Adaptive Power Decoupling Strategy for Single-Phase Grid-Connected Converter

Abstract

This study analyzes the power coupling in the single-phase grid-connected system and designs a novel power decoupling method for restraining the ripple voltage on the dc bus. First, the phenomena of power coupling under a non-ideal power grid, and the circuits with an active power decoupling method are derived. By introducing a ratio factor between dc bus capacitors, the decoupling ability in the proposed method can be improved. In order to achieve accurate power decoupling, a neural filter is adopted for clearly identifying the dc bus voltage level and extracting the ripple voltage on the dc bus. In addition, a total sliding-mode controller is further designed in the control strategy to enhance the system robustness with respect to varied power coupling conditions, e.g., under ideal or distorted power grids. The effectiveness of the proposed method is verified by numerical simulations and experimental results in comparison with a traditional capacitor decoupling method and an active power decoupling method with multi-proportional-resonant controllers in previous researches.