The control and compensation strategy research of unified power quality conditioner

This paper deals with the power flow analysis and control strategy research of unified power quality conditioner (UPQC). A UPQC is a combination of shunt and series active power filter (APF), sharing a common dc link. It can compensate almost all power quality problems such as voltage harmonics, voltage unbalance, voltage flickers, voltage sags, voltage swells, current harmonics, current unbalance, reactive current, etc. The power flow analysis is based on different compensation strategies. The energy flow relationships of two compensation strategies are analyzed in detail. The vector diagram is given on the basis of the energy analysis. The vector representation of the UPQC is also shown. This paper discusses the control strategy of the UPQC with a focus on the optimum angle injection. An experimental prototype is selected to verify the theoretical analysis. The experimental results are provided to prove the viability and effectiveness of the UPQC.