Wind turbine and method of deicing wind turbine blade

1. A wind turbine, comprising:

a rotor including a plurality of blades; and

a deicing unit,

wherein said deicing unit performs a deicing operation only on one or more of said plurality of blades, which has an azimuth angle within a predetermined range, and

said predetermined range is within a range from 90 to 270 degrees,

wherein said deicing unit includes:

a pitch angle controller independently controlling rotations of said plurality of blades around respective pitch axes; and

an acoustic generator provided on a tower supporting said rotor,

wherein, in said deicing operation, said pitch angle controller holds said one or more of said plurality of blades in a fine state or an inversion state in which the pitch angle thereof differs in 180 degrees from that of the fine state, and

wherein said acoustic generator outputs acoustic wave to said one or more of said plurality of blades.

2. The wind turbine according to claim 1 , wherein said deicing unit includes

an azimuth angle detection unit detecting an azimuth angle of each of said plurality of blades,

said plurality of blades includes

a first blade,

said pitch angle controller holds said first blade in the fine state or the inversion state in which a pitch angle thereof differs in 180 degrees from that of the fine state when a first azimuth angle of said first blade falls in said predetermined range, and

said pitch angle controller holds said first blade in a feathering state, a state between the fine state and the feathering state or a state between the inversion state in which the pitch angle thereof differs in 180 degrees from that of the fine state and the feathering state when said first azimuth angle does not fall in said predetermined range.

3. The wind turbine according to claim 1 , wherein said acoustic generator does not output the acoustic wave when none of said plurality of blades has an azimuth angle within said predetermined range.

4. The wind turbine according to claim 1 , wherein a frequency of said acoustic wave is an integer multiple of a resonance frequency of said one or more of said plurality of blades, the integer being equal to or greater than 1.

5. The wind turbine according to claim 1 , wherein said deicing unit includes an icing detection unit, and

said deicing unit performs said deicing operation when said icing detection unit detects icing on said rotor.

6. The wind turbine according to claim 5 , wherein said deicing unit stops performing said deicing operation when said icing detection unit does not detect the icing on said rotor.

7. The wind turbine according to claim 1 , wherein said deicing unit includes a weather condition detection unit,

wherein said deicing unit performs said deicing operation when said weather condition detection unit detects a predetermined weather condition.

8. The wind turbine according to claim 1 , wherein said deicing unit performs said deicing operation regularly.

9. A wind turbine blade deicing method, comprising:

performing a deicing operation only on one or more of a plurality of blades provided for a rotor of a wind turbine, which has an azimuth angle falling in a predetermined range,

wherein said predetermined range is within a range from 90 to 270 degrees,

wherein said performing said deicing operation includes

causing an acoustic generator provided on a tower supporting said rotor to output acoustic wave to said one or more of said plurality of blades while holding said one or more of said plurality of blades in a fine state or an inversion state in which a pitch angle thereof differs in 180 degrees from that of the fine state.

10. The wind turbine blade deicing method according to claim 9 , further comprising:

detecting a first azimuth angle of a first blade out of said plurality of blades during rotation of said rotor;

holding said first blade in the fine state or the inversion state in which a pitch angle thereof differs in 180 degrees from that of the fine state when said first azimuth angle falls in said predetermined range; and

holding said first blade in a feathering state, a state between the fine state and the feathering state or a state between the inversion state in which the pitch angle thereof differs in 180 degrees from the fine state and the feathering state when said first azimuth angle does not fall in said predetermined range.

11. The wind turbine blade deicing method according to claim 9 , wherein said acoustic generator does not output the acoustic wave when none of said plurality of blades has an azimuth angle within said predetermined range.

12. The wind turbine blade deicing method according to claim 9 , wherein said deicing operation is performed in a state in which said rotor is stopped.

13. The wind turbine blade deicing method according to claim 9 , wherein said deicing operation is performed when icing on said rotor is detected.

14. The wind turbine blade deicing method according to claim 13 , further comprising: stopping performing said deicing operation when the icing on said rotor is not detected.

15. The wind turbine blade deicing method according to claim 9 , wherein said deicing operation is performed when a predetermined weather condition is detected.

16. The wind turbine blade deicing method according to claim 9 , wherein said deicing operation is performed regularly.