Distributed Cooperative Control for DC Microgrid Clusters Interconnected by Multi-port Converter

Compared with AC microgrids, DC microgrids have attracted much attention due to the advantages of integrating distributed renewable energy generation systems, energy storage units, electric vehicles and other DC loads efficiently and reliably, without considering the issues of the frequency synchronization, the reactive power compensation, the power quality and so on. However, the current research on DC microgrid mainly focuses on the optimization and control of a single DC microgrid while ignoring the energy exchange and mutual support among multiple DC microgrids. In this paper, based on the consistency theory, we propose a distributed cooperative control method and apply this method to multiple DC microgrids which are connected by a multiple-active-bridge (MAB) converter. Each terminal port of the MAB converter is regarded as the internal node of the corresponding sub-microgrid. Thus, the accuracy of the average bus voltage is improved and the bus voltage of each sub-microgrid is stable and error-free. The output power of each distributed generation unit in a sub-microgrid is balanced. Meanwhile, the MAB converter can regulate the power flow according to the average voltage error and the output power of different microgrids, thereby achieving the energy exchange and mutual support between multiple DC microgrids. The output power of each distributed generation unit in all DC microgrids can also be balanced. Finally, the performance of the distributed cooperative control method is verified by simulation results.