Improvement of the differential busbar characteristic to avoid false operation during to CT saturation

Improvement of the differential busbar characteristic to avoid false operation during to CT saturation

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The proposed technique is based on extracting the windowed wavelet transform of fault generated transients to distinguish between faults in a busbar protection zone from those outside the zone, particularly in case of early and severe current transformer (CT) saturation. Most given techniques are tending to block the differential measurement during the portion of the cycle that a current transformer is saturated. Some other techniques bring more meaning to the breakpoint settings of the operating characteristic. The traditional differential concept is based on the current magnitude for estimating the restraining and biasing values. The significant imbalance comes from the secondary current of a current transformer with a resistive burden which collapses to zero when saturation occurs and it remains at zero until the time when the next zero crossing would have occurred. The study describes a new technique with improved characteristic and the differential concept does not depend on the current magnitude. The wavelet transform (WT) depends on high frequencies of the faulted signal produced owing to CT saturation. The proposed WT is based on Mexican basis function that was found to be an excellent discriminant for identifying the fault signals during the CT saturation. The time and frequency information during saturation are obtained rather than the current magnitude.


    1. 1)
      • S.H. Horowitz , A.G. Phadke . (1992) Power system relaying.
    2. 2)
      • Hughes, R., Legrand, E.: `Numerical busbar protection benefits of numerical technology in electrical substation', Int. Conf. on Developments in Power System Protection, IEE Pub. No. 479, 2001, p. 463–466.
    3. 3)
      • Rifitat, R.M.: `Considerations in applying power bus protection schemes to industrial and IPP systems', 37thIAS Annual Meeting. Conf. Record of the Industry Applications Conf., 2002, 2002, 3, p. 2231–2237.
    4. 4)
      • H. Haug , M. Forster . (1968) Electronic bus zone protection.
    5. 5)
      • Forford, T., Linders, J.R.: `Application of a high speed differential relay for buses, machines and cables', Presented at the Third Annual Western Protective Relay Conf., 18 October 1976, Spokane, WA.
    6. 6)
      • Androw, F., Suga, N., Murakami, Y., Inamura, K.: `Microprocessor-based busbar protection relay', Int. Conf. on Developments in Power System Protection, 1993, p. 103–106, IEE Pub. No. 368.
    7. 7)
      • Royle, J.B., Hill, A.: `Low impedance biased differential busbar protection for application to busbars of widely differential configuration', Int. Conf. on Developments in Power System Protection, 1989, p. 40–44, IEE Pub. No. 302.
    8. 8)
    9. 9)
    10. 10)
    11. 11)
      • Jiang, F., Bo, Z.Q., Redfern, M.A., Weller, G., Chen, Z., Xinzhou, D.: `Application of wavelet transform in transient protection-case study: busbar protection', Int. Conf. on Developments in Power System Protection, 2001, p. 197–200, IEE Pub. No. 479.
    12. 12)
      • Chen, Z., Bo, Z.Q., Xiang-ning, L., Caunce, B.R.J.: `Integrated line and busbar protection scheme based on wavelet analysis of fault generated transient current signals', Int. Conf. on Power System Technology, PowerCon 2004, vol. 1, , p. 396–401.
    13. 13)
      • Gafoor, S.A., Rao, P.V.R.: `A new wavelet transform based busbar protection', TENCON 2006, IEEE Region 10 Conf., November 2006, p. 1–4.
    14. 14)
    15. 15)
      • Brewis, K., Hearfield, K., Chapman, K.: `Theory and practical performance of interlocked overcurrent busbar zone protection in distribution substations', Seventh Int. Conf. on (IEE) Developments in Power System Protection, 2001, 9–12 April 2001, p. 475–478.
    16. 16)
      • Shashank, J., Msetcl, Dy.E.E.: `Backup to busbar protection with numerical distance protection', 15thNational Power Systems Conf. (NPSC), IIT Bombay, December 2008, .
    17. 17)
    18. 18)
      • Peck, D.M., Nygaard, B., Wadelius, K.: `A new numerical busbar protection system with bay oriented structure', Fifth Int. Conf. on Developments in Power System Protection, 1993, p. 228–231, IEE Pub. no. 368.
    19. 19)
    20. 20)
    21. 21)
    22. 22)
    23. 23)
      • An introduction to Wavelet. Available at:
    24. 24)
      • R. Murenzi , J.M. Combes , A. Grossman , P. Tchmitchian . (1988) Wavelets.
    25. 25)
      • ATP/EMTP Can. EMTP Users Group, January 1998, Version PC Salford 486 version 19.
    26. 26)
    27. 27)
    28. 28)

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