System and method for protecting wind turbines during extreme wind direction change

A system for protecting a wind turbine having a plurality of rotor blades from an extreme change in wind direction, the system comprising:

• one or more sensors configured to monitor at least one of wind direction or wind speed at the wind turbine;
• a controller communicatively coupled to the one or more sensors, the controller comprising one or more processors configured to perform one or more operations, the one or more operations comprising:
• receiving at least one of a wind direction or a wind speed at the wind turbine;
• when a change in the wind direction or the wind speed exceeds a predetermined threshold, determining a margin of at least one of the plurality of rotor blades to stall, and a margin of the at least one of the plurality of rotor blades to zero lift, at a blade span location of the at least one of the plurality of rotor blades at the at least one of a wind direction or a wind speed;
• determining an angle of attack that establishes both the margin to stall and the margin to zero lift at values that satisfy a predetermined stall margin and a predetermined margin to zero lift of the at least one of the plurality of rotor blades at the blade span location as a function of the wind direction, a tip speed ratio, and a structure twist;
• and
• without shutting down the wind turbine, modulating the angle of attack at the blade span location by pitching the at least one of the plurality of rotor blades and reducing a rotor speed of the wind turbine to prevent stall and zero lift from occurring on the at least one of the plurality of rotor blades during operation of the wind turbine.