NERC Published Lessons Learned July 2017

NERC Lessons Learned Four new NERC Lessons Learned (LL) were published since July 2017: LL20170701 – Loss of Wind Turbine due to Transient Voltage Disturbance on the BPS

Loss of Wind Turbines due to Transient Voltage Disturbances on the BES - Details Voltage disturbance events on the transmission system in Australia and Texas highlighted concerns with voltage ride through in some wind turbine control system parameters Multiple (five or more) voltage excursions could result in wind turbines ceasing to provide MWs (breakers closed but zero MWs) Lesson Learned document discusses the Australia Blackout and five different events in Texas

Loss of Wind Turbines due to Transient Voltage Disturbances on the BES - CA Units were identified where this is an issue and the simultaneous trip of these wind plants was reclassified as a credible contingency Worked with each GOP to determined if voltage ride- through settings were set to disconnect or reduce output if three to six voltage ride-through events were detected Wind plant operators and the turbine manufacturers proposed improved voltage ride-through settings for consideration

Loss of Wind Turbines due to Transient Voltage Disturbances on the BES - LL Wind GOs should review and verify the voltage ride- through capabilities of their equipment and communicate to BA and connected TOPs to ensure that models correctly reflect those capabilities If BAs and TOPs are notified of a units lack ride through capability, BAs and TOPs should communicate to RC BAs, TOPs, and RC should consider in their daily resource plan the potential for the loss of these resources during transmission faults on the power system BAs, TOPs, and RCs should take appropriate mitigating measures

Loss of Wind Turbines due to Transient Voltage Disturbances on the BES - LL Wind GOs should review and verify that UPS and “Smart Crowbar” systems within the wind turbines are maintained and functioning properly High speed PMU data is critical for visibility into the magnitude of voltage disturbances related to the loss of wind turbines

Ways to Access Lessons Learned On the NERC website, Go to www.NERC.com > Click on the “Program Areas & Departments” tab and click “Reliability Risk Management” Then on the left side menu under “Event Analysis” click “Lessons Learned” Link to Lessons Learned At the lower left corner of the NERC.com homepage http://www.nerc.com/pa/rrm/e a/Pages/Lessons-Learned.aspx At the lower left corner of the NERC.com homepage

Contact Hassan Hamdar (hamdar@frcc.com) or FRCC EA (EA@frcc.com) Contract NERC LL: NERC.LessonsLearned@nerc.net