Modeling and Stability Analysis of Paralleled Current-Controlled Three-Phase Inverters with LCL Filter

摘要

For multiple paralleled grid-connected inverters with LCL filter, the internal resonance of the inverters and the parallel resonance among paralleled inverters can be a potential risk for stable and effective operation of the system. In this paper, a Norton equivalent model of the paralleled grid-connected inverters is established. System stability is analyzed based on the close-loop transfer function matrixes. In order to improve the stability of the system, this paper uses an active damping method based on the grid-side current feedback with lead-lag network. The active damping method can suppress the resonance of the inverters and improve the stability of the system. Finally, experimental results are given to verify the analysis made above.