Wind turbine controller and method for controlling a power production of a wind turbine

1. A wind turbine controller for controlling a power production of a wind turbine, the wind turbine being arranged within a wind farm being coupled to a public power network via a point of common coupling, the wind turbine controller comprising:

a receiving unit for receiving a measured value of a property of the wind farm taken at the point of common coupling and for receiving a reference value for the property,

a control unit, in communication with the receiving unit, for controlling the power production of the wind turbine in a PCC-control mode by regulating a local property of the wind turbine based on the received measured value of the property and the received reference value of the property according to a current control mode of a plurality of control modes such that the measured value of the property of the wind farm taken at the point of common coupling corresponds to the reference value for the property, and

a monitoring unit, in communication with the control unit, for monitoring a value of a local voltage generated by the control unit to control the power production of the wind turbine,

wherein the monitoring unit configured to generate a voltage alert signal in response to determining by the monitoring unit the value of the local voltage is below a lower voltage limit value or above an upper voltage limit value of a voltage range, and

wherein the control unit configured to receive the voltage alert signal from the monitoring unit and, in response to the voltage alert signal, the control unit switches from the current control mode to a local voltage control mode of the plurality of control modes of the control unit, in which the control unit controls the power production of the wind turbine by regulating the local property of the wind turbine based on the voltage range.

2. The wind turbine controller according to claim 1 ,

wherein the property of the wind farm is at least one of a current, a voltage, a reactive power and a power factor.

3. The wind turbine controller according to claim 1 ,

wherein the local property of the wind turbine is at least one of the local voltage and a local reactive power.

4. The wind turbine controller according to claim 1 ,

wherein the control unit is further configured to determine a difference between the measured value and the reference value.

5. The wind turbine controller according to claim 1 ,

wherein the receiving unit is configured to receive a number of wind turbines being active within the wind farm, and wherein the control unit is further configured to control the power production based on the number of wind turbines.

6. The wind turbine controller according to claim 1 ,

wherein the monitoring unit monitors a value of a current set-point of the wind turbine.

7. The wind turbine controller according to claim 6 ,

wherein the monitoring unit is further configured to generate a current alert signal in response to determining by the monitoring unit the value of the current set-point is below a lower current limit value or above an upper current limit value of a current converter range.

8. The wind turbine controller according to claim 7 ,

wherein the control unit is further configured to receive the current alert signal and to switch to a local current control mode of the plurality of control modes of the control unit, in which the control unit controls the power production of the wind turbine by regulating the local property of the wind turbine based on the current converter range.

9. The wind turbine controller according to claim 8 ,

wherein the control unit is further configured to turn off an integrating unit of the control unit when receiving the current alert signal, and to turn on the integrating unit when the value of the current set-point is within the current converter range.

10. A wind turbine being arranged within a wind farm, the wind turbine comprising:

a power production unit for producing power, and

a wind turbine controller according to claim 1 for controlling the power production unit.

11. A wind farm being coupled to a public power network via a point of common coupling, the wind farm comprising:

a plurality of wind turbines according to claim 10 , and

a wind farm administration unit for measuring a value of a property of the wind farm taken at the point of common coupling and for sending the value of the property of the wind farm and a reference value for the property to the plurality of wind turbines.

12. The wind turbine controller according to claim 1 , wherein the control unit comprises a voltage controller producing a first local signal, an active power controller producing a second local signal, and a converter current controller producing a third local signal, based on an error signal from the point of common coupling wherein the monitoring unit is configured to monitor the first local signal, the second local signal and the third local signal so that the monitoring unit generates an alert signal to switch the control unit to a corresponding different control mode of the plurality of control modes of the control unit in response to the monitoring unit determining when one of the first local signal, the second local signal and the third local signal exceeds a corresponding limit.

13. A method for controlling a power production of a wind turbine, the wind turbine being arranged within a wind farm being coupled to a public power network via a point of common coupling, the method comprising:

receiving, by a wind turbine controller of the wind turbine, a measured value of a property of the wind farm taken at the point of common coupling (PCC),

receiving, by the wind turbine controller, a reference value for the property,

controlling, by a control unit of the wind turbine controller in a PCC-control mode, the power production of the wind turbine by regulating a local property of the wind turbine based on the received measured value of the property and the received reference value of the property according to a current control mode of a plurality of control modes such that the measured value of the property of the wind farm taken at the point of common coupling corresponds to the reference value for the property,

monitoring, by a monitoring unit of the wind turbine controller, a value of a local voltage generated by the control unit to control the power production of the wind turbine wherein the monitoring unit is in communication with the control unit,

generating, by the monitoring unit, a voltage alert signal in response to determining by the monitoring unit the value of the local voltage is below a lower voltage limit value or above an upper voltage limit value of a voltage range, and

switching, in response to the generated voltage alert signal, the control unit of the wind turbine controller from the current control mode to a local voltage control mode of the plurality of control modes of the control unit, in which the power production of the wind turbine is controlled by regulating the local property of the wind turbine based on the voltage range.

14. A non-transitory computer program product comprising a program code for executing the method according to claim 13 , when run on at least one computer.