NOGRR 245

2.6.2.1 · Frequency ride-through

What it means. At the POIB, the resource rides through 58.8 to 61.2 Hz continuously, and for at least 540 seconds from 61.2 to 61.6 Hz and from 58.4 to 58.8 Hz, and at least 299 seconds from 61.6 to 61.8 Hz and from 57.0 to 58.4 Hz. Beyond those bands it may ride through or trip; nothing requires it to trip. If over- or underfrequency, rate-of-change-of-frequency, anti-islanding or phase angle jump protection is installed and activated to trip, it must let the resource ride through beyond the table to the maximum level the equipment allows. The resource injects current, does not reduce active current while ride-through is required except for primary energy source availability, as allowed in the voltage sections, or to provide frequency response, and its plant, turbine or inverter controls must not disconnect it or block current exchange. Capability is maximized by December 31, 2025, or at synchronization for IBRs synchronizing after that, and the Resource Entity tells ERCOT the date. Maximizing means software, settings, firmware and parameterization changes, including memory upgrades to accommodate them, that do not modify other Resource equipment. Resources with an SGIA executed before August 1, 2024 that have not made those changes ride through the temporary table in Section 2.6.2.1.1.

Evidence ERCOT expects. Dated frequency, rate-of-change-of-frequency, anti-islanding and phase angle jump settings for the inverters or turbines and the plant controller compared with the Section 2.6.2.1 table, original equipment manufacturer (OEM) documentation of the maximum frequency capability, and the dated notice to ERCOT of the date capability was maximized.

2.9.1.1 · Preferred voltage ride-through

What it means. At the POIB, the resource rides through Table A (WGR IBRs) or Table B (photovoltaic and energy storage resource, or ESR, IBRs). Both tables require continuous operation from 0.90 to 1.10 per unit and 1.0 second from 1.10 to 1.20 per unit, and allow ride-through or trip above 1.20 per unit. Below 0.90 per unit, Table A requires 3.0, 2.5 and 1.2 seconds in the 0.70, 0.50 and 0.25 per unit bands, and Table B requires 6.0, 3.0 and 1.2 seconds; lower voltages follow a straight-line function, with a floor of 0.16 seconds (Table A) or 0.32 seconds (Table B) at the lowest voltages. For multiple excursions the time is cumulative over a ten-second window. Outside the continuous range the IBR keeps delivering pre-disturbance active current unless a reduction is needed for voltage support or specified by ERCOT or the interconnecting Transmission Service Provider (TSP), and returns to pre-disturbance real power no more than one second after POIB voltage recovers to the normal operating range, unless ERCOT allows a slower rate. It does not use phase angle jump or rate-of-change-of-frequency measurements to reduce output or trip during faults and recovery within the profile. Instantaneous overcurrent or overvoltage protection uses filtered quantities or time delays, and AC instantaneous overvoltage protection uses a measurement window of at least one cycle. These IBRs also meet sections 5, 7 and 9 of IEEE 2800-2022, applied at the POIB and the IBR unit terminal as appropriate, unless the Protocols, Operating Guides or Planning Guide clarify, modify or exempt them.

Evidence ERCOT expects. Inverter or turbine and plant protection and control settings compared with Table A or B, OEM documentation of IEEE 2800-2022 capability, and model quality test results for the ride-through profiles, which under the Dynamics Working Group (DWG) Procedure Manual also document the maximized low and high voltage ride-through (LVRT and HVRT) capability in the format of the Guide's tables.

2.9.1.2 · Legacy voltage ride-through

What it means. At the POIB, the resource rides through 0.90 to 1.10 per unit continuously; 1.0 second from 1.10 to 1.15, 0.5 seconds from 1.15 to 1.175 and 0.2 seconds from 1.175 to 1.20 per unit; and, below 0.90 per unit, a straight line from 0.15 seconds at zero voltage to 1.75 seconds at 0.9 per unit. Above 1.20 per unit it may ride through or trip. Paragraphs (4) to (7) set current injection, one-second real power recovery, phase angle jump and instantaneous protection rules parallel to the preferred section. The Resource Entity maximizes performance within equipment limitations no later than December 31, 2025 or the Commercial Operations Date, whichever is later. Until a resource completes the work to maximize its ride-through capability, it complies with the ride-through requirements in effect on May 1, 2024 (Section 2.11(2)).

Evidence ERCOT expects. Dated protection and control settings compared with the legacy table, OEM documentation of maximum capability, and the dated notice to ERCOT that the work to maximize ride-through capability is complete.

2.11 · Ride-through capability reports

What it means. A Resource Entity that believes its resource has maximized, or will maximize by December 31, 2025, its ride-through capability submits accurate models reflecting field settings. A resource with an SGIA executed before August 1, 2024 that could not comply by December 31, 2025 had to file, by April 1, 2025 through ERCOT's Resource Integration and Ongoing Operations (RIOO) system, an Initial Frequency Ride-Through Capability Report and/or an Initial Voltage Ride-Through Capability Report. Each report gives current capability in the Guide's table format, known limitations, a detailed description of the technical limitation with a letter signed by an officer or executive of the OEM (or its successor support company) or an engineering consulting firm, the software, firmware, settings or parameterization changes to be made, expected post-modification capability, a schedule, and a model reflecting all limitations. When the work is complete, the Resource Entity informs ERCOT.

Evidence ERCOT expects. Dated RIOO submissions, the signed OEM or consultant letters (or the notarized attestation the Guide allows when a letter cannot cover the whole plant), the models submitted, and the dated completion notice.

2.12 · Extensions and exemptions

What it means. For a resource with an SGIA before August 1, 2024, the notice of intent to request an exemption had to be filed with its April 1, 2025 capability report, no new notices are allowed after that date, and an exemption may rest only on the limitations identified in that report. Extension requests were also due April 1, 2025 unless ERCOT approves otherwise. ERCOT, in its sole and reasonable discretion, will grant an extension when all of these conditions exist: circumstances beyond the requester's reasonable control prevented meeting the deadline, the request shows good-faith efforts to minimize the extension, the requester has provided accurate models with all limitations, and the date does not exceed December 31, 2027 (SGIA before August 1, 2024) or December 31, 2028 (later SGIA). While an exemption or extension is in place, the documented maximum capability becomes the performance requirement. If a new software, firmware, settings or parameterization change becomes available for an exempt resource, the Resource Entity submits an implementation plan within 90 days and, once ERCOT approves it, implements it within 180 days unless ERCOT approves a longer timeline. The Guide still says the exemption process will come from a subsequent NOGRR, but the PUCT instead adopted Substantive Rule 25.517 (effective July 10, 2025), which now governs exemption requests: ERCOT assesses each request for threshold reliability risk, and ERCOT required complete capability reports, models and an Exemption Request Form by September 15, 2025.

Evidence ERCOT expects. Dated extension requests and notices of intent, OEM documentation of limitations and proposed modifications, ERCOT's written determinations, and any implementation plans with their approval and completion dates.

2.13 · Apparent failure to ride through

What it means. If a resource does not ride through in accordance with its applicable requirements, including its documented maximized capability, the Resource Entity, as soon as practicable, investigates the Apparent Performance Failure, reports the cause to ERCOT, and performs model validation and reports the results. It then develops a plan to meet the applicable requirements, submits it to ERCOT within 90 days, and implements it within 180 days of approval unless ERCOT approves a longer timeline. A failure where POIB conditions exceeded the Required Criteria but stayed within documented maximized capability is reported to the Reliability Monitor only if the Resource Entity does not fully meet those steps.

Evidence ERCOT expects. Event investigation records and data, the cause report to ERCOT, model validation results, and the dated plan, ERCOT approval and implementation record.

For inverter-based plants

NOGRR 245 is written for inverter-based resources and also covers Type 1 and Type 2 wind generators, which are not inverter-based. Measurement is at the Point of Interconnection Bus, not the inverter terminal, except where IEEE 2800-2022 unit requirements apply at the unit terminal.