Capacity optimization of battery energy storage systems for frequency regulation

The frequency regulation is an essential part of ancillary services in power systems to mitigate the impacts of uncertainty of load and variable energy resources (VERs) on system frequency. The battery energy storage systems (BESSs), typically with fast response rates, are one of the promising technologies to provide the frequency regulation service. However, the BESS along is not capable to restore frequency due to its limited capacity. As such, a hybrid frequency regulation system consisting of BESS and generators is usually more preferred. In this study, we first propose an optimal allocation method for regulation tasks to minimize the overall regulation cost of the hybrid system. We then optimize the regulation capacity of BESS and generators based on the optimal allocation method. The application of the proposed methods is illustrated with real regulation data from PJM. Simulation results indicate that the hybrid regulation system can better reduce frequency deviations at a lower cost.