Electric Field Distribution Calculation and Analysis of Composite Insulators Operating on Double Circuit Transposition Tower in 500kV Transmission Lines

Transposition tower is generally used in AC transmission line to change the configuration of conductors and mitigate the imbalance of voltage and current. Due to the special conductor configurations, the composite insulators on transposition tower are more likely to be damaged when compared with those on ordinary transmission tower. In this paper, a full-scale three-dimensional simulation model of double circuit transposition tower used in 500 kV transmission lines was built and the finite element method was used to compute the electric field distribution along composite insulators considering the effects of tower, conductor configurations, grading rings, fittings and phase interaction. The regularity of electric field distribution on the surface of composite insulators was researched and the differences between transposition tower and ordinary transmission tower were presented in simulation results. At last, some suggestions were provided to optimize electric field distribution and extend service life of composite insulators on transposition tower in this paper.