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Regulatory Updates

Revisions to FAC-001 and FAC-002 Submitted for FERC Approval

Dylan Achey | Jim Whitaker, PE | July 12, 2022

Revised FAC-001 and FAC-002 Mandatory Standards Submitted for FERC Approval

On June 14, 2022 NERC submitted its modifications to the FAC-001 and FAC-002 reliability standards. The proposed Reliability Standards FAC-001-4 and FAC-002-4 contain new and revised requirements that would establish the Planning Coordinator as the entity responsible for defining changes to existing interconnected Facilities. The proposed Reliability Standards would resolve the uncertainty and confusion that has arisen regarding the meaning of “materially modify” under the currently effective standards.

Clarifying the Requirement to “Materially Modify”

FAC-001 and FAC-002 work in conjunction with each other to ensure that that the proper studies are performed to evaluate the reliability impacts of newly interconnecting Facilities and existing interconnected facilities. In the currently effective standards, these are referred to as changes that “materially modify” the Facility. As part of a broader project assessing the Reliability Standards for improvements to address the growth of inverter-based resources on the Bulk Power System, the NERC Inverter-Based Resource Performance Task Force recommended that this “materially modify” language be revised to provide needed clarity for applicable entities regarding the types of changes that must be addressed in the interconnection studies.

NERC notes that the term “materially modify” should be used to distinguish between Facility changes that are required to be studied and those that are not required to be studied. The lack of responsibility for any one entity to define what constitutes a “materially modifying” change  has led to this confusion and could lead to reliability risks if changes that affect the electrical performance of an inverter-based resource are not studied in detail. For example, NERC states in its petition that a planning entity may consider a change to an inverter-based resource’s control system software to be a “materially modifying” change requiring study, but the owner of that inverter-based resource may not make the same determination and therefore would not provide any notification it is making the change. The control system change would therefore go unstudied, and its potential reliability impacts unassessed. As another example, NERC noted the potential for confusion regarding the circumstances under which a re-power of a wind plant would need to be studied.

NERC’s reporting on system disturbances related to Inverter-Based Resources control issues (e.g., post trip performance of inverter-based resources after system disturbances in California and Texas) has informed the industry of the need for this change.

Newly Approved Standard Modifications

To address these issues, NERC  proposes to revise the FAC-001-4 and FAC-002-4 Reliability Standards to: (i) clarify which entity is responsible for determining which Facility changes are “materially modifying,” and therefore require study under the standards; (ii) clarify that a Generator Owner should notify the affected entities before making a change that is considered “materially modifying”; and (iii) revise the term “materially modifying” so as not to cause confusion between the FAC standards and the FERC interconnection process orders, which use similar terminology.

Generators under the proposed standard FAC-002-4 (R6) would be subject to the Planning Coordinators’ publicly posted definition of what constitutes a qualified change for the purposes of Facility interconnection study or re-study. The proposal leaves the precise definition of what constitutes a qualified change up to the Planning Coordinator.

NERC believes that the proposed Reliability Standards, if approved by the FERC, will advance the reliability of the Bulk Power System by helping to ensure that changes to existing interconnected facilities that can have reliability impacts, are properly addressed in interconnection requirements and studies.

NERC Compliance Carry Over Effects

There are significant implications for the NERC compliance programs of registered entities relating to their respective roles in the new Facility interconnection review process as Generator Owners, Transmission Owners, and Planning Coordinators. A review of those processes in anticipation of FERC approval of the FAC-001-4 and FAC-002-4 standards is necessary to stay ahead of the regulatory change curve.

Next Steps

Utilities should carefully review the most recent NERC Petition to FERC and the revised standards in light of their respective roles in the interconnection process. The standards’ changes will have a 12-month implementation period after FERC approval.

With expertise in all areas of power system planning and power delivery, along with protection and control system engineering, TRC can provide independent technical advice and project management services to review your company’s affected compliance related documents, make recommendations for compliance process changes and assist in preparation or perform the system studies required.

Utilities should carefully review the most recent FERC Order and their current facilities rating compliance process documents. Companies should be prepared to modify their facilities ratings methods and other affected NERC compliance processes program documents as necessary to maintain compliance.

With expertise in all areas of power system planning and power delivery, along with protection system engineering, TRC can provide independent technical advice and project management services to review your company’s affected compliance related documents.


Your Trusted Regulatory Advisor

TRC closely follows the national and state regulatory trends in all regions of North America. Our approach to power system engineering, planning, design,  construction and commissioning testing balances solutions that incorporate appropriate industry trends, mandatory standard requirements, regulatory guidance, compliance obligations, best practices, operational goals and budgets. With expertise in both power system planning and operations, TRC supports public utilities and private energy providers in their effort to stay ahead of the curve and to meet regulatory requirements as they evolve.

This regulatory update is provided as a service to TRC’s utility clients, helping to  keep you informed of forward-looking issues that will impact your company’s electric system reliability risks along with related topics regarding 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

Jim Whitaker, PE

Jim Whitaker, PE is Supervisor of Power Systems Studies at TRC. He has over 30 years of experience in Transmission and Distribution Planning, and Substation, Transmission and Distribution Engineering. His Transmission Planning projects include coordinating joint/regional 10-year transmission plans, generator interconnections, regional system assessments, as well as NERC compliance studies. His projects have included studies for both Utilities and Project Developers across the United States in the Eastern and Western Interconnection transmission systems as well as ERCOT. Prior to joining TRC, Jim worked for Xcel Energy, Peak Power Engineering, Tucson Electric Power and Virginia Power. Contact Jim at

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