ERCOT Model Quality Testing (MQT) and PGRR109 Model Reviews: A Guide for IBR Owners

ERCOT's Model Quality Testing (MQT) checks that an IBR's dynamic models reproduce how the plant behaves. Together with the Planning Guide Revision Request 109 (PGRR109) model reviews and Dynamics Working Group (DWG) procedures, it sets the model data and timing expectations IBR owners in ERCOT work to.

Understanding ERCOT's MQT Requirements

ERCOT's DWG Model Quality Testing process checks that every IBR's dynamic model accurately reflects how the plant behaves in real life. To pass MQT, resource owners must demonstrate that their RMS (root-mean-square phasor, PSSE/TSAT) and EMT (electromagnetic transient, PSCAD) models reproduce key control behaviors:

• Voltage and frequency ride-through
• Active and reactive power controls
• PLL, outer-loop, and momentary cessation logic
• Response to benchmark disturbances

ERCOT's published MQT and voltage ride-through (VRT) guidelines define testbench configurations, benchmark event cases, and pass/fail criteria.

The PGRR109 Model Review Gate

ERCOT's Planning Guide Revision Request 109 (PGRR109), effective May 1, 2024, added two dynamic model reviews for IBRs:

1. Pre-commissioning: Interconnecting Entities for IBRs complete a dynamic model review before the Resource Commissioning Date.
2. Post-commissioning: Resource Entities with operational IBRs complete a review before implementing setting or equipment changes, such as protection or control setting updates, that could affect electrical performance and require model updates.

The effect is that models are reviewed again whenever the controls or settings they represent change. Submissions include updated PSSE/TSAT/PSCAD models, complete MQT reports, and supporting plots - all uploaded through ERCOT's Resource Integration and Ongoing Operations (RIOO) platform.

What to Watch

1. Model submission timing. Stability assessments use the models on file, so an incomplete MQT submittal can delay a project's review.

2. Measured response. ERCOT's Performance, Disturbance, Compliance Working Group (PDCWG) reviews frequency control performance in the ERCOT region, so models should match measured frequency and voltage response.

3. Field tuning. Changes to voltage control or reactive limits made on site during commissioning tests, without matching model updates, can cause MQT and VRT failures. Coordination between field engineers and modelers matters.

4. PGRR109 review time. ERCOT's model review takes time, and for operational IBR changes ERCOT may require the Transmission Service Provider (TSP) to run a limited dynamic stability study. These windows have direct commercial implications for projects targeting the commercial operation date (COD) or Nodal Operating Guide Revision Request (NOGRR) 255 compliance milestones.

Common Pain Points for IBR Owners

• Model redundancy: Separate RMS, TSAT user-defined model (UDM), and EMT files must stay aligned throughout the project lifecycle.
• Tight scheduling: Overlapping MQT, VRT, and PGRR109 reviews compress interconnection timelines.
• Post-tuning failures: Field modifications made without model updates can cause MQT and VRT failures and rework.

How GridStrong Supports ERCOT MQT

GridStrong's platform runs the ERCOT MQT workflow and keeps the results with the models they test.

1. Automated MQT Workflows

Run ERCOT's DWG test cases, overlay PSCAD/PSS®E/TSAT plots, and generate the MQT report in one platform.

2. Model Version Control and Validation

GridStrong links your dynamic models directly to field configuration data, so each update is traceable across studies.

3. PGRR109 Review Readiness

Prepares submission packages in ERCOT templates, with overlays and benchmark comparisons.

4. Event Data Integration

Compare modeled performance with recorded events, using the same data that supports NERC PRC-028-1 and PRC-030-1.

Best Practices for Meeting ERCOT's Model Quality Expectations

• Use ERCOT's latest templates and include your MQT report in every RIOO submission.
• Plan for review time, and more if ERCOT requires a TSP stability study.
• Lock field settings after model validation to prevent MQT/VRT inconsistencies.
• Maintain benchmark libraries using real event data for faster comparisons.

Why It Matters

ERCOT uses the models that pass MQT and PGRR109 review in its stability assessments, so model quality affects both study results and project schedules. The same field data that supports model validation also serves NERC PRC-028-1 and PRC-030-1.