Abstract:The proportional integral (PI) controller is used to track the signals in the process of grid connected control.However, in the tracking of sinusoidal current signals, the problem of stability and system disturbance is often caused by the impact load,This paper presents an optimal control strategy for quasi proportional resonant (PR) inverters based on proportional resonant (PR) control technique.Firstly, the principle of PR controller is introduced,Through the improvement of the PR controller, the quasi PR controller is constructed,The influence of the parameters of the quasi PR controller on the system performance is analyzed, and the parameters of the controller are determined when the system is optimal,On the basis of quasi PR control, a harmonic compensation loop is added to eliminate the harmonic in a certain number of times.The simulation experiment is carried out by using MATLAB/Simulink, and the experimental results of PI controller and quasi PR controller are compared and analyzed,It is proved that the improved quasi PR control can realize zero static error tracking and steadystate error elimination in the grid connected inverter system, and guarantee the dynamic stability of the system.