Reducing noise emissions of a wind turbine

A controller for reducing noise emissions of a wind turbine, the controller being configured to:

• receive data indicative of wind conditions in the vicinity of the wind turbine;
• determine an operational set point signal in accordance with a desired operation of the wind turbine, the operational set point signal being determined in dependence on the received data;
• apply a perturbation signal to the operational set point signal to obtain a modified operational set point signal;
• and,
• control operation of the wind turbine using the modified operational set point signal to reduce noise emissions of the wind turbine,
• wherein the perturbation signal is applied such that a signal characteristic has greater temporal variation in the modified operational set point signal than in the operational set point signal.

A wind turbine comprising:

• a tower;
• a nacelle disposed on the tower;
• and
• a controller, for reducing noise emissions of the wind turbine, the controller being configured to:
• receive data indicative of wind conditions in the vicinity of the wind turbine;
• determine an operational set point signal in accordance with a desired operation of the wind turbine, the operational set point signal being determined in dependence on the received data;
• apply a perturbation signal to the operational set point signal to obtain a modified operational set point signal;
• and
• control operation of the wind turbine using the modified operational set point signal to reduce noise emissions of the wind turbine,
• wherein the perturbation signal is applied such that a signal characteristic has greater temporal variation in the modified operational set point signal than in the operational set point signal.