Experimental Study on Sound Characteristics Produced by DC Corona and Pulsed Discharges.

The audible noise (AN) production mechanism caused by corona discharge in ultrahigh voltage transmission lines is less understood. The study on sound pressure characteristic is necessary to obtain the inherent relation between AN and corona discharge. In this paper, the experimental research on single-point direct current (dc) corona discharge was evolved and the time-domain sound pressure waveform was obtained using capacitor microphone. The experiment results show that the dc corona discharge comprises multiple subsequent discharge pulses. The discharge voltage and the electrode polarity have a direct effect on the rising time and pulsed width of the single current pulse. The waveform of sound pressure produced by single discharge is a bipolar microsecond pulse, which lags behind the current pulse in time domain. The time delay is propagation time of sound signal from the discharge spot to the measurement spot. Based on the corona discharge characteristic in dc voltage, the experiment platform for nanosecond pulsed discharge was built to obtain the relation between discharge parameter and sound parameter. The characteristics of sound pressure in different discharge conditions were analyzed. The study results indicate that the sound pressure produced by pulsed discharge is similar with that produced by corona discharge. The experiment platform for pulsed discharge can be used to research the AN production mechanism by dc corona discharge. [ABSTRACT FROM AUTHOR]