| Wind power generation is new renewable energy power generation technology. Power output of wind power is random, intermittent and not accurately predicted. With the increase of wind power installed capacity, large scales of wind power integration makes serious influence on safety and stability of power system. Energy storage technology is an effective measure smoothing wind power fluctuation. Hybrid energy storage overcomes the limit of simple energy storage. This paper makes battery and super-capacitor as hybrid energy storage system. Capacity configuration and coordinated control strategy of hybrid energy storage system are delved deeper in this paper.Firstly, necessity of using hybrid energy storage is proved by analysis of power fluctuation characteristics of wind power. mathematical model of wind speed, wind generator,double-fed wind power generator, battery and super-capacitor is built. Besides, their working principles are analyzed. Simulation models of battery and super-capacitor are built on MATLAB/SIMULINK and their charging and discharging characteristics are analyzed.Secondly, characteristics of topology structure of centralized and distributed energy storage is analyzed. Power output of wind power is decomposed by wavelet packet. Low frequency component is used as target power of wind power integration, and sub high and highest frequency components are compensated by hybrid energy storage system. So capacity configuration of hybrid energy storage can be calculated. Simulation model of wind power hybrid energy storage system is built on MATLAB/SIMULINK. According to smooth degree of power output of PCC and wave range of SOC of energy storage device, hybrid energy storage system is verified effectively smoothing wind power fluctuation by such capacity configuration. Simulation models of centralized and distributed energy storage are built on MATLAB/SIMULINK. According to power output of PCC and wave range of voltage of DC bus when sudden load, centralized energy storage is concluded having better performance of power smoothing, and distributed energy storage having better stability of voltage of DC bus.Lastly, inverter of hybrid energy storage system uses second power amendment control strategy. Fuzzy controller is used to amend power once, compensation value of battery and super-capacitor is used to amend power twice. Second power amendment control strategy cannot only smooth wind power fluctuation, but also improve SOC of hybrid energy storage device and increase their working life. |
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