| Due to the rapid growth of the national electricity demand, the grid is toward high-capacity, high-current, high-voltage, long-distance power transmission direction. The number of multiple transmission lines in the same corridor and cross transmission lines is increasing.Transmission lines and substation facilities are also more and more close to or in the population. Electromagnetic environment produced by transmission lines and distribution equipment is more and more difficult to control and has attracted widespread attention.It also becomes the important factor of defining the structure of the transmission line and the construction cost. So it is very necessary to make numerical analysis on electromagnetic environment produced by the transmission lines.Based on the two-dimensional direct boundary element method and three-dimensional indirect boundary element method, the electric field distribution between 2 d model and 3 d model are compared. The space electric field distribution of cross transmission lines and the changing rule of the space electric field with the change of phase sequence and cross angle are analyzed. This paper deduce the power frequency magnetic field calculation formula of 2 d model and 3 d model, comparing the magnetic field distribution between 2 d model and 3 d model. The space magnetic field distribution of cross transmission lines and the changing rule of the space magnetic field with the change of phase sequence and cross angle are analyzed too.According to the characteristics of the transmission conductor surface subdivision unit, the gauss integral precision is improved. Aims at the larger length-width ratio of unit, the number of gaussian points is increased in long direction. On the premise of high calculation precision,it can reduce unit subdivision number,and overall improve the calculation efficiencyBuilding three-dimensional model of tower, the line-plane mix boundary element method and the analytical solution are used to calculate the conductor surface electric field intensity near the tower effectively. The transmission tower’s influence on the conductor surface electric field and space field is analyzed.On the basis of the improved boundary element method, a software for electromagnetic environment calculation of high voltage transmission line is developed. The software containing the boundary element method suitable for open field calculation,can calculate the transmission line conductor surface electric field, audible noise, radio interference, power frequency electric field and magnetic field conveniently and efficiently. Microsoft Visual C++is the current mainstream development software. It contains the MFC foundation class library,and encapsulates the most of the windows API functions, Having the advantages of friendly interface, peform faster and higher efficiency,etc. C++ supports object-oriented programming at the same time,and has the characteristics of good repeatability, scalability and maintainability, etc. |
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