Upcoming Changes to MOD-026 and MOD-027

Modeling for inverter-based resources (IBRs) at the generator level continues to be an area of focus for the North American Electric Reliability Corporation (NERC) and Texas RE. MOD-026-1 and MOD-027-1 are included in the 2026 Compliance Monitoring and Enforcement Program (CMEP) Implementation Plan (IP) due to the ongoing risk posed by IBR models not matching real system behavior. These Standards seek to verify that Facility models accurately represent the systems controlling plant voltage, reactive power, and frequency response. To facilitate this, Generator Owners (GOs) must submit model verification to their Transmission Planners (TPs), and TPs must respond within 90 days communicating the usability of the models. Effective communication between entities is vital for ensuring the accuracy of these models.

The ERCOT Planning Guide and Dynamics Working Group Manual require GOs to provide Facility models to ERCOT. However, the procedures do not emphasize required communications between GOs and their TPs. Entities must understand and account for differences between NERC and ERCOT obligations.

Another compliance risk, particularly for smaller GOs, is overreliance on third-party modeling and compliance vendors. GOs should ensure modeling is completed well before submission deadlines to confirm documentation of verification.

Texas RE recommends the following additional internal controls for model verification, TP review, and associated deadlines:

• Implement dated checklists and peer review processes
• Request recipients confirm receipt and acknowledge deadlines
• Designate subject matter experts (SMEs) prior to engagement notice
• Ensure process documents are “live” (regularly reviewed, with dates and signatures)
• Incorporate MOD-026 and MOD-027 deadlines into existing compliance tools

Entities should look to MOD-026-2 when preparing for engagements with MOD Standards in scope. The new version will replace MOD-026-1 and MOD-027-1 by dealing with dynamic models more broadly. MOD-026-2 strengthens modeling requirements and expands the scope of applicable equipment and facilities. Notably, TPs and ERCOT will be required to jointly develop modeling requirements, and Transmission Owners (TOs) may submit generator models in place of GOs. For information on phased-in compliance dates, refer to the Implementation Plan.