Optimization of a Vanadium Redox Flow Battery with Hydrogen generation

Abstract: We consider the modelling and optimal control of energy storage systems, in this study a Vanadium Redox Flow Battery. Such a battery can be introduced in the electrical grid to be charged when demand is low and discharged when demand is high, increasing the overall efficiency of the network while reducing costs and emission of greenhouse gases. The model of the battery proposed in this study is less complex than the majority of models on batteries and energy storage systems found in literature, but still accurate enough to capture the core aspects of the behaviour of the battery. Estimation methods are discussed for determining unknown parameters in the model using experimental data and the model is evaluated against additional measurements of the physical system showing good fit. The purpose of having a simple model is that the resulting optimal control problem is easier to solve. Operation of the battery with respect to several different objectives are discussed and that of minimizing the vertical net load and maximizing profit are solved for open loop control and receding horizon control over the time span of one day. Two performance metrics are proposed for determining the gain of operating an electrical network with or without the battery. The results show that the introduction of storage systems indeed helps in increasing profit and reducing emissions.