输电线路杆塔对雷电流监测结果的影响

在输电线路上实际测量雷电是进一步了解雷电流各种参数的有效手段,但实际测量到的结果是受被击物体影响后的雷电流。为了通过测量结果得到雷电流的原始波形,在输电线路杆塔模型中考虑了雷电波在杆塔传播过程中的衰减、畸变以及杆塔冲击接地电阻等因素,采用电磁暂态分析程序PSCAD对两种不同的输电杆塔进行了仿真计算,并对是否装设避雷线的情况进行了比较分析。结果表明避雷线对于雷电波的传播有很明显的影响,雷击输电线路杆塔时塔顶和塔底的雷电流波形有显著的区别,塔底电流随着杆塔的增高而变大。

Influence of Transmission Tower on Measured Lightning Currents

In order to further understand the lightning current parameters, measurements were carried out on transmission line towers. However, the measured results were influenced by the structure involved. Investigating the current distortion due to the reflection and propagation effect is necessary to establish the relations between original and measured lightning current parameters. The tower model used in this paper takes into account many factors, such as the lightning current waveform attenuation and distortion, the impulse grounding resistance of tower grounding device. We used electromagnetic transient analysis software PSCAD to carry out the simulation of the transient process when lightning strikes a tower, two typical towers are considered, and conditions with and without overhead shielding wires are discussed. The result shows that the overhead shielding wire has an obvious effect on the lightning current waveform measured, and the results measured on the top and at the bottom of the tower have a huge disparity, in terms of the current both peak value and the waveform. The lightning current at the bottom of the transmission tower increases with the height of the tower, and the height of the tower has small impact on the lightning current on top of the tower. The lightning current distortion on the top of the tower and the lightning current at the bottom of the tower with the overhead shielding wire become smaller than that without the overhead shielding wire.