Transient Electromagnetic Fields Calculation around Transmission Lines using FDTD

Abstract

For proper design of transmission and distribution insulation systems, it is necessary to fully clarify the characteristics of lightning phenomena. In this study, two typical power transmission lines, 500 and 220 kV, were modeled to compute the lightning electromagnetic fields around the transmission lines. The lightning electromagnetic fields around the different power lines were calculated using the Finite Difference Time Domain (FDTD) method with Maxwell's equations. Two selected zones were used to capture electromagnetic fields during lightning strikes. The first zone was around the insulators and the second was at the ground level below the power line at 1 m above ground and the power line Right Of Way (ROW). The correlation between the induced magnetic and electric fields was verified in the free space inside the two selected zones. The induced electromagnetic fields were evaluated at different positions of each power line phase. The results obtained showed that while lightning strikes the conductor, the waveforms of the electromagnetic field obtained at the selected monitoring points were the same as the waveform of the lightning current. The amplitude of the electromagnetic field intensities exhibited a stable linear relationship with the lightning currents as the intrinsic impedance of the free air. This study was mainly concerned with transient electromagnetic fields that could appear inside high-voltage substations to clarify the electromagnetic exposure levels around high-voltage transmission lines.