An Optimal Operational Strategy for Vanadium Redox Flow Battery Based on Particle Swarm Optimization

Vanadium redox flow battery (VRB) is a promising technology for storing energy in smart grid applications and the establishment of the battery systems are growing rapidly worldwide. Operational characteristics of VRB is affected by multi variables such as electrolyte temperature, flow rate, and charge/discharge current. Existing problems like premature voltage cut-off and high concentration overpotential are mainly caused by inappropriate settings of electrolyte flow rate, charge/discharge current and temperature, eventually reducing battery energy efficiency. Previous optimization strategies usually focus on single variable and few articles discussed about the coupled effects among multi variables. In this paper, an optimal strategy using particle swarm optimization method is proposed to improve the overall energy efficiency and available capacity. Based on an electrochemical model, the experiment is conducted with a 5kW/3kWh VRB in the lab of Wuhan University of Technology. The results show that the instantaneous energy efficiency reaches up to 93.65% as the SOCs increases whereas the applied current decreases. The optimal flow rate increases drastically with regard to the flow factor. Among three variables, instantaneous energy efficiency is much more sensitive to the applied current.