Abstract: To reduce the fluctuation rate of wind power and improve the reliability of grid, this paper proposes a control method of smoothing wind power output with battery energy storage system based on fuzzy empirical mode decomposition （EMD）. Wind power is decomposed by EMD into two parts, the low-frequency part is used as wind power grid-connected value and the high-frequency part is stored by battery energy storage system （BESS）. Taking the fluctuation rate of wind power output after smoothing and the state of charge （SOC） as constraints, the orders of EMD filter can be adaptively adjusted on-line based on fuzzy control method, which can smooth wind power fluctuation better through fuzzy adaptive controller. Compared with another energy storage system control strategies for smoothing wind power, the simulation results show that the proposed method can effectively smooth the fluctuation of winds power output and avoid the over-charging and over-discharging of energy storage system so as to keep SOC stable.

Key words: empirical mode decomposition （EMD）, power smoothing, fuzzy control method, fluctuation rate, state of charge （SOC）