Research On Time-domain Solution Of Crosstalk Of Overhead Multi-conductor Transmission Line

In systems requiring long-distance overhead power lines,such as power systems,railway systems,or communication systems,surges and electromagnetic pulse caused by lightning and nuclear explosions,complex electromagnetic environments,or switching operations.The resulting crosstalk has always been a key issue affecting the safe and stable operation of power systems.It is difficult to measure the crosstalk of overhead lines,but obtaining the value of crosstalk is extremely critical to suppress the crosstalk between overhead lines.In order to ensure the safe operation of the power system,it is very essential to simulate and predict the electromagnetic crosstalk of overhead lines.In this context,based on the theory of multi-conductor transmission lines,this paper deeply studies the internal impedance,external impedance and ground impedance parameters of the wire caused by lossy ground,and establishes a transmission line model of overhead lines under the action of electromagnetic transient pulses.For long-distance overhead lines,an efficient alternating direction implicit finite-difference time-domain method is used to calculate the transmission line model established in this paper.The main research contents are as follows:1.In view of the overhead multi-conductor transmission line structure,based on the theoretical analysis of the multi-conductor transmission line,combined with the penetration depth of the lossy ground and the ground impedance of the wire.In this paper,a new unit length parameter model of overhead multi-conductor transmission line is established,and the equation of overhead multi-conductor transmission line on a lossy ground is derived.2.The finite-difference time-domain method is used to discretize the overhead multi-conductor transmission line equations,and the iterative equation of voltage and current at any position is derived.Combined with the boundary conditions of electromagnetic transient pulse coupling the excitation source and resistive load,the crosstalk of overhead multi-conductor transmission line on ideal conductive plane and lossy ground plane is analyzed in time-domain.Explore the coupling law of electromagnetic pulse to crosstalk of overhead multi-conductor transmission line.3.The finite-difference time-domain meshing process is limited by the stability of Courant Friedrichs Lewy condition,which leads to the problem of too many meshes in the process of long-distance overhead line dispersion and low computational efficiency.For this problem,alternating direction implicit finite-difference time-domain is used to calculate the crosstalk of overhead multi-conductor transmission lines and analyze the effect of electromagnetic transient pulse excitation of long-distance overhead wire harness.4.In view of uneven current distribution caused by the skin effect in the overhead line,and the uneven distribution of the overhead line due to the stress of the wire harness and the sag caused by gravity.This article carries out detailed theoretical derivation and analysis of this problem.Substituting the recalculated distribution parameters into the overhead multi-conductor transmission line equation to compare the effects of internal impedance loss and sag on the crosstalk.This article uses alternating direction implicit finite-difference time-domain to simulate the voltage propagation process of the step signal and Gaussian signal in the two-conductor transmission line model,and compares with the finite-difference time-domain simulation results to verify the accuracy of the alternating direction implicit finite-difference time-domain method.For the computational of electromagnetic transient pulse crosstalk on long-distance overhead multi-conductor transmission lines,the alternating direction implicit finite-difference time-domain method reduces the computing memory and has higher computational efficiency.The obtained crosstalk simulation results have guide significance for guiding the wiring of overhead lines and eliminating crosstalk.