A general code to simulate the effect of indirect lightning on overhead lines using EMTP-type programs

In this work, a general code is obtained to facilitate the simulation of the electromagnetic transient response of a transmission line excited by a nearby lightning stroke using EMTP-type programs, namely ATP (Alternative Transients Program) and PSCAD (Power Systems Computer Aided Design). Initially, a frequency domain model of a field-excited (illuminated) line is implemented using Taylor's formulation. Based on this model and on the application of the numerical inversion of the Laplace transform, a general code is developed in MATLAB to obtain terminal current sources representing incident field excitation, which are used as external sources for ATP and PSCAD. This code makes the computation of the effect of indirect lightning easier for the user, since a deep knowledge of the modeling approach behind this computation is not required. Several application examples are included to demonstrate the accuracy and versatility of the code.

I. Intraduction

An electromagnetic transient occurs when there is a sudden change of electromagnetic energy in a power system, which can be caused by lightning or switching phenomena [1]. A lightning stroke can impact a transmission line in a direct or indirect manner. Direct lightning corresponds to stroke impact to the towers, conductors and components of transmission systems. In a well-designed transmission system, the ground conductors are generally the ones hit by direct lightning strokes, although a small percentage of strokes can still hit the phase conductors. On the other hand, indirect lightning corresponds to lightning strokes to ground in the proximity of the transmission line. Although direct lightning strokes produce higher transient overvoltages than indirect ones, the effect of incident electromagnetic fields from nearby lightning strokes is also important for the design of protection and insulation elements. In addition, indirect lightning is a much more frequent phenomenon than direct lightning [2].