Wind turbine coupling to mitigate torque reversals

1. A method of providing torsional damping in a wind turbine drive system for a generator to reduce the magnitude and rapidity of torque reversals, and mitigate the resulting damaging impact loads on wind turbine drive system components, comprising:

detecting a wind turbine drive system torque reversal exceeding a first preset threshold;

dissipating torsional wind-up energy in the wind turbine drive system while maintaining said reverse torque at said first preset threshold;

detecting a positive torque exceeding a second preset threshold;

returning the wind turbine drive system to forward operation; wherein detecting a wind turbine drive system torque reversal and dissipating torsional wind-up energy are achieved automatically by frictional slipping and

wherein an angle of torsional displacement of said wind turbine drive system is sufficient to cause said frictional slipping to effectively reduce the magnitude of reverse torque and slow a rate of torque reversal magnitude increase, and wherein said generator operates at speeds greater than 1000 rpm and said angle of torsional displacement exceeds 10 degrees.

2. The method as recited in claim 1 , which allows said wind turbine drive system to operate in a forward direction producing electric power through said generator without affecting the system's forward operation, while providing torsional damping in a reverse direction.

3. The method as recited in claim 2 , wherein said first preset threshold is set at less than 100% of a turbine torque at a power rating of the generator.

4. The method as recited in claim 1 , wherein said first and second preset thresholds are the same.

5. The method as recited in claim 1 , wherein said frictional slipping is in parallel with torsional springs that deflect during normal forward operation such that a torque load in the turbine generator drive system is shared by both frictional slippage and spring deflection.

6. The method as recited in claim 5 , wherein said torsional springs have a zero torque load deadband for at least a portion of a torsional displacement movement during a torque reversal.

7. A method of providing torsional damping in a wind turbine drive system for a generator to reduce the magnitude and rapidity of torque reversals, and mitigate the resulting damaging impact loads on wind turbine drive system components, comprising:

detecting a drive system torque reversal exceeding a first preset threshold;

dissipating torsional wind-up energy in the wind turbine drive system while maintaining said reverse torque at said first preset threshold;

detecting a positive torque exceeding a second preset threshold;

returning the turbine drive system to forward operation; and

wherein said first preset threshold is set at less than 100% of the turbine torque at a power rating of the generator, wherein detecting a wind turbine drive system torque reversal and dissipating torsional wind-up energy are achieved automatically by frictional slipping, and said generator operates at speeds under 1000 rpm, and said angle of torsional displacement exceeds 1 degree per 100 rpm.

8. The method as recited in claim 7 , wherein a frictional slipping threshold is set at between 20% and 80% of rated turbine operating torque.

9. A method of providing torsional damping in a wind turbine drive system for a generator to reduce the magnitude and rapidity of torque reversals, and mitigate the resulting damaging impact loads on wind turbine drive system components, comprising:

detecting a wind turbine drive system torque reversal exceeding a first preset threshold;

dissipating torsional wind-up energy in the drive system while maintaining said reverse torque at said first preset threshold;

detecting a positive torque exceeding a second preset threshold;

returning the turbine drive system to forward operation; wherein detecting a wind turbine drive system torque reversal and dissipating torsional wind-up energy are achieved automatically by frictional slipping and

wherein said frictional slipping is in parallel with torsional springs that deflect during normal forward operation such that a torque load in the turbine generator drive system is shared by both torsional spring deflection and said frictional slipping, and said torsional springs have a zero torque load deadband for at least a portion of a torsional displacement movement during a torque reversal.

10. The method as recited in claim 9 , wherein the frictional slipping provides hysteresis damping to a winding up and unwinding of the wind turbine drive system components.

11. The method as recited in claim 9 , wherein said generator operates at speeds above 1000 rpm and said zero torque deadband of the torsional displacement exceeds 10 degrees.

12. The method as recited in claim 9 , wherein said generator operates at speeds below 1000 rpm and said zero torque deadband of the torsional displacement exceeds 1 degree per 100 rpm.

13. The method as recited in claim 9 , wherein a reverse torsional spring deflection action occurs at an end of the deadband movement.

14. The method as recited in claim 13 , wherein said reverse torsional spring deflection action is symmetric to a forward torsional spring deflection action thus achieving bidirectional operation of said wind turbine drive system.

15. The method as recited in claim 14 , wherein a total torsional spring deflection action of said forward and reverse torsional spring deflection actions and zero torque deadband exceeds 10 degrees for wind turbines with generator operating speed exceeding 1000 rpm.

16. The method as recited in claim 14 , wherein said total torsional spring deflection and zero torque action deadband exceeds 1 degree per 100 rpm for wind turbines with said generator operating speed under 1000 rpm.