NUMERICAL EVALUATION OF SELF AND MUTUAL EARTH RETURN IMPEDANCES

The paper presents an evaluation of analytical self and mutual impedances formulas of lines with earth return, taking into account the ground correction terms. The determined formulas contain semi-infinite integral terms which are calculated by a novel stable and efficient numerical integration scheme in order to overcome the involved oscillation problems. It might seek approximations of the semi-infinite integrals by replacing an exponential or algebraic function, the objective being to permit analytic integration. Since there is no good systematic method for making these replacements, their success depends directly on the intuition and ingenuity, taking into account that in practice the integrand has limited accuracy