New Method to Identify Sympathetic Inrush in Transformer Based on Hilbert Huang Transform
Sympathetic inrush may cause the mal-operation of differential protection. Aiming at this problem, based on the characteristic that sympathetic inrush contains a lot of aperiodic component and high harmonics, this paper proposes to use Hilbert Huang transform to identify sympathetic inrush. Firstly, the mathematical model of sympathetic inrush is established to analyze its characteristic. Then Hilbert transform is used to obtain harmonic contents of sympathetic inrush and internal fault current. According to the proportion of fundamental to current, sympathetic current can be identified and differential protection can be blocked. The simulation results show that this method has better reliability and sensitivity than the second harmonic restraint scheme. Besides, it has a good ability against TA saturation.
M. F. Gong et al., "New Method to Identify Sympathetic Inrush in Transformer Based on Hilbert Huang Transform", Applied Mechanics and Materials, Vols. 229-231, pp. 863-867, 2012