Resonance damping characteristics of a distributed inverter-based system（DIBS） will be influenced by grid voltage feed-forward control in weak grid condition as the actual feed-forward component contains information of capacitor voltage. By taking the digital control delay into consideration

a mathematical model of grid voltage feed-forward and capacitor current feedback controlled DIBS is established. According to Mason rules

the equivalent virtual impedance formed by control loop is obtained through a set of equivalent transformation

and corresponding impedance characteristics are analyzed. Base on Bode diagrams of system open-loop gain

the influence of grid voltage feed-forward control on resonance damping characteristic of DIBS is fully discussed in the presence and absence of digital control delay. Theory analysis and simulation results show that grid voltage feed-forward can shift resonance frequency under the both conditions. In addition

the damping performance of capacitor-current feedback control can be improved

and the robustness of system stability against grid impedance variation with digital control delay can be Increased.