IMPROVEMENTS RELATING TO THE DETERMINATION OF ROTOR IMBALANCES IN A WIND TURBINE

• US 20170241404A1
• Filed: 08/28/2015
• Published: 08/24/2017
• Est. Priority Date: 09/01/2014
• Status: Active Grant

• Current Assignee: Vestas Wind Systems A/S
• Original Assignee: Vestas Wind Systems A/S
• Inventors: KRISTOFFERSEN, Jacob Krogh
• Granted Patent: US 10,669,986 B2
• Time in Patent Office: Days
• CPC Class Codes: F03D 1/06 Rotors
• CPC Class Codes: F03D 17/00 Monitoring or testing of wind motors, e.g. diagnostics testing during commissioning of wind motors F03D13/30
• CPC Class Codes: F03D 7/0224 Adjusting blade pitch
• CPC Class Codes: F03D 7/0296 to prevent, counteract or reduce noise emissions
• CPC Class Codes: F03D 7/042 by means of an electrical or electronic controller
• CPC Class Codes: F05B 2260/966 by correcting static or dynamic imbalance
• CPC Class Codes: F05B 2270/331 Mechanical loads
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

A method and system for improving the balance of a rotor in a wind turbine, including; determining blade load data associated with a selected rotor blade pair; determining, based on the blade load data, pitch imbalance data associated with the selected rotor blade pair, wherein the pitch imbalance data associated with a rotor blade pair is based on measurements of at least blade loading, rotor speed and wind speed; and, determining and applying pitch control inputs to one or both of the selected rotor blade pair in order to reduce the severity of the rotor imbalance.

Claims

1. A method of improving the balance of a rotor in a wind turbine, the method including;

determining blade load data associated with a selected rotor blade pair;

determining, based on the blade load data, pitch imbalance data associated with the selected rotor blade pair, wherein the pitch imbalance data associated with a rotor blade pair is based on measurements of at least blade loading, rotor speed and wind speed; and

determining and applying pitch control inputs to one or both of the selected rotor blade pair in order to reduce the severity of the rotor imbalance.

2. The method of claim 1, wherein determining blade load data includes determining blade load parameters associated with each selected rotor blade pair.

3. The method of claim 2, wherein determining blade load data further includes determining a difference in the blade load parameters associated with each selected rotor blade pair.

4. The method of claim 3, wherein the difference in blade load parameters between the selected rotor blade pair is provided by:

E[M_BA]−

E[M_BB]≈

k₂·

Δ

_AB·

E[(V·

(1−

α

))²+(rω

_r·

(1+α

′

))²]

5. The method of claim 1, wherein determining pitch imbalance data associated with the selected rotor blade pair is provided by:

6. The method of claim 1, including determining blade load data associated with two or more selected rotor blade pairs.

7. The method of claim 1, wherein determining blade load data includes acquiring a blade load data set associated with each blade of the selected rotor blade pair during conditions in which the rotor speed is substantially constant.

8. The method of claim 7, wherein the rotor speed is maintained within +/−

10% of a target speed.

9. The method of claim 7, wherein the rotor speed is maintained within +/−

5% of a target speed.

10. The method of claim 7, wherein determining blade load data includes acquiring a blade load data set associated with each blade of the selected rotor blade pair during conditions in which wind speed is substantially constant.

11. The method of claim 10, wherein the blade load data set us acquired during conditions in which wind speed is constant to within +/−

25%.

12. The method of claim 10, wherein the blade load data set is acquired during conditions in which wind speed is constant to within +/−

10%.

13. The method of claim 1, wherein determining blade load data includes acquiring a blade load data set whilst the respective blade is near to blade azimuth positions of 0°

and 180°

.

14. The method of claim 1, wherein determining blade load data includes acquiring a lade load data set whilst the respective blade has a pitch angle of substantially 0°

.

15. The method of claim 1, further including, before the step of determining and applying pitch control inputs, checking that the pitch imbalance data associated with the selected rotor blade pair exceeds a predetermined threshold.

16. The method of claim 1, further including:

i) determining blade load data associated with a selected rotor blade pair; and

ii) determining, based on the blade load data, pitch imbalance data associated with the selected rotor blade pair; and

iii) determining and applying pitch control inputs to one or both of the selected rotor blade pair in order to check that the severity of the rotor imbalance has been reduced.

17. A wind turbine system comprising a rotor having plurality of rotor blades, each of the rotor blades being equipped with blade load sensing means and a blade pitch control means, the system further comprising a controller configured to:

use the blade load sensing means to determine blade load data associated with a selected pair of the plurality of rotor blades;

determine, based on the blade load data, pitch imbalance data associated with the selected rotor blade pair, wherein the pitch imbalance data associated with a rotor blade pair is based on measurements of at least blade loading, rotor speed and wind speed; and

determine and apply pitch control inputs to the pitch control means of one or both of the selected rotor blade pair in order to reduce the severity of the rotor imbalance.