DETECTING A WIND TURBINE ROTOR BLADE ADJUSTMENT FAULT

Abstract

A method of detecting an adjustment fault related to a wind turbine rotor blade mounted at a wind turbine rotor and including an adaptable flow regulating device, in particular spoiler and/or flap, the method including: estimating a quantity indicative of a change of a driving impact of wind on the wind turbine rotor based on at least two settings of the adaptable flow regulating device; determining another quantity indicative of a desired change of the driving impact on the wind turbine rotor, in order to change a value of a rotor speed to a reference value of the rotor speed; and indicating an adjustment fault based on a comparison of the quantity with the other quantity, is provided.

Claims

1. A method of detecting an adjustment fault related to a wind turbine rotor blade mounted at a wind turbine rotor and comprising an adaptable flow regulating device, the method comprising: estimating a first quantity indicative of a change of a driving impact of wind on the wind turbine rotor based on at least two settings of the adaptable flow regulating device; determining a second quantity indicative of a desired change of the driving impact on the wind turbine rotor to change a value of a rotor speed to a reference value of the rotor speed; and indicating an adjustment fault based on a comparison of the first quantity with the second quantity.

2. The method according to claim 1, wherein estimating the first quantity indicative of the change of the driving impact on the wind turbine rotor is further based on at least two settings of a blade pitch of the rotor blade, and/or wherein the first quantity and/or the second quantity comprises a rotor torque.

3. The method according to claim 1, wherein the comparison of the first quantity with the second quantity includes: determining a quantity difference between the first quantity and the second quantity.

4. The method according to claim 1, wherein the adjustment fault is indicated: if an absolute value of the quantity difference exceeds a quantity threshold; and/or if a sum of an absolute value of the quantity difference accumulated over a time interval exceeding a quantity threshold exceeds another quantity threshold.

5. The method according to claim 1, wherein estimating the first quantity comprises: modelling an air flow close to and/or at the rotor blade based on the value of the rotor speed for the at least two respective settings of the adaptable flow regulating device and the blade pitch; deriving, based on the air flow for the different settings, aerodynamic impact acting on the rotor blade for the different settings.

6. The method according to claim 1, wherein determining the second quantity is based on the value of the rotor speed and the rotor speed reference value.

7. The method according to claim 1, further comprising: measuring the at least two settings of the adaptable flow regulating device at a first time point and a second time point and determining a difference between the at least two settings; and/or measuring the at least two settings of the blade pitch at the first time point and the second time point and determining a difference between the at least two settings; and/or measuring the value of the rotor speed.

8. The method according to claim 1, wherein the at least two settings of the adaptable flow regulating device each indicates respective protrusion height and/or orientation and/or tilt of an airfoil shaped surface of the adaptable flow regulating device exposed to an air flow.

9. The method according to claim 1, wherein the at least two settings of the adaptable flow regulating device correspond to two states of the adaptable flow regulating device that differ in an effect on air flow.

10. The method according to claim 1, wherein the adaptable flow regulating device comprises a plurality of adaptable flow regulating device modules mounted at the rotor blade which are independently settable in respective module states, each of the at least two settings of the adaptable flow regulating device comprising information regarding all module states.

11. The method according to claim 1, further comprising, after indicating the adjustment fault: triggering a safe stop function of the adaptable flow regulating device and/or the blade pitch system for stopping the wind turbine.

12. An arrangement for detecting an adjustment fault related to a wind turbine rotor blade mounted at a wind turbine rotor and comprising an adaptable flow regulating device, the arrangement comprising a processor adapted: to estimate a first quantity indicative of a change of a driving impact of wind on the wind turbine rotor based on at least two settings of the adaptable flow regulating device; to determine a second quantity indicative of a desired change of the driving impact on the wind turbine rotor to change a value of a rotor speed to a reference value of the rotor speed; and to determine a presence of an adjustment fault based on a comparison of the first quantity with the second quantity.

13. The arrangement according to claim 12, further comprising: an input section for receiving the at least two settings of the adaptable flow regulating device and at least two settings of a blade pitch.

14. A wind turbine rotor blade, comprising: an adaptable flow regulating device; and the arrangement according to claim 12.

15. A wind turbine, comprising: a wind turbine rotor; and the wind turbine rotor blade mounted at the wind turbine rotor according to claim 14.

Description

BRIEF DESCRIPTION

[0049] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0050] FIG. 1 depicts a wind turbine rotor blade according to an embodiment of the present invention which comprises an adaptable flow regulating device according to an embodiment of the present invention; and

[0051] FIG. 2 depicts an arrangement for detecting an adjustment fault related to a wind turbine rotor blade mounted at a wind turbine rotor and comprising an adaptable flow regulating device according to an embodiment of the present invention which is configured to carry out a method according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0052] The illustration in the drawings is in schematic form.

[0053] The rotor blade 1 for a wind turbine illustrated in FIG. 1 comprises a rotor blade surface 3 which is exposed to the air flow during normal operation of the rotor blade involving rotation around a rotation axis 4 of a wind turbine. In particular, the rotor blade 1 comprises a front edge 5 and a rear (or trailing) edge 7 representing upstream edge and downstream edge, respectively, with respect to a wind direction 9.

[0054] The rotor blade 1 further comprises at least one adaptable flow regulating device 11 according to an embodiment of the present invention. The flow regulating device 11 is in the illustrated embodiment a spoiler which is installed for example at a suction side surface close to the front edge 5 of the rotor blade 1. The spoiler 11 comprises (in general the adaptable flow regulating device) comprises an airfoil surface 13 to be exposed to the air flow 9 during rotation of the rotor blade 1.

[0055] The wind turbine rotor blade 1 illustrated in FIG. 1 further comprises an arrangement 15 for detecting an adjustment fault related to the wind turbine rotor blade 1 mounted at the wind turbine rotor 4 and comprising an adaptable flow regulating device 11 according to an embodiment of the present invention. Thereby, the arrangement comprises an input section 17 which is adapted for receiving at least two settings 19a, 19b (e.g. measured by actuator and/or sensor 24) of the adaptable flow regulating device 11 and in particular also at least two settings 21a, 21b of a blade pitch which are measured for example by actuator and/or sensor 23.

[0056] The arrangement 15 is illustrated in an exemplary embodiment schematically in FIG. 2. At the input section 17, the arrangement 15 receives from the actuator and/or sensor 24 settings 19a, 19b, 19c of the flow regulating device 11. Further, the arrangement 15 receives the blade pitch angles 21a, 21b, 21c as determined by the actuator and/or sensor 23 measuring the blade pitch angles of the rotor blade 1. In particular, the blade pitch angles relate to a rotation angle of the rotor blade around a longitudinal axis 6 of the rotor blade.

[0057] As further inputs, the arrangement receives a value 25 of the rotor speed as is currently present. Furthermore, the arrangement receives a reference value 27 of the rotor speed at the input section 17. The arrangement 15 further comprises a pitch activity determination module 29 which derives from the pitch settings 21a, 21b, 21c for example a change of the pitch angles, as is indicated with reference sign 31.

[0058] Furthermore, the arrangement comprises an active add-on activity module 33 which receives the settings 19a, 19b, 19c of the adaptable flow regulating device 11 and determines a change 35 of the setting of the flow regulating device 11. Furthermore, the arrangement 15 comprises an estimation block 37 which is configured to estimate the rotor torque change (or in general a quantity) 41 based on the pitch activity change 31 and the active add-on activity change 35. The estimation block 37 therefore also receives the actual value 25 of the rotor speed. The estimation module 37 outputs the quantity 41 indicative of a change of a driving impact of wind on the wind turbine rotor, in particular indicating the torque.

[0059] A further processing module 39 is configured to determine e.g. the need of the rotor torque change rate based on the actual value 25 of the rotor speed and the reference value 27 of the rotor speed. The processing module 39 outputs the other quantity 43 indicative of a required change of the driving impact on the wind turbine rotor, in order to change a value of the rotor speed, i.e. the value 25 of the rotor speed, to the reference value 27 of the rotor speed.

[0060] The quantity 41 and the other quantity 43 are compared in a monitoring module 45 which is also comprised within the arrangement 15. If the difference between the quantity 41 and the other quantity 43 is exceeding a quantity threshold, a fault indicating signal 47 is output from the monitoring module 45 and supplied to a safety stop block 49 which may initiate or trigger a safe stop of the wind turbine.

[0061] Embodiments of the invention introduce a model-based actuator runaway protection system as is exemplarily illustrated in FIG. 2. Based on a state input from the blade pitch angle (for example blade pitch setting signals 21a, 21b, 21c) and the state of the active add-on (for example flow regulating device settings 19a, 19b, 19c) and further based on the actual value of the rotor speed 25, the actual change in rotor torque (for example labelled with reference sign 41) is estimated. This estimation, performed by the estimator block 37, may be done based on detailed data about the aerodynamic impact of the blade and active add-on or it could be based on simplified models.

[0062] The need of rotor torque change rate (for example labelled with reference sign 43 in FIG. 2) may be calculated as a function of the rotor speed 25, and the nominal or reference speed 27. The monitoring unit 45 may activate a safe stop function, if the difference between the estimated rotor torque change and the need of rotor torque change rate exceeds a threshold level. It could also be triggered if the accumulated values above the threshold level exceed an additional threshold for this accumulated value. The safe stop function (for example initiated or executed in block 49) may be either a safe pitch function or an active add-on function which may have the capacity of stopping the turbine, or a combination of these.

[0063] Embodiments of the present invention introduce active add-on states in an actuator runaway protect system. All actuators of one or more flow regulating devices may be summed or normalized to a sum of rotor torque change rate. All actuator systems may be compared by combining expected need of rotor torque change with an actual rotor torque change and activate the safe stop if they differ more than a threshold.

[0064] Advantages provided by embodiments of the present invention may be that the monitoring system can be made very narrow and slim and precise so it may capture an actuator runaway very early. This may reduce the design loads of the turbine. The monitoring unit or module 45 may for example output a signal indicating a fault, such as “actuator runaway”. According to another embodiment of the present invention, a wind turbine is provided including the rotor blade illustrated in FIG. 1.

[0065] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0066] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.