绝缘子在户外的表面污秽成分十分复杂,绝缘子表面电导特性和污闪电压在不同污秽成分的影响下有明显差异.选取4种典型污秽成分进行了试验研究,对比测量了涂刷不同污秽成分的绝缘子表面泄漏电流和闪络电压,获得了污秽成分对绝缘子泄漏电流特性和闪络电压的影响特性.试验表明,绝缘子泄漏电流最大值随着湿度和可溶性物质附着密度(SCD)的增加而增加,不同污秽成分在SCD较小时,区分度不高.绝缘子的闪络电压主要与可溶污秽成分的电导率、溶解度、电离特性和不溶污秽的成分组成以及它们相互间的影响有关.不同单种无机盐污秽成分的绝缘子闪络电压由低到高依次为:NaCl、NaNO3、MgSO4、CaSO4.不同混合无机盐污秽的绝缘子闪络电压均随着混合污秽中所含CaSO4质量分数的增加呈上升趋势.

为实现基于边缘检测的悬式绝缘子放电日盲紫外成像智能评估,论文搭建了悬式绝缘子污秽放电试验平台,获得了相对光斑面积等紫外参数并提出了放电严重程度判据,建立了不同放电程度的紫外图像样本数据库;采用改进的SSD模型对紫外放电视频流进行训练,实现了模型参数缩减以及训练收敛速度的提升.研究结果表明:采用改进后的SSD模型对放电图像进行训练,模型文件大小为4.5MB,具有良好的嵌入式检测性能;在模型训练过程中,设计了 自主更新学习率机制,使得模型的收敛速度提升约3.5倍,收敛值降低1/2.可将绝缘子的放电严重程度智能评估为"slight"、"moderate"、"heavy"、"worse"四个等级,论文的研究成果为边缘侧基于紫外成像的电力设备放电严重程度的实时评估提供了新思路.

鸟巢类故障是涉鸟故障中造成输电线路跳闸的主要原因之一,为研究巢材闪络与雨水的电导率、巢材的长度及其空间位置等因素的关系,论文测量了不同种类及湿度下巢材的电阻,研究了影响巢材导电性能的因素;模拟巢材在杆塔上的情况,研究了导线-杆塔间隙中有巢材时的闪络特性;建立了 110 kV酒杯型杆塔边相的三维仿真模型,研究了巢材对空气间隙电场畸变的影响.结果表明:喷淋在巢材上的雨水模拟液电导率越大,其在固定间隙距离下的间隙击穿电压和击穿场强越小;严重情况下,巢材与均压环的击穿平均场强为3.96kV/cm,可以等效为棒-棒间隙的击穿过程.论文研究结论可为输电线路鸟巢类故障防治和闪络预警提供一定的参考依据.

In order to study the discharge phenomena of plastic film overlapping on UHV DC transmission lines and explore the cause of flashover fault of a ± 800 kV UHV line, an experimental study is conducted on the flashover characteristics of plastic film with three different gap distances of 1.0 m, 2.0 m and 11.5 m, and the relationship between flashover voltage and plastic states, including dry and wet state, spreading and rolling state, is studied through analyzing the equivalent salt density of three typical areas on the surface of plastic film. The results show that, when the gap distance is 1.0 m and 2.0 m, the gap flashover potential gradients of wet plastic film are 1.22 kV/cm, 0.96 kV/cm, 0.82 kV/cm and 0.7 kV/cm respectively for the spreading out and rolling up state; When the gap distance is 11.5 m, the gap flashover potential gradient of the wet plastic film is 0.56 kV/cm. Under the condition of moisture, the plastic film in rolling up state is more prone to flashover than that in spreading out state, and the average flashover potential gradient decreases with the increase of gap distance. Finally, the causes for the failed three times of restart of a ± 800 kV UHV line caused by short circuit of plastic film is analyzed.