20070705IPC to Staff 1-14.pdf

Barton L. Kline (ISB No. 1526)
Lisa D. Nordstrom (ISB No. 5733)
IDAHO POWER COMPANY
1221 West Idaho Street
O. Box 70
Boise, 1083707
Tel: [phone]
Fax: [phone]
" ,!: .: ~, ,, '" , ,:,;, , ,
Attorneys for Idaho Power Company
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
CASSIA GULCH WIND PARK LLC AND
CASSIA WIND FARM LLC Case No. IPC-06-
Complainants IDAHO POWER'S RESPONSE TO
THE FIRST PRODUCTION
REQUEST OF THE COMMISSION
STAFFIDAHO POWER COMPANY
Respondent
COMES NOW , Idaho Power Company ("Idaho Power" or "the Company ) and, in
response to the First Production Request of the Commission Staff to Idaho Power
Company dated June 19, 2007, herewith submits the following information:
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page
REQUEST FOR PRODUCTION NO.What is the significance of
interconnection requests submitted during the period January 1 , 2005 through June 29
2006 as discussed in Section 4 on page 3 of the Settlement Stipulation? How does
Idaho Power propose to handle interconnection requests made after the period listed
above?
RESPONSE TO REQUEST FOR PRODUCTION NO.
Idaho Power received in excess of 390 MW of generation interconnection
requests for locations in the Magic Valley throughout the 2005 calendar year. Idaho
Power was aware that transmission constraints in the 230 and 138 kV transmission
system west of Midpoint Substation would not be able to accommodate all of the
requested capacity. It was determined that a single system impact study demonstrating
the total capability of the transmission system would be more efficient than performing
studies for each project. This system impact report was finalized on June 8, 2006 and
demonstrated that 305 MW could accommodated with transmission network
improvements. Idaho Power selected the cluster study window end date of June 29,
2006 based on the 390 MW of interconnection requests coupled with the study capacity
of 305 MW. It is not intended to exclude other interconnection requests that would have
an impact on the computation of costs and construction of facilities associated with the
Twin Falls "cluster . Idaho Power proposes to handle interconnection requests within
the "cluster" made after the June 29, 2006 date in the same manner as those projects
falling within the above-referenced timeframe.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 2
The response to this request was prepared by David Angell , Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline , Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 3
REQUEST FOR PRODUCTION NO.Please provide a map showing Idaho
Power s transmission system in the Magic Valley area, the capacity ratings and voltage
of each transmission line , the locations of each project requesting transmission service
locations of relevant substations , and the proposed point of interconnection for each
project. Please designate on the map the geographic boundaries for which future
projects will require transmission upgrades and may be subject to similar redispatch
requirements.
RESPONSE TO REQUEST FOR PRODUCTION NO.
To avoid the significant adverse results arising out of the public disclosure
requirements of FERC's Standards of Conduct and the Critical Infrastructure Protection
Standards , promulgated by NERC, Staff has agreed to withdraw this request and obtain
the requested information by way of Staff's statutory audit authority.
The response to this request was prepared by Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 4
REQUEST FOR PRODUCTION NO.Please provide a copy of the Generation
Interconnection System Impact Study referred to in Section 5 of page 3 of the
Settlement Stipulation.
RESPONSE TO REQUEST FOR PRODUCTION NO.
The generation system impact study named "Up to 305 MW of New Generation
on the 138 kV Transmission System in the Twin Falls Area" is enclosed.
The response to this request was prepared by David Angell, Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
ST AFF, Page 5
REQUEST FOR PRODUCTION NO.Please provide a copy of the
Redispatch Study" referred to in Section 5 of page 3 of the Settlement Stipulation.
RESPONSE TO REQUEST FOR PRODUCTION NO.
The generation impact study report named "Up to 330 MW of New Generation on
the 138 kV Transmission System in the Twin Falls Area" is enclosed.
The response to this request was prepared by David Angell , Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 6
REQUEST FOR PRODUCTION NO.: Will it be necessary for all projects in the
queue to agree to be subject to redispatch? If not, what cost would be assessed
projects that decline to be subject to redispatch , assuming Idaho Power makes
transmission upgrades only sufficient to accommodate all projects in the queue if all
projects are subject to redispatch? Please provide an example similar to the format
used in Exhibit B showing capacity and cost allocations if some projects agree to
redispatch and others do not.
RESPONSE TO REQUEST FOR PRODUCTION NO.
, Idaho Power will not require all projects in the generation interconnection
queue or the cluster group to be subject to "Cassia Redispatch." In order to provide an
example of project cost allocation for the scenario of some projects committing to
Cassia Redispatch while others do not, the transmission network upgrades identified in
both system impact studies will be combined as shown in Table 1. The allocation of
project capacity to the network upgrade phases for projects 114 through 136 committing
to Cassia Redispatch , while 154 through 170 do not, is shown in Table 2 and the
allocation of project cost per phase is shown in Table 3.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 7
Table 1: Transmission upgrade projects with only a portion of projects committing to
Cassia Redispatch
Total
CapacityPhase Available (MW)
Phase
Capacity
MW added CostProject
Upper Salmon Series Reactor 290,000
Lucky Peak Series Reactor 290 000
Lower Malad Series Reactor 153 290,000
Midpoint 1/3 Series Capacitor Bypass 156 100,000
King 230/138 Transformer 235 $ 10,320,000
Reconductor Midpoint Dram 230 kV line 305 170 $ 47 525 000
Total $ 58 815 000
Table 2: Project capacity allocation by network upgrade phase with projects 114 to 136
committing to Cassia Redispatch and 154 to 170 do not , allocation assumingII . tproJec s comp e e cons ruc Ion
Project No.Capacity Phase I Phase 2 Phase 3 Phase 4 Phase 5 Phase 6 Total
114
116 10.10.
117 101.21.10.
128 10.10.101.
134 18.18.10.
135 18.
136
154
155 11.11.
157 11.
158
159
170
Totals 304.79.4 68.304.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 8
Table 3: Project cost allocation by network upgrade phase with projects 114 to 136
committing to Cassia Redispatch and 154 to 170 do not, allocation assuming
projects complete construction
Project
No.Capacity Phase I Phase 2 Phase 3 Phase 4 Phase 5 Phase 6 Total
114
116 10.
117 101.$290,000 $137 627 427 627
128 10.$ 51 610 610
134 18.$ 92 898 898
135 $ 7 864 $ 100,000 $ 2 001 612 $ 2 109,476
136 $ 8,318,388 $ 8,318,388
154 $ 1 586,006 $ 1 586 006
155 11.$ 8,012 776 $ 8,012 776
157 $12,412 217 $12,412 217
158 $12,412 217 $12,412 217
159 $12,412 217 $12 412 217
170 689,568 689,568
Totals 304.$290 000 $290 000 $ 100,000 $10 320,000 $47 525 000 $58,525,000
The response to this request was prepared by David Angell, Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline , Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
ST AFF, Page 9
REQUEST FOR PRODUCTION NO.Please discuss how the proposed
resdispatch differs from the remedial action schemes discussed earlier in the
negotiations. Why is Idaho Power willing to now consider redispatch when it appeared
earlier in the negotiations to insist that a remedial action scheme was only a temporary
solution?
RESPONSE TO REQUEST FOR PRODUCTION NO.
The Cassia Redispatch aligns the cluster projects with other network generation
that are capable of being dispatched by Idaho Power transmission grid operations. The
grid operations personnel direct network generation to increase or decrease output in
response to transmission system outages to reduce transmission line overloads. This
ability to control the output of generators differs from a remedial action scheme in that it
relies on the Idaho Power transmission system operator to determine when and how
much "Cassia Redispatch" is required to reduce transmission line overloads.
Idaho Power has built its transmission system such that no transmission
overloads occur for the outage of a single transmission element (N-1).This
performance is required by the North American Energy Reliability Corporation (NERC).
Remedial action schemes are generally deployed for multiple element outages or where
fast action is required to maintain system voltage or stability. A remedial action scheme
employs sensors at substations that detect abnormal conditions, such as line or
equipment outages , and respond with predetermined actions, such as generation
tripping. Remedial actions schemes typically detect outages and initiate the remedial
action in the order of tenths of a second in order to maintain the transmission system
integrity. The transmission system overloads identified in the system impact studies
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 10
require action within thirty minutes which is sufficient time for the transmission system
operator to respond with appropriate generation dispatch.
The response to this request was prepared by David Angell , Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 11
REQUEST FOR PRODUCTION NO.Please describe the circumstances
under which redispatch would occur.Please provide an estimate of the timing,
magnitude, and frequency of when redispatCnls expec d to occur In fFi uture.
RESPONSE TO REQUEST FOR PRODUCTION NO.
The Cassia Redispatch will occur when an outage occurs on a transmission
element listed in Exhibit C to the Settlement Stipulation coincident with high cluster
group generation and high transmission flows across the west-of-Midpoint transmission
system.Idaho Power is restricted by FERC Standards of Conduct from providing
estimates of future transmission utilization , however, we are able to average outage and
outage duration by transmission class (from years 2002 through 2006), shown in Table
, and past ten year outage performance of the transmission lines listed in Exhibit C to
the Settlement Stipulation , as shown in the Table 5 below.
Transmission Line Class
~ --,. -
138-161 kV
230kV
Table 4: Years 2002 to 2006 av~rClg~tr?nsmissionline outagehi~tory
! Ave. Outage Duration
i Av..~~ 9.~!~-
g~~"
p.~r~,t~~E - i__J?~r ,!, ~~!.J~J_r:'ute!;t19 274
1 .17 1389
Table 5: Ten year average transmission line outage history for lines initiating
Cassia Redispatctl-
Transmission Line
---.._-,-, , - - ,- ~(?!~~..
~e."rl~tl~..~i5:ip..~irlt :f!_
?",_?--
?Q~,!_.._-
",,--,, ..".. "---"--"-"---"""""--"'",,_.........._..----
, Boise Ben~t1:~Jgp.9lQt:f!~"~9.kV
----,, ", -,,-,,--'.._- "
Boise Bench-Rattlesnake 230kV
,,------- - - ---- ..--
Danskin-Elmore-Mountain Home Junction 1 138KV
--"---"-"..,---,,..-....,,..-..--..
DRAM~"iqpC?.irl!--??9.~'!--_..
..,,.. ..,-
Lower Malad Power Plant-Mountain Home Junction 1 138kV
---
.. fy'!idp()irlt-R?ttlesnake 230kV
LJPp~r --SalrT1()rlJcSc.2-Mountain Home Junction 1 138kV
Ave. Out~--
g~--
s perYear
"W_---
""'--,--",, - ,..-..,------ ,., -"
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 12
The response to this request was prepared by David Angell , Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 13
REQUEST FOR PRODUCTION NO.Please explain the rationale for Section
, Part C of the Settlement Stipulation. Does Idaho Power anticipate making a request
for the Commission to authorize it to construct alternative transmission facilities that
would eliminate or reduce the costs of Network Upgrades?
RESPONSE TO REQUEST FOR PRODUCTION NO.
Idaho Power has no current plans to request authorization from the Commission
to construct alternative transmission facilities that would eliminate or reduce the cost of
the network upgrades specified in Tables B-1 and 8-4 of Exhibit 8 to the Stipulation.
However, as the Commission is well aware, Idaho Power is experiencing rapid
customer and load growth and transmission planning must remain flexible. All of the
network upgrade facilities described in Tables B-1 and B-4 of Exhibit 8 to the Stipulation
are facilities that would not have been constructed but for the interconnection of the QF
facilities. The cited provision acknowledges that if that situation changes in the near
term, a revised cost allocation allocator could be presented to the Commission for its
review and approval.
The response to this request was prepared by David Angell, Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline , Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 14
REQUEST FOR PRODUCTION NO.: What is the basis for requiring a 50%
mechanical availability guarantee in Section 14 of the Settlement Stipulation , rather than
some higher percentage such as the 85% that is being proposed in Case No. IPC-07-
04?
RESPONSE TO REQUEST FOR PRODUCTION NO.
The fifty percent (50%) amount is the product of the settlement negotiations.
Because the Cassia Projects and the vast majority of other QF projects included in
Table B-2 of Exhibit B to the Stipulation are "grandfathered", they currently have no
mechanical availability guarantee in their Firm Energy Sales Agreement , but are subject
to the 90%/110% performance band requirement. If the Commission agrees that the
cost sharing and other protocols in the Stipulation should be used as a template for
future QF interconnections where network upgrades are required , and if the
Commission eliminates the 90%/110% performance band in the IPC-07-4 case , Idaho
Power believes that it would be reasonable for future QF contracts to include a higher
percentage mechanical availability guarantee to qualify for transmission refunds.
The response to this request was prepared by Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 15
REQUEST FOR PRODUCTION NO.1 0:How is Idaho Power proposing to
determine mechanical availability in hours when there is little or no wind? How will
Idaho Power determine the capacity available to generate in each hour when the wind is
blowing? Please provide numerical examples to illustrate your answers.
RESPONSE TO REQUEST FOR PRODUCTION NO. 10:
Idaho Power proposes to determine mechanical availability by utilizing a self-
certification system in which the QF developer certifies the percentage of time the
facility was mechanically available and provides records for wind speed , forced outages
and generation at the individual QF site to verify the mechanical availability of the
project on a monthly basis. QFs currently report the nature and duration of forced
outages and routine maintenance. The Interconnection Agreement would also include
provisions that would give Idaho Power the right to audit the books and records of the
QF if a question arises as to the accuracy of the QF'sself-certification and the data
provided by the QF to support its self-certification.
The response to this request was prepared by David Angell, Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 16
REQUEST FOR PRODUCTION NO. 11:Please explain why Idaho Power
believes it is appropriate to pay full , published avoided cost rates for power received for
projects subject to redispatch. If redispatch is necessary at a time when Idaho Power is
unable to meet load using its own resources and must make off-system purchases at
costs above avoided cost rates , does Idaho Power believe that it should pay those
higher costs and impose no penalty on the projects being redispatched?
RESPONSE TO REQUEST FOR PRODUCTION NO. 11:
First it must be recognized that the Company currently pays full , published
avoided cost rates (based on the cost of a dispatchable CCCT) for power received from
QF projects even though the QF projects are not dispatchable like the proxy CCCT.
This is particularly true for wind generation projects.
Second, current pro forma Firm Energy Sales Agreements contain provisions
allowing interruptions of energy delivery and purchase for line maintenance and under
emergency conditions on Idaho Power s transmission and distribution system. Under
the redispatch protocol that will be mandated in amended QF agreements, QF project
generation will be limited to a nont-to-exceed set-point if conditions occur on Idaho
Power s system that could result in damage to the system and/or degraded service to
customers. However, under current QF contracts, there is no obligation on the part of
the QF to install equipment and facilities that will allow Idaho Power to limit the
generation from the QF project. Currently, all Idaho Power can do if a transmission
system emergency occurs is to totally disconnect the QF generation from the system.
As a result, the ability to set a not-to-exceed generation limit is an incremental
improvement over the current system when transmission overloading occurs. With
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 17
redispatch , the Company may still be able to keep a portion of the QF project
generation available to carry load. As a result, while the vast majority of QF projects are
not dispatchable and do not provide firm energy as that term is defined by utilities
during adverse transmission events the energy from QF projects with "not-to-exceed
dispatch" capability are somewhat "firmer" than older QF projects.
Finally, Idaho Power acknowledges that paying full avoided costs for power
received from QF projects that are subject to redispatch will result in higher costs to
customers when compared to a requirement that 100% of the cost of the transmission
upgrades be funded by the QF projects to avoid the need for redispatch.
Counterbalanced against the potentially higher costs to customers is the reality that if
100% of transmission upgrade costs are allocated to the QF developers , it is likely that
the QF projects will not be economically viable. Use of the redispatch protocol as
proposed in the Stipulation substantially reduces the cost of transmission upgrades and
will certainly improve the economics of most QF wind projects.
At the same time , the fact that the Stipulation requires QF developers to (1)
provide a significant portion of the network upgrade costs as a nonrefundable
contribution and (2) advance half of the cost of the network upgrade subject to refund
will provide a strong locational price signal to QF developers and incent them to make
economically rational decisions as to where they site QF projects. While the settlement
agreement memorialized in the Stipulation may not achieve full customer cost neutrality,
it does mitigate the cost impact on customers and provides an opportunity for small QF
developers to move forward with renewable resource projects. Development of these
renewable resource projects may allow the Company to avoid or defer future , potentially
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 18
more expensive intermittent resource projects identified in the Company s Integrated
Resource Plan.
For all of these reasons Idaho Power believes that the compromise worked out
and memorialized in the Stipulation provides a balanced approach that is fair to
customers and is consistent with a public policy to encourage the development of
renewable resources in the State of Idaho.
The response to this request was prepared by Barton L. Kline, Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 19
REQUEST FOR PRODUCTION NO. 12 Please explain in detail what criteria
have been used in determining the available transmission capacity for each phase
under the redispatch scenario , as opposed to the available transmission capacity under
no redispatch. Please cite and provide a copy of any reliability criteria used as a basis
for determining capacity under the redispatch scenario.
RESPONSE TO REQUEST FOR PRODUCTION NO. 12:
The studies for both the no-dispatch and Cassia Redispatch were evaluated for
the transmission system performance under a single element outage (N-1) conditions.
The difference in the studies was the allowable transmission system overload. The no-
dispatch generation was evaluated at equipment continuous thermal ratings and Cassia
Redispatch generation was evaluated at equipment 30-minute emergency ratings
115% of continuous thermal ratings. During both studies, the phased transmission
system improvements were added to the power flow case and the generation
representing the cluster projects was increased until any transmission element current
reached 100% (115% for Cassia Redispatch) of the elements continuous thermal rating.
The below criteria is an excerpt from the Appendix A of the "Up to 330 MW of
New Generation on the 138 kV Transmission System in the Twin Falls Area.
The following acceptability criteria were used in the power flow analysis to
determine the acceptability of the alternatives:
Loadings on transmission lines and transformers should not
exceed 115% of the continuous rating, immediately following
any N-1 outage. Loading on the Midpoint 230 kV series
capacitors should not exceed 135% of the continuous rating,
immediately following any N-1 outage. These loadings
levels of 115% on transmission lines and transformers and
135% on Midpoint series capacitors correspond to IPC's 30
minute emergency equipment ratings. Any loadings
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 20
immediately following an N-1 outage , less than the
minute emergency rating is acceptable.
Loadings which are less than the 30 minute emergency
equipment ratings but greater than the equipment
continuous ratings, must be reduced to the continuous
ratings by generation curtailments, re-dispatch , or someother operating procedure. Any remedial action
schemes(RAS) or other transmission switching, must be
judged to be reasonable before the alternatives performance
can be deemed acceptable.
The continuous rating of equipment is assumed to be the
normal thermal rating of the equipment. This rating will be
as determined by the manufacturer of the equipment or as
determined by Idaho Power. Less than or equal to 100% of
continuous rating for transmission lines and transformers is
acceptable. Less than or equal to 110% of continuous rating
for the Midpoint 230 kV series capacitors is acceptable.
Transmission voltages, under normal operating conditions
are maintained within plus or minus 5% (0.05 per unit) of
nominal. Therefore, voltages greater than or equal to 0.
pu voltage and less than or equal to 1 .05 pu voltage are
acceptable.
The stable operation of the transmission system requires an
adequate supply of volt-amperes reactive (VARs) to maintain
a stable voltage profile under both steady-state and dynamic
system conditions. An inadequate supply of V ARs will result
in voltage decay or even collapse under the worst
conditions. Idaho Power designs its system to integrate
Network Resources at full capability during specified outage
conditions.
The response to this request was prepared by David Angell, Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline , Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 21
REQUEST FOR PRODUCTION NO. 13 What level of subscription would be
required before Idaho Power would proceed with a phase of transmission upgrade? For
example, referencing table B-6 of Exhibit B , would all projects 135-170 have to commit
before Phase 5 would be initiated? If projects 235 and 136 committed, but projects 154-
170 did not, for example , would Idaho Power initiate Phase 5 and allocate all of the
costs for Phase 5 to projects 135 and 136?
RESPONSE TO REQUEST FOR PRODUCTION NO. 13:
Idaho Power has determined that any project of a size greater than allowed in
Schedule 84 may be subject to transmission network upgrades. Therefore , the level of
subscription that would require Idaho Power to proceed with a transmission upgrade
phase is any project capacity greater than 100 kW that is not supported in a prior phase.
Only one project, not all , in a phase would have to commit to construction before Idaho
Power would commence constructing that phase.If a single project requires a
transmission upgrade phase , then that phase cost will be solely allocated to that project.
Of course , that broad rule would have to be applied realistically. A 1 MW or 2
MW project , by itself, would not necessarily trigger the need to install a $10 million
transformer adding 174 MW of capacity. In that unique situation , other measures would
be considered to address system reliability issues.
The response to this request was prepared by David Angell, Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline , Senior Attorney,
Idaho Power Company.
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 22
REQUEST FOR PRODUCTION NO. 14 If a lower project in the queue is ready
to proceed to construction much sooner than higher projects in the queue , how will its
share of costs be allocated? For example, referring to Table B-6 of Exhibit B, what
costs would be allocated to project number 170 if it was ready to proceed with
construction and none of the other projects in Phase 5 were ready to proceed?
RESPONSE TO REQUEST FOR PRODUCTION NO. 14:
Idaho Power has required all projects in the cluster group to provide network
transmission facility study deposits in order to maintain queue position. Idaho Power
will require each project to commit to their allocated phase costs at a date following a
Commission order on this Settlement Stipulation. The phase cost allocation will be
adjusted at that time based on the commitment of the projects.Projects that
interconnect after this cluster group will be subject to the terms of this settlement
stipulation.
In response to the hypothetical posed in this request, referring to Table B-6 of
Exhibit B , if project number 170 proceeds to construction prior to the other projects in
Phase 5, project 170 would be required to provide seventy-five percent (75%) of
$68 300. Fifty percent (50%) of that amount would be subject to refund. Project 170
would also be required to post liquid security in an amount sufficient to cover the cost
Idaho Power would reasonably incur if the remaining projects in Phase 5 decided not to
proceed.Realistically, if only project 170 decided to proceed it would not be
reasonable to expect a 1 MW project to trigger the installation of the King 230/138
transformer adding 174 MW of capacity at a total cost of more that $10 million. A more
realistic scenario would be for projects 157, 158 and 159 to proceed ahead of projects
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 23
136, 154 and 155. Projects 157-159 would be required to pay 75% of the approximately
$4 million associated with their share of Phase 5 and to post liquid security for $6 million
or the remaining portion of the full , approximately $10 million amount. As the other
projects in Phase 5 completed construction, the level of projects 157-159'liquid
security amount would be reduced proportionately.
The response to this request was prepared by David Angell , Manager, Delivery
Planning, Idaho Power Company, in consultation with Barton L. Kline, Senior Attorney,
Idaho Power Company.
DATED at Boise, Idaho , this day of July, 2007.
BARTON L. KLINE
Attorney for Idaho Power Company
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 24
CERTIFICATE OF SERVICE
I HEREBY CERTIFY that on this day of July, 2007, I served a true and
correct copy of the within and foregoing document upon the following named parties by
the method indicated below, and addressed to the following:
Commission Staff
Donovan Walker
Deputy Attorney General
Idaho Public Utilities Commission
472 W. Washington (83702)
O. Box 83720
Boise, Idaho 83720-0074
-X- Hand Delivered
- U.S. Mail
Overnight Mail
FAX
Email Donovan.walker(g) puc.idaho.qov
Industrial Customers of Idaho Power
Peter J. Richardson , Esq.
Richardson & 0' Leary
515 N. 2ih Street
O. Box 7218
Boise, Idaho 83702
Hand Delivered
--.2LU.S. Mail
Overnight Mail
FAX..x Email peter(g) richardsonandolearv.com
Don Reading
Ben Johnson Associates
6070 Hill Road
Boise, Idaho 83702
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Overnight Mail
FAX..x Email dreadinq (g) mindsprinq.com
R. Blair Strong
Paine Hamblen et al
717 W. Sprague Ave.
Spokane , VVA 99201
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FAX..x Email blair.stronq (g) painehamblen.com
David J. Meyer
Senior Vice President
Avista utilities
O. Box 3727
Spokane , VVA 83702
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FAX..x Email dmever(g)avistacom.com
Ronald K. Arrington
Assoc. Chief Counsel
John Deere Credit
6400 NW 86th Street
Johnston , IA 50131
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FAX
Email arrinqtonronaldk(g) iohndeere.com
IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF , Page 25
Brian Dickman
Dean S. Brockbank
Rocky Mountain Power
201 S. Main Street, Suite 2300
Salt Lake City, UT 84111
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Overnight Mail
FAX
Email brian.dickman (Q) pacificorp.com
dean. brockban k (Q) pacificorp. com
Lawrence R. Lieb
Exergy Development Group of
Idaho LLC
910 W. Main Street, Suite 310
Boise, Idaho 83702
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IDAHO POWER'S RESPONSE TO THE FIRST PRODUCTION REQUEST OF THE COMMISSION
STAFF, Page 26
BEFORE THE
IDAHO PUBLIC UTiliTIES COMMISSION
CASE NO. IPC-O7-
IDAHO POWER COMPANY
Response to Staff Request No.
GENERA TOR INTERCONNECTION
SYSTEM IMP ACT STUDY REPORT
for
Up to 305 MW of New Generation
On the 138 kV Transmission System
In the Twin Falls Area
IDAHO POWER COMPANY, Transmission Provider
TRANSMISSION SYSTEM
FINAL REPORT
June 8, 2006
1.0 Introduction
Multiple new generation projects have contacted Idaho Power Company (IPe) to perfonn
Generator Interconnection System Impact Studies for Network Resource Interconnection
Service at 138 kV for the integration of new generation projects in the Twin Falls area
This report documents the basis for and the results of this System Impact Study. It describes
the backbone transmission system improvements required for Network Resource
Interconnection Service of the new generation proposed, the study cases used, outage scenarios
assumed and results of all work in the areas of concern.
Summary
The perfonnance of the backbone transmission system was evaluated to integrate up to 200
MW of new generation on the 138 kV transmission system in the Twin Falls area. Four phases
of transmission system improvements are required to provide 200 MW of new generation
Network Resource Interconnection Service.
Phase #1:
Phase #2:
Phase #3:
Phase #4:
Install a 19 ohm 138 kV Series Reactor on the Upper Salmon-Mountain Home
Junction 138 kV transmission line. Without this improvement, the outage of
the Midpoint-Rattlesnake #2 230 kV transmission line results in an overload
of the Upper Salmon-Mountain Home Junction 138 kV line with no new
generation in the Twin Falls area. This improvement is necessitated by the
transmission improvements associated with Generation Project 88 , and as a
result should be funded by Idaho Power Company - Delivery. This phase of
improvements is estimated at approximately $290 000.
Install a 10.5 ohm 138 kV Series Reactor on the Lower Malad-Mountain
Home Junction 138 kV transmission line. Without this improvement, the
outage of the Midpoint-Rattlesnake #2 230 kV transmission line results in an
overload of the Lower Malad-Mountain Home Junction 138 kV line with new
generation levels greater than 7 MW in the Twin Falls area. This phase
improvements is estimated at approximately $290 000.
Fold the Midpoint-DRAM #1 230 kV transmission line into the King
Substation and install a 230/138 kV 300 MV A transfonner. Without this
improvement, the outage of the Midpoint-Rattlesnake #2230 kV transmission
line results in an overload of the Upper Salmon-Mountain Home Junction 138
kV line with new generation levels greater than 60 MW in the Twin Falls
area. This phase of improvements is estimated at $10 320 000.
Reconductor/rebuild the King-DRAM #1 230 kV transmission line with a two
conductor bundle of 795 MCM ACSR "Tern" conductor. This rebuilt line
also must be folded into the Rattlesnake Substation north of Mountain Home.
In addition, transmission modifications are required at the DRAM end of the
line. Without this improvement, the outage of the Midpoint-Rattlesnake #2
230 kV transmission line results in an overload of the Upper Salmon-
Mountain Home Junction 138 kV line with new generation levels greater than
135 MW in the Twin Falls area. This phase of improvements is estimated at
$47 525 000.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). The proposed
cost allocation is subject to change, as more information is known. These are cost estimates
only and final charges to the customer will be based on the actual construction costs incurred.
Summary of Interconnection Requests
Requests were made to Idaho Power Co. by multiple generation projects in the Twin Falls area
to study the interconnection of the proposed generation projects to Idaho Power s transmission
system at the 138 kV level for Network Resource Interconnection Service.
Scope of Interconnection System Impact Study
The Interconnection System Impact Study was done and prepared in accordance with the
FERC Order 2003-, Standard Large Generator Interconnection Procedures, to provide a
preliminary evaluation of the System Impact of the interconnection of the proposed large
generating project to the Idaho Power transmission system. This study will only be concerned
with the capabilities of the Idaho Power system to manage this new resource within the study
area of the proposed interconnection.
Description of Existing Transmission Facilities
As shown in Figure 1 of Section 7., Midpoint Substation, north of Twin Falls, has three 230 kV
lines that carry bulk power westward to the Boise area. Midpoint-DRAM #1 line utilizes single
715.5 MCM conductor and has a continuous rating of339 MV A. The Midpoint-Rattlesnake-Boise
Bench #2 line utilizes a 2 conductor bundle of715.5 MCM. This line has a continuous rating of
677 MV A. The Midpoint-Boise Bench #3 line has similar conductors and the same rating as the
Rattlesnake-Boise Bench #2 line. In the Mountain Home area, an additional 230 kV line is
planned to carry bulk power westward. The Rattlesnake-Bennett Mountain-Danskin-Mora line
utilizes single 1272 MCM conductors(478 MV A) from Rattlesnake-Bennet Mountain, single 1590
MCM conductors(550 MV A) from Bennet Mountain-Danskin, and a two conductor bundle of795
MCM(700 MV A) from Danskin-Mora. The Bennett Mountain-Danskin-Mora transmission lines
are required for the interconnection of Generation Project 88 ; scheduled to be in-service Spring of
2008.
In addition to the Midpoint to the Boise area 230 kV lines previously mentioned, there are two
138 kV circuits which can carry power from the Twin Falls area to the Mountain Home area.
They are:
King-Lower Malad-Mountain Home Junction 138 kV Line
King-Upper Salmon-Mountain Home Junction 138 kV Line
Generators located in the Twin Falls area which are intended to serve load growth in the Treasure
Valley area, will be adding new incremental flows on top of existing committed east-to-west
transactions across the Midpoint West transmission cutplane. This System Impact study will
model approximately 1100 MW of transfers across the Midpoint West cutplane, prior to this
proposed generator addition. For these studies, the flow level of the Midpoint west cutplane is
defined as the sum of the flows on the following lines:
. Midpoint-DRAM #1 230 kV line
. Midpoint-Rattlesnake #2230 kV Line
. Midpoint-Boise Bench #3 230 kV Line
Lower Malad-Mountain Home Junction 138 kV Line
Upper Salmon-Mountain Home Junction 138 kV Line
Description of Configurations Studied
Since the most limiting operating conditions are expected during heavy production on the
upper and middle Snake and Boise River hydro plants, with heavy east-west transfers across
the Idaho Power transmission system, the injection of the new generation at King 138 kV bus
was inserted into a power flow case that would simulate committed (approximately 1100 MW)
pre-contingency flows on the Midpoint West transmission path.
Post-transient Study Results
This Interconnection System Impact Study Report is for Network Resource Interconnection
Service at 138 kV, for numerous proposed generation additions in the Twin Falls area. System
transfers across the Midpoint West cutplane are modeled at approximately 1100 MW prior to
the proposed transmission improvements or the proposed generators producing any power.
Hydro generation production for the Boise & Snake plants, were modeled at heavy, but
realistic levels. Ouput levels for the existing peakers at Danskin and Bennett Mountain were
varied over their operating ranges as appropriate. N-O and N-l outage performance for the
existing system are recorded. Generation levels at King 138 kV bus are increased until system
thermal limits are reached during N-l outages. The most effective and cost-efficient
transmission system improvements are then added to the model and King generation is then
increased until system thermal limits are reached during N-l outages.
Existin2 System
The following one line diagram depicts the existing system with no outages.
~!EBCHI- "
RlLSNK3" 'TISNX3E d.ointWest = 1111 A ~
, ,
"'A I
-=-_
T:fI-?'
------.:::~
---- ~A
"\~~"
'I .'0"'""
' O~m'"
--------
::1:
"""
.'000'"':CRON ,.. ~(II A " 0,A ~ "
" '
\1~,.(g:;;,
,,!N A E~~ A ." "'PJ\~'
~(
~A,
- ~ ;~~~;~~:;:-
"'A ~.,
~~=M "M 1-""
"\81""' WO(Y PI( '
~ ./
,- At~~~""~"'A
~~ --:ii .. "'A
"'A A~ "'A
"""'"
'"""'AU. 'm"',.
" '
~1~M;-;'~!~M
Existing System - No Outages
Figure 1
Existine System N-l Outaees
The following one line diagram depicts the existing system with no new generation in the Twin
Falls area, and the only N-I outage between Midpoint and the Mountain Home area that results
in loadings above continuous thennal ratings.
'?11~CH
MOM
,., ,
~ f
""",...
"\8I~"'I1'P"',.~YPl(
,~~ "
~Ii':.~
~:~
OWMON-r ~ 'WANFAU.
'"
""0"fi..,- - I,
"", . ,.,~""
Mid.oint West = 1143
"t%1V- 1:-AU. ""
""'.'M
"'" ~M
Existing System - Midpoint-Rattlesnake #2 Outage
Figure 2
Phase #1 Transmission Improvements
The Midpoint Series Capacitor banks are capable of 110% of thennal rating on a continuous
basis. As a result, only the Upper Salmon-Mountain Home Junction 103% overload is
problematic. The most effective and cost-efficient transmission improvement to alleviate this
overload is the installation of a series reactor on the Upper Salmon-Mountain Home Junction
138 kV line to better balance flows on the transmission network. The optimum size of the
series reactor was detennined to be 19 ohms for the ultimate build-out of the transmission grid.
Since this N-l overload condition pre-exists the addition of any new generation in the Twin
Falls area, Idaho Power Company would take responsibility to fund this series reactor
installation.
The following one line diagram depicts the system with Phase #1 improvements added, no new
generation in the Twin Falls area, and the same N-l as Figure 2.
8OlSEBOH
"""
Mid.oint West = ..1
"'DPO'",
VI Q"
",,,
KING
""'"~g~.~ '
5I!ANF
.:'-""~.",,'~.
Phase #1 Transmission Improvements - Midpoint-Rattlesnake #2 Outage
No New Generation
Figure 3
~"'
~'_d""""."ta""'t;"'"'"'.
'I:IfS",. :::~Sokron-"""ta.wo,,"a19o1ms
Phase #2 Transmission Im rovements
The following one line diagram depicts Phase #1 transmission improvements and 7 MW of
new generation in the Twin Falls area, and the only N-l outage between Midpoint and the
Mountain Home area that results in loadings above continuous thennal ratings.
?~1'i',CH
ANDERS"' ANDE~" ""
"" """ """
~1\W"6~
...~
tr\':"Jg~
OOWMON,"'8:\'\~ ~AU. .
~. ""',,~-
Midpoint West = '85 MW
Mln, """"-Lowe. MaIad """,, leatl'" " "" ",""""=e
~5 s~~!~v
~~v
Phase #1 Transmission Improvements - Midpoint-Rattlesnake #2 Outage
7 MW of New Generation
Figure 4
BURNS
"""
Mln, ",,",,-\Wel SoImon sen"""",'m' ,1lJO""" 190m.
The most effective and cost-efficient transmission improvement to alleviate this overload is the
installation of a series reactor on the Lower Malad-Mountain Home Junction 138 kV line to
better balance flows on the transmission network. The optimum size of the series reactor was
determined to be 10.5 ohms for the ultimate build-out of the transmission grid. This overload
is the result of the addition of new generation in the Twin Falls area, and as a result the costs of
this improvement will be allocated to new generation interconnections.
The following one line diagram depicts the system with Phase #2 improvements added, 7 MW
of new generation in the Twin Falls area, and the same N-l as Figure 4.
BOISEBCH
"""
Midpoint West = 1825 MW
VI """D
;'::'
'4'~I""1'W~u. """
"""""""
Phase #2 Transmission Improvements - Midpoint-Rattlesnake #2 Outage
7 MW of New Generation
Figure 5
Phase #3 Transmission Improvements
The following one line diagram depicts Phase #2 transmission improvements and 60 MW of
new generation in the Twin Falls area, and the only N-l outage between Midpoint and the
Mountain Home area that results in loadings above continuous thermal ratings.
001"'0.01",
OOWMONT 0, '" SWA",AU. 51""
. -jfi-.
Midpoint West = 11'1
KING
""'" .J'i "... _II~7-
~'"
4'~" ."1W"'
","i:I".M
","'
i:I"."
Mtn, Hare-lowa MaIad series reocto.' ,ffi5 "" 0. 10,5 ohms'I1'f"S,. Mtn, fbTIe-Uppeo-"'rronseriesreoctor" ,100,,"0. 19o1Yns
Phase #2 Transmission Improvements - Midpoint-Rattlesnake #2 Outage
60 MW of New Generation
Figure 6
To interconnect generation quantities greater than 60 MW will require additional transmission
system improvements. The required system improvements are referred to as "Phase #3" and
include folding the Midpoint-DRAM #1 230 kV transmission line into and back out of the
King Substation and installing a 230/138 kV 300 MV A transformer. This overload is the result
of the addition of new generation in the Twin Falls area, and as a result the costs of this
improvement will be allocated to new generation interconnections.
The following one line diagram depicts the system with Phase #3 improvements added, 60
MW of new generation in the Twin Falls area, and the same N-l as Figure 6.
,?!'.~CH
Midlloint West = 11" MW
MIDPOINT
"",:, ~..
"I-AU.
....
""Mow
"" ~..._.
Mtn. _e-Low., ""'-'d ""~ ,."to, . ,055 pu or 10,5 ohmsffi"',., Mtn- Home-L\Jp.' s.koon ser~ ,""to. . ,100 pu or 19 ohms
Phase #3 Transmission Improvements - Midpoint-Rattlesnake #2 Outage
60 MW of New Generation
Figure 7
Phase #4 Transmission Improvements
The following one line diagram depicts Phase #3 transmission improvements and 135 MW of
new generation in the Twin Falls area, and the only N-l outage between Midpoint and the
Mountain Home area that results in loadings above continuous thennal ratings.
OOISE'CH01'"
:~cP
"'.M :'1f,l,~ SWANFA~
--- """:.
-:t-- ,
Midlloint West = 1111 MW
MIDPOINT
"",
"1T
"" ,.
AU. ....
"" ......",,~..""'"
'"'0"
Mtn. Home-lo"", MaIod
""~ ,.,,"" . .
055 pu or 10,5 o/'ms
Mtn. Home-uppe, s.rnon ser;es ,""tor' .100 pu or 19 oCrns
Phase #3 Transmission Improvements - Midpoint-Rattlesnake #2 Outage
135 MW of New Generation
Figure 8
To interconnect generation quantities greater than 135 MW will require additional transmission
system improvements. The required system improvements are referred to a "Phase #4" and
include reconductoring/rebuilding the King-DRAM #1 230 kV transmission line with a two
conductor bundle of 795 MCM ACSR "Tern" conductor. This rebuilt line also must be folded
into and back out of the Rattlesnake Substation north of Mountain Home. In addition
transmission modifications are required at the DRAM end of the line. This overload is the
result of the addition of new generation in the Twin Falls area, and as a result the costs of this
improvement will be allocated to new generation interconnections.
The following one line diagram depicts the system with Phase #4 improvements added, 135
MW of new generation in the Twin Falls area, and the same N-l as Figure 8.
'?1~CH
~"'~!~"~~"
'tlf",
Mtn, Hcrne-lo,,"' Maad so"", 'sactm " .055 PJ m 10,5 ohms
Mtn, Hcme-Up,,", Sakron so"", ,eactm " .100 PJ m 19 otrns
Phase #4 Transmission Improvements - Midpoint-Rattlesnake #2 Outage
135 MW of New Generation
Figure 9
Phase #4 transmission improvements are capable of accomodating approximately 305 MW of
new generation in the Twin Falls area. The following one line diagram depicts the system with
Phase #4 improvements added, 305 MW of new generation in the Twin Falls area, and the loss
of the King 230/138 kV transfonner.
\'--
/' I
M""""""
',/1
"..
'4'~:r "1W.t~ MW""M..
- ""
i::".,,
~~r "",d """,, reacle.'.O55 pu '" 10,5 am.
'm~
::: ::::..""
samen """,, reacte. . .100 pu or 19 aim;
Phase #4 Transmission Improvements - King 230/138 kV Xfmr Outage
305 MW of New Generation
Figure 10
For generator interconnections in excess of 305 MW, the addition of a second 230/138 kV
transformer at King is required.
Fault Study Results
Since this System Impact Study lumps all the proposed generation additions at King 138 kV
bus, this Draft Report makes no attempt to address fault study concerns. Each proposed
generation project will have to be evaluated individually based on its specific location.
Transient Stability Study Results
The Midpoint West Transmission System is not transient stability limited. Therefore, no
transient stability studies were performed.
10.Conclusions
The System Impact of interconnecting up to 200 MW of new generation in the Twin Falls area
to Idaho Power s 138 kV transmission system was studied. Four phases of transmission system
improvements are required to provide Network Resource Interconnection Service to 200 MW
of new generation. Phase #1 is the installation of a 19 ohm 138 kV Series Reactor on the
Upper Salmon-Mountain Home Junction 138 kV transmission line. This improvement corrects
a N-l overload that exists before any new generation is added in the Twin Falls area. As a
result, the estimated $290 000 cost of this improvement will be borne by Idaho Power
Company. After approximately 7 MW of new generation is added, Phase #1 improvements are
no longer sufficent. Phase #2 improvements require the installation of a 10.5 ohm 138 kV
Series Reactor on the Lower Malad-Mountain Home Junction 138 kV transmission line. The
10-
estimated $290 000 cost of this improvement should be allocated to new generator
interconnections. Following the addition of approximately 60 MW of new generation, Phase
#3 transmission improvements are required. Phase #3 involves folding the Midpoint-DRAM
#1 230 kV transmission line into and back out of the King Substation and installing a 230/138
kV 300 MV A transfonner. The estimated $10 320 000 cost of this improvement should be
allocated to new generator interconnections. Following the addition of approximately 135
MW of new generation, Phase #4 transmission improvements are required. Phase #4 involves
reconductoring/rebuilding the King-DRAM #1 230 kV transmission line with a two conductor
bundle of 795 MCM ACSR "Tern" conductor. This rebuilt line also must be folded into and
back out of the Rattlesnake Substation north of Mountain Home. In addition, transmission
modifications are requi~ed at the DRAM end of the line. The estimated $47 525 000 cost of
this improvement should be allocated to new generator interconnections. Phase #4
transmission improvements are adequate to interconnect approximately 305 MW of new
generation in the Twin Falls area before additional improvements are required.
11-
BEFORE THE
IDAHO PUBLIC UTiliTIES COMMISSION
CASE NO. IPC-O7-
IDAHO POWER COMPANY
Response to Staff Request No.
GENERA TOR INTERCONNECTION
SYSTEM IMP ACT STUDY REPORT
for
Up to 330 MW of New Generation
On the 138 kV Transmission System
In the Twin Falls Area
IDAHO POWER COMPANY, Transmission Provider
TRANSMISSION SYSTEM
DRAFT REPORT
June 29, 2007
1.0 Introduction
Multiple new generation projects have contacted Idaho Power Company (IPe) to perfonn
Generator Interconnection System Impact Studies for Network Resource Interconnection
Service at 138 kV for the integration of new generation projects in the Twin Falls area
This report documents the basis for and the results of this System Impact Study. Previous
studies were perfonned with these new generation projects being non-dispatchable. This
System Impact Study will document the transmission system improvements required if the new
generation projects are dispatchable. It describes the backbone transmission system
improvements required for Network Resource Interconnection Service of the new generation
proposed, the study cases used, outage scenarios assumed, redispatch requirements, and results
of all work in the areas of concern.
Summary
The perfonnance of the backbone transmission system was evaluated to integrate up to 304
MW of new generation on the 138 kV transmission system in the Twin Falls area. Five phases
of transmission system improvements are required to provide 304 MW of new generation
Network Resource Interconnection Service.
Phase #1:
Phase #2:
Phase #3:
Install a 8 ohm 138 kV Series Reactor on the Upper Salmon-Mountain Home
Junction 138 kV transmission line. Without this improvement, the outage of
the Midpoint-Rattlesnake 230 kV transmission line results in an overload of
the Upper Salmon-Mountain Home Junction 138 kV line with no new
generation in the Twin Falls area. This improvement is necessitated by the
transmission improvements associated with Generation Project 88 , and as a
result should be funded by Idaho Power Company - Delivery. This phase of
improvements is estimated at approximately $290 000.
Install a 4 ohm 138 kV Series Reactor on the Mountain Home Junction-Lucky
Peak 138 kV transmission line. Without this improvement, the outage of the
Rattlesnake-Boise Bench 230 kV transmission line results in an overload
exceeding the 30 minute emergency rating of the Mountain Home Junction-
Lucky Peak 138 kV line with new generation levels greater than 42 MW in
the Twin Falls area. This phase of improvements is estimated at
approximately $290 000.
Install a 12.35 ohm 138 kV Series Reactor on the Lower Malad-Mountain
Home Junction 138 kV transmission line and increase the impedance of the
existing Upper Salmon-Mountain Home Junction 138 kV Series Reactor to
26.2 ohms. Without this improvement, the outage of the Midpoint-
Rattlesnake 230 kV transmission line results in an overload exceeding the 30
minute emergency rating of the Lower Malad-Mountain Home Junction 138
kV line with new generation levels greater than 94 MW in the Twin Falls
area. This phase of improvements is estimated at approximately $290 000.
Phase #4:
Phase #5:
Re-configure the Midpoint-Rattlesnake 230 kV series capacitor bank to allow
1/3 of the compensation to be bypassed via IPCo s SCADA system and install
a "automatic 1/3 bypass scheme" for overloads exceeding series capacitor
30 minute emergency equipment rating of 135%. Without this improvement
the outage of the Midpoint-Boise Bench #3230 kV transmission line results
in an overload exceeding the 30 minute emergency rating of the Midpoint-
Rattlesnake 230 kv Series Capacitor Bank with new generation levels greater
than 153 MW in the Twin Falls area. This phase of improvements is
estimated at approximately $100 000.
Fold the Midpoint-DRAM #1 230 kV transmission line into the King
Substation and install a 230/138 kV 300 MV A transfonner. Without this
improvement, the outage of the Rattlesnake-Boise Bench 230 kV transmission
line results in an overload exceeding the 30 minute emergency rating of the
Mountain Home Junction-Lucky Peak 138 kV line with new generation levels
greater than 156 MW in the Twin Falls area. This phase of improvements is
estimated at $10 320 000.
Once all five phases of improvements have been completed, the transmission system is capable
of interconnecting approximately 330 MW of new generation in the Twin Falls area and
serving them on a dispatchable basis.
Section 8.0 of this report details the results of studies to quantify generation redispatch
requirements following single contingencies on the transmission system. Reductions in the
amount of generation which may be redispatched following contingencies, are possible by
completing Phase #4 improvements earlier than required or funding optional modifications on
the Midpoint-Boise Bench #3 series capacitor bank.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). The proposed
cost allocation is subject to change, as more infonnation is known. These are cost estimates
only and final charges to the customer will be based on the actual construction costs incurred.
Summary of Interconnection Requests
Requests were made to Idaho Power Co. by multiple generation projects in the Twin Falls area
to study the interconnection of the proposed generation projects to Idaho Power s transmission
system at the 138 kV level for Network Resource Interconnection Service.
Scope of Interconnection System Impact Study
The Interconnection System Impact Study was done and prepared in accordance with the
FERC Order 2003-, Standard Large Generator Interconnection Procedures, to provide a
preliminary evaluation of the System Impact of the interconnection of the proposed large
generating project to the Idaho Power transmission system. This study will only be concerned
with the capabilities of the Idaho Power system to manage this new resource within the study
area of the proposed interconnection.
Description of Existing Transmission Facilities
As shown in Figure 1 of Section 7., Midpoint Substation, north of Twin Falls , has three 230 kV
lines that carry bulk power westward to the Boise area. Midpoint-DRAM #1 line utilizes single
715.5 MCM conductor and has a continuous rating of339 MV A. The Midpoint-Rattlesnake-Boise
Bench #2 line utilizes a 2 conductor bundle of715.5 MCM. This line has a continuous rating of
677 MV A. The Midpoint-Boise Bench #3 line has similar conductors and the same rating as the
Rattlesnake-Boise Bench #2 line. In the Mountain Home area, an additional 230 kV line is
planned to carry bulk power westward. The Rattlesnake-Bennett Mountain-Danskin-Mora line
utilizes single 1272 MCM conductors (478 MVA) from Rattlesnake-Bennet Mountain, single 1590
MCM conductors (550 MV A) from Bennet Mountain-Danskin and Danskin-Mora. The Bennett
Mountain-Danskin-Mora transmission lines are required for the interconnection of Generation
Project 88; scheduled to be in-service Spring of2008.
In addition to the Midpoint to the Boise area 230 kV lines previously mentioned, there are two
138 kV circuits which can carry power from the Twin Falls area to the Mountain Home area.
They are:
King-Lower Malad-Mountain Home Junction 138 kV Line
King-Upper Salmon-Mountain Home Junction 138 kV Line
Generators located in the Twin Falls area which are intended to serve load growth in the Treasure
Valley area, will be adding new incremental flows on top of existing committed east-to-west
transactions across the Midpoint West transmission cutplane. This System Impact study will
model approximately 1100 MW of transfers across the Midpoint West cutplane, prior to this
proposed generator addition. For these studies, the flow level of the Midpoint west cutplane is
defined as the sum of the flows on the following lines:
. Midpoint-DRAM #1 230 kV line
. Midpoint-Rattlesnake 230 kV Line
. Midpoint-Boise Bench #3 230 kV Line
Lower Malad-Mountain Home Junction 138 kV Line
Upper Salmon-Mountain Home Junction 138 kV Line
Description of Configurations Studied
Since the most limiting operating conditions are expected during heavy production on the
upper and middle Snake and Boise River hydro plants, with heavy east-west transfers across
the Idaho Power transmission system, the injection of the new generation at King 138 kV bus
was inserted into a power flow case that would simulate committed (approximately 1100 MW)
pre-contingency flows on the Midpoint West transmission path.
Post-transient Study Results
This Interconnection System Impact Study Report is for Network Resource Interconnection
Service at 138 kV, for numerous proposed generation additions in the Twin Falls area. System
transfers across the Midpoint West cutplane are modeled at approximately 1100 MW prior to
the proposed transmission improvements or the proposed generators producing any power.
Hydro generation production for the Boise & Snake plants, were modeled at heavy, but
realistic levels. Output levels for the existing peakers at Danskin and Bennett Mountain were
varied over their operating ranges as appropriate. N-O and N-1 outage perfonnance for the
existing system are recorded. For generation projects which will be dispatchable, generation
levels at King 138 kV bus are increased until a transmission system component reaches its 30
minute emergency equipment ratings during N-1 outages. IPCo s 30 minute emergency
equipment ratings are 115% of continuous thennal ratings on transmission lines and
transfonners, and 135% on Midpoint series capacitors. The most effective and cost-efficient
transmission system improvements are then added to the model and King generation is then
increased until 30 minute emergency equipment ratings are reached during N-1 outages.
Following any N-1 outage, transmission line and transfonner loadings which are less than or
equal to the 30 minute emergency equipment ratings (115%), but greater than the equipment
continuous ratings (100%), must be reduced to the continuous ratings by generation
curtailments, redispatch, or some other operating procedure. For the Midpoint series capacitor
banks, following any N-1 outage, similar corrective actions are required for loadings which are
less than or equal to the 30 minute emergency equipment ratings (135%), but greater than the
equipment 8 hour rating (110%). Various options to correct overloads following N -1 outages
will be explored.
System followinl! Generation Project 88
The following one line diagram depicts the transmission system with no outages, after the
addition of Generation Project 88 and its associated improvements.
'0""'"0".
-::" "~8,'~' "(~\'",'~:: rP
- .- "'~~
1i~~
~' ~ '
MldDolnt West = 1109 MW
'~'"'.- '"'""~
,"W
"'"
,"'M
..
""'1~~" b
System following Generation Project 88 - No Outages
Figure 1
System followin2 Generation Project 88 with N-1 Outa2es
The following one line diagram depicts the transmission system following the addition of
Generation Project 88 and its associated improvements in 2008 , with no new generation in the
Twin Falls area, and the only N-I outage between Midpoint and the Mountain Home area that
results in loadings above continuous thermal ratings on the 138 kV transmission system.
'0""'"
'-""
MldDolnt West = 1038 MW
5~'
'" '-
5wwm
"".~~.."" .~~..
System following Generation Project 88 - Midpoint-Rattlesnake 230 kV Outage
Figure 2
Phase #1 Transmission Im rovements
The Midpoint Series Capacitor banks are capable of 110% of thermal rating for eight hours. A
prolonged outage of the Midpoint-Rattlesnake 230 kV line will require a reduction of transfers
across the Midpoint West cutplane to prepare for the next contingency. The overload of the
Midpoint-Boise Bench #3 Series Capacitor is less than its 8 hour rating, and will be resolved
with the reduction in transfers. As a result, only the overloads on the 138 kV lines between
Upper Salmon and Mountain Home Junction are problematic. The most effective and cost-
efficient transmission improvement to alleviate these overloads is the installation of a series
reactor on the Upper Salmon-Mountain Home Junction 138 kV line to better balance flows on
the transmission network. A series reactor with an impedance of .042 pu(8 ohms) alleviates
the overloads. Since this N-I overload condition pre-exists the addition of any new generation
in the Twin Falls area, Idaho Power Company will take responsibility to fund this series reactor
installation.
The following one line diagram depicts the system with Phase #1 improvements added, no new
generation in the Twin Falls area, and the same N-I as Figure 2.
n1'
:'"
MldDolnt West = 1038 MW
'WN'
'" -
'w'","'-
'-,"
1- "'
"" :~:'.."" :~:",
Phase #1 Transmission Improvements - Midpoint-Rattlesnake 230 kV Outage
NoN ew Generation
Figure 3
Phase #2 Transmission Improvements
The following one line diagram depicts Phase #1 transmission improvements and 42 MW of
new generation in the Twin Falls area, and the only N-l outage that results in loadings at or
above 30 minute equipment ratings.
'OISE""
'-"'"~""
~82
::"":~\'"
M;: rP .
- "'
~'"O!~;: rP '"0""",
fi' "~
MldDolnt West = 1077 MW
~fiiJ-1 "'u
~ "
""1~:'"
"" 1~:'"
Phase #1 Transmission Improvements - Rattlesnake-Boise Bench #2 230 kV Outage
42 MW of New Generation
Figure 4
The most effective and cost-efficient transmission improvement to alleviate this overload is the
installation of a series reactor on the Mountain Home Junction-Lucky Peak 138 kV line to
better balance flows on the transmission network. A series reactor with an impedance of .021
pu( 4 ohms) was detennined to be the optimal size considering future generation additions.
This overload is the result of the addition of new generation in the Twin Falls area, and as a
result the costs of this improvement will be allocated to new generation interconnections.
The following one line diagram depicts the system with Phase #2 improvements added, 42
MW of new generation in the Twin Falls area, and the same N-l as Figure 4. Please note that
generation redispatch will be required following this contingency to reduce loadings to levels
which can be accommodated continuously.
n1'
:'"~" ~g,':;'
"1',j'"
!~.
~ r1' .' '" ~'"O
!~:'.r1'
""""
Vi~
Midpoint West = 1075
fj/~r 'w "'~
~ '.
"'1~~"
""1~~"
Phase #2 Transmission Improvements - Rattlesnake-Boise Bench #2 230 kV Outage
42 MW of New Generation
Figure 5
Phase #3 Transmission Im rovements
The following one line diagram depicts Phase #2 transmission improvements and 94 MW of
new generation in the Twin Falls area, and the only N-l outage that results in loadings at or
above 30 minute equipment ratings.
- 7-
?b\"
:'"
MldDolnt West = 1106
'W"
" -
sw'""~
..,...."..
""3~~,,
"" 3~~"
Phase #2 Transmission Improvements - Midpoint-Rattlesnake 230 kV Outage
94 MW of New Generation
Figure 6
To interconnect generation quantities greater than 94 MW will require additional transmission
system improvements. The most effective and cost-efficient transmission improvements to
alleviate these overloads is the installation of a new series reactor on the Lower Malad-
Mountain Home Junction 138 kV line and an increase in the impedance of the Upper Salmon-
Mountain Home Junction 138 kV line series reactor. These improvements, referred to as Phase
, will better balance flows on the transmission network. A Lower Malad-Mountain Home
Junction series reactor impedance of .065 pu(12.35 ohms) was detennined to be the optimal
size considering future generation additions. The impedance of the Upper Salmon-Mountain
Home Junction series reactor should be increased to .138 pu(26.2 ohms). This overload is the
result of the addition of new generation in the Twin Falls area, and as a result the costs of this
improvement will be allocated to new generation interconnections.
The following one line diagram depicts the system with Phase #3 improvements added, 94
MW of new generation in the Twin Falls area, and the same N-l as Figure 6.
n\'
,:."
MldDolnt West .. 1099
'WN'
'" -
'w'""~
..,
'MW","'M'"
"'" g~:",
Phase #3 Transmission Improvements - Midpoint-Rattlesnake 230 kV Outage
94 MW of New Generation
Figure 7
Phase #4 Transmission Improvements
The following one line diagram depicts Phase #3 transmission improvements and 153 MW of
new generation in the Twin Falls area, and the only N-l outage that results in loadings at or
above 30 minute equipment ratings.
~"'
f&i::1" "('oj'"~t:P
" "
M'"
t~:t. t:P
'OWMO"
~"~:'
'W'""~
---.:.fr.
MldDolnt West .. 1172
MIOW" MLO'CO"' "tn,sex:-
"",".."
It...." "tn,scx:-""pu
MLO'CO"''/' 0,
Phase #3 Transmission Improvements - Midpoint-Boise Bench #3 230 kV Outage
153 MW of New Generation
Figure 8
To interconnect generation quantities greater than 153 MW will require additional transmission
system improvements. Ifnew generation levels exceed 153 MW, and the Midpoint-Boise
Bench #3230 kV line opens, the series capacitor bank on the Midpoint-Rattlesnake 230 kV
transmission line may exceed its 30 minute overload capability of 135%. Presently, both the
230 kV series capacitor banks at Midpoint are configured to operate either fully inservice or
fully by-passed. The most effective and cost-efficient transmission improvement to alleviate
this overload is the re-configuration of the Midpoint-Rattlesnake 230 kV series capacitor bank
to allow one third of the compensation to be bypassed. In addition, an automatic control
scheme should be employed to bypass one third of the series capacitor bank when appropriate
system conditions are detected. The re-configuration of the series capacitor bank and the
addition of the automatic control scheme is referred to as Phase #4.
The following one line diagram depicts the system with Phase #4 improvements added, 153
MW of new generation in the Twin Falls area, and the same N-l as Figure 8.
n\'
,:."~?'
~" A~8J~' ~',,\'"
~~:!.cP.
~,"
M:!.cP. -
",,"'",
fi"
~~~
MldDolnt West a 1145 MW
:;?j(~~~" ::~::~~::::::::
""'01"
--
"./1 Woo
'W"
"'-
'WA"Au.B I_BOO 'OW"",B"'"
!~~"~"",,""'
00.. .. 0_98.. 0_
".."'"
L"OO
Phase #4 Transmission Improvements - Midpoint-Boise Bench #3 230 kV Outage
153 MW of New Generation
Figure 9
Phase #5 Transmission Im rovements
The following one line diagram depicts Phase #4 transmission improvements and 156 MW of
new generation in the Twin Falls area, and the only N-l outage that results in loadings at or
above 30 minute equipment ratings.
10-
'01"""L"..
~",'
m:::""(~\",
,.~~ .,p .. ..
~:"O
'~.~.,p
,"0'"'"'
Yi' "': -:iF
.:.
MldDolnt West = 1151
Phase #4 Transmission Improvements - Rattlesnake-Boise Bench #2 230 kV Outage
156 MW of New Generation
Figure 10
To interconnect generation quantities greater than 156 MW will require additional transmission
system improvements. Ifnew generation levels exceed 156 MW, and the Rattlesnake-Boise
Bench #2230 kV line opens, the Mountain Home Junction-Lucky Peak 138 kV transmission
line may exceed its 30 minute overload capability of 115%. The required system
improvements are referred to as "Phase #5" and include folding the Midpoint-DRAM #1 230
kV transmission line into and back out of the King Substation and installing a 230/138 kV 300
MV A transformer. This overload is the result of the addition of new generation in the Twin
Falls area, and as a result the costs of this improvement will be allocated to new generation
interconnections.
The following one line diagram depicts the system with Phase #5 improvements added, 156
MW of new generation in the Twin Falls area, and the same N-l as Figure 10.
11-
'OIS"'"
"'"~"'
r~IW "j'oj'";~::: cf'
.- '" ~-
'"O
;~:::cf' "'EO'",
~~~ jf-
MldDolnt West = 1165
~&. '"
~~O . ~.'I~:::,
----- -
::if-
, ---- . . -'- . -
'--- . --I--
-~-,.,..-~-
GU'","~OM' """",BE"'" """"
"'"
. ~'O,"8", '-" pu 1-02pu 1-02",
Phase #5 Transmission Improvements - Rattlesnake-Boise Bench #2 230 kV Outage
156 MW of New Generation
Figure 11
Phase #5 transmission improvements are capable of accommodating approximately 330 MW
of new generation in the Twin Falls area. The following one line diagram depicts the system
with Phase #5 improvements added, 330 MW of new generation in the Twin Falls area, and the
loss of the Midpoint-Rattlesnake 230 kV transmission line. At 330 MW of new generation in
the Twin Falls area, two other outages also result in transmission system components loaded at
their 30 minute emergency equipment ratings.
"""""'"
MldDolnt West.. 1272
l'litiIJ
,,~- """"!~~""'" !~~";'(
Phase #5 Transmission Improvements - Midpoint-Rattlesnake #2 230 kV Outage
330 MW of New Generation
Figure 12
12-
Generation Redispatch Requirements
Generators which have chosen to be dispatchable are allowed to operate at levels which may
create overloads at or below 30 minute emergency equipment ratings following N-
contingencies. Following any N -1 outage, transmission line and transformer loadings which
are less than or equal to the 30 minute emergency equipment ratings (115%), but greater than
the equipment continuous ratings (100%), must be reduced to the continuous ratings by
generation curtailments, redispatch, or some other operating procedure. For the Midpoint
series capacitor banks, following any N -1 outage, similar corrective actions are required for
loadings which are less than or equal to the 30 minute emergency equipment ratings(135%),
but greater than the equipment 8 hour rating( 110%).
The following table summarizes generation curtailment requirements for the proposed
generation projects modeled at King 138 kV Substation; for various timeframes, and for
numerous transmission system single contingencies.
The fourth column of the table provides information regarding potential benefits of requesting
and funding an optional improvement. The improvement evaluated is the re-configuration of
the Midpoint-Boise Bench #3230 kV series capacitor bank to allow one third of the
compensation to be bypassed. Unlike Phase #4, no automatic control scheme is contemplated.
This Optional Improvement may reduce the magnitude of generation which must be
redispatched during a Midpoint-Rattlesnake 230 kV Transmission Line outage. The Optional
Improvement is estimated at approximately $50 000.
The fifth column of the table provides information regarding potential benefits of completing a
portion of Phase #4 improvements early. Phase #4 improvements can be separated into two
components. The first component is the "re-configuration" of the Midpoint-Rattlesnake 230
kV series capacitor so it can be operated "fully inservice
, "
1/3 bypassed"
, "
2/3 bypassed", or
fully bypassed". The second component was the "automatic control scheme . The Phase #4a
improvement contained in the fifth column is for expediting only the "re-configuration
component. Expediting the phase #4a improvement may reduce the magnitude of generation
which must be redispatched during a Midpoint-Boise Bench #3230 kV Transmission Line
outage. The Phase #4a improvement is estimated at approximately $50 000.
13-
Maximum Maximum
Maximum Allowable Allowable
Allowable Maximum Generation Generation
Generation Allowable After N-After N-
Before Generation w/Optional w/Phase #4a
Contin2ency After N-Improvement Improvement
After Phase #1 , but before Phase #2
Midpoint-Boise Bench #3230 kV Line 42MW OMW OMW 42MW
Midpoint-Rattlesnake 230 kV Line 42MW 7MW 7MW 7MW
Rattlesnake-Boise Bench 230 kV Line, also
open Mountain Home Junction-Danskin 138 42MW 9MW 9MW 9MW
kV Line
Danskin-Mora 230 kV Line, also open
Mountain Home Junction-Danskin 138 kV 42MW 42MW 42MW 42MW
Line
After Phase #2, but before Phase #3
Midpoint-Boise Bench #3 230 kV Line 94MW OMW OMW 94MW
Midpoint-Rattlesnake 230 kV Line 94MW 9MW 9MW 9MW
Rattlesnake-Boise Bench 230 kV Line, also
open Mountain Home Junction-Danskin 138 94MW 32MW 32MW 32MW
kV Line
Danskin-Mora 230 kV Line, also open
Mountain Home Junction-Danskin 138 kV 94MW 80MW 80MW 80MW
Line
Mountain Home Junction-Lower Malad 138 94MW 49MW 49MW 49MWkV Line
Lucky Peak-Micron 138 kV Line 94MW 45MW 45MW 45MW
Danskin 230/138 kV Transformer 94MW 90MW 90MW 90MW
After Phase #3, but before Phase #4
Midpoint-Boise Bench #3230 kV Line 153 MW OMW OMW 153 MW
Midpoint-Rattlesnake 230 kV Line 153 MW l7MW 53MW l7MW
Rattlesnake-Boise Bench 230 kV Line, also
open Mountain Home Junction-Danskin 138 153 MW 71MW 71MW 71MW
kV Line
Danskin-Mora 230 kV Line, also open
Mountain Home Junction-Danskin 138 kV 153 MW 120 MW 120 MW 120 MW
Line
Mountain Home Junction-Lower Malad 138 153 MW 129 MW 129 MW 129 MWkV Line
Lucky Peak-Micron 138 kV Line 153 MW 84MW 84MW 84MW
Danskin 230/138 kV Transformer 153 MW 125 MW 125 MW 125 MW
14-
Maximum Maximum
Maximum Allowable Allowable
Allowable Maximum Generation Generation
Generation Allowable After N-After N-
Before Generation w/Optional w/Phase #4a
Contin2ency After N-Improvement Improvement
After Phase #4 but before Phase #5
Midpoint-Boise Bench #3230 kV Line 156 MW 156 MW 156 MW N/A
Midpoint-Rattlesnake 230 kV Line 156 MW 18MW 53MW N/A
Rattlesnake-Boise Bench 230 kV Line, also
open Mountain Home Junction-Danskin 138 156 MW 71MW 71MW N/A
kV Line
Danskin-Mora 230 kV Line, also open
Mountain Home Junction-Danskin 138 kV 156 MW 120 MW 120 MW N/A
Line
Mountain Home Junction-Lower Malad 138 156 MW 129 MW 129 MW N/AkV Line
Lucky Peak-Micron 138 kV Line 156 MW 84MW 84MW N/A
Danskin 230/138 kV Transfonner 156 MW 125 MW 125 MW N/A
After Phase #5
Midpoint-Boise Bench #3 230 kV Line 330 MW 140 MW 140 MW N/A
Midpoint-Rattlesnake 230 kV Line 330 MW 25MW 123 MW N/A
Rattlesnake-Boise Bench 230 kV Line, also
open Mountain Home Junction-Danskin 138 330 MW 254 MW 254 MW N/A
kV Line
Danskin-Mora 230 kV Line, also open
Mountain Home Junction-Danskin 138 kV 330 MW 310 MW 31OMW N/A
Line
Mountain Home Junction-Lower Ma1ad 138 330 MW 280 MW 280 MW N/AkV Line
Lucky Peak-Micron 138 kV Line 330 MW 265 MW 265 MW N/A
Danskin 230/138 kV Transfonner 330 MW 295 MW 295 MW N/A
King 230/138 kV Transfonner 330 MW 245 MW 245 MW N/A
Fault Study Results
Since this System Impact Study lumps all the proposed generation additions at King 138 kV
bus, this Draft Report makes no attempt to address fault study concerns. Each proposed
generation project will have to be evaluated individually based on its specific location.
10.Transient Stability Study Results
The Midpoint West Transmission System is not transient stability limited. Therefore, no
transient stability studies were perfonned.
15-
11.0 Conclusions
The System Impact of interconnecting up t0304 MW of new generation in the Twin Falls area
to Idaho Power s 138 kV transmission system was studied. Five phases of transmission system
improvements are required to provide Network Resource Interconnection Service to 304 MW
of new generation, on a dispatchable basis. Phase #1 is the installation ofa 8 ohm 138 kV
Series Reactor on the Upper Salmon-Mountain Home Junction 138 kV transmission line. This
improvement corrects a N-1 overload that exists before any new generation is added in the
Twin Falls area. As a result, the estimated $290 000 cost of this improvement will be borne by
Idaho Power Company. After approximately 42 MW of new generation is added, Phase #1
improvements are no longer sufficent. Phase #2 improvements require the installation of a 4
ohm 138 kV Series Reactor on the Mountain Home Junction-Lucky Peak 138 kV transmission
line. The estimated $290 000 cost of this improvement should be allocated to new generator
interconnections. Following the addition of approximately 94 MW of new generation, Phase
#3 transmission improvements are required. Phase #3 improvements require the installation a
12.35 ohm 138 kV Series Reactor on the Lower Malad-Mountain Home Junction 138 kV
transmission line, and increasing the impedance of the existing Upper Salmon-Mountain Home
Junction 138 kV Series Reactor to 26.2 ohms. The estimated $290 000 cost of Phase #3
improvements should be allocated to new generator interconnections. Following the addition
of approximately 153 MW of new generation, Phase #4 transmission improvements are
required. Phase #4 involves re-configuring the Midpoint-Rattlesnake 230 kV series capacitor
bank to allow 1/3 of the compensation to be bypassed via IPCo s SCADA system and install a
automatic 1/3 bypass scheme" for overloads exceeding the series capacitor s 30 minute
emergency equipment rating of 135%. The estimated $100 000 cost of this improvement
should be allocated to new generator interconnections. Following the addition of
approximately 156 MW of new generation, Phase #5 transmission improvements are required.
Phase #5 involves folding the Midpoint-DRAM #1 230 kV transmission line into and back out
of the King Substation and installing a 230/138 kV 300 MV A transfonner. The estimated
$10 320 000 cost of this improvement should be allocated to new generator interconnections.
Phase #5 transmission improvements are adequate to interconnect approximately 330 MW of
new generation in the Twin Falls area, on a dispatchable basis, before additional improvements
are required.
16-
APPENDIX A
1.0 Method of Study
The study methodology inserts the proposed generators up to the maximum requested output of
304 MW into the selected WECC power flow case and then, using the PowerWorid Simulator
powerflow program, examines the impacts of the new resource on Idaho Power s transmission
system (lines, transformers, etc.) within the study area under various operating/outage
scenarios. The WECC and Idaho Power reliability criteria and Idaho Power operating
procedures were used to determine the acceptability of the alternatives considered. The WECC
case is a recent cases modified to simulate stressed but reasonable pre-contingency energy
transfers utilizing the IPC system.
Acceptability Criteria
The following acceptability criteria were used in the power flow analysis to determine the
acceptability of the alternatives:
Loadings on transmission lines and transformers should not exceed 115% of the
continuous rating, immediately following any N-l outage. Loading on the Midpoint
230 kV series capacitors should not exceed 135% of the continuous rating, immediately
following any N-l outage. These loadings levels of 115% on transmission lines and
transformers and 135% on Midpoint series capacitors correspond to IPC's 30 minute
emergency equipment ratings. Any loadings immediately following an N-l outage
less than the 30 minute emergency rating is acceptable.
Loadings which are less than the 30 minute emergency equipment ratings, but greater
than the equipment continuous ratings, must be reduced to the continuous ratings by
generation curtailments, re-dispatch, or some other operating procedure. Any remedial
action schemes(RAS) or other transmission switching, must be judged to be reasonable
before the alternatives performance can be deemed acceptable.
The continuous rating of equipment is assumed to be the normal thermal rating of the
equipment. This rating will be as determined by the manufacturer of the equipment or
as determined by Idaho Power. Less than or equal to 100% of continuous rating for
transmission lines and transformers is acceptable. Less than or equal to 110% of
continuous rating for the Midpoint 230 kV series capacitors is acceptable.
Transmission voltages, under normal operating conditions, are maintained within plus
or minus 5% (0.05 per unit) of nominal. Therefore, voltages greater than or equal to
95 pu voltage and less than or equal to 1.05 pu voltage are acceptable.
The stable operation of the transmission system requires an adequate supply of volt-
amperes reactive (V ARs) to maintain a stable voltage profile under both steady-state
and dynamic system conditions. An inadequate supply of V ARs will result in voltage
decay or even collapse under the worst conditions. Idaho Power designs its system to
integrate Network Resources at full capability during specified outage conditions.
17-
Equipment/line/path ratings used will be those that are in use at the time of the study or that are
represented by IPC upgrade projects that are either currently under construction or whose
budgets have been approved for construction in the near future. All other potential future
ratings are outside the scope of this study. Future transmission changes may, however, affect
current facility ratings used in the study.
18-