Choi, Woojung2020-09-222020-09-222020-07https://hdl.handle.net/11299/216310University of Minnesota M.S.E.C.E. thesis. 2020. Major: Electrical/Computer Engineering. Advisor: Ned Mohan. 1 computer file (PDF); 82 pages.This paper proposes strategies to improve fault ride-through (FRT) capability of the modular multi-level converter (MMC) - high voltage direct current (HVDC) system connected to large offshore wind farms and performs simulations. In offshore wind power plants, HVDC system is indispensable for long-distance high-capacity transmission. The voltage rise of HVDC-link happens inevitably due to energy accumulation to satisfy low voltage ride-through (LVRT) regulation when a main grid fault occurs. This paper presents strategies for controlling HVDC-link voltages while minimizing the application of DC choppers and the mechanical and electrical stress of wind turbines through fast fault detection and current limit control of the master controller and wind turbine converter. PSCAD/EMTDC simulation is performed to verify the control strategies, and the results show that the FRT capability is enhanced by controlling HVDC-link voltage properly.enHVDCMMCoffshore wind farmsThesis or Dissertation