In reaction to industry concerns over its proposed ride-through requirements for inverter-based resources, NERC submitted a filing April 18 “providing additional clarity” on stakeholders’ concerns to FERC.
NERC submitted PRC-024-4 (Frequency and voltage protection settings for synchronous generators, Type 1 and Type 2 wind resources, and synchronous condensers) and PRC-029-1 (Frequency and voltage ride-through requirements for IBRs) to the commission in November 2024.
Commissioners issued a notice of proposed rulemaking the following month that indicated it would pass both standards, with an added requirement that NERC provide two informational filings after they go into effect relating to PRC-029-1 and its provision for exemptions to voltage and frequency ride-through requirements for existing or “legacy” IBRs. (See FERC Approves NERC Assessment, Seeks Comment on IBR Standards.) FERC proposed that the filings be due 12 and 24 months after the conclusion of the standards’ exemption request period.
The commission called for stakeholder comments. NERC replied March 24 requesting that it be required to submit a single filing 18 months after the exemption period ends. (See Stakeholders Call for Further IBR Standard Revisions.) The ERO’s most recent filing responded to issues raised by other industry respondents.
NERC began by addressing comments from the American Clean Power Association (ACPA), the Solar Energy Industries Association (SEIA), Ørsted Wind Power America and the Western Interconnection Regional Advisory Body. According to NERC, these groups suggested the process for developing PRC-029-1 “did not allow full stakeholder engagement.”
These claims arose from the unusual circumstances of the standard’s development, beginning in August 2024 after the standard failed to receive industry approval in a formal ballot round. With a deadline from FERC approaching, NERC’s Board of Trustees voted for the first time to exercise its authority under Section 321 of the ERO’s Rules of Procedure to streamline the normal development process.
The board ordered NERC’s Standards Committee to hold a technical conference to gain industry input, then revise the standard and submit it for a formal ballot. This revised standard received a 77.88% weighted segment value supporting passage in October 2024.
NERC recounted this history in its response, arguing it had “provided reasonable notice and opportunity for public comment, due process, openness and balancing of interests” during development, including the use of “a commission-approved process,” as it referred to Section 321.
The ERO affirmed the final standard had been revised with input from the technical conference, contrary to the stakeholders’ claim, and that NERC submitted the standard to the board along with a report of minority issues raised during development. NERC concluded the standard development process was “in full accordance with Section 215 of the Federal Power Act.”
The organization also discussed concerns raised by stakeholders about the proposed exemptions, which NERC said were considered by some to be “too narrow and limited” and by others to “impermissibly [favor] legacy IBR owners.”
Among the first group were the ACPA and SEIA, which sought to have the exemptions expanded to include resources that have executed an interconnection and primary design, procurement and/or construction agreement by the effective date of the standard.
The latter included the Louisiana Public Service Commission, which feared “transmission owners and operators are expected to mitigate an event consisting of an unknown number of IBRs disconnecting at any time in the future, in an unanticipated manner.”
In response, NERC reminded FERC that its order to develop IBR ride-through standards required it to allow exemptions for IBRs “that are unable to modify their coordinated protection and control settings to meet the [standard’s] requirements.” It said the exemptions in PRC-029-1 were “consistent” with the order, which “expressly limited NERC’s discretion.”
NERC acknowledged commenters’ concerns that the detail required in PRC-029-1 “may prove difficult or … impossible” for legacy IBRs to meet. But it said the idea of finding operational limits “is neither new nor novel” and suggested there are multiple ways to identify relevant issues. For this reason, NERC concluded its “limited and documented exemptions are consistent with” FERC’s directives.
In response to Ørsted, Union of Concerned Scientists and other commenters that suggested PRC-029-1 should align with the IEEE 2800 standard for interconnection and interoperability of IBRs, NERC argued the IEEE standards are “adopted voluntarily … and are applied for their own business benefit.” By contrast, NERC said its responsibility is to reduce risks to grid reliability and safety.
The ERO said the standard drafting team did consider the ride-through terms and tables in IEEE 2800. However, the team concluded that the IEEE standard contained clauses that “drafted in a manner that is enforceable within the current structure of NERC’s Compliance Monitoring and Enforcement Program.” IEEE 2800 also is not a publicly available standard, NERC continued, making it harder for responsible entities to access it.
Finally, NERC said PRC-029-1 “was developed specifically to address the commission’s directives” and therefore is more stringent than the IEEE standard. Because of this added stringency, NERC said there is no conflict between PRC-029-1 and IEEE 2800.
