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A new technique of differential relaying: The Δ-differential relay

  • University of Michigan, Ann Arbor

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Standard percentage differential relaying with through current restraint is insensitive to high impedance (i.e. low fault current) faults when applied to apparatus which experience substantial, near 1.0 pu, prefault through currents. A new technique of differential protection is proposed which considers only fault contribution currents through the use of microcomputer cancellation of the prefault through currents. This new form of differential relaying maintains the external fault selectivity of standard percentage differential relaying, has a large buffer zone between the tripping and restraint zones of relay operation, and is substantially more sensitive to high impedance faults than the standard arrangement. This paper presents the theory for this relay, a simplified analysis of the effects of CT errors on the relay operation, and the experimental results for a real time laboratory version of the relay using a 16-bit single-board microcomputer.

Original languageEnglish
Pages (from-to)4164-4170
Number of pages7
JournalIEEE Transactions on Power Apparatus and Systems
VolumePAS-101
Issue number10
DOIs
StatePublished - 1982
Externally publishedYes

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