摘要
在进行变电站的地网设计、确定变电站的安全指标(跨步电压和接触电压等)、以及研究电力电缆线路短路对邻近通讯系统的影响时,短路电流的分布和入地短路电流的计算至关重要。为此,建立了电缆金属护套两端直接接地和交叉互联两端接地的电缆线路的简化等效模型,在此基础上提出了一种用于计算广州高压电缆网络单相接地短路时短路电流分布和电缆分流系数的方法,并在实际运行的电缆线路上进行了试验验证。结果表明,只有很少一部分的短路电流是经变电站的接地网入地并通过大地回流的,绝大部分的短路电流是经过电缆护套回流的,且主要经过所谓的"主路径"的金属护套回流的。最后在分析计算的基础上对地网的设计、通讯干扰、单相短路时电缆金属护套上的工频过电压等问题进行了讨论。
The ground fault current distribution and the shunt factor of power cable is important parameters for the design of substations ground grid, the correct estimation of the safety conditions （step and touch voltages） in the substation and the interference to the communication system nearby. In this paper, a simplified equivalent model is presented to express the three single-core cable sheaths, which are two-ends grounded with or without applied cross- bonding connection. Based on this model, the paper presents an original analytical procedure for determination of the ground fault shunt factor when a ground fault occurs in the substation supplied by HV cable network. The method is proved to be a practical and precise technique for evaluating the ground current distribution and the shunt factor in HV cable system. The result indicates that only a little fault current is returned through grounding grid, the most is returned through cable sheaths. Moreover, it is returned through the sheaths of so-called ＂main line＂. Based on the analysis, correlative problems about designing of grounding grid, disturbance on communication lines, the power frequency overvoltage in sheath under single phase grounded, and etc, are discussed.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2007年第10期142-146,共5页
High Voltage Engineering
基金
广州供电局科技进步项目(D8040540)。~~
关键词
电缆网络
短路电流
分流系数
金属护套
接地网
单芯电缆
cable network
ground-fault current
reduction factor
metal sheath
grounding grid
single-core cable
