부산대학교 도서관

Traditional droop control methods are diffi cult to achieve accurate and autonomous current sharing between micro-source converters in DC microgrid, due to the mismatch of line impedance and the existence of low-speed communication. In this paper, an autonomous current sharing control strategy based on active frequency injection and line impedance compensation is proposed. Firstly, an active frequency injection method is used for all supported voltage-source converters. Under the feedback mechanism of the reactive power and voltage, the accurate current sharing can be achieved, and the total equivalent droop coeffi cient of each converter would be approximately equal. On the basis, the line impedance compensation information of each converter can be obtained accurately. Then, the original droop control method, in which the droop coeffi cient is the obtained compensation value, is utilized to replace the injection method. Without introducing any communication, this method not only can ensure the accuracy of load current sharing, but also can eff ectively improve the large ripple problem caused by frequency injection method, and avoid the secondary bus voltage drop. The design process and stability of the controller are analyzed in detail. Finally, the feasibility and eff ectiveness of the proposed control strategy are verifi ed by using the corresponding simulation model and HIL experimental platform.