频率响应复数值在电力变压器故障诊断中的应用

频率响应分析法是现场用于检测电力变压器内部机械缺陷的重要方法。目前有几种不同的、用于分析频率响应法结果的方法,其中最常用的就是利用数值指标(如相关系数、均方差等)得出不同频响曲线之间的差异性。然而,传统的数值指标都只使用了频率响应结果的幅值,其对于变压器绕组微小变形的检测灵敏度不够理想。因此,文中提出了一种同时考虑频率响应结果幅值和相位的数值指标及一种改进传统数值指标的方法;然后通过实验得到了不同轴向微小变形程度绕组的频率响应数据;最后将不同的数值指标应用于实验所得数据并进行了对比试验,验证了所提出数值指标及改进数值指标的优越性。试验结果表明,同时考虑频率响应结果幅值和相位可以提高频率响应分析法对于绕组微小变形的检测灵敏度,有利于提高电力变压器故障诊断水平。

Application of the Complex Values of the Frequency Response in Fault Diagnosis of Power Transformer

Frequency response analysis(FRA)is an important technique for detecting the mechanical defects inside a power transformer.There are several methods to interpret the FRA results,and the most common method is using the numerical index(such as correlation coefficient,mean square deviation,etc)to obtain the degree of deviation between different frequency response curve.However,the traditional numerical indices use only the magnitude response of the FRA results,which is not accurate enough for the detection of minor winding deformations.Therefore,a numerical index considering both the amplitude and phase of frequency response results and a method to improve the traditional numerical index are proposed.Then the frequency response data of different axial minor deformation windings are obtained through experiments.Finally,different numerical indices are applied to the experimental data and the results are compared to verify the superiority of the proposed numerical indices and the improved numerical indices.The results show that,the sensitivity of the frequency response analysis method to the minor winding deformations could be improved by considering both magnitude response and phase response of the FRA results,which is beneficial to improve the level of power transformer fault diagnosis.