Equivalent lumped parameter pi-network of typical grounding systems for linear and non-linear transient analysis

In this paper, the authors propose and validate a simple lumped parameter model based on a pi-type network. This model is able to simulate the ground potential rise of typical tower grounding systems under surge conditions. The lumped parameter values are estimated by means of an optimization procedure based the micro-genetic algorithm (muGA). This procedure minimizes the standard deviation between target values (obtained using a full circuit model able to perform frequency domain analyses and time domain analysis under linear and non-linear conditions) and simulation results (obtained using the equivalent pi-network model). The proposed model has been validated by means of massive simulations of typical Italian 380 HV transmission line grounding systems under surge conditions (varying impulsive current wave shapes, grounding system geometrical configurations, soil characteristics and also accounting for non-linear ionization phenomena). The simulation results have always revealed a very good agreement between target values and model results. In addition, the proposed pi-network model drastically reduces the computational resources required for linear and non-linear transient analyses of typical tower grounding systems.