Calculation of Electromagnetic Field Produced by Mixed Overhead Power Lines

The main goal of this paper is the investigation of the electromagnetic field produced by mixed overhead power lines, containing two three-phase electric systems on different voltage levels; middle-voltage system, for the distribution purpose and the low-voltage level, for the supply of consumers. In this paper electric and magnetic field produced by maximal load of two symmetrical systems were explored. The calculation was performed for the situation when only MV system is in function and the case when both systems are operational. Electric and magnetic field are calculated separately, applying COMSOL Multiphysics computer program package, based on Finite Element Method. As expected, electric field, produced by a MV system is dominant and the contribution of LV system is neglizible. On the other hand, since the phase currents in the both systems can be of the same order, magnetic field of both systems must be taking into account. Moreover, with the different phase arrangement it can be achieved the minimal values of magnetic field in vicinity of the system conductors, which is crucial for the environment protection. The investigated model was the real system, applied in Serbia. The results of the calculations are presented graphically, by the diagrams of electric field strength vector spatial distribution in vicinity of the system, as well as the diagrams of magnetic flux density vector spatial distribution.