Inverter-Based Resources Risk Element

Recent system events (such as the June 2022 Odessa Disturbance in ERCOT; the Southwest Utah disturbance in April 2023; and the California battery storage disturbances in April/May 2023) have highlighted the importance of IBRs in supporting grid reliability. During each of these occurrences, system disturbances resulted in a reduction of IBR generation far from the location of the initiating event.

In March 2023 NERC issued a Level 2 alert, “Inverter-based Resource Performance Issues,” to investigate this concern. Collected data indicated that nearly 5,200 MW of the Bulk Electric System (BES) IBRs have voltage and frequency protection settings that are set within the NERC PRC-024, “no trip zone,” which can impact the reliability of the Bulk Power System (BPS) as outlined in the 2024 ERO Compliance Monitoring and Enforcement Program (CMEP) Implementation Plan (IP).

The 2024 ERO CMEP IP describes risks that will be priorities for the ERO  this year. Understanding and accurately modeling IBR characteristics to improve ride-through capability and support normal fault BPS events is a priority for the ERO. Registered entities that own or operate IBRs, or are connected to IBRs, should expect to see the following Standards in their engagement scopes if they have not been included in a prior recent engagement: FAC-001, FAC-002, PRC-024, and MOD-026.

While evaluating compliance during an engagement, Texas RE audit teams look at the preventive, detective, and corrective controls an entity has in place to mitigate overall risks. For the Facility interconnection requirements risks, entities should consider the below controls based on their registration and applicability:

• Transmission Owners
  • Having a process to periodically review, track, and communicate updates to Facility interconnection requirements, and a process to perform gap analysis for current IBR interconnections based on any changes.
  • Having controls to perform verification of changes to Facility interconnection requirements for new IBR interconnections.
• Generator Owners
  • Having controls to ensure Facility interconnection requirements are documented and made available within 45 days to anyone requesting it.
  • Having a process that defines what it means to “materially modify” generation facilities.
• Transmission Planner or Planning Coordinator
  • Having processes that define what it means to “materially modify existing interconnections” and the “reliability impact.”
  • Having documented processes that specifically address studies for IBR interconnections.

The Engagement Common Questions on Texas RE’s website provides additional insights on processes compliance staff could focus on during an engagement. Texas RE’s engagement observations are fed back to the risk team as part of the internal feedback loop and may be reflected in the entity’s Compliance Oversight Plan.