Abstract:Aiming at the problems of grid uncertainty disturbance in grid-connected current control of three-phase grid-connected inverter, system coupling in dq coordinate system and the dependence of traditional controller design on accurate mathematical model, a linear active disturbance rejection control strategy based on two-phase stationary coordinate system is proposed. Taking T-type three-level LCL grid-connected inverter as the controlled object, a three-order linear active disturbance rejection controller is designed. Through the equivalent transfer function of the system, the stability and immunity of the inverter system are analyzed in detail, and the effectiveness of the proposed control strategy is verified by simulation and experiment. The results show that the designed control strategy can improve the stability and immunity of T-type three-level LCL grid-connected inverter, and achieve good control of the grid current, and the total harmonic distortion is controlled at 2.2 %. At the same time, the ' bandwidth ' parameter tuning method has clear physical meaning, simple parameter adjustment and high engineering application value.