A wind generation system (100) includes a wind turbine (1) for generating mechanical power, a doubly-fed induction generator (2) for converting the mechanical power to electrical power, a converter (3) for converting the electrical power to a desired electrical power for supplying to a power grid, and a transformer (7) through which a stator of the generator (2) is coupled to the power grid. When a measured rotation speed feedback from the rotor (21) of the generator is lower than an original cut-in rotation speed of the rotor, a cut-in rotation speed of the rotor is lowered by determining a DC link (33) voltage margin of the converter, determining a DC link (33) voltage setpoint of the converter based on the determined DC link (33) voltage margin; and controlling the converter (3) based on the determined DC link (33) voltage setpoint; and/or by increasing a turn ratio of the transformer (7) to reduce a grid voltage from the power grid (6).