| The electronic power system is an important national infrastructure,cables are used as the medium for transmitting information and energy in the system.Most of transmission cables are exposed to the external natural environment,and they are extremely susceptible to strong electromagnetic pulse interference to generate strong transient induced currents,and cause equipment damage through coupling into the electronic power system.Therefore,studying the coupling effect of strong electromagnetic pulse environment and various transmission cables is of great significance to the electromagnetic protection of current electronic power systems.For cables in lossy half space under strong electromagnetic pulse environment,a method combining the reflection coefficient method and the time domain integral equation(TDIE)method to solve the coupling effect of the strong electromagnetic pulse and various transmission cables is proposed Time domain method.First,the reflection coefficient method is used to obtain the time domain response of the lossy ground reflected wave reaching the cable,and then this part of the reflected wave is used as a part of the incident wave excitation source,added to the solution of the TDIE method to establish the integral equation of the electric field in the time domain of the single overhead line.Then,the integral equations of the multi-cable,the cable above the layered ground and the buried cable under different media conditions are expanded,and the time domain method of moments(TD-MOM)iS used to quickly solve.The last,this thesis uses the hybrid algorithm accurately models the overhead line antenna and calculates the transient response of the line antenna after being excited by a time-varying voltage source.On this basis,the induced current changes of overhead cables under different cable lengths,erection heights and polarization states of incident waves are analyzed,and the factors affecting the transient current at the midpoint of the thin wire antenna are discussed.Considering that the length of the actual power transmission line is very long and can be regarded as a periodic structure to a certain extent,the TDIE method based on the infinite-periodic structure theory is used to establish a coupling model of strong electromagnetic pulses to the actual ultra-long thin wire conductor,which solves the problem of using TDIE method or finite-difference time domain(FDTD)method is used to simulate the cable structure above the ground,the length of the cable that can be simulated is often limited due to the limited computing resources.The simulation results show that the reflection coefficient method and the TDIE method are combined to solve the coupling response of various transmission cables in the strong electromagnetic pulse environment.Compared with the traditional time domain reflection coefficient method and the full wave method,the calculation results of the hybrid time domain algorithm in this thesis are accurate and higher efficiency.For the calculation of the transient current of ultra-long cables,compared with the TDIE method,the TDIE numerical method based on the infinite-periodic structure theory is more efficient,the complexity is reduced by half,and the calculation memory consumption is lower.The research results are of great significance for improving the anti-interference of electronic power systems. |
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