Shunt-current-aware dynamic simulation of hundreds-kilowatt scale vanadium flow battery modules under constant power operation mode

The scale-up of vanadium flow batteries (VFBs) from single-stack system to multi-stack modules introduces complex electrolyte pipeline networks, where variations in pipeline configuration and length can induce non-uniform shunt currents through ionic conduction in the electrolyte. These shunt currents cause capacity loss and efficiency degradation, limiting the practical application of VFBs in large-scale energy storage systems. In this work, a dynamic model of hundred-kilowatt-level VFB module is developed and coupled with shunt current model, which enables effective time-dependent evaluations of hundred-kilowatts VFB modules under practical constant power charge-discharge operation scenario. Three series–parallel stack configurations of 250 kW and 500 kW modules are systematically investigated. Simulation results indicate that under constant power operation mode the modules with more series-connected stacks exhibit greater current non-uniformity between central and terminal stacks, leading to more pronounced efficiency losses. By contrast, pipeline layouts with longer branch pipelines effectively mitigate shunt-current-induced losses and improve CE and EE at the same power rating. The proposed framework provides guidance for pipeline layout design, stack integration, and optimization of high-power VFB systems in practical applications.