Study On Lightning Protection Performance Of Ⅰ Line Of Xin Luo Of 750KV

According to the statistics of the long run data of UHV overhead transmission lines at home and abroad,the main reason for the fault of the overhead transmission line is the lightning strike.Lightning strike wire accident accounts for more than 90%lightning accidents in UHV line.With the increase of the voltage level of the transmission line,the demand for the safety and reliability of the power supply is also increasing.According to the latest drafted "lightning protection guide for overhead transmission lines",The single loop lightning trip rate of the overhead transmission line from 750kV to 1000kV is not more than 0.1 times/(km2·a).In order to reduce the lightning accidents of UHV transmission lines,it is of great significance to study the protection performance of the transmission lines.This paper is aimed at the problem that the monitoring data of the lightning monitoring system has been covered all over the country,but its monitoring data have not been deeply excavated and analyzed;In the calculation of lightning protection engineering,the recommended lightning current amplitude probability curve and the lightning flash density calculated according to the thunderstorm days are generally used for lightning protection calculation,resulting in large deviation of calculation results;In the EGM model,the terrain parameters are difficult to obtain;According to the experience of lightning protection design and measures,it is not fully combined with the actual situation of the line,so that the lightning trip accident rate is high.Taking the I line of 750kV in Shaanxi Province as an example,the data processing and analysis of many years are carried out in combination with the database software and the GIS software.Study on the frequency,intensity and density distribution of ground flashes in Shaanxi Province.Use of grid statistics to obtain actual ground flash density in transmission line corridor for many years,at the same time,the amplitude probability curve of the lightning current is fitted to the actual ground flash of the I line of the Xin Luo line.Combined with the two development of Google earth,this paper presents a method of calculating the ground inclination of any point in the span.Based on the lightning parameters and terrain parameters obtained in this paper,we use the improved EGM theory model to calculate the shielding failure.The establishment of EGM model,ATP multi wave impedance model were studied to reduce protection angle,the arrester on Lightning level influence.Based on this,the lightning protection measures and two kinds of lightning protection schemes for the difference of the I line of the Xin Luo line are put forward,and the comparison is made from the aspects of economy,technology.The I line of the reformed Xin Luo line can reach the specified index of the rate of tripping.