城市轨道交通低压直流配电系统研究

城市轨道交通低压配电广泛采用交流配电系统。随着直流用电设备在城市轨道交通的大量应用，采用低压直流配电系统将成为趋势。但是，中外均缺乏城市轨道交通低压直流配电系统的工程案例和设计标准。因此，对城市轨道交通低压直流配电的电压等级选取、配电系统结构、接地类型和电气保护方式进行研究。结果表明，相同供电距离时，DC 750(±375)V供电网络的供电能力约为AC 380V的4倍。根据城市轨道交通用电负荷特点，低压直流供电系统主母线电压等级采用DC 750(±375)V、DC 220V(±110)V两级，主接线结构采用双极三线制，城市轨道交通低压直流配电系统应采用IT接地型式。

Low-Voltage DC Power Distribution in Urban Rail Transit

Presently, the AC distribution system is widely used in low-voltage distribution systems of urban rail transit. With the extensive application of DC power equipment in urban rail transit, the use of low-voltage DC distribution systems has become a trend. However, there is a lack of engineering cases and design standards for the low-voltage DC distribution systems of urban rail transit at home and abroad. Therefore, we study the voltage level selection, distribution system structure, grounding type, and electrical protection of low-voltage DC distribution in urban rail transit. We found that the power supply capacity of a DC 750 (±375) V power supply network is approximately 4 times that of AC 380 V at the same power supply distance. According to the electric load characteristics of urban rail transit, DC 750 (±375) V and DC 220V (±110) V should be used in the main bus voltage class of low-voltage DC power supply systems, and the main wiring structure should adopt the bipolar three-wire system. Furthermore, IT grounding should be used in the low-voltage DC distribution systems of urban rail transit.