Double closed-loop control strategy of LCL three-phase grid-connected inverter

摘要

Grid-connected inverter is an important part of the grid-connected system. Compared with the traditional L or LC filter, LCL filter has a better high-frequency harmonic attenuation performance. However, LCL filter has resonant peak, which has a great influence on the stability of the system. This paper first analyzes the effect of passive damping method on the resonance peak; then a double closed-loop control strategy with the inner loop of capacitor current and the outer loop of grid current is introduced; finally, the LCL three-phase grid-connected inverter with double-loop current control significantly reduces the Total Harmonic Distortion (THD), which verifies the feasibility of parameters design scheme of control strategy.