在线时大型电机定子绕组绝缘状况的监测

定子绕组绝缘状况是决定大型电机使用寿命的重要因素。局部放电测量是诊断定子绕组绝缘状况最为有效的方法。在线时定子绕组局部放电监测，具有成本低、可信度高、实时性好等待点。本文论述了大型电机定子绕组局部放电在线监测装置的一般结构。作为一个例子，介绍了一实际在线监测采样装置，及它用于电机局部放电测量时的有关测试结果。     

在线时大型电机定子绕组绝缘状况的监测

定子绕组绝缘状况是决定大型电机使用寿命的重要因素。局部放电测量是诊断定子绕组绝缘状况最为有效的方法。在线时定子绕组局部放电监测，具有成本低、可信度高、实时性好等特点．本文论述了大型电机定子绕组局部放电在线监测装置的一般结构。作为一个例子，介绍了一实际在线监测采样装置，及它用于电机局部放电测量时的有关测试结果。     

大型电机局部放电在线监测技术及其基础研究

论述了通过在线监测电机内局部放电监测电机绝缘状况的重要意义，简要介绍了国外已应于用实际大型电机的几种局部放电监测方法，详细分析了电机内局放在线监测技术的难点，强调指出，加强有关的基础研究，开发智能型在线监测系统是发展和提高我国电机绝缘状况在线监测技术水平的关键问题。     

高压电机局部放电在线监测方法

局部放电在线监测是诊断高压电机定子绕组绝缘邦联的有效方法之一。文中概述了国外高压电机局部放电在线监测的几种方法：基于汇流环上成对耦合电容器的监测法,基于中线射频监测法,基于电机引出线上耦合器的监测法,基于定槽耦合器的监测法,基于埋城定子槽里的电阻式测元元件导线的监测法等。     

大型电机局部放电在线监测的方法研究

大型电机在电力系统各个生产部门起着关键的作用。而局部放电是发生在电机定子绕组上的常见故障,会造成绝缘的劣化,最终导致绝缘的击穿和短路事故。对局部放电的监测方法进行了整体概述,具体介绍了几种常用的在线监测局部放电的方法：成对耦合器监测法、中线射频监测法、定子槽耦合器监测法、引出线上耦合器监测法,同时介绍了各种方法的传感器设置,噪声的抑制情况。     

同步电机在线局部放电监测系统在宝应站的应用探讨

局部放电是电机绕组绝缘老化的一个重要原因,通过局部放电测量,可以有效地判断绕组绝缘状况,从而掌握电机绝缘性能。南水北调宝应站建设中引进了电机局部放电在线监测技术,首次在大型泵站实现了同步电机定子绕组在线连续局部放监测,有助于提高大型泵站同步电机绝缘监测水平,对保障机组安全运行及泵站运行管理将起到积极推动作用。     

局部放电在线监测及其在大型电机中的应用

长期以来，局部放电在线监测已是一种监测大型电机绝缘系统的有效手段。在线测试能在设备正常工作进行分析和诊断，根据测试结果可有计划地安排、实施正确的纠正方案。本文系统介绍了局放的基本理论、在线测试方法、与传统测试的关系、测试数据的解释以及采取的相应对策。     

局部放电在线监测系统在大型水火电机组上的应用

在离线的情况下模拟电机发生各种局部放电的状态，利用ICM monitor局部放电在线监测系统得到其放电量峰值和平均放电电流的直线棒图以及局部放电的特征图等，结合吉林白山发电厂在已运行了近10年的4号机组上安装ICM monitor局部放电在线监测系统及试验，通过多次实验所测得的第一手数据对发电机的绝缘状态进行了评定。     

基于超声法的大电机局部放电监测系统及其仿真验证

探索了一种新的监测大电机绕组绝缘质量的局部放电方法.介绍了一种基于超声法和虚拟仪器的局部放电实时在线监测系统,分析了系统组成原理和各部分功能.通过实验分析了局部放电超声波信号在大电机定子内的传播特性,以及该超声信号在发电机正常运行时弱噪声和强机械背景噪声下的传播区别.实验证明,利用超声波对大电机绕组绝缘局部放电进行监测是可行的,为实现局部放电故障点定位提供了前期准备工作.     

大型电机定子绕组绝缘的在线监测

定子绕组绝缘的在线监测可以有效地保障大型电机的安全、可靠运行,现阐述了国外在线监测的各种方法及发展动态,指出局部放电的测试是诊断大型电机定子绕组绝缘状态的传统的有效方法。     

Comparison of on-line partial discharge detection methods for HV cable joints

The capacitive coupler, acoustic emission (AE) sensor and radio frequency current transducer (RFCT) have been used to detect partial discharge (PD) activity within a 132 kV prefabricated cable joint containing a known defect. Although each of the three methods has been applied individually under different situations, a comprehensive investigation and comparison of these three methods has not yet been made. Results obtained were compared to measurements made using the conventional electrical detection method. The quantification of the capacitive coupler measured signal in mV with a discharge apparent quantity in pC has been investigated and an on-line quantification method proposed. The capacitive coupler has good detection sensitivity and PD location can be realised by studying the time of Right between signals from two sensors. The difference in pulse shape, spectrum and time of flight between an internal discharge and external interference has been investigated. The AE approach has the advantage of being free from electrical interference. However, investigation indicated that AE signals were significantly attenuated within the cable joint. RFCTs were used to detect the discharge current flowing through the cable sheath. Where the detection sensitivity was low, a wavelet de-noising method was applied to process the RFCT signals and proved to tie effective in increasing the measurement signal to noise ratio.     

基于声电联合及振动的变压器类设备局部放电现场综合诊断方法

根据变压器和高压电抗器等设备结构及运行情况,利用特高频法、超声波法和振动法开展现场局部放电带电检测,对基于声电联合及振动带电检测的变压器类设备局部放电现场诊断方法进行了研究。以某500 k V线路高压电抗器为例,提出现场检测实施方法和信号分析、缺陷诊断方法。所提综合诊断方法有助于判断变压器和高压电抗器局部放电并诊断其缺陷类型及严重程度,提升了设备局部放电缺陷特别是较为严重的悬浮电位放电缺陷的现场检测水平。     

Understanding surface partial discharges in HV coils and the role of semi-conductive protection

An electrical insulating system in high voltage rotating machines is subjected to several stresses that cause changes of material properties during its lifetime. This phenomenon reduces progressively ability of the insulation to withstand the service stresses. Internal partial discharges can be located inside the high voltage insulation and usually they are dangerous for life-cycle duration. Surface discharges are generated at the solid/air interface in the gaps of machine stator slots or at the slot exits. Surface discharges can cause more intensive deterioration of the insulation, accelerate aging processes and definitively take aim toward premature failure of the machine. The application of conductive or semi-conductive protection layer provides certain protection for solid insulation from these discharges. Semi-conductive corona protection tapes are used on the coils at the slot exit region to electrical field control and prevent surface discharges. Laboratory measurements of the surface partial discharge quantities in specimens of high voltage coils with mica insulation were performed. The aim of the paper is to describe theoretically the development of surface discharges in rotating machines and to present surface partial discharge development in HV motors when semi-conductive layer protection is missing. The results can be found useful to understand better the surface discharge development and importance of high-quality semi-conductive protection technology.     

发电机局部放电甚高频在线监测现场试验分析

笔者研制了发电机局部放电甚高频在线监测系统,该系统基于双传感器定向耦合的原理进行信号采集,利用数字脉冲逐个识别技术通过软件来实现干扰抑制。结合在四川龚嘴电厂、福建池潭电厂等地的现场实验分析,验证了该系统的测试效果及其抗干扰能力。通过对某电厂发电机连续在线监测及故障预警的分析,证实了相比单一的放电量分析,采用统计参数趋势分析的方法能够更有效地反映发电机放电变化趋势。     

Partial discharge diagnostics for gas insulated substations

A defect such as a free metallic particle or stress-raising edge on an electrode could lead to breakdown in a gas insulated substation (GIS), but may be detected by the partial discharges it generates. Of the various detection means available, most success has been achieved with either acoustic transducers to detect sound waves from the discharge, or electrical couplers to pick up the ultra-high-frequency (UHF) signals generated inside the GIS chambers. All new GIS in the UK are fitted with internal couplers for UHF monitoring, and two examples of continuous monitoring schemes on 400 kV GIS at nuclear power stations are described. Further developments, which are already well advanced, include specifying and measuring the coupler characteristics, making use of expert systems to interpret the UHF discharge data, and extending the monitoring system to include the performance of circuit breakers and other equipment     

两种发电机绝缘监测方式的应用和可靠性探讨

介绍目前应用广泛的两种发电机定子绝缘在线监测手段,结合国华台电3~4号发电机故障的分析以及对安装在发电机内部的两种在线监测装置的监测数据的比较,对无线电频率在线监测和局放在线监测两种手段的有效性进行了综合评价。     

Dielectric windows for UHF partial discharge detection

Increasing the permittivity of the propagation medium inside a hollow tube lowers its cut-off frequency, allowing it to transmit a wider range of signal frequencies. This principle is applied to the design of dielectric windows that can be used to facilitate partial discharge (PD) detection at ultra high frequency (UHF) in a HV metalclad plant such as gas-insulated substation (GIS), power transformers and circuit breakers. External UHF couplers mounted on such windows can be removed or replaced without compromising the integrity of the insulation system. By increasing the signal power level incident on a window-mounted external UHF coupler, higher sensitivity to PD can be achieved. The problem is analyzed using waveguide theory and, using GIS as an example, improvements of ≈6 dB are demonstrated by means of coupler sensitivity measurements and experiments using PD sources     

变压器多参量在线监测集成系统的开发和应用

基于即插即用思想研制了一套变压器多参量综合在线监测系统。该系统能够在统一的软硬件结构下动态添加删除监测对象和监测参量而无需对系统本身进行改动,方便地扩展为多个变电站、多台变压器的综合在线监测网络;能够实时监测变压器中性点局部放电、局部放电超高频信号、油色谱、铁芯接地电流和顶层油温等状态参量。应用该系统对330 kV变压器进行现场连续在线监测,数据显示局部放电和油色谱数据能够同时反映变压器内部局部放电变化,局部放电超高频对单次局部放电监测具有较高灵敏度,铁芯接地电流在正常范围内波动,顶层油温处于正常范围。表明该系统能够及时全面反映运行变压器绝缘状态。