An Improved Harmonic Extraction Method for Grid Interactive Power Electronic Systems

Nonlinear and unbalanced loads causing harmonic currents to be drawn from microgrid give rise to unbalanced and distorted voltages at the Point of Common Coupling (PCC). In order to provide acceptable PCC voltages under certain standards, these harmonics have to be extracted from PCC voltages. With proper control methods, PCC voltages can be controlled to have a sinusoidal waveform meeting the certain standards, i.e. IEEE std 1547. In this study, with aim of obtaining a harmonic extraction method with high steady state accuracy and high dynamical performance, improved decoupling based harmonic extraction with DSOGI-PLL is proposed. The proposed method not only reduces the computational burden, but also providing fast and accurate extraction of harmonic components. Simulation results demonstrate feasibility and high performance of the proposed method.