Wind turbine

Abstract

A variable pitch controlled wind turbine comprising a tower, a nacelle mounted on the tower, a hub rotatably mounted on the nacelle, and at least three wind turbine blades wherein each wind turbine blade extends between a root end and a tip end connected to the hub via a pitch mechanism; the wind turbine further comprises at least three blade connection members, each blade connection member extending between a connection point on one wind turbine blade and a connection point towards an adjacent wind turbine blade, the connection points each located at a connection region of the respective blade; each wind turbine blade includes a spar cap extending in a spanwise outboard direction of the blade between a root end and a tip end, and a reinforcement member having an anchor end and a connection end, the connection end having a connection point from which the reinforcement member extends continuously to the anchor end, the anchor end overlapping a portion of the spar cap located outboard of the connection point, therefore, loads can be transmitted between the spar cap and the corresponding connecting component.

Description

Technical Field

[0001] The invention relates to a pitch-controlled wind turbine and a method of manufacturing a wind turbine blade of a wind turbine. Background Art

[0002] Wind turbine blades are subject to various loads, such as aerodynamic loads generated by the wind. These may include air pressure on the wind turbine blades and changing wind speed and direction. The wind turbine will also be subject to the weight of the wind turbine blades themselves.

[0003] Due to the increase in the amount of energy produced, there is a continuous drive to produce larger wind turbine blades. However, as the size of wind turbine blades continues to increase, the loads on the wind turbine blades also continue to increase. The increased loads often require further strengthening of the blades, however, this strengthening also increases the weight of the blades, with the loads acting on the blades further increasing. Summary of the invention

[0004] A first aspect of the present invention provides a pitch-controlled wind turbine, the wind turbine comprising: a tower; a nacelle mounted on the tower; a hub rotatably mounted on the nacelle; and at least three wind turbine blades, wherein each wind turbine blade extends between a tip end and a root end connected to the hub via a pitch mechanism; the wind turbine further comprises at least three blade connection members, each blade connection member extending from a connection point on one wind turbine blade toward a connection point on an adjacent wind turbine blade, each of the connection points being located at a connection region of a corresponding blade; and each wind turbine blade comprises: a spar cap extending in a spanwise direction of the blade between the root end and the tip end; and a reinforcement member having an anchor end and a connection end, the connection end having the connection point, the reinforcement member extending continuously from the connection point to the anchor end, the anchor end overlapping a portion of the spar cap so as to transfer load between the spar cap and the corresponding connection member.

[0005] The anchor end may overlap the portion of the spar cap outboard of the connection point.

[0006] The reinforcement member may be integral with the spar cap.The reinforcement member may be co-bonded with the spar cap.

[0007] The reinforcement member may include a fiber reinforced composite material.

[0008] The majority of the fibers in the fiber reinforced composite material may generally be oriented toward the span direction of the blade. The majority of the fibers may be oriented within 20 degrees of the span direction of the blade.

[0009] The reinforcing member may extend around a portion of the connection point.The fibres of the reinforcing member may be continuous around the portion of the connection point.

[0010] The width of the reinforcement member in the chordwise direction between the leading edge and the trailing edge of the blade may increase outwardly from the connection point to an inboard edge of the anchor end.

[0011] The reinforcement member may extend from the connection end and overlap an inner side of the spar cap and an outer side of the spar cap.

[0012] The spar cap may have a longitudinal axis which is offset in the direction of the thickness of the blade on either side of the stiffening member.

[0013] The spar cap may be continuous between the root end and the tip end.

[0014] The connection region may have a leading edge in front of a leading edge of the blade inside the connection region and in front of a leading edge of the blade outside the connection region. The connection point is located in front of a leading edge of the blade inside the connection region and in front of a leading edge of the blade outside the connection region.

[0015] The leading edge of the connection region may merge smoothly into the leading edge of the blade outside the connection region.

[0016] The leading edge of the connection point may be located on the pressure side of the blade.

[0017] Each connection point may include a connector. The connector may be embedded in the reinforcement member.

[0018] The reinforcing member may include a core material. The thickness of the core material may vary between the connection end and the anchor end to accommodate the thickness of the reinforcing member.

[0019] The thickness of the core material may gradually decrease away from the connection end so as to decrease the thickness toward the anchor end.

[0020] Each connection point may include a load-bearing structure configured to provide freedom of movement of the connection member about at least one axis.

[0021] A first connection member and a second connection member may extend from the connection point.

[0022] The wind turbine may be an upwind wind turbine.

[0023] A second aspect of the invention provides a method of manufacturing a wind turbine blade, the method comprising: providing a blade mould, the blade mould being shaped to form a blade having a connection area; laying a reinforcement member into the blade mould at the connection area; placing a spar cap into the mould and on top of the reinforcement member; placing a connector into the mould at the connection end of the reinforcement member so that the reinforcement member extends continuously from the connector to an anchor end of the reinforcement member, wherein the anchor end overlaps a portion of the spar cap, and wherein the connector is used to be connected to a corresponding connector on an adjacent wind turbine blade via the connection member.

[0024] The reinforcement member may include a first portion and a second portion; the method includes placing the spar cap and connector into the mold and onto the first portion; and folding the second portion of the reinforcement member over the spar cap and connector so that the reinforcement member surrounds the connector, wherein the first and second portions of the reinforcement member are placed on opposite sides of the spar cap.

[0025] Prior to folding the second portion of the reinforcement member over the spar cap and connector, the method may include placing a core material on the first portion of the reinforcement member and folding the second portion of the reinforcement member over the spar cap and connector, wherein the core material extends from the connector toward the spar cap.

[0026] The method of the second aspect may be used to manufacture a blade for a wind turbine of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0028] Figure 1 shows a front view of a wind turbine according to a first example;

[0029] Figure 2 A side view of a wind turbine is shown;

[0030] Figure 3 A wind turbine according to a second example is shown;

[0031] Figure 4 A wind turbine blade is shown;

[0032] Figure 5 A connection region of a wind turbine blade is shown, from which a connection member extends;

[0033] Figure 6 A cross section of a blade is shown;

[0034] Figure 7 A reinforcement member extending from the connection point to the spar cap of the blade is shown;

[0035] Figure 8 Shows Figure 8 A close-up view of the reinforcement member;

[0036] Fig. 9 shows a section AA of the spar cap at the location where the stiffening member overlaps the spar cap;

[0037] Fig.10 A section BB of the reinforcing member is shown;

[0038] Fig.11 shows a section CC of the reinforcing member at the connection point;

[0039] Fig.12 A connector for connecting regions is shown;

[0040] Fig.13 A cross section of the connector is shown;

[0041] Fig.14 A blade mould is shown;

[0042] Fig.15 shows the reinforcement members laid into the mould;

[0043] Fig.16 The spar caps are shown laid up into the mould;

[0044] Fig.17 The core material is shown placed into the mold;

[0045] Fig.18 A portion of the reinforcement member is shown folded over the core material and the reinforcement member;

[0046] Fig.19 An alternative arrangement with two reinforcement members is shown;

[0047] Fig. 20 Shows Fig.19 Plan view of the reinforcement member;

[0048] Fig.21 An alternative example of a connector is shown;

[0049] Fig. 22 Shows Fig.21 The cross section of the connector. DETAILED DESCRIPTION

[0050] In this specification, terms such as leading edge, trailing edge, pressure surface, suction surface, thickness and chord are used. Although these terms are well known and understood by those skilled in the art, for the avoidance of doubt, definitions are given below.

[0051] The term leading edge is used to refer to the edge of the blade which will be located at the front of the blade when the blade rotates in the forward direction of rotation of the wind turbine rotor.

[0052] The term trailing edge is used to refer to the edge of a wind turbine blade which will be located behind the blade when the blade rotates in the forward direction of rotation of the wind turbine rotor.

[0053] The chord of a blade is the straight line distance from the leading edge to the trailing edge in a given cross section perpendicular to the spanwise direction of the blade. The term chordwise is used to refer to the direction from the leading edge to the trailing edge and vice versa.

[0054] The pressure surface (or windward surface) of a wind turbine blade is the surface between the leading edge and the trailing edge which, when the blade is in use, has a higher pressure than the suction surface of the blade.

[0055] The suction surface (or leeward surface) of a wind turbine blade is the surface between the leading edge and the trailing edge which, when the blade is in use, will have a lower pressure acting upon it than the pressure surface.

[0056] The thickness of a wind turbine blade is measured perpendicular to the chord of the blade and is the maximum distance between the pressure surface and the suction surface in a given cross section perpendicular to the spanwise direction of the blade.

[0057] The term spanwise is used to refer to the direction from the root end of a wind turbine blade to the tip end of the blade, or vice versa. When the wind turbine blade is mounted on a wind turbine hub, the spanwise direction and the radial direction will be substantially the same.

[0058] The term spar cap is used to refer to the longitudinal, generally spanwise extending reinforcement member of the blade. The spar cap may be embedded in the blade shell, or may be attached to the blade shell. The spar caps on the windward side and the leeward side of the blade may be combined by one or more shear webs extending through the inner hollow space of the blade. The blade has more than one spar cap on one of the windward side and the leeward side. The spar cap may form a part of the longitudinal reinforcement spar or support member of the blade. In particular, the spar cap may form a part of a load-bearing structure extending in the longitudinal direction, which carries the flap direction bending loads of the blade.

[0059] The term outboard refers to the radial (spanwise) direction from the hub of the blade towards the tip of the blade. The term inboard refers to the radial direction from the tip of the blade towards the hub.

[0060] Figure 1 and Figure 2 A pitch-controlled wind turbine 1 according to a first example is shown. Figure 1 is a front view of the wind turbine 1, and Figure 2 is a side view of a wind turbine 1. The wind turbine 1 comprises a tower 2 and a nacelle 3 mounted on the tower 2. A hub 4 is rotatably mounted on the nacelle 3 and carries three wind turbine blades 5 extending outward from the nacelle 3. Figure 1 and Figure 2 The example shown in has three blades 5 , but it will be appreciated that other numbers of blades 5 are possible.

[0061] When wind blows towards the wind turbine 1 , the wind turbine blades 5 generate lift, which causes a generator (not shown) in the nacelle 3 to generate electrical energy.

[0062] It will be appreciated that the depicted wind turbine 1 may be any suitable type of wind turbine 1. The wind turbine 1 shown is an upwind wind turbine, but it will be appreciated that the wind turbine 1 may also be a downwind wind turbine. The wind turbine 1 may be an onshore wind turbine, such that the foundation is embedded in the ground, or the wind turbine 1 may also be an offshore facility, in which case the foundation will be provided by a suitable offshore platform.

[0063] Three blade connection members 6 interconnect adjacent wind turbine blades 5 between connection points 7 on the wind turbine blades 5. The connection members 6 are cables, such as steel cables. A pretensioning member 8 extends between one of each of the blade connection members 6 and a common point arranged at or near the hub 4. Figure 1 and Figure 2 In the example shown in FIG. 4 , the pretensioning member 8 extends to the hub 4 . The pretensioning member 8 is configured to provide a pretension in the blade connection member 6 .

[0064] The pre-tensioned blade connection members 6 support the wind turbine blades 5 against each other in a sense that the loads on the wind turbine blades 5, in particular the edge loads and flap loads, are “shared” among the wind turbine blades.

[0065] Figure 3 is a side view of a pitch-controlled wind turbine 1 according to a second example. Figure 3 The wind turbine 1 is similar to Figure 1 and Figure 2 The wind turbine 1 is described above and therefore the same features will not be described in detail here.

[0066] The pre-tensioning member 8 may be directly or indirectly connected to the hub 4. Figure 3As shown in FIG. 1 , the pretensioning member 8 may be connected proximate to the hub 4 and connected to a hub member 9 extending from the hub 4 generally in a direction defined by the axis of rotation of the hub 4. Figure 1 and Figure 2 Compared to the example of FIG. 4 , the connection point of the pretensioning member 8 is further away from the hub 4 and thus further away from where the wind turbine blade 5 is connected to the hub 4. As a result, the pretensioning member 8 may also pull the blade connection member 6 away from the hub 4 and the tower 2. This may also cause the wind turbine blade 5 to be pulled in this direction, thereby also reducing the edge and flap loads at the root of the wind turbine blade 5 and ensuring a tower clearance, which is similar to the clearance obtained when the cone angle is introduced.

[0067] The wind turbine blade 5 has a root end 11 close to the hub 4 and a tip end 12 away from the hub 4, the root end being adapted to be connected to the hub 4 via a pitch mechanism. The blade 5 comprises a leading edge 13 and a trailing edge 14 extending between the respective root end 11 and the tip end 12. The blade 5 comprises a suction side 15 and a pressure side 16 (see Figure 4 and Figure 5 ). The thickness dimension of the blade 5 extends between the suction side 15 and the pressure side 16 .

[0068] Each blade 5 may have a cross-section having a generally circular profile near the root end 11. The blade 5 may transition from a circular profile to an airfoil profile moving outwardly from the root end 11 of the blade 5. The blade 5 may include a "shoulder" 28 located outboard of the root end 11, which is the widest portion of the blade where the blade 5 has a maximum chord length. The blade 5 may have an airfoil profile with a gradually decreasing thickness at the outboard portion of the blade 5. The gradually decreasing thickness may extend from the shoulder 28 to the tip 12.

[0069] exist Figure 4 In the example shown in , the connection point 7 is located at about 40% of the blade length in the radial direction from the root end 11. However, it will be appreciated that the connection point 7 may be located at any position along the blade 5. The connection point 7 may be located between 10% and 60% of the length of the wind turbine blade 5 from the root end 11 to the tip end 12 in the radial direction, but is preferably located radially inside 50% of the length of the wind turbine blade 5 from the root end 11 to the tip end 12, and more preferably located radially inside 45% of the length of the wind turbine blade 5 from the root end 11 to the tip end 12.

[0070] The connection point 7 is located at the connection area 10 of the blade 5. The connection area 10 can extend the leading edge 21 of the blade 5 located inside the connection area 10 and the leading edge 22 of the blade 5 located outside the connection area 10 forward. The connection area 10 allows the blade 5 to be continuous from the root end 11 to the tip end 12.

[0071] exist Figure 4 In the example shown in , the leading edge 23 of the connection area 10 smoothly merges into the leading edge 22 of the blade 5 located outside the connection area 10. For example, the leading edge 23 of the connection area 10 may be curved from the connection point 7 to the leading edge 22 of the blade 5 located outside the connection area 10. However, it will be understood that in other examples, the leading edge 23 of the connection area 10 may transition sharply into the leading edge 22 of the blade 5 located outside the connection area 10, for example forming an apex between the leading edges 22, 23.

[0072] The leading edge 21 inside the leading edge 23 of the connection region 10 is shown as abruptly transitioning into the leading edge 23 in the connection region 10, wherein an apex 24 is formed between the leading edges 21, 23. Providing a smooth transition can reduce stress concentrations, while providing an overall sharp transition can provide additional clearance for the connection member 6 or other components. However, it will be understood that the leading edge 23 of the connection region 10 can smoothly blend into the leading edge 21 of the blade 5 located inside the connection region 10. For example, the leading edge 23 of the connection region 10 can bend from the connection point 7 to the leading edge 21 of the blade 5 located inside the connection region 10.

[0073] Similarly, the connection region 10 may extend outwardly from the blade 5 so as to increase the local thickness of the blade 5 at the connection region 10 relative to the thickness of the blade 5 inside the connection region 10 and outside the connection region 10. Figure 5 In the stereogram Figure 6 Along the middle Figure 5 The connection point 7 can be arranged at a position where the thickness-chord ratio of the wind turbine blade 5 is between 20% and 50%. The increase in thickness of the blade 5 can be more clearly shown on the pressure side 16 of the blade 5, so that the leading edge of the connection area extends outwardly from the blade on the pressure side of the respective blade.

[0074] like Figure 5 As shown in , the thickness of the blade 5 at the connection area 10 can smoothly transition to the portion of the blade 5 located outside the connection area 10, and can abruptly transition to the portion of the blade 5 located inside the connection area 10. Providing a smooth transition can reduce stress concentration, while providing an overall sharp transition can provide additional clearance for the connection member 6 or other components. However, it should be understood that the thickness change at either end of the connection area 10 can be a smooth transition or a sharp transition.

[0075] When the wind turbine blade 5 rotates about the nacelle with the hub 4, extending the connection region 10 so that the leading edge 23 of the connection region 10 extends forward of the inner and outer sides of the leading edges 21, 22 of the blade 5 provides additional clearance for the connection member 6, thereby increasing the range of motion of the blade 5 relative to the connection member 6. Similarly, increasing the thickness of the blade 5 at the connection region 10, and more specifically, providing a more significant thickness increase on the pressure side 16 of the blade 5, provides additional clearance for the connection member 6.

[0076] like Figure 7 As shown in , each wind turbine blade 5 has a spar cap 25 extending between the root end 11 and the tip end 12 along the span direction of the blade 5. The spar cap 25 may be continuous across the connection region 10. The spar cap 25 may be continuous between the root end 11 and the tip end 12 along substantially its entire length.

[0077] The reinforcement member 31 extends from the connection point 7 to the spar cap 25. In particular, the reinforcement member 31 has an anchor end 32 overlapping a portion of the spar cap 25 and a connection end 33 having the connection point 7, so that the reinforcement member 31 extends continuously from the connection point 7 to the anchor end 32, thereby transferring loads between the spar cap 25 and the corresponding connection member 6.

[0078] Preferably, if Figure 7 As shown in FIG, the anchor end 32 overlaps the spar cap 25 at a position outboard of the connection point 7, so that the reinforcement member 31 extends outward to resist the generally inboard load on the connection member 6. However, it will be understood that the anchor end 32 may overlap the spar cap 25 at any spanwise position, including inboard of the connection point 7.

[0079] The reinforcement member 31 may be formed of any suitable material (e.g., metal), but preferably comprises a fiber reinforced composite material. The fiber reinforced composite material may include glass and / or carbon fibers. The fiber reinforced composite material may be formed of a prepreg or dry fiber preform.

[0080] When the fibers are oriented along the load direction, the fiber reinforced composite material has increased stiffness. In the present case, most of the fibers in the fiber reinforced composite material may be oriented toward the span direction of the blade as a whole. Preferably, most of the fibers are oriented within 20 degrees in the span direction of the blade 5. Most may mean that more than 50% of the fibers are oriented along the span direction of the blade 5, but preferably, more than 80% of the fibers are oriented along the span direction of the blade 5.

[0081] The reinforcement member 31 may extend from the connection point 7 to the spar cap 25 on the pressure side 16 of the blade 5. The reinforcement member 31 may only extend from the connection point 7 to the spar cap 25 on the pressure side 16 of the blade 5, so that the reinforcement member 31 does not extend to the spar cap 25 on the suction side 15 of the blade 5.

[0082] The width of the reinforcement member 31 may increase from the connection end 33 to the anchor end 32. The width of the reinforcement member 31 may be measured along the chord direction of the blade 5, so that the width of the reinforcement member 31 increases in the span direction of the blade 5. Figure 8 As best shown in FIG. 1 , the width of the reinforcement member 31 in the chord-wise direction may increase outwardly from the connection point 7 to the inner edge 32 a of the anchor end 32 .

[0083] As previously mentioned, the anchor end 32 of the reinforcement member 31 overlaps a portion of the spar cap 25. The anchor end 32 may overlap the inner side 25a of the spar cap 25 (i.e., the side of the spar cap 25 away from the outer aerodynamic surface of the blade 5) and / or the outer side 25b of the spar cap 25 (i.e., the side of the spar cap 25 adjacent to the outer aerodynamic surface of the blade 5). Overlapping with the spar cap 25 improves load transfer between the anchor end 32 of the reinforcement member 31 and the spar cap 25 due to the large contact area. Fig. 9 In the example shown in , the reinforcement member 31 overlaps the inner side 25a of the spar cap 25 and the outer side 25b of the spar cap 25, so that within a given span, the reinforcement member 31 is attached to a larger surface area of ​​the spar cap 25 rather than overlapping one or the other of the inner and outer sides 25a, 25b. To accommodate the reinforcement member 31, the spar cap 25 may have a longitudinal axis that is offset along the blade thickness direction on either side of the reinforcement member at the location where the reinforcement member 31 overlaps the spar cap 25. Fig. 9 The spar caps 25 are shown offset towards the outer surface of the blade 5. This may be preferred to maintain the outer aerodynamic profile of the blade. The spar caps 25 may be offset near the inboard end 35a of the anchor end 32, and offset near the outboard end 35b of the anchor end 32. It will be appreciated that in examples where the anchor end 32 overlaps the outboard 25a of the spar cap 25 and / or the outboard 25b of the spar cap 25, the spar caps 25 may be similarly offset.

[0084] The thickness of the reinforcing member 31 may vary between the connection point 7 at the connection end 33 and the anchor end 32. Fig. 9 , Fig.10 and Fig.11 As can be seen in FIG. 1 , the thickness may vary from a first thickness 37a adjacent the connection end 33, where the fiber reinforced composite material extends on either side of the connector 40 of the connection point 7 (e.g., the connection point 7 is connected to the fiber reinforced composite material), to a second thickness 37b adjacent the anchor end 32. Fig.12 and Fig.13 37b), the fiber reinforced composite material extends to the spar cap 25. The first thickness 37a may be greater than the second thickness 37b. The relative change in thickness may at least partially account for the difference between the thickness of the connector 40 at the connection end 33 and the thickness of the spar cap 25 at the anchor end 32.

[0085] The reinforcement member 31 may include a core material 36. The core material 36 may extend from the connection end 33 toward the anchor end 32. The core material 36 may reduce the amount of fiber reinforced composite material required for the reinforcement member 31. In particular, the core material 36 may facilitate the transition from the thickness at the connection end 33 to the thickness at the anchor end 32. Fig.10 and Fig.11 As shown in FIG. 5 , the thickness of the core 36 may decrease between the inner end 36a and the outer end 36b along the span direction of the blade 5. Fig.10 and Fig.11 As shown in FIG. 8 , the thickness of the core material 36 may gradually become thinner away from the connection end 33 , thereby decreasing in thickness toward the anchor end 32 .

[0086] The use of core material 36 can reduce the weight of reinforcement member 31, for example, core material 36 can be lighter than fiber reinforced composite material. Core material 36 can be foam. Core material 36 can form a support structure for the fiber reinforced composite material of reinforcement member 31 to help keep the fibers of the fiber reinforced material generally straight, or at least avoid having sharp angles that may reduce the load-bearing performance of the fiber reinforced composite material.

[0087] The connector 40 may be embedded in the reinforcing member 31. The reinforcing member 31 may extend around a portion of the connection point 7. The fiber-reinforced composite material may extend around a portion of the connection point 7, wherein the fibers of the reinforcing member 31 are continuous around a portion of the connection point 7. Since the load-bearing capacity of the continuous fibers increases, when the reinforcing member 31 surrounds the connection point 7, the width of the reinforcing member 31 at the connection point 7 contacting the connector 40 may be reduced compared to the reinforcing member 31 that does not surround the connection point 7.

[0088] For example, Fig.11 As shown in FIG. 4 , the fiber reinforced composite material of the reinforcing member 31 may contact the inner portion 40a of the connector 40 instead of the outer portion 40b of the connector 40, so that the fiber reinforced composite material contacts the inner portion of the semi-cylindrical shape of the connector 40. However, it will be understood that the fiber reinforced composite material of the reinforcing member 31 may contact the outer portion 40b of the connector 40 or other portions of the connector 40, depending on the position of the connecting end 33 relative to the anchor end 32.

[0089] As previously mentioned, adjacent wind turbine blades 5 are connected to each other via blade connection members 6 extending from a connection point 7 on one wind turbine blade 5 towards a connection point 7 on an adjacent wind turbine blade 5. Each connection point 7 includes a connector 40 from which one or more connection members 6 extend. The blade connection members 6 may extend from a connection point 7 on one wind turbine blade 5 towards a connection point 7 on an adjacent wind turbine blade 5.

[0090] The connector 40 may be rigidly connected to the connection member 6 and / or the reinforcement member 31. Alternatively, the connection point 7, in particular the connector 40 of the connection point 7, may include a load-bearing structure 42, which is attached to the connection member 6 and provides freedom of movement of the respective connection member 6 around at least one axis. In this way, the connection member 6 may not be rigidly fixed to the reinforcement member 31 at the connection point 7.

[0091] The load-bearing structure 42 may include a coupling element 44 that extends through the connection end 33 of the reinforcement member 31. A bushing 45 may be positioned between the coupling element 44 and the reinforcement member 31, such as Fig.13 , wherein the bushing 45 provides for rotational movement of the coupling element 44 relative to the reinforcement member 31 about its longitudinal axis.

[0092] The load-bearing structure 42 may include a bearing 43 to which the connection member 6 or each connection member 6 is (are) attached. The bearing 43 may provide freedom of movement around two orthogonal directions. The bearing 43 may be a spherical plain bearing 43. Each connection member 6 may be connected to a respective bearing 43, such as Fig.12 as shown in .

[0093] A method of manufacturing a wind turbine blade 5 will now be described.

[0094] A half shell of a wind turbine blade 5 is manufactured in a blade mould 50 . Fig.14 A full length blade mould 50 for forming the pressure side 16 of a blade 5 is shown.

[0095] The fiber reinforcement material layers of the blade skin 48 may be laid up in the mold 50. The reinforcement member 31 is then laid up at the connection area 10 in the blade mold 50. The reinforcement member 31 may include a first portion 31a and a second portion 31b, such as Fig.15 As shown in , only the first portion 31a is laid at the connection area. The second portion 31b can extend inwardly from the first portion 31a so that the second portion is located inside the connection area 10.

[0096] The reinforcement member 31 may be provided as a layer of fiber material such as dry fiberglass or pre-impregnated fiberglass.

[0097] Subsequently, the spar cap 25 is added to the mold 50 and on top of the reinforcement member 31 so as to overlap with the anchor end 32 of the reinforcement member 31. The spar cap 25 may be laid on top of only a portion of the reinforcement member 31, for example, the spar cap 25 may be placed on top of the first portion 31a of the reinforcement member 31, but not on the second portion 31b of the reinforcement member, as shown in FIG. Fig.16 as shown in .

[0098] The core material 36 may be placed on at least a portion of the reinforcing member 31. The core material 36 may be placed on the first portion 31a of the reinforcing member 31, such as Fig.17 as shown in .

[0099] The connector 40 is placed in the mold 50 at the connection end 33 of the reinforcement member 31 so that at least a portion of the reinforcement member 31 extends continuously from the connector 40 to the anchor end 32 of the reinforcement member 31. The core material 36 may extend from the connector 40 toward the spar cap 25.

[0100] like Fig.18 , the second portion 31b of the reinforcement member 31 may be folded over the connector 40 and the spar cap 25. In this manner, the first portion 31a and the second portion 31b of the reinforcement member 31 may be placed on opposite sides of the spar cap 25, and the reinforcement member 31 may surround the connector 40, wherein the first portion 31a and the second portion 31b of the reinforcement member 31 are connected at the inner portion 40a of the connector 40 and extend on either side of the connector 40.

[0101] The first and second portions 31a, 31b of the reinforcement member 31 may have substantially the same size and shape such that the second portion 31b completely overlaps the first portion 31a, but it will be appreciated that the first and second portions 31a, 31b may have different sizes and / or shapes.

[0102] Where any additional parts are added to the blade mould 50 (e.g. additional fibre reinforced composite material in the example where the spar caps 25 are embedded in the outer shell of the blade 5), the outer shell of the blade 5 is cured to form the integral structure. Typically, the spar caps 25 are rigidly formed (i.e. cured fibre reinforced composite material) prior to addition to the mould, in which case the reinforcing members 31 are co-bonded with the spar caps 25, but it will be appreciated that the reinforcing members 31 may be co-cured with at least a portion of the material forming the remainder of the blade 5. The blade outer shell of the suction side 15 of the blade 5 may be formed and attached to the manufactured blade outer shell of the pressure side 16 described above, wherein the blade outer shell of the suction side 15 of the blade 5 is free of the reinforcing members 31 extending from the connection point 7 to the corresponding spar cap 25 of the blade outer shell.

[0103] In an example, the reinforcement member may be provided as a pre-fabricated cured component which is integrated into the blade and attached to the spar cap.

[0104] In some examples, blade 5 may include a plurality of reinforcement members 31 located at substantially the same spanwise position. Fig.19 and Fig. 20 A first reinforcing member 31i and a second reinforcing member 31j are shown. Fig. 20 As shown in FIG. 4 , the common connector 40 may be embedded in the first reinforcement member 31 i and the second reinforcement member 31 j. Alternatively, each of the first reinforcement member 31 i and the second reinforcement member 31 j may be attached to a separate connector 40 .

[0105] like Fig. 20 As shown in FIG. 4 , the bushing 45 may be positioned between the coupling element 44 and each of the first and second reinforcing members 31i, 31j. Alternatively, a common bushing 45 may extend across the coupling element 44 between the first and second reinforcing members 31i, 31j.

[0106] It will be appreciated that the connector 40 may be any suitable element that provides a connection between the reinforcement member 31 and each connection member 6 .

[0107] exist Fig.12 and Fig.13 In the example shown in , the reinforcing member 31 extends from a cylindrical coupling element 44 on which a bushing 45 can be mounted to provide for relative rotation between the coupling element 44 and the reinforcing member 31 , thereby providing for relative rotation between each connecting member 6 and the reinforcing member 31 about at least one axis.

[0108] In alternative examples, the coupling element 44 may be fixedly attached to the reinforcing member 31. The portions 40a, 40b of the connector 40 that contact the fiber reinforced composite material of the reinforcing member 31 may be semi-cylindrical, while the other of the portions 40a, 40b is not cylindrical. In these examples, relative rotation between each connecting member 6 and the reinforcing member 31 may be provided by a bearing structure 42 that includes a link 46 that is rotatable about a pin 47 that extends through the coupling element 44, such as Fig.21 and Fig. 22 It should be appreciated that the bearing structure 42 may provide a respective pin 47 rotatably coupled to each link 46 , or a common pin 47 to which two or more links 46 are attached.

[0109] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A wind turbine with variable pitch control, the wind turbine comprising: Tower; a nacelle, the nacelle being mounted on the tower; a wheel hub, the wheel hub being rotatably mounted on the nacelle; and at least three wind turbine blades, wherein each wind turbine blade extends between a tip end and a root end connected to the hub via a pitch mechanism; The wind turbine further comprises at least three blade connection members, each blade connection member extending from a connection point on one wind turbine blade towards a connection point on an adjacent wind turbine blade, each of the connection points being located at a connection region of a respective blade; and Each wind turbine blade comprises: a spar cap extending in a span-outboard direction of the blade between the root end and the tip end; and a reinforcement member having an anchor end and a connection end, the connection end having the connection point, the reinforcement member extending continuously from the connection point to the anchor end, the anchor end overlapping a portion of the spar cap so as to transfer loads between the spar cap and the corresponding connection member.

2. The pitch-controlled wind turbine according to claim 1, wherein: The anchor end overlaps the portion of the spar cap that is outboard of the connection point.

3. The pitch-controlled wind turbine according to claim 1 or 2, wherein: The reinforcement member is integral with the spar cap and preferably, the reinforcement member is co-bonded with the spar cap.

4. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The reinforcing member includes a fiber-reinforced composite material.

5. The pitch-controlled wind turbine according to claim 4, wherein: Most of the fibers in the fiber reinforced composite material are generally oriented toward the span direction of the blade, and preferably, most of the fibers are oriented within 20 degrees of the span direction of the blade.

6. A pitch-controlled wind turbine according to claim 4 or 5, wherein: The reinforcing member extends around a portion of the connection point, and fibers of the reinforcing member are continuous around the portion of the connection point.

7. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The width of the reinforcement member in the chordwise direction between the leading edge and the trailing edge of the blade increases outwardly from the connection point to an inboard edge of the anchor end.

8. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The reinforcement member extends from the connection end and overlaps an inner side of the spar cap and an outer side of the spar cap.

9. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The spar cap has a longitudinal axis that is offset in a blade thickness direction on either side of the stiffening member.

10. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The spar cap is continuous between the root end and the tip end.

11. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The connection region has a leading edge in front of the leading edge of the blade located inside the connection region and in front of the leading edge of the blade located outside the connection region, and preferably, wherein the connection point is located in front of the leading edge of the blade inside the connection region and in front of the leading edge of the blade outside the connection region.

12. The pitch-controlled wind turbine according to claim 9, wherein: The leading edge of the connection region merges smoothly into the leading edge of the blade outside the connection region.

13. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The leading edge of the connection point is located on the pressure side of the blade.

14. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: Each connection point includes a connector, and the connector is embedded in the reinforcement member.

15. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The reinforcing member comprises a core material, preferably wherein the thickness of the core material varies between the connecting end and the anchor end so as to adapt the thickness of the reinforcing member accordingly.

16. The pitch-controlled wind turbine according to claim 15, wherein: The thickness of the core material gradually decreases away from the connection end so as to decrease the thickness toward the anchor end.

17. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: Each connection point comprises a load-bearing structure configured to provide freedom of movement of the connection member about at least one axis.

18. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: A first connection member and a second connection member extend from the connection point.

19. A pitch-controlled wind turbine according to any one of the preceding claims, wherein: The wind turbine is an upwind wind turbine.

20. A method of manufacturing a wind turbine blade, the method comprising: providing a blade mold shaped to form a blade having a connection region; laying a reinforcement member into the blade mould at the connection region; placing a spar cap into the mold and on top of the stiffening member; A connector is placed into the mold at a connection end of the reinforcement member such that the reinforcement member extends continuously from the connector to an anchor end of the reinforcement member, wherein the anchor end overlaps a portion of the spar cap, and wherein the connector is for coupling to a corresponding connector on an adjacent wind turbine blade via a connection member.

21. The method according to claim 20, wherein: The reinforcing member comprises a first portion and a second portion; the method comprises: placing the spar caps and connectors into the mould and onto the first part, and The second portion of the reinforcement member is folded over the spar cap and the connector such that the reinforcement member surrounds the connector, wherein the first and second portions of the reinforcement member are placed on opposite sides of the spar cap.

22. The method according to claim 21, comprising: Prior to folding the second portion of the reinforcement member over the spar cap and connector, placing a core material on the first portion of the reinforcement member and folding the second portion of the reinforcement member over the spar cap and connector, wherein the core material extends from the connector toward the spar cap.

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