基于小波变换的变压器励磁涌流和内部故障电流的识别研究

摘要

在变压器差动保护中，励磁涌流的准确识别是保护可靠动作的保证，也是变压器保护的难点之一。提出一种准确可靠的基于小波变换的变压器励磁涌流和内部故障电流识别新方法。采用Matlab/Simulink建立模型进行仿真，得到了励磁涌流与内部故障电流的波形图，利用db2小波进行4尺度小波变换，将高频分量在第4尺度上的2个初始峰值比作为励磁涌流和内部故障电流识别的判据。大量实验表明，此判据能有效识别变压器差动保护中的励磁涌流和故障电流。%In differential protection of transformer, the accurate identification of magnetizing inrush current is a guarantee of reliable action, which also is difficult point in the protection of transformer. This paper proposes a new accurate and reliable method of transformer magnetizing inrush current and internal fault current based on wavelet transform. We get the oscillograms of magnetizing inrush current and internal fault current by Matlab/Simulink modeling simulation, in which we make use of the db2 4-scale wavelet transform and treat the 4th dimension of two initial peak values as the identify basis of magnetizing inrush current and internal fault current in high frequency components. Experiments show that this criterion can effectively recognize the magnetizing inrush current and internal fault current in differential protection of transformer.