20171120Dauphinais Direct - Redacted.pdf

RECENED
2(BT NOV 20 PM 3:22
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
IN THE MATTER OF THE APPLICATION )
OF ROCKY MOUNTAIN POWER FOR A )CERTIFICATE OF PUBLIC )CASE NO.PAC-E-17-07
CONVENIENCE AND NECESSITY AND )BINDING RATEMAKING TREATMENT )
FOR NEW WIND AND TRANSMISSION )
FACILITIES )
REDACTED Direct Testimony and Exhibits Of
James R.Dauphinais
On Behalf of
Monsanto Company
November 20,2017
Project 10465
CONFIDENTIAL
SUBJECT TO PROTECTIVE ORDER IN CASE NO.PAC-E-17-07
ORIGlNAL
ROCKY MOUNTAIN POWER
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
CASE NO.PAC-E-17-07
Table of Contents to the
Direct Testimony of James R.Dauphinais
I.INTRODUCTION AND SUMMARY................................................................................l
II.NEED FOR THE TRANSMISSION PROJECTS...............................................................3
III.RISKS ASSOCIATED WITH THE TRANSMISSION PROJECTS .................................6
A.Power System Analysis Study Risk ...................................................................................7
B.Permitting Risks................................................................................................................10
C.Construction Cost Risks ...................................................................................................ll
D.Third-Party Transmission Customer Revenue Risk.........................................................l1
Exhibits:
Exhibit 204:Qualifications of James R.Dauphinais
Exhibit 205:RMP Responseto WIEC 2.2 in Docket No.20000-520-EA-17of the
Wyoming Public Service Commission
Exhibit 206:RMP Responseto WIEC Informal Data Request 1.1 in Docket No.20000-
520-EA-17 of the Wyoming Public Service Commission
Exhibit 207:RMP Responseto WIEC 7.1 in Docket No.20000-520-EA-17of the
Wyoming Public Service Commission
Exhibit 208:RMP Responseto WIEC 7.3 in Docket No.20000-520-EA-17of the
Wyoming Public Service Commission
REDACTED Dauphinais,Di -i
Monsanto Company
ROCKY MOUNTAIN POWER
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
CASE NO.PAC-E-17-07
Direct Testimony of James R.Dauphinais
l I.INTRODUCTION AND SUMMARY
2 Q.PLEASE STATE YOUR NAME AND BUSINESS ADDRESS.
3 A.James R.Dauphinais.My business address is 16690 Swingley Ridge Road,Suite 140,
4 Chesterfield,Missouri 63017.
5 Q.WHAT IS YOUR OCCUPATION?
6 A.I am a consultant in the field of public utility regulation and a managing principal with
7 the firm of Brubaker &Associates,Inc.,which specializes in energy,economic,and
8 regulatoryconsulting.
9 Q.PLEASE DESCRIBE YOUR EDUCATIONAL BACKGROUND AND
10 EXPERIENCE.
11 A.A thorough description of my educational background and experience is set forth in
12 Exhibit No.204.
13 Q.ON WHOSE BEHALF ARE YOU TESTIFYING IN THIS PROCEEDING?
14 A.I am testifying on behalf of Monsanto Company ("Monsanto").Monsanto operates
15 facilities within the service territory of PacifiCorp d/b/a Rocky Mountain Power ("RMP,"
16 "PacifiCorp,"or the "Company"),from whom it purchases electricity and energy
17 services.
REDACTED Dauphinais,Di -I
Monsanto Company
l Q.WHAT IS THE PURPOSE OF YOUR TESTIMONY?
2 A.I respond to the Transmission Projects'portion of RMP's Combined Projects2 in this
3 proceeding.I specifically address the questions of the need and risks associated with the
4 proposed Transmission Projects.My colleagues,Kathryn Iverson and Nicholas L.
5 Phillips,are also presenting direct testimony on behalf of Monsanto regarding the
6 ratemaking treatment and the economic analysis of the Combined Projects.
7 My silence with respect to any position taken by RMP in its application or direct
8 testimony in this proceeding should not be interpreted as an endorsement of that position.
9 Q.PLEASE SUMMARIZE YOUR CONCLUSIONS.
10 A.The Transmission Projects are not needed to provide reliable electric service at lowest
11 reasonable cost.While RMP identified some potential reliability and operational
12 flexibility benefits from the Transmission Projects,the Company also admits that those
13 benefits alone would not justify construction of the Transmission Projects.As a result,
14 the Transmission Projects can only be justified if the forecasted net benefits and risks
15 associated with the Combined Projects are such that pursuit of the Combined Projects is
16 in the public interest for RMP's retail customers in Idaho.
17 I have identified several specific risks associated with the Transmission Projects,
18 which are factored into Mr.Phillips'conclusions and recommendations with respect to
19 the Combined Projects.These include:
20 1.Risks to Transmission Project construction costs or the receipt of Production
21 Tax Credits ("PTCs")for the Wind Projects due to the incomplete nature of
22 RMP's power system analysis studies for the Transmission Projects;
*The "Transmission Projects"consist of the Aeolus-to-Bridger/Anticline Line and 230 kV
Network Upgrades proposed by RMP in this proceeding.
2 The "Combined Projects"consist of the Transmission Projects and the four new Wyoming wind
resources with a total capacity of 860 megawatts (collectively,the "Wind Projects")that RMP proposed
in this proceeding.
REDACTED Dauphinais,Di -2
Monsanto Company
l 2.Risks to Transmission Project construction costs or the receipt of PTCs due to
2 incomplete permitting of the Transmission Projects;
3 3.Risks to Transmission Project construction costs or the receipt of PTCs due to
4 construction risks;and
5 4.Risks related to actually recovering a portion of the revenue requirement
6 associated with the Transmission Projects from PacifiCorp's third-party
7 transmission customers.
8 H.NEED FOR THE TRANSMISSION PROJECTS
9 Q.PLEASE DESCRIBE THE TRANSMISSION PROJECTS.
10 A.The Transmission Projects consist of the "Aeolus-to-Bridger/Anticline Line"and certain
11 "230 kV Network Upgrades."The Aeolus-to-Bridger/Anticline Line consists of the
12 followingthree components:
13 The 140-mile Aeolus-to-Anticline 500 kV transmission line including new
14 substations at Aeolus and Anticline;
15 The five-mile Anticline-to-Jim Bridger 345 kV transmission line including
16 modifications at the existing Jim Bridger substation to connect the line there;
17 and
18 Installation of a voltage control device at Latham substation.3
19 The 230 kV Network Upgrades consists of:
20 A new 16-mile 230 kV transmission line that would parallel an existing
21 230 kV transmission line from Shirley Basin substation to the proposed
22 Aeolus substation including modifications at the existing Shirley Basin
23 substation;
24 The reconstruction of four miles of an existing 230 kV transmission line
25 between the proposed Aeolus substation and the Freezeout substation
26 including modifications as required at the Freezeout substation;and
3 RMP Application at p.2.
REDACTED Dauphinais,Di -3
Monsanto Company
1 The reconstruction of 14 miles of an existing 230 kV transmission line
2 between the Freezeout substation and the Standpipe substation including
3 modifications as required at Freezeout and Standpipe substations.4
4 RMP identified an estimated cost of million for the Aeolus-to-
5 Bridger/Anticline Line and million for the 230 kV Network Upgrades.S The
6 entire cost of the Aeolus-to-Bridger/Anticline Line would be initially paid for by RMP.6
7 The cost of the 230 kV Network Upgrades would be re-assessed and assigned to the wind
8 resource facilities selected via RMP's 2017R Request for Proposals ("2017R RFP")
9 process under their respective interconnection agreements.'RMP expects to roll the cost
10 of the Transmission Projects into its formula transmission rates under the Company's
11 FERC-filed Open Access Transmission Tariff ("OATT"),which would allow RMP to
12 recover a portion of the cost of the Transmission Projects from its third-party
13 transmission customers."RMP expects the proposed Transmission Projects will increase
14 transmission capacity across Wyoming by 750 MW and allow RMP to interconnect
15 approximately 1,270 MW of wind resources,including the 860 MW of Wind Projects."
16 In order to obtain the full benefits of PTCs for the Wind Projects,the Transmission
17 Projects needs to be in service by no later than December 31,2020.'°
18 Q.WOULD RMP NEED THE TRANSMISSION PROJECTS IF IT WERE NOT
19 PURSUING THE WIND PROJECTS?
20 A.No.RMP has not identified a reliability need or an economic need that would justify the
21 Transmission Projects without the Wind Projects.To the contrary,RMP's President and
4
6 Direct Testimony of Rick A.Vail at p.12.
7 Id.at p.13.
"Id.at pp.15-17.
Id.at p.4.
io Id.at p.13.
REDACTED Dauphinais,Di -4
Monsanto Company
l Chief Executive Officer admits the Transmission Projects and Wind Projects are
2 mutually dependent on one another."The Wind Projects rely on the Transmission
3 Projects for interconnection to the transmission system and the Transmission Projects are
4 supported by the key attributes of the Wind Projects.12 While RMP claims the
5 Transmission Projects alone would be beneficial in reducing existing transmission
6 congestion and reducing capacity and energy losses during outage and non-outage
7 conditions,"RMP admits the Transmission Projects are not necessary for RMP to meet
8 the NERC Standards for the Bulk Electric System and WECC Regional Standards and
9 Criteria.14 Furthermore,RMP admits the Transmission Projects are not economic
10 without the Wind Projects.
11 For all of the foregoing reasons,RMP has not demonstrated that,without the
12 Wind Projects,the Transmission Projects are needed to provide reliable electric service at
13 lowest reasonable cost or would otherwise be in the public interest.
14 Q.IN CONJUNCTION WITH THE WIND PROJECTS,HAS RMP SHOWN THE
15 TRANSMISSION PROJECTS ARE NECESSARY FOR THE RELIABLE
16 PROVISION OF ELECTRIC SERVICE AT LOWEST REASONABLE COST?
17 A.No.To do so,RMP would have to demonstrate that it needs to add the Wind Projects in
18 order to provide reliable electric service at lowest reasonable cost.It has not done so.
19 Instead,RMP is proposing the Wind Projects essentially as an opportunity investment
20 under which retail customers would bear the rewards of any net benefits and the risks of
21 any net costs from the Combined Projects,while paying RMP for the cost of the
"Direct Testimony of Cindy A.Crane at p.3.
12 Id"Direct Testimony of Rick A.Vail at pp.17-23.
14 Id.at pp.19 and 22-23.
"Direct Testimony of Cindy A.Crane at p.10.
REDACTED Dauphinais,Di -5
Monsanto Company
l Combined Projects plus a regulated return.This disproportionately assigns risk to RMP's
2 retail customers versus the risk to RMP from the Combined Projects.For all of the
3 foregoing reasons,and as discussed in more detail by Mr.Phillips,a CPCN for the
4 Combined Projects should only be granted by the Commission if the forecasted net
5 benefits and risks associated with the Combined Projects for RMP's retail customers in
6 Idaho are such that it is in the public interest to do so.Mr.Phillips concludes that they do
7 not do so.However,if the Commission grants a CPCN for the Combined Projects,Mr.
8 Phillips recommends conditions to that approval to increase the likelihood of net benefits
9 for customers in Idaho.
10 III.RISKS ASSOCIATED WITH THE TRANSMISSION PROJECTS
11 Q.PLEASE RESTATE THE RISKS ASSOCIATED WITH THE TRANSMISSION
12 PROJECTS THAT YOU HIGHLIGHTED AT THE OUTSET OF YOUR
13 TESTIMONY.
14 A.These risks include:
15 1.Risk to Transmission Project construction costs or the receipt of PTCs for the
16 proposed Wind Projects in this proceeding due to the incomplete nature of RMP's
17 power system analysis studies for the Transmission Projects;
18 2.Risks to Transmission Project construction costs or the receipt of PTCs due to the
19 incomplete permitting of the Transmission Projects;
20 3.Risks to Transmission Project construction costs or the receipt of PTCs due to
21 construction risks;and
22 4.Risk related to actually recovering a portion of the revenue requirement associated
23 with the Transmission Projects from PacifiCorp's third-party transmission customers.
REDACTED Dauphinais,Di -6
Monsanto Company
l A.Power System Analysis Study Risk
2 Q.WHAT POWER SYSTEM ANALYSIS STUDIES HAS PACIFICORP
3 PERFORMED FOR THE TRANSMISSION PROJECTS?
4 A.RMP has not completed the powerflow,dynamic stability,stiffness factor analysis,Sub-
5 Synchronous Resonance,and voltage stability studies for the Transmission Projects.In
6 July 2017,RMP was asked to provide a complete copy of all powerflow and dynamic
7 stability analyses and studies that PacifiCorp has performed,or had performed on its
8 behalf,to determine the expected incremental transfer capability of 750 MW and
9 interconnection capability of 1,270 MW for the Transmission Projects.l6 In response,
10 RMP provided a WECC study from November 24,2010,and indicated that an additional
11 study was underway which would not be completed until six months before the
12 Transmission Projects are projected to enter service in December 2020.A copy of the
13 response to WIEC 2.2 data request response (excluding the appendices to the November
14 24,2010 WECC study report)is provided in Exhibit 205.
15 Subsequently,during a September 25,2017,Technical Conference held in the
16 Wyoming New Wind/Transmission Docket,RMP indicated that there were additional
17 transmission studies that will be conducted which the Company thought were identified
18 in RMP Exhibit RAV-10.However,RMP Exhibit RAV-10 did not identify those
19 additional transmission studies.Following the Wyoming technical conference,and in
20 response to WIEC Informal Data Request 1.1,RMP identified those additionalstudies on
21 October 12,2017.A complete copy of that response is included as Exhibit 206.RMP's
16 Wyoming Public Service Commission,Docket No.20000-520-EA-17 ("Wyoming New
Wind/TransmissionDocket"),Data Request WIEC 2.2.WIEC stands for "Wyoming Industrial Energy
Consumers."In Monsanto Data Request No.2 to RMP,Monsanto requested a copy of all data requests
and responses from the Wyoming New Wind/TransmissionDocket in discoveryin this proceeding.
REDACTED Dauphinais,Di -7
Monsanto Company
l response indicates the projected completion dates for these additional transmission
2 studies run from October 31,2017,to November 24,2017,to January 31,2018,to May
3 2018,to dates well into 2019.
4 Q.IN YOUR EXPERIENCE,IS IT UNUSUAL FOR A UTILITY TO RELY ON A
5 SEVEN YEAR OLD TRANSMISSION STUDY TO SUPPORT THE TRANSFER
6 AND INTERCONNECTION CAPABILITY OF A PROPOSED TRANSMISSION
7 PROJECT?
8 A.Yes.Based on my experience,if the original study for a project is stale,such as the case
9 with the November 24,2010 WECC Study Report,refreshed studies are usually
10 completed before a CPCN application is made.
11 Q.HAS RMP PROVIDED ANY ADDITIONAL POWER SYSTEM ANALYSIS
12 STUDY RESULTS FOR THE TRANSMISSION PROJECTS BESIDES THE
13 NOVEMBER 24,2010 STUDY REPORT?
14 A.Yes.On October 13,2017,in response to Data Request WIEC 7.1 in the Wyoming New
15 Wind/Transmission Docket,RMP provided a preliminary study report dated October
16 2017 titled "Aeolus West Transmission Path Transfer Capability Assessment."I have
17 included a complete copy of this response (excluding the appendices to the preliminary
18 study report and RMP's highly confidential power flow models)in Exhibit 207.In
19 response to WIEC Informal Data Request 1.1,RMP provided the following explanation
20 with respect to why it had drafted the preliminary study report:
21 "Due to interest shown by various stakeholders (via data requests)to
22 review the D.2 Project preliminary study findings,a preliminary study
23 report for the project is currently being drafted.The report should be
24 available by October 13,2017."
REDACTED Dauphinais,Di -8
Monsanto Company
l Q.WHAT DOES THE PRELIMINARY STUDY REPORT INDICATE WITH
2 RESPECT TO THE EXPECTED 750 MW OF INCREMENTAL TRANSFER
3 CAPABILITY AND 1,270 MW OF INTERCONNECTION CAPABILITY FOR
4 THE TRANSMISSION PROJECTS?
5 A.The study report indicates preliminary powerflow studies demonstrate that east to west
6 transfer levels across Wyoming would effectively increase by 817.5 MW.However,the
7 study report also indicated the need for dynamic voltage support at Latham Substation
8 and three different Remedial Action Schemes ("RAS").While these additional
9 reinforcements were identified in RMP's direct testimony in this proceeding,RMP has
10 still not completed its studies to determine the specifics of these reinforcements.In
11 addition,the preliminary study report provides no information with respect to the
12 expected 1,270 MW of additional interconnection capability that RMP expects to receive
13 from the Transmission Projects.
14 Q.PLEASE EXPLAIN THE CONCERNS YOU HAVE WITH THE STATUS OF
15 RMP'S POWER SYSTEM ANALYSES STUDIES FOR THE TRANSMISSION
16 PROJECTS.
17 A.The incomplete nature of the studies exposes RMP to the risk that something in the
18 results of those to be completed studies could lead to:(i)the expected 750 MW of
19 incremental transfer capability and/or 1,270 MW of expect interconnection capability
20 either not being realized or delayed;or (ii)the Transmission Projects having greater costs
21 than forecasted by RMP.Failure or delay in the full realization of the expected
22 incremental transfer capability and interconnection capability could lead to the Wind
23 Projects not receiving their full PTCs.This could significantly reduce the forecasted
REDACTED Dauphinais,Di -9
Monsanto Company
l gross economic benefit value of the Combined Projects.Additional costs for the
2 Transmission Projects would increase the total cost for the Combined Projects.In either
3 case,the forecasted net benefits of the Combined Projects would be reduced -potentially
4 down to a net cost for RMP's retail customers.
5 B.PermittingRisks
6 Q.HAS RMP ACQUIRED ALL OF THE PERMITS IT NEEDS FOR THE
7 TRANSMISSION PROJECTS?
8 A.No.RMP has obtained a federal right-of-way permit from the Bureau of Land
9 Management."However,RMP has yet to receive a Wyoming Industrial Siting Permit or
10 a Conditional Use Permit from Carbon County.RMP will not apply for the Wyoming
11 Industrial Siting Permit until August 2018."It will not apply for its Conditional Use
12 Permit form Carbon County until the second half of 2018.
13 Q.PLEASE EXPLAIN THE CONCERNS YOU HAVE WITH THE STATUS OF
14 RMP'S PERMITTING FOR THE TRANSMISSION PROJECTS.
15 A.Like with the incomplete status of RMP's power system analysis studies for the
16 Transmission Projects,the incomplete nature of the permitting process exposes RMP to
17 the risk that something unexpected may result in the Transmission Projects having a
18 greater than forecasted cost or the Transmission Projects being delayed.As I have noted,
19 a delay in the completion of the Transmission Projects could lead to the Wind Projects
20 not receiving their full PTCs --significantly reducing the forecasted gross economic
21 benefit value of the Combined Projects.And additional costs for the Transmission
17 Direct Testimony of Rick A.Vail at p.37.
"Gateway Transmission and New Wind,Technical Conference,(Wyoming PSC Docket No.
20000-520-EA-2017),September 25,2017 at Slide 19."Id.
REDACTED Dauphinais,Di -10
Monsanto Company
l Projects would increase the total cost for the Combined Projects.Any unexpected
2 increase in the cost of the Transmission Projects or Combined Projects,or the loss of the
3 full PTC value,would reduce the forecasted net benefits and could potentially result in a
4 net cost for RMP's retail customers.
5 C.Construction Cost Risks
6 Q.PLEASE EXPLAIN THE CONSTRUCTION COST RISKS ASSOCIATED WITH
7 THE TRANSMISSION PROJECTS.
8 A.In response to WIEC Data Request 7.3 in the Wyoming New Wind/Transmission Docket,
9 RMP identified that the cost estimates for the Transmission Project have an accuracy of
10 +/-15%given the early nature of the estimate and finalization of the scope and approach.
11 The upper end of this range would add million to the estimated costs of the
12 Combined Projects.20 I have provided a complete copy of this data request response in
13 Exhibit 208.As Mr.Phillips explains,upward deviations in the cost of the Transmission
14 Projects would reduce the forecasted net benefit of the Combined Projects and could
15 result in a net cost for RMP's retail customers.
16 D.Third-Party Transmission Customer Revenue Risk
17 Q.PLEASE EXPLAIN WHAT THIRD-PARTY TRANSMISSION CUSTOMER
18 REVENUES ARE AND WHY THEY ARE OF CONCERN.
19 A.Third-party transmission customer revenues are revenues that RMP collects from its
20 unbundled wholesale transmission customers under its OATT.RMP expects that it will
21 be permitted to roll the costs of the Transmission Projects into its OATT rates as the
22 projects enter service through the annual update of the inputs of its formula transmission
20 million ~15%x (million +million).
REDACTED Dauphinais,Di -11
Monsanto Company
l rate under its OATT.21 In total,RMP expects its third-party transmission customers will
2 cover approximately 12%of the total revenue requirement of the Transmission ProjectS22
3 and has factored the revenues it expects to recover from these customers into is net
4 benefit analysis for the Combined Projects.
5 My concern is that there is a risk that one or more of RMP's third-party
6 transmission customers could successfully challenge the rolling into RMP's OATT rates
7 of the cost of the Transmission Projects.The reason this risk exists is that,while the
8 Transmission Projects would be fully integrated into RMP's transmission network,they
9 are only being pursued by RMP to integrate and deliver power from the Wind Projects.
10 RMP has admitted it would not be pursuing the Transmission Projects without the Wind
11 Projects.Furthermore,the incremental transfer capacity and interconnection capability of
12 the Transmission Projects will likely be fully consumed by the Wind Projects.As a
13 result,it could be argued that the Transmission Projects will only provide a benefit to
14 RMP's native load customers,which could in turn result in RMP being barred from
15 rolling the cost of the Transmission Projects into its OATT rates.If that were to happen,
16 RMP would not receive any third-party transmission customer revenues for the
17 Transmission Projects and RMP might try to seek to recover the revenues it was
18 expecting from its third-party transmission customers from its retail customers instead.
19 As Mr.Phillips explains,removing the 12%OATT revenue assumption increases the
20 likelihood that the Combined Projects will result in a net cost for RMP's retail customers.
21 Direct TOStimony of Rick A.Vail at pp.16-17.
22 Direct Testimonyof Rick T.Link at p.24.
REDACTED Dauphinais,Di -12
Monsanto Company
l Q.RMP ARGUES THAT FERC PRECEDENT SUPPORTS ROLLING THE COSTS
2 OF THE TRANSMISSION PROJECTS INTO THE COMPANY'S OATT RATES.
3 HOW DO YOU RESPOND?
4 A.In general,FERC precedent supports rolling the costs of networked transmission facilities
5 into OATT rates.However,there can be exceptions especially when the network
6 transmission upgrades are for the benefit of the transmission provider's native load
7 customers alone.Specifically,in Northeast Utilities Service Company,62 FERC ¶
8 61,294 (1993),the FERC did not permit Northeast Utilities Service Company to include
9 the cost of certain transmission support payments principally associated with its share of
10 certain High Voltage Direct Current ("HVDC")transmission facilities because they were
11 dedicated to providing the delivery of purchased power to the native load customers of
12 the Northeast Utilities Operating Companies and not available for third-party use.In that
13 decision,the FERC indicated:
14 We agree generally with the intervenors on this issue.NU proposes to
15 include as a component of its transmission cost of service payments it
16 makes to obtain third-party transmission service from other utilities,e.g.,
17 to transmit its purchases from the Yankee companies and to support
18 transmission facilities used to import power from Canada.These expenses
19 are simply a cost of obtaining generation resources that are located on the
20 transmission grid of another utility.Indeed,if the generation seller obtains
21 the necessary third-party transmission services and includes these
22 expenses as part of the overall power sale price,there would be no
23 controversy that these expenses should be fully allocated to NU's own
24 power sale customers.The fact that NU,the power purchaser,separately
25 contracted for service over transmission facilities owned and operated by
26 third parties in order to import remote generation resources provides no
27 basis for allocating these costs to NU's transmission customers.Of course,
28 if NU uses facilities owned by third parties as an NU grid facility and uses
29 the facilities on a day-to-day basis to transmit power for tariff customers,
30 the third-party costs would be allocable to tariff customers,e.g.,payments
31 to lease a line owned by a third party but operated as part of NU's
32 transmission grid.However,as NU explains,most--if not all--of the third
33 party transmission costs at issue here involve payments to import remote
REDACTED Dauphinais,Di -13
Monsanto Company
l generating resources.Accordingly,these expenses are not incurred in
2 order to provide transmission service to tariff customers and NU will be
3 directed to exclude the expenses from the formula rate.23
4 While RMP would own the Transmission Projects,it is important to note that:(i)RMP
5 has indicated it would not being pursuing the Transmission Projects without the Wind
6 Projects;(ii)the incremental transfer capability expected to be provided by the
7 Transmission Projects is less than the nameplate capability of the new Wind Projects
8 (750 MW versus 860 MW);and (iii)the interconnection capability expected to be
9 provided Transmission Projects (1,270 MW)could potentially be fully consumed by
10 2017R RFP results.As a result,the Transmission Projects may leave nothing for third-
11 party transmission customers but a share of their costs.It is this possibility that places
12 RMP at risk with respect to receiving those third-party transmission customer revenues
13 given FERC's precedent involving Northeast Utilities Service Company.
14 Q.DO YOU HAVE ANY RECOMMENDATIONS REGARDING HOW THESE
15 RISKS SHOULD BE ADDRESSED IN ORDER TO PROTECT CUSTOMERS?
16 A.If the Commission approves a CPCN for the Combined Projects,that approval should
17 include protections to increase the likelihood that customers will benefit from the
18 Company's proposal.The specific protections recommended by Monsanto are discussed
19 in detail by Mr.Phillips.
20 Q.DOES THIS CONCLUDE YOUR DIRECT TESTIMONY?
21 A.Yes,it does.
MDoc\Shares\ProlawDocs\MED\l0465.Confidential\Testimony-BAI\333473docx
23 Northeast Utilities Service Company,62 FERC ¶61,294 (1993)at Section IV.A.6.
REDACTED Dauphinais,Di -14
Monsanto Company
Monsanto Exhibit No.204
Case No.PAC-E-17-07
Page 1 of 5
QUALIFICATIONSOF JAMES R.DAUPHINAIS
1 Q.PLEASE STATE YOUR NAME AND BUSINESS ADDRESS.
2 A.James R.Dauphinais.My business address is 16690 Swingley Ridge Road,Suite 140,
3 Chesterfield,MO 63017,USA.
4 Q.PLEASE STATE YOUR OCCUPATION.
5 A.I am a consultant in the field of public utility regulation and a Managing Principal with
6 the firm of Brubaker &Associates,Inc.("BAI"),energy,economic and regulatory
7 consultants.
8 Q.PLEASE SUMMARIZE YOUR EDUCATIONAL BACKGROUND AND
9 EXPERIENCE.
10 A.I graduated from Hartford State Technical College in 1983 with an Associate's Degree in
11 Electrical Engineering Technology.Subsequent to graduation I was employed by the
12 Transmission Planning Department of the Northeast Utilities Service Company'as an
13 Engineering Technician.
14 While employed as an Engineering Technician,I completed undergraduate studies
15 at the University of Hartford.I graduated in 1990 with a Bachelor's Degree in Electrical
16 Engineering.Subsequent to graduation,I was promoted to the position of Associate
17 Engineer.Between 1993 and 1994,I completed graduate level courses in the study of
18 power system transients and power system protection through the Engineering Outreach
19 Program of the University of Idaho.By 1996 I had been promoted to the position of
20 Senior Engineer.
'In 2015,Northeast Utilities changed its name to Eversource Energy.
Monsanto Exhibit No.204
Case No.PAC-E-17-07
Page 2 of 5
1 In the employment of the Northeast Utilities Service Company,I was responsible
2 for conducting thermal,voltage and stability analyses of the Northeast Utilities'
3 transmission system to support planning and operating decisions.This involved the use
4 of load flow,power system stability and production cost computer simulations.It also
5 involved examination of potential solutions to operational and planning problems
6 including,but not limited to,transmission line solutions and the routes that might be
7 utilized by such transmission line solutions.Among the most notable achievements I had
8 in this area include the solution of a transient stability problem near Millstone Nuclear
9 Power Station,and the solution of a small signal (or dynamic)stability problem near
10 Seabrook Nuclear Power Station.In 1993 I was awarded the Chairman's Award,
11 Northeast Utilities'highest employee award,for my work involvingstability analysis in
12 the vicinity of Millstone Nuclear Power Station.
13 From 1990 to 1996,I represented Northeast Utilities on the New England Power
14 Pool Stability Task Force.I also represented Northeast Utilities on several other
15 technical working groups within the New England Power Pool ("NEPOOL")and the
16 Northeast Power Coordinating Council ("NPCC"),including the 1992-1996 New York-
17 New England Transmission Working Group,the Southeastern Massachusetts/Rhode
18 Island Transmission Working Group,the NPCC CPSS-2 Working Group on Extreme
19 Disturbances and the NPCC SS-38 Working Group on Interarea Dynamic Analysis.This
20 latter working group also included participation from a number of ECAR,PJM and
21 VACAR utilities.
22 From 1990 to 1995,I also acted as an internal consultant to the Nuclear Electrical
23 Engineering Department of Northeast Utilities.This included interactions with the
Monsanto Exhibit No.204
Case No.PAC-E-17-07
Page 3 of 5
1 electrical engineering personnel of the Connecticut Yankee,Millstone and Seabrook
2 nuclear generation stations and inspectors from the Nuclear Regulatory Commission
3 ("NRC").
4 In addition to my technical responsibilities,from 1995 to 1997,I was also
5 responsible for oversight of the day-to-day administration of Northeast Utilities'Open
6 Access Transmission Tariff.This included the creation of Northeast Utilities'pre-FERC
7 Order No.889 transmission electronic bulletin board and the coordination of Northeast
8 Utilities'transmission tariff filings prior to and after the issuance of Federal Energy
9 Regulatory Commission ("FERC"or "Commission")FERC Order No.888.I was also
10 responsible for spearheading the implementation of Northeast Utilities'Open Access
11 Same-Time Information System and Northeast Utilities'Standard of Conduct under
12 FERC Order No.889.During this time I represented Northeast Utilities on the Federal
13 Energy Regulatory Commission's "What"Working Group on Real-Time Information
14 Networks.Later I served as Vice Chairman of the NEPOOL OASIS Working Group and
15 Co-Chair of the Joint Transmission Services Information Network Functional Process
16 Committee.I also served for a brief time on the Electric Power Research Institute
17 facilitated "How"Working Group on OASIS and the North American Electric Reliability
18 Council facilitatedCommercial Practices Working Group.
19 In 1997 I joined the firm of Brubaker &Associates,Inc.The firm includes
20 consultants with backgrounds in accounting,engineering,economics,mathematics,
21 computer science and business.Since my employment with the firm,I have filed or
22 presented testimony before the Federal Energy Regulatory Commission in Consumers
23 Energy Company,Docket No.OA96-77-000;Midwest Independent Transmission
Monsanto Exhibit No.204
Case No.PAC-E-17-07
Page 4 of 5
1 System Operator,Inc.,Docket No.ER98-1438-000;Montana Power Company,Docket
2 No.ER98-2382-000;Inquiry Concerning the Commission's Policy on Independent
3 System Operators,Docket No.PL98-5-003;SkyGen Energy LLC v.Southern Company
4 Services,Inc.,Docket No.ELOO-77-000;Alliance Companies,et al.,Docket No.ELO2-
5 65-000,et al.;Entergy Services,Inc.,Docket No.ER01-2201-000;Remedying Undue
6 Discrimination through Open Access Transmission Service,Standard Electricity Market
7 Design,Docket No.RM01-12-000;Midwest Independent Transmission System
8 Operator,Inc.,Docket No.ERl0-1791-000;NorthWestern Corporation,Docket No.
9 ERl0-l l38-001,et al.;Illinois Industrial Energy Consumers v.Midcontinent
10 Independent System Operator,Inc.,Docket No.ELl5-82-000;and Midcontinent
11 Independent System Operator,Inc.,Docket No.ERl6-833-000 I have also filed or
12 presented testimony before the Alberta Utilities Commission,Colorado Public Utilities
13 Commission,Connecticut Department of Public Utility Control,the Florida Public
14 Service Commission,Illinois Commerce Commission,the Indiana Utility Regulatory
15 Commission,the Iowa Utilities Board,the Kentucky Public Service Commission,the
16 Louisiana Public Service Commission,the Michigan Public Service Commission,the
17 Missouri Public Service Commission,the MontanaPublic Service Commission,the New
18 Mexico Public Regulation Commission,the Council of the City of New Orleans,the
19 Oklahoma Corporation Commission,the Public Utility Commission of Texas,the
20 Wisconsin Public Service Commission and various committees of the Missouri State
21 Legislature.This testimony has been given regarding a wide variety of issues including,
22 but not limited to,ancillary service rates,avoided cost calculations,certification of public
23 convenience and necessity,cost allocation,fuel adjustment clauses,fuel costs,generation
Monsanto Exhibit No.204
Case No.PAC-E-17-07
Page 5 of 5
1 interconnection,interruptible rates,market power,market structure,off-system sales,
2 prudency,purchased power costs,resource planning,rate design,retail open access,
3 standby rates,transmission losses,transmission planningand transmission line routing.
4 I have also participated on behalf of clients in the Southwest Power Pool
5 Congestion Management System Working Group,the Alliance Market Development
6 Advisory Group and several committees and working groups of the Midcontinent
7 Independent System Operator,Inc.("MISO"),including the Congestion Management
8 Working Group,Economic Planning Users Group,Loss of Load Expectation Working
9 Group,Regional Expansion,Criteria and Benefits Working Group and Resource
10 Adequacy Subcommittee (formerly the Supply Adequacy Working Group).I am
11 currently a member of the MISO Advisory Committee in the end-use customer sector on
12 behalf of a group of industrial end-use customers in Illinois and a group of industrial end-
13 use customers in Texas.I am also the past Chairman of the Issues/Solutions Subgroup of
14 the MISO Revenue Sufficiency Guarantee ("RSG")Task Force.
15 In 2009,I completed the University of Wisconsin-Madison High Voltage Direct
16 Current ("HVDC")Transmission course for Planners that was sponsored by MISO.I am
17 a member of the Power and Energy Society ("PES")of the Institute of Electrical and
18 Electronics Engineers ("IEEE").
19 In addition to our main office in St.Louis,the firm also has branch offices in
20 Phoenix,Arizona and Corpus Christi,Texas.
Doc\Shares\ProlawDocs\MED\10470\Testimony-BAI\332533.doex
Monsanto Exhibit No.205
Case No.PAC-E-17-07
20000-520-EA-17/Rocky Mountain Power Page 1 of 49
August 7,2017
WIEC Data Request 2.2
WIEC Data Request 2.2
Referring to Mr.Link's direct testimony at page 8:
(a)Please provide a complete copy of all power flow and dynamic-stabilityanalyses and
studies that PacifiCorp has performed,or had performed on its behalf,to determine
the incremental transfer capabilityof the proposed new transmission line will be 750
MW and it could enable up to 1,270 MW of new resource interconnections.
(b)Please provide a complete copy of all PSS/E power flow and dynamic-stabilityresults
that underlie the analyses and studies provided in responseto subpart (a).
(c)Please provide an electronic copy of all Siemens PTI PSS/E and MUST monitoring,
contingency,subsystem files,PSAS,IPLAN and Python files utilized to perform the
analyses and studies provided in responseto subpart (a).
(d)Please provide in "sav"format a complete copy of the Siemens PSS/E power flow
files used to perform the analyses and studies providedin responseto subpart (a).
When providing these files,please identify the version of PSS/E from which they
were produced.
(e)Please provide a complete copy in electronic format of all Microsoft Excel workbook
and worksheets used to compile,process,or analyze the results from the analyses and
studies provided in responseto subpart (a)with all formulae,links,and underlying
workbooks and worksheets intact.
Response to WIEC Data Request 2.2
(a)Please refer to Attachment WIEC 2.2,which provides the Western Electricity
Coordinating Council's (WECC)path rating studies of Energy Gateway West,which
included the Aeolus West transmission path.The Aeolus West path was granted
Phase 3 status by the WECC planning coordination committee (PCC)January 5,
2011.
North American Electric Reliability Corporation (NERC)FAC-013-2 transmission
assessment studies are currently underway,the completed studies will be finalized in
2020.System operating limit (SOL)studies required by Peak Reliability will be
completed six months prior to the new Aeolus -Bridger/Anticline line going in-
service in December 2020.
(b)Please see the responseto subpart (a)above.
(c)Please see the responseto subpart (a)above.
(d)Please see the responseto subpart (a)above.
(e)Please see the responseto subpart (a)above.
Monsanto Exhibit No.205
Case No.PAC-E-17-0720000-520-EA-17/Rocky MountainPower Page 2 of 49
August 7,2017
WIEC Data Request 2.2
Respondent:Craig Quist
Witness:Rick Link
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 3 of 49
Energy Gateway Project -Stage 1
Bridger /Anticline West (New Path 19)
Path C (New Path 20)Southbound
Aeolus West (New Path)
Phase 2 Path Rating Report
Submitted by
WECC Phase 2 -Bridger Area Study Group
Date;
November 24,2010
Revision 5.0
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 4 of 49
Executive Summary 5
1.Introduction 6
1.1.Project Description 6
1.2.Plan of Service 6
1.3.Planned Operating Date 6
2.Transfer Capability 6
3.Study Methods and Standards 7
3.1.Steady-State Case Stressing 7
3.2.Post Transient 7
3.3.Reactive Margin 8
3.4.Transient Stability 8
3.5.Generation Drop via Remedial Action Schemes (RAS)8
4.Path Definitions 8
4.1.Aeolus West (New)8
4.2.Aeolus South (New)9
4.3.Bridger West 345 kV (Existing)9
4.4.Bridger /Anticline West (Modified)9
4.5.Path C (Existing -After completion of the Populus -Terminal Project)9
4.6.Monument-Naughton (Internal Path)10
4.7.West of Rock Springs /Firehole (InternalPath)10
5.Project Base Case Modifications 10
5.1.SVC Tie Line Modeling 10
5.2.Line and Transformer Rating Conflicts 10
5.3.Phase Shifter Tap Steps 10
5.4.SVDs to Shunt Conversions 10
5.5.Other System Modeling Changes /Corrections 10
5.6.PacifiCorp System Updates /Corrections 11
6.Path Studies 11
6.1.Aeolus West vs.Aeolus South 11
6.1.1.Base Case Development 11
6.1.2.Post-Transient Analysis 12
6.1.3.Reactive Margin Analysis 13
6.1.4.Transient Stability Analysis 13
6.2.Aeolus West vs.Bonanza West 14
6.2.1.Base Case Development 14
6.2.2.Post-Transient Analysis 14
6.2.3.Reactive Margin Analysis 15
6.2.4.Transient Stability Analysis 15
6.3.Aeolus West vs.Tot la 16
6.3.1.Base Case Development 16
6.3.2.Post-Transient Analysis 16
6.3.3.Reactive Margin Analysis 18
6.3.4.Transient Stability Analysis 18
6.4.Bridger /Anticline West vs.Aeolus South 19
6.4.1.Base Case Development 19
11/24/2010 Gateway West Project -Bridger Study Area Page 2 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 5 of 49
6.4.2.Post-Transient Analysis 19
6.4.3.Reactive Margin Analysis 20
6.4.4.Transient Stability Analysis 20
6.5.Bridger /Anticline West vs.Path C Southbound 21
6.5.1.Base Case Development 21
6.5.2.Post-Transient Analysis 21
6.5.3.Reactive Margin Analysis 22
6.5.4.Transient Stability Analysis 23
6.6.Bridger /Anticline West vs.Bonanza West 23
6.6.1.Base Case Development 23
6.6.2.Post-Transient Analysis 23
6.6.3.Reactive Margin Analysis 24
6.6.4.Transient Stability Analysis 24
6.7.Bridger /Anticline West vs.Idaho -Montana (Path 18)25
6.7.1.Base Case Development 25
6.7.2.Post-Transient Analysis 25
6.7.3.Reactive Margin Analysis 26
6.7.4.Transient Stability Analysis 27
6.8.Bridger /Anticline West vs.Monument -Naughton 27
6.8.1.Base Case Development 27
6.8.2.Post-Transient Analysis 27
6.8.3.Reactive Margin Analysis 29
6.8.4.Transient Stability Analysis 29
6.9.Bridger /Anticline West vs.Rock Springs /Firehole 29
6.9.1.Post-Transient Analysis 29
6.9.2.Reactive Margin Analysis 31
6.9.3.Transient Stability Analysis 31
6.10.Bridger /Anticline West with the MSTI Project 31
6.10.1.Base Case Development 31
6.10.2.Post-Transient Analysis 31
6.10.3.Reactive Margin Analysis 32
6.10.4.Transient Stability Analysis 33
6.11.Path C Southbound vs.Idaho -Montana(Path 18)33
6.11.1.Base Case Development 33
6.11.2.Post-Transient Analysis 33
6.11.3.Reactive Margin Analysis 35
6.11.4.Transient Stability Analysis 35
6.12.Path C Southbound vs.Bonanza West 35
6.12.1.Base Case Development 35
6.12.2.Post-Transient Analysis 36
6.12.3.Reactive Margin Analysis 38
6.12.4.Transient Stability Analysis 38
6.13.Path C Southbound with the MSTI Project 39
6.13.1.Base Case Development 39
6.13.2.Post-Transient Analysis 39
6.13.3.Reactive Margin Analysis 40
6.13.4.Transient Stability Analysis 40
11/24/2010 Gateway West Project -Bridger Study Area Page 3 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 6 of 49
6.14.Path C Southbound vs.Monument -Naughton 41
6.14.1.Base Case Development 41
6.14.2.Post-Transient Analysis 41
6.14.3.Reactive Margin Analysis 42
6.14.4.Transient Stability Analysis 42
6.15.Path C Southbound vs.Rock Springs -Firehole 42
6.15.1.Base Case Development 42
6.15.2.Post-Transient Analysis 43
6.15.3.Reactive Margin Analysis 44
6.15.4.Transient Stability Analysis 44
7.Contingencies Studied 44
8.Study Conclusions /Recommendations 45
Appendix 1 -Post-Transient and Dynamic Contingency Lists 48
Appendix 2 -Nomograms 52
Appendix 3 -Post-transient Results Tables 67
Appendix 4 -Dynamic Stability Results Tables 90
Appendix 5 -Gateway West Study Plan 110
Appendix 21 150
TSS Approved Exceptions to the NERC/WECC Standards 150
Appendix 21 -Pages C20 -C23 from TSS Accepted Exceptions to NERC/WECC
Standards
APPENDIX FILES;Located on Idaho Power's FTP Site at;https:\\fileexch.idahopower.com
Appendix 6-1;See file;Appendix_6-l.pdf Aeolus West vs.Aeolus South -Base Case &PT Plots
Appendix 6-2;See file;Appendix_6-2.pdf Aeolus West vs.Aeolus South -Dynamics plots
Appendix 7-1;See file;Appendix_7-1.pdf Aeolus West vs.Bonanza West -Base Case &PT Plots
Appendix 7-2;See file;Appendix_7-2.pdf Aeolus West vs.Bonanza West-Dynamics plots
Appendix 8-1;See file;Appendix_8-1.pdf Aeolus West vs.Tot la -Base Case &PT Plots
Appendix 8-2;See file;Appendix_8-2.pdf Aeolus West vs.Tot la-Dynamics plots
Appendix 9-1;See file;Appendix_9-l.pdf Bridger West vs.Aeolus South -Base Case &PT Plots
Appendix 9-2;See file;Appendix_9-1.pdf Bridger West vs.Aeolus South-Dynamics plots
Appendix 10-1;See file;Appendix_10-l.pdf Bridger West vs.Path C South -Base Case &PTPlots
Appendix 10-2;See file;Appendix_10-2.pdf Bridger West vs.Path C South-Dynamics plots
Appendix 11-1;See file;Appendix l l-1.pdf Bridger West vs.Bonanza West -Base Case &PT Plots
Appendix 11-2;See file;Appendix 11-2.pdf Bridger West vs.Bonanza West -Dynamicsplots
Appendix 12-1;See file;Appendix 12-1.pdf Bridger West vs.Idaho -Montana (18)Base Cas&PT Plots
Appendix 12-2;See file;Appendix_12-2.pdf Bridger West vs.Idaho -Montana (18)-Dynamics plots
Appendix 13-1;See file;Appendix_l3-1.pdf Bridger West vs.Monument-Naughton Base Cas&PT Plots
Appendix 13-2;See file;Appendix_13-2.pdf Bridger West vs.Monument -Naughton-Dynamics plots
Appendix 14-1;See file;Appendix_14-1.pdf Bridger West vs.Rock Spgs /FH-Base Case &PT Plots
Appendix 14-2;See file;Appendix 14-2.pdf Bridger West vs.Rock Spgs /Firehole-Dynamics plots
Appendix 15-1;See file;Appendix 15-1.pdf Bridger West vs.MSTI-Base Case &PT Plots
Appendix 15-2;See file;Appendix 15-2.pdf Bridger West vs.MSTI-Dynamics plots
Appendix 16-1;See file;Appendix_l6-l.pdf Path C South vs.Idaho-Montana (18)Base Casee PT Plots
Appendix 16-2;See file;Appendix_16-2.pdf Path C South vs.Idaho -Montana (18)-Dynamics plots
Appendix 17-1;See file;Appendix_17-l.pdf Path C South vs.Bonanza West-Base Case &PT Plots
Appendix 17-2;See file;Appendix_17-2.pdf Path C South vs.Bonanza West-Dynamics plots
Appendix 18-1;See file;Appendix_l8-1.pdf Path C South vs.MSTI-Base Case &PT Plots
Appendix 18-2;See file;Appendix_18-2.pdf Path C South vs.MSTI-Dynamics plots
Appendix 19-1;See file;Appendix_19-1.pdf Path C South vs.Monument-Naughtn-Base Case+PT Plots
Appendix 19-2;See file;Appendix 19-21.pdf Path C South vs.Monument -Naughton-Dynamics plots
Appendix 20-1;See file;Appendix_20-1.pdf Path C South vs.Rock Spgs /Firehole Base Case &PT Plots
Appendix 20-2;See file;Appendix_20-2.pdf Path C South vs.Rock Spgs /Firehole-Dynamics plots
11/24/2010 Gateway West Project -Bridger Study Area Page 4 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 7 of 49
Executive Summary
PacifiCorp plans to build a 500 kV transmission Project to deliver wind power from central
Wyoming to central Utah and eastern Idaho.The Project consists of 500 kV transmission from
central Wyoming to central Utah and a second set of 500 kV lines from Wyoming to the eastern
Idaho area and eventually to the lower Columbia River system in north central Oregon.The
project also consists of a 230 kV collector system in Wyoming,which delivers the output of
various wind farms to a 500 /230 kV central hub called Aeolus.Just to the northwest of the
existing Dave Johnston plant,a second 230 kV hub station called Windstar will be developed
with 230kV tie lines to Aeolus.See Figure 1 for a geographic depiction of the proposed
facilities that comprise 'Stage l'of the ultimate build-out plan for the system.As noted in the
Legend,Stage 1 consists of the solid lines only.
Figure 1
Gateway Energy Project
Stage 1 -Transmission Plan
Legend r
Planned Future Voltage '
----·-500kV
--.---345kV oO
-----230kV nuo
Ocon sus
This study covers the "Bridger Area"and includes the followingprimary paths;
Aeolus West
Bridger /Anticline West
Path C Southbound
This study shows that the proposed project meets all applicable NERC Planning Standards and
WECC System Performance Criteria with minor modifications to the originally proposed plan of
service.
11/24/2010 Gateway West Project -Bridger Study Area Page 5 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-Ed7-07
Page 8 of 49
At the start of this study,Idaho Power and PacifiCorp agreed that the Bridger West 345 kV path
be studied only at 2400 MW,a 200 MW upgrade from the existing rating of 2200 MW.
1.Introduction
This report establishes that,at the proposed transfer levels,the Bridger Area of the Gateway
West system has little to no impact on paths external to PacifiCorp and Idaho.
1.1.Project Description
As shown in Figure 1,the Gateway West system consists of a 230kV collector system for
various wind farms in central and western Wyoming.These systems either connect to the "Tot
4a"230kV lines or connect directly to the Windstar and Aeolus hubs.From Aeolus extends a
500 kV line to Anticline,in the Bridger vicinity,and then on to Populus.Other portions of the
Gateway West project will consist of 500 kV lines from Populus to Midpoint and Hemmingway,
and on to Slatt substation in Oregon.A second 500 kV line from Aeolus will extend through
northwestern Colorado and into a new substation called Mona Annex (or Clover)located with a
few miles of the existing Mona 345kV station.
1.2.Plan of Service
.See Appendix 5 for the Gateway West Study Plan (2010 01 19 V9 -Phase I II GW Study
Plan.doc)for a detailed listing of the project components.
1.3.Planned Operating Date
The plan of service provides for the Aeolus West stage one facilities to be operational by 2016 or
2017.The Aeolus South stage two facilities will be operational by 2017 to 2019
2.Transfer Capability
This report intends to prove that the Gateway West Project has little or no significant impact to
paths external to PacifiCorp.In the few instances where impacts are identified,simultaneous
flow impacts will be respected.In some cases,impact remediation facilities will be installed.
Early on in this study,a request was received to analyze possible increases in the study plan
table of desired capacities to allow some flexibility of delivery to Aeolus South or Aeolus West.
Table 1 shows the originally proposed path ratings and actual ratings achieved.
Table l
11/24/2010 Gateway West Project -Bridger Study Area Page 6 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 9 of 49
Path RatingWECCPathProposedStageAchievedinthisName/Number 1 Ratmg study
Aeolus West'(New)1500 MW 2672 MW
Bridger /Anticline West (19)3900 MW 4100 MW
Path C (20)Southbound 2250 MW 2250 MW
The above ratings are all based on a heavy summer representation for the 2019 time frame.An
analysis of a lighter load condition to study Path C northbound was requested,but a PRG
approved base case was not delivered in time to be included in this study.The Path C
northbound path rating will be addressedin a separate report.
The path transfer capability is limited due to NERC/WECC reliability performance
requirements.The NERC/WECC "Reliability Criteria"is available at the followinglink:
http://www.wecc.biz/documents/library/procedures/CriteriaMaster.pdf
3.Study Methods and Standards
3.1.Steady-StateCase Stressing
Details of how each study base case was developed can be found in the Base Case Development
sections of the studied system flow conditions.
3.2.Post Transient
The power flow conditions generated above are modeled with single line (N-1)outages,credible
double line (N-2)outages,breaker failure outages,as well as risk assessment outages to evaluate
the NERC/WECC category B,and C performance.All modeled system bus voltages and line,
transformer,and series capacitor current flows are monitored.Voltage deviations greater than
5%and significant overloaded elements,with greater than a 2%change in flow,are reported in
the tables located in the appendices.Engineering judgment was used to determine whether the
overloadingwas relevant to the area.For example,some contingencies in the PACE area caused
parallel transformer tap changers in B.C.Hydro and Alberta to head in opposite directions,
leading to circulating Vars overloading the transformers.These loading issues are clearly a
defect in modeling built into the original base cases and these loadings have not been included in
the reports.
For PacifiCorp's Wyoming system,voltages less than .90 pu are reported.For Montana buses
on Path 18 for Level B and C contingencies,.90 pu voltage is required.For Idaho and
PacifiCorp Path 18 buses,voltages less than .87 pu are limiting for Level B and C contingencies.
For Level C contingencies,under-voltage load tripping at Amps,Peterson Flats,and Big Grassy
is allowedto restore system voltages.
'The study plan definition of Aeolus West as only the Aeolus -Anticline 500 kV line.During the course of this
study,the definition was modified to include three 230 kV lines.
l1/24/2010 Gateway West Project -Bridger Study Area Page 7 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 10 of 49
Violations of the NERC/WECC allowed performance are identified in the summary paragraphs
for each path relationship /nomogram section.
3.3.Reactive Margin
Idaho Power's reactive margin requirements are;
For N-1 outages;500 MVAR for 500 kV and 250 MVAR for 345 and 230 kV.
For N-2 outages;400 MVAR for 500 KV and 200 MVAR for 345 and 230 kV
For this study,Idaho is assumed to be the owner of the following margin tested buses;
Borah 500
Borah 345
Kinport 345
Midpoint 500
Hemmingway 500
Cedar Hill 500
The WECC also requires that new rated paths or facilities be scheduled at 2.5%for all level C
contingencies and 5%over their rated capacities for Level B contingencies to test for voltage
collapse.Each starting nomogram corner case was modified to increase the flow by 5%and
checked that a solution was attained for each outage.
3.4.Transient Stability
Utilizing GE PSLF software,select single line (N-1)and double line (N-2)and other outages
were studied to evaluate transient stability performance.Relevant bus voltage and frequency
violations of the NERC/WECC allowed performance are documented in Appendix 4.
3.5.Generation Drop via Remedial Action Schemes (RAS)
In order to maintain PacifiCorp's current level of reserve requirements (for Bridger
contingencies),Wyoming wind generation dropping via RAS was limited to 600 MW for single
line outage contingencies (N-1)and 1200 MW for double line outage contingencies.
4.Path Definitions
Both new and existing path definitions are as follows,with a '*'denoting the metering points.
4.1.Aeolus West (New)
The Aeolus West transmission path is a constrained path and is defined as the sum of the flows
on the followinglines:(this defn differs from the study plan)
Aeolus*-Anticline 500 kV
Platte*-Latham 230 kV
Mustang*-Bridger 230 kV
11/24/2010 Gateway West Project -Bridger Study Area Page 8 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 11 of 49
Riverton*-Wyopo 230 kV
4.2.Aeolus South (New)
The Aeolus South path is a constrained path and is defined as the sum of the flows on only one
line:
Aeolus*-MonaAnnex 500 kV
4.3.Bridger West 345 kV (Existing)
The Bridger /Anticline West constrained path and is defined as the sum of the flows on the
following lines:
Bridger*-3 Mile Knoll 345 kV
Bridger*-Populus 345 kV #1
Bridger*-Populus 345 kV #2
Bridger West,comprising only the existing 345 kV lines from Bridger,is currently rated at 2200
MW.With the Gateway West Project,this path rating is planned to increase to 2400 MW.
4.4.Bridger /Anticline West (Modified)
The Bridger /Anticline West constrained path and is defined as the sum of the flows on the
followinglines:
Anticline*-Populus 500 kV
Bridger*-3 Mile Knoll 345 kV
Bridger*-Populus 345 kV #1
Bridger*-Populus 345 kV #2
With the Gateway West Project this Path is anticipated to be rated at 4100 MW.
4.5.Path C (Existing -After completion of the Populus -Terminal Project)
Path C is a constrained path and is defined as the sum of the flows on the followinglines:
Terminal -Populus*345 kV
Ben Lomond -Populus*345 kV #2
Ben Lomond -Populus*345 kV #3
Treasureton -Brady*230 kV
Fish Creek -Goshen*161 kV
Malad-American Falls *138 kV
3 Mile Knoll 138 /345*kV Transformer
3 Mile Knoll*-Hooper Spur 138 kV
After completion of the Populus -Terminal Project,Path C will have a southbound rating of
1600 MW and a northbound rating of 1250 MW.With the Gateway West Project,the Path C
rating goals are 2250 MW bi-directional.
11/24/2010 Gateway West Project -Bridger Study Area Page 9 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 12 of 49
4.6.Monument --Naughton (Internal Path)
Monument-Naughton is a path internal to PacifiCorp,is not registered with the WECC,and is
defined as the sum of the flows on the followinglines:
Monument PST*-Craven Creek 230 kV
Monument PST*-Naughton 230 kV
4.7.West of Rock Springs /Firehole (Internal Path)
Monument-Naughtonis a path internalto PacifiCorp,is not registered with the WECC,and is
defined as the sum of the flows on the followinglines:
Rock Springs*-Palisade 230 kV
Firehole*-Mansface 230 kV
5.Project Base Case Modifications
The followingdescribes various changes to the base cases to resolve PSLF solution convergence
issues.
5.1.SVC Tie Line Modeling
At St.George,Red Butte,Platte,and Aeolus,tie lines between the SVC and the main substation
bus had too low an impedance to obtain reliable solutions in PSLF.These impedances were
adjusted to be above the Z threshold to get the cases to reliably converge.In some instances,the
Red Butte SVC had to be disconnected to obtain a valid solution.
5.2.Line and Transformer Rating Conflicts
From the original WECC base cases there are some instances where the emergency ratings
(MVA2)are lower than the normal ratings (MVAl).The consequencesof this are that the Post-
transient flow program output would get clogged with reports of overloads that are not real.To
reduce the erroneous reports,a program was run to set the emergency ratings at least equal to the
normal ratings.
5.3.Phase Shifter Tap Steps
Most of the controlled flow phase shifter tap steps were changed to zero degrees to allow for fine
tuning of the path flows.
5.4.SVDs to Shunt Conversions
In the PacifiCorp system,many of the Static Var Devices (SVDs)were disconnected and
replaced with shunt capacitors and reactors to allow forcing of the devices to correct voltage
profiles while keeping generator reactive within reasonable limits.
5.5.Other System Modeling Changes/Corrections
Several cases involving heavy Path C southbound flows resulted in Aeolus flows greater than
1700 MW.To keep the Aeolus south flows within the 1700 MW limit,a small portion of the
l1/24/2010 Gateway West Project -Bridger Study Area Page 10 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 13 of 49
series capacitors closest to Aeolus were bypassed (by modifying the bank impedance)on the
Aeolus -Mona Annex 500 kV line.
On the starting base case,errors were noted on the PDCI B-Face table such that the PDCI flows
were being incorrectly reported.This was corrected via an epel routine.
5.6.PacifiCorp SystemUpdates/Corrections
Through the course of the study,modeling errors were noted in both the existing system in the
Gateway West proposed facilities.To track case versions,these changes also describe case
version code changes;
1.Early on in the studies,a reactive deficiency at Bonanza was noted.At the recommendation of Deseret
Energy,the 345 kV line reactor was removed from the Bonanza -Mona 345 kV line and a 60 MVar shunt
capacitor was added to the Bonanza 138 kV bus.A previously suggested load addition at Chapita 138 was
not added due to the lack of a plan of service study.At about the same time it was noted that the SVDs
modeled at the Tot 4a 230kV buses were causing the PT cases to diverge.To fix this problem,the SVDs
were converted to shunts and switched via RAS in the switching files.These changes,along with a rating
change of the Malad -American Falls 138 kV line were incorporated into cases identified by the version
code '8h5'.
2.An error was found in the conversion of the cases from PSSE to PSLF in the shunt tables.In PSSE,
shunts are part ofthe bus records,and if they are off line,they are simply deleted from the record.When
converting to PSLF,this information is lost.An EPCL was developed to incorporate the original shunt
tables from the parent WECC case.The case version code for this change was '8h6'.
3.In the approved project case,only transformer and phase shifters connected to Anticline 500 kV to Bridger
345.A change was requested to add the 5 mile section of 345 kV line between Anticline and Bridger with
the transformers and phase shifters located at Anticline.Also,the addition of Riverton -Wyopo 230 kV
line to the Aeolus West interface.The case version code for this change was '8h7'.
4.Errors were noted in the representation of the Aeolus area shunts and SVC.The SVC was increased to
+450 MVar.At this same time,the fixed SVD at Spence was removed and replaced with a switchable
shunt and the Pinto phase shifter impedance was corrected.The case version code for this change was
'8h8'.
5.After it was found that the Platte -Miners and Platte -Latham 230 kV lines were constraining Aeolus
West flows,it was decided to change the emergency rating (MVA2)to the 30 minute rating of 521 MVA
for both of these lines.As the network topology did not change,the version code remained at '8h8'.
6.Path Studies
6.1.Aeolus West vs.Aeolus South
6.1.1.Base Case Development
The Gateway West Project base case was modified to stress Aeolus West to 2672 MW with
several cases spanning a range of Aeolus South flows.The primary resource for stressing
Aeolus West was the Wyoming Wind developments.Aeolus South flows were stressed by
varying;l)Current Creek generation,2)IPP DC flows and the wind generation connected to IPP
345,and lastly,Nevada generation and Tot 2C flows.
11/24/2010 Gateway West Project -Bridger Study Area Page 11 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 14 of 49
For cases with Aeolus South flows at 1700 MW,Aeolus West flows were fine tuned by varying
schedules from WAPA (73)to the Northwest (40).Shunt capacitors were added to Mona
Annex 500 kV to support the high flows into central Utah.Path flows for each of the above
cases are shown on Appendix 3-1.The resulting nomogram is shown on Appendix 2-1.
Finally,two margin test cases were developed with 5%additional flows across 1)Aeolus West
path and 2)Aeolus South path.These cases are shown near the bottom of Appendix 3-1.
6.1.2.Post-Transient Analysis
Appendix 3-1 contains the tables associatedwith the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading informationhas been requested for design input
to PacifiCorp to determine the magnitude of rating increase neededto rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional 230kV capacitors at Mustang,Riverton,and additional capacitors on Path
18)becomes the limiting contingency for both nomogram corners.This outage results in
overloads on the Miners -Platte 230 kV line even when the 521 MVA 30 minute emergency
rating is used,and thereby sets the PT limit for this contingency.
Aeolus --Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
This contingency also diverges without any RAS actions.However,with 600 MW of
generation dropping and 500 kV and 230 kV switchable capacitor applications,the
contingency problems are fully resolved.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigated with RAS switching.
11/24/2010 Gateway West Project -Bridger Study Area Page 12 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 15 of 49
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (C03 and RAS
variations)
This outage resulted in overloads of the Bridger -Rock Springs 230kV line.Follow-up
cases with Bridger generation dropping and additionalRAS action on Path 18 resolve both
the loadingproblem and the voltage deviationissues on Path 18.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in overloads of Springer -Gladstone l 15 kV line for one corner point of the
nomogram and an overload of Merwin -View Tap 115kV line for the other corner point.
Springer -Gladstone is a knownproblem for which remediation is already planned.The
Merwin -View tap problem is also a known problem related to north to south flows on
transmission into the Vancouver,WA and Portland,OR loads.
6.1.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-1.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.1.4.Transient Stability Analysis
As shown on Appendix 4-1,dynamic simulations were run on both nomogram corner points.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the exceptions for Bridger that are filed with
the WECC.See Appendix21 for details of the TSS Approvedexceptions for Bridger.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
Contingency Bl6 (Aeolus-Mona Annex 500 kV line)also produced voltage deviations.
However,these were mitigated with some of the RAS actions simulated in the PT contingencies.
Blundel #2 also lost synchronism and went out-of-step.Blundel #2 is known as having
modelingproblems where the unit losses synchronism for very remote faults.This result is not
relevant to this study.
11/24/2010 Gateway West Project -Bridger Study Area Page 13 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 16 of 49
6.2.Aeolus West vs.Bonanza West
6.2.1.Base Case Development
The Gateway West Project base case was modified to stress Aeolus West to 2666 MW with
several cases with Bonanza West flows at 785 MW and 685 MW.The primary resource for
stressing Aeolus West was the Wyoming Wind developments.Bonanza West flows were
stressed by varying;l)Current Creek generation,and 2)IPP DC flows and the wind generation
connected to IPP 345.From the starting point (2666,785)Aeolus West flows were cut by 100
MW to 2566 MW by varying schedules from WAPA (73)to the Northwest (40).Path flows for
each of the above cases are shown on Appendix 3-2.The resulting nomogram is shown on
Appendix 2-2.
Two margin test cases were developed with 5%additional flows across 1)Aeolus West path and
2)Bonanza West path.These cases are shown near the bottom of Appendix 3-2.
6.2.2.Post-Transient Analysis
Appendix 3-2 contains the tables associatedwith the post-transient study results for the Aeolus
West vs.Bonanza West cases.A discussion of several of the prominent outages follows.
Anticline --Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading informationhas been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Bridger -3 Mile Knoll 345 kV Lines (B04 and RAS variations)
For this outage,loadings are within emergency ratings.However,voltage deviations and
deviations from the .90 pu standard for Path 18 are noted.Subsequent simulations with
RAS actions fully resolve these issues.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.Howeverwith RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional230kV capacitors at Mustang,Riverton,and additionalcapacitors on Path
18)becomes the limiting contingency for both nomogram corners.This outage results in
overloads on the Miners-Platte 230 kV line even with the 521 MVA 30 minute emergency
rating,and thereby sets the PT limit for this contingency.
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS variations)
11/24/2010 Gateway West Project -Bridger Study Area Page 14 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 17 of 49
This contingency also diverges without any RAS actions.However,with 600 MW of
generation dropping and 500 kV and 230 kV switchable capacitor applications,the
contingency problems are fully resolved.
Bonanza -Mona 345 kV Line (B40 and B40a with RAS)
For this outage,a total of 10 elements overload,with the worst being the Bonanza -Vernal
138 kV line that loads to 133.42%of its emergency rating.Contingency 40a,with the
existing Bonanza generation dropping RAS,fully resolves the loading and voltage deviations
issues.
Bridger -Populus 345 kV Lines 1 &2 (C02 and RAS variations)
This outage results in overloads on the Bridger-3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigated with RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
This outage resulted on overloads of the Bridger -Rock Springs 230kV line.Follow-up
cases with Bridger generation dropping and additionalRAS action on Path 18 resolve both
the loading problem and the voltage deviationissues on Path 18.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in overloads of Springer -Gladstone 115 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.
6.2.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-2.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.2.4.Transient Stability Analysis
As shown on Appendix 4-2,,dynamic simulations were run on both nomogram corner points.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.For contingency B09c,the backswing exceeded the "exceptions"for Bridger that are
filed with the WECC.See Appendix 21 for details of the TSS Approvedexceptions for Bridger.
If this deviationis determined to be acceptable and not a risk to tripping the Bridger units,an
amendment to the WECC exceptions list could easily resolve this issue.
l1/24/2010 Gateway West Project -Bridger Study Area Page 15 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 18 of 49
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
Contingency B16 (Aeolus -Mona Annex (Clover)500 kV line)for the second base case (785,
2666)also produced voltage deviations and a over-excitationlimiter (OELl)relay trip of the
Bonanza unit.Follow-up RAS cases with generation drop RAS and capacitor switching did not
resolve the OEL trips.A further investigationinto the OEL1 relay resulted in new relay data
from Deseret Energy.However,the new data also resulted in a trip of Blundel #2 in addition to
the OEL trip of Bonanza.After checking the dynamics plots it was found that the excitation
current was well below the OELl trip setting.A further test with the trip functions of the OEL
relay disabled produced stable operation and generator filed currents well within the maximums.
From this,it is concluded to be a relay /modeling problem and is not a problem associated with
Gateway West transfers.If a more detailed analysis determines Bonanza OEL1 relay settings
to be correct and the field current to be a real problem,a 60 MVar switchable cap (#2)could be
added to get the generator off its excitation /Var limits.This sensitivity analysis is provided on
line 86 of Appendix 4-2.
6.3.Aeolus West vs.Tot la
6.3.1.Base Case Development
The Gateway West Project base case was modified to stress Aeolus West to 2672 MW with
several cases with Tot la flows at 650 MW and 550 MW.The primary resource for stressing
Aeolus West was the Wyoming Wind developments.Tot la flows were stressed by varying;1)
Bonanza generation,2)Craig /Hayden generation,3)Current Creek generation,and 4)IPP DC
flows and the wind generation connected to IPP 345.Craig #3 generation was modeled at 4302
MW which is above the governor limit shown in the dynamics data file.From the starting point
(2672,650)Aeolus West flows were cut by 100 MW to 2572 MW by varying schedules from
WAPA (73)to the Northwest (40).Path flows for each of the above cases are shown on
Appendix 3-3.The resulting nomogram is shown on Appendix 2-3.
One margin test cases was developed with 5%additionalflows across the Aeolus West path and
Tot la.These cases are shown near the bottom of Appendix 3-3.
6.3.2.Post-Transient Analysis
Appendix 3-3 contains the tables associated with the post-transient study results for the Aeolus
West vs.Bonanza West cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
2 An email request for this modeling change was made to Tri-State on June 17,2010.As of this writing,no
response has been received.
11/24/2010 Gateway West Project -Bridger Study Area Page 16 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 19 of 49
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading information has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Bridger -3 Mile Knoll 345 kV Lines (B04 and RAS variations)
For this outage,loadings are within emergency ratings.However,voltage deviations and
deviations from the .90 pu standard for Path 18 are noted.Subsequent simulations with
RAS actions fully resolve these issues.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional 230kV capacitors at Mustang,Riverton,and additionalcapacitors on Path
18)becomes the limiting contingency for both nomogram corners.This outage results in
overloads on the Miners-Platte 230 kV line even with the 521 MVA 30 minute emergency
rating,and thereby sets the PT limit for this contingency.
Aeolus -MonanX (Clover)500 kV Line (Contingency B36 and RAS variations)
This contingency also diverges without any RAS actions.However,with 600 MW of
generation dropping and 500 kV and 230 kV switchable capacitor applications,the only
issues remaining are voltage deviations greater than 5%in the Bonanza area.A shunt
capacitor,discussed later in this report,may be available to bring the Bonanza generator off
of its upper Var limit and thereby reduce the voltage deviations to acceptable limits.
Bonanza -Mona 345 kV Line (B40 and B40a with RAS)
For this outage,a total of 10 elements overload,with the worst being the Boanza -Vernal
138 kV line that loads to 133.42%of its emergency rating.Contingency 40a,with the
existing gen drop RAS,fully resolves the loadingand voltage deviations issues.
Bridger --Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigatedwith RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
11/24/2010 Gateway West Project -Bridger Study Area Page 17 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 20 of 49
This outage resulted on overloads of the Bridger-Rock Springs 230kV line.Follow-up
cases with Bridger generation dropping and additional RAS action on Path 18 resolve both
the loading problem and the voltage deviationissues on Path 18.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in overloads of Springer -Gladstone l15 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.
6.3.3.Reactive Margin Analysis
As shown near the bottom of Appendix 3-3,One simultaneous case was developed with +5%on
Aeolus West and Tot la.This case solved for all contingencies (with appropriate RAS actions),
indicating sufficient reactive margins for both Level B and Level C contingencies.Idaho's
reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.3.4.Transient Stability Analysis
As shown on Appendix 4-3,dynamic simulations were run on both nomogram corner points.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.For contingency B09c,the backswing exceededthe exceptions for Bridger that are
filed with the WECC.See Appendix 21 for details of the TSS Approvedexceptions for Bridger.
If this deviation is determined to be acceptable and not a risk to tripping the Bridger units,an
amendment to the WECC exceptions list could easily resolve this issue.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
Contingency B16 (Aeolus -Mona Annex (Clover)500 kV line)for the second base case (650,
2522)resulted in an over-excitationlimiter (OELl)relay trip of the Bonanza unit.Follow-up
RAS cases with generation drop RAS and capacitor switching did not resolve the OEL trips.A
further investigationinto the OELl relay resulted in new relay data from Deseret Energy.
However,was not successful in elimination of the Bonanza OEL trip.After checking the
dynamics plots it was found that the excitationcurrent was well below the OEL1 trip setting.A
further test with the trip functions of the OEL relay disabled.The resulting run produced stable
operation and generator filed currents well within the maximums.From this,it is concluded to
be a relay /modeling problem and is not a problem associatedwith Gateway West transfers.If a
more detailed analysis determines Bonanza OEL1 relay settings to be correct and the field
current to be a real problem,a 60 MVar switchable cap (#2)could be added to get the generator
off its excitation/Var limits.
11/24/2010 Gateway West Project -Bridger Study Area Page 18 of 150
WECC Phase 2 Project RatingReport
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 21 of 49
6.4.Bridger /Anticline West vs.Aeolus South
6.4.1.Base Case Development
The Gateway West Project base case was modified to stress Bridger /Anticline West to 4100
MW with several cases spanning a range of Aeolus South flows from 1500 MW to 1700 MW.
The primary resource for stressing Bridger /Anticline West was the Wyoming Wind
developments.Aeolus South flows were controlled by varying;1)Current Creek generation,2)
IPP DC flows and the wind generation connected to IPP 345,and lastly,Nevada generation and
Tot 2C flows.
For cases with Aeolus South flows at 1700 MW,Bridger /Anticline West flows were fine tuned
by varying schedules from WAPA (73)to the Northwest (40).Shunt capacitors were added to
Mona Annex (Clover)500 kV to support the high flows into central Utah.Path flows for each
of the above cases are shown on Appendix 3-4.The resulting nomogram is shown on Appendix
2-4.
Finally,two margin test cases were developed with 5%additional flows across 1)Aeolus West
path and 2)Aeolus South path.These cases are shown near the bottom of Appendix 3-4.
6.4.2.Post-Transient Analysis
Appendix 3-4 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading informationhas been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional230kV capacitors at Mustang,Riverton,and additionalcapacitors on Path
18)becomes the limiting contingency for both nomogram corners.For the upper left
nomogram corner point,this outage results in overloads of the Bridger 345 /230 kV
transformer #2,and thereby sets the PT limit.For the lower right nomogram point,this
outage results in overloads of three critical elements,the worst of which is the Miners -
Platte 230 kV line.
11/24/2010 Gateway West Project -Bridger Study Area Page 19 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 22 of 49
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
This contingency also diverges without any RAS actions.However,with 600 MW of
generation dropping and 500 kV and 230 kV switchable capacitor applications,the
contingency problems are fully resolved.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigated with RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (C03 and RAS
variations)
This outage resulted on overloads of the Bridger -Rock Springs 230kV line.Follow-up
cases with Bridger generation dropping and additionalRAS action on Path 18 resolve both
the loading problem and the voltage deviationissues on Path 18.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load droppingplanned for this event
resulted in overloads of Springer -Gladstone l15 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.
6.4.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-4.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.4.4.Transient Stability Analysis
As shown on Appendix 4-4,dynamic simulations were run on cases near the nomogram corner
points.Contingency BO8 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the "exceptions"for Bridger that are filed with
the WECC.See Appendix 21 for details of the TSS Approved exceptions for Bridger.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigatedwith some of the RAS actions simulated in the PT
contingencies.
11/24/2010 Gateway West Project -Bridger Study Area Page 20 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 23 of 49
Contingency B16 (Aeolus -Mona Annex (Clover)500 kV line)also produced voltage
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
6.5.Bridger /Anticline West vs.Path C Southbound
6.5.1.Base Case Development
The Gateway West Project base case was modified to stress Bridger /Anticline West to 4100
MW with several cases spanning a range of Path C Southbound flows from 1450 to 1550 MW.
The primary resource for stressing Bridger /Anticline West was the Wyoming Wind
developments.Path C Southbound flows were controlledby varying;1)Northwest (40)
generation,and 2)PACE area generation including Current Creek,Lakeside,and Huntington.
A second case with Path C southbound flows at 2250 MW,and Bridger /Anticline West reduced
to 3900 MW was very difficult to schedule without overloadingthe Aeolus South path.
Additional cases with higher Bridger/Anticline West were not attainable.The resulting
nomogram is shown on Appendix 2-5.
Two margin test cases were developed with 5%additionalflows across 1)Bridger /Anticline
West and 2)Path C Southbound.These cases are shown near the bottom of Appendix 3-5.
6.5.2.Post-Transient Analysis
Appendix 3-5 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading information has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.Howeverwith RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional230kV capacitors at Mustang,Riverton,and additionalcapacitors on Path
18)resolves the voltage deviationproblems.The Jefferson phase shifter overload shown is
based on an emergency rating of 100 MVA.When corrected to the true rating of 112 MVA,
the overload is resolved.
Aeolus -MonanX (Clover)500 kV Line (Contingency B36 and RAS variations)
11/24/2010 Gateway West Project -Bridger Study Area Page 21 of 150
WECC Phase 2 Project RatingReport
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 24 of 49
This contingency also diverges without any RAS actions.With 600 MW of generation
droppingand 500 kV and 230 kV switchable capacitor applications,the Grace -Soda 138
kV line remains overloaded,indicatingthe need for bypassing ½of the 3 Mile Knoll series
capacitor or reconductoring of the Grace -Soda 138 kV line.
Bridger -Populus 345 kV Lines 1 &2 (C02 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuildingthe limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigated with RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
This outage resulted in an overload of the Bridger -Rock Springs 230kV line.Follow-up
cases with Bridger generation dropping and additionalRAS action on Path 18 resolve both
the loading problem and the voltage deviationissues on Path 18.
Path C Double Line Outages (Contingencies C09,CIO,C11,&C12)
This outage resulted in an overload of the Grace -Soda 138 kV line,indicatingthe need for
bypassing ½of the 3 Mile Knoll series capacitor or reconductoring of the Grace -Soda 138
kV line.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in overloads of Springer -Gladstone l 15 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.
6.5.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-5.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).While it would appearthat the Level C (N-2)contingencies do not meet Idaho's
reactive margin requirements,a review of the margin tables shows the lowest margins for
contingencies CO3 &C04.Follow-up RAS scenarios fully resolve margin deficiencies noted by
red shaded cells.
11/24/2010 Gateway West Project -Bridger Study Area Page 22 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 25 of 49
6.5.4.Transient Stability Analysis
As shown on Appendix 4-5,dynamic simulations were run on both nomogram corner points.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the "exceptions"for Bridger that are filed with
the WECC.See Appendix 21 for details of the TSS Approved exceptions for Bridger.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
Contingency Bl6 (Aeolus -Mona Annex 500 kV line)also produced voltage deviations.
However,these were mitigated with some of the RAS actions simulated in the PT contingencies.
6.6.Bridger /Anticline West vs.Bonanza West
6.6.1.Base Case Development
The Gateway West Project base case was modified to stress Bridger/Anticline West to 4100
MW with several cases spanning a range of Bonanza West flows.The primary resource for
stressing Bridger /Anticline West was the Wyoming Wind developments.Bonanza West flows
were controlledby varying;1)Bonanza generation,2)Craig /Hayden generation,3)Currant
Creek generation,and 4)IPP DC flows and the wind generation connected to IPP 345.
For cases with Aeolus South flows at 1700 MW,Bridger/Anticline West flows were fine tuned
by varying schedules from WAPA (73)to the Northwest (40).Shunt capacitors were added to
Mona Annex 500 kV to support the high flows into central Utah.Path flows for each of the
above cases are shown on Appendix 3-6.The resulting nomogram is shown on Appendix 2-6.
Finally,two margin test cases were developed with 5%additionalflows across 1)Aeolus West
path and 2)Bonanza West path.These cases are shown near the bottom of Appendix 3-6.
6.6.2.Post-Transient Analysis
Appendix 3-6 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loadinginformation has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Aeolus --Anticline 500 kV Line (Contingency B35 and RAS variations)
11/24/2010 Gateway West Project -Bridger Study Area Page 23 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 26 of 49
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional230kV capacitors at Mustang,Riverton,and additional capacitors on Path
18)becomes the limiting contingency for both nomogram corners.For both nomogram
corner points,this outage results in overloads of the Miners -Platte 230 kV line,and this
loading sets the PT limit.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigated with RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
This outage resulted on overloads of the Bridger -Rock Springs 230kV line.Follow-up
cases with Bridger generation dropping and additionalRAS action on Path 18 resolve both
the loading problem and the voltage deviationissues on Path 18.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in overloads of Springer -Gladstone 115 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.
6.6.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-6.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.6.4.Transient Stability Analysis
As shown on Appendix 4-6,dynamic simulations were run on both nomogram corner points.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the "exceptions"for Bridger that are filed with
the WECC.See Appendix21 for details of the TSS Approvedexceptions for Bridger.
Contingency Bl5 (Aeolus-Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
11/24/2010 Gateway West Project -Bridger Study Area Page 24 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 27 of 49
Contingency Bl6 (Aeolus -Mona Annex (Clover)500 kV line)resulted in no voltage or
frequency deviations for the upper left nomogram point (695,4100).The lower right nomogram
corner point (785,4062)had extensive difficulties with an over-excitationlimiter (OELl)model
that tripped the unit supposedly to protect the rotor from overheating damage.Flows on
Bonanza
West were decremented down to 3532 MW before the OEL1 generation trip problem was
resolved.After a discussion of these results,Deseret provided corrected OEL1 model data that
slightlychanged the timing of the trips,but not the end result.Additional sensitivity cases with
the OEL1 trip timers set to 999 seconds but with the OELl runback function still active,the PT
corner point (785,4062)had no voltage or frequency deviations and of course the unit does not
tnp.
6.7.Bridger /Anticline West vs.Idaho -Montana (Path 18)
6.7.1.Base Case Development
The Gateway West Project base case was modified to stress Bridger /Anticline West to 4100
MW and Path 18 was controlled to 337 MW.The primary resource for stressing Bridger /
Anticline West was the Wyoming Wind developments with fine tuning using schedules from
WAPA (73)to Northwest (40).Path 18 flows were controlledby schedules from Montana (62)
to Idaho (60)and adjustments of the Jefferson and Mill Creek phase shifters.
Two margin test cases were developed with 5%additionalflows across 1)Bridger /Anticline
West and 2)Path 18.These cases are shown near the bottom of Appendix 3-7.
6.7.2.Post-Transient Analysis
Appendix 3-7 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading information has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Bridger -3 Mile Knoll 345 kV Line (Contingency B04 and RAS variations)
This outage results in voltage deviations and violations of the .87 pu voltage standard for the
Path 18 buses.Follow-up cases were run with switching of the Kinport 345 kV shunt
capacitor,Dillon 69 kV shunt capacitors c3 &c4,and a new 42 MVar shunt capacitor at Big
Grassy 161 kV.These cases show the voltage problem resolved with the lowest voltage
11/24/2010 Gateway West Project -Bridger Study Area Page 25 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 28 of 49
shown to be .881 pu at Peterson Flat 230.The overload shown for E.Helena 69/100 kV #2
is the result of circulating reactive power (vars)between the two transformers at E.Helena.If
the transformers were correctly modeled,the overload would be resolved.
3 Mile Knoll -Goshen 345 kV Line (Contingency B06 and RAS variations)
Contingency B06 results in overloads on the Grace -Soda 138 kV line.The follow-up case
B06a,with the 3 Mile Knoll series capacitor bank bypassed,results in a violation of
Montana's .90 pu voltage standard.A second follow-up case (B06b),with switching of the
Big Grassy 161 kV shunt capacitor fully resolves the voltage problem.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional 230kV capacitors at Mustang,Riverton,and additionalcapacitors on Path
18)fully resolves all voltage and loading problems.
Bridger -Populus 345 kV Lines I &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.In follow-up cases,some voltage deviationproblems are noted,but
these issues are fully mitigated with RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
This outage resulted in voltage deviations on Path 18 buses.Follow-up cases with RAS
switching of Path 18 shunt capacitors and load tripping via under-voltage relays results in
acceptable performance.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in overloads of several overloads including the Sigurd PS -Glen Canyon 230kV
line.This line is loaded southbound in the base case,and this loading result may indicate a
simultaneous flow relationship between Bridger /Anticline West and Tot 2B.
6.7.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-7.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
11/24/2010 Gateway West Project -Bridger Study Area Page 26 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 29 of 49
Idaho's reactive margin requirements were also met for all contingencies (withappropriate RAS
actions).While it would appear that the Level C (N-2)contingencies do not meet Idaho's
reactive margin requirements,a review of the margin tables shows the lowest margins for
contingencies CO3 &C04.Follow-up RAS scenarios fully resolve any margin deficiencies.
6.7.4.Transient Stability Analysis
As shown on Appendix 4-7,dynamic simulations were run on the simultaneous flow corner
point.Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the exceptions for Bridger that are filed with
the WECC.See Appendix 21 for details of the TSS Approvedexceptions for Bridger.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the post-
transient contingencies.
6.8.Bridger /Anticline West vs.Monument --Naughton
6.8.1.Base Case Development
The Gateway West Project base case was modified to stress Bridger /Anticline West to 4100
MW with several cases spanning a range of Monument-Naughtonflows from 332 MW to 475
MW.The primary resource for stressing Bridger /Anticline West was the Wyoming Wind
developments.Monument -Naughton flows were controlled by the Monument phase shifting
transformers.Loads in the Trona area of SW Wyoming (Zone 668)were reduced by roughly
141 MW to prevent the Rock Springs /Firehole cut-plane from exceeding its 640 MW capacity.
The resulting nomogram is shown on Appendix 2-8.
Two margin test cases were developed with 5%additionalflows across 1)Bridger /Anticline
West and 2)Monument -Naughton.These cases are shown near the bottom of Appendix 3-8.
6.8.2.Post-Transient Analysis
Appendix 3-8 contains the tables associatedwith the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading information has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
3 Mile Knoll -Goshen 345 kV Line (Contingencies B06 and B06a)
11/24/2010 Gateway West Project -Bridger Study Area Page 27 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 30 of 49
Contingency B06 results in overloads on the Grace -Soda 138 kV line.The follow-up case
B06a,with the 3 Mile Knoll series capacitor bank bypassed,fully resolves the overload.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional 230kV capacitors at Mustang,Riverton,and additional capacitors on Path
18)resolves the voltage deviation problems.This outage results in a slight overload
(100.04%)on the Miners -Platte 230 kV line even with the 521 MVA 30 minute emergency
rating,and thereby sets the PT limit for this contingency.
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
This contingency also diverges without any RAS actions.With 600 MW of generation
dropping and 500 kV and 230 kV switchable capacitor applications,the contingency
converges to a solution with no overloads.
Bridger --Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigated with RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
This outage resulted in a voltage deviation at Populus 500 for the case with Bridger /
Anticline West at 4100 MW.Follow-up RAS cases with Bridger gen tripping resolve the
Populus deviationproblem,but then created problems for Path 18 buses.The case with 475
MW on Monument -Naughton,this outage overloaded both Monument phase shifters.
While RAS actions did help the loading situation,a better solution would be to adjust the
phase shifter taps to reduce flows.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in an overload of the Glen Canyon 345 /230 kV transformer.This overload arises
when the generation at Glen Canyon is not correctly divided between the 230 kV and 345 kV
11/24/2010 Gateway West Project -Bridger Study Area Page 28 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 31 of 49
step-up buses.This is a known modeling problem and is unrelated to the Gateway West
Project.
6.8.3.ReactiveMargin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-8.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.8.4.Transient Stability Analysis
As shown on Appendix 4-5,dynamic simulations were run on both nomogram corner points.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the exceptions for Bridger that are filed with
the WECC.See Appendix 21 for details of the TSS Approved exceptions for Bridger.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
6.9.Bridger /Anticline West vs.Rock Springs /Firehole
The Gateway West Project base case was modified to stress Bridger /Anticline West to 4100
MW with several cases spanning a range of Rock Springs /Firehole (RS/FH)West flows from
489 MW to 640 MW.The primary resource for stressing Bridger /Anticline West was the
Wyoming Wind developments.RS/FH flows were controlledby adjustments to the Monument
phase shifting transformers.The resulting nomogram is shown on Appendix 2-9.
Two margin test cases were developed with 5%additionalflows across 1)Bridger /Anticline
West and 2)RS/FH West.These cases are shown near the bottom of Appendix 3-9.
6.9.1.Post-Transient Analysis
Appendix 3-9 contains the tables associatedwith the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline ---Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading information has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
l1/24/2010 Gateway West Project -Bridger Study Area Page 29 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 32 of 49
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
3 Mile Knoll -Goshen 345 kV Line (Contingencies B06 and B06a)
Contingency B06 results in overloads on the Grace -Soda 138 kV line.The follow-up case
B06a,with the 3 Mile Knoll series capacitor bank bypassed,fully resolves the overload.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional230kV capacitors at Mustang,Riverton,and additionalcapacitors on Path
18)resolves the voltage deviation problems.This outage results in a slight overload
(100.05%)on the Miners -Platte 230 kV line even with the 521 MVA 30 minute emergency
rating,and thereby sets the PT limit for this contingency.
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
This contingency also diverges without any RAS actions.With 600 MW of generation
dropping and 500 kV and 230 kV switchable capacitor applications,the contingency
converges to a solution with no overloads.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger-3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.Some voltage deviationproblems are noted,but these issues are fully
mitigated with RAS switching.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in an overload of the Glen Canyon 345 /230 kV transformer.This overload arises
when the generation at Glen Canyon is not correctly divided between the 230 kV and 345 kV
step-up buses.This is a known modeling problem and is unrelated to the Gateway West
Project.
11/24/2010 Gateway West Project -Bridger Study Area Page 30 of 150
WECC Phase 2 ProjectRating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 33 of 49
6.9.2.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-9.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.9.3.Transient Stability Analysis
As shown on Appendix 4-5,dynamic simulations were run on both nomogram corner points.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the exceptions for Bridger that are filed with
the WECC.See Appendix 21 for details of the TSS Approved exceptions for Bridger.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
6.10.Bridger /Anticline West with the MSTI Project
6.10.1.Base Case Development
The Gateway West Project base case was modified to stress Bridger /Anticline West to 4100
MW simultaneous with the MSTI project at 1496 MW.Resources for the majority of the
schedules were from three 450 MW equivalent wind models represented near Townsend,
Montana.To fully load the MSTI project,other Montana generation was increased and
scheduled to Idaho and the Northwest.
Two margin test cases were developed with 5%additional flows across 1)Bridger /Anticline
West and 2)The MSTI project.These cases are shown near the bottom of Appendix 3-10.The
resulting nomogram is shown on Appendix 2-10.
6.10.2.Post-Transient Analysis
Appendix 3-10 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline --Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading information has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
11/24/2010 Gateway West Project -Bridger Study Area Page 31 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 34 of 49
Anticline --Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger-3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading information has been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
This contingency diverges without any RAS actions.However with RAS actions as noted
for the B35g,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied,additional230kV capacitors at Mustang,Riverton,and additionalcapacitors on Path
18)does not quite resolve the voltage deviationproblems until Path 18 is reduced to 287
MW.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.However,as
noted above,the loading numbers are to be used as a design input for rebuilding the limiting
conductor sections.The Bridger-Rock Spring 230 kV line is also overloaded.But this
loading and the voltage deviation problems are mitigated with RAS switching.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
This outage resulted in an overload of the Bridger -Rock Springs 230kV line.Follow-up
cases with Bridger generation dropping and additionalRAS action on Path 18 resolved both
the loading problem and the voltage deviationissues on Path 18.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event
resulted in overloads of Springer -Gladstone l 15 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.This contingency also had 7 voltage
deviations in the New Mexico system.
6.10.3.Reactive Margin Analysis
Margin cases from the point with simultaneous flows on Bridger /Anticline West and the MSTI
Project were tested with +5%flow cases as noted near the bottom of Appendix 3-10.Both
+5%cases solved for all contingencies (withappropriate RAS actions),indicating sufficient
11/24/2010 Gateway West Project -Bridger Study Area Page 32 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 35 of 49
reactive margins for both Level B and Level C contingencies.Idaho's reactive margin
requirements were also met for all contingencies (withappropriate RAS actions).
6.10.4.Transient Stability Analysis
As shown on Appendix 4-9,dynamic simulations were run on the one simultaneous case.
Contingency B08 and B09 with RAS variations,resulted in back swing under-frequency
deviations.However,these deviations are within the exceptions for Bridger that are filed with
the WECC.See Appendix 21 for details of the TSS Approvedexceptions for Bridger.
Contingency B15 (Aeolus -Anticline 500 kV line)also produced voltage and frequency
deviations.However,these were mitigated with some of the RAS actions simulated in the PT
contingencies.
6.11.Path C Southbound vs.Idaho --Montana (Path 18)
6.11.1.Base Case Development
The Gateway West Project base case was modified to stress Path C North to South flows to 2250
MW simultaneous with stressed Path 18 North to South flows.Two base cases were developed.
The first case included Path 18 Shunt Additions while the second case did not.Without the Path
18 Shunt Additions,Path 18 North to South flows were limited to 285 MW.With the Path 18
Shunt Additions,Path 18 North to South flows were limited to the current Path 18 transfer limit
of 337 MW.The Path 18 Shunt Additions include switchable capacitor banks at the Amps,
Peterson Flat,Big Grassy,and Dillon stations.
Multiplemargin test cases were developed with 5%additional flows across Path C and Path 18.
These cases are shown near the bottom of Appendix 3-11.
The resulting nomogram is shown on Appendix2-10.
6.11.2.Post-Transient Analysis
Appendix 3-10 contains the tables associatedwith the post-transient study results for the import
cases with and without Path 18 Shunt Additions.A discussion of several of the prominent
outages follows.
Anticline -Populus 500 kV Line (Contingency BOI and RAS variations)
When applied to the case without the Path 18 Shunt Additions,this outage results in
overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the line is rated at 1840
Amps and this loading information has been requested for design input to PacifiCorp to
determine the magnitude of rating increase needed to rebuild the single conductor portions of
the line capable of withstanding the most severe contingencies imposed by the Gateway West
11/24/2010 Gateway West Project -Bridger Study Area Page 33 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 36 of 49
Project.Several RAS options are shown to allow selection of line upgrade costs vs.the risks
inherent with RAS.
When Contingency B01 was applied to the case with the Path 18 Shunt Additions,this
outage didn't result in any overloads or voltage issues.
3 Mile Knoll -Goshen 345kV Line (Contingency B06 and RAS variations)
In both cases (with and without the Path 18 Shunt Additions),this outage without RAS
resulted in overloads of the Grace -Soda and 3 Mile Knoll -Soda 138 kV lines.Bypassing
the 1/2 the series capacitor in the Bridger -3 Mile Knoll 345kV line mitigates both of these
overloads.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
In the case without the Path 18 Shunt Additions,this outage resulted in overloads on the
Dave Johnston -Dave Johnston South Tap 115 kV line and the Bridger 345/230kVBank #2.
In the case with the Path 18 Shunt Additions,this outage resulted in overloads on the Dave
Johnston -Dave Johnston South Tap 115 kV line only.In both cases,the RAS actions as
noted for disturbance B35a (600 MW of Aeolus area generation dropping,500 kV switchable
capacitors applied at Aeolus,and additional230kV capacitors applied at Aeolus,Atlantic,
Miners and Platt)resolved these overloads.
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
In both cases (with and without the Path 18 Shunt Additions),this disturbance without any
RAS actions caused the cases to diverge.With 600 MW of generation dropping and 500 kV
and 230 kV switchable capacitor applications,the contingency problems are fully resolved.
Bridger -Populus 345 kV Lines 1 &2 (C02 and RAS variations)
In both cases (with and without the Path 18 Shunt Additions),this disturbance without any
RAS actions caused overloads on the Bridger -3 Mile Knoll 345 kV and Grace -Soda
138kV lines.RAS action,as noted for disturbance CO2a (Tripping of a Bridger Unit),
resolved these overloads.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
In the case without the Path 18 Shunt Additions,this disturbance was limiting for Path 18
flows.Outage CO3 caused the voltage at the PTRSNFUR 69kV bus to drop to 0.90 pu.
Increasing Path 18 flows to levels greater than 285MW North to South caused post-
contingency voltages at the PTRSNFUR 69kV bus to drop below 0.90 pu.In addition,the
RAS variations of disturbance CO3,including CO3a and CO3b (dropping one or two Bridger
units),caused the post-contingency voltages at the PTRSNFUR 69kV bus to be worse.Since
11/24/2010 Gateway West Project -Bridger Study Area Page 34 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 37 of 49
disturbances CO3d and CO3e both include Path 18 shunts additionswitching,they were not
applied to the case.
Without the Path 18 Shunt Additions,this outage limited Path 18 flows to 285 MW North to
South.With the Path 18 Shunt Additions and their employment in outage CO3d and CO3e,
Path 18's transfer limit is maintained at 337 MW North to South.
Populus -Ben Lomond 345 kV #2 and #3 Double Line Outage (C06 and RAS
variations)
In both cases (with and without the Path 18 Shunt Additions),this outage resulted in an
overloadof the Grace -Soda 138 kV line.In the case with Path 18 shunts,this outage also
resulted in an overload of the 3 Mile Knoll -Soda 138 kV line.Bypassing the 1/2 the series
capacitor in the Bridger -3 Mile Knoll 345kV line mitigates these overloads.
Populus -Terminal 345 kV +Treasureton -Bradv 230 kV Lines Outage (C12)
In the case without the Path 18 Shunt Additions,this outage resulted in an overload of the
Grace -Soda 138 kV line.Bypassing the 1/2 the series capacitor in the Bridger -3 Mile
Knoll 345kV line mitigates both of these overloads.In the case with the Path 18 Shunt
Additions,no emergency overloads were encountered.
6.11.3.Reactive Margin Analysis
From the base cases,margin cases (with and without Path 18 Shunt Additions)were created.The
margin cases stressed Path 18 North to South and Path C North to South flows by an additional
+5%as noted near the bottom of Appendix 3-11.All +5%cases solved for all contingencies
(with appropriate RAS actions),indicating sufficient reactive margins for both Level B and
Level C contingencies.Idaho's reactive margin requirements were also met for all contingencies
(with appropriate RAS actions).
6.11.4.Transient Stability Analysis
As shown on Appendix 4-11,dynamic simulations were run on the simultaneous cases (with and
without Path 18 Shunt Additions).Contingency B09 resulted in back swing under-frequency
deviations that exceed the standard WECC frequency deviationcriteria for load buses,but did
not exceed PacifiCorp's frequency deviation exception for Bridger unit buses on file with
WECC.All the other disturbances modeled did not result in transient stability problems or
criteria violations.
6.12.Path C Southbound vs.Bonanza West
6.12.1.Base Case Development
11/24/2010 Gateway West Project -Bridger Study Area Page 35 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 38 of 49
The Gateway West Project base case was modified to stress Path C North to South flows
simultaneous with stressed Bonanza West (Path 33)flows.Two base cases were developed.The
first case included Path C set at 2250 MW North to South with Bonanza West simultaneously set
at 749 MW.The second case included Path C set at 1849 MW North to South with Bonanza
West simultaneously set at 785 MW,Path 33's current transfer limit.
Multiplemargin test cases were developed with 5%additional flows across Path C and Bonanza
West.These cases are shown near the bottom of Appendix 3-12.
The resulting nomogram is shown on Appendix 2-11.
6.12.2.Post-Transient Analysis
Appendix 3-12 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline -Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in overloads on the Bridger -3 Mile Knoll 345 kV line.In the cases,the
line is rated at 1840 Amps and this loading informationhas been requested for design input
to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
3 Mile Knoll -Goshen 345kV Line (Contingency B06 and RAS variations)
In both cases,this outage without RAS resulted in overloads of the Grace -Soda and 3 Mile
Knoll -Soda 138 kV lines.Bypassing the 1/2 the series capacitor in the Bridger -3 Mile
Knoll 345kV line mitigates the loading on the 3 Mile Knoll -Soda 138 kV line entirely.
However,bypassing the 1/2 the series capacitor in the Bridger -3 Mile Knoll 345kV line
mitigates the loading on the Grace -Soda 138 kV line to approximately 101%of its
emergency rating.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
In the case with Path C stressed at 2250 MW North to South and Bonanza West at 749 MW,
this outage resulted in overloads on the Platt -Latham and Miners -Platt 230kV lines as well
as voltage deviations greater than 5%on many buses.The RAS actions as noted for
disturbance B35a,(600 MW of Aeolus area generation dropping,500 kV switchable
capacitors applied at Aeolus,and additional 230kV capacitors applied at Aeolus,Atlantic,
Miners and Platt)resolved these overloads and voltage deviations.
In the case with Bonanza West stressed at 785 MW and Path C at 1849 MW North to South,
this outage resulted in the following:overloads on all three Bridger 345/230 kV banks,the
Platt -Latham 230kV line,Miners -Platt 230kV line and Bar X-Echo Springs 230kV line;
voltage deviations greater than 5%on many buses;and post-contingency voltages in
Wyoming lower than 0.9 pu.The RAS actions,as noted for disturbance B35a,were enough
11/24/2010 Gateway West Project -Bridger Study Area Page 36 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 39 of 49
to mitigate the emergency overloads;however,they were not enough to mitigate the bus
voltagedeviations.The RAS actions as noted for disturbance B35d (600 MW of Aeolus area
generation dropping,500 kV switchable capacitors applied at Aeolus,and additional230kV
capacitors applied at Aeolus,Atlantic,Miners,Platt,Mustang and Riverton)resolved the
remaining voltage deviations.
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
This disturbance without any RAS measures caused both cases to diverge.With 600 MW of
generation dropping and 500 kV and 230 kV switchable capacitor applications (outage
B36a),the cases exhibitedenough reactive margin to solve.
In the case with Path C stressed at 2250 MW North to South and Bonanza West at 749 MW,
an overload on the Grace -Soda 138 kV line still remained even with the RAS actions
employed for disturbance B36a.The additional RAS measure of bypassing the 1/2 the series
capacitor in the Bridger -3 Mile Knoll 345kV line mitigated the Grace -Soda 138 kV line
overload.
In the case with Bonanza West stressed at 785 MW and Path C at 1849 MW North to South,
the RAS actions as noted for B36a were sufficient to mitigate all emergency overloads and
voltagedeviations.
Bonanza -Mona 345kV Line (Contingencv B40 and RAS variations)
In the case with Path C stressed at 2250 MW North to South and Bonanza West at 749 MW,
this outage resulted in overloads on the Emma Park -Upalco,Emma Park -Panther and
Panther -Carbon 138kVlines as well as voltage deviations greater than 5%on a few buses
near Upalco.In the case with Bonanza West stressed at 785 MW and Path C at 1849 MW
North to South,this outage resulted in overloads on the Emma Park -Upalco,Emma Park -
Panther and Panther -Carbon,Bonanza-Vernal 138kV lines as well as the Flaming Gorge
230/138 kV bank #2.This outage also resulted in voltage deviations greater than 5%on a
few buses near Upalco.The RAS actions as noted for disturbance B40a,(Tripping a Bonanza
Unit)resolved these overloads and voltage deviations.In both cases,Path C and Bonanza
West flows were limited by disturbance C04a with RAS tripping of a Bonanza unit and the
subsequent overload of the Emma Park -Upalco 138kV line.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
In both cases,this disturbance without any RAS actions caused overloads on the Bridger -3
Mile Knoll 345 kV and Grace -Soda 138kV lines.RAS action,as noted for disturbance
CO2a (Tripping of a Bridger Unit),resolved the Grace -Soda 138kVline overloads.The
Bridger -3 Mile Knoll 345kV line remained overloaded in both cases.Tripping two Bridger
units will mitigate the loading on the Bridger -3 Mile Knoll 345kV line;however,the
voltage drop around Path 18 starts to become an issue in the case with Path C stressed at
2250 MW North to South and Bonanza West at 749 MW.After the tripping two units,the
l1/24/2010 Gateway West Project -Bridger Study Area Page 37 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 40 of 49
post-contingency bus voltage at the PTRSNFUR 69.0 bus was 0.899 pu,which is right at the
limit of 0.9 pu.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
Disturbance CO3 without any RAS actions caused the case with Path C at 2250 MW North to
South and Bonanza West at 749 MW to diverge.Conversely,the case with Bonanza West at
785 MW and Path C at 1849 MW North to South solved following disturbance CO3.Both
cases solved following CO3a (CO3 plus RAS Tripping of one Bridger Unit)and CO3b (CO3
plus RAS Tripping of two Bridger Unit);however,the RAS tripping of the Bridger units
followingdisturbance CO3 caused the voltage at the PTRSNFUR 69kV bus to get worse (less
than 0.9 pu).Both cases solved following disturbance CO3d (CO3 plus RAS Tripping of one
Bridger unit plus RAS switching of capacitors at Amps and Big Grassy stations)exhibited
acceptable voltages in Wyoming and near Path 18.The Amps and Big Grassy capacitors
switched as part of the remedial action for disturbance CO3 are part of the Path 18 Shunt
Additions.
Populus -Ben Lomond 345 kV #2 and #3 Double Line Outage (C06 and RAS
variations)
In the case with Path C at 2250 MW North to South and Bonanza West at 749 MW,this
outage resulted in an overload of the Grace -Soda 138 kV line.Bypassing the 1/2 the series
capacitor in the Bridger -3 Mile Knoll 345kV line mitigates this overload.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event,
resulted in overloads of Springer -Gladstone 115 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.
6.12.3.Reactive Margin Analysis
From the base cases,margin cases were created.The margin cases stressed Bonanza West and
Path C North to South flows by an additional+5%as noted near the bottom of Appendix 3-12.
All +5%cases solved for all contingencies (with appropriate RAS actions),indicating sufficient
reactive margins for both Level B and Level C contingencies.Idaho'sreactive margin
requirements were also met for all contingencies (with appropriate RAS actions).
6.12.4.Transient Stability Analysis
As shown on Appendix 4-12,dynamic simulations were run on the simultaneous cases.
Contingency BO8 and B09 resulted in back swing under-frequency deviations that exceed the
standard WECC frequency deviation criteria for load buses,but did not exceed PacifiCorp's
frequency deviation exception for Bridger unit buses on file with WECC.
11/24/2010 Gateway West Project -Bridger Study Area Page 38 of 150
WECC Phase 2 Project RatingReport
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 41 of 49
In the case with Path C at 2250 MW North to South and Bonanza West at 749 MW,all the other
disturbances modeled did not result in transient stability problems or criteria violations.
In the case with Bonanza West at 785 MW and Path C at 1849 MW North to South,disturbances
Bl5 (Aeolus -Anticline 500 kV Line)and B16 (Aeolus -Mona Annex(Clover)500 kV Line)
caused voltage dips exceeding 20%for 20 cycles or more at multiple load buses.Disturbances
Bl5a and B16a with RAS (tripping 600 MW of Aeolus units and insertion of capacitors at the
Aeolus 500kV bus and at the Aeolus,Miners,Platt and Atlantic 230kV buses)mitigated the
voltage dips noted.
6.13.Path C Southbound with the MSTI Project
6.13.1.Base Case Development
The Gateway West Project base case was modified by the additionof the MSTI project.The case
was further modified by stressing Path C North to South flows simultaneous with MSTI Project
flows.One base case was developed with Path C set at 2250 MW North to South and MSTI
Phase Shifter flow simultaneously set at 1500 MW.To achieve a Phase Shifter flow of 1500
MW,it was necessary to dispatch 800 MW of total MSTI generation
Multiplemargin test cases were developed with 5%additional flows across Path C and the MSTI
Phase Shifter.These cases are shown near the bottom of Appendix 3-13.
The resulting nomogram is shown on Appendix 2-12.
6.13.2.Post-Transient Analysis
Appendix 3-13 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
Anticline --Populus 500 kV Line (Contingency B01 and RAS variations)
This outage results in an overload on the Bridger -3 Mile Knoll 345 kV line.In the cases,
the line is rated at 1840 Amps and this loading information has been requested for design
input to PacifiCorp to determine the magnitude of rating increase needed to rebuild the single
conductor portions of the line capable of withstanding the most severe contingencies
imposed by the Gateway West Project.Several RAS options are shown to allow selection of
line upgrade costs vs.the risks inherent with RAS.
3 Mile Knoll -Goshen 345kV Line (Contingency B06 and RAS variations)
This outage without RAS resulted in overloads of the Grace -Soda and 3 Mile Knoll -Soda
138 kV lines.Bypassing the 1/2 the series capacitor in the Bridger -3 Mile Knoll 345kV line
mitigates both of these overloads.
11/24/2010 Gateway West Project -Bridger Study Area Page 39 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 42 of 49
Aeolus --Anticline 500 kV Line (Contingency B35 and RAS variations)
This outage resulted in voltage deviations greater than 5%on many buses.The RAS actions,
as noted for disturbance B35a (600 MW of Aeolus area generation dropping,500 kV
switchable capacitors applied at Aeolus,and additional230kV capacitors applied at Aeolus,
Atlantic,Miners and Platt),resolved the voltage deviations.
Bonanza -Mona 345kV Line (Contingency B40 and RAS variations)
This outage resulted in overloads on the Emma Park -Upalco,Emma Park -Panther and
Panther -Carbon 138kV lines.The RAS actions,as noted for disturbance B40a (Tripping a
Bonanza Unit),resolved these overloads.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
This disturbance without any RAS actions caused overloads on the Bridger -3 Mile Knoll
345 kV and Grace -Soda 138kVlines.RAS action,as noted for disturbance CO2a (Tripping
of one Bridger Unit),resolved the Grace -Soda 138kV line overload.The Bridger -3 Mile
Knoll 345kV line remained slightlyoverloaded.Tripping of two Bridger units,as modeled in
disturbance CO2b,resolved both overloads.
Populus -Ben Lomond 345 kV #2 and #3 Double Line Outage (C06 and RAS
variations)
This outage resulted in an overload of the Grace -Soda 138 kV line.Bypassing the 1/2 the
series capacitor in the Bridger -3 Mile Knoll 345kV line mitigates this overload.
Palo Verde 2-unit loss with FACRI (N-2)
This contingency,with FACRI action and Desert SW load dropping planned for this event,
resulted in overloads of Springer -Gladstone l 15 kV line.Springer -Gladstone is a known
problem for which remediation is already planned.
6.13.3.Reactive Margin Analysis
From the base cases,margin cases were created.The margin cases stressed MSTI and Path C
North to South flows by an additional+5%as noted near the bottom of Appendix 3-13.All
+5%cases solved for all contingencies (with appropriate RAS actions),indicating sufficient
reactive margins for both Level B and Level C contingencies.Idaho's reactive margin
requirements were also met for all contingencies (with appropriate RAS actions).
6.13.4.Transient Stability Analysis
As shown on Appendix 4-12,dynamic simulations were run on the simultaneous cases.
Contingency B09 resulted in back swing under-frequency deviations that exceed the standard
11/24/2010 Gateway West Project -Bridger Study Area Page40 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 43 of 49
WECC frequency deviation criteria for load buses,but did not exceed PacifiCorp's frequency
deviationexception for Bridger unit buses on file with WECC.
6.14.Path C Southbound vs.Monument --Naughton
6.14.1.Base Case Development
The Gateway West Project base case was modified to stress Path C Southbound to 2250 MW
with Monument-Naughtonflows at 475 MW.Path C was stressed by reducing generation in
Utah and increasing generation in the Pacific Northwest.Monument -Naughtonflows were
controlled by the Monument phase shifting transformers.Loads in the Trona area of SW
Wyoming (Zone 668)were reduced by roughly 356 MW to prevent normal overloads of the
Rock Springs -Palisades 230kV Line.The resulting nomogram is shown on Appendix 2-13.
Two margin test cases were developed with 5%additionalflows across 1)Path C Southbound
and 2)Monument -Naughton.These cases are shown near the bottom of Appendix 3-14.
6.14.2.Post-Transient Analysis
Appendix 3-14 contains the tables associatedwith the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
3 Mile Knoll -Goshen 345 kV Line (ContingenciesB06 and B06a)
Contingency BO6 results in an overload on the Grace -Soda 138 kV line.The RAS modeled
in outage B06a,which included bypassing 1/2 of the 3 Mile Knoll series capacitor bank,
resolved the overload.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
Contingency B35 diverged without any RAS actions.The RAS actions,as noted for the
B35d (600 MW of Aeolus area generation dropping,500 kV switchable capacitors applied at
Aeolus and additional 230kV capacitors at Aeolus,Atlantic,Miners,Platt,Mustang,and
Riverton),resolved the voltage deviationproblems.
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
Contingency B36 diverged without any RAS actions.The RAS actions,as noted for the
B36v (600 MW of Aeolus area generation dropping,500 kV switchable capacitors applied at
Aeolus,Anticlin,Populus,additional 230kV capacitors at Aeolus,Atlantic,Miners,Platt,
Mustang,Riverton and Chappel,as well as one 345kV capacitor at Kinport),resolved the
divergence and didn't produce any WECC criteria violations.
Bonanza -Mona 345kV Line (Contingency B40 and RAS variations)
11/24/2010 Gateway West Project -Bridger Study Area Page 41 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 44 of 49
Outage B40 resulted in overloads on the Bonanza -Vernal,Emma Park -Upalco,Emma
Park -Panther and Panther -Carbon 138kV lines,Flaming Gorge 230/l38kV Transformer #2
as well as voltage deviations greater than 5%on a few buses near Upalco.The RAS actions,
as noted for contingency B40a (Tripping a Bonanza Unit),resolved these overloads and
voltage deviations.
Bridger -Populus 345 kV Lines 1 &2 (C02 and RAS variations)
Outage CO2 resulted in an overload on the Bridger -3 Mile Knoll 345 kV line.As noted
above,the loading numbers will be used as a design input for rebuilding the limiting
conductor sections.The overload was fully mitigated with RAS switching of one Bridger
unit as modeled in outage CO2a.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
Outage CO3 resulted in an overload on the Bridger-Rock Springs 230kV line and a low
voltage on a single bus (PTRSNFUR 69.0)near Path 18.RAS actions,as noted for the CO3d
(Tripping of Bridger unit and additional switchable capacitors applied at Big Grassy 161 kV
and Amps 230kV buses),resolved the overload and low voltage problems.
6.14.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-14.Both corner +5%cases solved for all contingencies (with appropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.14.4.Transient Stability Analysis
As shown on Appendix 4-14,dynamic simulations were run for various contingencies.
Contingency B08 and B09 with RAS variations resulted in back swing under-frequency
deviations;however,these deviations are within the exceptions for Bridger that are filed with
the WECC.See Appendix 21 for details of the TSS Approved exceptions for Bridger.
Contingency Bl5 (Aeolus -Anticline 500 kV line)also produced voltage deviations,which
were mitigated with some of the RAS actions simulated in the PT contingencies.
6.15.Path C Southbound vs.Rock Springs -Firehole
6.15.1.Base Case Development
The Gateway West Project base case was modified to stress Path C Southbound to 2250 MW
with Rock Springs /Firehole West flows at 640 MW.Path C was stressed by reducing
generation in Utah and increasing generation in the Pacific Northwest.Rock Springs /Firehole
11/24/2010 Gateway West Project -Bridger Study Area Page 42 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 45 of 49
West flows were controlled by the Monument phase shifting transformers.The resulting
nomogram is shown on Appendix 2-14.
Two margin test cases were developed with 5%additional flows across 1)Path C Southbound
and 2)Rock Springs /Firehole West.These cases are shown near the bottom of Appendix 3-15.
6.15.2.Post-Transient Analysis
Appendix 3-15 contains the tables associated with the post-transient study results for the import
cases.A discussion of several of the prominent outages follows.
3 Mile Knoll -Goshen 345 kV Line (Contingencies B06 and B06a)
ContingencyB06 results in an overload on the Grace -Soda 138 kV line.The RAS modeled
in outage B06a,which included bypassing 1/2 of the 3 Mile Knoll series capacitor bank,
resolved the overload.
Aeolus -Anticline 500 kV Line (Contingency B35 and RAS variations)
Contingency B35 without any RAS actions produced several voltage deviations greater than
5%,low voltages in Wyoming and various emergency overloads.The worst emergency
overload occurred on the Platt -Latham 230kV line at 111%.,and the worst voltage
deviation (17.4%)occurred at the Latham 34.5kV bus.Correspondingly,the lowest voltage
(0.838 pu)was experienced occurred at the Bairoil ll5kV bus.The RAS actions,as noted for
the B35d,(600 MW of Aeolus area generation dropping,500 kV switchable capacitors
applied at Aeolus and additional 230kV capacitors at Aeolus,Atlantic,Miners,Platt,
Mustang,and Riverton)resolved all the voltage deviations,low voltages and emergency
overloads.
Aeolus -Mona Annex (Clover)500 kV Line (Contingency B36 and RAS
variations)
Contingency B36 diverged without any RAS actions.The RAS actions,as noted for the
B36v (600 MW of Aeolus area generation dropping,500 kV switchable capacitors applied at
Aeolus,Anticlin,Populus,additional 230kV capacitors at Aeolus,Atlantic,Miners,Platt,
Mustang,Riverton and Chappel,as well as one 345kV capacitor at Kinport),resolved the
divergence and didn't produce any WECC criteria violations.
Bonanza -Mona 345kV Line (Contingency B40 and RAS variations)
Outage B40 resulted in overloads on the Bonanza -Vernal,Emma Park -Upalco,Emma
Park -Panther and Panther -Carbon 138kV lines,Flaming Gorge 230/138kVTransformer #2
as well as voltage deviations greater than 5%on a few buses near Upalco.The RAS actions
as noted for disturbance B40a,(Tripping a Bonanza Unit)resolved these overloads and
voltagedeviations.
Bridger -Populus 345 kV Lines 1 &2 (CO2 and RAS variations)
11/24/2010 Gateway West Project -Bridger Study Area Page 43 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 46 of 49
Outage CO2 resulted in an overload on the Bridger -3 Mile Knoll 345 kV line.As noted
above,the loading numbers will be used as a design input for rebuildingthe limiting
conductor sections.The overload was fully mitigated with RAS switching of one Bridger
unit as modeled in outage CO2a.
Bridger -Populus &Bridger -3 Mile Knoll 345 kV Lines (CO3 and RAS
variations)
This outage resulted a low voltage on a bus (PTRSNFUR 69.0)near Path 18.RAS actions,
as noted for the CO3d (Tripping of Bridger unit and additional switchable capacitors applied
at Big Grassy 161 kV and Amps 230kV buses),resolved the low voltage problems.
Populus -Ben Lomond 345 kV Double Line Outage (Contingencies C06 and C06k)
Contingency C06 resulted in an overload on the Grace -Soda 138 kV line.Bypassing 1/2 of
the 3 Mile Knoll series capacitor as modeled in outage C06k fully resolved the overload.
6.15.3.Reactive Margin Analysis
Both corner points of the nomogram were tested with +5%flow cases as noted near the bottom
of Appendix 3-15.Both corner +5%cases solved for all contingencies (withappropriate RAS
actions),indicating sufficient reactive margins for both Level B and Level C contingencies.
Idaho's reactive margin requirements were also met for all contingencies (with appropriate RAS
actions).
6.15.4.Transient Stability Analysis
As shown on Appendix 4-15,dynamic simulations were run for various contingencies.
Contingency B08 and B09 with RAS variations resulted in back swing under-frequency
deviations;however,these deviations are within the exceptions for Bridger that are filed with the
WECC.See Appendix 21 for details of the TSS Approved exceptions for Bridger.
Contingency B15 (Aeolus -Anticline 500 kV line)also produced voltage deviations,which
were mitigated with some of the RAS actions simulated in the PT contingencies.
7.ContingenciesStudied
A list of the studied contingencies are located in Appendix A
l1/24/2010 Gateway West Project -Bridger Study Area Page 44 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 47 of 49
8.Study Conclusions /Recommendations
Results of the simultaneous path interaction studies are summarized in Table 2.
Table 2
Simultaneous Max P ath FlowsPrimaryPathSecondaryPathLimitations Comments
Primary Secondary
AeolusWest;Aeolus South Flow Nomogram 2672 1700
BonanzaWest Nomogram 2672 785
Tot la 2672 650
Bridger /Anticline West Aeolus South Flow Nomogram 4095 1700 Primary Path to be increased to 4100 MW
Path C Southbound Nomogram 4100 2250
BonanzaWest Nomogram 4100 785
Path 18 No Restrictions 4100 337 Path 18 @ 337 Achieved w/Caps Added
MSTIProject No Restrictions 4100 1500
Monument-Naughton Nomogram 4100 475
Rock Spgs /Firehole West Nomogram 4100 640
Path C Southbound;Path 18 Nomogram 2250 337 Path 18 @ 337 Achieved w/Caps Added
BonanzaWest Nomogram 2250 785
MSTIProject No Restrictions 2250 1500
Monument-Naughton Nomogram Internal Path -To be added after PRG Review
Rock Spgs /Firehole West Nomogram Intemal Path -To be added after PRG Review
Throughoutthe studies,the Bridger West 345 Path was modeled at 2400 MW with reductions in
Bridger /Anticline West flows taken entirely on the Anticline -Populus 500 kV line.Although
this path uprate was not specifically requested in the study plan goals,in conjunction with the
Gateway West system,a Bridger West 2400 MW rating is proven by this study.
As can be seen from the post-transient results tables,for contingencies involvingthe Aeolus -
Anticline 500 kV and Aeolus -Mona Annex (Clover)500 kV lines have varying needs for RAS
switching to achieve post-transient solutions and acceptable voltage deviations.Details of
transfer levels commensurate with RAS generation tripping and capacitor switching will need to
be determined in additional studies prior to operation.It is expected that additional studies will
need to be developed to determine operating limits as the various components of the Gateway
West facilities are energized.
During the course of this study,post-transient voltage deviations and violations of the .90 pu
local voltage criteria were noted to be limiting for the most critical contingencies.As a
relatively economical expansion of transfer capabilities,some additional shunt capacitors were
added as follows;
11/24/2010 Gateway West Project -Bridger Study Area Page 45 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 48 of 49
1.Mona Annex 500;A total of three 200 MVar switchable shunt capacitor banks
2.Anticline 500 kV;A total of three 200 MVar switchable shunt capacitor banks
3.Populus 500 kV;Three 200 MVar switchable shunt capacitor banks
4.Mustang 230 kV;Two 30 MVar Switchable capacitor banks
5.Riverton 230 kV;One 41 MVar Switchable capacitor bank
6.Chapel Creek 230 kV;One 30 MVar Switchable capacitor banks
7.Bonanza 138 kV;One 60 MVar Switchable capacitor bank
Earlier studies of the Bridger /Anticline West vs.Path 18 studies showed a nomogram
relationship limited by voltage problems at the Path 18 buses.After changes to the base case
modeling from Northwestern,Idaho Power,and PacifiCorp,revised studies show the modeling
changes along with lowering the allowablePath 18 minimum voltage to .87 pu for Level B and
Level C contingencies,will allow simultaneous operation at full capacity on each path.While
not demonstrated in these studies,it is expected that these same modeling and voltage standard
changes will also impact the Path C southbound vs.Path 18 nomogram such that both paths can
be operated at their respective ratings.
Base case overloads noted to be most significant in Appendices 3-5,3-7,and 3-10.These
overloads appear in SE Wyoming and along the Colorado front range and are more prevalentin
cases with high loadings on Tot la and Bonanza West.In these cases,Tot 3,between SE
Wyoming and the "front range"area is some 400 -600 MW under its current operating limit of
1604 MW.The Cottonwood -Monument -Kettle Creek 115 kV and Kelker W -Rock Island
115 kV overloads appear to be in the Colorado Springs area and are probably more indicative of
a local area problem than anything associated with Gateway West.The Sidney DC tie and the
Sidney 230 /115 transformer overloads appear to be due to scheduling of the Sidney back-to-
back DC terminals.
In many of the path flow scenarios studied,overloads of the Grace -Soda 138 kV line,and to a
lesser extent,the 3 Mile Knoll -Soda 138 kV line were encountered.These overloads were as a
result of Bridger 345 kV system N-1 &N-2 outages and Path C N-2 outages.Tests of several
RAS options indicated that bypassing both segments of the 3 Mile Knoll capacitor bank resulted
in impacts to system voltages for several 345 kV outages.Bypassing ½of the 3 Mile Knoll 345
kV series capacitor bank was the most effective method of mitigating the 138 kV overloads for
most conditions while not causing other voltage problems.This assumes that Path 18
recommended voltage mitigations are installed.With these assumptions,the 3 Mile Knoll -
Soda 138 kV line was still slightlyoverloaded at 101%of its emergency rating and will need to
be either uprated,equipped for dynamic ratings,or be rebuilt with higher temperature
conductors.
Several scenarios show that for high levels of wind generation and an outage of one of the
Aeolus 500 /230 kV transformers,the remaining two transformers load to about 105%of their
emergency ratings.As these transformers have not yet been specified,it is recommended that
the top FOA ratings shown in the base case data be increased to 1764 MVA.
The Bridger -3 Mile Knoll 345 kV line maximum flows were encountered on the Bridger /
Anticline West vs.Path C southbound cases with Contingency CO2 and CO2a (Bridger -Populus
11/24/2010 Gateway West Project -Bridger Study Area Page 46 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.205
Case No.PAC-E-17-07
Page 49 of 49
345kV line DLO).With no gen drop RAS,the maximum line flow was found to be 2354 Amps.
If one Bridger Unit is tripped via RAS,then the maximum line flow is 2064 Amps.These flow
numbers can be found on Appendix 3-5.With this information,the cost of upgrading the
Bridger -3 Mile Knoll 345 kV line can be compared to continued exposure of the Bridger Units
to RAS tripping.
Dynamic stability analysis of Aeolus West vs.Bonanza West and Aeolus West vs.Tot la both
showed under frequency deviations down to 59.418 Hz.which is outside the TSS Approved
exceptions to the NERC/WECC reliability performance standards.Appendix 21 includes the
approved exceptions on pages C24 through C26.On page C26,the Bridger 22 kV generator
buses are allowed a under frequency deviation down to 59.42 Hz.This exception to the
standards may need to be amended to allow for the lower frequency excursion down to 59.40 Hz.
11/24/2010 Gateway West Project -Bridger Study Area Page 47 of 150
WECC Phase 2 Project Rating Report
Monsanto Exhibit No.206
Case No.PAC-E-17-07
20000-520-EA-17/Rocky Mountain Power Page 1 of s
October 12,2017
WIEC Informal Data Request 1.1
WIEC Informal Data Request 1.1
Please providethe dates for the additionaltransmission studies that will be conducted
(including,but not limited to that for the voltage support device)for the proposed
transmission line.These were the dates that Rick Vail had thought were in his Exhibit
RAV-10 but turned out not to be included.
Response to WIEC Informal Data Request 1.1
A summary of additional technical studies and corresponding completion dates,as of
October 9,2017,is outlined below:
GATEWAY WEST -SUBSEGMENT D.2 TECHNICAL STUDIES
The followingtechnical studies will be required to support the completion of Gateway West
-Sub-segment D.2 by 12/31/2020:
o Preliminary InternalTransmission Planning Studies
Purpose:(1)better definition of FDD facility requirements,(2)develop system
models in preparation for external consulting studies and (3)perform preliminary
Transfer CapabilityAssessment studies.
Type of Studies:
o Power Flow:steady-state,contingency and voltage stability analysis
o Dynamic Stability:transient system responseto critical system events
o Stiffhess Factor Analysis (short circuit ratio):evaluation of system
robustness-utilizing both power flows and short circuit duty analysis
Who Involved:East Side Transmission Planning Staff with model building
support from the West Side Transmission Planning Staff
When Studies Would Be Performed:
o Aeolus SVC -dynamic need identification:Completed 3/3/17 -3/6/17
o Detailed internal studies (power flow and stability /evaluatingwide range
of operating conditions),which are necessary to support (1)better
definition of FDD facilityrequirements,(2)PSCAD (power system
computer aided design)modeling and other modeling by extemal
consultants,and (3)preliminary Transfer CapabilityAssessment studies
(TOT 4A,TOT 4B and Aeolus West):Completed 5/31/17
Study Follow-up:
o Due to interest shown by various stakeholders (via data requests)to
review the D.2 Project preliminary study findings,a preliminary study
report for the project is currently being drafted.The report should be
available by October 13,2017.
Monsanto Exhibit No.206
Case No.PAC-E-17-07
20000-520-EA-17/Rocky MountainPower Page 2 of s
October 12,2017
WIEC Informal Data Request 1.1
o External Consultant Studies [included on PMO Gateway -Subsegment D.2 schedule]
Purpose:define system/equipment electrical studies we will have Electranix
perform
Type of Studies:
o SSR,Power Flow,Dynamic Stability,PSCAD Modeling
Who Involved:GE Energy Consulting,Electranix,Power Engineers,or
equivalent consultant
When Studies Would be Performed:
o Initial data provided by Transmission Planning:Completed 5/31/17
o Study Schedule:PMO Gateway -SubsegmentD.2 schedule;SSR [GE]
Studies:10/31/17;D.2 Project [Electranix]:11/24/17
o D.2 Project -230 kV Alternative Studies (including DJ Retirement)
Purpose:provide technical analysis for a D.2 Project 230 kV alternative that
includes retirement of the Dave Johnson generating plant.(Intended for
submission to requesting public utility commissions.)
Type of Studies:
Power Flow,Dynamic Stability,PSCAD Modeling
Who Involved:East Side Transmission Planning Staff and Electranix
When Studies Would be Performed:
Initial studies by Transmission Planning:Completed 8/15/2017
PMO Gateway -Subsegment D.2 schedule;Electranix:11/24/17
o Latham Dynamic Device Evaluation
Purpose:refine the architecture (SVC/STATCOM)and size of the Lathan
dynamic device
Type of Studies:
Dynamic Stability,PSCAD Modeling
Who Involved:East Side Transmission Planning Staff and Electranix
When Studies Would be Performed:
More detailed studies by Transmission Planning:10/31/2017
PMO Gateway -Subsegment D.2 schedule,Electranix:1/31/18
o FAC-013-2Transfer CapabilityAssessment studies [studies performed in parallel with
consulting studies above]
Monsanto Exhibit No.206
Case No.PAC-E-17-07
20000-520-EA-l7 /Rocky MountainPower Page a of s
October 12,2017
WIEC Informal Data Request 1.1
NOTE:Path rating'studies for the Aeolus West transmission path for the full Energy
Gateway project were completed in July 2011;therefore,these studies will not be needed
at this time.Therefore,FAC-Ol3-2 Transfer CapabilityStudies will be performed to
demonstrate east to west improvement in the Wyoming transmission system performance
due to adding the D.2 Project.
Purpose:perform necessary technical studies to assess the Transfer Capability of
the Aeolus West path.
Type of Studies:
o Power Flow,Dynamic Stability,Voltage Stability;interaction analysis
with other transmission paths
Who Involved:East Side Transmission Planning Staff,Transmission Planners
from other utilities (WAPA,Basin,Black Hills,Tri-State,Idaho Power,Deseret
G&T,NorthWestern Energy,and other WECC members who anticipate an
interaction with their system.
When Studies Would be Performed:
While preliminary studies can be performed prior to award of the EV2020 RFP in
1Ql8,the assessment of the Aeolus West path FAC-013-2 Transfer Capability
with other utilities cannot be formally initiated until specific new southeast
Wyoming wind resources have been identified.
o Initial Transfer Capability Studies:
Technical studies and draft report.
Paths:TOT 4B,TOT 3,TOT lA,Bonanza West.(Paths
Interacting with Bridger West:Path C,Montana-Idaho)
Date:September 2017 -May 2018
o Joint Studies:
Formation of Study Group:May 2018
Initial Kick-Off Meeting:June 2018
Development of Study Plan and Base Cases:July -August 2018
Perform both non-simultaneous and simultaneous analysis:
September -December 2018
Study Group -Sensitivity Studies:January -March 2019
1 At the March 30,2010,Gateway West and Gateway South combined project review meeting participants
approved the Gateway Phase 2 Study Plan and agreed that incremental transmission limitations for transmission
segments that are added between stages,will be addressed via SOL (System Operating Limit)studies.[This same
process was previously followed and successfully demonstrated by BPA and Avista for the West of Hatwai
Expansion project.]
Monsanto Exhibit No.206
Case No.PAC-E-17-0720000-520-EA-l7 /Rocky MountainPower Page 4 of 5
October 12,2017
WIEC Informal Data Request 1.1
Group Consensusand Development of FAC-013-2 Transfer
Capability assessment report for WECC:March -May 2019
o Western Interconnection Studies:
Issuance of FAC-013-2 Transfer Capabilityassessment report and
Request WECC inputs [60 days]:June -July 2019
Address outstanding issues:August -October 2019
Request Path Rating Catalog modification:October 2019
o RAC Committee Acceptance:
WECC RAC Chairman issues letter granting Transfer Capability:
November 2019
o Completion Project:
All facilities in-service to support transfer capability [Target:
December 2020]
o Remedial Action Scheme (RAS)-Additions/ModificationsStudies
o Purpose:The following RAS scheme additions/modifications were identified in
FDD 5.0:
A new generation tripping (RAS)scheme will needto be implemented
at Aeolus,which would trip generation in the Foote Creek/Aeolus area in
the event that the Bridger/Anticline-Aeoluslines (or transformers)trip
during high transfers on the Aeolus West transmission path.
Initial technical studies has identified tripping up to ~660 MW of
generation during high transfer conditions.Specific generation tripping
locations will be determined based on follow-on technical studies.Specific
RAS arming levels for lower flow conditions will need to be determined
during the same studies.
Jim Bridger C/D RAS modifications will be required due to the
redispatch of Jim Bridger generation necessary to accommodate new wind
generation in eastern Wyoming,while maintaining the 2400 MW rating on
the Bridger West transmission path.
New LGI generation trippingRAS schemes (funded by LGI customers)
may be required (as identified in the LGIA)for specific new/modified
wind generation facilities to maintain transmission system reliability
during local area transmission outages.
o Type of Studies:
Power Flow,Dynamic Stability
o Who Involved:East Side Transmission Planning Staff with model building
support from the West Side Transmission Planning Staff for the Bridger C/D RAS
studies
Monsanto Exhibit No.206
Case No.PAC-E-17-07
20000-520-EA-17/Rocky MountainPower Page s of s
October 12,2017
WIEC Informal Data Request 1.1
o When Studies Would be Performed [anticipated to be in parallel with the FAC-
013-2 Transfer CapabilityAssessment above,or immediately following]:
Study Schedule:Initiating in May 2018,following issuance of FAC-013-
2 Transfer Capabilityanalysis reports.Studies would take 6-9 months to
performs,depending on anticipated changes to the Jim Bridger C/D RAS
scheme.
Respondent:Craig Quist
Witness:Rick Vail
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 1 of 21
20000-520-EA-17 /Rocky Mountain Power
October 13,2017
WIEC Data Request 7.1
WIEC Data Request 7.1
Please refer to RMP's response to WIEC Data Request 2.2.During the September25,
2017 technical conference in this proceeding,RMP indicated that it or its consultants had
completed additional power flow and dynamic stability analyses and/or studies beyond
the November 24,2010 WECC study provided in response for WIEC Data Request 2.2
that support the incremental transfer capability of the proposed new transmission line
project will be 750 MW and it could enable up to 1,270 MW of new resource
interconnection.
(a)Please provide a complete copy of all of these additional power flow and dynamic
stability analyses or studies.
(b)Please provide a complete copy of all PSS/E power flow and dynamic stability results
that underlie the analyses and studies provided in response to subpart a.
(c)Please provide an electronic copy of all Siemens PTI PSS/E and MUST monitoring,
contingency,subsystem files,PSAS,IPLAN and Python files utilized to perform the
analyses and studies provided in response to subpart a.
(d)Please provide in "sav"format a complete copy of the Siemens PSS/Epower flow
files used to perform the analyses and studies provided in response to subpart a.
When providing these files,please identify the version of PSS/Efrom which they
were produced.
(e)Please provide a complete copy in electronic format of all Microsoft Excel workbook
and worksheets used to compile,process,or analyze the results from the analyses and
studies provided in response to subpart a.with all formulae,links,and underlying
workbooks and worksheets intact.
Response to WIEC Data Request 7.1
The power flow files provided in Highly Confidential Attachment WIEC 7.1-1 are
considered to be highly confidential and commercially sensitive.The Company requests
special handling.Please contact Stacy Splittstoesser at [phone] to make
arrangements for review of each of the following highly confidential attachments.
Please refer to Attachment WIEC 7.1-2 and Confidential Attachment WIEC 7.1-3,which
provide the requested study report and supporting documentation.
Confidential information is provided subject to the terms and conditions of the protective
agreement in this proceeding.
Respondent:Craig Quist
Witness:Rick Vail
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 2 of 21
Aeolus West Transmission Path
Transfer Capability Assessment
/
Preliminary Study Report
Revision 1.0
October 2017
Prepared by
PacifiCorp -Transmission Planning
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 3 of 21
Table of Contents
Executive Summary.....................................................................1
1 Introduction ......................................................................4
1.1 Purpose..............................................................................4
1.2 Plan of Service ...................................................................................4
1.3 Planned OperatingDate ................................................................4
1.4 Scope.............................................................................5
2 Study Criteria.......................................................................5
2.1 Thermal Loading...................................................................5
2.2 Steady State Voltage Range.....................................................................6
2.3 Post-Transient Voltage Deviation...................................................................6
2.4 TransientStability Analysis Criteria............................................................6
2.5 TransientVoltage Response..................................................................7
3 Base Case Development...................................................................................8
3.1 Base Case Selection ......................................................................8
3.2 GeneratingFacility Additions................................................................10
3.3 Base Case Modification and Tuning....................................................................11
4 Path Studies ..............................................................................11
4.1 Aeolus West vs.TOT 4B .......................................................................11
4.2 Base Case Development....................................................................14
4.3 Transient Stability Analysis .......................................................................14
5 Sensitivity Analysis ........................................................................17
6 Study Conclusions............................................................................18
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 4 of 21
Executive Summary
This assessment was conducted to document the Transfer Capability of the Aeolus Westi
transmission path once the Gateway West -Subsegment D.22 (Bridger/Anticline -Aeolus)
transmission facilities (D.2 Project)are added to the Wyoming transmission system.
The Aeolus West transmission path (see Figure 1)is a new path that will be formed by
adding the D.2 Project in parallel with the TOT 4A3 (Path 37)transmission path facilities.
The anticipated in-service date for the D.2 Project is November 2020.The D.2 Project will
include the following major transmission facilities:
Aeolus-Anticline 500 kV new line,Figure 1:Aeolus West Transmission Path
Shirley Basin -Freezeout 230 kV line
loop-in to Aeolus,
Aeolus 500/230 kV substation,^t
Anticline 500/345 kV substation,
Bridger -Anticline 345 kV new line,I i
Latham dynamic voltage control
h
rleey
Basin -Aeolus 230 kV #2
Aeolus -Freezeout 230 kV line
rebuild,and 3 --
Freezeout -Standpipe 230 kV line reconstruction
The WECC 2021-22 HW power flow base case was utilized for the Aeolus West transfer
capability studies.In support of the EV2020 initiative,which calls for the addition of new
and repowered wind resources in Wyoming,the base case was modified to achieve the
1 The Aeolus West path will include the following major transmission elements:Aeolus*-Anticline 500 kV,Platte*-Latham 230 kV,Mustang*-Bridger 230 kV and Riverton*-Wyopo 230 kV transmission lines.(*meter location)
2 Gateway West -Subsegment D.2 is a key component of the Energy Vision 2020 (EV2020)initiative that was
announced by PacifiCorp on April 4,2017.Other components of the EV2020 initiative include repowering
PacifiCorp's existing wind fleet in southeast Wyoming and adding approximately 1,100 MW of new wind
generation east of Bridger/Anticline.
3 The existing TOT 4A (Path 37)path is comprised ofthe Riverton*-Wyopo 230 kV,Platte -Standpipe*230
kV and Spence*-Mustang 230 kV transmission lines.(*meter location)
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 5 of 21
transfer levels evaluatedby adding 1169 MW (up 1270 MW as a sensitivity)of anticipated
generationresource currently in the PacifiCorp (PAC)-Large Generation Interconnection
(LGI)queue,which were used as a proxy for new resources.For different Aeolus West
transferlevels (heavy and light)resources in eastern Wyoming were redispatched relative to
the Jim Bridger GenerationPlant.
Contingenciesthat were considered in this analysis include:
N-1 of D.2 Project facilities
N-1,N-2 Bridger contingencies
All Wyoming transmission system contingencies performed as part of the TPL-001-4
annual assessment.
For the preliminary Transfer Capability assessment,simultaneous interaction between the
Aeolus West path and the TOT 4B path was evaluated;however,the interaction with other
transmission paths (Yellowtail South,Jim Bridger West,TOT lA and TOT 3)was monitored
throughoutthe study.
As part of the analysis,sensitivity studies were also performed to evaluate:(1)performance
of different dynamic voltage control architecture (SVC vs STATCOM)at Latham,and (2)
variations in the assumed magnitudeand location of new wind generation,up to 1270 MW.
Conclusions
Technical studies demonstrated that with the addition of the planned D.2 Project facilities to
the Wyoming transmission system,system performance will meet all NERC and WECC
performancecriteria.
Preliminary power flow studies demonstrate that by utilizing existing and planned southeast
Wyoming resources4,the Aeolus West transmission path can transfer up to 1696 MW under
simultaneous transfer conditionswith the TOT 4B transmission path,effectively'increasing
the east to west transfer levels across Wyoming by 817.5 MW.Power flow findings also
indicated:
4 Southeast Wyoming Resources:Existing Wind:1124 MW,Dave Johnston (net)717 MW,Repower Wind:
zero MW to 137.5 MW,New Wind:1152 -l169 MW at various locations
*Effective transfers were determinedby subtracting the existing TOT 4A path maximum'*transfer level (960
MW)from the Aeolus West transfer level (1696 MW)and adding the Platte area loads (82.5 MW)that are up-
stream of the Aeolus West metering point.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 6 of 21
Dynamic voltage control is necessary at the Latham 230 kV substation to mitigate
low voltage conditions resulting from loss of Bridger/Anticline -Aeolus transmission
facilities.
Under certain operating conditions,three different Remedial Action Schemes (RAS)
will need to be implemented to trip generation following outage of specific
transmission facilities.
The location (and output level)of new and repowered wind resources can influence
the transfer capability level across the Aeolus West transmission path.
While a wide range of disturbances were evaluated,dynamic stability studies identified that
the slowest post fault voltage recovery will occur for a fault at Anticline or Jim Bridger 345
kV bus followed by loss of the Bridger/Anticline -Aeolus transmission segment and the
planned operation of a generation tripping (RAS)scheme.The stability analysis
demonstrated that all planned system events met the stability performance criteria.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 7 of 21
1 Introduction
1.1 Purpose
The purposeof this study is to identify the new Aeolus West path limitation,the interaction
between the Aeolus West and the TOT 4B transmission paths by creating a nomogram,
system limitation(s)and various Remedial Action Scheme (RAS),such that the
interconnectedtransmission BES in Wyoming can support additional generationwith the D.2
Project and can be operated reliably during normal and contingencyoperations throughout
the planning horizon.
This report outlines the power flow and dynamic stability study findings from the Aeolus
West transfer capability assessment and identifies performanceof the BES in Wyoming with
the addition of the D.2 Project and 1169 MW of new wind generation.
1.2 Plan of Service
The D.2 Project consists of the following system improvements:
1.A new 500 kV Anticline substation
2.A new 230/500kV,1600 MVA transformerat Aeolus
3.A new 137.8-mile 3x1272 ACSR (Bittern),500 kV line between Aeolus and
Anticline substations
4.A new 500/345 kV,1600 MVA transformerat Anticline
5.A new 5.1-mile 3x1272 ACSR (Bittern),345 kV line between Anticline and Jim
Bridger substations
6.A new 50 MVAr reactor at Aeolus 230 kV bus
7.A new 200 MVAr shunt capacitor bank at Aeolus 500 kV bus
8.A new 200 MVAr shunt capacitor bank at Anticline 500 kV bus
9.Rebuild of the Aeolus -Freezeout and Freezeout -Standpipe 230 kV lines to 2x1272
ACSR (Bittern)conductor
10.A new 2xl557 ACSR/TW Aeolus -ShirleyBasin 230 kV #2 line
11.A new dynamic reactivedeviceat Latham230 kV substation.
1.3 Planned Operating Date
The plan of service for the facilities to be operationalis by November2020.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 8 of 21
1.4 Scope
The Aeolus West transfer capability assessment assumes the addition of new wind generation
facilities plus the repoweredwind generationmodeling data as noted in Table 1.While the
new technology and model information of the repoweredunits was used in the steady-state
and transient stability analysis,no incremental MW output was considered;i.e.,each
repowered facility was limited to its current Large Generator Interconnection (LGI)
agreement capacity.The study was performed using a 2021-22 heavy winter WECC
approvedcase which was modified to include the D.2 Projects and wind generation facilities.
The system model assumed summer line ratings to assess the thermal limitation of the
Wyoming system.Load served from Platte is normally represented as an open point between
Platte -Whiskey Peak 115 kV.The system configurationwith Platte l15 kV normally open
is presently the most limiting scenario for the existing TOT 4A/4B nomogram.
Table 1:GeneratingResourceScenario
East Wyoming Jim Bridger Gen East Wyoming Repowered Wind New SE
Thermal Gen level (MW)Existing Wind (MW)Wyoming.Wind
(MW)(MW)(MW)
Dave Johnston -1400 -2100 1124 0.0 1169
Online (Foote Creek,Rock Repowering wind See Table 4
Wyodak -Online River,High Plains,turbine
Seven Mile Hill,representation was
Dunlap,Root added to the
Creek,Top of the system model but
World,Glenrock,the output was
Three Buttes,limited to existing
Chevron)LGI levels
2 Study Criteria
2.1 Thermal Loading
For system normal conditions described by the PO6 event,thermal loading on BES
transmission lines and transformers is requiredto be within continuousratings.
6 Facility outage events that are identified with "P"designations are referenced to the TPL-001-4 NERC
standard.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 9 of 21
For contingencyconditions described by Pl-P7 category planningevents,thermal loading on
transmission lines and transformers should remainwithin 30-minuteemergency ratings.
The thermal ratings of PacifiCorp's BES transmission lines and transformers are based on
PacifiCorp's Weak Link Transmission Database and Weak Link TransformerDatabase as of
March 31,2017.
2.2 Steady State Voltage Range
The steady state voltageranges at all PacifiCorp BES buses shall be within acceptable limits
as established in PacifiCorp's Engineering Handbook section 1B.3 "Planning Standards for
TransmissionVoltage"'as shown below.
Table 2:Voltage Criteria
OperatingSystem Normal Conditions (P0)Contingency Conditions (P1-
P7)Configuration Vmin (pu)Vmax (pu)Vmin (pu)Vmax (pu)
Looped 0.95 1.06"0.90 1.10
Radial 0.90 1.06"0.85 1.10
Steady state voltage ranges at all applicable BES buses on adjacent systems were screened
based on the limits established by WECC regional criterion as follows:
95%to 105%of nominal for PO event (system normal),
90%to 110%of nominal for Pl-P7 events (contingency).
2.3 Post-Transient Voltage Deviation
Post-contingency steady state voltage deviation at each applicable BES load serving bus
(having no intermediate connection)shall not exceed 8%for Pl events.
2.4 Transient StabilityAnalysis Criteria
All voltages,frequencies and relative rotor angles are required to be stable and damped.
Cascading or uncontrolledseparation shall not occur and transient voltage response shall be
within established limits.
7 PacifiCorp EngineeringHandbook "Planning Standards for Transmission Voltage,"April 8,2013.
8 In some situations,voltages may go as high as 1.08 pu at non-load buses,contingent upon equipment rating
review.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 10 of 21
2.5 Transient Voltage Response
Transient stability voltage response criteria are based on WECC Regional Performance
Criteria WRl.3 through WRl.5 as follows:
Transient stability voltage response at the applicable BES buses serving load (having
no intermediate connection)shall recover to at least 80%of pre-contingency voltage
within 20 seconds of the initiating event for all Pl-P7 category events,for each
applicable bus servingload.
For voltage swings following fault clearing and voltage recovery above 80%,voltage
dips at each applicable BES bus serving load (having no intermediatebuses)shall not
dip below 70%of pre-contingency voltage for more than 30 cycles or remain below
80%of pre-contingency voltage for more than two seconds for all Pl-P7 category
events.
For contingencies without a fault (P2-1 category event),voltage dips at each
applicable BES bus serving load (having no intermediate buses)shall not dip below
70%of pre-contingencyvoltage for more than 30 cycles or remainbelow 80%of pre-
contingency voltage for more than two seconds.
The following criteria were used to investigate the potential for cascading and uncontrolled
islanding:
Load interruption due to successive line tripping for thermal violations shall be
confined to the immediate impacted areas and shall not propagate to other areas.The
highest available emergency rating is used to determine the tripping threshold for
lines or transformerswhen evaluating a scenario that may lead to cascading.
Voltage deficiencies caused by either the initiating event or successive line tripping
shall be confined to the immediate impacted areas,and shall not propagate to other
areas.
Positive damping in stability analysis is demonstratedby showing that the amplitude of
power angle or voltage magnitudeoscillations after a minimum of 10 seconds is less than the
initial post-contingency amplitude.Oscillations that do not show positive damping within a
30-second time frame shall be deemed unacceptable.
Stability studies shall be performed for planning events to determinewhether the BES meets
the performancerequirements.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 11 of 21
Single contingencies (Pl category events):No generating unit shall pull out of
synchronism (excludes generators being disconnected from the system by fault
clearingaction or by a special protectionsystem).
Multiple contingencies (P2-P7 category events):When a generator pulls out of
synchronism in the simulations,the resulting apparent impedance swings shall not
result in the tripping of any transmission system elements other than the generating
unit and its directly connected facilities.
Power oscillations are evaluatedby exhibiting acceptable damping.The absence of
positive damping within a 30-second time frameis considered un-damped.
3 Base Case Development
3.1 Base Case Selection
The base case development process involves selecting an approved WECC base case,
updatingthe models to represent existing and plannedfacilities (D.2 Project transmission and
wind generationfacilities)and then tuning the cases to maximum transfer conditions on the
WECC transmission path(s)being studied.For this study purpose,the published WECC
base case that is close to the projects'in-service date of November2020,which has average
load conditions based on 2021 load projection and availability of a stability case,was
selected.The WECC approvedbase case 2021-22 HW (created on August 19,2016)was
selected,which meets these criteria.This study focused on simultaneous transmission path
interaction in the Wyoming area between the Aeolus West and the TOT 4B transmission
paths;however,other transmission paths such as Yellowtail South (non-WECC path),Jim
Bridger West,TOT lA and TOT 3 (See Appendix A for path definitions)were monitored
throughoutthe study.
The various critical components for this study purpose from selected 2021-22 HW base case
are listed below:
Table 3:Wyoming Load,Generation and Platte Normal Open Configurationin Base Case
North Wyoming PAC Load (including Wyodak load of 42 391 MWMW)
North Wyoming -Western Area Power Administration 211 MW(WAPA)Load
Eastern Wyoming PAC Load (including DJ load of 56 MW)474 MW
Eastern Wyoming PAC loads on WAPA system 95 MW
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 12 of 21
Central Wyoming Load (including JB load of 130 MW)434 MW
Yellowtail South Flow 192 MW
YellowtailGeneration 140/260 MW (Online/Max)
WAPA's Existing Small Generation*in North Wyoming 26/50 MW(Online/Max)
WAPA's Existing Small Generationl°in Eastern Wyoming 484/584 MW(Online/Max)
Wyodak Generation (PacifiCorp/Black Hills)350/380 MW (Online/Max)
Dry Fork Generation (Basin Electric)420/440 MW (Online/Max)
Gross Laramie RiverGeneration I (WAPA's swing machine)605 MW(Max)
Gross Laramie RiverGeneration II 590/605 MW(Online/Max)
Gross Dave Johnston (DJ)Generation 700/774 MW(Online/Max)
Total Existing PAC East Wyoming Wind"Generation 885.7/1124 MW (Online/Max)
Rapid City DC W Tie 130 W2E (200 MW-bidirectional)
Stegall DC Tie 100 E2W (110 MW-bidirectional)
Sydney DC Tie 196 E2W (200 MW-bidirectional)
TOT4A 627 MW
TOT 4B 469 MW
Jim Bridger (JB)Generation 2200 MW
Jim Bridger West Flow 2027 MW
TOT 3 1259.1 MW
TOT lA 195 MW
Platte -Mustang 115 kV Normal Open point Platte -Normal Open
WAPA'ssmall generation in north Wyoming includes;Boysen,BBill,Heart MT,Shoshone,Spring Mtn
to WAPA's small generation in eastern Wyoming includes;Alcova,Fremont,Glendo,Guernsy,Kortes,
Seminoe,CLR 1,SS_Genl AND CPGSTN
"PAC eastern Wyoming wind generation includes;Root Creek,Three Buttes,Top of World,Glenrock,Rolling
Hills,Dunlap.Seven Mile Hill,Foote Creek and High Plains wind generation
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 13 of 21
3.2 GeneratingFacility Additions
Because the specific size and location of new and repowered Wyoming wind generation
associated with the EV2020 initiative will not be known until lQl8,this study evaluated
anticipated Wyoming wind generation options 2 for the preliminary Aeolus West analysis,
based on requests in the PacifiCorp Large Generation Interconnection (LGI)queue as a
proxy for new resources.The following generating facility assumptions were made and
added into the base case.
Table4:AssumedGenerationProjects
Proposed New Wind Facilities Project size Point of Interconnection
Aeolus/Freezeout/ShirleyBasin Area 320 MW Freezeout 230 kV
250 MW Aeolus 230 kV
250 MW Shirley Basin 230 kV
250 MW Shirley Basin 230 kV
Foote Creek Area 99 MW Foote Creek -High Plains 230 kV line
230 kV
Repowered Wind Facilities13
High Plains/McFadden Ridge I Gen 0.0 MW High Plains 230 kV
Repowering (+29.75 MW)
Seven Mile Hill Gen Repowering 0.0 MW Freezeout 230 kV
(+27.65 MW)
Dunlap Gen Repowering (+26 MW)0.0 MW Shirley Basin 230 kV
Glenrock Gen Repowering I (+27.65)0.0 MW Windstar 230 kV
Glenrock Gen Repowering H (+27.65 0.0 MW Windstar 230 kV
MW)
TOTAL 1169 MW
See Appendix B for detail on repoweredand new wind farm modelling assumptions.
"An additional resource option is outline in Sensitivity Study -Section 5.B.
"The repowered generation was modeled,but the repowered MW output was not increased in the base case,
i.e.increase machine size was modeled,but output was limited to existing LGI agreement
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 14 of 21
3.3 Base Case Modification and Tuning
The 2021-22HW base case was modified to reflect the most recent Foote Creek,High Plains,
Top of the World and Three Buttes wind generation modeling as per recent MOD-032 data
submitted by each generator owner (GO).Transmission line impedances between Dave
Johnston and Standpipe were verified and updated and the transmission line ratings in the
2021-22 heavy winter case were modified to summer ratings,which represent the most
conservative thermal limitations.The Platte -Standpipe 230 kV dynamic line rating of
608/666/680 MVA was assumed during the analysis.
The new wind resources listed in Table 4 were added to the base case and the existing
repowered wind farm generatormodels and collector system data were updated.The Aeolus
West path was stressed by maximizing the output on all of the existing and new wind
generation facilities.Output for the repowered wind generation facilities was limited to the
existing LGI agreementgeneration levels.The additional generation in southeast Wyoming
was re-dispatched with Jim Bridger,central and southern Utah generation.The Jim Bridger
generation output was maintained such that Jim Bridger West path flows were held at 2400
MW.
As per the available data obtained from various wind generationfacilities at the time of this
study analysis,the base cases were reviewed and adjusted to ensure voltages in the collector
system of wind generation facilities were below 1.05 p.u.and that there was no reactive
power loop flow between the main generator step-up transformers GSU's for wind
generation facility.This process involved tuning transformer and generatorparameters such
that generatorswere producing appropriate reactive power output.Additionally,within the
230 kV transmission system it was verified that the shunt reactive devices were accurately
represented,voltage profiles were normal,reactive power flows were within normal
operating ranges and transmission system voltage was maintained to match acceptable
PacifiCorp TransmissionVoltage Schedules.
4 Path Studies
4.1 Aeolus West vs.TOT 4B
Based on the assumptions outlined above the study demonstrated that the Aeolus West
maximum transfer capability limit is 1696 MW,while meeting all NERC and WECC
performance criteria.While this transfer level is 735 MW above the present TOT 4A (960
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 15 of 21
MWl4)path limit for similar conditions,east to west transfers have effectively increased by
817.5 MW due to shifting the Platte area load (82.5 MW)east of the Aeolus West cut plane.
The Aeolus West path was stressed using by 3010 MW of total generation resources,which
includes thermal (Dave Johnston,717 MW -net),existing wind (1124 MW),and new wind
(1169 MW)resources.It was assumed that the following eastern Wyoming thermal
generation was available for redispatch to maintain transfers on the Aeolus West and the
TOT 4B transmission paths:
Wyodak (268 MW)
DaveJohnston (717 MW,net)
The maximum flow limitation of 1696 MW was achievedby utilizing all new and existing
wind resources and reducingDaveJohnston generation by 149 MW.
Table 5:Aeolus West and TOT 4B Corner Point Cases (See Figure 2)
Case TOT TOT 4B Platte -Limiting Element Outage
4A (MW)Latham
(MW)(MVA)
1 1696 103 546 Platte-Latham 230 kV line's Anticline -Aeolus 500
kV line outage with
RAS
2 1681 299 548 Platte-Latham 230 kV line's Anticline -Aeolus 500
kV line outage with
RAS
3 1651 499 547 Platte-Latham 230 kV lines Anticline -Aeolus 500
kV line outage with
RAS
4 1608 700 547 Platte-Latham 230 kV lines Anticline -Aeolus 500
kV line outage with
RAS
5 1575 857 -Yellowtail -Sheridan 230 kV N-0
line
547 Platte-Latham 230 kV line"Anticline -Aeolus 500
kV line outage with
RAS
14 Niaximum nomogram point with normal open point at Platte and the dynamic line rating on Platte -
Standpipe 230 kV line is utilized
"Platte-Latham 230 kV line flow may exceed the 557 MVA summer emergency rating depending on load at
Platte.Percentage loading is based on current rather than MVA.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 16 of 21
See Appendix C for power flow diagrams.
In the study,three different remedial action schemes (RAS)were consideredfor N-1 outages:
i.Aeolus RAS to trip up to 640 MW of wind generationdepending on pre-outageflow
conditions for any of the new transmission element outages between Aeolus -Jim
Bridger.
ii.Freezeout RAS to trip up to 140 MW of generation in the Freezeout area for the
Aeolus -Freezeout 230 kV line outage dependingon the pre-outageflow conditions.
iii.Shirley Basin RAS to trip up to 60 MW of generationin the Shirley Basin area for the
Aeolus -Shirley Basin 230 kV line outage dependingon pre-outageflow conditions.
Figure 2:Aeolus West Vs TOT 4B Nomogram
Wyoming System Operating Curve
2022 Heavy Winter Loads
Normal Open Point:Plattell5 kV
900
800
700
600
500O
400
I-100
0
0 200 400 600 800 1000 1200 1400 1600 1800
Aeolus West Flow (MW)
Figure 2 depicts that the Aeolus West and TOT 4B path interaction is minimized with the
addition of the D.2 Project,as indicated by the steeper curve (implying little or no path
interaction)as compared to present TOT 4A/TOT 4B interaction.However,anytime the
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 17 of 21
emergency dynamic line rating on Platte -Standpipe is lower than 651 MVA16 the
nomogram in Figure 2 will be shifted to the left.Therefore,a new system operating limit
(SOL)value will be identified to represent the real time rating restriction to the path.
Additionally,the load at Platte substation can cause a shift in the nomogram;higher load at
Platte can shift the curve towards the right and lower load at Platte can shift the curve
towards the left,making it more conservative.This is due to the Platte -Latham 230 kV line
being the limiting element,as mentionedin Table5.
4.2 Base Case Development
The 2021-22 HW WECC case was modified to simultaneously stress the Aeolus West and
the TOT 4B path flows.The Aeolus West path was stressed using approximately2861 MW
of eastern Wyoming resource from a total of 3010 MW (existing and future)wind and net
coal resource.These resources were re-dispatched with Jim Bridger and Utah Valley
resources such that the Jim Bridger West flows were maintainedat 2400 MW.No additional
resources were imported from WAPA into PAC to stress the Aeolus West path.Since the
future resources in eastern Wyoming are in excess of future available transmission capacity,
Dave Johnston plant output was reduced in eastern Wyoming.The Shiprock,San Juan and
Gladstone phase shifters were locked to regulate flow across the TOT 3 path between
Colorado and Wyoming.
The TOT 4B path flows were adjusted between a minimum of 100 MW and a maximum of
857 MW.The Montana resources,up to 388 MW,were re-dispatchedwith WAPA (Dry
Fork)to reduce TOT 4B flow or re-dispatched with PAC resources to increase the TOT 4B
flow using Crossover,Rimrock and Steam Plant phase shifters in Montana.
4.3 Transient Stability Analysis
The stability analysis was performedusing GE provided model (GEO501)for repoweredand
new wind generation.The generic model for the Root Creek wind model was updated to
GEO501 (GE 1.85 units).Top of the World and Three Buttes were updated to GE 1.5 wind
turbine model provided by GE for PTI V33.The generic WECC models were used for the
Latham dynamic reactivedevice.
The transient stability study was performed for one (worst case)nomogram point of the
Aeolus West vs.the TOT 4B nomogram curve.The nomogram point with the heaviest
The highest loading on the Platte -Standpipe 230 kV line as per power flow analysis based on study
assumption.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 18 of 21
Aeolus West flow was considered for stability study analysis.Table 6 provides the
nomogrampoint description.
Table 6:Nomogram pointfor Dynamic Stability
Case TOT TOT 4B Platte -Limiting Element Outage
4A (MW)Latham
(MW)(MVA)
1 1696 103 546 Platte-Latham 230 kV line Anticline -Aeolus
500 kV line outage
with RAS
See Appendix D for dynamic stability plots
Transient stability was performed on selectivecritical outages based on anticipatedpost fault
impact on the wind generationperformance,especially for the portion of the system with a
calculated short circuit ratio of approximately 1.5.Below is the list of critical transmission
outages.
1.Point of Rocks -Latham 230 kV line outage for three phase fault at Latham 230 kV
bus (5 cycles)
2.Standpipe -Platte 230 kV line outage for three phase fault at Standpipe 230 kV bus
(5 cycles)
3.Platte -Latham 230 kV line outage for three phase fault at Platte 230 kV bus (5
cycles)
4.Dave Johnston -Casper 230 kV line outage for three phase fault at Dave Johnston
230 V bus (5 cycles)
5.Amasa -Difficulty 230 kV line outage for three phase fault at Amasa 230 kV bus
(5 cycles)
6.Dave Johnston -Amasa 230 kV line outage for three phase fault at Dave Johnston
230 kV bus (5 cycles)
7.Shirley Basin -Aeolus 230 kV line outage for three phase fault at Shirley Basin
230 kV bus (5 cycles)
8.Freezeout -Standpipe 230 kV line outage for three phase fault at Freezeout 230 kV
bus (5 cycles)
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 19 of 21
9.Aeolus -Freezeout 230 kV line outage for three phase fault at Aeolus 230 kV bus
(5 cycles)
10.Aeolus-Anticline 500 kV line outage for three phase fault at Aeolus 230 kV bus (4
cycle fault and 10 cycles for RAS operation)
11.Aeolus-Anticline 500 kV line outage for three phase fault at Anticline 345 kV bus
(4 cycle fault and 10 cycles for RAS operation)
12.Riverton -Wyopo 230 kV line outage for three phase fault at Riverton 230 kV bus
(5 cycles)
Observation 1:During the stability analysis it was identified that the Latham SVC model
tripped on high voltage for Platte -Standpipe 230 kV line outage.Following the fault,the
Latham SVC is radial from Point of Rocks substation,causing high voltage at Latham 230
kV bus and tripping the SVC model.This issue can be resolved with changing the SVC
operating parameter such that the SVC blocks VAR supply for voltage below a certain
voltage level.
Observation 2:Additionally the slowest voltage recovery following the fault clearing
occurs for a fault at either the Anticline or the Jim Bridger 345 kV bus followed by the
loss of the new Aeolus -Anticline/Jim Bridger segment and operation of the Aeolus
RAS to drop generation,causing the largest angular separationbetween Jim Bridger and
Dave Johnston.For local fault conditions,the GE wind turbine models ramp down
momentarily,whereas the models do not ramp for remote faults.
Due to the fault being on the remote end (at Anticline or Jim Bridger)of the new Aeolus
-Bridger line segment,which is isolated from the wind farms,the voltage depression
seen by the wind generating units (modelled as current source)are not as low,the power
output is much higher during the fault and power output recovery is much faster after the
fault as compared to the fault close to Aeolus.The remote fault results in more stress on
the system during the fault and post fault,which leads to slower voltage recovery.The
synchronous machines (modelled as voltage source)at Dave Johnston and Jim Bridger
(one unit offline in the stress base case)try to recover the system voltage,which leads to
higher angular separation between the two buses.Thus,the loss of the Aeolus -
Anticline/Jim Bridger segment with a remote fault is the most severe.
This issue can be mitigated by effectively sizing dynamic reactive device at Latham to
boost the system voltage.This disturbance did not result in system instability or system
separation.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 20 of 21
Additionally,the stability analysis demonstrated that all planning events met stability
performance criteria.
5 SensitivityAnalysis
A.A sensitivity study was performed to replace the SVC dynamic device model at
Latham with a generic STATCOM model.The dynamic simulations were
performed for a stressed base case and the STATCOM model displayed behavior
similar to the SVC model.High post fault voltage conditions require model data
adjustments to prevent SVC and STATCOM model blocking and tripping.
B.A sensitivity analysis was performed to evaluate the system impacts of increasing
the magnitude and changing the location of generation resources identified in the
Assumed Generation Projects in Table 4.As part of this analysis,assumed wind
generation was increased from 1169 MW to 1270 MW,by increasing the
repowered generation by 137.5 MW and adding 240 MW of new generation in
the Bighorn area of northern Wyoming,and reducing the new wind generation at
Shirley Basin from 500 MW to 250 MW.(Other generation adjustments were
made for loads and resource balancing.)Due to reduced generation in southeast
Wyoming,Aeolus West transfer capability limit increased to 1790 MW.The
limiting element was the Platte -Latham 230 kV line emergency thermal rating
following outage of the Bridger/Anticline -Aeolus facilities and initiation of
associated generating tripping.
The study also identified two different RAS schemes to trip generation for N-1
outage:
i.Aeolus RAS to trip up to 640 MW of wind generation depending on pre
outage flow conditions for any of the new transmission element outage
betweenAeolus -Anticline/JimBridger segment.
ii.Freezeout RAS to trip up to 190 MW of generation in Freezeout area for
Aeolus -Freezeout 230 kV line outage depending on pre outage flow
conditions.
There were no additional system improvement requirements identified.
Monsanto Exhibit No.207
Case No.PAC-E-17-07
Page 21 of 21
6 Study Conclusions
Technical studies demonstrated that with the addition of the planned D.2 Project
facilities to the Wyoming transmission system,system performance will meet all NERC
and WECC performance criteria.
Preliminary power flow studies demonstrate that by utilizing existing and planned
southeast Wyoming resources4,the Aeolus West transmission path can transfer up to
1696 MW under simultaneous transfer conditions with the TOT 4B transmission path,
effectively"increasing the east to west transfer levels across Wyoming by 817.5 MW.
Power flow findings also indicated:
Dynamic voltage control is necessary at the Latham 230 kV substation to
mitigate low voltage conditions resulting from loss of Bridger/Anticline-Aeolus
transmission facilities.
Under certain operating conditions,three different Remedial Action Schemes
(RAS)will need to be implemented to trip generation following outage of
specific transmission facilities.
The location (and output level)of new and repowered wind resources can
influence the transfer capabilitylevel across the Aeolus West transmission path.
While a wide range of disturbances were evaluated,dynamic stability studies identified
that the slowest post fault voltage recovery will occur for a fault at Anticline or Jim
Bridger 345 kV bus followed by loss of the Bridger/Anticline -Aeolus transmission
segment and the planned operation of a generation tripping (RAS)scheme.The stability
analysis demonstrated that all planned system events met the stability performance
criteria.
Monsanto Exhibit No.208
Case No.PAC-E-17-07
20000-520-EA-17/Rocky Mountain Power Page 1 of i
October 13,2017
WIEC Data Request 7.3
WIEC Data Request 7.3
Please identify all contingency amounts that RMP has included in its cost estimates for its
proposed transmission line project in this proceeding and identify the specific contingency
being addressedby each contingency amount.
Response to WIEC Data Request 7.3
In developingthe transmission project estimate the Company has presented the estimate
as a +/-15 percent accuracy given the early nature of the estimate and finalization of the
scope and approach.The estimate values used historical pricing from previous projects
(inflation adjusted as necessary),the historical pricing units were from engineer,procure
and construct (EPC)contracts and contained contractor contingencies representing such
risks as soils,production rates,weather,environmental constraints and the like.In
addition the Company prepared a risk evaluation to determine potential cost and/or
schedule risks,the values determined from this process identified that the risk profile was
within the overall accuracy of the project cost estimate.
Respondent:Todd Jensen /Stuart Smith
Witness:Rick Vail