Modeling and Simulation of a Utility-Scale Battery Energy Storage System

This paper presents the modeling and simulation study of a utility-scale MW level Li-ion based battery energy storage system (BESS). A runtime equivalent circuit model, including the terminal voltage variation as a function of the state of charge and current, connected to a bidirectional power conversion system (PCS), was developed based on measurements from an operational utility-scale battery demonstrator. The accelerated response of the battery unit was verified by pulse discharging it from maximum to minimum SOC and its application for grid resiliency was demonstrated through an example droop control frequency response. For the purpose of validating the equivalent BESS model, experimental results retrieved from the LG&E and KU E.W. Brown solar facility, which houses a 1MW/2MWh operational BESS and a 1MVA variable load bank were compared with simulation results from an equivalent model developed in PSCAD/EMTDC software, which is a tool typically employed for transient analysis.