A Hybrid Energy Storage Strategy Based Fuzzy Control to Suppress Power Fluctuation of Grid-Connected Photovoltaic Power System

Aiming at the problem that the grid-connected power fluctuation of the photovoltaic (PV) power system affects the stability of power grid operation, a fuzzy control strategy based on the supercapacitor battery hybrid energy storage system (HESS) to suppress power fluctuation is proposed. Secondly, a fuzzy controller is established based on the grid-connected estimated fluctuation power of the PV power system and the current state of charge (SOC) of the HESS. The time constant of the low pass filter (LPF) is adjusted to allocate the fluctuating power in real-time, the high frequency fluctuating power is smoothed by the supercapacitor, and the low frequency fluctuating power is smoothed by the battery. So the purpose of rationally distributing power between different energy storage medium is achieved. In addition, according to the SOC variation of HESS, a fuzzy controller is established to correct the charge-discharge capacity of the supercapacitor and battery, calculate the actual output power of the current supercapacitor and battery, and update the energy state of the HESS in real-time. Finally, the Simulink simulations verify the effectiveness of HESS fuzzy control power allocation and smoothing grid-connected power fluctuations.