System and method for operating a wind turbine based on rotor blade margin

1. A method for operating a wind turbine, the method comprising:

calculating, via a processor, one or more blade root resultant moments of at least one rotor blade of the wind turbine as a function of a tip speed ratio and a pitch angle of the rotor blade;

estimating, via the processor, a span-wise loading of the rotor blade based on the one or more blade root resultant moments;

determining, via the processor, a deformation margin of the rotor blade based at least partially on the span-wise loading and one or more real-time deformations occurring on the rotor blade; and

controlling, via the processor, the wind turbine based on the deformation margin.

2. The method of claim 1 , wherein calculating the one or more blade root resultant moments of at least one rotor blade of the wind turbine further comprises:

measuring, via one or more sensors, a plurality of operating parameters of the wind turbine;

estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters;

determining an application point of the out-of-plane and in-plane force on a span of the rotor blade;

estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point;

estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and,

calculating the one or more blade root resultant moments acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment.

3. The method of claim 1 , wherein estimating the span-wise loading of the rotor blade based on the one or more blade root resultant moments further comprises:

determining a real-time operating point of the wind turbine;

determining corresponding curve fit coefficients based on the operating point;

generating a non-dimensional load shape curve based on the coefficients offline; and

scaling the non-dimensional load shape curve up or down based on the one or more blade root resultant moments to create a dimensional curve online.

4. The method of claim 1 , further comprising storing, via a memory device, at least one of the one or more blade root resultant moments, the span-wise loading, or the deformation margin.

5. The method of claim 1 , wherein determining the deformation margin of the rotor blade further comprises:

applying a predetermined load distribution to the rotor blade;

measuring one or more corresponding margins in response to the predetermined load distribution; and

storing the measured corresponding margins in at least one of a map or look-up-table.

6. The method of claim 5 , wherein determining the deformation margin of the rotor blade further comprises:

determining an actual load distribution of the rotor blade in real-time; and

scaling the measured corresponding margins based on the actual load distribution.

7. The method of claim 1 , wherein the one or more real-time deformations comprise at least one of a strain deformation or a buckling deformation.

8. The method of claim 1 , wherein controlling the wind turbine based on the deformation margin further comprises determining a control parameter based on at least one of a maximum deformation or the deformation margin.

9. The method of claim 8 , further comprising calculating a deformation error as a function of the control parameter and a predetermined threshold and implementing a corrective action based on the error.

10. The method of claim 9 , wherein the corrective action comprises at least one of altering the pitch angle of a rotor blade, modifying a generator torque, modifying the generator speed, modifying the power output, yawing a nacelle of the wind turbine, braking one or more wind turbine components, or activating an airflow modifying element on a rotor blade.

11. A method for controlling loads of a rotor blade of a wind turbine, the method comprising:

storing a predetermined deformation margin for the rotor blade in a processor of a controller of the wind turbine;

calculating, via the processor, a blade root load of the rotor blade as a function of a tip speed ratio and a pitch angle of the rotor blade;

determining, via the processor, a span-wise loading of the rotor blade based at least partially on the blade root load;

updating, via the processor, the predetermined deformation margin based at least partially on the span-wise loading or one or more real-time deformations occurring on the rotor blade; and,

implementing a corrective action based on the deformation margin.

12. A system for operating a wind turbine, the system comprising:

a controller comprising a processor configured to perform one or more operations, the one or more operations comprising:

calculating one or more blade root resultant moments of at least one rotor blade of the wind turbine as a function of a tip speed ratio and a pitch angle of the rotor blade;

estimating a span-wise loading of the rotor blade based at least partially on the one or more blade root resultant moments;

determining a deformation margin of the rotor blade based at least partially on the span-wise loading and one or more estimated deformations occurring on the rotor blade; and

controlling the wind turbine based on the deformation margin.

13. The system of claim 12 , wherein calculating the one or more blade root resultant moments of at least one rotor blade of the wind turbine further comprises:

measuring, via one or more sensors, a plurality of operating parameters of the wind turbine;

estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters;

determining an application point of the out-of-plane and in-plane force on a span of the rotor blade;

estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point;

estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and

calculating the one or more blade root resultant moments acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment.

14. The system of claim 12 , wherein estimating span-wise loading of the rotor blade based on the one or more blade root resultant moments further comprises:

determining a real-time operating point of the wind turbine;

determining corresponding curve fit coefficients based on the operating point;

generating a non-dimensional load shape curve based on the coefficients offline; and

scaling the non-dimensional load shape curve up or down based on the one or more blade root resultant moments to create a dimensional curve online.

15. The system of claim 12 , wherein determining the deformation margin of the rotor blade further comprises:

applying a predetermined load distribution to the rotor blade;

measuring one or more corresponding margins in response to the predetermined load distribution; and

storing the measured corresponding margins in at least one of a map or look-up-table.

16. The system of claim 15 , wherein determining the deformation margin of the rotor blade further comprises:

determining an actual load distribution of the rotor blade in real-time; and

scaling the measured corresponding margins based on the actual load distribution.

17. The system of claim 12 , wherein the one or more deformations comprise at least one of a strain deformation or a buckling deformation.

18. The system of claim 12 , wherein controlling the wind turbine based on the deformation margin further comprises determining a control parameter based on at least one of a maximum deformation or the deformation margin, calculating a deformation error as a function of the control parameter and a predetermined threshold, and implementing a corrective action based on the error.