特高压直流套管气-固界面长时闪络放电特性及其影响因素

Long-time Flashover Discharge Characteristics of Gas-solid Interface of UHVDC Bushing and its Influencing Factors

胶浸纸(resin-impregnated paper,RIP)干式套管内部的SF_(6)气体与环氧树脂浸纸电容芯体组成的气-固界面是套管内部易发生放电的绝缘薄弱点。该文搭建闪络放电特性实验平台,测试套管环氧浸纸试样和芯体模型在不同表面状态、微粒影响下的表面电荷分布,揭示多种因素对表面电场及闪络特性的影响机制。同时,对套管芯体缺陷试样长时局部放电至闪络放电发展过程进行试验验证。结果表明:高压侧区域套管气-固界面存在高分散性的纤维凸起,运行过程中吸附微粒,在直流电压作用下电荷积聚和电场畸变引发微弱起始局部放电;长期的电压作用使电荷积聚加剧,电场畸变程度进一步增大,局部放电频次和幅值逐步增加,最终导致贯穿性闪络放电。该研究可为胶浸纸套管芯子表面处理工艺的优化,以及长期直流下闪络放电的抑制措施的制定提供理论和实验依据。

The gas-solid interface between SF_(6) gas and the epoxy resin-impregnated paper capacitor core inside the resin-impregnated paper bushing(RIP Bushing)is the weak point of insulation inside the bushing where discharges are likely to occur.In order to study the long-time flashover discharge characteristics and its influencing factors at the gas-solid insulation interface inside the dry-type bushing,we build an experimental platform for flashover characteristics,and test the surface charge distribution of epoxy-impregnated paper specimens under the influence of different surface states and particles,revealing the influence mechanism of various factors on the surface electric field and flashover characteristics.At the same time,a long-time pressurization experiment is conducted to obtain the discharge characteristics by manufacturing defects core specimens.The results show that there are highly dispersed fiber protrusions at the gas-solid interface of the bushing in the high-voltage side area,in which particles can be easily attracted during operation.Under the action of DC voltage,charge accumulation and electric field distortion will cause weak initial partial discharge.Besides,the long-term voltage action intensifies the charge accumulation,further increases the degree of electric field distortion,gradually increases the frequency and amplitude of PD,and eventually leads to penetrating flashover discharge.The research results can provide theoretical and experimental basis for optimization of the surface treatment process of the resin-impregnated paper bushing capacitor core and the formulation of the suppression measures for flashover discharge under long-term direct current.