直流覆冰绝缘子电气特性及伞裙结构抗冰性能优化研究

Electrical Characteristics of DC Ice-Covered Insulators and Anti-Icing Function Optimization of Shed Structure

根据绝缘子局部放电机理对动态直流局部电弧数学模型进行了改进,并基于此数学模型,计算了在不同电压下覆冰绝缘子表面局部电弧状态及其泄漏电流,电弧温度等参数。并结合实验,对覆冰绝缘子在不同等级电压作用下的电气特性进行了分析。在此基础上,对FXBW4 110/100型绝缘子的伞裙结构进行改进,计算了其在改进后相同覆冰情况下的闪络电压。并根据计算数据总结研究了导致其闪络电压改变的主要因素。研究结果表明,覆冰绝缘子的局部放电起始电压与闪络电压无直接关系,局部放电状态下的绝缘子通常可以正常工作,且会因局部电弧对冰棱存在加热效应导致冰棱融化断裂,最终覆冰绝缘子会因冰棱大量断裂不满足局部放电条件而熄弧。气隙长度对覆冰绝缘子的闪络电压影响不大,但其气隙数量对闪络电压有很大影响。气隙出现后,维持局部放电需要有局部电弧将气隙与冰面桥接,从而产生狭窄的弧根,导致整个回路剩余电阻增加。根据研究结果,本研究提出绝缘子的防冰设计理念,既易实施,又能有效提升绝缘子的防冰闪性能。

Based on a dynamic DC partial arc mathematical model improved by the partial discharge mechanism of insulator,calculations on parameters of partial arc state,leakage current,and arc temperature on the surface of the ice-covered insulator under different voltages have been made in this paper.The electrical characteristics of the ice-covered insulator under different grades of voltage has been analyzed with the help of experiments. Based on these analyses,the shed shape of the FXBW4 110/100 insulator is altered and its flashover voltage comparing with unaltered insulator under the same ice-covered state is calculated. The primary factors causing the changes of flashover voltage is summarized by using the data which has been calculated. The results show that the ice-covered insulator’s arc striking voltage has no direct relevance to its flashover voltage. In general,the insulator can work normally after the partial arc occurring. The icicles would be melted by the heat originating from the partial arc and then break off. In the end,the arc on the ice-covered insulator would be extinguished as substantial amount of icicle crack leading to an insufficient condition for arc striking. It is not the length,but the number of air gaps,which has great influence on the flashover voltage of ice-covered insulator. After the occurring of air gaps,for keeping partial discharging,the partial arcs are needed as bridges to connect the air gaps and the ice surface. This would produce narrow arc roots which would result in the increasing of the residual electric resistance in the whole circuit. According to the research results,an anti-icing scheme for the insulator is proposed,which is easy to implement and can effectively improve the anti-ice-flashover performance.