Study on Pollution Flashover Performance of Short Samples of Composite Insulators Intended for /spl plusmn/800 kV UHV DC

Abstract

Based on the artificial pollution tests, the effects of pollution and high altitude on the flashover performance of short samples of five kinds of UHV/EHV dc composite long rod insulators are analyzed. The exponent characterizing the influence of salt deposit density on the flashover voltage is related with the profile and the material of the insulator shed. The values of the samples' exponents vary between 0.24 and 0.30, which are smaller than those of porcelain or glass cap-and-pin insulators, namely, the influence of the pollution on the composite long rod insulators is less, relatively. Thus, the composite insulators have certain advantages in severe pollution regions. The best ratio of the leakage distance to the arcing distance is about 3.35. The exponent characterizing the influence of air pressure on the flashover voltage is related with the profile and the material of the insulator shed and the pollution severity, the values of the samples' exponents vary between 0.6 and 0.8, which are larger than those of porcelain or glass cap-and-pin insulators. Therefore, the dc composite insulator used in high altitude regions should have enough arcing distance. Based on the test results, if insulator sample Type E is selected for the ±800 kV UHV dc transmission lines, the basic arcing distance should be no less than 8.16 m and the basic leakage distance no less than 30.2 m.

AC pollution flashover circuit model for composite insulator based on multiple arcs series

“…Fifty per cent flashover voltage U 50% was determined by the up-and-down method and the voltage step was 10% of the expected U 50% . Since there is a relative standard error s% between the U 50% and the flashover voltage U f , the flashover voltage U f can be expressed as [36]:…”

Effects of Non-uniform Pollution on the AC Flashover Performance of Suspension Insulators

“…The artificial climate chamber, with a diameter of 7.8 m and a height of 11.6 m, can simulate complex atmospheric environments such as fog, rain, ice and high altitude [13][14][15][16]. The power was supplied by the AC voltage test set (YDTW) -500 kV/ 2000 kVA pollution test transformer, of which the maximum short current is 75…”

“…Thus some researches were conducted to discuss the performance of non-uniform contamination on top and bottom surfaces, as well as its influence on insulator flashover [4][5][6][7][8][9][10][11][12][13][14][15][16].…”

Preliminary Study on the Drawing of the Electronic Polluting Area Map

“…The surface contamination and moisture of insulators, which is largely used in power system, seriously affects the electrical properties of insulators, brings the risk of grid flashover accidents, and endangers the safe operation of power grid [1][2][3]. Currently, pollution flashover accident is one of the main factors of electric power accidents in China.…”