Methods and apparatus for controlling wind turbines

A wind turbine, comprising:

• a nacelle;
• a plurality of wind turbine blades, rotatablely mounted to the nacelle by a main bearing;
• and
• a control system comprising a processor and a memory storage device including instructions that when executed by the processor enable the control system to:
• determine an actual loading of a wind turbine component of the wind turbine based on current wind conditions affecting the wind turbine component, wherein the wind turbine component is set to a first rotational path according to a first control strategy that sets individual pitch controls for all of the wind turbine blades of the wind turbine, wherein the first rotational path defines a first series of angles for the wind turbine component over a given rotation of the wind turbine blades around the main bearing of the wind turbine;
• calculate a corrected loading on the wind turbine component based on the current wind conditions and a second rotational path for the wind turbine component, wherein the second rotational path is set according to a second control strategy that sets a collective pitch control for all of the wind turbine blades and defines a second series of angles, different than the first series of angles, for the wind turbine component over the given rotation of the wind turbine blades around the main bearing of the wind turbine;
• calculate a damage index for the wind turbine component based on the corrected loading;
• and
• in response to determining that a pre-determined threshold exceeds the damage index, switch control of the wind turbine from the first control strategy to the second control strategy.

A computer-readable storage medium comprising instructions which, when executed by a processor performs an operation for controlling a wind turbine, the operation comprising:

• determining an actual loading of a wind turbine component of the wind turbine based on current wind conditions affecting the wind turbine component, wherein the wind turbine component is set to a first rotational path according to a first control strategy that sets individual pitch controls for all wind turbine blades of the wind turbine, wherein the first rotational path defines a first series of angles for the wind turbine component over a given rotation of wind turbine blades around a main bearing of the wind turbine;
• calculating a corrected loading on the wind turbine component based on the current wind conditions and a second rotational path for the wind turbine component, wherein the second rotational path is set according to a second control strategy that sets a collective pitch control for all of the wind turbine blades and defines a second series of angles, different than the first series of angles, for the wind turbine component over the given rotation of the wind turbine blades around the main bearing of the wind turbine;
• calculating a damage index for the wind turbine component based on the corrected loading;
• and
• in response to determining that a pre-determined threshold exceeds the damage index, switching control of the wind turbine from the first control strategy to the second control strategy.