VARIABLE-SPEED POWER GENERATION DEVICE AND CONTROL METHOD THEREFOR

Reactive power is supplied in accordance with a reactive-power supply instruction from a power grid while ensuring a variable-speed range of a wound-rotor induction generator. A variable-speed power generator (1) includes a prime mover that generates motive power by using natural energy; an electric generator (6) that includes a stator having a primary winding and a rotor having a secondary winding, the stator and the rotor being connected to a power grid (2), and that generates electric power based on the motive power generated by the prime mover; and a power converter (17) connected to the stator and the rotor, wherein the power converter (17) does not supply reactive power to the power grid (2), and wherein the variable-speed power generator (1) includes a power-converter controller (21) that causes the electric generator (6) to operate at a rotation speed set to be higher than or equal to a synchronous speed and increases reactive power supplied to the power grid (2) when a reactive-power supply instruction for supplying reactive power to the power grid (2) is obtained from the power grid (2).