Accurate Calculation of Magnetic-Field Intensity Due to Overhead Power Lines With or Without Mitigation Loops With or Without Capacitor Compensation

An accurate method for the evaluation of 50-Hz magnetic fields produced by overhead power lines is presented. The method, which is based on the matrix formalism of multiconductor transmission lines (MTL), allows for a correct evaluation of all the currents flowing in the MTL structure, including the currents in the subconductors of each phase bundle, the currents in the ground wires, the currents in the mitigation loop (if present), and also the earth return currents. Furthermore, the analysis also incorporates the nonuniform character of the structure arising from conductor sagging between towers. Frequency domain magnetic field calculations are performed by vectorial sum of the magnetic effects originated by all the existing currents. For exemplification purposes the case of an actual 400-kV–1.4-GVA single-circuit three-phase line is examined. Results presented include a discussion on the effects of mitigation loops with or without capacitor compensation.