A phase-locked method based on a novel cascaded adaptive filter

When connecting distributed generation systems like wind power to the grid, it is crucial to accurately detect the fundamental frequency and phase of the grid voltage in real-time. However, the presence of DC component and harmonics within the sampled grid voltage signal can hinder precise phase locking. In this paper, an improved adaptive filter (AF) structure is proposed to address these challenges. By utilizing a cascade method of dual adaptive filters, the novel cascaded adaptive filter (NCAF) effectively handles the DC component. This enhanced filter is then applied to the QT1-PLL structure, allowing for accurate extraction of the fundamental frequency, amplitude, and phase of the three-phase voltage signal even in the presence of DC component and harmonics. Simulation results validate the effectiveness of the phase-locked method based on the improved adaptive filter.