110kV双回线路管型复合材料绝缘杆避雷线接地引下方式研究

Study on Grounding Down Mode of Shielding Wire of Tubular Composite Material Insulating Pole of 110 kV Overhead Line of Double Circuit

为了解决我国南部沿海地区110 k V双回架空线路试点应用的管型复合材料绝缘杆(简称"复合材料杆")所存在的接地引下线易短接杆身绝缘的问题,针对典型设计的110 k V双回线路复合材料杆的结构特点,分析了避雷线采用沿杆表面架设接地引下线方式所面临电气问题的本质成因,提出了沿导线方向在两回线路中心线上竖直架设引下线的方式,定义为内侧竖直接地引下方式。该方式实现了将铁塔2项功能分离:复合材料杆起结构支撑作用、接地引下线起导电通流功能。通过真型杆头雷电冲击放电试验,证实了内侧竖直接地引下方式较沿杆表面接地引下方式的电气优势:沿杆表面和内侧竖直2种接地引下方式下的雷电冲击绝缘强度U50%分别为960 k V和1 230k V,后者较前者提高了28%;观察内侧竖直接地引下方式中雷电冲击放电路径,当垂直引下线离杆身距离大于0.60 m时,可避免沿杆表面接地引下时雷击闪络和工频续流电弧烧蚀复合材料横担,并可利用杆身绝缘性增加相对地爬距。结合雷电性能计算,获得了内侧竖直接地引下方式的雷电性能,与沿杆表面接地引下方式相比,反击耐雷水平提高了28%,雷击闪络跳闸率降低了54%。因此110 k V双回线路管型复合材料杆避雷线采用内侧竖直接地引下方式的雷电性能明显优于沿杆表面接地引下方式。

Tubular composite material insulating pole （composite material pole for short） is applied in pilot projects of 110 kV overhead line of double circuit in the coastal regions of South China. In order to solve the problem that grounding down-lead is easy to cut through the insulation of pole body, according to the characters of typical composite material pole of 110 kV overhead line, we analyzed the essential causes of the problem of the grounding down mode with down-lead erected along the surface of the pole. We put forward a new grounding down mode, in which the down-lead vertically suspended conductors were erected on the center line between the two circuit lines, and defined it as a vertical down-lead mode in the internal side of line. The new grounding down mode can separate the two functions of steel tower： composite material pole takes the function of supporting conductors and down-lead takes function of leading the lighting current. Then, the lightning impulse discharge of true type pole head was tested to determine lightning impulse dielectric strength U50% of the two grounding down mode, down-lead erected along the surface of the pole and vertical down lead mode suspended in the internal side of line, which were 960 kV and 1 230 kV, respectively, the latter was 28% more than the former. According to the impulse discharge path of the vertical down lead mode suspended in the internal side of the line, the distances of grounding down-lead from pole body were determined. Moreover, the lightning performance of the two grounding down modes could be obtained by the theoretical calculation, and the lightning withstand level and lightning flashover trip rate of the new grounding down mode increased by 28% and decreased by 54% than the formermode, respectively. Therefore, the lightning performance of composite material of 110 kV overhead line of double circuit with down-lead vertically suspended on the center line between the two circuit lines is much better than that with down-lead erected along the surface of the pole.