Influence of humidity on spectrum characteristics of audible noise of DC transmission lines

In order to investigate the influence of humidity on the A-weighting sound pressure values and spectrum characteristics of the audible noise, a laboratory scale corona cage made by stainless steel and a closed environment test chamber made by polymethyl methacrylate box have been constructed. The aluminum conductor steel reinforced (ACSR), which type is JL/G3A-1000/45 and the same as the conductors applied in ± 800kV DC transmission lines, is used and the ultraviolet detection imager is employed to indicate the intensity of the corona discharge in the experiment, which visualized ultra violet signals of the corona discharge. The results reveal that the A-weighting sound pressure level of audible noise increases with the increase of the humidity. With humidity increases from 9.2 g/m
³
to 25.8 g/m
³
, the value of A-weighting sound pressure values increases in the corona cage. The humidity affects the spectral components (>100Hz) more pronounced than low spectral components. The low frequency components are mainly the background noise, which construct the low frequency of audible noise. The correlations between the relative humidity and the spectrum of audible noise pave the way for the restriction the value of audible noise to a more reasonable degree for the surrounding area of lines in future.