Abstract：With the increase of the capacity,the saturation magnetic flux of the transformer decreases.Meanwhile,the residual magnetism caused by DC resistance test cannot be eliminated completely.Consequently,the ultra-saturation phenomenon of the transformer may occur.Under this condition,the inrush waveform is similar to the sinusoidalwaveform.Hence,the second harmonic and the dead angle of the inrush are very small,which would make the differential protection based on the second harmonic or dead angle blocking cannot operate normally.The expressions of the inrush are derived firstly,and the generating mechanism for the ultra-saturation phenomenon is then analyzed.Based on it,a novel identification method of the inrush based on fundamental harmonic and second harmonic angle difference (FSAD) and aperiodic component is proposed.With the comparison with conventional identification methods,the novel approach can identify the ultra-saturation inrush quickly and correctly.Accordingly,it can make the protection have a faster operation speed when the transformer has internal faults.The dynamic experiment demonstrates the effectiveness and advantage of the proposed identification method.The algorithm can block the differential protection reliably when the transformer is in ultra-saturation condition and the second harmonic component is less than 8%.
王业,袁宇波,高磊,陆于平,朱磊. 基于FSAD及非周期分量的励磁涌流鉴别算法[J]. 电工技术学报, 2015, 30(21): 127-135.
Wang Ye,Yuan Yubo,Gao Lei,Lu Yuping,Zhu Lei. A Algorithm to Identify Magnetizing Inrush Current Based on FSAD and Aperiodic Components. Transactions of China Electrotechnical Society, 2015, 30(21): 127-135.
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2015, Vol. 30 
