20060717IPC to Staff 25, 75, part I.pdf

~~,~,---~,~-
IDAHO POWER COMPANY
R E eEl V E 0O, BOX 70
BOISE, IDAHO 83707
2006 JUL I 1+ PH 4= 51
IDAHO PUBLIC
UTILITIES COMMISSION
Monica Moen
AttorneyAn IDACORP Company
July 14 , 2006
Jean D. Jewell, Secretary
Idaho Public Utilities Commission
472 West Washington Street
P. O. Box 83720
Boise, Idaho 83720-0074
Re:Case No. IPC-06-
Idaho Power Company s Response to the First Production Request of
Commission Staff
Dear Ms. Jewell:
Please find enclosed for filing an original and two (2) copies of Idaho Power
Company s Response to the First Production Request of Commission Staff regarding the
above-described case.
I would appreciate it if you would return a stamped copy of this transmittal letter
to me in the enclosed self-addressed stamped envelope.
Very truly yours
~'-
Monica B. Moen
MBM:sh
Enclosures
Telephone [phone] Fax [phone], E-mail MMoen(g)idahopower.com
BARTON L. KLINE ISB #1526
MONICA B. MOEN ISB #5734
Idaho Power Company
P. O. Box 70
Boise , Idaho 83707
Telephone: [phone]
FAX Telephone: [phone]
RECE\VEO
100G JUL \ 4 PH 4: 5 ,
IDAHO PUBLIC
UTILITIES COMMISSION
Attorney for Idaho Power Company
Street Address for Express Mail
1221 West Idaho Street
Boise, Idaho 83702
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
IN THE MATTER OF THE APPLICATION
OF IDAHO POWER COMPANY FOR A
CERTIFICATE OF PUBLIC CONVENIENCE
AND NECESSITY FOR THE RATE BASING
OF THE EV ANDER ANDREWS POWERPLANT.
CASE NO. IPC-06-
IDAHO POWER COMPANY'
RESPONSE TO THE FIRST
PRODUCTION REQUEST OF
COMMISSION STAFF
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 16, 2006, herewith submits the following information:
IDAHO POWER COMPANY'S RESPONSE TO FIRST
PRODUCTION REQUEST OF COMMISSION STAFF Page
REQUEST NO. 25: Please provide information supporting the
transmission costs assumed by Idaho Power for each of the bids considered. Include
cost assumptions , transmission losses , and any other transmission factors considered.
RESPONSE TO REQUEST NO. 25: Please refer to the documents
attached hereto as "Response to Request No. 25.
The response to this request was prepared by Monica Moen, Attorney II
Idaho Power Company.
IDAHO POWER COMPANY'S RESPONSE TO FIRST
PRODUCTION REQUEST OF COMMISSION STAFF Page 2
REQUEST NO. 75: For all intervenor requests , please provide the
confidential responses to Staff even if the Company is unable to provide the information
to that-party.
RESPONSE TO REQUEST NO. 75: With respect to confidential information
requested by Mountain View Power, Inc. ("MVP") that was not provided to MVP , Idaho
Power has provided the requested confidential information to the Commission Staff as
follows:
Response to MVP Request No.1 (a)The confidential information requested by
MVP in its Request No.1 (a) has been provided to the Commission Staff in Idaho
Power s Response to Commission Staff Request No.
Response to MVP Request No. : The confidential information requested by
MVP in its Request No. 14 has been provided to the Commission Staff in Idaho Power
Response to Commission Staff Request No. 45.
The response to this request was prepared by Monica Moen, Attorney II , Idaho
Power Company.
(t.
MONICA B. MOEN
Attorney for Idaho Power Company
IDAHO POWER COMPANY'S RESPONSE TO FIRST
PRODUCTION REQUEST OF COMMISSION STAFF Page 3
CERTIFICATE OF SERVICE
I HEREBY CERTIFY that on this 14th day of July, 2006, I served a true and
correct copy of the within and foregoing IDAHO POWER COMPANY'S RESPONSE TO
THE FIRST PRODUCTION REQUEST OF COMMISSION STAFF upon the following
named parties by the method indicated below, and addressed to the following:
Commission Staff --2L Hand Delivered
Donovan Walker US. Mail
Deputy Attorney General Overnight Mail
Idaho Public Utilities Commission FAX
472 W. Washington (83702)Email: Donovan.walker(g)puc.idaho.gov
O. Box 83720
Boise, Idaho 83720-0074
Industrial Customers of Idaho Power Hand Delivered
Peter 1. Richardson, Esq.u.S. Mail
Richardson & O'Leary Overnight Mail
515 N. 27th Street FAX
O. Box 7218 Email: peter(g)richardsonandoleary.com
Boise, Idaho 83702
Don Reading
Ben Johnson Associates Hand Delivered
6070 Hill Road u.S. Mail
Boise, Idaho 83702 Overnight Mail
FAX
Email: dreading (g) mindspring.com
Mountain View Power, Inc.Hand Delivered
Ronald L. Williams --2L u.S. Mail
Williams Bradbury, P.Overnight Mail
O. Box 2128 FAX
Boise, Idaho 83701 Email: ron(g)williamsbradbury.com
Robert D. Looper, President Hand Delivered
Mountain View Power, Inc.u.S. Mail
1015 W. Hays Street Overnight Mail
Boise, Idaho 83702 FAX
Email: rlooper(g)spellc.com
~ (3.
Monica B. Moen
CERTIFICATE OF SERVICE, Page
IDAHO POWER COMPANY
CASE NO. IPC-O6-
FIRST PRODUCTION REQUEST
OF COMMISSION STAFF
RESPONSE TO
REQUEST NO. 25
LARGE GENERATOR INTERCONNECTION
FEASIBILITY STUDY REPORT
for the
230 KV INTERCONNECTION OPTION
EAST BOISE SITE
for
Idaho Power Company - Power Supply, Interconnection Customer
for connection of
A 200 MW OR 85 MW SIMPLE CYCLE GAS TURBINE PEAKING PROJECT
EAST BOISE SITE
IDAHO POWER COMPANY, Transmission Provider
TRANSMISSION SYSTEM
FINAL REPORT
September 9, 2005
, .
1.0 Introduction
Idaho Power Company - Power Supply has contracted with Idaho Power Company (IPC) to
perform a Large Generator Interconnection Feasibility Study for Network Resource
Interconnection Service at 230 kV for the integration of either a new 200 MW or 85 MW
simple cycle gas turbine peaking project. The proposed location is the East Boise Site near the
S. Eisenman Road Exit 59A on Interstate 84 just East of Boise, Idaho.
This report documents the basis for and the results of this Feasibility Study. It describes the
proposed interconnection alternatives, the study cases used, outage scenarios assumed and
results of all work in the areas of concern.
Summary
The performance of a 230 kV interconnection alternative was evaluated to integrate a 200 MW
simple cycle gas turbine, located at the East Boise Site, into the Idaho Power System. A
detailed description of the location ofthe East Boise Site can be found in Section 5.0 of this
report. Idaho Power Company - Power Supply has requested Interconnection Feasibility
Studies for two units of different sizes at the East Boise Site. The larger unit is rated 200 MW
1$ -7 degrees C(winter rating) and 174 MW 1$ 32 degrees C(summer rating). The smaller unit
is rated 85 MW 1$ -7 degrees C(winter rating) and 73.1 MW 1$ 32 degrees C(summer rating).
It is. our understanding that only one unit will be selected for construction at this time. The
same 230 kV interconnection alternative was selected for evaluation for each proposed unit.
The 230 kV interconnection alternative performed acceptably for the 174/200 MW unit. This
interconnection alternative is estimated to cost approximately $3 million. The smaller 73/85
MW unit will require the same interconnection facilities, thus have the same interconnection
cost. We find no reason to believe the smaller unit would result in operational problems that
were not apparent for the larger unit.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). These are cost
estimates only and final charges to the customer will be based on the actual construction costs
incurred.
Summary of Interconnection Request
A request was made to Idaho Power Co. by Idaho Power Company - Power Supply to study the
interconnection of either a proposed 174/200 MW or a proposed 73/85 MW simple cycle gas
turbine at the East Boise Site, near Boise, Idaho, to Idaho Power s transmission system at the
230 kV level for Network Resource Interconnection Service.
Scope of Interconnection Feasibility Study
The Interconnection Feasibility Study was done and prepared in accordance with the FERC
Order 2003-, Standard Large Generator Interconnection Procedures , to provide a preliminary
evaluation of the feasibility ofthe 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 Proposed Generating Project
Idaho Power Company - Power Supply proposes to connect one or the other of two different
sized simple cycle gas turbines to the Idaho Power 230 kV transmission system, at the East
Boise Site. The East Boise Site is located at Boise Meridian Township 2N, Range 2E, NW1I4
ofNE1I4 of Section 13. The larger unit is rated 200 MW
~ -
7 degrees C(winter rating) and
174 MW ~ 32 degrees C(summer rating). The smaller unit is rated 85 MW
~ -
7 degrees
C(winter rating) and 73.1 MW ~ 32 degrees C(summer rating). It is our understanding that
only one unit will be selected for construction at this time.
The equipment for the larger unit is described as being, a Siemens SGT6-5000F CT ECNO
Pack. The general equipment description for the smaller unit is a GE 7F A Package. The
proposed commercial operation date is April 1 , 2007, for either unit.
Description of Existing Transmission Facilities
The East Boise Site geographically lies under the Boise Bench to Caldwell 230 kV
transmission line. The closest 138 kV line is approximately 1 mile away. At the Scoping
Meeting for these Interconnection Requests, it was agreed that the interconnection voltage to
be studied would be 230 kV. It was anticipated that the cost of a 138 kV alternative would be
similar to the 230 kV alternative with no apparent performance advantage.
The East Boise Site is approximately 8 circuit line miles out of the Boise Ben.ch Substation on
the Boise Bench to Caldwell 230 kV line.
,';..
Description of Configurations Studied
Since the most limiting operating conditions are expected during summer peak load conditions
the injection of the simple cycle gas turbine s 174 MW summer rated output was inserted into
a 2006 power flow case that would simulate peak summer loads in the Boise area.
The interconnection alternative selected for evaluation was a fold of the Boise Bench to
Caldwell 230 kV line and construction of a new 230 kV substation utilizing three 230 kV
circuit breakers. The three terminal ring bus configuration would accommodate the generator
terminal, the Boise Bench to East Boise Site 230 kV line terminal, and the Caldwell to East
Boise Site line terminal.
Post-transient Study Results
This Interconnection Feasibility Study Report is for Network Resource Interconnection Service
at 230 kV, for a 174/200 MW or 73/85 MW simple cycle gas turbine at the East Boise Site.
The studies evaluate system performance for all levels of production ITom 0 MW output, up to
its maximum rating for the summer season. For this study, there is no reason to believe the
smaller unit would create operational problems, ifthe larger unit did not. N-O and N-1 outage
performance for the existing system are recorded. For this alternative, the new generator
output was taken to its maximum summer rating of 174 MW and system conditions recorded
for both N-O and N-1 outages.
Existing System
The following one line diagram depicts the existing system with no outages.
BROWNLEE043 u
Existing System - No Outages
Figure 1
174 MW East Boise Generator Added
. The following one line diagram depicts the system with the East Boise Generator at full outputand with no outages.
BROWNLEE1.043 u
174 MW (ID East Boise Site - No Outages
Figure 2
'J'
, ./
Single Contingency Line Outage Performance
Four single contingency line outages (N-l) will be considered to evaluate system performance
following the generator addition. The following one line depicts system performance following
the loss of the Boise Bench to Locust 230 kV line, with the generator at 174 MW output.
BROWNLEE044 u
174 MW (lY East Boise Site - Boise Bench to Locust 230 kV Line Outage
Figure 3
For cowparison purposes, the following one-line depicts the existing system performance for
the sallie Boise Bench to Locust 230 kV line outage.
BROWNLEE044 u.
Existing System - Boise Bench to Locust 230 kV Line Outage
Figure 4
The following one line depicts system performance following the loss of the Brownlee to
Ontario 230 kV line, with the generator at 174 MW output.
BROWNLEE1.04 u
174 MW &J East Boise Site - Brownlee to Ontario 230 kV Line Outage
Figure 5
For comparison purposes, the following one-line depicts the existing system performance for
the same Brownlee to Ontario 230 kV line outage.
BROWNLEE1.044
Existing System - Brownlee to Ontario 230 kV Line Outage
Figure 6
The Brownlee to Ontario 230 kV line outage is critical in determining the timing of the next
major transmission system improvement project required for Treasure Valley load growth. For
the existing system with no generation at the East Boise Site, approximately 205 MW of
Nampa/Caldwell area load growth can be accommodated before major transmission
improvements are required. With 174 MW of generation at the East Boise Site, only about 185
MW ofload growth in the Nampa/Caldwell area can be accommodated before major
transmission system improvements are required. As a result, the utilization of the East Boise
Site will slightly accelerate the schedule for the next major transmission system improvement
to accommodate load growth in the Nampa/Caldwell area.
The following one line depicts system performance following the loss of the Boise Bench to
East Boise Site 230 kV line, with the generator at 174 MW output.
BROWNLEE1.043 u
174 MW ~ East Boise Site - Boise Bench to East Boise Site 230 kV Line Outage
Figure 7
The foUowing one line depicts system performance following the loss of the Nampa Tap to
East~kise Site 230 kV line, with the generator at 174 MW output.
BROWNLEE1. "J.
174 MW ~ East Boise Site - Nampa Tap to East Boise Site 230kV Line Outage
Figure 8
For comparison purposes, the following one-line depicts the existing system performance for
the same Boise Bench to Nampa Tap 230 kV line outage.
/,.'
BROWNLEE1.044 u
Existing System - Brownlee to Ontario 230 kV Line Outage
Figure 9
The 230 kV interconnection alternative exhibits acceptable performance for all conditions
studied. No single contingencies examined produced overloads or unacceptable voltage levels.
Unfortunately, utilizing the East Boise Site will accelerate the schedule for the next major
transmission system improvement to accommodate load growth in the NampaiCaldwell area.
Estimated Cost of Proposed Improvements
Cost estimates for the 230 kV interconnection alternative were generated for two categories of
costs:
Transmission Line Costs
Substation Costs
Approximate estimated costs for the East Boise Site interconnection alternative are:
$ 115 000
010 000
$ 3 125 000
- Transmission Line Costs
- Substation Costs
- Total estimated generator interconnection cost
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). No tax gross-up
is included in these estimates. These are cost estimates only and final charges to the customer
will be based on the actual construction costs incurred.
10.Short Circuit Study Results
Preliminary short circuit study results indicate five 138 kV circuit breakers at Boise Bench will
need to be replaced to be able to accommodate the increased fault duty. More detailed short
circuit analysis will be required to determine with certainty whether replacement of all five
breakers will be required. Additional short circuit studies will be required if either of these
generator interconnection projects proceed to a system impact study. If the additional short
circuit analysis studies still require breaker replacements, cost estimates will be developed at
that time.
11.Conclusions
The feasibility of interconnecting either a 174/200 MW or 73/85 MW simple cycle gas turbine at
the East Boise Site to Idaho Power 230 kV transmission system was studied. The 230
interconnection alternative evaluated was found to provide acceptable system performance for
either of the proposed generators. The estimated total cost ofthe transmission improvements
associated with the 230 kV interconnection alternative is approximately $3 Million.
, ,
APPENDIX A
1.0 Method of Study
The study methodology inserts the proposed generator up to the maximum requested output of
174 MW into the selected WECC power flow case and then, using the Power Wodd Simulator
powerflow program, examines the impacts ofthe 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 ofthe 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 flowing any N-l outage. Loading on the Midpoint 230
kV series capacitors should not exceed 135% of the continuous rating, immediately
flowing any N-l outage. These loadings levels of 115% on transmission lines and
transformers and 135% on Midpointseries capacitors correspond to IPCo 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.
.. " ,. '
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.
~,.",. -
T;5:;'
10-
LARGE GENERATOR INTERCONNECTION
FEASIBILITY STUDY REPORT
for the
230 KV INTERCONNECTION OPTION
EV ANDER ANDREWS PROJECT
for
Idaho Power Power Marketing, Interconnection Customer
for connection of
A 200 MW SIMPLE CYCLE GAS TURBINE PEAKING PROJECT
EV ANDER ANDREWS PROJECT
IDAHO POWER COMPANY, Transmission Provider
TRANSMISSION SYSTEM
FINAL REPORT
August 4, 2005
1.0
...
Introduction
Idaho Power Power Marketing has contracted with Idaho Power Company (IPC) to perform a
Large Generator Interconnection Feasibility Study for Network Resource Interconnection
Service at 230 kV for the integration of a new 200 MW simple cycle gas turbine peaking
project. The proposed location is the Evander Andrews Project near Mountain Home, Idaho.
This report documents the basis for and the results ofthis Feasibility Study. It describes the
proposed interconnection alternatives, the study cases used, outage scenarios assumed and
results of all work in the areas of concern.
Summary
The performance ofthree interconnection alternatives was evaluated to integrate a 200 MW
simple cycle gas turbine, located at Evander Andrews Project, into the Idaho Power System.
Alternative #3 is the recommended alternative.
Alternative #1:
Alternative #2:
Alternative #3:
Construct a radial 230 kV interconnection line, from a new 230 kV substation
at Evander Andrews, to the Midpoint-Boise Bench #3 transmission line.
Numerous N-l contingencies resulted in unacceptable overloads for this
alternative. The additional improvement of a 230/138 kV transformer at
Evander Andrews was evaluated in an unsuccessful attempt to achieve
acceptable performance under N-l outage conditions.
Construct two new 230 kV transmission lines from Bennett Mountain to
Evander Andrews and Evander Andrews to Rattlesnake. These lines would
complete a 230 kV loop from Rattlesnake to Bennett Mountain to Evander
Andrews and back to Rattlesnake. In addition, the Dram-Midpoint #1230 kV
line would be looped into Rattlesnake and rebuilt to support bundled 230 kV
conductors west of Rattlesnake. Additional transmission modifications were
also modeled at DRAM substation to make the "Old Midpoint to DRAM #1"
230 kV line bypass the DRAM Substation and terminate at Boise Bench.
230/138 kV transformer was modeled at Evander Andrews to improve system
performance under N-l conditions. Alternative #2 has one N-l outage that
produces an overload that exceeds 115% of continuous rating. In addition
three N-l contingencies still require curtailments for Alternative #2.
Alternative #2 is an unacceptable alternative due to the N-l outage that
produces an overload that exceeds 115%. Alternative #2 is anticipated to be
similar in cost to Alternative #3 , yet does not perform as well.
Rebuild a de-energized 132 kV transmission line to 230 kV construction
between Bennett Mountain and Mora Substations. This alternative utilizes the
406 line route which passes in the vicinity of Evander Andrews. The west end
of the 230 kV line is assum~d to terminate at a new 230 kV Mora Substation
which is folded into the Boise Bench-Caldwell 230 kV line. No 230/138 kV
transformer is modeled to tie the two Mora busses. A 230/138 kV transformer
was modeled at Evander Andrews to improve system performance under N-
conditions. Studies revealed the need to reconductor/rebuild the Evander
Andrews to Mountain Home Junction 138 kV line. With the previously
mentioned additions in-service, two N-l outages produce overloads above
equipment continuous ratings. One overload only requires a 2% reduction in
loading to fall to a level that can be sustained continuously. Opening another
lightly loaded line can mitigate the other overload. The estimated total cost
for this alternative is approximately $26 Million, with approximately $22
Million allocated Idaho Power Power Marketing for the generator
interconnection improvements and the remaining $4 Million allocated to
Idaho Power Delivery to correct existing operational concerns. Following the
execution of either a Large Generator Interconnection Agreement or a
Engineering & Procurement Agreement by Idaho Power Power Marketing,
Idaho Power Company estimates the time required to construct these facilities
is approximately 18-21 months.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). A cursory
attempt has been made in this study to characterize each transmission improvement as either
needed to integrate the proposed generator" or "needed to correct existing operational
concerns . 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 Request
A request was made to Idaho Power Co. by Idaho Power Power Marketing to study the
interconnection of a proposed 200 MW simple cycle gas turbine at the Evander Andrews
Project, near Mountain Home, Idaho, to Idaho Power s transmission system at the 230 kV level
for Network Resource Interconnection Service.
Scope of Interconnection Feasibility Study
The Interconnection Feasibility Study was done and prepared in accordance with the FERC
Order 2003-, Standard Large Generator Interconnection Procedures, to provide a preliminary
evaluation of the feasibility 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 Proposed Generating Project
Idaho Power Power Marketing proposes to connect a 200 MW simple cycle gas turbine to the
Idaho Power 230 kV transmission system, at the existing Evander Andrews Power Complex
1862 NW Mashburn RD., Mountain Home, ID 83647. ThemaximUIn generating capacity of
the proposed unit is estimated to be 200 MW for both summer and winter temperatures. The
equipment is described as being, a Siemens Westinghouse 501F Econopac. The proposed
commercial operation date is April 1 , 2007.
Description of Existing Transmission Facilities
At the Scoping Meeting for this Interconnection Request, it was agreed that the interconnection
voltage to be studied would be 230 kV. The existing generating units at Evander Andrews Power
Complex utilize the 138 kV transmission grid. No 230 kV transmission is present at Evander
Andrews at this time.
Evander Andrews has four 230 kV lines in relatively close proximity. Three ofthem run from the
Midpoint Substation(north of Twin Falls, ill) to the east Boise area. The closest is the Midpoint-
DRAM #1 line, which is approximately 4 miles Northeast of Evander Andrews. This line utilizes
single 715.5 MCM conductors and has a continuous rating of339 MY A. The Rattlesnake-Boise
Bench #2 line is approximately 5 miles Northeast ofEvander Andrews and utilizes a 2 conductor
bundle of715.5 MCM. This line has a continuous rating of677 MYA. The Midpoint-Boise
Bench #3 line is approximately 7 miles Northeast of Evander Andrews. This line has similar
conductors and the same rating as the Rattlesnake-Boise Bench #2 line. The fourth 230 kV line in
the area is the Rattlesnake-Bennett Mountain line. It is approximately 5 miles to the Southeast of
Evander Andrews. This line utilizes single 1272 MCM conductors and has a continuous rating of
478 MYA.
In addition to the three Midpoint to the east Boise area 230 kV lines previously mentioned, there
are two 138 kV circuits which can carry power from the Mountain Home area to the Boise Area.
They are:
Mountain Home Junction-Lucky Peak-Micron 138 kV Line
Mountain Home Junction-Evander Andrews-Strike-Swan Falls-Bowmont 138 kV
Line
Generators located in the Mountain Home 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 feasibility study will
model 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 ofthe'simplecyc1e gas turbine s 200 MW
output was inserted into a power flow case that would simulate committed (1100 MW) pre-
contingency flows on the Midpoint West transmission path.
In accordance with the Scoping Meeting for this Feasibility Study Request, three alternatives
were studied, all of which employed a 230 kV interconnection voltage.
Alternative #1 employed a radial 230 kV line to connect the generator to the Midpoint-Boise
Bench #3 transmission line. The line was modeled as being 7.7 miles in length and utilized
1272 MCM single conductor construction. An additional improvement of a 230/138 kV 200
MY A transformer(duplicate of the Midpoint unit) was explored at Evander Andrews to
improve the performance of this alternative.
Alternative #2 calls for the construction of two new 230 kV transmission lines from Bennett
Mountain to Evander Andrews, and Evander Andrews to Rattlesnake. These lines would
complete a 1272 MCM single conductor 230 kV loop from Rattlesnake to Bennett Mountain to
Evander Andrews and back to Rattlesnake. In addition, the Dram-Midpoint #1 230 kV line
would be looped into Rattlesnake and rebuilt to support a two conductor bundle of715.5 MCM
conductors west of Rattlesnake. Additional transmission modifications were also modeled
outside of DRAM substation to make the "Old Midpoint to DRAM #1" 230 kV line bypass
the DRAM Substation and terminate at Boise Bench. The combination of bundled conductors
and folding the #1 line into Rattlesnake Substation necessitated the change to avoid overloads
at DRAM associated with the loss ofthe DRAM to Boise Bench 230 kV line. A 230/138 kV
200 MY A transformer(duplicate of the Midpoint unit) was modeled at Evander Andrews to
improve system performance under N-l conditions.
Alternative #3 employed the rebuild of a de-energized 132 kV transmission line to 230 kV
bundled 795 MCM construction between Bennett Mountain and Mora Substations. This
alternative utilizes the 406 line route (originally was the Upper Salmon to Caldwell line) which
passes in the vicinity of Evander Andrews. The west end of this new 230 kV line is assumed
to terminate at a new 230 kV Mora Substation, which is folded into the Boise Bench-Caldwell
230 kV line. No 230/138 kV transformer is modeled to tie the two Mora busses. A 230/138
kV 200 MY A transformer(duplicate of the Midpoint unit) was modeled at Evander Andrews to
improve system performance under N-l conditions. Studies also revealed the need to
reconductor/rebuild the Evander Andrews to Mountain Home Junction 138 kV line, with this
alternative.
Post-transient Study Results
This Interconnection Feasibility Study Report is for Network Resource Interconnection Service
at 230 kV, for a 200 MW simple cycle gas turbine at the Evander Andrews Power Project.
System transfers across the Midpoint West cutplane are modeled at 1100 MW prior to the
proposed transmission improvements or the proposed generator 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 Evander Andrews and Bennett Mountain were
varied over their operating ranges as appropriate. N-O and N-l outage performance for the
existing system are recorded. As agreed in the Scoping Me~ting, three alternatives were
. ..
evaluated. For each alternative, the new generator s output was taken to its maximum level of
200 MW and system conditions recorded for both N-O and N-l outages.
/'~
Existing System
The following one line diagram depicts the existing system with no outages.
Mid oint West = 1100
Existing System - No Outages
Figure 1
For the existing system, seven N-l outages produce overloads that exceed the continuous
rating of elements ofthe transmission system. The N-l 's that produce overloads with the
existing system are included in Appendix B, Figures 9 - 15.
Alternative #1
The following one line diagram depicts the system with Alternative #1 added, full output of the
generator, and with no outages.
Mid oint West = 1063 MW
Alternative #1- No Outages
Figure 2
Alternative #1 has multiple N-l outages that produce overloads that exceed 115% of
continuous ratings. Some of the resulting overloads are reduced with the addition of the
Evander Andrews 230/138 kV transformer, and others are increased. The largest overloads are
produced by the Lockman Butte to Boise Bench #3 230 kV line outage. The following one
line depicts a 128 % loading on the Mountain Home Junction to Lucky Peak 138 kV line
without the Evander Andrews 230/138 kV transformer.
Mid oint West = 910 MW
Alternative #1 - Lockman Butte-Boise Bench #3 230 kV Outage
Without the Evander Andrews 230/138 kV Transformer
Figure 3
Adding the Evander Andrews 230/138 kV Transformer to the above outage, produces a 172%
loading on the Mountain Home Junction to Lucky Peak 138 kV line.
With the Evander Andrews 230/138 kV transformer in-service, only one other N-l outage
produces overloads that exceed 115% loading and are also greater than existing system
overloads for the same N-l. That N-l is loss of the Rattlesnake to Boise Bench #2230 kV
line.
Without the Evander Andrews 230/138 kV transformer in-service, four other N-l outages
produces overloads that exceed 115% loading and are also greater than existing system
overloads for the same N -1. They are:
Rattlesnake - Boise Bench #2 230 kV Line outage
Midpoint - Rattlesnake #2 230 kV line outage
Evander Andrews - Strike 138 kV line outage
Strike - Bowmont 138 kV line outage
Several other N-l outages result in overloads below 115% that would require curtailments
following the outage to get down to loadings that can be sustained continuously. In some
cases, lowering the output ofthe proposed generator helps to lower the overload; but in 'one
case (Lucky Peak - Micron 138 kV line outage), the overload increases as the proposed
generators output is lowered.
Alternative #1 is an unacceptable alternative, due to two N-l outages which produce overloads
that exceed 115% of continuous ratings. The Network Rating for Alternative #1 is 0 MW.
Alternative #2
The following one line diagram depicts the system with Alternative #2 added, full output of the
generator, and with no outages.
Mid Dint West = 1083 MW
Alternative #2 - No Outages
Figure 4
The addition ofthe Evander Andrews 230/138 kV transformer improves the performance of
Alternative #2 for most N-l outages, but not all. Alternative #2 has one N-l outage that
produces an overload that exceeds 115% of continuous rating and is also greater than existing
system overloads for the same N-l. The outage is the Rattlesnake to Boise Bench #1 230 kV
line. The following one line diagram depicts this outage at 200 MW of output on the proposed
unit.
BOISEBCHB1pu
Mid ointWest = 1028 MW
Alternative #2 - Rattlesnake to Boise Bench #1
Line Outage ~ 200MW of Output
Figure 5
The output ofthe new unit needs to be restricted to approximately 163 MW to limit the
overload to 115% on the Mountain Home Junction to Lucky Peak 138 kV line for this N-
outage. For this reason, this alternative does not provide adequate performance for a Network
Resource Rating of 200 MW. The following one line diagram depicts this condition.
Mid olnt West = 1036 MW
Alternative #2 - Rattlesnake to Boise Bench
Line Outage (ID 163 MW of Output
Figure 6
Curtailments are required for all three N-l outages ofthe 230 kV lines from the Mountain
Home area into Boise Bench. Loss of the Rattlesnake to Boise Bench #1 or #2 lines require
the proposed unit's output to be lowered to approximately 67 MW to reduce overloads
100% of the continuous rating or a level that the overload is no worse than it is for the existing
system with the same N-l outage. These contingencies and resulting system performance
determines the Network Resource Rating to be 67 MW for Alternative #2. The loss ofthe
Midpoint to Boise Bench #3 230 kV line requires a curtailment to 10wer a 118% overload of
the series capacitors on the Midpoint to Rattlesnake #2 230 kV line. This alternative does not
permit the overload to be reduced by lowering the output of the proposed unit. Lowering the
output of proposed unit will increase the overload on the series capacitors in question. Other
generators would have to be curtailed to solve this overload scenario.
Alternative #2 is an unacceptable alternative for the proposed unit at 200 MW for Network
Resource Interconnection Service, due to the N-l outage that produces overloads that exceed
115% of continuous ratings. The Network Resource Rating for Alternative #2 is 67 MW.
Alternative #2 is also believed to very similar in cost to AlternatIve #3 , yet it's performance is
much more problematic than Alternative #3.
10-
'-
Alternative #3
The following one line diagram depicts the system with Alternative #3 added, full output ofthe
generator, and with no outages.
Mid oint West = 1103 MW
Alternative #3 - No Outages
Figure 7
The addition ofthe Evander Andrews 230/138 kV transformer improves the performance of
Alternative #3, for all but one of the N-l outages. Alternative #3 has no N-l outages that
produce overloads that exceed 115% of continuous ratings.
Two N-l outages result in overloads below 115% and at a level that the overload is greater
than it is for the existing system with the same N-l outage. The loss of the Midpoint to Boise
Bench #3 230 kV line results in a 112% loading on the series capacitor of the Midpoint to
Rattlesnake #2230 kV line. This series capacitor is capable of 110% loading continuously, so
a 2% reduction in flow is required. Lowering generation in the Mountain Home area results in
increased flow on the series capacitor bank, so transfers across the Midpoint West cutplane
will need to be reduced to correct this overload, as well as prepare for the next contingency.
The second N-l outage that results in an overload below 115%, is the Evander Andrews to
Mora 230 kV line. This N-l outage results in a 106% loading on the Mountain Home Junction
to Lucky Peak 138 kV line. This overload can be managed by opening the Evander Andrews
to Mountain Home Junction 138 kV line.
Alternative #3 changes the characteristics of the interconnected network enough to create the
need to reconductor/rebuild the Evander Andrews to Mountain Home Junction 138 kV line.
For the N-l outage of the Lucky Peak to Micron 138 kV line, the Evander Andrews to
Mountain Home Junction 138 kV line loads to 109% of its rating with all the peaking
generation in the Mountain Home area at full output. If the output ofthe peaking generation in
the Mountain Home area is reduced, the overload increases in magnitude. The following one
11-
line diagram depicts the Lucky Peak to Micron 138 kV line outage with all the Mountain
Home area peaking generation offline.
Mid oint West = 1157
Alternative #3 - Luck Peak to Micron 138 kV Line Outage
With Peakers Off-line
Figure 8
Alternative #3 is the recommended alternative for the proposed unit at 200 MW for Network
Resource Interconnection Service.
Cost Allocation of Proposed Improvements
Alternative #3 contains the following five construction components:
Bennett Mountain to Evander Andrews 230 kV line and terminals
Evander Andrews to Mora 230 kV line and terminals
230 kV generator connection terminal at Evander Andrews
Evander Andrews 230/138 kV transformer and terminals
Reconductor/rebuild of the Evander Andrews to Mountain Home Junction 138
kV line
A cursory attempt has been made in this study to characterize each transmission improvement
as either "needed to integrate the proposed generator" or "needed to correct existing
operational concerns . The costs associated with those improvements believed to be "needed
to integrate the proposed generator" are allocated to the generator interconnection. The costs
associated with those improvements believed to be "needed to correct existing operational
concerns " are allocated to IPCo Delivery.
12-
Approximate estimated costs allocated to the generator interconnection are:
$ 4.1 Million - Bennett Mountain to Evander Andrews 230 kV line and terminals
$17.3 Million - Evander Andrews to Mora 230 kV line and terminals
$ 0.4 Million - 230 kV generator connection terminal at Evander Andrews
$21.8 Million - Total estimated generator interconnection cost
Approximate estimated costs allocated to the IPCo Delivery are:
$2.1 Million - Evander Andrews 230/138 kV transformer and terminals
$1.7 Million - Evander Andrews to Mountain Home Junction 138 kV line rebuild
$3.8 Million - Total estimated allocation to IPCo Delivery
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.
10.Short Circuit Study Results
Preliminary short circuit study results indicate the surrounding circuit breakers are believed to
be able to accommodate the increased fault duty. No circuit breaker replacements are
anticipated at this time.
11.Conclusions
The feasibility of interconnecting a 200 MW simple cycle gas turbine at Evander Andrews Power
Complex to Idaho Power s 230 kV transmission system was studied. Three interconnection
alternatives were evaluated. Both Alternatives #1 & #2 were found to be unacceptable alternatives
due to transmission system loadings that exceeded 115% for N-l outages. Alternative #3 was
found to be an acceptable interconnection alternative. While Alternative #3 does require minimal
redispatch/transmission switching for two N-l outages, they are minor in nature and deemed
acceptable for this feasibility study. The estimated total cost of the transmission improvements
associated with Alternative #3 is approximately $26 Million. At this time it is believed that
approximately $22 Million of these estimated costs should be allocated to the generator
interconnection.
13-
APPENDIX A
1.0 Method of Study
The study methodology inserts the proposed generator up to the maximum requested output of
200 MW into the selected WECC power flow case and then, using the PowerWorld 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
~cenarios. 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 flowing any N-l outage. Loading on the Midpoint 230
kV series capacitors should not exceed 135% of the continuous rating, immediately
flowing any N-l outage. These loadings levels of 115% on transmission lines and
transformers and 135% on Midpoint series capacitors correspond to IPCo 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 ofthe 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
14-
decay or even collapse under the worst conditions. Idaho Power designs its system to
integrate Network Resources at full capability during specified outage conditions.
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 ofthis study. Future transmission changes may, however, affect
current facility ratings used in the study.
15-
. .
APPENDIX B
1.0 l Outages That Produce Overloads On The Existing System
The following one line diagrams depict system performance following the seven N-l outages
that produce overloads which exceed the continuous rating of facilities. Figure 1 on page 5
depicts the operation of the existing system with no outages. The combination of heavy hydro
and peaker generation in the Mountain Home area, and 1100 MW east to west transfers on
Midpoint West, results in the Mountain Home Junction to Lucky Peak and Lucky Peak to
Micron 138 kV lines being loaded to 98% & 99% respectively, prior to any outages.
Mid oint West = 981
Existing System - Midpoint to Boise Bench #3 230 kV Outage
Figure 9
16-
Mid oint West = 951
Existing System - Rattlesnake to Boise Bench #2 230 kV Outage
Figure 10
Mid oint West = 997
Existing System - Midpoint to Rattlesnake #2 230 kV Outage
Figure 11
17-
, .
MId oint West = 1053
Existing System - Midpoint to DRAM #1 230 kV Outage
Figure 12
Mid oint West = 1085
Existing System - CJ Strike to Bowmont 138 kV Outage
Figure 13
18-
Mid oint West = 1072
Existing System - Lucky Peak to Micron 138 kV Outage
Figure 14
Midpoint West = 1094
Existing System - Evander Andrews to CJ Strike 138 kV Outage
Figure 15
19-
LARGE GENERATOR INTERCONNECTION
FEASIBILITY STUDY REPORT
for the
230 KV INTERCONNECTION OPTION
EV ANDER ANDREWS PROJECT
for
Idaho Power Company - Power Supply, Interconnection Customer
for connection of
A 100/124 MW SIMPLE CYCLE GAS TURBINE PEAKING PROJECT
EV ANDER ANDREWS PROJECT
IDAHO POWER COMPANY, Transmission Provider
TRANSMISSION SYSTEM
FINAL REPORT
September 23, 2005
Introduction
Idaho Power Company - Power Supply has contracted with Idaho Power Company (IPC) to
perform a Large Generator Interconnection Feasibility Study for Network Resource
Interconnection Service at 230 kV for the integration of a new 100/124 MW simple cycle gas
turbine peaking project. The proposed location is the Evander Andrews Project near Mountain
Home, Idaho.
This report documents the basis for and the results of this Feasibility Study. It describes the
proposed interconnection alternatives , the study cases used, outage scenarios assumed and
results of all work in the areas of concern.
Summary
The performance of three interconnection alternatives was evaluated to integrate a simple cycle
gas turbine with a summer rating of 100 MW and a winter rating of 124 MW, located at
Evander Andrews Project, into the Idaho Power System. Alternative #3 is the recommended
alternative.
Alternative #1:
Alternative #2:
Construct a radial 230 kV interconnection line, from a new 230 kV substation
at Evander Andrews, to the Midpoint-Boise Bench #3 transmission line.
Several N-l contingencies resulted in unacceptable overloads for this
alternative. The additional improvement of a 230/138 kV transformer at
Evander Andrews was evaluated in an unsuccessful attempt to achieve
acceptable performance under N-l outage conditions.
Construct two new 230 kV transmission lines from Bennett Mountain to
Evander Andrews and Evander Andrews to Rattlesnake. These lines would
complete a 230 kV loop from Rattlesnake to Bennett Mountain to Evander
Andrews and back to Rattlesnake. In addition, the Dram-Midpoint #1 230 kV
line would be looped into Rattlesnake and rebuilt to support bundled 230 kV
conductors west of Rattlesnake. Additional transmission modifications were
also modeled at DRAM substation to make the "Old Midpoint to DRAM #1"
230 kV line bypass the DRAM Substation and terminate at Boise Bench.
230/138 kV transformer was modeled at Evander Andrews to improve system
performance under N-l conditions. Alternative #2 has no N-l outages that
produce overloads that exceeds 115% of continuous rating and are also greater
than existing system overloads for the same N-l. Alternative #2 will require
curtailments of the proposed generators output following multiple N-
outages. The Network Resource Rating for Alternative #2 is 67 MW.
Alternative #2 is anticipated to be similar in cost to Alternative #3 , yet does
not perform as well.
Alternative #3: Rebuild a de-energized 132 kV transmission line to 230 kV construction
. between Bennett Mountain and Mora Substations. This alternative utilizes the
406 line route which passes in the vicinity of Evander Andrews. The west end
of the 230 kV line is assumed to terminate at a new 230 kV Mora Substation
which is folded into the Boise Bench-Caldwell 230 kV line. No 230/138 kV
transformer is modeled to tie the two Mora busses. A 230/138 kV transformer
was modeled at Evander Andrews to improve system performance under N-
conditions. Studies revealed the need to reconductor/rebuild the Evander
Andrews to Mountain Home Junction 138 kV line. With the previously
mentioned additions in-service, one N-l outage produces an overload above
equipment continuous ratings. This overload only requires a 6% reduction in
loading to fall to a level that can be sustained continuously. The estimated
total cost for this alternative is approximately $26 Million, with approximately
$22 Million allocated Idaho Power Company - Power Supply for the generator
interconnection improvements and the remaining $4 Million allocated to
Idaho Power Delivery to correct existing operational concerns. Following the
execution of either a Large Generator Interconnection Agreement or a
Engineering & Procurement Agreement by Idaho Power Company - Power
Supply, Idaho Power Company estimates the time required to construct these
facilities is approximately 18-21 months.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). A cursory
attempt has been made in this study to characterize each transmission improvement as either
needed to integrate the proposed generator" or "needed to correct existing operational
concerns . 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 Request
A request was made to Idaho Power Co. by Idaho Power Company - Power Supply to study
the interconnection of a proposed 100/124 MW simple cycle gas turbine at the Evander
Andrews Project, near Mountain Home, Idaho, to Idaho Power s transmission system at the
230 kV level for Network Resource Interconnection Service.
Scope of Interconnection Feasibility Study
The Interconnection Feasibility Study was done and prepared in accordance with the FERC
Order 2003-, Standard Large Generator Interconnection Procedures, to provide a preliminary
evaluation of the feasibility 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 Proposed Generating Project
Idaho Power Company - Power Supply proposes to connect a 100/124 MW simple cycle gas
turbine to the Idaho Power 230 kV transmission system, at the existing Evander Andrews
Power Complex, 1862 NW Mashburn RD., Mountain Home, ill 83647. The maximum
generating capacity of the proposed unit is estimated to be 100 MW for the summer and
124 MW for winter temperatures. The equipment is described as being, a Siemens SSC6-
3000E CT ECNO Pack. The proposed commercial operation date is April 1 , 2007.
Description of Existing Transmission Facilities
At the Scoping Meeting for this Interconnection Request, it was agreed that the interconnection
voltage to be studied would be 230 kV. The existing generating units at Evander Andrews Power
Complex utilize the 138 kV transmission grid. No 230 kV transmission is present at Evander
Andrews at this time.
Evander Andrews has four 230 kV lines in relatively close proximity. Three of them run from the
Midpoint Substation(north of Twin Falls, ill) to the east Boise area. The closest is the Midpoint-
DRAM #1 line, which is approximately 4 miles Northeast of Evander Andrews. This line utilizes
single 715.5 MCM conductors and has a continuous rating of 339 MV A. The Rattlesnake-Boise
Bench #2 line is approximately 5 miles Northeast of Evander Andrews and utilizes a 2 conductor
bundle of 715.5 MCM. This line has a continuous rating of 677 MV A. The Midpoint-Boise
Bench #3 line is approximately 7 miles Northeast of Evander Andrews. This line has similar
conductors and the same rating as the Rattlesnake-Boise Bench #2 line. The fourth 230 kV line in
the area is the Rattlesnake-Bennett Mountain line. It is approximately 5 miles to the Southeast of
Evander Andrews. This line utilizes single 1272 MCM conductors and has a continuous rating of
478 MVA.
In addition to the three Midpoint to the east Boise area 230 kV lines previously mentioned, there
are two 138 kV circuits which can carry power from the Mountain Home area to the Boise Area.
They are:
Mountain Home Junction-Lucky Peak-Micron 138 kV Line
Mountain Home Junction-Evander Andrews-Strike-Swan Falls-Bowmont 138 kV
Line
Generators located in the Mountain Home 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 feasibility study will
model 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 #2 230 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 simple cycle gas turbine s 100 MW
summer output was inserted into a power flow case that would simulate committed (1100 MW)
pre-contingency flows on the Midpoint West transmission path.
In accordance with the Scoping Meeting for this Feasibility Study Request, three alternatives
were studied, all of which employed a 230 kV interconnection voltage.
Alternative #1 employed a radial 230 kV line to connect the generator to the Midpoint-Boise
Bench #3 transmission line. The line was modeled as being 7.7 miles in length and utilized
1272 MCM single conductor construction. An additional improvement of a 230/138 kV 200
MV A transformer( duplicate of the Midpoint unit) was explored at Evander Andrews to
improve the performance of this alternative.
Alternative #2 calls for the construction of two new 230 kV transmission lines from Bennett
Mountain to Evander Andrews, and Evander Andrews to Rattlesnake. These lines would
complete a 1272 MCM single conductor 230 kV loop from Rattlesnake to Bennett Mountain to
Evander Andrews and back to Rattlesnake. In addition, the Dram-Midpoint #1230 kV line
would be looped into Rattlesnake and rebuilt to support a two conductor bundle of 715.5 MCM
conductors west of Rattlesnake. Additional transmission modifications were also modeled
outside of DRAM substation to make the "Old Midpoint to DRAM #1" 230 kV line bypass
the DRAM Substation and terminate at Boise Bench. The combination of bundled conductors
and folding the #1 line into Rattlesnake Substation necessitated the change to avoid overloads
at DRAM associated with the loss of the DRAM to Boise Bench 230 kV line. A 230/138 kV
200 MV A transformer(duplicate of the Midpoint unit) was modeled at Evander Andrews to
improve system performance under N-l conditions.
Alternative #3 employed the rebuild of a de-energized 132 kV transmission line to 230 kV
bundled 795 MCM construction between Bennett Mountain and Mora Substations. This
alternative utilizes the 406 line route (originally was the Upper Salmon to Caldwell line) which
passes in the vicinity of Evander Andrews. The west end of this new 230 kV line is assumed
to terminate at a new 230 kV Mora Substation, which is folded into the Boise Bench-Caldwell
230 kV line. No 230/138 kV transformer is modeled to tie the two Mora busses. A 230/138
k V 200 MV A transformer( duplicate of the Midpoint unit) was modeled at Evander Andrews to
improve system performance under N-l conditions. Studies also revealed the need to
reconductor/rebuild the Evander Andrews to Mountain Home Junction 138 kV line, with this
alternative.
Post-transient Study Results
This Interconnection Feasibility Study Report is for Network Resource Interconnection Service
at 230 kV, for a 100/124 MW simple cycle gas turbine at the Evander Andrews Power Project.
System transfers across the Midpoint West cutplane are modeled at 1100 MW prior to the
proposed transmission improvements or the proposed generator 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 Evander Andrews and Bennett Mountain were
varied over their operating ranges as appropriate. N-O and N-l outage performance for the
existing system are recorded. As agreed in the Scoping Meeting, three alternatives were
evaluated. For each alternative, the new generator s output was taken to its summer
temperature maximum level of 100 MW and system conditions recorded for both N-O and N-
outages.
Existine: System
The following one line diagram depicts the existing system with no outages.
MldDolnt West = 1100 MW
Existing System - No Outages
Figure 1
For the existing system, seven N-l outages produce overloads that exceed the continuous
rating of elements of the transmission system. The N-l' s that produce overloads with the
existing system are included in Appendix B , Figures 7 - 13.
Alternative #1
The following one line diagram depicts the system with Alternative #1 added, full summer
output of the generator, and with no outages.
Mid oint West = 1080
Alternative #1 - No Outages
Figure 2
Alternative #1 has multiple N-l outages that produce overloads that exceed 115% of
continuous ratings. Some of the resulting overloads are reduced with the addition of the
Evander Andrews 230/138 kV transformer, and others are increased.
The largest overloads are produced by the Lockman Butte to Boise Bench #3 230 kV line
outage. The following one line depicts a 124 % loading on the Mountain Home Junction to
Lucky Peak 138 kV line, without the Evander Andrews 230/138 kV transformer.
DNPRCT!
IR0J) 1O0MWcr 11M",
Mid oint West = 946 MW
Alternative #1- Lockman Butte-Boise Bench #3230 kV Outage
Without the Evander Andrews 230/138 kV Transformer
Figure 3
Adding the Evander Andrews 230/138 kV Transformer to the above outage, produces a 158%
loading on the Mountain Home Junction to Lucky Peak 138 k V line.
With the Evander Andrews 230/138 kV transformer in-service, there are no other N-l outages
that produce overloads that exceed 115% loading.
Without the Evander Andrews 230/138 kV transformer in-service, four other N-l outages
produces overloads that exceed 115% loading and are also greater than existing system
overloads for the same N-l. They are:
Rattlesnake - Boise Bench #2 230 kV Line outage
Midpoint - Rattlesnake #2 230 kV line outage
Evander Andrews - Strike 138 kV line outage
Strike - Bowmont 138 kV line outage
Several other N-l outages result in overloads below 115% that would require curtailments
following the outage to get down to loadings that can be sustained continuously. In some
cases , lowering the output of the proposed generator helps to lower the overload, but in one
case (Lucky Peak - Micron 138 kV line outage), the overload increases as the proposed
generators output is lowered.
Alternative #1 is an unacceptable alternative, due to the N-l outage that produces an overload
that exceeds 115% of continuous ratings. The Network Rating for Alternative #1 is 0 MW.
Alternative #2
The following one line diagram depicts the system with Alternative #2 added, full output of the
generator, and with no outages.
Alternative #2 - No Outages
Figure 4
The addition of the Evander Andrews 230/138 kV transformer improves the performance of
Alternative #2 for most N-l outages , but not all. Without the Evander Andrews 230/138 kV
transformer, Alternative #2 has four N-l outages that produce overloads that exceeds 115% of
continuous rating, however, all the overloads are less than existing system overloads for the
same N-l and as a result are judged to provide acceptable performance. With the Evander
Andrews 230/138 kV transformer, Alternative #2 has no N-l outages that produce overloads
that' exceed 115 % of continuous rating.
Curtailments are required for all three N-l outages of the 230 kV lines from the Mountain
Home area into Boise Bench. Loss of the Rattlesnake to Boise Bench #1 or #2 lines require
the proposed unit's output to be lowered to approximately 67 MW to reduce overloads to
100% of the continuous rating or a level that the overload is no worse than it is for the existing
system with the same N-l outage. These contingencies and resulting system performance
determines the Network Resource Rating to be 67 MW for Alternative #2. The loss of the
Midpoint to Boise Bench #3230 kV line requires a curtailment to lower a 118% overload of
the series capacitors on the Midpoint to Rattlesnake #2 230 kV line. This alternative does not
permit the overload to be reduced by lowering the output of the proposed unit. Lowering the
output of proposed unit will increase the overload on the series capacitors in question. Other
generators would have to be curtailed to solve this overload scenario.
Alternative #2 will require curtailments of the proposed generators output following multiple
loutages. As a result, Alternative #2 does not provide acceptable performance for Network
Resource Interconnection Service for the proposed unit at full output. The Network Resource
Rating for Alternative #2 is 67 MW. Alternative #2 is also believed to very similar in cost to
Alternative #3 , yet it's performance is much more problematic than Alternative #3.
Alternative #3
The following one line diagram depicts the system with Alternative #3 added, full output of the
generator, and with no outages.
Mld olnt West = 1118 MW
Alternative #3 - No Outages
Figure 5
The addition of the Evander Andrews 230/138 kV transformer improves the performance of
Alternative #3 , for all but one of the N-l outages. With the Evander Andrews 230/138 kV
transformer in service, alternative #3 has no N-l outages that produce overloads that exceed
115% of continuous ratings.
One N-l outage results in an overload below 115% and at a level that the overload is greater
than it is for the existing system with the same N-l outage. The loss of the Midpoint to Boise
Bench #3 230 kV line results in a 116% loading on the series capacitor of the Midpoint to
Rattlesnake #2 230 kV line. This series capacitor is capable of 110% loading continuously, so
a 6% reduction in flow is required. Lowering generation in the Mountain Home area results in
increased flow on the series capacitor bank, so transfers across the Midpoint West cutplane
will need to be reduced to correct this overload, as well as prepare for the next contingency.
Alternative #3 changes the characteristics of the interconnected network enough to create the
need to reconductor/rebuild the Evander Andrews to Mountain Home Junction 138 kV line.
For the N -1 outage of the Lucky Peak to Micron 138 k V line, the Evander Andrews to
Mountain Home Junction 138 kV line loads to 113% of its rating with all the peaking
generation in the Mountain Home area at full output. If the output of the peaking generation in
the Mountain Home area is reduced, the overload increases in magnitude. The following one
line diagram depicts the Lucky Peak to Micron 138 kV line outage with all the Mountain
Home area peaking generation offline.
Mld olnt West.. 1157
Alternative #3 - Luck Peak to Micron 138 kV Line Outage
With Peakers Off-line
Figure 6
Alternative #3 is the recommended alternative for the proposed unit at 100/124 MW for
Network Resource Interconnection Service.
Cost Allocation of Proposed Improvements
Alternative #3 contains the following five construction components:
Bennett Mountain to Evander Andrews 230 kV line and terminals
Evander Andrews to Mora 230 kV line and terminals
230 kV generator connection terminal at Evander Andrews
Evander Andrews 230/138 kV transformer and terminals
Reconductorlrebuild of the Evander Andrews to Mountain Home Junction 138
kV line
A cursory attempt has been made in this study to characterize each transmission improvement
as either "needed to integrate the proposed generator" or "needed to correct existing
operational concerns . The costs associated with those improvements believed to be "needed
to integrate the proposed generator" are allocated to the generator interconnection. The costs
10-
associated with those improvements believed to be "needed to correct existing operational
concerns " are allocated to IPCo Delivery.
Approximate estimated costs allocated to the generator interconnection are:
$ 4.1 Million - Bennett Mountain to Evander Andrews 230 kV line and terminals
$17.3 Million - Evander Andrews to Mora 230 kV line and terminals
$ 0.4 Million - 230 kV generator connection terminal at Evander Andrews
$21.8 Million - Total estimated generator interconnection cost
Approximate estimated costs allocated to the IPCo Delivery are:
$2.1 Million - Evander Andrews 230/138 kV transformer and terminals
$1.7 Million - Evander Andrews to Mountain Home Junction 138 kV line rebuild
$3.8 Million - Total estimated allocation to IPCo Delivery
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.
10.Short Circuit Study Results
Preliminary short circuit study results indicate the surrounding circuit breakers are believed to
be able to accommodate the increased fault duty. No circuit breaker replacements are
anticipated at this time.
11.Conclusions
The feasibility of interconnecting a 100/124 MW simple cycle gas turbine at Evander Andrews
Power Complex to Idaho Power s 230 kV transmission system was studied. Three interconnection
alternatives were evaluated. Alternative #1 was found to be an unacceptable alternative due to
transmission system loadings that exceeded 115% for N-l outages. Alternative #2 did not provide
acceptable performance for Network Resource Interconnection Service for the proposed unit at full
output. The Network Resource Rating for Alternative #2 is 67 MW. Alternative #3 was found to
be an acceptable interconnection alternative. While Alternative #3 does require minimal
redispatchltransmission switching for one N-l outage, it is minor in nature and deemed acceptable
for this feasibility study. The estimated total cost of the transmission improvements associated with
Alternative #3 is approximately $26 Million. At this time it is believed that approximately $22
Million of these estimated costs should be allocated to the generator interconnection.
11-
APPENDIX A
Method of Study
The study methodology inserts the proposed generator up to the maximum requested output of
100 MW into the selected WECC power flow case and then, using the PowerWorld 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 flowing any N-l outage. Loading on the Midpoint 230
kV series capacitors should not exceed 135% of the continuous rating, immediately
flowing any N-l outage. These loadings levels of 115% on transmission lines and
transformers and 135% on Midpoint series capacitors correspond to IPCo 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
12-
decay or even collapse under the worst conditions. Idaho Power designs its system to
integrate Network Resources at full capability during specified outage conditions.
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.
13-
APPENDIX B
1 Outages That Produce Overloads On The Existing System
The following one line diagrams depict system performance following the seven N-l outages
that produce overloads which exceed the continuous rating of facilities. Figure 1 on page 5
depicts the operation of the existing system with no outages. The combination of heavy hydro
and peaker generation in the Mountain Home area, and 1100 MW east to west transfers on
Midpoint West, results in the Mountain Home Junction to Lucky Peak and Lucky Peak to
Micron 138 kV lines being loaded to 98% & 99% respectively, prior to any outages.
Midpoint West II 981
Existing System - Midpoint to Boise Bench #3230 kV Outage
Figure 7
14-
MldDolnt West = 951
Existing System - Rattlesnake to Boise Bench #2 230 kV Outage
Figure 8
Mld olnt West = 997
Existing System - Midpoint to Rattlesnake #2230 kV Outage
Figure 9
15-
Midpoint West = 1053
Existing System - Midpoint to DRAM #1 230 k V Outage
Figure 10
Mid oint West = 1085
Existing System - CJ Strike to Bowmont 138 kV Outage
Figure 11
16-
MldDolnt West = 1072
Existing System - Lucky Peak to Micron 138 kV Outage
Figure 12
Mld olnt West = 1094
Existing System - Evander Andrews to CJ Strike 138 kV Outage
Figure 13
17-
LARGE GENERATOR INTERCONNECTION
FEASIBILITY STUDY REPORT
for the
230 KV INTERCONNECTION OPTION
EV ANDER ANDREWS PROJECT
for
Idaho Power Company - Power Supply, Interconnection Customer
for connection of
A 91/100 MW SIMPLE CYCLE GAS TURBINE PEAKING PROJECT
EV ANDER ANDREWS PROJECT
IDAHO POWER COMPANY, Transmission Provider
TRANSMISSION SYSTEM
FINAL REPORT
September 23, 2005
1.0 Introduction
Idaho Power Company - Power Supply has contracted with Idaho Power Company (IPC) to
perform a Large Generator Interconnection Feasibility Study for Network Resource
Interconnection Service at 230 kV for the integration of a new 91/100 MW simple cycle gas
turbine peaking proj ect. The proposed location is the Evander Andrews Proj ect near Mountain
Home, Idaho.
This report documents the basis for and the results ofthis Feasibility Study. It describes the
proposed interconnection alternatives, the study cases used, outage scenarios assumed and
results of all work in the areas of concern.
Summary
The performance of three interconnection alternatives was evaluated to integrate a simple cycle
gas turbine with a summer rating of91 MW and a winter rating of 100 MW, located at
Evander Andrews Project, into the Idaho Power System. Alternative #3 is the recommended
alternative.
Alternative #1:
Alternative #2:
Alternative #3:
Construct a radial 230 kV interconnection line, from a new 230 kV substation
at Evander Andrews, to the Midpoint-Boise Bench #3 transmission line.
Several N-l contingencies resulted in unacceptable overloads for this
alternative. The additional improvement of a 230/138 kV transformer at
Evander Andrews was evaluated in an unsuccessful attempt to achieve
acceptable performance under N-l outage conditions.
Construct two new 230 kV transmission lines from Bennett Mountain to
Evander Andrews and Evander Andrews to Rattlesnake. These lines would
complete a 230 kV loop from Rattlesnake to Bennett Mountain to Evander
Andrews and back to Rattlesnake. In addition, the Dram-Midpoint #1 230 kV
line would be looped into Rattlesnake and rebuilt to support bundled 230 kV
conductors west of Rattlesnake. Additional transmission modifications were
also modeled at DRAM substation to make the "Old Midpoint to DRAM #1"
230 kV line bypass the DRAM Substation and terminate at Boise Bench.
230/138 kV transformer was modeled at Evander Andrews to improve system
performance under N-l conditions. Alternative #2 has no N-l outages that
produce overloads that exceeds 115% of continuous rating and are also greater
than existing system overloads for the same N-l. Alternative #2 will require
curtailments of the proposed generators output following multiple N-
outages. The Network Resource Rating for Alternative #2 is 67 MW.
Alternative #2 is anticipated to be similar in cost to Alternative #3, yet does
not perform as well.
Rebuild a de-energized 132 kV transmissionline to 230 kV construction
between Bennett Mountain and Mora Substations. This alternative utilizes the
406 line route which passes in the vicinity of Evander Andrews. The west end
of the 230 kV line is assumed to terminate at a new 230 kV Mora Substation
--'
which is folded into the Boise Bench-Caldwell 230 kV line. No 230/138 kV
transformer is modeled to tie the two Mora busses. A 230/138 kV transformer
was modeled at Evander Andrews to improve system performance under N-
conditions. Studies revealed the need to reconductor/rebuild the Evander
Andrews to Mountain Home Junction 138 kV line. With the previously
mentioned additions in-service, one N-l outage produces an overload above
equipment continuous ratings. This overload only requires a 6% reduction in
loading to fall to a level that can be sustained continuously. The estimated
total cost for this alternative is approximately $26 Million, with approximately
$22 Million allocated Idaho Power Company - Power Supply for the generator
interconnection improvements and the remaining $4 Million allocated to
Idaho Power Delivery to correct existing operational concerns. Following the
execution of either a Large Generator Interconnection Agreement or a
Engineering & Procurement Agreement by Idaho Power Company - Power
Supply, Idaho Power Company estimates the time required to construct these
facilities is approximately 18-21 months.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). A cursory
attempt has been made in this study to characterize each transmission improvement as either
needed to integrate the proposed generator" or "needed to correct existing operational
concerns . 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 Request
A req4est was made to Idaho Power Co. by Idaho Power Company - Power Supply to study
the interconnection of a proposed 91/100 MW simple cycle gas turbine at the Evander
Andrews Project, near Mountain Home, Idaho, to Idaho Power s transmission system at the
230 kV level for Network Resource Interconnection Service.
Scope of Interconnection Feasibility Study
The Interconnection Feasibility Study was done and prepared in accordance with the FERC
Order 2003-, Standard Large Generator Interconnection Procedures, to provide a preliminary
evaluation ofthe feasibility ofthe interconnection ofthe proposed large generating project to
the Idaho Power transmission system. This study will only be concerned with the capabilities
ofthe Idaho Power system to manage this new resource within the study area of the proposed
interconnection.
Description of Proposed Generating Project
Idaho Power Company - Power Supply prop,oses to connect a 91/100 MW simple cycle gas
turbine to the Idaho Power 230 kV transmission system, at the existing Evander Andrews
Power Complex, 1862 NW Mashburn RD., Mountain Home, ill 83647. The maximum
generating capacity of the proposed unit is estimated to be 91 MW for the summer and
100 MW for winter temperatures. The equipment is described as being, 2 GE LM 6000
Packages, or a GE7F A, or a GE LMS 1 00 Package. The proposed commercial operation date is
April 1 , 2007.
Description of Existing Transmission Facilities
At the Scoping Meeting for this Interconnection Request, it was agreed that the interconnection
voltage to be studied would be 230 kV. The existing generating units at Evander Andrews Power
Complex utilize the 138 kV transmission grid. No 230 kV transmission is present at Evander
Andrews at this time.
Evander Andrews has four 230 kV lines in relatively close proximity. Three of them run ITom the
Midpoint Substation(north of Twin Falls, ill) to the east Boise area. The closest is the Midpoint-
DRAM #1 line, which is approximately 4 miles Northeast of Evander Andrews. This line utilizes
single 715.5 MCM conductors and has a continuous rating of339 MV A. The Rattlesnake-Boise
Bench #2 line is approximately 5 miles Northeast of Evander Andrews and utilizes a 2 conductor
bundle of715.5 MCM. This line has a continuous rating of 677 MV A. The Midpoint-Boise
Bench #3 line is approximately 7 miles Northeast of Evander Andrews. This line has similar
conductors and the same rating as the Rattlesnake-Boise Bench #2 line. The fourth 230 kV line in
the area is the Rattlesnake-Bennett Mountain line. It is approximately 5 miles to the Southeast of
Evander Andrews. This line utilizes single 1272 MCM conductors and has a continuous rating of
478 MVA.
In addition to the three Midpoint to the east Boise area 230 kV lines previously mentioned, there
are two 138 kV circuits which can carry power ITom the Mountain Home area to the Boise Area.
They are:
Mountain Home Junction-Lucky Peak-Micron 138 kV Line
Mountain Home Junction-Evander Andrews-Strike-Swan Falls-Bowmont 138 kV
Line
Generators located in the Mountain Home 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 feasibility study will
model 1100 MW oftransfers 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 #3230 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 simple cycle gas turbine s 91 MW
summer output was inserted into a power flow case that would simulate committed (1100 MW)
pre-contingency flows on the Midpoint West transmission path.
In accordance with the Scoping Meeting for this Feasibility Study Request, three alternatives
were studied, all of which employed a 230 kV interconnection voltage.
Alternative #1 employed a radial 230 kV line to connect the generator to the Midpoint-Boise
Bench #3 transmission line. The line was modeled as being 7.7 miles in length and utilized
1272 MCM single conductor construction. An additional improvement of a 230/138 kV 200
MV A transformer(duplicate of the Midpoint unit) was explored at Evander Andrews to
improve the performance of this alternative.
Alternative #2 calls for the construction of two new 230 kV transmission lines from Bennett
Mountain to Evander Andrews, and Evander Andrews to Rattlesnake. These lines would
complete a 1272 MCM single conductor 230 kV loop from Rattlesnake to Bennett Mountain to
Evander Andrews and back to Rattlesnake. In addition, the Dram-Midpoint #1230 kV line
would be looped into Rattlesnake and rebuilt to support a two conductor bundle of715.5 MCM
conductors west of Rattlesnake. Additional transmission modifications were also modeled
outside of DRAM substation to make the "Old Midpoint to DRAM #1" 230 kV line bypass
the DRAM Substation and terminate at Boise Bench. The combination of bundled conductors
and folding the #lline into Rattlesnake Substation necessitated the change to avoid overloads
at DRbM associated with the loss of the DRAM to Boise Bench 230 kV line. A 230/138 kV
200 My A transformer(duplicate of the Midpoint unit) was modeled at Evander Andrews to
improve system performance under N-l conditions.
Alternative #3 employed the rebuild of a de-energized 132 kV transmission line to 230 kV
bundled 795 MCM construction between Bennett Mountain and Mora Substations. This
alternative utilizes the 406 line route (originally was the Upper Salmon to Caldwell line) which
passes in the vicinity of Evander Andrews. The west end of this new 230 kV line is assumed
to terminate at a new 230 kV Mora Substation, which is folded into the Boise Bench-Caldwell
230 kV line. No 230/138 kV transformer is modeled to tie the two Mora busses. A 230/138
kV 200 MV A transformer(duplicate of the Midpoint unit) was modeled at Evander Andrews to
improve system performance under N-l conditions. Studies also revealed the need to
reconductor/rebuild the Evander Andrews to Mountain Home Junction 138 kV line, with this
alternative.
Post-transient Study Results
This Interconnection Feasibility Study Report is for Network Resource Interconnection Service
at 230 kV, for a 91/100 MW simple cycle gas turbine at the Evander Andrews Power Project.
System transfers across the Midpoint West cutplane are modeled at 1100 MW prior to the
proposed transmission improvements or the proposed generator 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 Evander Andrews and Bennett Mountain were
varied over their operating ranges as appropriate. N-O and N-l outage performance for the
existing system are recorded. As agreed in the Scoping Meeting, three alternatives were
evaluated. For each alternative, the new generator s output was taken to its summer
temperature maximum level of91 MW and system conditions recorded for both N-O and N-
outages.
Existin2 System
The following one line diagram depicts the existing system with no outages.
Mid oint West = 1100
Existing System - No Outages
Figure 1
For the existing system, seven N-l outages produce overloads that exceed the continuous
rating of elements ofthe transmission system. The N-s that produce overloads with the
existing system are included in Appendix B, Figures 7 - 13.
Alternative #1
The following one line diagram depicts the system with Alternative #1 added, full summer
output of the generator, and with no outages.
Mid oint West = 1081 MW
Alternative #1- No Outages
Figure 2
Alternative #1 has multiple N-l outages that produce overloads that exceed 115% of
continuous ratings. Some of the resulting overloads are reduced with the addition of the
Evander Andrews 230/138 kV transformer, and others are increased.
Some of the larger overloads are produced by the Lockman Butte to Boise Bench #3230 kV
line outage. The following one line depicts a 123 % loading on the Mountain Home Junction
to Lucky Peak 138 kV line, without the Evander Andrews 230/138 kV transformer.
'-
Mid oint West = 949 MW
. Alternative #1 - Lockman Butte-Boise Bench #3 230 kV Outage
Without the Evander Andrews 230/138 kV Transformer
Figure 3
Adding the Evander Andrews 230/138 kV Transformer to the above outage, produces a 156%
loading on the Mountain Home Junction to Lucky Peak 138 kV line.
With the Evander Andrews 230/138 kV transformer in-service, there are no other N-l outages
that produce overloads that exceed 115% loading.
Without the Evander Andrews 230/138 kV transformer in-service, four otherN-l outages
produces overloads that exceed 115% loading and are also greater than existing system
overloads for the same N-l. They are:
Rattlesnake - Boise Bench #2 230 kV Line outage
Midpoint - Rattlesnake #2 230 kV line outage
Evander Andrews - Strike 138 kV line outage
Strike - Bowmont 138 kV line outage
Several other N-l outages result in overloads below 115% that would require curtailments
following the outage to get down to loadings that can be sustained continuously. In some
cases, lowering the output of the proposed generator helps to lower the overload, but in one
case (Lucky Peak - Micron 138 kV line outage), the overload increases as the proposed
generators output is lowered.
Alternative #1 is an unacceptable alternative, due to the N-l outage that produces an overload
that exceeds 115% of continuous ratings. The Network Rating for Alternative #1 is 0 MW.
Alternative #2
The following one line diagram depicts the system with Alternative #2 added, full output of the
generator, and with no outages.
Mid oint West = 1101 MW
Alternative #2 - No Outages
Figure 4
The aq,gition ofthe Evander Andrews 230/138 kV transformer improves the performance of
Alternative #2 for most N-l outages, but not all. Without the Evander Andrews 230/138 kV
transformer, Alternative #2 has four N-l outages that produce overloads that exceeds 115% of
continuous rating, however, all the overloads are less than existing system overloads for the
same N-l and as a result are judged to provide acceptable performance. With the Evander
Andrews 230/138 kV transformer, Alternative #2 has no N-l outages that produce overloads
that exceed 115% of continuous rating.
Curtailments are required for all three N-l outages ofthe 230 kV lines from the Mountain
Home area into Boise Bench. Loss of the Rattlesnake to Boise Bench #1 or #2 lines require
the proposed unit's output to be lowered to approximately 67 MW to reduce overloads to
100% ofthe continuous rating or a level that the overload is no worse than it is for the existing
system with the same N-l outage. These contingencies and resulting system performance
determines the Network Resource Rating to be 67 MW for Alternative #2. The loss ofthe
Midpoint to Boise Bench #3230 kV line requires a curtailment to lower a 120% overload of
the series capacitors on the Midpoint to Rattlesnake #2 230 kV line. This alternative does not
permit the overload to be reduced by lowering the output ofthe proposed unit. Lowering the
output of proposed unit will increase the overload on the series capacitors in question. Other
generators would have to be curtailed to solve this overload scenario.
' -'-
Alternative #2 will require curtailments of the proposed generators output following multiple
l outages. As a result, Alternative #2 does not provide acceptable performance for Network
Resource Interconnection Service for the proposed unit at full output. The Network Resource
Rating for Alternative #2 is 67 MW. Alternative #2 is also believed to very similar in cost to
Alternative #3, yet it's performance is much more problematic than Alternative #3.
Alternative #3
The following one line diagram depicts the system with Alternative #3 added, full output of the
generator, and with no outages.
Mid oint West = 1119
Alternative #3 - No Outages
Figure 5
The addition of the Evander Andrews 230/138 kV transformer improves the performance of
Alternative #3, for all but one ofthe N-l outages. With the Evander Andrews 230/138 kV
transformer in service, alternative #3 has no N-l outages that produce overloads that exceed
115% of continuous ratings.
One N-l outage results in an overload below 115% and at a level that the overload is greater
than it is for the existing system with the same N-l outage. The loss of the Midpoint to Boise
Bench #3230 kV line results in a 116% loading on the series capacitor of the Midpoint to
Rattlesnake #2 230 kV line. This series capacitor is capable of 110% loading continuously, so
a 6% reduction in flow is required. Lowering generation in the Mountain Home area results in
increased flow on the series capacitor bank, so transfers across the Midpoint West cutp1ane
will need to be reduced to correct this overload, as well as prepare for the next contingency.
Alternative #3 changes the characteristics of the interconnected network enough to create the
need to reconductor/rebui1d the Evander Andrews to Mountain Home Junction 138 kV line.
For the N-l outage of the Lucky Peak to Micron 138 kV line, the Evander Andrews to
Mountain Home Junction 138 kV line loads to 113% of its rating with all the peaking
generation in the Mountain Home area at full output. lithe output of the peaking generation in
the Mountain Home area is reduced, the overload increases in magnitude. The following one
line diagram depicts the Lucky Peak to Micron 138 kV line outage with all the Mountain
Home area peaking generation offline.
Mid oint West = 1157
Alternative #3 - Luck Peak to Micron 138 kV Line Outage
With Peakers Off-line
Figure 6
Alternative #3 is the recommended alternative for the proposed unit at 91/100 MW for
Network Resource Interconnection Service.
Cost Allocation of Proposed Improvements
Alternative #3 contains the following five construction components:
Bennett Mountain to Evander Andrews 230 kV line and terminals
Evander Andrews to Mora 230 kV line and terminals
230 kV generator connection terminal at Evander Andrews
Evander Andrews 230/138 kV transformer and terminals
Reconductor/rebuild of the Evander Andrews to Mountain Home Junction 138
kV line
A cursory attempt has been made in this study to characterize each transmission improvement
as either "needed to integrate the proposed generator" or "needed to correct existing
operational concerns . The costs associated with those improvements believed to be "needed
to integrate the proposed generator" are allocated to the generator interconnection. The costs
10-
associated with those improvements believed to be "needed to correct existing operational
concerns " are allocated to IPCo Delivery.
Approximate estimated costs allocated to the generator interconnection are:
$ 4.1 Million - Bennett Mountain to Evander Andrews 230 kV line and terminals
$17.3 Million - Evander Andrews to Mora 230 kV line and terminals
$ 0.4 Million - 230 kV generator connection terminal at Evander Andrews
$21.8 Million - Total estimated generator interconnection cost
Approximate estimated costs allocated to the IPCo Delivery are:
$2.1 Million - Evander Andrews 230/138 kV transformer and terminals
$1.7 Million - Evander Andrews to Mountain Home Junction 138 kV line rebuild
$3.8 Million - Total estimated allocation to IPCo Delivery
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 subj ect 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.
10.Short Circuit Study Results
Preliminary short circuit study results indicate the surrounding circuit breakers are believed to
be able to accommodate the increased fault duty. No circuit breaker replacements are
anticipated at this time.
11.Conclusions
The feasibility of interconnecting a 91/100 MW simple cycle gas turbine at Evander Andrews
Power Complex to Idaho Power s 230 kV transmission system was studied. Three interconnection
alternatives were evaluated. Alternative #1 was found to be an unacceptable alternative due to
transmission system loadings that exceeded 115% for N-l outages. Alternative #2 did not provide
acceptable performance for Network Resource Interconnection Service for the proposed unit at full
output. The Network Resource Rating for Alternative #2 is 67 MW. Alternative #3 was found to
be an acceptable interconnection alternative. While Alternative #3 does require minimal
redispatch/transmission switching for one N-l outage, it is minor in nature and deemed acceptable
for this feasibility study. The estimated total cost of the transmission improvements associated with
Alternative #3 is approximately $26 Million. At this time it is believed that approximately $22
Million of these estimated costs should be allocated to the generator interconnection.
11-
'-,
APPENDIX A
1.0 Method of Study
The study methodology inserts the proposed generator up to the maximum requested summer
output of91 MW into the selected WECC power flow case and then, using the PowerWorld
Simulator powerflow program, examines the impacts of the new resource on Idaho Power
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
acceptabilityofthe alternatives:
Loadings on transmission lines and transformers should not exceed 115% of the
continuous rating, immediately flowing anyN-l outage. Loading on the Midpoint 230
kV series capacitors should not exceed 135% of the continuous rating, immediately
flowing anyN-l outage. These loadings levels of 115% on transmission lines and
transformers and 135% on Midpoint series capacitors correspond to IPCo 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
12-
decay or even collapse under the worst conditions. Idaho Power designs its system to
integrate Network Resources at full capability during specified outage conditions.
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 ofthis study. Future transmission changes may, however, affect
current facility ratings used in the study.
13-
APPENDIX B
1.0 l Outages That Produce Overloads On The Existing System
The following one line diagrams depict system performance following the seven N-l outages
that produce overloads which exceed the continuous rating of facilities. Figure 1 on page 5
depicts the operation of the existing system with no outages. The combination of heavy hydro
and peaker generation in the Mountain Home area, and 1100 MW east to west transfers on
Midpoint West, results in the Mountain Home Junction to Lucky Peak and Lucky Peak to
Micron 138 kV lines being loaded to 98% & 99% respectively, prior to any outages.
Mid oint West = 981
Existing System - Midpoint to Boise Bench #3 230 kV Outage
Figure 7
14-
Mid oint West = 951
Existing System - Rattlesnake to Boise Bench #2 230 kV Outage
Figure 8
Mid oint West = 997
Existing System - Midpoint to Rattlesnake #2 230 kV Outage
Figure 9
15-
Mid oint West = 1053 MW
Existing System - Midpoint to DRAM #1 230 kV Outage
Figure 10
Mid oint West = 1085
Existing System - CJ Strike to Bowmont 138 kV Outage
Figure 11
16-
Mid oint West = 1072
Existing System - Lucky Peak to Micron 138 kV Outage
Figure 12
MIdpoint West = 1094
Existing System - Evander Andrews to CJ Strike 138 kV Outage
Figure 13
17-
- ,
LARGE GENERATOR INTERCONNECTION
FEASIBILITY STUDY REPORT
for the
138 KV INTERCONNECTION OPTION
EV ANDER ANDREWS PROJECT
for
Idaho Power Company - Power Supply, Interconnection Customer
for connection of
A 73/86 MW SIMPLE CYCLE GAS TURBINE PEAKING PROJECT
EV ANDER ANDREWS PROJECT
IDAHO POWER COMPANY, Transmission Provider
TRANSMISSION SYSTEM
FINAL REPORT
October 14, 2005
1.0 Introduction
Idaho Power Company - Power Supply has contracted with Idaho Power Company (IPC) to
perform a Large Generator Interconnection Feasibility Study for Network Resource
Interconnection Service at 138 kV for the integration of a new 73/86 MW simple cycle gas
turbine peaking project. The proposed location is the Evander Andrews Project near Mountain
Home, Idaho.
This report documents the basis for and the results of this Feasibility Study. It describes the
proposed interconnection alternatives, the study cases used, outage scenarios assumed and
results of all work in the areas of concern.
Summary
The performance of a 138 kV interconnection alternative was evaluated to integrate a simple
cycle gas turbine with a summer rating of 73 MW and a winter rating of 86.3 MW, located at
Evander Andrews Project, into the Idaho Power System. Several system performance
problems for N-l outages , necessitated additional facility additions, but ultimately a 138 kV
interconnection alternative was found that performed acceptably.
The addition of a new 138 kV transmission line from Evander Andrews to the Mora Substation
was the initial interconnection alternative that was evaluated. It did not perform acceptably for
its own N-l outage. To correct this performance shortcoming, a 230/138 kV 200 MV A
transformer at Rattlesnake Substation and a new 138 kV transmission line from Rattlesnake to
Mountain Home Junction was added to the alternative. The additional facilities resulted in
acceptable performance for the N-l outage ofthe proposed Evander Andrews to Mora 138 kV
line. However, the 230/138 kV transformer addition resulted in performance problems for a
different N-l outage. As a result, the reconductor/rebuild of the Evander Andrews to Mountain
Home Junction 138 kV transmission line was added to the necessary facility additions for the
138 kV interconnection alternative.
The estimated total cost for this alternative is approximately $23.1 Million, with all the costs
allocated to Idaho Power Company - Power Supply for the generator interconnection
improvements. Following the execution of either a Large Generator Interconnection
Agreement or a Engineering & Procurement Agreement by Idaho Power Company - Power
Supply, Idaho Power Company estimates the time required to construct these facilities is
approximately 18-21 months.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). These are cost
estimates only and final charges to the customer will be based on the actual construction costs
incurred.
Summary of Interconnection Request
A request was made to Idaho Power Co. by Idaho Power Company - Power Supply to study
the interconnection of a proposed 73/86 MW simple cycle gas turbine at the Evander Andrews
Project, near Mountain Home, Idaho, to Idaho Power s transmission system at the 138 kV level
for Network Resource Interconnection Service.
Scope of Interconnection Feasibility Study
The Interconnection Feasibility Study was done and prepared in accordance with the FERC
Order 2003-, Standard Large Generator Interconnection Procedures , to provide a preliminary
evaluation of the feasibility 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 Proposed Generating Project
Idaho Power Company - Power Supply proposes to connect a 73/86 MW simple cycle gas
turbine to the Idaho Power 138 kV transmission system, at the existing Evander Andrews
Power Complex, 1862 NW Mashburn RD., Mountain Home, ill 83647. The maximum
generating capacity of the proposed unit is estimated to be 73 MW for the summer and
86.3 MW for winter temperatures. The equipment is described as being, two GE LM 6000
packages , or a GE7FA, or a GE LMSlOO package. The proposed commercial operation date is
April 1 2007.
Description of Existing Transmission Facilities
At the Scoping Meeting for this Interconnection Request, it was agreed that the interconnection
voltage to be studied would be 138 kV. The existing generating units at Evander Andrews Power
Complex utilize the 138 kV transmission grid. No 230 kV transmission is present at Evander
Andrews at this time.
Evander Andrews has four 230 kV lines in relatively close proximity. Three of them run from the
Midpoint Substation(north of Twin Falls, ill) to the east Boise area. The closest is the Midpoint-
DRAM #1 line, which is approximately 4 miles Northeast of Evander Andrews. This line utilizes
single 715.5 MCM conductors and has a continuous rating of 339 MV A. The Rattlesnake-Boise
Bench #2 line is approximately 5 miles Northeast of Evander Andrews and utilizes a 2 conductor
bundle of 715.5 MCM. This line has a continuous rating of 677 MV A. The Midpoint-Boise
Bench #3 line is approximately 7 miles Northeast of Evander Andrews. This line has similar
conductors and the same rating as the Rattlesnake-Boise Bench #2 line. The fourth 230 kV line in
the area is the Rattlesnake-Bennett Mountain line. It is approximately 5 miles to the Southeast of
Evander Andrews. This line utilizes single 1272 MCM conductors and has a continuous rating of
478 MVA.
In addition to the three Midpoint to the east Boise area 230 kV lines previously mentioned, there
are two 138 kV circuits which can carry power from the Mountain Home area to the Boise Area.
They are:
Mountain Home Junction-Lucky Peak-Micron 138 kV Line
Mountain Home Junction-Evander Andrews-Strike-Swan Falls-Bowmont 138 kV
Line
Generators located in the Mountain Home 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 feasibility study will
model 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 #2 230 kV Line
. Midpoint-Boise Bench #3230 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 simple cycle gas turbine s 73 MW
summer output was inserted into a power flow case that would simulate committed (1100 MW)
pre-contingency flows on the Midpoint West transmission path.
In accordance with the Scoping Meeting for this Feasibility Study Request a 138 kV alternative
was studied. A new Evander Andrews to Mora 138 kV transmission line, utilizing 1272 MCM
single conductor construction, was explored in the initial powerflow studies. This line is
assumed to be 36.4 miles in length.
The initial powerflow studies indicated additional facility improvements would be required to
achieve satisfactory system performance under N-l outage conditions. As a result, the addition
of a 230/138 kV 200 MV A transformer at Rattlesnake Substation and a 138 kV transmission
line from Rattlesnake to Evander Andrews was incorporated into the configuration studied.
The Rattlesnake to Evander Andrews 138 kV line was assumed to be 1 mile in length and
utilized 954 MCM single conductor construction. Subsequent powerflow studies indicated
additional facility improvements would be required to achieve satisfactory system performance
under different N -1 outage conditions. The final facility addition to the configuration studied
was a reconductor/rebuild of the Evander Andrews to Mountain Home Junction 138 kV line.
This line is approximately 5.6 miles in length and the existing 397.5 MCM conductors were
upgraded to 954 MCM.
The facility additions employed in the final configuration of this study are listed below:
A new 138kV transmission line from Evander Andrews to Mora Substation.
A new 230/138 kV 200 MV A transformer at Rattlesnake Substation.
A new 138 kV transmission line from Rattlesnake to Mountain Home Junction.
A reconductor/rebuild of the Evander Andrews to Mountain Home Junction 138 k
transmission line.
Post-transient Study Results
This Interconnection Feasibility Study Report is for Network Resource Interconnection Service
at 138 kV, for a 73/86 MW simple cycle gas turbine at the Evander Andrews Power Project.
System transfers across the Midpoint West cutplane are modeled at 1100 MW prior to the
proposed transmission improvements or the proposed generator 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 Evander Andrews and Bennett Mountain were
varied over their operating ranges as appropriate. N-O and N-l outage performance for the
existing system are recorded. As agreed in the Scoping Meeting, a 138 kV alternative was
evaluated. For the 138 kV alternative, the new generator s output was taken to its summer
temperature maximum level of 73 MW and system conditions recorded for both N-O and N-
outages.
Existing System
The following one line diagram depicts the existing system with no outages.
BOISEBCH1.02,"
Mld olnt West = 1100
Existing System - No Outages
Figure 1
For the existing system, seven N-l outages produce overloads that exceed the continuous
rating of elements of the transmission system. The N-l' s that produce overloads with the
existing system are included in Appendix B , Figures 9 - 15.
Additional Facilities Added
The following one line diagram depicts the system with full summer output of the generator
only the Evander Andrews- Mora 138 kV line added, and with no outages.
n1E,",
Mid oint West = 1100
Evander Andrews to Mora Line & Generator Added - No Outages
Figure 2
With the generator and the Evander Andrews to Mora 138 kV line added, one N-l outage
produces an overload that exceeds 115% of continuous ratings. The N-l outage with
unacceptable performance is loss of the new Evander Andrews to Mora 138 kV line. The
following one line diagram depicts the system performance with full summer output of the
generator and loss of the Evander Andrews to Mora 138 kV line.
,,\,Iij'
MidDoint West 1089 MW
Loss of Evander Andrews to Mora 138 kV Line, when it was
the only proposed transmission improvement
Figure 3
The 119% loading on the Mountain Home Junction to Lucky Peak 138 kV line, requires
additional transmission improvements be added to this proposal in an attempt to achieve
acceptable performance for a 138 kV interconnection alternative. The least expensive
transmission addition that will relieve the Mountain Home Junction to Lucky Peak 138 kV
overload, is installation of a 230/138 kV 200 MV A transformer at Rattlesnake Substation
along with a new one-mile long 954 MCM 138 kV line from the low side of the transformer to
Mountain Home Junction. The following one line depicts system performance with
transmission improvements including, the Evander Andrews to Mora 138 kV line, a 230/138
k V 200 MV A transformer at Rattlesnake, and a new 138 k V line from Rattlesnake to Mountain
Home Junction, with no outages.
n,!!'.",
MidDoint West = 1101 MW
Evander Andrews to Mora 138 kV Line,
Rattlesnake 230/138 k V Transformer,
Rattlesnake to Mountain Home Junction 138 kV Line,
& Generator Added - No Outages
Figure 4
For the transmission facilities shown above, three N-l outages produce overloads that exceed
115 % of continuous ratings. All three outages create overloads on the Evander Andrews to
Mountain Home Junction 138 kV line. The following one line depicts system performance
with transmission improvements including, the Evander Andrews to Mora 138 kV line, a
230/138 kV 200 MV A transformer at Rattlesnake, and a new 138 kV line from Rattlesnake to
Mountain Home Junction. The outage for this one line diagram is the 230 kV Boise Bench to
Rattlesnake #2 line, with all the peakers off-line at Evander Andrews.
Bn~'j,""
MidDoint West = 1033 MW
Evander Andrews to Mora 138 k V Line added,
Rattlesnake 230/138 kV Transformer added
Rattlesnake to Mountain Home Junction 138 kV Line added,
& Evander Andrews Peakers Off-line
- with Boise Bench to Rattlesnake #2 230 k V Line Outage
Figure 5
The overloads experienced on the Evander Andrews to Mountain Home Junction 138 kV line
for all three problem N -1' s , mandates the need to reconductorlrebuild the line with a minimum
of 954 MCM conductor. The following one line diagram depicts system performance with no
outages for the following additions:
Evander Andrews to Mora 1272 MCM 138 kV Line
Rattlesnake 230/138 kV 200 MV A Transformer
Rattlesnake to Mountain Home Junction 954 MCM 138 kV Line
Evander Andrews to Mountain Home Junction reconductorlrebuild from 397.
MCM conductor to 954 MCM conductor
bW"
Mid oint West = 1101
Evander Andrews to Mora 138 k V Line added
Rattlesnake 230/138 k V Transformer added,
Rattlesnake to Mountain Home Junction 138 kV Line added,
& Mountain Home Junction to Evander Andrews 138 kV Line Reconductored
- No Outages
Figure 6
Two N-l outages result in performance concerns for the addition of the generator and the other
transmission facilities listed above. The most serious concern is for the outage of the Boise
Bench to Rattlesnake #2 230 kV line, with all the peaking generation on-line at Evander
Andrews. The following one line diagram depicts system performance for this outage.
nl'iJ',
Mld oint West 1003 MW
Evander Andrews to Mora 138 k V Line added
Rattlesnake 230/138 kV Transformer added,
Rattlesnake to Mountain Home Junction 138 kV Line added,
& Mountain Home Junction to Evander Andrews 138 kV Line Reconductored
- Boise Bench to Rattlesnake #2 230 kV Line Outage
Figure 7
The 136% loading on the Mountain Home Junction to Lucky Peak 138 kV line will require a
remedial action scheme(RAS) to provide acceptable performance. Following the loss of the
Boise Bench to Rattlesnake #2 230 kV line, either the Rattlesnake 230/138 kV transformer or
the Mountain Home Junction to Lucky Peak 138 kV line could be opened to relieve the
overload. The following one line diagram depicts system performance for a remedial action
scheme that opens the Rattlesnake 230/138 kV transformer following the loss of the Boise
Bench to Rattlesnake #2 230 kV line.
10-
BOISEBeH00p"
Mid oint West = 957
Evander Andrews to Mora 138 kV Line added
Rattlesnake 230/138 kV Transformer added,
Rattlesnake to Mountain Home Junction 138 kV Line added
& Mountain Home Junction to Evander Andrews 138 kV Line Reconductored
- Boise Bench to Rattlesnake #2 230 kV Line Outage with RAS opening Rattlesnake
230/138 k V Transformer
Figure 8
The N-l outage of the Rattlesnake to Midpoint #2 230 kV line, with the Evander Andrews
peaking generation off-line, creates a 2% overload of the Upper Salmon to Mountain Home
Junction 138 kV line. An operating procedure will be required to relieve this minor overload.
Opening the Rattlesnake 230/138 kV transformer is a possible solution.
Both the remedial action scheme and the operating procedure can be further investigated if this
project proceeds to a system impact study.
The Brownlee to Ontario 230 kV line outage is critical in determining the timing of the next
major transmission system improvement project required for Treasure Valley load growth. For
the existing system approximately 205 MW of NampalCaldwell area load growth can be
accommodated before major transmission improvements are required. With 73 MW of new
generation at the Evander Andrews Site and the associated transmission facility improvements
for a 138 kV interconnection, approximately 228 MW of load growth in the NampalCaldwell
area can be accommodated before major transmission system improvements are required. As a
result, the utilization of the 138 kV interconnection alternative for a 73 MW generator at the
Evander Andrews Site will slightly delay the schedule for the next major transmission system
improvement to accommodate load growth in the NampalCaldwell area.
11-
,..
A 138 kV interconnection alternative is feasible for Network Resource Interconnection Service
for the proposed 73/86 MW simple cycle gas turbine at the Evander Andrews Project. With
the following transmission facility additions, marginally acceptable system performance is
possible:
Evander Andrews to Mora 1272 MCM 138 kV Line
Rattlesnake 230/138 kV 200 MV A Transformer
Rattlesnake to Mountain Home Junction 954 MCM 138 kV Line
Evander Andrews to Mountain Home Junction reconductorlrebuild from 397.
MCM conductor to 954 MCM conductor
Cost Estimates of Proposed Improvements
Approximate estimated costs for the proposed transmission improvements are:
$16.9 Million - Evander Andrews to Mora 138 kV line and terminals
$ 4.0 Million - Rattlesnake 230/138 kV Transformer and Rattlesnake to Mountain
Home Junction 138 kV Line & associated terminals
$ 1.7 Million - Evander Andrews to Mountain Home Junction 138 k V Line
Reconductorlrebuild
$ 0.5 Million - Generator 138 kV Connection Terminal at Evander Andrews
$23.1 Million - Total estimated generator interconnection cost
All of these interconnection costs would be allocated to the generator interconnection.
These cost estimates include direct equipment and installation labor costs, indirect labor costs
and overheads, and allowance for funds used during construction (AFUDC). These are cost
estimates only and final charges to the customer will be based on the actual construction costs
incurred.
10.Short Circuit Study Results
Preliminary short circuit study results indicate the surrounding circuit breakers are believed to
be able to accommodate the increased fault duty. No circuit breaker replacements are
anticipated at this time.
11.Conclusions
The feasibility of interconnecting a 73/86 MW simple cycle gas turbine at Evander Andrews Power
Complex to Idaho Power s 138 kV transmission system was studied. Initial studies found adding
only a Evander Andrews to Mora 138 kV line would not yield acceptable performance. Several
successive rounds of adding additional transmission improvements did eventually yield marginally
acceptable performance. The required transmission improvements are:
12-
A new 138 kV transmission line from Evander Andrews to Mora Substation.
A new 230/138 kV 200 MV A transformer at Rattlesnake Substation.
A new 138 kV transmission line from Rattlesnake to Mountain Home Junction.
A reconductorlrebuild of the Evander Andrews to Mountain Home Junction 138 kV
transmission line.
The estimated total cost of the transmission improvements associated with the 138 k
interconnection alternative is approximately $23.1 Million. At this time, it is believed that the
entire $23.1 Million should be allocated to the generator interconnection.
13-