A low cost high performance UPQC for current and voltage harmonics compensations

This paper introduces a low cost high performance three-phase unified power quality conditioner (UPQC) by using four-switch three-phase inverters. In the proposed UPQC, both shunt and series active power filters (APFs) are developed by using four-switch three-phase inverters so that the number of switching devices in the proposed topology is reduced from twelve in the traditional UPQC down to eight devices. In addition, by inserting an additional capacitor in series with the shunt APF, the DC-link voltage in the proposed UPQC can also be greatly lessened. As a consequence, by using a smaller number of power switches with lower rating voltage in the proposed UPQC system, we can greatly reduce the system cost of the UPQC without degrading the harmonic compensation performance. Design of passive components for the proposed UPQC to achieve a good performance is discussed in detail in this paper. Simulation studies are performed to verify the effectiveness of the proposed topology.