Analysis of self-correlation characteristics of corona current spectrum on UHVDC transmission line

Analysis of the spectral characteristics of corona current is of great significance for optimizing the design of transmission lines. In this paper, a great number of corona current waveforms were measured on conductors in a large outdoor corona cage and actual UHVDC test transmission lines. First, a linear relationship with proportionality coefficient of approximately 1 between the spectrum components of corona current in the range of 5-20 kHz was found. Second, based on the similarity of the correlations between the spectrum components, a universal linear expression representing the correlation between the spectrum components of corona current under different conditions was obtained through data fitting. Finally, with the obtained expression, the spectrum components of the corona current at frequencies in the range of 5-20 kHz were estimated according to the spectrum component at 5 kHz, and then measured on the high altitude UHVDC test line segment located in Tibet, China. By comparing the estimated values with the measured ones, the validity and accuracy of the self-correlation expression between spectrum components was verified.