Grounding grids in electro-magnetic transient simulations with frequency-dependent equivalent circuit

The frequency behaviour of a grounding grid cannot be neglected in insulation coordination studies. This paper proposes a new approach, which consists of calculating the frequency behaviour of a grounding grid by means of a software which implements the electromagnetic theory, building a two-port component, whose internal admittances are defined as rational functions in the Laplace domain, and finally using this two-port component for time-domain fast transient simulations.