Research on resonance suppression of LCL grid connected inverter based on capacitive current feedback

This article focuses on the resonance suppression approach for LCL-type grid-connected inverters, emphasizes the use of capacitor current feedback as the basis for the strategy, and explores how to improve the harmonic suppression effect of the system while ensuring system stability by optimizing the control strategy. In this study, the advantages and disadvantages of traditional resonance suppression strategies were analyzed, and a new control scheme was proposed, which effectively addresses the distortion problem caused by voltage harmonics on grid currents. Lastly, a MATLAB/Simulink simulation model was developed for a three-phase LCL grid-connected inverter. When a control delay compensation link was added and the system parameter design met the stability requirements mentioned above, the inverter could operate stably. The delay compensation method introduced in this article successfully raised the boundary frequencies (both positive and negative) of the equivalent resistance, broadened the range of positive resistance for active damping, and ultimately fortified the stability of the grid-connected system, particularly under conditions of a weak power grid.