A hybrid energy storage strategy based on multivariable fuzzy coordinated control of photovoltaic grid-connected power fluctuations

Aiming at the problem that the grid-connected power fluctuation of the photovoltaic power system affects the stability of grid operation, a multivariable fuzzy coordinated control strategy for photovoltaic grid-connected power fluctuation based on super-capacitor and battery is proposed. First, a multivariable fuzzy controller is established based on the grid-connected estimated fluctuation power of the photovoltaic power system and the current energy state of charge of super-capacitor and battery. The fuzzy relational matrix is used to introduce interaction effects of inputs into the fuzzy control, the fuzzy relation matrix is established by multiplying with weights, and the time constant of the low-pass filter is adjusted to coordinate the distribution of fluctuating power between different energy storage in real-time. Second, according to the SOC variation of HESS, a super-capacitor fuzzy controller and battery fuzzy controller are established to modify the charging and discharging instructions of battery and super-capacitor. The charging and discharging power of the energy storage are constraints to optimize the charging and discharging power of the energy storage, and the energy state of the HESS is updated in real-time. Finally, an overall example analysis of fuzzy coordinated control is performed to verify the effectiveness of the proposed control strategy.