| At present, the power demand in our country is increasing rapidly, and the power system is developing in the direction of high voltage, large capacity and long distance.With more and more attention has been paid to the electromagnetic environment problems, accurate calculation of the transmission line generated by the electromag-netic field and assess its impact on the environment is excessive has become an important issue to be solved. In this paper, 220kV power transmission line is taken as the object of study, and the power frequency electric field generated around it is simulated and analyzed.For the power frequency electric field of transmission lines, the surface of the earth is usually assumed to be plane, and the method is simulated by the charge simulation method combined with the mirror image method. This can be applied to plain or open flat terrain, but for mountainous, hilly and other uneven terrain, it is necessary to set the simulated charge under the ground according to the terrain, so it is impossible to use the mirror image method. The artificial determination of the simulated charge positions is limited by the complexity of the problem and the design experience. To solve this problem, two methods are used in this study: the simulated charge method and the finite difference method.High voltage transmission line is high voltage multi loop system, the distribution of electric field strength around the situation is more complex, this paper introduces the charge simulation method, establishes a mathematical model of two-dimensional electric field of high voltage transmission line, the simulation program is compiled.Through simulation and analysis, the basic law of electric field of high voltage transmission line is obtained.In order to simulate the complicated problems further, the influence of topography and other factors on the electric field distribution of high voltage line is considered. By using the finite difference method to achieve the simulation of high-voltage electric field distribution of real terrain, and adding boundary conditions for the establishment of a medium ground and forest vegetation model, this paper fully embodies the influence of topography and vegetation in the three-dimensional space for the space electric field.The main work is as follows:1. according to the existing program of simulation charge method, the near-field electric field distribution characteristics of 220kV high voltage line under different conditions are calculated and studied.2. based on the existing two-dimensional finite difference equation and five point difference scheme on the understanding, formulas of three-dimensional non equidistant finite difference formula, puts forward 7 points three dimensional Laplasse equation format and introducing complex voltage based on the application of the finite difference method in three-dimensional space.3. the method of stepped approximation of terrain model is put forward, and combined with DEM data, the simulation of three-dimensional electric field of high voltage line under real terrain is realized. The reliability of the method is verified by the measured results.4. according to the boundary condition of the electric field to achieve a simulation of conductive media presence in space electric field, a medium ground and vegetation model, analyzed the spatial distribution of the electric field under the condition of existing vegetation near power lines and calculation.Through the typical example simulation, the distribution law of the frequency distribution of the wire, the height of the wire, the radius of the sub-conductor, the number of splitting, the splitting distance, the uneven terrain, the medium ground and the vegetation are analyzed; This paper discusses the measures to reduce the distribution of the electric field and obtains some useful conclusions, which can help the evaluation of the electromagnetic environment of the high voltage line and the optimization design of the high voltage line corridor. |
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