STUDY PLAN
GRID INTEGRATION ASSESSMENT NORTHWEST TRANSMISSION PROJECTS
???? Study Sponsors ????
December 2007
Draft 12-7-07
GRID INTEGRATION ASSESSMENT NORTHWEST TRANSMISSION PROJECTS
1. INTRODUCTION AND PURPOSE
A variety of major transmission projects have been proposed that will have a significant
impact on the northwest transmission grid. To date, little analysis has been completed to
assess how these projects will interact with each other. In addition, for some of the projects,
the preliminary plan of service and preferred project terminations have not been determined.
The Grid Integration Assessment – Northwest Transmission Projects (GIANT Projects
Study) is intended to fill this gap by investigating the interactions between these projects and
then developing a preferred approach to integrating them into the existing northwest
transmission grid. In determining the preferred approach to integrating these projects, the
study will focus on minimizing costs and maximizing technical functionality. This information
will be used as a basis for more detailed project development studies as well as to influence
the development of projects that are being pursued by various entities. The approach to be
used in GIANT Projects Study will be to first model all of the major projects together using
power flow analysis. The overall combination of projects will be refined so that they can all
function satisfactorily together (but perhaps not at their simultaneous maximum capabilities).
After an optimal overall plan is developed, then the phasing of the projects will be
considered.
The major projects (500 kV AC or DC) to be modeled in the studies include:
1) Paul-Troutdale 500 kV line (i.e., the I-5 Corridor project) – Proposed by BPA to
increase transfer capability between Seattle and Portland. This capability is most
needed during the summer when large amounts of power are being exported from
Canada and the northwest to California (see Attachment 1).
2) McNary-John Day and Big Eddy-Station Z 500 kV lines (i.e., the West of McNary
Project) – Proposed by BPA to allow the development of renewable resources along
the Columbia River Gorge in Oregon and Washington (see Attachment 2).
3) Northern Lights Project – A DC line from Canada to either Celilo or the new
McNary/Boardman Substation (see Attachment 3). For Study Purposes, this will be
modeled as fixed power injection ranging from 0 to 3000 MW at McNary/Boardman.
4) Southern Crossing Project – A 500 kV line from the Boardman area to Bethel
Substation near Salem Oregon. This project has been proposed by PG&E to allow
the development of renewable resources along the Columbia River Gorge in Oregon
and Washington. This line will be modeled as proposed by PGE with a 500 kV
connection to the PG&E Project and the AC Intertie at Grizzly Substation (see
Attachment 4).
5) Canada to Northern California Project – Proposed by PG&E to import renewable
resources from Canada and the northwest into California (see Attachment 5). For
this study, the project will be assumed to connect to two points in the Northwest: a
New Avista Substation and Grizzly Substation. At Grizzly Substation, the project will
change from AC to DC as it continues on to California. The project will be fed by
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3000 MW of new generation in Canada. The Sea breeze NW to California Undersea
cable Project will be considered as one alternative to this project.
6) Hemmingway to McNary 500 kV Project – Proposed by Idaho Power to Import Power
from the Mid-C area to Idaho (see Attachment 6). This line will be loaded with new
resources from Wyoming for the east to west transfer conditions.
7) Hemmingway to Captain Jack 500 kV Project – Proposed by PacifiCorp to import
power from the east into southern Oregon (see Attachment 7). The Hemmingway to
Captain Jack 500 kV line will be compensated so that it is carrying comparable
power as the Midpoint-Summer Lake 500 kV line. This line will be loaded with new
resources from Wyoming through new transmission projects proposed by Idaho
Power and PacifiCorp as described in Attachment 7.
2. STUDY METHODOLOGY
a. Miscellaneous Assumptions
I. The study group will review available power flow cases and select the
appropriate cases for the study. A few options include the power flow cases
being developed by ColumbiaGrid for the Biennial Plan, the NTTG cases and
the cases being developed by PG&E for their projects.
II. All system elements will be in service for the assumed initial conditions.
III. System transfer levels for major WECC paths will be agreed upon and listed.
IV. Voltage criteria will be applied in accordance with the existing policies of the
respective utilities or operating agents.
V. A list of the series compensation assumptions for the major EHV lines will be
provided.
VI. Series compensation for new lines will be limited to 70%.
VII. New 500 kV AC lines will have an assumed 1500 ampere normal rating and
2000 ampere emergency rating unless better information is available.
b. Performance Criteria
Power flow analysis will be performed in accordance with the NERC/WECC Planning
Standards and current WECC practices. For this study, stability studies will not be
completed. Stability analysis will be completed in the next phase of project
development or by the individual projects as they evolve.
c. Development of Base Cases
Due to the diverse nature of the various projects being proposed, multiple base
cases will be used. Conditions to be studied will include maximum transfers east to
west as well as west to east, with and without high levels of north to south transfers
to California. At a minimum, the following stressed system conditions will be modeled
in the base cases.
i.
ii.
High transfers from Wyoming to Washington and Oregon.
- High Canada to California transfers
- Low Canada to California transfers
Moderate transfers from the northwest to Idaho and Utah.
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- High Canada to California transfers
- Low Canada to California transfers
d. Outage Performance
After appropriately stressing the case, outages will be simulated and any violations
and potential solutions will be noted. Pre and post contingency flows on major lines
will be tabulated and presented in the report.
e. Project Optimization
Using these results, the performance of the projects will be optimized by adjusting
series compensation (up to 70%), changing project terminations, changing project
loading levels, or making other changes as appropriate.
f.
Develop recommended changes to the various projects:
I.
II.
III.
IV.
V.
VI.
Alternate terminations
Series compensation levels
Phase Shifters
SVCs (with approximate ratings)
Remedial Action Schemes
Other, if any
g. Conduct sensitivity studies.
Sensitivity studies will be conducted as determined necessary by the engineers
completing the studies to fully explore the project alternatives.
3. DOCUMENTATION OF STUDY RESULTS
The results of these technical studies will be documented in a report.
4. Schedule
a. Finalization of Study Plan – February 1, 2008
b. Completion of Base Cases – March 15, 2008
c. Refinement of combination of projects cases – June 1, 2008
d. Initial Report – Combination of Projects Study Portion – July 1, 2008
e. Studies examining Project Phasing – October 1, 2008
f.
Final Report – December 1, 2008
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Attachment 1
Paul-Troutdale 500 kV line
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Attachment 2
McNary-John Day and Big Eddy-Station Z 500 kV
lines
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Attachment 3
Northern Lights Project
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Attachment 4
Southern Crossing Project
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Attachment 5
Canada to California Project
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Attachment 6
Hemmingway to McNary 500 kV Project
Figure to be added
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Attachment 7
Idaho Power and PacifiCorp Major Projects
PacifiCorp publicly announced on May 30, 2007, its transmission expansion plan to build
more than 1,200 miles of new 500 kV transmission lines originating in Wyoming and
connecting into Utah, Idaho, Oregon and the desert southwest, with completion targeted in
2014. The plan includes projects already in the company’s 10-year business plan and
additional investments that will address customers’ increasing electricity use. In addition to
improving system reliability, these projects are aimed at delivering wind and other renewable
generation resources to more customers throughout PacifiCorp’s six-state service area and
the Western Interconnection. (A fact sheet that was provided with this initial announcement
is included in Attachment A.)
Since the initial project announcement, the proposed transmission facilities to support the
two major transmission routes (Northern and Southern) have evolved to better meet
PacifiCorp’s needs and the anticipated needs of other stakeholders. This modified system
is illustrated on Figure 1 and is summarized below:
Figure 1: Wyoming – Utah/Idaho 500 kV Transmission Project
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
The Two Projects
The electric transmission projects will consist of two transmission line routes, a
northern route and a southern route. In the previous plan, Bridger was intended to
be the hub for both projects; however, a modified configuration has been defined
which includes a second transmission hub east of Bridger, located northeast of
Miners substation (designated Aeolus). This second hub will improve overall system
reliability and provide better support for anticipated Wyoming load service and
generation (TSR/LGI) requests.
Northern Route
o Double-circuit 500 kV transmission line; PacifiCorp and Idaho Power
Company are pursuing joint ownership of this line
o Will start from the Jim Bridger Power Plant (Jim Bridger) in Wyoming to
southeastern Idaho with a connection south along an existing transmission
path from southern Idaho into northern Utah (Path C)
o Will be extended west across Idaho and into Oregon in a single-circuit 500 kV
construction
o These facilities will include 600-plus miles of line capable of delivering up to
3,000 megawatts of electricity from Wyoming to Idaho into Utah and up to
2,500 megawatts of new incremental capacity from Idaho west into Oregon
o
o
Additionally, a double-circuit 500 kV and 230 kV line will be extended from
Jim Bridger to a second hub (Aeolus) that would be located northeast of the
Miners substation.
Single and double-circuit 500 kV and 230 kV lines would extend from Aeolus
to Dave Johnston, and would be routed to optimize access to potential wind
resources.
Southern Route
o Double-circuit 500 kV transmission line
o Will start from southwestern Wyoming (Aeolus) with a connection into central
Utah at the Mona substation located in Juab County
o Will extend from the Mona or Sigurd area into southern Utah and the desert
southwest (Crystal near Las Vegas, Nevada and/or Four Corners, New
Mexico)
o These facilities will include 600 miles of line capable of delivering up to 3,000
megawatts from Wyoming to Mona, and 3,000 megawatts from the Mona
area into the desert southwest
Project Description
This transmission expansion plan includes the following elements (see Figure 1):
o Segment A – Walla Walla to Yakima 230.
o Segment B – Path C upgrade, will provide for additional resources to be
delivered from Idaho into the Utah – Wasatch Front.
o Segment C – Mona to Terminal segment, which includes the Mona to
Oquirrh segment. These transmission facilities will allow increased transfers
from central Utah to the Wasatch Front. This project could be upsized
subject to regional and customer needs.
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o
o
o
o
o
o
Segment D – Dave Johnston to Miners (Aeolus) to Bridger project. This
project will provide for the delivery of new Wyoming wind and thermal
resources to Jim Bridger. This project could be upsized subject to regional
and customer needs.
Segment E – Jim Bridger to Populus to Hemmingway project with Idaho
Power Company. This project is intended to meet future resource needs of
both PacifiCorp and Idaho Power, as well as other anticipated regional
needs.
Segment F – Aeolus to Mona. This project will provide for delivery of both
wind and thermal resources to central Utah. Final configuration, routing and
capacity are subject to regional planning processes and customer needs.
Segment G – Sigurd to Red Butte to Crystal. This project would be
developed based on resource needs of PacifiCorp. This project could be
upsized and extended to Mona, subject to regional and customer needs.
Segment H – Hemmingway to Captain Jack. This project would be
developed to support PacifiCorp west side load growth, renewable portfolio
standards, and regional and customer needs. The exact terminus in southern
Oregon is subject to completion of regional planning and rating processes.
Segment J – Four Corners to Mona. This project would be developed to
support based on regional transmission needs.
The Detailed Plan Description above has identified multiple lines and line segments
that, for study purposes, will be broken-down specific projects for evaluation. For
example, Segment B (Path C) will be evaluated separate from Segment H
(Hemmingway – Captain Jack); however, Segment E (Bridger – Populus – Midpoint
– Hemmingway) will be studies as one project. (The detailed plan-of-service for
each line segment has been included in Attachment B.) As studies move forward,
logical study segments will be proposed to the study groups and agreement will be
reached. To this end, the remainder of the study plan is generic in nature and
outlines the overall study approach that will be followed to evaluate specific projects.
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