Distance protection of multiple-circuit shared tower transmission lines with different voltages: Part I: Fault current magnitude

Research output: Contribution to journalJournal article

Abstract

Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. This study presents a detailed theoretical analysis of such combined faults, including the development of a formula for estimating the magnitude of the short-circuit current. It is demonstrated that if the faulted phase from the higher voltage level leads the faulted phase from the lower voltage level, a distance relay at the higher voltage level sees the fault in the forward direction, whereas a distance relay at the lower voltage level sees the fault in the reverse direction. The opposite happens if the lower voltage level leads the higher voltage level. It is also demonstrated that the magnitude of fault currents of combined faults is normally slightly larger than of equivalent single-phase-to-ground fault at the higher voltage level. Part II will continue the research work and focus in the fault loop impedance RX diagrams.
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Details

Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. This study presents a detailed theoretical analysis of such combined faults, including the development of a formula for estimating the magnitude of the short-circuit current. It is demonstrated that if the faulted phase from the higher voltage level leads the faulted phase from the lower voltage level, a distance relay at the higher voltage level sees the fault in the forward direction, whereas a distance relay at the lower voltage level sees the fault in the reverse direction. The opposite happens if the lower voltage level leads the higher voltage level. It is also demonstrated that the magnitude of fault currents of combined faults is normally slightly larger than of equivalent single-phase-to-ground fault at the higher voltage level. Part II will continue the research work and focus in the fault loop impedance RX diagrams.
Original languageEnglish
JournalIET Generation, Transmission & Distribution
Volume11
Issue number10
Pages (from-to)2618-2625
Number of pages8
ISSN1751-8687
DOI
StatePublished - Jul 2017
Publication categoryResearch
Peer-reviewedYes
ID: 244601914