Enhancing Grid Resilience: Inside NERC’s PRC-029-1 Ride-Through Standard for Inverter-Based Resources

Introduction

The evolving nature of the electric power system has brought both challenges and opportunities—especially in maintaining grid reliability amid rising integration of inverter-based resources (IBRs). As synchronous generators retire, IBRs like solar PV, wind turbines, and battery energy storage systems are increasingly connecting to the Bulk Power System (BPS). In response, the North American Electric Reliability Corporation (NERC) developed PRC-029-1, a new reliability standard to address shortcomings in PRC-024-3 by providing specific, modernized frequency and voltage ride-through requirements.

This blog reviews the PRC-029-1 Technical Rationale, detailing key performance expectations, IEEE 2800 alignment, FERC Order No. 901 directives, and compliance implications for generator owners and planners.

The Need for PRC-029-1

A New Paradigm in Generation

Unlike synchronous generators, inverter-based resources rely on fast-switching power electronics governed by software controls—not mechanical inertia. Their different response to disturbances has led to variable and often inadequate ride-through behavior.

Grid Reliability Challenges

Numerous disturbance events have exposed weaknesses in IBR performance. PRC-024-3 lacked clarity for IBR operations during transients. PRC-029-1 resolves this by introducing explicit requirements for voltage and frequency ride-through, momentary cessation prevention, and grid support during events.

Foundation and Regulatory Backdrop

FERC Order No. 901: The Catalyst

FERC Order No. 901 initiated the need for revised standards. It directs NERC to:

• Ensure IBRs ride through voltage and frequency events
• Ban momentary cessation in must ride-through zones
• Require current injection and resynchronization
• Allow exemptions under strict documentation protocols

The PRC-029-1 Technical Rationale aligns with IEEE Std 2800-2022 while maintaining regulatory consistency.

Explore NERC Order No. 901 Compliance

Key Ride-Through Requirements of PRC-029-1

Requirement R1: Voltage Ride-Through

IBRs must stay connected and exchange current during voltage events. Key elements include:



• Defined must ride-through zones (per IEEE 2800)
• PLL synchronization under rapid phase shifts
• Loss-of-synchronism protection deactivation
• Tolerance for 25 electrical degrees of phase angle jump
  

Requirement R2: Voltage Performance Criteria

R2 specifies response by region:



• R2.1: Return to pre-disturbance active power
• R2.2: Reactive current injection in the mandatory zone
• R2.3: Current blocking in the permissive zone; recovery in ≤5 cycles
• R2.4: Controlled post-fault recovery
• R2.5: Resume full operation unless otherwise instructed
  

Requirement R3: Frequency Ride-Through

Requires 6 seconds of continuous operation during 56–64 Hz frequency swings. Adds:

• ROCOF trip only if >5 Hz/sec
• ROCOF must be disabled during faults

Averaging ≥0.1 seconds for ROCOF calculations

See PRC-029-1 Compliance Guide

Requirement R4: Legacy Exemptions

Legacy IBRs unable to meet R1 or R2 can apply for exemptions if:

• Clearly documented and justified
• Affected voltage ranges specified
• Shared with Planning Coordinator, Transmission Planner, and Reliability Coordinator
  

Design Philosophy: Event-Based Compliance

PRC-029-1 prioritizes field performance over theoretical simulations. Compliance is measured by IBR behavior during actual grid events, although dynamic modeling still supports planning.

Implementation and Stakeholder Responsibilities

For Generator Owners and Operators (GOs)

GOs and TOs (for VSC-HVDC) must:



• Configure inverters and controls for compliance
• Meet frequency/voltage thresholds
• Disable incompatible protection settings

For Planning and Transmission Coordinators

PCs and TPs must:



• Model exemptions
• Validate AVR tuning and reactive current injection
• Coordinate with IBR operators

Industry Impact and Future Outlook

PRC-029-1 enhances grid reliability through:



• Precise frequency/voltage expectations
• Flexibility for legacy equipment
• Real-world compliance auditing

As implementation progresses to 2030, stakeholders must:

• Audit existing IBR fleets
• Update control and modeling parameters
• Prepare for enforcement

Conclusion

NERC PRC-029-1 is a foundational shift in how inverter-based resources are regulated. It supports the transition to a low-inertia, decarbonized grid while demanding higher ride-through performance. With field-based compliance and FERC Order No. 901 directives, IBR owners must take proactive steps to meet evolving expectations.

For full compliance support, modeling services, and simulation consulting, visit: Nerc Compliance Service.

FAQ: PRC-029-1 Ride-Through Compliance for Inverter-Based Resources (IBRs)