An Integrated Harmonic-Filtering Transformer for Low-Voltage Distribution Systems

There are ever-increasing harmonic concerns caused by nonlinear loads in today´s low-voltage distribution systems. Therefore, a passive-filter-based transformer equipped in the box-type distribution substations is conceived for power quality improvement. Attempting to address the problem that physical size is strictly confined in these prefabricated substations, a distribution transformer with integrated filtering inductors is proposed in this paper. The configuration, electromagnetic decoupling circuit, and design procedures of this transformer are described. To verify the theoretical analysis, finite-element simulations and experiments of an integrated distribution transformer prototype are performed, by which the essential electromagnetic performances of the proposed transformer, such as electromagnetic decoupling and inductance linearity of the integrated inductors, are validated.