基于差流符号序列特征的变压器励磁涌流识别判据

变压器在空载合闸的过程中，会产生幅值较大的励磁涌流，如不采取相应的闭锁措施，将导致变压器差动保护误动作。针对该问题，提出了一种基于差流符号序列特征的变压器励磁涌流识别判据。该判据首先对差流序列进行符号化处理，根据符号序列中相关模式序列出现的比例，量化表征差流波形的特征，实现对励磁涌流和故障差流的识别。利用PSCAD/EMTDC仿真软件验证了所提判据在各类区内外故障和励磁涌流工况下，以及各类工况伴随电流互感器饱和时的有效性。

Identification criterion of transformer magnetizing inrush current based on symbol sequence characteristic of differential current

In the process of no-load closing of transformer, the magnetizing inrush current with large amplitude will be generated. If the corresponding locking measures are not taken, the transformer differential protection will be misoperated. In order to solve this problem, an identification criterion of transformer magnetizing inrush current based on the symbol sequence characteristics of differential current is proposed. This criterion firstly symbolizes the sequence of differential current, and then quantifies the characteristics of differential current waveform according to the proportion of correlation pattern sequence in the symbol sequence, so as to realize the identification of magnetizing inrush current and the differential fault current. PSCAD/EMTDC simulation software is used to verify the validity of the proposed criteria under various types of in-area and out-of-area faults and magnetizing inrush current conditions, as well as various types of conditions accompanied by current transformer saturation.