Transmission tower representation directly in the time domain

This work presents a proposal for modeling conventional and giant transmission towers directly in the time domain whose admittances of these structures are represented by lumped circuit elements. From this representation, one can calculate voltages caused by lightning striking at the top of each transmission tower. In this proposal, voltages produced in each transmission tower are obtained directly in the time domain using electromagnetic analysis programs, which does not require inverse Laplace or Fourier transformations. This modeling initially consists of calculating the admittance of any transmission tower in the frequency domain using the Moment Method (MoM), taking into account the tower geometry, soil resistivities and tower-footing grounding impedance. Once the admittances of the conventional and giant transmission towers are obtained, these curves are represented by rational functions obtained by the Vector Fitting technique and then an equivalent lumped electric circuit is proposed for each curve calculated numerically. These circuits will be analyzed in electromagnetic transient software and the voltages due lightning strikes in each tower are estimated. In this proposal, the inclusion of the tower trusses, homogenous soils and grounding electrodes are considered, and the responses are more precisely obtained. A comparison between the voltages obtained by the proposed modeling and the conventional models is also presented. In these comparisons, it can be seen that conventional models for representing transmission towers have limitations, in which the proposed modeling is more satisfactory performed. (AU)