A control strategy for unified power quality conditioner

This paper presents a control strategy for a unified power quality conditioner. This control strategy is used in three-phase three-wire systems. The UPQC device combines a shunt-active filter together with a series-active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current. Previous works presented a control strategy for shunt-active filter that guarantees sinusoidal, balanced and minimized source currents even if under unbalanced and/or distorted system voltages, also known as "sinusoidal fryze currents". Then, this control strategy was extended to develop a dual control strategy for series-active filter. Now, this paper develops the integration principles of shunt current compensation and series voltages compensation, both based on instantaneous active and non-active powers, directly calculated from a-b-c phase voltages and line currents. Simulation results are presented to validate the proposed UPQC control strategy.