Optimized Operation Method of Vanadium Redox Flow Batteries Based on Microgrid Load Response

The vanadium redox flow battery (VRB) is considered to be one of the most promising technologies for large-scale energy storage, as well as an effective method to solve the problems of peak regulation and frequency modulation of power grid and promote the consumption of intermittent renewable energy. In this study, the electrochemical model of the VRB system is formulated using MATLAB based on self-discharge effect to investigate the effect of the charge/discharge process and electrolyte flow rate on the battery performance of the VRB system. Furthermore, an optimized scheduling model for the load in a microgrid is formulated. An optimal electrolyte flow calculation model for real-time response to the demand side load fluctuations in a microgrid is also constructed, and an optimized operation method of the VRB system is proposed. Simulation results show that the overpotential loss of vanadium battery correlates positively with the current. When the electrolyte flow rate of the VRB system increased from 0.024 m³/h to 0.288 m³/h, the pump power consumed by the battery increased from 0.027 W to 0.422 W, resulting in an increase in the energy efficiency. Higher system efficiencies can be obtained under constant loads by selecting the appropriate electrolyte flow rate of the VRB system. The proposed optimized operation method of the VRB system can be employed to realize real-time optimal control of battery electrolyte flow in a microgrid under variable load conditions. Unlike the constant flow operation method, the system efficiency of the battery can be increased to 87.03% using the optimized operation method.