Compared to the AC distribution network, DC distribution network has the advantage on reliability, transmission capacity and power flow control. This article firstly introduces the current development of DC power distribution technology and the power distribution demonstration projects at home and abroad, and sorts out the main technical standards of DC power distribution system voltage levels. On this basis, the five typical application scenarios of DC power distribution technology are clarified and the main characteristics of various scenarios are further analyzed. Study the structural differences and configuration requirements of various typical medium-voltage DC distribution networks. By comparing and analyzing the technical characteristics of various AC/DC converters, DC transformers and DC circuit breakers, the technical requirements of various DC power distribution equipment in terms of topology, control strategy, and magnetic integration technology are put forward. Furthermore, in view of the advantages and disadvantages of different control methods, research requirements for multi-operation state conversion, circulation suppression, and energy optimization are proposed. Finally, the protection requirements of AC side faults, converter faults, DC side faults and other types of faults are analyzed, and the basic requirements for DC distribution protection configuration and technical requirements for fault identification, fault location, coordination and cooperation of multiple voltage levels are put forward. 

direct current distribution network; DC voltage grade; application scenario; network frame topology; protection strategy