Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title A Novel Digital Lock-In Amplifier Based Harmonics Compensation Method for the Grid Connected Inverter Systems
Authors Saghir Amin ; Muhammad Noman Ashraf ; Woojin Choi
DOI 10.6113/TKPE.2020.25.5.358
Page pp.358-368
ISSN 1229-2214
Keywords PV (Single Stage Photovoltaic System); MPPT (Maximum Power Point Tracking); Harmonic compensation method
Abstract Grid-connected inverters (GCIs) based on renewable energy sources play an important role in enhancing the sustainability of a society. Harmonic standards, such as IEEE 519 and P1547, which require the total harmonic distortion (THD) of the output current to be less than 5%, should be satisfied when GCIs are connected to a grid. However, achieving a current THD of less than 5% is difficult for GCIs with an output filter under a distorted grid condition. In this study, a novel harmonic compensation method that uses a digital lock-in amplifier (DLA) is proposed to eliminate harmonics effectively at the output of GCIs. Accurate information regarding harmonics can be obtained due to the outstanding performance of DLA, and such information is used to eliminate harmonics with a simple proportional?integral controller in a feedforward manner. The validity of the proposed method is verified through experiments with a 5 kW single-phase GCI connected to a real grid.