DC-link fluctuation compensation method for PV generation system combined energy storage

A DC-link voltage compensation method for a photovoltaic (PV) generation system with energy storage system(ESS) is presented. When PV power is oscillated, the DC-link voltage is also influenced. And this fluctuation of DC-link critically affects the load voltage when the ESS is operated in stand alone mode. In conventional method, huge capacitor bank is necessary to reduce the fluctuation. In this case, if the PV power is drastically changed, large capacitance as much as the whole PV system is required to reduce the DC-link fluctuation. Therefore, the DC-link voltage compensation method is applied to the DC-link control to reduce the DC-link voltage variation without using huge capacitor bank. The proposed control method is mathematically analyzed and verified by simulation results.