Transcript Path Concept Task Force

WECC Path Concept Task Force
Report to PCC
March 26, 2014
Chifong Thomas
Topics
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Recap
POTF New Paradigm and Potential Implication
for Planning
Next Steps
Recap
• The Path Concept White Paper was
approved by the PCC and posted on the
PCC Documents web site
• New PCC Path Concept Task Force was
populated to continue work with the POTF
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Path Concept Task Force (PCTF)
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Chuck Matthews (BPA)
Jim Tucker (Deseret G&T)
Abbas Abed (Navigant)
Don Johnson (Portland General Electric)
Gordon Dobson-Mack (Powerex)
Brian Keel (SRP)
Chifong Thomas (Smart Wire Grid) - Chair
Rabi Kiran (SCE)
David Franklin (SCE)
Peter Mackin (USE)
Bob Easton (WAPA-RMR)
Branden Sudduth (WECC)
Ultimate reliability objectives
• To ensure that Facility Ratings and voltage
limits are not exceeded in both the pre- and
post-Contingency state
• To ensure that stability limits are not
exceeded in the pre-Contingency state.
Pre-Contingency stability limits are
established to ensure pre- and postContingency BES stability.
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POTF Conclusions/Recommendations
that can Impact Planning Processes
• The “Path SOL” concept goes away:
o While Facility Ratings and voltage limits pre- and postContingency are always SOLs, a Path itself does not
have an SOL. The only time the Path itself has an SOL
is when the Path happens to coincide with a monitored
stability limit.
o Instead, a Path has a Transfer Capability or Total
Transfer Capability (TTC) as defined in the NERC
Glossary of Terms
• Exceeding an established Transfer Capability or a TTC in
real-time does not constitute SOL exceedance
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POTF Conclusions/Recommendations
that can Impact Planning Processes
• Operators should monitor actual Path flow against predetermined TTC values to provide operator awareness of
when reliability issues might be expected to occur
• WECC Path Ratings serve as a TTC cap for WECC
Paths.
• TTC still needs to be determined:
o Transfer analysis studies need to be run throughout the operations
horizon to determine stability limits – even if voltage or thermal
constraints are encountered at lower transfer levels
• Proposed to have agreements and understanding of who
calculates TTC for every ATC Path in WECC.
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Changes in Operator Activities that can
impact Planning Process
• For TTC – Run transfer analysis studies ahead of
time to determine the Path TTC.
• Allocates the Path TTC among TOPs who operate TTC
Facilities on that WECC Path.
• For Reliability – Run transfer analysis studies
ahead of time to determine stability limits and to
identify thermal and voltage limitations that could
be encountered.
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Changes in Operator Activities that can
impact Planning Process
• SOL exceedances (as indicated by real-time tools) to
be mitigated by the most appropriate or effective
means:
• With internal congestion management tools (CAISO
and BPA have these), and/or
• Locally according to operational plans and procedures,
or Op Guides, and/or
• With interconnection-wide congestion management
tools administered by Peak RC.
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Remaining Issue(s) that can Impact
Planning Process
How do nomograms fit in to the new
paradigm?
• Possible Solutions:
o Nomograms determine TTC, not SOL.
o TOP that identified flow interactions between
two ATC paths needs to continue to coordinate
on TTC establishment for those paths.
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Questions for Planning Processes
• If Path Ratings are TTC caps, and nomograms determine
TTCs
o Can the real-time Path flow exceed the established
Path Rating?
 If so,
 Should the potential exceedance be estimated ahead of realtime?
 Should the TTC facility owner(s) be required to request a TTC
exceedance?
 How should impacts on other systems due to real-time TTC
exceedance be accounted for?
 How would the planner know when this happens and plan for
system improvements?
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Questions for Planning Processes
o If a Path Owner requests to increase the
seasonal or real-time Path TTC, would the
Path Owner then be required to go through the
Path Rating Process?
 If not, what does it mean to have an Accepted
Rating?
o Other issues?
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Next Steps
• Identify issues and develop solutions
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Questions?