Study On The Impacts And Shielding Method Of Electromagnetic Environment In Building Caused By Extra High Voltage Transmission Lines

In recent years, as urban power load quickly increasing and urban areas continuously expanding, the size of power grid, transmission voltage grading and distribution pattern have changed greatly. More high-voltage substations and power distribution networks are built in high density city, the extra high voltage(EHV) transmission lines which originally appeared in the suburbs now appear in city, and these cause the electromagnetic environment very complex in buildings. The radiation impacts on urban life and environment become more apparent. Another, people have higher requirements on the quality of the environment, so the electromagnetic environment around high-voltage power transmission also becomes the issue at home and abroad. The frequency electromagnetic field caused by EHV transmission lines and their impacts on the electromagnetic environment of building are studied, and shielding methods of frequency magnetic field are analyzed.Charge simulation method is adapted to calculate the frequency electric field of EHV transmission lines, the distribution rules and impacts on environment are also analyzed. Electric field distribution is calculated when high-rise building is on one side of transmission lines. Simulation current method is used when calculating frequency magnetic field, the distribution rules and impacts on environment are also analyzed.Simulation model is built after validating the feasibility of Maxwell 3D software in simulating electromagnetic problems of transmission lines. Electric field distribution in building when the EHV lines are nearby is analyzed and the impacts of building materials on distribution of the electric field are also studied. Position and size of window are considered. The magnetic distribution is also simulated under three-dimensional eddy current field of Maxwell 3D software.The shielding methods of frequency magnetic field is discussed mainly because of buildings have good shielding function to electric field. Here, magnetic analysis method is used to approximately calculate the shielding effectiveness of complete metal shield (rectangular section); Simulation model is built in Maxwell 3D software to study the shielding effectiveness when shielding plate and reinforcing wire mesh are placed on the roof of building. The transmission coefficient and shielding effectiveness are calculated after simulating. The impacts of material, thickness, grid size and diameter of reinforcing steel bar on shielding effect are also researched, and some useful conclusions are received.A simulation software that can calculate the electric field caused by transmission lines is developed. Running the software can get the contour map and bitmaps of the electric filed.