Output feedback control of electrolyte flow rate for Vanadium Redox Flow Batteries

In this paper, we propose a new strategy for electrolyte flow rate control in Vanadium Redox Flow Batteries. The keystone of our approach is a novel methodology for determination of optimal reference voltage and robust feedback controller design that provides the desired transient and steady state battery performance. In addition, we introduce a hierarchical scheme of the general battery control system that significantly simplifies classification of battery control tasks and gives guidelines for multistage controller design. The research considers a kilo-watt class VRFB system operating in a wide range of loading currents (20–180 A). The proposed control algorithm allows reference trajectory tracking with high accuracy (average error less than 0.0005%), yet providing the required battery performance at twice lower flow rates as compared to the existing solutions, and thus, decreasing pump energy consumption by a factor of 3. As a result, the proposed method can be used for flow rate regulation in practical VRFB systems ensuring their stable and efficient operation under dynamic loading conditions. •A new approach for flow rate control in VRFB systems is proposed.•A kilo-watt class VRFB system is considered (5 kW/15 kWh).•A hierarchical classification of tasks related to flow rate regulation is proposed.•The control strategy is based on proportional-and-integral controller.•The designed controller assures stable VRFB operation at dynamic loads.