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Energies 2014, 7(7), 4571-4587; doi:10.3390/en7074571
Article

Saturation Detection-Based Blocking Scheme for Transformer Differential Protection

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Received: 26 February 2014; in revised form: 27 June 2014 / Accepted: 10 July 2014 / Published: 18 July 2014
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Abstract: This paper describes a current differential relay for transformer protection that operates in conjunction with a core saturation detection-based blocking algorithm. The differential current for the magnetic inrush or over-excitation has a point of inflection at the start and end of each saturation period of the transformer core. At these instants, discontinuities arise in the first-difference function of the differential current. The second- and third-difference functions convert the points of inflection into pulses, the magnitudes of which are large enough to detect core saturation. The blocking signal is activated if the third-difference of the differential current is larger than the threshold and is maintained for one cycle. In addition, a method to discriminate between transformer saturation and current transformer (CT) saturation is included. The performance of the proposed blocking scheme was compared with that of a conventional harmonic blocking method. The test results indicate that the proposed scheme successfully discriminates internal faults even with CT saturation from the magnetic inrush, over-excitation, and external faults with CT saturation, and can significantly reduce the operating time delay of the relay.
Keywords: saturation detection based blocking; harmonic blocking; current differential relay; transformer protection; operating time delay saturation detection based blocking; harmonic blocking; current differential relay; transformer protection; operating time delay
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Lee, B.E.; Lee, J.; Won, S.H.; Lee, B.; Crossley, P.A.; Kang, Y.C. Saturation Detection-Based Blocking Scheme for Transformer Differential Protection. Energies 2014, 7, 4571-4587.

AMA Style

Lee BE, Lee J, Won SH, Lee B, Crossley PA, Kang YC. Saturation Detection-Based Blocking Scheme for Transformer Differential Protection. Energies. 2014; 7(7):4571-4587.

Chicago/Turabian Style

Lee, Byung E.; Lee, Jinsik; Won, Sung H.; Lee, Byongjun; Crossley, Peter A.; Kang, Yong C. 2014. "Saturation Detection-Based Blocking Scheme for Transformer Differential Protection." Energies 7, no. 7: 4571-4587.


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