Lightning Surge Analysis on Grounding Models of a Transmission Lines

Lightning has been one of the important problems for insulation design of power systems and it is still the main cause of outages of transmission and distribution lines. The lightning return-stroke current and the charge delivered by the stroke are the most important parameters to assess the severity of lightning strokes to power lines and apparatus. In order to calculate lightning surge analysis in power systems, appropriate models and parameters describing the components of systems should be required. It is also necessary to clarify how much those models would influence results of simulation. In other words, it is important to confirm how much probability of back flashover accidents would occur in changing grounding model or its input parameters. In this paper we compare some models for components in transmission tower and will show the influence to the back flashover results, especially focusing on grounding impedance model.