Power fluctuation alleviation using cascade STATCOMs with energy storages for wind farm applications

In this paper, a cascade STATCOM with battery energy storages for wind power applications is presented. Meanwhile, a coordinate control strategy is proposed for this inverter system in order to alleviate both active and reactive power fluctuation in a wind power generation system. The SoC of each battery is directly controlled using PI controller and zero sequence voltage is injected so as to obtain balanced state-of-charge (SoC). A time constant T is involved to identify the power reference from the cascade inverter, this time constant is determined by considering both the SoC of each battery and the required power of the wind farm. A nine-zone plot is presented to simplify the above process for deriving the parameter T. A simulation model based on MATLAB/Simulink is developed to validate the proposed method. At the same time, a 10 kW prototype is implemented and experimental results are given to demonstrate the feasibility of the approach.