Method on the Calculation of Overhead Power Line Separate Wire Electromagnetic Characteristics

This paper presents a novel method for calculating the load and frequency characteristics (specifically, the linear inner complex electrical impedance), Zint of individual multistranded, coaxially twisted overhead power line (OHL) conductors. Accurate Zint data is essential for determining conductor heating, analyzing transient electromagnetic processes, and optimizing the selection new conductor types. The method achieves higher accuracy of conductor internal electromagnetic field calculation by assuming helical invariance of field and utilizing a quasi-orthogonal helical coordinate system for each layer, replacing heterogeneous layer media with homogeneous equivalents using effective specific electrical conductivity and magnetic permeability, and applying the L.R. Neyman theory for the skin effect in steel strands. The result is a refined, generalized model of coaxial wires and cables, enabling complete electromagnetic calculation across a wide range of frequencies and load conditions.