Dynamic modeling and optimal control of switching modes in reversible solid oxide cells for integrated electric-hydrogen energy system

Reversible solid oxide cells (RSOC) are expected to play an important role in the sustainable energy system. RSOC can be switched flexibly in different operating modes when it is integrated with the power grid. However, it has been observed that significant overshoots of the current density occur during its dynamic processes. The dynamic response will damage the life and reliability of RSOC. In spite of the fact that the mechanisms of the current response have been studied, it remains unclear how overshoot evolution will occur under complex conditions, and few research has been conducted regarding suppression methods. Herein, the overshoot numerical relationships in various dynamic processes are analyzed, and the feasibility and effect of optimization methods for different dynamic behavior optimization methods in switching mode processes are discussed. It indicates that prolonging the switching time by a considerable amount reduces transient overshoot by approximately 99.5 %, though it inevitably slows down the process of reaching the steady state. A bidirectional adaptive fuzzy logic controller is proposed to achieve robust control in multiple scenarios of switching modes, which results in better overshoot suppression and faster steady-state than the direct adjustment of voltage steps. In addition, regulating the gas stream can improve the overall reactant distribution, thereby accelerating the rebalancing process. This method suppresses current overshoot by more than 99 %, and also effectively mitigates power fluctuation, therefore enhancing the long-term working stability of RSOC.