变压器直流电阻不平衡系数超标原因分析

针对步桥220 kV变电站4号主变压器施工期间线圈直流电阻不平衡系数超标问题,从高压线圈、高压引线、套管、分接开关等部件对线圈直流电阻的影响进行分析,判断出故障缺陷位置。采用排除法,结合施工现场实际情况,对故障缺陷予以消除,并对施工方法提出若干建议。试验结果表明:缺陷处理后,变压器高压线圈及引线直流电阻测试值趋向平衡,满足规程规定的要求。     

两起220kV变电站主变压器跳闸故障分析

针对某220 kV变电站连续发生的两起主变压器跳闸故障,根据故障信息及相关试验结果进行分析,找出导致主变压器跳闸的原因,提出对树脂浇注式电流互感器在投运前开展局部放电检测,在中性点非有效接地系统推广接地转移技术等措施。应用结果表明:改进措施有效防止了因树脂浇注式电流互感器主绝缘击穿导致的主变压器跳闸故障的发生。     

220kV变压器⁃套管体系抗震性能的数值模拟分析∗

为了进行高压变压器-套管体系抗震性能的数值模拟分析,并进行高压变压器-套管体系地震动模拟振动台试验方案的初步设计,针对OSSZ11-240 000/220 型变压器,采用ABAQUS 软件建立了变压器-套管体系的有限元分析模型,模拟了其自振特性和关键部位地震响应。在模拟结果的基础上,分析了变压器油箱顶板刚度对套管抗震性能的影响、套管根部的动力放大系数、以及套管地震响应的特点等。结果表明： ①变压器油箱顶板刚度较低会降低套管的自振频率,放大其地震响应,同时,油箱顶板上多个套管间的动力相互作用会改变其地震响应;②高压套管根部的动力放大系数最高达5.17,远大于规范推荐值;③缩尺模型与原模型模态和动力分析结果的对比验证了缩尺模型的合理性。建立的有限元方法可用于高压变压器—套管体系抗震性能的数值仿真分析、以及制定高压变压器—套管体系地震动模拟振动台试验的初步方案。     

银川东750kV变电站的电容型设备绝缘状态在线监测

为了保证银川东750 kV变电站电气设备安全、稳定运行,采用了先进的信号及测量技术、相位测量基准获取技术,建立了电气设备绝缘状态在线监测系统。实现了对750 kV主变压器套管及主变压器高、中压两侧CVT的在线监测。运行结果表明:在线监测系统各项指标达到了对电容型设备绝缘状态进行实时监测的技术要求。     

换流变压器阀侧套管充气及压力检测装置的研制

由于灵州换流站 ABB供货的换流变压器阀侧套管没有可观测的密度表计、没有专用的补气口,密度继电器的校验、SF₆气体湿度和分解物检测、套管实际压力检查需将密度继电器从套管上拆除,容易造成密度继电器连接处密封圈损坏,直流套管漏气,影响直流系统的安全稳定运行,针对此问题研制了换流变压器阀侧套管气体充气及压力检测装置,旨在解决站内换流变压器阀侧套管实际压力监测及补气困难的现状。     

变压器差动保护校验自动计算模块的开发应用

针对主变压器差动保护校验时计算复杂且容易出错的情况,以南瑞RCS-978主变压器差动保护为例,对目前广泛应用的两种典型主变压器差动保护校验方法进行分析,开发了基于EXCEL的主变压器差动保护校验自动计算模块。应用结果表明:该自动计算模块减少了差动保护校验的复杂性,提高了差动保护校验的正确性和效率。     

超高压大型变压器铁心故障诊断的试验研究

为了准确地判断大型变压器铁心故障点的位置,对一起超高压大型主变压器缺陷的诊断试验过程进行了研究。在国内首次将变压器铁心接地电流长时间高采样率的波形分析应用到变压器故障诊断和状态评价中,并综合局部放电、油色谱等试验结果进行故障分析判断。结果表明:变压器铁心接地电流长时间采样能够准确判断设备接地电流型故障。     

主变压器通风电源切换故障率高的原因分析

针对国电大武口热电有限责任公司 3 号主变压器通风电源切换故障率高的问题进行分析,找出故障原因并对 3 号主变压器通风电源回路进行了改造。结果表明:主变压器强制通风联锁条件不可靠、联锁回路辅助接点接触不良、交流电源开关与低压脱扣线圈机械配合不好是引发故障的原因。通过主变压器联锁回路的改造和更换部分设备,大大提高了 3 号主变压器通风电源切换的可靠性,收到了良好的效果。     

220kV变压器高压套管发热问题的分析与处理

结合金凤220 kV变电站1号主变C相中压套管发热问题的案例,介绍了该台主变高压套管发热问题的原因与处理过程。通过对高压套管的解体及红外热成像检测的综合分析,确定了造成高压套管发热及最初影响检修人员对发热部位误判的原因,对此类问题的分析与处理提出了具体的建议,可提高运行设备的可靠性。     

220kV主变压器冷却器全停告警原因分析及处理

针对一起 220 kV 强迫油循环风冷式主变压器冷却器全停事故,对故障原因进行分析,提出了提高冷却器工作电压和调整电压监视继电器整定值的改进措施。应用结果表明:该措施稳定了主变压器冷却器的工作电压,消除了导致冷却器全停的事故隐患,确保了主变压器的安全、可靠运行。     

超声波局部放电检测在GIS自由颗粒缺陷检测中的应用

气体绝缘金属封闭开关(gas insulated switchgear, GIS)设备内部自由颗粒缺陷对GIS设备安全稳定运行构成较大危害,通过对GIS自由颗粒特性进行分析,提出采用超声波局部放电检测技术检测GIS中自由颗粒缺陷的方法。应用结果表明:超声波局部放电检测能有效检测出GIS设备内部自由颗粒缺陷,提前发现潜伏性缺陷,保障设备安全运行。     

GIS内置式特高频局放传感器悬浮电位缺陷的分析

内置式特高频传感器由于灵敏度高、抗干扰能力强的优点在GIS局部放电检测中获得广泛的应用,但内置式传感器制造安装要求高,运行过程中会出现安装工艺不良等造成的传感器本身放电缺陷,针对此问题,利用局放带电检测方法,定位363 kV GIS设备内置式特高频传感器接口部位悬浮电位缺陷,准确分析缺陷原因,提出解决措施,并在不改变设备本体结构情况下完成缺陷处理,确保了设备安全运行。     

气力除灰系统常见缺陷原因分析及防范措施

针对宁夏马莲台电厂2×330 MW燃煤机组正压气力输灰系统的常见的缺陷,进行全面分析,找出缺陷发生的原因,提出了处理缺陷的改进措施。分析结果表明:燃煤发热量低,煤量大、灰量大是造成缺陷的主要原因。     

TEV、UT、UHF技术在开关柜局部放电检测中的应用

针对10kV开关柜局部放电问题,为排除干扰,准确判断开关柜局部放电类型和放电点位置,提出采用暂态地电位(transient earth voltage, TEV)、超声波(ultrasonic test, UT)、特高频(ultra high frequency, UHF)技术进行联合检测的方法,并在现场实测工作中进行了应用和验证。结果表明:该联合方法对开关柜设备缺陷的检测与定位非常有效,提高了开关柜局部放电检测的准确性和有效性。     

GIS罐体内部异物清理机器人的研发与应用

针对气体绝缘金属封闭开关设备( gas insulated switchgear, GIS)内部异物颗粒引起设备内部电场畸变,从而造成设备闪络故障问题,通过对异物颗粒的产生原因及影响因素进行分析,研制了一种GIS罐体内部异物颗粒清理机器人,实现了GIS设备内部可视化异物清理功能。应用结果表明:机器人检测不仅提高了750kV GIS内部缺陷检查的效率,而且保证了检测人员的安全,为GIS状态检修提供了有效技术支持。     

应用超声波检测技术对开关柜早期故障的诊断

某 35kV开关柜存在疑似放电声音,应用超声波检测手段对该开关柜进行全面检测,最终确诊了放电类型及放电位置。停电后,发现柜内一处等电位线断裂。经检修处理后,放电声音消失,超声波检测无异常。本次应用超声波检测有效避免了一起设备事故。应用结果表明：超声波检测技术能够在开关柜早期故障诊断中发挥重大作用,并有利于设备状态评价与检修工作的开展。     

Monitoring and reporting attacks on education in the Democratic Republic of the Congo and Somalia

The United Nations' Monitoring and Reporting Mechanism is charged with documenting six grave violations against children in a time of conflict, including attacks on schools. Many of these incidents, however, remain unreported across the globe. This study explores whether or not a local knowledge base of education and child protection actors in North and South Kivu Provinces, Democratic Republic of the Congo, and in Mogadishu, Somalia, could contribute to a more complete record of attacks on education in those areas. Hundreds of semi‐structured interviews were conducted with key informants across the three settings, and in total 432 attacks on education were documented. Purposive samples of these reports were verified and a large majority was confirmed. Local non‐governmental organisations and education institutions were most knowledgeable about these incidents, but most never reported them to a monitoring authority. The study concludes that attack surveillance and response were largely insufficient, and recommends investing in mechanisms that utilise local knowledge to address these shortcomings.     

The Response of the South Manchester Accident Rescue Team (SMART) to the Armenian Earthquake and Lockerbie Air Disaster: A Report to the Prime Minister's Office

The delay in receiving authorisation for the despatch of SMART significantly reduced our overall effectiveness. The majority of injured survivors were extracted during this time and our special expertise could have saved a significant number of lives. The episode has provided SMART with unique experience for a British medical team and this knowledge should not be wasted. In contrast to other major western countries the British response was fragmented. We have no central stockpile of equipment and no official response team. The British who responded were independent of each other even when from the same service. The quality of the individual British teams was as good as any and often better. However, the ability of other nations to coordinate their response centrally and draw from a pool of workers already used to working together, improved both their efficiency and effectiveness. There are great difficulties in communication during any disaster and these increase with the scale of the disaster. Incoming rescue workers were given false or misleading information and rumour was widespread. Even when few people were found alive rescue workers expressed a strong need for a medical presence in case they discovered an injured person or they them selves became ill or injured. We were told repeatedly by experienced rescuers that we were the first team of British senior doctors they had met at the front line of a disaster and they were extremely pleased to see us. Transport was a major problem both in terms of vehicles and local knowledge. It was not thought to be within the remit of a medical team to make provision for food and shelter and this was confirmed in Moscow prior to departure for Yerevan. In retrospect this was a mistake and reduced the time we could stay at the front line. If we had not equipped ourselves with special clothing we could not have gone to the front line. A medical team must be part of larger team of rescue workers. Within this unit there will be provision for food, shelter, transport and communication as well as medical and surgical equipment.     

黏土半巷道围岩模型过巷道轴线平面破坏过程实验观测∗

为了观测过巷道轴线平面上应变局部化带及裂纹的发展演化规律,开展了黏土半巷道围岩模型三轴压缩实验研究。半巷道围岩模型的观测表面处于平面应变状态,且分步开挖巷道。在每次巷道开挖之前,对半巷道围岩模型卸荷。每次巷道开挖之后,再对半巷道围岩模型加荷。采用数字图像相关方法观测了观测表面的最大剪切应变场,并统计了裂纹面积百分比随纵向应变的演化规律。得到以下结论:当纵向应变较高时,在半巷道围岩模型的观测表面上,出现了由巷道两帮或两帮与掌子面交点处发展出的应变局部化带;另外,还出现了距离巷道表面较远的应变局部化带。由此可以推出,垂直于巷道轴线平面上将会出现分区破裂化。裂纹面积百分比随纵向应变的增加而增加;随着阈值(可识别的裂纹面积的最小值)的增加,裂纹面积百分比降低,但降低的速度越来越慢。剪裂纹主要位于巷道的两帮;拉裂纹遍布各处,呈现一定的等间距性。     

Environmental Health and the 1991 Bangladesh Cyclone

A brief post-disaster study was undertaken soon after the cyclone of 1991 in Bangladesh to make a preliminary assessment of existing environmental health conditions. Eighty affected people and 26 relief personnel from the affected areas were interviewed. Faecal coliform counts, salinity conductivity and pH values were determined for 43 water samples from tubewells and ponds. The quality of 32 samples of water purifying tablets was also tested.
Water scarcity was acute, especially water used for washing and personal hygiene. The situation was made worse by the fact that the surface water sources (ponds) which were commonly used for domestic purposes other than drinking were flooded, highly contaminated and regarded as unusable. The user load on existing tubewells doubled, indicating a significantly increased demand for the tubewell water which is commonly used for drinking purposes only. The majority (63 per cent) of the water purifying tablets were found to have lost potency. Sanitation was very poor in households as well as in field clinics and shelters. Most people, including relief personnel, lacked environmental health knowledge. Suggestions regarding immediate preparations for disaster relief include: restoring water systems (tubewells and ponds), training courses for relief personnel, standardizing of water purifying tablets, promoting appropriate water use and its treatment, maintaining sanitation in clinics and shelters and improving the skills and resources of local people to enable them to cope with the situation.