Abstract: Compared with traditional Z-source and quasi-Z-source inverter, tapped-inductor quasi-Z-source inverter (TL-qZSI) has higher booster multiple, lower capacitance stress and higher conversion efficiency. Therefore, it is very suitable for grid-connected photovoltaic power generation system. This paper analyzes the voltage boosting theory of the TL-qZSI and applies it into grid-connected photovoltaic power generation system. For the imbalanced power grid voltage sag situation, this paper puts forward a low voltage ride-through (LVRT) control strategy. System realizes the unity power factor running and has a good LVRT ability under imbalanced power grid voltage sag. At last, the simulation and experimental results are shown to verify the correctness of the control method.