Department of Computer Science and Electrical
Engineering
Monitoring of Distribution System Power Quality
Final Year Honours Thesis
Jeff McGuire
Abstract:
'Power Quality' is a term still very much in its infancy. However, with
the immense growth of the power electronics and control systems industries
currently being experienced, its importance should not be underestimated.
The term power quality is used to describe any abnormal behaviour in a
power system arising from voltage or current faults which adversely
affects the usual operation of electrical equipment. Power quality
disturbances can have catastrophic affects on systems. A major computer
centre in the United States reports that a two second interruption in the
power supply results in a $600,000 loss. Electrical utilities also share
concerns about power quality issues. With deregulation of the electricity
industry, and hence growing competition between utilities, the financial
impact of lost customers is quite significant.
A thorough understanding of power systems is imperative before any work in
the area of power quality is commenced. A knowledge of the varying types
of loads in use, their operation, and affect on nearby equipment should
also be obtained. However, these skills are only of use if the equipment
used to conduct power quality surveys has better than average
capabilities.
This thesis report firstly introduces the reader to the fundamentals of
power quality, before proceeding to an analysis of three case studies. The
first case study was conducted at the Caltex Oil Refinery in the Brisbane
suburb of Lytton for a duration of 17 days, followed by a study in the
Chemistry building at The University of Queensland for 11 days, before the
final study in the laser laboratory within the Physics also at The
University of Queensland is presented. A thorough description of the
equipment used in the surveys is also presented, as well as a description
of another piece of equipment useful in studying power quality.
After careful analysis of the results obtained from each survey, it was
found that the quality of the power at each location was quite
satisfactory, with the exception of a moderate degree of imbalance between
the phases in each case. The most likely cause of this imbalance
experienced was found to be the operation of many non-linear loads in each
site with the exception of the Chemistry building, where the cause was
probably due to the majority of loads being single phase. The laser
laboratory experienced two short duration transient faults, which can be
eliminated by the use of an AC power filter, of which a description of its
operation is presented. The thesis paper concludes with suggestions on how
to approach future work in this area in order to gain extra benefit from
the experience.
Thesis Report:
thesis.pdf
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Conference paper:
conference paper.pdf
About the Author
Department of Computer Science and
Electrical Engineering
Last modified 15/10/99