Controlling wind turbine based on rain drop size

A computer program product comprising a non-transitory computer readable medium having instructions which, when executed by one or more processors cause a control system for a wind turbine having a rotor with one or more blades to perform an operation;

• wherein the wind turbine has a rated angular rotation speed of the rotor;
• wherein the operation comprises:
• providing an estimated drop size of rain drops impinging on the one or more blades,
• determining whether an entry criterion for operation according to a reduced mode is fulfilled, wherein said determining is based at least partially on the estimated drop size, and
• controlling the wind turbine according to the reduced mode upon determining that the entry criterion is fulfilled, wherein in the reduced mode an angular rotation speed of the rotor is limited below an angular rotation speed threshold, and wherein the angular rotation speed threshold is smaller than the rated angular rotation speed of the wind turbine.

A wind turbine, comprising:

• a tower;
• a nacelle disposed on the tower;
• a rotor extending from the nacelle, the wind turbine has a rated angular rotation speed of the rotor;
• a plurality of blades disposed on an end of the nacelle;
• and
• a control system configured to:
• provide an estimated drop size of rain drops impinging on the plurality of blades,
• determine whether an entry criterion for operation according to a reduced mode is fulfilled, wherein said determining is based at least partially on the estimated drop size, and
• control the wind turbine according to the reduced mode upon determining that the entry criterion is fulfilled, wherein in the reduced mode an angular rotation speed of the rotor is limited below an angular rotation speed threshold, and wherein the angular rotation speed threshold is smaller than the rated angular rotation speed of the wind turbine.

A method for controlling a wind turbine, wherein the wind turbine comprises a wind turbine rotor with one or more blades, wherein the wind turbine has a rated angular rotation speed of the wind turbine rotor;

• the method comprising:
• providing an estimated aerial particle size of aerial particles impinging on the one or more blades,
• determining whether an entry criterion for operation according to a reduced mode is fulfilled, wherein said determining is based at least partially on the estimated aerial particle size, and
• controlling the wind turbine according to the reduced mode upon determining that the entry criterion is fulfilled, wherein in the reduced mode an angular rotation speed of the wind turbine rotor is limited below an angular rotation speed threshold, wherein the angular rotation speed threshold is smaller than the rated angular rotation speed of the wind turbine.