A Thévenin-Type Version of the Extended Modal-Domain Model for Lightning-Induced Voltage Calculations

Abstract

In this paper, a new procedure is proposed for determining the external current sources required for evaluating lightning-induced voltages on overhead lines with the extended-modal domain (EMD) model. Unlike the original model, in which the calculation of the inducing current sources depends on the fitting of the characteristic admittance of the line, in the proposed procedure this calculation is performed using the characteristic impedance of the line. This significantly simplifies the use of the EMD model because now all parameters can be readily obtained from the built-in fitting tool that is usually available in electromagnetic transient programs to derive the parameters of Marti’s transmission line model. The validity of the proposed procedure is demonstrated through examples that indicate its accuracy in the calculation of lightning-induced voltages on overhead distribution lines terminated with different types of loads, including transformers and surge arresters, and multiple grounding points.