State of the Interconnection 2025
Reportable Events
System events are a measure of the health of the system and are an indication of where the system may be challenged. The number of reportable events on the system increased slightly in 2024 due to a rise in incidents involving IBRs.
Protection System Misoperations
The correct operation of protection systems is a key measure of system performance. The misoperations rate has decreased over the last four years. This continues a decade-long decline in misoperations resulting from a concerted effort between WECC and industry.
Energy Emergency Alerts
The number and duration of Energy Emergency Alerts (EEA) increased in 2024. Extreme weather events can drive an increase in EEAs; nearly half of the EEA-3s issued in 2024 occurred during the winter storms Gerri and Heather.
System Events
Reportable Events
There were 35 reportable events on the bulk power system in the Western Interconnection in 2024, up from 34 events in 2023. This includes the first Category 2 event or higher since 2021.
Four of the events in 2024 were related to IBRs. Most of the events were tied to poor coordination between relay settings. The slight increase in events in 2024 indicates a need for better coordination between systems and pieces of equipment. The severity of events on the bulk power system had not increased since 2021.
The Category 2 event was due to an incorrect equipment setting following maintenance. This resulted in the forced outage of a wind facility but no loss of load. The rest of the events were Category 1.
Protection System Misoperations
Misoperations involve the unexpected performance of protection systems, which are critical components of the grid that remove faults from the system and protect sensitive equipment. Misoperations occur when the protection equipment does not perform as designed for a range of reasons. They can contribute to generation and transmission outages.
The misoperations rate has declined each year since 2021, and the 2024 rate (4.6%) was the lowest since 2020.
Unplanned Transmission Outages of Three or More Elements
Although most unplanned transmission outages involve only a single element, outages involving three or more elements pose a higher risk to reliability. The number of outages involving three or more elements decreased in 2024 for the third consecutive year. This decline is not significant, but it has been steady, and it coincides with a similar decline in the number of protection systems misoperations. Outages involving three or more transmission elements are usually tied to the misoperation of a protection system, so the improved performance of the protection system may be the reason for the decline in transmission system events.
Energy Emergency Alerts
In 2024, there were 30 EEAs, up from 21 in 2023. Eighteen of the EEAs reported in 2024 were EEA-3s, the most severe level. However, all but one of the EEA-3s occurred in two Balancing Authorities, and nearly half of the EEA-3s occurred during winter storms Heather and Gerri in January 2024.
The duration of EEAs also increased from an average of 2.47 hours in 2023 to 4.28 hours in 2024. The duration of EEA-1 events increased to 4.47 hours in 2024, up from 1.94 in 2023.
Extreme weather (variability and extreme temperatures) continues to be the biggest driver of EEAs across the interconnection as it leads to surging demand and the potential to impact generation. NERC’s 2024 Long-Term Reliability Assessment found that over half of the continent faces a potential shortage of electricity in the coming years, due to a confluence of factors including surging demand growth, the retirement of baseload generation, and the increase in energy-limited generating resources. Uncertainty related to extreme weather compounds this risk.
CAISO's proactive collaborative approach to mitigating IBR disturbances
The California Independent System Operator (CAISO) is collaborating with resource owners to better understand how recent IBR-related incidents have occurred to improve reliability of IBRs. This is following a number of incidents in which IBRs tripped offline during minor disturbances.
A root cause analysis of a 2023 California event identified several energy storage resources that did not respond properly to a low-frequency event. CAISO worked with resource owners and managers of the storage assets to investigate the disturbance and determined that incorrect settings on the storage resource caused the problem. CAISO identified a lack of clarity and understanding about the settings and worked with the owner and operator to help them better understand and correct the issue.
Although the need to provide industry-wide awareness for the appropriate settings required for IBRs to ride through minor grid disturbances remains, CAISO's swift work to understand and help resolve the problem serves as a model for mitigating future events involving IBRs.
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