Modeling and simulation for determining the characteristic impedance of transmission and distribution line structures

The characteristic impedance of structures is an important parameter used in the development of overvoltage protection studies and in the insulation coordination in electrical systems. The transmission line towers shapes and the poles shapes make it difficult to calculate the characteristic impedance analytically, or even measuring in laboratory. Thus, this paper presents a methodology to calculate the characteristic impedance of concrete poles in distribution networks and transmission line towers. A model was developed in Q3D Extractor software to run these simulations. A comparison between simulations and an analytical method is made, considering two types of structures, a distribution pole, and a transmission tower. The results show divergences between the calculated values by the various analytical methods and those obtained in this work. At the end, it is concluded that the determination of the characteristic impedance using the proposed methodology is more accurate due to the degree of structure details considered.