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The use of high voltages to measure insulating materials and spacings is discussed. Techniques for the generation and measurement of high test voltages are examined. Types of high-voltage tests are described. The procedures fall into three basic categories: those devised to test materials, those devised to test apparatus, and those devised to evaluate the deterioration of insulation in service 相似文献
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Partial discharge or corona activity in the insulation system of large electric machine stators has caused deterioration of these machines, and in some cases resulted in premature failures. Development work is being done to better understand the cause and effects of this corona activity. Efforts are centering around the increased use of corona-resistant material, and the reduced use of corona-sensitive materials. Some of the developments are described in this paper 相似文献
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水电机组的劣化影响着水电站乃至电力系统的安全稳定运行。为了准确解析水电机组运行状态,获取机组的劣化趋势并对其进行准确预测,本文提出了一种基于极限梯度提升算法、变分模态分解算法、双向门控循环单元神经网络和注意力机制的水电机组劣化趋势预测混合模型。该方法首先用极限梯度提升算法建立考虑工作水头、有功功率和导叶开度影响的水电机组健康状态模型;其次,根据健康状态模型,推导出数年后的水电机组劣化趋势;再次,通过变分模态分解算法对水电机组劣化趋势进行分解,得到多个相对平稳的固有模态函数分量,并对每个模态分量建立双向门控循环单元神经网络和注意力机制的组合模型进行预测;最后,将预测模型的结果进行叠加,得到最终的趋势预测结果。实例分析结果表明,所提方法能准确地表达水电机组的劣化趋势,并且能有效地提高机组劣化趋势的预测精度。 相似文献
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A system capable of monitoring mine electrical power systems and detecting component failure in early stages could significantly improve power system safety and availability. Such monitoring would require a method of evaluating electrical features, calculated from terminal values, for indications of component deterioration. Research is being conducted by the US Bureau of Mines to examine the use of mathematical models to aid in this evaluation by creating polynomial networks called adaptive learning networks that can indicate deteriorated conditions in cable-connected motor systems. This process uses laboratory training data to select the electrical features most significant for accurately modeling cable-motor system conditions and forms mathematical expressions relating these features to the presence and severity of deterioration. Particular attention is given to PNETTR-4X, a modelling software package that forms adaptive learning networks from input training data using an unsupervised learning process. Models developed thus far can process readily measured terminal information and quantify deterioration power and current to within 3% of motor full load values 相似文献
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《Power Systems, IEEE Transactions on》2009,24(1):58-66
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The authors review the procedures available for the periodic testing of industrial power system components, with particular reference to the mining industry. The inherent limitations of these tests are discussed, and appropriate applications for these tests are suggested. The use of negative-sequence monitoring as an inexpensive but powerful detector of incipient failure in industrial power systems is proposed. It is emphasized that negative-sequence monitoring does not interfere with normal operations and is continuous. In laboratory experiments, it has been proven to be a sufficient indicator for detecting electrical deterioration within a squirrel-cage induction motor. It is concluded that, despite the effects of an unbalanced voltage supply on the measurement and the present uncertainty over how to compensate for these effects, negative-sequence monitoring can be a significant and powerful addition to a plant's motor testing program 相似文献
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Shigemitsu Okabe Masanori Koto Yoji Fukuda Yoshinori Hayashi Toshio Nara Kunihiko Takahashi 《Electrical Engineering in Japan》1995,115(8):1-11
Power capacitors are highly reliable due to their completely enclosed configuration. They are relatively trouble-free over the long term. However, their dielectric strength can be reduced due to some stresses, including overvoltage application or thermal degradation of the insulation material during long periods of operation; these events can result in dielectric breakdown of capacitors in extreme cases. Since almost all power capacitors with oil-impregnated paper have been operated for more than twenty years, some kind of failure should be expected. To prevent these incipient accidents, it is important to examine the insulation deterioration mechanism and evaluate the degree of deterioration before capacitor breakdown. To establish a diagnostic method of deterioration of the capacitors with oil-impregnated paper, we have conducted thermally and electrically accelerated deterioration tests and investigated the changes of their characteristics. Based on the experimental results we obtained, it can be concluded that the behavior of the oil-dissolved gases can be used as a useful index to diagnose the insulation deterioration of these capacitors. 相似文献
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The Japanese high-voltage system is outlined. The OLCM (online cable monitor) method is explained in detail from concept to the developed automatic model. OLCM is the name of the apparatus for monitoring the deterioration state of XLPE cables without interrupting service. With OLCM, it is possible to detect deterioration of XLPE cables having water-trees while the cables are live. Some views on the insulation resistance characteristics of deteriorated XLPE cables following long-term operation of the OLCM are presented 相似文献
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Intensive research and development concerning the application of polymeric outdoor insulations in Japan started about 10 years ago. Research on applying polymeric insulating materials to power systems covers various fields such as insulators and interphase spacers for overhead transmission lines, polymer housing of bushing and surge arresters for substation apparatus, insulators and interphase spacers for distribution lines and insulators for railways. Polymeric insulators and housings for electric power systems are being evaluated to extend their use, focusing on insulation characteristics such as withstand voltage against salt contamination and deterioration through prolonged use. For railways, trial uses of polymeric insulators have been started on commercial lines 相似文献
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Tsuruo Yorozuya Nobuo Takasu Susumu Isaka Toshio Suzuki Yukihiro Hashimoto Yasuaki Ishioka 《Electrical Engineering in Japan》1993,113(5):44-58
Power transformers have been expected to work with safety and reliability over a period of more than 30 years. The life expectancy of transformers depends upon the degree of deterioration of insulating materials, particularly conductor insulating paper. Many attempts have been made in recent years to estimate the degree of deterioration of transformers but no diagnostic techniques have been put into practical use because of the difficulty of taking into account the service conditions. It is well known that materials change color when they deteriorate, but no colorimetry study has been made on material deteriorations. According to the recent advances in instrumentation and data processing equipment, the color of materials has become easy to measure qualitatively. Therefore, the basic investigation on colorimetry of insulating papers has been made to clarify the applicability to power transformers. Test results showed a strong correlation between the color difference and the deterioration of insulating paper. This report discusses the effect of materials of papers and impregnating oils on colorimetry. 相似文献
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Partial discharges (PD) and the way they affect insulation quality has for decades been a rewarding subject for many researchers. There are two topics that are of particular interest to the workers in the field of PD. One is the impact of a wide variety of statistical tools on the interpretation of discharge data obtained with standard PD detection apparatus according to IEC270. The other topic is the study of discharge-induced degradation processes by looking into the physics of the discharge process. This can be done by different means but a valuable technique, at least for the laboratory, is the use of ultra-wide band PD detection systems. This paper is a mix of a short review on the progression in the understanding of deterioration by internal PD obtained with such systems and of results recently obtained by the author 相似文献
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通过正交试验分析了温度、水分、金属杂质三因素对抗燃油劣化速度的影响 .实验结果表明 :水分是影响ZR 881型抗燃油劣化的主要因素 ,温度是影响FyrquelEHC劣化的主要因素 .这个试验结论对于现场运行中抗燃油防劣化方法的选取有较大的指导意义 . 相似文献
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Digital recorders are becoming more commonly used in the recording of steep-front HV impulses. Although many digitizers exhibit a nonlinear deterioration in dynamic performance with increasing input signal steepness, there is no accepted method for predicting the magnitude of the resulting errors. The authors describe the development and implementation of a computer modeling technique for establishing the magnitude of these errors. The model is based on time-domain test data combined with a basic understanding of the digitizer's operating principles. The model is general in nature and can be used for the prediction of errors generated by any recorder that has systematic errors. The model was used to predict the maximum error which can occur when a particular EBS (electron-bombarded semiconductor) recorder is used to monitor HV impulse tests on power apparatus. Its use allowed for the determination of error limits for records of steep-front impulse tests which will be standardized in the near future 相似文献
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Takashi Shinmoto Chiaki Kimura Ken Yamamoto Susumu Umeda 《Electrical Engineering in Japan》1996,116(5):75-84
The method for measuring insulation resistance by superimposing the dc voltage has potential for detecting the deterioration of cable insulations. The deterioration of cable insulations can be detected by measuring current which flows through a grounded shielding wire. However, the earth current also flows from the cable sheath into the grounding wire as noise. Thus, to assess the deterioration properly, it is necessary to separate the earth current from the total current. On the other hand, to improve detection sensitivity, it is desirable to superimpose the highest possible dc voltage. In this case, provision must be made so that there are no adverse effects on the GPT. The authors, placing special emphasis on the method of measuring high insulation resistance by configuring the bridge, have conducted an investigation on how to detect the insulation deterioration with high accuracy and sensitivity without impairing the functions of the GPT. The following issues were investigated and the results are reported in this paper: (1) It is possible to measure insulation resistance as high as 100,000 MΩ by superimposing 50-V dc through the GPT after cancelling the earth-current and by configuring a bridge for determining insulation resistance from voltage ratio. (2) Even if 50-V dc is superimposed through the GPT, it is possible to prevent the magnetic saturation of GPT if the current injected by such superimposition is limited (i.e., below max. 5 mA). (3) In lieu of a variable resistor, a variable dc voltage supply is employed in the bridge. The variable dc voltage supply requires no mechanically driven part, thus making it possible to realize a fully automatic monitoring system. 相似文献
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Improvement of partial discharge (PD) resistance of epoxy resin by using sulfur-containing additives
Yasuhiko Kako Shigetaka Watanabe Yutaka Higashimura Kenji Matsunobu 《Electrical Engineering in Japan》1994,114(7):1-11
In the field of high-voltage engineering, it has been desired for a long time to improve the internal PD resistance of epoxy resin without lowering other properties. Recently, the authors discovered that some sulfur compound as curing agents or simple additives improved the PD resistance of rubber markedly, and here an attempt has been made to apply this fact to the case of epoxy resin. As was expected, some sulfur compounds containing SS-bond suppress the deterioration of epoxy resin due to internal partial discharges, and the larger the molecular weight of organic group combining the SS-bond, the longer the effective life of additives. Moreover, to make full use of these additives, it is very important to restrict moisture in the insulation systems. From this study, the authors have proposed the chemical formulation of the suppressive effect of additives for deterioration of epoxy resin due to internal partial discharges. 相似文献