Adaptive measuring algorithm suppressing a decaying DC component for digital protective relays

Abstract This paper presents a new adaptive phasor estimation algorithm for digital protective relaying. The algorithm is completely immune to an exponentially decaying dc component regardless of its initial magnitude and time constant. The algorithm is primarily intended for current signals and improves both magnitude and impedance measurements. The new technique is based on the recursive full-period Fourier filter with a separate adaptive function allowing for thorough rejection of the dc signal component. The comparative analysis of the algorithm, both analytical and by simulation, is included. The presented algorithm outperforms known measuring techniques including the digital mimic filtering broadly used in today's relays.

[1]  M.S. Sachdev,et al.  A New Algorithm for Digital Impedance Relays , 1979, IEEE Transactions on Power Apparatus and Systems.

[2]  L.A.L. de Almeida,et al.  Covariance management based RLS algorithm for phasor estimation in severely noisy systems , 1998 .

[3]  Adly Girgis,et al.  Application of Kalman Filtering in Computer Relaying , 1981, IEEE Transactions on Power Apparatus and Systems.

[4]  Jun-Zhe Yang,et al.  Complete elimination of DC offset in current signals for relaying applications , 2000, 2000 IEEE Power Engineering Society Winter Meeting. Conference Proceedings (Cat. No.00CH37077).

[5]  Alf Isaksson Digital protective relaying through recursive least-squares identification , 1988 .

[6]  G. Benmouyal,et al.  Removal of DC-offset in current waveforms using digital mimic filtering , 1995 .

[7]  Jyh-Cherng Gu,et al.  Removal of DC offset in current and voltage signals using a novel Fourier filter algorithm , 2000 .

[8]  E. O. Schweitzer,et al.  Filtering for protective relays , 1993, IEEE WESCANEX 93 Communications, Computers and Power in the Modern Environment - Conference Proceedings.

[9]  Pradipta Kishore Dash,et al.  Digital impedance protection of power transmission lines using a spectral observer , 1988 .

[10]  Eugeniusz Rosolowski,et al.  Fast identification of symmetrical components by use of a state observer , 1994 .

[11]  M. S. Sachdev,et al.  A recursive least error squares algorithm for power system relaying and measurement applications , 1991 .