Lightning Electromagnetic Field Coupling to Overhead Lines: Theory, Numerical Simulations and Experimental Validation

The evaluation of electromagnetic transients in overhead power lines due to nearby lightning return strokes requires accurate models for the calculation of both the incident lightning electromagnetic pulse ( LEMP) and the effects of coupling of this field to the line conductors. Considering also the complexity of distribution networks in terms of their topology and the presence of power system components and protection devices, the implementation of the LEMP-to-transmission-line coupling models into software tools used to represent the transient behavior of the entire network is of crucial importance. This paper reviews the most significant results obtained by the authors concerning the calculation of lightning-induced voltages. First, the theoretical basis of advanced models for the calculation of LEMP-originated transients in overhead power lines is illustrated; then, the relevant experimental validation using: 1) reduced-scale setups with LEMP and nuclear electromagnetic pulse ( NEMP) simulators and 2) full-scale setups illuminated by artificially initiated lightning are reported. Finally, the paper presents comparisons between simulations and new experimental data consisting of measured natural lightning-induced voltages on a real distribution network in northern Italy, correlated with data from lightning location systems.