Research on Dual-Closed-Loop Control Strategy for LCL-Type Three-Phase Grid-Connected Inverter

The three-phase inverter is a crucial component for integrating photovoltaic power generation into the grid. Its performance directly impacts the stability and power quality of grid-tied photovoltaic systems. To address the issue of high Total Harmonic Distortion (THD) in three-phase grid-tied inverters, this study proposes a novel three-phase LCL grid-tied inverter. The LCL filter circuit parameters are analyzed, and a mathematical model of the three-phase grid-tied inverter in the dq rotating coordinate system is established. A dual closed-loop feedforward control strategy is proposed for the current inner loop and voltage outer loop in the rotating coordinate system. The correctness of the inverter design is verified using MATLAB/SIMULINK.