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Abstract:
As environmental pollution continues to rise, it is of great importance to ensure proper living conditions for humans. Along with rising electricity consumption, pollution from the magnetic field generated by electrical equipment and transmission lines is also increasing. The potential health effects of exposure to power frequency magnetic fields are referenced at levels of 0.2 µT to 3 µT in many countries. This study focuses on the magnetic field generated by indoor medium-voltage/low-voltage transformer substations. As the magnetic field in apartments above indoor substations exceeds the reference level, certain measures are to be taken. The so-called active shields are made of a closed current-carrying loop, a control system, and magnetic field sensors. They mitigate the magnetic field to the reference level. However, these shields continuously consume electric power. Therefore, the aim of this work is to develop a technique for designing energy-efficient active shields. The properties of these active shields are determined by solving an optimization problem that minimizes active power. Triangular, quadrangular, pentagonal, and hexagonal shapes of current-carrying loops are under study. Results show that using geometrically complex designs of active shields, particularly hexagonal ones, may be beneficial for energy-efficient and high-performance mitigation of the transformer substation magnetic field. Thus, the power consumption of the active shield is reduced from 50 W to 2.3 W when mitigating the magnetic field of the substation under study.

Keywords:
Magnetic field, Shielding, Transformer substation, Energy efficiency , Active power , Reference level , Optimization