US 12,116,981 B2
Compensating gravity cycles of a pitching system
Søren Forbech Elmose, Bording (DK); Thomas Esbensen, Herning (DK); Gustav Hoegh, Vejle (DK); Tommy Hastrup Knudsen, Karup J (DK); Peder Bay Enevoldsen, Vejle (DK); and Eduardo Raymaska Wiputra, Westminster, CO (US)
Assigned to SIEMENS GAMESA RENEWABLE ENERGY A/S, Brande (DK)
Appl. No. 18/039,185
Filed by Siemens Gamesa Renewable Energy A/S, Brande (DK)
PCT Filed Nov. 17, 2021, PCT No. PCT/EP2021/081958
§ 371(c)(1), (2) Date May 26, 2023,
PCT Pub. No. WO2022/117342, PCT Pub. Date Jun. 9, 2022.
Claims priority of application No. 20211406 (EP), filed on Dec. 3, 2020.
Prior Publication US 2024/0003332 A1, Jan. 4, 2024
Int. Cl. F03D 7/02 (2006.01)
CPC F03D 7/0224 (2013.01) [F05B 2270/32 (2013.01); F05B 2270/326 (2013.01); F05B 2270/328 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method of controlling a pitching system of a rotating rotor blade of a wind turbine, the method comprising:
controlling the pitching system such that unintended pitching due to gravity is reduced, wherein controlling the pitching system comprises:
determining a control signal;
supplying the control signal to the pitching system, wherein the control signal varies in dependence of a rotational speed of the rotor,
the control signal comprising a component being defined by a periodic waveform function having as a repetition period the revolution period of the rotor,
wherein the control signal is determined based on a feedback signal, wherein the feedback signal comprises:
an actual blade torsion indicating signal indicating the actual torsion of the blade relative to a hub at which the blade is mounted,
wherein the control signal is supplied to a blade pitch angle actuator adapted to set a pitch angle,
wherein the blade pitch angle actuator comprises at least two pistons guided within two respective cylinders which are connected to a hydraulic system that is controlled based on the control signal,
wherein the control signal is adapted to drive the at least two pistons in order to reduce backlash,
wherein the control signal is determined such that to drive the at least two pistons:
in different directions towards restricting pitching movement, in case of torsion fluctuating is around or close to zero; and
in same direction enabling readjusting the pitch angle, if the torsion is positive or negative.