LCL types grid-connected inverter without damping has the advantages of high efficiency and low harmonic distortion rate, but the problem of high frequency resonance often occurs in engineering applications. Aiming at the high frequency resonance problem of the LCL type grid-connected inverter without damping, this paper first simplified the grid-connected inverter model, and obtained a single-phase linear model suitable for high-frequency stability analysis. Then, the influences of grid impedance, filter inductance saturation, multi-machine parallel connection to the high-frequency stability of grid-connected inverter are separately analyzed. Additionally, the key part affecting high-frequency stability are pointed out and improvement measures are given. Finally, the correctness of the analysis in this paper is verified by digital simulations.
 

LCL filter without damping;grid-connected inverter;high frequency resonance