VFT Configuration for Decoupled Active-Reactive Powers Transfer Control

Variable frequency transformer (VFT) integrates the basics principles of rotary transformer and phase shifting transformer to control active power transfer between the two electrical networks. The active power transfer control concepts, design, and transient produce of the VFT have been deliberate in summary and are reported in the literature. However, reactive power flow through the VFT has not been appreciates so far. In the live installations, in order to encounter the VFT internal reactive current needed (magnetizing), switched capacitor banks are being used on the two sides of the VFT. These switched capacitor banks are outside to deal with uncontrolled reactive power interchange that can happen between the two networks through the VFT. This may attain desired power factor operation, but cannot avert the undesired reactive power exchange. These paper represent the detailed study on reactive flow through the VFT. The paper also proposes a new VFT configuration (with integrated partially-rated series voltage compensation strategy) to achieve a total control over reactive power flows. Thereby, the proposed design can achieve the bidirectional and decoupled active and reactive power flow through VFT.