Protection System Settings

During a recent NSRF meeting, I discussed the importance of accurate protection system settings to ensure reliable operations of the Bulk Electric System (BES). Setting your applicable frequency and voltage protections to enable generation units to Ride-through disturbances is imperative. On October 1, 2026, PRC-024-4 will replace the current protection settings Standard, PRC-024-3. Version 4 will apply to synchronous generators, type 1 and type 2 wind resources, and synchronous condensers. Simultaneously, a new Standard, PRC-029-1, will become effective and will apply to both BES inverter-based resources (IBRs) and non-BES IBRs that have an aggregate nameplate ≥20 mVA and are connected to a common point of connection ≥60 kV (Category 2).

Similar to the prior version, PRC-024-4 will contain frequency and voltage protection criteria in R1 and R2, respectively. Entities must remain connected and be able to Ride-through during defined frequency and voltage events, and if an entity has a known equipment limitation that prevents its Facility from meeting the protection criteria, the entity must document the limitation per R3. If your Planning Coordinator or Transmission Planner requests your protection settings, then you must provide those settings within 60 days of the request in accordance with R4.

With the growth of IBRs, the ERO Enterprise recognized a need for specific Ride-through criteria for these generators and developed PRC-029-1. R1 and R2 address voltage Ride-through capabilities, and R3 governs frequency Ride-through capabilities. Requirement R4 acknowledges that in certain situations, a Generator Owner (GO) may have a hardware limitation that prevents it from meeting the protection system's setting criteria. The ERO Enterprise is currently developing an Align Periodic Data Submittal (PDS) to submit a R4 limitation spreadsheet and evidence to the Secure Evidence Locker (SEL). For more information regarding the required evidence, refer to R4.1.1 through R4.1.5 of PRC-029-1. The PRC-029-1 Implementation Plan (IP) states that for IBRs that were in service prior to the effective date of the Standard, R4 equipment limitations will be due by January 1, 2027.

The PRC-029-1 IP also bifurcates the design and operations elements of R1-R3 deadlines based on a generation unit’s commercial operations date (COD) and if the unit is a BES or non-BES IBR. The first deadline is for BES IBRs with COD on or before the effective date of the Standard; it requires 100 percent of units to be in compliance by October 1, 2026. Non-BES IBRs must be compliant by January 1, 2027. However, the ERO Enterprise understands that there is currently a backlog for GOs to receive vendor support to design and implement these settings in the field. For this reason, the ERO Enterprise is currently developing a practice guide to outline a CMEP approach that allow Enforcement discretion for certain PRC-029-1 deadlines. More information will be released to industry when this approach is finalized.

It is important to note the differences between ERCOT NOGRR245 criteria and PRC-029-1 requirements. While the two regulations share similarities, they are distinct requirements; generally, NOGRR245 has a broader Ride-through zone, and the ERCOT regulation also permits exemptions for both software and hardware limitations. In contrast, PRC-029-1 only allows for hardware limitations.

Overall, the upcoming PRC-024-4 and PRC-029-1 Standards will adapt the regulations for protections settings to the changing generation mix of the power grid. With electric demand continuing to grow in Texas, it is critical that GOs collaborate closely both internally and with equipment manufacturers to implement accurate settings to remain online during excursions and provide reliable service across the ERCOT region.