Abstract: With the increasing popularity of renewable energy sources such as photovoltaics and wind power，

improving the reliability and stability of grid-connected system operation has become a key technology in the

system. Affected by the dynamic characteristics of the grid，if the traditional droop control is still used in the case of

the grid voltage imbalance，the grid-connected inverter will not be able to operate stably and effectively，and the

voltage and current imbalance at the point of common coupling（PCC）will also be increased accordingly. Aiming at the problem of voltage imbalance at the PCC in the grid-connected system，an improved voltage imbalance

compensation control strategy was proposed. Based on the traditional droop control，a positive sequence reactive

power droop compensation loop and a negative sequence voltage feedforward compensation loop were introduced

and superimposed to generate the inverter output voltage compensation reference value，so as to effectively reduce the voltage imbalance of the grid connection point. The small signal model of the system was established，and the stability analysis of the control strategy was carried out on this basis. Finally，the effectiveness and feasibility of the droop control strategy was verified by the simulation.

      Key words: droop control；unbalance compensation；negative sequence voltage feedforward；small signal

analysis