一种模拟变压器绕组变形故障的装置

基于频率响应分析法的基本原理和变压器装置的等效电路模型,针对实际工程中易发生的电力变压器绕组和机械构造发生变形故障问题,提出了一种可以用于绕组变形频响法教学讲解和用于现场快速测试变压器绕组变形频响测试仪的功能好坏的故障模拟装置。从原理上分析了变压器各种变形导致频率响应不同变化的机理,解决了如何简单快速识别变压器绕组变形问题。研究结果表明所提故障模拟装置对于教学和配套给绕组变形频响测试仪作为其自检有很大的帮助和实际价值。     

基于周期性宽频带M序列激励的变压器绕组变形故障检测

为了有效地检测电力变压器绕组变形,及时发现变压器的潜在故障,结合频率响应法的基本原理,提出了基于周期性宽频带M序列激励的变压器绕组变形故障检测方法(M序列激励法)。在介绍M序列信号的特性和产生方法后,给出了M序列级数、位持续时间和采样频率的选取原则。为了实施M序列激励法,研制了综合该法和扫频法的绕组变形检测装置,并通过实验室模拟绕组不同位置、不同程度匝间短路故障进行测试。结果表明:M序列激励法具有扫频法相同的检测精度,能够快速、准确地获得绕组的频响曲线。现场应用表明该方法具有良好的测量稳定性,能有效检测变压器绕组变形。     

电力变压器绕组变形常用检测方法

电力变压器绕组变形直接或者间接引起的变压器故障较多,检测变压器绕组变形十分有必要。变压器绕组变形检测的常用方法有低电压脉冲法、频响法和短路阻抗法。介绍变压器绕组变形的主要形式,分析三种测量变压器绕组变形的原理,对比三种测量方法的优缺点。     

阻抗法和频响法诊断电力变压器绕组变形

简要介绍了阻抗法和频响法测量电力变压器绕组变形的基本原理和实现方法,比较分析了阻抗法和频响法对两种典型变形测试的灵敏性,并指出了两种方法的互补性。在初步总结诊断绕组变形基本规则的基础上,对某次变压器绕组办形故障进行了分析和诊断。     

PT20电压互感器二次压降测试仪

由深圳市凯菱实业有限公司电力自动化公司生产的KLDL-B100系列变压器绕组频响分析测量仪是不吊心检测变压器绕组变形的专用仪器，产品通过对变压器绕组的频率响应图谱的分析，可以反映出绕组整体变形和局部变化情况，从而得出绕组变形故障的类型、程度等多种信息。产品主要用于35kV及以上电压等级大容量电力变压器绕组频率响应测量，适应干变电站现场和变压器生产厂试验站等各种环境。     

频响阻抗法诊断变压器绕组变形

变压器绕组变形是变压器的主要故障类型之一,严重威胁电网安全。为此,提出频响阻抗法诊断变压器绕组变形。研究了变压器绕组在低频和中频段的阻抗频率特性,以频率响应的测试接线为基础,测量相关的电压和电流值,对测得的电气数据进行处理以获得阻抗频率曲线,通过对比曲线间的差异实现对变压器绕组变形的诊断。建立了变压器绕组变形的仿真模型,通过改变模型中不同类型元件的参数值模拟绕组故障。仿真结果表明该方法能明显反应绕组故障,验证了频响阻抗法的有效性。     

电力变压器绕组变形的综合诊断法

为准确判断电力变压器故障后的绕组变形情况,笔者探究了频响法、短路阻抗法和绕组电容法综合判断变压器绕组变形的依据和规律.通过对故障变压器的理论分析和计算,结合实际的吊罩结果,证实了此3种方法的有机结合有助于准确分析和判断变压器绕组变形程度.     

基于欧氏距离分析的电力变压器绕组变形程度与类型的诊断方法

频率响应分析法是检测电力变压器绕组变形的常用诊断方法之一。近年来,频率响应分析法的检测流程趋向标准化,但寻求合适的算法对频响曲线数据进行量化分析仍需深入研究。文中将频响曲线数据的量化分析看作一个概率分类问题,提出了应用欧氏距离分析诊断变压器绕组变形程度和类型的新方法。研究结果表明,欧氏距离分析能够有效地对变压器绕组变形程度进行诊断,且与先前研究提出的数学指数方法相比,该方法对变形程度的诊断结果具有更高的线性度。同时,在检测频段分段后获取子频段的欧氏距离分布的基础上,计算得到了子频段欧氏距离的最大值与最小值的比值,该比值能够有效地对绕组变形类型进行诊断。研究结果对频响曲线数据量化分析具有一定的参考价值。     

基于频响曲线稀疏表示的变压器绕组变形模式识别方法

为了提高电力变压器绕组状态监测水平,提出了一种基于频响曲线稀疏表示的变压器绕组变形模式识别方法。文章在构建了Gabor原子的过完备原子库和通过有限元模型仿真得到了正常及变形绕组频响曲线的基础上,将正常情况及变形情况下的绕组频响曲线在过完备原子库上进行稀疏表示,并对所有匹配的Gabor原子分别进行短频傅里叶变换、叠加,得到正常曲线及变形曲线的等效时频分布,然后将两条曲线的等效时频分布值相减,得到可以反映绕组频响曲线变形程度的特征向量。最后,利用支持向量机模型实现了不同绕组变形故障的识别。试验结果表明,提出的方法具有较高的可靠性,适用于绕组变形模式识别。     

基于振动频响法的变压器绕组松动故障检测方法研究北大核心CSCD

变压器是电力系统的重要设备,在长期运行中会出现绕组松动、变形等故障,影响电力系统的正常工作,因此对变压器绕组健康状态进行评估极为重要。提出利用振动频响法获取变压器绕组的振动频响函数,对比绕组故障状态与健康状态下的振动频响函数,将两者之间的相关系数作为判断变压器绕组故障与否的依据。随后,对比健康状态与4种不同程度松动状态下变压器绕组的振动频响函数,探讨利用相关系数判断变压器绕组松动故障程度的可行性。本研究结果对判断变压器绕组运行故障具有一定的指导意义。     

Diagnosis Criterion of Abnormality of Transformer Winding by Frequency Response Analysis (FRA)

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.     

大型电力变压器损耗测量不确定度分析

为指导大型电力变压器损耗测量设备的选用,实现精确损耗测量,分析了造成大型变压器损耗测量不确定度的各种因素,并对这些因素造成的不确定度进行定量计算,最终对单个因素造成的不确定度进行合成,得到整体测量系统的测量不确定度.基于对损耗测量不确定度的分析,确定测量系统的相位测量精度是影响测量不确定度的最主要因素.定量分析和比较了使用不同测量系统进行损耗测量的不确定度,结果表明,使用0.01级的电压和电流互感器配合 Fluke Norma5000型功率分析仪(或性能接近的功率分析仪产品),大型电力变压器损耗测量的不确定度可控制在2%以内,是适合于大型变压器损耗测量的测量系统     

变压器绕组变形的频率响应分析法综述

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。     

FPGA-based Adaptive Phase-shift Compensation Method for Electronic Instrument Transformers

Accurate and reliable instrument transformers play an important role in power system measurement and protection. This paper focuses on the phase accuracy of electronic instrument transformers and presents an adaptive phase-shift compensation method for measuring electronic current transformers. Different from the existing approaches in which the empirical evaluation and fixed phase-shift compensation are used, the proposed method measures the phase displacement in real-time and calibrates the corresponding phase error adaptively, with the aim of achieving high and reliable phase accuracy. In particular, several practical factors are considered in the design, such as the phase displacement composition, phase error uncertainty, synchronous mode diversity, and computational complexity and latency. The proposed method is developed in a field-programmable gate array platform with low-latency hardware implementation and further employed in a merging unit. Finally, the experimental results are provided to demonstrate the validity of the proposed method.     

Improving the numerical indices proposed for the FRA interpretation by including the phase response

The frequency response analysis (FRA) is an effective technique to diagnose the mechanical deformations in a power transformer. Using the numerical indices is one of the methods proposed for the interpretation of the FRA results. Various indices have been proposed in the literature, but most of them are only based on the magnitude response of the FRA results. By contrast, this paper improves a number of the existing indices and defines a new index to include the phase response in the interpretation. The experimental data corresponding to different extents of the axial displacement and disc space variation show that including the phase response in an index increases its sensitivity. These results are also validated with simulation models of three transformers. Afterward, different uncertainties are introduced in the experiment, and it is shown that the new indices have also better performances against uncertainties in the FRA measurement. Although further studies are needed to settle the new indices, this research shows the early functionality and the potential of the phase information to improve the interpretation of the FRA results.     

Determination of phase angle and amplitude error of voltage and current transformers up to some 100 Hz for loss measurements on power transformers

Contents  For the load loss measurement of power transformers, current and voltage transformers with usually extremely low errors of phase angle and amplitude are used. However, even small errors of the measuring transformers may result in an error in the measured load loss. Therefore, national and international standards allow the correction of the measured value by the amount caused by phase angle and amplitude error of the measuring equipment [2–4]. The determination of the errors of phase angle and amplitude of measuring transformers is carried out on the basis of calibrated standard measuring transformers which are traceable to national standard equipment at rated frequency, e.g. at 50 and 60 Hz. For some applications – e.g. the load loss measurement of HVDC power transformers according to the draft of IEC standard 61378-2 [1] – a load loss measurement at frequencies other than rated frequency is required. For that, the errors of phase angle and amplitude of the measuring transformers must be known. This paper describes a method how to determine the phase angle and amplitude errors of the measuring transformers at arbitrary frequencies on the basis of the calibrated error values at rated frequency. Received: 9 August 2000     

A comparison of trans-admittance and characteristic impedance as metrics for detection of winding displacements in power transformers

Transfer function signatures are commonly used in condition monitoring analysis to give early indications of winding movement in power transformers. This paper presents a comparison of the use of trans-admittance (frequency response analysis, FRA), presently the industry standard, and characteristic impedance (transmission line diagnostics, TLD), a new method, as signatures for the detection of winding displacements in power transformers. To facilitate the comparison, a computer based winding model based on a multi-phase transmission line system was developed and different winding deformations were analyzed. The results show that TLD has a higher degree of sensitivity and can be used to augment the ability to classify different types of distortions currently diagnosed by FRA.     

Transformer winding movement monitoring in service - key factors affecting FRA measurements

This paper presents data from a study conducted to identify the key factors that contribute to frequency response analysis (FRA) measurement results. The results show that the lower the shunt impedance, the higher the sensitivity of the FRA measurement for the detection of winding movement. On transformers with large bushings, the bushings can mask the detection of winding movement. To detect minor winding movements, the FRA comparison has to be made using the same connections each time. With a typical test circuit, the FRA measurement sensitivity range of the standard lead arrangement is up to approximately 2 MHz only. For optimum measurement, the lead lengths need to be as short as possible, and the test configuration must remain constant for repeated tests. The higher the frequency range used, the more critical this becomes. From the results, it is apparent that minor winding movement or winding looseness generally shows in the high frequency region of the FRA admittance. All of the factors investigated impact on the ability of FRA measurements to detect winding movement. To optimize the sensitivity of FRA measurement method, these factors need to be taken into account.     

测量短路电抗是判断变压器绕组变形的有效方法

从理论和实践的结合上阐述了测量短路电抗可以判断变压器绕组是否变形的道理,分析了三相变压器不同联结组短路阻抗的测量计算方法,介绍了测量仪器的选择和使用注意事项。     

电子式互感器误差校准的研究

电子式互感器是智能电网建设的关键设备之一,其性能直接影响到数字化变电站的安全和经济效益,也是电能计量准确的必要条件。电子式互感器的输出与传统互感器不同,分为数字输出和模拟输出两种,因此传统的互感器校准方法已经不适用于校准新型的电子式互感器。文章以模拟量输出的互感器为例,创新性地提出了采用精密分流器和示波器测量比值差和相位差,并对校准数据进行了验证,测量结果满意。