杆塔接地体冲击对输电线路雷电反击分析

Analysis of Lightning Back Striking of Transmission Line Considering Impulse Characteristics of Grounding Electrodes

为了减少雷害事故的发生,为输电线路防雷提供科学依据,计算输电线路雷电反击跳闸率时必须考虑杆塔接地体冲击特性。通过EMTP建立了线路及杆塔模型,考虑雷电流作用下接地体冲击特性,分析线路反击时杆塔和接地体暂态电压变化规律。计算不同土壤电阻率和接地体长度下线路反击跳闸率,同时讨论工频电压对反击跳闸率的影响。分析结果表明:雷电流幅值较大时,接地体冲击接地电阻降低明显。工频电压对线路反击跳闸率有一定影响。增加接地体长度和降低土壤电阻率可以有效减少线路反击跳闸率。

In order to prevent the power failure caused by lightning and provide scientific bases for the lightning protection of transmission lines, it is necessary to considering impulse characteristics of grounding electrodes when calculating back striking trip-out rates of transmission lines. Equivalent circuit models of transmission lines and tower are built by EMTP, the impulse characteristics of grounding electrodes under lightning are considered, discussing the transient change rule of the tower and the grounding electrodes during back striking of transmission line, Back striking trip-out rates under different soil resistivity and grounding electrodes are calculated, and the effect of power frequency voltage on back striking trip-out rate is discussed. The analysis results show that： the impact grounding resistance of grounding electrodes is reduced obviously when lightning current amplitude is high. Frequency voltage has a certain influence on back striking trip-out rates. The back-flashover tripout rates can be effectively reduced by increasing the length of the grounding electrode and reducing the soil resistivity.