Compound energy storage control of wind power base on wavelet decomposition

A compound energy storage system in which lead acid battery combines with super capacitor is used to balance the fluctuation of wind power in this paper. A wavelet decomposition method is put forward to extract control signal that contains slowly variable low frequency signal and fluctuant high frequency signal. The slowly variable signal is applied to control the charge or discharge of the battery. The fluctuant signal is applied to control the super capacitor to absorb rapidly changing energy. A control way that voltage loop combines with current loop is used to keep the DC bus voltage steady. A simulation study based on MATLAB is presented to verify the correctness of proposed control strategy. Simulation results show that the battery can be charged steadily and discharged reasonably. In addition, the super capacitor can extract rapidly fluctuant wind energy, and the DC bus voltage of wind power system can be keep in steady at different wind speed and loads. Therefore, the proposed com pound energy storage control method can satisfy the energy balance requirement in wind power system.