Effects of Transmission Line Faults on Electric Field Distribution Nearby

Based on the electromagnetic simulation software Ansoft, a high-voltage AC transmission line model with sag is established to investigate the effects of transmission line faults on the nearby electric field and the electric field distribution near the top of objects. Through the changes of various faults, the distortions of electric field near the high-voltage AC transmission line caused by single-phase grounding fault, two-phase grounding short-circuit fault, two-phase short-circuit fault, and three-phase short-circuit fault are compared and analyzed. On this basis, a model containing trees and buildings is constructed to analyze the changes of electric field intensity around trees and buildings after various faults occur. The results show that the electric field characteristics generated by different faults on the transmission line are obviously different. The maximum electric field intensity near the line after the faults does not exceed the maximum electric field intensity before the faults; different faults have different degrees of influrnce on the maximum intensity and amplitude of electric field around the line, and some faults even have "zero points". The feasibility of using the change of the electric field to diagnose operating state of the high-voltage transmission line is verified. In addition, after faults, the electric field intensity surrounding the tops of trees and buildings greatly increases, especially when a two-phase short-circuit fault occurs, the maximum intensity at the top of trees is close to 3.81 times of the normal value, and the maximum intensity near the top of the buildings is close to 7.15 times of the normal one, which is more likely to cause corona discharge. This study may provide reference for transmission line design, fault diagnosis, and green development of power grid in the future. © 2021, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.