The Study of Extremely Heavy Rainfall Effect on Power System Insulation Equipment Based on Electric Field Simulation

In recent years, severe rain flashover accidents occurred in substations and caused significant barrier to power system stability, a high percentage of which happened on transformer bushings. To study the effect of rain-curtain length and rain-drop quantity on the bushing external electric field, this paper established standard bushing model with dry sheds, rain-curtain model with water film and water curtain on sheds, and rain-drop model with water film and water drops on sheds. Based on Electric field simulation, it analyzed average field strength along shed surface and field strength in shed air gap. The result shows that both rain-curtain and rain-drop cause electric field distortion. As rain-curtain length increases, both the average field strength along shed surface increase, and field distortion in shed air gap enlarged. In condition of one rain drop, both the average field strength along shed surface and filed distortion in shed air gap increase compared to the standard model. But as the rain drop quantity increases, field strength along shed surface changes differently and distortion in shed air gap is partially diminished.