Terry Baker Peak Reliability September 20th, 2015 San Diego Load Shed Event Terry Baker Peak Reliability

Brief Summary of Event Otay Mesa Energy Center (OMEC) was forced out of service due to emission issue in the plant. Based on values produced by Peak’s VSA Real Time tool, Peak determined that imports in the SDG&E area were approaching the real-time IROL. As a result, the Peak RC issued a Reliability Directive to the CAISO to shed 150 MW of load in the SDG&E area to maintain a sufficient margin away from the San Diego Import IROL as calculated by Peak’s real time VSA tool. In response, CAISO issued a Directive to SDG&E to shed interruptible load and subsequently to shed 150 MW of firm load.

A A – Otay Mesa Generation Offline

B B – Peak VSA calculates 0 MW limit when tool does not converge for critical contingency

C C – load shed

Lessons Learned Lessons learned for Real Time Tool: Modeling accuracy and data inputs are critical for our tools Assumptions need to be consistent (load modeling, RAS, capacitor switching, etc) Load shedding philosophy has been improved Coordination and Communication amongst the impacted entities

Moving Forward New standards approved which require outage coordination, Operational Planning Analyses and Real-time Assessments Path Operator Implementation Task Force and SOL Methodology revision Peak working with Idaho Power, SCE, and SDG&E to advance real-time VSA Focus continues to be on improving reliability through improved tools and processes

Questions?