直流电压下绝缘子表面电荷分布中"电荷斑"模式的分析与研究

The charge accumulation on the surface of downsized GIL insulators under DC voltage usually presents two different distribution phenomena, which can be called "dominant pattern" and "charge speckle pattern" respectively. The "dominant pattern" is a larger area with uniform and gradient charge distribution, and the "charge speckle pattern" usually consists a number of speckles or stripes. Experiments show that the charge accumulation of the "charge speckle pattern" is different from the "dominant pattern", which fails to represent the essential characteristics of the charge accumulation of the insulator. In order to quantify the characteristics of charge accumulation accurately, the "charge speckles" need to be separated. In this paper, the reasons for the formation of "charge speckle" are analyzed, the maximum inter-class variance method is proposed to separate "charge speckles". At last, the "dominant pattern" charge distribution after the separation of "charge speckles" is quantitatively characterized. The analysis shows that the characterization results are in good agreement with the experimental and the simulation results.