Effective Trade Day (TD) 6/14/17, the California ISO will temporarily increase its daily procurement of operating reserves to mitigate reliability risk against potential loss of solar resources which are susceptible to tripping due to faults on the transmission system.
On June 8, 2017 the North American Electric Reliability Corporation (NERC) completed their investigation and published a report on the August 16, 2016 disturbance event where the loss of approximately 1,200 MW of photovoltaic (solar) generation impacted the Western Interconnection. The findings in the report uncover a reliability gap in frequency measurement errors that can cause erroneous tripping of photovoltaic (solar) generation. A link to the NERC announcement and report can be found at http://www.nerc.com/news/Headlines%20DL/Inverter%20060817.pdf.
Although the NERC and Western Electricity Coordinating Council (WECC) operating reserves requirement for the California ISO Balancing Authority Area is not affected and does not change, the California ISO, in response to NERC’s findings, has assessed its current portfolio of photovoltaic (solar) generation and will temporarily adjust its operating protocol (starting TD 6/14/17) to procure more operating reserves to minimize the potential impact due to loss of inverter power injection during a single transmission contingency event.
As a result, Market Participants will see an increase in the amount of reserves procured via Open Access Same-Time Information System (OASIS). More operating reserves are expected to be procured during solar production hours. The new target total operating reserve procurement will be set to the maximum of NERC/WECC required operating reserves and up to 25% of the total solar production forecast. The California ISO will assess this percentage and adjust to maintain system reliability as needed based on system topology, transmission system conditions and remediation of the underlying inverter issue.
