Influence of Inrush Current on Second Harmonic Characteristics of Direct-driven Wind Turbine

In the large-scale PMSG delivery system, when the adjacent transformer is closed to the Wind power generator grid bus without load, the excitation inrush current may cause the Wind power generator output current to distort, and in serious cases, cause the Wind power generator off-grid accident. Taking the no-load closing of adjacent transformers as the scene, this paper introduces the structure and control strategy of the PMSG grid-connected system, proposes the suppression method of the nth harmonic current of the Wind power generator output current three-phase n (n=2,3,⋯⋯, the same below) frequency doubling rotation dq feedback, establishes the model of the nth harmonic current suppression loop to suppress the nth harmonic current caused by the excitation inrush current. Finally, the correctness of the proposed suppression measures is verified by PSCAD/EMTDC simulation platform.