电力变压器含水量测量的介质响应方法

文章介绍了3种介质诊断方法,即回复电压法（RVM）、极化去极化电流法（PDC）和频域谱法（FDS）,以及3种方法测量结果的比对,并介绍了这些方法的优缺点和改进措施。     

变压器油微水超标现场处理方法的改进

针对龙嘉500 kV变电站变压器油微水超标问题,介绍单罐式滤油循环法和倒罐式滤油循环法的原理、处理效果和存在的问题,分析原因并提出改进措施。经处理的全部绝缘油检验均合格,保证了该变压器施工的正常进行。     

变压器在线监测技术的新突破

通过对变压器的油色谱分析、微水分析、温度热效应等综合信息，可以准确分析判断变压器绝缘状况，介绍了变压器在线监测系统的主要原理和功能特点。并分析该系统如何通过监测变压器负荷、顶部油温和绕组热点温度得出变压器绝缘老化速率，判断其安全运行的可能性。     

基于ModbusRTU的变压器油微水变送器设计

高压电力变压器油中水分存在不同形态,危害变压器运行,在线监测变压器油中微水含量意义重大.分析了高分子材料-聚酰亚胺薄膜的电容式湿度敏感元件测量原理,设计了采用以相对饱和度和温度为监测特征量的变压器油微水变送器,用实验方法证明了研制的变压器油微水变送器的测试结果与国家标准试验方法-卡尔·费休试剂法具有一致性,测量重复性较好,从而实现油中实际微水含量的在线监测,保证了在线监测变压器油中微水含量的准确性.     

油浸电力变压器固体绝缘老化的诊断

分析了固体绝缘老化机理，对变压器油中糠醛含量，熔解气体含量和绝缘纸聚合度等数据进行了统计分析，提出了对现场运行变压器固体绝缘的老化状态进行判断和评估的方法。     

电力变压器零序阻抗的测量

对２２０ＫＶ电力变压器零序阻的抗特性,测试方法进行了分析和探讨,并列举出种常见的大型电力变压器零序阻抗测量实例,供现场参考。     

变压器油微水在线监测技术原理及实现

论述了变压器油微水在线监测原理、检测方法和系统技术的实现,实现了微水信息的在线采集和处理。     

Digital Wattmeters for Loss Measurements of Power Transformers

This paper gives particular attention to the theoretical and practical difficulties that arise in the measurement of power losses in very large transformers or inductors. The most serious of these problems is the measurement of very low power factor loads, values down to 0.01 or 1% may be encountered. Major difficulties in making these measurements include problems associated with non-ideal power sources, problems introduced by the necessity - in some cases - of making measurements on highly distorted waveforms, and problems associated with making measurements in a restricted amount of time. While a measurement involves a complete system, the emphasis in this paper is upon the power measurement circuitry itself. An attempt is made to point out the theoretical limitations of various approaches and to separate these from the practical limitations of certain types of circuits. The major emphasis is upon digital methods of measuring power. The final section of the paper provides a comparison between some of the available types of digital wattmeters. It is hoped that this paper will provide help in selecting and in understanding the use of instruments to be used in the measurement of transformer losses.     

大型电力变压器油纸绝缘微水含量定量评估检测技术

针对110 kV及以上等级大型变压器油纸绝缘微水含量检测的问题,文中采用时、频域结合的双通道测量技术对不同新旧程度的变压器进行实地现场测试试验,分析了温度、频率、微水含量等因素对大型电力变压器介质响应特性的影响规律,并定性地给出了其绝缘微含水量的分析方法。最后,通过X-Y模型,并结合复介电常数数据库,定量地给出了油纸绝缘中微水含量的计算公式。试验数据库、结果及定量计算方法可为大型电力变压器的实地微水含量检测及设备维护提供工程参考依据。     

大型电力变压器油纸绝缘含水量的介质响应诊断技术

介质响应技术是检测油纸绝缘含水量的一种无损诊断技术,该技术通过油纸绝缘的介质响应曲线判断其含水量。为推动该技术的发展和实际应用,以电介质理论为基础,对大型油纸绝缘电力变压器的介质响应特性开展了大量研究。结果表明,大型电力变压器介质响应曲线受频率、温度、含水量的影响具有较强的规律。提出了大型电力变压器油纸绝缘含水量的定性分析方法,并通过建立不同含水量、不同温度油浸纸板的复介电常数数据库及设备的X-Y模型,实现了大型电力变压器油纸绝缘含水量的定量计算,计算结果与实际基本相符。     

考虑在线监测信息的电力变压器时变停运模型

变压器的可靠运行受到自身健康状态、运行状态、气象环境等多方面因素的影响,这些因素增加了变压器运行状态的随机性和复杂性,现有模型无法量化分析不同影响因素对变压器时变停运过程的影响。文中提出了基于比例风险模型和半马尔可夫过程的变压器时变停运率模型,模型可以融合不同影响因素,并考虑了影响因素自身状态的随机过程。为了克服解析法直接求解的困难,引入了蒙特卡洛法对影响因素状态进行采样,给出了变压器可靠性评估流程与收敛条件。算例分析表明了时变停运模型的合理性,以及评估算法的有效性。     

Field Measurements of Partial Discharges in Potential Transformers

A recent increase of failures of high voltage potential transformers, due to insulation breakdowns, cause great concern in the utility industry. The need for in situ testing of installed instrument transformers to confirm the loss or remaining quality of the insulation material has led to the adoption of well-established laboratory test methods for applications in electrical substations.     

Effects of Moisture on Furfural Partitioning in Oil-Paper Insulation System and Aging Assessment of Power Transformers

The furfural concentration in oil is a well-accepted chemical marker indicating the aging condition of power transformers. However, recent researches suggest that the furfural concentration in oil is affected by moisture, because moisture influences the furfural partitioning ratio in oil-paper insulation system. In this study, the correlation of moisture and furfural partitioning ratio was investigated. The accelerated thermal aging test and moisture absorption test were conducted to prepare oil-paper samples with different furfural and moisture concentrations. For samples with different moisture concentrations, the furfural partitioning ratios between oil and paper were compared. Results showed that samples with high humidity exhibited a high furfural mass fraction in oil. This finding implied that high humidity promoted the furfural diffusion from paper to oil. Further, the interference of moisture on aging assessment of insulation paper was analyzed. Results showed that the increase of moisture concentration in oil-paper system would significantly affect the accuracy of insulation paper aging assessment. A corrected equation for aging assessment of insulation paper with different moisture concentrations was established. Verification result showed that the equation could effectively correct the interference of moisture and enhance the accuracy of the aging assessment of insulation paper.     

电力变压器中的静电起电

对变压器中绝缘油流动带电现象进行了研究，给出了一些大型变压器运行故障实例，分析了变压器静电起电的原因和条件，介绍了静电起电的监视技术。     

高损耗电力变压器的改造

近年来,新设计的低损耗中小型电力变压器S9系列已大批量投入电网运行,取得了显著的节能效果.但由于电网中仍存在大量高损耗变压器,造成大量的电能损耗.节约能源,合理利用资源,成为当今社会走可持续发展道路的必要保证.通过对变压器铁芯降低磁密改造及线圈增加匝数,并对改造前后的产品性能、经济效益对比和变压器改造实例分析,进一步表明对原有高损耗变压器采用新材料和新工艺改造,既能达到节约大量资金,又能达到高效利用能源的目的.     

变压器油纸绝缘含水量定量评估的频域介电特征参量研究

水分是影响电力变压器油纸绝缘性能的一个重要因素。为了更好地将频域介电谱法(Frequency Domain Spectroscopy,FDS)应用于变压器油纸绝缘含水量的无损定量评估,从而对变压器的绝缘状态及剩余寿命进行可靠预测,本文在实验室内制备了不同水分含量的油纸绝缘样品,并在30℃及50℃下对样品进行频域介电谱测试;为了在有限的测量频段内尽可能获得复相对介电常数(?*r)所携带的绝缘信息,本文在深入研究水分及温度对油纸绝缘?*r影响规律的基础上,提出在特征频段内采用复相对介电常数的实部积分(SRP)和虚部积分(SIP)作为绝缘纸板水分含量评估的特征参量,并给出了特征参量与绝缘纸板水分含量的拟合关系。最后,引入了"FDS曲线频率平移法"以消除温度对油纸绝缘频域介电特性的影响。结果表明:SRP在10?3~10?1Hz的特征频段内随绝缘纸板水分含量的增加而显著增大;而SIP在10?1~101Hz特征频段内也存在类似规律,通过"FDS曲线频率平移法"绘制的?*r主曲线可以消除温度对油纸绝缘频域介电特性的影响,从而提高绝缘纸板水分评估结果的可靠性。