Voltage and E-field distribution of UHV composite insulator with connection of porcelain insulators

摘要

Composite insulator has advantages in antifouling property, light weight, easy installation and transportation. It has been widely used in 1000kV UHV transmission lines. As the increase of operating voltage, the nonuniformity of potential and electric field distribution on the high voltage end of composite insulator is more serious due to its geometry configure, and the aging problem is easier to occur. Porcelain insulator has higher permittivity and better electrical erosion resistance when compared with composite insulator. Therefore, in order to improve the voltage-sharing and anti-aging performance, this paper proposed a novel configuration scheme of composite insulator with series connection of several porcelain disc insulators for 1000kV AC transmission line. One type of 1000kV suspension composite insulator string was taken as an example. Porcelain disc insulators of different number were installed to the high voltage end respectively, while the length of composite insulator string was decreased in order to guarantee the same total insulation length. The three-dimensional (3D) finite-element method (FEM) models of combined insulator strings were built with software ANSYS. The potential and electric field distributions on the whole insulator string were calculated, and the influence of the number of porcelain disc insulators was analyzed. The grading ring configuration for the whole insulator string was also put forward in order to decrease the surface electric field strength on sheds and fittings of insulators. The analysis result shows that the composite insulator with series connection of several porcelain disc insulators could improve the uniformity of potential and electric field distribution effectively. This research could provide valuable references for application of combined insulator string in the 1000kV UHV AC transmission line.