Modeling of surge currents in lightning protection system using ATP-EMTP

The paper presents computer simulations of current distribution in lightning protection system (LPS) for a small residential structure. The primary objective was the theoretical examination of the current waveshapes in different parts of the circuit and the division of the injected impulse current between the grounding system of the LPS and remote ground. Two different approaches are adopted in modeling of impulse excitation. First, the simple current source described by double-exponential approximation is used. In the second approach the circuit model of the generator connected to the return path is implemented to ATP-EMTP simulation. Vertical and horizontal ground electrodes are modeled for specified parameter resulting from the geometrical configuration of the system and the measured soil resistivity. Computed currents show a good agreement with the experimental data obtained in 2013 using the impulse current generator at the test site in Poland. A significant influence of frequency dependent components of the system impedances on current waveshapes is noticed. The same as for measurements current waveshapes in the vertical ground electrodes differed from the injected current waveshapes and from the current waveshapes in other parts of the test system.