Project WECC-0100 Update Reliability Subcommittee

1. Project WECC-0100 UpdateReliability Subcommittee February 2014

2. 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

3. 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

4. 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?

5. 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?

6. 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

7. 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