Performance Evaluation of UPQC for Interconnecting Photovoltaic Systems to the Electric Grid

摘要

This paper proposes the efficient operation of a unified power-quality conditioner (UPQC) for interconnecting the photovoltaic (PV) systems to the utility grid. An extended reference signal generation scheme is proposed based on a modified version of the p-q theory using a high selectivity filter (HSF) and power angle control method. The proposed topology provides PV power generation, as well as the function of the UPQC. The shunt active power filter (SAPF) is used to extract the power from the PV power-generating system along with compensating the current harmonics and reactive power. The series active power filter (APF) in the UPQC is used for supplying a part of reactive power required by the load, along with the compensation of the voltage sag/swell, voltage unbalance, and voltage harmonics. This is achieved by controlling the phase angle and magnitude of series injected voltage called the power angle control method. The proposed topology utilizes the renewable energy source with an energy storage unit to meet the dc-link voltage requirement of the shunt and series APF of the UPQC. The shunt inverter control scheme is based on the use of HSF for reference-current generations. In addition, the fuzzy-logic controller is implemented for better current control accuracy of the shunt active filter. The simulation and experimental studies are carried out to validate the effectiveness of the proposed PV-based three-phase, four-wire UPQC.