Optimization of Vanadium Redox Flow Battery Performance for Solar PV Integrated Electric Vehicle Charging Station

This paper demonstrates the performance optimization of a kW scale VRFB storage system in a solarpowered EV charging station. Particle Swarm Optimization (PSO) has been used. Here, both VRFB system power loss (including stack and pumps) and stack temperature have been optimized simultaneously. The electrolyte flow rate has been considered as the control variable in optimizing the overall VRFB system power loss and battery temperature, as the electrolyte acts as a charge carrier and heat carrier at the same time. The validation of the proposed work has been done by charge-discharge experiments on a 1kW 6kWh VRFB with different electrolyte flow rates and different levels of stack current, considering certain EV penetration profiles and the availability of solar power for an EV charging station. It is observed from the results that the overall VRFB system power loss becomes the minimum at an optimal flow rate of 6 L/min over a range of 1-18 L/min electrolyte flow rate at 40A, 45A, and 50A, and VRFB stack temperature also lies within the safe limit of 35°C. The proposed work formulation demonstrated in this paper is a generalized one and can also be very useful for large-scale solar PV-VRFB integrated power system applications.