By Carl Curry, NERC Reliability Specialist
NERC released the 2024 State of Reliability (SOR) report and SOR Overview in June, 2024, which provides an assessment of the Bulk Power System (BPS) based on performance of the grid for the entire year of 2023. Data for the report was taken from industry reporting systems. This article will provide a summary of the report, findings, and conclusions of the study of the grid operating results for 2023.
Key Finding #1: Response to Severe Weather Events Confirms the Overall Resilience of the BPS
The report points out that while 2023 did not experience extreme weather events to the extent seen in previous years, the BPS did perform well under regional severe weather events such as flooding, winter weather events, summer heat waves, and storms. This finding shows the importance of weatherization of generation facilities along with actively managing, monitoring, and responding to changing weather conditions. EOP-011-2 was issued and became enforceable in 2023 to ensure adequate weather preparation is being completed and documented, with EOP-012-1 to be effective in 2024. To ensure future weather event readiness, continue to evaluate winter preparation procedures, survey heat tracing and freeze protection, follow up with repairs where needed, conduct annual training as required, and follow up with a post-season review of winter operations.
Graphic from: Billion-Dollar Weather and Climate Disasters | National Centers for Environmental Information (NCEI) (noaa.gov) as shown in the NERC SOR Overview.
Key Finding #2: Generation Forced Outage Rates Continue to Increase
This finding was based on a review of resources by fuel and revealed that while coal units improved from last year, they continue an overall increasing trend over the past several years. This trend is attributed to increased age, additional maintenance requirements with reduced resources, and increased cycling/lower service hours.
Wind resources have experienced increased forced outage rates (18.9% WEFOR in 2023 vs. 18.1% in 2022). This metric is a concern as more wind resources have been commissioned in recent years, but expanded reporting requirements will provide more data for the future evaluation of these resources.
The report observes that traditional energy planning and strategies may need to be modified to take the risks of these findings into account, on both short term and long-term basis, and NERC standards are proposed to be released in 2024 to address these concerns. NERC also provides long term assessments of resource adequacy through the Long-Term Reliability Assessment (LTRA), Summer Reliability Assessment, and Winter Reliability Assessments. A Working Group has also been created to assess the resource adequacy of the BPS as the resource mix evolves.
Key Finding #3: Performance of Inverter Based Resources (IBR) Continues to Impact the BPS
With the increased role of solar and wind resources, Inverter Based Resources continue to impact BPS reliability in some regions. Sudden generation losses and system stability issues, some with repeat occurrences, have been noted. Future oversight and mitigation of these risks will be required, as more of these resources are utilized and relied on. The report notes that control software upgrades have been effective in some instances in improving the system disturbance response of these resources. In addition, NERC is changing registration requirements for IBRs, developing new or modified Reliability Standards for IBRs, and collecting additional generating and event data in 2024 for wind, solar, battery energy storage systems (BESS) facilities.
Key Finding #4: Texas Interconnection Reliability Performance Improves While Facing New Challenges
The Texas interconnection has used BESS to support frequency while relying on additional variable generation resources to support load requirements, and to provide energy and ramping support during evening down-ramp of solar generation. The Texas Interconnection also showed a decrease in the misoperation rate and essentially unchanged generation and transmission outage rates in 2023 as compared to previous years.
Further Information
For more information on the findings and conclusions of this study, refer to the NERC Technical Assessment of 2023 Bulk Power System Performance report, as detailed in the 2024 State of Reliability issued in June, 2024.