Virtual Infinite Capacitor for Grid-Connected Inverter

The DC voltage of PV single-phase grid-connected inverter contains a lot of double power frequency ripple, which leads to higher third harmonics in the AC output, which affects the output power quality of the inverter. The virtual infinite capacitor (VIC) can effectively decrease DC voltage ripple, reduce the capacitance of the filter capacitor, reduce the capacitance volume, and increase the power density of the system. Therefore, this paper presents a virtual infinite capacitor for grid-connected inverters. Based on VIC principle, the control strategy of VIC is changed, and a single phase PV inverter grid-connected system is constructed. The simulation realizes the operation of the grid-connected system, the results verify that the virtual infinite capacitor used in the grid-connected system has the effect of decreasing the voltage ripple of the DC bus, reducing the capacitance capacity of the circuit, and improving the output power quality.