高海拔特高压复合支柱绝缘子伞形结构对直流污闪特性的影响（英文）

Study of the Influence of Shed Shapes of UHV Composite Post Insulators on DC Pollution Flashover Performance at High Altitude

为研究高海拔地区伞形结构对复合支柱绝缘子直流污闪特性的影响规律,对4种不同伞形结构的6支复合支柱绝缘子和1支无伞裙结构的复合支柱绝缘子在昆明特高压国家工程实验室进行了大量的直流人工污秽试验,分析了各类试品的爬距有效系数,用紫外放电成像仪对各类试品的局部放电现象进行观测,统计了紫外放电光子数,同时利用高速摄像机观察了不同伞形结构试品沿面电弧的发展情况,并分析了一大一中4小伞形复合支柱绝缘子伞裙参数对直流污闪电压的影响,结果表明:一大两小伞形是4种伞形中最优的伞形结构,该伞形试品的直流污闪电压和爬距有效系数均最高,等径伞伞形最差;各类试品的爬距有效系数随着盐密的增大而有所增加;等径伞伞形试品的紫外局部放电现象严重,电弧桥接现象最明显,导致爬距利用率最低,而大小伞交替伞形不仅紫外局部放电现象较弱,还能较好抑制电弧桥接现象,有效提高爬距利用率;建议在高海拔地区一大一中4小伞形复合支柱绝缘子的爬电系数取3.5左右,相邻伞间距不小于35 mm,但由于一大一中4小伞形相邻伞裙电弧桥接现象严重,即使改变伞裙参数也不能有效提高其直流污闪电压,因此,该伞形不如一大两小伞形。

In this paper, the influence of shed shape on the DC pollution flashover performance of composite post insulator at high attitude areas is studied. Artificial pollution tests were carried out on six composite post insulators with four different shed shapes and one composite post insulator without shed. All experiments were taken place in National Engineering Laboratory of Ultra High Voltage Engineering Technology （Kunming） at high altitude areas （2100m）. The relationship between the utilization coefficient of creepage distance and the shed shape was analyzed. The ultraviolet photons of partial discharge phenomena of samples and the total counts of the ultraviolet photons were characterized with an ultraviolet camera （UVC）. The development path of arcs along the surface was observed using a high speed camera. In addition, the influence of the shed parameters of composite post insulators （with shed shape of alternating large and medium shed and four small sheds （denoted by LMS）） on DC pollution flashover voltage were analyzed. The results showed that the shed shape of alternating large and two small sheds （denoted by LSS） among the four shed shapes was the most optimal one which had the highest DC pollution flashover voltage, most effective coefficient of creepage distance of this shed shape and the lowest shed shape is the same shed overhang （denoted by SS）. The effective coefficient of creepage distance of all specimens was increased with the increment of equivalent salt deposit density （ESDD）. The number of ultraviolet photons of SS shed shape is largest and the phenomenon of arc bridging is the most seriously which leads to the reduction of the utilization coefficient of creepage distance. Therefore, the composite post insulator with the shed shape of alternating large and small shed had less ultraviolet photons, less arc bridging and higher utilization rate of creepage distance. The recommending range of creepagecoefficient for composite post insulator of LMS shed shape is about 3.5 at high altitude areas. The shed spacing between adjacent sheds should be larger than 35 ram. Since the phenomenon of partial arc bridging between adjacent sheds is the most serious, it is difficult for LMS shed shape to improve the pollution flashover voltage by changing its shed parameters Therefore, LSS shed shape outperforms LMS shed shape.