Modeling and control for large capacity battery energy storage system

Energy storage as an alternative solution for integrating renewable energy into grid has been studied recently. Vanadium Redox Battery (VRB) has been received much attention for its excellent characteristics, especially for large capacity energy storage. This paper focuses on the structure, modeling and control of VRB energy storage system. To cooperate with large scale wind farm /PV station, the structure for large capacity battery energy storage system (BESS), including configuration site, battery system and power condition system (PCS), is discussed. The equivalent circuit model of VRB, concerning of electrical, physical and chemical factors, is established, and also the PCS. The PQ decoupled scheme is adopted to control active power and reactive power independently, and the zero-sequence circulating current control scheme is employed for parallel converters. To coordinate the operation of battery system with PCS, the battery-based restriction control and multiple operation modes are proposed. The simulation results with MATLAB/Simulink are presented to verify the model and control schemes.