Electric Fields Induced by EHV Transmission Over Irregular Terrain

A method for calculating electric fields induced by transmission lines over irregular terrain using a simulated surface charge distribution is outlined. The method approximates the two- dimensional physical charge distribution induced by the lines with a set of discrete line charges. Solution to the quasi-static electric field profiles is sought by constraining the discrete charge distribution such that the field is perpendicular to the surface at a finite set of points. The accuracy of the method depends on the number of charges used and the location of the charges. The analytical flat earth solution is used to establish accuracy as a function of charge configuration. Finally, the method is used to predict fields for irregular terrain. The predicted fields show good agreement with measured data in several examples where there was significant departure from the field predicted by a flat earth solution.