Control of a wind turbine during recovery after a grid fault

A control system for a wind turbine, the control system comprises at least one processor for:

• detecting a fault of the utility grid;
• controlling one or more rotor blades in a fault mode;
• detecting a recovery of the utility grid;
• and
• controlling, during a recovery period, one or more of the rotor blades in a recovery mode, wherein the recovery mode comprises:
• determining an actual pitch angle of each of the rotor blades;
• determining an actual wind speed;
• determining a desired pitch angle of each of the rotor blades according to the actual wind speed;
• determining a pitch ramp rate of each of the rotor blades so that the actual pitch angle matches the respective desired pitch angle before an end of the recovery period, and
• ramping the pitch angle of each of the rotor blades with the respective determined pitch ramp rate.

A wind turbine comprising a control system wherein the control system comprises at least one processor configured to perform an operation comprising:

• detecting a fault of the utility grid;
• controlling one or more rotor blades in a fault mode;
• detecting a recovery of the utility grid;
• and
• controlling, during a recovery period, one or more of the rotor blades in a recovery mode, wherein the recovery mode comprises:
• determining an actual pitch angle of each of the rotor blades;
• determining an actual wind speed;
• determining a desired pitch angle of each of the rotor blades according to the actual wind speed;
• determining a pitch ramp rate of each of the rotor blades so that the actual pitch angle matches the respective desired pitch angle before an end of the recovery period, and
• ramping the pitch angle of each of the rotor blades with the respective determined pitch ramp rate.

A computer program product comprising software code adapted to control a wind turbine when executed on a data processing system, the computer program product being adapted to control the wind turbine according to an operation comprising:

• entering a fault mode in response to detecting a fault of the utility grid;
• controlling one or more rotor blades of the wind turbine in the fault mode;
• detecting a recovery of the utility grid;
• and
• controlling, during a recovery period, one or more of the rotor blades in a recovery mode, wherein the recovery mode comprises:
• determining an actual pitch angle of each of the rotor blades;
• determining an actual wind speed;
• determining a desired pitch angle of each of the rotor blades according to the actual wind speed;
• determining a pitch ramp rate of each of the rotor blades so that the actual pitch angles match the respective desired pitch angle before the end of the recovery period, and
• ramping the pitch angle of each of the rotor blades with the respective determined pitch ramp rate.