Study on Flashover of Suspension Insulator String Caused by Windage Yaw in 500kV Transmission Lines

In recent years, windage yaw flashover frequently occurs in 500kV transmission lines, and the frequency of such accident exceeds the receivable limit of power system secure operation. The transmission lines designed according to standard are supposed to be secure in practical operation, however, since the second generation of transmission towers for 500kV transmission line are put into operation, the incidence of windage yaw flashover increases year by year, and it is unreasonable theoretically. Starting with the calculation model of windage yaw angle of suspension insulator string for 500kV transmission line, the existing problems in static stress balancing algorithm adopted in windage yaw angle calculation are analyzed in detail, and a modified method for maximum windage yaw angle calculation is given;to determine the least air clearance between tower and conductors, the traditional way estimates it by complex geometrical construction, in this paper by means of leading the two dimensional Descartes coordinate system into tower calculation model the calculation becomes more sententious and convenient, and the calculation accuracy is improved. Finally, detailed analysis on main problems existing in present research on windage yaw phenomenon is conducted.