TONBRIDGE POWER
Green Line Project
Plan of Service
108005-00037 – TON-EL-REP-0001
13 June 2011
Bellaire
6330 West Loop South, Bellaire TX 77401, United States
Tel: +1 713 407 5005
Fax: +1 713 407 5099
WorleyParsons Limited
© Copyright 2011 WorleyParsons
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
SYNOPSIS
This report documents the transmission line calculations, results, and recommendations undertaken
as part of the Green Line Project for Tonbridge Power.
Disclaimer
This study report is conceptual in nature and represents the work of WorleyParsons performed to
recognized engineering principles and practices appropriate for conceptual engineering work and
the terms of reference provided by WorleyParsons’ contractual Customer, Tonbridge Power (the
“Customer”). This study report may not be relied upon for detailed implementation or any other
purpose not specifically identified within this study report. This study report is confidential and
prepared solely for the use of the Customer. The contents of this study report may not be used or
relied upon by any party other than the Customer, and neither WorleyParsons, its subconsultants
nor their respective employees assume any liability for any reason, including, but not limited to,
negligence, to any other party for any information or representation herein. The extent of any
warranty or guarantee of this study report or the information contained therein in favor of the
Customer is limited to the warranty or guarantee, if any, contained in the contract between the
Customer and WorleyParsons.
PROJECT 108005-00037 - GREEN LINE PROJECT
REV
DESCRIPTION
A
Issued for Review
B
ORIG
REVIEW
WORLEYPARSONS
APPROVAL
C Aderholdt
J Glasgow
R Simon
C Aderholdt
J Glasgow
R Simon
Issued for Review
DATE
CLIENT
APPROVAL
19-May-11
N/A
13-Jun-11
N/A
DATE
N/A
Green Line Report
Rev B (16-June-11)
Corporate Base
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
CONTENTS
A. EXECUTIVE SUMMARY ..................................................................................................5 B. INTRODUCTION ..............................................................................................................6 C. PLAN BASIS.....................................................................................................................7 D. PLAN ASSUMPTIONS .....................................................................................................8 E. RECOMMENDED PLAN ..................................................................................................9 F. RECOMMENDED PLAN (ALTERNATIVE) .....................................................................10 G. PLAN 3 - DETAILED DESCRIPTION .............................................................................11 G.1 Plan 3 Summary ..............................................................................................11 G.2 Plan 3 Details ..................................................................................................11 G.3 Plan 3 Impact on Area Voltages ......................................................................12 G.4 Plan 3 Impact on Area Transmission Services ................................................12 G.5 Plan 3 Transient Analysis ................................................................................13 G.6 Plan 3 Transmission Line Losses ....................................................................14 G.7 Plan 3 Costs ....................................................................................................14 G.8 Plan 3 Conclusions ..........................................................................................14 H. PLAN 3A - DETAILED DESCRIPTION ...........................................................................15 H.1 Plan 3A Summary ...........................................................................................15 H.2 Plan 3A Details ................................................................................................15 H.3 Plan 3A Impact on Area Voltages ....................................................................16 H.4 Plan 3A Impact on Area Transmission Services ..............................................17 H.5 Plan 3A Transient Analysis..............................................................................18 H.6 Plan 3A Transmission Line Losses..................................................................18 H.7 Plan 3A Costs..................................................................................................18 H.8 Plan 3A Conclusions .......................................................................................18 I. CONCLUSION AND RECOMMENDATIONS .................................................................19 J. SWITCHING STUDY ......................................................................................................20 Green Line Report
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
K. REFERENCES ...............................................................................................................23 Appendices
APPENDIX 1 - PLAN COSTS APPENDIX 2 - PLAN SKETCHES APPENDIX 3 - PRELIMINARY 230 KV SWITCHING STATION LAYOUTS APPENDIX 4 - ALTERNATE PLANS FOR CONNECTING GREEN LINE TO GARRISON OR
TOWNSEND APPENDIX 5 - ALTERNATE PLANS FOR CONNECTING TONBRIDGE SS TO GREAT FALLS
USING A POWER CIRCUIT BREAKER Green Line Report
Rev B (9-June-11)
Corporate Base
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
A.
EXECUTIVE SUMMARY
Tonbridge Power plans to construct a 230 kV transmission line (called the Green Line) in
western Montana. The proposed Green Line will connect wind generation in Montana into
the existing Colstrip to Taft 500 kV EHV transmission system. Initially two alternate
interconnection points for the Green Line were proposed. One plan was to construct a Great
Falls to Garrison 230 kV transmission line with one end terminated in the existing Great Falls
230 kV substation and the other end at the Garrison 500 kV substation. The second plan
was to construct a Great Falls to Townsend 230 kV transmission line with one end
terminated at Great Falls and the other in a new Townsend 500 kV substation.
Tonbridge Power submitted two Points of Interconnection requests to the Bonneville Power
Administration (BPA) for the Green Line project for a Feasibility Study. Both interconnection
requests were alternate Points of Interconnection for the Green Line project. One of the two
alternate Points of Interconnection was for an interconnection, for the Green Line, at the
existing Garrison 500 kV substation. The other alternative was for an interconnection, for
the Green Line, at a site near Townsend. At the existing Garrison 500 kV substation
Tonbridge will install two 500/230 kV transformers to connect the 230 kV Green Line to the
500 kV network. The Townsend site will require the construction of a new Townsend
500/230 kV substation and will also require Tonbridge to install two 500/230 kV transformers
at the new Townsend 500 kV substation to connect the Green Line to the 500 kV network.
BPA completed a Line Loading Interconnection Feasibility Study (LLIFES) for the two
Tonbridge Power Point of Interconnection requests November 15, 2010. The BPA feasibility
study concluded the Green Line Plan of Service as originally provided by “the developer to
get to the Points of Interconnection did not appear to be feasible.”
As a result of the BPA feasibility study, Tonbridge Power asked Worley Parsons, Corp to
develop a Plan of Service for the Green Line that would meet the BPA system requirements.
The purpose of this report is to discuss the alternate Plans of Service for the Green Line
developed by Worley Parsons that will meet the NERC, WECC, and member reliability
standards, and, to recommend a preferred Plan of Service.
Green Line Report
Rev B (9-June-11)
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
B.
INTRODUCTION
The proposed “Green Line” will connect renewable wind energy in Central Montana to the
existing northwest power grid. To connect the wind energy to the northwest power grid will
require a Point of Interconnection on the Colstrip to Taft 500 kV transmission line. The two
possible interconnection points being considered are the existing Garrsion, MT., 500 kV
substation, or, at a new 500 kV substation to be constructed near Townsend, MT.
Eight (8) alternate plans were developed for the proposed Green Line transmission line
project; four for an interconnection at the existing Garrison 500 kV Substation, and four for
an interconnection near Townsend. Each of the alternate plans was studied using the
WECC 2014 Light Autumn load base case power system model. The wind turbine
generation (WTG) modelled in the base cases for each plan included 300 MW at Hay Lake,
and, 150 MW and 500 MW, at the Renewable Collector System (RCS) Substations A and B,
respectively.
The Green Line alternate plans developed in this study which are
recommended are described in detail, along with the power system study results, in Sections
G and H of this report. The other plans considered in this study are described in detail in
Appendix 4 and 5 of this report.
Two additional plans were developed after completion of the initial Green Line study: Plan
3A and Plan 9. Plan 3A is a variation of Plan 3. In Plan 3A, the Green Line is a singlecircuit, 600 MVA, transmission line from the Tonbridge SS to Garrison and there is only one
500/230 kV transformer at Garrison. Plan 9 extends the single-circuit, 600 MVA, Green Line
from Garrison to Marias and the Tonbridge switching station is constructed at Maries.
Green Line Report
Rev B (9-June-11)
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
C.
PLAN BASIS
The report basis is the following:
1.
PSSE Program Version 32.1.0
2.
PSSE power system model and dynamics data originally came from WECC.
3.
The results of the Power System Analysis also determined the reactive power
requirements at each of the substations. Switching studies must be conducted to
determine the maximum MVAR sizes of individual capacitor banks and shunt
reactors that can be safely switched.
4.
The rating for the proposed Phase Shifting Transformer (PST) and the MATL is
600 MVA. The rating for the 500/230 kV transformers 700 -800 MVA
5.
PSSE Model Modifications were made based on the different plans detailed in the
Report Sections detailing Plan 1 – Plan 8. Appendix 2 has some sketches to detail
6.
The projected in-service for Green Line is estimated to 2013.
7.
No cost estimates have been done for connections into the existing Great Falls
230 kV substation. A study will need to be performed to determine the impacts on
the existing equipment at Great Falls: PCB’s, bus, switches, transmission lines,
etc.
8.
No costs were included for the ten miles of 230 kV connecting the proposed
Tonbridge 230 kV Switching Station because that circuit is part of the MATL intertie
which was looped into the new Tonbridge SS.
9.
The existing Montana-Northwest (Mt-NW) path and the West-of-Garrison (WOG)
network are both limited to 2200 MW east-to-west. As a result, in this study,
generation at Colstrip was reduced to off-set the addition of Wind Turbine
Generation (WTG) at Hay Lake and the RCS.
Green Line Report
Rev B (9-June-11)
Corporate Base
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
D.
PLAN ASSUMPTIONS
When completing the PSSE calculations, the report assumptions are as follows:
1.
WECC 2014 Light Autumn Case Loading – The Montana to Northwest Path is
rated 2200 MW east to west and 1350 MW west to east; however, the 2200 MW
east to west is only available during light load conditions.
2.
The existing Montana-Northwest (Mt-NW) path and the West-of-Garrison (WOG)
network are both limited to 2200 MW east-to-west. As a result, in this study,
generation at Colstrip was reduced to off-set the addition of Wind Turbine
Generation (WTG) at Hay Lake and the RCS.
3.
Cost estimates are based on in-house pricing, except for the pricing provided by
BPA.
4.
The Phase Shifting Transformer rating was matched to the new MATL rating of
approximately 600 MVA.
5.
The two 500/230 kV transformers ratings were assumed to be in the 700 – 800
MVA range.
6.
The proposed Green Line will need to sized to approximately 1600 MVA to
accommodate the 600 MVA MATL line and 950 MW of Wind Turbine Generation.
7.
The Wind Turbines for the Hay Lake will be Acciona 1530 units with a reactive
capacity of +/- 0.59 MVAR. For the study, it was assumed the Wind Turbines for
the Renewable Collector System (RCS) would also be the Acciona 1530 units.
8.
The existing Montana-Northwest (Mt-NW) path and the West-of-Garrison (WOG)
network are both limited to 2200 MW east-to-west. As a result, in this study,
Generation at Colstrip was reduced to off-set the Wind Turbine Generation (WTG)
at Hay Lake and the RCS.
9.
For outages of the Garrison-Taft 1 & 2 or the Townsend-Garrison 1 & 2, 500 kV
transmission lines, with Green Line in-service and with 950 MW of WTG on-line,
the existing Colstrip ATR would trip the remaining generation at Colstrip.
10.
The existing Western Montana Remedial Action Scheme (RAS) can be modified to
include tripping the RCS WTG.
11.
Pricing for the AC/DC/AC back-to-back station has been requested from ABB.
Green Line Report
Rev B (9-June-11)
Corporate Base
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
E.
RECOMMENDED PLAN
Based on the results of this study, Plan 3 would be the preferred alternative. Plan 3 consists
of the following:
1.
2.
3.
4.
5.
6.
7.
8.
Construct a 230 kV “Tonbridge” Switching Station (SS) approximately 10 miles
north of the existing Great Falls 230 kV substation.
Loop the Montana-Alberta (MATL) 230 kV interconnection into the new Tonbridge
230 kV SS.
At the new Tonbridge SS – Add a phase shifting transformer (PST) in the
Tonbridge SS to Great Falls 230 kV circuit (MATL) to limit power flow into Great
Falls.
At the new Tonbridge SS – Install two, 230 kV, 80 MVAR shunt reactors and three,
230 kV, 60 MVAR, capacitor banks for voltage control/support
Construct a 145 mile, double-circuit, 230 kV transmission line (the Green Line)
from the new Tonbridge SS to the Garrison 500/230 kV substation.
At Garrison add two 500/230 kV transformers to connect to the 230 kV Green Line
to the 500 kV network.
Garrison 230 kV bus - Install two, 230 kV, 80 MVAR shunt reactors and three, 230
kV, 60 MVAR, capacitor banks for voltage control/support.
To prevent system collapse and instability following major contingencies, the
existing Western Montana Remedial Action Scheme (RAS) will need to be revised
to include tripping the Renewable Collector System (RCS) 650 MW of Wind
Turbine Generation (WTG).
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Rev B (9-June-11)
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
F.
RECOMMENDED PLAN (ALTERNATIVE)
Based on discussions with Tonbridge Power, another version of Plan 3 was developed.
Plan 3A is a variation of Plan 3 with the major change being the reduced capacity in the
proposed Green Line from approximately 1600 MVA to 600 MVA. This change is based on
expected available transmission capacity of about 600 MVA west of Garrison and the
possibility the Renewable Collector System (RCS), 650 MW of wind generation, may not be
built. Plan 3A consists of the following:
1.
2.
3.
4.
5.
6.
7.
Construct a 230 kV “Tonbridge” Switching Station (SS) approximately 10 miles
north of the existing Great Falls 230 kV substation.
Loop the Montana-Alberta (MATL) 230 kV interconnection into the new Tonbridge
230 kV SS.
At the new Tonbridge SS – Add a phase shifting transformer (PST) in the
Tonbridge SS to Great Falls 230 kV circuit to limit power flow into Great Falls.
At the new Tonbridge SS – Install two, 230 kV, 80 MVAR shunt reactors and three,
230 kV, 60 MVAR, capacitor banks for voltage control/support
Construct a 145 mile, single-circuit, 600 MVA, 230 kV transmission line (the Green
Line) from the new Tonbridge SS to the Garrison 500/230 kV substation.
At Garrison add one 500/230 kV transformers to connect to the 230 kV Green Line
to the 500 kV network.
Garrison 230 kV bus - Install two, 230 kV, 80 MAVR shunt reactors and three, 230
kV, 60 MVAR, capacitor banks for voltage control/support.
Green Line Report
Rev B (9-June-11)
Corporate Base
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
G.
PLAN 3 - DETAILED DESCRIPTION
G.1
Plan 3 Summary
Construct a 230 kV “Tonbridge” Switching Station (SS) approximately 10 miles north of the
existing Great Falls 230 kV substation. Loop the Montana-Alberta (MATL) 230 kV
interconnection into the new Tonbridge 230 kV SS and add a phase shifting transformer
(PST) in the Tonbridge SS to Great Falls 230 kV circuit to limit power flow into Great Falls.
Construct a 145 mile, double-circuit, 230 kV transmission line (the Green Line) from the new
Tonbridge SS to the Garrison 500/230 kV substation. At Garrison add two 500/230 kV
transformers to connect to the Green Line to the 500 kV network.
G.2
Plan 3 Details
Plan 3 includes the construction of a new 230 kV Tonbridge Switching Station (SS)
approximately 10 miles north of the existing Great Falls 230 kV substation. The Montana
Alberta 230 kV (MATL) transmission line will be looped into the new 230 kV Tonbridge SS
and a phase shifting transformer (PST) will be installed in the Tonbridge SS to Great Falls
230 kV circuit to limit power flow into Great Falls. A new 145 mile, double-circuit, 230 kV
transmission line (the Green Line) will be constructed from the new 230 kV Tonbridge SS to
the Garrison 500/230 kV substation. At Garrison two 500/230 kV transformers will be added
to connect the Green Line to the 500 kV network.
The Green Line facilities for Plan 3, modelled in the 2014 Light Autumn Load power system
study, included the following:
1.
2.
3.
4.
5.
6.
7.
Green Line Report
Rev B (9-June-11)
Construction of a new Tonbridge 230 kV Switching Station (SS) at a site
approximately ten miles north of Great Falls.
Loop the MATL 230 kV transmission line into the new Tonbridge SS.
Tonbridge SS – Install 230kV Phase-Shifting Transformer (PST) in 230 kV circuit
(MATL) to Great Falls.
Construct a Tonbridge SS-Garrison 230 kV transmission line (double-circuit, two
954,000 ACSR conductors per phase, rated at approximately 1600 MVA).
At Garrison – Add two 500/230 kV transformers.
Tonbridge SS – Add two, 230 kV, 80 MVAR shunt reactors and three, 230 kV, 60
MVAR, capacitor banks for voltage control/support.
Garrison Green Line 230 kV bus - Add two, 230 kV, 80 MVAR shunt reactors
and three, 230 kV, 60 MVAR, capacitor banks for voltage control/support.
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
8.
The Colstrip generation was reduced 950 MW to accommodate the addition of
950 MW of Wind Turbine Generation (WTG).
9. The Wind Turbines for the Hay Lake and the Renewable Collector System
(RCS) were assumed to be Acciona 1530 units with a reactive capacity of +/0.59 MVAR.
10. Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(units 1 and 2 are off-line to accommodate the addition of 950 MW of WTG).
G.3
Plan 3 Impact on Area Voltages
The power system analysis results for indicated that for voltages greater than 1.10 per unit
(PU), in the Montana and Northwestern areas, for the 2014 Light Autumn base case, the
addition of the Green Line, with 950 MW of Wind Turbine Generation (WTG), would have no
significant voltage impact.
The power system analysis results for voltages less than 0.95 per unit (PU), and below, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case, indicated the
addition of the Green Line, with 950 MW of WTG, would have no significant voltage impact.
The power system contingency analysis for voltages less than 0.95 per unit (PU), and below,
in the Montana and Northwestern areas, for the 2014 Light Autumn base case, compared
the impact of an outage of the Garrison-Taft 1 & 2, 500 kV transmission lines, (with Colstrip
ATR), on area voltages, with the Green Line in-service, and with for four different levels of
WTG on-line: 950 MW, 650 MW (300 MW at Hay Lake off), 300 MW (650 MW at RCS off),
and all 950 MW WTG off. The study results indicated an outage of the Garrison- Taft 1 & 2,
500 kV transmission lines, with the Green Line in-service and 950 MW of WTG on-line,
would not have a significant impact on area voltages.
The power system contingency analysis for voltages less than 0.95 per unit (PU), and below,
in the Montana and Northwestern areas, for the 2014 Light Autumn base case, compared
the impact of an outage of the Townsend-Garrison 1 & 2, 500 kV transmission lines, (with
Colstrip ATR), on area voltages with the Green Line in-service, and, for four base cases
different levels of WTG on-line: 950 MW, 650 MW (300 MW at Hay Lake off), 300 MW (650
MW at RCS off), and all 950 MW WTG off. The study results indicated the outage of the
Townsend-Garrison 1 & 2, 500 kV transmission lines, with the Green Line in-service and 950
MW of WTG on-line, would not have a significant impact on area voltages.
G.4
Plan 3 Impact on Area Transmission Services
The power system analysis of the impact of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, indicated there would not be any additional overloaded transmission
Green Line Report
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
facilities, nor, would there be any significant changes in existing overloaded facilities with the
Green Line in-service. The power system analysis included base cases with the Green Line
in-service and with different levels of WTG in-service: 950 MW, 650 MW (300 MW at Hay
Lake off), 300 MW (650 MW at RCS off), and all 950 MW WTG off.
The power system contingency analysis of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, indicated that with
the Green Line in-service, and 950 MW of WTG, and the Garrison-Taft 1 & 2, 500 kV
transmission lines out, (with Colstrip ATR), the Hot Springs 500/230 kV transformer would
overload approximately 117 per cent. The study also indicated tripping the 300 MW of WTG
at Hay Lake off-line, with the Green Line in-service, and, with the Garrison-Taft 1 & 2, 500
kV lines out, the Hot Springs 500/230 kV transformer would still overload approximately 104
per cent. To reduce the power flow in the Hot Springs 500/230 kV transformer below the
Rate A rating of 942 MVA, with the Green Line in-service, and the Garrison-Taft 1 & 2, 500
kV lines out, will require tripping of the 650 MW of WTG in the RCS. The John Day
generation facility 100/13.8 kV step-up transformers, and the 500/100 kV transformers TX3
and TX4, also overloaded approximately 4 percent with the Green Line in-service and for all
levels of WTG. There were no other new overloaded transmission facilities, or, significant
changes in existing overloaded facilities.
The power system contingency analysis of the impact of an outage of the TownsendGarrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated the case with the
Green Line in-service and with 950 MW of WTG would not have any significant transmission
system overloads. The study also looked at the Green Line in-service and with four levels of
WTG on-line: 950 MW, 650 MW (300 MW at Hay lake tripped off), 300 MW (650 MW at RCS
tripped off), and with all 950 MW of WTG off. The John Day generation facility 100/13.8 kV
step-up transformers, and the 500/100 kV transformers TX3 and TX4, overloaded
approximately 4 percent with the Green Line in-service and for all levels of WTG. There
were no other new overloaded transmission facilities, or, significant changes in existing
overloaded facilities.
G.5
Plan 3 Transient Analysis
The initial transient analysis indicated for an outage of the Garrison-Taft, 1 & 2, 500 kV
transmission lines, at a minimum, the RCS 650 MW of WTG will need to be tripped concurrently with the Colstrip units. The existing Western Montana Remedial Action Scheme
(RAS) will need to be revised to include tripping of the 650 MW of WTG in the RCS.
The Initial transient analysis indicated that outages of the Broadview-Townsend, 1 and 2,
500 kV or the Townsend-Garrison, 1 & 2, 500kV transmission lines may not require the
reduction of the 950 MW of WTG.
Green Line Report
Rev B (9-June-11)
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
G.6
Plan 3 Transmission Line Losses
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Hay Lake-Tonbridge)*
299
285
14
4.7 %
Green Line #1 (Tonbridge-Garrison)
463
439
24
5.2 %
Green Line #2 (Tonbridge-Garrison)
463
439
24
5.2 %
Transmission Line
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformers (PST) at Substation
120S.
G.7
Plan 3 Costs
Plan 3 costs are listed in Appendix 1.
G.8
Plan 3 Conclusions
Plan 3 with the proposed new Tonbridge SS-Garrison, double-circuit, 230 kV transmission
line will provide a connection hub for WTG in northern Montana. However, the study results
indicated an outage of Garrison-Taft, 1 & 2, 500 kV transmission lines, will require the RCS,
650 MW of WTG to be tripped to prevent overloading the Hot Springs 500/230 kV
transformer, and maintain system stability. The existing Western Montana Remedial Action
Scheme (RAS) will need to be revised to include tripping the RCS WTG.
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
H.
PLAN 3A - DETAILED DESCRIPTION
H.1
Plan 3A Summary
Plan 3A is a variation of Plan 3 based on the expected available transmission capacity west
of Garrison and the assumption the Renewable Collector System (RCS) 650 MW of wind
generation may not be built. Plan 3A, like Plan 3, would also construct a new 230 kV
“Tonbridge” Switching Station (SS) approximately 10 miles north of the existing Great Falls
230 kV substation, loop the Montana-Alberta (MATL) 230 kV interconnection into the new
Tonbridge 230 kV SS, and add a phase shifting transformer (PST) in the Tonbridge SS to
Great Falls 230 kV circuit to limit power flow into Great Falls.
However, Plan 3 A would construct a 145 mile, single-circuit, 600 MVA, 230 kV (1,590,000
ACSR) transmission line (the Green Line) from the new Tonbridge SS to the Garrison
500/230 kV substation. At the Garrison 500 kV substation, Tonbridge would add one
500/230 kV transformer to connect to the Green Line to the 500 kV network.
H.2
Plan 3A Details
Plan 3A includes the construction of a new 230 kV Tonbridge Switching Station (SS)
approximately 10 miles north of the existing Great Falls 230 kV substation. The Montana
Alberta 230 kV (MATL) transmission line will be looped into the new 230 kV Tonbridge SS
and a phase shifting transformer (PST) will be installed in the Tonbridge SS to Great Falls
230 kV circuit to limit power flow into Great Falls. A new 145 mile, single-circuit, 600 MVA,
230 kV transmission line (the Green Line) will be constructed from the new 230 kV
Tonbridge SS to the Garrison 500/230 kV substation. At Garrison, one 500/230 kV
transformer will be added to connect the Green Line to the 500 kV network.
The Green Line facilities for Plan 3A, as modelled in the 2014 Light Autumn Load power
system study, included the following:
1.
2.
3.
4.
5.
Green Line Report
Rev B (9-June-11)
Construction of a new Tonbridge 230 kV Switching Station (SS) at a site
approximately ten miles north of Great Falls.
Loop the MATL 230 kV transmission line into the new Tonbridge SS.
Tonbridge SS – Install 230kV Phase-Shifting Transformer (PST) in 230 kV circuit
(MATL) to Great Falls.
Construct a Tonbridge SS-Garrison 230 kV transmission line (single-circuit, rated
at approximately 600 MVA – 1,590,000 ACSR conductor).
At Garrison – Add one 500/230 kV transformer, rated approximately 600 MVA.
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
6.
Tonbridge SS – Add two, 230 kV, 80 MAVR shunt reactors and three, 230 kV, 60
MVAR, capacitor banks for voltage control/support.
7. Garrison 500 kV substation Green Line 230 kV bus - Add two, 230 kV, 80 MAVR
shunt reactors and three, 230 kV, 60 MVAR, capacitor banks for voltage
control/support.
8. The Colstrip generation Unit 2 was reduced 330 MW to accommodate the
addition of the Hay Lake 300 MW of Wind Turbine Generation (WTG).
9. The Hay Lake Wind Turbines were assumed to be Acciona 1530 units with a
reactive capacity of +/- 0.59 MVAR.
10. Contingency studies assumed the Colstrip ATR would trip Colstrip units 1, 3, and
4 (unit 2 is off-line to accommodate the addition of Hay Lake 300 MW of WTG).
H.3
Plan 3A Impact on Area Voltages
The power system analysis results for indicated that for voltages greater than 1.10 per unit
(PU), in the Montana and Northwestern areas, for the 2014 Light Autumn base case, with
300 MW of Wind Turbine Generation (WTG) at Hay Lake and a transfer of 300 MW from
Alberta to PGE, the addition of the Green Line, would have no significant high-voltage
impact.
The power system analysis results for voltages less than 0.95 per unit (PU), and below, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case, with 300 MW of
Wind Turbine Generation (WTG) at Hay Lake and a transfer of 300 MW from Alberta to
PGE, indicated the addition of the Green Line, would have no significant low-voltage impact.
The power system contingency analysis results for voltages less than 0.95 per unit (PU),
also included the outage of the Garrison-Taft 1 & 2, 500 kV transmission lines, (with Colstrip
ATR). The contingency analysis examined the voltage impact for the out for three different
system conditions: (1) With 300 MW WTG at Hay Lake, and with a transfer of 300 MW from
Alberta to PGE, (2) With 300 MW WTG at Hay Lake, and (3) With 0 MW WTG at Hay Lake,
and with 0 MW transfer from Alberta to PGE. The study results indicated an outage of the
Garrison- Taft 1 & 2, 500 kV transmission lines, with the Green Line in-service and for each
of the system conditions studied, would not have a significant impact on area low-voltages.
The power system contingency analysis results for voltages less than 0.95 per unit (PU),
also included the outage of the Townsend-Garrison 1 & 2, 500 kV transmission lines, (with
Colstrip ATR). The contingency analysis examined the voltage impact for the out for three
different system conditions: (1) With 300 MW WTG at Hay Lake, and with a transfer of 300
MW from Alberta to PGE, (2) With 300 MW WTG at Hay Lake, and 0 MW transfer from
Alberta to PGE, and (3) With 0 MW WTG at Hay Lake, and with 0 MW transfer from Alberta
to PGE. The study results indicated an outage of the Townsend-Garrison, 1 & 2, 500 kV
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 16
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
transmission lines, with the Green Line in-service and for each of the system conditions
studied, would not have a significant impact on area low-voltages.
H.4
Plan 3A Impact on Area Transmission Services
The power system analysis of the impact of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, indicated there would not be any additional overloaded transmission
facilities, nor, would there be any significant changes in existing overloaded facilities with the
Green Line in-service. The power system analysis included base cases with the Green Line
in-service and with three different system conditions: (1) With 0 MW WTG at Hay Lake, and
with 0 MW transfer from Alberta to PGE, (2) With 300 MW WTG at Hay Lake, and 0 MW
transfer Alberta to PGE, (3) With 300 MW WTG at Hay Lake, and 300 MW transfer Alberta
to PGE.
The power system contingency analysis of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, included the
outage of the Garrison-Taft 1 & 2, 500 kV transmission lines, (with Colstrip ATR). The
contingency analysis included cases with the proposed Green Line in-service and the
Garrison-Taft 1&2, 500 kV lines outaged, for three different system conditions: (1) With 300
MW WTG at Hay Lake and 300 MW transfer Alberta to PGE, (2) With 300 MW WTG at Hay
Lake, and 0 MW transfer Alberta to PGE, (3) With 0 MW WTG at Hay Lake, and with 0 MW
transfer from Alberta to PGE. The results of the contingency studies, with the Green Line inservice, and with an outage of the Garrison-Taft 1&2, 500 kV lines, for the system conditions
studied, indicated there would not be any new overloaded transmission facilities, or,
significant changes in existing overloaded facilities.
The power system contingency analysis of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, included the
outage of the Townsend-Garrison 1 & 2, 500 kV transmission lines, (with Colstrip ATR). The
contingency analysis included cases with the proposed Green Line in-service and the
Townsend-Garrison 1&2, 500 kV lines outaged, for three different system conditions: (1)
With 300 MW WTG at Hay Lake and 300 MW transfer Alberta to PGE, (2) With 300 MW
WTG at Hay Lake, and 0 MW transfer Alberta to PGE, (3) With 0 MW WTG at Hay Lake,
and with 0 MW transfer from Alberta to PGE. The results of the contingency studies, with
the Green Line in-service, and with an outage of the Townsend-Garrison 1&2, 500 kV lines,
for the system conditions studied, indicated there would not be any new overloaded
transmission facilities, or, significant changes in existing overloaded facilities.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 17
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
H.5
Plan 3A Transient Analysis
The initial transient analysis indicated that for an outage of the Garrison-Taft, 1 & 2, 500 kV
transmission lines, or the Townsend-Garrison, 1 & 2, 500kV transmission lines, with the
Colstrip ATR in effect, the generation at Hay Lake would remain stable.
H.6
Plan 3A Transmission Line Losses
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (MATL120S-Hay Lake)*
196
191
14
2.6 %
MATL (Hay Lake-Tonbridge)*
491
452
39
7.9 %
Green Line (Tonbridge-Garrison)
452
414
38
8.4 %
Transmission Line
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformers (PST) at Substation
120S.
H.7
Plan 3A Costs
Plan 3A costs are listed in Appendix 1.
H.8
Plan 3A Conclusions
Plan 3A with the proposed new Tonbridge SS-Garrison, single-circuit, 230 kV, 600 MVA,
transmission line will provide a path for WTG in northern Montana to be connected into the
500 kV network. The study results indicated that an outage of either the Garrison-Taft, 1 &
2, 500 kV transmission lines, or the Townsend-Garrison1 &2, 500 kV lines, with the green
Line in-service, with 300 MW of WTG at Hay Lake, and a 300 MW transfer from Alberta to
PGE, would not significantly impact the Montana or Northwestern systems.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 18
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
I.
CONCLUSION AND RECOMMENDATIONS
Based on the results of this study, Plan 3 would be the preferred alternative. Plan 3
includes the construction of a new Tonbridge 230 kV Switching Station (SS) and the
construction of a 145 mile, 1600 MVA, 230 kV transmission line (Green Line) from the new
Tonbridge SS to Garrison. At Garrison, Tonbridge will install two 500/230 kV transformers to
connect the Green Line to the 500 kV network. The interconnection at Garrison will
eliminate or sustainably reduce the impact of outages of the Broadview-Townsend 1 & 2,
and the Townsend-Garrison 1 & 2, 500 kV lines. The new Tonbridge SS will serve as a hub
for the 300 MW of wind turbine generation at Hay Lake and the 650 MW of wind turbine
generation in the Renewable Collector System (RCS) in northern Montana.
However, recent information indicated the proposed RCS facility may not be built. Based on
that information, Plan 3A would be the preferred alternative. The Plan 3A Green Line
consists of a 145 mile, single-circuit, 600MVA, 230 kV transmission line and will require only
one 500/230 kV transformer at the Garrison 500 kV substation.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 19
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
J.
SWITCHING STUDY
A Switching Study was performed to determine the voltage increase or decrease caused by
switching the capacitors and reactors associated with the MATL, the Green Line, and the
Tonbridge Switching Station (SS). The results of the Switching study for the Marias 230 kV
bus, the Tonbridge SS 230 kV bus, and the Green Line 230 kV bus at Garrison are tabulated
below.
MARIAS SWITCHING STATION
BUS
NAME
BASE CASE
NO
CAP/REACTOR
SWITCH
SWITCH
SWITCH
160 MVAR CAP
BK
80 MVAR CAP BK
60 MVAR CAP BK
VOLT (PU)
VOLT
(PU)
DELTA
(PU)
VOLT
(PU)
DELTA
(PU)
VOLT
(PU)
DELTA
(PU)
MARIAS_N
230KV
1.2171
1.4354
0.2183
1.3202
0.1031
1.2934
0.0763
MARIAS
1.0129
1.1131
0.1002
1.0609
0.0480
1.0485
0.0356
MARIAS_S
230KV
1.0274
1.1577
0.1303
1.0896
0.0622
1.0735
0.0461
The Switching Study results for the Marias Switching Station are tabulated on the above
table. As can be seen on the table, switching a 160 MVAR capacitor bank at the Marias 230
kV bus will cause a voltage rise of 21.8 % on the Marias_N 230 kV bus, 10 % on Marias,
and 13 % on Marias_S. Switching a 80 MVAR capacitor bank instead of the 160 MVAR
bank will cause voltage increases of 10.3 % on the Marias_N 230 kV bus, 4.8 % on Marias,
and 6.2 % on Marias_S. Switching a 60 MVAR capacitor bank instead of the 160 MVAR
bank will cause voltage increases of 7.6 % on the Marias_N 230 kV bus, 3.6 % on Marias,
and 4.6 % on Marias_S.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 20
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
TONBRIDGE SWITCHING STATION
BUS NAME
BASE CASE
NO
CAP/REACTOR
SWITCH
SWITCH
60 MVAR CAP
BK
80 MVAR LINE
REACTOR
VOLT (PU)
VOLT
(PU)
DELT
A (PU)
VOLT
(PU)
DELTA
(PU)
TONBRIDGE
SS 230KV
0.9604
0.9920
0.0316
0.9211
-0.0393
GF PST
0.9351
0.9539
0.0188
0.9118
-0.0233
MARIAS_S
230KV
1.1306
1.1340
0.0034
1.1262
-0.0044
MARIAS
230KV
1.0398
1.0588
0.0190
1.0161
-0.0237
MARIAS_N
230KV
1.0920
1.1368
0.0448
1.0369
-0.0551
The Switching Study results for the Tonbridge Switching Station are tabulated on the above
table. As can be seen on the table, switching a 60 MVAR capacitor bank at the Tonbridge
SS 230 kV bus will cause a voltage rise of approximately 3.2 %. Likewise, switching an 80
MVAR line reactor will decrease the Tonbridge 230 kV bus voltage by 3.9 %.
GREEN LINE 230KV BUS AT GARRISON 500 KV SUBSTATION
BUS NAME
GRN LINE
230KV
Green Line Report
Rev B (9-June-11)
BASE CASE NO
CAP/REACTOR
SWITCH
SWITCH
60 MVAR CAP
BK
80 MVAR LINE
REACTOR
VOLT (PU)
VOLT
(PU)
DELT
A (PU)
VOLT
(PU)
DELTA
(PU)
1.0070
1.027
8
0.0208
0.9806
-0.0264
Corporate Base
Page 21
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
GARRISON
500KV
1.0695
1.077
4
0.0079
1.0593
-0.0102
TONBRIDGE
SS 230KV
1.0039
1.008
2
0.0043
0.9985
-0.0054
The Switching Study results for the Tonbridge Green Line 230 kV bus at the Garrison 500
kV substation are tabulated on the above table. As can be seen on the table, switching a 60
MVAR capacitor bank at the Green Line 230 kV bus at Garrison will cause a voltage rise of
approximately 2.1 %. Likewise, switching an 80 MVAR line reactor will decrease the Green
Line 230 kV bus at Garrison voltage by 2.6 %.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 22
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
K.
REFERENCES
“The Green Line Pre-Feasibility Study”, Prepared by Big Sky Green Power, Spring 2010.
The “Line Load Interconnection Feasibility Study (LLFES) for Requests L0314 and L0315
Agreement Nos. 10TX-14636 & 10TX-14637”, Prepared by the Bonneville Power
Administration November 15, 2010.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 23
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Appendix 1 -
Green Line Report
Rev B (9-June-11)
Plan Costs
Corporate Base
Page 24
Project: Tonbridge
Location: Montana
Plan No
Initial Cost Comparison
1
2
3
3A
4
5
6
7
8
9
6/7/2011 / 9:42 AM
Date: May 2011
Appendix 1
$260,140,608
$301,228,432
$272,140,608
$259,635,608
$313,228,432
$260,645,608
$301,733,432
$373,840,608
$403,928,432
$343,635,608
1 of 1
Report Spreadsheets RR2.xls
Project: Tonbridge
Location: Montana
Cost per unit
$
$
$
$
$
$
$
$
$
$
$
$
$
6/7/2011 / 9:47 AM
Date: May 2011
Appendix 1
1,200,000
12,000,000
505,000
2,625,108
4,000,000
2,100,000
146,000
2,444,000
756,000
1,495,000
1,384,000
1,560,000
10,120,500
Unit
Mile
Transformer
Breaker (230 kV)
Breaker (500 kV)
Reactor (80 MVAR)
Reactor (60 MVAR)
Garrison Substation
Fiber Optic Repeater Stations
Great Falls Substation
Hay Lake WTG (300MW)
RCS Site A
RCS Site B
Total Comm & Control with OH’s
1 of 1
Report Spreadsheets RR2.xls
Two 230 kV PCB’s at Garrison
One 500 kV PCB at Garrison (with OH’s)
Add two 230kV, 80 MVAR Reactors at Garrison
Add two 230kV, 80 MVAR Reactors at Great Falls
Add three 230kV, 60 MVAR Capacitor banks at Garrison
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Great
Falls
$146,000 Garrison Substation
$2,444,000 Fiber Optic Repeater Stations
$756,000 Great Falls Substation
$1,495,000 Hay Lake WTG (300MW)
$1,384,000 RCS Site A
$1,560,000 RCS Site B
$10,120,500 Total Comm & Control with OH’s
$260,140,608
$1,010,000
$2,625,108
$8,000,000
$8,000,000
$6,300,000
6/7/2011 / 9:42 AM
1 of 1
Notes
1
Costs estimated by Bonneville Power Administration (BPA).
2013
2013
2013
2013
2013
2013
Total:
TOTAL
2013
2013
2013
2013
2013
2013
$174,000,000 Construct 145 mile, 230 kV transmission line
$12,000,000 Construct 230 kV Switchyard at Great Falls
$24,000,000 Add two 500/230 kV transformers at Garrison
2013
2013
2013
ITEM
COST
Appendix 1
YEAR
Plan 1
Project: Tonbridge
Location: Montana
1
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
Comm. & Control Equip. Req’d by BPA
Green Line - Great Falls to Garrison 230 kV
Connect to existing Great Falls sub via jumpers
ITEM DESCRIPTION
Date: May 2011
$2,404,000
$2,444,000
$889,000
$1,495,000
$1,384,000
$1,560,000
$30,784,000
$301,228,432
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
Construct 115 mile, 230 kV transmission line
Construct 230 kV Switchyard at Great Falls
Add 2,500/230 kV transformers at Townsend
Add two 230 kV PCB’s at Townsend
Construct a 500 kV, 8 PCB, substation at Townsend (with
OH’s)
Add two 80 MVAR Reactors at Garrison
Add two 80 MVAR Reactors at Great Falls
Add three 60 MVAR Capacitor banks at Garrison
Add three 60 MVAR Capacitor banks at Great Falls
Garrison Substation
Typical MW repeaters for SONET loop Garrison to
Townsend
Townsend Sub
Fiber Optics Townsend to Great Falls
Great Falls Substation
Hay Lake WTG (300MW)
RCS Site A
RCS Site B
Total Comm & Control with OH’s
ITEM
Appendix 1
6/7/2011 / 9:43 AM
1 of 1
Costs estimated by Bonneville Power Administration (BPA).
$8,000,000
$8,000,000
$6,300,000
$6,300,000
$868,000
$12,636,000
2013
2013
2013
2013
2013
2013
Notes
1
$138,000,000
$12,000,000
$24,000,000
$1,010,000
$43,154,432
COST
2013
2013
2013
2013
2013
YEAR
Plan 2
Project: Tonbridge
Location: Montana
Communication & Control
1
1
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
Green Line - Great Falls to Garrison 230 kV
ITEM DISC
Date: May 2011
Appendix 1
1 of 1
COST
ITEM
$174,000,000 Construct 145 mile, 230 kV transmission line
$12,000,000 Construct Tonbridge 230 kV Switching Station (SS) 10 miles north
of Great Falls
$12,000,000 Install 230 kV Phase-shifting transformer at Tonbridge SS
$24,000,000 Add two 500/230 kV transformers at Garrison
$1,010,000 Add two 230 kV PCB’s at Garrison
$2,625,108 One 500 kV PCB at Garrison (with OH’s)
$8,000,000 Add two 230kV, 80 MVAR Reactors at Garrison
$8,000,000 Add two 230kV, 80 MVAR Reactors at Tonbridge SS
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Garrison
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Tonbridge SS
$146,000 Garrison Substation
$2,444,000 Fiber Optic Repeater Stations
$756,000 Great Falls Substation
$1,495,000 Hay Lake WTG (300MW)
$1,384,000 RCS Site A
$1,560,000 RCS Site B
$10,120,500 Total Comm & Control with OH’s
$272,140,608
Costs estimated by Bonneville Power Administration (BPA).
6/7/2011 / 9:44 AM
Notes
1
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
YEAR
2013
2013
Plan 3
Project: Tonbridge
Location: Montana
Communication & Control
1
1
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
Install in 230kV connection to Great Falls
ITEM DESCRIPTION
Green Line – Tonbridge SS to Garrison 230 kV
New Tonbridge 230 kV Switching Station
Date: May 2011
Notes
1
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
YEAR
2013
2013
COST
ITEM
$174,000,000 Construct 145 mile, 230 kV transmission line
$12,000,000 Construct Tonbridge 230 kV Switching Station (SS) 10 miles north
of Great Falls
$12,000,000 Install 230 kV Phase-shifting transformer at Tonbridge SS
$12,000,000 Add one 500/230 kV transformer at Garrison
$505,000 Add one 230 kV PCB at Garrison
$2,625,108 One 500 kV PCB at Garrison (with OH’s)
$8,000,000 Add two 230kV, 80 MVAR Reactors at Garrison
$8,000,000 Add two 230kV, 80 MVAR Reactors at Tonbridge SS
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Garrison
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Tonbridge SS
$146,000 Garrison Substation
$2,444,000 Fiber Optic Repeater Stations
$756,000 Great Falls Substation
$1,495,000 Hay Lake WTG (300MW)
$1,384,000 RCS Site A
$1,560,000 RCS Site B
$10,120,500 Total Comm & Control with OH’s
$259,635,608
Costs estimated by Bonneville Power Administration (BPA).
Plan 3A
Communication & Control
Install in 230kV connection to Great Falls
ITEM DESCRIPTION
Green Line – Tonbridge SS to Garrison 230 kV
New Tonbridge 230 kV Switching Station
1
1
1
1
1
1
1
1
Notes
6/7/2011 / 9:44 AM
Appendix 1
1 of 1
Construct 115 mile, 230 kV transmission line
Construct new 230 kV Tonbridge Switching Station
Add 230kV PST in circuit to Great falls
Add two 500/230 kV transformers at Townsend
Add two 230 kV PCB’s at Townsend
Construct a 500 kV, 8 PCB, substation at Townsend (with OH’s)
Add two 230kV, 80 MVAR Reactors at Townsend
Add two 230kV, 80 MVAR Reactors at Great Falls
Add three 230kV, 60 MVAR Capacitor banks at Townsend
Add three 230kV, 60 MVAR Capacitor banks at Great Falls
Garrison Substation
Typical MW repeaters for SONET loop Garrison to Townsend
Townsend Sub
Fiber Optics Townsend to Great Falls
Great Falls Substation
Hay Lake WTG (300MW)
RCS Site A
RCS Site B
Total Comm & Control with OH’s
ITEM
Costs estimated by Bonneville Power Administration (BPA).
$138,000,000
$12,000,000
$12,000,000
$24,000,000
$1,010,000
$43,154,432
$8,000,000
$8,000,000
$6,300,000
$6,300,000
$868,000
$12,636,000
$2,404,000
$2,444,000
$889,000
$1,495,000
$1,384,000
$1,560,000
$30,784,000
$313,228,432
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
Notes
1
COST
YEAR
Plan 4
Project: Tonbridge
Location: Montana
Communication & Control
1
1
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
Green Line – Tonbridge SS to Townsend 230 kV
New Tonbridge SS, 10 miles north of Great Falls
ITEM DISC
Date: May 2011
Costs estimated by Bonneville Power Administration (BPA).
6/7/2011 / 9:44 AM
Notes
1
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
1 of 1
$174,000,000 Construct 145 mile, 230 kV transmission line
$12,000,000 Construct Tonbridge 230 kV Switching Station (SS) 10 miles north of
Great Falls
$505,000 Install 230 kV PCB at Tonbridge SS
$24,000,000 Add two 500/230 kV transformers at Garrison
$1,010,000 Add two 230 kV PCB’s at Garrison
$2,625,108 One, 500 kV PCB at Garrison (with OH’s)
$8,000,000 Add two 230kV, 80 MVAR Reactors at Garrison
$8,000,000 Add two 230kV, 80 MVAR Reactors at Tonbridge SS
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Garrison
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Tonbridge SS
$146,000 Garrison Substation
$2,444,000 Fiber Optic Repeater Stations
$756,000 Great Falls Substation
$1,495,000 Hay Lake WTG (300MW)
$1,384,000 RCS Site A
$1,560,000 RCS Site B
$10,120,500 Total Comm & Control with OH’s
$260,645,608
2013
2013
ITEM
COST
Appendix 1
YEAR
Plan 5
Project: Tonbridge
Location: Montana
Communication & Control
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
Install in 230kV connection to Great Falls
Green Line – Tonbridge SS to Garrison 230 kV
New Tonbridge 230 kV Switching Station
ITEM DISC
Date: May 2011
2013
2013
2013
2013
Total:
TOTAL:
6/7/2011 / 9:45 AM
1 of 1
$2,404,000
$2,444,000
$889,000
$1,495,000
$1,384,000
$1,560,000
$30,784,000
$301,733,432
Costs estimated by Bonneville Power Administration (BPA).
Townsend Sub
Fiber Optics Townsend to Great Falls
Great Falls Substation
Hay Lake WTG (300MW)
RCS Site A
RCS Site B
Total Comm & Control with OH’s
$8,000,000
$8,000,000
$6,300,000
$6,300,000
$868,000
$12,636,000
2013
2013
2013
2013
2013
2013
Notes
1
Construct 115 mile, 230 kV transmission line
Construct new 230 kV Tonbridge SS
Install 230 kV PCB at Tonbridge SS
Add two 500/230 kV transformers at Townsend
Add two 230 kV PCB’s at Townsend
Construct a 500 kV, 8 PCB, substation at Townsend (with
OH’s)
Add two 230kV, 80 MVAR Reactors at Townsend
Add two 230kV, 80 MVAR Reactors at Tonbridge SS
Add three 230kV, 60 MVAR Cap banks at Townsend
Add three 230kV, 60 MVAR Cap banks at Tonbridge SS
Garrison Substation
Typical MW repeaters for SONET loop Garrison to Townsend
ITEM
$138,000,000
$12,000,000
$505,000
$24,000,000
$1,010,000
$43,154,432
COST
Appendix 1
2013
2013
2013
2013
2013
2013
YEAR
Plan 6
Project: Tonbridge
Location: Montana
Communication & Control
1
1
1
1
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
Green Line – Tonbridge SS to Townsend 230 kV
New Tonbridge SS, 10 miles north of Great Falls
Install in 230kV connection to Great Falls
ITEM DISC
Date: May 2011
ITEM
Appendix 1
1 of 1
$290,000,000 Construct 145 mile, 500 kV transmission line
$12,000,000 Construct Tonbridge 230 kV Switching Station (SS) 10 miles north
of Great Falls
$12,000,000 Install 230 kV Phase-shifting transformer at Tonbridge SS
$24,000,000 Add two 500/230 kV transformers at Tonbridge SS
$1,010,000 Add two additional 230 kV PCB’s at Tonbridge SS
$2,625,108 One 500 kV PCB at Garrison (with OH’s)
$8,000,000 Add two 230kV, 80 MVAR Reactors at Tonbridge SS
$6,300,000 Add three 230kV, 60 MVAR Capacitor banks at Tonbridge SS
$146,000 Garrison Substation
$2,444,000 Fiber Optic Repeater Stations
$756,000 Great Falls Substation
$1,495,000 Hay Lake WTG (300MW)
$1,384,000 RCS Site A
$1,560,000 RCS Site B
$10,120,500 Total Comm & Control with OH’s
$373,840,608
COST
Costs estimated by Bonneville Power Administration (BPA).
6/7/2011 / 9:45 AM
Notes
1
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
2013
2013
YEAR
Plan 7
Project: Tonbridge
Location: Montana
Communication & Control
Install in 230kV circuit to Great Falls
1
1
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
Green Line – Tonbridge SS to Garrison 500 kV
New Tonbridge 230 kV Switching Station
ITEM DISC
Date: May 2011
$2,404,000
$2,444,000
$889,000
$1,495,000
$1,384,000
$1,560,000
$30,784,000
$403,928,432
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
6/7/2011 / 9:46 AM
Appendix 1
Townsend Sub
Fiber Optics Townsend to Great Falls
Great Falls Substation
Hay Lake WTG (300MW)
RCS Site A
RCS Site B
Total Comm & Control with OH’s
1 of 1
Add two 500 kV, 120 MVAR Reactors at Townsend
Add two 230 kV, 80 MVAR Reactors at Tonbridge SS
Add three 230kV, 60 MVAR Cap banks at Tonbridge SS
Garrison Substation
Typical MW repeaters for SONET loop Garrison to Townsend
ITEM
Construct 115 mile, 500 kV transmission line
Construct new 230 kV Tonbridge SS
Add 2,500/230 kV transformers at Tonbridge SS
Install 230 kV Phase-shifting transformer at Tonbridge SS
Add two additional 230 kV PCB’s at Tonbridge SS
Construct a 500 kV, 8 PCB, substation at Townsend (with OH’s)
Costs estimated by Bonneville Power Administration (BPA).
$13,000,000
$8,000,000
$6,300,000
$868,000
$12,636,000
2013
2013
2013
2013
2013
Notes
1
COST
$230,000,000
$12,000,000
$24,000,000
$12,000,000
$1,010,000
$43,154,432
YEAR
2013
2013
2013
2013
2013
2013
Plan 8
Project: Tonbridge
Location: Montana
Communication & Control
Install in 230kV circuit to Great Falls
1
1
1
1
1
1
1
1
1
1
Notes
Report Spreadsheets RR2.xls
ITEM DESCRIPTION
Green Line – Tonbridge SS to Townsend 500 kV
New Tonbridge SS, 10 miles north of Great Falls
Date: May 2011
Notes
1
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
2013
Total:
TOTAL:
2013
YEAR
2013
2013
Plan 9
Loop Bole-Conrad 230 kV line into Tonbrideg/Marias SS
Add one 500/230 kV transformer at Garrison
Add one 230 kV PCB at Garrison
One 500 kV PCB at Garrison (with OH’s)
Add two 230kV, 80 MVAR Reactors at Garrison
Add two 230kV, 80 MVAR Reactors at Tonbridge SS
Add three 230kV, 60 MVAR Capacitor banks at Garrison
Add three 230kV, 60 MVAR Capacitor banks at Tonbridge SS
Garrison Substation
Fiber Optic Repeater Stations
Great Falls Substation
Hay Lake WTG (300MW)
RCS Site A
RCS Site B
Total Comm & Control with OH’s
Costs estimated by Bonneville Power Administration (BPA).
$12,000,000
$12,000,000
$505,000
$2,625,108
$8,000,000
$8,000,000
$6,300,000
$6,300,000
$146,000
$2,444,000
$756,000
$1,495,000
$1,384,000
$1,560,000
$10,120,500
$343,635,608
COST
ITEM
$246,000,000 Construct 220 mile, 230 kV transmission line
$12,000,000 Construct Tonbridge/Marias 230 kV Switching Station (SS) at
Marias 85 miles north of Great Falls
$12,000,000 Install 230 kV Phase-shifting transformer at Tonbridge/Marias SS
Communication & Control
Install in MATL 230kV connection to Great Falls
ITEM DESCRIPTION
Green Line – Tonbridge SS to Garrison 230 kV
New Tonbridge 230 kV Switching Station
1
1
1
1
1
1
1
1
Notes
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Appendix 2 -
Green Line Report
Rev B (9-June-11)
Plan Sketches
Corporate Base
Page 26
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Appendix 3 Layouts
Green Line Report
Rev B (9-June-11)
Preliminary 230 kV Switching Station
Corporate Base
Page 27
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Appendix 4 - Alternate Plans For Connecting Green Line
to Garrison or Townsend
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 28
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 1 - DETAILED DESCRIPTION
Plan 1 Summary
Construct a 145 mile, double circuit, 230 kV transmission line (the Green Line) from the
Great Falls 230 kV substation to the Garrison 500 kV substation. At Garrison add two
500/230 kV transformers to connect the Green Line to the 500 kV network.
At the Great Falls 230 kV substation, construct a new 230 kV switchyard adjacent to the
existing Great Falls switch yard and connect the new 230 kV switch yard to the existing
Great Falls 230 kV switch yard using 230 kV jumpers. Terminate the new Green Line in the
new 230 kV switch yard at Great Falls.
Plan 1 Details
Plan 1 includes the construction of a 145 mile, double-circuit, 230 kV transmission line from
the existing Great Falls 230 kV substation to the Garrison 500 kV substation. The new
transmission line, referred to as the “Green Line”, will provide a path for renewable energy
from wind generation facilities in Montana to the northwest power grid. The Green Line
facilities for Plan 1 as modelled in the 2014 Light Autumn Load base case included the
following:
1. Construction of a new 230 kV switchyard at Great Falls connected to existing
Great Falls 230 Substation via jumpers.
2. Construction of a 230 kV transmission line (Green Line) from Great Falls to
Garrison 500 kV substation.
3. Construction of a new Great Falls to Garrison 230 kV transmission line assumed
to be a double-circuit, two 954,000 ACSR conductors per phase, rated at
approximately 1600 MVA.
4. At Great Falls - Add two, 230 kV, 80 MVAR shunt reactors and three, 230 kV, 60
MVAR, capacitor banks for voltage control/support.
5. At Garrison 500 kV sub – Add two 500/230 kV transformers.
6. At new Garrison Green Line 230 kV bus - Add two, 230 kV, 80 MVAR shunt
reactors and three, 230 kV, 60 MVAR, capacitor banks for voltage
control/support.
7. The Colstrip generation was reduced 950 MW to accommodate the addition of
950 MW of Wind Turbine Generation (WTG).
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 29
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
8. The Wind Turbines for the Hay Lake and the Renewable Collector System (RCS)
were assumed to be Acciona 1530 units with a reactive capacity of +/- 0.59
MVAR.
9. Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(Colstrip units 1 and 2 are off-line to accommodate the addition of 950 MW of
WTG).
Plan 1 Impact on Area Voltages
The power system analysis results for indicated that for voltages greater than 1.10 per unit
(PU), in the Montana and Northwestern areas, for the 2014 Light Autumn base case, the
addition of the Green Line, and 950 MW of Wind Turbine Generation (WTG), would have no
significant voltage impact.
The power system analysis results for voltages less than 0.95 per unit (PU), and below, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case, indicated the
addition of the Green Line, and 950 MW of WTG, would have no significant voltage impact
The power system analysis for voltages less than 0.95 per unit (PU), and below, in the
Montana and Northwestern areas, for the 2014 Light Autumn base case, compared the
impact of an outage of the Garrison-Taft 1 & 2, 500 kV transmission lines, (with Colstrip
ATR), on area voltages, with the Green Line in-service, and with for four different levels of
WTG on-line: 950 MW, 650 MW (300 MW at Hay Lake off), 300 MW (650 MW at RCS off),
and all 950 MW WTG off. The study results indicated an outage of the Garrison- Taft 1 & 2,
500 kV transmission lines, with the Green Line in-service and 950 MW of WTG on-line,
would not have a significant impact on area voltages.
The power system analysis for voltages less than 0.95 per unit (PU), and below, in the
Montana and Northwestern areas, for the 2014 Light Autumn base case, compared the
impact of an outage of the Townsend-Garrison 1 & 2, 500 kV transmission lines, (with
Colstrip ATR), on area voltages with the Green Line in-service, and, for four base cases
different levels of WTG on-line: 950 MW, 650 MW (300 MW at Hay Lake off), 300 MW (650
MW at RCS off), and all 950 MW WTG off. The study results indicated the outage of the
Townsend-Garrison 1 & 2, 500 kV transmission lines, with the Green Line in-service and 950
MW of WTG on-line, would not have a significant impact on area voltages.
Plan 1 Impact on Area Transmission Lines
The power system analysis of the impact of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, indicated there would not be any additional overloaded transmission
facilities, nor, would there be any significant changes in existing overloaded facilities with the
Green Line in-service. The power system analysis included base case with the Green Line
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 30
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
in-service and with different levels of WTG in-service: 950 MW, 650 MW (300 MW at Hay
Lake off), 300 MW (650 MW at RCS off), and all 950 MW WTG off.
The power system contingency analysis of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, indicated that with
the Green Line in-service, with 950 MW of WTG, and the Garrison-Taft 1 & 2, 500 kV
transmission lines out, (with Colstrip ATR), the Hot Springs 500/230 kV transformer would
overload approximately 119 per cent. The study also indicated tripping the 300 MW of WTG
at Hay Lake off-line, with the Green Line in-service and the Garrison-Taft 1 & 2, 500 kV lines
out, the Hot Springs 500/230 kV transformer would still overload approximately 109 per cent.
To totally reduce the power flow in the Hot Springs 500/230 kV transformer below the Rate A
rating of 942 MVA, with the Green Line in-service and the Garrison-Taft 1 & 2, 500 kV lines
out, will require the tripping of the 650 MW of WTG in the RCS. Northwestern’s John Day
generation facility 100/13.8 kV step-up transformers, and the 500/100 kV transformers TX3
and TX4, also overloaded approximately 4 percent with the Green Line in-service and for all
levels of WTG. There were no other new overloaded transmission facilities, or, significant
changes in existing overloaded facilities.
The power system analysis of the impact of an outage of the Townsend-Garrison, 1 & 2, 500
kV transmission lines, (with Colstrip ATR), indicated the case with the Green Line in-service
and with 950 MW of WTG would not have any significant transmission system overloads.
Northwestern’s John Day generation facility 100/13.8 kV step-up transformers, and the
500/100 kV transformers TX3 and TX4, overloaded approximately 4 percent with the Green
Line in-service and for all levels of WTG. There were no other new overloaded transmission
facilities, or, significant changes in existing overloaded facilities.
Plan 1 Transient Analysis
The initial transient analysis indicated for an outage of the Garrison-Taft 1 & 2, 500 kV
transmission lines, at a minimum, the RCS 650 MW of WTG will need to be tripped concurrently with the Colstrip units to maintain system stability. The existing Western Montana
Remedial Action Scheme (RAS) will need to be expanded to include tripping the RCS 650
MW of WTG.
The Initial transient analysis indicated that outages of the Broadview-Townsend, 1 & 2, or
the Townsend-Garrison, 1 & 2, 500kV transmission lines may not require the reduction of
the 950 MW of WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 31
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Plan 1 Transmission LIne Losses
Sending
End
Receivin
g End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Hay Lake-Great Falls)*
299
284
15
5.0 %
Green Line #1 (Great Falls-Garrison)
339
328
11
3.2 %
Green Line #2 (Great Falls-Garrison)
339
328
11
3.2 %
Transmission Line
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 1 Costs
Plan 1 costs are listed in Appendix 1.
Plan 1 Conclusions
Please note: The existing Great Falls 230 kV substation appears to be congested, and,
constructing a new 230 kV switch yard adjacent to the existing switchyard to connect the
proposed Green Line, the 230 kV connections to the Renewable Collector System (RCS),
and the 230 kV MATL may not be feasible.
Plan 1 with the proposed new Great Falls-Garrison, double-circuit, 230 kV transmission line
(Green Line) will provide a connection for WTG in northern Montana. However, for an
outage of Garrison-Taft 1 & 2, 500 kV lines, the 650 MW of WTG at RCS will need to be
tripped to prevent overloading the Hot Springs 500/230 kV transformer, and to maintain
system stability. The existing Western Montana Remedial Action Scheme (RAS) will need to
be revised to include tripping the RCS 650 MW of WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 32
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 2 – DETAILED DESCRIPTION
Construct a 115 mile, double circuit, 230 kV transmission line (the Green Line) from the
Great Falls 230 kV substation to a site near Townsend, MT. At the Townsend site construct
a new 500/230 kV substation to interconnect to the 500 kV network.
At the Great Falls 230 kV substation, construct a new 230 kV switchyard adjacent to the
existing Great Falls 230 kV switch yard and connect the new 230 kV switch yard to the
existing 230 kV switch yard using jumpers. Terminate the new Green Line in the new 230
kV switch yard at Great Falls.
Plan 2 Details
Plan 2 includes the construction of a 115 mile, double-circuit, 230 kV transmission line from
the existing Great Falls 230 kV substation to the a site near Townsend. Currently there is
not an existing 500 kV substation at Townsend. The construction of the Great Falls to
Townsend 230 kV transmission line will require the construction of a new Townsend 500 kV
substation. The new transmission line, referred to as the “Green Line”, will provide a path for
renewable energy from wind generation facilities in Montana to the northwest power grid.
The Green Line facilities for Plan 2 included in the 2014 Light Autumn Load base case
power system study included the following:
1.
2.
3.
4.
5.
6.
7.
8.
Construction of a new 230 kV switchyard at Great Falls connected to existing Great
Falls 230 Substation via jumpers.
Construction of a new Great Falls to Townsend 230 kV transmission line – the
Green Line (double-circuit, two 954,000 ACSR conductors per phase, rated at
approximately 1600 MVA).
To connect the proposed Green Line to the 500 kV network at Townsend, BPA will
require the construction of new, 8 PCB, 500 kV Townsend substation.
At the new Townsend 500 kV substation – Add two, 500/230 kV transformers.
At new Townsend Green Line 230 kV bus - Add two, 230 kV, 80 MVAR shunt
reactors and three, 230 kV, 60 MVAR, capacitor banks for voltage control/support.
At Great Falls – Add two, 230 kV, 80 MVAR shunt reactors and three, 230 kV, 60
MVAR, capacitor banks for voltage control/support.
The Colstrip generation was reduced 950 MW to accommodate the addition of 950
MW of Wind Turbine Generation (WTG).
The Wind Turbines for the Hay Lake and the Renewable Collector System (RCS)
were assumed to be Acciona 1530 units with a reactive capacity of +/- 0.59 MVAR.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 33
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
9.
Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(Colstrip units 1 and 2 are off-line to accommodate the addition of 950 MW of
WTG).
Plan 2 Impact on Area Voltages
The power system analysis results for the proposed Green Line, indicated that for voltages
greater than 1.10 per unit (PU), in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, the addition of the Green Line, with 950 MW of Wind Turbine Generation
(WTG), would have no significant voltage impact. The only significant impacts (changes of
greater than 0.02 PU) on voltages above 1.10 PU occurred on the Marias N and Marias S
230 kV buses and that was a result of the way the MATL was modelled in the base case.
The power system analysis results for the proposed Green Line impact on voltages less than
0.95 per unit (PU), and below, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, indicated the addition of the Green Line, with 950 MW of WTG, would
not have a significant voltage impact
The power system contingency analysis for the proposed Green Line impact on voltages
less than 0.95 per unit (PU), and below, in the Montana and Northwestern areas, for the
2014 Light Autumn base case, indicated an outage of the Garrison-Taft 1 & 2, 500 kV
transmission lines, (with Colstrip ATR), with the Green Line in-service would not have a
significant impact on area voltages. The study also looked at base cases with the Green
Line and with different levels of WTG in-service: 950 MW, 650 MW (300 MW at Hay Lake
off), 300 MW (650 MW at RCS off), and all 950 MW WTG off. The study results indicated
the outage of the Garrison- Taft 1 & 2, 500 kV transmission lines, with the Green Line inservice, would not have a significant impact on area voltages for any level of WTG.
The power system contingency analysis for the proposed Green Line on voltages less than
0.95 per unit (PU), and below, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, and for an outage of the Townsend-Garrison 1 & 2, 500 kV transmission
lines, (with Colstrip ATR), failed to converge with the Green Line in-service and with 950 MW
of WTG. Tripping the 300 MW of WTG at Hay Lake resulted in a solved case, but with
numerous voltage violations. Tripping the 650 MW of WTG at the RCS facility did not have
any significant voltage violations.
Plan 2 – Impact on Area Transmission Facilities
The power system analysis of the impact of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, indicated there would not be any additional overloaded transmission
facilities, nor, would there be any significant changes in existing overloaded facilities with the
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 34
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Green Line in-service. The power system analysis included base cases with the Green Line
in-service, and with different levels of WTG in-service: 950 MW, 650 MW (300 MW at Hay
Lake off), 300 MW (650 MW at RCS off), and all 950 MW WTG off. The study results
indicated there would not be any additional overloaded transmission facilities, nor, would
there be any significant changes in existing overloaded facilities with the Green Line inservice.
The power system contingency analysis of the proposed Green Line, on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, indicated that with
the Green Line in-service, and 950 MW of WTG, and, with the Garrison-Taft 1 & 2, 500 kV
transmission lines out, (with Colstrip ATR), the Hot Springs 500/230 kV transformer would
overload approximately 119 per cent. The study results also indicated that with the Green
Line in-service, and with the Garrison-Taft 1 & 2, 500 kV transmission lines out, tripping the
300 MW of WTG at Hay Lake, the Hot Springs 500/230 kV transformer would overload
approximately 105 per cent. To reduce the loading in the Hot Springs transformer below the
Rate A rating of 942 MVA with the Green Line in-service, and with the Garrison-Taft 1 & 2,
500 kV transmission lines out, will require the tripping of the 650 MW of WTG in the RCS.
Northwestern’s John Day generation facility 100/13.8 kV step-up transformers, and the
500/100 kV transformers TX3 and TX4, also overloaded approximately 4 percent with the
Green Line in-service and for all levels of WTG. There were no other new overloaded
transmission facilities, or, significant changes in existing overloaded facilities.
The power system contingency analysis of the proposed Green Line, on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, indicated that with
the Green Line in-service, and 950 MW of WTG, and, with the Townsend-Garrison 1 & 2,
500 kV transmission lines out, (with Colstrip ATR), the case would not converge indicating
serious system problems. Tripping the 300 MW of WTG at Hay Lake with the Green Line inservice, and with the Townsend-Garrison 1 & 2, 500 kV transmission lines out, overloaded
the Great Falls-Landers Fork-Ovando 230 kV transmission line 120 per cent. Several other
transmission facilities were overloaded also. Tripping the 650 MW of WTG at the RCS, with
the Green Line in-service, and, with Townsend-Garrison 1 & 2, 500 kV transmission lines
out, there were no other new overloaded transmission facilities, or, significant changes in
existing overloaded facilities.
Plan 2 Transient Analysis
The initial transient analysis indicated for an outage of the Garrison-Taft, 1 & 2, 500 kV
transmission lines, or, the Townsend-Garrison, 1 & 2, 500kV transmission lines, at a
minimum, the RCS 650 MW of WTG will need to be tripped con-currently with the Colstrip
units. The existing Colstrip ATR may need to be expanded to include the RCS WTG – or a
separate remedial Action Scheme (RAS) will need to be developed.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 35
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
The Initial transient analysis indicated that outages of the Broadview-Townsend, 1 and 2,
may not require the reduction of the 950 MW of WTG.
Plan 2 Area Losses
Transmission Line
MATL (Hay Lake-Great Falls)*
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
299
284
15
5.0 %
Green Line
Townsend)
#1
(Great
Falls-
371
360
11
3.0 %
Green Line
Townsend)
#2
(Great
Falls-
368
357
11
3.0 %
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 2 Costs
Plan 2 costs are listed in Appendix 1.
Plan 2 Conclusions
Please note: The existing Great Falls 230 kV substation appears to be congested, and,
constructing a new 230 kV switch yard adjacent to the existing switchyard to connect the
proposed Green Line, the 230 kV connection to the Renewable Collector System (RCS),
and the 230 kV MATL (currently under construction) may not be feasible.
Plan 2 with the proposed new Great Falls-Townsend, double-circuit, 230 kV transmission
line will provide a connection for WTG in northern Montana. However, for an outage of
Garrison-Taft, 1 & 2, 500 kV, transmission lines, or, the Townsend-Garrison, 1 & 2, 500kV
transmission lines, the 650 MW of WTG at RCS will need to be tripped to prevent
overloading the Hot Springs 500/230 kV transformer, and to maintain system stability. For
outage of the Broadview-Townsend, 1 & 2, 500 kV circuits tripping the RCS, 650 MW of
WTG at the RCS may not be required. The existing Western Montana Remedial Action
Scheme (RAS) will need to be revised to include tripping the RCS WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 36
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 4 – DETAILED DESCRIPTION
Plan 4 Summary
Construct a 230 kV “Tonbridge” Switching Station (SS) approximately 10 miles north of the
Great Falls 230 kV substation. Loop the MATL line into the new Tonbridge SS and add a
PST in the Tonbridge SS to Great Falls 230 kV circuit to limit power flow into Great Falls.
Construct a 115 mile, double-circuit, 230 kV transmission line (the Green Line) from the new
Tonbridge SS to a site near Townsend. At the Townsend site construct a new 500/230 kV
substation to connect to the Green Line to the 500 kV network.
Plan 4 Details
Plan 4 includes the construction of a new 230 kV Tonbridge Switching Station (SS)
approximately 10 miles north of the existing Great Falls 230 kV substation. The Montana
Alberta 230 kV transmission line (MATL) will be looped into the new 230 kV Tonbridge SS
and a phase shifting transformer (PST) will be installed in the Tonbridge SS to Great Falls
230 kV circuit to limit power flow into Great Falls. A new 115 mile, double-circuit, 230 kV
transmission line (the Green Line) will be constructed from the new 230 kV Tonbridge SS to
the Townsend area. At the Townsend site a new 500 kV, 8 PCB substation will be
constructed. At the new Townsend 500 kV substation, two 500/230 kV transformers will be
installed to connect the Green Line to the 500 kV network (see Figure 4).
The Green Line facilities for Plan 4 included in the 2014 Light Autumn Load power system
study included the following:
1.
2.
3.
4.
5.
6.
7.
Green Line Report
Rev B (9-June-11)
Construct a new Tonbridge Switching Station (SS) 10 miles north of Great Falls.
Loop the MATL 230 kV transmission line into the new Tonbridge SS.
Add a 230 kV Phase-Shifting transformer in the Tonbridge SS to great Falls 230
kV circuit.
Construct a new 230 kV transmission line from the Tonbridge SS to Townsend
(double-circuit, two 954,000 ACSR conductors per phase, rated at
approximately 1600 MVA).
To connect the proposed Green Line to the 500 kV network, BPA will require the
construction of new, Townsend, 8 PCB, 500 kV substation.
At the new Townsend 500 kV substation – Add two 500/230 kV transformers.
At new Tonbridge SS - Add two, 230 kV, 80 MVAR shunt reactors and three, 230
kV, 60 MVAR, capacitor banks for voltage control/support.
Corporate Base
Page 38
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
8.
At new Townsend 500 kV substation 230 kV bus – Add two, 230 kV, 80 MVAR
shunt reactors and three, 230 kV, 60 MVAR, capacitor banks for voltage
control/support.
9. The Colstrip generation was reduced 950 MW to accommodate the addition of
950 MW of Wind Turbine Generation (WTG).
10. The Wind Turbines for the Hay Lake and the Renewable Collector System
(RCS) were assumed to be Acciona 1530 units with a reactive capacity of +/0.59 MVAR.
11. Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(units 1 and 2 are off-line to accommodate the addition of 950 MW of WTG).
Plan 4 Impact on Area Voltages
The power system analysis results for the proposed Green Line, indicated that for voltages
greater than 1.10 per unit (PU), in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, the addition of the Green Line, with 950 MW of Wind Turbine Generation
(WTG), would have no significant voltage impact.
The power system analysis results for the proposed Green Line impact on voltages less than
0.95 per unit (PU), and below, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, indicated the addition of the Green Line, with 950 MW of WTG, would
have no significant voltage impact
The power system contingency analysis for the proposed Green Line impact on voltages
less than 0.95 per unit (PU), and below, in the Montana and Northwestern areas, for the
2014 Light Autumn base case, indicated an outage of the Garrison-Taft 1 & 2, 500 kV
transmission lines, (with Colstrip ATR), with the Green Line in-service would not have a
significant impact on area voltages. The study also looked at base cases with the Green
Line and with different levels of WTG in-service: 950 MW, 650 MW (300 MW at Hay Lake
off), 300 MW (650 MW at RCS off), and all 950 MW WTG off. The study results indicated
the outage of the Garrison- Taft 1 & 2, 500 kV transmission lines, with the Green Line inservice, would not have a significant impact on area voltages for any level of WTG.
The power system contingency analysis for the proposed Green Line on voltages less than
0.95 per unit (PU), and below, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, and for an outage of the Townsend-Garrison 1 & 2, 500 kV transmission
lines, (with Colstrip ATR), indicated there would be large number of voltage violations
(greater than 0.02 per unit) with the Green Line in-service and with 950 MW of WTG on-line.
Tripping the 300 MW of WTG at Hay Lake, with the Green Line in-service, and, with the
Townsend-Garrison 1 & 2, 500 kV lines out, also had numerous voltage violations. Tripping
the 650 MW of WTG at the RCS facility, with the Green Line in and with Townsend-Garrison
1 & 2 out, did not have any significant voltage violations.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 39
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Plan 4 Impact on Area Transmission Services
The power system analysis of the impact of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case, indicated there would not be any additional overloaded transmission
facilities, nor, would there be any significant changes in existing overloaded facilities with the
Green Line in-service. The power system analysis included base cases with the Green Line
in-service, and with different levels of WTG in-service: 950 MW, 650 MW (300 MW at Hay
Lake off), 300 MW (650 MW at RCS off), and all 950 MW WTG off. The study results
indicated there would not be any additional overloaded transmission facilities, nor, would
there be any significant changes in existing overloaded facilities with the Green Line inservice.
The power system contingency analysis of the proposed Green Line, on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, indicated that with
the Green Line in-service, and 950 MW of WTG, and, with the Garrison-Taft 1 & 2, 500 kV
transmission lines out, (with Colstrip ATR), the Hot Springs 500/230 kV transformer would
overload approximately 118 per cent. The study results also indicated that with the Green
Line in-service, and with the Garrison-Taft 1 & 2, 500 kV transmission lines out, tripping the
300 MW of WTG at Hay Lake, the Hot Springs 500/230 kV transformer would overload
approximately 104 per cent. To reduce the loading in the Hot Springs transformer below the
Rate A rating of 942 MVA with the Green Line in-service, and with the Garrison-Taft 1 & 2,
500 kV transmission lines out, will require the tripping of the 650 MW of WTG in the RCS.
The John Day generation facility 100/13.8 kV step-up transformers, and the 500/100 kV
transformers TX3 and TX4, also overloaded approximately 4 percent with the Green Line inservice and for all levels of WTG. There were no other new overloaded transmission
facilities, or, significant changes in existing overloaded facilities.
The power system contingency analysis of the proposed Green Line, on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, indicated that with
the Green Line in-service, and 950 MW of WTG, and, with the Townsend-Garrison 1 & 2,
500 kV transmission lines out, (with Colstrip ATR), indicated there would a number of
overloads in Montana. Tripping the 300 MW of WTG at Hay lake with the Green Line inservice, and, with the Townsend-Garrison 1 & 2, 500 kV transmission lines out, eliminated
most of the overloads. Several other transmission facilities were overloaded also. Tripping
the 650 MW of WTG at the RCS, with the Green Line in-service, and, with TownsendGarrison 1 & 2, 500 kV transmission lines out, indicated there would be no new overloaded
transmission facilities, or, significant changes in existing overloaded facilities.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 40
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Plan 4 Transient Analysis
The initial transient analysis indicated for an outage of the Townsend-Garrison, 1 & 2, 500
kV transmission lines, or the Townsend-Garrison, 1 & 2, 500 kV, at a minimum, the RCS 650
MW of WTG will need to be tripped con-currently with the Colstrip units. The existing
Western Montana Remedial Action Scheme (RASR) will need to be revised to include
tripping of the RCS WTG.
The Initial transient analysis indicated that outages of the Broadview-Townsend, 1 & 2, may
not require the reduction of the 950 MW of WTG.
Plan 4 Transmission Line Losses
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Hay Lake-Tonbridge)*
299
285
14
4.7 %
Green
Line
Townsend)
#1
(Tonbridge-
463
446
17
3.7 %
Green
Line
Townsend)
#2
(Tonbridge-
463
446
17
3.7 %
Transmission Line
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 4 Costs
Plan 4 costs are listed in Appendix 1.
Plan 4 Conclusions
Plan 4 with the proposed new Tonbridge Switching Station and the Tonbridge SSTownsend, double-circuit, 230 kV transmission line will provide a connection for WTG in
northern Montana. However, for an outage of Townsend-Garrison, 1 & 2, 500 kV
transmission lines, or, the Townsend-Garrison, 1 & 2, 500 kV transmission lines, the 650
MW of WTG at RCS will need to be tripped to prevent overloading the Hot Springs 500/230
kV transformer and maintain system stability. For outage of the Broadview to Townsend 500
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 41
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
kV circuits 1 and 2, tripping the 650 MW of WTG at RCS may not be required. The existing
Western Montana Remedial Action Scheme (RAS) will need to be revised to include tripping
the RCS WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 42
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 7 - DETAILED DESCRIPTION
Plan 7 Details
Construct a 230 kV “Tonbridge” Switching Station (SS) approximately 10 miles north of the
Great Falls 230 kV substation. Loop the MATL line into the new Tonbridge 230 kV SS and
add a PST in the Tonbridge SS to Great Falls 230 kV circuit to limit power flow into Great
Falls.
Install two 500/230 kV transformers in the Tonbridge SS and construct a 145 mile, 500 kV,
transmission line (the Green Line) from the Tonbridge SS to the Garrison 500 kV substation
and connect to the Garrison 500 kV bus.
Plan 7 Details
Plan 7 includes the construction of a new 230 kV Tonbridge Switching Station (SS)
approximately 10 miles north of the existing Great Falls 230 kV substation. The Montana
Alberta 230 kV transmission line (MATL) will be looped into the new 230 kV Tonbridge SS
and a phase shifting transformer (PST) will be installed in the Tonbridge SS to Great Falls
230 kV circuit to limit power flow into Great Falls. A new 145 mile, 500 kV transmission line
(the Green Line) will be constructed from the new 230 kV Tonbridge SS to the Garrison
500/230 kV substation. At the Tonbridge SS, two 500/230 kV transformers will be added to
connect to the 500 kV Green Line.
The Green Line facilities for Plan 7, included in the 2014 Light Autumn Load power system
study, included the following:
1.
2.
3.
4.
5.
6.
7.
Green Line Report
Rev B (9-June-11)
Construct a new Tonbridge 230 kV Switching Station (SS) approximately ten
miles north of Great Falls.
Loop the MATL 230 kV transmission line into the new Tonbridge SS.
Install a 230 kV PST in the Tonbridge SS to Great Falls 230 kV circuit.
The Tonbridge SS to Garrison 500kV transmission line was assumed to be a
single-circuit, three 954,000 ACSR conductors per phase, rated at
approximately 2600 MVA (3,000A).
Tonbridge SS – Add two 500/230 kV transformers.
Tonbridge SS – Add two, 230 kV, 80 MVAR shunt reactors and three, 230 kV, 60
MVAR, capacitor banks for voltage control/support.
The Colstrip generation was reduced 950 MW to accommodate the addition of
950 MW of Wind Turbine Generation (WTG).
Corporate Base
Page 43
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
8.
9.
The Wind Turbines for the Hay Lake and the Renewable Collector System
(RCS) were assumed to be Acciona 1530 units with a reactive capacity of +/0.59 MVAR.
Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(units 1 and 2 are off-line to accommodate the addition of 950 MW of WTG).
Plan 7 Impact on Area Voltages
The power system voltage analysis results for voltages greater than 1.10 per unit (PU), in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, and with 950 MW of WTG on line indicated there would not
be any significant impacts (changes of greater than 0.02 PU) on voltages above 1.10 PU.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, and with 950 MW of WTG on line, indicated there would
not be any significant impacts (changes of greater than 0.02 PU) on voltages less than 0.95
per unit (PU), and below.
The power system contingency analysis results for voltages less than 0.95 per unit (PU),
and below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case
with the proposed Green Line in-service, with 950 MW of WTG, and with an outage of the
Garrison-Taft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated there would
not be any significant impacts (changes of greater than 0.02 PU) on voltages less than 0.95
per unit (PU), and below.
The power system contingency analysis results for voltages less than 0.95 per unit (PU),
and below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case
with the proposed Green Line in-service, with 950 MW of WTG, and an outage of the
Townsend-Garrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated, there
would not be any significant impacts (changes of greater than 0.02 PU) on voltages less
than 0.95 per unit (PU), and below.
Plan 7 Impact on Area Transmission Services
The power system analysis results for transmission line loadings, 100 per cent or higher, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, and with 950 MW of WTG on line, indicated there would not
be any no new overloaded transmission facilities, or, significant changes in existing
overloaded facilities.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 44
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
The power system contingency analysis results for transmission line loadings, 100 per cent
or higher, in the Montana and Northwestern areas, for the 2014 Light Autumn base case
with the proposed Green Line in-service, and 950 MW of WTG on-line, and with an outage
of the Garrison-Taft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated the Hot
Springs 500/230 kV transformer would overload approximately 119 per cent. Also, with the
300 MW at Hay Lake tripped off, the Hot Springs 500/230 kV transformer would still overload
approximately 105 per cent. To prevent overloading of the Hot Springs 500/230 kV
transformer, tripping the RCS 650 MW of WTG will be required. Also, the John Day
generation facility 100/13.8 kV step-up transformers, and the 500/100 kV transformers TX3
and TX4, also overloaded approximately 4 percent. There were no other new overloaded
transmission facilities, or, significant changes in existing overloaded facilities.
The power system contingency analysis results for transmission line loadings, 100 per cent
or higher, in the Montana and Northwestern areas, for the 2014 Light Autumn base case
with the proposed Green Line in-service, with 950 MW of WTG on-line, and with an outage
of the Townsend-Garrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated
there would not be any new overloaded transmission facilities, or, significant changes in
existing overloaded facilities. However, Northwestern’s John Day generation facility’s
100/13.8 kV step-up transformers, and, the 500/100 kV transformers TX3 and TX4, were
overloaded approximately 4 percent, with the Green Line in-service, and the TownsendGarrison 1 & 2, 500 kV lines out, for all levels of WTG. There were no other new
overloaded transmission facilities, or, significant changes in existing overloaded facilities.
Plan 7 Transient Analysis
The initial transient analysis indicated for an outage of the Garrison-Taft, 1 & 2, 500 kV
transmission lines, at a minimum, the RCS 650 MW of WTG will need to be tripped concurrently with the Colstrip units. The existing Western Montana Remedial Action Scheme
(RAS) will need to be revised to include tripping the 650 MW of WTG at the RCS.
The Initial transient analysis indicated that outages of the Broadview-Townsend, 1 & 2, 500
kV transmission lines, or the Townsend-Garrison, 1 & 2, 500 kV transmission lines may not
require the reduction of the 950 MW of WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 45
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Plan 7 Transmission Line Losses
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Hay Lake-Tonbridge)*
299
286
13
4.3 %
Green Line
500 kV)
927
915
12
1.3 %
Transmission Line
(Tonbridge-Garrison
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 7 Costs
Plan 7 costs are listed in Appendix 1.
Plan 7 Conclusions
Plan 7 with the proposed new Tonbridge 230 kV Switching Station (SS) and the Tonbridge
SS-Garrison 500 kV transmission line will provide a connection hub for WTG in northern
Montana. However, the study results indicated an outage of Garrison-Taft, 1 & 2, 500 kV
transmission lines, will require the RCS, 650 MW of WTG to be tripped to prevent
overloading the Hot Springs 500/230 kV transformer, and to maintain system stability. The
existing Western Montana Remedial Action Scheme (RAS) will need to be revised to include
tripping the RCS WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 46
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 8 – DETAILED DESCRIPTION
Plan 8 Summary
Construct a 230 kV “Tonbridge” Switching Station (SS) approximately 10 miles north of the
Great Falls 230 kV substation. Loop the MATL line into the new Tonbridge SS and add a
PST in the Tonbridge SS to Great Falls 230 kV circuit to limit power flow into Great Falls.
Install two 500/230 kV transformers in the Tonbridge SS and construct a 115 mile, 500 kV,
transmission line (Green Line) from the Tonbridge SS to Townsend and connect to the
Townsend 500 kV bus.
Plan 8 Details
Plan 8 includes the construction of a new 230 kV Tonbridge Switching Station (SS)
approximately 10 miles north of the existing Great Falls 230 kV substation. The Montana
Alberta 230 kV transmission line (MATL) will be looped into the new 230 kV Tonbridge SS
and a phase shifting transformer (PST) will be installed in the Tonbridge SS to Great Falls
230 kV circuit to limit power flow into Great Falls. A new 115 mile, single-circuit, 500 kV
transmission line (the Green Line) will be constructed from the new 230 kV Tonbridge SS to
the Townsend area. At the Townsend site construct a new 500 kV, 8 PCB substation. At
the new Tonbridge SS install two 500/230 kV transformers to connect to the 500 kV Green
Line.
The Green Line facilities for Plan 8 in the 2014 Light Autumn Load power system study
included the following:
1.
2.
3.
4.
5.
6.
7.
Green Line Report
Rev B (9-June-11)
Construct a new Tonbridge 230 kV Switching Station (SS) approximately ten
miles north of Great Falls.
Loop the MATL 230 kV transmission line into the new Tonbridge SS.
Add a 230 kV Phase-Shifting transformer in the Tonbridge to Great Falls 230 kV
circuit.
The Tonbridge to Townsend 500 kV transmission line was assumed to be a
single-circuit, three 954,000 ACSR conductors per phase, rated at
approximately 2600 MVA (3,000A).
At the new Tonbridge SS – Add two, 500/230 kV transformers.
BPA will require the construction of new, Townsend, 8 PCB, 500 kV substation.
At Tonbridge SS - Install two, 230 kV, 80 MVAR shunt reactors and three, 230
kV, 60 MVAR, capacitor banks for voltage control/support.
Corporate Base
Page 47
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
8.
At Townsend 500 kV bus (62013) – Add two, 500 kV, 120 MVAR shunt reactors
for voltage control.
9. The Colstrip generation was reduced 950 MW to accommodate the addition of
950 MW of Wind Turbine Generation (WTG).
10. The Wind Turbines for the Hay Lake and the Renewable Collector System
(RCS) were assumed to be Acciona 1530 units with a reactive capacity of +/0.59 MVAR.
11. Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(units 1 and 2 are off-line to accommodate the addition of 950 MW of WTG).
Plan 8 Impact on Area Voltages
The power system voltage analysis results for voltages greater than 1.10 per unit (PU), in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, with 950 MW of WTG on line, indicated there would not be
any significant impacts (changes of greater than 0.02 PU) on voltages above 1.10 PU.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, and with 950 MW of WTG on line indicated there would
not be any significant impacts (changes of greater than 0.02 PU) on voltages less than 0.95
per unit (PU), and below.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, , with 950 MW of WTG, and with an outage of the
Garrison-Taft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated there would
not be any significant impacts (changes of greater than 0.02 PU) on voltages less than 0.95
per unit (PU), and below.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, with 950 MW of WTG, and with an outage of the
Townsend-Garrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated there
would be a large number of voltage violations (changes of greater than 0.02 PU). The
contingency case with the 300 MW of WTG at Hay Lake off also indicated there would be a
large number of voltage violations (changes of greater than 0.02 PU). The contingency base
cases with the RCS 650 MW of WTG off, or with all of the 950 MW of WTG off-line did not
have any significant voltage problems.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 48
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Plan 8 Impact on Area Transmission Services
The power system analysis impacts of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case with the proposed Green Line in-service, with 950 MW of WTG on line
indicated there would not be any new overloaded transmission facilities, or, significant
changes in existing overloaded facilities.
The power system analysis results for transmission line loadings, 100 per cent or higher, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, with 950 MW of WTG, and with an outage of the GarrisonTaft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated the Hot Springs
500/230 kV transformer would overload approximately 119 per cent. Also, with the 300 MW
at Hay Lake tripped off, the Hot Springs 500/230 kV transformer would overload
approximately 106 per cent. To prevent overloading of the Hot Springs 500/230 kV
transformer, tripping the 650 MW of WTG at the RCS will be required. Also, Northwestern’s
John Day generation facility 100/13.8 kV step-up transformers, and the 500/100 kV
transformers TX3 and TX4, also overloaded approximately 4 percent, with the Green Line
In-service, and the Garrison-Taft 1 & 2, 500 kV lines out, for all levels of WTG. There were
no other new overloaded transmission facilities, or, significant changes in existing
overloaded facilities.
The power system analysis results for transmission line loadings, 100 per cent or higher, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, with 950 MW of WTg, and with an outage of the TownsendGarrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated there would be
several overloaded transmission facilities in the Montana area. Tripping with the Hay Lake
300 MW of WTG would unload the transmission facilities. There were not any other
significant transmission loading problems in the Montana area with the exception of the John
Day generation plant’s 100/13.8 kV step-up transformers, and the 500/100 kV transformers
TX3 and TX4, that overloaded approximately 4 percent for all levels of WTG. There were no
other new overloaded transmission facilities, or, significant changes in existing overloaded
facilities.
Plan 8 Transient Analysis
The initial transient analysis indicated for an outage of the Garrison-Taft, 1 & 2, 500 kV
transmission lines, or, the Townsend-Garrison, 1 & 2, 500 kV transmission lines, at a
minimum; the RCS 650 MW of WTG will need to be tripped con-currently with the Colstrip
units. The existing Colstrip ATR may need to be expanded to include the RCS WTG – or a
separate remedial Action Scheme (RAS) will need to be developed.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 49
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
The Initial transient analysis indicated that outages of the Broadview-Townsend, 1 & 2, 500
kV transmission lines, may not require the reduction of the 950 MW of WTG.
Plan 8 Transmission Line Losses
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Hay Lake-Tonbridge)*
299
286
13
4.3 %
Green Line
500 kV)
927
917
10
1.1 %
Transmission Line
(Tonbridge-Townsend
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 8 Costs
Plan 8 costs are listed in Appendix 1.
Plan 8 Conclusions
Plan 8 with the proposed new Tonbridge Switching Station and the Tonbridge SS-Townsend
500 kV transmission line will provide a connection for WTG in northern Montana to the
Northwest power grid. However, for an outage of Garrison-Taft, 1 & 2, 500 kV transmission
lines, or, an outage of the Townsend-Garrison, 1 & 2, 500 kV transmission lines, the 650
MW of WTG at RCS will need to be tripped to prevent overloading the Hot Springs 500/230
kV transformer, and maintain system stability. For outage of the Broadview-Townsend 1 & 2
500 kV circuits, tripping the 650 MW of WTG at RCS may not be required. The existing
Western Montana Remedial Action Scheme (RAS) will need to be revised to include tripping
the RCS WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 50
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 9 – DETAILED DESCRIPTION
Plan 9 Summary
Construct a 230 kV “Tonbridge” Switching Station (SS) at the Marias site, approximately 85
miles north of the existing Great Falls 230 kV substation. The Marias site is located on the
Montana-Alberta 230 kV transmission line (MATL) right-of-way and is where Tonbridge
Power plans to install back-to-back series capacitors to aid power flow on the MATL 230 kV
interconnection. The new Tonbridge/Marias SS will include a Phase-Shifting Transformer
(PST) to control power flow on the MATL line section from the Tonbridge/Marias SS to the
Great Falls 230 kV substation. A new 230 kV single-circuit 230 kV transmission line (the
Green Line) will be constructed from Marias to the existing Garrison 500 kV substation. At
the Garrison 500 kV substation, Tonbridge will install a 500/230 kV transformer to connect
the Green Line to the 500 kV network.
Plan 9 Details
Plan 9 includes the construction of a new 230 kV Tonbridge Switching Station (SS) at
Marias, approximately 85 miles north of the existing Great Falls 230 kV substation. The
MATL will be looped into the new 230 kV Tonbridge/Marias SS and a phase shifting
transformer (PST) will be installed in the Tonbridge/Marias SS to Great Falls 230 kV circuit
to limit power flow into Great Falls. A new 220 mile, single-circuit, 230 kV transmission line
(the Green Line) will be constructed from Marias to the Garrison 500 kV substation. . At the
Garrison 500 kV substation, Tonbridge will install a 500/230 kV transformer to connect the
Green Line to the 500 kV network.
The Green Line facilities for Plan 9 as modelled in the 2014 Light Autumn Load power
system study included the following:
1.
2.
3.
4.
5.
Green Line Report
Rev B (9-June-11)
Construct a new Tonbridge 230 kV Switching Station (SS) at the Marias site,
approximately 85 miles north of the existing Great Falls 230 kV substation.
Connect the new Tonbridge/Marias SS to the Marias South 230 kV bus.
Add a 230 kV Phase-Shifting transformer in the MATL 230 kV transmission line
from the new Tonbridge/Marias SS to the existing Great Falls 230 kV substation.
Construct a Tonbridge/Marias SS to Garrison 230 kV transmission line (a singlecircuit, 1,590,000 ACSR conductor, transmission line, rated at approximately
600 MVA).
At the existing Garrison 500 kV substation – Add one, 500/230 kV transformer.
Corporate Base
Page 51
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
6.
At the new Tonbridge/Marias SS - Install two, 230 kV, 80 MAVR shunt reactors
and three, 230 kV, 60 MVAR, capacitor banks for voltage control/support.
7. At the new 230 kV bus at the Garrison 500 kV substation – Install two, 230 kV,
80 MAVR shunt reactors and three, 230 kV, 60 MVAR, capacitor banks for
voltage control/support.
8. The Colstrip generation was reduced 330 MW (Colstrip Unit 2) to accommodate
the addition of 300 MW of Wind Turbine Generation (WTG) at Hay Lake.
9. The Wind Turbines for the Hay Lake were assumed to be Acciona 1530 units
with a reactive capacity of +/- 0.59 MVAR.
10. Contingency studies assumed the Colstrip ATR would trip Colstrip units 1, 3, and
4 (unit 2 is already off-line to accommodate the addition of 300 MW of WTG at
Hay Lake).
Plan 9 Impact on Area Voltages
The power system voltage analysis results for voltages greater than 1.10 per unit (PU), in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, with 0 MW of WTG on line, indicated the voltage at the
Marias South and the PST 230 kV buses would increase to approximately 1.32 and 1.26 per
unit, respectively, which will exceed the WECC upper voltage limit of 1.05 per unit for noncontingency system conditions. The high voltages are a result of interaction between the
series, and shunt, capacitors at Marias and the line shunt reactors associated with the
Green Line.
Switching the 4, 160 MVAR shunt capacitor banks off at Maries resulted in reducing the
voltages at the Marias S and PST 230 kV buses to approximately 1.05 per unit each;
however, the voltages at the Marias N and Hay Lake 230 kV buses decreased to 0.79 and
0.87 per unit, respectively. The voltages at Marias N and Hay Lake are well below the
WECC minimum voltage level of 0.95 per unit.
Adding 300 MW of WTG at Hay Lake, with the Marias 4, 160 MVAR shunt capacitors off,
resulted in voltages at Marias S, Marias N, Hay Lake, and the PST buses of 1.28, 0.67, 0.84,
and 1.23 per unit, respectively, all of which are outside the WECC voltage limits 1.05 per unit
maximum and 0.95 per unit minimum.
Adding 300 MW of WTG at Hay Lake, with the Marias shunt capacitors off, - and looping the
Bole-Conrad 230 kV transmission line into Marias S, resulted in voltages at Marias S, Marias
N, Hay Lake, and the PST buses of 106, 107, 105, and 106 per cent, respectively, all of
which are slightly above the WECC maximum voltage limit of 105 per cent.
Adding a transfer of 200 MW from Alberta to PGE through the MATL 120 PST’s to the 300
MW of WTG at Hay Lake, with the Marias shunt capacitors off, and with the Bole-Conrad
Green Line Report
Rev B (9-June-11)
Corporate Base
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
line looped into Marias S, resulted in the voltages at Marias S, Marias N, Hay Lake, and the
PST buses to 1.07, 1.12, 1.05, and 1.06 per unit, respectively, which also exceeded to the
WECC upper limit of 1.05 per unit and would not be acceptable.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), in the
Montana and Northwestern areas, for the 2014 Light Autumn base case with the proposed
Green Line in-service, with 0 MW of WTG on line, indicated the voltage at the Marias N and
Hay Lake 230 kV buses would decrease to approximately 0.99 and 1.00 per unit,
respectively, which are within the WECC voltage limits of 1.05 and 0.95 per unit for noncontingency system conditions.
Switching the 4, 160 MVAR shunt capacitor banks off at Maries resulted in reducing the
voltages at the Marias N and Hay Lake 230 kV buses to approximately 0.79 and 0.87 PU,
respectively. Both voltages were well below the WECC minimum voltage level of 95 PU.
The low voltages are a result of interaction between the series capacitors at Marias and the
line shunt reactors associated with the Green Line.
Adding 300 MW of WTG at Hay Lake, with the Marias shunt capacitors off, resulted in
voltages at Marias N and Hay Lake 230 kV buses of 0.67 and 0.84 PU, respectively, all of
which are below the WECC voltage minimum limit of 0.95 per unit.
Adding 300 MW of WTG at Hay Lake, with the Marias shunt capacitors off, - and looping the
Bole-Conrad 230 kV transmission line into Marias S - resulted in voltages at Marias S,
Marias N and Hay Lake 230 kV buses of 1.07 and 1.05 PU, respectively, all of which are
only slightly above the WECC maximum voltage limit of 1.05 per unit.
Adding a transfer of 200 MW from Alberta to PGE through the MATL 120 PST’s to the 300
MW of WTG at Hay Lake, with the Marias shunt capacitors off, and, with the Bole-Conrad
230 kV line looped into Marias S, resulted in the voltages at Marias N and Hay Lake of 1.12
and 1.05 PU, respectively, which also exceeded to the WECC upper limit of 1.05 PU and
would not be acceptable.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, with 300 MW of WTG at Hay Lake and 200 MW transfer
Alberta to PGE, and, with the Bole-Conrad 230 kV line looped into Marias S, with an outage
of the Garrison-Taft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated the
Marias, Marias N, and Hay Lake voltages would be 1.00, 1.11, and 1.04 PU, respectively.
The 1.11 PU voltage at Marias N slightly higher than the WECC limits of 1.10 PU maximum
and 0.90 PU minimum for contingency conditions; which may be acceptable.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 53
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
the proposed Green Line in-service, with 300 MW of WTG at Hay Lake and 200 MW transfer
Alberta to PGE, and with an outage of the Townsend-Garrison, 1 & 2, 500 kV transmission
lines, (with Colstrip ATR), indicated the Marias, Marias N, and Hay Lake voltages would be
0.99, 1.09, and 1.025 PU, respectively, which are all within the WECC voltage limits of 1.10
PU maximum and 0.90 PU minimum for contingency conditions.
Plan 9 Impact on Area Transmission Services
The power system analysis impacts of the proposed Green Line on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case with the proposed Green Line in-service, with 300 MW of WTG on line at
Hay Lake, and, with a 200 MW transfer from Alberta to PGE, indicated the Tonbridge/Marias
SS-Bole 230 kV circuit would overload approximately 142 per cent.
The power system analysis results for transmission line loadings, 100 per cent or higher, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, with 300 MW of WTG at Hay Lake, and, with 200 MW
transfer from Alberta to PGE, and with an outage of the Garrison-Taft, 1 & 2, 500 kV
transmission lines, (with Colstrip ATR), indicated the Tonbridge/Marias SS-Bole 230 kV
circuit would overload approximately 154 per cent. Also, with the 200 MW transfer from
Alberta to PGE reduced to zero, Tonbridge/Marias SS-Bole 230 kV circuit would overload
approximately 102 per cent. To prevent overloading of the Tonbridge/Marias SS-Bole 230
kV circuit would require tripping the 300 MW of WTG at Hay Lake and all power transfers
from Alberta.
The power system analysis results for transmission line loadings, 100 per cent or higher, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, with 300 MW of WTG at Hay Lake, and, with 200 MW
transfer from Alberta to PGE, and with an outage of the Townsend-Garrison, 1 & 2, 500 kV
transmission lines, (with Colstrip ATR), indicated the Tonbridge/Marias SS-Bole 230 kV
circuit would overload approximately 131 per cent. To prevent overloading of the
Tonbridge/Marias SS-Bole 230 kV circuit would require tripping of all power transfers from
Alberta.
Plan 9 Transient Analysis
The initial transient analysis was not performed because the power system analysis
indicated Plan 9 – the Green Line connection from Marias to Garrison would not be feasible.
Plan 9 Transmission Line Losses
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 54
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Substation 120S-Hay LakeTonbridge)*
189.3
185.1
4.2
2.2%
MATL (Hay Lake-Tonbridge)*
485.1
472.5
12.6
2.6 %
Green Line (Tonbridge/Marias SSGarrison 230 kV)
265.6
249.6
16.0
6.0 %
Transmission Line
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 9 Costs
Plan 9 costs are listed in Appendix 1
Plan 9 Conclusions
Plan 9 with the proposed new Tonbridge/Marias Switching Station and the Tonbridge SSGarrison 230 kV transmission line (Green Line) would not be feasible because of the
interaction between the series and shunt capacitors at Marias and the Green Line shunt
reactors. Switching off the four 160 MVAR capacitor banks at Marias, and looping the BoleConrad 230 kV transmission line into the Maris S bus would help with the voltage issues;
however, the loop establishes a 230 kV direct tie to Great Falls which would severely
overload (142 per cent) with 300 MW of WTG at Hay Lake and a 200 MW transfer from
Alberta to PGE.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 55
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Appendix 5 - Alternate Plans For Connecting Tonbridge
SS to Great Falls using a Power Circuit Breaker
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 56
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 5 – DETAILED DESCRIPTION
Plan 5 Summary
Same as Plan 3 except replace the PST in the Tonbridge to Great Falls 230 kV circuit with a
230 kV circuit breaker and operate “Normally Open”.
Plan 5 Details
Plan 5 includes the construction of a new 230 kV Tonbridge Switching Station (SS)
approximately 10 miles north of the existing Great Falls 230 kV substation. The Montana
Alberta 230 kV transmission line (MATL) will be looped into the new 230 kV Tonbridge SS.
A 230 kV PCB will be installed in the Tonbridge SS to Great Falls line section and will be
operated normally open. A new 145 mile, double-circuit, 230 kV transmission line (the
Green Line) will be constructed from the new 230 kV Tonbridge SS to the Garrison 500/230
kV substation. At Garrison two 500/230 kV transformers will be added to connect the Green
Line to the 500 kV network (see Figure 5).
The Green Line facilities for Plan 5, included in the 2014 Light Autumn Load power system
study are as follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Green Line Report
Rev B (9-June-11)
Construct a new Tonbridge 230 kV Switching Station (SS) approximately ten
miles north of Great Falls.
Loop the MATL 230 kV transmission line into the new Tonbridge SS.
Add a 230 kV PCB (Operate Normally Open) in the Tonbridge SS to Great falls
circuit.
Construct a new 145 mile, Tonbridge SS to Garrison, 230 kV transmission line
(double-circuit, two 954,000 ACSR conductors per phase, rated at
approximately 1600 MVA).
Install two 500/230 kV transformer at Garrison.
Tonbridge SS – Add two, 230 kV, 80 MVAR shunt reactors and three, 230 kV, 60
MVAR, capacitor banks for voltage control/support.
Garrison 230 kV bus - Add two, 230 kV, 80 MVAR shunt reactors and three, 230
kV, 60 MVAR, capacitor banks for voltage control/support.
The Colstrip generation was reduced 950 MW to accommodate the addition of
950 MW of Wind Turbine Generation (WTG).
The Wind Turbines for the Hay Lake and the Renewable Collector System
(RCS) were assumed to be Acciona 1530 units with a reactive capacity of +/0.59 MVAR.
Corporate Base
Page 57
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
10. Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(units 1 and 2 are off-line to accommodate the addition of 950 MW of WTG).
Plan 5 Impact on Area Voltages
The power system analysis results for impacts of the Green Line on voltages greater than
1.10 per unit (PU), in the Montana and Northwestern areas, for the 2014 Light Autumn base
case, with the proposed Green Line, and with 950 MW of WTG on line indicated there would
be no voltage violations (changes of greater than 0.02 PU) on voltages above 1.10 PU.
The power system analysis results for impacts of the Green Line on voltages less than 0.95
per unit (PU), and below, in the Montana and Northwestern areas, for the 2014 Light Autumn
base case with the proposed Green Line in-service, with 950 MW of WTG on line, indicated
there would be no significant impacts (changes of greater than 0.02 PU) on voltages less
than 0.95 per unit (PU), and below.
The power system contingency analysis results for the Green Line on voltages less than
0.95 per unit (PU), and below, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case with the proposed Green Line, with 950 MW of Generation (WTG), and
an outage of the Garrison-Taft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR),
indicated there would be no significant violations. The study also considered the impact of
the Green Line, with the Garrison-Taft 1 & 2, 500 kV lines out, on four base cases with the
Green Line in-service, and with different levels of WTG in-service: 950 MW, 650 MW (300
MW off at Hay Lake), 300 MW (650 MW off at RCS), and with all 950 MW of WTG off. The
study results indicated there would be no significant impacts (changes of greater than 0.02
PU) on voltages less than 0.95 per unit (PU), and below.
The power system contingency analysis results for voltages less than 0.95 per unit (PU),
and below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case
with the Green Line in-service, with 950 MW of WTG on-line, indicated there would be no
significant voltage problems. The study also examined the impacts of the Green Line on
base cases with an outage of the Townsend-Garrison, 1 & 2, 500 kV transmission lines,
(with Colstrip ATR). The base cases included four base cases with the Green Line inservice, and with different levels of WTG in-service: 950 MW, 650 MW (300 MW at Hay
Lake off), 300 MW (650 MW at RCS off), and with all 950 MW WTG off. The study results
indicated there would be no significant impacts (changes of greater than 0.02 PU) on
voltages less than 0.95 per unit (PU), and below.
Plan 5 Impact on Area Transmission Services
The power system analysis results for transmission line loadings, 100 per cent or higher, in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 58
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
proposed Green Line in-service, and with 950 MW of WTG on line, indicated there would be
no new overloaded transmission facilities, or, significant changes in existing overloaded
facilities.
The power system contingency analysis of the impacts of the proposed Green Line on
transmission line loadings, 100 per cent or higher, in the Montana and Northwestern areas,
for the 2014 Light Autumn base case, with the Green Line in-service, and 950 MW of WTG
on-line, and, with the Garrison-Taft, 1 & 2, 500 kV transmission lines outaged, (with Colstrip
ATR), indicated the Hot Springs 500/230 kV transformer would overload 117 per cent. Also,
tripping off the 300 MW of WTG at Hay Lake resulted in the Hot Springs 500/230 kV
transformer overloaded approximately 106 per cent. To prevent overloading of the Hot
Springs 500/230 kV transformer, tripping of the RCS 650 MW of WTG will be required. Also,
the study indicated the John Day generation facility 100/13.8 kV step-up transformers, and
the 500/100 kV transformers TX3 and TX4, would overloaded approximately 4 percent, with
the Green Line in-service, and the Garrison-Taft 1 & 2 out, for all levels of WTG. There were
no other new overloaded transmission facilities, or, significant changes in existing
overloaded facilities.
The power system contingency analysis of the Green Line impacts on transmission line
loadings, 100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light
Autumn base case with the Green Line in-service, with 950 MW of WTG on-line, and with an
outage of the Townsend-Garrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR),
indicated there would not be any new overloaded transmission facilities, or, significant
changes in existing overloaded facilities.
Plan 5 Transient Analysis
The initial transient analysis indicated for an outage of the Garrison-Taft, 1 & 2, 500 kV
transmission lines, at a minimum, the RCS 650 MW of WTG will need to be tripped concurrently with the Colstrip units. The existing Colstrip ATR may need to be expanded to
include tripping the RCS WTG – or a separate remedial Action Scheme (RAS) will need to
be developed.
The Initial transient analysis indicated that outages of the Broadview-Townsend, 1 & 2, 500
kV transmission lines, or the Townsend-Garrison, 1 & 2, 500 kV transmission lines may not
require any reduction of the 950 MW of WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 59
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Plan 5 Transmission Line Losses
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Hay Lake-Tonbridge)*
299
285
14
4.7 %
Green Line #1 (Tonbridge-Garrison)
463
439
24
5.2 %
Green Line #2 (Tonbridge-Garrison)
463
439
24
5.2 %
Transmission Line
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 5 Costs
Plan 5 costs are listed in Appendix 1.
Plan 5 Conclusions
Plan 5 with the proposed new Tonbridge 230 kV Switching Station (SS) and the Tonbridge
SS-Garrison, double-circuit, 230 kV transmission line will provide a connection hub for WTG
in northern Montana. However, the study results indicated an outage of Garrison-Taft, 1 &
2, 500 kV transmission lines, will require the RCS, 650 MW of WTG to be tripped to prevent
overloading the Hot Springs 500/230 kV transformer, and to maintain system stability. The
existing Western Montana Remedial Action Scheme (RAS) will need to be revised to include
tripping the RCS 650 MW of WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 60
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
PLAN 6 – DETAILED DESCRIPTION
Plan 6 Summary
Same as Plan 4 except replace the PST in the Tonbridge to Great Falls 230 kV circuit with a
230 kV circuit breaker and operate “Normally Open”.
Plan 6 Details
Plan 6 includes the construction of a new 230 kV Tonbridge Switching Station (SS)
approximately 10 miles north of the existing Great Falls 230 kV substation. The Montana
Alberta 230 kV transmission line (MATL) will be looped into the new 230 kV Tonbridge SS.
A 230 kV PCB will be installed in the Tonbridge SS to Great Falls 230 kV circuit and will be
operated normally open. A new 115 mile, double-circuit, 230 kV transmission line (the
Green Line) will be constructed from the new 230 kV Tonbridge SS to the Townsend area.
At the Townsend site a new 500 kV, 8 PCB substation will be constructed. At the new
Townsend 500 kV substation two 500/230 kV transformers will be installed to connect the
Green Line to the 500 kV network.
The Green Line facilities for Plan 6 included in the 2014 Light Autumn Load power system
are as follows:
1.
2.
3.
4.
5.
6.
7.
8.
Green Line Report
Rev B (9-June-11)
Construct a new Tonbridge 230 kV Switching Station (SS) approximately ten
miles north of Great Falls.
Loop the MATL 230 kV transmission line into the new Tonbridge SS.
Add a 230 kV PCB (Operate Normally Open) in the Tonbridge SS to Great falls
circuit.
Construct a new Tonbridge to Townsend 230 kV transmission line (assumed to
be double-circuit, two 954,000 ACSR conductors per phase, rated at
approximately 1600 MVA).
BPA will require the construction of new, Townsend, 8 PCB, 500 kV substation.
Tonbridge will install two 500/230 kV transformers at new Townsend 500 kV
substation.
At Tonbridge SS - Add two, 230 kV, 80 MVAR shunt reactors and three, 230 kV,
60 MVAR, capacitor banks for voltage control/support.
At new Townsend 500 kV substation 230 kV bus – Add two, 230 kV, 80 MVAR
shunt reactors and three, 230 kV, 60 MVAR, capacitor banks for voltage
control/support.
Corporate Base
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TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
9.
The Colstrip generation was reduced 950 MW to accommodate the addition of
950 MW of Wind Turbine Generation (WTG).
10. The Wind Turbines for the Hay Lake and the Renewable Collector System
(RCS) will be Acciona 1530 units with a reactive capacity of +/- 0.59 MVAR.
11. Contingency studies assumed the Colstrip ATR would trip Colstrip units 3 and 4
(units 1 and 2 are off-line to accommodate the addition of 950 MW of WTG).
Plan 6 Impact on Area Voltages
The power system voltage analysis results for voltages greater than 1.10 per unit (PU), in
the Montana and Northwestern areas, for the 2014 Light Autumn base case with the
proposed Green Line in-service, and with 950 MW of WTG on line indicated there would not
be any significant impacts (changes of greater than 0.02 PU) on voltages above 1.10 PU.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, and with 950 MW of WTG on line, indicated there would
not be any significant impacts (changes of greater than 0.02 PU) on voltages less than 0.95
per unit (PU), and below.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, with 950 MW of WTG on-line, and, an outage of the
Garrison-Taft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated there would
not be any significant impacts (changes of greater than 0.02 PU) on voltages less than 0.95
per unit (PU), and below.
The power system voltage analysis results for voltages less than 0.95 per unit (PU), and
below, in the Montana and Northwestern areas, for the 2014 Light Autumn base case with
the proposed Green Line in-service, with 950 MW of WTG on-line, and with an outage of the
Townsend-Garrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated there
would be a large number of voltage violations (changes of greater than 0.02 PU). The case
with the 300 MW of WTG at Hay Lake off, with the Green Line in-service, and the
Townsend-Garrison 1 & 2, 500 kV lines out, also had a large number of voltage violations
(changes of greater than 0.02 PU). The contingency base case with the RCS 650 MW of
WTG off, or with all of the 950 MW of WTG off with the Green Line in-service, and the
Townsend-Garrison 1 & 2, 500 kV lines, out did not have any significant voltage violations.
Plan 6 Impact on Area Transmission Services
The power system analysis results for the green Line impacts on transmission line loadings,
100 per cent or higher, in the Montana and Northwestern areas, for the 2014 Light Autumn
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 62
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
base case with the proposed Green Line in-service, with 950 MW of WTG on line did not
have any no new overloaded transmission facilities, nor, were there any significant changes
in existing overloaded transmission facilities.
The power system contingency analysis of the loading impacts of the proposed Green Line
for transmission line loadings, 100 per cent or higher, in the Montana and Northwestern
areas, for the 2014 Light Autumn base case with the proposed Green Line in-service, and
with an outage of the Garrison-Taft, 1 & 2, 500 kV transmission lines, (with Colstrip ATR),
indicated the Hot Springs 500/230 kV transformer would overload approximately 118 per
cent. Also, the study indicated the case with the 300 MW at Hay Lake tripped off, theGreen
Line in-service, and with the Garrison-Taft 1 & 2, 500 kV lines out, the Hot Springs 500/230
kV transformer would still overload approximately 105 per cent. To prevent overloading of
the Hot Springs 500/230 kV transformer, tripping the 650 MW of WTG at the RCS will be
required. The study results also indicated the John Day generation facility 100/13.8 kV stepup transformers, and the 500/100 kV transformers TX3 and TX4, would overload
approximately 4 percent, with the Green Line in-service, and with the Garrison-Taft 1 &2,
500 kV lines out. There would not be any other new overloaded transmission facilities, or,
significant changes in existing overloaded facilities.
The power system contingency analysis results for transmission line loadings, 100 per cent
or higher, in the Montana and Northwestern areas, for the 2014 Light Autumn base case
with the proposed Green Line in-service, with 950 MW of WTG, and with an outage of the
Townsend- Garrison, 1 & 2, 500 kV transmission lines, (with Colstrip ATR), indicated there
would be a number of overload transmission facilities in the Montana area. Tripping of the
Hay Lake 300 MW of WTG, with the Green Line in-service, and the Townsend-Garrison 1 &
2, 500 kV lines out, eliminated the transmission overloads. There were not any other
significant transmission loading problems in the Montana area with the exception of the
Northwestern John Day generation plant’s 100/13.8 kV step-up transformers, and the
500/100 kV transformers TX3 and TX4, that overloaded approximately 4 percent with the
Green Line in-service, and the Townsend-Garrison 1 & 2, 500 kV lines out, for all levels of
WTG. There were no other new overloaded transmission facilities, or, significant changes in
existing overloaded facilities.
Plan 6 Transient Analysis
The initial transient analysis indicated for an outage of the Garrison-Taft 1 & 2, 500 kV
transmission lines, or the Townsend-Garrison 1 & 2, 500kV transmission lines, at a
minimum, the RCS 650 MW of WTG will need to be tripped con-currently with the Colstrip
units. The existing Western Montana Remedial Action Scheme (RAS) will need to be
revised to include the 650 MW of WTG at the RCS.
The Initial transient analysis indicated that outage of the Broadview-Townsend 1 & 2, 500 kV
transmission line may not require the reduction of the 950 MW of WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 63
TONBRIDGE POWER
GREEN LINE PROJECT
PLAN OF SERVICE
Plan 6 Transmission Line Losses
Sending
End
Receiving
End
Line
Losses
Line
Losses
MW
MW
MW
Per Cent
MATL (Hay Lake-Tonbridge)*
299
285
14
4.7 %
Green Line #1 (Tonbridge-Garrison)
463
446
17
3.7 %
Green Line #2 (Tonbridge-Garrison)
463
446
17
3.7 %
Transmission Line
* Power flow on the Montana-Alberta Transmissio n Line (MATL)
controlled by the phase-shifting transformer (PST) at Substation
120S.
Plan 6 Costs
Plan 6 costs are listed in Appendix 1.
Plan 6 Conclusions
Plan 6 with the proposed new Tonbridge Switching Station and the Tonbridge SSTownsend, double-circuit, 230 kV transmission line (Green Line) will provide a connection
for WTG in northern Montana. However, for an outage of Garrison-Taft, 1 & 2, 500 kV
transmission lines, or, an outage of the Townsend-Garrison, 1 & 2, 500 transmission lines,
the 650 MW of WTG at RCS will need to be tripped to prevent overloading the Hot Springs
500/230 kV transformer, and to maintain system stability. For outage of the BroadviewTownsend, 1 & 2, 500 kV transmission lines, tripping the 650 MW of WTG at RCS may not
be required. The existing Western Montana Remedial Action Scheme (RAS) will need to be
revised to include tripping the RCS WTG.
Green Line Report
Rev B (9-June-11)
Corporate Base
Page 64