Faults affect a conventional power system differently than they do modern systems with many inverter-based resources, or IBRs, such as solar and wind energy. (Image: Philip Gray/ORNL, U.S. Dept. of Energy)

Researchers at the Department of Energy’s Oak Ridge National Laboratory are leading the way in understanding the effects of electrical faults in the modern U.S. power grid.

Faults are abnormal conditions that interrupt the flow of power, with the potential to cause blackouts that affect thousands of customers. They can be caused by equipment failure, human error, weather events, or natural disasters. Understanding them enables electric companies and system operators to maintain reliable electricity service and reduce the number of outages.

However, traditional modeling methods are less effective at predicting how cutting-edge digital technology will behave. Green resources like solar panels and electric vehicle chargers are spreading through the electric grid, increasing the presence of electronic inverters, which alter the flow of electrical current to match the larger transmission system. Compared to mechanical systems, these power electronics are much faster-acting and are affected differently by faults in distant parts of the grid. But most power companies have not adjusted their planning to reflect these changes.

That’s why the North American Electric Reliability Corporation (NERC) an international regulatory authority responsible for grid reliability, is asking utilities and operators to use a new method to probe the causes and effects of faults: electromagnetic transient, or EMT, domain analysis. Compared with traditional modeling, this type of analysis is expected to portray rapidly unfolding events more accurately. The power industry is exploring new fast approaches to meet these requirements by also exploiting newer high-speed computers.

“As the grid transformation happens with more inverter-based resources and EV chargers, EMT is needed to understand the reliability of the system,” said ORNL researcher Suman Debnath. Lacking these methods and tools, operators and utilities may not be able to retain their past level of service reliability, especially as they plan future interconnections and expansions of the transmission system.

Debnath’s team of ORNL researchers, working with partner Southern California Edison, conducted one of the first successful fault replications using EMT earlier this year after integrating their own models and algorithms into an EMT domain analysis tool. Running the simulation in the ORNL lab and in hardware at Southern California Edison, they accurately reproduced the effects of a 2018 California fault on a large solar plant.

“Developing a high-fidelity model will help utilities better understand the physical dynamics of the power electronics, thus improving grid performance and aligning with our future vision of grid modernization,” said Md Arifujjaman, senior engineer for grid technology innovation at Southern California Edison. “This kind of project helps us a lot. The more dynamics you can present, the better for us, for the grid, and for the customer.”