A free tool in Laplace domain for assessing the extra high voltage cable energization

The purpose of this paper is to present a free tool easily implementable in commercial mathematical software (e.g. Matlab) which allows computing the switching overvoltages due to the cable (in single or double circuit) energization. Also the use of shunt reactive compensation can be accounted for. In order to achieve this goal, the authors have made an extensive use of Lapalce domain. The paper shows both a numerical inverse Laplace transform and a novel method which does not need a numerical inverse transform. In fact, by representing the transmission line as a cascade of n cells constituted of lumped L-C ladder, it is straightforward to make the inverse Laplace transform of rational functions as polynomials.