A Novel Adaptive Algorithm to Identify Inrush

� Abstract—A novel scheme based on mathematical morphology to distinguish the inrush current from the internal fault current in power transformers is proposed, which is derived from high non-linearity in exciting cores of transformers. Transient current signals are extracted by use of the novel morphological gradient and morphological opening and closing transform, meanwhile various kinds of additive white noises are effectively suppressed by adaptive filtering. Based on different characteristics of transients between the short circuit current and the inrush current, the transformer criterion is developed. The proposed technique is immune to CT saturation. A total of 120 Electrical Power Dynamic Laboratory (EPDL) simulation cases are used to test the performance of the technique. This method has stability during the symmetrical inrush current and can be implemented in real time with very high accuracy. The results of different EPDL testing systems verify the feasibility and practicability of the proposed scheme.

[1]  Cheng Xiao.  STATISTICS AND ANALYSIS OF OPERATION SITUATION OF PROTECTIVE RELAYINGS AND AUTOMATION DEVICES OF POWER SYSTEMS IN CHINA IN 2002 , 2003 .

[2]  A. Wiszniewski,et al.  A multi-criteria differential transformer relay based on fuzzy logic , 1995 .

[3]  Xu Yan,et al.  A new principle of discrimination between inrush current and internal fault current of transformer based on self-correction function , 2005, 2005 International Power Engineering Conference.

[4]  M. S. Sachdev,et al.  Online identification of magnetizing inrush and internal faults in three-phase transformers , 1992 .

[5]  M. Wang,et al.  Analytical processing of online monitored dissipation factor based on morphological filter , 2004, IEEE Transactions on Dielectrics and Electrical Insulation.

[6]  Q. H. Wu,et al.  Ultra-High-Speed Directional Protection of Transmission Lines Using Mathematical Morphology , 2002, IEEE Power Engineering Review.

[7]  Xu Yan,et al.  Single-ended transient positional protection of transmission lines using mathematical morphology , 2005, 2005 International Power Engineering Conference.

[8]  Emmanuel Ifeachor,et al.  Digital Signal Processing: A Practical Approach , 1993 .

[9]  B. Jeyasurya,et al.  A state-of-the-art review of transformer protection algorithms , 1988 .

[10]  Yang Qixun.  STUDY ON THE NOVEL TRANSFORMER PROTECTION PRINCIPLE BASED ON THE TRANSFORMER MODEL , 2003 .

[11]  M. R. Zaman,et al.  Artificial neural network based protection of power transformers , 1998 .

[12]  M. Suzuki,et al.  Digital protection method for power transformers based on an equivalent circuit composed of inverse inductance , 1988 .

[13]  B. A. Mork,et al.  Transformer modeling for low- and mid-frequency transients - a review , 2005 .

[14]  Ge Baoming,et al.  An equivalent instantaneous inductance-based technique for discrimination between inrush current and internal faults in power transformers , 2005 .

[15]  O. A. S. Youssef,et al.  A wavelet-based technique for discrimination between faults and magnetising inrush currents in transformers , 2002, IEEE Power Engineering Society Summer Meeting,.

[16]  A. G. Phadke,et al.  A New Computer-Based Flux-Restrained Current-Differential Relay for Power Transformer Protection , 1983, IEEE Power Engineering Review.