WIND TURBINE BLADE FLOW REGULATION

Abstract

Provided is a wind turbine including: at least a rotor blade including an aerodynamic device for influencing the airflow flowing from the leading edge section of the rotor blade to the trailing edge section of the rotor blade, wherein the aerodynamic device is mounted at a surface of the rotor blade, a pressure supply system for providing a pressurized fluid for operating the aerodynamic device between a first protruded configuration and a second retracted configuration, a control unit for controlling the pressure supply system, a monitor unit for monitoring a pressure and/or a flow rate of the pressurized fluid, and configured for: receiving a measured pressure and/or flow rate signal in at least one section of the pressure supply system, deriving an operative status of the aerodynamic device based on the measured pressure and/or flow rate signal.

Claims

1. A turbine comprising: a rotor blade comprising an aerodynamic device for influencing an airflow flowing from a leading edge section of the rotor blade to a trailing edge section of the rotor blade, wherein the aerodynamic device is mounted at a surface of the rotor blade; a pressure supply system for providing a pressurized fluid for operating the aerodynamic device between a first protruded configuration and a second retracted configuration; a control unit for controlling the pressure supply system; and a monitor unit for monitoring a pressure and/or a flow rate of the pressurized fluid, wherein the monitor unit configured for: receiving a measured pressure and/or flow rate signal in at least one section of the pressure supply system, and deriving an operative status of the aerodynamic device based on the measured pressure and/or flow rate signal.

2. The wind turbine according to claim 1, wherein the pressure supply system comprises: a first pressure control volume containing the pressurized fluid at a first pressure value, a second pressure control volume containing the pressurized fluid at a second pressure value higher than the first pressure value, a pressure line for providing the pressurized fluid from an actuator of the aerodynamic device to the first pressure control volume and from the second pressure control volume to the actuator of the aerodynamic device at least one pressure sensor and/or one flow rate sensor for measuring the pressure and/or the flow rate of the pressurized fluid in at least one section of the pressure supply system the monitor unit being connected to the at least one pressure sensor and/or one flow rate sensor.

3. The wind turbine according to claim 2, wherein the pressure supply system comprises: a nozzle upstream the first pressure control volume.

4. The wind turbine according to claim 3, wherein the pressure supply system comprises: at least one de-pressurizing valve for connecting the pressure line to the first pressure control volume such a way that the pressurized fluid flows from the actuator of the aerodynamic device to the first pressure control volume the control unit and the monitor unit being connected to the at least one de-pressurizing valve, at least one pressurizing valve for connecting the pressure line to the second pressure control volume in such a way that the pressurized fluid flows from the second pressure control volume to the actuator of the aerodynamic device, the control unit and the monitor unit being connected to the at least one pressurizing valve, the nozzle being placed between the at least one de-pressurizing valve and the first pressure control volume.

5. A rotor blade for a wind turbine an aerodynamic device for influencing an airflow flowing from a leading edge section of the rotor blade to trailing edge section of the rotor blade; wherein the aerodynamic device is mounted at a surface of the rotor blade; a pressure supply system for operating the aerodynamic device between a first protruded configuration and a second retracted configurations; a control unit for controlling the pressure supply system; and a monitor unit for monitoring a pressure and/or a flow rate of the pressurized fluid, wherein the monitor unit is configured for: receiving a measured pressure and/or flow rate signal in at least one section of the pressure supply system, and deriving an operative status of the aerodynamic device based on the measured pressure and/or flow rate signal.

6. A method for detecting an operative status of an aerodynamic device for influencing an airflow flowing from a leading edge of a rotor blade for a wind turbine to a trailing edge of the rotor blade, the aerodynamic device being movable by an actuator between a first protruded configuration and a second retracted configuration pressure supply system for providing a pressurized fluid, the method comprising: measuring a pressure signal and/or a flow rate signal in at least a section of the pressure supply system, and deriving the operative status of the aerodynamic device based on the pressure signal and/or the rate signal.

7. The method according to claim 6, comprising: measuring a temporal course of the pressure and/or the flow rate in at least a section of the pressure supply system, comparing the temporal course of the pressure and/or the flow rate in at least a section of the pressure supply system with a desired pressure temporal course, and deriving the operative status of the aerodynamic device based on a comparison between the temporal course of the pressure and/or the flow rate in at least a section of the pressure supply system with a desired pressure temporal course.

8. The method according to claim 7, wherein the measuring of a temporal course of a pressure and/or flow rate in at least a section of the pressure supply system is performed during pressurizing or de-pressurizing of a pressure line for providing the pressurized fluid to an actuator of the aerodynamic device

9. The method according to claim 7, wherein comparing the measured temporal course of the operational value with a desired temporal course of an operational value comprises calculating a difference between the pressure and/or the flow rate in at least a section of the pressure supply system with a desired pressure and/or desired flow rate temporal course.

10. The method according to claim 8, wherein if during pressurizing or de-pressurizing of the pressure line the measured temporal course of the pressure and/or the flow rate increases and/or decreases faster or slower than a desired pressure and/or flow rate temporal course, then a faulty status of the aerodynamic device is derived.

11. The method according to claim 7, the method comprising: calculating a frequency spectrum of the pressure and/or the flow rate signal, and deriving an operative status of the aerodynamic device based on the frequency spectrum.

Description

BRIEF DESCRIPTION

[0045] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0046] FIG. 1 shows a wind turbine;

[0047] FIG. 2 shows a rotor blade of a wind turbine including an aerodynamic device;

[0048] FIG. 3 shows a radial section of the rotor blade of FIG. 2;

[0049] FIG. 4 shows a radial section of the rotor blade of FIG. 2

[0050] FIG. 5 shows a diagram describing a pneumatic arrangement according to embodiments of the present invention included in the wind turbine of FIG. 1;

[0051] FIG. 6 shows temporal course of operational values of the wind turbine of FIG. 1, in normal operative condition;

[0052] FIG. 7 shows temporal course of operational values of the wind turbine of FIG. 1, in a first faulty operative condition; and

[0053] FIG. 8 shows temporal course of operational values of the wind turbine of FIG. 1, in a second faulty operative condition.

DETAILED DESCRIPTION

[0054] FIG. 1 shows a conventional wind turbine 10 for generating electricity. The wind turbine 10 comprises a tower 11 which is mounted on the ground 16 at one end. At the opposite end of the tower 11 there is mounted a nacelle 12. The nacelle 12 is usually mounted rotatable with regard to the tower 11, which is referred to as comprising a yaw axis substantially perpendicular to the ground 16. The nacelle 12 usually accommodates the generator of the wind turbine and the gear box (if the wind turbine is a geared wind turbine). Furthermore, the wind turbine 10 comprises a hub 13 which is rotatable about a rotor axis Y. When not differently specified, the terms axial, radial and circumferential in the following are made with reference to the rotor axis Y. The hub 13 is often described as being a part of a wind turbine rotor, wherein the wind turbine rotor is capable to rotate about the rotor axis Y and to transfer the rotational energy to an electrical generator (not shown).

[0055] The wind turbine 1 further comprises at least one blade 20 (in the embodiment of FIG. 1, the wind rotor comprises three blades 20, of which only two blades 20 are visible) mounted on the hub 13. The blades 4 extend substantially radially with respect to the rotational axis Y.

[0056] Each rotor blade 20 is usually mounted pivotable to the hub 13, in order to be pitched about respective pitch axes X. This improves the control of the wind turbine and in particular of the rotor blades by the possibility of modifying the direction at which the wind is hitting the rotor blades 20. Each rotor blade 20 is mounted to the hub 13 at its root section 21. The root section 21 is opposed to the tip section 22 of the rotor blade.

[0057] FIG. 2 illustrates the rotor blade 20 comprising an aerodynamic device 30 in the form of an actuated spoiler. Between the root section 21 and the tip section 22 the rotor blade 20 furthermore comprises a plurality of aerofoil sections for generating lift. Each aerofoil section comprises a suction side 25 and a pressure side 26. The aerofoil shape of the aerofoil portion is symbolized by one aerofoil profile which is shown in FIG. 2 and which illustrates the cross-sectional shape of the rotor blade at this spanwise position. Also note that the suction side 25 is divided or separated from the pressure side 26 by a chord line 27 which connects a leading edge 41 with a trailing edge 31 of the rotor blade 20.

[0058] The aerodynamic device 30 is arranged on the suction side 25 between the leading edge 41 and the trailing edge 31.

[0059] The aerodynamic device 30 in FIG. 2 is movable by a pressure line 53 or other pneumatic actuator, for example an inflatable cavity, or by an hydraulic actuator.

[0060] The pressure line 53 is comprised in a pressure supply system 52, controlled by a control unit 51 and monitored by a monitor unit 54. The pressure supply system 52 provides a pressurized fluid, for example pressurized air or other pressurized gasses. In this context, the term “pressurized fluid” not only implies positive pressure but also negative pressure, wherein fluid is sucked (or “drawn”) out of the pressure hose of the aerodynamic device 30. The pressure line 53 could be in practice realized as tubes or pipes which do not significantly change their volume. Finally, the control unit 51 is responsible for setting a specific pressure at the pressure supply system 52 which subsequently leads to a certain predetermined pressure at the aerodynamic device 30. In the example shown in FIG. 2, the control unit 51, the pressure supply system 52 and the monitor unit 54 are located in the root section 21 of the rotor blade 20. According to other embodiments of the present invention (not shown in the attached figures), these parts could also be placed elsewhere in the wind turbine, such as e.g. in the hub 13 of the wind turbine 10.

[0061] The rotor blade 20 additionally comprises a flow regulating unit 40 comprising multiple pairs of vortex generators.

[0062] The flow regulating unit 40 are arranged on the suction side 25 of the blade 20 between the aerodynamic device 30 and the trailing edge 31.

[0063] According to other embodiments of the present invention (not shown in the attached figures), the flow regulating unit 40 are arranged on the suction side 25 of the blade 20 between the leading edge 41 and the aerodynamic device 30.

[0064] According to other embodiments of the present invention (not shown in the attached figures), the flow regulating unit 40 are not present and only the aerodynamic device 30 is used to regulate the flow on the surface of the blade 20.

[0065] According to other embodiments of the present invention (not shown in the attached figures), the blade 20 comprises a plurality of aerodynamic devices 30.

[0066] FIG. 3 shows the aerodynamic device 30 in a first protruded configuration.

[0067] In the first configuration the aerodynamic device 30 deviates the airflow 61 which is flowing from the leading edge 41 to the trailing edge 31 of the rotor blade.

[0068] The aerodynamic device 30 in the first protruded configuration induces stall. This is visualized with relatively large vortices 63 downstream of the aerodynamic device 30. A consequence of the induced stall is a decrease in lift of the rotor blade and, consequently, a reduced loading of the rotor blade and related components of the wind turbine.

[0069] FIG. 4 shows the aerodynamic device 30 in a second retracted configuration, i.e. moved downwards towards the surface of the rotor blade 20.

[0070] In this second configuration, the airflow 61 flowing across the aerodynamic device 30 remains attached to the surface of the rotor blade 20, thus that no flow separation, i.e. stall, occurs. As a consequence, the lift of the rotor blade increases. Re-energizing vortices 64 are generated in the boundary layer by the vortex generators 40, which have the effect of helping increasing the lift. As a result, the highest lift values can be achieved.

[0071] By operating the actuator, i.e. the pressure line 53, of the aerodynamic device 30, the aerodynamic device 30 can be moved between the first protruded configuration and the second retracted configuration in order to vary the aerodynamic properties of the blade as desired and requested when operating the wind turbine 10.

[0072] FIG. 5 shows a pneumatic scheme of the pressure supply system 52 and the connections between the pressure supply system 52 and the control unit 51, the monitor unit 54 and the aerodynamic device 30.

[0073] The pressure supply system 52 comprises a first control volume 55a and a second control volume 55b connected to the pressure line 53, respectively through at least one de-pressurizing valve 56 (two de-pressurizing valves 56 in the embodiment of FIG. 5, for redundancy purpose) and through at least one pressurizing valve 57 (two pressurizing valves 57 in the embodiment of FIG. 5, for redundancy purpose).

[0074] In the embodiment of FIG. 3, the first control volume 55a and the second control volume 55b are confined in respective tanks. According to other possible embodiments (not shown), each control volume is part of larger volume.

[0075] The first pressure control volume 55a contains a pressurized fluid at a first pressure value while the second pressure control volume 55b contains the pressurized fluid at a second pressure value higher than the first pressure value.

[0076] The pressure line 53 provides the pressurized fluid from an actuator of the aerodynamic device 30 to the first pressure control volume 55a and from the second pressure control volume 55b to the actuator of the aerodynamic device 30.

[0077] The pressure supply system 52 further comprises at least one pressure sensor 59 (two pressure sensors 59 in the embodiment of FIG. 5, for redundancy purpose) for measuring the pressure of the pressurized fluid in the pressure line 53.

[0078] According to other embodiments of the present invention (not shown), the pressure sensors 59 may be used to measure the pressure in another section of the pressure supply system 52, for example in the pressure line 53 near to the aerodynamic device 30. The pressure sensors could also be placed at the end of a return hose (not represented) from the aerodynamic device 30 to pressure supply system 52.

[0079] According to other embodiments of the present invention (not shown), one or more flow rate sensors may be used for measuring a mass or volume flow rate signal in at least one section of the pressure supply system 52, for example immediately upstream of the pressure line 53 or in the pressure line 53 itself.

[0080] A nozzle 58 is provided in the pressure supply system 52 between the two de-pressurizing valves 56 and the first pressure control volume 55a.

[0081] The de-pressurizing valves 56 are distribution valves with two positions and two ports and connect the pressure line 53 to the first pressure control volume 55a in such a way that the pressurized fluid flows from the actuator of the aerodynamic device 30 to the first pressure control volume 55a.

[0082] The two pressurizing valves 57 are distribution valves with two positions and two ports and connect the pressure line 53 to the second pressure control volume 55b in such a way that the pressurized fluid flows from the second pressure control volume 55b to the actuator of the aerodynamic device 30, the control unit 51 and the monitor unit 54 being connected to the at least one pressurizing valve 57.

[0083] The control unit 51 is connected to the de-pressurizing valves 56 and to the pressurizing valves 57 in order to operate such valves 56, 57.

[0084] The monitor unit 54 is connected to the de-pressurizing valves 56, to the pressurizing valves 57 and to the pressure sensors 59.

[0085] In embodiments where more flow rate sensors are present, the monitor unit 54 is connected to the flow rate sensors.

[0086] According to other embodiments, the present invention may be applied to other pressure supply systems having different schemes including, for example, pumps and/or blowers, valves for controlling pressure and/or flow rate of the pressurized fluid and one or more pressure tanks or control volumes. Pressure or air flow sensors could be placed between the pumps/blower and the control volumes and/or in connection with the individual pressure lines.

[0087] The monitor unit 54 is configured for: [0088] comparing the measured temporal course of the pressure measured by the pressure sensors 59 with a desired pressure temporal course, [0089] deriving an operative status of the aerodynamic device 30, based on such comparison. Alternatively, or in addition thereto, the monitor unit 54 is configured for: [0090] comparing a measured temporal course of the flow rate with a desired flow rate temporal course, [0091] deriving an operative status of the aerodynamic device 30, based on such comparison.

[0092] FIGS. 6 to 8 show embodiments of respective executions of a method for detecting the operative status of the aerodynamic device 30.

[0093] In embodiments of the present invention, such method is performed using the above described pressure supply system 52 in connection with the control unit 51 and the monitor unit 54.

[0094] Each of the FIGS. 6 to 8 comprises: [0095] a first diagram 101 representing the valve states 105, 106 of the de-pressurizing valves 56 and of the pressurizing valves 57, respectively; [0096] a second diagram 102 representing the measured temporal course 110 of the pressure measured by the pressure sensors 59 superposed to a desired pressure temporal course 120; [0097] a third diagram 103 representing the actual position 130 of the aerodynamic device 30 superposed to an expected position 140 of the aerodynamic device 30. The expected position correspond theoretically to the valve states of the de-pressurizing valves 56 and of the de-pressurizing valves 57, when the aerodynamic device 30 and their actuator are faultless. In the third diagram 103 the ordinate “1” corresponds to the first protruded configuration of the aerodynamic device 30 (FIG. 3) while the ordinate “0” corresponds to the second retracted configuration of the aerodynamic device 30 (FIG. 4).

[0098] With reference to the first diagram 101, in all the FIGS. 6 to 8, the pressurizing valves 57 are activated, i.e. for connecting the second pressure control volume 55b to the actuator of the aerodynamic device 30, in a first time interval T1 to T2, while the de-pressurizing valves 56 are activated, i.e. for connecting the actuator of the aerodynamic device 30 to the first pressure control volume 55a, in a second time interval T3 to T4, subsequent to the first time interval T1 to T2. This produces the transients in the measured temporal course 110 of the pressure shown in the second diagram 102 and in the expected position 140 of the aerodynamic device 30 shown in the third diagram 103. The transients correspond to ordinate values of pressure and position, respectively, comprised between zero and respective maximum values of pressure and position.

[0099] According to embodiments of the present invention, in each valve pair constituted by the two de-pressurizing valves 56 or by the two pressurizing valves 57, both valves can be activated and deactivated together or one by one. In the latter case embodiments of the present invention can detect differences in the behaviour of the two valves of each pair and therefore be used also to detect a failure in each of the valves.

[0100] According to embodiments of the present invention, the operative status of the aerodynamic device 30 is derived by looking at the high frequency content in a frequency spectrum of the pressure signal. An aerodynamic device 30 when activated induces some “white noise” in the pressure into the hose because of flow forces, which could be detected by a Fast Fourier Transform (FFT) analysis.

[0101] FIG. 6 shows the normal case, where the aerodynamic device 30 is behaving as expected. The pressure transient 110 has a specific pattern, which is the desired pressure temporal course 120, i.e. the expected pattern for the pressure signal as a function of the valve states. This pattern can be obtained by data driven models, where the pattern will be the average pattern of several valve activations and deactivations, or it could be based on simulation models. Consequently, the actual position 130 of the aerodynamic device 30 has also an expected trapezoidal pattern starting at time T1 from ordinate “0” (second retracted configuration), reaching through a ramp the maximum ordinate (first protruded configuration) and then reaching again second retracted configuration) at a time T5 comprise in the second time interval T3 to T4.

[0102] FIG. 7 shows a first faulty case, corresponding to a case where the aerodynamic device 30 is blocked in the second retracted configuration (the actual position 130 of the aerodynamic device 30 is always at the value “0” in the third diagram 103). In this case the measured temporal course 110 builds up faster than expected, as highlighted by the difference 150 between the measured temporal course 110 and the desired pressure temporal course 120 during the first time interval T1 to T2. The measured temporal course 110 also decreases faster than expected. As shown at the beginning of the second time interval T3 to T4. By detecting the difference 150, the method according to embodiments of the present invention can derive a “Faulty Closed” status of the aerodynamic device 30.

[0103] FIG. 8 shows a second faulty case, corresponding to a case where the aerodynamic device 30 is blocked in the first protruded configuration (the actual position 130 of the aerodynamic device 30 is always at the maximum value in the third diagram 103, after the starting time T3 of the second time interval T3 to T4). In this case the pressure measured temporal course 110 decreases faster than expected in the second time interval T3 to T4. This is highlighted by the difference 151 between the measured temporal course 110 and the desired pressure temporal course 120 during the second time interval T3 to T4. By detecting the difference 151, the method according to the present invention can derive a “Faulty Open” status of the aerodynamic device 30.

[0104] 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.

[0105] 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.