The Equivalent Circuit Model of a Four-Winding Inductive Filtering Transformer and its Filtering Characteristics

A four-winding inductive filtering transformer (FW-IFT) that is of a special filtering winding is designed according to the equivalent zero impedance principle of multi-winding transformer. The inductive filtering method with the series connection of the passive filter and the filtering winding of a FW-IFT is proposed to deal with the problem of reactive power and harmonics in a high-voltage distribution network. The equivalent circuit model of the FW-IFT is analyzed in detail from the inductive filtering condition. Then, the voltage equations are established, and harmonic suppression factor is introduced to analyze its filtering characteristics. The simulation and experimental results are provided to verify the feasibility of implementing the inductive filtering for the FW-IFT.