WO1996013663A1

WO1996013663A1 - Device for wind power plants

Info

Publication number: WO1996013663A1
Application number: PCT/SE1995/001293
Authority: WO
Inventors: Bruno SJÖDIN
Original assignee: Sjoedin Bruno
Priority date: 1994-11-01
Filing date: 1995-11-01
Publication date: 1996-05-09
Also published as: AU3857995A

Abstract

The invention refers to a device for wind power plants, in which a wind turbine (1) is situated on top of a mast (2). The turbine axis (3) of the wind turbine (1) is journalled essentially parallel to the centre line of the mast. The mast (2) is at least partly flexible, so that the tare of the wind turbine brings the top of the mast and the turbine axis into an inclined position in relation to the vertical plane.

Description

DEVICE FOR WIND POWER PLANTS

Present invention refers to a device for wind power plants, in which the wind turbine is situated on top of a mast.

BACKGROUND OF THE INVENTION

Conventional wind power plants usually consist of a tower with a machinery comprising horizontal axis on the top. To be able to set the wind power plant in correct direction, a turning bearing is arranged, usually a large gearwheel, on the top of the tower. With information from a wind indicator, an auxiliary engine revolves the wind turbine and machinery on said turning bearing. Smaller plants are self turned by means of a fin or the like, but the basic principle is the same.

Some problems are related to the technique of today. Extremely significant demands are directed on equipment, which in an extremely exposed position partly can probably hold firm the heavy machinery, partly allow it revolving itself. This applies to both the mechanics, and the control and adjustment technics. The demands result in large weights and high costs. The complicated technique renders breakdowns, which cause high maintenances and lost of production time.

A consequence of the large weights is that the plants become bulky and difficult to place in a landscape, since they are interpreted as visual disturbance.

The wind power plants of today can be summarized in terms of being rigid, heavy, rough and containing high technique, by having many complicated included components with relatively short life.

One consequence, due to the problems with conventional wind power plants, is trying to eliminate the gearbox, since it has indicated to be the part, especially exposed to damages. The direct driven generator, without a gearbox, has premises to be lighter than a traditional generator with a gearbox. Technically and economically it also can be an advantage, if the direct driven generator has a large radius. In other words, the new generator technique does not change the obvious desire to have the machinery on a lower level than at the top of a tower.

There is an assembly, so-called Darrieus swivel, comprising vertical arched blades, which has the proper feature of having the machinery arranged at a low level, but this construction despite that, has become outclassed by the horizontally arranged propeller, for instance due to a large starting momentum and having too small sweeping surface.

THE OBJECT OF THE INVENTION AND MOST IMPORTANT FEATURES

The object of the invention is to overcome the above problems, ie. to reduce the large mechanical strains, to which the wind turbine and its transmission are exposed to, substantially to reduce the weight at the top of the tower or mast, to reduce the number of moving parts and thereby to obtain a simpler, more reliable and cheaper assembly, which also requires less maintenance. Another object is to make the wind power plant self-adjusting, so that it adjusts itself according to wind direction and wind velocity. To minimize the visual disturbance, efforts have been made to make the plants as slender as possible.

These tasks have been solved by arranging the turbine axis of the wind turbine essentially parallel to the centre line of the mast, and that the mast at least is partly flexible, so that the tare of the wind turbine brings the top of the mast and the turbine axis to an inclination position relative the vertical plane.

DESCRIPTION OF THE DRAWINGS

The invention will be described closer referring to some embodiments, with reference to the attached drawings.

Figure 1 shows the wind power plant according to the invention in a lateral view and in three different positions, a first position, shown with solid lines, with the wind turbine in passive position, ie. at calm, a second position, shown with dash-point lines, with a turbine in a position, at normal wind forces, and a third position, shown with dash-double-point lines, at extremely hard wind. Figure 2 shows, in a smaller scale, the wind power plant according to the invention in a lateral view, with an inclined foundation and flexible top.

Figure 3 shows a sea-based wind power plant, according to the invention, in a lateral view.

Figure 4 shows, in an enlarged scale, a cross-section through two alternative embodiments of the foundation of the wind power plant, where the left half of the drawing shows a land-based foundation and the right half a pontoon or the like, on which foundation a wind power plant machinery is situated. DESCRIPTION OF EMBODIMENTS

The wind power plant shown in fig. 1 consists of a wind turbine 1, mounted on the top of a flexible mast 2 with the turbine axis 3 journalled, so that it is essentially parallel to the longitudinal axis of the mast. The mast is supported on a foundation 4 and its wind power machinery, e.g. including a transmission 5 and a generator 6 can be provided at the top of the mast and/or at the foot of the mast. In the embodiment shown the transmission 5, e.g. a gearbox, is located at the top of the mast and an electricity generator 6 at the foot of the mas .

The mast 2 or the top of the mast is flexible in such extent that the tare of the wind turbine 1 causes the top of the mast and thereby the turbine axis 3essentially to take a horizontal position, when the wind power plant is in operation. Since the mast or at least its upper portion is flexible in all directions, the wind turbine through the influence of the wind automatically turns itself so that the turbine comes into the leewards of the mast. This feature is obtained by that, the mast, at least in its upper portion being flexible, as shown in the drawings, or by consisting of a combination of rigid and flexible parts (not shown in fig.) The simplest of these variants is a rigid lower part and a flexible mast top.

By allowing the mast flexibility, ie. certain elasticity, the strains on the mechanical parts (for example the turbine bearing) of the plant are reduced. For same objects the turbine blade is made more slender and flexible, so that the sweep area is reduced at hard winds, as it is shown in fig. 1 with dashed-double-pointed lines. Accordingly, the idea enables alternative location of the generator and possible transmission. The traditional location of the generator at top of the mast is substituted as far as possible through placement at the foot of the mast. In the later case, the transmission of the power from the wind turbine 1 to the generator 6 is achieved through a flexible or articulated axis, hydraulic or pneumatic conductors or the like, preferably inside the mast.

Figures 2 and 3 show a modified wind power plant according to the invention, where the wind turbine 1 is firmly mounted on the mast 2, so that it turns when the turbine 1 rotates, i.e. the mast can be regarded as a long flexible axis.

Figure 2 shows an example where the mast 2 consists of a flexible upper part 7 and more stiff, straight lower part 8. The rotating mast 2 conveys the force down to the machinery 6. Owing to the flexible mast turbine it automatically sets itself to the wind direction. To provide the axis as horizontal as possible, the foundation 4 may be provided so that the upper part is tiltable and follows the mast, so that the foundation inclines towards the lee. The solution shown on the drawing represents the simplest solution, with the upper part of the foundation situated on a ring of springs.

The flexibility of the upper part of the mast can be obtained, for instance through a coil spring of steel or titanium alloy and it is arranged included in a high quality rubber mass (based on polyurethane or similar, for example

"Trekollan") • Both materials cooperate in such a way that the coil spring first absorbs the torque (pulling) from the turbine and the rubber material absorbs the weight and the tensile stress. To maximize the strain, one can as an extra precautionary measure set a reinforcement of aramide fibre or the like.

Figure 3 shows an example of a sea-based wind power plant, where the wind turbine 1 is firmly mounted on an inclined and slightly bent mast 2. The rotating mast conducts the force down to the machinery, which in this case consists only of a generator 6 situated at the foot of the mast. The foundation 4 consists of a floating platform 9, for example by means of a pontoon firmly anchored to the sea bed by means of mooring ropes 11. On the top of the foundation - pontoon - a turntable is arranged, so that the wind power plant can freely revolve and automatically place itself in the wind direction. The platform 9 may be so made that it also serves as a breakwater. The buoyancy and shape stiffness of the platform balances the weight of the turbine and the mast, and a keel may be required to moderate the movements in the sea further.

The wind power plant can also be made on a caisson, firmly founded on the sea bed or if the local conditions allow on a tower.

Figure 4 shows an example on how an inclined mast 2 with a generator 6 situated at the foot of the mast can be supported by a foundation 4. The mast, which preferably of carbon fibre or the like, is equipped with an end portion 12 of steel, carried in the frame of the engine housing 13. The engine housing is mounted on the generator house 15 revolving in the vertical plane about an axis 14, in which house a multi-terminal generator 6 with a rotor 16 is arranged, which is directly connected to the end portion 12 of the mast and which rotor is characterized by its large radius. Further, in the generator house 15 is provided disc brakes 17, for braking and fixation of the rotor.

The foundation of figure 4 is illustrated using two alternative embodiments, a land based and a sea-based foundation. Common for both is that, they are provided with a horizontal platform 18 at the top, which is formed as a turntable and which through bearing means 19 is rotatable so that the wind power plant by means of the wind sets itself in the wind direction.

By means of a setting device (not shown) , which is connected to a holder 21 at the generator house 15 and a holder 22 at the turntable 18, the wind power plant can from a vertical plane, from a downwards turned assembly position, with the wind turbine close to the ground level, be turned in to a turned up position, in which the wind turbine can be activated. Eventually, the mast is lowered to an essentially horizontal level when the wind is so strong (storm) that the wind power plant may be damaged.

A sea-based, close to shore plant of wind power stations can be so formed that the foundation's anchorage cooperates with wave power plant's anchorage. The advantages of locating the wind and wave power plants in same place in this way will be many. The wave power plant damps the waves for the floating platforms of the wind power plants and large investments can be used at same time. An example of such investments is anchorage means, shore cable, safety systems, as well as management and maintenance. The floating platforms can be used as anchorage for and as working platforms for mussel and pisciculture.

As it appears from figure 1, the wind turbine 1 is so designed that it also protects the wind power plant from very high wind velocity. The turbine blade is stall adjusted, which implies that the wings are firm (unlike so- called "the pitch adjustment", where the blades are turned mechanically through high wind velocities) and the wing profile is so designed that at a certain velocity of wind the aerodynamic around the wing profile becomes so deteriorated that the speed of rotation reduces or even ceases, although the wind velocity increases. Moreover, in this case the blades are so constructed that at wind velocities over "the stall wind" the soft composite blades bend back and thereby reduce the sweep area and stresses on the plant. (On the drawing a propeller comprising two blades is shown which is good from the weight point of view, but propellers having three blades are preferred, especially because of the balancing reasons.)

Also, all overloading and security systems, which are used in the traditional wind power plants can be used in present concept, but efforts are made to use as little as possible wind brakes, mechanical brakes etc., and instead absorb the forces in the structure of the plant by means of the elasticity of the mast and rotor.

In the above description, it is stated that the wind power plant automatically turns itself so that the turbine is positioned in the leewards of the mast. It is of course possible, within the scope of the invention and through known methods, to turn the plant through influence of the wind so that the turbine turns towards the wind.

Claims

CLAIM

1. A device for wind power plant, in which a wind turbine (1) is situated on top of a mast (2), c h a r a c t e r i z e d in, that turbine axis (3) of the wind turbine (1) is journalled essentially parallel to the centre line of the mast, and that the mast (2) is at least partly flexible, so that the tare of the wind turbine brings the top of the mast and the turbine axis into an inclined position in relation to the vertical plane.

2. A device according to claim 1, c h a r a c t e r i z e d in, that mast (2) through influence of the wind, at least in its upper part has more flexibility than in the remaining part of the mast.

3. Device according to claim 1 or 2 , c h a r a c t e r i z e d in, that the blade of the wind turbine (1) is flexible in a direction of the leeward side of the wind power plant at influence of the wind.

4. A device according to any of preceding claims, c h a r a c t e r i z e d in, that the mast (2) consists of several rigid parts combined with several flexible parts.

5. A device according to any of preceding claims, c h a r a c t e r i z e d in, that the generator (6) and possible transmission (5) of the wind power plant is firmly mounted on the top of the mast and/or at the foot of the mast or in the foundation, and that said plant is provided with means for transmission of the power from the wind turbine to the generator or the like, which means comprises a flexible or articulated axis, hydraulic or pneumatic conductors, which are arranged inside the mast.

6. A device according to claim 1, c h a r a c t e r i z e d in, that the wind turbine (1) is firmly mounted to the mast (2) in such a way that the mast rotates with the wind turbine and thereby conducts the power down to machinery, e.g. an electricity generator (6) , placed in lower position.

7. A device according to claim 1, c h a r a c t e r i z e d in, that mast inclines in relation to the vertical line.

8. A device according to any of preceding claim, c h a r a c t e r i z e d in, that the wind power plant is arranged to set itself in the wind direction by means of the mast (2) , preferably at the foot of the mast or a foundation (4) to connected it is rotatable.

9. A device according to any of preceding claims, c h a r a c t e r i z e d in, that the mast (2) is rotatable in relation to the foundation (4) in the vertical plane by means of a setting device (20) and fixable in a wanted position.

10. A device according to claim 1, c h a r a c t e r i z e d in, that the foundation (4) is firmly anchored on the ground, on a tower or by means of a caisson on the sea bed, alternatively supported by means of a floating platform, e.g. a pontoon, or the like.