| With the continuous development and improvement of power grid,the scale of transmission line is growing rapidly.Most of the transmission lines are arranged overhead.Many of the transmission lines pass through areas with complex terrain,high ground flash density and high soil resistivity.In recent years,the frequent occurrence of lightning transmission line accidents has brought many adverse factors to business operation and social stability,which has attracted people's attention.How to take effective measures to improve the lightning resistance level of overhead transmission lines and reduce the line trip accidents caused by lightning stroke has become an urgent research topic.Through the joint efforts of all sectors of society,people have a deeper understanding of the basic laws of lightning activities,developed a series of lightning protection devices,and formulated the corresponding lightning protection specifications.However,the specific application of lightning protection strategy still needs to be summarized,analyzed and improved.This paper takes the overhead transmission line in Zibo area as the research object,analyzes the lightning activity and the distribution characteristics of line lightning damage in the past ten years.Two typical lightning trip cases are selected to study the specific fault conditions and causes.Combined with the lightning flashover principle of transmission lines,the lightning protection status of overhead transmission lines in Zibo area is analyzed and evaluated,and the existing problems in lightning protection are found out.Using ATP-EMTP electromagnetic transient analysis software,according to the actual parameters,the lightning current model,tower multi wave impedance model,insulator model,arrester model and so on are built to carry out the simulation research of overhead transmission lines.The influence of measures such as reducing tower ground resistance,installing arresters according to the strategy combination on improving the lightning resistance level of transmission lines and improving the safety and economic benefits is discussed.Based on the practical application of the project,the differential control scheme of overhead transmission line is put forward.(1)Implement the whole process management of lightning protection of overhead transmission lines,coordinate project planning,construction and operation and maintenance,and realize closed-loop process management and control.(2)Based on the micro terrain and ground lightning conditions,the risk assessment of the whole line is carried out,the change of lightning activities along the route is analyzed,and the vulnerable pole section is graded,and the differential strategy is implemented forlightning protection transformation.(3)According to the seasonal and regional characteristics,carry out the measurement and treatment of the grounding resistance of transmission lines and towers,and establish a special dynamic account.According to the different terrain,we adopt the targeted resistance reduction method,and innovate the application of new technology engineering projects to reduce the grounding resistance.The lightning arrester shall be installed for the tower in the typical section according to the strategy combination.(4)The transmission line visualization system and lightning location system are combined to strengthen the observation of micro meteorology.A transmission line fault location device is arranged.According to the actual situation of overhead transmission lines in Zibo area,the corresponding implementation measures are formulated. |
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