The good points of CHB are used in grid-connected inverter systems frequently because of their simple structure, easy modular design, and have good filtration performance. But its own resonance issue can’t be ignored, the CHB inverter is linked to the grid when the grid is connected. the grid impedance also has an impact on the cascaded H-bridge resonance, and the traditional PI control cannot be well resonant suppression and the system stability is low when the grid impedance changes. Based on this, this paper proposes an self-adaptive resonance repression method based on the gray wolf algorithm of PSO optimization, which first combines the conventional PI.The controller is replaced by a non-linear PI controller to optimize the system, and the gray wolf algorithm optimized by particle swarms is used to identify the parameters of the nonlinear PI controller and correct the parameters of the controller in time, so as to realize the cascaded H-bridge inverter to maintain system stability when the impedance of the grid changes, and improve the system's perception and suppression ability of load disturbance. Finally, the traditional PI controller, the nonlinear PI controller and the proposed method are used for experiments, and the effectiveness and feasibility of the means is proved by analyzing the simulation results.

Cascaded H-bridge; Grid-connected inverter; Resonance suppression; Gray Wolf Algorithm; non-linear PI controller.