The influence of contaminations on HVDC conductor corona characteristics

The contaminations adhering to the surface of HVDC overhead transmission line affect the conductor corona characteristics, such as radio interference, audible noise and corona loss, remarkably. The measurement of corona characteristics in a laboratory corona cage is introduced in this paper, and some experiment results are presented. The artificial pollution experiments of DC transmission line were carried out in the corona cage. The contaminations, which plastered on the surface of conductor uniformly, composed of salt, kaolin, carbon. Corona ion current and audible noise was measured, and both negative and positive voltages were applied. The experiment results revealed that the contaminations on the conductor surface could increase the ion current and the audible noise of positive polarity conductor obviously. Corona characteristics varied with different contaminations´ component and the voltage polarity. Factors that affected the corona characteristics of contaminated conductor were analyzed in virtue of corona measurement datum of the corona current pulse.