Estimating an upgraded power curve

A method of estimating a second power curve of a wind turbine regarding a second operational configuration, the method comprising:

• receiving power output data (a, b, pertaining to a first operational configuration;
• receiving power data-relating to power output pertaining to the second operational configuration;
• deriving the second power curve-using the power output data fab pertaining to the first operational configuration, the power output data pertaining to the second operational configuration and a first power curve of the first operational configuration, wherein receiving power data relating to a power output pertaining to the second operational configuration comprises:
• receiving power data relating to a power output of at least one first wind turbine operated according to the second operational configuration in a first time interval;
• receiving power output data pertaining to the first operational configuration comprises:
• receiving power data b relating to a power output of at least one second wind turbine operated according to the first operational configuration in the first time interval, the method further comprising:
• receiving power data relating to a power output of the first wind turbine operated according to the first operational configuration in a second time interval,
• receiving power data relating to a power output of the second wind turbine operated according to the second operational configuration in the second time interval;
• wherein deriving the second power curve is based on:
• the power data relating to a power output of the first wind turbine operated according to the second operational configuration in the first time interval;
• the power data-relating to a power output of the second wind turbine operated according to the first operational configuration in the first time interval,
• the power data relating to a power output of the first wind turbine operated according to the first operational configuration in the second time interval;
• the power data relating to a power output of the second wind turbine operated according to the second operational configuration in the second time interval;
• and
• the first power curve,
• wherein the first wind turbine and the second wind turbine are operated at the same time interval always in different operational configurations, wherein deriving the second power curve comprises:
• deriving a first estimate of the second power curve employing a calculation scheme,
• the calculation scheme having as a first input the power data relating to power output of the first wind turbine operated according to the second operational configuration in the first time interval;
• the calculation scheme having as a second input the power data relating to power output of the second wind turbine operated according to the first operational configuration in the first time interval,
• wherein the calculation scheme further uses the first power curve, to derive the first estimate of the second power curve,
• wherein the second power curve is derived further based on the first estimate of the second power curve,
• wherein the calculation scheme derives a difference between data supplied to the first input and data supplied to the second input.