Numerical modelling of grounding systems in high-performance parallel computers

The design of safe grounding systems in electrical installations is essential to assure the security of the persons, the protection of the equipment and the continuity of the power supply [1,2]. In order to achieve these goals, it is necessary to compute the equivalent electrical resistance of the system and the potential distribution on the earth surface when a fault condition occurs. While only crude approximations were available before the 60's, some intuitive methods [1] have been proposed in the 70's and the 80's. These non-rigorously established methods are widely used to compute small and medium size installations, in spite of the problems that have been reported [3]. On the other hand, the authors have developed a BEM numerical formulation that has proved to produce highly accurate results in the earthing analysis of large real grounding systems with uniform [4,5] and stratified soil models [6]. At present, single-layer models run in real-time in personal computers, while multiple-layer models break off the design process (since the computing time is not contemptible). In this paper, we present our BEM formulation for the analysis of grounding systems embedded in stratified soils, and we discuss the key points of its implementation in a high-performance parallel computer (HPPC). The feasibility of this approach is demonstrated by its application to the analysis of a real grounding system with a two-layer soil model. As we expected, the speed-up of the algorithm increases when the number of processors does, in accordance with the theoretical predictions. Therefore, the proposed multi-layer BEM formulation could become a real-time design tool in a close future, when high-performance parallel computing becomes a widespread resource in engineering design.