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PRC-028-1
Disturbance Monitoring and Reporting Requirements for Inverter-Based Resources
PRC-028-1 requires the Generator Owner of an applicable inverter-based resource to record sequence of events, fault and dynamic disturbance data at the plant, synchronize it to UTC, keep it, and provide it on request in standard formats. PRC-029-2 relies on this data as the evidence of how a plant actually performed during each excursion, and it also supports model validation.
Who it applies to
- Generator Owners that own Elements associated with BES inverter-based resources.
- Generator Owners of non-BES inverter-based resources that have, or contribute to, an aggregate nameplate capacity of 20 MVA or more, connected through a system designed primarily to deliver that capacity to a common point at 60 kV or above.
Key dates
- April 1, 2025: effective date.
- April 1, 2028: R1 to R7 in place at 50 percent of an entity's BES inverter-based resources that were in commercial operation by April 1, 2025 (all of them if the entity has only one).
- January 1, 2030: R1 to R7 in place at all BES inverter-based resources in commercial operation by April 1, 2025, and at all non-BES inverter-based resources in commercial operation by May 15, 2026.
- Newer resources: comply within 15 months of the effective date or at commercial operation, whichever is later.
- R8: applies from January 1, 2026 for BES inverter-based resources and from April 1, 2027 for non-BES inverter-based resources.
GridStrong procedure
GS-PRC-028-0001
A template procedure written to the standard. Send it back to us with your document template and we convert it into your organization's format and design automatically, with the roles mapped to your team.
Source
NERC PRC-028-1 (standard page)October 4, 2026
Requirements
What each requirement asks for, in plain English.
R1 · Sequence of events recording (SER)
What it means. Record breaker position for the breakers on the main power transformer, collector buses, and shunt static and dynamic reactive devices. Inverters and turbines record their fault codes, fault alarms, and voltage and frequency ride-through mode status when triggered by a ride-through or a trip. IBR units in commercial operation before the effective date record these only if they are capable of it; units reaching commercial operation later must record them.
Evidence an auditor expects. Device configuration and settings, station drawings, and sample SER records.
R2 and R3 · Fault recording (FR)
What it means. Triggered recordings of phase-to-neutral voltage, phase and residual current, and three-phase real and reactive power at the high side of the main power transformer and at the collector feeder breakers, and three-phase reactive power at shunt dynamic reactive devices. Each record has at least two cycles before the trigger and 2.0 seconds in total, at 64 samples per cycle or more, with triggers on residual overcurrent, over- and undervoltage, and over- and underfrequency.
Evidence an auditor expects. Device specifications and trigger settings, and actual records or derivations showing the quantities, sample rate and record length.
R4 and R5 · Dynamic disturbance recording (DDR)
What it means. Continuous recording at each main power transformer of one phase-to-neutral or positive-sequence voltage, the matching current, three-phase real and reactive power, and frequency, sampled at 960 samples per second or more and recorded at 60 times per second or more.
Evidence an auditor expects. Device configuration, data storage capability, and sample DDR records.
R6 · Time synchronization
What it means. All SER, FR and DDR data is synchronized to UTC. Inverter and turbine clocks stay within 100 milliseconds; every other device stays within 1 millisecond.
Evidence an auditor expects. Time-synchronization status or indication for each device.
R7 · Retention and delivery
What it means. Keep data retrievable for 20 calendar days and provide it within 15 calendar days of a request, unless the requestor grants an extension, to the Transmission Planner, Planning Coordinator, Transmission Operator, Balancing Authority, Reliability Coordinator, Regional Entity or NERC. SER goes in CSV; FR and DDR in CSV or COMTRADE (IEEE C37.111); file names follow COMNAME (IEEE C37.232).
Evidence an auditor expects. Dated transmittals to each requester with the formatted records.
R8 · Restore failed recording
What it means. Within 90 calendar days of discovering a recording failure, restore it or submit a Corrective Action Plan to the Regional Entity, then carry out the plan on its timeline.
Evidence an auditor expects. Records of the discovery date and restoration date, SCADA records, and dated CAP transmittals with evidence the plan was implemented.
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