Research on Electrical Safety of Live-line Work of Ground Wire for UHV/EHV Transmission Line Based on Helicopter Winch Method

Helicopter winch method has the advantages of flexible operation, convenience and efficiency, and high safety. In order to solve the difficulties in the maintenance of conventional overhead ground wire, the helicopter winch method can be applied to the live maintenance of overhead ground wire. In this paper, the electrical safety and protective measures for ground wire repair for UHV/EHV transmission line based on the helicopter winch method are studied. The minimum safety distance and the minimum combined clearance are obtained by carrying out switching impulse discharge test for live working gap under the typical working conditions. To ensure the safety of the helicopter body and live workers, the induced electricity characteristics of overhead ground wire for UHV/EHV transmission line are analyzed, and the minimum effective insulation length of insulated rope for hanging maintenance workers and safety protection measures are studied. Finally, the field application of helicopter winch method for live-line work of ground wire has been successfully carried out, which proves the feasibility, safety and efficiency of helicopter winch method, and lays a foundation for the promotion and application of this maintenance method.

I. Introduction

Under the target vision of “double carbon”, the adoption of ultra-high voltage, large capacity and long-distance transmission is the key way to solve the cross-regional energy demand, and the safe and stable operation of transmission lines is an important guarantee for the realization of sustainable and reliable power transmission. Overhead ground wire is a vital part of high-voltage transmission line structure, which can effectively prevent lightning from striking the transmission line. Besides, the optical ground wire (OPGW) has both lightning protection and communication functions, and is widely used in the power grid. In the normal operation process, the overhead ground wire will inevitably suffer various damages[1]–[4], mainly manifested as different degrees of broken strands. If the ground wire damages are not eliminated in time, it may affect the safety of the line operation and even cause major accidents.