New Defend Thunder Technique Application Study Of Jiangjin 35 KV Transmission Line

As the main transmission line of Jiangjin bureau, the 35kV transmit lines faces a formidable difficulty in lightning-proof task. This paper sufficiently studied the lightning basic parameter of Chongqing in recent years, The results of which indicate that Chongqing is belonged to strong -lightning-day zone, has about 95 lightning days per year and has 7.022 hours per lighting day. Moreover the common ground flashing density is 0.1216/km2. d. Therefore, it is necessary to study new methods and measurements to prevent transmission lines from lightning fault for improving lightning withstand capacity of 35kV lines.According to the Shuangjin 35kV lines' lightning defend operation information, this paper built lightning striking tower numeric calculation models, considering factors of landform of transmission line aisle and spanning instance. Based on that model, it has made a lot of calculations about the diffusing coefficient, lightning withstand level and lightning withstand level of lightning counter-striking lines as lightning-striking lines' tower or pole, before and after the line is equipped with MOA. The results indicate:(1) The lines' lightning withstand level was improved rapidly after line surge arrester was fixed: improved 1 to 2 times with a group of arrester, improved 2.5 to 3 times with 2 groups and improved 3 to 4 times with 3 groups.(2) Tower grounding resistance can affect the lightning-proof property of transmission line and the function of line-surge arrester. With the increasing of their value, the line-surge arrester action weakens. And the lightning-withstand level decreases. But as the resistance increase to a certain value (about 30 ), this effect weakens.(3) The calculation results of the diffusing coefficient at the time of lightning striking the transmission line tower with/without MOA are valuable to engineering application.Based on the research, we have rebuilt 35kV Shuangjin line for improving the lightning withstand level with fixing line-surge arrester to improve line lightning withstand level, tower load directly grounding to prevent load connect trouble and disposing the tower grounding device with concrete to avoid rust and to reduce the grounding resistance. These new methods and measurements improved the lines' lightning withstand level in some degree. The operation results more than one year after the rebuilding revealed that the effect of the pretend thunder measurements were tremendous, and the lightning tripping outage was reduced rapidly.