A Novel Lightning Strike Response Simulation Method for Transmission Lines Considering Transient Grounding Resistance

The transient grounding resistance of a grounding device may change rapidly when a power transmission line is struck by lightning. The value of the grounding resistance can affect the simulation results of lightning response in power transmission lines, which can create difficulties in lightning protection design. This article proposes an electromagnetic transient program (EMTP) modeling method that considers transient grounding resistance. First, an initial EMTP model of the power transmission line is established. Then, the critical breakdown field strength of the soil is measured. Next, the measurement results are incorporated into a finite element simulation model of the grounding device. Finally, a particle swarm optimization (PSO) algorithm is used to fit the formula for calculating the transient grounding resistance, and it is incorporated into the initial model. Additionally, the accuracy of the proposed simulation model was validated through multiple on-site experiments, with errors within 5%, which is better than conventional modeling methods; furthermore, based on the proposed simulation model, an analysis of different soil critical breakdown field strengths and grounding device types was conducted, and a comparison of the calculation results between this article's method and conventional methods was made. The research results of this article can provide a reference for high-precision modeling of power transmission lines and guide lightning protection design.