| Since the center of energy source is far away from the center of the load in China, it has been a necessity to develop the large-capacity and long-distance transmission lines. However, it is increasingly difficult to erect new power transmission corridors in some developed areas as the land resources are very limited. So a growing number of HVDC transmission lines are erected with HVAC transmission lines in the same corridor as a constructive solution. Now the new problems of electromagnetic environment brought about, especially the hybrid electric field, are drawing more and more attention. The impacts of different factors on the characteristics of hybrid electric field are researched in this paper, and the characteristics of hybrid electric field are analyzed in detail based on the hybrid finite element finite volume method.Firstly, the hybrid finite element finite volume method and the direct superposition method are introduced. Then the calculation results of the hybrid finite element finite volume method are mainly compared with the calculation results which are the superposition electric field of ac electric field and dc electric field. By comparing with the measured results, the hybrid electric field need to be calculated by hybrid finite element finite volume method when the characteristics of the hybrid electric field are analyzed.Secondly, the hybrid electric field is measured on the platform of the corona, and then calculated through the hybrid finite element finite volume method. The measured data are compared with the calculation results to study the characteristics of the hybrid electric field. Then the impacts of the adjacent distance, the height and the voltage of conductors on the electric field distribution are concluded. And the validity of the hybrid finite element finite volume method is also verified.Finally, the hybrid finite element finite volume method employed, the electric field of an actual project is predicted with the calculation results. Such a situation is taken as an example, a single ±800kV UHVDC transmission line is paralleled with a single 1000kV UHVAC transmission line in the same corridor. The intensity of the electric field on the ground under the parallel lines is calculated. By the comparison of the calculation results, the influence of the adjacent distance and the height of the HVAC/HVDC transmission lines on the distribution of the electric field on ground is obtained, which can a meaningful reference for the design and operation of transmission line projects. |
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