以电场特征理解电缆终端气隙的局部放电发展机理  

Toward Understanding Development Mechanism of Partial Discharge in Air Gap Defects in Cable Termination by Analysis of Electric Field Characteristics

作　　者：万利[1] 周凯[1] 李旭涛[2] 吴科[1] 

机构地区：[1]四川大学电气信息学院,成都610065 [2]国网宁夏电力公司电力科学研究院,银川750011

出　　处：《高电压技术》2014年第12期3709-3716,共8页High Voltage Engineering

基　　金：国家自然科学基金(51477106)~~

摘　　要：为了研究气隙缺陷导致电缆终端绝缘失效的机理,基于电场分析探讨了终端气隙的局部放电发展过程。建立了终端气隙缺陷的有限元模型并进行了电场理论计算,阐述了气隙对终端电场分布的影响并分析了气隙沿电缆轴向和径向的电场强度特征,讨论了气隙参数与终端气隙内电场强度最大值之间的关系。进而,通过实验终端电热老化实验中的局部放电检测发现,运行条件下终端气隙缺陷放电迅速发展,在不同的老化阶段表现出不同的放电特征。同时,观察老化前后的气隙缺陷发现,老化后气隙内的绝缘毛刺被烧蚀,通道狭长平滑。结合气隙的电场特征分析说明,半导电层截断位置集中的电场导致此处的气隙更容易发生局部放电,而放电表现出的阶段性差异与气隙通道的逐渐贯穿密切相关,通过简化的放电模型可以描述气隙的放电发展机理。In order to investigate the insulation failure mechanism of cable termination caused by air gap defects, the development process of partial discharge（PD） in air gap was investigated based on electric field analysis. A finite element model was established to find out effects of air gap on the electric field distribution of cable termination. Characteristics of electric field strength in the axial and radial direction of air gap were analyzed by finite element simulation. Moreover, relationships between parameters of air gap and the maximum electric field strength were discussed. And then, PDs were measured and analyzed during the process of electrical-thermal aging experiment. The results showed that PD intensified rapidly in the air gap of the tested cable termination and presented different characteristics at different aging stages. In addition, discharge channels were found to be narrow and smooth with the insulation burr ablation in the air gap after the aging experiment. According to analysis of electric field characteristics in air gap, it is indicated that air gap near the cutting position of the outer semi-conducting layer results in PDs. Differences of PDs at different aging stages are related to discharge channels formed in air gap gradually. The development mechanism of partial discharge channels in air gap can be described by a simplified discharge model.

关 键 词：电缆终端 气隙缺陷 有限元仿真 电场分析 局部放电 发展机理 

分 类 号：TM75[电气工程—电力系统及自动化]