变压器绕组局部放电故障的定位

频率响应分析法只能检测变压器绕组变形故障 ,而不能实现对局部放电故障的定位。在频率响应分析法的基础上 ,对变压器绕组的模拟电路进行了分析研究 ,利用绕组在一定频率范围内呈现纯容性的特性 ,给出了实现变压器绕组局部放电故障定位的新思路。经仿真计算 ,验证了这种局部放电故障定位的有效性。     

变压器绕组局部放电故障的定位

频率响应分析法只能检测变压器绕组变形故障,而不能实现对局部放电故障的定位.在频率响应分析法的基础上,对变压器绕组的模拟电路进行了分析研究,利用绕组在一定频率范围内呈现纯容性的特性,给出了实现变压器绕组局部放电故障定位的新思路.经仿真计算,验证了这种局部放电故障定位的有效性.     

Effect of manufacturer, winding age and insulation type on stator winding partial discharge levels

With thousands of machines monitored for as long as 25 years with the same method, on-line partial discharge (PD) testing has become a recognized, proven tool to help maintenance engineers identify which stator windings need off-line testing, inspections and/or repairs. With over 63,000 test results acquired with the same test method, what constitutes a winding with low, moderate or high PD has been identified. This paper presents tables that enable test users to easily identify with some certainty which stators are likely to suffer from groundwall insulation deterioration, with only a single measurement on a machine. The practical importance of these tables is that if one applies PD sensors to a machine and, in the first measurement, one obtains a Qm that exceeds the 90 percentile of the relevant Qm distribution, then one should be concerned enough at the PD level to take action, such as more frequent testing and/or off-line tests and inspections at the next convenient machine shutdown. Within the statistical accuracy possible with several thousands of independent results, it seems that critical PD levels only depend on operating voltage, hydrogen pressure, manufacturer, and the specific type of PD sensor and instrumentation used.     

Evaluation of the state of the insulation system of a stator winding of high-voltage electric machines based on measurements of statistical characteristics of partial discharges

The statistical characteristics of amplitude and amplitude-phase spectra of PDs in the insulation of model specimens with artificial flaws in a semiconducting coating are investigated. The algorithm for distinguishing the flaws in the stator winding insulation of high-voltage electrical machines based on statistical parameters of the PD spectra is developed and practically implemented.     

On-line monitoring of partial discharges on stator windings oflarge rotating machines in the petrochemical environment

This paper describes a joint collaboration program between a major large electric machine manufacturer and a petrochemical manufacturer to investigate the effectiveness of time- and frequency-domain techniques for the online monitoring of the health of high-voltage machine stator insulation systems. Information is given on the factory and site testing carried out, as well as on the analysis and discussion of the results. It is concluded that both techniques can be used in the petrochemical environment for general assessments, but the time domain technique is required if identification of specific locations of discharge sites is needed     

判断电动机定子绕组首末端的方法

一般电动机定子的绕组首、末端均引到出线板上，并采用符号D1、D2、D3表示首端，D4、D5、D6表示末端。电动机定子绕组的6个线头可以按其铭牌上的规定接成“Y”形或“△”形。但实际工作中，常会遇到电动机三组定子绕组引出线的标记遗失或首、末端不明的情况，此时可采用以下几种方法予以判别。     

双馈异步发电机定子匝间短路故障诊断研究

分析双馈异步发电机定子绕组匝间短路故障负序电流的来源,提出以负序电流作为故障特征量进行故障诊断,建立双馈异步发电机仿真模型,通过改变模型中短路匝数和短路电阻的大小实现了匝间短路故障模拟.对仿真发电机在风速恒定的条件下发生定子绕组匝间短路故障进行了模拟.结果表明,定子发生匝间短路故障后,会在定子中增加负序电流分量,定子负...     

大型发电机定子绕组局部放电在线监测方法的研究

考虑放电脉冲在定子绕组中的传播规律，通过安装在定子绕组线圈上的感应传感器监测发电机定子绕组局部放电，确保局部放电信号在变形和衰减前被分离，同时对局部放电信号进行处理。分析了其监测原理，以高压电缆接头或定子绕组线圈发生局部放电为例，将2个传感器分别置于试件两侧，分析这2个传感器上电压的关系，可判断局部放电是发生在试件的内部还是外部，并计算内部局部放电时的脉冲灵敏度或外部局部放电时的噪声干扰灵敏度。     

多相电机定子绕组改进绕组函数的有限元分析

提出改进绕组函数的有限元算法,解决了改进绕组函数的准确计算问题。根据有限元算法和叠加原理,分析了线圈和多相电机相绕组的改进绕组函数的基本特征,并根据该基本特征研究了多相电机气隙磁动势分布和气隙电感。结果表明,多相电机相绕组的改进绕组函数与绕组函数之间的差别为与多相电机结构有关的函数,电机正常运行时,该函数通常只含偶次谐波,并会影响电机气隙磁动势分布的计算,进而影响交、直轴电感曲线的谐波,但对交、直轴电感曲线的直流分量影响较小,基本可以忽略。     

无刷双馈电机定子绕组的设计

介绍了无刷双馈电机工作原理及其定子绕组的设计原则和方法，利用双极槽号相位图和单板槽号相位图对具体定子绕组进行了设计和分析。用本文所介绍的方法设计出的无刷双馈电机定子的单套或双套绕组方案，能保证定子绕组各支路感应电势相等以及其他电气性能要求，从而保证了无刷双馈电机的运行性能及可靠性，对无刷双馈电机设计有一定的指导意义。     

600MW汽轮发电机定子绕组水电接头泄漏分析

某电厂一台600MW机组在常规大修中，发现定子绕组多处水电接头漏水，检查发现水盒和空心导线等处泄漏，采取现场修理的办法，成功消除了漏水缺陷。本文详细介绍漏水处理的经过。     

F级模压定子线圈发空问题的研究

为了提高F级模压定子线圈的质量 ,解决线圈发空问题。通过对F级云母带胶化时间、热压过程的半压时间、热压温度和保温时间的试验研究 ,其应用试验结果表明 :选择合理的工艺条件 ,基本上解决了定子线圈发空问题 ,实际应用效果十分有效     

Forces acting on induction machine stator core due to winding faults

A newly developed model for direct calculation of the Fourier components of currents is presented. Any connection of stator coils including shortings, can be analysed. A formula giving forces acting on the stator has the form of a sum of various waves. The waves causing elliptical deformations of the stator yoke have been specially investigated. The calculation and measurement results given refer to a 7.5 kW machine.Ein neu entwickeltes Modell zur direkten Berechnung der Fourierkomponenten der Ströme wird vorgestellt. Beliebige Verknüpfungen der Ständerwindungen, darunter auch Kurzschlüsse, können analysiert werden. Der Ausdruck für die Kräfte hat die Form einer Summe von verschiedenen Wellen. Eingehender wurden jene Wellen untersucht, die zu elliptischen Verformungen des Ständers führen. Die Berechnungs- und Meßergebnisse betreffen eine 7,5 kW Maschine.     

基于负序电压分布的发电机定子匝间短路保护

提出发电机定子绕组匝间短路保护新判据方法,包括主判据和闭锁判据.主判据由发电机机端负序电压和中性点负序电流构成;闭锁判据由发电机机端负序电压、主变高压侧负序电压、主变中压侧负序电压、高厂变1分支负序电压、高厂变2分支负序电压构成.如果主判据为真,再判断闭锁判据是否为真,如果闭锁判据也为真,则立即闭锁保护,否则延时保护动作并发告警信号.所提方法不仅可对发电机的各种非对称故障进行反应,还可以对主变及厂用变压器的一部分内部故障进行反应;与纵向零序电压方案相比较,可不增加一次设备并且容易双重化;在靠近发电机中性点处相间故障时,可得到较高的灵敏度.     

基于小波变换的高压电动机定子绕组匝间短路故障在线检测新方法

基于小波变换的分析方法,提出了基于定子三相电流之间相位对称度检测的定子绕组匝问短路故障在线检测新方法。分析表明,该方法计算结果稳定、灵敏度高,能有效地检测出匝间短路故障。     

300MW发电机定子绕组高压预试及故障处理

发电机端部绝缘从制造角度来讲是1个较薄弱的部位,运行中发生故障的几率较高,而交、直流耐压试验是判断发电机定子绕组绝缘优劣最常用、有效的手段。本文分析了某公司300 MW发电机定子C相线圈和B相引线绝缘磨损故障,介绍了用高压预示查找故障点并进行定子线棒局部更换,局部修理引线绝缘的过程,总结了发电机故障诊断及其处理的经验和方法。     

外高桥发电广发电机定子绕组堵塞故障的早期发现

定子绕组采用水内冷冷却方式的发电机,由各种原因引发的定子绕组热故障,不但在发电机事故中所占比例较大,而且造成的经济损失惨重.介绍2007年5月外高桥发电厂3号发电机因小混床树脂颗粒直径太小且凝集力很强,在毛口处很容易形成堆积堵塞,导致4根线棒堵塞故障情况.该机装有的发电机故障诊断专家系统中的定子绕组温度指纹计算和动态阈值判断定子绕组热故障的功能,在开机过程中、有功功率为125 MW故障线棒槽内检温计温度为55～58℃(未超过现行规程规定的报警阈值)时早期报警,避免了重大事故的发生及其所带来的巨大的经济损失.     

A digital technique for stator winding protection of synchronous generators

This paper describes a digital technique for detecting internal faults in stator windings of synchronous generators. The technique uses positive- and negative-sequence models of the synchronous generator, and voltages and currents measured at the generator terminals. It does not need information concerning the machine parameters and is applicable to all types of generators, irrespective of their size. Fault discrimination characteristics and a digital algorithm based on the proposed technique are described. The performance of the proposed technique was evaluated using fault data generated by simulations using an electromagnetic transient program, EMTDC. Fault data were also acquired by subjecting a laboratory generator to internal and external faults. Results of the studies using simulated and experimental data are included in the paper. The results indicate that the proposed technique can detect faults including open circuits and faults that short-circuit windings of one phase.     

溪洛渡左岸电站定子绕组安装技术

详细介绍了溪洛渡左岸首台770 MW发电机定子绕组安装工艺.在借鉴三峡水轮发电机定子绕组安装经验基础上,重点阐述了溪洛渡左岸电站哈尔滨电机厂有限责任公司生产的定子绕组的结构设计及安装特点,同时,对安装遇到的难点进行了分析并给出了解决措施.经试验表明,安装后的机组各项技术指标均符合国家标准要求.这次成功的安装为百万千瓦机组定子绕组的安装积累了可行借鉴经验.     

水轮发电机定子绕组不对称支路电磁参数计算模型

为了探讨水轮发电机定子绕组不对称支路参数的计算问题,根据交流电机多回路理论,建立了绕组不对称支路参数计算的数学模型,给出了应用有限元方法计算绕组不对称支路参数的通用方法。通过对样机计算表明,该方法可用于任意线圈组合的电磁参数计算,且计算结果准确;绕组各支路电磁参数的不一致完全体现了各支路不对称程度,不对称支路间的环流损耗随绕组不对称度的增大呈指数关系增长;采用有限元方法进行不对称绕组支路电磁参数的计算,为支路不对称绕组的设计提供了依据,同时也为发电机绕组故障分析打下了良好的理论基础