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Key Takeaways from NERC’s Technical Conference on FERC Order 909

  • meganzeeb
  • Nov 26
  • 2 min read

Sing Tay

Lead NERC Compliance Specialist

Elevate Energy Consulting



wind farm

FERC Order No. 909 (issued July 2025) approved PRC-029-1 (IBR ride-through performance) and PRC-024-4 (synchronous generator protection) and directed NERC to resolve three major issues with PRC-029-1: (1) legacy equipment limitations; (2) HVDC-connected IBR challenges; and (3) long-lead-time equipment constraints. NERC’s November 4, 2025 workshop gathered industry feedback to inform required rule refinements and future filings with FERC.



1. Legacy Equipment & Documentation Challenges

Core Issue: Older IBR facilities lack consolidated documentation and validated models needed to demonstrate whether hardware limitations prevent full compliance with PRC-029-1.

Key Points

  • Retrieving documentation is difficult for 10–20+ year-old equipment: missing firmware history, outdated specs, replacement components, lost OEM support, or unavailable diagnostic tools.

  • Equipment capability must be assessed at the plant level—not down to individual subcomponents.

  • Nameplate data is insufficient; OEM-provided capability documentation is required.

  • Studies (RMS preferred; EMT only where necessary) are essential to validate plant-level ride-through capability, especially when OEM documentation is incomplete.

  • Measurement-based verification is possible but impractical, as it would require plants to fail ride-through events.

  • OEMs may provide statements confirming limitations for exemption requests under R4.

  • Survey: Majority of stakeholders favor revising PRC-029-1 language to clarify acceptable documentation when hardware limitations cannot be directly proven.



2. HVDC-Connected IBRs & Chopper Limitations

Core Issue: PRC-029-1 requires ride-through performance that HVDC chopper systems physically cannot meet due to thermal limits.

Key Points

  • Choppers dissipate excess active power during voltage dips to prevent DC overvoltage and system trips.

  • Chopper resistors can absorb 1 p.u. for ~2 seconds; PRC-029-1 requires four 1.2-second dips within 10 seconds - far exceeding design limits.

  • Cooling times for these large resistors are 15–25 minutes, making consecutive-dip performance infeasible.

  • IEEE 2800 includes explicit allowances for chopper limitations; PRC-029-1 does not.

  • Retrofitting chopper systems is impractical - equipment is massive and custom-built.

  • Survey: Stakeholders split between modifying Attachment 1 to reflect thermal limits or revising R2 to allow exceptions.

Consensus: The standard should be revised to acknowledge physical limitations rather than relying on case-by-case exemptions.



3. Long-Lead-Time (LLT) Projects

Core Issue: Projects that procured equipment before PRC-029-1 was approved may be unable to meet the new requirements once they reach commercial operation.

Key Points

  • LLT projects typically ordered inverters years ago; redesigning equipment mid-project is infeasible.

  • Without exemptions, many gigawatts of already-financed projects could face cancellation or multi-year delays.

  • Proposed exemption criteria include:

    • Using executed interconnection agreement or EPC contract date (cutoffs debated: July 24, 2025 (FERC approval date) or Oct 1, 2026 (PRC-029-1 effective date)), or

    • Requiring a TP/PC reliability assessment confirming no adverse system impact.

  • Reliability impacts remain uncertain: Some argue exemptions only affect extreme events, while others warn that concentrated non-conforming resources could pose regional risks.

  • Survey: Industry split between date-based criteria vs. TP/PC-based reliability review.



Looking Ahead

FERC deadlines:

  • A NERC determination for any PRC-029-1 revisions within 12 months.

  • An 18-month post-exemption report analyzing system-wide reliability impacts.

This signals increased regulatory scrutiny and a long-term expectation that all grid-connected resources ultimately meet essential reliability functions, including fault ride-through.



How Elevate Can Support

Elevate assists clients with:

  • PRC-029-1 compliance planning and documentation

  • Protection and control setting reviews

  • OEM coordination

  • Simulation studies (PSCAD, PSS®E, PSLF)

  • Preparing exemption documentation

  • PRC-028 disturbance monitoring and PRC-030 event analysis readiness

For support or assessments, contact info@elevate.energy or visit www.elevate.energy.


 
 
 

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