Electric field computation and optimization of composite tower in 330 kV double circuit transmission lines

Tower is an important kind of power device, it has been widely used in transmission lines of different voltage ratings. Composite tower has advantage in saving line corridors, reducing tower weight, easy installation and transportation when compared with all-steel towers. It has got a growing attention from researchers. Owing to its complex structure, satisfactory operation of composite tower is intimately related to the potential and surface electric field distribution. With a three-dimension (3-D) finite-element method (FEM) software ANSYS, this paper presents computation results of the potential and electric field distribution for composite tower in 330 kV double circuit transmission line. The influence of tower, conductors, grading rings and ground has been analyzed. The voltage undertaken by cross-arms and tower body has been calculated in different situations. A set of grading rings configuration program has been proposed to control the electric field strength of the position that need to be concerned. After optimization, the electric fields strength of the key location of composite tower has been proved that they could meet the critical values.