Contents Introduction
As well known, the steep-fronted current impulses injected by lightning strokes in OHL tower peaks or shield wires can cause backflashover of line insulation. In order to prevent back-flashes, complex grounding arrangements (i.e. involute geometries) and/or large spatial extension (i.e. counterpoises) are commonly used for OHL towers built on medium-to-high resistivity soils. The aim is the reduction of the tower grounding impedance, mainly due to relaying performance concerns and lightning withstand. The numerical simulation of such spatially extended grounding systems may be advantageously carried out by means of circuit models [1]–[4], able to provide accurate results even for complex scenarios [5]–[11]; however, the main drawback of such models, especially when complex power systems must be simulated and non-linear soil ionization phenomena must be taken into account [12]–[16], is the large request of computational resources in terms of occupation memory and execution time.
