Computer-aided analysis of high-speed protective relays

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© The Institution of Electrical Engineers
Published 24/07/2012

Abstract

Most of the modern distance relays are designed to avoid overreaching due to the transient d.c. component of the fault current, whereas a more likely source of transients in e.h.v. systems is the oscillatory discharge of the system charging current into the fault. Until now attempts have not been made to reproduce these transients in the laboratory. This paper describes an analogue and an accurate digital simulation of these harmonic transients. The dynamic behaviour of a typical polarised mho-type relay is analysed, and results are presented. The paper also advocates the use of active filters for filtering the harmonics associated with e.h.v. system, and hence, to improve the speed of response and accuracy of the protective relays.

Inspec keywords: electrical engineering applications of computers; relays; simulation; relay protection; transients; computer aided analysis

Other keywords: EHV; computer aided analysis; high speed protective relays; analogue simulation; active filters; oscillatory discharge; line charging effects; digital simulation; distance relays; dynamic behaviour of mho type relay; electrical engineering applications of computers; transients; harmonics

Subjects: Power system protection; Power engineering computing

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