工频恒定电压下SF6气体中沿面放电发展过程研究

Development process of surface discharge in the SF6 gas under constant voltage of power frequency

气体绝缘组合电器(GIS)中绝缘缺陷的存在会造成局部放电,导致设备劣化,进而危害到电力系统的稳定性。其中危害较严重的为绝缘子沿面放电缺陷,为探究其在工频恒定电压作用下的放电发展过程及规律,文中制作了“三结合”模型模拟SF 6中沿面放电缺陷并展开试验。保持工频电压在模型闪络电压的95%不变,每隔5 min记录一次局部放电信号,直至模型频繁发生闪络,分析各阶段放电统计参量的变化。结果表明沿面模型在闪络前的放电呈现放电重复率增加、放电量增加、放电间歇、放电再次增强的发展过程。放电间歇的产生与SF 6的强电负性、电场均匀化等均有一定关系。因此,需通过长时间放电检测以准确判定设备劣化阶段,并采取相应措施。

In the gas insulated switchgear(GIS),the existence of insulation defects will cause partial discharge,which results in degradation of the equipment and endangers the stability of the power system.The defect of surface discharge along the insulator is relatively severe among all kinds of insulation defects.In order to study the discharge development process and regularity of this kind of defect under constant power frequency voltage,this paper sets up a"triple-combination"model to simulate the surface discharge in SF6.With the power frequency voltage kept unchanged at 95% of the flashover voltage,a set of partial discharge signal is recorded every 5 minutes until the flashover occurs frequently,and the statistical parameters of each stage is calculated.The results show that before flashover,the discharge development process of the surface model follows the sequence of the increase of discharge repetition rate,the increase of the discharge quantity,the intermittence of discharge and the rising of discharge again,and at last the flashover happens.The occurrence of discharge intermittence may have relationship with the strong electronegativity of SF6,the uniformity of the electric field and so on.Therefore,long-term discharge detection is required to accurately determine the stage of equipment degradation,and measures should be taken accordingly.