Methods and apparatus for rotor blade ice detection

• US 20050276696A1
• Filed: 06/10/2004
• Published: 12/15/2005
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: LeMieux, David Lawrence
• Granted Patent: US 7,086,834 B2
• Time in Patent Office: Days
• US Class Current: 416/61
• CPC Class Codes: F03D 7/02 the wind motors having rotation axis substantially parallel to the air flow entering the rotor
• CPC Class Codes: F03D 80/40 Ice detection; De-icing means
• CPC Class Codes: F05B 2270/32 Wind speeds
• CPC Class Codes: F05B 2270/80 Devices generating input signals, e.g. transducers, sensors, cameras or strain gauges
• CPC Class Codes: F05B 2270/804 Optical devices
• CPC Class Codes: F05B 2270/808 Strain gauges; Load cells
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

A method for detecting ice on a wind turbine having a rotor and one or more rotor blades each having blade roots includes monitoring meteorological conditions relating to icing conditions and monitoring one or more physical characteristics of the wind turbine in operation that vary in accordance with at least one of the mass of the one or more rotor blades or a mass imbalance between the rotor blades. The method also includes using the one or more monitored physical characteristics to determine whether a blade mass anomaly exists, determining whether the monitored meteorological conditions are consistent with blade icing; and signaling an icing-related blade mass anomaly when a blade mass anomaly is determined to exist and the monitored meteorological conditions are determined to be consistent with icing.

Claims

1. A method for detecting ice on a wind turbine having a rotor and one or more rotor blades each having blade roots, said method comprising:

monitoring meteorological conditions relating to icing conditions;

monitoring one or more physical characteristics of the wind turbine in operation that vary in accordance with at least one of the mass of the one or more rotor blades or a mass imbalance between the rotor blades;

using the one or more monitored physical characteristics to determine whether a blade mass anomaly exists;

determining whether the monitored meteorological conditions are consistent with blade icing; and

signaling an icing-related blade mass anomaly when a blade mass anomaly is determined to exist and the monitored meteorological conditions are determined to be consistent with icing.

2. A method in accordance with claim 1 wherein the rotor has a plurality of blades and the blade mass anomaly is a blade mass imbalance.

3. A method in accordance with claim 1 wherein the blade mass anomaly is a blade mass change.

4. A method in accordance with claim 1 further comprising monitoring yaw error, and wherein said signaling an icing related blade mass anomaly is further conditioned on the monitored yaw error being near zero.

5. A method in accordance with claim 1 further comprising monitoring yaw error, iterating said monitoring of the one or more physical characteristics of the wind turbine until the one or more physical characteristics are monitored with yaw error near zero, and said using the one or more monitored physical characteristics to determine whether a blade mass anomaly exists comprises using the physical characteristics monitored when the yaw error is near zero.

6. A method in accordance with claim 4 further comprising monitoring yaw error, correcting the yaw error, repeating said monitoring of one or more physical characteristics of the wind turbine with the yaw error corrected, and said using the one or more monitored physical characteristics to determine whether a blade mass anomaly exists comprises using the physical characteristics monitored with the yaw error corrected.

7. A method in accordance with claim 1 wherein the one or more physical characteristics of the wind turbine include rotor speed and acceleration.

8. A method in accordance with claim 1 wherein the one or more physical characteristics of the wind turbine include changes in bending moments.

9. A method in accordance with claim 1 wherein the one or more physical characteristics of the wind turbine include changes in at least one of mechanical torque or electrical torque.

10. A method in accordance with claim 1 wherein the one or more physical characteristics of the wind turbine include changes in rotor speed and acceleration.

11. A method in accordance with claim 1 wherein said monitoring one or more physical characteristics includes monitoring changes in pitch motor actuator response.

12. A method in accordance with claim 1 wherein said monitoring one or more physical characteristics includes monitoring acoustic properties of each blade.

13. A method in accordance with claim 1 wherein the blade mass anomaly is a blade mass change, and said monitoring one or more physical characteristics includes monitoring acoustic properties of a tower on which the wind turbine stands.

14. A method in accordance with claim 1 wherein the blade mass anomaly is a blade mass change, said monitoring one or more physical characteristics includes monitoring a system load of the wind turbine, and further wherein said using the one or more monitored physical characteristics to determine whether a blade mass anomaly exists comprises comparing the monitored system load to previously monitored system loads monitored under non-icing conditions with known wind conditions.

15. A method in accordance with claim 1 wherein the blade mass anomaly is a blade mass imbalance, said monitoring one or more physical characteristics includes monitoring oscillatory deviations of output power from the wind turbine.

16. A method in accordance with claim 1 further comprising signaling ice shedding when short-term transients are observed in the one or more monitored physical characteristics.

17. A method for detecting ice on a wind turbine having a rotor and one or more rotor blades each having blade roots, said method comprising:

monitoring meteorological conditions relating to icing conditions;

monitoring one or more physical characteristics of the wind turbine in operation, said physical characteristics including at least blade root bending moments, that vary in accordance with at least one of the mass of the one or more rotor blades or a mass imbalance between the rotor blades;

using the one or more monitored physical characteristics to determine whether a blade mass anomaly exists;

determining whether the monitored meteorological conditions are consistent with blade icing; and

signaling an icing-related blade mass anomaly when a blade mass anomaly is determined to exist and the monitored meteorological conditions are determined to be consistent with icing.

18. A method in accordance with claim 17 further comprising filtering wind shear signals from the monitored blade root bending moments to produce filtered blade root bending moments, and wherein said using the one or more monitored physical characteristics to determine whether a blade mass anomaly exists comprises using the filtered blade root bending moments.

19. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring a signal from a strain sensing apparatus affixed or embedded in a rotor blades.

20. A method in accordance with claim 19 wherein the strain sensing apparatus is a strain gauge.

21. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring deflections of a hub of the rotor at either a shaft or a shaft flange at or near connection of the shaft flange to the hub.

22. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring strain in a hub of the rotor, a shaft, or a shaft flange at or near connection of the shaft flange to the hub.

23. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring blade root bending moments utilizing optical fibers having Bragg gratings embedded in the one or more rotor blades.

24. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring strain information obtained from instrumented T-bolts attaching a rotor blade to a hub of the rotor.

25. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring deviations in a motion vector of a gear box of the wind turbine.

26. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring bending moments at a plurality of locations in a span of the one or more rotor blades, and said using the one or more physical characteristics comprises using the monitored bending moments the plurality of locations to identify locations of possible icing.

27. A method in accordance with claim 17 wherein said monitoring one or more physical characteristics includes monitoring radial bending of a main shaft of the wind turbine.

28. A wind turbine comprising:

a rotor having one or more rotor blades;

one or more meteorological sensors configured to monitor meteorological conditions relating to icing;

one or more physical characteristic sensors configured to monitor one or more physical characteristics of the wind turbine in operation that vary in accordance with at least one of a mass of said one or more rotor blades or a mass imbalance between said rotor blades; and

a processor operably coupled to said one or more meteorological sensors and said one or more physical characteristic sensors, said processor configured to;

determine whether the monitored meteorological conditions are consistent with blade icing;

use the one or more monitored physical characteristics to determine whether a blade mass anomaly exists; and

generate a signal indicating an icing-related blade anomaly when the existence of a blade mass anomaly is determined and the monitored meteorological conditions are determined to be consistent with icing.

29. A wind turbine in accordance with claim 28 wherein said one or more physical characteristic sensors include at least one sensor configured to monitor blade azimuth position and at least one sensor configured to monitor rotor rotation speed.

30. A wind turbine in accordance with claim 28 wherein said computer is configured to monitor system loads of said wind turbine to previously monitored system loads monitored under non-icing conditions with known wind conditions.

31. A wind turbine in accordance with claim 28 wherein said one or more physical characteristic sensors comprise a plurality of sensors configured to monitor blade root bending located at different locations on spans of the rotor blades.

32. A wind turbine in accordance with claim 28 configured to identify locations of possible icing.

33. A wind turbine comprising:

a rotor having one or more rotor blades;

one or more meteorological sensors configured to monitor meteorological conditions relating to icing;

one or more physical characteristic sensors configured to monitor one or more physical characteristics of the wind turbine in operation that vary in accordance with at least one of a mass of said one or more rotor blades or a mass imbalance between said rotor blades, said physical characteristic sensors including at least one sensor that monitors blade root bending moments, and

a processor operably coupled to said one or more meteorological sensors and said one or more physical characteristic sensors, said processor configured to;

determine whether the monitored meteorological conditions are consistent with blade icing;

use the one or more monitored physical characteristics to determine whether a blade mass anomaly exists; and

generate a signal indicating an icing-related blade anomaly when the existence of a blade mass anomaly is determined and the monitored meteorological conditions are determined to be consistent with icing.

34. A wind turbine in accordance with claim 33 wherein said sensors configured to monitor blade root bending moments comprise strain measuring devices embedded in or affixed to said rotor blades.

35. A wind turbine in accordance with claim 33 wherein said strain measuring devices comprise strain gauges.

36. A wind turbine in accordance with claim 33 wherein said wind turbine further comprises a rotor hub, and said sensors configured to monitor blade root bending moments comprise one or more sensors configured to monitor deflections of said rotor hub.

37. A wind turbine in accordance with claim 33 wherein said wind turbine further comprises a main shaft, and wherein said sensors configured to monitor blade root bending moments comprise sensors configured to monitor a radial displacement of said shaft.

38. A wind turbine in accordance with claim 33 wherein said sensors configured to monitor blade root bending moments comprise optical fibers with Bragg gratings, and at least one said optical fiber is embedded in a blade root of each said rotor blade.

39. A wind turbine in accordance with claim 33 wherein said wind turbine further comprises a nacelle having a frame and said rotor further comprises a hub, and said sensors configured to monitor blade root bending moments comprise instrumenting T-bolts attaching said rotor blades to said hub.

40. A wind turbine in accordance with claim 33 wherein said wind turbine further comprises a gear box, and said sensors configured to monitor blade root bending moments comprise proximity probes configured to monitor gear box motion in a vertical plane and in a horizontal plane.

41. A wind turbine in accordance with claim 33 wherein said sensors configured to monitor blade bending moments comprise sensors configured to monitor deviations in a motion vector of a gear box of the wind turbine.

42. A wind turbine comprising a rotor having at least one blade, a nacelle, and a yaw control system, said wind turbine configured to yaw the nacelle and to signal a blade mass imbalance when a variable gyroscopic load is detected when the nacelle is yawed.

43. A method for detecting a blade mass imbalance comprising yawing a nacelle of a wind turbine and signaling a blade mass imbalance when a variable gyroscopic load is detected when the nacelle is yawed.

44. A wind turbine comprising a rotor having at least one blade, a pitch system, a turbine controller, and meteorological instrumentation configured to measure wind speed, said controller configured to signal a blade mass anomaly when said blades are pitched outside of a predetermined nominal range for a measured wind speed.

45. A method for detecting a blade mass anomaly on a wind turbine having at least one blade, a pitch system, and meteorological instrumentation configured to measure wind speed, said method comprising measuring a wind speed using the meteorological instrumentation, comparing a pitch of the blades to a predetermined nominal range for the measured wind speed, and signaling a blade mass anomaly when the blades are pitched outside of the predetermined nominal range for the measured wind speed.