Research On Lightning Protection And Grounding Technique In Qinghai-Tibet Railway Transmission Line And Substation

Qinghai-Tibet Railway passes through Qinghai-Tibet Plateau. The length of this railway is about 1100km, the altitude of 84% length is above 4500m and 50% of railway passing through the perennial frozen sediment soil area of Qinghai-Tibetan Plateau. This zone has high frequency thunderstorm, and the soil resistivity reaches to 3000Ω·m. The frozen soil and altiplano are the main problems during the construct of Qinghai-Tibet Railway. Because of the special geologic and climate condition, the design and implement of grounding system and lightning protection in Qinghai-Tibet Railway is difficult to that in the other zones. Today, the systemic research of grounding system and lightning protection in Qinghai-Tibet Railway is blank in the world. To keep the Qinghai-Tibet Railway safe, it is importance and necessary to start this research.To summarize and analyze the thunderstorm condition along the Qinghai-Tibet Railway, the form, characteristic, activity rules and lightning parameters of plateaus thunderstorm are introduced. Some protection principles to transmit electricity systems in this zone are recommended. To keep the lightning protection level of 110kV transmission line along the railway meets the design demands and reduces the construct difficulty, the methods of fix arrester and enhance allowable value of tower grounding system are recommended. First, the simulative module of 110kV transmission line is set up. The influence of different fix condition of arresters in tower on lightning protection level is analyzed. Then the arrester fix methods and the new allowable value of tower grounding system are recommended. At last, the discharge current and absorb energy of arrester during lightning strike are calculated.To reduce the grounding resistance of substation, the geologic condition of Ge-La segment is introduced. The influence of temperature and humidity on the soil resistivity is obtained by the experiments. The design principles of substation grounding grid are recommended. The choose rules of grounding grid area, vertical rod and the seasonal influence on the resistance of grounding grid are Qinghai-Tibet Railway passes through Qinghai-Tibet Plateau. The length of this railway is about 1100km, the altitude of 84% length is above 4500m and 50% of railway passing through the perennial frozen sediment soil area of Qinghai-Tibetan Plateau. This zone has high frequency thunderstorm, and the soil resistivity reaches to 3000Ω? m. The frozen soil and altiplano are the main problems during the construct of Qinghai-Tibet Railway. Because of the special geologic and climate condition, the design and implement of grounding system and lightning protection in Qinghai-Tibet Railway is difficult to that in the other zones. Today, the systemic research of grounding system and lightning protection in Qinghai-Tibet Railway is blank in the world. To keep the Qinghai-Tibet Railway safe, it is importance and necessary to start this research.To summarize and analyze the thunderstorm condition along the Qinghai-Tibet Railway, the form, characteristic, activity rules and lightning parameters of plateaus thunderstorm are introduced. Some protection principles to transmit electricity systems in this zone are recommended. To keep the lightning protection level of 110kV transmission line along the railway meets the design demands and reduces the construct difficulty, the methods of fix arrester and enhance allowable value of tower grounding system are recommended. First, the simulative module of 110kV transmission line is set up. The influence of different fix condition of arresters in tower on lightning protection level is analyzed. Then the arrester fix methods and the new allowable value of tower grounding system are recommended. At last, the discharge current and absorb energy of arrester during lightning strike are calculated.To reduce the grounding resistance of substation, the geologic condition of Ge-La segment is introduced. The influence of temperature and humidity on the soil resistivity is obtained by the experiments. The design principles of substation grounding grid are recommended. The choose rules of grounding grid area, vertical rod and the seasonal influence on the resistance of grounding grid are of the grounding rods by measure the special node port resistances. To reduce the cost in grounding resistance measurement of grounding grid along Qinghai-Tibet Railway, a new measurement device is designed. According to the soil structure and grounding grid, this device can determine the spots where voltage pole and current pole are installed. At the same time, Frequency conversion technology is used to avoid disturbances.