Lightning-induced voltage analysis on a three-phase compact distribution line considering different line models

Abstract

This paper discusses the simulation of lightning-induced voltages on a three-phase compact distribution line considering either a first order finite-difference time-domain solution of telegrapher's equations or a version of Marti's transmission line model extended to include the influence of external electromagnetic fields, named EMD model. The validity of both models is first demonstrated by means of comparisons with lightning-induced voltages measured in rocket-triggered lightning experiments. It is then shown that the EMD model can be used in the simulation of lightning-induced voltages on compact distribution lines provided special attention is given to the model fitting in the modal domain, regardless if complex or real poles are used. Results obtained with the vector fitting technique are seen to be more reliable than those obtained using Bode's asymptotic method, which must be used with caution in the modeling of compact distribution lines. The obtained results are relevant because compact distribution lines contain both bare and covered conductors, which is likely to pose difficulties to the simulation of transients with transmission line models based on modal-domain theory.