共查询到19条相似文献,搜索用时 156 毫秒
1.
快速准确定位电缆局放故障位置对电缆系统安全稳定运行具有重要意义。针对传统行波定位法在长电缆局放定位时反射信号难以识别以及存在时间同步误差的问题,提出一种基于变分模态分解-维格纳威尔分布(VMD-WVD)相位法的电缆局放双端定位方法,通过准确标记双端局放信号波头时刻实现双端局放信号的同步,利用相位定位实现长电缆局放入射信号的双端同步。文中建立了长线路PSCAD模型,分析故障位置、电缆长度和采样率对VMD-WVD相位法在长电缆定位的精度影响。结果表明,在上述3种因素影响下,VMD-WVD相位法的平均定位精度分别为0.54%,0.85%,0.69%,高于传统行波定位法。文中研究成果为长电缆局部放电精准定位提供一种全新思路。 相似文献
2.
3.
城市电网中因电缆沟电缆故障起火的事件时有发生,电缆绝缘劣化是电缆发生故障的重要原因,局部放电(简称局放)是电缆绝缘缺陷的表征,也是导致其绝缘劣化的主要原因之一。一直以来手持局放仪巡检电缆线路是诊断电缆绝缘状态的重要方法,为降低工作人员手持局放仪巡线的繁琐程度,研究了一种新型的电缆局放在线监测系统,该系统中使用高频电流传感器耦合流过电缆接头接地引下线的高频脉冲电流信号,并通过新型局部放电采集器将局放综合信息上传至局放监测主机,完成局放信号的实时在线监测。与传统的局放采集器相比新型局放采集器搭载了电力人工智能芯片,实现了局放信号处理的边缘计算,极大地缓解了庞大安装数量级下局放监测主机的压力,最后在现场测试中应用了该系统,并验证了该系统的可行性。 相似文献
4.
针对传统高频电流法检测电缆局放存在的缺陷,提出采用基于信号分离技术的电缆局放检测方法的理论依据,并采用 TechImp局部放电仪对一条电缆进行局放检测,以证明基于信号分离技术的电缆局放检测方法的可行性和优越性。 相似文献
5.
6.
不同类型的高压电缆局部放电(简称局放)模式识别是该领域的难题。部分电缆局放类型之间相似度较大,识别困难。针对该问题,文中提出了一种基于随机决策森林(RF)的高压电缆局放模式识别方法。首先,制作了5种高压电缆人工缺陷,结合IEC 60270—2015系统和高频电流互感器(HFCT)进行实验,获取局放数据,并进行局放特征提取。其次,介绍了随机森林算法的原理和基于随机森林的高压电缆局放模式识别流程。最后,基于实验所得数据开展了局放模式识别方法有效性验证,确定了随机森林每个节点处特征子集中特征个数、节点分裂规则、树的棵数3个参数,并与传统的决策树、BP神经网络和支持向量机(SVM)3种方法进行比较。结果显示,与上述3种方法相比,随机森林算法对高相似度局放识别能力更强。 相似文献
7.
交联聚乙烯电缆局放系统的应用研究 总被引:1,自引:0,他引:1
局部放电测试是发现电缆缺陷的一种重要手段,随着电缆网的发展这种测试方法越来越受到关注。目前市场上的局放测试设备较多,介绍了技术较为成熟的意大利TechImp公司局放检测系统。通过一次现场案例的阐述,论证了其在局放测试中的有效性,同时也证明了局放测试的重要性。 相似文献
8.
9.
由于电缆中局放脉冲传播速度很快,对电缆局放定位误差影响很大。由于电缆参数不同导致其中局放脉冲的传播速度有所差别。波速微小的差别会使定位结果偏差较大。针对不同电缆,局放定位应该采用基于实验确定的波速。在分析了广泛应用的交联聚乙烯(XLPE)绝缘电缆中局放脉冲传播特性后,提出了电缆局放定位中波速确定方法。基于实验数据拟合,得到局放脉冲在电缆中的传播时间与电缆长度的表达式,为局放点精确定位打下基础。 相似文献
10.
11.
Partial Discharge Pulse Propagation in Shielded Power Cable and Implications for Detection Sensitivity 总被引:1,自引:0,他引:1
《Electrical Insulation Magazine, IEEE》2007,23(6):5-10
Boggs and Stone (1982) defined the fundamental limits to the electrical detection of corona and partial discharge (PD), i.e., wideband detection of a PD-induced pulse in the presence of thermal noise. This paper treated the effect of frequency-dependent attenuation in shielded power cable in that context. However, most of the plots in that paper were the result of numerical computations. In the same year, Stone and Boggs set out a theory for high-frequency attenuation of shielded power cable. They showed good agreement between attenuation predicted from measured material properties and measured, high-frequency attenuation of shielded power cable. Since 1982, measurements of high-frequency cable attenuation have been reported by a number of authors for a variety of cables. In addition, software tools have become available that facilitate an analytic solution for the parameters of interest. This article summarizes the theory for PD propagation in shielded power cable for both symmetric (Gaussian) and asymmetric PD-pulse waveforms, based on the assumption that the attenuation constant (dB/m or Nepers/m) of the cable is proportional to frequency. This appears to be the most complete possible analytic exposition of PD attenuation in shielded-power cable, which has obvious applications to field PD measurements of such cable. 相似文献
12.
13.
局部放电(简称局放)试验是验证交联聚乙烯绝缘电力电缆(简称交联电缆)及电缆附件质量的重要环节。脉冲电流法一直是目前实验室内进行局放检测的主要方法,该方法在技术上已经较为成熟,且由于实验室内屏蔽效果好,背景干扰低,因此对电缆或电缆附件进行出厂试验之一局放检测效果较好,但是对于运行的电缆或电缆附件进行局放检测,或对已经发现存在局放的电缆回路中进行局放定位,往往需要复杂的波形分析或数学计算。通过利用超声局放测量仪器,对运行前和运行中10 kV交联电缆和电缆分支箱等电缆附件分别进行了局放测量,方法简单易行,取得了较好的效果。 相似文献
14.
In this second of a series of three papers, the authors investigate partial discharge (PD) detection and propagation in cable joints. The complex nature of cable joints leads to errors when PD analysis is carried out using conventional equivalent circuits. The authors use the finite difference time domain method to determine the transient electromagnetic fields caused by simulated PD in model cable joints. 相似文献
15.
《Electrical Insulation Magazine, IEEE》2008,24(1):25-29
Dispersion, the variation in propagation velocity with frequency, is one of those phenomena that people in the field of partial discharge (PD) detection have talked about since at least the early 1980s, but which is lacking a formal treatment in the literature. When one of the authors recently published an analytic theory of PD propagation in shielded power cable, both reviewers said "dispersion, dispersion". They believed that dispersion was important but gave no evidence for that assertion. In fact, as shown below, dispersion in shielded power cable has little if any impact on measurement of PD magnitude because the Fourier components of the pulse attenuate to insignificance before they can disperse to a degree that would cause appreciable change in the peak pulse amplitude or integral of the pulse waveform. However, dispersion does cause some distortion of the pulse shape that has implications for PD location, as it has a second-order effect on the timing of the peak PD amplitude relative to other pulses in the pulse train caused by multiple reflections from the ends of the cable. A Gaussian PD pulse in the time domain will have a Fourier spectrum that is also Gaussian in the frequency domain. If the Fourier components in the frequency domain propagate down the cable at differing velocities, the waveform to which they add will vary as a function of distance propagated, and the energy in the PD pulse is likely to spread out in time, which would have an effect on wide band PD detection no matter what the means of detection. 相似文献
16.
Kreuger F.H. Wezelenburg M.G. Wiemer A.G. Sonneveld W.A. 《Electrical Insulation Magazine, IEEE》1993,9(6):15-22
Errors in partial discharge (PD) location on high voltage dielectric cables caused by both mechanical and electrical phenomena are discussed. The sources of error relevant to PD location include errors in measuring time delays, scatter caused by noise and disturbances, pulse propagation distortion, errors in cable length measurement, and trivial errors in experimental technique. Experiments to determine typical PD location error were carried out using a detector with a 10 MHz bandwidth. Extensive tests were carried out on a 200 m, 15 kV cable with metering marks on the outer sheath, as well as a 590 m, 10 kV cable without metering marks 相似文献
17.
电力电缆在电力、建筑、通信等供电及辅助系统中应用愈来愈广,然而电力电缆在高电压、强电场、大电流以及复杂环境条件下,容易发生绝缘老化、电树枝化甚至击穿故障。此外由于铜损、介质损耗发热会导致电缆温度升高和恶化加剧,因此通过监测电缆局放及温度来实现监测电缆绝缘性,是保障电网安全运行的重要手段。本文研发了具有高速采集功能的高频检测模块(100MHz)。首先,基于此模块,本文结合同步信号降噪技术,滤除现场各种类型的干扰信号;结合聚类多源分离技术,解决了多源叠加影响类型诊断的问题;结合小波滤波降噪技术,有效的滤除窄带型干扰信号。此外,基于大量现场实践经验,构建了包含各种典型放电类型各个发展阶段的放电信息指纹库,实现了对局部放电缺陷类型的准确诊断和基于放电发展阶段的状态评估和预警。最后,提出了低成本高频局放及温度检测的改进方法,实现了局放及温度的同时监测功能,并提高了电力电缆局放及温度多维度检测的可靠性。 相似文献
18.
The partial discharges (PDs) inside of high-voltage cable insulation negatively influence cable service lifespan. Therefore timely detection and localization of affected areas with the weakened electric insulation is a vital question, in particular—according to measured values of PD parameters before they reach the dangerous stage of their development. Electrical cable is a circuit with the distributed parameters for current and voltage waves, initiated by local PD which changes their starting values with time. These changes can be taken as informative parameters for solving problems of localization of the defect and evaluation of dangers to cable's performance. Clear and detailed understanding of PD pulse distribution features in power cables is the basis for correctly solving cable diagnostics tasks with non-destructive approaches. This article uses the mathematical model of a power cable on the premises of cable equations. The model allows for modeling of wave processes in a non-uniform electric circuit (at sudden change of longitudinal parameters) in view of repeated reflection of PD waves from the ends and un-homogeneities of an electric cable. Results of mathematical modeling were compared to the data received from physical model of 110 kV XLPE electric cable. The cable physical model is realized with the help of the chained circuit consisting of 15 quad-poles. This document shows results of measurements and modeling of wave process caused by PD. Also, details of the wave process as dependent on time and frequency, and practical use of measurements of PD for cable insulation control, are discussed. Practical measurements show high degree of accuracy with regards to the data generated by theoretical model analysis. 相似文献
19.
Oussalah N. Zebboudj Y. Boggs S.A. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(5):1264-1270
Shielded power cable can be considered as a lossy transmission line, the high frequency attenuation of which causes the PD pulse amplitude, as well as the pulse energy, to decrease as a function of distance propagated. We develop analytical expressions which characterize PD pulse propagation in a shielded power cable for both symmetric and asymmetric PD pulse waveforms for an attenuation constant which increases linearly with frequency. 相似文献