Operating Region of a Three-Phase UPQC Including Photovoltaic Power Injection

The UPQC has been widely used to improve power quality. Therefore, in this new topology, it is relevant to study the limitations in order to obtain maximum benefit. This paper presents the stationary analysis of a three-phase unified power quality conditioner with the injection of active power in the DC link from a solar panel farm. The transformation from abc axes to dq axes is used to convert sinusoidally varying quantities into constant quantities. This allows finding an explicit solution of the system's state variables and inputs for a specific operating condition, which is useful for obtaining the system's operating region. Hence, establishing the voltage variations at the Point of Common Coupling (PCC) and the power factor of the load that the UPQC can compensate, in order to maintain the voltage at the load at nominal values and a specified power factor at the PCC. Another condition imposed in this work is that the topology should not absorb active power from the grid, aiming to reduce the losses of the topology. The preliminary results show that injecting active power from solar panels into the DC link enhances the ability to compensate sags and swells at the PCC.