Propagation of lightning electromagnetic fields in the presence of buildings

Abstract Coupling of lightning electromagnetic fields to distribution lines causes overvoltages that can provoke interruption of energy supply and damage to equipment of the power network and consumers. The propagation of these electromagnetic fields is strongly affected by nearby buildings and the effect depends on both the electric and the geometric parameters of the buildings and on the electric characteristics of the soil. The influence of the permittivity and conductivity of buildings with different heights on the behavior of lightning electromagnetic fields was studied. First and subsequent strokes and different values of soil parameters were considered. The electromagnetic fields were calculated with the Microwave Studio module of the CST Studio Suite 2013 software. The results have shown that the vertical electric field is reduced by the presence of buildings, practically in the same way for first and subsequent strokes. PEC buildings cause significantly greater reduction than concrete buildings and the effect is greater for higher buildings. The influence of buildings on the horizontal electric field is very much complex. Depending on the specific condition and type of stroke (first or subsequent stroke), reduction or increase and polarity inversion can be observed, along with negative excursion and oscillation. Regarding magnetic fields, only with subsequent strokes and higher PEC buildings a significant effect was observed due to the occurrence of oscillations.