【作者】 彭文雄；

【导师】 唐炬；

【作者基本信息】 重庆大学 ， 电气工程， 2005， 硕士

【摘要】 全封闭组合电器(Gas Insulated Switchgears,简称GIS)与传统的电器设备相比具有突出优点,它的问世是电力领域的一次革命。运行经验表明,尽管GIS 的运行可靠性非常高,但其内部不可避免的缺陷仍可能引起事故。GIS 最通常的故障特征是在绝缘完全击穿前发生局部放电,通过对GIS 局部放电的在线监测,可以及时发现GIS 内存在的缺陷,避免重大事故的发生。因此,开展GIS 局部放电检测及其模式识别的研究,对于保证GIS 的安全可靠运行、掌握GIS 的绝缘状况和缺陷类型特征以及指导GIS 的检修工作有着十分重要的意义。　本文通过对GIS 局部放电激发的电磁波的实验研究,分析了该电磁波的激励、传输、衰减与泄漏特性,表明超高频段的局部放电信号能够在GIS 中传播,而且会发生反射和折射,但在传播过程中会出现一定程度的衰减。正是因为这种电磁波的反射和折射,有利于外部天线接收。因此,根据现场实用的特点和要求,本文设计了超高频外置天线—矩形微带贴片天线,该天线与其它2 种外置天线相比,具有安装固定且方便,耦合GIS 局部放电信号强烈,且易于和后续电路集成等优点。实测参数表明:该天线性能优良,能满足超高频信号的检测。同时在实验室对不同模拟缺陷下的局部放电信号进行了大量的采集,并和内置传感器采集到的局部放电信号进行了比较。通过研究表明微带贴片天线有较高的灵敏度,能满足工程上的应用要求,为今后在实际工程中的应用打下坚实的基础。　在总结目前各种模式识别方法的基础上,提出基于分形理论与小波相结合的模式识别。在对已构造出的3 种实验模拟缺陷,利用内外传感器进行大量的实验数据采集的基础上,首先基于分形理论对局部放电信号的特征量—分维数进行了理论上的探讨。通过分析小波与分形理论内在紧密的联系,并结合小波构造的思想和方法,构造出小波对局部放电信号进行了时—频域的分解,使得各模拟缺陷下的局部放电信号分维数特征存在一定差别,以频率为横坐标,分维数倒数为纵坐标,作出了各缺陷下放电的图形,发现各缺陷产生的局部放电的特征峰区别显著。表明小波理论和分形理论互补应用于局部放电模式识别具有广阔的前景,为进一步进行GIS 局部放电诊断提供了新的特征信息,具有一定的理论价值。更多还原

【Abstract】 Comparison with traditional apparatus devices, Gas Insulated Switchgears (GIS) has salient advantages. Its appearance gives a revolution in power domain. The in service experiences show that internal GIS exists defects inevitably in spite of high reliability running. Partial discharge (PD) phenomena are most common characteristic before insulation breakdown in GIS. By PD on-line monitoring systems, GIS internal defects can be discovered in time to avoid the occurrence of fatal failure. So the research of PD detection and its pattern recognition for GIS is very important to guarantee its safe operation, to find out its insulation condition and defects type in time and to guide its maintenance. In this paper, according to the experimental study of GIS PD excited electromagnetic wave (EMW), the excitation, transmission, attenuation and leakage characteristic for the EMW show that PD signal in ultra high frequency (UHF) band could propagate in GIS, and could occur reflect and refraction, have a bit of attenuation, leak out in GIS spacer. According to the utility and the convenience, a UHF outer antenna sensor which is rectangular-patch micro-strip antenna is successfully developed, compared with the other outer antenna, it’s easy to install and fix to the next circuit. The measured parameter show the received antenna of PD signal in GIS is sensitive and is suit to measure in UHF. PD sample data of different artificial defect models are got by PD detection system in laboratory, and are compared with the signals which other sensor received. Based on present various pattern recognition methods, the hybrid method on account of fractal and wavelet theory is presented. According to three kinds of experimental defects, based on hundreds test data sampled by outer antenna sensor, the PD signal feature is extracted by fractal dimension discussed theoretically. The study shows that fractal dimension is a perfect feature, and combines to wavelet configuration idea and method. This paper utilizes wavelet to decompose the PD signals in time-frequency domain. The fractal dimension feature under different simulated PD signal could be apparently be distinguished and the PD patterns could be recognized evidently. The combination of wavelet theory and fractal theory could be applied to the PD pattern recognition . The combination have a wide outlook in insulation diagnosis and have theoretical values of character information of pattern recognition for future measuring on-line in GIS.更多还原