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

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

3. 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

4. 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

5. 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.

6. 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

7. 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

8. 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

9. Link to Lessons Learned
Directions to Lessons Learned: Go to > “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.