Harmonic current detection method of double frequency phase lock based on cascade SOGI

The ip-iq harmonic detection method generated in the theory of instantaneous reactive power has a complicated structure and a relatively long delay time. In order to simplify the structure of harmonic detection and improve the accuracy and speed of detection, this paper proposed a double-frequency harmonic current detection method adopting cascade SOGI structure. In this paper, the calculation of the active and reactive components of the load current in the ip-iq harmonic detection method is omitted. Then, by combining two SOGIs into a cascade structure, the structure is then used to extract the fundamental wave in harmonic current detection. After that, the harmonic command current is obtained through mathematical operation, which provides a precondition for future harmonic compensation. The proposed method can detect harmonics accurately and quickly. Simulations verify the effectiveness and applicability of the proposed method.