Thesis

Implementation of a Faraday effect based optical current transducer using digital signal processing techniques

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Awarding institution
  • University of Strathclyde
Date of award
  • 2000
Thesis identifier
  • T9993
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • In recent years, the idea of replacing conventional high voltage (HV) current transformers (CTs) with optical current transducers (OCTs) has gained increased attention. This is a direct consequence of a progress in fibre-optic sensing technology which can now provide a means of current measurement with potentially superior performance and functionality over the conventional CTs. Optical current transducers offer many advantages including inherent high voltage insulation, intrinsically safe failure modes, immunity to electromagnetic interference, enhancement in signal bandwidth and dynamic range, ease of integration into future digital control and protection systems and reduced costs. Additional benefits include reduced size and weight of the transducers compared to the conventional devices providing easier installation and potentially reduced substation land requirements. The research work presented in this thesis is related specifically to compensation of environmental factors within operation of the Faraday Effect based OCT using digital signal processing (DSP) techniques. The thesis analyses measurement errors within the optical current sensor attributed mainly to thermal influences, vibration induced noise and magnetic cross-talk. It is shown that the use of a fully automatic, real time, processing facility, as developed within this research work, for implementation of software based temperature, vibration and magnetic cross-talk compensation schemes will satisfy the accuracy specifications demanded from the OCT. It is also demonstrated, that the same DSP system can facilitate the linearisation of the sensor response characteristic in real time operation and increase the maximum modulation level of the measured signal. This allows for use of an extended sensor dynamic range and relaxes some critical design requirements of the photodetector circuit.
Advisor / supervisor
  • McDonald, Jim, 1965-
Resource Type
DOI
EThOS ID
  • 248515

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