A study of high voltage direct current conductor corona in a purpose built corona cage.
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Date
2003
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Abstract
The main aim of this study was concerned with the design and commissioning of a
corona cage, which could be used under Direct Current (DC) conditions. The cage
was designed based on empirical formulas and equations as well as electric field
simulations. The designed cage was then fabricated. The commissioning of the cage
was undertaken in the High Voltage Direct Current (HVDC) laboratory at the
University of Durban - Westville (UDW).
Tests to determine the effects of a silicone coating as well as wind on the corona
performance of conductors were undertaken. The tests were done in order to
determine ways of improving the corona performance of conductors under HVDC
potential. The tests were carried out using various conductor surface conditions. The
wind tests were made possible by using a powerful fan. A silicone coating was also
used to determine the effects that it would have in mitigation of corona activity on
HVDC conductors. The conductors were tested without the coating, with half of their
length coated and then fully coated.
Results showed that the effect of wind on corona generation in a corona cage is
minimal. The effect of the silicone coating was that it increased the corona currents
measured in the corona cage. The conductors with no coating generated the lowest
currents, the half coated conductors generated the second highest measured currents
and the fully coated conductors generated the most corona.
Analysis of the increased currents showed that the increase in corona currents due to
the silicone coating could be attributed to three factors. Firstly the coating caused an
increase in conductor to cage capacitance. Secondly, partial discharges could have
occurred in the silicone due to microscopic air particles and lastly, the increase in
corona currents could be ascribed to the effect of the boundary conditions on the
boundary between the conductor and the coating.
Description
Thesis (M.Sc.)-University of Durban-Westville, 2003.
Keywords
High voltage direct current., Electrical engineering., Theses--Electrical engineering.