Abstract: A mathematical model of LCL grid-connected inverter system is established to solve the problems of low stability margin and excessive harmonic when LCL grid-connected inverter is connected to a weak grid.Firstly,the influence of wide range of power grid impedance on system stability is analyzed.A capacitor voltage feedforward control strategy based on inverter side current feedback control system is constructed.Secondly,based on the principle of minimizing the number of sensors,the parameters of the capacitor voltage active damping are designed and the filter is superimposed on the feedforward compensation link to optimize the design,so that the grid-connected inverter always has sufficient stability margin in weak grid.Finally,a grid-connected inverter simulation model and prototype are built to verify the effectiveness,and the feasibility of the proposed method are verified.