Research on improved current control strategy of LCL grid-connected inverter under weak grid

Under weak grid conditions, significant changes in grid impedance can lead to decreased stability in grid-connected inverter systems, and grid harmonics and LCL filter resonance issues often distort the current waveform. To address these challenges, this paper proposes an improved current control method. The strategy utilizes a negative second-order high-pass filter, and the three-phase LCL-type grid-connected inverter is modeled, with the control parameters optimized. This approach enhances the system’s phase margin, increases the inverter’s adaptability in weak grids, and improves power quality. The accuracy and efficacy of this control method are confirmed through Matlab/Simulink simulations.