电容型设备绝缘在线监测的研究

本文论述了在电力系统中电容型设备绝缘在线监测的方法，介绍了一种新的测量装置。同时，通过该装置在现场的实际运行，总结出运行中设备绝缘状态判断的新观点。     

气体绝缘组合电器现场试验现状与发展

为了诊断现场气体绝缘组合电器(GIS)绝缘状况，需要对GIS进行现场绝缘试验。阐述了对GIS进行现场交流耐压试验的基本方法，并讨论了传统的局部放电测量方法，综合分析GIS现场绝缘试验的有效性和存在问题，指出交流耐压试验配合灵敏的局放测量是有效的现场试验方法。选择可行的局部放电在线监测系统，还可以实现实时掌握绝缘运行状态。     

电容型设备绝缘在线监测与诊断技术综述

传统的定期检修已不能满足高压输变电设备安全运行的要求，以状态检修代替定期检修已成为电力系统设备检修的必然趋势。实时的绝缘监测及诊断技术是状态维修的基础。电容型设备在变电站中具有重要地位，因而对其绝缘状况进行在线监测具有重要意义。本文介绍了电容型设备在线监测的具体内容(如在线监测信号的提取和介损数字化测量等)，电容型设备在线监测和诊断技术的研究现状与应用状况，并就其存在的问题和对今后的技术发展提出了建议。     

大型地下变电站GIS现场绝缘试验的方法与实践

根据大型地下变电站的特点,SF6气体绝缘的试验电抗器是GIS耐压试验的理想设备;实践结果表明交流耐压试验配合灵敏的局放测量,是地下变电站GIS最有效的现场绝缘试验方法。分析了传统局放测量方法,提出超高频局放检测系统具有较高的灵敏度。     

气体绝缘开关设备局部放电特高频在线监测技术及应用

分析了各种气体绝缘开关(gas insulated switchgear,GIS)局部放电检测方法,认为特高频(ultra high frequency,UHF)法抗干扰能力较强,检测效率较高,可实现在线监测、故障模式识别及定位。以一起UHF在线监测系统发现的GIS设备缺陷为例,分析并总结运行经验。运行经验表明,对连续性的局部放电信号要重点关注,应监测24 h局部放电的发展情况,必要时利用便携式设备进行复测,排除现场干扰,确定故障位置,进行解体处理。通过安装GIS设备局部放电UHF在线监测系统,可发现GIS设备隐患,有效保证电力系统的安全稳定运行。     

新型的电缆局部放电在线监测系统研究

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。     

安装在马来西亚的GIS局放试验的技术和经验

马来西亚的GIS在运行和现场试验期间的故障统计结果不能令人满意，主要特点是为数众多的绝缘故障。必须介绍的是严格的质量控制程序和有效的测试方法。在现场试验中基于局放测量的诊断方法已成为必做项目。一个关键(重要)的变电站已配有在线的超高频局放监测系统。所有运行中的GIS的绝缘状况已用超声局放测量进行了确认。所有介绍的诊断方法都是基于新型的高灵敏度探测仪及先进的计算机辅助分析系统。     

基于地电波检测法的非侵入式高压开关柜局部放电监测定位研究

在分析TEV技术原理的基础上,研制一套基于测量开关柜表面地电波来监测开关柜内部局部放电及定位局部放电源的非侵入式高压开关柜局部放电监测定位系统。使用该系统进行了实验室测试和现场变电站内开关柜的局放实测,并综合应用TEV技术对高压开关柜典型缺陷的局部放电进行了检测与分析,测试结果表明该系统功能完备、安全可靠、性能优良、操作方便,总体功能及性能参数满足高压开关柜非侵入在线局部放电监测的应用需求。     

便携式高压设备绝缘测试仪

用于诊断高压设备绝缘状态的便携式智能型高压设备绝缘测试仪由天津电力试验研究所研制成功,并通过专家鉴定.该仪器以先进的8031单片计算机为核心,扩展了存储器、计数器、键盘显示电路及微型打印机等,并与有关模拟和数字电路构成智能仪器.具有测量精度高、运算速度快,操作灵活方便等特点.其测量、计算、显示等均自动完成.该仪器主要适用于110kV至500kV高压电气设备绝缘在线监测.在现场实际测试中,具有较强的抗干扰能力,测量数据准确可靠,测量参数选择合理,满足有关规程的规定.     

分散式绝缘在线监测

介绍了对多个变电站的一次设备的绝缘参数进行分散式监测及变压器局部放电的在线监测。结果表明，分散式绝缘监测是可行的，其测量精度符合现场测试要求。     

在线局部放电监测技术的实际应用

局部放电测量装置价格高 ,安装局部放电传感器和对结果进行解释的困难妨碍了它的广泛应用。通过 5年的研究开发和广泛的工业应用 ,工业研究公司(TRL)进行的快速非侵入性在线局放测量可使工业界通过有效经济的预言以及状态检修来保护它们的主设备     

Cost-effective on-line partial discharge of measurements for cables

On-line partial discharge (PD) measurements are an efficient method for detecting certain insulation defects of cables. These include defects in cable joints and terminations, and defects due to mechanical impact. Noninvasive, efficient, and widely applicable, portable on-line PD measurement techniques are strongly favored by the electricity industry. Three on-site PD measurements for cables are described in this article to illustrate how the techniques achieve cost-effective insulation diagnosis to protect the main assets.     

A novel wavelet transform technique for on-line partial discharge measurements. 1. WT de-noising algorithm

Medium and high voltage power cables are widely used in the electrical industry with substantial growth over the last 20-30 years ago, particular in the use of XLPE insulated systems. Ageing of the cable insulation is becoming an increasing problem that requires development of reliable methods for on-line condition assessment. For insulation condition assessment of MV and HV cables, partial discharge (PD) monitoring is one of the most effective techniques. However on-site and on-line PD measurements are affected by electromagnetic interference (EMI) that makes sensitive PD detection very difficult, if not impossible. This paper describes implementation of wavelet transform techniques to reject noise from on-line partial discharge measurements on cables. A new wavelet threshold determination method is proposed with the technique. With implementation of this novel de-noising method, PD measurement sensitivity has been greatly improved. In addition, a full AC cycle data recovery can be achieved instead of focusing only on recovering individual PD pulses. Other wavelet threshold de-noising methods are discussed and examined under a noisy environment to compare their performance with the new method proposed here. The method described here has been found to be superior to the other wavelet-based methods     

Fundamentals in computer aided PD processing, PD patternrecognition and automated diagnosis in GIS

The partial discharge (PD) measurement is a sensitive method for testing and monitoring the insulation condition of HV apparatus. Digital PD measurements have become state of the art. Computer-based PD diagnostic systems nowadays can be used to increase the reliability of modern gas-insulated system (GIS). Also on-line monitoring of HV equipment is becoming increasingly important to enable prevention of a sudden breakdown of PD affected components. On-line monitoring must be done on-site, but an important problem of on-site PD measurement is the superposition of PD data and interference. Furthermore, reliable recognition of the type or nature of the insulation defect is necessary for any risk assessment. Traditionally, this is achieved with reference to expert knowledge. An alternative approach is presented in this paper, which treats the fundamentals of automated computer-based PD diagnosis, taking into account that successful noise suppression is essential for a successful on-site diagnosis     

A novel wavelet transform technique for on-line partial discharge measurements. 2. On-site noise rejection application

For pt.I see ibid., p.3-14, (2007). Insulation assessment of HV cables requires continuous partial discharge (PD) monitoring to identify the nature of insulation defects and to determine any degradation trends. However to recover PD signals with sufficient sensitivity to determine such insulation degradation in substations with high levels of electromagnetic interference is a major challenge. This paper is the second of two papers addressing this challenge for on-line PD measurements in a noisy environment. The first paper described a wavelet transform-based method of interference rejection. This paper applies that method to the problem of on-site testing, using both laboratory tests and on-site tests. The laboratory tests were used to stimulate the noisy on-site testing environment, with use of transient pulse-like noise, discrete spectral interference (DSI) and white noise. These noise types have been successfully rejected by the method proposed in the first paper. In addition, on-site tests have been undertaken and have been able to detect PD signals in an old 11 kV substation multi-cable installation     

XLPE电力电缆综合绝缘诊断策略研究

长久以来,有关交联聚乙烯(XLPE)电缆绝缘现场试验或诊断被清晰的分为离线和在线两类,绝缘监测目标也往往以针对电缆本体或针对电缆附件区别对待。本文第一次提出针对电缆整体,在电缆整个运行期的综合绝缘监视方法,同时提出以在线监测为主,离线绝缘诊断为辅的综合绝缘评价策略,论证了推行这种策略的必要性。     

A new adaptive technique for on-line partial discharge monitoring

The insulation system of HV apparatus deteriorates due to partial discharges (PD). PD tests are carried out successfully in shielded laboratories to verify the insulation quality and to rectify defects left during the manufacturing process. A variety of techniques exists for this purpose. It is also desired to monitor the insulation when equipment is in operation. Unfortunately, the performance of PD test equipment is adversely affected by interference signals. The sinusoidal signals of low and high frequency, due to their correlation, make the measurement difficult and sometimes even impossible. This paper describes the design of an adaptive digital filtering technique and its successful application to the on-line/on-site detection of PD current pulses generated in HV insulation in the presence of sinusoidal noise signals. The technique is based on Wiener optimal filtering theory and its characteristics are investigated. The adaptive filter of this system has a time-varying response and is self-tuning to each low and high frequency noise component. The filter remains active until the signal-to-noise ratio is significantly increased and it can be used for weak PD pulse integration. Theoretical background of the technique and the results of laboratory and field tests are presented     

750 kV变压器现场工频感应耐压和局部放电试验

介绍了我国750 kV输变电示范工程中变压器现场局放交接试验的标准、程序和过程,分析了局放起始电压和熄灭电压定义中的含混之处,比较了750 kV变压器的工频耐压值和局放试验电压值、分析了局放试验中经常出现的问题。提出如下建议：①提高750 kV变压器的工频绝缘水平;②放宽变压器局放现场交接试验标准至1 000 pC;③重新定义局部放电起始电压和熄灭电压;④加强现场实用技术的研究;⑤试验人员持证上岗;⑥试验仪器定期校验;⑦必要时采用在线监测。这些建议不限于750 kV变压器,也可为 1 000 kV变压器的现场局放交接试验参考。     

Ultra-wide-band PD diagnostics of power cable terminations in service

During the past decade the PD probing in the ultra-high frequency (UHF) range has successfully been proven for on-site PD diagnostics of GIS cable terminations in service. Therefore it was decided to apply this non-conventional method also for condition assessment of the insulation integrity of outdoor cable terminations. In order to evaluate the minimum detectable PD level the paper deals with comparative PD studies using the IEC and the UHF method. Moreover, experimental studies on the attenuation of PD pulses traveling through power cables were performed in order to assess the spatial selectivity of the UHF method applied.     

基于ARTNN的GIS绝缘故障识别新方法

为根据局部放电信号识别早期的GIS绝缘故障缺陷类型,提出了一种利用ART神经网络在线识别GIS绝缘故障类型的新方法。较之常用BP神经网络,该法训练时间短、所需样本少、权值稳定、不存在局部收敛,故更适于在线识别。网络的输入量为一个工频周期内局部放电脉冲重复率、主频率、阻尼系数、放电量、放电相位分布。利用5种GIS绝缘缺陷类型的实验所得数据对ART神经网络进行训练及验证,证明该法的缺陷类型正确识别率可>98%,在GIS绝缘故障类型的在线模式识别中具有广泛的前景。