What is the main goal of PRC-029-1?

To ensure IBRs remain connected and exchange current during defined frequency and voltage excursions.

How does PRC-029-1 differ from PRC-024?

It is performance-based, tailored to IBR characteristics, and includes ROCOF considerations.

What voltage thresholds are used?

Thresholds are measured at the high-side of the main power transformer, aligning with IEEE 2800-2022.

What defines compliance under PRC-029-1?

Field event performance is primary; models and simulations are supporting evidence.

What is momentary cessation?

A condition where IBRs stop injecting current—prohibited in the must ride-through zone.

What frequency ranges are covered in R3?

56–57 Hz and 61.8–64 Hz must be tolerated for at least 6 seconds.

Are exemptions allowed?

Only for legacy equipment under R4, with strict documentation and planner communication.

What is ROCOF and how is it treated?

Rate of Change of Frequency. Ride-through is mandatory for ROCOF ≤ 5 Hz/sec.

Is IEEE 2800 compliance sufficient?

No. PRC-029-1 may exceed IEEE 2800 requirements in some areas.

What is the Continuous Operation Region?

The voltage range where IBRs must fully return to pre-disturbance power.

Can IBRs prioritize reactive current?

Yes, by default. But transmission operators may require active power prioritization.

What is PLL loss-of-synchronism protection?

A trip mechanism when phase angle shifts exceed thresholds; should be disabled for BPS IBRs.

What’s the purpose of Attachment 1?

It defines ride-through voltage zones and durations.

How fast must current resume in permissive zones?

Within 5 cycles once voltage recovers.

Can IBRs block current in low voltage conditions?

Yes, temporarily in the permissive zone.

How should AVR be tuned?

To avoid overshoot or undershoot and enable stable voltage recovery.

What happens if AVR causes overshoot?

The overshoot must remain within Attachment 1’s limits.

Are frequency protection settings prescribed?

No. They must protect equipment but not interfere with R3 compliance.

Can ROCOF trip during faults?

No. ROCOF protection must be disabled during faults and fault clearance.

When is exemption communication required?

Upon documentation or removal of limitations.

Can IBRs with legacy controls be exempt from R3?

No. Exemptions apply only to voltage ride-through under R4.

How is ride-through evaluated?

Through field data from disturbance events and simulation studies.

Is modeling still required?

Yes, but as supplementary evidence to field behavior.

Can inverter units be individually exempt?

No. PRC-029-1 applies to the IBR plant as a whole.

Why is PRC-029-1 critical now?

With growing IBR penetration, system inertia is declining, increasing the risk of instability during disturbances

PRC-029-1 Explained: IBR Ride-Through & Compliance Guide

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As inverter-based resources (IBRs) increasingly dominate the power generation landscape, North American Electric Reliability Corporation (NERC) has taken a critical step with PRC-029-1—a standard developed to bridge the performance gap between IBRs and synchronous generators during system disturbances. PRC-029-1, titled “Frequency and Voltage Ride-Through Requirements for Inverter-Based Generating Resources,” outlines how IBRs must behave during frequency and voltage excursions, ensuring they contribute to, rather than destabilize, grid reliability.

Historically, PRC-024 addressed ride-through requirements but was found inadequate for managing IBR behavior during system events. The unique nature of IBRs—fast-switching, electronically interfaced resources—requires specialized performance criteria. Their control systems are programmable but constrained by equipment limits. As a result, inconsistent ride-through performance led to widespread reliability concerns, especially during major disturbance events.

PRC-029-1 not only aligns partially with IEEE 2800-2022, but also responds directly to mandates issued by the Federal Energy Regulatory Commission (FERC) in Order No. 901. It defines event-based criteria that reflect real-world IBR behavior during system faults, frequency dips, and voltage excursions.

What is the main goal of PRC-029-1?
To ensure IBRs remain connected and exchange current during defined frequency and voltage excursions.
How does PRC-029-1 differ from PRC-024?
It is performance-based, tailored to IBR characteristics, and includes ROCOF considerations.
What voltage thresholds are used?
Thresholds are measured at the high-side of the main power transformer, aligning with IEEE 2800-2022.
What defines compliance under PRC-029-1?
Field event performance is primary; models and simulations are supporting evidence.
What is momentary cessation?
A condition where IBRs stop injecting current—prohibited in the must ride-through zone.
What frequency ranges are covered in R3?
56–57 Hz and 61.8–64 Hz must be tolerated for at least 6 seconds.
Are exemptions allowed?
Only for legacy equipment under R4, with strict documentation and planner communication.
What is ROCOF and how is it treated?
Rate of Change of Frequency. Ride-through is mandatory for ROCOF ≤ 5 Hz/sec.
Is IEEE 2800 compliance sufficient?
No. PRC-029-1 may exceed IEEE 2800 requirements in some areas.
What is the Continuous Operation Region?
The voltage range where IBRs must fully return to pre-disturbance power.
Can IBRs prioritize reactive current?
Yes, by default. But transmission operators may require active power prioritization.
What is PLL loss-of-synchronism protection?
A trip mechanism when phase angle shifts exceed thresholds; should be disabled for BPS IBRs.
What’s the purpose of Attachment 1?
It defines ride-through voltage zones and durations.
How fast must current resume in permissive zones?
Within 5 cycles once voltage recovers.
Can IBRs block current in low voltage conditions?
Yes, temporarily in the permissive zone.
How should AVR be tuned?
To avoid overshoot or undershoot and enable stable voltage recovery.
What happens if AVR causes overshoot?
The overshoot must remain within Attachment 1’s limits.
Are frequency protection settings prescribed?
No. They must protect equipment but not interfere with R3 compliance.
Can ROCOF trip during faults?
No. ROCOF protection must be disabled during faults and fault clearance.
When is exemption communication required?
Upon documentation or removal of limitations.
Can IBRs with legacy controls be exempt from R3?
No. Exemptions apply only to voltage ride-through under R4.
How is ride-through evaluated?
Through field data from disturbance events and simulation studies.
Is modeling still required?
Yes, but as supplementary evidence to field behavior.
Can inverter units be individually exempt?
No. PRC-029-1 applies to the IBR plant as a whole.
Why is PRC-029-1 critical now?
With growing IBR penetration, system inertia is declining, increasing the risk of instability during disturbances

In 1995, Sandip (Sonny) R. Patel earned his Electrical Engineering degree from the University of Illinois, specializing in Electrical Engineering . But degrees don’t build legacies—action does. For three decades, he’s been shaping the future of engineering, not just as a licensed Professional Engineer across multiple states (Florida, California, New York, West Virginia, and Minnesota), but as a doer. A builder. A leader. Not just an engineer. A Licensed Electrical Contractor in Florida with an Unlimited EC license. Not just an executive. The founder and CEO of KEENTEL LLC—where expertise meets execution. Three decades. Multiple states. Endless impact.

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Navigating PRC-029-1- Enhancing Grid Reliability Through Inverter-Based Ride-Through Requirements

Introduction

The Driving Force: Why PRC-029-1 Was Developed

Key Features of PRC-029-1

1. Event-Based Compliance

2. Defined Frequency and Voltage Zones

3. FERC-Directed Enhancements

Detailed Requirements Breakdown

Requirement R1: Voltage Ride-Through Capability

Requirement R2: Voltage Performance During Disturbances

Requirement R3: Frequency Ride-Through

Requirement R4: Exemptions for Legacy Equipment

Implications for Developers, Owners, and Grid Operators

Integration with IEEE 2800-2022 and PRC-024

Conclusion

Technical FAQs on PRC-029-1