一起电容式电压互感器油箱过热故障的分析

文章对一起电压互感器油箱过热故障进行了分析,通过对该故障CVT的检查、试验和解体分析,确定了引起油箱过热的原因,主要是因为阻尼器中电容器被击穿,失去了谐振条件,导致电容单元电流增大,使电压互感器底部油箱的温度上升。文章还给出了预防该类型故障的反事故措施。     

对一起电容式电压互感器过热故障的综合诊断

由于电容式电压互感器结构原因,易发生因电磁单元故障引发的过热故障。介绍了电容式电压互感器的结构原理,针对一起运行中电容式电压互感器电磁单元引起的过热故障,提出了以红外检测技术和绝缘油色谱分析技术相结合的方法来进行故障诊断,得到了较好的效果,并对电容式电压互感器的现场检测和故障诊断提出了建议。     

肇庆换流站110 kV换流乙线CVT故障分析

对肇庆换流站站用电系统换流乙线CVT电磁单元过热故障进行检查和分析,通过对分压电容器电容量测试、电磁单元油色谱试验、电磁单元阻尼器阻尼伏安特性测试确定阻尼器异常,并通过吊心检查及阻尼电容器解剖进一步确定阻尼电容器击穿,阻尼器L、C谐振破坏导致阻尼电阻长期过负荷引起发热。同时对国内CVT常见问题进行归纳和汇总,并对CVT运行维护提出了建议。     

500kV电容式电压互感器电磁单元过热故障分析

针对电容式电压互感器故障真实案例,通过红外测温、故障录波、油化试验和解体检修等方法,对电容式电压互感器电磁单元过热故障的原因进行了深入分析,找到了导致电容式电压互感器电磁单元过热的根本原因,并基于此次故障分析,给出了在实际运行和检修中关于电容式电压互感器的建议。     

肇庆换流站110kV换流乙线CVT故障分析

对肇庆换流站站用电系统换流乙线CVT电磁单元过热故障进行检查和分析，通过对分压电容器电容量测试、电磁单元油色谱试验、电磁单元阻尼器阻尼伏安特性测试确定阻尼器异常，并通过吊心检查及阻尼电容器解剖进一步确定阻尼电容器击穿，阻尼器L、C谐振破坏导致阻尼电阻长期过负荷引起发热。同时对国CVT常见问题进行归纳和汇总，并对CVT运行维护提出了建议。     

一起220kV电容型电压互感器故障的原因分析及防范措施

某220 kV变电站一台220 kV电容式电压互感器故障后,对故障的原因进行了初步分析,同时对全省在运的同厂家产品进行了排查。根据排查结果,选取了一台具有代表性的设备进行了解体检测,发现由于电磁单元中间变压器硅钢片材料选用和设备制造工艺把关不严,设备存在中间变压器硅钢片锈蚀及漆膜脱落等质量缺陷,引起电磁单元局部过热、内部绝缘老化。同时,设备电磁单元密封不严,严重受潮,加剧了电磁单元内部绝缘老化。并根据故障原因分析结果提出了相应的防范措施。     

GIS过热案例分析及回路电阻检测方法探讨

GIS设备过热故障原因主要有导体连接部位螺栓松动、电弧灼伤、弹簧疲劳、接触面积减小等造成接触电阻增大,温度急剧升高,导体或紧固件熔化导致设备短路故障。在分析几起GIS设备过热故障、异常案例的基础上,评估了回路电阻检测、气体分解物测试、局部放电检测等几种方法对于GIS过热故障前预防、故障后定位的应用效果,认为回路电阻检测对于发现各种原因导致的GIS过热缺陷最为直接有效。经模拟实验辅助验证,证明了该方法的有效性,并对GIS设备回路电阻检测提出了相关建议。     

双馈异步发电机定转子绕组过热故障监测方法

双馈异步发电机(DFIG)在长期运行中很容易发生定转子绕组过热故障。以绕组温度为研究对象,在分析绕组过热故障成因的基础上,分别从电机热性能和参数辨识两方面进行检测。使用参数辨识法时,首先利用电机电磁数学模型辨识定转子绕组电阻,再根据电阻与温度之间的关系计算定转子温度,从而判断绕组是否过热。最后基于MATLAB软件仿真验证了定转子绕组参数辨识法的正确性,为DFIG诊断绕组过热故障提供理论支撑。     

35kV电容式电压互感器的过热故障分析

针对一起红外测温发现的35kV 电容式电压互感器电磁单元过热故障,结合电容式电压互感器结构及工作原 理,通过现场检查、解体检查及试验,发现是电磁单元阻尼器回路损坏导致的发热故障,提出了处理建议及 预防措施,为同类故障的分析处理预防提供了参考.     

浅析变压器的瓦斯保护

变压器故障一般分为内部故障和外部故障两种。所谓内部故障,就是指变压器油箱内所发生的故障,如线圈的相间短路、单相接地短路、单相层间短路以及铁心烧坏等。变压器的内部故障如不及时排除,就有引起油箱爆炸的严重危险。变压器内部故障时,由于短路电流和电弧的作用,使附近的绝缘物分解而产生气体,同时由于气体上升会引起油流的变化。利用这个特点构成的保护称为瓦斯保护,或称气体保护。l瓦斯保护的结构瓦斯保护主要由瓦斯继电器构成,它装在变压器油箱和油枕的联接管道上。目前我国采用的瓦斯继电器有3种型式：浮筒式、挡板式和开口…     

500kV电容式电压互感器暂态特性仿真

电容式电压互感器(CVT)作为电力系统一次侧输入电压的传感设备已得到广泛运用,其性能好坏会直接影响到继电保护、故障测距、监控等二次侧设备的正常工作。当系统发生故障时,由于CVT中含有电容及电感类的储能元件,因此其二次侧输出电压不能跟踪一次侧输入电压的变化,暂态过程可能延续数十ms,从而造成快速保护动作延迟,甚至出现不正确动作。为此,结合500kV电压等级的CVT实际参数值在Matlab/Simulink中搭建了该电压等级CVT的仿真模型,比较详细地研究了其暂态特性,分析了不同因素对暂态过程的影响,并基于仿真数据分析了暂态过程的变化规律。仿真结果表明不同故障时刻、不同电路参数时的暂态过程有很大的差异。该仿真结果对于设计实际产品、优化产品性能具有很大的实用价值。     

外置床受热面防磨技术及应用

针对300 MW等级CFB锅炉机组外置床受热面存在的磨损、爆管、超温等现象,分析了外置床受热面的磨损机理及原因,提出了管卡结构优化、检修工艺优化、监测外置床受热面管束出口汽温、热强度高的管子绝热保温等防磨、防超温措施。介绍了600 MW CFB锅炉机组外置床设计结构,并将300 MW等级CFB锅炉机组外置床的成熟防磨技术应用于600 MW等级CFB锅炉机组,提高了机组的可靠性,取得了较好的效果。     

基于特征气体分层特性的电力变压器故障诊断技术研究

随着电网的扩大,变压器在电网中的作用日益提高,从而变压器在线故障诊断技术也显得异常重要。分析了变压器常见的故障类型以及变压器故障与变压器油产生特征气体的对应关系;选出具有代表性的特征气体作为最优诊断特征量;将故障诊断过程分为三个层次：正常-故障层、过热-放电层和故障细化层（高温过热、中低温过热、低能量放电、高能量放电）;最后用互信息方法与神经网络法实现基于特征气体分层特性的变压器故障诊断方案。     

Observations from measurements of the furfural content of oil samples from transmission transformers

The concentration of the chemical furfural in transformer oil is well known to be an indicator of the extent to which the paper insulation of the windings has deteriorated. However, the majority of publications on this topic are based on small-scale laboratory investigations with very little on field experience with power transformers. This paper reports on the analysis of data on the concentration of furfural in oil samples from 310 transmission transformers. The data showed that while high furfural concentrations (FC's) tended to occur in older transformers, there was no distinct trend. This, together with the lack of an upward tendency for the FC in cases where two readings were taken several months apart, indicated that the deterioration in paper strength and the associated increase in FC, occur in occasional and discrete steps. The model proposed is that these step-changes are due either to internal faults causing extreme local overheating, or to overloading of the transformer causing general overheating. A simulation based on these criteria gave a similar pattern of FC versus service age. Overall the results indicated an upward trend of log(FC) versus length of service but with very large scatter and with clustering by manufacturer. It was clear that the majority of transformers show negligible deterioration even after 20 years in service. This is in agreement with the above scenario. There was reason to believe that transformers located in industrial areas were likely to have been overloaded during the 1980s, so an analysis by locality was done. This showed that the percentage of transformers with high (>4 mg/l) FC's in nominally industrial areas was double that of the rest. This difference, although suggestive, proved not to be statistically significant. The model described indicates that, because of the auto-catalytic nature of the process, oil changes would be beneficial where the FC level exceeds 4 mg/l: less deterioration will occur when the transformer is overloaded.     

可靠性技术在汽轮发电机故障诊断中的应用

本文提出了可靠性分析技术应用于汽轮发电机现场故障诊断的方法，旨在准确识别故障。文中给出了该方法在汽轮发电机轴承油膜振荡故障和静子线圈过热故障诊断中的应用实例。     

采用电流突变量夹角余弦的直流电网线路纵联保护方法

直流线路的保护是多端柔性直流电网发展面临的关键问题之一。文中针对现有纵联电流差动保护存在的问题,提出了一种采用电流突变量夹角余弦值的纵联保护方法,它利用线路两端电流突变量计算夹角余弦值从而进行区内、外故障判断。区内故障时,线路两端电流突变量方向相反,夹角余弦值为负值;区外故障时,线路两端电流突变量方向相同,夹角余弦值为正值。保护方法采用改进电压梯度法快速启动,并利用正、负极电压比值来识别故障极。仿真表明,所提出的保护方法不仅可以可靠识别区内、外故障,同时具有较强的耐过渡电阻能力且不易受线路分布电容电流的影响。     

一起大型换流变压器潜伏性故障发现与处理

通过对一起利用油中溶解气体分析、调整运行方式、电气试验等手段综合诊断分析换流变压器(以下简称“换流变”)潜伏性过热故障过程分析,并经解体检查确认了故障原因,验证了本次通过油中溶解气体分析和调整运行方式诊断换流变压器潜伏性过热性故障的有效性和可行性,为后续换流变压器的类似潜伏性故障运维检修提供可借鉴的经验。     

Application of common transformers faults diagnosis methods on biodegradable oil-filled transformers

Due to environmental concerns regarding the use of mineral oil, biodegradable oil is increasingly being used as an alternative dielectric fluid. This paper presents results of experiments performed in the laboratory on the use of biodegradable oils for transformer application. The investigations cover two important diagnostic techniques for insulation assessment: (i) an investigation of partial discharge (PD) activity and characteristics in such oils and (ii) an investigation of the standard hydrocarbon dissolved gas products produced due to transformer faults. The fundamental aim of the investigation was to provide information as to whether the existing analysis techniques of PD fault pattern recognition and dissolved gas analysis methods, developed for mineral oil, are valid when used for insulation assessment with biodegradable transformer oil. The experiments were conducted on test samples to simulate three common types of transformer faults: low-energy PDs, high-energy arcing/sparking, and overheating. For the purpose of comparison, the same tests were performed using a mineral oil (Shell Diala MX) and a biodegradable oil (Envirotemp FR3). Also, each oil type was tested at three different moisture levels and with or without the presence of solid insulating materials (pressboard). PD activity was monitored using the standard IEC60270 phase-resolved analysis method. The fault gases produced were extracted and analysed by standard gas chromatography methods. Test results indicate that the PD phase resolved patterns are, in general, similar for the two oil types and thus existing PD pattern interpretations can be used to distinguish different types of PD faults, e.g. corona versus surface discharges. However, the values of various discharge quantities (PD magnitudes, repetition rate, current, etc) are very different under the same test condition. The quantities and the trend of dissolved gases for faults in biodegradable oil are substantially different compared with mineral oil. For the PD fault, biodegradable oil was found to release only a limited number of gases. For arcing and overheating faults, the main key gas produced is different between the two oils. Also, the presence of cellulosic materials such as pressboard influences the extent of hydrocarbon gases dissolved in the oil. It was found that for biodegradable oil, fewer amounts of gases are produced as the oil gets wetter.     

220kV GW6型隔离开关导电回路过热故障分析及处理

针对近年来某电站220kV GW6型隔离开关多起导电回路过热故障,通过对过热部件的试验、分解检查和分析,发现导电回路接触部位的表面处理工艺缺陷以及接触面配合尺寸的偏差是引起该结构隔离开关局部过热故障的主要原因,提出了导电接触面防氧化处理和采用双面镀锡铜导电带进行补偿的解决方案,通过实施该方案后的设备实际运行状况良好。     

基于轻量AlexNet的电容型电压互感器故障诊断

电容型电压互感器（CVT）是重要的一次侧电压监测元件。针对环境温度、湿度以及元件老化等因素造成的电容型电压互感器一次侧电容上下臂击穿或互感器二次侧短路等故障,提出了一种基于轻量AlexNet的电容型电压互感器故障诊断方法。该方法利用Matlab建立了CVT电路模型,分别对高压臂电容击穿、低压臂电容击穿以及互感器二次侧短路3种典型的故障进行仿真。采集CVT二次侧电压数据,利用马尔可夫变迁场将其转化为特征矩阵,最后使用轻量化的AlexNet神经网络对电压特征矩阵进行故障分类。仿真实验证明,所提方法在不拆除CVT的情况下,能准确检测出CVT的故障类型。