| Lightning is the main reason that causing lightning accident to transmission line. Since there is high frequency thunderstorm in Qinghai-Tibet plateau, and thundercloud is lower relatively, transmission line in this zone is easier to be stroke than in plain. To keep the Qinghai-Tibet Railway safe, it is important and necessary to start this research on improving lightning withstand level of 110kV transmission line along Qinghai-Tibet Railway.This paper summarizes and analyzes the thunderstorm condition along the Qinghai-Tibet Railway and simulates the lightning withstand level when lightning strikes the tower and line directly, discussing the factors that effect line arrester's function. Based on the model of 110kV transmission line along Qinghai-Tibet Railway, the influence of different installation condition of arresters in tower is analyzed. Then the arrester installation methods are recommended. At last, the protecting range, the discharge current and absorb energy of arrester during lightning strike are calculated.Reducing the tower grounding resistance is one of the useful methods to increase lightning withstand level of transmission line, but this method is limited in high soil resistivity areas. Since the soil resistivity reaches 3000Ω·m in Qinghai-Tibet, it is necessary to take measures to reduce soil resistivity. In this paper, experiments were conducted in a perennial frozen sediment area and Qinghai -Tibet railway. It is verified that the grounding modules have good performance for reducing grounding resistance in perennial frozen sediment areas and the design requirements can be fulfilled by parallel connecting necessary number of grounding modules.
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