WECC-0160: WECC EMT Modeling and Screening Criteria

In Q4 2025, WECC convened Transmission Planners (TPs) and Planning Coordinators (PCs) from across the Western Interconnection at its WECC EMT Strategic Workshop. The primary issue identified through the WECC EMT Strategic Workshop is the absence of consistent, regionally harmonized criteria governing IBR modeling (model specifications, model quality, and model performance testing, model benchmarking) and electromagnetic transient (EMT) screening methods. NERC standards are prescribing the “what” – TPs and PCs need to establish IBR modeling requirements and screening methods for the necessity of EMT studies. However, the details associated with how to implement these requirements are left to individual entities.

This SAR/Project was developed as an outcome of the 2025 WECC EMT Strategic Workshop. The 2025 WECC EMT Strategic Workshop was attended by 77 people spanning NERC, WECC, ESIG, Transmission Planners, Planning Coordinators, equipment manufacturers, national laboratories, generator developers, and other industry subject matter experts. The attendance also included a few attendees from across North America. The workshop strongly highlighted that there is a window of opportunity and thus a sense of urgency from TP and PC technical teams to move this effort forward. With the impending NERC Reliability Standards under development and expected to be passed within the next year or so, TPs and PCs will be developing and/or enhancing their technical requirements, improving business practices, and training staff on implementing these within their organizations.

Hence, if stakeholders can leverage a regionally aligned Regional Criterion, it presents a tremendous opportunity and benefit for all stakeholders who will be mandatorily pursuing these same efforts across the Region. The level of detail needed within the proposed Regional Criterion far exceeds what would go in a NERC Reliability Standard or WECC Regional Reliability Standard or WECC Regional Variance; thus, a voluntary WECC-driven Regional Criterion fits stakeholder needs effectively and efficiently.