Power Allocation and Transient Voltage Drop Balancing in Multiple DC-Microgrids with AC Interconnections

Currently, most of the distributed generation systems have DC output, and local DC microgrids are preferred ways to accommodate various distributed generation sources. A DC microgrid often uses grid-forming inverters to supply power to AC loads. Meanwhile, a regional microgrids can be established with the interconnected grid-forming inverters from multiple DC microgrids. However, the transient power allocation and voltage drops balancing within this multiple DC-Microgrids AC interconnected system (MDAIS) are still a technology gap. In this paper, a state-space model of MDAIS is first constructed to reveal the relationship between the transient power allocation, and DC voltage drops among multiple DC microgrids, and a design scheme that can allocate the power and regulate the transient voltage drop is proposed accordingly. The scheme is able to mitigate the different degrees of impacts by AC loads on different DC microgrids and realize the cooperative control of multiple DC microgrids. Finally, the parametric design strategy is verified in a three DC-Microgrid AC interconnection experimental platform.