Simulation Research On Induced Voltages And Magnetic Fields Distribution In Buildings Hit Directly By Lighting

Lightning is a frequent electromagnetic phenomenon in the nature which can cause personal injury and power outages,equipment troubles and other safety accidents in the buildings.With the rapid development of national economy in our country,the lightning protection technology has been developing rapidly as an indispensable part in the construction of buildings.The lightning will produce a greater threat to safe operation of the transmission lines in the buildings,but the research on the distribution regularities of electromagnetic field in the vicinity of the lightning channel just started and lack of systemic understanding.As to fully understand transient electromagnetic phenomena due to direct lightning strikes,a reduced scale model of five-story building is built in this thesis,the electromagnetic effects,the condition of current distribution,induction voltage and magnetic field distribution system of building due to direct lightning strikes are systematically analyzed.1.The modeling method of the lightning protection system of building based on the approach of a finite difference time domain(FDTD)is used.The transient surge current distribution in LPS is simulated.The validation of the proposed approach is performed by comparing the results with experimental results and the results of different calculation methods.2.After getting the surge current distribution in the building lightning protection system,the transient magnetic field distribution inside the building is calculated by means of FDTD.On the premise of calculation accuracy,the methods avoid the mash complexity and time consuming problems that exist in others,and which are suitable for magnetic field calculation in true size building.3.According to FDTD calculation,induced voltage on branch wire of each floor in the building is simulated.The improved waveform of induced voltage in building is got by the installation of surge protection device(SPD).It proves that the influence of building equipments resulted by induced voltage will significantly decrease after installing SPD by comparing the induced voltage on branch wire of each floor in the building.