1次人工触发闪电引起的临近地网电位升高及其特征分析

Ground Potential Rise Between the Adjacent Ground Networks Based on One Artificially Triggered Lightning

为了研究近距离闪电发生时临近地网地电位升高的电压特征,对1次触发闪电过程中2个相距40 m的地网地电位升高电压的观测数据进行了分析。研究结果表明:(1)3次回击对应的地电位升高电压峰值范围为-9.0kV^-15.4 kV,均在亚μs时间内快速下降形成次峰,下降幅度分别为51.1%、51.9%和53.9%,之后缓慢下降;(2)11次M分量引起的地电位升高电压峰值范围为-0.3 kV^-3.0 kV,平均为-1.0 kV;10%~90%上升时间范围为14.0μs^776.6μs,平均为190.7μs,与对应触发闪电电流特征基本一致;半峰宽度范围为49.6μs^1 005.4μs,平均为317.9μs,是对应雷电流参数平均值的1.5倍;(3)回击过程地电位升高电压峰值与雷电流峰值及雷电流陡度的相关系数分别为0.96和0.98,回击阶段的地电位升高是由雷电流在土壤中的泄放和感应耦合共同作用的结果;M分量过程地电位升电压峰值与雷电流峰值及雷电流陡度的拟合系数分别为0.99和0.73,M分量引起地网地电位升高主要是由雷电流在土壤中的泄放引起的,感应耦合的作用是第2位的。长连续电流叠加M分量会使临近地网的地电位升高电压长时间维持在较高水平,这是临近地网地电位反击导致浪涌保护器(SPD)损坏的重要原因。

In order to further study the voltage characteristic of the GPR when the close-range lightning stricks, we ana- lyzed the data from artificially triggered lightning experiments of the elevated voltage of the GPR 40 metres apart. And the conclusion can be drawn that： （1） The peak values of GRPs related to 3 return strokes ranges from -9.0 kV to -15.4 kV, then the GRPs fall to 51.1%, 51.9%, and 53.9% of its peak value and forms 3 sub-peaks respectively within several microseconds. （2） The peak values of GPRs caused by M-component have a range of -0.3 kV to -3.0 kV, the average value is -1.0 kV; the scope of 10%-90% rising time is between 14.0 ~ts to 776.6 ~ts with a mean value of 190.7 p.s, which is 1.5 times that in lightning current. （3）In the realm stroke stage, the linear correlation coefficient of peak value and gra- dient between GPR voltages and direct lightning current are 0.96 and 0.98, respectively. The GPRs in return stroke stage is a combined effort of current discharge in soil and inductive coupling; In M-component process, the peak values of GPRs and direct lightning current are almost the same, however, the correlation coefficient of waveform gradient is just 0.73, which means the GPRs during M-component progress is mainly caused by lightning current discharge in soil, the inductive coupling can only be the secondary factor. The GPR between the adjacent ground networks will be long-time kept at a rather high level by M-component with the continuous current superposition, and that is an important reason for the damage of Surge Protective Devices （SPD） led by the ground potential counterattack between the adjacent ground networks.