A novel design of architecture and control for multiple microgrids with hybrid AC/DC connection

Abstract Microgrid provides an effective approach to utilize distributed renewable energies (DREs). Given the ongoing transformation of distribution system with high penetration of DREs, coordinating and consuming a large amount of distributed generators (DGs) within one single microgrid has become increasingly infeasible. Interconnecting multiple microgrids as a microgrid cluster is an effective way to improve the operation quality of large-scale DG integration. As the keys to the microgrid clusters, the flexible configurations and coordinated operation among multiple microgrids have not been adequately addressed. In order to solve this problem, a novel architecture for multiple microgrids and its coordinated control schemes are designed. Firstly, the advanced microgrid interface named hybrid unit of common coupling (HUCC) is designed and utilized in replacement of the conventional point of common coupling (PCC). The HUCC employs modular multilevel converter (MMC) as its core component and provides both AC and DC interfaces. Then, this paper puts forward a HUCC-based architecture for multiple microgrids where microgrids are grid-connected via the AC interfaces and interconnected via the DC interfaces. Based on the proposed architecture, coordinated control schemes under different operation scenarios are came up with at last. A case study of the HUCC-based multiple microgrids is performed in PSCAD/EMTDC on the basis of the demonstration project in Guangxi, China. The simulation results show that the interconnected microgrids with the proposed architecture and control schemes operates effectively and efficiently under different operation scenarios. The proposed architecture and control schemes not only enhance the large-scale integration of DREs, but realize the optimal use of DGs as well.