不同湿度下低值瓷质绝缘子的发热特性

Heating Characteristics of Deteriorated Porcelain Insulator Under Different Humidities

绝缘子串中劣化低值绝缘子对电网的安全运行构成了潜在的隐患。以瓷质绝缘子为试品,利用红外成像技术重点分析了不同阻值的低值绝缘子在不同相对湿度、不同位置条件下对检测的影响;并提取数据绘制了温升曲线,研究了其发热规律,最后通过Comsol有限元分析法进行了模拟仿真。实验结果表明：低值绝缘子位于绝缘子串高压端时易于检测,阻值较大的低值绝缘子位于串中部或接地端时易漏检;劣化绝缘子的温升幅度与阻值大小并不成线型规律变化,阻值为30 M？左右时发热最大;污秽等级为I级,相对湿度在70%～80%时,绝缘子发热最大,相对湿度〉90%时,劣化绝缘子温升有所下降,会致使误检或漏检的发生。

Deteriorated insulators among strings potentially threaten the safety of power grid. Consequently, taking porcelain insulators as objectives, and utilizing infrared thermograph,we studied the influences of defective insulators of different impedance located on different positions of the strings under various relative humidity on detection. The thermal statics of insulator strings were subtracted and then plotted, heating patterns of defective strings were studied, and the simulation of the above was made by a finite element analysis software Comsol. The experimental results show that the deteriorated insulators at the high voltage position of the string are more easy to be detected, and deteriorated insulators of large impedance on zero voltage position or middle of the strings may lead to false examining. The relationship between temperature rise and its impedance is nonlinear, and the rise reaches its maximum when the impedance is 30 M？. Under Icontamination level, temperature rise will reach maximum when relative humidity variesfrom 70% to 80%, and temperature rise of the deteriorated insulators will decrease when relative humidity ascends to 90%, which may cause error in detecting.