OPERATING A WIND TURBINE IN A WIND POWER PLANT DURING LOSS OF COMMUNICATION

Abstract

The invention relates to wind turbines, particularly to controlling a wind turbine during a communication loss between the wind turbine and the power plant controller. In case of communication loss, the wind turbine enters a fallback operation mode, wherein the wind turbine is ramping the power production of the wind turbine to a predefined fallback set point.

Claims

1. A method for operating a wind turbine in a wind power plant, the wind power plant comprises a power plant controller, the method comprising: detecting by the wind turbine a communication loss between the wind turbine and the power plant controller, entering a fallback operation mode of the wind turbine in case of detecting the communication loss, wherein the fallback operation mode comprises ramping the power production of the wind turbine to a predefined fallback set point.

2. The method according to claim 1, wherein ramping the power production of the wind turbine to the predefined fallback set point is performed with a predefined ramp rate or within a predefined time.

3. The method according to claim 1, wherein upon detecting the communication loss, the method comprises entering the fallback operation mode after a set time delay.

4. The method according to claim 3, wherein the method comprises reducing the set time delay with a predefined reduction factor, if the communication loss is not planned.

5. The method according to claim 1, wherein the predefined fallback set point is determined such that the loads on the wind turbine are lowered when entering the fallback operation mode.

6. The method according to claim 1, wherein the predefined fallback set point is determined such that the power production of the wind turbine is ramped down or up to the predefined fallback set point wherein the loads on the wind turbine are at a local minimum.

7. The method according to claim 1, wherein the predefined fallback set point is chosen from a set of fallback set points each being a set point wherein the loads on the wind turbine are at a local minimum.

8. The method according to claim 7, wherein the predefined fallback set point is chosen to be the closest set point of the set of fallback set points.

9. The method according to claim 7, wherein the predefined fallback set point is chosen to be the set point of the set of fallback set points that is reached first when ramping power production down.

10. The method according to claim 1, wherein the method further comprises shutting down the wind turbine after entering the fallback operation mode if communication is not re-established after a given time.

11. The method according to claim 1, wherein the method further comprises ramping the power production of the wind turbine to an operation set point received from the power plant controller when the communication is re-established.

12. The method according to claim 11, wherein ramping the power production of the wind turbine to an operation set point is performed with a predefined ramp rate or within a predefined time.

13. (canceled)

14. (canceled)

15. (canceled)

16. A control system for operating a wind turbine during a communication loss, wherein the control system comprises: a memory; and a processor coupled to the memory and configured to operate a wind turbine in a wind power plant by: detecting by the wind turbine a communication loss with the wind turbine, entering a fallback operation mode of the wind turbine in case of detecting the communication loss, wherein the fallback operation mode comprises ramping the power production of the wind turbine to a predefined fallback set point.

17. A wind turbine comprising: a tower; a nacelle disposed on the tower; a control system for operating the wind turbine by: plant by: detecting by the wind turbine a communication loss with the wind turbine, entering a fallback operation mode of the wind turbine in case of detecting the communication loss, wherein the fallback operation mode comprises ramping the power production of the wind turbine to a predefined fallback set point.

18. A computer program product comprising software code adapted to control a wind turbine when executed on a data processing system, the computer program product being adapted to perform an operation, comprising: detecting by the wind turbine a communication loss between the wind turbine and a power plant controller, entering a fallback operation mode of the wind turbine in case of detecting the communication loss, wherein the fallback operation mode comprises ramping the power production of the wind turbine to a predefined fallback set point.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0051] The wind power plant and the method to control the wind power plant according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0052] FIG. 1 shows a wind turbine.

[0053] FIG. 2 shows an overview of the communication between the power plant controller and the wind turbines in the wind power plant.

[0054] FIG. 3 is a flow-chart of a method according to the invention.

[0055] FIG. 4 shows a state diagram of the method for controlling the wind turbine.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0056] FIG. 1 shows a wind turbine 100 comprising a tower 101 and a rotor 102 with at least one rotor blade 103, such as three blades, extending from the hub 105. The rotor is connected to a nacelle 104, which is mounted on top of the tower 101 and being adapted to drive a generator situated inside the nacelle via a drive train. The rotor 102 is rotatable by action of the wind. The wind induced rotational energy of the rotor blades 103 is transferred via a shaft to the generator. Thus, the wind turbine 100 is capable of converting kinetic energy of the wind into mechanical energy by means of the rotor blades and, subsequently, into electric power by means of the generator. The generator is connected with a power converter, which comprises a generator side converter and a line side converter. The generator side converter converts the generator AC power into DC power and the line side converter converts the DC power into an AC power for injection into the utility grid. Moreover, the wind turbine 100 comprises a control system. The control system may be placed inside the nacelle 104 or distributed at a number of locations inside the turbine 100 and communicatively connected.

[0057] FIG. 2 shows an overview of the communication between the power plant controller 201 and the wind turbines 100 in the wind power plant 200. The wind turbines 100 are connected to an internal medium voltage network 204 to which the wind turbine 100 are transmitting real power P, and transmitting and receiving reactive power Q. The medium voltage network 204 is connected to a transformer 205, wherein the voltage is transformed from the medium voltage network 204 to a high voltage network 206, which is connected to the utility grid 210 through a point of common coupling 209.

[0058] The power plant controller 201 is measuring real power, reactive power, voltage and other relevant data at, or near, the point of common coupling 209. The power plant controller 201 may generate set points for the wind turbines 100 based on the measured values at, or near, the point of common coupling and preferably also based on operation parameters of wind turbines 100. The power plant controller 201 is communicating with the wind turbines 100 through the communication lines 211, which may be wireless. The communication may be operation set points sent from the power plant controller 201 to the wind turbines 100 and relevant operation parameter sent from the from the wind turbines 100 to the power plant controller 201.

[0059] FIG. 3 shows an example of a possible implementation of the method of the invention. The control system of a wind turbine is constantly monitoring for a communication loss 301 between the wind turbine and the power plant controller. The communication loss may be detected by not receiving any communication from the power plant controller within a time period, for instance within 500 ms. When a communication loss is detected, the control system of the wind turbine may wait for a set time delay 304, for instance five or ten seconds, and if still not receiving any communications from the power plant controller, the control system realizes there still is a communication loss 305. The communication loss may be just a glitch and the communication may be re-established after a short time, perhaps only a few seconds. If communication is not re-established after a short time within the set time delay, the wind turbine enters the fallback operation mode 306. When in fallback operation mode the wind turbine control system selects a predefined fallback set point and ramps the power production to the fallback set point 307. The predefined fallback set point selected may be selected from a set of fallback set points, where each set point represent a local minimum in the load on the wind turbine. Ramping the power production to the fallback set point may be done fast or slow, for example, depending in whether it is a planned or an unplanned communication loss. Further, when entering the fallback operation mode, the wind turbine control system starts a shutdown timer 308. If the shutdown timer expires 309, the wind turbine is shut down 310 If the shutdown timer does not expire, and it is detected that the communication loss has ended 311 and communication is re-established, the wind turbine returns to normal operation 312. Ending of the communication loss is determined by the wind turbine when it again receives a operation set point from the power plant controller. The wind turbine will then return to normal operation and ramps the power production to meet the received operation set point.

[0060] Of course, the method may be implemented in different ways than described above, as there are many ways to make an embodiment according to the method of this invention.

[0061] FIG. 4 shows a state diagram of the method for controlling the wind turbine. The wind turbine is operating in normal operation 401, but when a communication loss 404 occurs, the wind turbine changes to fallback operation mode 402. When entering fallback operation mode a timer is started and after a given time, the wind turbine is shutting down 403. However, if communication is reestablished 405 before the given time has elapsed, the wind turbine returns to normal operation 401.

[0062] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms comprising or comprises do not exclude other possible elements or steps. Also, the mentioning of references such as a or an etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.