When digital control is adopted in an LCL-type grid-connected inverter

the traditional capacitive current feedback active damping will be equivalent to the impedance which is related to frequency

and in the frequency band greater than 1/6 of the sampling frequency

the impedance will show negative damping characteristics. Under the condition of weak power grid

the grid impedance which is time-varying in a wide range will change the resonant frequency of LCL. If the resonant frequency of LCL is greater than 1/6 of the sampling frequency

the robustness will be seriously threatened. To solve the above problem

we put forward a novel capacitor current feedback active damping strategy

and introduced the phase-lead compensation link into the capacitor current feedback branch to reduce the influence of phase lag caused by control-delayd

and to promote the effective damping area of active damping. Moreover

we analyzed the improved system under the discrete domain. Finally

a simulation model of the single-phase LCL grid-connected inverter was built for simulation verification. The research results show that this strategy ensures the grid-connected inverter to always have a good robustness in the weak grid; meanwhile

compared with the existing compensation strategy

this strategy introduces less high-frequency harmonic and is more conducive to the control of grid-connected inverters in weak grid.