Optimal capacity selection of hybrid energy storage systems for suppressing PV output fluctuation

Photovoltaic (PV) system is installed in power system as one of the countermeasures for problems of the global warming. The output fluctuations due to the climate condition make an impact to the power system. As one of solutions for this problem, installation of the battery energy storage system (BESS) has been proposed. However, since the BESS is still expensive, it is favorable to reduce the capacity of the BESS to save installation cost. In this study, we propose the operational procedure based on the cloud cover to suppress output fluctuation of PV. Since cloud cover affects to PV outputs significantly, the control procedure of BESS that use this information is promising. The procedure can save the BESS's capacity, and can suppress the fluctuation. We also propose the hybrid storage system composed by the battery and the capacitor. This system can reduce the capacity of the battery and the frequency of charge-discharge cycle.