Finite Fourier transform distance protection for e.h.v. transmission systems.

  • K. F. Al-Janabi

Student thesis: Doctoral ThesisPhD


This thesis describes the development of a new distance protection relay for the protection of extra high voltage (e.h.v.) transmission lines. The new algorithm developed is based on relating the Fourier Transform of a finite window of information to the first order transmission line model measurands of the fault loop impedance. This algorithm is implemented using a discrete signal processing technique. In this technique samples of voltage and current are fed to the relay. The algorithm is tested using a conventional hardware structure. This structure consists of a data acquisition unit, a microcomputer and a multiplier unit incorporating a fast hardware multiplier. For the process implementation, a quadrilateral characteristic is used and a trip signal is initiated when the measurands converge to this region. In order to maintain the speed-accuracy trade off, a decision logic process incorporating an up/down counter was used. The relay performance is investigated using a programmable transmission line (PTL) equipment, from which a series of fault waveforms were applied, corresponding to various line configurations and inception angles for both solid and resistive faults. The relay directional stability was studied for reverse and forward faults.
Date of Award1985
Original languageEnglish
Awarding Institution
  • University of Bath

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