低压配电网零线电压分布的研究

Research on the voltage distribution in neutral wire of the low voltage distribution network

我国低压电网用电采用380V/220V三相四线制供电系统。由于零线不与地线直接相连,为了保护用户,防止发生触电事故,通常还需要单设一条地线将用电设备接地。但是很多地方的楼宇住宅没有地线或者地线接地不是很好,在使用电器设备时就存在着一定的安全隐患。在三相负荷对称的情况下,零线与大地电位相等,但是当三相负荷不对称时,零线的电位将出现偏移。本文通过理论分析和Matlab/Simulink软件仿真计算了零线上的电压分布情况,计算结果表明零线上的偏移电压不会超过36V,不会对人体造成危害。在电器设备的设计中虽然零线不能代替地线的使用,但可以用零线当作地线的备用,对低压电器设备的安全运行起到辅助作用。

The 380V/220V three-phase four-wire power supply system is generally used in low-voltage power grid in our country, in which the neutral wire is grounded. In the general case, the neutral wire and the ground potential equal to zero and thus human body＇s contact with the line is safe. But in real life, the human body electric shock accident often happens due to contact the neutral wire , which shows the neutral wire potential is not zero. This article does not appear in the zero line disconnection and asymmetry load of no more than 10% in the range of the premise, through theoretical analysis and Matlab / Simulink simulation software platform the voltage distribution on neutral line, verify the ＂offset voltage＂ of the neutral wire not great, less harmful to the human body, and even can be used as ground line, thus plays a supporting role in the safe operation in low-voltage distribution system.