SF_6中绝缘子表面电荷积聚及其对直流GIL闪络特性的影响  

Surface Charge Accumulation on Insulators in SF_6 and Its Effects on the Flashover Characteristics of HVDC GIL

作　　者：张博雅[1,2] 王强[1,2] 张贵新[1,2] 李金忠[3] 

机构地区：[1]清华大学电机工程与应用电子技术系,北京100084 [2]清华大学电力系统及发电设备安全控制和仿真国家重点试验室,北京100084 [3]中国电力科学研究院,北京100192

出　　处：《高电压技术》2015年第5期1481-1487,共7页High Voltage Engineering

基　　金：国家重点基础研究发展计划(973计划)(2014CB239502)~~

摘　　要：随着中国特高压直流输电工程建设进程的逐渐加快,直流气体绝缘输电线路(GIL)的需求日益迫切,对GIL在特高压直流下一些关键问题的研究显得至关重要。因此针对直流电压下GIL中盆式绝缘子表面电荷积聚问题展开研究,建立了一套基于静电探头法的表面电荷测量系统,研究了在SF6气体环境中,不同电压幅值和电压极性反转情况下绝缘子表面电荷的积聚规律。同时,在特高压直流GIL试验单元上进行了直流闪络试验,研究了绝缘子表面电荷积聚对直流闪络特性的影响。研究结果表明:在0.5 MPa的SF6中,绝缘子表面主要积聚与所加直流电压极性相反的电荷,这种电荷分布将增大绝缘子表面与中心电极间的局部场强,并将进一步导致绝缘子闪络;GIL中盆式绝缘子的直流耐受电压仅为交流耐受电压的64%左右。该研究为GIL中盆式绝缘子在直流电压下闪络电压下降提供了一种可能的解释。As the process of UHVDC power transmission projects accelerates in China, the demand for DC gas insulated transmission lines （GIL） is increasing. Thus it is very necessary to investigate the key issues of GIL under UHVDC vol- tage. Focusing on the surface charge accumulation phenomenon of GIL insulator under DC voltage, we established a surface charge measurement system based on an electrostatic voltmeter. Moreover, we studied the surface charge accu- mulation patterns in SF6 under different voltage amplitudes and under polarity reversal conditions. Meanwhile, we experimentally studied the flashover in a UHVDC GIL test unit in order to study the influence of surface charge accumu- lation on the flashover eharaeteristics of the GIL insulator. The results show that, in SF6 at 0.5 MPa, the most accumulated charges on the insulator surface are those with the opposite polarity of the applied voltage, which can enhance the electric field between the electrode and insulator surface and even leads to flashover on the insulator. The flashover experiments show that the maximum withstand voltage of GIL insulator under DC voltage is just 64% of that under AC voltage. The study can give a possible explanation for the reduction ofDC flashover voltage of GIL insulator.

关 键 词：表面电荷 绝缘子 SF6 气体绝缘 GIL 特高压直流 闪络 静电探头 

分 类 号：TM216[一般工业技术—材料科学与工程]