Corona Identification of Impulse Voltage and Current

Year 2018, Volume: 18 Issue: 1, 78 - 82, 23.02.2018

Emel Önal

Abstract

The corona effect in the
power system has a dominant role in reducing the efficiency of the high-voltage
lines. In this study, the current and voltage impulses, which are important in
corona determination, have been examined in frequecy spectrogram base from test
result. The frequency spectrogram graphs have been obtained from the
current-time and voltage-time variation by Matlab program. With these graphs,
frequency values have been found to provide an important clarification of the
insulation performance of electrical equipment for reliable and accurate
diagnosis. These values have been observed according to different conditions
like pressure, polarity, and insulation ambient. This spectrogram analysis can
be used to find the characteristic frequencies and eliminate the disturbance
effect. The time between corona steps decrease when Sulphur hexafluoride (SF6)
gas pressure is increased. The time of second corona is close to leader's
discharge time. Corona starts early when SF6 amount is decreased in gas
mixtures. The corona currents are large in the low SF6 gas mixtures, this
situation is related to the high insulation of the SF6 gas. A feature which is
dependent the frequency is not found.

Keywords

Corona, impulse, spectral analysis

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