Research on Control Strategy of Z-source Photovoltaic Grid-connected Inverter Based on Sliding Mode Control

Abstract

This paper proposes a photovoltaic grid-connected inverter based on a Z-source NPC three-level topology to achieve buck-boost control and improve the transmission efficiency of the system. In view of the instability of the output power of the photovoltaic system, which affects the output of the grid-connected inverter, this paper proposes a dual closed-loop sliding mode control strategy. The DC bus voltage outer loop of this strategy adopts traditional sliding mode control and grid-connected current The inner loop adopts PI control to weaken the system chatter. The anti-interference ability of photovoltaic grid-connected system and harmonic content of grid-connected current were studied through the Matlab/Simulink simulation platform. The results show that the control strategy can effectively improve the robustness of the system and reduce the harmonic content of grid-connected current.