This study presents an observer-based methodology to estimate, in real-time, the state of charge of a Vanadium redox flow battery. Different from the available results in the literature, this work presents a new estimator that distinguishes between the concentration in the tank and cell parts of the system. Moreover, it presents an estimation of the state of charge that can deal with both balanced and unbalanced situations. The model used for the observer design is a nonlinear electrochemical model. A nonlinear observer is proposed, designed and validated through simulation and in an experimental prototype.


mathematical programming, observability, storage automation.

Author keywords

Redox flow battery, State of Charge, nonlinear observer

Scientific reference

A. Clemente, A. Cecilia and R. Costa. Online state of charge estimation for a vanadium redox flow battery with unequal flow rates. Journal of Energy Storage, 2023, to appear.