污秽绝缘子表面局部电弧的发展变化与泄漏电流密切相关。为此,以普通悬式瓷绝缘子XP-70为试品,在人工雾室环境下进行了大量人工污秽试验,研究了污秽绝缘子表面局部电弧与泄漏电流波形特征之间的关系。利用泄漏电流采集装置连续存储了电流波形并利用高速摄影仪同步拍摄了放电过程,详细记录了绝缘子表面的局部放电现象以及泄漏电流的发展变化过程,揭示出局部放电强度与泄漏电流波形类别之间的对应关系;通过提取不同局部放电强度下泄漏电流波形的多个特征量(半波极大值同极小值之比k;波动率为k的电流波形在1s内出现的次数fk;一定时间内fk出现的总次数Ck及fk的最大值fkmax),研究了整个试验过程中各特征量的变化规律以及它们与等值盐密ρESDD之间的关系。研究结果表明,可以根据泄漏电流波形特征初判绝缘子表面的放电程度;根据fk变化规律及局部放电强度,能更加明确地将泄漏电流划分为3个区段即安全区、预报区和危险区;在污秽严重的情况下,fkmax(k〉80)在一定程度上能较好地反映绝缘子的污秽程度和放电强度;Ck(50〈k〈80)与等值盐密值有一定的对应关系。
To study the relationship between surface discharge of insulators surface and leakage current(LC),a series of artificial contamination experiments were conducted in artificial fog chamber by taking porcelain insulators XP-70 as example,and the partial discharge phenomena and development process of insulator surface leakage current were recorded in detail using high-speed camera and LC measurement equipment.The relationship between typical discharge phenomena and their corresponding LC characteristic value is established.Moreover,several LC characteristic values(k is ratio of half-wave maximum and minimum,fk is the number of LC waveforms in one second in different k,Ck is the cumulative number of fk,fkmax is the maximum of fk) in different partial discharge intensity were extracted to study the law of characteristic values and the relationship between they and ρESDD.The results show that insulator surface discharge intensity can be inferred from the LC waveform characteristics,three stages of the whole process of discharge can be clearly divided by fk and intensity of partial discharge,fkmax(k80) can well reflect the pollution degree and discharge strength of insulators and be used as one of important parameters of pre-warning of the pollution flashover when the pollution level is high;Ck(50k80) as a cumulant has a certain relationship with the value of ρESDD.