电感效应与火花效应对接地体及其周围土壤雷电冲击特性的影响分析

Influence Analysis of Inductance Effect and Spark Effect on Lightning Impulse Characteristics of Grounding Conductors and Its Ambient Soil

为研究电感效应、火花效应对接地体冲击特性的影响规律,区分2种效应占主导的影响范围,构建了接地体的电网络模型和考虑火花放电的迭代算法,并使用冲击大电流作用下的真型试验数据对上述模型、算法的有效性和准确性进行了验证。在此基础上,对不同波形冲击电流作用下不同长度水平接地体的冲击特性进行了仿真计算。结果表明:随着土壤电阻率的增大,接地冲击特性呈现出由电感效应影响占主导逐渐转换为火花效应影响占主导;归纳得到归一化参数的临界值为450 k A·?,可以以此定量区分电感效应影响占主导和火花效应影响占主导的范围。所得结论对于优化设计伸长接地体和水平射线的长度具有指导意义。

In order to study the influences of inductance effect and spark effect on the impulse characteristics of grounding bodies, and to distinguish the ranges dominated by these two effects, we established an electrical network model and its corresponding iterated algorithm of grounding bodies by taking spark discharge into consideration. The model and algorithm were verified in the aspects of validity and accuracy by calculations using the full-scale test data in the case of high impulse current. Moreover, we used the model and algorithm to calculate the impulse characteristics of horizontal grounding bodies with different lengths influenced by impulse currents with different waveforms. The results indicate that, with increasing soil resistivity, the dominant factor determining grounding impulse characteristics turns from inductance effect into spark effect gradually. The obtained critical value of the normalized parameter of 450 kA.Ω, can be taken as the thre- shold to discriminate the conditions with dominate inductance effect from the conditions with dominant spark effect. The results above can be used for selecting the lengths of extended grounding bodies and horizontal ray conductors.