110kV覆冰绝缘子串交流闪络放电过程研究

受冰冻灾害天气的影响,广东北部的清远、韶关地区多条110kV以上线路受覆冰影响跳闸。为了进一步加深认识覆冰对绝缘子闪络问题,笔者对110kV玻璃绝缘子串覆冰闪络过程进行了细致的研究。考虑到粤北地区绝缘子覆冰的特点,在中国电力科学研究院的人工气候室中,采用绝缘子上下表面均匀覆冰的方式来模拟绝缘子覆冰形貌;并从覆冰绝缘子冰凌的长度、融冰水电导率以及污秽程度等方面研究了融冰期绝缘子覆冰闪络时的放电过程。试验结果表明绝缘子表面的融冰水电导率有明显的盐析效应,使覆冰过程中的融冰水电导率增大,降低闪络电压;无冰凌情况下绝缘子放电过程与污闪类似,有冰凌存在的情况下,放电路径沿未桥接冰凌发展;与没有污秽的情况相比,污秽的存在使闪络过程中放电更加严重。

Study on AC Flashover Process of Iced 110 kV Insulator Strings

As a result of the freezing weather,many 110 kV or higher voltage power lines tripped due to icing in the north of Guangdong Province,such as in Qingyuan and Shaoguan.In order to understand ice flashover performance on insulator strings,the ice flashover process on 110 kV insulator strings was investigate.Taking into account the icing feature of insulator strings in the north area of Guangdong Province,uniform ice layer on both top and bottom surfaces of an insulator was simulated in CEPRI(China Electric Power Research Institute) Artificial Weather Laboratory.More attention was paid to the effect of icicle length on the ice flashover process.And the influences of thawy ice water's conductivity and pollution degree of the insulator on the ice flashover process during ice thawing period were also investigated.The results show that: salt-precipitation in thawy ice water on the surface of insulator significantly increases the conductivity of melting ice to reduce the flashover voltage of the iced insulator string;the ice flashover process of iced insulator string without icicles is similar to that of pollution flashover,while the path of flashover is along the un-bridged icicles with the presence of icicles;pollution leads to more serious flashover.