WO2012054937A1

WO2012054937A1 - Field-based test stands for wind turbine blades, and associated systems and methods

Info

Publication number: WO2012054937A1
Application number: PCT/US2011/057545
Authority: WO
Inventors: Myles L. Baker; Kenneth Lee Kaser
Original assignee: Modular Wind Energy, Inc.
Priority date: 2010-10-22
Filing date: 2011-10-24
Publication date: 2012-04-26

Abstract

Systems and methods for testing wind turbine blades are disclosed herein. A method for testing a wind turbine blade in accordance with a particular embodiment includes forming at least a portion of wind turbine rotor by attaching a wind turbine blade to a hub and testing the wind turbine blade by applying a load to at least one of the hub and the wind turbine blade while the wind turbine blade and hub are attached to each other, to deflect the wind turbine blade relative to the hub. After testing the wind turbine blade, the rotor can be installed on a wind turbine.

Description

FIELD-BASED TEST STANDS FOR WIND TURBINE BLADES,

AND ASSOCIATED SYSTEMS AND METHODS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to pending U.S. Provisional Application No. 61/406,095, filed October 22, 2010 and incorporated herein by reference.

TECHNICAL FIELD

[0002] The present technology is directed generally to field-based test stands for testing wind turbine blades, and associated systems and methods.

BACKGROUND

[0003] As fossil fuels become scarcer and more expensive to extract and process, energy producers and users are becoming increasingly interested in other forms of energy. One such energy form that has recently seen a resurgence is wind energy. Wind energy is typically harvested by placing a multitude of wind turbines in geographical areas that tend to experience steady, moderate winds. Modern wind turbines typically include an electric generator connected to one or more wind-driven turbine blades, which rotate about a vertical axis or a horizontal axis.

[0004] In general, larger (e.g., longer) wind turbine blades produce energy more efficiently than do short blades. Accordingly, there is a desire in the wind turbine blade industry to make blades as long as possible. However, long blades create several challenges. For example, long blades are heavy and therefore have a significant amount of inertia, which can reduce the efficiency with which the blades produce energy, particularly at low wind conditions. In addition, long blades are difficult to manufacture and in many cases are also difficult to transport. Accordingly, a need remains for large, efficient, lightweight wind turbine blades, and suitable methods for transporting, assembling and testing such blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a partially schematic, isometric illustration of a wind turbine system having blades configured and tested in accordance with an embodiment of the presently disclosed technology.

[0006] Figure 2 is a partially schematic, isometric illustration of a wind turbine rotor undergoing testing in accordance with an embodiment of the presently disclosed technology.

[0007] Figure 3 is a partially schematic, isometric illustration of a wind turbine rotor undergoing testing in accordance with another embodiment of the presently disclosed technology.

[0008] Figure 4 is a partially schematic, isometric illustration of a wind turbine rotor undergoing testing in accordance with still another embodiment of the presently disclosed technology.

[0009] Figure 5 is a partially schematic, isometric illustration of a wind turbine rotor having blades undergoing distributed load testing in accordance with yet another embodiment of the presently disclosed technology.

[0010] Figure 6 is a partially schematic, isometric illustration of a wind turbine rotor having a blade tested independently of other blades in accordance with another embodiment of the presently disclosed technology.

[0011] Figure 7 is a partially schematic side view of a support that can carry, actuate, and/or anchor wind turbine blades in accordance with an embodiment of the presently disclosed technology.

[0012] Figure 8A is a partially schematic plan view of a test fixture configured to support multiple wind turbine blades in accordance with an embodiment of the presently disclosed technology.

[0013] Figure 8B is a partially schematic side view of the test figure shown in Figure 8A. [0014] Figures 9A-9D are partially schematic end views illustrating wind turbine blades under test in accordance with particular embodiments of the presently disclosed technology.

DETAILED DESCRIPTION

[0015] The presently disclosed technology is directed generally to field-based test stands for testing wind turbine blades, and associated systems and methods. Several details describing structures and/or processes that are well-known and often associated with wind turbine blades and rotors are not set forth in the following description to avoid unnecessarily obscuring the description of the various embodiments of the technology. Moreover, although the following disclosure sets forth several representative embodiments, several other embodiments can have different configurations and/or different components than those described in this section. In particular, other embodiments may have additional elements and/or may lack one or more of the elements described below with reference to Figures 1-9D. In Figures 1-9D, many of the elements are not drawn to scale for purposes of clarity and/or illustration. In several instances, elements referred to individually by a reference number followed by a letter (e.g., 110a, 110b, 110c) are referred to collectively by the reference number without the letter (e.g., 110).

[0016] Figure 1 is a partially schematic, isometric illustration of an overall system 100 that includes a wind turbine 103 having blades 110 configured in accordance with an embodiment of the disclosure. The wind turbine 103 includes a tower 101 (a portion of which is shown in Figure 1), a housing or nacelle 102 carried at the top of the tower 101 , and a generator 104 positioned within the housing 102. The generator 104 is connected to a shaft or spindle carrying a hub 105 that projects outside the housing 102. The blades 110 each include a hub attachment portion 112 at which the blades 110 are connected to the hub 105, and a tip 111 positioned radially or longitudinally outwardly from the hub 105. In an embodiment shown in Figure 1 , the wind turbine 103 includes three blades connected to a horizontally-oriented shaft. Accordingly, each blade 110 is subjected to cyclically varying loads as it rotates between the 12:00, 3:00, 6:00 and 9:00 positions, because the effect of gravity on the blade is different at each position. In other embodiments, the wind turbine 103 can include other numbers of blades connected to a horizontally-oriented shaft, or the wind turbine 103 can have a shaft with a vertical or other orientation. In any of these embodiments, the blades 110 and the hub 105 can together form a rotor 106. The blades 110 can be manufactured and/or assembled in situ, in the field, or otherwise near the tower 101 to reduce the expense and inconvenience of transporting large, fully-assembled blades. The blades 110 can be tested after manufacture/assembly and while mounted to the hub 105, but before the rotor 106 is mounted to the shaft, e.g., as is described further below with reference to Figures 2-7. In other embodiments, multiple blades 110 can be tested together on fixtures other than the hub 105, e.g., as is described further below with reference to Figures 8A-9D.

[0017] Figure 2 is a partially schematic, isometric illustration of an embodiment of the rotor 106 described above with reference to Figure 1. The rotor 106 includes a hub 105 carrying three wind turbine blades 110, shown as a first blade 110a, a second blade 110b, and a third blade 110c. Each of the blades 110 can be manufactured and/or assembled, at least in part, in the field or another location distant from a standard blade manufacturing and testing facility. For example, the blades 110 can be manufactured as segments and transported to a wind turbine installation site for final assembly in accordance with any of the techniques described in co-pending U.S. Provisional Application 61/347,724, filed May 24, 2010 and incorporated herein by reference. In one aspect of an embodiment shown in Figure 2, the blades 110 will not have undergone at least a portion of the testing (e.g., a proof test) that is normally completed on the blade 110 after it is assembled and before it is installed on the wind turbine. Accordingly, as shown in Figure 2, the individual wind turbine blades 110 can be tested in the field while attached to the hub 105 (which operates as a common support structure) in a manner that takes advantage of the hub 105 and/or the other blades 110 while still accomplishing the goals of a typical test procedure. As noted above, the test performed on the wind turbine blades can include a proof test, e.g., a static test performed on the blades as a final quality assurance test on both the blades 110 and the hub 105. In a particular embodiment, the proof test can include testing the blades 110 in the thickness or flapwise direction to confirm the stiffness and strength of the blade in that direction. In other embodiments, tests can be performed along other blade axes, and/or can include tests other than static tests. For example, a modal test could be performed to identify the natural frequencies of the blade/hub assembly, which can be used to validate the mass and stiffness characteristics of the blades. During testing, the hub 105 can carry one or more blades at a time, up to all the blades the hub can carry (e.g., three in an embodiment shown in Figure 2). Accordingly, tests can be performed on a fully or partially bladed rotor.

[0018] As shown in Figure 2, the hub 105 can be anchored or otherwise fixed via a hub support element, e.g., an anchor 220, while the blades 110 can be subjected to test loads (e.g., bending loads) produced by a loading device. For example, the first blade 110a can be loaded by a first actuator 230a, the second blade 110b can be loaded by a second actuator 230b, and the third blade 110c can be loaded by a third actuator 230c (referred to collectively as actuators 230). By anchoring the hub 105 and by testing each blade 110 while the other blades 110 are also attached to the hub 105, techniques in accordance with the present technology can balance and/or counter the forces applied to the blade 110 under test without requiring the support equipment associated with a typical blade test stand. The loading device can also support the blades 110 as the blades 110 are attached to the hub 105.

[0019] In a particular embodiment, the actuators 230 can place the same load on each corresponding blade 110 simultaneously to facilitate balancing the forces on the rotor 106. In other embodiments, individual blades 110 can be tested individually while still balancing the loads, as will be described in greater detail below with reference to Figure 4. In any of these embodiments, the rotor 106 can be located at a relatively flat area to avoid non-uniform loading due to gravity. The anchor 220 can include a weight that is heavy enough to counteract the loads placed on the rotor 106 by the actuators 230, and/or the anchor 220 can be attached to the ground to prevent the hub 105 from moving upwardly when the blades 110 are loaded in an upward direction. The actuators 230 can impart static and/or dynamic loads to the blades 110, and in particular embodiments, can determine the natural frequency of the rotor 106 as a whole. In at least some embodiments, the natural frequency of the rotor 106 can be obtained by supporting the blades 110, imparting a force or displacement to the hub 105, and allowing the hub 105 to "bounce" up and down. Accordingly, the arrangement described later with reference to Figure 4 can be used for this type of test. In any of these embodiments, the actuators 230 can apply sufficient tests to the blades 110 to ensure that the blades 110 conform with design, regulatory and/or other requirements before the rotor 106 is installed on the tower 101 shown in Figure 1.

[0020] Figure 3 illustrates a testing arrangement configured in accordance with another embodiment of the technology in which an anchor 320 (e.g., a weight) is attached to the hub 105, but is not securely fastened to the ground. Instead, the weight of the anchor 320 can be selected such that when the appropriate maximum load is applied to the blades 110 via the actuators 230, the hub 105 and the anchor 320 lift off the ground, as shown in Figure 3. Accordingly, the weight operates as a hub support element. This arrangement can be simpler than the arrangement described above with reference to Figure 2 because it does not require securing the hub 105 to the ground. Conversely, the arrangement described above with reference to Figure 2 can allow a greater flexibility when selecting the maximum load applied to the blades 110 because the maximum load is not constrained by the weight of the anchor 320. In still further embodiments, the weight of the hub 105 alone is sufficient to react the test loads applied to the blade(s). In such cases, the hub support element can include straps, rails, posts and/or other structures to control the position or motion of the hub 105 as loads are applied to the blade(s).

[0021] Figure 4 illustrates a testing arrangement configured in accordance with still another embodiment in which the blades 110a, 110b, 110c are secured to the ground via corresponding anchors 420a, 420b, 420c (referred to collectively as anchors 420). An actuator 430 directs a load to the hub 105 to provide a bending load on the blades 110. In one aspect of an embodiment shown in Figure 4, the actuator 430 bends the blades 110 in a direction opposite that in which the blades 110 bend in the embodiments described above with reference to Figures 2 and 3. To achieve bending in the same direction as was described above with reference to Figures 2 and 3, the rotor 106 can be inverted (e.g., so that the hub 105 is facing downwardly), or the actuator 430 can be configured to pull the hub 105 downwardly. In the latter embodiment, the anchors 420a-420c can be tall enough to provide sufficient clearance for the actuator 430 as it moves downwardly, and/or the actuator 430 can be located below grade (e.g., in a pit).

[0022] Figure 5 illustrates a testing arrangement configured in accordance with still another embodiment of the technology in which actuators 530 (shown as first, second, and third actuators 530a, 530b, 530c) can apply a distributed load to the corresponding blades 110a, 110b, 1 10c. The actuators 530 can accordingly include a "whiffletree" arrangement, or an arrangement of individual actuator elements positioned to apply loads at various locations along the lengths of the blades. The loads can be directed upwardly, as shown by the arrows in Figure 5, or downwardly in other embodiments. In particular embodiments, loads can be applied to the blades from above and/or from other directions, e.g., with cranes or other suitable equipment

[0023] Figure 6 illustrates a testing arrangement in accordance with yet another embodiment of the technology in which one or more of the blades 1 10 are anchored (e.g., to provide a reaction force) while another one or more of the blades are tested. For example, in the illustrated embodiment, the second and third blades 1 10b, 110c are anchored via corresponding blade support elements, e.g., anchors 620b, 620c, while the first blade 110a is loaded by an actuator 630. In other embodiments, two of the blades 110 can be loaded while the third blade is fixed. As is also shown in Figure 6, the testing arrangement can include a provision for applying loads to different portions of the blade 110a in a manner different than that discussed above with reference to Figure 5. In particular, the actuator 630 can be moved to various positions along the length of the first blade 110a (as indicated in dashed lines) to support loading at such locations during a test procedure. In any of the foregoing embodiments, a hub support element is positioned to support a wind turbine blade hub carrying at least one wind turbine blade. A wind turbine blade support element is positioned proximate to the hub support element to engage with one or more blades carried by the hub, and at least one of the hub support element and the blade support element is movable relative to the other to place a load on one or more blades. The hub support element can have any of a variety of suitable configurations to control or restrict the position or motion of the hub as loads are applied to the hub/rotor assembly. [0024] Figure 7 is a partially schematic, side elevation view of a support 740 that can be used to provide or facilitate one or more of multiple functions generally similar to and/or in addition to those described above with reference to Figures 1-6. For example, the support 740 can include a base 742 that is heavy enough to anchor a blade 1 10 (the end of which is visible in Figure 7) and/or the hub 105 described above. The base 742 can optionally include elements for attaching it (e.g., releasably) to the ground.

[0025] The support 740 can also include an actuator 730 that applies loads to the blade 110. The actuator 730 can accordingly include a power source 741 (e.g., a hydraulic power source) and a push rod 731 or other moveable element. In the particular embodiment shown in Figure 7, the push rod 731 carries a blade interface 732 that contacts the blade 110. If the blade 110 is only flexed upwardly relatively to its rest position during testing, the blade interface 732 can support just the downwardly facing surface of the blade 110. If the actuator 730 pulls the blade 110 downwardly from its rest position, the support 740 can include a cap 733 that fits over the top of the blade 1 10 to provide a suitable reaction force.

[0026] In still another aspect of the present technology, the blade interface 732 can be configured to support the blade 110 as the blade 110 is attached to the hub 105 described above. In still a further aspect of the disclosure, the blade interface 732 and the support 740 can be configured to support the blade 110 as it is being assembled. For example, the blade interface 732 can be shaped and configured to attach to an internal spar, an internal rib, and/or an external panel as the blade 110 is being assembled (e.g., in accordance with any of the techniques described in co-pending U.S. Provisional Application 61/347,724, previously incorporated herein by reference).

[0027] One feature of several of the foregoing embodiments is that they can facilitate testing a fully assembled blade (and in particular embodiments, a partially or fully assembled rotor) without requiring a typical standard test facility. An advantage of this arrangement is that it allows the blade and/or rotor to be fully tested even if it is manufactured and/or assembled in a remote location, e.g., at a wind turbine installation site rather than a typical manufacturing facility. This in turn allows the manufacturer/installer to demonstrate blade/rotor compliance with design, regulatory, and/or other requirements while taking advantage of the simplified transportation arrangements that can be obtained by transporting pieces of the blade to the wind turbine installation site and assembling the blade in the field rather than assembling the blade at a manufacturing facility and then transporting the blade to the remote installation site, which can have very limited accessibility. As a result, the wind turbine operator can take advantage of favorable wind conditions located at sites that are inaccessible to wind turbine blades made and tested using conventional techniques.

[0028] Figures 8A-9D illustrate test fixtures and associated methods in accordance with a still further embodiments of the technology in which multiple blades can be tested in situ (e.g., at a wind turbine installation site) using a test fixture that does not necessarily include a wind turbine hub. In a particular embodiment shown in Figure 8A, a test fixture 800 includes a support structure 840 (e.g., a common support structure) configured and positioned to carry multiple wind turbine blades 110, shown as a first wind turbine blade 110a and a second wind turbine blade 110b. In a particular aspect of this embodiment, the support structure 840 can include an anchor or body 848 and a buttress 846. The body 848 can include a heavy or strong, free-standing fixture that may be transported from one installation site to another. The buttress 846 can include a brace 844 and a foot 845 that together can prevent the body 848 from tipping under the weight of the wind turbine blades 110a, 110b, as will be described further below with reference to Figure 8B. In other embodiments, the buttress 846 can have other forms or configurations, e.g., the form of a counterweight on the opposite side of the body 848.

[0029] The support structure 840 can include multiple attachment positions 842 (two are shown in Figure 8A as a first attachment position 842a and a second attachment position 842b) for each of a corresponding multiple number of wind turbine blades. Accordingly, the test fixture 800 can test multiple wind turbine blades simultaneously. The test fixture 800 can further include a loading device 850 that applies loads to the wind turbine blades 110a, 110b. In a particular embodiment, the loading device 850 includes one or more first attachment elements or blade interfaces 832a and one or more second attachment elements or blade interfaces 832b. The first attachment element or elements 832a are releasably attached to the first wind turbine blade 110a, and the second attachment element or elements 832b are releasably attached to the second wind turbine blade 1 10b. One or more corresponding actuators 830 (two are shown in Figure 8A) are connected between corresponding first and second attachment elements 832a, 832b with corresponding first couplings 851a and second couplings 851 b, respectively. In a particular embodiment, the actuators 830 can include winches, and the first and second couplings 851a, 851 b can include cables. Accordingly, the actuators 830 can draw the wind turbine blades 1 10a, 110b toward each other, as indicated in dashed lines in Figure 8A. In other embodiments, the actuators 830 can include other devices, e.g., hydraulic actuators, and the first and second couplings 851a, 851 b can include elements other than cables, e.g., pistons. Accordingly, the actuators 830 can push the first and second wind turbine blades 110a, 110b apart from each other, as is shown in dotted lines in Figure 8A.

[0030] In a particular embodiment shown in Figure 8A, each of the first and second blades 110a, 110b is positioned to extend outwardly in a generally normal direction from the corresponding faces 841a, 841b, as indicated by lines N1 and N2. The faces 841a, 841b can be parallel to each other or, as shown in Figure 8A, angled away from each other. When angled away from each other, the angle between the faces 841a, 841 b can be set to the minimum value required to accommodate the maximum deflection between the blades, while allowing space for the loading device positioned between the blades. The attachment positions 842a, 842b can each include a pivot bearing 843 (e.g., a pitch bearing), identified individually as a first pivot bearing 843a and a second pivot bearing 843b. Accordingly, each of the wind turbine blades 110a, 110b can be rotated relative to the support structure 840 about the corresponding axis N1 , N2 so as to be loaded along different blade axes. Further details of this arrangement are described below with reference to Figures 9A-9D.

[0031] Figure 8B is a partially schematic, side view of the test fixture 800 shown in Figure 8A, in accordance with an embodiment of the presently disclosed technology. As shown in Figure 8B, the buttress 846 can be positioned to prevent the body 848 from tipping due to the weight of the first wind turbine blade 110a and the second wind turbine blade 110b (not visible in Figure 8B). The buttress 846 can be collapsible so as to be easily transported among multiple wind turbine installation sites. This feature can accordingly reduce the weight and/or volume of the body 848, which facilitates transporting the entire test fixture 800 from one site to another. The body 848 can be filled with sand, water or another readily available and disposable weighting material, and can be emptied for transport.

[0032] Figures 9A-9D are partially schematic end views of the test fixture 800 with the first and second blades 110a, 110b positioned for testing in accordance with representative embodiments of the present technology. In Figure 9A, the first and second wind turbine blades 110a, 110b are oriented such that thickness axes T of each blade are generally parallel to each other, and are generally horizontal or otherwise aligned generally parallel to the first and second couplings 851a, 851b. In addition, the suction surfaces S of the first and second wind turbine blades 110a, 110b are positioned to face toward each other. Accordingly, when the actuator 830 is actuated, the wind turbine blades 110a, 110b can be tested in a flapwise or thickness direction, e.g., in a "maximum flap" orientation.

[0033] In Figure 9B, the wind turbine blades 110a, 110b have been disconnected from the actuator 830 and rotated approximately 180° using the pivot bearings 843a, 843b described above with reference to Figure 8A. The wind turbine blades 110a, 110b are then reattached to the actuator 830 and tested again in the flapwise direction, but this time with the pressure surfaces P of the blades 110a, 110b facing toward each other (e.g., in a "minimum flap" orientation). In a particular embodiment, the first and second attachment elements 832a, 832b can have a generally frame-like configuration so as to support loads applied to the blades 110a, 110b from a variety of directions. The attachment elements 832a, 832b can also be configured to releasably receive the corresponding first and second couplings 851a, 851b to facilitate testing the blades 110a, 110b in a variety of orientations. For example, the individual attachment elements 832a, 832b can include eyelets or holes that receive a corresponding hook carried by a corresponding one of the first and second couplings 851a, 851b.

[0034] In Figure 9C, the first and second blades 110a, 110b have been further rotated so as to align or generally align chordwise axes C of the blades with the first and second couplings 851a, 851b. In this orientation, leading edges LE of the first and second blades 110a, 110b face toward each other. Accordingly, the blades can be stressed in a chordwise or edge (e.g., "maximum edge") orientation. In Figure 9D, the blades 110a, 110b have been rotated approximately 180° from the orientation shown in Figure 9C to test the blades in a "minimum edge" orientation, with the trailing edges TE of the blades facing toward each other. In other embodiments, the blades 110a, 110b can be tested in orientations other than those expressly described above. In any of these embodiments, each of the blades 110a, 110b can provide a reaction force for the load applied to the other, and multiple blades can be tested simultaneously. While the maximum/minimum flap and maximum/minimum edge loadings are typical, in other embodiments, the load can be applied to other blade axes and/or with the blade in other orientations. In still further embodiments, additional loads (e.g. weights) are added to the blade to change the direction of the load applied to the blade.

[0035] From the foregoing, it will be appreciated that specific embodiments of the disclosure have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. For example, the actuators can include hydraulic jacks in some embodiments, and other devices (e.g., winches or cranes) suitable for applying the loads required to achieve the desired test results in other embodiments. The rotor can include more than three blades or fewer than three blades. The loads applied to the blades can be static and/or dynamic and/or can be applied in directions other than those expressly described above. For example, the blades can be torqued about their longitudinal axes, and/or can be loaded horizontally or laterally (in the views shown in Figures 2-7), with the hub and/or other blades providing a suitable reaction force. In some embodiments, fewer than all the wind turbine blades accommodated by the hub can be tested when attached to the hub. For example, two blades can be attached to the hub and testing initiated with those two blades before a third blade is attached. In other embodiments, more than two blades can be attached to a non- hub test fixture. For example, three attachment sites or more blades can be attached to a fixture having correspondingly positioned blade, and the blades can be tested in pairs or otherwise to provide suitable reaction forces. Depending upon the embodiment, the blades can be tested in any of a variety of suitable environments, e.g., in the field, at a wind farm, at a manufacturing facility, and/or at a test facility. [0036] In still further embodiments, the support structure described above with reference to Figures 8A-8B can have other configurations. For example, the attachment positions 842a, 842b can be rotatable toward and away from each other about an axis that is generally perpendicular to the plane of Figure 8A. This allows the operator to select a large included angle between relatively long and/or flexible blades, and a smaller included angle between relatively short and/or stiff blades. In a particular embodiment, the support structure can include a pivot joint at the intersection of axes N1 , N2 to facilitate rotating the blades in the foregoing manner. In other embodiments, the pivot joint can pivot relative to other axes, and/or the support structure can include multiple pivot joints. In any of these embodiments, once the blades are rotated about the pivot joint(s) (e.g., about an axis normal to the plane of Figure 8A), the pivot joint(s) can be locked, and the blades can be tested in accordance with the techniques described above. This arrangement can reduce the weight and/or volume of the blade support structure.

[0037] Certain aspects of the disclosure described in the context of particular embodiments may be combined or eliminated in other embodiments. For example, the distributed load arrangements shown in Figures 5 and 6 can be applied to other rotor support arrangements. The loads applied to the blades can be varied directionally not only in the embodiments described above with reference to Figures 8A-9D, but also in the embodiments described above with reference to Figures 2-7. For example, the hub typically includes pitch bearings to which the blades are attached, and the blades can be rotated relative to the hub via these bearings to change the orientation of the blade relative to the load applied to it. Further, while advantages associated with certain embodiments have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the present disclosure. Accordingly, the present disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Claims

CLAIMS I/We claim:

1. A method for testing a wind turbine blade, comprising:

forming at least a portion of a wind turbine rotor by attaching a wind turbine blade to a hub;

testing the wind turbine blade by applying a load to at least one of the hub and the wind turbine blade, while the wind turbine blade and the hub are attached to each other, to deflect the wind turbine blade relative to the hub; and after testing the wind turbine blade, installing the rotor on a wind turbine.

2. The method of claim 1 wherein forming at least a portion of the wind turbine rotor and testing the wind turbine blade are performed in situ at a wind turbine operation site that includes a wind turbine tower.

3. The method of claim 1 , wherein testing includes supporting the hub while deflecting the wind turbine blade.

4. The method of claim 3 wherein testing includes securing the hub to ground while deflecting the wind turbine blade upwardly.

5. The method of claim 3 wherein testing includes applying a weight to the hub to secure the hub to ground or to provide a desired hub load while deflecting the wind turbine blade upwardly.

6. The method of claim 1 wherein testing includes supporting the wind turbine blade while deflecting the hub.

7. The method of claim 1 wherein applying a load includes applying a load that is distributed along a length of the wind turbine blade.

8. The method of claim 1 , further comprising supporting both the hub and the wind turbine blade, while forming at least a portion of the wind turbine rotor, with an arrangement of supports, and wherein testing the wind turbine blade includes testing the wind turbine blade while the hub and the wind turbine blade are carried by the same arrangement of supports.

9. The method of claim 1 wherein applying a load includes applying a static load

10. The method of claim 1 wherein applying a load includes applying a dynamic load.

11. The method of claim 1 wherein testing the wind turbine blade includes determining a natural frequency of the wind turbine blade and rotor.

12. The method of claim 1 wherein testing the wind turbine blade includes testing with the hub facing upward.

13. The method of claim 1 wherein testing the wind turbine blade includes testing with the hub facing downward.

14. The method of claim 1 wherein attaching the wind turbine blade includes attaching a first wind turbine blade, and wherein the method further comprises attaching a second wind turbine blade to the hub, and wherein testing the wind turbine blade testing the first wind turbine blade while securing the second wind turbine blade.

15. The method of claim 1 wherein attaching the wind turbine blade includes attaching a first wind turbine blade, and wherein the method further comprises attaching a second wind turbine blade to the hub, and wherein testing the wind turbine blade testing both the first wind turbine blade and the second wind turbine blade.

16. The method of claim 15 wherein testing both the first and second wind turbine blades includes testing the first and second wind turbine blades simultaneously.

17. The method of claim 1 wherein testing the wind turbine blade includes applying at least one load at multiple spaced apart points along a length of the blade.

18. A method for testing a wind turbine blade, comprising:

connecting multiple wind turbine blades to a common support structure;

applying a load to a first one of the wind turbine blades; and

reacting the load applied to the first wind turbine blade with a second one of the wind turbine blades.

19. The method of claim 18 wherein the common support structure includes a wind turbine blade hub.

20. The method of claim 18 wherein applying a load includes applying a test load.

21. The method of claim 20 reacting the load includes applying an equal and opposite test load to the second wind turbine blade.

22. The method of claim 18 wherein applying a load includes drawing at least one of the first and second wind turbine blades toward the other.

23. The method of claim 18 wherein applying a load includes moving at least one of the first and second wind turbine blades away from the other.

24. The method of claim 18 wherein the common support structure includes a wind turbine blade hub, and wherein applying a load includes applying a test load, and wherein the method further comprises, after testing the wind turbine blade, installing the wind turbine blades and the hub on a wind turbine.

25. A system for testing a wind turbine blade, comprising:

a hub support element positioned to control at least one of a position and a motion of a wind turbine blade hub carrying at least one wind turbine blade; and a wind turbine blade support element positioned proximate to the hub support element to engage with the at least one wind turbine blade, with at least one of the hub support element and the wind turbine blade support element movable relative to the other to place a load on the at least one wind turbine blade.

26. The system of claim 25 wherein the hub support element is movable relative to the wind turbine blade support element.

27. The system of claim 25 wherein wind turbine blade support element is movable relative to the hub support element.

28. The system of claim 25 wherein the wind turbine blade support element is one of a plurality of wind turbine blade support elements positioned proximate to the hub support element, and wherein individual wind turbine blade support elements are positioned to simultaneously engage with corresponding wind turbine blades carried by the wind turbine blade hub.

29. The system of claim 25 wherein the wind turbine blade support element is one of a plurality of wind turbine blade support elements positioned proximate to the hub support element along a length of the at least one wind turbine blade.

30. A system for testing a wind turbine blade, comprising:

a support structure having a first attachment position for a first wind turbine blade and second attachment position for a second wind turbine blade, the support structure being positioned to simultaneously carry a first wind turbine blade at the first attachment position and a second wind turbine blade at the second attachment position; and

a loading device positioned proximate to the support structure, the loading device being simultaneously coupleable to the first and second wind turbine blades when the first wind turbine blade is carried at the first attachment position and the second wind turbine blade is carried at the second attachment position.

31. The system of claim 30 wherein the support structure includes:

a body having a first face with the first attachment position and a second face with the second attachment position, the first and second faces facing in different directions; and

a buttress coupled to the body to at least restrict the body from tipping under the weight of the first and second blades.

32. The system of claim 30 wherein the loading device includes an actuator.

33. The system of claim 30 wherein the loading device includes:

a first element coupleable to the first wind turbine blade;

a second element coupleable to the second wind turbine blade; and

an actuator coupled between the first and second elements to impart motion to at least one of the first and second elements.

34. The system of claim 33 wherein the actuator is positioned to draw at least one of the first and second elements toward the other.

35. The system of claim 33 wherein the actuator is positioned to force at least one of the first and second elements away from the other.