Method for the operation of a wind energy plant

1. A method for the operation of a wind energy plant, the wind energy plant comprising a control system which can preset a desired value for an electric variable of the wind energy plant to be generated; and a control unit, on which the measured values for the wind velocity and the wind direction are present, the method comprising:

providing a wind measurement device for measuring a direction of wind and a wind velocity;

providing at least one sector of critical wind directions to the control unit,

determining if the measured direction of wind falls within the at least one sector of critical wind directions provided to the control unit;

generating a control signal only when the measured wind direction is in one of the at least one sector of the critical wind directions and a determined characteristic value exceeds a predetermined maximum value for the characteristic value, the control unit providing the control signal to the control system in order to reduce the desired value of the electric variable to be generated.

2. The method according to claim 1 , characterized in that the characteristic value is determined depending on the measured wind velocity and/or on a controller's activity.

3. The method according to claim 2 , characterized in that the controller's activity of a pitch controller is detected for determining the characteristic value.

4. The method according to claim 1 , characterized in that the at least one sector of critical wind directions of the control unit are preset.

5. The method according to claim 1 , characterized in that the control unit determines the at least one sector of critical wind directions from a turbulence intensity depending on the wind direction, wherein the turbulence intensity exceeds a predetermined maximum value for the turbulence intensity in the at least one sector.

6. The method according to claim 1 , characterized in that the control unit analyzes the wind velocity as a characteristic value.

7. The method according to claim 5 , characterized in that the control unit calculates the turbulence intensity as a characteristic value from the measured values of the wind velocity and the associated wind directions.

8. The method according to claim 7 , characterized in that the control unit calculates the turbulence intensity from the measured values of the wind velocity and of the wind direction continuously.

9. The method according to claim 5 , characterized in that when the predetermined maximum value for the turbulence intensity is exceeded, the control unit generates the control signal for the control system only when the measured value of the wind velocity exceeds a predetermined maximum value.

10. The method according to claim 5 , characterized in that when the maximum value for the turbulence intensity is exceeded, the control unit generates the control signal for the control system only when a characteristic value for tower head movement and/or acceleration exceeds a predetermined critical value.

11. The method according to claim 1 , characterized in that the effective power is provided as the electric variable.

12. The method according to claim 1 , characterized in that an actual value for the blade pitch angle is present on the control unit.

13. The method according to claim 12 , characterized in that the reduction of the electric variable takes place solely or additionally by a change of the blade pitch angle of at least one rotor blade.

14. The method according to claim 1 , further comprising:

comparing the measured wind direction to the at least one sector of critical wind directions; and

comparing a determined characteristic value to a predetermined maximum value for the characteristic value.

15. A method of operating a wind energy plant, the wind energy plant comprising a control system, a control unit, and a wind measurement device, the method comprising:

determining at least one sector of critical wind directions, the at least one sector of critical wind directions being a region of wind directions where a measured turbulence intensity is greater than a predetermined maximum turbulence intensity;

providing the at least one sector of critical wind directions to the control unit;

measuring wind direction and wind velocity with the wind measurement device;

determining whether the wind direction is in the at least one sector of critical wind directions;

determining whether the measured wind velocity is greater than a predetermined critical value of wind velocity only when the wind direction is in the at least one sector of critical wind directions;

determining a turbulence intensity, the turbulence intensity depending on wind direction and a mean wind velocity;

determining whether the turbulence intensity is greater than a critical turbulence intensity; and

providing a signal to the control system when the wind direction is in the at least one sector of critical wind direction, the turbulence intensity is greater than the critical turbulence intensity, and the measured wind velocity is greater than the critical wind velocity, wherein the control system reduces a desired value of an electric variable upon receiving the signal.

16. A method of operating a wind energy plant, the wind energy plant comprising a control system, a control unit, and a wind measurement device, the method comprising:

determining at least one sector of critical wind directions, the at least one sector of critical wind directions being a region of wind directions where a measured turbulence intensity is greater than a predetermined maximum turbulence intensity;

providing the at least one sector of critical wind directions to the control unit;

measuring wind direction and wind velocity with the wind measurement device;

determining whether the wind direction is in the at least one sector of critical wind directions;

determining a turbulence intensity, the turbulence intensity depending on the measured wind direction;

determining a characteristic value for the stress of the wind energy plant; and

providing a signal to the control system only when the wind direction is in the at least one sector of critical wind direction, the turbulence intensity is greater than a critical turbulence intensity, and the characteristic value for stress is greater than a predetermined maximum value for stress, wherein the control system reduces a desired value of an electric variable upon receiving the signal.

17. A method of operating a wind energy plant, the wind energy plant comprising a control system, a control unit, and a wind measurement device, the method comprising:

determining at least one sector of critical wind directions, the at least one sector of critical wind directions being a region of wind directions where a measured turbulence intensity is greater than a predetermined maximum turbulence intensity;

providing the at least one sector of critical wind directions to the control unit;

measuring wind direction and wind velocity with the wind measurement device;

determining whether the wind direction is in the at least one sector of critical wind directions;

determining a turbulence intensity, the turbulence intensity depending on the measured wind direction;

determining a characteristic value for the stress of the wind energy plant;

providing a signal to the control system only when the wind direction is in the at least one sector of critical wind direction, the turbulence intensity is greater than a critical turbulence intensity, and the characteristic value for stress is greater than a predetermined maximum value for stress, wherein the control system reduces a desired value of an electric variable upon receiving the signal, and

further characterized in that the control unit determines the at least one sector of critical wind directions during operation of the wind energy plant.