Wind turbine blade deflection control system

• US 7,246,991 B2
• Filed: 09/23/2002
• Issued: 07/24/2007
• Est. Priority Date: 09/23/2002
• Status: Expired due to Fees

• Current Assignee: John Vanden Bosche
• Original Assignee: John Vanden Bosche
• Inventors: Bosche, John Vanden
• Primary Examiner(s): Look; Edward K.
• Assistant Examiner(s): White; Dwayne J
• Application Number:
  US10/253,134
• Publication Number:
  US 20040057828A1
• Time in Patent Office: 1,765 Days
• Field of Search: 415/14, 415/33, 415/118, 415/4.1, 415/132.B, 415/61, 415/31
• US Class Current: 415/14
• CPC Class Codes: F03D 7/0204 for orientation in relation to wind direction
• CPC Class Codes: F03D 7/0224 Adjusting blade pitch
• CPC Class Codes: F03D 7/0288 in relation to clearance between the blade and the tower, i.e. preventing tower strike
• CPC Class Codes: F03D 7/046 with learning or adaptive control, e.g. self-tuning, fuzzy logic or neural network
• CPC Class Codes: F05B 2270/17 to avoid excessive deflection of the blades
• CPC Class Codes: F05B 2270/33 Proximity of blade to tower
• CPC Class Codes: F05B 2270/707 fuzzy logic
• 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 wind turbine with a sensor that measures the out-of-plane deflection of the blades and a controller that uses the signal from the sensor to determine the risk of a tower strike. The controller takes any necessary action to prevent a tower strike when it determines that the risk of a strike is high. The sensor can include strain gages or accelerometers mounted on the blades or it can include a fixed sensor mounted on the side of the tower to measure tower clearance as the blade passes by. The control action taken can include pitching blades, yawing the nacelle, or stopping the turbine. The controller is preferably a fuzzy logic controller.

Claims

1. A wind turbine comprising:

a tower;

a rotor mounted on top of said tower with at least one blade that rotates about a substantially horizontal axis;

a sensor that measures the out-of-plane deflection of said blade; and

a controller that uses the out-of-plane deflection measurement from said sensor to determine a clearance between said blade and said tower wherein said controller performs a control action when there is a danger of said blade striking said tower to prevent said blade from striking said tower.

2. The wind turbine of claim 1 wherein said sensor further comprises a stationary sensor mounted on said tower to measure the clearance between said blade and said tower.

3. The wind turbine of claim 2 wherein said sensor is an ultrasonic sensor.

4. The wind turbine of claim 2 wherein said sensor is a laser sensor.

5. The wind turbine of claim 2 wherein said sensor is a radar sensor.

6. The wind turbine of claim 1 wherein said controller is a fuzzy logic controller.

7. The wind turbine of claim 1 wherein said wind turbine further comprises a mechanism for adjusting the pitch angle of said blade and wherein said control action includes changing said pitch angle.

8. The wind turbine of claim 1 wherein said wind turbine further comprises a yaw drive for orienting said rotor relative to the prevailing wind direction and wherein said control action includes activating said yaw drive to yaw said rotor out of the wind.

9. The wind turbine of claim 1 wherein said control action includes stopping said wind turbine.

10. A method of controlling a wind turbine comprising:

providing a tower;

providing a rotor on top of said tower with at least one blade that rotates about a substantially horizontal axis;

providing a sensor that measures the out-of-plane deflection of said blade wherein said sensor comprises an accelerometer affixed to said blade;

providing a controller that determines the level of risk of said blade striking said tower; and

performing a control action to prevent said blade from striking said tower.

11. A method of controlling a wind turbine comprising:

providing a tower;

providing a rotor on top of said tower with at least one blade that rotates about a substantially horizontal axis;

measuring the out-of-plane deflection of said blade using an accelerometer affixed to said blade;

inferring blade flapwise bending stress from blade out-of-plane deflection measurements; and

performing a control action as necessary to maintain blade flapwise bending stress within predetermined limits.