The Research On The Coupling Effect Of High Altitude Nuclear Electromagneti Pulse On Transmission Lines

The protection of power grid system against the HEMP has become a hot topic in current electromagnetic compatibility research.In this paper,the transmission lines in the power grid system are taken as the subject.Based on the basic transmission line theory,different circuit models and the theories of electromagnetic topologies,the transmission line equations applicable to different conditions are derived and the codes are compiled for the simulation calculation of the transmission lines,transmission line networks and common transmission line structures' coupling rsponse under HEMP's environment.Finally,a simple experimental platform of high-intensity electromagnetic pulse(EMP)radiates double-line transmission line and pylon-transmission line structure is preliminarily established,and the experimental results are compared with the software simulation results.Detailed work is carried out as follows:Firstly,this paper simply introduces the related theories of HEMP and the basic transmission line equation is derived.Based on the transmission line theory and equivalent models of different circuits,the transmission line equations suitable for three different types of single transmission lines(overhead transmission lines,buried transmission lines and transmission lines connected transformer)are derived.Moreover,the coupling response of cables under HEMP's evvironment with different parameters is simulated.And some new problems such as the difference of inductance between buried cable and overhead cable,are analyzed quantitatively.So some general conclusions and rules are obtained which can be used as reference for the protection and reinforcement of power grid system.Secondly,the coupling response of multi-line transmission lines above the lossy ground plane was analyzed,and the multi-conductor BLT hypermatrix equation was deduced.The lossy ground distribution parameters were extracted,and the equation was solved with the method of combination of chain parameter matrix and modulus decoupling.The response conditions of cables under different conditions were simulated.This method is applied to the calculation and comparison of HMEP coupling between split conductor structure and single conductor structure from a relatively new point of view,which highlights the advantage of split conductor structure cable shielding HEMP coupling effect.In the same way,the BLT hypermatrix equation of the buried multi-wire transmission line coupled HEMP is deduced.Then the BLT hypermatrix of the transmission line network and the parameter matrix is deduced by combining the theory of electromagnetic topology,and simulation calculation for the common transmission line network is carried out as a reference for the electromagnetic compatibility construction of power grid.Finally,a simple experimental platform of high-intensity electromagnetic pulse(EMP)radiates double-line transmission line and pylon-transmission line structure is preliminarily established,and the induced voltage of lines' s experimental results are compared with the software simulation results.The comparison results verify the preliminary feasibility of the platform,point out the direction of the experimental platform' improvement,and provide a reference for the EMP protection of power grid.