NERC Lessons Learned Summary LLs Published in June 2015 – Part II

NERC lessons learned published in 2015 Two Additional NERC lessons learned (LL) published in June 2015 LL20150603 - Pre-Contingent Load Shed Event LL20150604 - EMS Recovery Strategy

Real-Time Contingency Analysis Failure due to a Modeling Error Pre-Contingent Load Shed Outage was planned to take a 345-kV circuit breaker out of service for retrofit and maintenance During the planning for this outage, a potential cascading outage was identified for certain conditions affecting generation and loading in the outage area Reliability Coordinator worked with the registered entities involved to develop an operating memorandum, which described shedding load if the pre-contingency conditions met specified parameters

Real-Time Contingency Analysis Failure due to a Modeling Error Pre-Contingent Load Shed Lesson Learned Communication and coordination is an essential aspect of implementing load shedding in order to minimize the impact to affected parties All potentially affected parties should be included in the planning and advised in advance Include the probable duration of the outage. Most should be of relatively short durations or may be rolling black outs. Planning for pre- and post-contingency actions is encouraged In the planning stage, an alternate plan should be considered in case assumptions made for initial plan change Consider expected temperature changes Planning for an outage that may require load shed should be considered only as a last resort

Real-Time Contingency Analysis Failure due to a Modeling Error Pre-Contingent Load Shed Lesson Learned Cont. BA’s and TOP’s should conduct training and drills with their customers (typically DPs and LSEs) on directing customer load shedding Training should include those who may be contacting the DP and LSE operators and the language of a directive using good three-part communication This helps the DP and LSE operators to have a method for identifying an authority who is giving an operating directive Consider the availability of demand-side management in lieu of load shedding In order for this to be effective, it must be considered early in the planning stage and requested early and possibly, in some cases, prior to the actual need arising.

Generator control system impact on Voltage Regulators EMS recovery strategy EMS auto recovery process was configured such that all nodes (servers, workstations) in the EMS were prompted to unload and/or reboot for a particular system condition This complete system restart sequence took 47 minutes to complete Led to a complete loss of control and monitoring functionality until the critical servers and workstations reported their statuses normal and fully functional

Generator control system impact on Voltage Regulators EMS recovery strategy Corrective Actions System was reconfigured such that if this scenario were to occur again, the entire system would not be prompted to unload and reboot Only the offending server would be impacted Lesson Learned Careful analysis of EMS system configurations that initiate a complete system restart should be performed during the commissioning of the EMS to identify and minimize the duration of EMS unavailability

Generator control system impact on Voltage Regulators EMS recovery strategy Lesson Learned Cont. EMS nodes (servers/workstations) should be prioritized during an auto recovery process such that essential nodes are up and available first to give operators the ability to monitor and control the electrical system as quickly as possible Recovery of non-essential servers, workstations, etc. could have a significant impact on the duration of a complete system restart time Scenarios should be evaluated that could trigger an application or system recovery due to a system condition Procedures should be developed and periodically reviewed to ensure minimal recovery time, and to familiarize staff on recovery processes

Link to Lessons Learned Directions to Lessons Learned: Go to www.NERC.com > “Program Areas & Departments” tab > “Reliability Risk Management” (left side menu) > “Event Analysis” (left side menu) > “Lessons Learned” (left side menu) NERC’s goal with publishing lessons learned is to provide industry with technical and understandable information that assists them with maintaining the reliability of the bulk power system. NERC requests that industry provide input on lessons learned by taking the short survey. The survey link is provided on each Lesson Learned.