共查询到19条相似文献,搜索用时 243 毫秒
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在对运用频响法测试变压器绕组变形仪器工作原理研究的基础上,通过对事故后变压器测试的频率响应曲线分析,初步地建立了频响法检测变压器绕组变形的测试结果判定标准. 相似文献
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为更加准确地理解和掌握变压器绕组的振动响应特性,及时发现变压器绕组的故障隐患,以一台110 k V变压器为研究对象,依托所研制的变压器振动频响测试系统,对变压器绕组正常与典型故障下的振动频响特性进行了试验研究,根据箱壁上多个测点处的振动频响曲线,基于信息融合的思想计算分析了变压器绕组融合振动频响曲线的归一化奇异谱熵。试验结果进一步验证了变压器绕组振动频响试验的可重复性。变压器绕组振动频响曲线峰值随频率的增加而增大,且其峰值点随绕组工况不同出现明显偏移。归一化奇异谱熵能够较好地对变压器振动频响曲线进行定量描述,当变压器绕组存在松动或变形等典型故障时,振动频响曲线的归一化奇异谱熵变化率均5%。 相似文献
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钱国超于虹邹德旭徐肖伟刘光祺 《南方电网技术》2016,(11):45-51
为更加准确地检测变压器绕组的故障隐患,从变压器绕组多个测点处振动频响曲线的相关性出发,提出了一种综合灰色关联分析和熵权理论的变压器绕组振动检测方法。首先基于灰色理论计算了各个测点处振动频响曲线的灰色关联度和灰色面积关联度,然后定义了熵权关联度对变压器绕组状态进行检测。对某220 k V变压器绕组正常与松动时的振动频响试验结果进行了分析,结果表明,所定义的熵权关联度的计算结果与变压器预设工况吻合良好,可以较好地描述变压器绕组的松动状态,具有较好的工程应用价值。 相似文献
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离线频响法的传递函数难以应用于运行中变压器的绕组变形检测,因而构建了适用于在线监测的传递函数,并对比分析了其反映变形缺陷的能力。基于多端口电路网络理论,分别构造了适用于中性点接地和中性点不接地的带电运行变压器的3种传递函数;参考实际180 MVA/220k V变压器绕组参数,建立了三相双绕组变压器多导体传输线模型,计算了鼓包和位移变形时各传递函数的频响曲线及其8种特征参数。对比结果表明:在线传递函数的相关系数和欧氏距离的数值、随变形量变化的线性度、对变形量的灵敏度与离线传递函数基本一致;各传递函数特征参数的线性度达到0.8以上,对鼓包变形的灵敏度大约是位移变形的40%。所构造的传递函数不仅适用于带电检测,而且性能与离线传递函数基本一致。 相似文献
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变压器绕组变形的频率响应分析法综述 总被引:17,自引:1,他引:17
目前对绕组频率响应的分析方法主要是基于幅频响应曲线的分析,因此从频段划分、幅频曲线特征的分析及曲线相似指数3方面综述了幅频响应曲线的研究现状,介绍了频率响应分析法的原理,从扫频范围的选择和影响测量的因素2方面讨论了绕组频率响应的测量,认为应建立原始的绕组频率响应数据库,在反映绕组变形程度的曲线相似指数研究方面有待于提出切实有效的量化标准。 相似文献
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研究冷轧硅钢片铁心磁性能和油纸绝缘介电性能对绕组频率响应的温度效应。推导稀疏线圈在有铁心和空心时的阻抗差异与铁心复磁导率,以及绝缘材料的阻抗与其复介电常数的频率依赖关系。在频率范围从1k Hz到1MHz对铁心复磁导率、油和纸绝缘复介电常数和模型变压器两种绕组的频率响应进行从110℃自然降温到30℃的试验研究。获得铁心复磁导率、油和纸绝缘材料复介电常数随温度变化的规律,探讨了纸占比对油纸复合绝缘介电特性的影响,讨论铁心和油纸绝缘单独作用时绕组频率响应特征的变化趋势。进而用变压器这2种材料温度特性结合绕组等效电路解释了模型变压器层式绕组和饼式绕组的频率响应随温度变化的特征,认为绕组等效(合成)电感与等效电容的乘积变化最终决定了(反)谐振频率移动方向。为了正确地解释变压器绕组频率响应,应密切关注绕组变形试验时的温度。 相似文献
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Influence of Measurement Parameters on Frequency Response Analysis Diagnosis of Oil‐Immersed Transformer
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Katsunori Miyagi 《Electrical Engineering in Japan》2014,186(1):18-25
Appropriate monitoring and maintenance become important as an oil‐immersed transformer ages. Generally, dissolved gas analysis (DGA) is effective for the online diagnosis, and if an abnormality is detected, frequency response analysis (FRA) is effective for the offline diagnosis to localize the failed part. FRA diagnosis detects a slight change of waveforms; however, external factors may influence the results. Here, we discuss the influence of an insulating oil presence, tap position, and measurement lead wire length as possible parameters that influence the FRA characteristics. We confirmed that the measurement parameters examined here greatly influenced the FRA characteristics. In the actual diagnosis, it is important to remove these external parameters as much as possible, and keep a detailed record of the measurement parameters. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 18–25, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22313 相似文献
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介绍了应用频率响应分析法检测变压器绕组变形的两个实例.指出在检测中通过对前后频谱曲线的分析,能准确有效地发现变压器内部电气及机械事故隐患,对于变压器及电网的安全运行有着重要意义.但频率响应分析法不一定能够有效反映出变压器绕组变性发生单一扭动变形这类故障,绕组变形的诊断仍需使用多种试验手段综合分析和判断. 相似文献
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Diagnosis Criterion of Abnormality of Transformer Winding by Frequency Response Analysis (FRA)
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SATORU MIYAZAKI YOSHINOBU MIZUTANI AKIRA TAGUCHI JUNICHI MURAKAMI NAOKAZU TSUJI MASAHIRO TAKASHIMA OSAMU KATO 《Electrical Engineering in Japan》2017,201(3):25-34
Frequency response analysis (FRA) is a powerful technique to detect internal abnormalities within power transformers. However, diagnosis criteria of power transformers by FRA have not been fully established yet. In this paper, a new evaluation method of degree of identification between two transfer functions is proposed. In the proposed method, a frequency window is employed and cross‐correlation factor is calculated with moving the window. Furthermore, the proposed method is applied to transfer functions of real transformers with or without some abnormalities. Based on this discussion, objective criteria for diagnosis of abnormalities of transformer windings by FRA are proposed. The proposed criteria are based on a few data of transformers with some abnormalities. Therefore, the proposed criteria are tentative and they would be improved by accumulation of further data. 相似文献
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Abeywickrama N. Serdyuk Y.V. Gubanski S.M. 《Power Delivery, IEEE Transactions on》2008,23(3):1432-1438
This paper presents how the frequency response analysis (FRA) measurements on a transformer can be influenced by magnetization condition of the core. Measurements were performed on two transformers at different magnetization levels to show effects of remanent magnetization in the core due to removal of 3-supply, of relaxation demagnetization and of dc flux on the frequency response of winding impedance. The most important observations were that any sudden change of excitation field (applying or removing magnetization current) yields a slowly varying magnetic relaxation, which causes the impedance to change with time due to magnetic viscosity. Results of diagnostic measurements of transformer winding impedance can therefore depend on the level of remanent magnetic flux appearing in the core limbs after switching-off a transformer. These observations lead to a conclusion that, for avoiding the effects of core magnetization, diagnostic FRA measurements on power transformers should not be performed directly after disconnection from network. 相似文献
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变压器是电网安全运行中最关键的设备之一,由内绝缘(油纸绝缘)问题引发的变压器故障占变压器事故重要部分。目前用于诊断变压器油纸绝缘状态的方法尚存在各自的不足之处,故研究通过无损的诊断方法获取表征油纸绝缘老化状态的特征量,为评估变压器油纸绝缘老化状态提供准确且有价值的参考,无疑具有重要意义。基于频域介质响应的频域谱法是一种诊断电力变压器绝缘老化状态的非破坏性方法,笔者首先通过模拟变压器实际生产流程,制作变压器油纸绝缘试品,并对油纸绝缘试品进行加速热老化试验,得到不同老化程度的油纸绝缘试品。通过频域谱测试并分析了温度对油纸绝缘试品的频域介电特征量变化规律,运用电介质极化理论对测试结果进行了分析,为频域谱技术用于实际变压器油纸绝缘老化状态的无损诊断提供技术积累。结果表明:测量温度对频域谱诊断油纸绝缘老化状态影响显著,采用频温平移因子可以将任意测量温度下的频域谱曲线归算到同一参考温度,解决了测量温度对FDS测试结果的影响。初步研究结果表明,经过频温修正后的FDS能用于不同温度下的变压器油纸绝缘老化的评估。 相似文献