Strategy for Smoothing Photovoltaic Power Fluctuation of Hybrid Energy Storage System Using Self-adaptive Variational Mode Decomposition

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. © 2019, High Voltage Engineering Editorial Department of CEPRI. All right reserved.