Analysis and mitigation techniques of overvoltages due to insulator transient arcs clearing on a 500 kV OHTL

Abstract

In high-voltage OHTL, Overvoltages and arc currents due to insulator transient arcs clearing severely affect the stability of power systems.In this paper, a 500 kV Egyptian OHTL was simulated using ATP-EMTP software package. The insulators transient arcs clearing of the system were tested under different impedances of tower footing, locations of insulator arc tower, angles at which the arc initiate. Additionally, the effects of the corona phenomenon were taken into account to achieve realistic study. Furthermore, these factors thoroughly were analyzed to determine worst-case scenarios. Also the paper evaluated the performance of the overvoltage mitigation methods based on the installation of neutral shunt reactors, MOSA (Metal Oxide Surge Arresters), or combinations of both.The results demonstrated that the combination of MOSA and neutral shunt reactors was the most effective mitigation technique, reducing overvoltages by approximately 57.4 %, arc currents by 80 %, and arc extinction time by 27.3 %Notably, the most severe overvoltages and peak arc currents occurred at an angle of θ = 180° and footing impedance 30Ω. Additionally, the corona phenomenon played a role in reducing the severity of overvoltages, arc currents, and arc extinction time by approximately 56 %, 56 %, and 1.8 %, respectively. Finally, These findings provide valuable recommendations for mitigating overvoltages, arc currents, and arc extinction time during insulator arc clearing events.