多串并联绝缘子交直流污闪特性

AC and DC Pollution Flashover Performance of Multiple Parallel Suspension Insulators

特高压等级线路中为满足机械特性的需要而应用到多串并联形式的绝缘子串。为此,分别在交流和直流电压下通过人工污秽试验研究了多串并联绝缘子的污闪特性,试验中分别采用了2联、3联、4联以及6联的结构。试验结果表明,多串并联绝缘子的污闪电压比单串低,其原因除了绝缘子并联串数的增加导致其污闪概率的升高外,还受到并联串间放电产生的电离空气的影响。并联数<4时,多串并联绝缘子的污闪电压比单串降低约4%;并联数≥4时,污闪电压降低超过10%。建议在实际工程中使用多串并联的形式时,将瓷绝缘子的片数在原基础上增加8%,复合绝缘子的串长增加5%。研究结论可为特高压输电线路外绝缘的设计与建设提供参考。

Multiple parallel suspension insulators are applied in UHV lines to meet some mechanical requirements. Hence we investigated the pollution flashover performance of multiple parallel insulators by means of artificial contamination tests under both AC and DC voltages. The tests were performed using two-string, three-string, four-string, and six-string parallel insulators. The results show that pollution flashover voltages of multiple parallel insulators are lower than those of single insulator strings. This is because not only that multiple strings increase the pollution flashover probability, but also that they are affected by the ionization of air. When the parallel number is less than four, pollution flashover voltage is about 4% lower than that of a single string, and if the parallel number is no less than four, the flashover voltage can be reduced by more than 10%. Hence, it is suggested that in applications of multiple parallel insulators, the number of porcelain insulators should be increased by 8% from the original value, and the insulation length of composite insulator should be increased by 5%. The conclusion of this work can provide a technical reference for external insulation design and construction of UHV transmission lines.