Double parameter optimization and mode switch strategy for a hybrid energy storage system

To avoid frequent mode switching and optimize the system control parameters for multi-mode hybrid energy storage system (HESS), a mode switch strategy with double parameter optimization (DPO) is proposed. Combining the state of charge (SOC) of ultra-capacitor (UC), power demand and the component efficiency, the DPO is integrated with the hysteresis control based on the real-time average power. The frequent mode switching can be effectively avoided and the system stability of the multi-mode HESS can be improved via the hysteresis control. To achieve the optimization of the overall system efficiency, the goal function of the simulated annealing optimization is established. The simulations and experiments verify the effectiveness of the DPO switch strategy. A comparison shows that the DPO switch strategy enables to reduce the frequencies of mode switching and of battery power output. The system stability and the battery safety are effectively guaranteed, and the overall system efficiency is improved and the battery life is extended simultaneously. Compared with the rule-based strategy, the overall system efficiency is improved up to 1.8%.