Study on Lightning Withstand Level and Induced Voltage after Insulation Reconstruction of Overhead Ground Wire

Abstract

Large current ice-melting method is one of the most effective measures to prevent ice-covered disasters on overhead ground wires. In conventional wiring mode, the ground wire is directly connected to the transmission line tower, and the ice-melting circuit loop cannot be formed, so large current ice-melting is hard to be achieved. Therefore, the ground wire must be insulated to meet the demands of ice-melting. After the insulation reconstruction, the original wiring form of ground wire has been changed. The reconstruction has influenced on lightning protection performance and induced voltage of ground wires. In this paper, the corresponding simulation model is established in the Alternative Transients Program Electro-Magnetic Transient Program (ATP-EMTP). The researches have been made on the impacts of insulation segment length and grounding method on the lightning-withstand level. Meantime, the influence on induced voltage of the transmission lines has also been studied. The results indicate that insulation reconstruction has no significant effect on lightning shielding failure. And the length of reconstructed insulation segment has no significant effect on strike-back lightning-withstand level. The length of reconstructed insulation segment should be determined by the amplitude of induced voltage. When setting the midpoint of the insulation segment as grounding point of common ground wire, and applying Optical Fiber Composite Overhead Ground Wire (OPGW) two-point grounding, the lightning-withstand level of the transmission line can be effectively improved. Meantime the amplitude of induced voltage obviously decreases. The simulation results in this paper can provide references for insulation reconstruction design of overhead ground wires in the transmission lines.