A method of configuring a wind turbine

Abstract

In a first aspect of the present invention there is provided a method of configuring a wind turbine The wind turbine comprises a rotor comprising a hub and at least three wind turbine blades attached to the hub. Each blade extends between a root and a tip, and each blade comprises a connection point located between the root and the tip. The wind turbine further comprises a plurality of blade connecting members. Each blade connecting member extends between a respective pair of wind turbine blades. Each blade connecting member is connected at a first end to a connection point of a wind turbine blade and at a second end to an adjustable tension lock attached to the other blade of the pair of wind turbine blades. The method of configuring the wind turbine comprises coupling a tension adjustment device to the second end of the blade connecting member, and operating the tension adjustment device to adjust the tension in the blade connecting member. The method further comprises locking the tension lock to thereby maintain the adjusted tension in the blade connecting member.

Description

[0001] A method of configuring a wind turbine

[0002] Technical field

[0003] The present invention relates generally to wind turbines and more particularly to a method of configuring a wind turbine comprising a blade connecting member extending between a pair of wind turbine blades.

[0004]

[0005] Increasing the swept area of a wind turbine rotor typically means that the wind turbine can produce increased levels of power. Accordingly, there is a motivation to manufacture wind turbines with increasingly larger blades. However, increasing the length of a wind turbine blade increases the magnitude of loads, such as wind loads and weight loads, experienced by the blade and transferred to a hub of the rotor, in use.

[0006] It follows that increasing blade length typically reguires an increase in blade root diameter to safely transfer the increased blade loads. However, increasing the blade root diameter introduces further challenges for manufacturing and transporting such blades. In some cases, a support frame or supporting cables may be included on the rotor to transfer some of the blade loads to the hub and / or to other blades. For example, a cable-stayed rotor may include support cables extending between the blades and / or hub of a rotor to share and transfer blade loads, such that the structural reguirements for the blade root may be reduced. Reducing the structural reguirements of the blade root means that the length of a blade can be increased without increasing the root diameter of the blade.

[0007] The tension in the support cables is one of the factors which dictates the proportional distribution of loads between the support cables and the root of the blade. As such, it is important to set and maintain the tension in the support cables at specific levels. An optimal tension level may be dependent on factors such as wind speed and / or direction, seasonal conditions, and turbine operating modes. The tension in the support cables may be set during assembly and initial configuration of the wind turbine. In some cases, it may be beneficial to adjust the tension at a later stage after assembly, for example during operation of the turbine, in a reconfiguration phase between operational phases and / or during maintenance. Further, with particular reference to maintenance operations, in some cases it may be necessary to entirely unload blade-related tension from a support cable. However, adjusting the tension and / or slackening support cables on existing cable-stayed rotors can be both challenging and complicated. Therefore there is a need for apparatusand a method which facilitates simple, efficient, and safe adjustment of such support cables.

[0008] It is against this background that the present invention has been developed.

[0009] Summary

[0010] In a first aspect of the present invention there is provided a method of configuring a wind turbine. The wind turbine comprises a rotor comprising a hub and at least three wind turbine blades attached to the hub. Each blade extends between a root and a tip, and each blade comprises a connection point located between the root and the tip. The wind turbine further comprises a plurality of blade connecting members. Each blade connecting member extends between a respective pair of wind turbine blades. Each blade connecting member is connected at a first end to a connection point of a wind turbine blade and at a second end to an adjustable tension lock attached to the other blade of the pair of wind turbine blades. The method of configuring the wind turbine comprises coupling a tension adjustment device to the second end of the blade connecting member, and operating the tension adjustment device to adjust the tension in the blade connecting member. The method further comprises locking the tension lock to thereby maintain the adjusted tension in the blade connecting member.

[0011] In some examples, the method may be a method of reconfiguring a wind turbine. For example, the wind turbine may be assembled and operational in a first configuration, and the method may comprise reconfiguring the wind turbine into a second configuration. For example, the blade connecting member may have a first tension during operation of the wind turbine in the first configuration. Operating the tension adjustment device may therefore adjust the tension in the blade connecting member from the first tension to a second tension. The wind turbine may then be operated with the wind turbine in a second configuration in which the blade connecting member has the second tension.

[0012] It follows that in some examples, the tension lock may be locked prior to operation of the tension adjustment device. For example, the tension lock may be locked during operation of the wind turbine in the first configuration. Accordingly, in some examples the method may optionally include releasing the tension lock before operating the tension adjustment device to adjust the tension in the blade connecting member. In such an example the tension lock may preferably be released after the tension adjustment device is coupled to the second end of the blade connecting member. In some other examples the tension lock may comprise a one-way locking system, such as a ratchet, which facilitates adjustmentof the tension in the blade connecting member in one direction without necessarily releasing the tension lock. As such in some examples the method may not necessarily require actively releasing the tension lock prior to operation of the tension adjustment device.

[0013] In some preferred examples, the wind turbine blades may be pitchable relative to the hub. It should be understood that the term “pitchable” refers to the ability to rotate the whole blade about its longitudinal, i.e. spanwise, axis relative to the hub and at the hub.

[0014] In some examples, the blade connecting members may be referred to as “direct blade-to-blade” connecting members, because the connecting members are connected between respective pairs of blades.

[0015] In some preferred examples, the adjustable tension lock may be remotely operable. The tension adjustment device may also be remotely operable. Accordingly, in some examples of the method the tension in the blade connecting member may be adjusted remotely.

[0016] In some examples, the connection point may be located in a mid-portion of the respective wind turbine blade. Locating the connection point in the mid-portion of the blade means that the connection point is located away from the root and the tip. For example, the midportion of the blade may be a portion extending between a point located 15% of the length of the blade from the root and a point located 15% of the length of the blade from the tip. As such, a connection point located in the mid-portion of the blade may be located at least 15% of the length of the blade away from the root. Similarly, a connection point located in the mid-portion of the blade may be located at least 15% of the length of the blade away from the tip.

[0017] The adjustable tension lock may also act as a safety system. For example, the adjustable tension lock may facilitate maintaining the tension in the blade connecting member if the tension adjustment device were to lose power, experience a technical issue, or fail in any other way.

[0018] In some examples, the adjustable tension lock may be integrated with another component of the wind turbine. For example, the adjustable tension lock may be integrated in an assembly with the tension adjustment device. As described in more detail later, in some examples the tension adjustment device may include a winch and / or a motor. The adjustable tension lock may be part of the winch and / or motor.In some examples, the adjustable tension lock may comprise a locking bar comprising at least one hole and at least one locking pin. The second end of the blade connecting member may be connected to the locking bar. Locking the tension lock may comprise inserting the at least one locking pin into the at least one hole in the locking bar. In some preferred examples, the locking pin may be removably inserted into the hole in the locking bar such that the pin can be removed to thereby release the tension lock.

[0019] In some examples, the locking bar may comprise a plurality of sequential holes. Locking the tension lock may comprise inserting the at least one locking pin into at least one of the sequential holes in the locking bar. As such, the adjustable tension lock may comprise a plurality of locked positions dependent on the which hole the locking pin is engaged in. This means that the adjustable tension lock may facilitate locking the tension at a plurality of different pre-defined tensions, by selectively engaging the locking pin in any one of the holes in the locking bar.

[0020] In some examples, the adjustable tension lock may comprise a plurality of locking pins arranged to extend into the same hole in the locking bar. Accordingly, locking the tension lock may comprise inserting a plurality of locking pins into the same hole in the locking bar. As such, the adjustable tension lock may be referred to as a multi-pin locking system in some examples. Such an arrangement increases redundancy and safety for engaging at least one pin in the hole to lock the tension in the blade connecting member. In some examples, the adjustable tension lock may comprise at least one locking pin arranged to extend into a hole from one side, and at least one locking pin arranged to extend into the same hole from an opposing side of the locking bar.

[0021] In some examples, the or each locking pin may be biased into a normally locked arrangement in which the locking pin extends into a hole in the locking bar. For example, the or each locking pin may be biased into the hole in the locking bar by a spring or a magnet to lock the tension in the blade connecting member. The adjustable tension lock may comprise an actuator, a solenoid, a magnet, or other disengagement apparatus configured to selectively move the locking pin out of engagement in the hole, against the biasing force. For example, a solenoid may be activated to pull the locking pin out of the hole in the locking bar and thereby release the tension lock.

[0022] In some examples, the adjustable tension lock may comprise one or more clamps configured to clamp the blade connecting member, or an associated component, to thereby lock the tension in the blade connecting member. In some examples, the one ormore clamps may be spring-loaded, and thereby biased into a normally-clamped configuration.

[0023] In some examples, the blade connecting member may be connected to the adjustable tension lock, such as to a locking bar of the tension lock, indirectly, for example via a coupling member such as a rope, wire, cable or belt.

[0024] In some examples, the tension adjustment device may be attached to the same wind turbine blade as the adjustable tension lock. For example, the tension adjustment device may be attached to an outer surface of the wind turbine blade. In some other examples, the tension adjustment device may be attached to an inner surface of the wind turbine blade, or to attachment apparatus within the blade.

[0025] In some examples, the adjustable tension lock and the tension adjustment device may be jointly operable in a plurality of conditions. For example, in an active adjustment configuration the tension adjustment device may be operable to adjust the tension of the associated blade connecting member. In such an active adjustment configuration, the adjustable tension lock may be released, i.e. unlocked. In a passive tension configuration, the adjustable tension lock may be locked to maintain a tension applied to the blade connecting member by the tension adjustment device. With the tension lock locked, the tension adjustment device may be inactive, or even uncoupled from the second end of the blade connecting member.

[0026] In some examples, the method may further comprise removably attaching the tension adjustment device to the wind turbine blade before operating the tension adjustment device, and removing the tension adjustment device from the blade after locking the tension lock. Accordingly, the tension lock maintains the adjusted tension in the blade connecting member even after the tension adjustment device is uncoupled from the second end of the blade connecting member and removed from the blade.

[0027] In some examples, the tension adjustment device may be located on or in a root portion of the respective blade to which it is attached. For example, the root portion of a blade may be considered to extend up to 10 m outboard of the root of the blade. Locating the tension adjustment device within 10 m from the root of the blade may be advantageous for facilitating access to the tension adjustment device for assembly and / or maintenance operations. Further, locating the tension adjustment device on or in a root portion of the respective blade means that, in examples wherein the tension adjustment device remains on or in the blade during operation of the wind turbine, the mass of the tension adjustmentdevice is located closer to the hub, and to the rotor axis about which the rotor rotates during operation. In some examples, the tension adjustment device may be located at substantially the same radial location as the connection point of a respective wind turbine blade, in relation to a rotor axis of the wind turbine.

[0028] Alternatively, in some other examples, the tension adjustment device may be located inside the hub. The second end of each blade connecting member of the wind turbine may be connectable to the tension adjustment device which is located inside the hub. In some examples, the method may comprise adjusting the tension in each blade connecting member in turn. As such, the method may comprise connecting the second end of each blade connecting member to the tension adjustment device in the hub in turn. Such an arrangement may provide quick and simple adjustment of the tension in each blade connecting member with only a single tension adjustment device, without requiring repositioning and attachment of the tension adjustment device for each blade connecting member. Arranging the tension adjustment device inside the hub may be advantageous in examples where the adjustment device remains attached to the wind turbine during operation of the turbine. For example, locating the adjustment device in the hub means that the mass of the adjustment device is located close to the rotor axis about which the rotor rotates during operation of the wind turbine. This may be advantageous for improving efficiency and balancing the rotor.

[0029] In some examples, the tension lock may be locked to maintain an initial tension in the blade connecting member before the tension adjustment device is coupled to the second end of the blade connecting member. In some examples, the method may be a method of reconfiguring the wind turbine after a period of operation. As such, the tension lock may be in a locked state before the tension adjustment device is coupled to the blade connecting member. In some other examples, the tension lock may comprise a one-way locking system, such as a ratchet, such that the tension lock may be in a locked state whilst still facilitating adjustment of the tension in the blade connecting member in one direction. In such an example the tension lock may be locked prior to adjustment as a safety precaution to ensure the tension applied by the tension adjustment device is maintained.

[0030] As described previously, in some examples the method may comprise unlocking the tension lock to facilitate adjustment of the tension in the blade connecting member. In such an example, the method may comprise coupling the tension adjustment device to the second end of the blade connecting member, subsequently unlocking the tension lock,and subsequently operating the tension adjustment device to adjust the tension in the blade connecting member. As previously described, the tension lock may then be locked to maintain the adjusted tenson, before the tension adjustment device is uncoupled from the blade connecting member.

[0031] In some examples, when the adjustable tension lock is in a locked state, the blade connecting member and / or a component connected to the blade connecting member may comprise a high tension portion on one side of the tension lock and a low tension portion on an opposite side of the tension lock. In some examples, the tension adjustment device may be coupled to the low tension portion of the blade connecting member and / or component connected to the blade connecting member. Configuring the blade connecting member, tension lock, and tension adjustment device in this way advantageously ensures that locking the tension lock substantially isolates the tension adjustment device from the tension of the blade connecting member. Accordingly, such a configuration facilitates safe coupling and uncoupling of the tension adjustment device from the blade connecting member.

[0032] In some examples, before operating the tension adjustment device to adjust the tension in the blade connecting member, the method may comprise rotating the rotor such that a spanwise axis of the blade to which the adjustable tension lock is attached extends substantially vertically. For example, the rotor may be arranged such that spanwise axis of the blade extends substantially vertically upwards with the tip of the blade being above the root of the blade. This position may be referred to as a twelve o’clock position. In some other examples, the rotor may be arranged such that spanwise axis of the blade extends substantially vertically downwards with the tip of the blade being below the root of the blade. This position may be referred to as a six o’clock position. Arranging the rotor such that spanwise axis of the blade extends substantially vertically may advantageously minimize flapwise and / or edgewise loading of the blade resulting from the weight of the blade. As such, the 6 o’clock and 12 o’clock positions may be considered to be substantially neutral positions where flapwise and edgewise deflection of the blade is minimized. This may help to reduce tension in the blade connecting member, such that adjustment of the tension in the blade connecting member is easier.

[0033] Alternatively, in some other examples the method may comprise rotating the rotor such that a spanwise axis of each blade of the pair of wind turbine blades extends diagonally downwards before operating the tension adjustment device to adjust the tension in the blade connecting member. For example, the rotor may be rotated such that for each bladein the pair of blades, the respective tip is below the respective root. For example, one blade in the pair of blades may be arranged in an eight o’clock position. Further, one blade in the pair of blades may be arranged in a four o’clock position. In some highly preferred examples, the rotor may be arranged such that the blade connecting member extends substantially horizontally between the pair of blades.

[0034] Arranging the rotor such that the pair of blades extends downwards advantageously utilizes gravity to reduce the load on the blade connecting member and the tension adjustment device. For example, with the blade extending diagonally downwards, a component of the gravitational force acting on each blade pulls the tips of the blades towards one another. The self-weight of the blades may therefore reduce the distance between the connection point of a blade and the adjustable tension lock of the other blade of the pair, thereby reducing tension in the associated blade connecting member. Arranging the rotor with the pair of blades extending downwards may therefore make it easier by reducing the force required to adjust and set the tension in the blade connecting member.

[0035] In some examples, the second end of the blade connecting member may be coupled to the tension adjustment device indirectly, for example via a coupling member such as a rope, wire, cable or belt.

[0036] In some examples, the tension adjustment device may comprise a winch comprising a winch reel. Operating the tension adjustment device may therefore comprise spooling the respective blade connecting member off and onto a winch reel to vary a free length of the blade connecting member. In such examples, the blade connecting member is preferably a flexible, i.e. bendable, blade connecting member, such as a rope, wire, cable or belt.

[0037] The free length of a blade connecting member may refer to the length of a portion of the blade connecting member, which is not spooled onto the winch reel, i.e. the length of the portion of the blade connecting member between the winch reel and the connection point of the other blade in the pair of wind turbine blades. Varying the free length of the blade connecting member may vary the tension in the blade connecting member. Accordingly, the winch may be operated to adjust the tension in the blade connecting member spooling the blade connecting member off and onto the winch reel.

[0038] In some examples, the tension adjustment device may comprise a winch comprising a winch reel and a winch line wound onto the winch reel. The second end of the blade connecting member may be coupled to the winch line. Operating the tension adjustmentdevice may therefore comprise spooling the winch line off and onto the winch reel to thereby vary the tension in the blade connecting member coupled to the winch line. The inclusion of a winch line means that a substantially rigid blade connecting member can be used, in some examples, whilst still facilitating adjustment of the tension in the blade connecting member using a winch. A substantially rigid blade connecting member may comprise a fibre reinforced pultrusion, a metal bar or rod. The winch line may comprise a rope, wire, cable or belt.

[0039] In some examples, the winch line may be routed from the winch spool to the blade connecting member via at least one pulley. The inclusion of one or more pulleys may provide a mechanical advantage in relation to the force required to tension the blade connecting member. Further, the inclusion of one or more pulleys may provide greater flexibility for positioning the tension adjustment device.

[0040] In some examples, the winch may comprise a motor, such as an electric motor. For example, the motor may be operable to drive the winch reel. In some examples the adjustable tension lock may be integrated as part of the winch reel or the motor.

[0041] In some examples, the tension adjustment device may comprise a linear actuator. In some examples the linear actuator may be coupled directly to the second end of the blade connecting member. In some other examples, the blade connecting member may be coupled to the linear actuator indirectly, for example via a coupling member such as a rope, wire, cable or belt. The linear actuator may actuate in a plane orthogonal to the span of the blade. For example, the linear actuator may actuate in a plane substantially parallel to the blade connecting member, or parallel to the span of the blade. Actuating parallel to the span of the blade may provide more design freedom and space for lengthwise extension of the linear actuator.

[0042] In some examples, the linear actuator may be a hydraulic or pneumatic linear actuator. The blade connecting member may be connected to a piston of a hydraulic or pneumatic linear actuator. In some other examples, the linear actuator may be an electric linear actuator. An electric linear actuator may comprise a screw or threaded bar which is driven into and out of a housing when actuating the linear actuator. The blade connecting member may be connected to the screw or threaded bar.

[0043] In some examples, the blade connecting member may be coupled to the linear actuator via a lever arm. The lever arm may be attached to the respective blade via a pivot. The blade connecting member and linear actuator may be connected to the lever arm such thatextending or retracting the linear actuator pivots the lever arm about the pivot to thereby adjust the tension in the blade connecting member.

[0044] In some examples, the method may further comprise coupling at least one active tension control system between a blade connecting member and the hub to actively adjust the tension in the blade connecting member during operation of the wind turbine. The active tension control system may facilitate adjustment of the blade connecting member tension during operation of the wind turbine. For example, the active tension control system may be operable during operation of the wind turbine when the adjustable tension lock is locked.

[0045] In some examples, the active tension control system may be coupled to a midpoint, or substantially the middle of the respective blade connecting member. In some examples, the active tension control system may be coupled to the blade connecting member via a tension adjustment member such as a cable, wire, rope or belt. The active tension control system may be configured to vary the tension in the blade connecting member based on inputs such as wind speed, wind direction, operating mode, pitch angle and yaw angle. The active tension adjustment system may be operable to continuously vary the tension in the blade connecting member during operation of the wind turbine.

[0046] Notably, in examples including an active tension control system, the mechanism or apparatus for providing the active tension adjustment, such as a winch or actuator, may be relatively small, or underpowered compared to the main tension adjustment device. This is particularly the case when the blade connecting member is tensioned by the tensioning adjustment device and therefore is arranged substantially straight between the connection points of the blades. This is because the tension adjustment device may be configured to apply the majority of the tension in the blade connecting member and optionally lock the length of the blade connecting member. Therefore, only a smaller or lesser powered active tension control system may be required to change the blade connecting member away from being straight and effect tension adjustments when actively controlling the tension during operation of the turbine.

[0047] In some examples, each blade connecting member may extend between a respective pair of wind turbine blades at an angle of between 10 to 40 degrees relative to a pitch axis of each blade in the respective pair of wind turbine blades. In some preferred examples, each blade connecting member may extend between a respective pair of wind turbine blades at an angle of between 15 to 35 degrees relative to a pitch axis of each blade in the respectivepair of wind turbine blades. It should be understood that the pitch axis of wind turbine blade is the axis about which the blade pitches, i.e. rotates around the spanwise direction of the blade, relative to the hub.

[0048] In some examples, the blades may be coned relative to the hub. In such an example it may be advantageous for the blade connecting members to extend at an angle of between 32 to 35 degrees relative to the pitch axis of each blade in the respective pair. Such a configuration may be particularly advantageous in examples where the turbine does not necessarily include an active tension control system.

[0049] In some examples, the tension lock and tension adjustment device may be configured such that the blade connecting member can be slackened without necessarily requiring disconnection of the blade connecting member from the associated connecting point. This may be particularly beneficial in examples where the configuration method is used during a maintenance operation, i.e. where the method is used to configure the wind turbine into a maintenance or service configuration. Accordingly, in some examples, the step of operating the tension adjustment device may comprise reducing the tension in the blade connecting member by at least 75% of an operating tension, or more preferably by at least 90% of the operating tension.

[0050] For example, where the tension adjustment device comprises a winch, the winch may be configured such that the blade connecting member, or the associated winch line, can be unspooled far enough to dramatically reduce tension and substantially unload the blade connecting member. The step of operating the tension adjustment device may therefore comprise unspooling the blade connecting member, or the winch line, off the reel to slacken the blade connecting member to less than 25%, or preferably less than 10% of an operating tension of the blade connecting member.

[0051] In some examples, a blade to which a respective adjustable tension lock is attached may comprise an access opening through a surface of the blade proximal to the location of the tension lock. The access opening may facilitate access to an externally mounted adjustable tension lock from inside the blade. In some other examples, the access opening may facilitate access to an internally mounted adjustable tension lock from outside of the blade. Such access to the adjustable tension lock may be advantageous for assembly and / or maintenance operations. In some examples, the method of configuring the wind turbine may comprise accessing the adjustable tension lock via the access opening through the blade. In some examples, the tension adjustment device may be coupled tothe blade connecting member in the proximity of the adjustable tension lock. Accordingly, the method may additionally or alternatively include accessing the tension adjustment device via the access opening through the blade.

[0052] Brief description of the drawings

[0053] Examples of the present invention will now be described by way of non-limiting example only, with reference to the accompanying figures, in which:

[0054] Figure 1 is a schematic perspective view of a wind turbine comprising a hub, a plurality of wind turbine blades and a plurality of blade connecting members;

[0055] Figure 2 is a schematic perspective view of a connection point at which a blade connecting member is connected to a wind turbine blade;

[0056] Figure 3 is a schematic view of an example of a tension lock arrangement to which a blade connecting member is connected;

[0057] Figure 4 is a schematic perspective view of an example of a tension adjustment device operable to adjust the tension in a blade connecting member in a configuration method;

[0058] Figure 5 is a schematic perspective view of a different example of a tension adjustment device;

[0059] Figure 6 is a schematic view of a wind turbine comprising a rotor oriented in a preferred orientation for the configuration method; and

[0060] Figure 7 is a schematic perspective view of an example of a wind turbine including an active tension control system coupled between a blade connecting member and the hub.

[0061] Detailed description

[0062] Figure 1 is a schematic perspective view of a wind turbine 10 comprising a rotor 12 which features a plurality of wind turbine blades 14 attached a hub 16. Each blade 14 extends between a blade root 18 and a blade tip 20, and each blade 14 includes a connection point 22 located between the root 18 and the tip 20. It follows that the wind turbine 10 also includes a plurality of blade connecting members 24, and each blade connecting member 24 extends between a respective pair of wind turbine blades 14. Accordingly, the rotor 12 may be referred to as a cable-stayed rotor 12, in some examples. The blade connecting members 24 are configured to transfer loads between the blades 14 during operation ofthe wind turbine 10 and thereby reduce peak loads experienced at the root 18 of each blade 14.

[0063] Each blade connecting member 24 preferably extends between a respective pair of wind turbine blades 14 at an angle of between 10 to 40 degrees relative to a pitch axis of each blade 14 in the respective pair. It follows that in some examples the blades 14 may be pitchable, i.e. rotatable, relative to the hub 16, about the respective pitch axes. The rotor 12 may therefore be referred to as a cable-stayed pitchable rotor 12. If the blades 14 are coned relative to the hub 16, then it may be advantageous for the blade connecting members 24 to extend at an angle of between 32 to 35 degrees relative to the pitch axis of each blade 14 in the respective pair.

[0064] With reference to Figure 2, which shows an example of a connection point 22 in more detail, each blade connecting member 24 is connected at a first end 26a to a connection point 22 of a wind turbine blade 14. A second end 26b of each respective blade connecting member 24 is connected to an adjustable tension lock 28, shown in more detail in Figure 3. The adjustable tension lock 28 is attached to a wind turbine blade 14. Accordingly, for a respective pair of wind turbine blades 14, a blade connecting member 24 is connected between a connection point 22 of one blade 14 and an adjustable tension lock 28 attached to the other blade 14 of the pair.

[0065] Figure 3 shows an example of an adjustable tension lock 28 attached to a wind turbine blade 14. As shown, in some examples the adjustable tension lock 28 may include a locking bar 30 and the second end 26b of a blade connecting member 24 may be connected to the locking bar 30, either directly (not shown) or indirectly via another component 32. The locking bar 30 may have one or more holes 34 and the adjustable tension lock 28 may include at least one locking pin 36 arranged for insertion into a hole 34 to thereby lock the position of the locking bar 30 relative to the blade 14. It follows that locking the tension lock 28 may therefore include inserting a locking pin 36 into the at least one hole 34 in the locking bar 30, in some examples.

[0066] As shown in the example of Figure 3, the locking bar 30 may feature a plurality of sequential holes 34 which allow the locking bar 30 to be locked in a plurality of different positions to thereby maintain a respective plurality of different tensions in the associated blade connecting member 24. The or each locking pin 36 is preferably biased into a normally locked position in which the locking pin 36 extends into a hole 34 in the locking bar 30. For example, the adjustable tension lock 28 may include biasing means 38, suchas a spring, arranged to bias the locking pin 36 into engagement in a hole 34 in the locking bar 30.

[0067] As described by way of background, the tension in a blade connecting member 24 is one of the factors which dictates the proportional distribution of loads between the connecting member 24 and the root 18 of the blade 14. In preferred examples the wind turbine 10 may therefore be configured with a respective tension level in the blade connecting members 24 based on factors such as wind speed and / or direction, seasonal conditions, and turbine operating modes. The requisite tension in a blade connecting member 24 may be set in an initial configuration stage during assembly of the turbine 10, or during a reconfiguration process during or after operation of the turbine 10.

[0068] An example of a method of configuring the wind turbine 10 to achieve a desired tension in a blade connecting member 24 may include using a tension adjustment device 40, examples of which are shown in Figure 4 and 5. For example, a method of configuring the wind turbine 10 may include coupling a tension adjustment device 40 to the second end 26b of the blade connecting member 24, and operating the tension adjustment device 40 to adjust the tension in the blade connecting member 24. Configuring the wind turbine 10 may also include locking the tension lock 28 to thereby maintain the adjusted tension in the blade connecting member 24.

[0069] As noted previously, the wind turbine 10 may be reconfigured during or after operation, for example between operational phases. Accordingly, the tension lock 28 may be locked to maintain an initial tension in the blade connecting member 24, for example during an initial operational phase, before the tension adjustment device 40 is coupled to the blade connecting member 24 to adjust the tension, or at least before the tension is adjusted during the reconfiguration. It follows that for some examples of an adjustable tension lock 28, adjusting the tension in the blade connecting member 24 may involve releasing the tension lock 24 before operating the tension adjustment device 40.

[0070] The blade connecting member 24, or an associated component connected to the blade connecting member 24, may include a high tension portion 42 on one side of the tension lock 28 when the tension lock 28 is in a locked state, and a low tension portion 44 on an opposite side of the tension lock 28. Accordingly, components on the low tension side may be substantially isolated from the tension in the blade connecting member 24 by the locked tension lock 28. It follows that the tension adjustment device 40 is preferably coupled to the low tension portion 44 of the blade connecting member 24 or associated component.Examples of a tension adjustment device 40 that may be used for adjusting the tension in the blade connecting member 24 are shown schematically in Figures 4 and 5. The tension adjustment device 40 may be attached to the same wind turbine blade 14 as the adjustable tension lock 28, in some examples. As shown in Figures 4 and 5, in some examples the tension adjustment device 40 may be located on or in a root portion 46 of the respective blade 14 to which it is attached. For example, the adjustment device 40 may be located near to the tension lock 28 and / or connection point 22 of a respective blade 14.

[0071] Whilst the tension adjustment device 40 may remain in or on the blade 14 during operation of the wind turbine 10, in some preferred examples the adjustment device 40 may be removed from the blade 14 before operating the turbine 10. For example, the configuration method may include removably attaching the tension adjustment device 40 to the wind turbine blade 14 and subsequently operating the adjustment device 40 to adjust the tension in the blade connecting member 24. After locking the tension lock 28 to maintain the adjusted tension, the tension adjustment device 40 may then be removed from the blade 14.

[0072] With reference now to Figure 4, in some examples, the tension adjustment device 40 may include a winch 48. For example, the second end 26b of the blade connecting member 24 may be coupled to a winch line 32 which is wound onto a winch reel 50. It follows that operating the tension adjustment device 40 in the configuration method may include spooling the winch line 32 off and onto the winch reel 50. With the blade connecting member 24 coupled to the winch line 32, spooling the winch line 32 off and onto the winch reel 50 may thereby vary the tension in the blade connecting member 24.

[0073] Alternatively, in some other examples (not shown), the blade connecting member 24 may be bendable, and operating the tension adjustment device 40 may include spooling the blade connecting member 24 off and onto the winch reel 50. Such operation may vary the free length of the blade connecting member 24, i.e. the portion of the blade connecting member 24 that is not wound onto the winch reel 50, such that the tension in the blade connecting member 24 is thereby adjusted.

[0074] Referring now to Figure 5, in some examples the tension adjustment device 40 may include a linear actuator 52, such as a pneumatic or hydraulic linear actuator. For example, the linear actuator 52 may be removably attached to the blade 14 in some examples of the configuration method. Where included, the linear actuator 52 is preferably arranged such that extending or retracting the linear actuator 52 varies the tension in the associated bladeconnecting member 24. For example, the blade connecting member 24 may be coupled to the linear actuator 52 via a lever arm 54. The lever arm 54 may be attached to the blade 14 via a pivot 56 such that the lever arm 54 is moveable, i.e. pivotable, relative to the blade 14. In the configuration method, the linear actuator 52 may be operated to extend or retract and thereby pivot the lever arm 54 to adjust the tension in the blade connecting member 24.

[0075] Advantageously, the configuration method to adjust the tension in the blade connecting member 24 may be performed with the rotor 12 in any orientation. However, as shown in Figure 6, in some preferred examples the method may include arranging the rotor 12 with the pair of blades 14 extending downwards. For example, the rotor 12 may be arranged such that a spanwise axis of each blade 14 extends diagonally downwards, with the tip 20 of each blade 14 thereby being below the respective root 18. In such an arrangement the self-weight of the blades 14 pulls the blades 14 closer together such that the tension in the blade connecting member 24 extending between the downwards-extending blades 14 is reduced. This means that the tension in the blade connecting member 24 can be adjusted more easily, i.e. with less effort, by a tension adjustment device 40. It follows that the configuration method may include a step of rotating the rotor 12 such that a spanwise axis of each blade 14 of the pair of wind turbine blades 14 extends diagonally downwards before operating the tension adjustment device 40 to adjust the tension in the blade connecting member 24 between the pair of wind turbine blades 14 extending diagonally downwards.

[0076] Figure 7 shows an example of a wind turbine 10 following an optional additional step in the configuration method. As shown, in some examples, the method may additionally include a step of coupling at least one active tension control system 58 between a blade connecting member 24 and the hub 16. The active tension control system 58 may be configured to actively adjust the tension in the blade connecting member 24 during operation of the wind turbine 10. Notably, the requirements of such an active tension control system 58 may be significantly reduced compared to previous active systems because the active tension control system 58 is not required to apply the initial tension in the blade connecting member 24, as this is instead achieved by the tension adjustment device 40 in the configuration method described previously, whereby a more straight blade connecting member 24 between the two blades is achieved. Hence, only a small force in the active tension control system is required to achieve a substantial change in tension in the blade connecting member.Whilst not shown in the accompanying figures, in some examples the second end 26b of a blade connecting member 24 may be connected to a tension adjustment device 40 located on or in the hub 16. For example, the tension adjustment device 40 may be arranged on or in the hub 16 during assembly of the wind turbine 10, or the configuration method may include removably attaching the tension adjustment device 40 to the hub 16. In such an example, the respective connecting member 24, or a component such as a winch line 32 associated with the blade connecting member 24, may be routed inboard towards a tension adjustment device 40 located on or in the hub 16.

[0077] In some examples the method may comprise coupling the second end 26b of each blade connecting member 24 to the same tension adjustment device 40. In other words, each blade connecting member 24, or a component such as a winch line 32 associated with each blade connecting member 24 may be routed inboard to a single tension adjustment device 40 located on or in the hub 16. In such an example the configuration method may facilitate simultaneous or one after the other adjustment of the tension in all of the blade connecting members 24 by operating a single tension adjustment device 40.

[0078] The description provided herein serves to demonstrate a plurality of possible examples of the present invention. It will be appreciated that features described in relation to any of the examples above may be readily combined with any other features described with reference to other examples without departing from the scope of the invention as defined in the appended claims.

Claims

Claims:

1. A method of configuring a wind turbine (10), wherein the wind turbine comprises:a rotor (12) comprising a hub (16) and at least three wind turbine blades (14) attached to the hub, each blade extending between a root (18) and a tip (20), and each blade comprising a connection point (22) located between the root and the tip; anda plurality of blade connecting members (24), wherein each blade connecting member extends between a respective pair of wind turbine blades, wherein each blade connecting member is connected at a first end (26a) to a connection point of a wind turbine blade and at a second end (26b) to an adjustable tension lock (28) attached to the other blade of the pair of wind turbine blades;wherein the method comprises:coupling a tension adjustment device (40) to the second end of the blade connecting member;operating the tension adjustment device to adjust the tension in the blade connecting member; andlocking the tension lock to thereby maintain the adjusted tension in the blade connecting member.

2. The method of claim 1, wherein the adjustable tension lock (28) comprises a locking bar (30) comprising at least one hole (34) and at least one locking pin (36), wherein the second end (26b) of the blade connecting member (24) is connected to the locking bar, and wherein locking the tension lock comprises inserting the at least one locking pin into the at least one hole in the locking bar.

3. The method of claim 2, wherein the locking bar (30) comprises a plurality of sequential holes (34) and wherein locking the tension lock comprises inserting the at least one locking pin (36) into at least one of the sequential holes in the locking bar.

4. The method of claim 2 or claim 3, wherein the or each locking pin (36) is biased into a normally locked arrangement in which the locking pin extends into a hole (34) in the locking bar (30).

5. The method of any preceding claim, wherein the tension adjustment device (40) is attached to the same wind turbine blade (14) as the adjustable tension lock (28).

6. The method of claim 5, further comprising removably attaching the tension adjustment device (40) to the wind turbine blade (14) before operating the tension adjustment device, and removing the tension adjustment device from the blade after locking the tension lock (28).

7. The method of claim 5 or claim 6, wherein the tension adjustment device (40) is located on or in a root portion (46) of the respective blade (14) to which it is attached.

8. The method of any of claims 1 to 4, wherein the tension adjustment device (40) is located on or in the hub (16), and wherein the second end (26b) of each blade connecting member (24) of the wind turbine (10) is connectable to the tension adjustment device.

9. The method of any preceding claim, wherein the adjustable tension lock (28) is locked to maintain an initial tension in the blade connecting member (24) before the tension adjustment device (40) is coupled to the second end (26b) of the blade connecting member (24).

10. The method of any preceding claim, wherein when the adjustable tension lock (28) is in a locked state, the blade connecting member (24) and / or a component connected to the blade connecting member comprises a high tension portion (42) on one side of the tension lock and a low tension portion (44) on an opposite side of the tension lock, and wherein the tension adjustment device (40) is coupled to the low tension portion of the blade connecting member and / or component connected to the blade connecting member.

11. The method of any preceding claim, wherein before operating the tension adjustment device (40) to adjust the tension in the blade connecting member (24), the method comprises rotating the rotor (12) such that a spanwise axis of each blade (14) of the pair of wind turbine blades extends diagonally downwards such that for each blade in the pair, the respective tip (20) is below the respective root (18).

12. The method of any preceding claim, wherein the tension adjustment device (40) comprises a winch (48) comprising a winch reel (50), and wherein operating the tension adjustment device comprises spooling the respective blade connecting member (24) off and onto the winch reel to vary a free length of the blade connecting member.

13. The method of any of claims 1 to 11, wherein the tension adjustment device (40) comprises a winch (48) comprising a winch reel (50) and a winch line (32) wound onto the winch reel, wherein the second end (26b) of the blade connecting member (24) is coupled to the winch line, and wherein operating the tension adjustment device comprises spooling the winch line off and onto the winch reel to thereby vary the tension in the blade connecting member coupled to the winch line.

14. The method of claim 12 or claim 13, wherein operating the tension adjustment device (40) comprises spooling the blade connecting member (24) or winch line (32) off the winch reel (50) to reduce the tension in the blade connecting member to less than 25%, or preferably less than 10%, of an operating tension of the blade connecting member.

15. The method of any of claims 1 to 11, wherein the tension adjustment device (40) comprises a linear actuator (52).

16. The method of claim 15, wherein the blade connecting member (24) is coupled to the linear actuator (52) via a lever arm (54), wherein the lever arm is attached to the respective blade (14) via a pivot (56), and wherein the blade connecting member and linear actuator are connected to the lever arm such that extending or retracting the linear actuator pivots the lever arm about the pivot to thereby adjust the tension in the blade connecting member.

17. The method of any preceding claim, further comprising coupling at least one active tension control system (58) between a blade connecting member (24) and the hub (16) to actively adjust the tension in the blade connecting member during operation of the wind turbine (10).

18. The method any preceding claim wherein each blade connecting member (24) extends between a respective pair of wind turbine blades (14) at an angle of between 10to 40 degrees relative to a pitch axis of each blade in the respective pair of wind turbine blades.

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