Abstract
Ice flashover threatens the security and reliability of power transmission. However, the ice flashover mechanism of insulators remains poorly understood. This study analyses water droplet freezing and ion distribution in ice layer under alternating electric field. It also investigates ion migration during icing process of insulator string under alternating electric field and its effects on insulator flashover. Results showed that the average freezing time of water droplets was related to electric field strength. The extent of ion migration during freezing decreased with increasing electric field strength. The maximal melting water conductivity of the ice layer and icicle of the insulator formed under energized condition was higher than the corresponding freezing water conductivity but lower than that under non-energized condition. Furthermore, the hanging location of each insulator significantly affected the melting water conductivity of the ice layer. The surface conductivity of the ice layer increased because of the conductive ion migration in freezing water during freezing, which was an important factor that decreased the flashover voltage of the ice-covered insulator. The existence of alternating electric field would impact the extent of ion migration. This study may serve as a reference for updating prediction flashover model of ice-covered insulators during the melting period.
Highlights
Many countries have suffered from serious icing disasters, which exert a strong impact on power grid [1]
Three units of glass insulator string were used for the icing under the energized condition
The melting water conductivity of the ice layer on No 1 insulator surface changed depending on melting time (Figure 6)
Summary
Many countries have suffered from serious icing disasters, which exert a strong impact on power grid [1]. Experimental investigations and field observations indicated that the flashover of ice-covered insulator string typically occurs during the ice-melting period [6,7,8]. Ion distribution in ice layer and flashover voltage research of ice-covered insulators are affected. To understand duringon freezing under alternating electric field and its impact on insufficient research ion has migration been conducted this area. To understand ion migration during freezing underofalternating electric fieldalternating and its impact on field, the ion distribution in ice layer formed by. NaCl aqueous solution under alternating electric insulator flashover, this study investigated the freezing of water droplets under field, and the distribution extent of ioninmigration insulator string. NaClof aqueous solution alternating electric the influence ion migration on the during flashover an ice-covered insulator. This study analyzed the influence of ion migration on the flashover voltage of an ice-covered insulator
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