Perturbation finite element method for the analysis of earthing systems with vertical rods

This paper deals with the electrokinetic modeling of earthing systems by means of a sub-domain perturbation finite element technique. An axisymmetric problem is solved for each single grounding rod. Its solution must then be corrected by taking into account the influence of the other rods. The electric scalar potential is transferred from one problem to the other through projections between meshes. An inherently 3D problem can thus be solved as a succession of 2D sub-problems, what significantly speeds up the solution and enables to tackle complicated grounding systems. The method is validated by means of both analytical formulas and 3D computations.