Influence of pollution on surface streamer discharge

The outdoor insulators in the transmission lines are apt to accumulate pollution on the surface in the atmospheric environment. The pollution flashover is liable to occur after the pollution becomes wet, which has caused great harm to the stable and safe operation of the power grid. The generation and development of the surface streamer discharge is an essential stage before the pollution flashover. Hence, the research on the characteristics of the surface streamer discharge can reveal the mechanism of the pollution flashover. In the paper, characteristics of the streamer discharge along the pollution insulation surface were measured by three photomultipliers and an ultraviolet camera in the three-electrode arrangement. The streamer stable propagation electric field, velocity, light intensity, and propagation paths along the pollution insulation surface were compared with that along the clean insulation surface. There were significant differences between the streamer discharge along the clean and pollution insulation surface. Furthermore, the pollution layers with different salt densities and ash densities also had an important influence on the surface streamer discharge. These results revealed the mechanism of the pollution flashover, and provided a theoretical and experimental basis for the design of improvement measures for the pollution flashover voltage.