Patent Description:
Stay cables, also called "guy cables", are used for stabilizing tall structures, such as towers or masts. Stay cables are furthermore used in bridge-building, for example for supporting the bridge deck. A typical application are wind turbine towers, wherein the additional stability provided by the stay cables allows for a slender and optimized tower structure. A foundation is used to connect the stay cable to ground. A stay cable connection assembly and anchorage is used to connect the stay cable to such foundation. A steel adaptor plate is for example mounted to a concrete structure, and the stay cable is attached to the adaptor plate, for example by means of a ring nut screwed onto a stay cable termination and bearing against a bearing plate.

As the stay cable is tensioned, significant forces are applied to the stay cable termination and the bearing plate. If the axis of the stay cable termination is not perpendicular to the bearing plate and thus to the steel adaptor plate, the stay cable termination will experience significant bending moments. Generally, as the foundation can only be constructed with a certain degree of precision, and as likewise, the erection of the tower will result in a certain positioning error in horizontal direction, which can be up to or even exceed <NUM>, a misalignment between the bearing plate and the termination of the stay cable often occurs. When such misaligned stay cable is tensioned, a permanent bending moment is originated near the cable termination. Further, oscillation of the tower results in oscillation of the cable tension. Permanent bending moments reduce the cable ULS (ultimate limit state) strength. The tension oscillations translate into oscillating bending moments experienced by the end of the stay cable. As a result, the cable experiences significant fatigue and may be damaged.

Furthermore, as the cable is generally tensioned by tensioning the cable strands using wedges, which bite into the strands, it is often not possible to re-tension the stay cable. In general, the entire stay cable would need to be replaced. However, in view of the slender structure of the respective wind turbine tower, which is supported and held in place by the stay cables, it is not possible to replace the stay cable without unmounting the whole wind turbine nacelle and upper tower sections. A misalignment between the steel adaptor plate and the slope of the cable at its termination can accordingly result in significant drawbacks. Conventional attempts to avoid such misalignment are generally labour-intensive and cumbersome to implement.

In the past, for stay cables, the tolerances have been met by adjusting the bearing plate to align with the stay cable by using for example screws. Alternatively, hinges have been introduced as part of the bearing plate assembly, allowing the bearing plate to tilt freely and adjust itself to the inclination of the stay cable, so that no alignment is required. Such configuration is however complex and less robust. Alternatively, tolerances have been included in the design of the stay cable and bearing plate for which there is a design penalty and resulting inefficiency. Considering the generous foundation execution tolerances, such solution is however hardly achievable.

<CIT> discloses an engagement between a transverse support beam and the lower end of a hanger of a bridge. The lower end of the hanger is fixed to a transverse support beam by a length-adjustable connection part. By rotating a movable bolt, a movable wedge can be slid longitudinally to adjust the length.

<CIT> refers to a tower structure comprising at least two tower sections arranged one above the other.

At a connection point between both tower sections, a leveling device is arranged for aligning the upper tower section substantially vertically.

It is accordingly desirable to connect a stay cable in a fast and efficient way to a respective foundation or other anchoring point while avoiding a respective misalignment and other drawbacks of the prior art.

There is accordingly a need to improve the connecting of a stay cable to a support structure that supports the end of the stay cable and in particular to provide such connection in a simple and efficient way that facilitates and accelerates the connection procedure.

The dependent claims describe embodiments of the invention.

According to an embodiment of the invention, a stay cable connection assembly is provided, which comprises a support and a bearing surface configured to bear a load applied by the stay cable. The stay cable connection assembly is configured to transfer the load to the support. The stay cable connection assembly (abbreviated herein as "connection assembly") further includes a first adjustment plate which is wedge-shaped and arranged between the bearing surface and the support and a second adjustment plate which is likewise wedge-shaped and arranged between the bearing surface and the support. At least one of the first and second adjustment plates is configured to be rotatable to adjust an orientation of the bearing surface with respect to the support.

Such connection assembly may allow the connection of a stay cable in such a way that respective bending moments are avoided for the target preload cable sag, i.e. for the cable sag (and thus orientation of the termination) present when the cable is tensioned to the target preload. In particular, by rotating the first and/or second adjustment plate, the orientation of the bearing surface can be adjusted to that it is essentially perpendicular to an axial direction of the end of the stay cable to be mounted to the connection assembly, in particular of a termination thereof. Such two wedged adjustment plates furthermore allow a tilting angle between the bearing surface and the support to be adjusted over a certain range without having to disassemble the connection assembly, in particular without having to exchange any elements thereof. The adjustment of the orientation of the bearing surface can thus be performed fast and efficiently and in a simple manner. Even if there are errors present in the positioning of the tower and/or foundation, it becomes possible to provide an alignment between the stay cable and the support that avoids bending moments associated with execution errors. Adjusting the orientation of the bearing surface in particular relates to adjusting an amount and a direction of a tilting (inclination angle) of the bearing surface with respect to the support, i.e. an adjustment of an angle formed between a surface normal of the bearing surface and a surface normal of the support.

Preferably, both adjustment plates are rotatable.

The stay cable connection assembly may further comprise a bearing plate providing the bearing surface on a side of the bearing plate facing away from the support. The second adjustment plate may be the bearing plate, or it may be a separate plate distinct from the bearing plate and arranged between the bearing plate and the support. Whereas the former configuration provides a simplified construction of the connection assembly, the later configuration allows for example the providing of two identical adjustment plates and of a bearing plate having parallel end faces, thereby facilitating the manufacturing thereof. The adjustment plates may in particular be shim plates, and the connection assembly may accordingly comprise two such wedge-shaped shim plates.

It is particularly beneficial if the first adjustment plate and/or the second adjustment plate has a handle configured to allow manual rotation of the respective adjustment plate. By such configuration, the relative angular position between the two adjustment plates and the angular position of each adjustment plate with respect to the support can be changed fast and efficiently. Preferably, the handle is provided on the thicker part of the wedge-shaped adjustment plate, in particular at the circumferential position at which the thickness of the adjustment plate is largest. The handle may have a bar shape, a C-shape or the like.

In an embodiment, the first adjustment plate and/or the second adjustment plate has a first end face and a second end face, wherein the first end face is inclined with respect to the second end face by an angle of inclination. The angle of inclination may lie within a range of <NUM>° to <NUM>°, e.g. within the range of <NUM>° to <NUM>°, <NUM>° to <NUM>°, for example at about <NUM>°. The angle may also be termed "skew angle". If both plates have a skew angle of <NUM>°, the total amount of inclination may for example be adjusted between <NUM>° and <NUM>°. The adjustment plates may thus be kept relatively thin while providing a sufficient amount of angular adjustment.

The angle of inclination of the adjustment plates may be selected so as to match the expected range of tolerances on the alignment of the bearing plate.

The first adjustment plate and/or the second adjustment plate may have an annular shape with a central bore and first and second annular end faces. The first or the second annular end face may be perpendicular to an axial direction of the bore. The wedge shape may accordingly be achieved by only skewing one end face of the respective plate.

The first and second adjustment plates may be arranged such that the inclined end faces are in contact with each other, i.e. the slanted surfaces are in contact. In other configurations, an intermediate piece may be provided between the slanted surfaces, or the slanted surfaces may be provided on opposite sides, in axial direction, of the adjustment plates, or may be provided so that they face in the same axial direction. If the inclined surfaces face each other and are in contact, the first and second adjustment plates may form a cylinder and may combine to a total angle of inclination of <NUM>° if the largest thickness of the plates is arranged at opposing angular positions, and may amount to twice the angle of inclination if the largest thickness of both plates is positioned at the same angular position.

In an embodiment, an angle of inclination between a first end face and a second end face of the first and second adjustment plates is substantially the same for both plates. In particular, the first and second adjustment plates may have substantially the same shape. Accordingly, the adjustment plates are easy to manufacture. As they are complementary in such configuration, the total angle of inclination can be adjusted between <NUM>° and twice the individual angle of inclination. In other embodiments, the angles of the first and second adjustment plates may be different.

To provide a particularly large inclination, the first and second adjustment plates may form a first set of plates, and the stay cable connection assembly may comprise at least a further set of plates including third and fourth adjustment plates. It should be clear that by adding further sets of adjustment plates, the possible range of angles of inclination between the bearing surface and the support may further be increased. In other embodiments, a single further wedge-shaped adjustment plate may be added for achieving larger angles of inclination. If the angle of inclination of such single additional adjustment plate is twice that of the angle of inclination of the first and second adjustment plates, the connection assembly may still be adjusted for a total of <NUM>° inclination.

It should be clear that such second set of plates may have a configuration similar to the one of the first set of plates, but that the adjustment plates of such second set may also have a different angle of inclination and/or a different thickness.

The support may comprise an adapter plate, in particular a steel adapter, and the adapter plate may be configured to be attached to a concrete structure, for example by means of an anchor of a post tension strand fixed to the concrete structure.

In an embodiment, the connection assembly further comprises a fixing plate configured to be mounted to the support. At least one, preferably both of the first and second adjustment plates are arranged between the fixing plate and the support. The fixing plate may be tightened to the support to fix the position of the respective at least one adjustment plate. Such fixation allows the determination of the actual orientation of the bearing surface achieved by the rotation of the adjustment plates.

Preferably, the bearing plate is mounted to the fixing plate. The fixing plate may be mounted to the support in a releasable way, for example by studs, threaded bolts, or other connecting members. Connecting members that are releasable from a side of the support facing away from the fixing plate may be employed for mounting the fixing plate to the support. Loosening the fixing plate when the bearing plate is mounted is thus possible. When the whole assembly, including the support, bearing plate, fixing plate and adjustment plates is mounted to the foundation, the connecting members may be untightened, thus releasing the pressure on the adjustment plates and allowing the adjustment of the orientation of be bearing surface by rotation of one or more of the adjustment plates. Providing the bearing plate and the fixing plate as separate plates facilitates achieving the desired strength of the assembly.

Generally, the bearing plate will be facing downwards when mounting a stay cable of a bridge or tower, which extends in an upward direction. The connecting members of the fixing plate may be configured and arranged such that untightening the connecting members results in the bearing plate and fixing plate moving downwards (in particular falling) by their own weight, thus releasing pressure on the adjustment plates. In particular, the center of gravity of the bearing plate and fixing plate assembly may be determined and the connecting members may be positioned so as to ensure that loosening of the connecting members releases the pressure on the adjustment plates while avoiding damage to the connecting members, e.g. studs or bolts.

It should be clear that in other configurations, no separate fixing plate may be provided, and the bearing plate may directly be attached to the support by the connecting members (the adjustment plates being arranged between bearing plate and support). In even other embodiments, the bearing plate may be mounted after fixing the position of the adjustment plates by means of the fixing plate, so that the correct orientation can be affirmed prior to attaching the stay cable. The fixing plate may for example have parallel end faces. The bearing plate may also have parallel end faces. The bearing plate may be mounted to the fixing plate. Accordingly, the orientation of the end face of the fixing plate that faces away from the support may be indicative of the orientation of the bearing surface on the bearing plate. It can thus be determined, by means of the fixing plate, if the bearing plate will have the desired orientation with respect to the support and/or the stay cable termination. Such fixing plate furthermore facilitates assembly and readjustment of the orientation, since it can be made significantly thinner and thus less heavy as the bearing plate. However, pre-assembly of bearing plate, fixing plate and support is preferred, as outlined above.

It should be clear that for mounting a wind turbine stay cable, the bearing plate may have significant size, it may for example exceed <NUM>, <NUM> or more in outer diameter. Mounting and unmounting of such large and heavy plate or of the whole assembly is accordingly relatively cumbersome or even impossible. Preassembly and adjustment by releasing the fixing plate is thus advantageous.

The connection assembly may further comprise the stay cable, and the stay cable may be a wind turbine stay cable configured to be connected to a wind turbine tower to support the wind turbine tower. The adjustment plates, the bearing plate and/or the fixing plate may be made of steel.

According to a further embodiment of the invention, a wind turbine comprising a wind turbine tower, a stay cable connected at one end to the wind turbine tower, and a stay cable connection assembly having any of the configurations described herein is provided. The other end of the stay cable is connected to the stay cable connection assembly such that the bearing plate supports the load applied by the stay cable. The stay cable connection assembly may in particular have a configuration in which by rotation, the first and/or second adjustment plates are adjusted such that an axial direction of a termination of the stay cable at the end at which it is mounted to the connection assembly is substantially perpendicular to the bearing surface at the target preload of the stay cable.

According to a further embodiment, a method of aligning a bearing surface for mounting a stay cable is provided. The method comprises arranging a first adjustment plate between the bearing surface and a support. The first adjustment plate is wedge-shaped, wherein the bearing surface is configured to bear a load applied by the stay cable, the load being transferred to the support. The method further includes providing a second adjustment plate, wherein the second adjustment plate is wedge-shaped and arranged between the bearing surface and the support. Further, at least one of the first and second adjustment plates is rotated to adjust an orientation of the bearing surface with respect to the support. By such rotation, the inclination/tilting of the bearing surface with respect to the support is in particular adjustable, both in amount and direction of the tilting. By such method, advantages similar to the ones outlined further above may be achieved.

For example, adjusting the orientation of the bearing surface with respect to the support may comprise adjusting the angular position of the first adjustment plate with respect to the second adjustment plate to adjust the amount of inclination of the bearing surface with respect to the support and/or adjusting the angular position of both adjustment plates (i.e. by the same amount and in the same direction) with respect to the support to adjust the angular direction of the inclination. Different amounts of misalignment and different angular directions of misalignment between the stay cable and the support may thus be compensated by rotation of the adjustment plates.

The method may further comprise bringing the bearing surface into an orientation in which an axial direction of a termination of a stay cable (at the stay cable target preload) is substantially perpendicular to the bearing surface at an axial position of the bearing surface by said rotating. In other words, the adjustment is performed such that the bearing surface is substantially parallel to a contact surface of a ring nut to be mounted to the stay cable termination when the stay cable is at its target preload, i.e. at the tension it is supposed to have when the tower or bridge is finally erected. The contact surface may contact the bearing surface when the ring nut is mounted. By such adjustments, bending moments on the termination of the stay cable may be avoided when the stay cable has the target preload.

The method may further comprise fixing the angular orientation of the first and/or second adjustment plate. This may for example be done by clamping at least one of the first and second adjustment plates, preferably both, between a fixing plate and the support. Screws, bolts, or threaded rods may for example be used to mount the fixing plate to the support, and these may be tightened to apply sufficient pressure to keep the first and second adjustment plates in place.

The method may further comprise determining a required orientation of the bearing surface (for example based on an expected orientation of the termination of the stay cable at a cable sag corresponding to the target preload); performing the rotating of the adjustment plates to orient the bearing surface in accordance with the required orientation; fixing the angular orientation of the first and second adjustment plates (e.g. by means of a fixing plate); and measuring an orientation of a surface that is indicative of the orientation of the bearing surface (this may be the bearing surface if the bearing plate is pre-assembled to the support; it may also be the surface of the fixing plate facing away from the support if the bearing plate is mounted after the adjustment). If the expected or measured orientation of the bearing surface does not correspond to the required orientation (i.e. bearing surface not parallel to ring nut contact surface), the rotating of the first and second adjustment plates may be repeated. Otherwise, if the orientation corresponds to the required orientation, the method may continue with the mounting of a stay cable to the stay cable connection assembly, for example by inserting the stay cable and mounting a ring nut to a stay cable termination.

It should be clear that before performing a second rotating step, the fixing of the angular position may be released, for example by loosening a respective fixing plate. However, as can be seen, it is not necessary to completely dismount a component of the connection assembly or to disassemble the connection assembly.

The method may further comprise the preassembly of the support, first and second adjustment plates, the bearing plate and optionally the fixing plate and mounting of the assembly to a foundation, prior to performing the adjustment. It is also possible to mount the bearing plate after said rotating has been performed.

It should be clear that the method may comprise further steps, for example any of the steps described herein. Furthermore, it should also be clear that the connection assembly may have a configuration that allows it to carry out the method in any of the embodiments disclosed herein.

The foregoing and other features and advantages of the invention will become further apparent from the following detailed description read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.

It is to be understood that the following description of the embodiments is given only for the purpose of illustration and is not to be taken in a limiting sense. It should be noted that the drawings are to be regarded as being schematic representations only, and elements in the drawings are not necessarily to scale with each other. Rather, the representation of the various elements is chosen such that their function and general purpose become apparent to a person skilled in the art.

<FIG> schematically illustrates a wind turbine <NUM> including a wind turbine tower <NUM>, a nacelle <NUM> and a rotor <NUM>. The wind turbine tower <NUM> is supported by stay cables <NUM>. Only two exemplary stay cables are shown in <FIG>, but it should be clear that further stay cables may be provided around wind turbine tower <NUM> and at different vertical positions on the tower. On the tower <NUM>, a stay cable piece <NUM> is provided, to which one of the stay cables <NUM> is attached. The other end of stay cable <NUM> is attached to a foundation <NUM> by means of a stay cable connection assembly <NUM>. In general, when planning and constructing the wind turbine, the end of the stay cable <NUM> meets the connection assembly <NUM> at a predefined slope, i.e. the axial direction at the end of the stay cable <NUM> forms a certain angle with ground. This angle can vary when wind turbine tower <NUM> is erected, for example due to errors in the positioning and inclination of the tower. Furthermore, stay cable <NUM> experiences sag that depends on the actual cable tension, which can however be determined based on the properties of the cable and a load estimation (target pretension) and is thus generally considered in the planning. Furthermore, the positioning and erection of the foundation <NUM> is associated with a certain error. Accordingly, in practice, there can be misalignment between the end of the stay cable <NUM> and the connection assembly <NUM>, to that the end (in particular the axial direction of the cable termination) is no longer perpendicular to a bearing surface of the connection assembly. As mentioned above, bending moments can be experienced by the end of the stay cable <NUM> as a result thereof. Oscillation of the tension in the stay cable <NUM> further results in oscillation of the bending moments, which provokes fatigue damage to the stay cable <NUM>. The present solution thus provides a stay cable connection assembly that minimizes such misalignment and accordingly the occurrence of respective bending moments. In particular, embodiments of the connection assembly <NUM> provide for an efficient and fast alignment of the bearing surface that bears the load applied by the stay cable <NUM> to the actual orientation of the respective end of the stay cable <NUM> that is to be connected to the connection assembly <NUM>.

<FIG> schematically illustrates an exemplary implementation of the foundation <NUM> and the connection assembly <NUM> of <FIG>. The connection assembly <NUM> includes a support <NUM>, which is exemplarily provided in form of an adapter plate <NUM>. Foundation <NUM> can include a concrete wall, as shown, and the adapter plate <NUM> can be placed on the foundation <NUM> and held in place for an initial rough adjustment by a screw <NUM>. The adapter plate may be fixed to the foundation <NUM> by means of a post-tensioning strand <NUM> and plate anchor <NUM>. After post-tensioning the strands, grouting may be performed. Accordingly, the support <NUM> can be adhered firmly to the foundation <NUM>. It should be clear that on the other side of support <NUM>, a respective foundation is provided (not shown in <FIG>).

To attach the stay cable <NUM> to the support <NUM>, a bearing plate <NUM> with a bearing surface <NUM> is provided. Stay cable <NUM> is led through respective openings in the support <NUM> and bearing plate <NUM> and is held in place and tensioned by a ring nut <NUM>, that can for example be screwed onto an outer thread <NUM> of the termination of stay cable <NUM>. It should be clear that the general tensioning and mounting of stay cable <NUM> is known, and any such known ways of mounting stay cable <NUM> may be employed. For example, the individual strands of the stay cable <NUM> may be pre-tensioned using a jack and respective wedges that clamp the strands in place, and the stay cable <NUM> may further be tensioned by tightening the ring nut <NUM>.

As mentioned above, there may be a misalignment between the bearing surface <NUM> and an axial direction <NUM> of the end of stay cable <NUM>. To avoid bending moments, the surface normal of the bearing surface <NUM> should have the same direction as the axial direction <NUM> of stay cable <NUM>, i.e. the axial direction <NUM> should be perpendicular to the bearing surface <NUM> at the target preload of the stay cable <NUM>.

To achieve such alignment, the connection assembly <NUM> includes first and second adjustment plates <NUM>, <NUM>, which can be provided in form of shim plates. By means of these adjustment plates <NUM>, <NUM>, an orientation (in particular inclination) of the bearing surface <NUM> with respect to a surface <NUM> of support <NUM> on which the adjustment plates <NUM>, <NUM> rest can be adjusted. The adjustment plates <NUM>, <NUM> allow an adjustment of both, the amount of inclination and the direction of inclination. Accordingly, the orientation (in particular the surface normal) of the bearing surface <NUM> can be brought into alignment with the axial direction <NUM> of the end of the stay cable <NUM>.

<FIG> illustrates a particular implementation of the connection assembly <NUM> of <FIG> and <FIG>, so that the above explanations apply equally to the embodiment of <FIG> shows a sectional side-view through the center of the stay cable <NUM>. As can be seen, the first adjustment plate <NUM> and the second adjustment plate <NUM> each have a wedge shape. First adjustment plate <NUM> has a first end face <NUM> that is perpendicular to an axial direction of a through-bore through the adjustment plate <NUM>. It further has a second end face <NUM> that is inclined with respect to the first end face <NUM>, i.e. it is not perpendicular to the axial direction of the through-bore. The angle of inclination of end face <NUM> can be chosen in dependence on the desired amount of adjustment of the orientation of bearing surface <NUM>. The first adjustment plate <NUM> further has a handle <NUM> that is configured to allow a manual rotation of the adjustment plate, in particular around the axis of its through-bore.

The second adjustment plate <NUM> is configured correspondingly. It likewise includes an end face <NUM> that is substantially perpendicular to an axial direction of its through-bore, and a second end face <NUM> that is inclined with respect to the first end face <NUM>. The second adjustment plate <NUM> further includes a handle <NUM> configured to enable a manual rotation of the adjustment plate <NUM>.

In the present example, the configuration of the second adjustment plate <NUM> is similar to that of the first adjustment plate <NUM>, they may in particular have the same shape. This facilitates manufacturing of the adjustment plates. They are however oriented differently in the connection assembly <NUM>; in particular, the inclined end faces <NUM>, <NUM> face each other in the example of <FIG>. As illustrated, in such configuration, if the angles of inclination of the two adjustment plates <NUM>, <NUM> are arranged such that they oppose each other (i.e. plate <NUM> is turned by <NUM>° compared to plate <NUM>), the two inclinations match each other so that the combination of both plates <NUM>, <NUM> takes a cylindrical shape, resulting in a parallel orientation of end faces <NUM>, <NUM> and a combined inclination of zero. By rotating one of the plates by <NUM>°, a maximum combined inclination can be achieved that corresponds to twice the inclination of each individual adjustment plate <NUM>, <NUM>. Any other angle of inclination between this maximum angle and zero can be achieved by respectively rotating one adjustment plate with respect to the other. Further, by rotating both adjustment plates <NUM>, <NUM> in the same direction by the same rotation angle, the direction of the combined total inclination can be adjusted. As the adjustment plates <NUM>, <NUM> are arranged between the bearing surface <NUM> and the support <NUM>, the orientation of the bearing surface <NUM> with respect to support <NUM> and thus with respect to the axial direction <NUM> of the end of stay cable <NUM> can be adjusted. As the adjustment is achieved by rotating the plates <NUM>, <NUM> using the handles <NUM>, <NUM>, respectively, the adjustment can be made without disassembling any parts of the connection assembly <NUM>. The adjustment can thus be made in a fast, simple and efficient manner.

In <FIG>, the thickness of the adjustment plates <NUM>, <NUM> is exaggerated in order to illustrate the wedge shape of these plates. As shown in <FIG>, plates <NUM>, <NUM> can be significantly thinner, and in particular much thinner than the bearing plate <NUM>. It should be clear that in other implementations, both end faces <NUM>, <NUM> of one or both adjustment plates may be inclined. Furthermore, the first and second adjustment plates <NUM>, <NUM> may be configured differently and may in particular have different angles of inclination. The range of the total inclination may thereby be increased, although a certain offset of the total inclination angle will result. Furthermore, it should be clear that further adjustment plates can be provided. For example, a further pair of adjustment plates can be provided, thus extending in the range over which the orientation of bearing surface <NUM> can be adjusted. It would also be conceivable to add a third adjustment plate, which may for example have a larger angle of inclination chosen such that the angle of inclination can be compensated by the combined angles of inclination of the first and second adjustment plates. In such configuration, the range can be extended while a combined angle of inclination of <NUM>° can still be achieved.

In even further implementations, the second adjustment plate <NUM> may not be a separate plate, but may be provided by the bearing plate <NUM>. In particular, one or both of the axial end faces of bearing plate <NUM> may be inclined. Bearing plate <NUM> may then be provided with handle <NUM> and may be rotated to adjust the orientation of bearing surface <NUM>, in combination with the first adjustment plate <NUM>. It should be clear that also in such configuration, the second adjustment plate, i.e. the bearing plate <NUM>, is arranged between the bearing surface <NUM> and the support <NUM>, as the bearing surface <NUM> faces away from the support <NUM> (i.e. in such configuration, the second adjustment plate provides the bearing surface <NUM>). Such configuration reduces the number of components of the connection assembly <NUM>, although it makes the manufacturing of the bearing plate <NUM> more difficult. Also, the adjustment becomes more difficult in view of the weight of bearing plate <NUM>.

<FIG> further illustrates the outer thread <NUM> on the termination <NUM> of the stay cable <NUM>. As can be seen, when the ring nut <NUM> is tightened, the ring nut <NUM> bears against the bearing surface <NUM> and applies the tensional load of the stay cable <NUM> to the bearing surface <NUM>. The load is transferred by the connection assembly, in particular via the first and second adjustment plates <NUM>, <NUM> to the support <NUM>.

Optionally, a fixing plate <NUM> may be provided. By means of such fixing plate <NUM>, it is possible to fix the first and second adjustment plates <NUM>, <NUM> in a particular angular position. After adjustment (rotation) of the first and second adjustment plates <NUM>, <NUM>, the fixing plate <NUM> can be tightened to the support <NUM>, so that plates <NUM>, <NUM> are fixed in place and no longer rotatable. As shown, fixing plate <NUM> and bearing plate <NUM> may have substantially parallel axial end faces. Providing a separate bearing plate and adjustment plate facilitates providing the required attachment to the support for the fixing plate while allowing the bearing plate to retain the desired strength.

The stay cable connection assembly <NUM> may comprise the support <NUM>, the first and second adjustment plates <NUM>, <NUM> and the bearing plate <NUM>. It may further comprise the fixing plate <NUM>. It may further comprise the ring nut <NUM> and the stay cable <NUM>.

<FIG> is a top view of the first and second adjustment plates <NUM>, <NUM>, wherein adjustment plate <NUM> is located underneath adjustment plate <NUM>, so that only handle <NUM> is visible. For example by rotating handle <NUM> in the angular direction <NUM>, as indicated by the arrow, the combined inclination of both adjustment plates <NUM>, <NUM> can be adjusted.

By rotating both handles <NUM>, <NUM> equally, the direction in which the inclination is present can be adjusted.

<FIG> shows a section through the first and second adjustment plates <NUM>, <NUM> taken along line B-B of <FIG>. As can be seen, plate <NUM> has a wedge shape with an angle of inclination <NUM> of the inclined surface <NUM>. Furthermore, the second adjustment plate <NUM> likewise has an inclined surface with a respective inclination angle (not shown), resulting in the combined angle of inclination <NUM>. As an example, if the inclination angle is <NUM>° for each adjustment plate <NUM>, <NUM>, the combined inclination angle <NUM> can be adjusted between <NUM>° and <NUM>°. It should be clear that this is only an example, and that other values can be chosen for the angle of inclination of each adjustment plate.

<FIG> illustrates a particular implementation of the connection assembly <NUM> shown in <FIG>. In the example of <FIG>, adjustment plates <NUM>, <NUM> have the same angular setting, so that they cannot be distinguished in view of their low thickness. Further, as illustrated, a fixing plate <NUM> is provided and can be used to fix the angular position of adjustment plates <NUM>, <NUM>. For this purpose, connecting members, e.g. screws or bolts <NUM>, can be provided and can be screwed into screw holes <NUM> provided in fixing plate <NUM>. Respective through-holes <NUM> are provided in the support <NUM>. The bearing plate <NUM> is mounted to the fixing plate <NUM>, for example by using further bolts, screws or other fastening elements <NUM>. The fixing plate <NUM> and bearing plate <NUM> can be mounted to support <NUM> prior to mounting the assembly to the foundation <NUM>. As the fixing plate <NUM> can be untightened to release the pressure on the adjustment plates, the orientation of the bearing surface <NUM> can be checked and adjusted prior to mounting the stay cable. The stay cable can be fed through tube <NUM> and through the through-holes in the elements <NUM>, <NUM>, <NUM> and <NUM> of the connection assembly <NUM>, and can thereafter be attached in a conventional way, for example by using a respective ring nut <NUM> and employing known pre-tensioning methods. <FIG> furthermore illustrates further through-holes in the support <NUM> that are used for attaching the support <NUM> to the foundations <NUM>, e.g. by using a respective plate anchor for anchoring the support <NUM> to the post-tension strands <NUM>. The support <NUM> of <FIG> essentially corresponds to the support <NUM> of <FIG>, wherein the stabilizing sidewalls welded to the steel adaptor plate are not shown in <FIG>. Plates <NUM> are bearing plates that bear the load applied by the post-tension strand anchorage (plates <NUM> are not shown in <FIG>).

It should be clear that <FIG> only illustrates a possible implementation of the connection assembly <NUM> and that several modifications are conceivable. For example, the fixing plate <NUM> is optional, and it may have a different configuration. It may for example have a different shape and may be mounted differently to the support <NUM>. Further, as mentioned before, only one adjustment plate may be provided as a shim plate, and the other adjustment plate may be provided by the bearing plate <NUM>, for example by providing one surface of the bearing plate <NUM> with a respective inclination with respect to the axial direction of the through-bore. However, providing two shim plates <NUM>, <NUM> is preferred, as these can be relatively thin and are thus relatively easy to mount and to rotate. Further, it should be clear that the shape of the support <NUM> is only exemplary, and that for a different type of foundation, a different support <NUM> may be used. To adjust the position at which wedges of the termination of the stay cable <NUM> grip the cable strands, it also possible to add spacers between the bearing plate <NUM> and the ring nut <NUM> (not shown in <FIG>). The ring nut <NUM> may accordingly not directly abut against the bearing surface <NUM>, but the load may be transferred to the bearing surface <NUM> via respective spacers.

<FIG> shows a flow chart illustrating a method according to an embodiment. In step S1, pre-assembly of the adaptor plate, adjustment plates, fixing plate and bearing plate occurs, e.g. at ground level. Such assembly is easier compared to assembling these components once the adaptor plate has been mounted to the foundation. The foundation <NUM> is executed in step S2, wherein during execution of the foundation, the assembly is lifted and placed at the desired foundation position and attached to the foundation. Step S2 further includes the errection of the wind turbine tower <NUM> up to the stay cable attachment piece <NUM>. In step S3, a misalignment between the wind turbine tower <NUM> and the stay cable attachment interface provided by connection assembly <NUM> is measured. The orientation of the stay cable attachment interface may be the orientation of the bearing surface <NUM> (if the bearing plate is pre-assembled), but may also correspond to the outer surface of fixing plate <NUM> if the bearing plate is not yet mounted. Such misalignment may for example include a tower horizontal error, which may be due to a small deviation in the positioning or inclination, or due to manufacturing tolerances and the like of the tower elements.

In step S3, it is estimated how the stay cable termination <NUM>, i.e. the end of the stay cable to be attached to the connection assembly, is angled at the position of the connection assembly. Such estimation considers cable sag at the target preload, i.e. at the tension that the stay cable will finally have. Based on such expected angle of the stay cable termination, the required orientation of the bearing surface <NUM> can be derived, since the bearing surface <NUM> should be arranged perpendicular to the expected axial direction <NUM> of the stay cable termination <NUM>, i.e. parallel to the contact surface of the ring nut <NUM>. In step S4, the actual orientation of the stay cable attachment interface, in particular of the bearing surface <NUM>, is measured. An angular error between the required orientation of the bearing surface (i.e. the orientation of the ring nut contact surface) and the actual orientation of the bearing surface can thus be derived. In step S5, the fixing plate is loosened and the first and/or second alignment plates are adjusted, in particular by rotation using handles <NUM>, <NUM>, to align the orientation of the bearing surface <NUM> to the determined angle of the stay cable termination, i.e. to the required orientation of bearing surface <NUM>. As the angular deviation between the required orientation and the actual orientation of the bearing surface is known, the required adjustment angles can be determined and the adjustment plates can be set accordingly. Furthermore, the fixing plate <NUM> is then retightened to lock the first and second adjustment plates in place.

In step S6, the actual orientation of the stay cable attachment interface is re-measured, in particular by measuring the orientation of the bearing surface <NUM>. In step S7, it is checked if the measured orientation matches the expected angle of the stay cable termination, i.e. if it matches the required orientation. For example, the angle between the bearing plate <NUM> and the ring nut contact surface (the expected position thereof) may be evaluated. If this is not the case, steps S5 and S6 are repeated, and the adjustment plates <NUM>, <NUM> are in particular set such that the remaining discrepancy in the orientation is compensated. If it is determined that the required orientation has been achieved in step S7, the stay cable <NUM> is mounted to the stay cable attachment piece <NUM> on the wind turbine tower <NUM>, and the other end of the stay cable and its termination <NUM> is connected to the connection assembly <NUM> at the foundation <NUM>, in particular by making use of the ring nut <NUM>. It should be clear that any attachment and tensioning means known in the art may be employed for mounting the stay cable <NUM> to the connection assembly <NUM>, such as using respective pre-tensioning methods and performing a tensioning of the overall stay cable <NUM> using the ring nut <NUM>. The method may comprise further steps, e.g. mounting the bearing plate if it has not been pre-assembled in step S1. Further, for the present solution, several of the steps shown in <FIG> are optional and not required for performing the adjustment of the bearing surface <NUM>, such as steps S1 to S5, S7 and S9. In particular, the adjustment occurs by rotating the adjustment plates <NUM>, <NUM> such that the bearing surface <NUM> is adjusted to be perpendicular to the axial direction <NUM> of the end of the stay cable <NUM>.

As can be taken from the above description, the angle of the bearing surface <NUM> can be adjusted repeatedly without the need to dismantle any parts of the connection assembly <NUM>. In particular, only the fixing plate <NUM> needs to be loosened and the shim plates <NUM>, <NUM> can be rotated using the respective handles for performing the adjustment. A precise alignment between bearing surface <NUM> and the end of the stay cable <NUM> can be achieved, which minimizes respective bending moments, whereby providing such alignment is facilitated by using the adjustment plates <NUM>, <NUM> and can be performed fast and efficiently.

Claim 1:
A stay cable connection assembly, comprising:
- a support (<NUM>);
- a bearing surface (<NUM>) configured to bear a load applied by a stay cable (<NUM>), the stay cable connection assembly (<NUM>) being configured to transfer the load to the support (<NUM>);
- a first adjustment plate (<NUM>), wherein the first adjustment plate (<NUM>) is wedge-shaped and arranged between the bearing surface (<NUM>) and the support (<NUM>); and
- a second adjustment plate (<NUM>), wherein the second adjustment plate (<NUM>) is wedge-shaped and arranged between the bearing surface (<NUM>) and the support (<NUM>),
characterized in that at least one of the first and second adjustment plates (<NUM>, <NUM>) is configured to be rotatable to adjust an orientation of the bearing surface (<NUM>) with respect to the support (<NUM>).