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Regulatory Update

NERC Reliability Standard PRC-024-3 Approved: Frequency and Voltage Protection Settings for Generating Resources

Dylan Achey and Tim Farrar, PE | July 28, 2020

On July 9, 2020 NERC standard PRC-024-3 was approved, paving the way for improved protection systems in support of keeping generating resources connected during defined frequency and voltage excursions. The standard has a two-year implementation plan. Immediately prior to its effective date, PRC-024-02 will be retired.

PRC-024-3 clarifies the voltage and frequency protection setting requirements to assure that generating resources, including inverter-based resources, continue to support power system stability during system disturbances. The standard identifies the types of protection subject to the requirements and incorporates language used by inverter manufacturers and solar project developers, while ensuring correct protection settings for applicable generating resources.

PRC-024-2 standard was revised to address recommendations made by the NERC Inverter-Based Resource Performance Task Force (IRPTF) which were developed in response to NERC and WECC analysis of the Blue Cut Fire and Canyon 2Fire disturbances in southern California. Event analysis for both disturbances revealed that misinterpretation of the requirements of PRC-024-2 led to the intentional and unnecessary tripping of solar PV resources during these events. In addition to identifying the need to provide clarity around the intent and requirements in PRC-024-2, the IRPTF also found errors within the standard.

The expectations of generators regarding adherence to the no-trip boundaries for both system frequency and system voltage excursions for each interconnection in North America are the key technical components of the standard.

Next Steps for Successful Compliance

NERC standards are the minimum obligations that must be met for utility for reliable operation of the Bulk Electric System. Now is the time to begin planning for the changes needed to your company’s processes and procedures to implement the revised standard within your compliance program.

Utilities should evaluate their programs and processes in order to stay ahead of regulatory changes. Now is the time to consider what support you might need for further NERC Compliance program development, independent compliance assessment, pre-audit reviews and compliance documentation.


 About the TRC Power Delivery Practice

TRC’s approach to power delivery design balances solutions that incorporate appropriate standards, regulatory requirements, best practices and operational goals and budgets. Our work for public and private sector utility clients is a testament to our understanding of power delivery operations. Our successful application of technological solutions in a constantly evolving business and regulatory landscape will provide you with confidence regarding your compliance programs.

Our power system experts help you stay ahead of changing regulatory expectations because they are continually engaged with the regulatory process and know how to plan, design and install programs that address your financial, technical and scheduling goals including compliance with changing NERC standards and guidelines, as well as industry best practices.

 This regulatory update is a service to TRC’s utility clients, helping keep you informed of issues that impact your company’s electric system reliability risks along with related topics regarding future regulatory developments to help you achieve your company’s business goals.

Dylan Achey

Dylan Achey is TRC’s Manager of Generation Engineering Services. He has been leading the effort with TRC generation clients on evaluating and providing updates/information so that clients can meet applicable NERC standards. His highly technical staff perform NERC compliance standard evaluations as well as studies for both generation and transmission clients that need assistance on technical issues concerning NERC compliance. Contact Dylan at

Tim Farrar, PE

Tim Farrar is a licensed professional engineer and works as the Protection & Controls Chief Engineer in TRC’s Augusta, Maine office. He is also a Certified Control System Technician (CCST) and Licensed Electrician with an Associate Degree from Eastern Maine Technical in Electrical Power Technology. Tim has 28 years of experience in protection and controls systems engineering for electric utilities and power generation industries including 10 years at Central Maine Power Company and 18 Years in the consulting engineering business. He has held several positions at TRC as an Engineer, Supervisor of Automation and Controls and Electrical Engineering Manager prior to his current position as Chief Engineer.

Contact Tim at

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