Flashover Performance and Process of Suspension Insulator Strings Artificially Covered with Snow

Abstract

Snow accumulates on the surface of insulator string, causing a decrease in its electrical performance, seriously threatening the reliable operation of the power grid. Most previous studies have focused on iced insulators; however, there is a lack of research on snow-covered insulators. In this paper, to reveal the influencing mechanism that snow has on the electrical characteristics of insulator string, based on an artificial snowing test in a chamber, the effects of equivalent salt deposit density, applied voltage type, and snow thickness on the flashover performance of snow-covered insulators are analyzed, and the flashover process is investigated. The results show that the relationship between the arc flashover gradient and the equivalent salt deposit density is a power function with a negative exponent, which is similar to that of polluted and ice-covered insulator strings. For the insulator strings with the same snow accretion, the direct current (DC) arc flashover gradient is lower than the alternating current (AC) arc flashover gradient. The relationship between arc flashover gradient and snow thickness is also a power function. The formation of a dry band during the flashover of snow-covered insulator string is similar to the flashover of the polluted insulator, and the arc propagation along the surface of the snow-covered insulator is similar to the flashover of the iced insulator.

Comparison of AC Flashover Performance of Snow-Accreted Insulators Under Natural and Artificial Simulation Environments

“…(3) However, the variation of flashover gradient with snow thickness is inconsistent with the results of silicone rubber insulators in [13], which is explained as follows. The distance between the adjacent sheds of silicon rubber insulator is much smaller than that of glass insulator.…”

“…Snow accretion on the insulator can be considered as a special type of icing. Hence, the flashover voltage of snowcovered insulators as a function of the ESDD can be depicted by the following equation [13]:…”

“…However, less attention has been paid to the effect of snow accumulation on the external insulation of transmission lines. Hu et al [13] researched the effect of snow accretion on the various type of the insulators in an artificial climate chamber, and arrived at the conclusion that the relationship between the snow flashover gradient of the insulators and equivalent salt deposit density is a power function with a negative exponent. Jiang et al [14] found that the DC flashover voltage of artificial snow-covered insulator is lower than that of the AC.…”

Influence of Crystallization Effect During Icing Water Phase Transition on the Flashover Characteristics of Ice-Covered Insulators

“…On January 24, 2018, an ice-snow storm similar to what happened in 2008 swept most of the power grids in southern China. Failures such as tower collapse, disconnection, and flashover shutdown occurred in many provinces [4]- [6].…”

Influence of snow accretion on arc flashover gradient for various types of insulators

“…In January 2018, a large blizzard similar to that in 2008 once again swept South China, East China and Southwest China. As icing and snowing increased, a series of power failures occurred because of the tower falling down, conductor galloping, line breaking and insulation flashover accidents [8,9]. The recurrence of the ice-snow disaster in 2018 fully demonstrates the uncontrollability of natural disasters and the extreme difficulty of emergency response.…”