System and method for controlling a wind turbine based on identified surface conditions of the rotor blades

1. A method for controlling a wind turbine based on an identified surface condition of a rotor blade of the wind turbine, the method comprising:

actively adjusting an operating input of the wind turbine over time;

monitoring an operating parameter of the wind turbine to obtain parameter data related to the operating parameter as the operating input is being actively adjusted;

comparing the parameter data to predetermined parameter data for the operating parameter to identify variations in a dynamic response of the operating parameter over time to changes in the operating input;

determining that a change in a surface roughness of the rotor blade has occurred based on the identified variations in the dynamic response of the operating parameter;

adjusting at least one of a pitch angle or a tip speed ratio of the rotor blade when it has been determined that the change in the surface roughness of the rotor blade exceeds a predetermined threshold account for the change in the surface roughness of the rotor blade; and

maintaining the adjustment made to the at least one of the pitch angle or the tip speed ratio as the wind turbine continues to be operated so as to recover over time at least a portion of a reduction in an aerodynamic efficiency caused by the change in the surface roughness of the rotor blade.

2. The method of claim 1 , wherein the operating input comprises at least one of pitch angle, yaw angle, generator speed or generator torque.

3. The method of claim 1 , wherein the operating parameter comprises at least one of shaft bending, blade bending, tower bending, power output, generator speed, generator torque, component vibration or blade noise.

4. The method of claim 1 , wherein the predetermined parameter data corresponds to clean parameter data previously collected for the operating parameter while the operating input was being actively adjusted.

5. The method of claim 4 , wherein determining that the change in the surface roughness has occurred comprises determining that the change in the surface roughness has occurred when the dynamic response of the operating parameter as provided within the parameter data differs from the dynamic response of the operating parameter as provided within the clean parameter data by at least the predetermined threshold.

6. The method of claim 4 , wherein determining that the change in the surface roughness has occurred comprises:

analyzing the parameter data to establish a current trend line for the parameter data;

analyzing the clean parameter data to establish a clean trend line for the clean parameter data; and

comparing the current trend line to the clean trend line to identify the variations in the dynamic response of the operating parameter over time to changes in the operating input.

7. The method of claim 1 , wherein adjusting the at least one of the pitch angle or the tip speed ratio of the rotor blade comprises adjusting the tip speed ratio when it has been determined that the change in the surface roughness of the rotor blade exceeds the predetermined threshold.

8. The method of claim 1 , further comprising supplementing the parameter data with surface condition data obtained using a surface roughness sensor in order to determine that the change in the surface roughness of the rotor blade has occurred.

9. A system for controlling a wind turbine based on an identified surface condition of a rotor blade of the wind turbine, the system comprising:

a controller including at least one processor and associated memory, the memory storing instructions that, when implemented by the at least one processor, configured the controller to:

actively adjust an operating input of the wind turbine over time;

monitor an operating parameter of the wind turbine to obtain parameter data related to the operating parameter as the operating input is being actively adjusted;

compare the parameter data to predetermined parameter data for the operating parameter to identify variations in a dynamic response of the operating parameter over time to changes in the operating input;

determine that a change in a surface roughness of the rotor blade has occurred based on the identified variations in the dynamic response of the operating parameter;

adjust at least one of a pitch angle or a tip speed ratio of the rotor blade when it has been determined that the change in the surface roughness of the rotor blade exceeds a predetermined threshold to account for the change in the surface roughness of the rotor blade; and

maintain the adjustment made to the at least one of the pitch angle or the tip speed ratio as the wind turbine continues to be operated so as to recover over time at least a portion of a reduction in an aerodynamic efficiency caused by the change in the surface roughness of the rotor blade.

10. The system of claim 9 , wherein the operating input comprises at least one of pitch angle, yaw angle, generator speed or generator torque.

11. The system of claim 9 , wherein the operating parameter comprises at least one of shaft bending, blade bending, tower bending, power output, generator speed, generator torque, component vibration or blade noise.

12. The system of claim 9 , wherein the predetermined parameter data corresponds to clean parameter data previously collected for the operating parameter while the operating input was being actively adjusted.

13. The system of claim 12 , wherein the controller is configured to determine that the change in surface roughness has occurred when the dynamic response of the operating parameter as provided within the parameter data differs from the dynamic response of the operating parameter as provided within the clean parameter data by at least the predetermined threshold.

14. The system of claim 9 , wherein the controller is configured to adjust the tip speed ratio of the rotor blade when it has been determined that the change in the surface roughness of the rotor blade exceeds the predetermined threshold.

15. The system of claim 9 , further comprising a surface roughness sensor configured to directly monitor the surface roughness of the rotor blade, the controller being communicatively coupled to the surface roughness sensor, the controller configured to supplement the parameter data with surface condition data obtained from surface roughness sensor in order to determine that the change in the surface roughness of the rotor blade has occurred.

16. The system of claim 12 , wherein the controller is configured to determine that the change in surface roughness has occurred by comparing a current trend line associated with the parameter data to a clean trend line associated with the clean parameter data to identify the variations in the dynamic response of the operating parameter over time to changes in the operating input.

17. The system of claim 9 , wherein the controller is configured to adjust the pitch angle of the rotor blade when it has been determined that the change in the surface roughness of the rotor blade exceeds the predetermined threshold.

18. The method of claim 1 , wherein adjusting the at least one of the pitch angle or the tip speed ratio of the rotor blade comprises adjusting the pitch angle when it has been determined that the change in the surface roughness of the rotor blade exceeds the predetermined threshold.