Influence of surface contamination of conductor on positive corona-generated audible noise spectrum characteristics of HVDC system

Surface contamination of high-voltage direct-current power transmission lines has a large influence on corona characteristics. The audible noise of the polluted conductors is much higher than clean conductors. Little is known about the effect of the surface conditions of conductors on spectrum characteristics of the positive corona-generated audible noise under a high voltage. In order to investigate the influence of surface contamination produced by atmospheric pollution on the spectrum of the audible noise, this paper presented the measurement of spectrum characteristics of the audible noise of positive corona discharge in a laboratory corona cage. We researched the influence of deposition and relative permittivity of the contamination on the spectrum characteristics of the positive corona-generated audible noise. The relationships among these factors were consequently acquired. The results revealed that the spectral components of the audible noise of clean conductor were obviously different with the increase of the applied voltage. The spectral components (>1kHz) of the polluted conductors were much higher than those of the clean conductors. The contamination adhering to the surface of conductors affected spectral components (>1kHz) much more obviously than low spectral components, and the results were analyzed in this paper. The conclusion lays a foundation for researching the influence of the surface conditions on the corona-generated audible noise.