A modular control architecture for safe and efficient operation of vanadium flow batteries under dynamic current profiles

Vanadium flow batteries operating under rapidly varying power demands require coordinated management of reactant supply and electrochemical safety. To address this need, this paper presents a modular hierarchical control architecture with an explicit priority structure: safety is prioritized over current compliance, and current compliance over efficient reactant supply. The first module regulates stack conversion by dynamically adjusting the electrolyte flow rate, extending classical flow-factor operation beyond quasi-steady conditions. The second module enforces safety through a control barrier function acting as a smooth and minimally invasive current filter, modifying a baseline current request only when required to preserve prescribed concentration or state-of-charge bounds with formal guarantees. By avoiding hard saturation, the safety layer prevents abrupt power curtailment while retaining a lower computational cost than conventional centralized optimization. Comprehensive experimental tests under steady and highly dynamic operating conditions demonstrate stable conversion regulation, substantially smoother flow-rate commands, and strict compliance with the prescribed safety constraints.