Electromagnetic Transient Modeling Update

Electromagnetic transient (EMT) modeling simulates fast, short-duration electrical events—switching operations, lightning strikes, inverter interactions—that standard steady-state and dynamics analysis cannot capture. EMT studies are crucial for grids like ours with high penetration of inverter-based resources (solar, wind, battery storage), where conventional planning tools cannot identify some interactions like those that occurred in California, Utah, and Texas IBR events. These EMT studies validate fault-ride-through, harmonic interactions, and control-response under disturbances; assess breaker transient recovery voltage and very-fast transients in gas-insulated switchgear; and support protection coordination and anti-islanding strategies. The Texas Interconnection is also experiencing power system disturbances involving large loads, whose extensive power electronics and control schemes have characteristics that require similar modeling.

The North American Electric Reliability Corporation (NERC) Inverter-Based Resource Performance Subcommittee (IRPS) developed a Reliability Guideline: Recommended Practices for Performing EMT System Studies for Inverter-Based Resources to describe the industry’s changing needs for interconnection and operational studies. IRPS, in turn, spun off the stakeholder Electromagnetic Transient Modeling Task Force (EMTTF) to focus on industry adoption of EMT modeling and simulation through guidance and technical reference materials. Their first two draft whitepapers were the culmination of lengthy efforts; approved by NERC’s Reliability and Security Technical Committee (RSTC) on June 10, 2025, they will be posted publicly in the near future:   

• Case Study on Adoption of EMT Modeling and Studies in Interconnection and Planning Studies for BPS–connected IBRs
• EMT Analysis in Operations Planning for BPS-Connected IBRs

In addition to these technical papers on EMT practices, NERC and Oak Ridge National Laboratory (ORNL) are holding their 2025 Electromagnetic Transient Simulation Workshop from October 7-9, 2025, in Knoxville, Tennessee. Texas RE will also host training by the Energy Systems Integration Group (ESIG) at our offices December 16-18.  

Revisions to Reliability Standards involving EMT are also underway in Project 2022-04, based on a Standards Authorization Request (SAR) accepted on July 19, 2023. This project will update FAC-001, FAC-002, MOD-032, and TPL-001 to ensure that planners have models and tools necessary to adequately conduct reliability assessments under increasing IBR levels. This requires the collection of EMT models by applicable entities, Transmission Planners (TPs), and Planning Coordinators (PCs) to conduct EMT studies where needed. This project is developing just behind Federal Energy Regulatory Commission (FERC) Order 901 Milestone 3 projects, since it relates directly to their modeling content (but it is not considered a Milestone 3 project). Posting of draft revisions for the two FAC Standards is planned for October.