ROTOR FOR A WIND TURBINE, WIND TURBINE AND ASSOCIATED METHOD

Abstract

A rotor for a wind, to a wind turbine and to a method for increasing the yield of a rotor of a wind turbine. In particular, a rotor for a wind turbine, comprising at least one rotor blade, having a rotor blade trailing edge and rotor blade leading edge extending between the rotor blade root and the rotor blade tip over a rotor blade length, a profile depth established between the rotor blade leading edge and the rotor blade trailing edge, and an adjustable pitch angle, wherein the rotor blade has at least one profile element which is arranged on the rotor blade trailing edge or in the region adjacent to the rotor blade trailing edge for increasing the profile depth by an enlargement value, characterized by a control unit for determining a pitch angle to be set, which is configured to determine the pitch angle to be set depending on the enlargement value.

Claims

1. A rotor for a wind turbine, the rotor comprising: a rotor blade coupled to the rotor, the rotor blade having: a rotor blade root and a rotor blade tip, a rotor blade trailing edge and rotor blade leading edge extending between the rotor blade root and the rotor blade tip over a rotor blade length, a profile depth between the rotor blade leading edge and the rotor blade trailing edge, an adjustable pitch angle, and a profile element arranged on the rotor blade trailing edge or in a region adjacent to the rotor blade trailing edge for increasing the profile depth by an enlargement value, and a controller configured to determine a pitch angle in dependence on the enlargement value.

2. The rotor as claimed in claim 1, wherein the controller is configured to determine the pitch angle to be set depending on two or more enlargement values and/or on a profile of the enlargement value.

3. The rotor as claimed in claim 2, wherein the controller is configured to determine the pitch angle to be set in indirect or direct dependence on the enlargement value.

4. The rotor as claimed in claim 3, wherein the controller is configured to take into account an induction factor, a wind speed in a rotor blade plane, at least one local angle of attack, and/or an air density when determining the pitch angle.

5. The rotor as claimed in claim 1 wherein: the rotor blade has a maximum angle of attack having a substantially separation-free flow around the rotor blade, and the controller is configured to take into account the maximum angle of attack, which is increased by the profile element, when determining the pitch angle to be set.

6. The rotor as claimed in claim 1, wherein the controller is configured to control the pitch angle to be set in such a way that an angle-of-attack reserve of the rotor blade is set substantially independently of the enlargement value, wherein the angle-of-attack reserve is defined as an angle between a maximum angle of attack and an angle of attack that is currently applied based on the setting of the pitch angle, wherein the maximum angle of attack causes a substantially separation-free flow around the rotor blade.

7. The rotor as claimed in claim 6, wherein the controller is configured to set the pitch angle taking into account a maximum angle of attack, wherein the maximum angle of attack is increased by the profile element and/or an increased stall angle.

8. The rotor as claimed in claim 1, wherein the controller takes into account design loads of the wind turbine for determining the pitch angle, wherein the controller is configured to compare operating loads of the wind turbine with the design loads.

9. The rotor as claimed in claim 1, wherein the enlargement value is less than or equal to 20% of the profile depth.

10. The rotor as claimed in claim 1, wherein the profile element extends at least in sections over the rotor blade length.

11. The rotor as claimed in claim 1, wherein the profile element is arranged in a region of between 70% and 100% of a relative rotor blade length.

12. The rotor as claimed in claim 1, wherein a distal section of the at least one profile element has a serrated profile.

13. The rotor as claimed in claim 1, wherein a distal section of the at least one profile element has a trapezoidal profile.

14. The rotor as claimed in claim 1, wherein the profile element is adjustable such that a first enlargement value and a second enlargement value are configured to be set, wherein the first enlargement value is smaller than the second enlargement value, and wherein the controller is configured to determine a smaller pitch angle when setting the second enlargement value than when setting the first enlargement value.

15. A wind turbine comprising: a tower, and the rotor as claimed in claim 1 coupled to the tower.

16. A method comprising: increasing a yield of a rotor of a wind turbine having an adjustable pitch angle, a rotor blade trailing edge, and a rotor blade leading edge extending between a rotor blade root and a rotor blade tip over a rotor blade length, and the rotor blade having a profile depth between the rotor blade leading edge and the rotor blade trailing edge, wherein increasing comprises: arranging at least one profile element the rotor blade trailing edge or in a region adjacent to the rotor blade trailing edge, wherein the at least one profile element for increasing the profile depth by at least one enlargement value, determining the pitch angle depending on the enlargement value, and adjusting the pitch angle to the determined pitch angle.

17. The rotor as claimed in claim 11, wherein the enlargement value is less than or equal to 15% of the profile depth.

18. The rotor as claimed in claim 17, wherein the enlargement value is less than or equal to 10% of the profile depth.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0046] Preferred exemplary embodiments will be explained by way of example on the basis of the appended figures. In the figures:

[0047] FIG. 1: shows a schematic view of a wind turbine;

[0048] FIG. 2: shows a schematic view of a rotor blade;

[0049] FIG. 3: shows a schematic view of a sub-section of a rotor blade trailing edge;

[0050] FIG. 4: shows a further schematic view of a sub-section of a rotor blade trailing edge;

[0051] FIG. 5: shows schematic partial views of profile elements;

[0052] FIG. 6: shows schematic profiles of axial induction factors;

[0053] FIG. 7: shows schematic profiles of angles of attack;

[0054] FIG. 8: shows schematically a flow diagram of a method.

[0055] In the figures, functionally identical or functionally similar elements are provided with the same reference signs.

DETAILED DESCRIPTION

[0056] FIG. 1 shows a schematic illustration of a wind turbine. The wind turbine 100 has a tower 102 and a nacelle 104 on the tower 102. An aerodynamic rotor 106 having three rotor blades 108 and having a spinner 110 is provided on the nacelle 104. During the operation of the wind turbine 100, the aerodynamic rotor 106 is set in rotational motion by the wind and thereby also rotates an electrodynamic rotor or runner of a generator, which is coupled directly or indirectly to the aerodynamic rotor 106. The electric generator is arranged in the nacelle 104 and generates electrical energy.

[0057] The pitch angles of the rotor blades 108 can be varied by way of pitch motors at the rotor blade root of the respective rotor blades 108. The rotor blades 108 each have a rotor blade root and a rotor blade tip, between which the rotor blades 108 extend with a rotor blade length. In addition, the rotor blades 108 each have a rotor blade trailing edge and/or a blade leading edge extending over the rotor blade length. A profile depth is established in each case between the rotor blade leading edge and the rotor blade trailing edge. To control the pitch angles of the rotor blades 108, a controller 200 is provided, which can be designed as a separate controller 200 of the pitch angle of the rotor blades 108 or as part of the control of the wind turbine 100. FIG. 2 shows a schematic view of a rotor blade 1, which is an example of one of the rotor blades 108 which are shown in FIG. 1. The rotor blade 1 extends from a rotor blade root 4 to a rotor blade tip 5, such that a rotor blade length 10 is established. The rotor blade 1 extends substantially orthogonally to the rotor blade length 10 from a rotor blade leading edge 2 to a rotor blade trailing edge 3. A profile depth 13 is established between the rotor blade leading edge 2 and the rotor blade trailing edge 3. A profile element 6, which projects from the rotor blade trailing edge 3, is arranged schematically on the rotor blade trailing edge 3.

[0058] FIG. 3 shows a schematic view of a sub-section of a rotor blade trailing edge 3. The profile element 6 is arranged at least in a sub-section of the rotor blade trailing edge 3. The profile element 6 shown has a continuous profile section 7. The profile element 6 projects from the rotor blade trailing edge 3. In the present case, the projecting length is the enlargement value L.

[0059] FIG. 4 shows a further schematic partial view of a rotor blade trailing edge. The profile element 6 shown here has, in addition to a continuous profile section 7, a serrated profile section 8. The enlargement value L is added up from the projecting length of the continuous profile section 7 and the projecting length of the serrated profile section 8, wherein the projection up to the serration tips 12 is taken into account. The serrations 9 of the serrated profile section 8 each have a serration base 11 and the serration tip 12 already mentioned above. A serration with a serration height Z extends between the serration base and the serration tip 12.

[0060] FIG. 5 shows schematic partial views of profile elements. The serrated profile section 8′ has serrations which extend from a serration base 11′ to a serration tip 12′. The serrated profile section 8′ has serrations arranged uniformly next to one another. The serrated profile section 8″ has pin-shaped serrations which are distinguished by a rectangular section and a serration-shaped section arranged thereon. The serrations have a serration base 11″ and a serration tip 12″.

[0061] FIG. 6 shows schematic profiles of axial induction factors. The relative rotor blade length 21 is plotted on the abscissa. The axial induction factor 20 is plotted on the ordinate. The axial induction factor 0.33, which is also referred to as the Betz optimum, is entered as the constant. A total of six different curves are depicted in the diagram. Three curves are depicted for a first wind speed v1 and three further curves for a second wind speed v2. The first wind speed v1 is lower than the second wind speed v2.

[0062] For each wind speed, the axial induction factor applied at a relative rotor blade position in each case is plotted for in each case three different enlargement values. The induction factors along the rotor blade length are therefore plotted for two different wind speeds for a first profile element with an enlargement value L1, for a second profile element with an enlargement value L2 and for a third profile element with the enlargement value L3. In the diagram, the curves corresponding to the different enlargement values are denoted by L1, L2 and L3.

[0063] The profile elements are attached between 70% and 100% of the relative rotor blade length. It can be seen that, with a greater enlargement value, a greater axial induction or a higher axial induction factor 20 is achieved. In the case of the low wind speed v1, this leads to an overinduction in the case of an enlargement value L2 and L3. As a result, for example at the wind speed v1, the angle of attack for a profile element can be reduced with a first and second enlargement value, such that the Betz optimum at 0.33 can again be achieved.

[0064] FIG. 7 shows schematic profiles of angles of attack. The relative rotor blade length 23 is again plotted on the abscissa and the locally applied angle of attack 22 is plotted on the ordinate. It can be seen that, with increasing length of the profile elements, which is shown here by the enlargement values L1-L3, a lower local angle of attack is achieved. This is achieved by the fact that a longer profile element with a greater enlargement value achieves a greater reduction in the wind speed in the rotor plane, such that a smaller local angle of attack is set, taking into account the peripheral speed.

[0065] At the second wind speed v2, it can also be seen that the influence of the profile elements arranged between 70% and 100% also acts on the region in which no profile element is arranged, namely in the region between 40% and 70% of the relative rotor blade length.

[0066] The relationships between the induction and the enlargement value of the profile element that are shown here make it clear that it is desirable to take the enlargement value into account during the determination of an optimal pitch angle by the controller 200. As a result, the aerodynamic performance of the rotor can be improved, as can the yield of the wind turbine.

[0067] FIG. 8 schematically shows a flow diagram of a method 300 for increasing the yield of a rotor, for example the above-described rotor 106 of the wind turbine 100.

[0068] In a step S310, a profile element, for example a profile element 6 described above, is arranged to increase the profile depth by at least one enlargement value L. Step S310 is optional in the method 300 and may, for example, also already be carried out during the assembly of the wind turbine. Alternatively, the replacement of a profile element and the adjustment of the enlargement value L, for example in the context of maintenance of the wind turbine, are also described with this step.

[0069] In a step S320, the pitch angle to be set is determined depending on the enlargement value L of the profile element arranged in step S310. The regulation of the wind turbine in this way enables, as described, a yield-optimized operation of the wind turbine.

[0070] Furthermore, the method may include a step that comprises changing the enlargement value L during operation. The change in the enlargement value L can be made possible, for example, by a movable and/or extendable profile element. An actuator can be provided for this purpose.

REFERENCE SIGNS

[0071] 1 Rotor blade [0072] 2 Rotor blade leading edge [0073] 3 Rotor blade trailing edge [0074] 4 Rotor blade root [0075] 5 Rotor blade tip [0076] 6 Profile element [0077] 7 Continuous profile section [0078] 8 Serrated profile section [0079] 9 Serrations [0080] 10 Rotor blade length [0081] 11 Serration base [0082] 12 Serration tip [0083] 20 Axial induction factor [0084] 21, 23 Relative rotor blade length [0085] 22 Angle of attack [0086] 100 Wind turbine [0087] 102 Tower [0088] 104 Nacelle [0089] 106 Rotor [0090] 108 Rotor blades [0091] 110 Spinner [0092] 200 Controller [0093] 300 Method [0094] S310 Arranging a profile element [0095] S320 Determining the pitch angle [0096] L Enlargement value [0097] Z Serration height