Fibre-optic acoustic sensing of the presence and location of partial discharges in a high-voltage power transformer

Pao Yue-kong Library Electronic Theses Database

Fibre-optic acoustic sensing of the presence and location of partial discharges in a high-voltage power transformer

 

Author: Yeung, Kwong-tung Tony
Title: Fibre-optic acoustic sensing of the presence and location of partial discharges in a high-voltage power transformer
Degree: M.Sc.
Year: 1997
Subject: Electric transformers
Electric discharges
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Pages: v, 75 leaves : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1398635
URI: http://theses.lib.polyu.edu.hk/handle/200/693
Abstract: It has long been recognised that the level of partial discharge inside an oil-filled power transformer is a direct indication of the integrity of the insulation system. An acoustic detection method using externally mounted piezoelectric sensors for detecting partial discharges inside a power transformer has been introduced by E.Howells et. al. in the early 80's. The advantages and limitations of these detection systems were critically reviewed in this study. To overcome the inherent limitations of these systems, an all-fibre acoustic detection system using a Mach-Zehnder interferometer was introduced. This system , with its sensor installed inside the transformer tank, works on the principle that the acoustic pressure wave generated by the partial discharge when impinging on the fibre will change the refractive index of the fibre. This change in refractive index will in turn change the phase of the light emerging from the fibre. By detecting this phase change through the Mach-Zehnder interferometer and the demodulation circuit, the level of acoustic pressure and hence the level of partial discharge could be deduced. A detailed mathematical derivation of the pressure-phase change relationship was presented in this study. The mathematical models of the detection system and the demodulation circuit were also derived. Apart form detection, the discharge site could also be located by this system if more than three sensors were installed. By measuring the time of the acoustic pressure surge reaching these sensors, the discharge site could then be located by using the triangulation technique. In addition to the theoretical discussion, some practical considerations which arise when applying this detection system to real life situations were also discussed.

Files in this item

Files Size Format
b13986351.pdf 2.523Mb PDF
Copyright Undertaking
As a bona fide Library user, I declare that:
  1. I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
  2. I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
  3. I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.

     

Quick Search

Browse

More Information