Research on Harmonic Suppression Strategy of Grid - Connected Inverter Based on Power Grid Background Harmonics

摘要

The current quality is an important indicator to evaluate the performance of a grid-connected inverter. In practice, many factors including the grid voltage distortion, dead-time effect, non-ideal switches and dc-link disturbances would result in many low-order harmonics in the injected grid current. To improve the current quality of LCL-type grid-connected inverter, accurate equivalent impedance network model is proposed by incorporating dead-time effects and digital control delay into the model. From Norton equivalent circuit model, a combined scheme for harmonic suppression is proposed based on detailed performance analysis of partial grid voltage feed-forward, full grid voltage feed-forward and multi-resonant control schemes in this paper. Finally, experimental results are presented to demonstrate the effectiveness of the proposed multi-resonant control schemes.