A Practical Method for Transient Analysis of Grounding Grids

Abstract

A practical method is proposed in this paper for analysis of the lightning transient in the grounding grids. The circuit parameters of the grounding electrodes are evaluated by a set of analytic formulas, in which the soil ionization effect is taken into account. By means of the circuit parameters, the grounding electrode segments are represented by the π‐type circuits and a circuit model is built for the grounding grids. The lightning transient responses in the grounding grids can be calculated from the circuit model. The calculated results are compared with the measured ones to check the validity of the circuit model. In view of the actual distribution randomness, the lightning current amplitude is taken as a random variable and a statistical algorithm is further presented for statistical analysis of the lightning transient in the grounding grids. In the algorithm, the accumulative probability function is introduced to describe the random distribution of the lightning current amplitude. The lightning transient responses calculated in a large interval of the lightning current amplitude are weighted by the corresponding probability density. Then, the statistical values of the lightning transient responses can be obtained from the weighted sum. A numerical example is also given to discuss the difference between the statistical values and the nonstatistical ones calculated by the conventional method. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.