Statistical Method Of Lightning Parameters For Transmission Line Corridor In Thunderstorm Area

In recent years,the scale of power network in our country is enlarged,and land resources are tight.The phenomenon of multi-circuit line sharing transmission line corridor is very common,and the lightning hazard risk of transmission line becomes more and more serious,so it is important to analyze the lightning hazard risk of transmission line corridor.The lightning distribution is the main factor to evaluate the lightning hazard risk of transmission lines.Grid method is a traditional method to analyze the ground flicker distribution,but it has some limitations in the application of transmission line corridor.At present,there is no good statistical method for the ground lightning parameters of transmission line corridor which can compensate for the limitation of grid method.So this paper presents a statistical method of ground lightning parameters of transmission line corridor in strong thunderstorm area.In this paper,the grid method is used to analyze the parameters of the ground flashover in the study area.The distribution of lightning time,the density of lightning and the accumulative probability of lightning current in the study area are preliminarily understood.The limitations of grid method are analyzed from four aspects:the size of grids,anchor point selection,edge estimation accuracy and quantification error of grid method.The kernel density estimation is used to estimate the ground flicker parameters of the transmission line corridor.This method can directly reflect the distribution of the statistical data according to the statistical probability of the sample.In the process of kernel density estimation a probability density function is generated for each sample to be counted.Any region in the statistical range can obtain a distribution probability which is not affected by the number of statistical samples.The limitation of grid method can be remedied in practical application.Combined with the distribution of ground lightning density and tower tower,the parameter of "Tower-flash composite density" is put forward.The "Tower-flash composite density" in Fangchenggang area from 2012 to 2014 is calculated.It is found that the correlation between composite density and lightning damage is higher than that between lightning density and lightning damage.It is found that the kernel density estimation can be used to calculate the short-time lightning parameters effectively.In view of the continuous lightning tripping accidents caused by two strong thunderstorms in Fangchenggang area,the lightning distribution is calculated in units of 15 minutes.It is found that there is a positive correlation between lightning failure and the intensity of ground flash.It is found that the short-time lightning parameter statistics based on kernel density estimation can reflect the formation and development of thunderstorms.The statistical method proposed in this paper can effectively describe the ground flashover parameters of transmission line corridor in strong thunderstorm area,and make up for the limitation of grid method.The application of this method can provide the basis for the differential lightning protection of transmission lines and lay a foundation for the lightning disaster early warning in the strong thunderstorm area.