Study on corona discharge spatial structure and stages division based on visible digital image colorimetry information

Due to the progress in photoelectric detection techniques, visible light images provide more abundant spatial structure information, which facilitates the detection of the colorimetry distribution in discharge images. In this study, the 50Hz AC high voltage power source was applied to the 15 mm needle-plane gap under room temperature and atmospheric pressure. The discharge images in the time scale of seconds were obtained by a high resolution digital camera. Two kinds of colorimetry indicators based on RGB model and HSI model were used to reflect the spatial structure and the colorimetry variation of discharge areas. Our experimental results demonstrated the growth, suppression, and penetration of the filamentary discharge and reflected that the relative intensity of characteristic color varies with different voltages. According to the variation of colorimetry information, we divided the AC corona stages, and the stage division results of two models are well correlated. Oscilloscope electrical signals verify the reliability of the colorimetry result, and colorimetry information shows the advantage of overcoming the randomness of one single discharge pulse amplitude. The colorimetry information extracted from images can represent the statistical characteristics of a large number of discharges, helping to characterize the spatial structure of corona discharges and evaluate its status.