Saturation Detection-Based Blocking Scheme for Transformer Differential Protection

Byung Eun Lee, Jinsik Lee, Sung Ho Won, Byongjun Lee, Peter A. Crossley and Yong Cheol Kang
Additional contact information
Byung Eun Lee: Wind Energy Grid-Adaptive Technology Research Centre, Chonbuk National University, Chonju 561-756, Korea
Jinsik Lee: Department of Electrical Engineering and Wind Energy Grid-Adaptive Technology Research Centre, Chonbuk National University, Chonju 561-756, Korea
Sung Ho Won: Korea Electrical Contractors Association, #533-2, Deungchon-2Dong, Gangseo-Ku, Seoul 157-718, Korea
Byongjun Lee: Department of Electrical Engineering, Korea University, Seoul 136-701, Korea
Peter A. Crossley: The School of Electrical & Electronic Engineering, the University of Manchester, Manchester M13 9PL, UK
Yong Cheol Kang: Department of Electrical Engineering, Wind Energy Grid-Adaptive Technology Research Centre and Smart Grid Research Centre, Chonbuk National University, Chonju 561-756, Korea

Energies, 2014, vol. 7, issue 7, 1-17

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 (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2014
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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