Study On Pollution And Ice AC Flashover Characteristics Of Inverted T Type Insulators String

The insulation degradation is an important factor leading to grid fault under pollution and icing weather conditions.And a reasonable arrangement of insulator strings is one of the effective ways to improve the pollution flashover voltage and the ice flashover voltage of transmission lines.At present,the arrangement of insulator strings at home and abroad mainly adopts common suspension string,horizontal string,V string and Y string.But it has not researched the inverted T string with both suspension string and horizontal string's advantages.Based on the research results at home and abroad and combined with the actual problems in transmission lines,this paper has studied the pollution and icing flashover characteristics and flashover process of the inverted T insulators string in the large-scale multi-functional artificial climate chamber using XP-160 and LXY-160.According to the pollution experiments,it can be found that the pollution flashover voltage and the equivalent salt density of the inverted T type insulator string satisfy negative power function,and with the increasing of the equivalent salt,the flashover voltage decreases gradually.Compared with the suspension string,the pollution flashover voltage of the inverted T type insulator string has obviously improved.For“2+2”type,the improvement of XP-160 is 11.13%and LXY-160 is 13.14%;for“3+3”type,the improvement of XP-160 is 12.00%and LXY-160 is 12.28%;for“7+2”type,the improvement of XP-160 is 6.12%and LXY-160 is 6.91%.Compared the flashover process of different arrangement,flashover process has some difference.In suspension string,the local arc is first produced and developed at high voltage end and the partial arc at high voltage end is developing rapidly and the discharge degree is fierce.In inverted T type insulator string,the local arc is first produced and developed at low voltage end.And the partial arc at high voltage end is developing slowly and the discharge degree is weak.According to the icing experiments,it can be found that the ice flashover voltage(U_mf)and the equivalent salt density?ESDD?of the inverted T type insulator string satisfy negative power function,and with the increasing of the density of the equivalent salt,the flashover voltage decreases gradually.With the increase of icing degree,the ice flashover voltage of the inverted T insulator string is also gradually reduced,and the relationship between the flashover voltage and the ice thickness of the rotating conductor satisfies the negative power function relationship.Compared with the suspension string,the ice flashover voltage of the inverted T type insulator string has obviously improved,about 6.21%⁹.69%,and with the increasing of the icing degree,the improvement also increases.Compared the flashover process of two arrangement,flashover process have some difference.In suspension string,the local arc is first produced and developed at high voltage end and the partial arc at high voltage end is developing rapidly and the discharge degree is fierce.In inverted T type insulator string,the local arc is first produced and developed in the end of the suspension part.The partial arc at high voltage end is developing slowly and the discharge degree is weak.And it's rare to find the arc connection insulators at high voltage end so the leakage distance of insulators can be effectively used.The thesis has shown that the pollution and ice flashover voltage of inverted T sting have improved compared with the suspension string.Moreover,inverted T sting also have advantages in the process of fouling.So if the transmission line adopt inverted T type insulators string,the occurrence of flashover accidents can be reduced and the reliability of power supply can be improved.