The islanded micro-grid system using voltage-current (U-I) droop control operates at power frequency, which avoids the frequency deviation and frequency over-limit caused by traditional droop control, but it causes circulation, and inaccuracy power sharing among distributed generations (DGs). Therefore, the current synchronous U-I droop control method is proposed, which consists of current synchronous control and U-I amplitude droop control. The former can restrain the circulation by adjusting the output voltage phase angle to make the output current phase angle of each DGs consistent. The latter regulates the amplitude of the output voltage according to the amplitude of the output current so that power sharing of each DGs is distributed according to its capacity. On this basis, the small-signal model of the double-terminal system is established to analyze the influence of control parameters in the current synchronous control loop on the stability of the system, which provides a basis for parameter design. Simulation and experimental results show that, compared with U-I droop control, the proposed method can reduce the system circulation by more than 50%, improve the voltage distortion rate by nearly 10%, and improve the power distribution precision between DGs and the power quality of the system significantly.
