Method for controlling a wind power installation

A method for controlling a wind power installation,

• wherein the wind power installation includes:
• an aerodynamic rotor operable at a rotational speed that is variable and having rotor blades with adjustable blade angles, and
• wherein the method comprises:
• controlling the wind power installation in a partial-load range using open-loop operating-characteristic control, wherein:
• the open-loop operating-characteristic control uses an operating characteristic that sets a relationship between the rotational speed and a generator state variable,
• the generator state variable is a generator power or a generator torque, and
• controlling the wind power installation using the operating-characteristic control includes setting the generator state variable using the operating characteristic and depending on a detected rotational speed;
• controlling the wind power installation in a full-load range using closed-loop pitch control, in which the rotational speed is controlled to a speed setpoint value, by adjusting the blade angles;
• and
• in at least one speed range of the partial-load range and/or in a transitional range from the partial-load range to the full-load range, controlling the wind power installation using speed-power control, in which the rotational speed is controlled to a speed setpoint value, by adjusting the generator state variable, wherein the speed-power control includes an outer cascade and an inner cascade, wherein:
• in the outer cascade, a first closed-loop controller compares a setpoint speed with the detected rotational speed and determines a first acceleration setpoint value of the rotor based on comparing the setpoint speed with the detected rotational speed, and
• in an inner cascade, a second closed-loop controller compares the first acceleration setpoint value with a detected acceleration value of the rotor and determines a generator setpoint value for the generator state variable based on comparing the first acceleration setpoint value with the detected acceleration value.