The stochastic volatility of photovoltaic power has a certain impact on the stable operation of power grid. To solve this problem

a method called hybrid energy storage system（HESS） for smoothing photovoltaic output fluctuation

which is based on adaptive variational modal decomposition

is proposed. Firstly

according to the typical photovoltaic output scenes

combined with photovoltaic power fluctuation standards and energy storage component characteristics

the variational mode of original photovoltaic power self-adaptability is decomposed to achieve primary power distribution;then secondary modification for the primary power of the HESS is performed using fuzzy control inside HESS according to the state of charge of super capacitor. The research results show that the proposed strategy is able to achieve optimal decomposition and rational distribution of photovoltaic output

and the method can reduce photovoltaic power fluctuations effectively and avoid excess capacity of energy storage components; the optimization and modification of primary power based on fuzzy control ensure the state of charge（SOC） of HESS to work within the reasonable range

extending the service life of energy storage component greatly. The research results provide a solid foundation for wide use of the variational mode decomposition algorithm

and provide a certain theoretical foundation for the achievement in reliable grid connection of large-scale photovoltaic power station and the development of photovoltaic power online control.