基于小波变换的变压器励磁涌流识别方法

Method for exciting inrush detection in transformers using wavelet transform

可靠识别励磁涌流是变压器差动保护中一个亟待解决的问题。由于变压器铁芯的高度非线性特征 ,导致励磁涌流波形出现明显的突变特征 ,利用二进小波变换可以有效地检测这个突变 ,可以获得优良的差动保护动作性能。基于此 ,该文提出了一种识别变压器励磁涌流的方法 ,这个方法可以在小于 5 ms的时间内判定出励磁涌流。电磁暂态仿真计算结果证实了所提方法的正确性和有效性。

Effective detection of exciting in -rush remains as an important problem in transformer differential protection. Satisfactory performance of the differential protection can be achieved by analyzing and discriminate in -rush of transformer. Because of the high non -linearity in exciting core of transformers, waveform of the exciting inrush shows “abrupt change” characteristics and quite differs from one of fault current of transformer. Using dyadic wavelet transforms, the “abrupt change” can be detected and the exciting in -rush can be identified. Based on the discriminating characteristics, new algorithm for detecting exciting in -rush was proposed. The method can detect the inrush in 5 ms . Results of EMTP (electromagnetic transient program) simulations show that this method is valid and also possesses fast detecting ability.