Research progress of AC, DC and their hybrid micro-grids

Micro-grid technologies have greatly attracted attention due to quick development of distribution energy resources. Micro-grid studied by researchers primarily includes AC micro-grid, DC micro-grid and AC-DC hybrid micro-grid. The advantages and application of these three types of micro-grids have been introduced and analyzed in this paper. The grid architecture, energy management, operation control and protection strategy of AC-DC hybrid micro-grid are further summarized in detail.