Research Center for Photovoltaic System Engineering of Ministry of Education, Hefei University of Technology, Hefei 230009, China

A novel low voltage ride-through(LVRT)control scheme based on proportional-integral-resonant(PIR)controller and also applicable to current source converter based direct-drive permanent magnet synchronous generator(PMSG)wind generation system(CSC-DPMSG-WGS)is proposed. Based on the proposed method, once unbalanced grid voltage dip happens, the generator-side converter will quickly limit the power which flows to the DC-link to coordinate the grid-side and generator-side power. Meanwhile the grid-side converter adopts the PIR controller to control the positive and negative sequence current simultaneously in the positive sequence rotating coordinate system. This is intended to eliminate the power fluctuation of twice the fundamental frequency caused by unbalanced grid fault and maintain DC current stability. It is proved by simulation and experimental results that the proposed control strategy can eliminate the fluctuation of DC current and realize LVRT during balanced and unbalanced dip faults.