Noise control for a wind turbine

1. An arrangement for determining a d-component (Idref, I*d) of a reference current in a d-q coordinate system for reducing noise/vibration of a wind turbine, the arrangement comprising:

a noise/vibration determination module for determining at least one noise/vibration component of oscillations of at least one wind turbine component; and

a processing block for calculating a first type of the d-component of the reference current based on the at least one noise/vibration component output by the noise/vibration determination module.

2. The arrangement according to claim 1 , wherein the processing block comprises:

a noise/vibration processing module for obtaining an actual characteristic of at least one noise/vibration component of the determined at least one noise/vibration component;

a reference determination module for providing a reference characteristic of the noise/vibration component; and

a control module for calculating the first type of the d-component of the reference current based on a difference between the actual characteristic and the reference characteristic of the noise/vibration component.

3. The arrangement according to claim 1 , wherein the noise/vibration determination module comprises:

a sensor module for sensing noise and/or vibration for measuring the noise/vibration components of oscillations of the at least one wind turbine component.

4. The arrangement according claim 1 , wherein the noise/vibration determination module comprises:

an estimation module for estimating the noise/vibration components of oscillations of the at least one wind turbine component based on current (Id, Iq), voltage (Vd, Vq) output by a generator of the wind turbine and based on rotational frequency (ωg) and angular position (θg) of a rotor of the generator.

5. The arrangement according to claim 3 , wherein the noise/vibration determination module comprises:

a switch to selectively alternatively supply the noise/vibration components of oscillations of the at least one wind turbine component as measured by the sensor or as estimated by the estimation module to the noise/vibration processing module.

6. The arrangement according to claim 1 , wherein the reference determination module is configured to calculate a reference characteristic of the noise/vibration component based on a simulation or off-line test using a rotational frequency (ωg) and a torque (Te) of a generator as input,

wherein the reference determination module comprises a look up table comprising information for different working points.

7. The arrangement according to claim 1 , wherein

the noise/vibration processing module outputs an amplitude and/or phase of the noise/vibration component being associated with 6 times or 12 times an electrical frequency as the actual characteristic and

the reference determination module outputs a reference amplitude and/or phase of the noise/vibration component being associated with 6 times or 12 times an electrical frequency as the reference characteristic.

8. The arrangement according to claim 1 , wherein

the noise/vibration processing module outputs a wave form signal of the noise/vibration component being associated with 6 times or 12 times an electrical frequency as the actual characteristic and

the reference determination module outputs a reference wave form signal of the noise/vibration component being associated with 6 times or 12 times an electrical frequency as the reference characteristic.

9. The arrangement according to claim 1 , further comprising:

a subtraction element for calculating a difference between the actual characteristic and the reference characteristic of the noise/vibration component being arranged to supply the difference to a control module.

10. The arrangement according to claim 1 , further comprising:

a MTPA module configured to apply a maximum torque per ampere algorithm for calculating a second type of the d-component of the reference current in a d-q coordinate system for minimizing generator total current.

11. The arrangement according to claim 1 , further comprising:

a voltage control module configured to calculate, for flux weakening under high speed operation, a third type of the d-component of the reference current in a d-q coordinate system for avoiding converter overmodulation.

12. The arrangement according to claim 11 , further comprising:

a selection module for selecting the first type, the second type or the third type of the d-component of the reference current as the d-component of the reference current, wherein in particular the minimum is selected.

13. A generator side controller for controlling a generator side frequency converter of a wind turbine, the generator side controller comprising:

an arrangement for determining a d-component of a reference current according to claim 1 ;

an arrangement for determining a q-component of a reference current;

a current controller for determining a d-component and a q-component of a desired voltage at the generator output; and

a modulator to generate pulse width modulation signals, for the generator side frequency converter, based on the d-component and the q-component of the desired voltage.

14. A wind turbine, comprising:

a generator;

a generator side frequency converter; and

a generator side controller according to claim 13 , coupled to control the generator side frequency converter.

15. A method for determining a d-component of a reference current in a d-q coordinate system for reducing noise of a wind turbine, the method comprising:

determining at least one noise/vibration component of oscillations of at least one wind turbine component; and

calculating a first type of the d-component of the reference current based on the noise/vibration component output by the noise/vibration determination module, the calculating comprising:

obtaining an actual characteristic of at least one noise/vibration component of the determined noise/vibration component;

providing a reference characteristic of the noise/vibration component; and

calculating the first type of the d-component of the reference current based on a difference between the actual characteristic and the reference characteristic of the noise/vibration component.

16. The arrangement according to claim 3 , wherein the sensor module is at least one of a microphone and acceleration sensor.