Three-Phase Unified Power Quality Conditioner based on H-bridge and High-Frequency Link

In this paper, a three-phase unified power quality conditioner (UPQC) based on H-bridge and high-frequency link is proposed and investigated. The shunt converter compensates reactive power from the load and supplies the isolated H-bridges dc links of the series unit. The connection between the series and shunt dc links is performed applying a unidirectional isolated dc-dc converter. A multi-winding high-frequency transformer (HFT) is implemented allowing the dc-dc power conversion. The proposed UPQC is able to mitigate grid voltage sag using conventional active power compensation strategies. Hence, HFT along with unidirectional dc-dc converter might optimize the overall UPQC power density while reducing the control complexity of dc-dc stage. Operating principle, high-frequency link implementation, PWM strategy, control approach as well as comparison with similar structures are discussed in this work. Simulation and experimental results are presented in order to evaluate the proposed system.