A Unified Power Quality Conditioner (UPQC) is an integration of series and shunt active filters to improve power
quality in a power distribution system. Model-based control of UPQC has attracted attentions in recent years, which aims to regulate the source current and the load voltage to the desired reference signals in spite of the existence of harmonic components in the supply voltage and the load current, possible sag or swell in the supply voltage, and variations in the load current. However,most of the previous studies did not take the control saturation
explicitly into their control design. This paper investigates the performance limit of UPQC under control input constraints by means of a Model Predictive Controller (MPC). MPC is an optimal control strategy that can take into account control constraints explicitly. Simulation studies, mainly focused on the comparison of performance between the MPC and a linear Multi-Variable Regulator (MVR), are carried out on a single-phase power distribution system to help us understand the performance limit under such control saturation.