Fractional Order Model And Numerical Calculation Method Of Frequency Dependent Overhead Transmission Line Port

In the operation of the power system,overhead transmission lines are essential infrastructure for connecting the substations and important users.Lightning strikes overhead lines caused the rapid rise in voltage on the line to produce lightning over-voltage,resulting in lightning strike accidents seriously affected the safe and reliable operation of the power system.Therefore,the establishment of a more effective and accurate overhead transmission line port model,not only in the electromagnetic transient calculation of a wide range of applications,but also to further study the transmission line lightning protection.Based on the fractional calculus theory,this paper establishes a more accurate,effective and concise model of the overhead line port fractional model based on the frequency variation characteristics of the overhead itself and the soil electrical parameters,and makes an in-depth study on its numerical calculation method.Firstly,the characteristic impedance of overhead line has been fitted by the method of fractional vector matching technique,recursive convolution method based on the time domain model of the equivalent current source,we get the fraction model of frequency dependent overhead transmission line port.Secondly,the numerical calculation method for the fractional order model is obtained by using the fractional order difference method for the proposed model.Based on the theory of phase mode transformation,respectively for each characteristic impedance modulus of fractional order vector matching fitting,the overvoltage calculation of three frame line port of lightning,and through the MATLAB language and EMTP-ATP software to verify the correctness and effectiveness of the proposed model and algorithm.Finally,combined with the numerical calculation model of tower and calculated the lightning overvoltage of 220 kV double circuit transmission lines.