Simulation and experimental verification of lightning current division characteristics of 220 kV transmission towers based on multi-wave impedance model

Abstract To address the discrepancy between the research on the impulse characteristics of existing single grounding devices and actual lightning strike scenarios, this paper conducts a study on the lightning current division characteristics of 220 kV transmission line towers, considering the multi-wave impedance model. First, the actual lightning strike process is analyzed, which indicates that after the lightning current is divided and dissipated by the tower and lightning conductor, the current entering the ground differs significantly from the original lightning current. This clarifies the necessity of constructing an integrated model of “transmission line - tower - grounding device”. Based on the multi-wave impedance theory, the T.Hara equivalent distributed line model is adopted to establish the tower transient model. Through segmented comparative simulation, it is determined that 8 segments represent the optimal segmentation scheme (as the potential peak tends to saturate). A full-scale field test is carried out on the 220-HD21S-J1 tower: the impulse grounding resistance is measured by wiring at an angle in accordance with the DL/T266-2012 standard. The results show that the simulation waveform is consistent with the measured waveform in terms of trend, and the error of the impulse grounding resistance is only 5.97%, which verifies the correctness of the proposed model. This study can provide theoretical and experimental support for the lightning protection design of transmission lines.