A BEM approach for grounding grid computation

Abstract

[Abstract] Grounding systems are designed to preserve human safety and grant the integrity of equipments under fault conditions. To achieve these goals, the equivalent electrical resistance of the system must be low enough to ensure that fault currents dissipate (mainly) through the grounding electrode into the earth, while maximum potential gradients between close points on the earth surface must be kept under certain tolerances (step and touch voltages) [1,2]. In this paper, we present a Boundary Element approach for the numerical computation of grounding systems. In this general framework, former intuitive widespread techniques (such as the Average Potential Method) are identified as the result of specific choices for the test and trial functions, while the unexpected anomalous asymptotic behaviour of these kind of methods [3] is mathematically explained as the result of suitable assumptions introduced in the BEM formulation to reduce computational cost. On the other hand, the use of high order elements allow to increase accuracy, while computing time is drastically reduced by means of new analytical integration techniques. Finally, an application example to a real problem is presented.