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NERC Primers

A Primer on NERC's Rules for IBRs


The rapid interconnection of bulk power system (BPS)-connected inverter-based resources (IBR) is the most significant driver of grid transformation and poses a high risk to BPS reliability. The speed of this change continues to challenge grid planners, operators, protection engineers, and many other facets of the electricity sector. Implemented correctly, inverter technology can provide significant benefits for the BPS; however, the new technology can introduce significant risks if not integrated properly.

New Rules for Inverter-Based Resources

The North American Electric Reliability Corporation will soon have new requirements for Generator owners of Inverter-based resources. The ERO continues to stress the need for industry action in multiple areas to address the systemic reliability risks posed by inverter-based resource performance issues. Multiple disturbances that involve the widespread reduction of solar photovoltaic (PV) resources have occurred in California and Texas.
  • Inverter Based Resources are expected to and required to be able to ride through without tripping or reduction in capability for normal system disturbances that fall within predetermined criteria.
  • The below references are links to other disturbances similar in nature that have occurred in recent years.
Odessa Event: Location of Affected Facilities
Areas Affected by the Odessa Disturbance

ERO Recommendations

Transmission Owners
  • Establish or improve clear and consistent interconnection requirements for BPS-connected inverter-based resources
    • NERC FAC-001 and FAC-002
  • Adopt NERC Reliability Guidelines comprehensively

Generator Owners/Operators

  • Incorporate NERC Reliability Guideline material into practices
    • Strengthen contractual agreements with OEMs and vendors
  • Ask questions when lacking clarity
  • Improve monitoring and analysis of plant performance

Transmission Planners & Planning Coordinators

  • Improve modeling and study requirements per NERC Reliability Guideline recommendations
    • Develop EMT modeling requirements
    • Establish strong model quality requirements and continuous model update requirements
  • Identify plants performing differently than models –seek corrective action

When Will Inverter-Based Resources Be Required to Register with NERC?

In the past, IBRs with a capacity below 75 MW were not considered part of the Bulk Electric System (BES) Definition. However, recently, FERC instructed NERC to eliminate the minimum capacity requirement for including IBRs in the BES I4 category. Consequently, any IBRs using inverters that could impact the BPS will now need to be registered with NERC. Within the next 90 days, NERC is tasked with developing the criteria for registering these new entities and establishing the relevant Reliability Standards. This process may involve introducing a new functional registration and necessitate the creation or revision of Reliability Standards.
To read the full report from NERC, click here.
To access a copy of NERC’s recently filed Work Plan, go to:

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