绞线花纹导线表面电场强度计算与分析

为了准确计算输电绞线花纹多股绞线表面电场强度的大小,建立了二维电场模型,采用有限元法与镜像法相结合的方法计算带有花纹的输电线表面场强,并与光滑导线模型的场强进行比较,还分析了绞线花纹对导线表面最大场强的影响。考虑输电线表面花纹后计算出的表面最大场强与将导线视为光滑圆柱体的计算结果相差>20%。在导线选型时,应充分考虑绞线花纹对导线表面最大场强的影响。

Computation and Analysis of the Electric Field Intensity on Conductor Surface for the Bunch Wire of Transmission Lines

Corona performance is an important consideration in the design and operation of high voltage transmission lines. The most important factor influencing the occurrence and characteristics of corona discharge on transmission line conductors is the electric field intensity in the region surrounding the conductor surface. The electric field intensity is determined by not only the voltages applied to the various conductors but also the surface shape of the conductors. The conductors of transmission lines are made of twisted wires, which lead to patterns on the surface of conductor. The patterns enhance the maximal electric field intensity on the conductor surface. Two dimensions electric field model is set up for the determination of conductor surface electric fields of multi-conductor transmission lines. The appropriate electromagnetic model for this purpose is the quasi-static model. The traditional method of images for computing the electric field intensity does not consider the patterns. The combined approach of the finite element method (FEM) and the method of images has been applied to develop a more accurate method to obtain the electric field intensity on the conductor surface of transmission lines, particularly for considering the patterns. The different methods of calculation available for high-voltage AC transmission line configurations are described in this paper. The effect of the patterns influencing the maximum values of the electric field intensity is analyzed by comparing the field considering the patterns with and without considering the patterns. The former is over 20% greater than the latter. It should be adequately considered that the patterns will contribute to the maximum values of electric field intensity when twisted wires are selected in transmission lines.