Functionalities of unified power quality conditioner

This paper discusses the topology and control of a unified power quality conditioner (UPQC) that can be used simultaneously in voltage or current control mode in a power distribution system. In the voltage control mode, the UPQC can force the voltage of a distribution bus to be balanced sinusoids. At the same time it can also perform load compensation resulting in the drawing of balanced sinusoidal currents from the distribution system bus in the current control mode. Both these objectives are achieved irrespective of unbalanced and harmonic distortions in load currents or source voltage. We shall discuss a suitable UPQC structure that allows the tracking of the reference current and voltage generated to meet the objective stated above. The reference generation scheme along with the switching control scheme is presented in detailed. Extensive results of digital computer simulation studies are presented to validate the proposed structure and control