A wye-delta multi-function balance transformer based power quality control system for single-phase power supply system

This paper proposed a wye-delta multi-function balance transformer based power quality control system (MBT-PQCS) to deal with the power quality problems in the single-phase power supply system. MBT-PQCS is mainly consists of a wye-delta multi-function balance transformer (YD-MFBT) and a three-phase full-bridge converter (FBC). It fully explores the inherent negative sequence current (NSC) suppressing ability of YD-MFBT, which makes the active power transformed by FBC is less than that of conventional transformer based compensating system. On the other hand, because YD-MFBT exits an interface for connection of active part, so FBC can be integrated with the main transformer without the help of other high-power auxiliary transformers. Hence the initial cost, installing difficulties, and covering space of the whole compensating system are reduced significantly. First, the current transforming relationship and compensating principle of MBT-PQCS are presented. Second, the detection and control methods are given as well. Finally, the simulation and experiment results verify the effectiveness of the proposed system.