Method for Calibrating a Measuring Device of a Wind Turbine

A wind power installation configured to calibrate a measuring device for measuring a load of a rotor blade of the wind power installation, wherein the wind power installation has a rotor with a rotor axis and a plurality of rotor blades with an adjustable blade angle, wherein the wind power installation is configured to:

• for one rotor blade at a time,
• record a sensor value of a load sensor,
• determine at least one conversion factor for converting the sensor value into a load value acting on the rotor blade in an area of a blade root of the rotor blade, wherein
• the conversion factor is determined from a relationship between the sensor value and a comparative force acting on the rotor blade,
• the comparative force is determined as a function of a weight force acting on the rotor blade, and
• a function of a correction component that takes into account a deviation between the comparative force and the weight force.