A Multi-physics Model of Vanadium Redox Flow Battery for Grid Control

The traditional VRB models are equivalent electrical circuit models with low precision, which cannot accurately and comprehensively reflect the characteristics of multi-physical field of VRB, and difficult for flow rate and current control. A multi-physical field coupling model for the control-oriented VRB is established in this paper. The model is composed of three sub-models: the equivalent circuit sub-model is used to describe the external characteristics of VRB, considering the effects of flow rate and temperature. The equivalent hydraulic sub-model can describe the mathematical relationship between flow rate and pump power by analyzing the pressure drop in the hydraulic topology of the VRB system. The equivalent thermal model is based on the third-order Cauer thermal network, which can describe the temperature variation of the VRB system during operation. Particle Swarm Optimization (PSO) is used to identify the parameters of the equivalent circuit model. The proposed model can accurately describe the operating characteristics of VRB with low computational complexity and is suitable for real-time control of VRB.