Background
For decades, Electromagnetic Transients (EMT) modeling was considered a specialized tool, used primarily for niche applications such as switching studies, lightning surge analysis, or advanced technologies like HVDC links and FACTS devices. The reason was straightforward: EMT simulations are complex, computationally intensive and time-consuming.
But the grid is changing fast.
The rise of inverter-based resources (IBRs) has exposed the limitations of traditional modeling methods. Unlike conventional phasor-domain (RMS) models, EMT simulations capture the lightning-fast control actions, nonlinear behaviors and high-frequency dynamics that govern IBR interactions with the grid. What was once a niche tool has now become indispensable for modern power systems, particularly in regions dominated by IBRs.
Why EMT Modeling Matters Now
Inverter-based resources behave fundamentally differently from traditional synchronous machines. By reducing grid inertia and introducing complex control interactions, IBRs present new challenges for both stability and reliability. Regulators and standards bodies have responded accordingly, elevating EMT modeling from a best practice to a compliance requirement.
Standards such as IEEE 2800-2022 and IEEE 1547-2018 require IBRs to demonstrate capabilities including voltage and frequency ride-through, reactive current support and fast control responses, dynamics that only EMT simulations can accurately capture. The urgency is underscored by NERC Alert Level 3 issued in May 2025. Following several large-scale, unexpected IBR trips that RMS models failed to predict, NERC mandated Generator Owners, Transmission Planners and Planning Coordinators to report by August 18, 2025, on their EMT modeling processes or plans to establish them, underscoring NERC’s trajectory toward eventually requiring EMT models as a standard practice.
The message is clear: without EMT modeling, the risks to grid reliability are simply too high.
The Value of EMT Modeling
The strength of EMT modeling lies in its approach. Unlike phasor-domain tools, which approximate system behavior in the frequency domain, EMT models operate directly in the time domain, capturing instantaneous waveforms, nonlinear device behavior such as IGBTs, diodes and arresters, and fast, complex control dynamics.
In today’s IBR-rich systems, characterized by weaker grids, reduced inertia and nonlinear devices, these details are critical. Verified EMT models not only give grid operators confidence that power plants meet performance standards but also provide a trusted foundation for system-wide studies. EnerNex’s extensive experience demonstrates how detailed EMT modeling can transform planning and operational confidence.
Roles and Responsibilities
Achieving reliable EMT-based verification is a collaborative effort requiring coordination across the entire value chain. Project owners must begin early, engaging experts to develop EMT models based on manufacturer-verified data. Consultants and engineers then integrate these models, perform compliance testing and identify potential limitations, while grid operators and regulators define performance criteria and rely on accurate EMT models for planning and operational decisions.
The consequences of poor modeling are significant. Incomplete or poorly tuned models can mask real issues, creating “false compliance” and a dangerous illusion of security. EnerNex’s experience shows that early preparation, transparency and collaboration among stakeholders are essential to overcome project limitations and establish confidence in system-wide modeling results.
Challenges Along the Way
Building high-quality EMT models is not without its obstacles. Grid codes may impose conflicting requirements, such as demanding both active and reactive current injections under varying conditions, forcing unavoidable trade-offs due to limited inverter capacity. Many manufacturer-provided models are “black boxes” that conceal internal control logic, making it difficult to distinguish genuine system issues from modeling artifacts. Simplifications in some models, such as omitting communication delays, discrete control logic, or signal filtering, can create a misleadingly stable or responsive simulation.
These challenges highlight the importance of expert judgment and thorough validation, both of which EnerNex has applied extensively in project work.
Conclusions
As the energy transition accelerates, inverter-based resources are becoming the backbone of the power grid, making EMT simulations essential rather than optional. Validated EMT models, grounded in real-world performance, provide grid operators with the confidence needed to plan, operate, and secure the power system. Achieving this requires early engagement, meticulous verification and close collaboration among project owners, manufacturers, consultants and regulators.
When executed effectively, EMT modeling does more than check a compliance box. It enables the stable, reliable operation of an increasingly complex and dynamic grid and EnerNex stands ready to support this effort, leveraging its expertise to ensure that EMT modeling delivers actionable insights and lasting value across the entire power system.