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Hirotaka Muto Masashi Doi Haruhisa Fujii Mitsuhito Kamei 《Electrical Engineering in Japan》2000,131(2):1-11
Electromagnetic waves are used for detection of partial discharges (PD) in GIS (gas‐insulated substations). A very wide frequency band up to 1.5 GHz is utilized for detection. There are three categories of electromagnetic wave which can be excited and propagate in coaxial cylindrical structures like GIS, namely, TEM, TE, and TM modes. The characterization and identification of each mode is indispensable to understanding the partial discharge phenomena in GIS. In this paper, peaks in the frequency spectrum excited by PD are identified in each mode and the resonant characteristics of each mode are studied. The following are the major results: (1) The resonance peaks appear at the frequencies defined by the spacer distance. (2) The intensity of each mode depends on the position of discharge source along the radial direction. The lower‐order modes including TEM are excited when a discharge source is located near the center conductor. On the other hand, higher‐order modes are excited when the discharge source is at the enclosure surface. (3) The experimental profile of each mode excited by PD along the radial direction approximately agrees with the general theory of electromagnetic wave propagation in coaxial cylindrical cavity. © 2000 Scripta Technica, Electr Eng Jpn, 131(2): 1–11, 2000 相似文献
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GIS局部放电外置超高频检测系统 总被引:4,自引:1,他引:4
研制了宽带和窄带两种超高频外置天线传感器,两种传感器增益均大于1,驻波比在其有效带宽范围内均小于2,均能用于GIS局部放电超高频检测。设计了高性能放大器和半分布参数超高频滤波器,工作频带为300~1000MHz,完全覆盖了两种传感器的工作频带。性能测试表明,传感器和滤波放大器性能优良,频率匹配,能满足超高频信号检测预处理的要求。通过对绝缘子表面金属污染缺陷产生的局部放电信号进行检测研究表明,超高频检测系统能够检测到超高频段微弱的局部放电信号,并能抑制低频段干扰,为后续模式识别的研究打下了基础。 相似文献
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基于GIS中电磁波传播路径特性的局放源定位方法 总被引:10,自引:1,他引:9
气体绝缘开关设备(GIS)中发生局部放电(以下简称局放)时,为查找绝缘缺陷,需对局放源进行准确定位。超高频(UHF)时差定位法由于原理简单、实现方便、定位精度高等优点获得了广泛应用,但当局放信号的初始脉冲较小而难以确定信号的起始脉冲时间时,UHF时差法将难以有效运用从而导致较大误差。为提高时差定位法的准确性,对局放电磁波在GIS中的传播路径特性进行研究,分析结果表明,局部放电产生的电磁波在GIS中的传播路径与局放源的位置、检测点的位置密切相关,据此提出了基于传播路径的脉冲时差定位法。实验结果表明,当局放源位于GIS外壳附近、电磁波信号初始脉冲很小、难以辨识时,用该方法可以准确定位。 相似文献
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对变压器局部放电在线检测方面的研究进行了阐述和分析,根据几种不同的局部放电检测方法,从数据的采集、干扰的产生及抑制、局放的定位和局放信号分析等几个方面进行了总结和评价。指出传统的局部放电检测测量频率低、信息量少、易受外界干扰,而超高频测量技术也存在频带窄、检测范围有可能不包含放电特征峰等缺点,超宽频带局部放电检测技术具有测量频率高、频带宽、信息量大等优点,可以较全面地研究局部放电的本质特征,从而揭示了变压器局放在线检测的发展前景和当前的研究重点。 相似文献
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GIS中电磁波传播特性的仿真研究 总被引:10,自引:2,他引:8
为研究UHF信号在GIS中的传播特性,采用时域有限差分法进行了仿真建模和计算。GIS内部的局部放电会在腔体中激励超高频(UHF)电磁波信号,UHF法是通过对局部放电时产生的超高频电磁波信号进行检测,获得局部放电信号的有关信息以实现对设备的绝缘状态诊断和评估。UHF法抗干扰能力较强、灵敏度高。仿真结果表明,UHF信号在GIS内传播时呈现明显的时延特性,有利于局放源的定位;UHF信号的强弱和检测点与局放源的夹角Φ有关,Φ=0°和180°时信号的能量最大;局放脉冲越陡,在GIS腔体中激励的高次模波分量越大。 相似文献
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Electromagnetic Wave Propagation in a Coaxial Pipe GIS Model 总被引:2,自引:0,他引:2
Okabe S. Kaneko S. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(5):1161-1169
Partial discharge (PD) detection using a UHF band signal is a well known advanced insulation diagnosis method in a gas insulated switchgear (GIS) and has been actively studied. Detailed investigation of detection principles and electromagnetic wave propagation inside the GIS tank is required for significant improvement in sensitivity and accuracy. As the wavelength of UHF-band signals is comparable to the GIS tank size, higher-order modes also appear in electromagnetic waves propagating inside at frequencies at or above a certain value, creating complicating phenomena. This study investigated these phenomena, focusing on experiments with a UHF sensor inside a coaxial pipe as a simplified model of GIS structure, while varying conditions such as sensor shape and installation position (both circumferential and longitudinal), the input method of a simulated PD signal, and the presence or absence of an insulating spacer. On the low frequency side (TEM mode only), the sensor output can be described by an equivalent electric circuit determined by the coupling capacitance between the sensor surface, the center conductor and the tank. At the cutoff frequency of the TE11 mode or above, resonance phenomena appeared, which were related to the pipe length. Further, it was found that installing an insulating spacer inside the coaxial pipe shifted the resonant frequency in a manner closely connected with the spacer position's relationship to the electric field distribution inside the tank. 相似文献
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为了了解局部放电类型对UHF传感方法灵敏度的影响,笔者采用10~80MHz、150~250MHz、300~800MHz3种频段的高频放大器对浮电位局部放电进行测量。试验选择了0.2、0.8、1.4mm3种浮电位放电间隙。随着放电间隙的增大,局部放电量增大,但300~800MHz频段检测信号的幅值减小。结果表明,UHF检测信号的幅值并不能准确反映局部放电的严重程度,建议采用多频段信号传感,根据多频段检测信号幅值的相对关系进行局部放电严重程度判别。 相似文献
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为了抑制局部放电(PD)信号中含有的窄带周期干扰和白噪声,提出一种基于优化的变分模态分解(VMD)阈值去噪方法。首先针对VMD算法可能造成染噪信号欠分解或过分解的问题,提出一种基于频谱分析和四分位数的模态分解数K值优化方法,并结合模态的峭度特征去除窄带周期干扰和高频白噪声;针对PD信号主导模态中残留的白噪声,利用文中研究中发现的VMD分解白噪声所得模态的两个统计特性,提出一种噪声标准差估计方法来确定阈值,最后引入间隔阈值函数对PD信号主导模态进一步去噪。采用该方法对仿真和实测信号进行去噪处理,并将其与传统方法进行对比,结果表明,所提方法不仅可以更有效地抑制噪声,同时也能更好地保留PD信号的特征。 相似文献
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Masayuki Hikita Shinya Ohtsuka Satoshi Matsumoto 《IEEJ Transactions on Electrical and Electronic Engineering》2007,2(5):504-509
The ultra high frequency (UHF) electromagnetic wave detection method has been widely studied and used in partial discharge (PD) measurement and as a diagnostic technique for insulation performance in gas‐insulated switchgears (GIS) and transformers. The UHF method has advantages such as high sensitivity, wide detection range and reduced external disturbances. On the other hand, there are still some issues to be solved in the UHF methods, such as a clear understanding of the propagation characteristics of electromagnetic waves arising from the structure of the equipment, optimization of antenna design, calibration of charge, etc. This article deals with the present status and future trend of the technology of this promising UHF method of PD measurement, together with recent activities and results from our laboratory. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
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Rui Yao Gangquan Si Yanbin Zhang 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(2):162-167
The ultrahigh frequency (UHF) method is used for detecting the three kinds of surface discharges started by metallic particles on the spacer insulators in gas‐insulated switchgear (GIS). Three different designs of the same surface defect are applied to ensure the consistency of the results. The present experiments are made on a 220‐kV GIS, which is close to the actual situations to study the surface discharge characteristic. A measuring system for this purpose consists of an oscilloscope connected to UHF sensors. Partial discharge (PD) data was captured by UHF detection using an oscilloscope and stored as phase‐resolved pulse sequence (PRPS) data. Since PRPS data contain the complete information of the PD, PRPS analysis (PRPSA) pattern and three‐dimensional ϕ − q − n (3D PRPD) pattern can be calculated from the recorded PRPS datasets. The PRPSA data also allows us to obtain the actual test voltage (rms) of every cycle, the number of measuring cycles, and phase information of all PD pulses, together with their peak values, so that a statistical analysis of these data can be discussed. Besides, this paper also focuses on the frequency analysis and time–frequency analysis of the single‐pulse time‐domain signal. It is shown that the characteristic parameters obtained from the PRPS data, frequency spectrum, and time–frequency spectrum have the potential to be used as PD characteristic interpretation and further research on PD pattern identification. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
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分析了各种气体绝缘开关(gas insulated switchgear,GIS)局部放电检测方法,认为特高频(ultra high frequency,UHF)法抗干扰能力较强,检测效率较高,可实现在线监测、故障模式识别及定位。以一起UHF在线监测系统发现的GIS设备缺陷为例,分析并总结运行经验。运行经验表明,对连续性的局部放电信号要重点关注,应监测24 h局部放电的发展情况,必要时利用便携式设备进行复测,排除现场干扰,确定故障位置,进行解体处理。通过安装GIS设备局部放电UHF在线监测系统,可发现GIS设备隐患,有效保证电力系统的安全稳定运行。 相似文献
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油纸屏障对变压器局部放电超高频检测信号的影响 总被引:2,自引:2,他引:0
受变压器内部复杂结构的影响,局部放电超高频信号在变压器内部的传播特性非常复杂。笔者通过变压器局部放电超高频实验研究,分析了油纸屏障对变压器局部放电被测超高频信号的影响。设计了油中气隙放电、油中沿面放电和油中电晕放电3种局部放电模型,在实验油箱中进行局部放电实验,采用超高频小环天线进行放电信号检测,在有无油纸屏障情况下获得了局部放电超高频信号实测数据,对所测局部放电超高频信号在时域和频域上进行了对比分析。结果表明,油纸屏障对超高频信号幅值衰减及信号功率谱有一定影响。 相似文献
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利用辐射UHF信号反演局部放电脉冲电流 总被引:1,自引:0,他引:1
获取局部放电(PD)特征信息是局部放电特高频(UHF)检测的关键问题之一,研究UHF信号与PD脉冲电流之间的关系有助于绝缘缺陷的诊断.文中从电磁辐射理论出发,计算了变压器油箱外壳等复杂环境影响下的PD脉冲电流辐射场,分析了PD脉冲电流辐射场的横电磁波特性.在此基础上,提出了利用检测UHF信号的时间积分反演PD点脉冲电流的新方法,并讨论了UHF传感器及检测系统频带对PD脉冲电流推测算法的影响.仿真和油中针-板型放电实验结果表明:文中所提出的方法能有效推测PD脉冲电流波形,对变压器PD信号UHF在线监测和智能化诊断有一定的参考价值. 相似文献