Electric field characteristics of UHV DC tension string during insulator replacement by two workers

Abstract

The UHV DC tension insulator strings are often large-tonnage suspension porcelain or glass insulators with high mechanical strength. The single insulator is heavy, so two workers working at the same time are required to make a replacement on insulator strings in live working conditions. One of the key problems that must be solved in live working conditions is to select an appropriate way to reach the working position and realize the potential transfer between two workers. In this paper, the electric field calculation model of live working of ±800 kV tension strings was established. The process that two workers enter and leave the working position along the tension string and different conditions that two workers replace insulators were simulated and analyzed, and distribution characteristics of the electric field of insulator strings and live workers were obtained. According to the calculation results, when the two workers replace the tension insulators in different tension strings, it is easy to realize the potential transfer, so as to reach the same potential for work. The study results of this paper provide a basis for the selection of replacement method of large-tonnage single insulator by two workers, and a theoretical basis for UHV DC live working.

Key technology of replacing insulators for 500kV transmission line with electric operation

“…However, the tower window clearance of the 500kV compact same tower double circuit line is much smaller than the conventional one, the phase spacing is smaller, the movable channel for the operator is limited, the surrounding electric field intensity of the equipotential operator in the tower window is higher than that in the conventional line, and the minimum safety distance condition must be satisfied for the charged operation. Moreover, the jumper of the inner upper-phase conductor of the tension-resistant tower is placed above the upper-phase conductor cross-arm, which is different from the jumper arrangement of the tension-resistant tower of the conventional 500kV line [4] . Conventional 500kV line with electric replacement of insulators is not necessarily applicable to 500kV compact same-tower double-circuit transmission lines.…”