Mitigation of residential magnetic fields generated by MV/LV substations

The design of a magnetic shielding arrangement for an indoor substation is considered. The aim of the intervention is to reduce the magnetic field intensity inside a room above the substation. Stray fields are mitigated by using metallic screens and by rearranging LV cables in order to limit intervention costs. A three-dimensional electromagnetic analysis of stray fields is performed by means of an original integral code, whereas a two-dimensional FEM software is used for assessing the shielding performance locally, in proximity of LV cables. Simulations show that the highest field attenuation levels are attained when phases of conductors and transformers are arranged in optimised configurations. The developed procedure is then applied to design a magnetic shield for a MV/LV substation. It is shown that measured and computed field r.m.s. values of the magnetic flux density are in good agreement.