2015 TEPPC Study Program
DRAFT for TAS Review
Studies Work Group
April 16, 2015
155 North 400 West, Suite 200
Salt Lake City, Utah 84103-1114
2015 TEPPC Study Program
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Table of Contents
Appendix A – 2015 TEPPC Study Program ................................................................................................ 12
Base Cases ............................................................................................................................................. 12
High Priority Studies.............................................................................................................................. 13
Medium or Low Priority Studies ........................................................................................................... 17
“Conditional” Studies ............................................................................................................................ 20
Studies with yet to be Determined Priority ............................................. Error! Bookmark not defined.
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Introduction
This document presents and discusses details of the 2015 Transmission Expansion Planning Policy
Committee (TEPPC) Study Program. TEPPC is tasked with conducting a biennial transmission system
study program (Study Program) as a component of WECC’s regional transmission planning process
(RTEP). The goals, processes and procedures of the Study Program were crafted, in part, as a response
to FERC Order No. 890 “Preventing Undue Discrimination and Preference in Transmission Service”
(Order 890). One of the provisions of Order 890 is to give transmission system stakeholders the right to
request a defined number of high priority studies annually. Recognizing that enforcement of this
provision on a provider-by-provider basis would be costly, and could result in duplicative studies and
could hinder sub-regional and regional coordination, FERC also allows transmission providers and
stakeholders to cluster or batch requests for economic planning studies to enable efficient
performance of such studies. The TEPPC Study Program, along with studies done by Transmission
Providers and sub-regional planning groups (using FERC parlance for regional and sub-regional
planning) together satisfy the requirements of Order 890, as appropriate to best meet the needs of
stakeholder study requests. The Study Program is based on inputs from multiple sources, including
requests from stakeholders that arise out of the provisions of Order 890.
The 2015 Study Program has been prepared under the provisions of the TEPPC Regional Transmission
Expansion Planning (RTEP) Protocol (TEPPC Transmission Planning Protocol). The Study Program for
this year is the first year of a new biennial transmission study program. The goal of the biennial study
program is to produce sets of study results that are analyzed and used in the preparation of a WECC
Interconnection-wide Transmission Plan (WECC Plan). The Study Program for this year details the
analytical activities that TEPPC will perform to evaluate the needs and weaknesses of transmission
system of the Western Interconnection under various conditions for future 10-year and 20-year time
horizons. Two time horizons will be studied as part of the 2014 Study Program.


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Ten-year Horizon (2026) – The 10-year time horizon will be used to evaluate the impact of
options to meet existing and potential future energy policies, and the impact technology
changes and external drivers may have on transmission needs and costs in the Western
Interconnection. All 10-year studies start with the 10-year Common Case, ensuring a common
point of reference exists for all 10-year studies performed and analyzed in the process of
creating a WECC Plan. The Common Case is based on stakeholder-provided assumptions
regarding loads, generation and transmission. The 10-year studies are conducted with a
production cost model.
20-year Horizon (2036) – A set of studies representing potential energy futures for a 20-year
study horizon will be evaluated using the WECC Long-Term Planning Tool (LTPT), a capital
expansion model (CXM). A desired outcome, in part, of the long-term studies is to identify
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those decisions that need to be made now in order to realize the potential energy futures being
evaluated.
The Study Program is developed to:
1)
2)
3)
4)
Respond to requests received under the provisions of the TEPPC Transmission Planning
Protocol.
Incorporate relevant study needs of regional planning groups, state authorities,
transmission providers and generators.
Develop needed models for production cost and transmission utilization studies.
Support the objectives of the WECC Strategic Plan by providing useful transmission insights
into the implications of major policy and technology changes for the future of the western
power system.
The list of proposed studies outlined in this document was prepared by the Technical Advisory
Subcommittee (TAS) from an initial clustering and consolidation of study requests prepared by the
Studies Work Group (SWG) for this planning year. The list includes study requests submitted under the
provisions of the TEPPC Transmission Planning Protocol during the request window period that ended
January 31 of this planning year (Study Request Open Season). The result of this process is the
proposed Study Program described herein. Prior to finalizing the Study Program, TEPPC will review
stakeholder feedback and requests for reconsideration.
Transmission Planning and the Study Program
The objective of TEPPC’s transmission expansion studies is to provide an Interconnection-wide
perspective on future transmission needs of the Western Interconnection. This information is useful to
transmission project developers, energy service providers, regulators, policymakers, and other parties
involved in making public policy and investment decisions that impact the Western Interconnection.
Since TEPPC’s work is one component of the many activities involved in the planning, building, and
operating of the transmission system, this section first covers WECC’s planning activities. Following
this, there is a brief description of the adaptive planning cycle of the TEPPC Transmission Planning
Protocol. Finally, the specific study methodology that will be used for this year’s TEPPC Study Program
is described.
TEPPC’s work complements and coordinates with other transmission planning related activities. These
include state and provincial integrated resource planning (IRP), regional planning group plans, state
and provincial renewable portfolio standards (RPS), analyses of renewables integration by the National
Renewable Energy Laboratory (NREL), the Western Electricity Industry Leaders (WEIL) studies, and the
numerous initiatives by the Western Governors’ Association (WGA).
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Purpose of Transmission Planning
Electric power networks are a unique part of our national infrastructure. With current technology,
long-distance high-voltage lines are not buried, so they become a visible part of the landscape through
which they pass. Transmission facilities also have very long lives, so decisions made today have longlasting effects. Therefore, the objective of long-term transmission planning is to make the best network
design decisions today after considering possible future needs and expansion options. Few, if any, 10year or 20-year transmission plans will come to fruition as originally conceived. However, by planning
for possible future needs, flexibility is built into the network’s design that allows options to be
exercised and adaptation to occur as future conditions are revealed.
TEPPC’s activities are an integral part of the Western Interconnection’s overall approach to
Interconnection-wide planning of the transmission system, which has two major aspects for
consideration:
1)
2)
System reliability—characterized as “keeping the lights on” while responding in a
predictable fashion to both planned and unplanned outages to generation and transmission
system elements.
System utilization,—a measure of the economic performance of the transmission system.
System production cost studies and associated capital cost estimates for those studies
provide answers to the question, “While operating within the bounds of reliable operation,
how well does the transmission system perform to deliver electricity services to consumers
at a reasonable cost?”
Regional Transmission Expansion Planning
WECC’s RTEP project is described in the TEPPC Transmission Planning Protocol. The TEPPC
Transmission Planning Protocol governs the transmission planning process used by TEPPC to support
transmission providers in meeting the transmission planning obligations of Attachment K to the
transmission providers’ Open Access Transmission Tariffs (OATT).
TEPPC Study Program Development
The Study Program for this year represents the first year of a new biennial RTEP study cycle. The
development of the annual Study Program is an adaptive process that uses results from previous study
programs to not only improve the quality of the cases, but to add new models or modify study
methodology to continually improve the results produced by each successive study program. This
expansion of planning activity is made possible, in part, by lessons learned in previous study programs.
Figure 1 is taken from the TEPPC Transmission Planning Protocol and presents the process for
developing a Study Program. The inputs presented in Figure 1 are used by the SWG to develop a
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consolidated list of studies. In preparing the consolidated list, the SWG looks for opportunities to
combine requests to meet multiple needs with a reduced number of studies. The consolidated list is
reviewed by TAS and forwarded to TEPPC for consideration. All stakeholders, including the parties who
submitted study requests, are invited to attend TEPPC meetings and participate in the prioritization
discussion. The consolidated list of studies is then adjusted based on the TEPPC discussion and posted
for review. Stakeholders are given an opportunity to request reconsideration of TEPPC’s proposed
Study Program before it is finalized.
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Figure 1. Study Program Development Process
Lessons Learned from Previous Study Cycles
Results from previous Study Programs will be used to create the current Study Program which will
inform the WECC Plan. As such, results produced from previous study programs will provide an
analytical foundation from which new studies can be performed and analyzed for use in the creation of
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a new WECC Plan. The list of proposed studies outlined in this document has been developed and
prioritized to reflect this goal.
In addition, the goal of each study program is to improve on previous study programs. As such, the
studies outlined in this document consider new issues/topics of Interconnection-wide significance, and
address gaps left by past study programs and plans.
Other Study Activities
In addition to the studies described in this report, TEPPC has ongoing activities that support its Study
Program effort.
•
•
•
WECC staff led effort to conduct historical analysis of system utilization.1
The SWG and Data Work Group (DWG) build the study databases needed for
simulation studies.
The Modeling Work Group (MWG) develops improved simulation models based on
needs identified in past studies.
Each of these activities is an important element of TEPPC’s adaptive approach to developing
transmission planning studies.
Types of Study Cases
Prior to the formation of TEPPC, a number of Western Interconnection transmission studies were
completed using production cost simulations. These studies stimulated an interest in economic
evaluation of transmission expansion and led to the formation of TEPPC. These studies were also
influential in triggering an interest in a number of major transmission projects now being developed
across the Western Interconnection. However, one of the concerns expressed regarding the early
studies was the inclusion of potentially redundant generation and transmission expansion proposals.
The presence of surplus generation and transmission tended to mask possible congestion – eliminating
it before it could be identified. To avoid this problem, the SWG uses a study methodology consisting of
two types of study cases: portfolio cases and expansion cases. The relationship between the two types
of study cases is shown in Figure 2 for a set of illustrative, hypothetical cases.
1
Historical analysis of actual flows has been conducted by WECC for the past 12 years.
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Figure 2. Simulation Study Case Relationships
Common Case and Reference Case
The Common Case and Reference Case are the Study Cases from which all other Study Cases are built.
The Common Case is the 10-year “expected future” based on a compilation of all the existing and 10year projected load, resources, and transmission. The Reference Case is the 20-year “possible energy
future” extending the trajectory of the 10-year Common Case assumptions another ten years into the
future.
Portfolio Cases
Portfolio Cases (PC) are developed to represent a possible pattern of future load and resource
development. The type and location of incremental resources will be different among portfolio cases,
based on the analysis of the WECC Loads & Resources information. Load and general policy changes
can also be included to reflect varying futures. For the network topology, portfolio cases use a
representation of the existing transmission plus new transmission for which construction is sufficiently
certain in the given horizon year. From the Common Case, additional Portfolio Cases are developed
that represent other possible patterns of load and resource developments.
The portfolio cases provide a hypothetical portfolio of resources that balance load and generation. In
past TEPPC studies, the incremental resources were added in three groups: 1) renewable resources
needed to meet the renewable portfolio standard (RPS) of a given state in the study year, 2) more
likely planned resources listed in LRS reports, and 3) enough conventional generation to achieve loadresource balance. Evaluation of a portfolio case is used to identify binding constraints that may suggest
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what additional transmission is needed to alleviate congestion. In other words, these are used to
evaluate the impact of different future market, regulatory, and policy conditions on the need for
transmission network expansion.
Sensitivity Cases
Sensitivity Cases are typically a set of studies consists of “single-parameter” changes within the load,
resource, and transmission assumptions of a Study Case. By changing a single variable or specific set of
variables such as hydro conditions or load, this set of studies informs stakeholders about how
deviations in the study case assumptions can impact on the initial study case’s results.
Expansion Cases
Expansion Cases (EC) are developed from portfolio cases by adding incremental transmission and/or
storage projects, or any other incremental piece of infrastructure that may provide operational or
economic benefit. This is the second step in the transmission study analysis to investigate the effect
that various transmission expansion options may have on system utilization. By reporting the impact
on system utilization and a capital cost estimate of different alternatives, stakeholders will be more
able to judge their interest in various projects and provide a basis for further project studies.
Power Flow Export Cases
Power Flow (PF) Export Cases are power flow models (PFM) that represent the system condition of a
specific hour within a production cost study case’s simulation.
Study Cases
“Study Case” generically describes other Study Cases that don’t fall into the above mentioned types of
study cases. Varies numerous inputs and/or assumptions of a specific study case to evaluate the
aggregate impacts (typically built from the Common Case)
Elements and Themes of the this Study Program
The consolidated list of proposed study cases prepared by the SWG and TAS is provided in Appendix A.
Because of the large number of study requests, only a limited number of study cases were given a high
priority, indicating the intent to complete them within the current study year. The remaining studies
were ranked as medium priority and will be completed as time permits.
An explanation of each proposed study cluster and general study approach is located at the beginning
of Appendix A. Once the Study Program is approved by TEPPC, the study formulation effort is kicked off
in a “scoping call” where the exact study specifications, timeline, and central study questions are
developed by SWG leadership, WECC staff, and the study requestor(s). TEPPC will rely on a number of
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study requestors to provide data needed for its study cases. Requests for this data will be
communicated clearly and in a timely fashion via the Study Scoping Form (Appendix D) that is filled out
in the scoping calls.
General Study Themes
This section describes the general study themes of the study programs (Appendices A and B). The study
themes represent the areas of interest where TEPPC would like to focus its attention while leveraging
both WECC analysis and studies being conducted by others.
Studying the Important Challenges to the Grid
Stakeholder requests influenced the Study Program to examine some important trends that pose
major challenges to the grid over the 10-year and 20-year study horizons. In particular, key topics to be
addressed are increasing levels of distributed generation, increasing levels of renewable generation to
meet evolving policy objectives, and the potential increase in coal plant retirements or displacements
(e.g., not explicitly retired as part of a study assumption, but rather displaced due to an indirect study
assumption such as high carbon costs) in the Western Interconnection. These scenarios strive to raise
and explore important questions about the reliability of the grid and whether the future system has
sufficient flexibility to meet increased levels of variable generation. The use of transmission expansions
to mitigate future stresses introduced by load growth and resource build-outs has and should continue
to be the focus of interconnection-wide planning efforts. In addition, it is important to explore and
study how new resource and transmission technologies (e.g., storage facilities, enhancements to
thermal ramping capabilities, synchrophasors, advantages of DC transmission lines) can be used to
mitigate future issues.
Unifying Planning Efforts and Tools
The desire to analyze the reliability and flexibility of the future grid requires adding new innovative
tools of analysis to transmission expansion planning. TEPPC has augmented its traditional use of the
production cost model (PCM) with a capital expansion model (CXM) by integrating a Long Term
Planning Tool (LTPT) developed by WECC to study potential long term energy futures (e.g., 20-years).
WECC is also working to further integrate its PCM, CXM, and power flow model (PFM). The PCM is ideal
for learning how efficiently the system may be utilized economically and where weaknesses exist and
under what conditions. The PFM is ideal for examining the reliability of the system in greater detail
through power flow (PF) analyses which could include contingency analysis, congestion analysis,
reactive voltage support, transfer capabilities, and dynamic stability, to name a few. The CXM, using
the LTPT, is ideal for gaining an understanding of potential energy futures and what investment
decisions might be needed in terms of future generation and transmission infrastructure.
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In order to improve continuity between 10-year, 20-year, adequacy, and reliability studies,
mechanisms and processes must be developed to strengthen the linkages between the WECC planning
models to create more cohesive and holistic sets of models. These mechanisms and processes must
enable a seamless conversion and exchange of data inputs and results between the various planning
models so that studies can be performed more holistically (e.g., build a PCM from the results of a CXM
and build a PFM from the results of a PCM).
Aging assets and retirement of major base load resources
The focus of some of the study cases is on learning and understanding the impacts of future generating
resource retirements in the 10-year horizon. The Western Interconnection needs to understand the
reliability and environmental implications associated with decisions to retire or maintain aging base
load resources.
Collaboration with other efforts beyond WECC
The core cases (10-year Common Case and 20-year Reference Case) serve as foundations for other
transmission expansion studies in the Western Interconnection. In addition to running and analyzing
the cases in the Study Programs, TEPPC is committed to maintain close ties with other study efforts to
provide support and maximize synergies.
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Appendix A – 2015 TEPPC Study Program
The following high priority studies will be undertaken by TEPPC and WECC. Some studies are focused on only 10-year production
cost model runs, while others ask for both 10- and 20-year analyses. Assumptions for studies featuring 10-year and 20-year analyses
have the opportunity to be aligned in this study cycle. 10-year production cost studies are designated with “2026PC” or “2026EC”
case IDs, 20-year capital expansion studies are designated with “2036PC” case IDs, and power flow (PF) export studies are
designated with “PF” case IDs.
WECC has taken steps to develop a common dataset and the analytical tools to link production cost modeling results into power
flow analysis for the purpose of analyzing reliability issues. The ability to move from production cost modeling to power flow
analysis has been referred to as performing a “roundtrip” analysis. At this time, however, TEPPC and WECC do not have the
capabilities to perform the roundtrip from production cost modeling to power flow analysis. The studies requesting a roundtrip
analysis are designated with a new “Conditional” priority in the 2015 Study Program. The Conditional priority recognizes the
importance and desire to the proposed studies but acknowledges that it is not technically possible for WECC staff to run such
roundtrip studies because of current limitations in the data sets and experience in using both sets of modeling tools. If WECC
develops the capability to perform the roundtrip capability, these studies would convert to the High priority status.
Common Case and Reference Case
Case ID
Case Summary
Common Case and Sensitivities
2026PC01
2026 Common Case
2036PC01
2036 Reference Case
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Requester(s)
High
High
WECC
WECC
L E C T R I C I T Y
Comments
10-year “expected future”, update 2024 Common Case
Jumps off from 2026 Common Case
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High Priority
Case ID
Case Summary
“Single Variable” Sensitivities
Priority
Requester(s)
2026PC02
10-year Increased Load
High/Pending
PG&E
2026PC03
10-year Decreased Load
High/Pending
PG&E
2026PC04
10-year Increased Hydro
High
PG&E
2026PC05
10-year Decreased Hydro
High
PG&E
2026PC06
10-year Increased Natural Gas Price
High
PG&E
2026PC07
10-year Decreased Natural Gas Price
High
PG&E
2026PC08
10-year Increased CO2 Price
High
PG&E
2026PC09
10-year Decreased CO2 Price
High
PG&E
High
PacifiCorp,
SPSC/WIRAB, High
Plains Express
Comments
Pending TAS resolution of on-going
discussions2
Coal Retirement / Low Carbon
2026PC10
10-year Coal Retirement / Low
Carbon Future
Refresh 2024 coal retirement cases
2
TAS Work Groups currently discussing three options: (1) simple +/- west-wide percent change for “robustness test”, (2) developing more complex study case
to represent likely extreme load futures (load & related impacts), and (3) sub-annual timeframe of extreme load (e.g., one or several extreme load days).
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Case ID
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Case Summary
Priority
2026EC10 Add High Plains Express
Requester(s)
Comments
 [Bill Pascoe, comment receved
4/8/2015] I've taken a quick look
at the draft study plan and am
generally satisfied with the
prioritization. My only significant
concern is with the High Plains
Express cases that are assigned a
"High" priority. These are the
High Plains Express
only project-specific cases in the
"High" category, the rest are
ranked as "Medium". I can see
no good reason for singling out
HPX for this special treatment.
HPX has been studied in past
TEPPC study cycles as have
TransWest, Centennial, etc.
High
20-year Coal Retirement / Low
High
Carbon Future
High Renewables West-wide & Test Possible Mitigations
2026PC11
10-year High RE west-wide
High
10-year High RE west-wide,
2026EC11a
High
consolidate BAs
2036PC10
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SPSC/WIRAB
Jumps off of 10-year case
SPSC/WIRAB
SPSC/WIRAB
High Plains Express
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Case Summary
Priority
2026EC11b Add High Plains Express
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Comments
 [Bill Pascoe, comment receved
4/8/2015] I've taken a quick look
at the draft study plan and am
generally satisfied with the
prioritization. My only significant
concern is with the High Plains
Express cases that are assigned a
"High" priority. These are the
High Plains Express
only project-specific cases in the
"High" category, the rest are
ranked as "Medium". I can see
no good reason for singling out
HPX for this special treatment.
HPX has been studied in past
TEPPC study cycles as have
TransWest, Centennial, etc.
High
10-year High RE west-wide, increase
flexible resources
10-year High RE west-wide, increase
2026EC11d
RE geographic diversity
10-year High RE west-wide, add
2026EC11e
storage resources
Increased Renewables in California
10-year 5% increase in California RPS
(38% total, ~+14,000 GWh) supplied
2026PC12
by additional renewables in WY and
CO
2026EC11c
Requester(s)
High
SPSC/WIRAB
High
SPSC/WIRAB
High
SPSC/WIRAB
Open for revision per review of the
status of CAISO studies to ensure these
High Plains Express
studies are complementary and not
duplicative to those studies.
High
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Case ID
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Case Summary
Priority
2026EC12 Add High Plains Express
Requester(s)
Comments
 [Bill Pascoe, comment receved
4/8/2015] I've taken a quick look
at the draft study plan and am
generally satisfied with the
prioritization. My only significant
concern is with the High Plains
Express cases that are assigned a
"High" priority. These are the
High Plains Express
only project-specific cases in the
"High" category, the rest are
ranked as "Medium". I can see
no good reason for singling out
HPX for this special treatment.
HPX has been studied in past
TEPPC study cycles as have
TransWest, Centennial, etc.
High
West Coast Offshore Resources
2026PC13
10-year +3000MW offshore
wind/wave & tidal wave resources
High
Oregon Wave
Energy Trust
2036PC13
20-year offshore wind/wave & tidal
wave breakthrough
High
Oregon Wave
Energy Trust
10-year Impact of De-Rating COI by
~30%
High
PG&E
Opportunity for DWG investigation:
Resource & transmission data exists,
just a matter of investigating/reviewing
Opportunity for DWG investigation:
Resource & transmission data exists,
just a matter of investigating/reviewing
Other
2026PC14
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PACI RAS, which reduces COI capability
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Medium or Low Priority
Case ID
Case Summary
High Renewables: New Mexico
Priority
2026PC20
Medium
10-year High RE in New Mexico
Requester(s)
Clean Line Energy
Partners
Clean Line Energy
Partners
Comments
Re-analysis of a past study case
2026EC20a Add Centennial West
Medium
2026EC20b Add Western Spirit
Medium
Clean Line Energy
Partners
Re-run/refresh of 2014 Study Program
study case. Connects wind farm to four
corners - not inter-regional.
Medium
Absaroka Energy
Re-run/refresh of 2014 Study Program
study case
Medium
Absaroka Energy
Re-run/refresh of 2014 Study Program
study case
Medium
Absaroka Energy
Re-run/refresh of 2014 Study Program
study case
Medium
TransWest Express
Medium
TransWest Express
Medium
High Plains Express
High Renewables: Montana
10-year Add Montana RE & swap out
Pacific Northwest RE, add Gordon
2026PC21
Butte Pumped Storage. Remove Path
8 upgrades if in Common Case
10-year Replace Colstrip with
Montana RE, add Gordon Butte
2026PC22
Pumped Storage. Remove Path 8
upgrades conditional per Common
Case
10-year Add more Montana RE &
2026PC23
swap out Pacific Northwest RE, add
Colstrip South transmission expansion
High Renewables: Wyoming
10-year Add 3000 MW of Wyoming
2026PC24
wind
Add TransWest Express
2026EC24
High Renewables: Wyoming & Colorado
10-year Add 12,000GWh of Colorado
2026PC25
wind
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Re-analysis of a past study case
Re-run/refresh of 2014 Study Program
study case
Re-run/refresh of 2014 Study Program
study case
Continuation of 2014 Study Program
study case
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Case Summary
2026EC25 Add High Plains Express
Priority
Requester(s)
Medium
High Plains Express
High Renewables West-wide & Test Possible Mitigations
10-year High RE west-wide & create
2026PC26
Low
EIM
High Plains Express Study Cases
SPSC/WIRAB
2026PC27
10-year EPA 111(d) Scenario
Low
High Plains Express
2026PC28
10-year “Special High Plains Express
Study Case”
Low
High Plains Express
Low
High Plains Express
Low
High Plains Express
Low
High Plains Express
Low
High Plains Express
2026PC29
2026PC30
2026PC31
2026PC32
10-year EPA 111(d) scenario with
Special High Plains Express Study
Case
10-year +12,000GWh of CO wind with
High Plains Express & Special High
Plains Express Study Case
10-year Re-run 2024EC25-1 PCM with
Special High Plains Express Study
Case
10-year Re-run 2024EC25-2 PCM with
Special High Plains Express Study
Case
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Comments
Continuation of 2014 Study Program
study case
EIM is beyond WECC TEP tools/models
(i.e., requires intra-hour PCM)
Refer to others’ analysis.
EPA 111(d) assumptions will be included,
to the extent possible, in the “Common
Case”
Partnered with SPSC High RE Westwide.
Assume significant increase in BA
Coordination (zero hurdle rates?), higher
carbon taxes, higher cost of natural gas
and lower capital cost for renewable
resources (Wind, Storage, and Solar)
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2026PC33
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Case Summary
10-year Increased Renewables for
California supplied by additional
renewables in WY, CO, AZ, & NM with
High Plains Express& Special High
Plains Express Study Case
Priority
Requester(s)
Low
High Plains Express
Low
Great Basin
Transmission
Comments
Other
2036PC34
20-year System-wide increase in
north to south transfer capability:
Boardman-Hemingway+SWIP-N,
increased PDCI capacity, increased
north-to-south capacity of Gateway
projects
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Uncertain on how to do with LTPT.
Maybe as a 10-year PCM?
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“Conditional” Priority
Case ID
Case Summary
Coal Retirement / Low Carbon
2026PF10
10-year Power flow analyses of 2024
or 2026 coal retirement study case
High DG West-wide
10-year High DG Power flow
2026PF35
analyses - focus on voltage and
frequency response issues
High Renewables: Wyoming & Colorado
Priority
Requester(s)
Comments
Conditional
PacifiCorp,
SPSC/WIRAB, High
Plains Express
See above for current treatment &
future possibilities.
Conditional
SPSC/WIRAB
See above for current treatment &
future possibilities.
Continuation of 2014 Study Program
study case. See above for current
treatment & future possibilities.
Continuation of 2014 Study Program
study case. See above for current
treatment & future possibilities.
2026PF36
10-year Analyze reliability or stability
issues in 2024EC25-1 (PF Analyses)
Conditional
High Plains Express
2026PF37
10-year Analyze reliability or stability
issues in 2024EC25-2 (PF Analyses)
Conditional
High Plains Express
Conditional
High Plains Express
See above for current treatment &
future possibilities.
Conditional
High Plains Express
See above for current treatment &
future possibilities.
Analyze reliability or stability issues
(PF analyses) in adding 12,000GWh
2026PF25
of Colorado wind & High Plains
Express
Analyze reliability or stability issues
(PF analyses) of 10-year Increased
2026PF12 Renewables for California supplied
by additional renewables in WY, CO,
AZ, & NM
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Appendix B - Glossary of TEPPC Terminology
AC: Alternating Current – A type of electrical current, the direction of which is reversed at regular
intervals or cycles. In the United States, the standard is 120 reversals or 60 cycles per second, denoted
as 60 Hz (Hertz).
DOE: U.S. Department of Energy – The federal agency designed “to advance the national, economic,
and energy security of the United States; to promote scientific and technological innovation in support
of that mission; and to ensure the environmental cleanup of the national nuclear weapons complex.”
DSM: Demand-Side Management – The term for all activities or programs undertaken by a LoadServing Entity or its customers to influence the amount or timing of electricity they use.
DWG: Data Work Group – The DWG collects and verifies data used in the TEPPC database for economic
studies of transmission planning. This data is made available to SPGs, developers, regulators, and
others.
EDTF: Environmental Data Task Force – A task force created by the SPSG to develop recommendations
on the type, quality, and sources of data on wild lands, wildlife, cultural resources and potential water
resources that can be used in transmission planning processes.
EE: Energy Efficiency – Programs and policies designed to reduce electric energy consumption or
increase the efficiency of electric loads.
FERC: Federal Energy Regulatory Commission – An independent federal agency that regulates the
interstate transmission of natural gas, oil, and electricity. FERC also regulates natural gas and
hydropower projects.
Generation – The process of producing electricity by transforming other forms or sources of energy
into electrical energy; measured in kilowatt-hours.
IRP: Integrated Resource Plan – A plan developed by an electric power provider, sometimes as required
by a public regulatory commission or agency, that defines the short- and long-term capacity additions
(supply-side) and demand-side management programs that it will undertake to meet projected energy
demands.
Load Center: A geographic area with a concentrated electrical load.
LSE: Load-Serving Entity – Secures energy and transmission service (and related Interconnected
Operations Services) to serve the electrical demand and energy requirements of its end-use customers.
MW: Megawatt – 1,000 kilowatts, or 1.0 million watts; standard measure of electric power plant
generating capacity.
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MWG: Modeling Work Group – The MWG evaluates and proposes improved models for production
cost simulation.
NERC: North American Electric Reliability Corporation – NERC is the electric reliability organization
certified by the Federal Energy Regulatory Commission to establish and enforce reliability standards for
the Bulk-Power System.
Path, or Transmission Path: A single or set of transmission lines with an established rating. There are 66
WECC-rated paths in the Western Interconnection. Paths are analogous to the term “flowgate” used in
other parts of North America.
PCM: Production Cost Model – An analytic representation of an electrical generation and transmission
system used to determine the most efficient dispatch of generation to meet system loads within the
reliability constraints on power system operations.
Renewable Generation – Energy derived from resources that are regenerative or for all practical
purposes cannot be depleted.
ROW: Right of Way – A corridor of land on which electric lines may be located. The Transmission
Owner may own the land in fee, own an easement, or have certain franchise, prescription, or license
rights to construct and maintain lines.
RPS: Renewable Portfolio Standard – A regulation that requires an established level of production or
purchase of energy from renewable energy sources, such as wind, solar, biomass, and geothermal.
Scenario – A plausible future that is defined by various economic, social, political, and technological
factors.
RPCG: Regional Planning Coordination Group – Coordinates regional planning activities of mutual
interest related to TEPPC activities.
RPCG Common Case Transmission Assumptions (CCTA) – The RPCG facilitated the preparation of and
developed the criteria for the RPCG Common Case Transmission Assumptions. The list identified
projects having a high-probability of being constructed by the 10-year study horizon year. These
projects provide an assumed minimum transmission system starting point for TEPPC’s future planning
studies, and are included as inputs into the WECC 10-Year Regional Transmission Plan.
SPG: Subregional Planning Group – An organization that coordinates planned transmission system
changes within a defined geographical area in the Western Interconnection. WECC currently recognizes
nine SPGs in the Western Interconnection:
1)
2)
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Alberta Electric System Operator (AESO);
British Columbia Coordinated Planning Group (BCCPG);
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4)
5)
6)
7)
8)
9)
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California Independent System Operator (CAISO);
Colorado Coordinated Planning Group (CCPG);
ColumbiaGrid;
California Transmission Planning Group (CTPG);
Northern Tier Transmission Group (NTTG);
Sierra Subregional Planning Group (SSPG); and
Southwest Area Transmission (SWAT).
SPSC: State-Provincial Steering Committee – The SPSC is composed of appointees from each state and
province in the Western Interconnection, and comprises one-third of the SPSG membership. The
Western States’ Water Council and the Western Governors’ Wildlife Council are ex-officio members of
the SPSC. The purpose of the SPSC is to provide input to Western Interconnection transmission
planning and analysis.
SPSG: Scenario Planning Steering Group – The SPSG is a multi-constituency steering group that
provides strategic guidance and direct participation in TEPPC activities. The purpose of the SPSG is to
provide: 1) strategic guidance to TEPPC; 2) scenarios to be modeled in transmission planning studies; 3)
modeling tools to be used; and 4) key assumptions to be used in creating and reviewing the scenarios.
Stakeholder – A person or entity interested or wishing to participate in WECC’s planning activities.
Study Case – A set of load, resource, and network topology conditions used to model the performance
of the Western Interconnection transmission grid.
Study Program – A set of studies, developed under the provision of the TEPPC Transmission Planning
Protocol, to be completed by TEPPC within that study year. Each Study Program is developed based on
consideration and prioritization of all study requests received for that year.
SWG: Studies Work Group – The SWG directs studies for which TEPPC is the study lead, establishes
assumptions, and confirms methodology.
TAS: Technical Advisory Subcommittee – TAS collects and disseminates data for historic and forwardlooking planning studies. TAS subgroups include the Data Work Group, Modeling Work Group, and
Studies Work Group.
TEPPC: Transmission Expansion Planning Policy Committee – A WECC Board committee that conducts
and facilitates economic transmission planning for the Western Interconnection. TEPPC activities
include fulfilling transmission owner/operator and Subregional Planning Group planning requirements
under FERC Order 890. TEPPC has a balanced membership comprised of individuals from WECCmember organizations and stakeholders.
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Transmission – An interconnected group of lines and associated equipment for the movement or
transfer of electric energy between points of supply and points at which it is transformed for delivery
to customers or is delivered to other electric systems.
WECC: Western Electricity Coordinating Council – The Regional Entity responsible for coordinating and
promoting Bulk Electric System reliability in the Western Interconnection.
WGA: Western Governors’ Association – An independent, nonpartisan organization of Governors
representing 19 Western states, and three U.S.-flag Pacific islands. The WGA identifies and addresses
key policy and governance issues in natural resources, the environment, human services, economic
development, international relations, and public management.
Western Interconnection – The interconnected electrical system that encompasses the provinces of
Alberta and British Columbia, the northern portion of Baja California (Mexico), and all or portions of
the 14 Western states in between.
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Appendix C - TEPPC 2015 Study Program Study Case Scoping Form
The purpose of this document is to define the overall scope of a TEPPC study case so that the study
requestor, TEPPC, and the WECC staff have a common understanding of the expectations and
limitations of the study that will be completed.
Study Case Name
Case Number
Study Requestor(s)
Date of Adoption
Study Timeframe
Priority
Study Case Summary(ies)
Key Questions to be Answered/Addressed by the Study
This information will be used to identify data inputs required for the study as well as key outputs that
should be communicated back to the study requestor.
1.
2.
Study Case Tasks
Requestor Task(s)
1.
2.
WECC Staff or Work Group Task(s)
1.
2.
Responsible Party(ies)
Completion Date
Responsible Party(ies)
Completion Date
Key Limitations
What issues will not be addressed by this TEPPC study due to limitations in time, resources, or modeling
tools?
1.
2.
Other Study Information
Link to background material (reports/analysis completed in support of study) and/or study results
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