Research On Prediction And Calculation Of Electromagnetic Environment Of UHVDC Transmission Lines

Ultra High Voltage Direct Current(UHVDC) transmission lines have unique advantages, which plays an increasingly important role in construction strategy of UHV power grid. However, the electromagnetic environment of it has become an important factor restricting its development. The parameters to assess the electromagnetic environment of UHVDC are : the synthetic electric field, the ion current density,the radio interference and the audible noise.In the calculation of the electromagnetic environment of unipolar transmission lines,the paper calculated the synthetic electric field and the ion current density.The calculation of the synthetic electric field is closely related to the conductor surface electric field and the nominal electric field. So we first need to calculate the conductor surface electric field and the nominal electric field. This article adopting charge simulation method firstiy proposed the judgment basis of conductor surface maximum electric field relative error. On this basis, the position and number of simulation charges of traditional charge simulation method were optimized the analysis. This paper adopting the optimized charge simulation method detailed analyzed the structural parameters of the unnipolar line including the number of split conductors, sub-conductor split spacing, sub-conductor cross-section and conductor-to-ground height affecting on the surface electric field and the nominal electric field, and by reasonable changing conductor structure parameters can effectively reduce both electric field.In the areas of the synthetic field and ion current density of unipolar line,this paper adopting the analytical method detailed analyzed the influence of structural parameters including the sub-conductor split spacing,sub-conductor cross-section and conductor-to-ground height, and gave a valid conclusion to guide engineering practice.In the calculation of the electromagnetic environment of bipolar transmission lines,the paper calculated the synthetic electric field,the ion current density,the radio interference and the audible noise.Firstly,the surface electric field and the nominal electric field of bipolar line were studied and analyzed by using the optimized charge simulation method. In the areas of the synthetic field and ion current density of bipolar line,this paper adopting the analytical method detailed analyzed the influence of structural parameters including the sub-conductor split spacing, sub-conductorcross-section, conductor-to-ground height and the pole conductor spacing, and presented a reasonable reference for the transmission lines to select and erect.In the areas of radio interference and audible noise,this paper adopt recommended formula from EPRI to calculate and simulation, described attenuation characteristics, and proposed measures to reduce both numerical size.In order to verify the correctness and rationality of prediction methods, this paper compared predictions and measured datas of ±800k V Hami-Zhengzhou transmission project, and reasonably analyzed error between them. Based on the above study,this paper adopt hybrid programming mode by combining Visual Studio and MATLAB to compile prediction software of electromagnetic environment of UHVDC transmission lines, so that the electromagnetic environment of UHVDC transmission lines could be intuitively forecast and analyzed.This paper provided a powerful software and theoretical support for EIA work in future.