THREE-LEG, STANDBY CONVERTER-BASED SINGLE-PHASE TRANSFORMERLESS UNIFIED POWER QUALITY CONDITIONER

Abstract

This paper proposes a transformer less single-phase to single-phase unified power quality conditioner (UPQC) based on three-leg and standby converters. The system consists of a two-leg module series connected to a threeleg module; the control system offers shunt and series compensation and can be designed to operate with a high modulation index under rated conditions and voltage sag events; additionally, a low standby power consumption and a new decoupling method to compensate voltage swells using the two-leg module. In comparison to the conventional solution, the proposed converter shows lower semiconductor losses and reduced waveform harmonic distortion, while retaining the same or better operational features, such as the elimination of circulating currents and line-frequency transformers.