Source: https://patents.google.com/patent/US7296971B2/en
Timestamp: 2019-12-11 00:08:30
Document Index: 158236312

Matched Legal Cases: ['art 8', 'art 8', 'art 9', 'art 9', 'art 21', 'art 21', 'arts 9', 'art 9', 'art 9']

US7296971B2 - Wind power station - Google Patents
Wind power station Download PDF
US7296971B2
US7296971B2 US10/554,279 US55427905A US7296971B2 US 7296971 B2 US7296971 B2 US 7296971B2 US 55427905 A US55427905 A US 55427905A US 7296971 B2 US7296971 B2 US 7296971B2
US10/554,279
US20060269396A1 (en
2003-04-28 Priority to NO20031888A priority Critical patent/NO324756B1/en
2003-04-28 Priority to NO20031888 priority
2004-04-28 Application filed by SWAY AS filed Critical SWAY AS
2004-04-28 Priority to PCT/NO2004/000119 priority patent/WO2004097217A1/en
2005-11-24 Assigned to SWAY AS reassignment SWAY AS ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BORGEN, MR. EYSTEIN
2006-11-30 Publication of US20060269396A1 publication Critical patent/US20060269396A1/en
2007-11-20 Publication of US7296971B2 publication Critical patent/US7296971B2/en
An arrangement for a floating wind power station (1) tower (3) which floats in a substantially vertical position in that the effective centre of gravity of the tower (3) is below the centre of buoyancy of the tower (3), and wherein a machine house (13) including rotor (15) is non-rotatably connected to the tower (3) and the tower (3) is articulatedly connected to the seabed (5), wherein the tower (3) is rotatable about a tower axis of rotation (29) in that lower part (21) of the tower (3) is provided with a swivel joint (27 a or 27 b) that is designed to essentially absorb vertical tensile forces.
The present invention relates to arrangements for a floating wind power station wherein the machine house is non-rotationally connected to the tower of the wind power station and the tower is rotatable about a tower rotational axis. Furthermore the tower is provided at least one tension rod and at least one outrigger where the at least one tension rod extends from an upper part of the tower, via the at least one outrigger, to a lower part of the tower.
The effective centre of gravity of the tower is below its centre of buoyancy in that the tower is anchored to the seabed, directly or via tension legs. The effective centre of gravity of the wind power station at any given time is determined by the total weight and shape of the power station and the effect of weight, shape and any tensile forces from the anchoring system. This means that the position of the effective centre of gravity can be maintained by various combinations of ballast and tension from the anchoring system, i.e., that a reduced ballast can be offset by increased tensile force from the anchoring system.
The invention also relates to an almost vertical swivel joint/rotary joint that connects the tower to a torsion-proof foundation, where the direction of the axis of rotation can deviate slightly from the perpendicular through the axis that passes through a rotor. A rotor housing is connected in a torsion-proof manner to an upper part of the tower. The axial direction of the swivel joint ensures that the wind forces against the rotor apply a torque to the tower which maintains the rotor in a favourable position relative to the wind direction at all times. As a result of this effect, the design of the tower can be optimised, in that the maximum bending stress occurs in a plane that coincides with the centre axis through the tower and the centre axis through the rotor.
Because the tower leans when subjected to the wind forces, it will be desirable to set the rotor at an angle other than 90 degrees to the tower to ensure that the axis of the rotor remains approximately horizontal. This means that the rotor blades could strike against the tower if the rotor is positioned on the windward side of the tower, It will therefore be desirable to be able to position the rotor on the leeward side of the tower. However, this causes the disadvantage that the rotor blades pass through the shadow area behind the tower each time a blade passes the 6 o'clock position, which results in a sudden change of the wind pressure against the blades and thus substantial fatigue stress.
The invention is based on moving one of the floating wind power station's arrangements for maintaining direction relative to wind, as described above, from an upper part of the wind power station tower to its lower part. A tower's swivel joint with an essentially vertical centre axis, and essentially coincident with the perpendicular to a centre axis through a wind power station rotor, is mounted on the lower part of the tower. A machine house containing wind power station rotor, gear housing and generator, or transfer transmission to the gear housing and the generator located lower down on the tower, is non-rotationally connected to the wind power station tower.
a) a centre axis through the rotor of a wind power station is called the rotor axis of rotation; and
b) a centre axis through the swivel joint of the wind power station is called the tower axis of rotation.
a) The rotor axis of rotation is at right angle to the tower axis of rotation:
b) The rotor axis of rotation is not at right angles to the tower axis of rotation:
The tower is also affected by the wind forces against the rotor blades, as the total wind force against the blades will apply a torque to the tower about the tower axis of rotation if the common point of application of the forces is not coincident with the tower axis of rotation. If said point of application is in front of the tower axis of rotation when seen in the wind direction, the wind forces will try to turn the tower so that the rotor is positioned on the opposite side, that is, on the leeward side of the tower.
Consequently, the direction of the tower axis of rotation is used to control how the tower and its rotor are to be oriented relative to the wind. Thus, the fact that the tower turns constantly with the wind means that a major advantage is obtained as regards material consumption, weight and the cost of building a floating wind power station tower.
If the tower axis of rotation intersects the rotor axis of rotation behind the rotor, that is to say, behind the centre of the point of application of the wind forces on the rotor, when seen in the direction of the rotor, and where the machine house and the tower are behind the rotor, the tower will be kept turned with the wind, so that the rotor is on the leeward side of the tower.
It is desirable to keep the rotor axis of rotation essentially horizontal during is operation. Because of the wind forces against the tower, the tower will lean in the wind direction. It is also desirable to maintain a certain distance between the tower and the outer ends of the rotor blades to prevent the blades from striking against the tower in strong wind. One consequence of the two said factors is that it is advantageous to keep the rotor on the leeward side of the tower. The tower axis of rotation is thus advantageously positioned so that the tower axis of rotation intersects the rotor axis of rotation behind the rotor, when seen in the direction of the rotor with the machine house and tower behind the rotor.
The swivel joint could be mounted coincident with the centre axis of the tower. The wind power station will then take up a position with the rotor on its leeward side, in the same way as a weathercock. Because of the tilt of the tower caused by the wind forces, a tilt which will typically be about 5-20 degrees static, and the desire to maintain the rotor axial direction essentially horizontal during operation, the rotor will typically be mounted at a static angle of 90 degrees+5-20 degrees=95-110 degrees between the rotor axis of rotation and the tower axis of rotation.
As the rotor axis of rotation is not at right angles to the tower axis of rotation, the torque that is transferred from the rotor through the generator will apply a torque to the tower around the tower axis of rotation. This is unfavourable as it means that the rotor has a tendency to be turned away from the wind direction. Because the swivel joint essentially does not absorb bending moment, the tower axis of rotation can be set at right angles to the rotor axis of rotation, that is to say, “askew” relative to the centre axis of the tower and at the same number of degrees as the 5-20 degrees mentioned above. Thus, the tower will no longer have a tendency to turn the rotor axis away from the wind direction.
The wind power station cables for the transmission of electric power run from the generator through the tower and down to the seabed. To minimise the twisting of the cable when the wind power station is turned with the wind through one or more revolutions in the same direction, it is an advantage that the cable should run along the centre through the tower's swivel device and universal joint at the bottom of the tower. The universal joint is therefore advantageously provided with an open centre according to prior art per se.
FIG. 2 a is a side view, on the same scale as FIG. 1, of a floating power station, where a tower axis of rotation is at right angles to a rotor axis of rotation and where the tower is stabilised by means of stays and provided with aerodynamic covers;
FIG. 2 b shows on a larger scale a cross-section taken along the line II-II through the tower in FIG. 2 a;
FIG. 2 c is a side view, on the same scale as FIG. 1, of a floating wind power station, where the tower axis of rotation is at an angle to the wind direction;
FIG. 4 shows on the same scale as FIG. 3 a longitudinal section through an alternative connection between a tower having a straight swivel joint, a freely bendable universal joint and a tensioned anchor leg.
Reference is first made to FIG. 1 where the reference numeral 1 a indicates a floating wind power station wherein a tower 2 is non-rotationally anchored to the seabed 5 by means of a tensioned anchor leg 7 and an anchor 8, and wherein an upper part 8 of the tower 2 projects above the surface of the sea 11. A machine house 12 is pivotally connected to the upper part 8 of the tower 2. A rotor 14 has a rotor axis of rotation 16 at right angles to the centre axis of the tower 2. An arrow 19 marks the direction of the wind towards the wind power station.
Reference is next made to FIGS. 2 a-3, wherein the reference numeral 1 b indicates a floating wind power station according to the invention wherein a tower 3 is anchored to the seabed 5 by means of the tensioned anchor leg 7 and the anchor 8, and wherein an upper part 9 of the tower 3 projects above the surface of the sea 11. A machine house 13 is non-rotationally connected to the upper part 9 of the tower 3. A rotor 15 has an axis of rotation 17 at right angles to the centre axis of the tower 3. The arrow 19 indicates the wind direction towards the wind power station.
The articulation 23 comprises a swivel joint 27 a and a universal joint 25. The swivel joint 27 a is attached to the lower part 21 of the tower 3 at an angle so that a tower axis of rotation 29 intersects the rotor axis of rotation 17. The swivel joint 27 a is pivotally fastened to a bearing house 31 by means of a ball bearing 33 and axial locking means (not shown) on the swivel joint 27 a and in the bearing housing 33. The bearing housing 31 is fixed to the upper section 35 of a universal joint 25. A seal 34 is located below the bearing 33 and seals an annular space 32 between the swivel joint 27 a and the bearing housing 31.
A casing 37 is fastened to and seals tightly around the fastening point of the swivel joint 27 a to the lower part 21 of the tower 3 and essentially surrounds the bearing housing 31. A seal 39 is placed below the bearing 33 and closes an annular space 40 between the casing 37 and the bearing housing 31. The annular spaces 32 and 40 communicate via the bearing 33 and are filled with a bearing lubricant.
In an alternative embodiment shown in FIG. 4 the centre axis of a swivel joint 27 b, i.e., the tower axis of rotation 29 is coincident with the centre axis of the tower 3.
The swivel joint 27 a, 27 b has an open central passage 51. The universal joint 25 and the tension leg 7 also have open central passages 53 and 55 for running cables to the wind power station (not shown).
According to FIG. 2 a, the tower 3 is provided with a tension rod 61 connected to the upper and lower parts 9, 21 of the tower 3 and held stretched out by two outriggers 63 that are fastened to the tower 3, and which in one embodiment of the invention project out from the windward side of the tower ±30 degrees relative to a plane coincident with the wind direction and/or wave direction.
The upper part 9 of the tower 3 is shaped aerodynamically, i.e., with a non-circular cross-section. The upper part 9 of the tower may be provided with aerodynamic screens 71 preferably partially rotatable about the tower 3, and may be designed to reduce the turbulence of the wind (19) on the leeward side of the tower (3).
The universal joint 25 ensures that the swivel joint 27 a or 27 b, does not absorb bending moment.
The swivel joint 27 a or 27 b and its support 31, 33 ensure that the tower 3 can turn freely about the tower axis of rotation 29 and take up a direction that corresponds to the wind direction.
By determining the direction of the tower axis of rotation 29 relative to the rotor axis of rotation 17 and the resultant point of application of the wind forces on the rotor 15, it is possible to determine how the tower will be positioned relative to the wind direction.
Setting the tower axis of rotation 29 to intersect the rotor axis of rotation 17 in front of the rotor 15, when seen with the rotor in front of the machine house 13 (as shown in FIG. 2 c), will result in the wind turning the tower 3 to stand with the rotor on the windward side of the tower. This may be desirable if the intention is to use an upwind rotor 15, which is most technically and commercially available today.
Since the casing 37 seals around the junction between the swivel joint 27 a or 27 b and the tower 3, fewer demands may be made as regards the quality of the seals 34 and 39 if a bearing lubricant that is lighter than water is used. Because of the central opening 53 in the universal joint 25, the water pressure on the seals 34, 39 is equal, and the water pressure alone is capable of holding the bearing lubricant in place in the annular spaces 33, 40 defined by the casing 37 and the swivel joint 27 a or 27 b.
Since the power transmission cables (not shown) only tolerate a limited degree of twisting, the motors 43 are used, after the tower has rotated a certain number of times with the wind, to cause the tower 3 to rotate back to a position of neutrality for the cables. The motors 43 can also be used to dampen or stop the rotational motion of the tower.
1. An arrangement for a tower of a floating wind power station comprising a machine house including a rotor, the machine house being non-rotationally connected to the tower and the tower being rotatable about a tower rotational provided with at least one tension rod and at least one outrigger, the at least one tension rod extending from an upper part of the tower, via the at least one outrigger, to a lower part of the tower.
2. An arrangement according to claim 1, wherein the tower axis of rotation is coincident with the centre axis of the tower.
3. An arrangement according to claim 1, wherein the tower axis of rotation is at an angle to the centre axis of the tower.
4. An arrangement according to claim 1, wherein an upper part of the tower is aerodynamically designed, i.e., with a non-circular cross-section, or provided with aerodynamic screens preferably partially rotatable about the tower.
5. An arrangement according to claim 1 wherein the tower is articulately connected to the seabed or to a tensioned anchor leg.
6. An arrangement according to claim 1 wherein the effective centre of gravity of the tower is below the centre of buoyancy of the tower.
7. An arrangement according to claim 1 wherein the lower part of the tower is provided with a swivel joint.
8. An arrangement according to claim 7, wherein the swivel joint is provided with means for forced rotation of the tower.
9. An arrangement according to claim 7, wherein a bearing housing for the swivel joint is connected to a tensioned anchor leg via a freely bendable joint.
wherein the tower its lower part, the swivel joint, the joint and the tension leg are provided with open central passages for the routing of cables.
11. An arrangement according to claim 9, wherein the bearing housing is surrounded by a casing which, together with the swivel joint and essentially downward directed seals, forms communicating annular spaces.
12. An arrangement according to claim 11, wherein the communicating annular spaces are designed to hold a lubricant enclosed by means of water pressure directed towards the essentially downward directed seals of the casing.
US10/554,279 2003-04-28 2004-04-28 Wind power station Active 2024-05-02 US7296971B2 (en)
NO20031888A NO324756B1 (en) 2003-04-28 2003-04-28 Floating wind power plants with steadying
NO20031888 2003-04-28
PCT/NO2004/000119 WO2004097217A1 (en) 2003-04-28 2004-04-28 Wind power station
US20060269396A1 US20060269396A1 (en) 2006-11-30
US7296971B2 true US7296971B2 (en) 2007-11-20
ID=19914705
US10/554,279 Active 2024-05-02 US7296971B2 (en) 2003-04-28 2004-04-28 Wind power station
US (1) US7296971B2 (en)
EP (1) EP1618301B1 (en)
JP (1) JP4651614B2 (en)
AT (1) AT388326T (en)
AU (1) AU2004235020B2 (en)
CA (1) CA2523274C (en)
CY (1) CY1108068T1 (en)
DE (1) DE602004012244T2 (en)
DK (1) DK1618301T3 (en)
ES (1) ES2303635T3 (en)
NO (1) NO324756B1 (en)
PL (1) PL1618301T3 (en)
PT (1) PT1618301E (en)
WO (1) WO2004097217A1 (en)
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2003-04-28 NO NO20031888A patent/NO324756B1/en unknown
2004-04-28 JP JP2006507896A patent/JP4651614B2/en not_active Expired - Fee Related
2004-04-28 DK DK04730134T patent/DK1618301T3/en active
2004-04-28 AT AT04730134T patent/AT388326T/en not_active IP Right Cessation
2004-04-28 ES ES04730134T patent/ES2303635T3/en active Active
2004-04-28 EP EP20040730134 patent/EP1618301B1/en active Active
2004-04-28 DE DE200460012244 patent/DE602004012244T2/en active Active
2004-04-28 PT PT04730134T patent/PT1618301E/en unknown
2004-04-28 WO PCT/NO2004/000119 patent/WO2004097217A1/en active Application Filing
2004-04-28 US US10/554,279 patent/US7296971B2/en active Active
2004-04-28 CA CA 2523274 patent/CA2523274C/en active Active
2004-04-28 AU AU2004235020A patent/AU2004235020B2/en not_active Ceased
2004-04-28 PL PL04730134T patent/PL1618301T3/en unknown
2008-06-04 CY CY081100589T patent/CY1108068T1/en unknown
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JP2006524778A (en) 2006-11-02
ES2303635T3 (en) 2008-08-16
NO20031888L (en) 2004-10-29
JP4651614B2 (en) 2011-03-16
CY1108068T1 (en) 2014-02-12
PL1618301T3 (en) 2008-08-29
WO2004097217A1 (en) 2004-11-11
DE602004012244D1 (en) 2008-04-17
AT388326T (en) 2008-03-15
DE602004012244T2 (en) 2009-03-19
CA2523274C (en) 2012-08-28
US20060269396A1 (en) 2006-11-30
EP1618301A1 (en) 2006-01-25
PT1618301E (en) 2008-06-17
KR20060008893A (en) 2006-01-27
NO324756B1 (en) 2007-12-10
NO20031888D0 (en) 2003-04-28
EP1618301B1 (en) 2008-03-05
AU2004235020A1 (en) 2004-11-11
AU2004235020B2 (en) 2008-04-03
CA2523274A1 (en) 2004-11-11
DK1618301T3 (en) 2008-07-07
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2005-11-24 AS Assignment
Owner name: SWAY AS, NORWAY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BORGEN, MR. EYSTEIN;REEL/FRAME:016812/0917