| Use of renewable energy is an important means to solve21st century global energycrisis and environmental issues. Due to historic, mature technology, the large-scaleutilization, wind energy has attracted people’s expectations in the field of renewable energy.But wind has characteristics of randomness and volatility, when the capacity of windpower more than a certain percentage of power system, the impact of the wind farm outputpower fluctuations on the grid is increasingly apparent. Energy storage system caneffectively stabilize the fluctuations of wind power output, improve the safety factor ofgrid operation, the power control of energy storage system become a hot research in recentyears.Firstly, the structure of wind and storage systems are studied, using centralizedconfiguration storage systems in the exports of wind farm approach to stabilize powerfluctuations; PCS structure of the energy storage system base on the characteristics ofstorage system itself, PCS topology only has DC/AC; circuit filter is LCL filter,attenuation characteristics of LCL filter in high frequency is fasted, it can stabilize highharmonics, effectively reduce the value of the inductor. Through the study of entire windfarm system structure, MATLAB/SIMULINK simulation model of wind farm and storagesystems is build to facilitate the study of storage battery model and control strategy.Vanadium redox flow battery has good characteristics, for example deep discharge,fast response, security and high reliability, as a result the battery suitable as wind farmstorage systems. Based on the study of the state of charge, voltage and currentcharacteristics of vanadium redox flow battery establish the structures of the cell model,and considering the battery state of charge (SOC) and fluctuation suppression effect ofwind farm output power, a fuzzy adaptive variable time constant of the low pass filtercontrol strategy is proposed. It prevents the battery overload by adjusting the filter timeconstant and optimize the battery SOC by adjustment fuzzy value. Simulation results showthat the control strategy can take into account the effect of suppressing wind farm power fluctuations and energy storage battery SOC, to prevent overcharging the battery andoptimist the battery state.The control strategy of low-pass filter has characteristics of phase delay, and whenwind power sudden has changed the controller response is slow. Then a fuzzy adaptiveKalman filter control strategy is proposed to effectively solve the low-pass filter phasedelay problem, the active target value adjusted by the state of the battery and SOC rate incontroller system, the speed of battery SOC recovery is fast. The simulation results showthat the power fluctuation output by the wind farm is suppressed and SOC of the battery iscontrolled effectively by applying proposed control strategy. Moreover, the problem ofbattery overcharge and over discharge is prevented, extending the life of the energy storagesystem. |
