Report by NERC and WECC says reduction of solar resources could cause reliability risks

A new report reveals that the widespread reduction of solar photovoltaic (PV) resources could be a significant reliability risk to the bulk power system (BPS).

The new report, issued by the North American Electric Reliability Corp (NERC) and the Western Electricity Coordinating Council (WECC), cited four disturbances in the summer of 2021 in Southern California as an example. These disturbances caused a widespread reduction in power from BPS-connected solar PV resources, specifically in areas of high penetrations of solar PV and wind resources. These four disturbances emphasize the need to ensure BPS-connected solar PV resources are operating reliably to support the BPS.

“This report shows the continued reliability impacts of inverter-based resources connected to the BPS,” Howard Gugel, NERC’s vice president of Engineering and Standards, said. “NERC continues to stress the importance of understanding how these resources react to grid disturbances, ensuring they provide essential reliability services and developing mitigation strategies to reduce negative reliability impacts.”

The report offered three recommendations for the industry to mitigate these concerns. One is to reinforce the recommendations from the Odessa Disturbance Report. The NERC Odessa Disturbance Report outlined a number of strong recommendations to address reliability gaps or issues for the reliable operation of BPS-connected inverter-based resources, mainly solar PV resources.

The second is to update and improve the FERC Generator Interconnection Agreements. The report says that all the performance issues identified in the NERC disturbance reports stem from a lack of performance requirements. These four events show that most of the affected facilities had minimal interconnection requirements applied to them. Therefore, they introduced adverse impacts to the Bulk Electric System in aggregate.

The third is to reinforce the fact that improvements to NERC Reliability Standards are needed to address systemic issues with inverter-based resources.

“There is no doubt that the penetration of inverter-based resources will increase, not just in California, but throughout the Western Interconnection,” Branden Sudduth, WECC’s vice president of Reliability Planning and Performance Analysis, said. “We need to get to the point where we have confidence in the models and actual performance of these resources. We have a lot of work to do to get to this point, but we have efforts in place to ensure that the legacy equipment is performing as optimally as possible while ensuring the performance of new plants exhibits the ride-through capabilities we know these resources are capable of. We believe the recommended alterations to certain standards will clearly set the expectation of how these resources are to be modeled and perform.”

NERC and WECC strongly recommend that the industry take timely action to implement all of these recommendations.