Thrust control for wind turbines using active sensing of wind turbulence

Patent metadata

Field	Value
Publication number	US-11408396-B2
Application number	US-202117144377-A
Country	US
Kind code	B2
Filing date	Jan 8, 2021
Priority date	Jan 8, 2021
Publication date	Aug 9, 2022
Grant date	Aug 9, 2022

Abstract

A wind turbine and method are provided for defining a plurality of thrust limits for the wind turbine located at a site and having a rotor with rotor blades, wherein the thrust limits define values of aerodynamic thrust on the rotor not to be exceeded in operation. The method includes providing a wind speed distribution representative for the site and defining one or more isolines of constant turbulence probability representing a turbulence parameter as a function of wind speed. The isolines correspond to quantile levels of turbulence of the wind speed distribution and the turbulence parameter is indicative of wind speed variation. The turbulence parameter is determined by continuously measuring wind speed upstream of the rotor with an active sensing system and calculating the wind speed variations from the measured wind speed. Turbulence ranges are defined with respect to the isolines and thrust limits are defined for the turbulence ranges.

First claim

What is claimed is:

1. A method for defining a plurality of thrust limits for a wind turbine located at a site and having a rotor with a plurality of blades, wherein the thrust limits define values of aerodynamic thrust on the rotor not to be exceeded in operation, the method comprising:
providing a wind speed distribution representative for the site,
defining one or more isolines of constant turbulence probability representing a turbulence parameter as a function of wind speed, wherein the isolines correspond to quantile levels of turbulence of the wind speed distribution and the turbulence parameter is indicative of wind speed variation;
wherein the turbulence parameter is determined by substantially continuously measuring wind speed upstream of the rotor with an active sensing system and calculating the wind speed variations from the measured wind speed;
defining turbulence ranges with respect to the isolines; and
defining thrust limits for the turbulence ranges.

2. The method according to claim 1 , wherein the active sensing system uses a Doppler lidar system to generate multiple measurement beams directed upwind of the wind turbine to sample an incoming wind flow.

3. The method according to claim 2 , wherein the measurement beams are fixed measurement beams directed at a different angle relative to an axis of the rotor to define an increasing sample field as distance from the rotor increases, each of the fixed measurement beams measuring wind speed and at a plurality of different ranges from the rotor.

4. The method according to claim 3 , wherein the Doppler lidar system generates five fixed measurement beams and each fixed measurement beam detects wind speed at ten different ranges from the rotor.

5. The method according to claim 4 , wherein the wind turbine includes a nacelle, the Doppler lidar system mounted atop the nacelle, the fixed measurement beams comprising a center axial beam and a plurality of additional beams projecting at an angle away from the center axial beam and spaced equally around a circular circumference.

6. The method according to claim 3 , wherein wind measurements from the plurality of different ranges for each fixed measurement beam are used to calculate a mean wind speed of the incoming wind flow and a standard deviation of the wind speed, wherein the standard deviation of the wind speed corresponds to the turbulence parameter.

7. The method according to claim 6 , wherein the wind speed measurements and calculation of the standard deviation are performed at a rate of at least 4 Hz, the standard deviation calculations smoothed by a low-pass filter.

8. The method according to claim 7 , wherein a filter time constant for the low-pass filter is adjustable and selected to approximate a typical wind speed of the incoming wind flow and an average range of wind speed measurements from the rotor.

9. The method according to claim 6 , wherein the isolines define the standard deviation as a linear function of the wind speed within a wind speed range.

10. The method according to claim 1 , wherein the wind speed distribution for the site is based on wind measurements at a site of the wind turbine.

11. The method according to claim 1 , further comprising selecting one of the thrust limits based on the determined turbulence parameter and the determined wind speed, and operating the wind turbine such that a thrust on the rotor is below the selected thrust limit.

12. The method according to claim 11 , wherein operating the wind turbine such that a thrust on the rotor is below the predetermined thrust limit comprises comparing the thrust on the rotor with the selected thrust limit, and if the thrust is above the selected thrust limit, sending a collective pitch signal to the blades of the rotor to pitch the blades and reduce the thrust on the rotor.

13. A wind turbine comprising:
a rotor with a plurality of blades;
a pitch system configured with the blades to rotate the blades around longitudinal axes of the blades;
an active sensing system mounted on the wind turbine, the active sensing system comprising a Doppler lidar system that generates measurement beams upwind of the wind turbine to detect wind speed of an incoming wind flow;
a control system in communication with the Doppler lidar system and configured to:
substantially continuously measure the wind speed of the incoming wind flow and calculate a turbulence parameter corresponding to wind speed variations from the measured wind speeds;
select a thrust level based on the turbulence parameter and the measured wind speed, wherein the thrust level is selected from a plurality of thrust limits for different turbulence ranges, the plurality of thrust limits determined by quantile-based regression of a wind speed distribution of wind speed and the turbulence parameter; and
send signals to the pitch system to collectively pitch the blades such that aerodynamic thrust on the rotor is below the selected thrust level.

14. The wind turbine according to claim 13 , wherein the Doppler lidar system is configured to generate multiple fixed measurement beams upwind of the wind turbine to sample the incoming wind flow, wherein each of the fixed measurement beams detects wind speed at a different angle relative to an axis of the rotor and at a plurality of different ranges from the rotor.

15. The wind turbine according to claim 14 , further comprising a nacelle, the Doppler lidar system mounted atop the nacelle, the fixed measurement beams comprising a center axial beam and a plurality of beams projecting at an angle away from the center axial beam and spaced equally around a circular circumference.

16. The wind turbine according to claim 15 , wherein the control system is configured to use the wind measurements from the plurality of different ranges for each fixed measurement beam to calculate a mean wind speed of the incoming wind flow and a standard deviation of the wind speed, wherein the standard deviation of the wind speed corresponds to the turbulence parameter.

17. The wind turbine according to claim 16 , wherein the wind speed measurements and calculation of the standard deviation are performed by the control system at a rate of at least 4 Hz, the standard deviation calculations smoothed by a low-pass filter.

18. The wind turbine according to claim 17 , wherein the control system sets the filter time constant for the low-pass filter to approximate a typical wind speed of the incoming wind flow and an average range of wind speed measurements from the rotor.

Assignees

• General Electric Renovables Espana Sl

Inventors

• Bonanni Pierino Gianni
• Fu Xu
• Perrone Francesco

Classifications

• F03D80/00 Primary

  Details, components or accessories not provided for in groups F03D1/00 - F03D17/00 · CPC title

• F03D7/0236

  by changing the active surface of the wind engaging parts, e.g. reefing or furling · CPC title

• F03D1/0675

  of the blades · CPC title

• F03D1/0658

  Arrangements for fixing wind-engaging parts to a hub · CPC title

• F03D17/00

  Monitoring or testing of wind motors, e.g. diagnostics (testing during commissioning of wind motors F03D13/30) · CPC title