避雷线对高压架空配电线路雷电感应电压影响的分析

Analysis of the Influence of Shield Wires on the Voltage Induced by Lightning on the High Voltage Overhead Distribution Lines

电力系统的电压等级对电力线路雷电过电压的产生起着决定作用。在架空配电线路中,直接或间接由雷击引起短暂的雷电过电压,可通过改变线路结构、安装避雷器和架设一根或多根避雷线来提高线路的耐雷水平,增加线路的临界冲击闪络电压。该文旨在分析雷击附近配电线路时避雷线对降低浪涌幅度的有效性的影响。创新性的通过缩比模型实验和计算机仿真,分析避雷线相对于每相导体的相对位置、避雷线的间距、接地电阻、雷电流的陡度以及雷电通道相对于接地点的相对位置等相关参数的组合对感应电压的影响,并用避雷线和相导体之间的电压Upg与在没有避雷线的情况下相线上的感应电压U′p的比值来表示避雷线的抑制作用,最后对仿真结果和实验结果作比较、分析。得出如上各个因素对不同情况下感应电压的影响。本文的研究结果将对以后高压配电线路的防雷起一定的指导意义,有重要的参考价值。

The mechanisms from which lightning overvoltages can be produced on a power line depend on the system voltage. In high voltage overhead distribution systems, lightning transients can be originated from either direct or indirect strokes. The main methods that can be adopted to improve the line lightning performance concern the increase of the critical impulse flashover voltage （CFO） of the line structures, the installation of surge attesters, and the use of one or more shield wires. This paper deals with the evaluation of the effectiveness of shield wires in reducing the magnitudes of the surges induced by nearby strokes on distribution lines. Innovatively through scale model experiments and computer simulations, analysis such effectiveness depends on the combination of several parameters such as the relative position of the shield wire with respect to the phase conductors, the grounding interval, the ground resistance, the stroke current steepness, and the relative position of the stroke channel with respect to the grounding points. What＇s more, the suppressive effect of the shield wire can be expressed as the ratio of the voltage between the phase conductor and the shield wire （Ups） and the voltage that would be induced in the phase conductor in the absence of the shield wire （U~）. After, by comparing and analysing the simulation and experimental results, obtained the impact of various factors on the induced voltage in each case the mentioned as above, under controlled conditions. The study results will have an important reference value on the high voltage distribution lines.