Electric field calculations on outdoor insulators including the effect of arc jumping

Summary

Insulator flashover could interrupt the power transmission by causing line to ground fault. Flashover consists of arc tracks from insulator high voltage electrode to ground electrode. Therefore arc propagation around the insulator is a serious issue to insulation systems, especially if the insulator is covered by a pollution layer. Most existing arc propagation models simulate arc tracks along the insulator leakage distance. However arc propagation is a stochastic process rather than a deterministic one in reality. This paper proposes a statistical arc propagation model based on random walk theory and electric field distribution. Arc initialization and propagation occur when electric field applied across the insulating substance exceeds the threshold dielectric strength, thus electric field distribution around the insulator is able to determine the initial point and direction of arc propagation. Self-adaptive grid finite difference method is developed to calculate the field distribution and improve the computational efficiency. Shed-to-shed arc jumping phenomena could shorten the leakage distance and intensify the electric field during arc propagation process. The average probabilities of arc jumping are presented in the paper to demonstrate arc jumping is the major factor to cause flashover. Instantaneous electric field distributions with and without arc jumping are compared to conclude that electric field distribution and arc jumping have mutual facilitation effects on each other. A consecutive of arc jumping phenomena constitute the conductive path and lead to flashover. Arc propagation model and electric field calculations are programmed on MATLAB platform and can be easily modified according to arc and insulator structures as the source code is completely accessible.

Additional informations

Authors

MITSUI

Keywords

Electric Field Calculation, Insulators, Flashover Probability, Arc Jumping, Random Walk