The power grid is evolving, and so are the requirements for connecting new resources. EMT simulations are becoming a key tool for analyzing fast-changing grid dynamics, especially as inverter-based resources (IBRs) like solar, wind, and battery storage grow.
What are EMT studies? How do they differ from the traditional steady state studies? Why are policymakers and RTOs beginning to require them of generators and developers? Read on to find the answers.
EMT-based studies
Traditionally, RTOs have conducted steady state-based studies to analyze load flow and short circuit scenarios within an electrical network. RMS simulations include frequency domain analysis, using phasor calculations for voltages and currents, and offer a simplified method for analyzing electrical systems. These simulations assume that the power system operates in a quasi-steady state and is free from rapid transients. The simplification of complex calculations makes it easier to conduct steady state simulations for large-scale power system networks.
EMT studies, on the other hand, are more detailed and offer a comprehensive approach to evaluating transient overvoltages. EMT simulation is the process of modeling and analyzing rapid, short-duration events in electrical power systems, known as electromagnetic transients. Often triggered by factors such as the switching operations of inverter-based resources (IBRs) or the energization and de-energization of electrical equipment, these transients can significantly impact the performance and reliability of power systems. Such transients can cause overvoltage or overcurrent, potentially damaging equipment, disrupting system operations, or compromising system stability.
Using simulation tools like PSCAD to solve differential equations of the power system in very short time intervals, these studies capture the complex behavior of the system and account for phenomena like wave propagation, reflections, and electromagnetic interference.
Why EMT studies are becoming the standard
The electrical network was historically characterized by large generating capacity such as coal, gas, and nuclear power plants. The amount of inverter-based resources (IBRs) was relatively low. Steady state-based studies, therefore, were fit for purpose for these networks.
Today, this landscape is changing. Smaller and distributed IBRs make up the majority of new additions to electrical networks. What’s more, these resources – say, wind turbines, solar plants, and battery energy storage systems (BESS) – all interact with one another, the existing large generators, and with the grid in complex and fast-changing ways.
To accurately analyze inverter behavior and interactions with conventional systems, EMT simulations are becoming the norm for generators and developers, and are being adopted as requirements by policymakers and RTOs.
The U.S. Department of Energy’s Transmission Interconnection Roadmap, for example, recommends requiring validated EMT models for all IBRs during the interconnection process and suggests developing screening criteria to determine when EMT studies are necessary within a region as part of a proactive approach to grid planning and reliability.
The North American Electric Reliability Corporation (NERC), for its part, has initiated Project 2022-04 EMT Modeling, emphasizing the necessity for Transmission Planners (TPs) and Planning Coordinators (PCs) to collect EMT models and conduct studies where appropriate. NERC also held a working group in 2023 to support and accelerate industry adoption of EMT simulation and to determine the required standards for EMT models.
PJM may also require generators and developers to perform EMT studies in some cases. This requirement would first involve PJM to conduct its own traditional steady state-based analysis by splitting its network into clusters of projects. If the study results reveal that there is not enough stability in the network, PJM would require generators to conduct a more detailed EMT-based analysis.
California Independent System Operator (CAISO) also requires detailed EMT models for inverter-based generators, including solar PV and BESS. These models must encompass full inner control loops, plant-level controllers, and accurately represent installed protections for both balanced and unbalanced fault conditions.
All of this is to say that EMT studies are becoming the industry standard for generators and project developers and will be increasingly required by regulators and RTOs for IBR interconnection.
PSC advantage
For power generators, and developers, EMT simulations offer a superior tool for understanding complex, fast-changing grid behaviors, especially with the increasing integration of IBRs. They enable more accurate and reliable system planning, operations, and interconnection compliance compared to traditional RMS-based studies. While RMS studies remain useful for analyzing broader, steady-state, or slower dynamics, the future of power system analysis in the energy transition lies increasingly with EMT simulations.
PSC Consulting has a strong heritage and track record of providing high-quality and timely EMT simulations. With a global footprint, PSC has performed EMT analyses in a number of markets, most notably Australia, where generators and developers have long been required to perform EMT studies in order to connect to the electrical network.
Please find out more about our Power Networks capabilities and contact us to talk about first steps.