One Model of Lightning Discharge Electromagnetic Field in the Vicinity of Single Protection Rod in Frequency Domain

摘要

In this paper unknown current distribution (UCD) is determined along vertical mast antenna (VMA) which models lightning discharge channel (LDC) in the vicinity of vertical lightning protection rod (LPR) in frequency domain. Counter-poises of VMA and LPR are modeled by small semi-spherical ground electrodes, while real ground is modeled as homogeneous lossy half-space (LHS). VMA and LPR are treated as unique system as for boundary conditions which results in the System of integral equations of two potentials (SIE-TP) for UCD-s along VMA and LPR. SIE-TP is numerically solved by using Point Matching Method (PMM) and polynomial approximation for the UCD-s. The influence of the real ground, expressed through Sommerfeld''s integral kernel (SIK), is modeled using new so-called Two-image approximation (TIA). This approximation gives good results for modeling in both near and far field. The lightning impulse problem can thus be solved using IFT (Inverse Fourier Transform) applied to the results in frequency domain obtained for each frequency in the presented way.