WO2014015998A1

WO2014015998A1 - Floatable platform for wind power turbines

Info

Publication number: WO2014015998A1
Application number: PCT/EP2013/054570
Authority: WO
Inventors: Michael SCHLÖGEL; Philipp MENGELKAMP; Claus Colling
Original assignee: Schloegel Michael; Mengelkamp Philipp; Claus Colling
Priority date: 2012-07-26
Filing date: 2013-03-07
Publication date: 2014-01-30
Also published as: DE102012213213B4; DE102012213213A1

Abstract

The present invention relates to a floatable platform for wind power turbines, comprising at least two elongate float bodies which are floating substantially vertically; at least one first connecting member; and at least one second connecting member having a concentrically disposed anchoring. The at least two float bodies are respectively pivotally connected to each other through the first connecting member. The at least two float bodies are respectively pivotally connected to each other through the second connecting member. The first connecting member and the second member are substantially parallel to each other, such that a parallel swinging of the float bodies relative to each other is possible in a plane that is defined by the vertical longitudinal axis of the respectively connected two float bodies.

Description

Floatable platform for wind power turbines

Cross-Reference to related Applications

[0001] The present application claims priority of the German Patent Application DE 10 2012 213 213.9 filed on July 26^th, 2012.

Background of the Invention

[0002] The present invention relates to the field of wind power plants. Particularly, the present invention relates to a floatable platform for wind power turbines, for example vertical axis wind turbines (VAWTs) or horizontal axis wind turbines (HAWTs), comprising two coupled floatable bodies.

Background Art

[0003] During advancement in wind power plant technology, particularly for generating electric power out of wind energy, more and more construction accounts are made for building so-called wind farms comprising a plurality of wind power plants. Thus, the search for suited locations for such wind farms becomes harder. For exploration of further areas for wind farms, difficultly exploitable or accessible regions, like water areas (oceans, lakes, rivers, etc.), become more important. Wind power plants on water areas offer special benefits, since here usually even wind conditions prevail which promises a constantly high power output.

[0004] However, the safe construction of wind power plants on water areas is difficult and expensive. Further, conventional wind power plants that are built on water areas are stiffly and inflexibly set on their fixed sockets such that a subsequent change of location is not possible. Therefore, efforts are made for developing floatable wind power plants.

[0005] DE 103 37 997 B4 discloses an anchoring device for an off-shore wind power plant having a foundation, provided with a support for the wind power plant, which floats in the water and which is attached to the sea bed via a number of anchoring lines. The anchoring device is characterized in that the foundation is provided by an elongate float body along which a helical blade is disposed for vertically stabilizing the anchoring device.

[0006] However, such single float bodies are very susceptible for waves and may be tilted by them or may be turned over or pushed under water due to the oscillation frequency of the float body. Namely, a single float body behaves like a vertically put up spring pendulum with it's eigenfrequency, wherein the buoyancy of the float body substitutes the vertical spring reset force of the spring pendulum. If the frequency or multiples of the frequency of the water waves is sufficiently close to this eigenfrequency an unwanted feedback may occur. This effect is known from the field of architecture.

Summary of the Invention

[0007] To solve these problems of the state of the art, the present invention provides a floatable platform for wind power turbines according to claim 1, comprising at least two elongate float bodies which are floating substantially vertical and which comprise at least one first connecting member and at least one second connecting member having a concentrically disposed anchoring. The at least two float bodies are respectively pivotally connected to each other through the first connecting member and the second member, wherein the first connecting member and the second member are substantially parallel to each other. Thereby, the pivot plane passes through both vertical longitudinal axes of the float bodies. The second connecting member is preferably the upper connecting member and thus closer to the water surface. Alternatively, the second connecting member may also be disposed as the bottom connecting member.

[0008] The floatable platform according to the invention may further comprise at least one oscillation damper. At least one of the connecting members may me coupled to a generator inside of a float body which is suitable for generating electric power out of the oscillation of the float bodies induced by waves. The at least two float bodies may be hollow, may have a substantially circular cross sectional area, and may respectively have a substantially cylindrical upper portion with a first diameter and a substantially cylindrical bottom portion with a second diameter being larger then the first diameter. Further, the at least two float bodies may respectively have a substantially conical middle portion.

[0009] The upper portion of the floatable platform according to the invention may be formed as a truss type girder to reduce the resistance of the at least two float bodies to incoming waves or water streams.

[00010] The at least two float bodies may be manufactured out of metal, like a bended metal sheet, or through a concrete cast method using concrete or a concrete mixture. The at least two float bodies may respectively be sectioned into at least three segments by plates, wherein at least one of the bottom segments comprises ballast. In the floatable platform according to the invention, at least one segment may be formed as a ballast tank for adjusting the draft of the float body. In at least one of the segments of the at least two float bodies, a module or a plurality of modules may be respectively disposed, wherein the module or the plurality of modules comprises at least one device of the group consisting of a system controlling device, a water pump, a power converter, a power rectifier, a power transformer, a power storing device, a hydrogen production unit and a hydrogen storage device.

[00011] Preferably, the floatable platform further comprises at least two wind turbines respectively disposed on the top part of one of the at least two float bodies. Preferably, these wind turbines have the same design. The anchoring of the floatable platform according to the invention may comprise at least one pair of inductors for transmitting electric power inductively from the floatable platform to a power line. Optionally, the anchoring may comprise an upper anchoring member and a lower anchoring member respectively having a substantially circular protrusion engaging with each other. The protrusions may respectively have a substantially L-shaped cross section for allowing the first anchoring member and the second anchoring member to be rotatable to each other by 360°. The upper and the lower anchoring member may further comprise internal holes guiding a water pressure that applies at vertical movements of the anchoring to friction surfaces of the anchoring members and their circular protrusions, respectively, the friction surfaces being stressed by compressive forces or tensile forces, such that a water film reduces the friction at the stressed locations.

[00012] The wind turbines are preferably vertical rotor wind turbines respectively vertical axis wind turbines (VAWTs); however, horizontal axis wind turbines may also be used as wind turbines and the invention is not limited to VAWTs. A rotation direction of at least one of the vertical axis wind turbines may be opposite to a rotation direction of another vertical axis wind turbine on another float body of the floatable platform.

[00013] The above described floatable platform may be further characterized in that the torques being generated by the wind turbines are transmitted to the first connecting member via the float bodies. In this case, the torques generated by the wind turbines and transmitted to the first connecting member may add up to zero.

[00014] Alternatively, the rotation speeds of the vertical axis wind turbines may be varied by selectively decelerating single vertical axis wind turbines so as to generate a torque of the platform by different rotation speeds of the vertical axis wind turbines. One possible method for selectively decelerating the wind turbines is described in EP 20 85 610, i.e., the use of aerodynamic breaks on the VAWTs.

[00015] Another aspect of the present invention is a floatable platform system comprising at least two of the above described floatable platforms. Further, wind direction sensors arranged at the floatable platforms and transmitting wind direction data to the system controller of the floatable platforms may be arranged, wherein the system controllers are adapted for communicating with each other to automatically calculate an alignment of each floatable platform in order to improve the total power output of the entire system through selectively decelerating either one of the vertical axis wind turbines.

Brief Description of the Drawings

[00016] The drawings described in the following are schematic drawings. Therein, in the drawings as well as in the description equal or similar parts are denoted with the same reference signs. [00017] Fig. 1 is a schematic view of the present invention using vertical axis wind turbines.

[00018] Fig. 2 is a schematic view of the present invention with water surface and anchoring.

[00019] Fig. 3 is a schematic view of the present invention illustrating a first connecting member.

[00020] Fig. 4 is a schematic view of the present invention illustrating a second connecting member with anchoring.

[00021] Fig. 5 is a schematic view of the present invention illustrating different rotation orientation with anchoring.

[00022] Fig. 6 is a schematic view of the present invention illustrating the anchoring with fixing at the ground, a cross section view of the anchoring, and a schematic view of the inductive power transmission.

[00023] Fig. 7 is a schematic view of the present invention illustrating the holes in the anchoring.

[00024] Fig. 8 is a schematic view of the present invention illustrating a float body with segmentation.

Detailed Description [00025] Fig. 1 is a schematic view of the present invention using wind turbines, especially vertical axis wind turbines (VAWT). Although Fig. 1 and 2 show the present invention with VAWTs, the invention may also be carried out when using horizontal axis wind turbines (HAWT). It should be noted that a floatable platform of the present invention is preferably operated with wind turbines of the same design. Fig. 1 shows a floatable platform 1 for wind turbines 6. In this first embodiment, the invention is described with two elongate float bodies 2. The at least two float bodies may be manufactured out of metal, like a bended metal sheet, or through a concrete cast method using concrete or a concrete mixture. However, it is noted that the number of float bodies 2 may exceed two. The two float bodies 2 float in water substantially vertical. The floatable platform 1 further comprises at least one first connecting member 3 and one second connecting member 4, comprising a concentrically disposed anchoring 5. If the platform 1 comprises more then two float bodies 2 the number of connecting members 3, 4 needs to be adapted for ensuring a connection between the float bodies allowing a parallel shifting of the elements to each other. Here, the number of first connecting members 3 may be adapted according to the stress for the system depending on the weight of the platform 1, the maximal wind force, and the maximal swell. More first connecting members 3 increase the stability but also the weight and the costs of the platform 1. Preferably, the second connecting member is the upper connecting member and therewith, it is closer to the water surface. Alternatively, the second connecting member may be disposed as the bottom connecting member.

[00026] The at least two float bodies 2 are respectively pivotable connected through the first connecting member 3 and the second connecting member 4, wherein the first and the second connecting member 3, 4 are arranged substantially parallel to each other and with a sufficient distance. This arrangement allows that the float bodies of the platform swing parallel in a layer of the vertical float body axes induced by waves and this swing energy may either be damped, e.g. by board-shaped connecting members 3, 4, or transformed into electric power by generators. The connecting members 3, 4 are respectively coupled with a mechanism inside of the float body 2, which converts the swinging movement into a circular movement to operate a generator.

[00027] The float bodies 2 may further comprise a vibration damper (not shown) arranged in form of a weight comprising a metal, a metal mixture, concrete or another sufficiently dense material. This vibration damper is disposed in the float bodies through resilient elements such that displacement of the float bodies 2 is damped. Preferably, the vibration damper is specially designed to damp frequencies in the range of the eigenfrequency of the float bodies 2 and/or the floatable platform 1. This happens through metered adjustment of weight, position and suspension of the vibration damper.

[00028] Fig. 2 is a schematic view of the present invention with water surface 8 and anchoring 5. The above described second connecting member 4 has a concentric anchoring 5. Preferably, the second connecting member 4 is the upper connecting member and therewith closer to the water surface. This is beneficial for preventing a breakdown torque of the system in case of strong water currents. Alternatively, the second connecting member 4 may also be disposed as the bottom connecting member. The anchoring 5 is for anchoring the platform 1 to the ground 7 of the body of water. This may be done by a mooring respectively by an anchoring system, a killick, anchoring drillings, or other sufficiently steady anchoring techniques, as shown in Fig. 2. Preferably, a anchoring of the platform 1 with one fixing point is used; however, anchoring with two, three, or more fixing points at the ground 7 is also possible. Since the platform has a stable position, a strongly preloaded fixing of the platform is not necessary, thereby reducing stress for the anchoring points and the anchoring. Thus, the anchoring points may be set up easier and more inexpensive, e.g. by smaller killicks or drillings with a shorter depth.

[00029] Fig. 3 is a schematic view of the present invention illustrating a first connecting member. Fig. 4 is a schematic view of the present invention illustrating a second connecting member with anchoring. As shown in Fig. 3, the connecting members 3, 4 maybe designed as simple connecting rods having a linkage on both ends. Alternatively, as shown in Fig. 4, a design as flat connecting boards is also possible for generating a resistance to vertical displacements in water. Another not shown possibility is a design as truss type girder with a preferably small resistance. Additionally, the second connecting member 4 has a concentric anchoring 5, as further shown in Fig. 4.

[00030] Fig. 5 is a schematic view of the present invention illustrating the different rotation orientation of the vertical axis wind turbines. In the embodiment of Fig. 5, the wind turbines 6 are vertical axis wind turbines 6. However, horizontal axis wind turbines (not shown) are also suited to be installed on a platform 1 of the present invention. A rotation direction 9 of at least one of the vertical axis wind turbines 6 may be respectively opposite to a rotation direction 9 of another vertical axis wind turbine 6 on another float body 2 of the floatable platform 1 , as shown in Fig. 5. This offers the advantage that the torques of the wind turbines 6 are cancelling each other and no net torque affects the platform 1.

[00031] Fig. 6 shows that the transmission of electric power to a submarine power cable may occur through a direct cable connection (Fig. 6 top). Alternatively, the anchoring 5 may comprise at least one pair of inductors suitable for inductively transmitting the generated electric power from the floatable platform 1 to a power cable (Fig. 6 middle and bottom). Through the inductive transmission, wearing parts in the anchoring 5 may be omitted and/or protected. Further, the two anchoring members may rotate around each other by 360° which prevents stress through torsion of the power cable, e.g. if the platform rotates by 360°. In the bottom part of Fig. 6, an alternative design with two anchoring members having spherical surfaces is shown. This embodiment also allows rotation by 360° without torsion of a coupled power collection cable.

[00032] Fig. 7 is a detailed view of a portion of the anchoring 5 which may optionally have holes 10. These holes are supplied with water by flat incident funnels opened in direction of the water surface. Through the funnel shape, water is pressed in between the two anchoring members being rotatable to one another by 360° if the anchoring is pushed horizontally through water, e.g. if the whole floatable platform 1 or the second connecting member 4 oscillate vertically. The water inflowing due to the pressure gradient ensures a continuous water bearing at the anchoring member portions that are stressed by the water pressure and the water resistance, respectively.

[00033] The holes 10 with the funnel shaped openings are located on the top side and the bottom side of the anchoring 5. Due to the permanent up-and-down movement of the floatable platform 1 water is pressed into the holes 10 and through the further path of the holes up to the bearing areas in order to work there as a water bearing. The holes may exist in different numbers on the top side and the bottom side, but at least two per top side and bottom side. Optionally, the areas of the anchoring 5 around the holes may be treated or equipped with anti-fouling means, e.g. a suited coating or lamination.

[00034] Fig. 8 is a schematic view of the present invention illustrating a float body with segmentation. The two float bodies 2 of the present invention are hollow and have a substantially circular cross sectional area. Further, the float bodies 2 may respectively comprise a cylindrical upper portion 10 with a first diameter a, a substantially conical middle portion 11, and a substantially cylindrical bottom portion 12 with a second diameter b being larger then the first diameter a. Due to the thinner upper portion 10 the resistance to waves of the water surface 8 is additionally diminished which gives the floatable platform 1 a more stable position in water.

[00035] Additionally, the upper portion 10 may be designed as a truss type girder in the area of the water surface 8 to further reduce a resistance of the two float bodies 2 to incoming waves.

[00036] As shown in Fig. 8, the two float bodies 2 may respectively be sectioned into at least three segments. Preferably, at least one of the bottom segments may comprise ballast. This ballast maybe incorporated in form of ballast stones, sand, silt from the water ground, or concrete. Generally, each material being distinctly denser then water and sufficiently easy to transport or to gather on site is suitable.

[00037] Further, at least one segment maybe formed as a ballast tank for adjusting the draft of the float body 2. The pumps required for that may be provided on e.g. a ship while installing the platform 1 or may be provided in one of the upper segments of the platform 1.

[00038] Inside the segments of the floatable platform 1 of the present invention, modules 13 maybe disposed as shown in Fig. 8. Said modules 13 may comprise a plurality of elements or devices which are necessary for the performance of the platform 1 or the installed wind power plant 6. For example, such devices may be a system controlling device, a water pump, a power converter, a power rectifier, a power transformer, a power storing device, such as an accumulator, a hydrogen production unit or current power to gas (methanol) and a hydrogen storage device. The hydrogen production unit and the hydrogen storage device allow operation of the system without a direct grid connection. Thus, platforms 1 may be conceivably operated as a "gas station" with flexible location for ships or as supply for remote islands or temporary expeditions. Furthermore, operation for generating hydrogen in great quantities is conceivable therewith relieving already installed power grids onshore and offshore and dispensing with the need for power storages for storing excess or fluctuating power from wind or sun power plants.

[00039] The rotational speeds of the vertical rotor wind turbines 6 of the present embodiment may be variable through selective deceleration of single vertical rotor wind turbines 6. The decelerating may be performed by mechanical breaks or flaps provided on the vertical rotor wind turbines 6. Thereby, through different rotational speeds of the vertical rotor wind turbines 6, a torque may be induced to the platform 1. The two mechanisms that allow differential torque induction produce a net torque affecting the platform 1 if the two torques of the vertical rotor wind turbines 6 do not sum up to zero.

[00040] An additional embodiment of the present invention relates to a floatable platform system comprising at least two of the above described floatable platforms 1. Additionally to the above described, wind direction sensors are disposed at the floatable platforms 1. Wind direction data from the sensors are transmitted to the system controllers of the floatable platforms 1 , wherein the system controllers may respectively communicate with each other and, together with the data from the wind direction sensors, may automatically compute an alignment that is optimized regarding the power gain of each single floatable platform 1. This may be performed by a central system or by a computing network of the single system controllers.

[00041] The above described optimized alignment allows an improved power gain of each single wind turbine due to improved wind conditions since the wake of other wind turbines can be minimized. The computed optimized alignment of the platforms 1 may be automatically implemented through the above described selective deceleration of the vertical rotor wind turbines 6. Additionally, such a system has the advantage to supply the highest possible power gain at any time without the need for persons to do adjustments or computation. Such an intelligent wind farm may work completely independent and needs human assistance only for maintenance or repair.

[00042] Above embodiments describe a platform 1 of two float bodies 2. However, platforms 1 of three or more float bodies 2 are also possible. However, the number of connecting members 3, 4 needs to be correspondingly adjusted to a circular or rectangular connection of the float bodies 2. Due to the increased number of float bodies, more complex hinges, like ball joints, become necessary for connection with the connecting members.

[00043] The inventive floatable wind power system may be applied in cases where realisation of a post basis for conventional wind power plants is not possible due to the water depth (e.g. too deep), the nature of the ground (e.g. slit), or due to financial reasons.

Further Embodiments

[00044] In another embodiment of the present invention, the at least two float bodies may be fabricated out of plastic, multi-layer structured workpieces, segmented elements or any other suited material or manufacturing or construction method. [00045] In another embodiment of the present invention, the floatable wind turbine platform of the present invention may comprise a pneumatic production unit and/or may comprise a unit designed to produce methane out of the harvested wind energy and water or generated hydrogen, respectively.

[00046] In another embodiment of the present invention, the selective decelerating may be done by controllable spoilers, like the devices disclosed in EP 20 85 610, disposed on the VAWTs of the floatable wind turbine platform of the present invention.

[00047] In another embodiment of the present invention, any portion of the float body or the float body as a whole may be designed as a truss type grinder.

[00048] In another embodiment of the present invention, the second connecting element may comprise another conventional system for transmitting harvested energy to a power line.

[00049] In another embodiment of the present invention, the position of the floatable wind turbine platform may be controlled by one or more drift anchor. Drift anchors are usually formed by an anchoring chain, cable or an anchoring rope and a flow resistance element like a sufficiently large funnel out of plastic or a strong fabric. The cable/rope is fixed at the float body platform at a decentralized point by a winch allowing adjustment of the length of each distance between platform and anchor. The result of an unequal length caused by changing the rope/cable length is a torsional moment affecting the float bodies which brings the platform in a desired position. This allows inducing a torsional moment to the float bodies to change the orientation of the platform. The drift anchor can be installed permanently for e.g. fail safe positioning control or temporary, for events like e.g. maintenance.

[00050] However, the present invention is not limited to any of above described embodiments.

Claims

Claims:

1. Floatable platform (1) for wind power turbines (6), comprising:

at least two elongate float bodies (2) that float substantially vertically;

at least one first connecting member (3); and

at least one second connecting member (4), having a concentrically disposed anchoring (5), wherein

the at least two float bodies (2) are respectively pivotally connected to each other through a first connecting member (3),

the at least two float bodies (2) are respectively pivotally connected to each other through a second connecting member (4), and wherein

the first and the second connecting member (3, 4) are substantially parallel to each other such that a parallel swinging of the float bodies relative to each other is possible in a plane that is defined by the vertical longitudinal axes of the respectively connected two float bodies.

2. Floatable platform (1) according to claim 1, wherein at least one of the connecting members (3, 4) is coupled to a generator inside of the at least one float body (2), the generator being suitably for generating electric power out of the wave-induced relative oscillation of the float bodies (2).

3. Floatable platform (1) according to one of the preceding claims, the at least two float bodies (2) being hollow, having a substantially circular cross sectional area, and respectively comprising:

a substantially cylindrical upper portion (10) with a first diameter (a);

a substantially conical middle portion (11); and

a substantially cylindrical bottom portion (12) with a second diameter (b) being larger then the first diameter (a), wherein the upper portion (10) is formed as a truss type girder in the area of the water surface (8) to reduce the resistance of the at least two float bodies (2) to incoming waves.

4. Floatable platform (1) according to one of the preceding claims, wherein the at least two float bodies (2) are respectively sectioned into at least three segments by plates, wherein at least one of the bottom segments comprises ballast and wherein at least one segment is designed as a ballast tank for adjusting a draft of the float bodies (2).

5. Floatable wind turbine platform (1), comprising:

a floatable platform according to claim 4; and

at least two vertical axis wind turbines (6) respectively disposed on an upper side of one of the at least two float bodies (2).

6. Floatable wind turbine platform (1) according to claim 5, wherein the anchoring (5) comprises at least one pair of inductors for transmitting electric power inductively from the floatable platform (1) to a power line, and wherein the anchoring (5) comprises an upper anchoring member and a bottom anchoring member respectively comprising a substantially circular protrusion engaging with each other, the protrusions having a substantially L-shaped cross-section for allowing that the first anchoring member and the second anchoring member are pivo table with respect to each other by 360°.

7. Floatable wind turbine platform (1) according to claim 5 or 6, wherein the anchoring (5) comprises internal holes guiding a water pressure affecting a vertical movements of the anchoring (5) to friction surfaces of the anchoring members and their circular protrusions, respectively, the friction surfaces being stressed by compressive forces or tensile forces, such that a water film reduces the friction at the stressed locations.

8. Floatable wind turbine platform (1) according to one of claims 5 to 7, wherein modules (13) are respectively disposed in at least one segment of the at least two float bodies (2), wherein the modules (13) comprises at least one device of the group consisting of a system controlling device, a water pump, a power converter, a power rectifier, a power transformer, a power storing device, a hydrogen production unit and a hydrogen storage device.

9. Floatable wind turbine platform (1) according to one of claims 5 to 8, wherein a rotation direction (9) of at least one of the vertical rotor wind turbines (6) is opposite to a rotation direction (9) of another vertical axis wind turbine (6) on another float body (2) of the floatable platform (1).

10. Floatable wind turbine platform (1) according to claim 9, wherein the torques of the vertical rotor wind turbines (6) are variable through selective deceleration of single vertical rotor wind turbines (6) for generating a total torque of the floatable platform (1) through different rotational speeds of the vertical rotor wind turbines (6), wherein the deceleration is performed by mechanical brakes or flaps provided on the vertical rotor wind turbines (6).

11. Floatable wind turbine platform system, comprising:

at least two floatable platforms (1) according to one of claims 6 to 10; and wind direction sensors disposed at the floatable platforms (1) and transmitting wind direction data to system controllers of the floatable platforms (1), wherein the system controllers are suitable for communicating with each other and for automatically computing an alignment on basis of the data from the wind direction sensors that is improved regarding the power gain of the vertical rotor wind turbines (6) of each single floatable platform (1) and implementing the improved alignment through selectively decelerating the vertical rotor wind turbines (6).

12. Floatable Wind turbine platform (1) according to one of claims 1 to 11, further comprising at least one drift anchor attached to the platform via a winch allowing adjustment of the length of each distance between platform and anchor for inducing a torsional moment to the float bodies to change the orientation of the platform.