Abstract: With the wide application of renewable energy, LCL grid-tied inverters play a key role in converting DC power into AC power and connecting it to the grid. The LCL filter has a filtering effect on higher harmonics, there is a resonance peak because it is a third-order underdamping, Active damping can be used to reduce the resonant amplitude, However, digitally controlled delay can change the active damping characteristics of the capacitor current, setting its output resistance and the cutoff frequency of the filter capacitor to f_s/6, affecting the robustness to the impedance of the grid. In this paper, the current double closed-loop control strategy is adopted, and the power system stabilizer is added to the active damping branch(PSS). Through the simulation results, it can be seen that the proposed method can improve the positive and negative demarcation frequency of the active damping equivalent resistance, improving the robustness of the system to different grid impedances.