Modeling and Measurement of Load Rejection Overvoltage of Inverter-Based Resources Interconnected to Distribution Feeders

Inverter-based renewable generation resources are proliferating as a response to environmental policy. Along with these variable forms of generation comes the application of battery energy storage systems that are necessary to level off generation as well as provide system support that in many jurisdictions can include ramp rate regulation. They can also enable high levels of renewable penetration by contributing to system inertia, ancillary services near critical facilities, reducing transmission security violations, and orderly islanding, with the objective of improving system resilience. It is well known that the costs of renewable generation and energy storage have been following a descending trend which has led to a gradually higher adoption level. These inverter-based resources, however, create new problems for electrical utilities planners and engineers. One such issue, which has been studied recently, is how to measure, test, and manage load rejection overvoltage. This phenomenon takes place upon sudden islanding of a power system area such that it becomes supported by grid-following inverter-based resources only. This paper presents background, practical methods to test the behavior, as well as two case studies of utility-scale generation and energy storage connected to a distribution feeder.