Experimental Study on Spectral Characteristics of Corona-Generated Audible Noise From a DC Conductor

Abstract

In this paper, spectral characteristics of the corona-generated audible noise (AN) on a dc conductor are studied through a quadrate corona cage structure. To reduce the influence of background noise, all experiments are conducted in a semi-anechoic chamber. Different from previous investigations, time-domain waveforms of corona-generated AN are recorded and the frequency spectra are calculated based on the time-domain waveforms through the calculation method of A-weighted sound pressure level (SPL). The results confirm that the frequency spectra describe different characteristics at different applied voltages and have a close relationship with pulse amplitude and pulse repetition frequency. In addition, the AN from a negative corona discharge contains more high-frequency components than those from a positive corona discharge. The components with the frequency above 400 Hz contribute most to the resultant total A-weighted SPL. The differences of AN from positive and negative corona discharges are interpreted on the basis of the corona discharge physics. Furthermore, some correlation frequency components in the frequency spectrum are found and can be used to calculate the total A-weighted SPL by adding correction values. Finally, the influences of pulse amplitudes and repetition frequency on the frequency spectrum of AN are discussed on the basis of the time-domain stochastic model.