The configuration optimized design method based on real-time efficiency for the application of vanadium redox flow battery in microgrid

To realize the efficient, economical and stable operation of vanadium redox flow battery (VRB) in a microgrid containing a high proportion of renewable energy, a coupling calculation model is constructed and a configuration optimized design method is proposed in this paper. First, the coupling calculation model involving the fluid mechanics model and electrochemistry model is established to obtain the real-time efficiency of VRB. Second, an economic model of VRB is constructed considering the investment costs, operation costs, economic benefits and renewable energy utilization. Finally, a configuration optimized design method based on typical load and real-time efficiency is further proposed to cope with practical application scenarios. Two different objectives, including the lowest average daily cost and the lowest renewable energy curtailment, are selected in the method. The results are presented as follows. First, the energy efficiency of the battery is increased from 76.90% to 80.45% with the increase of electrolyte flow rate. With the optimal selection of porous electrode porosity, the merit energy efficiency and system efficiency are presented. Better VRB performance can be obtained at the electrolyte flow rate of 120 ml/min and the porous electrode porosity of 0.93. Second, the novel proposed configuration design method can be implied to improve the renewable energy consumption capacity while ensuring system economics. Finally, with the lowest average daily cost as the objective, the optimal configuration of VRB is 891 kW and 7344 kWh, respectively, while the time average efficiency is 79.26%. The total amounts of renewable energy curtailment in one day decreases from 12,380 kWh to 6,281 kWh. At the same time, the power supply quality is significantly improved after accessing various distributed energy sources to the microgrid.