Influence of UHV DC Transmission Line Arrester on Electric Field Distribution of Composite Insulator

Abstract

According to the typical tower structure of ±800 kV UHV DC transmission line, considering the influence of several factors including the tower, bundle conductor, grading ring, and dielectric as well as conductivity of ZnO varistor, the calculation of the impact of ±800 kV DC line arrester and its novel installation method on the composite insulator string, grading ring electric potential and field strength distribution have been done comparatively via the three-dimensional finite element method of the electrostatic field. Research indicates that the arrester slightly increases the maximum value of the potential and electric field strength of the composite insulator string. The arrester also makes the uniformity of the distribution of the electric potential and field strength along the composite insulator slightly reduced, but the impact is rather small. On the other hand, the arrester reduces the surface field strength of the grading ring on the side of the cross arm and increases the surface field strength of the grading ring on the conductor side, but the maximum electric field strength is far below the limit. Analysis indicates that the impact of the arrester on the electric field distribution of the insulator string can be neglected.