The corona-generated audible noise (AN) has become one of decisive factors in the design of high voltage direct current (HVDC) transmission lines. The AN from transmission lines can be attributed to sound pressure pulses which are generated by the multiple corona sources formed on the conductor, i.e., transmission lines. In this paper, a detailed time-domain characteristics of the sound pressure pulses, which are generated by the DC corona discharges formed over the surfaces of a stranded conductors, are investigated systematically in a laboratory settings using a corona cage structure. The amplitude of sound pressure pulse and its time intervals are extracted by observing a direct correlation between corona current pulses and corona-generated sound pressure pulses. Based on the statistical characteristics, a stochastic model is presented for simulating the sound pressure pulses due to DC corona discharges occurring on conductors. The proposed stochastic model is validated by comparing the calculated and measured A-weighted sound pressure level (SPL). The proposed model is then used to analyze the influence of the pulse amplitudes and pulse rate on the SPL. Furthermore, a mathematical relationship is found between the SPL and conductor diameter, electric field, and radial distance.

Although transverse wind exerts an important influence on the distribution of the ion current density under HVDC transmission lines, very few experiments involving stable wind have been used to verify the numerical model. To overcome the variability of natural wind, a low-speed wind tunnel was used to produce stable wind in this research. An experimental platform was set-up in the wind tunnel, to measure the ion current density of DC wires. Based on the experiment, transverse wind exerted significant influence over the distribution of the ion current. The numerical model was discussed and the results showed reasonable agreement with the measured values for different wind speeds.

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