Research On Lightning Protection Of Transmission Line Of Lhasa-Linzhi Section Of Sichuan-Tibet Railway

At present,the relevant national standards only give allowable value requirements on the power frequency grounding resistance about the grounding device,the design and construction of the project is in accordance with the allowable value of the power frequency grounding resistance too,and the true impact of the role of impulse grounding resistance did not make a clear allowable value requirement,the difference in characteristics between the power frequency grounding resistance and the impulse grounding resistance can lead to excessive grounding of the grounding device or does not satisfy the requirement of lightning protection in some special cases.In this paper,in the background of Tibet and the Changdu power grid network project,Sichuan-Tibet railway Lhasa to Linzhi section of the power supply project in China Electric Power Research Institute,study on the power frequency characteristic and the impact characteristic of the horizontal grounding device and the vertical grounding device through the simulation test and the true type test,then summarizes the resistance reducing measures,and put forward the optimization scheme for the grounding device under different soil resistivity,and finally put forward the grounding scheme suitable for each section along the Lhasa to Linzhi Railway to further improve the lightning protection performance of the grounding device grounding device and ensure the most reasonable use of grounding material,to ensure the safe and economical operation of the power system.Firstly,this paper analyzes the law of lightning activity and geological conditions along the Lhasa-Linzhi section of Sichuan-Tibet Railway,and puts forward the design principle of tower grounding device,and puts forward the double safety design principle to meet the power grounding resistance and impulse grounding resistance and economic design principle.Then,using the electromagnetic analysis software CDEGS based on the moment method,the power grounding characteristics and the impulse grounding characteristics of the tower grounding device are analyzed qualitatively by the horizontal grounding device and the vertical grounding pole,the influence of soil,type and size of grounding divice on the grounding resistance and impact coefficient were analyzed under the condition of uniform soil and stratified soil.In order to make up for the deficiency of CDEGS,we can further study the impact characteristics of the horizontal grounding by using the true type test.The influence of the amplitude of the impulse current and the injection point on the grounding resistance is analyzed,andsome results of the simulation experiment are verified,the power frequency and impact characteristics of the horizontal grounding device and the vertical grounding resistance are summarized and the differences between them are summarized.And then summed up the resistance reduction measures under different conditions can be applied to Lhasa to Linzhi section.Finally,compared with the current grounding design standard,using the numerical calculation method for impulse grounding resistance based on considering the effect of electromagnetic wave propagation analyze the grounding scheme quantitatively,and put forward the optimization scheme of grounding device.By optimizing,up to 47%of grounding material can be saved at low soil resistivity,and 16%increase in high soil resistivity,grounding material can meet the double safety requirements of power grounding resistance and impulse grounding resistance to achieve safety and economy claim.