Ice detection based on anemometry

A method for calibrating an ice detection unit, comprising:

• measuring a data set of a first anemometer for a period and under a condition during which icing may not occur, wherein the first anemometer being of a first type;
• measuring a data set of a second anemometer corresponding to the period, wherein the second anemometer being of a second type, and wherein the second type is different from the first type;
• defining a functional interrelation between the first data set and the second data set;
• and
• defining a limit value determining a deviation threshold to indicate an icing condition flag.

An ice detection unit for a wind turbine, comprising:

• a first anemometer of a first type;
• a second anemometer of a second type, wherein the second type is different from the first type, and wherein the second anemometer is heatable to reduce affection of the second anemometer by ice;
• a temperature sensor adapted for measuring an ice condition threshold parameter to distinguish a condition during which icing may occur and a condition during which icing may not occur;
• and
• an evaluation unit configured to evaluate a functional relationship between a signal from the first anemometer and a signal from the second anemometer.