Abstract: Wind energy is a kind of highly uncontrollable natural resource.Random changes of wind energy will lead to fluctuations in the output power of wind turbines.Output power fluctuations will cause grid frequency fluctuations and voltage flicker,which even endangers the power grid security directly.In order to meet the requirements of wind farms and improve the power quality of power grid,power smoothing technology has become an urgent problem to be solved.This paper introduces two types of power smoothing methods,that is direct power control and indirect power control,and expounds principles of a variety of specific methods.The present research work of the various methods is given.In addition,the merits,demerits and application situations of each method are summarized.Finally,the current optimization direction of the power smoothing control technologies is carried out.