单根伸长接地体的雷电冲击特性

Lightning impulse characteristics of single extended tower grounding conductor

雷电流的高频高幅特点使得接地体的冲击特性受电感效应和火花效应的影响较大,这与工频稳态时有很大不同,为研究雷电冲击条件下接地体电压、电流及接地电阻的变化特征,以典型单根水平接地体为对象,采用模拟试验和数值仿真的方法,研究了接地体长度、电流幅值、电流注入点位置对冲击特性的影响,并分析了瞬时冲击接地电阻随时间的变化特性,得出了以下结论:冲击电流幅值越大,火花效应越明显,冲击接地电阻和冲击接地系数越小,时变曲线下移,端部注入点电位高于中间注入点电位,可对电网防雷研究提供参考.

Lightning current has characteristics of high frequency and high amplitude; so its impulse characteristics are affected greatly by inductance effect and spark discharge effect; that is different under power frequency. In order to research variation characteristics of grounding conductor＇s voltage, current and im- pulse grounding resistance under lightning, this paper chooses typical single extended tower grounding conductor as research object, uses ways of testing and numerical simulation. Affecting factors of impulse characteristics are analyzed, such as length, current amplitude and current injection points. In addition impulse grounding resistance＇s change over time is analyzed. Some conclusions are drawn as follows. The move evident spark discharge effect is, the smaller impulse grounding resistance and coefficient is; time-varying curve moves down, when impulse current increases. And potential at end injection point is higher than that at intermediate injection point. Research results above provide references for lightning protection of power grid.