Modeling And Analysis Of Transient Electromagnetic Effect In Lightning Strikes On Buildings

In view of the electromagnetic effect and overvoltage interference caused by lightning strikes on buildings,this thesis uses a fast calculation method and efficient operation program to design a calculation of electromagnetic phenomena and induced electromotive force in the lightning protection network framework of buildings.The strategy of mold analysis provides a new idea for building lightning protection design and construction.This topic firstly simulates two complete and reasonable lightning protection network framework models based on the actual lightning protection system design of buildings.According to the transmission network equation,the whole framework is equivalent to an electrical network,using the relevant formula of capacitance resistance inductance in international standards.Calculate the parameters of the node admittance matrix on the network.Then according to the lightning current parameters defined in the lightning protection specification,the appropriate impulse current expression is selected to simulate the lightning current waveform on the lightning protection network frame,and the lightning impulse current is solved in the frequency domain,and the node admittance matrix is used to calculate The frequency domain voltage value of each network node,and then the voltage value is converted into the time domain form,and the time domain current on each branch conductor is calculated by using the equivalent power line model,so that the current voltage distribution on the lightning protection network frame is obtained.characteristic.Secondly,according to the current distribution characteristics,the semi-analytical method combining the difference method and the analytical method is used to calculate and simulate the electromagnetic field size and spatial distribution inside the lightning protection network,and the magnetic field simulation is performed on the whole network frame and any plane,and electromagnetic induction is utilized.The law and the micro-element method simulate the magnitude of the induced electromotive force in any loop within the network in the time domain and the spatial domain.A fast vector plane projection method is used in the programming to speed up the efficiency of the program operation.In order to verify the accuracy and reliability of the method,the same problem was calculated by the method in the thesis and the method of international lightning protection standard "IEC62305-4".The results show that the method is in accordance with the IEC standard in terms of accuracy and efficiency.Faster.Finally,by quantitatively exploring the impact current waveform parameters,lightning protection network frame conductor material,lightning protection structure conductor diameter,grounding resistance and lightning rod mounting point on the lightning protection network electromagnetic effect and the magnitude of the induced electromotive force,the lightning strike point and the inrush current are obtained.The induced magnetic field and induced electromotive force are the strongest near the main venting channel,and the attenuation inside the network is serious.The induced voltage around the conductor of the lightning protection structure is strong,and there is a negative voltage.The interference problem of the subsequent lightning strike cannot be ignored.The placement of sensitive equipment Keep away from important conclusions such as interference zones.This topic provides a new idea for the optimal design of building lightning protection network framework with a faster calculation method and a more concise and effective operation program,and provides new suggestions for lightning protection construction of buildings.