Control method for a wind turbine

Patent metadata

Field	Value
Publication number	US-9777708-B2
Application number	US-201113995449-A
Country	US
Kind code	B2
Filing date	Dec 15, 2011
Priority date	Dec 21, 2010
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A method of controlling a wind turbine comprising blades attached to a rotor hub for rotation in a rotor plane and a control system for individually pitching the blades relative to the hub. The method comprises dividing the rotor plane into a number of sectors, determining the individual sectors for each blade during the rotation by means of an azimuth angle sensor, and obtaining blade sensor data from a blade sensor on an individual blade relating to a sector, and comparing the obtained data with data relating to the same sector and representing blade sensor data on other blades. When an event is detected in a given sector, an individual pitch contribution is determined in the sector, and the blades are then pitched according to this individual pitch contribution for that given sector at least partly during passage of the sector.

First claim

The invention claimed is:

1. A method of controlling a wind turbine, the wind turbine comprising a plurality of blades attached to a rotor hub for rotation in a rotor plane and a control system for individually pitching each blade of the plurality of blades relative to the rotor hub, the method comprising:
dividing the rotor plane into a plurality of sectors;
determining, during the rotation of the plurality of blades, which sector of the plurality of sectors corresponds to each blade of the plurality of blades, wherein determining which sector corresponds to each blade is performed by means of an azimuth angle sensor;
obtaining, during the rotation of the plurality of blades, first blade sensor data from a blade sensor on a first blade of the plurality of blades during a first passage of the first blade through a first sector of the plurality of sectors, the blade sensor comprising a blade load sensor and the first blade sensor data comprising first blade load data;
comparing the first blade sensor data with second blade sensor data corresponding to the first blade or to a second blade of the plurality of blades, the second blade sensor data obtained during a second passage of the first blade or the second blade through the first sector during the rotation of the plurality of blades, the second blade sensor data comprising second blade load data;
calculating, based on the first blade sensor data for each sector of the plurality of sectors, a deviation from a defined normal operating condition, wherein the first blade sensor data compromises instantaneous blade sensor data, and wherein calculating a deviation from a defined normal operating condition comprises:
comparing the instantaneous blade sensor data relating to the first sector to a load threshold, the load threshold being a function of mean blade sensor data and a number of standard deviations;

detecting, based on the comparison of the first blade load data and the second blade load data, whether a predefined wind event has occurred within the first sector, wherein detecting whether the predefined wind event has occurred within the first sector is further based on the calculated deviation;
determining, upon detecting the predefined wind event within the first sector, an individual pitch contribution to be applied to each blade of the plurality of blades during a respective passage of each blade through the first sector; and
pitching each blade of the plurality of blades according to the determined individual pitch contribution during the respective passage of each blade through the first sector.

2. The method of controlling a wind turbine according to claim 1 , wherein the blade sensor comprises a blade stall sensor, wherein the first blade sensor data comprises blade stall data from the blade stall sensor.

3. The method of controlling a wind turbine according to claim 1 , further comprising:
detecting a spatial orientation of the wind turbine,
wherein the first blade sensor data comprises instantaneous blade sensor data relating to the first sector,
wherein detecting whether a predefined wind event has occurred comprises comparing the instantaneous blade sensor data to a load threshold, and
wherein the load threshold is a function of the spatial orientation.

4. The method of controlling a wind turbine according to claim 1 , wherein calculating a deviation from a defined normal operating condition comprises determining an instantaneous blade load, wherein the method further comprises:
reducing a first load threshold of a first sector by a factor, when the instantaneous blade load exceeds the load threshold in a second sector of the plurality of sectors, the second sector being less than a predefined number of sectors of the plurality of sectors away from said first sector.

5. The method of controlling a wind turbine according to claim 1 , wherein detecting whether a predefined wind event has occurred comprises:
comparing an instantaneous blade load relating to the first sector to a maximum load threshold reflecting a predetermined maximally acceptable blade load.

6. The method of controlling a wind turbine according to claim 5 , wherein detecting whether a predefined wind event has occurred further comprises:
comparing an instantaneous kinetic energy derived from the instantaneous blade load relating to the first sector to a kinetic energy threshold, the kinetic energy threshold being a function of a mean blade kinetic energy and a number of standard deviations.

7. The method of controlling a wind turbine according to claim 1 , wherein detecting whether a predefined wind event further has occurred comprises determining an instantaneous blade load, and
wherein each blade of the plurality of blades is pitched according to the determined individual pitch contribution during the respective passage of each blade through the first sector until the instantaneous blade load relating to the first sector is decreasing.

8. The method of controlling a wind turbine according to claim 1 , wherein detecting whether a predefined wind event further comprises determining an instantaneous blade load, and
wherein each blade of the plurality of blades is pitched according to the determined individual pitch contribution during the respective passage of each blade through the first sector until the instantaneous blade load relating to the first sector is decreased by a load factor, the load factor based on a maximum blade load obtained after detecting the predefined wind event.

9. The method of controlling a wind turbine according to claim 1 , wherein the individual pitch contribution is a function of a rotational speed of a rotor of the wind turbine.

10. The method of controlling a wind turbine according to claim 1 , where the control system is configured to initiate individually pitching each blade at an angular compensation distance prior to the blade entering the first sector.

11. The method of controlling a wind turbine according to claim 1 , wherein the individual pitch contribution is determined as a function of a position of the first blade within the first sector.

12. The method of controlling a wind turbine according to claim 1 , wherein the control system comprises a memory adapted for blade sensor data comprising the first blade sensor data and the second blade sensor data, and wherein the method further comprises:
determining, using the blade sensor data corresponding to sensors on a leading blade of the plurality of blades, a required pitch contribution of a lagging blade of the plurality of blades.

13. The method of controlling a wind turbine according to claim 1 , wherein the individual pitch contribution is determined as a function of a gradient of the first blade sensor data and the second blade sensor data.

14. The method of controlling a wind turbine according to claim 1 , wherein the individual pitch contribution is adjusted as a function of a difference between a load threshold for the first sector and a measured blade load.

15. The method of controlling a wind turbine according to claim 1 , wherein each sector of the plurality of sectors is between 5 degrees and 30 degrees.

16. The method of controlling a wind turbine according to claim 1 , wherein each sector of the plurality of sectors has an equal size.

17. A wind turbine comprising:
a plurality of blades attached to a rotor hub for rotation in a rotor plane;
a control system for individually pitching each blade of the plurality of blades relative to the rotor hub, wherein the control system is configured to:
determine, during the rotation of th

Assignees

• Risager Lars
• Dalsgaard Søren
• Kristoffersen Jacob Krogh
• Thomsen Jesper Sandberg
• Sørensen Søren
• Andersen Asger Svenning
• Vestas Wind Sys As

Inventors

• Risager Lars
• Dalsgaard Søren
• Kristoffersen Jacob Krogh
• Thomsen Jesper Sandberg
• Sørensen Søren
• Andersen Asger Svenning

Classifications

• F03D7/024

  of individual blades · CPC title

• F05B2270/326

  Rotor angle · CPC title

• F05B2270/331

  Mechanical loads · CPC title

• Y02E10/723

  Cross-Sectional Technologies · mapped topic

• F03D7/0224 Primary

  Adjusting blade pitch · CPC title