Project WECC-0100 UpdateReliability 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 – 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

• 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

• 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

• 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. PRC-024) 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