750kV防冰型复合绝缘子冰闪试验研究

Ice Flashover Test of 750kV Anti-Icing Composite Insulators

复合绝缘子以其优良的耐污闪性能在电力系统中得到广泛应用,然而普通伞形复合绝缘子的伞裙在覆冰情况下很容易被冰棱桥接,覆冰后复合绝缘子的绝缘特性明显下降。近年来,覆冰引起的输电线路和变电站绝缘子闪络事故对电力系统的安全稳定运行造成了严重威胁。国内外对输电线路及变电站覆冰绝缘子的闪络特性进行了大量研究,但大多以短串为主,针对超高压和特高压全尺寸完整串绝缘子的相关研究还比较少。开展了4种不同伞形的750 kV复合绝缘子的冰闪试验,结果表明:复合绝缘子加超大伞后,绝缘子的覆冰过程和最终覆冰状态不同,加装7,9,10个超大防冰伞复合绝缘子的闪络电压较普通型的分别高12.3%、25.8%、27.7%;冰闪电压随着防冰伞数量的增加呈上升且逐渐饱和的趋势,750 kV线路复合绝缘子的防覆冰伞形优化需选择合理的防冰伞裙间距离。

Composite insulator has been widely used in power system due to its excellent flashover endurance capability, but the common umbrella-type composite insulator is easily been bridged in icing condition, and the insulating properties of iced composite insulator decrease obviously. In recent years, the flashover accidents of transmission lines and substation insulators caused by icing have been a serious threat to the safe and stable operation of power system. A lot of work has been done on the flashover characteristics of iced composite insulators in China and abroad, but most tests are focused on short strings. Only few researches on EHV and UHV full-size complete string insulator. This paper carried out icing flashover tests for four 750 kV composite insulators with different umbrella-types. The results show that the icing process and final icing status are different after adding large umbrella to composite insulator; the flashover voltage of composite insulators with 7/9/ 10 large anti-icing umbrellas is 12. 3%, 25.8% and 27.7% higher than that of standard composite insulatorsm, respectively. The flashover voltage increases along with the number increase of anti-icing umbrellas, while has a saturated trend. The anti-icing umbrella optimization of 750 kV composite insulators should choose a reasonable anti-icing distance.