基于超声波法识别环网柜的局部放电类型研究

随着经济的快速发展,对电能质量提出了越来越高的要求,环网柜作为配电网联络的设备,其重要性不言而喻。由于环境影响,施工工艺等因素,环网柜中常常会有局部放电的现象,影响设备的稳定运行,危害电力系统的安全。环网柜的局部放电总的分类可分为四大类:悬浮放电、沿面放电、电晕放电和多点放电,不同的局部放电类型相应的特点以及对环网柜的损害都不一样。基于此,采用超声波法对环网柜的局部放电类型进行识别研究,从超声波检测方法的幅值图、超声波检测方法的相位图和超声波检测方法的波形图三位一体,比较了不同局部放电类型的特征和差异点。与传统的超声波法相比,文中方法检测的参数更多,更能实现准确检测。不仅可以加深对局部放电的了解,具有实际的实践意义,还能为进一步的局部放电定位奠定扎实的理论基础。     

运行中的GIS不同部位盘式绝缘子超宽频带局部放电特性试验研究

采用超宽频带局部放电测试系统,研究了玉泉变运行中的110kV电压等级GIS各关键部位盘式绝缘子的超宽频带局部放电信号。试验结果发现,运行中的GIS不同部位的盘式绝缘子具有各不相同的局部放电特征,且放电频率主要集中在300MHz频率段以下,为今后GIS在线监测提供了数值依据。     

Electrical measurements for the characterization of electret properties of cellular polymers

Cellular polymeric materials may show interesting quasi-piezoelectric properties, upon charging under specific conditions of electrical field, temperature, pressure and environment. Electrical charging is the trigger of electret properties. It has been proved that the occurrence of electrical avalanches in the cavities which are present in a material is associated with the appearance of electret behavior, but the precise nature of the phenomena involved in this transformation is still under investigation. This paper provides a contribution to the study of these materials focusing on the relation between the appearance of electret properties and the presence of charge injection and partial discharge phenomena. For this purpose, space charge, partial discharges and low-frequency polarization measurements were carried out on polypropylene (PP) cellular materials, at different fields and temperatures. The existence of a threshold field for the start up of electret behavior that is larger than the threshold for space charge injection and partial discharge inception was observed. Steady charge is accumulated in the material, thus generating electret behavior, only if partial discharge repetition rate becomes sufficiently high and space charge is injected from electrodes. Space charge measurements were performed through the pulsed electroacoustic technique, in spite of significant attenuation of acoustic waves due to the cellular nature of the materials. Partial discharge measurements were carried out by an advanced system recording each discharge pulse, thus allowing observation of single and multiple pulses, besides achieving statistics of discharge pulse amplitude and phase. By such approach, space charge and partial discharge measurements proved to constitute a valuable tool to investigate the phenomena leading to piezoelectric behavior and, also, to infer electret time stability and optimize charging methodologies.     

PD source recognition by Weibull processing of pulse heightdistributions

The problem of identification of partial discharge (PD) phenomena occurring in an insulation system is addressed in this paper. PD distributions coming from different sources, such as internal voids, as well as surface and corona discharges, are compared. In particular, the investigation focuses on the Weibull probability function applied to pulse charge-height distribution. It is shown that the different discharge sources can be identified on the basis of the value of the shape parameter of the Weibull distribution and that identification holds even when two PD sources are combined, i.e. are active simultaneously. In this case, the application of the 5-parameter Weibull function permits separation of PD phenomena, and recognition by means of the shape parameter value associated to each phenomenon. Finally, the proposed procedure is applied to practical objects, i.e. insulation systems of rotating machines, with real insulation defects, showing promising on-field application prospective     

高压电缆终端在线局部放电测试分析

介绍了综合运用高频(high frequency,HF)与超高频(ultrahigh frequency,UHF)2种测试技术成功实现对运行中高压电缆终端局部放电进行测试的实例.方法是首先利用UHF检测系统初步巡检,然后根据现场情况分别采用多种信号检取方式从被试电缆终端取样测量信号,进行HF深入测量.测试的结果:获得了...     

X射线激励下局部放电的研究进展

X射线具有较大的能量,能使电介质发生电离,进而可以影响局部放电的发生与发展过程。首先介绍X射线激励固体绝缘内部气隙、油纸绝缘内部气隙和油隙等典型缺陷局部放电的宏观现象,综述X射线能够为绝缘体中的气隙放电提供给初始电子,减小放电统计时延,降低局部放电起始电压的机理。其次,阐述近年来X射线激励下GIS绝缘子中气隙缺陷、环氧树脂浸渍绝缘中气隙缺陷和油纸绝缘系统等绝缘结构中的局部放电现象和特性。最后,总结现有X射线激励下局部放电检测技术的应用场景,给出该技术的发展和应用前景。     

Use of a mixed-Weibull distribution for the identification of PDphenomena [corrected version]

The interaction between partial discharge (PD) phenomena occurring in insulating systems is investigated in this paper. In particular, the recognition of two PD phenomena simultaneously active is approached by means of a 5-parameter additive Weibull distribution. Various shapes of the PD height distribution, obtained from measurements performed on specimens of stator bars and windings of ac rotating machines, are considered. It is shown that the proposed probability function fits well the partial discharge height distributions. The probability distribution relevant to each concurring PD phenomenon can be derived, analyzed and identified. Moreover, the standard average quantities are estimated for each phenomenon     

基于联合检测的环网柜局部放电方法研究

随着城市配电网的快速发展,对供电可靠性的要求也越来越高,环网柜作为配电网联络、转电的设备,其重要性不言而喻。环网柜局部放电的快速准确检测对于保障电网安全稳定运行,提高供电的可靠性具有重要的意义。文中详细介绍了脉冲电流法和特高频法的相关原理及其相应的特点,并提出了运用脉冲电流法与特高频联合检测方法对环网柜的局部发电进行检测。通过现场测试可知,所提出的方法能够准确快速地实现环网柜局部放电的检测,具有很好的实践意义。     

GIS局部放电检测中的小波包变换提取信号

在介绍小波包变换算法的基础上，将小波包变换用于白噪声干扰下的气体绝缘组合电器(GIS)局部放电信号提取。对模拟的局部放电信号进行了小波包分解与重构的计算机仿真研究，分析了不同的局部放电波形、噪声水平及采样率对去噪结果的影响，最后对GIS内置传感器实测波形进行了小波包变换去噪。     

局部放电特高频检测校准影响因素研究

局部放电特高频(UHF)法广泛应用于电气设备在线监测,由于UHF信号传递函数的影响因素相当繁复,至今未能实现定量校准。为研究UHF检测技术定量校准的影响因素,分析了典型局部放电源的放电机理,通过试验研究了UHF信号的传播规律以及天线测量特性。研究表明,基于特征参量放电量的UHF检测校准可靠性与放电源有较大关联,电晕放电与悬浮放电的校准曲线更能准确表征设备绝缘缺陷的严重程度,内部气隙放电与沿面放电的准确性则相对较差。UHF信号能量衰减至平稳期所需距离随频率增高而变小,而UHF信号频率变化时不影响传感器在不同角度测量的信号能量衰减变化规律。因此,UHF信号校准必须综合考量具体的放电类型与测量条件。研究结果可为构建UHF校准体系的进一步研究提供参考,对推进UHF法在电力设备故障诊断和绝缘状态评估中的应用具有重要意义。     

Identification of Partial Discharge Location Using Probabilistic Neural Networks and the Fuzzy C-means Clustering Approach

This article proposes an approach for location of partial discharge sources in the power cable and gas-insulated load break switches using a probabilistic neural networks and the fuzzy C-means clustering approach. Three different defect positions are designed in the power cable and gas-insulated load break switches. The three different defect positions of partial discharge occurrence are located by the proposed method. Discrete wavelet transform is employed to suppress noises of measured signals by the high-frequency current transformer. The proposed method can assist electrical engineers in making accurate statistical judgments. To accurately discover the different defect positions, the proposed method uses feature extraction and statistical analysis of the measured signals. Finally, experimental results validate that the proposed approach can effectively determine the location of partial discharge sources in practical partial discharge measurement.     

油纸绝缘老化的超宽频带局部放电信号时频域特性逐步判别分析

传统局部放电检测方法测量和分析1MHz以下信号,测量频带窄、信息量少、易受干扰,不能全面反映局部放电本质特征。首先对多个试品进行电热联合老化试验,然后用超宽频带局部放电测试系统,将时域参数和频域参数相结合诊断油纸绝缘老化状态。通过逐步判别分析,先选取13个时频域特征参量中的8个重要特征参量,建立典型判别方程,描出对应的散点图。继而又推导出分别表征油纸绝缘5个老化阶段的Bayes线性判别方程。经原样本组内验证和Jackknife法交叉验证,所建方程组用于诊断油纸绝缘老化状态具有良好的效果。     

高压设备局部放电脉冲电流频度数字测量

提出了局部放电脉冲电流频度单片机测量方案,讨论了不同相位的测量问题。给出了该方案的硬件系统和软件编程的实现方法。这种测量方法是检测局部放电的重要手段之一。所做的工作为研制电气设备局部放电在线监测系统打下了良好的基础。     

紫外成像检测变电设备电晕放电的实际应用

介绍紫外成像技术检测变电设备电晕放电的实际应用,利用紫外成像仪对变电站设备进行检测,发现了部分设备的电晕放电现象,对放电现象进行了分类,并初步分析放电原因.     

Use of a mixed-Weibull distribution for the identification of PDphenomena [rotating machines]

The interaction between partial discharge (PD) phenomena occurring in insulating systems is investigated in this paper. In particular, the recognition of two PD phenomena simultaneously active is approached by means of a five-parameter additive Weibull distribution. Various shapes of the PD height distribution, obtained from measurements performed on specimens of stator bars and windings of ac rotating machines, are considered. It is shown that the proposed probability function fits well the partial discharge height distributions. The probability distribution relevant to each concurring PD phenomenon can be derived, analysed and identified. Moreover, the standard average quantities are estimated for each phenomenon     

转轮法试验中复合绝缘子放电现象及泄漏电流特征分析

为明确复合绝缘子转轮法试验中放电现象及泄漏电流与其老化程度的对应关系,利用自主研制的复合绝缘子转轮老化试验装置对8支"R配方"的复合绝缘子短样进行了30 000转老化试验。通过监测老化过程中绝缘子表面放电现象及泄漏电流变化,总结出绝缘子表面放电现象及泄漏电流波形变化大致可分成均匀烘干、干带电弧、零星放电和微弱放电这4个阶段。分析了这4个阶段放电特征和泄漏电流波形特征,发现泄漏电流幅值、3次谐波和5次谐波的变化规律同绝缘子的老化程度有一定的对应关系,对辨识转轮试验中复合绝缘子表面的老化程度有一定的参考价值。     

局部放电检测用超高频天线的设计与性能对比

根据高压电力设备局部放电信号检测的需要,基于PCB技术设计并制作了四种不同原理和结构尺寸的超高频天线,仿真分析了其性能参数,检验所设计天线用于局部放电超高频检测法的可行性。利用矢量网络分析仪测试天线的端口特性,验证了天线的电压驻波比等参数。基于GTEM小室提供标准场,在不同工作频率下分别对四种天线样机的天线系数进行了标定,得到各天线系数的拟合公式与曲线。采用针-板放电模型作为局部放电源,基于脉冲电流法测量参考放电量,对所设计的天线进行了局部放电测试实验,采集天线接收到的局放信号波形。仿真和实验结果表明微带天线与缝隙天线工作带宽和增益较低;偶极子天线与螺旋天线在工作频带内损耗低、增益高、阻抗匹配效果较好,检测局部放电信号的效果良好。     

高强度气体放电电子镇流的非线性频率调制

研究表明,高强度气体放电灯高频工作且具备适当的激励频率和足够的能量时,会产生声谐振现象.在脉冲宽度调制频谱分析的基础上,提出了非线性频率调制方法,分散输出电流频谱,减小各频率分量的振幅,降低激励能量;同时使得调制频率非线性变化,防止离子声波在固定频率点上产生驻波,从而抑制声谐振.文章也给出了实现方法和测试结果.     

基于局部放电统计参量的脉冲电压下绝缘老化分析

主要针对匝间和对地绝缘电磁线在脉冲电压下老化后的局部放电特征进行了研究.通过不同老化时间的局部放电相位相关分析,在高频脉冲电压下老化后放电次数相位分布出现明显的"放电丛"现象,并通过工频老化后的局部放电结果对此加以证实.通过两种不同电磁线老化特征对比,匝间绝缘和对地绝缘呈现不同的放电特征,匝间主要以内部气隙放电为主,而对地绝缘电磁线则以槽放电为主.此外,测量和分析了局部放电统计参量(如偏斜度、峭度、不对称度等)随老化时间的变化,结果表明平均放电量的偏斜度和老化时间有着一定联系.为更深入地研究脉冲电压下绝缘老化机理打下了坚实的基础.     

GIS体外超高频法检测局部放电的研究与应用

简单介绍了GIS几种局部放电常用的检测方法,具体论述了GIS局部放电超高频(UHF)检测法,分别对UHF检测法检测原理、干扰原理、定位原理进行了阐述,通过对局部放电的波形特征、相位特征和频率特征的综合分析列出了各种局部放电现象的特征经验总结。最后给出了GIS局部放电UHF检测法的一个典型实例,应用此实例对GIS进行了局部放电现场测试及测试分析。