| With the increased presence of wind energy in the electric power system, many utilities now have grid code requirements specific to wind turbines. Low voltage ride through (LVRT) is one such requirement, where turbines have to stay connected to the grid for typical faults on the transmission systems. Solutions have been proposed for wind turbines equipped with doubly fed induction generators (DFIG). This thesis is a contribution to a comparative assessment of the respective performance of three LVRT solutions. This assessment is made in reference to representative existing grid codes. The DFIGs are placed in an electric power system benchmark which is subjected to a series of faults of various types, durations, and severities. The wind farm input wind speed is also varied to change the DFIGs operating conditions. The performance of each method is evaluated based on the DFIG response, such as rotor speed, rotor current, and dc bus voltage, and on the wind farm response, such as power generation, terminal voltage and output current. Recommendations on how the turbine using a given method should be modified to ensure that the LVRT requirement is met are made based on observations from simulations. |
