直流接地极附近架空光缆拉线的接触电势研究

Study on the Touch Potential of Stay Wires of an Overhead Optical Cable Near DC Grounding Electrode

直流系统单极大地运行时通过接地极注入大地的电流会造成系列负面影响,某直流工程系统调试期间测得临近接地极的一架空光缆线路拉线接触电势高达440 V,安全风险极高。首先分析了架空光缆系统的结构特点,发现架空光缆的吊线与接地拉线构成了一个长距离多点接地系统。对典型架空光缆系统拉线的接触电势进行了理论计算,发现拉线接触电势取决于吊线接地点间的电位差和拉线接地电阻。采用基于边界元法的仿真软件CDEGS研究了土壤、线路走廊、以及拉线参数等对接触电势的影响,最后提出了通过绝缘子将吊线电气断开来保证每段吊线单点接地的解决方法。

The DC current flowing through a grounding electrode into the earth during monopolar operation of HVDC systems with ground return may cause a serious of negative effects.The touch potential of a stay wire of an overhead optical cable near the grounding electrode is as high as 440 V during the commissioning of a DC engineering system,which is a high risk to safety.In this paper,the structure characteristics of the overhead optical cable system and the reasons for the high touch potential of the stay wire drawing are analyzed.It's found that the overhead cable system and stay wire constitute a long distance multi-point grounding system.In this paper,the contact potential of a typical overhead optical cable system is theoretically calculated,and it is found that the contact potential of the drawing line depends on the potential difference and the wire grounding resistance.A simulation model based on the boundary element method is used to establish the simulation model of the grounding electrode optical cable system,and the influence of the soil model,the parameters of the line corridor and the joint location on the contact potential of the stay wire is studied.At the end of the article,it's proposed that as long as there is only one grounding point at each section of wire,the risk of touch potential can be removed.