WO2000045050A1

WO2000045050A1 - Wind power plant

Info

Publication number: WO2000045050A1
Application number: PCT/SE2000/000155
Authority: WO
Inventors: Alf Israelsson
Original assignee: Alf Israelsson
Priority date: 1999-01-27
Filing date: 2000-01-27
Publication date: 2000-08-03
Also published as: SE9900246L; SE9900246D0; AU2585500A

Abstract

Concerning existing propeller-driven wind power plants, weight increases faster than effect, with increasing radii of the wings, thereby the costs, which has the result that plants are becoming unprofitable when they go beyond a certain size. This problem has been solved by many off-line wind absorbing blades (11) each of them is attached to a carriage (12), that runs along a closed track (13, 14). Energy is outlet through linear electrical generators (32, 33) placed along the closed track without any moving parts except for the details of the generators (33), which are attached to the carriages. The plant tolerates an extension laterally, which involves an increase of power, with low increase in weight and low rise of costs. The plant is raised and lowered for overhaul by winches, at which a frame construction (4) is attached by bearings of the rotable bedding and momentarily to the ground base plate, which even can consist of seabased pontoons or the like.

Description

Wind Power Plant

This invention concern^'s a wind power plant with many wind absorbing blades arranged in parallel and attached to carriages which move around one, above all laterally, extensible closed circuit with linear generators located alongside the endless track without any moving parts with the exception of the details of the generators attached to the carriages. The plant is constructed by framework towers connected by other frameworks forming a framework construction which rest on a bedding in order to put the plant in a right angle towards the direction of the wind.

The purpose of the invention is to obtain a wind power plant built up of very large units with good profitability, high safety of operations and requiring close to non maintenance.

Background of the Invention

Large wind power plants have many advantages compared to smaller ones. From the aesthetical and preservation of natural amenities aspects it is needed a minimum of encroachment on the landscape, which is easier to achive with a small number of large rather than a large number of small wind power plants, obtaining the same sum of power. Considering the landarea the advantages with large plants is obvious, since each plant, independent of size, not land, requires very large surrounding free areas, which cannot be used for other purposes. For overhaul and maintenance it is needed as much time for a large as for a small plant. Furthermore large electrical machines are considerably more effective than small ones. However the manufacturing costs for wind power plants of propeller shape increase more rapidly than the available power the larger the plants are. This has the effect that very large plants cannot be made profitable with the technique of today.

Wind absorbing blade effect - blade weight - total costs

The energy obtained by a conventional wind power plant of propellerform is proportional to the swept area of the propeller. Furthermore a large wind power plant obtains a larger effect due to the greater windforces on the higher altitude. But unfortunately the propellers gain weight faster than the effect increases with increasing size, since the weight of the propellers in a conventional propellerplant with two or three blades increases in proportion to the cubic of the radie of the propeller, because the volume of the material is the product of the length, breadth and thickness of the material and because all three approximately increase in proportion to the size. Accordingly the cost of the plant increases in a similar way. The effect however increase in proportion to the swept area i. e. only in square. Consequently there exist an upper limit for profitable size for the conventional plants of propellermodel.

Environmental and aestetic considerations

To allow these small wind turbines to occupy the territories around the coasts and on the seward skerries would be devastating from an environmental and aestetic point of view as well as considering an effective use of these areas. The bird population would be disturbed far less by a single large plant with for example a total of 250 m of diameter laterally than by 20 plants of medium size with same sum of power but with at least 3-5 km tangent surface both laterally and depthways between the outermost plants. The same argument can be used for the aestetical comparison between the two alternatives. Efficiency

High efficiency is obtaind above all with multy-blade propellers containing narrow blades. But, for a conventional propellerplant, the space around the hub will then be too narrow around the solid holds of the blades, for what reason one today build propellers with two or three blades which rotate with high speed, so-called high-speed propellers, at which long blade length give better efficiency than shorter. The actual efficiency will be lower, above all after a long time of operation when the evenness of the blades deteriorate, at which time the difference in efficiency between long and short bladelength equalize as well.

Pitch angle regulation

Concerning wind absorbing blades of propellermodel it has not up to now been possible to arrange a change of pitch angle for a propeller model with many blades. But pitch angle regulation is necessary to adjust the power at high velocity and for avoidance of stress during storm. With a small number of blades it is true that it is relatively easy and cheep to create devices for pitch angle regulations, but the disadvantage lies in the fact that every small radially spread part of the propeller preferably should have its own specific angle of rotation for a particular wind and rotation velocity. As an example 2 degrees turning will have great effect on the outher parts of a propeller, but hardly any effect at all on the inner parts closer to the shaft. So far this has been solved by pitch angle regulating the outher parts of the blade separately.

Stress caused by wind

As the wind force increases with altitude a conventional propeller plant - especially the very large two-bladed, which according to the reasoning above should be the most interesting of the conventional plants - additional serious side-effects unfortunately will supervene; a turbine with the radie of 60 m, the tip of the blade can be at 200 m altitude and the lower at the same time at 80 m altitude. Half a second later it is reverse. The turbine shaft and blades are exposed to pulsating moments, and because the blades of wind power plants with the power of more than 2 MW solely have a combined mass that can exceed 60 tons, the stress will be enormous.

Price raising supplements

Another disadvantage with conventional wind power plants of the propellertype is that the electrical generator need relatively large cog gear change as a result of the low rate of rotary speed of the propeller with a large diameter, approximately 20-30 numbers of revolutions per minute, despite a large "snabblδptal" which raises the price of the plant at which those and all other machinery parts are placed in a rotary engine house arranged on a comprehensive rotation device which will circulate in accordance to the peak of a high tower, which will, apart from the usage of material from the aspect of structural strength, obstract montage, maintenance and repairs.

The (use of) landarea

The propellerturbine describes a circular surface which is a bad utilization of the windarea, since the velocity of the wind decreases downward and as the side extension is limited. Many small propeller power plants placed at a distance of many hundred meters from each other is an even worser exploitation of the surrounding area, since they must be placed at a relative far distance from each other, up to 1 km, not to get into each outhers wind-shadow. For this reason it is important that each plant cowers a much broader area.

Noise pollution on the environment

Noise is an important factor in localization of the wind power plants and in determining how close to settlement they can be located. The noise consists principally of two components; machine noise and aerodynamic noise. By introducing linear generators the only machine noise that remain on blade level is that produced by the rolling contact between the carriages and the tracks. Shaft bearings for a linear movement are arranged for the conveyance of the carriages, or if the wheels are provided with a noise-suppressing shed, the noise will be decreased down to relatively low values. The aerodynamic whispering sound, which with two-bladed turbines, do not appear in the present plant.

When extending an existing conventional wind power plant it is necessary to add new plants at a certain shortest distance from the existing one. When enlarging the existing plant the wings and meny more details must be changed. But, as mentioned before, the costs increase faster than the power obtained by increasing the wing radie. At the present at the actual plant the wind absorbing blades must not be extended in order to increase the swept area, at which all available plant details, wings, linear generator details an so on are allowed to, in the existing shape, be included in the plant. But the swept area in the present plant can also be enlarged by extending the blades without exponentional weight enlargement which is guilty for conventional propeller blades, as the blades in all its length permits approximately the same bredth as the aerodynamic conditions are essentially the same for the whole winglength at least in a large part of the track, with the exception outermost bendingpart of the track.

Proposed principal solutions

To manage with the disadvantages named above in the actual wind power plant the following form of execution and arrangements have been introduced: a. Selecting many narrow parallely arranged wind absorbing blades moving with medium speed compared with the outher parts in a conventional fast propellerturbine. This choice gives, according to up to now known theories and attempts, very high efficiency of the wind absorbing blades.

b. The blades are attached symmetrically to the carriages, connected one after the other in an oblong and closed track at which a swept effect area is received with the possibility to optional size, without, for that sake, the effect area and the weight of the plant will increase more than the received power, as the blades and its attachments are regularly divided over the whole track.

This can be compared with blades of propellertype whose complete mass is concentrated to only one point in the hub with the strains and rise in the prizes of the components this involves. Each blade can also be designed with a considerably lower mass than a conventional propellerblade of the same length.

c. Energy outlet will be done by several independent sectors along the track by linear generators completely free from axles, bearings, gear reduction sets, and so on. Besides the independence of these components, which lead to cheeper production costs. The oversight and repairs will as well be considerably lower compared to conventional plants. The linear generators are desfgned tnaY each can be connected or disconnected when necessary, which involve variably rated output of the plant and by that a better utilization of moderate winds.

e. The carriages are arranged either with travelling wheels or journal, bearings for essentially linear motion designed to permit some curvature of the track.

f. The pitch angle regulation will be performed by correcting units attached to each blade. Because the blade will be moving on an oblong track with partially almost straight sections, apply for a large part of the track a specific blade angle essentially for the full extent of the blade contrary to an ordinary propeller, where every radially spread part of the blade in the whole circulation, demand its own blade angle at a certain rotation- and windcondition, something that only partially is possble to realize.

g. A structural element for the wind absorbing blades , which rest rotary on a bed, which always adjust itself in a straight angle against the wind. h. The structural element is equipped with turnable holders attached to carriages and with turnable holders attached to the ground. This makes it possible to quickly and easily raise and lower the plant with winches or the like for maintenance or overhaul.

Differences compared with wind power plants earlier known arranged with wind absorbing blades which run along a closed track.

Wind power plants according to the patents Dl.US, A, 4930985, D2: US, A, 3 504988, D3: US, A, 4589344, D4: US, A, 4303 834, D5: DE, Al, 3304825. All include many wind absorbing blades who runs in a closed track. However the power outlet in these plants are not done through linear generators arranged along the whole or parts of the closed track. Neither are the blades in these arranged with satisfactory holders attached to the closed track. They are not stable enough. With only one attachement vertically for each blade and not as in the present wind power plant with two outher attachements in the longitudinal direction for the blades on each side of and on a relativly long distans from the carriages. From the essential centre line of the carriages, the track and also the blades, at which a very stable grip of the blades are achived. In D4 the blades are arranged whith a central holder, but not attached to the carriage but to at least one endless cable lacking a solid track. In D5 the blades are in its entity attached to the upper part of the upper track or on the lower part of the return track at which the track consists of an oval pipe or the like. In D2 and D3 the blades both running directions are placed at the same level at which the blades on the back part of the track, considering the direction of the wind, land up in the leeward of the former with considerably less effect Special description of the invention and its essential characteristics

Description of the drawings

Fig 1 shows a view from the front, that is in the direction of the wind, of one half of a complete plant.

Fig 2 shows a cross section straight through the long direction of a complete plant.

Fig 3 shows a top view of one half of a plant.

Fig 4 shows a schematic sketch of a cross section straight through the long direction of a bladeholder with carriages and a linear asynchronous linear generator.

Fig 5 shows a schematic sketch of details of a carriage and a linear generator.

Fig 6 shows a schematic sketch of guide shafts with inholds at carriage.

Description of form of execution

The wind power plant is built up of one or more framework towers (1), tube towers or masts who are combined with each other through connecting frameworks (2), tubes or girders, so that they form a frame construction (4), which rotary rests on a bed, for example on wheeled carriages (5) which moves on one or more circular tracks of rail (6) or other, for wheels suitable beddings, to adjust the plant in a straight angle against the wind, at which the framework is also built up by one, two or more inclined and consistencing and also supporting framework towers or tube towers with the base resting on wheeled carriages (7) on the back sections of the tracks and combined with those in a line standing towers with horizontal combining trussed frames (8) or girders, at which the upper parts of the inclined towers are combined with vertical frameworks (9) arranged between the lower and upper combining frameworks (2). The frame construction is arranged to automatically, with the help of the wind power, place itself towards the direction of the wind by being placed symmetrically behind the ratable bedding's centre point (10).

The windabsorbing blades (11) are essentially parallelly arranged by a carriage (12) each, which runs around a closed track ( 13, 14) in a vertical plane in front of the frame construction, at which each blade is attached at an appropriate distance on each side of the carriage's center by outher bladeholders (15, 16) in such a distance towards the wing tip that the demand of enough steadiness for the windabsorbing blades is fulfild. When necessary even the blades can be attached at an inner bladeholder. The outher bladeholders are turnable attached by bearings at at least one trailing wheel ( 17, 18) or bearings for linear movement ( 19) or similar bearing elements on each side of and on appropriate distance from the centre of the track, at which the trailing wheels or the bearings are arranged to roll on the closed track, for example rail (20, 21) attached on the frame construction, at which the trailing wheels or the bearings are adjusted to the rail, so that the carrier and the blade can not move towards the interior of or towards out of the rotary basic construction. The outher bladeholders are attached at at least one combining girder or holdarm (22, 23) on which is attached an powertransmission line (24) which consist of elongated at each other linked girders (25, 26) who runs around the closed track.

The closed track can entirely or partially form the shape of a circle, an ellipse or a similar geometrical representation and partially rectilinear as well. If the blades are allowed to rotate freely around their holders, in the entrance of the end sectors, the inner, towards curve center located sections of the blades, they will move forward because of the abrupt braking of these passages, and the outher sections on the periphery will retain the same movement insted of accelerating in the cornering. If this cornering do not occur, the blades run the risk to break. By forming the track elliptic at the outher sectors, this cornering can be made more softly by, in more than one combining holdarms (22, 23), these are arranged turnably connected with the outher bladeholders (15, 16) in such a way that they, at straight track, form a rectangle and at curved track is allowed to have the form of parallelogram. To regulate the deflection of the blades every carriage is combined with the beforelying by means of two guide shafts (27, 28) each placed on each side of the center of the carriages, at which the rod ends are put together at suitable distances from the center of each carriage, at which every rod is arranged with infitted springings in one or both ends, at which a certain change of length is permitted, at which the blades are hold essentially at right angles to the track at straight tracks and when entering a curving of the track, the inner tips of the blades placed closest to the center of the curved track are permitted to retard in a suitable and less rapid prolongation than if the blades had been fixed anchored right-angled toward the running direction, at which the blades outher wingtips in a similar fashion are permitted a softer acceleration at the passage to the curved section of the track. The width of the track is thereby adapted to the change of form and is made narrow in corresponding proportions in these sections of the track.

The trailing wheels and the linear bearings can be equipped with a spring system (30) for safer, smoother and less clash running. When necessary smaller carriages can be installed between the carriages of the wings, at which these also are turnable connected with the power transmission line (24).

The outlet of energy is made trough one or more through the entire or parts of the track comprising lineare electrical generators (32, 33) at which the linear generators are functioning as rotating electrical generators according to the alternating current or direct current principles with the rotor and stator planned to be cutted up and straightened, at which stators (32) and rotors (33), attached to the frame construction respective the carriages and the power transmission line, are spread parallel to each other through the track of the turbine blades.

In this description a linear generator is described. As a principal it is constructed as an asynchronous generator with so called squirrel-cage winding or can rotor. This means that the rotor consist of an oblong, flat metal track (34) which is attached to the powertransmission line and the wing fixing girders and stretch lengthways threw sectioning with roundings of the ends fitted in each other which makes this flat track bendebal through the entire track.

Each generator can gradually be switched on and off according to electrotechnical methods and devices, or also mechanically during running action, at which the stator is made displaceable from its operational position at the track by, for example resting on rolls (35), arranged between U-girders (36), at which one U-girder is seated below the stator and another in the framework, at which at the displacement a gap or empty space gradually arises between the stator and rotor in such a way that eventually no electrical power can be

80 generated. When reconnecting the generator the stator is gradually brought back to the working position creating a very small airgap between the stator and the rotor, at which one or more springs (37) or other known devices are arranged to push the stator in the direction of the rotor, at which one or more wheels (38) arranged at the stator or its holders can be arranged to, isolated against electricity roll towards the rotor in such a way that a certain

85 desired small gap always exists between the stator and the rotor.

The generator components are protected against wind, rain- and snowfall by suitable protection (39).

90 The angular adjustment of the turbine blades towards the wind direction, the pitch angle regulation, demand an electronic correcting unit (40) for each blade, at which the correcting unite is attached to the carriage through an adjusting rod (41) and it should be done in contact with the rear of the wing, at which the carriage will have its power through an electric power distribution and suitable connector and level indicator from detecting organs

95 which detect relevant operational parameters.

Energy of the gusts of short duration will immediately be taken charge of by this regulation. The regulators are protected against wind, rain and snowfall by suitable encapsulation.

100 For raising and lowering the frame construction can be arranged turnable attached by bearings on the turnable bedding and at least to two or more ground fasteners (42) all of which are placed in a straight line. In the bearings easely mountable and dismountable axle journals are thereby included.

105 The installation of a completed wind power plant is made with the frame construction lying on the ground at which one end of at least one winch rope is attached to the frame construction and the other to one or more winches firmly established on the ground in concrete beds or the like, of which the completely put together plant is raised or lowered with the winches.

110

The turnable bedding can, above all dealing with large plants with a large moment of inertia, be arranged with motor-driven removal in optional direction through guide by a regulator, at which a faster adjustment of the plant against the wind direction will be achived.

115 Since the blade profile essentially has the same shape in its entire length the consumption of material for the blade manufacturing will be relatively low and the manufacturing simple.

The invention is of course not limited to the form of execution described above, but can within the limits of the patent claims be modified in alternative forms of execution. For 120 example the noise can be muffled by choosing silent running linear bearings, choosing silencing wheel-material and protective housing.

Claims

PATENT CLAIMS

1. A wind power plant with many essentially parallel arranged windabsorbing blades ( 11) arranged by carriages ( 12), which, interlinked with each other runs around a closed track

( 13, 14), at which the plant is built up of one or more framework towers (1), tube towers or masts which are combined with each other through connecting frameworks (2), tubes or girders, so that they together form a frame construction (4), which construction rotary rest on a bed to adjust the plant in a right angle against the wind c ha ra c te ri z e d t h e re b y that the energy outlet is done through one or more through the whole or parts of the track comprising linear electrical generators, at which the linear generators are functioning as rotating electrical generators according to the alternating current or direct current principles with the rotor and stator thought as cutted up and straightened, at which stators (32) and rotors (33, 34), attached to the frame construction respectively the carriages and a connecting power transmission line (24, 25, 26), are spread parallelly to each other along the track of the turbine blades, at which either the rotors or the stators are permitted to have longer extension in relation to the others, at which the rotors will serve as rotors for more than one stator, that the windabsorbing blades ( 11) are arranged attached to the carriages by outher bladeholders (15, 16) on each side of the center line of the carriages and the track, at which on each bladeholder is attached at least one trailing wheel (17, 18) or bearing for linear movement ( 19), or similar bearing element, so arranged that the carriages are permitted, without possibility to lateral deviation, slide along the closed track (13, 14) attached to the frame construction (4).

2. Wind power plant according to claim 1, c h a r a c t e r i z e d t h e r e b y that two or more linear generators are permitted to be connected in series or parallel when not moving or during running action, at which one, two or more of the generators simultaneously can be cut on, or cut off, according to some of these combinations, permitting generating electric power.

3. Wind power plant according to claim 1 and 2, c h a ra c te ri z e d th e re b y that the linear generator is constructed as an asynchronous alternating current generator with cage rotor, at which the rotor essentially is arranged as oblong, flat metal tracks (34) with one of the flat faces running close to the stator (32), or the stators, in the case of more than one generator, at which is connected to the carriages and stretch lengthways through the whole track, at which the rotor through sectioning with roundings of the ends is bendebal, at which the stator (32) is connected along the frame construction.

4 Wind power plant according to claim 1 - 3 c h a ra c t e r i z e d th e r e b y that each generator, stationary or during running action, can be connected or disconnected through a mechanical displacing of the stator from its operational position along the track, at which a gap gradually arise between the stator and rotor in such a way that eventually no electrical power can be generated, at which in connecting the generator, the stator is gradually brought back to the working position with a very small air gap between the stator and the rotor.

5. Wind power plant according to claim 1-4, characterized thereby that one, two or more wheels (38) or the like attached to the stator or its holders are arranged to, isolated against electricity roll or slide towards the rotor or its holders in such a way that a certain requested small gap always exist between the stator and the rotor, at which a spring (37) or another known arrangement press the stator in the direction of the rotor.

6. Wind power plant according to claim 1, characterized thereby that the windabsorbing blades (11) are arranged turnable attached to the carriages by outher bladeholders (15, 16) on each side of the centre line of the carriages and the track, at which the blades are permitted to turn in the swept, vertical plane, and at which the angular adjustment of the blades with respect to wind speed is permitted regulation.

7. Wind power plant according to claim 1 and 6, characterized thereby that a correcting unit (40) for the pitch angle regulation is arranged between the carriage and the blade.

8. Wind power plant according to claim 1 and 7, characterized thereby that the outher bladeholders ( 15, 16) are turnable connected to at least one connecting holdarm (22, 23).

9. Wind power plant according to claim 1 and 6, characterized thereby that guide shafts (27, 28) are connected between the carriages on each side of the center of the carriages, at which in the guide shafts are infitted one or more springings, which makes change of length of the guide shafts possible, at which the carriages and the wind absorbing blades are permitted requested turning.

10. Wind power plant according to claim 1, characterized thereby that smaller carriages (31) are arranged between the carriages of the wind absorbing blades permitting a better adjustment of the powertransmission line (24) and the linear generators to the shape of the closed track.

11. Wind power plant according to any of earlier claims, characterized thereby that the plant is arranged to rest on one or more sea- or lakebased pontoons, rafts, hull of the boat, or the like hulls attached at each other by means of cables, bracings, cross bars or frameworks, which form a floating platform, which is anchoraged at the bottom of a sea or the lake.

12. Wind power plant according to claim 1, characterized thereby that the frame construction for raising and lowering is in a straight line turnable attached by bearings on the turnable bedding and to ground fasteners (42) at which in the bearings easely mountable and dismountable axle journals thereby are included, at which the frame construction, for example overhaul by means of one or more winches, can be raised respective lowered.

90 13. Wind power plant according to claim 1, characterized thereby that the closed track (13, 14) towards the flank is arranged enlarged upwards and downwards, at which the track at the flanks is arranged essentially elliptic with the major axis (43) directed towards the flank.

95 14. Wind power plant according to any of earlier claims, characterized thereby that the plant is permitted enlargement laterally, at which the enlargement will be made in the centre part of the frame construction and the track, at which the existing sections are transfered towards in the same extension.