SF_(6)直流穿墙套管金属微粒产生过程模拟及沿面闪络特性研究

Simulation of Metal Particles Generation Process in SF_(6)DC Wall Bushing and Experimental Study of Flashover Characteristics

穿墙套管是特高压直流输电工程中不可替代的关键装备。在SF_(6)气体绝缘直流穿墙套管内,部件间的相互摩擦会产生大量金属微粒,这是引发其内绝缘失效的主要原因之一。因此,研究金属微粒的产生过程和形貌特征,进而研究其对闪络的影响具有重要意义。该文计算某特高压工程中昼夜温差与风致振动工况下触指的振动幅值和频率,开展触指磨损实验,基于磨损产物进行金属微粒吸附实验以及闪络电压测量实验。结果表明:脉动风作用下的触指磨损程度较大,是金属微粒的主要来源;在粘着磨损以及磨粒磨损的耦合作用下,产生的微粒基本处于微米级,材料包括铝、银、锌和铜,大微粒多为片状,小微粒多为椭球状;在库仑力的作用下,微粒主要在绝缘支柱法向电场较大的表面吸附;附着微米级金属微粒可以使得环氧闪络电压下降20%。该研究结果可为金属微粒对绝缘特性影响的研究提供选型参考。

Wall bushing is one of the irreplaceable key equipment in the ultra-high voltage direct current(UHVDC)transmission project.In SF_(6)gas-insulated DC wall bushing,the friction between components will produce a great quantity of metal particles,which is one of the main reasons for the insulation failure.Therefore,it is of great significance to study the generation process and morphology characteristics of metal particles,and to study their influence on flashover.In this paper,the vibration amplitude and frequency of the spring under the conditions of temperature change and wind-induced vibration in a certain UHV project are calculated.The results show that the wear degree of the contact under fluctuating wind is greater,which is the main source of metal particles.Under the coupling effect of adhesive wear and abrasive wear,the particles are basically in the micron scale,which includes Al,Zn,Ag,and Cu,and the big particles are chip-shape while the small ones are ellipsoid-shape.Under the effect of Coulomb force,the particles mainly adhere on the epoxy surface with stronger normal electric field.The micron metal particles can reduce the epoxy flashover voltage by 20%.This work can provide a reference for the further study of the influence of metal particles on insulation characteristics.