MOD-026-2

R1 · Set dynamic model requirements (Transmission Planner and Planning Coordinator)

What it means. Each Transmission Planner and its Planning Coordinator jointly develop the dynamic model requirements used to evaluate submitted models and documentation of Model Verification and Model Validation, and the Transmission Planner makes them available to Generator Owners and Transmission Owners. At a minimum they cover positive sequence model requirements for the models and functions in Attachment 1, including which limiting and protective functions must be represented; for inverter-based resources, FACTS devices and HVDC, which legacy facilities need EMT models under R3 (with a statement of need) and the acceptable EMT models, format and level of detail; and any additional requirements the Transmission Planner uses to judge acceptability, or a statement that none apply. A legacy facility is any facility with a commercial operation date before the effective date of MOD-026-2.

Evidence an auditor expects. Dated documents, webpages or web portals setting out the jointly developed requirements, and evidence that the Transmission Planner made them available to Generator Owners and Transmission Owners.

R2 · Provide verified and validated positive sequence models

What it means. Each Generator Owner or Transmission Owner provides its Transmission Planner, on the Attachment 2 schedule, positive sequence dynamic models with parameters representing the in-service equipment, including at a minimum each applicable model and function in Attachment 1 per the R1 requirements. With the models go documentation of Model Verification showing that the configurable, site-specific parameters represent the design and settings of the in-service equipment (with a written statement identifying any parameters that cannot be verified and why), and documentation of Model Validation comparing model behavior to measured behavior in a staged test or system disturbance for a voltage or reactive power excursion and for a frequency or active power excursion. A frequency excursion qualifies only if the facility is in a frequency responsive mode and the nadir deviation from scheduled frequency is at least 0.04 Hz in the Eastern Interconnection, 0.08 Hz in the ERCOT and Western Interconnections, or 0.30 Hz in the Quebec Interconnection. Where a frequency excursion from a system disturbance is the chosen validation method and the facility has installed and operating recording equipment but sees no qualifying excursion by its due date, a written statement meets the frequency part, and the validation follows within 365 calendar days after a qualifying excursion is recorded.

Evidence an auditor expects. Dated evidence for each applicable facility, such as an email, postal receipt or web portal upload, that the positive sequence models and accompanying documentation were provided to the Transmission Planner.

R3 · Provide EMT models for IBRs, FACTS devices and HVDC

What it means. For FACTS devices, HVDC systems, BES IBRs and non-BES IBRs, the Generator Owner or Transmission Owner also provides EMT models on the Attachment 2 schedule. Excluded are legacy facilities whose original equipment manufacturer no longer supports EMT models for the facility, and legacy facilities the Transmission Planner did not identify under R1 Part 1.2.1. The facility EMT model represents the applicable HVDC system, FACTS device or IBR units, collector system, auxiliary control devices that act on voltage or frequency, power plant controller, generator step-up and main power transformers, and includes enabled protective functions that directly trip the IBR units or facility and limiting functions that limit their active or reactive output. The submittal includes Model Verification and Model Validation documentation as in R2; for IBR facilities, test results comparing the IBR unit response with the IBR unit EMT model response for large signal disturbances, or the documented reason they are not obtainable; and a comparison of the positive sequence model response with the EMT model response for large signal disturbances as defined by the Transmission Planner.

Evidence an auditor expects. Dated evidence for each applicable facility, such as an email, postal receipt or web portal upload, that the EMT models and accompanying documentation were provided to the Transmission Planner.

R4 · Update models after a change

What it means. Within 180 calendar days after a hardware, software, firmware, control mode or setting change to an applicable unit or facility that alters its dynamic response, the Generator Owner or Transmission Owner gives its Transmission Planner updated models and documentation per R2 Parts 2.1 to 2.3 and, if applicable, R3 Parts 3.1 to 3.5, or on a revised timeline agreed with the Transmission Planner. Automatic setting changes caused by a change in operating mode are excluded. A transmittal resets the 10-year date only if all models and parameters are verified and included.

Evidence an auditor expects. Dated evidence, such as an email or postal receipt, that updated models and documentation were provided for each change that altered the dynamic response.

R5 · Review submitted models (Transmission Planner)

What it means. Within 120 calendar days after receiving models and documentation, or on a mutually agreed timeline, the Transmission Planner evaluates them against the R1 requirements and either notifies the owner that they are acceptable (and notifies, or sends the accepted models to, its Planning Coordinator) or notifies the owner that they are not acceptable, with an explanation and supporting evidence. For facilities commissioned before April 1, 2026 that were not applicable under MOD-026-1 or MOD-027-1, the implementation plan gives the Transmission Planner 365 days to review.

Evidence an auditor expects. Dated evidence of receipt, review and the written response, such as the date received, review date and a dated email or postal receipt.

R6 · Respond to an unacceptable model or a review request

What it means. The Generator Owner or Transmission Owner responds to its Transmission Planner within 120 calendar days after a notice of unacceptability under R5, or within 180 calendar days after a Transmission Planner request to review a model for identified deficiencies (or on an agreed revised timeline for such a request). The response is either updated models and documentation per R2 and, if applicable, R3, or a technical justification with supporting evidence for keeping the current models.

Evidence an auditor expects. Dated evidence, such as an email or postal receipt, that the response was provided.

R7 · Provide current models on request (Transmission Planner)

What it means. Within 90 calendar days of a written request from the Generator Owner or Transmission Owner that owns an existing facility, the Transmission Planner provides the current (in-use) models and accompanying documentation for that facility.

Evidence an auditor expects. Dated evidence, such as an email or postal receipt, that the current models and documentation were provided.

For inverter-based plants

BES IBRs and non-BES IBRs that have or contribute to 20 MVA or more delivered at 60 kV or above owe both a positive sequence model and an EMT model with enabled protective and limiting functions, an IBR unit test comparison against the EMT model (or the documented reason test results are not obtainable), and a positive sequence versus EMT comparison, unless excluded as a legacy facility under R3.