Rotational Speed Control of a Wind Turbine Based on Rotor Acceleration

• US 20110221194A1
• Filed: 03/04/2011
• Published: 09/15/2011
• Est. Priority Date: 03/10/2010
• Status: Active Grant

• Current Assignee: Siemens Gamesa Renewable Energy A/S (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Stiesdal, Henrik, Egedal, Per, Winther-Jensen, Martin, Lind, Soeren Oemann, Kjaer, Ole
• Granted Patent: US 8,829,699 B2
• Time in Patent Office: Days
• US Class Current: 290/44
• CPC Class Codes: F03D 7/0224 Adjusting blade pitch
• CPC Class Codes: F03D 7/0276 controlling rotor speed, e.g. variable speed
• CPC Class Codes: F03D 7/028 controlling wind motor output power
• CPC Class Codes: F03D 7/042 by means of an electrical or electronic controller
• CPC Class Codes: F05B 2270/101 to control rotational speed (n)
• CPC Class Codes: F05B 2270/1011 to prevent overspeed
• CPC Class Codes: F05B 2270/1016 in variable speed operation
• CPC Class Codes: F05B 2270/102 to control acceleration (u)
• CPC Class Codes: F05B 2270/309 Rate of change of parameters
• CPC Class Codes: F05B 2270/327 Rotor or generator speeds
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

It is described a method for controlling the rotational speed of a rotor of a wind turbine in particular at high wind speeds. The described method comprises (a) determining a rotor acceleration value, wherein the rotor acceleration value is caused by a temporal change of the rotational speed of the rotor, and (b) controlling the rotational speed of the rotor as a function of the rotor acceleration value. It is further described a control system for controlling the rotational speed of a rotor of a wind turbine, a wind turbine being equipped with such a control system and to a computer program, which is adapted for controlling and/or for carrying out the mentioned rotational speed control method.

Claims

1-14. -14. (canceled)

15. A method for controlling the rotational speed of a rotor of a wind turbine during high wind speeds, the method comprising

determining a rotor acceleration value, wherein the rotor acceleration value is caused by a temporal change of the rotational speed of the rotor;

and

controlling the rotational speed of the rotor as a function of the rotor acceleration value.

16. The method as set forth in claim 15, wherein the controlling the rotational speed of the rotor comprises:

determining an internal speed limit, which is based on the rotor acceleration value, and

controlling the rotational speed of the rotor as a function of the determined internal speed limit.

17. The method as set forth in claim 16, wherein

the rotational speed of the rotor is controlled by a speed reference value, and

the speed reference value is the minimum value taken

(a) from the internal speed limit, and

(b) from an external speed limit and/or a nominal speed reference value.

18. The method as set forth in claim 17, wherein the controlling the rotational speed of the rotor comprises:

determining a power generation reference value and/or a blade pitch angle reference value based on the speed reference value, and

using the power generation reference value for operating the wind turbine and adapting the blade pitch angle of at least one blade of the rotor to the blade pitch angle reference value.

19. The method as set forth in claim 17, wherein the controlling the rotational speed of the rotor comprises:

determining a power generation reference value and/or a blade pitch angle reference value based on the speed reference value, and

using the power generation reference value for operating the wind turbine.

20. The method as set forth in claim 17, wherein the controlling the rotational speed of the rotor comprises:

determining a power generation reference value and/or a blade pitch angle reference value based on the speed reference value, and

using the power generation reference value for adapting the blade pitch angle of at least one blade of the rotor to the blade pitch angle reference value.

21. The method as set forth in claim 15, wherein the determining the internal speed limit comprises:

measuring the rotational speed of the rotor, and

calculating the rotor acceleration value by taking the derivative with respect to time of the measured rotational speed.

22. The method as set forth in claim 21, wherein the determining the internal speed limit further comprises:

taking the absolute value of the calculated rotor acceleration value.

23. The method as set forth in claim 19, wherein the determining the internal speed limit further comprises:

filtering the calculated rotor acceleration value.

24. The method as set forth in claim 19, wherein the determining the internal speed limit further comprises

determining an acceleration limit, which represents a maximal allowable rotor acceleration, and

comparing the rotor acceleration value with the determined acceleration limit.

25. The method as set forth in claim 22, wherein

the acceleration limit is determined based on

at least one of the following parameters characterizing the actual operational state of the wind turbine;

(a) the rotational speed of the rotor,

(b) the amount generated power, and

(c) the pitch angle of at least one blade of the rotor.

26. The method as set forth in claim 22, wherein

the acceleration limit is determined based on

an estimated wind speed,

the actual wind speed and/or

a change of an estimated and/or actual wind speed.

27. The method as set forth in claim 22, wherein the determining the internal speed limit further comprises:

integrating over time a result of comparing the rotor acceleration value with the determined acceleration limit.

30. A computer program for controlling the operation of a wind turbine at high wind speeds, the computer program, when being executed by a data processor, is adapted for controlling and carrying out the method as set forth in any one of the claims 15.

28. A control system for controlling the rotational speed of a rotor of a wind turbine in particular at high wind speeds, the control system, comprising:

a determining arrangement for determining a rotor acceleration value, wherein the rotor acceleration value is caused by a temporal change of the rotational speed of the rotor, and

a control unit for controlling the rotational speed of the rotor as a function of the determined rotor acceleration value.

29. A wind turbine for generating electrical power, the wind turbine comprising

a rotor with at least one blade, wherein the rotor is rotatable around a rotational axis and the at least one blade extends radial with respect to the rotational axis;

a generator mechanically coupled with the rotor; and

a control system as set forth in the claim 28.