Frequency and Voltage Ride-through Requirements for Inverter-based Resources

The California ISO (ISO) has updated the Inverter-Based Resource (IBR) Model Validation Procedure and the Inverter-Based Interconnection Requests (IBR) Dynamic Model Review Guideline posted on Transmission planning webpage. The updates accommodate new WECC approved models, retirement of repc_b model, and PRC-029-1 compliance. The ISO is also providing process information for submitting facility setting and model changes associated with the implementation regarding compliance with the North American Electric Reliability Corporation (NERC) Reliability Standard PRC-029-1, Frequency and Voltage Ride-through Requirements for Inverter-Based Resources.

The purpose of PRC-029-1 is to ensure that inverter-based resources remain connected and support the Bulk Power System (BPS) during and following defined frequency and voltage excursions. The NERC Reliability Standard PRC-029-1 becomes effective on Oct. 1, 2026. The standard and associated requirements are available on the NERC website. Each applicable entity is responsible for evaluating its facility and determining whether changes are necessary to comply with PRC-029-1. 

Generating Facility Modification Requirements

For existing Generating Facilities, changes limited to frequency or voltage ride-through settings, or associated model parameters that do not constitute a material modification should be submitted through the Data Submission Process described below. 

If implementation of PRC-029-1 requires equipment changes or other changes that constitute a material modification defined in Section 6 of the Generator Management Business Practice Manual, changes must be submitted to the ISO’s Queue Management through a written request. Requests must include the completed Modification Request Form and applicable deposit, which is available on the Queue management page.

Data Submission Process

For existing Generating Facilities, PRC-029-1 related setting and model updates that do not constitute a material modification should be validated using the IBR Model Validation Procedure and sent to the CAISO Grid Modeling Data team at GridModelingData@caiso.com.

Submissions must also include the applicable Participating Transmission Owner (PTO):

• Pacific Gas & Electric Company: GenModel@pge.com
• Southern California Edison Company: basecase@sce.com
• San Diego Gas & Electric Company: basecase@semprautilities.com
• Valley Electric Association, Inc.: veaengineering@vea.coop
• GridLiance West Transmission Company: GLW-planning@gridliance.com

Email Subject Line Convention

Please use the following naming convention for all submissions:

<Resource ID>_<Generating unit name>_<PRC-029-1 submission> 

Please contact ISO Generator Model Data Administrators at GridModelingData@caiso.com with any questions.