基于差分双正交小波熵的变压器励磁涌流识别算法

励磁涌流仍然是制约差动保护正确动作的最主要问题之一。分析了励磁涌流和内部故障电流的波形特征,根据励磁涌流突变点分布特性,提出了一种小波熵识别励磁涌流的新判据。用双正交多分辨率分析取代常规的正交多分辨率分析,以解决下坡突变点难以辩识问题。采用差分预处理策略放大突变点的奇异性特征,并利用三相小波熵的分布特征识别励磁涌流。在此基础上,制定了励磁涌流识别的具体实现方案。仿真及实验表明,所提出的励磁涌流识别方法有效。

Identification of transformer inrush current based on difference biorthogonal wavelet entropy

Inrush current is still one of the most important issues which restricts the accuracy movements of differential protection. The characteristics of the differential current under the conditions of inrush and internal fault are analyzed. According to the feature of the inrush mutations, a new judgment to identify the inrush current based on wavelet entropy is proposed. In order to solve the problem that the downhill mutations are difficult to identify, biorthogonal multi-resolution analysis is used instead of the conventional orthogonal multi-resolution analysis. The difference pretreatment is used to amplify the characteristics of the singularity of mutations, and the inrush current is identified by the use of the distribution of the three-phase wavelet entropy. Based on the above analysis, the specific implementation scheme is made. Simulation and experiments show that the proposed method is effective.