汽轮发电机定子绕组匝间短路保护的必要性

长期流传的“汽轮发电机定子绕组同相同槽的线棒数量很少”的说法纯属传。文中分析了汽轮发电机定子绕组槽内分布情况及发生故障情况的原因,指出大型汽轮发民机定子绕组同相同槽的数量将近５０％,据此推论得出：汽轮发电机应装设定子绕组匝间短路保护。     

汽轮发电机定子绕组端部振动特性分析

以国产600 MW大型汽轮发电机端部结构为分析对象,对定子绕组端部的受力和振动特性进行了理论研究和实验分析。首先对端部结构进行简化,建立了定子绕组端部的数学模型,并利用镜像法和比奥-萨格尔定律计算得到了端部电磁力密度。然后分别计算并比较了在A相、B相、C相电流达到最大值时,A相绕组的线棒在不同位置处的径向、切向和轴向电磁力密度大小关系。最后分析了发电机负荷对端部电磁力密度的影响,并与大唐国际乌沙山发电厂实测的定子绕组端部振动数据进行了比较,与理论分析结果基本吻合。     

汽轮发电机定子绕组端部短路的分析（Ⅰ）

本文对16台汽轮发电机定子绕组端部短路事故进行了分析,提出了造成事故的主要原因和综合的防止措施。     

汽轮发电机定子绕组的更换技术

近几年多台国产QFS-125-2型发电机进入服役末期,发电机定子绕组故障明显增加,在无法局部修复时,需对定子绕组进行更换,并同步进行发电机组增容改造.通过对QFS-125-2型汽轮发电机改造的工作实践,从改造内容的确立到改造工序工艺要求作了介绍,提出改造中的关键点,对同类型机组的发电机定子绕组故障的更换处理或技术改造,具有现实的指导作用.     

汽轮发电机定子绕组端部短路事故的分析（Ⅱ）

4 事故原因分析4.1 发生励端引线与汽端水接头处事故原因的分析通过对事故情况的综合分析,事故原因就比较清楚。发生在励端引线与汽端水接头处的短路事故有很多是相似的。其为:(1)短路发生在高电位处。(2)短路点是绝缘相对薄弱的部位。(3)发生短路事故的机组存在油污严重湿度偏高的运行工况。(4)短路事故大部分发生在北方、寒冷季节、深夜或早晨及负荷较低的时候。说明与相对湿度偏高有关。     

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.     

清江水布垭电站发电机定子绕组主保护分析

针对清江水布垭电站46万kW发电机定子绕组结构及其综合差动主保护方式动作行为进行计算分析和评价,重点阐述了定子绕组匝间故障及分支断线时保护动作的灵敏度,指出该主保护方式优于其他组合主保护方式,现有保护定值个别之处有待商榷,保护仍有死区,保护动作原因综合分析较复杂.该文对大型水轮发电机的故障分析有一定的借鉴作用.     

A novel protection scheme for synchronous generator stator windings based on SVM

This paper proposes a novel scheme for detecting and classifying faults in stator windings of a synchronous generator (SG). The proposed scheme employs a new method for fault detection and classification based on Support Vector Machine (SVM). Two SVM classifiers are proposed. SVM1 is used to identify the fault occurrence in the system and SVM2 is used to determine whether the fault, if any, is internal or external. In this method, the detection and classification of faults are not affected by the fault type and location, pre-fault power, fault resistance or fault inception time. The proposed method increases the ability of detecting the ground faults near the neutral terminal of the stator windings for generators with high impedance grounding neutral point. The proposed scheme is compared with ANN-based method and gives faster response and better reliability for fault classification.     

Unconventional diagnostic methods for testing generator stator windings

This paper presented a comparison of different methods of measuring insulation resistance and tan delta (dissipation factor), and of documenting partial discharge activity. The measurements were made on several service-aged generators. The results for one in-service generator, obtained between service inspections, are discussed in detail. Comparing classical insulation resistance measurements and the dielectric response behavior in the frequency domain, good agreement is found. With the insulation time-constant, the dryness can be determined relatively. In the case of resin-impregnated insulation systems, additional investigations are required to determine the humidity absolutely. The determination of tan delta using various test systems and measuring methods was carried out on-site. Because tan delta is frequency and temperature-dependent, the results of series resonance circuit measurements must be modified by correcting for the difference between the measurement frequency and the power frequency. The results obtained using various PD-test systems depend on bandwidth and the circuit configuration. The multi-synchronous system has the significant advantages that the PD activity at several points can be monitored in one measurement, and the three-phase amplitude relation diagram makes it easy to identify the PD source. However, the calibration process is lengthy, so little time is saved overall, and a full set of quadripoles and coupling capacitors is needed for each channel.     

发电机定子接地保护的分析

本文介绍了发电机定子接地保护的种类、原理及应用以及对定子接地保护的要求,并针对发电机中性点接地方式的不同,具体分析了相应定子接地保护的原理、保护范围及配置特点,为其在大中型机组上安全有效的运行提供了重要的理论依据。最后介绍了孟加拉巴库现场定子接地保护的具体应用。     

俄800MW发电机定子接地保护分析

俄罗斯800MW机组бРЭ1301.01定子接地保护方案比较特别，整定办法复杂繁琐，加之俄罗斯说明书讲解不详，造成有些单位在没有定值整定书的情况下运行。本文结合国内外同类保护，介绍该保护原理、归纳整定办法，并对该保护的优缺点进行了分析，旨在指导现场生产人员学习、整定计算之用。     

发电机100%定子接地保护误动作分析

某电厂600MW机组在发电机空载试验时发生100%定子接地保护动作,经发现设计方案无法满足机组并网前继电保护要求。通过对原来设计方案和机组启动过程出现的问题进行了分析,找出问题的原因,并对原来的设计方案进行优化,对优化后的方案进行了调试,结果表明优化后的方案较好地解决了问题,满足了机组并网前后100%定子接地保护的要求。     

ANN-based novel fault detector for generator windings protection

In this paper, an artificial neural network (ANN) based internal fault detector algorithm for generator protection is proposed. The detector uniquely responds to the winding earth and phase faults with remarkably high sensitivity. Discrimination of the fault type is provided via three trained ANNs having a six dimensional input vector. This input vector is obtained from the difference and average of the currents entering and leaving the generator windings. Training cases for the ANNs are generated via a simulation study of the generator internal faults using Electromagnetic Transient Program (EMTP). A genetic algorithm is employed to reduce training time. The proposed ANN algorithm is compared with a conventional differential algorithm. It is found to be superior regarding sensitivity and stability     

大型汽轮发电机3次谐波电压定子接地保护方案的研究与改进

基于一台300 MW汽轮发电机的参数,对常用的3种3次谐波电压定子接地保护方案进行灵敏度对比分析。分析结果表明大型汽轮发电机采用接地变压器接地方式时,现有的3次谐波电压定子接地保护在定子绕组中部的灵敏度仍然不足。考虑现有3次谐波电压定子接地保护存在误动较多的问题,分析了导致发电机机端、中性点3次谐波电压变化的原因。在此基础上,提出一种改进型3次谐波电压变化量差动原理定子接地保护方案。该方案对机端3次谐波电压变化量进行校正后与中性点3次谐波电压变化量构成差动判据,可有效区分定子接地故障与发电机3次谐波电压的正常波动。该方案还根据高压侧3次谐波电压的变化量增加了浮动的保护启动门槛,避免因高压侧3次谐波电压变化而导致的误动。仿真结果表明所提方案理论正确,灵敏度较高,受机组运行变化状态的影响小。