Behaviour of grounding systems excited by high impulse currents:the model and its validation

摘要

The behaviour of grounding systems excited by high impulsencurrents (such as lightning strokes or phase to ground faults)nconsiderably differs from that at low-frequency and at low-current:ninductive behaviour can become more and more important with respect tonresistive behaviour and, in addition, these currents can generate soilnbreakdown (which makes the impulse response typically nonlinear). Manynexperimental tests confirm these aspects. In order to obtain a correctndesign of electrical systems, with respect to the protection ofninstallations against anomalous events, it is fundamental to predict thenimpulse characteristics of grounding systems. An efficient solution tonthis problem may be obtained by a mathematical model based on a circuitnapproach. The development of this model (which is able to simulatencomplex grounding systems when nonlinear ionization phenomena takenplace) is described in this paper. The model has been validated byncomparing the numerical results both with experimental tests and withnthe simulations executed by various approaches