Lightning Impulse Impedance and Surface Potential Distribution of 10 kV Distribution Line Tower: Field Test and Simulation

The impulse grounding performance of distribution lines tower is the key factor to lightning protection. Few field high-current impulse test researches are conducted on distribution line tower. In this paper, we used a mobile high-current impulse generator to conduct test on a 10 kV distribution line tower. The peak value of the current injection is 6 kA to 16 kA. The impulse impedance and the surface potential distribution are measured and analyzed. Based on the CDEGS software, an equivalent modeling of the experiment was carried out. The influence of soil ionization was taken into account by the method of changing the conductor radius through two rounds of calculation. The simulation and measured results were basically consistent. Experiments have shown that the soil ionization effect has an important impact on lightning performance of distribution line tower. The graphite earthing modules (GEMs) and pulling wires can significantly reduce the impulse impedance of the tower. The potential rise of the earth surface at a distance of 30 m from the tower can reach 1 kV at peak, under an injection of 7.15 kA.

I. Introduction

Lightning impulse performance of grounding devices is important for lightning protection of transmission and distribution lines [1]–[3]. Lightning current has the characteristics of high amplitude, steep front and short duration. The inductive effect of grounding conductors and soil ionization often have a significant impact on impulse grounding research [4]–[7]. The potential rise of the grounding down-conductor and the uneven distribution of the ground potential during the lightning will produce a high transient touch/step voltage, which threatens the safety of humans and animals around.