Magnetic Fields in Multiconductor Systems with Harmonic Currents.

Abstract

Electric and magnetic fields produced by power transmision and distribution lines are receiving strong interest due to its biological effects and interference disturbances upon electronic and computer equipment. The presence of currents with harmonic contents, generated by variable speed drives and other power electronic devices worsen the problem. The accurate evaluation of the magnteic field in the vicinity of the line must take into account the non uniform distribution of currents inside the conductors, due to skin and proximity effects. The spatial distribution of induction lines down to the ground level must be plotted, to evaluate its effects in the body of a person situated below the line This paper proposes a two step procedure for solving the problem: first, the non uniform distribution of the currents in the conductors is calculated, applying Maxwell laws. Second, the distribution of the field is obtained, using a very fast and innovative approach, based on the application of the Bidimensional Fast Fourier Transform to solve a bidimensional convolution in the domain of the spatial frequency.