An Optimal Frequency Division Control for Hybrid Energy Storage Considering the Change Rate of the Load

In traditional hybrid storage system, DC bus is used to regulate the high frequency load, super capacitor is used to regulate the medium frequency load, and the battery is used to regulate the low frequency load, but the change rate of the load is not considered in these processes. So in this paper, an optimal frequency division control method of hybrid energy storage is proposed for the first time by considering the change rate of the load. Firstly, the super capacitor and lead-acid battery which can cover the maximum variation of load frequency are selected as the hybrid energy storage components according to the Ragone curves of energy storage elements. And then the control strategy of optimal frequency division of hybrid energy storage is designed, in which the piecewise function based first power allocation and the frequency division control based second power allocation are applied to improve the accuracy of hybrid energy storage system for responding to load. Finally, the model is applied in residential area microgrid to avoid the peak load through simulation. The simulation results conform with the theoretical analysis, which verifies the correctness of the control strategy.