Project WECC-0100 Update
Reliability Subcommittee
February 2014
TPL-001-4 Effective Dates
• FERC Acceptance October 17, 2013
• January 1, 2015
– R1 – maintain System models
– R7 – PC and TP study responsibilities
• January 1, 2016
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R2 – prepare annual Planning Assessment
R3 – steady state studies
R4 – stability studies
R5 – TP and PC criteria for voltage and transient performance
R6 – TP and PC criteria to identify system instability for ...
R8 – Distribution of Planning Assessment results
• January 1, 2021 – NCLL no longer allowed as corrective
action plan for certain Contingencies listed in Standard
Project WECC-0100 Scope
• WECC Board approved retirement of WR1, WR2, WR4,
WR5 upon effective date of NERC TPL-001-4
• WR3 (voltage stability margin), TPL-001-4 R5 and R6
– R5 – criteria for acceptable ss voltage limits, post-contingency
voltage deviations, and transient voltage response
– R6 – criteria or methodology used in analysis to identify System
instability for conditions such as Cascading, voltage instability, or
uncontrolled islanding
• TPL-001-4 is the Standard – Reliability need is for TP’s
and PC’s to have a criteria per R5 and R6
• Regional Business Practice is a Criteria to help meet the
Standard where consistency in WECC is important
Voltage Instability Criteria
Alternatives being discussed:
• Existing Criteria: At a minimum, verify power flow
convergence at 105% and 102.5% of (base/reference)
transfer or load levels
- Solution Divergence => Voltage Instability
• Concern about Existing Criteria: specifying a particular
methodology, not truly VS margin; questionable VS Test
– myriad reasons for solution divergence
• Alternative Criteria: Demonstrate actual margins (real
and reactive) > minimum by using post-contingency P-V
and V-Q analyses
(as per “WECC Voltage Stability Criteria – Guideline”)
• Other?
Transient Voltage Performance
Alternatives being discussed:
• Apply extrinsic documents by reference
– Apply PRC-024 generator LVRT curve to generator busses to ensure resources
stay connected for planning contingencies
– Apply PRC-024 generator LVRT curve to generator and load busses to
demonstrate acceptable performance, evaluate risk
– Apply PRC-024 generator LVRT curve to generator busses and something else
to load busses to demonstrate acceptable performance
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Drafting concerns
– As “extrinsic” documents such as PRC-024 change – so does the WECC-0100
document
– Incorporation by reference means WECC loses control of administration
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Operational concerns
– Concern raised about expected ride thru of loads (that is NCLL)
– Concern raised about expectations of ride thru of loads for 3-Phase faults
– FIDVR considerations
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Other?
Steady State Voltage and Voltage Deviations
Alternatives being discussed:
• Steady state voltage limits are individual system
dependent, if an individual system does not have a
criteria then specify a default for those systems
• Voltage deviation may be covered by transient voltage
response if a voltage ride-through type curve (e.g. PRC024) is utilized
Instability for Cascading and Uncontrolled Islanding
Cascading and Uncontrolled Islanding not allowed for
planning contingencies
Alternatives being discussed:
• Point to existing NERC Glossary definitions
• Create a “criteria or methodology” (R6) to identify/detect
the potential for its occurrence, e.g.
– Post-contingency Line loading exceeds relay
loadability setting (determined in PRC-023)…
potential trigger for thermal cascading
– Poorly damped rotor-angle oscillations or unstable
power swings… potential trigger for uncontrolled
system separation