Operating Region of Single-Phase UPQCs

The stationary analysis of a single-phase unified power quality conditioner is introduced. The decomposition of a single-phase waveform into a sum of sine and cosine functions gives a representation of the original signals and at the same time allows to find the operating region of the system. This is due to the fact that a model where all the state variables become dc quantities in steady state is obtained. The operating region establishes that sags and swells can be readily compensated by the series converter of the unified power quality conditioner. However, the range is limited by the power factor at the point of common coupling, the dc link voltage of the topology, and the load voltage reference. Furthermore, the angle of the load voltage to the PCC voltage is found to be arbitrary. However, it can be chosen to obtain either a maximum compensating range for sags and swells or to operate the topology at minimum losses. Extensive simulated results probe the theoretical considerations