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 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