Study on voltage coordinating control of a LV DC micro-grid based voltage-source converters

摘要

When the master-slave strategy is employed for the DC bus voltage control of a DC micro-grid, the voltage is determined by the constant DC voltage control converter. The DC voltage will be unstable when the active power is unbalance or the constant DC voltage control terminal is tripped off against faults. At this scenario, the DC voltage must be controlled through the coordinating control of the system supervisor layer through communication. In this paper, a novel method using the voltage coordinating control through the voltage margins is presented. By carefully selection of the margins according to the system strength and converter type, the DC bus voltage of a VSC DC micro-grid can be controlled steadily after a variety of faults. The author designed a 4-terminal low-voltage VSC DC micro-grid prototype system and developed a simulation model for the system. The effectiveness of the control strategy for the 4-terminal DC micro-grid is illustrated through simulations using PSCAD/EMTDC.