【作者】 孟庆红；

【导师】 唐炬；

【作者基本信息】 重庆大学 ， 电气工程， 2010， 硕士

【摘要】 六氟化硫（SF₆）气体具有优良的绝缘和灭弧性能,作为绝缘介质又可以大大减小设备尺寸,提高绝缘强度,已广泛地应用于气体绝缘组合电器（Gas Insulated Switchgear,简称GIS）中。纯净的SF₆气体化学性能稳定,不易分解。但局部放电、火花放电、电弧放电和过热作用会导致SF₆发生分解。通过分析气体分解组分来诊断SF₆气体绝缘电气设备的绝缘状况,目前已成为本领域研究的热点。局部放电（Partial Discharge,简称PD）是表征设备绝缘性能的主要指标之一,而传统的电测法难以摆脱现场电磁信号的干扰,存在局限性。研究表明PD会导致SF₆气体发生分解,并且不同的PD原因下SF₆的分解特性不同。深入开展对SF₆分解产物的形成过程、相对含量关系、影响因素等的研究,提出以气体组分定量检测评判绝缘状况的理论与方法,对实现GIS绝缘缺陷引起突发性故障的早期诊断和预测有着重大意义。本文主要针对GIS早期绝缘缺陷产生的PD导致SF₆气体分解问题进行基础研究。GIS内部常见的绝缘缺陷有高压导体突出物、自由导电微粒、绝缘子金属污染及气隙缺陷。本文利用建立的SF₆气体放电分解试验装置,并结合电气测量技术和气相色谱分析技术跟踪检测不同PD原因下SF₆的分解情况,研究GIS内部不同PD下SF₆分解特性及影响因素,寻找能有效表征绝缘故障类型的特征参量。为此,本文构建了四种GIS典型绝缘缺陷物理模型,并对缺陷模型进行电场分布仿真,仿真结果表明四种缺陷模型在预定部位和可接受的电压阈值内均能产生PD。同时,建立了能有效分离SF₆放电分解组分的气相色谱定量检测系统,在此基础上,对不同绝缘缺陷PD下的SF₆分解气体进行96h跟踪检测,测量结果显示:SF₆局放分解的特征组分有SOF₂、SO₂F₂、CF₄和CO₂,且不同PD下SF₆的分解特性和产气规律存在明显差异。研究发现,高压导体突出物PD稳定、放电能量大,SF₆产气量和分解速率高;自由导电微粒单次PD强度高,SOF₂/SO₂F₂较高;绝缘子表面金属污染由于PD涉及固体绝缘材料CF₄含量逐渐增加;绝缘子外气隙虽然PD强度较高,但产气量小。分析得出可以通过SOF₂/SO₂F₂、CO₂/CF₄、（SOF₂+SO₂F₂）/（CO₂+CF₄）三组含量比值初步判定四种绝缘缺陷类型,利用SOF₂/SO₂F₂监测PD强度及发展趋势,CF₄的含量变化在一定程度上反映GIS内绝缘材料的劣化情况。更多还原

【Abstract】 For the excellent insulating and arc-quenching performance, SF₆ can significantly reduce the equipment size and improve the dielectric strength. It has been widely used in gas-insulated switchgear （hereinafter referred to as GIS） as insulating medium. Pure SF₆ is non-toxic and non-flammable inert gas. It has good stability and is difficult to decompose. However, partial discharge, spark discharge, electric arc and local overheating can cause SF₆ decomposition. At present, it has become a hot area of research that by way of analyzing the decomposition components to diagnose the insulation condition of SF₆ gas-insulated electrical equipment.PD （Partial Discharge, referred to as PD） is the main indicator of insulation performance of equipment. However, the traditional measurement method is difficult to get rid of the electromagnetic disturbance in field. There are limitations. Researches show that PD can course SF₆ decomposition. And the decomposition characteristics has differences under various PD. Intensive study on the formation, mechanism and the relative content of SF₆ decomposition products in order to propose the judgments theory and method of insulation condition based on quantitative detection of decomposition components is significant to the realization of early diagnosis and prediction of GIS catastrophic failure caused by insulation defects. This paper mainly research on SF₆ decomposition characteristics under various PD of different insulation defects in GIS.The typical insulation defects in GIS include high voltage metallic outshoot, free conductive particles, metallic contamination on insulator, insulator external gas-gap, insulator internal bubble defects. Based on the SF₆ discharge decomposition test equipment and combined with electrical measurement techniques and gas chromate- graphic analysis, SF₆ decomposition compositions under different PD were tracked and measured in this paper. The SF₆ decomposition characteristics, the development of insulation defects and influencing factors under different PD were studied in order to find effective characteristic parameters of fault types. Therefore, five kinds of physical model of typical insulation defects were constructed and the distribution of electric field of these models was analyzed by Finite Element Simulation. Simulation results showed that the defect models can raise PD in scheduled location and acceptable threshold voltage.96 hours PD test was conducted for different insulation defects to cause SF₆ decomposition. The results showed that: The characteristic decomposition components of SF₆ under PD were CF₄, CO₂, SOF₂, and SO₂F₂, and due to different discharge energy, intensity, location, etc. in various PD the decomposition quantity and rate had significant differences. High voltage metallic outshoot PD had stable frequency and large energy. The decomposition rate of SF₆ was rapid and the gas production rate was high. Under high PD intensity of free conductive particles defect, SOF₂/SO₂F₂ was higher; Owing to involving solid insulating material in metallic contamination on insulator PD, CF₄ content increased gradually; In insulator external gas-gap defect PD intensity was high, but the total production was low. SOF₂ content is lower than SO₂F₂. Insulation defects can be preliminarily identified by analyzing SOF₂/SO₂F₂, CO₂/CF₄ and （SOF₂+SO₂F₂）/（CO₂+CF₄）. Further, use SOF₂/SO₂F₂ to assess intensity and development trend of PD. Changes of CF₄ content can reflect degradation of the insulating material in GIS to some extent.更多还原