GB2472103A

GB2472103A - Wind turbine support for vertical adjustment installation method

Info

Publication number: GB2472103A
Application number: GB0912984A
Authority: GB
Inventors: John Westwood Moore
Original assignee: NJORDGEN SUSTAINABLE TECHNOLOGIES Ltd; WINDCROP Ltd
Current assignee: WINDCROP LIMITED
Priority date: 2009-07-24
Filing date: 2009-07-24
Publication date: 2011-01-26
Anticipated expiration: 2029-07-24
Also published as: GB2472103B; GB0912984D0

Abstract

A wind turbine support assembly comprises a mast 100, a foundation of e.g. three helical piles 400c and at least three struts 200c each pivotably connected by a pin to the mast at a first connection point 210c, at e.g. 5m along the mast, and at the other end by pivot pins 220c to respective foundation connection points. Adjustable length links 300c, e.g. turnbuckles, are pin pivoted 310c, 320c between each strut and second mast connection point, e.g. at the base. The foundation may be installed to a lower accuracy and tower may be adjusted vertical to higher accuracy using the adjustable links. Foundation end fittings on two struts may form a pivot axis (Fig. 1) about which the assembly may pivot between horizontal and vertical by hydraulic rams acting between the pivot bearing foundations and the mid point of a scissoring linkage attached to the third foundation.

Description

A wind turbine support assembly and a method for installing a wind turbine using the same.

The invention relates to a support for a wind turbine support assembly, and a method of installing a small wind turbine in a desired orientation using such a support assembly. In particular, the invention is advantageously applied to small horizontal axis wind turbines that are rotatable to face into the wind. However, there are also advantages in improving the accuracy of alignment of vertical axis wind turbines.

Conventionally, wind turbines suitable for generating electricity are provided in one of three distinct classes.

Firstly, large industrial wind turbines are available for large-scale energy generation. These large wind turbines are typically used to provide power directly to electric power transmission networks and can provide power in the order of megawatts, typically in the range of 1MW to 5MW.

These large turbines are generally mounted by erecting a mast and then using a crane to mount the turbine on the mast; they are too heavy to erect the mast with the turbine already attached.

Secondly, small wind turbines are used to provide power in the range of 2kw to 50kw. These wind turbines are generally mounted on masts of length in the range 9m to 30m prior to the mast being erected.

Finally, micro-generation turbines used to power individual homes generally produce less than 1.5kw. These are typically mounted on a building and, in order to meet building regulations, do not extend more than 3m above the normal height of the building.

The following disclosure is concerned with small wind turbines and, in particular, the installation of the same.

Such installation typically involves raising a mast with a wind turbine already attached.

Small wind turbines are of a size where it is possible to mount the turbine in a rotatable manner on the top of a mast so that the turbine can face into the wind.

Conventionally, a small wind turbine mast is supported by a base set in concrete. A large pit is dug, into which concrete is poured which when set holds the base firm to provide a horizontal support onto which the mast is bolted.

Such a method has a number of problems. In particular, the process takes a long time because of the need to wait for the concrete to set. Furthermore, for wind turbines that rotate about the longitudinal axis of the mast so as to face into the wind, it is necessary for the mast to be accurately mounted such that mast axis is vertical. With a base set in a concrete foundation, the mast cannot be easily adjusted once installed.

Alternatively, piles are be driven into the ground. A grillage is mounted on the piles, and then the mast is bolted to the grillage. However, such an approach is very expensive.

Embodiments of the invention provide a wind turbine support assembly and a method of installing a small wind turbine using the same, wh.ich overcome the problems of the prior art.

According to a first aspect of the present invention, there is provided a wind turbine support assembly as claimed in claim 1.

According to a second aspect of the present invention, there is provided a method of installing a small wind turbine as claimed in claim 14.

For a better understanding of the invention and to show how it may be put into effect reference is now made, by way of example only, to the accompanying drawings in which: Figure 1 shows a plan view of a small wind turbine support assembly; Figure 2 shows a side view of a strut of the small wind turbine support assembly; Figure 3 shows a helical pile; Figures 4a, 4b, and 4c show the stages of installation of a wind turbine; and Figure 5 shows a plan view of a wind turbine support assembly including actuation means used in the process of Figures 4a to 4c.

A preferred embodiment of a wind turbine support assembly 50 in accordance with the invention is shown in figures 1 and 2.

The wind turbine support assembly 50 comprises: a mast 100; three piles 400a, 400b, 400c; and three struts 200a, 200b, 200c extending radially outwardly from the mast 100 and mounted on the piles 400a, 400b, 400c.

As can be seen in Figure 2, the strut 200c is attached to the mast 100 at a point along the length of the mast 100, near the end of the mast which is highest in use, by a pin joint 210c. The strut 200c is attached to the pile 400 by a pin joint 220c. The other struts 200a, 200b will be similarly connected.

In figure 2 it can also be seen that a turnbuckle 300c is connected between the mast 100 and the strut 200c. The turnbuckle 300c is attached to the mast via a pin joint 310c at a point near the end of the mast 100 which is nearest the ground when the mast is erected. The turnbuckle is attached to the strut 200c via a pin joint 320c at a point along the length of the strut 200c, near the end of the strut closest to the pile 400c. The other struts 200a, 200b will also be provided with turnbuckles in a similar fashion; the relevant turnbuckles 300a, 300b can be seen in the later figures.

In preferred embodiments, strut 200c may be provided with a flange 250c extending therefrom and having an attachment point 260c.

The struts 200a, 200b, and 200c are substantially identical except for the extension member and the angle at which the ends of the struts 200a, 200b, and 200c meet the pin joints 220a, 220b, 220c. As can be seen in Figure 1, strut 200c is substantially straight along its whole length, while struts 200a and 200b are bent at the ends thereof. The rotational axis of pin joint 220c is perpendicular to strut 200c.

Struts 200a and 200b meet pin joints 220a and 220b at an angle, such that the pin joints are oriented to pivot about a common axis X-X. Axis X-X is not perpendicular to the longitudinal axes of struts 200a and 200b.

Advantageously, the use of struts for supporting the mast at a point along its length (above ground level when the mast is vertical) reduces the maximum bending moment in the mast produced by perpendicular loading (caused by wind, or during installation), as compared with a mast that is merely mounted on a base bolted to a foundation. For example, when the mast is erected by rotation about axis X-X, it is supported via the struts 200a, 200b, 200c at a point distant from this axis. The maximum bending moment is therefore at this supported point rather than at the base of the mast.

Accordingly, a narrower mast can be used to support the turbine.

Furthermore, a base mounted mast is supported by tension along one side of the mast and compression along the opposite side. When a 15m the mast is supported by struts at a point 5m along its length, the compression of the struts and resistance to shear at the attachment points support the Sm point so that the maximum bending moment is reduced by a third. The load in the attachment points of the struts would be an order of magnitude small than in an equivalent number of bolts of a base mounted mast.

In preferred embodiments, the struts will meet the mast at an angle in the range of 200 to 40°. Preferably, the length of the struts will be in the range of 2m to Sm. Ideally, the struts will have a diameter of 45mm to 75mm.

Preferably, the struts will be formed of steel (ideally, galvanised).

Figure 3 shows a helical pile 400 in place in the ground 10.

A helical pile 400 comprises a cylindrical body 410 and two screw threads 420. A portion 430 of the cylindrical body 410 protrudes from the ground 10. A pin joint 220a, 220b, 220c (see earlier figures) is formed on the top of the protruding portion 430.

The two screw threads 420 of the helical pile are in the form of large flat plates. The pitch of each thread 420 is different, such that when drilled into the ground 10, the soil is compressed between progressively close threads 420.

This compression leads to an increase in the torque required to drive the pile 400 further into the ground. The driving torque can be sensed using known methods. A minimum threshold of driving torque must be reached to ensure that a pile 400 is sufficiently held in the ground 10, while a maximum threshold is used to prevent damage to the pile 400 and/or driving apparatus.

The helical piles 400 are driven into the ground so that each protrudes by a predetermined amount, thereby providing three mounting points in the form of the pin joints 220a, 220b, 220c that have approximately equal height irrespective of the gradient of the ground 10.

Advantageously, the length of each turnbuckle 300a, 300b, 300c can be adjusted. By adjusting each turnbuckle 300a, 300b, 300c, the orientation of the mast 100 can be altered.

For large alterations, the struts 200a, 200b, 200c will not meet the pin joints 220a, 220b, 22Cc exactly perpendicular to the pins. However, in preferred embodiments the pin joints 220a, 220b, 220c will tolerate minor deflections in the struts 200a, 200b, 20Cc. In further preferred embodiments, the pin of the pin joints 220a, 220b, 220c is a bolt that can be loosened to allow deflection and tightened once the turnbuckles 300a, 300b, 300c have been set and the mast aligned.

Pin joint 220c releasably connects the strut 200c to helical pile 400c. Thus the strut 200c can be released from pile 400c to allow the struts 200a, 200b to rotate about axis X-x.

As can be seen in figures 4a, 4b, 4c and 5, a linkage and an actuator may be provided to aid the installation of the wind turbine.

In such embodiments the linkage is connected between the extension member 250c and the helical pile 40Cc.

Preferably, the linkage is connected to the pin joint 220c.

The linkage is rotatably connected to the attachment point 26Cc on flange 50.

The linkage is formed of three links of the same length, a pair of links SOOb sandwich a third link 500a as seen in Figure 5. The symmetry provided by the two links 500b prevents a torque from being imposed on the joints of the linkage. The link 500a is pivotably connected at one end to the pile 400a and at the other end to the links 500b. The links 500b are connected between the attachment point 260c and the ends of links 500b.

An actuator, in the form of two hydraulic rams 600a (shown in figure 4) and 600b (not shown in figure 4) is provided.

Hydraulic rams 600a, 600b extend linearly under the action of hydraulic pressure. Each hydraulic ram 600a, 600b is rotatably attached at one end to the links 500a, 500b by a joint 510, and at the other end to a respective pile 400a, 400b.

The following describes a preferred embodiment of a method of installing a wind turbine in accordance with the invention.

Three helical piles 400a, 400b, and 400c are driven into the ground 10 until a portion 430 of desired length of the cylindrical body 410 protrudes from the ground.

The length of the protrusion 430 is such that the height of the top of each pile 400 is roughly equal. Owing to the adjustability of the turnbuckles 300, high precision in the determination of the length of the protrusion 430 is not required, nor is it necessary for the helical piles to be located, when viewed in plan from above after installation, at the corners of an equilateral triangle.

Further steps of the method are shown in Figures 4a, 4b, and 4c.

In figure 4a, the mast 100, with a wind turbine attached at its far end (not shown), is supported in an approximately horizontal orientation and the mast 100 is connected to helical pile 400a (shown in Figure 4a) and helical pile 400b (not visible in Figure 4a) such that it may rotate about the axis X-X through joints 220a and 22Db formed thereon.

The hydraulic rams 600a, 600b are in a shortened state, corresponding with, the orientation of the mast 100.

In figure 4b, the hydraulic rams 600a, 600b are extended, folding the linkage formed by links 500a and 50Db, to thereby draw the flange 250c towards the pile 400c.

Consequently, the mast 100 is rotated about the axis X-X towards a vertical orientation.

In figure 4c, hydraulic rams GOOa, 600b are shown in a fully extended state and the linkage formed by links 500a, 500b is folded such that the ends thereof are spaced apart by the extension member 250c. The end of strut 200c is coupled to the pile 400c by the pin joint 220c.

The linkage used in the method shown in figures 4a, 4b and 4c provides a mechanical advantage as compared with simply locating the hydraulic ram below the mast.

The mast has been rotated to a near vertical position. As stated above, at this stage the accuracy of the vertical orientation of the mast is dependent upon the accuracy of -10 -the method by which the piles were located. Advantageously, it is not essential for the piles to be accurately aligned, since further adjustment can be effected to correct any misalignment of the mast 100 by lengthening of shortening the turnbuckles 300a, 300b, 300c by an appropriate amount.

In preferred embodiments, a laser pointer may be mountable on the mast 100 for alignment therewith to shine a bright visible dot on the ground to provide an indication of the orientation of the mast 100 whilst the turnbuckles 300 are being adjusted.

Optionally, when strut 200c has been coupled to the pin joint 400c by the releasable pin joint 220c, the hydraulic rams 600a, 600b can be removed. These components can therefore be used again in the installation of a different wind turbine.

Advantageously, the above method of installing a wind turbine does not permanently orient the mast 100 in a vertical position and is free to be lowered if, for example, maintenance is required. By re-attaching the linkage formed by links 500a, 500b and the hydraulic rams 600a, 600b and releasing the pin joint 220c to decouple the link 200c from the pile 400c, the mast is again free to rotate about pin joints 220a and 220b, and can be lowered back to a horizontal position.

Since attachment point 260c is spaced from the helical pile 400c by the flange 250c, the ends of the links 500a, 500b are separated. That is, the linkage is not fully collapsed (see figure 4c) . Therefore, if the actuators 600a, 600b are -11 -extended and attached to joint 510, retraction of the actuators will draw the joint 510 towards the axis X-X through pin joints 220a, 220b and rotate the mast 100 towards a horizontal orientation.

Whilst in the embodiments described above each turnbuckle 300 is attached to a strut 200a, 200b, 200c at some point along its length, it is possible for the turnbuckles 300a, 300b, 300c to be attached directly to the pin joints 220.

In the case of strut 200c and turnbuckle 300c, this joint will be detachable for attachment to pin joint 220c at the top of protrusion 430.

It is not necessary for turnbuckles 300a, 300b, 300c to be attached near the end of the mast 100 (when erect) with struts 200 attached to a point near the higher end of the mast 100 (when erect) . The opposite arrangement, in which the struts 200a, 200b, 200c are attached closer to the lower end of the mast 100 than the turnbuckles 300a, 300b, 300c, is also possible. In fact, it is also envisaged that struts 200a, 200b, 200c could be formed as turnbuckles, which may be advantageous if piles 400a, 400b, 400c are positioned inaccurately.

The embodiments presented above disclose a wind turbine support 50 having three struts. However, more struts are possible to provide greater support to the mast 100. In the case of having a greater number of struts, a first plurality of struts would be connected to pin joints having collinear rotational axes, whilst a second plurality of struts would have releasable pin joints that attach the struts to the piles when the mast is rotated to a vertical orientation.

-12 -With regard to the method of using a linkage comprising links 500a, 500b to erect the mast, it is noted that this method could be applied to a solid support, such as a grillage or a solid plate, which would pivot about one side.

Thus this method can be used to erect a mast 100 on a concrete surface into which piles cannot be embedded.

Whilst the above describes the installation of the disclosed support using a linkage and hydraulic rams. It is possible to install the mast with the support using a gin pole and winch, as is known in the art.

Claims

-13 -CLAIMS: 1. A wind turbine support assembly comprising: a mast; a foundation; at least first, second and third struts, each pivotably connected at first ends to the mast at a first set of connection points; at least first, second and third pivots for respectively pivotably connecting second ends of the first, second and third struts to the foundation; at least first, second and third adjustable length links pivotably connected at first ends to the mast at a second set of connection points spaced apart from the first set of connection points and pivotably connected at second ends respectively to either the first, second and third struts or the first, second and third pivots, wherein: the first, second, and third pivots are spaced apart so that when the mast is erect and the struts are connected between the mast and the pivot points then the struts are angularly spaced apart when viewed in a plan view; and vertical orientation of the mast can be adjusted by adjusting the lengths of the first second and third adjustable length links.
2. A wind turbine support assembly as claimed in claim 1, wherein: the first and second pivots together define an axis of rotation; the third pivot comprises a releasable coupling by which the third strut is connected to the pivot; -14 -an actuator is provided for rotating the mast, whereby when the releasable coupling is released, then the mast can be pivoted between a substantially horizontal position and a substantially vertical position.
3. The support assembly of claim 2, wherein the actuator is a hydraulic ram.
4. The support assembly of any one of claims 1 to 3, wherein the foundation comprises at least first, second and third piles, each of the first, second and third pivots being mounted on a respective pile.
5. The support assembly of any preceding claim, wherein the actuator is connected to a linkage with a first end of the actuator connected to a joint connecting two links of the linkage.
6. The support assembly of claim 5, wherein the linkage is pivotably connected at a first end to a pivot on a flange provided on the third strut.
7. The support assembly of claim 6, wherein the linkage is pivotably connected at a second end to either or both of the first and second pivots.
8. The support assembly of any one of claims 5 to 7, further comprising a second actuator connected to the joint connecting the two links of the linkage.
9. The support assembly of any preceding claim, wherein the length of the mast is in the range of 9m to 30m.

-15 -
10. The support assembly of any preceding claim, wherein the length of the mast is substantially l5m.
11. Use of the support assembly of any preceding claim, suitable to support a wind turbine of power output in the range of 2kW to 50kw.
12. Use of the support assembly of any one of claims 1 to 10 to support a wind turbine of power output of substantially 5kW.
13. The support assembly of any one of the preceding claims wherein the adjustable length links comprise turnbuckles.
14. A method of installing a small wind turbine, comprising the steps of: providing at least three pivots; using a mast to support the wind turbine in an elevated position; connecting the mast to first, second and third pivots using respectively first, second and third struts, each pivotably connected at one end to the mast and at the other end to a respective one of the pivots; connecting at least first, second and third variable length links between the mast and respectively either the first, second and third struts or the first, second and third pivots; adjusting the length of the variable length links to vary vertical orientation of the mast when erect.
15. The method of claim 14 comprising also: -16 -connecting a first ram to a linkage connected between the mast and the foundation; extending the first ram to thereby pivot the mast about an axis defined by the first and second pivots
16. The method of claim 15, further comprising the steps of: connecting a second ram to the linkage; and extending the second ram in synchronisation with the first ram.
17. The method of of claim 15 or claim 16, wherein the linkage is connected to the mast at a point vertically spaced from the axis of rotation 18. The method of any one of claims 14 to 17, wherein the piles are driven to provide the foundation.19. The method of claim 18, wherein the piles are driven a predetermined distance into the ground and each of the three pivots is mounted on a respective one of the piles.Amendment to the claims have been filed as follows -17 1. A wind turbine support assembly comprising: a mast; a foundation; at least first, second and third struts, each pivotably connected at first ends to the mast at a first set of connection points; at least first, second and third pivots for respectively pivotably connecting second ends of the first, second and third struts to the foundation; at least first, second and third adjustable length links pivotably connected at first ends to the mast at a second set of connection points spaced apart from the first set of connection points and pivotably connected at second ends respectively to either the first, second and third : :11 struts or the first, second and third pivots, * wherein: the first, second, and third pivots are spaced apart so that when the mast is erect and the struts are connected *** ** S * between the mast and the pivot points then the struts are angularly spaced apart when viewed in a plan view; vertical orientation of the mast can be adjusted by adjusting the lengths of the first second and third adjustable length links; the first and second pivots together define an axis of rotation; the third pivot comprises a releasable coupling by which the third strut is connected to the pivot; and an actuator is provided for rotating the mast, whereby when the releasable coupling is released, then the mast can be pivoted between a substantially horizontal position and a substantially vertical position.2. The support assembly of claim 1, wherein the actuator is a hydraulic ram.3. The support assembly of claim 1 or claim 2, wherein the foundation comprises at least first, second and third piles, each of the first, second and third pivots being mounted on a respective pile.4. The support assembly of any preceding claim, wherein the actuator is connected to a linkage with a first end of e..the actuator connected to a joint connecting two links of the linkage. S.: 5. The support assembly of claim 4, wherein the linkage isSS* pivotably connected at a first end to a pivot on a flange *:::: provided on the third strut. * 20S.....* 6. The support assembly of claim 5, wherein the linkage is pivotably connected at a second end to either or both of the first and second pivots.7. The support assembly of any one of claims 4 to 6, further comprising a second actuator connected to the joint connecting the two links of the linkage.8. The support assembly of any preceding claim, wherein the length of the mast is in the range of 9m to 30m.9. The support assembly of any preceding claim, wherein the length of the mast is substantially 15m.10. Use of the support assembly of any preceding claim, suitable to support a wind turbine of power output in the range of 2kw to 50kw.11. Use of the support assembly of any one of claims 1 to 9 to support a wind turbine of power output of substantially 5kw.12. The support assembly of any one of the preceding claims wherein the adjustable length links comprise turnbuckles. * S SS *S13. A method of installing a small wind turbine, comprising the steps of: providing at least three pivots; * using a mast to support the wind turbine in an elevated *:::: position; connecting the mast to first and second pivots using respectively first and second struts, each pivotably connected at one end to the mast and at the other end to a respective one of the pivots, the first and second pivots together defining an axis of rotation; using an actuator to rotate the mast between a substantially horizontal position and a substantially vertical position; connecting the mast to a third pivot using a third strut pivotably connected at one end to the mast and at the other end to a respective one of the pivots; connecting at least first, second and third variable length links between the mast and respectively either the first, second and third struts or the first, second and third pivots; adjusting the length of the variable length links to vary vertical orientation of the mast when erect.14. The method of claim 13 comprising also: connecting a first ram to a linkage connected between the mast and the foundation; extending the first ram to thereby pivot the mast about an axis defined by the first and second pivots 15. The method of claim 14, further comprising the steps of: connecting a second ram to the linkage; and 15 extending the second ram in synchronisation with the first ram. * S * *** * S..* 16. The method of claim 14 or claim 15, wherein the linkage is connected to the mast at a point vertically spaced from the axis of rotation 17. The method of any one of claims 13 to 16, wherein piles are driven to provide a foundation to support the pivots.
18. The method of claim 17, wherein the piles are driven a predetermined distance into the ground and each of the three pivots is mounted on a respective one of the piles.