WO2010139725A1 - Method of installation of an offshore wind turbine and combination of an offshore wind turbine and a floating vessel - Google Patents

Method of installation of an offshore wind turbine and combination of an offshore wind turbine and a floating vessel Download PDF

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Publication number
WO2010139725A1
WO2010139725A1 PCT/EP2010/057706 EP2010057706W WO2010139725A1 WO 2010139725 A1 WO2010139725 A1 WO 2010139725A1 EP 2010057706 W EP2010057706 W EP 2010057706W WO 2010139725 A1 WO2010139725 A1 WO 2010139725A1
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WO
WIPO (PCT)
Prior art keywords
tower
section
wind turbine
installation
offshore wind
Prior art date
Application number
PCT/EP2010/057706
Other languages
French (fr)
Inventor
Anders Varming Rebsdorf
Original Assignee
Dong Energy A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dong Energy A/S filed Critical Dong Energy A/S
Priority to EP10722105A priority Critical patent/EP2437997A1/en
Publication of WO2010139725A1 publication Critical patent/WO2010139725A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/18—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes
    • B66C23/36—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes mounted on road or rail vehicles; Manually-movable jib-cranes for use in workshops; Floating cranes
    • B66C23/52—Floating cranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C1/00—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles
    • B66C1/10—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles by mechanical means
    • B66C1/62—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles by mechanical means comprising article-engaging members of a shape complementary to that of the articles to be handled
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/18—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes
    • B66C23/20—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes with supporting couples provided by walls of buildings or like structures
    • B66C23/207—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes with supporting couples provided by walls of buildings or like structures with supporting couples provided by wind turbines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/18—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes
    • B66C23/26—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes for use on building sites; constructed, e.g. with separable parts, to facilitate rapid assembly or dismantling, for operation at successively higher levels, for transport by road or rail
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B17/02—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
    • E02B17/027—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto steel structures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
    • F03D13/10—Assembly of wind motors; Arrangements for erecting wind motors
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B2017/0039—Methods for placing the offshore structure
    • E02B2017/0043—Placing the offshore structure on a pre-installed foundation structure
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B2017/0056—Platforms with supporting legs
    • E02B2017/006—Platforms with supporting legs with lattice style supporting legs
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B2017/0091—Offshore structures for wind turbines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00—Components
    • F05B2240/90—Mounting on supporting structures or systems
    • F05B2240/95—Mounting on supporting structures or systems offshore
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/727—Offshore wind turbines

Definitions

  • the present invention relates to a method of installation of an offshore wind turbine on the seabed, the offshore wind turbine comprising a tower composed by at least a first section and a second section, whereby the tower by means of a vessel is transported to an installation location in a non-upright position of the tower, and whereby the tower is raised to its upright position at the installation location.
  • EP 1 234 978 A2 discloses a method of installation of an offshore wind turbine, whereby the complete assembled wind turbine is transported on a barge with the tower of the wind turbine in its horizontal position. In order to erect the tower, it is moored by means of wires and tilted over the edge of the barge to its vertical position. However, it may be difficult to control the tilting operation of the long and heavy tower.
  • DE 103 32 382 A1 discloses a method of installation of an offshore wind turbine, whereby a foundation is established on the seabed comprising a pile with a connection piece just above the sea surface. Subsequently, the wind turbine is transported to the installation site on a floating vessel. The tower of the turbine is carried in an inclined position on the vessel, and, at the installation site, the bottom of the tower is engaged with the connection piece, whereby the tower may be erected to its vertical position.
  • the float- ing vessel required is very large and the installation procedure consequently very costly.
  • the foundation has to be installed in a separate process.
  • EP 1 321 671 A1 discloses a floating transport platform for transportation of a completely assembled offshore wind turbine on the sea.
  • the transport platform comprises a tiltable gripping mechanism for engagement with the tower of the wind turbine.
  • the gripping mechanism may be tilted between a position in which the tower of the wind turbine is in an inclined position and a position in which the tower is in its vertical position.
  • the wind turbine may be transported to an installation site in the inclined position and erected to its vertical position at the installation site, whereupon the tower may be mounted on a connection piece located just above the sea surface and arranged on a foundation pile established on the seabed.
  • the floating transport platform required is very large, and the foundation has to be installed in a separate process.
  • WO 2008/119863 A1 discloses a land-based wind turbine comprising a lattice tower composed by a lower section and an upper section that are hingedly connected.
  • the lower section is also hingedly connected to a foundation on ground so that it may be erected by means of a traction wire.
  • the upper section may also be erected by means of a traction wire.
  • the object of the present invention is to provide a simple and reliable method of installation of an offshore wind turbine on the seabed.
  • the first section and the second section of the tower are connected pivotally about a hinge axis, the first section of the tower is swung about the hinge axis down into the sea to its upright position when the second section of the tower is still carried in a non-upright position by the vessel, the first section of the tower is installed on the seabed, and, subsequently, the second section of the tower is swung about the hinge axis to its upright position and locked to the first section of the tower in this position.
  • the first section of the tower may easily be carefully and precisely positioned during the installation on the seabed, and the second section of the tower may likewise be erected under controlled conditions, whereby the complete installation procedure may be performed without any need for large and heavy cranes. Consequently, the wind turbine may be transported by means of a much smaller vessel than would otherwise be required.
  • the off- shore wind turbine may in this way be erected much faster than it is the case according to conventional methods, and the method of installation may require smaller investments than is required by conventional methods of installation.
  • the first section of the tower is carried by a separate floating vessel.
  • the complete tower may be transported to the installation location without the need for displacement of the tower on the vessel before swinging the first section of the tower about the hinge axis down into the sea.
  • the separate floating vessel comprises at least one balloon
  • the first section of the tower is allowed to swing down into the sea by allowing gas to escape from the at least one balloon.
  • the separate floating vessel comprises at least one pontoon
  • the first section of the tower is allowed to swing down into the sea by allowing ballast water to enter the at least one pontoon.
  • the first section of the tower is allowed to swing down into the sea by rolling out a wire from the separate floating vessel, said wire carry- ing the first section of the tower.
  • the separate floating vessel may have the form of a simple barge or the like.
  • the first section of the tower is allowed to swing down into the sea by rolling out a wire extended between the first and the second section of the tower. Thereby, the need for a separate floating vessel carrying the first section of the tower during swinging down this section may be eliminated.
  • the hinge axis of the pivotal connection between the first section and the second sec- tion of the tower is located between edges of the vessel, so that a good balance of the vessel may be obtained, and, before that the first section of the tower is allowed to swing down into the sea, the tower is displaced along the vessel, so that the hinge axis is located over the sea, thereby enabling the first section of the tower to be swung down into the sea to its upright position.
  • the second section of the tower is swung about the hinge axis to its upright position by means of a traction wire extended between the first and the second section of the tower and by means of a winding gear winding up the traction wire.
  • the second section of the tower may be erected without the need for any crane or similar high structure.
  • the second section of the tower is swung about the hinge axis to its upright position by means of a traction wire extended between the second section of the tower and the separate floating vessel and by means of a winding gear winding up the traction wire.
  • the second section of the tower may be erected without the need for any crane or similar high structure.
  • the first section of the tower is installed on the seabed by means of a pre-established foundation.
  • the first section of the tower is installed on the seabed by means of a so-called bucket foundation, whereby at least one bucket-like structure mounted on the first section of the tower is placed with its opening facing the seabed, and, subsequently, water is pumped out from the interior of the at least one bucket-like structure, so that the bucket-like structure is pressed down into the seabed.
  • a very simple and fast installation of the offshore wind turbine may be obtained, as the foundation by means of the at least one bucket-like structure may be facilitated in that the position of the bucket-like structure may be controlled by the vessel on which the second section of the tower is carried. Therefore, separate means for controlling the position of and/or for guiding the bucket-like structure during the establish- ment of the foundation may be omitted.
  • a synergistic effect is obtained when the at least one bucket-like structure mounted on the first section of the tower is guided by means of the tower itself.
  • the at least one bucket-like structure is utilized as a bal- last tank during the operation of swinging the first section of the tower down into the sea, whereby the opening of the bucket-like structure is covered by a removable lid and ballast water is allowed to enter the interior of the bucket- like structure gradually through a controlled valve, and whereby the removable lid is removed from the bucket-like structure before installation of the first section of the tower on the seabed.
  • a separate floating vessel comprising a pontoon or ballast tank for carrying the first section may be omitted or have reduced capacity, or a traction wire for carrying the first section during the operation of swinging may be assisted.
  • the height position of the vessel is controlled by means of pumping ballast water to or from at least one ballast tank comprised by the vessel.
  • the height position of the tower may be adapted according to the tide level so that the first section is in the correct position for mounting on the seabed.
  • the height position of the tower may be adjusted accordingly by means of the at least one ballast tank during pressing down of the bucket-like structure into the seabed.
  • the pivotal connection between the first section and the second section of the tower is accomplished by means of a separate hinge tool that is mounted between the first section and the second section of the tower before raising of the tower, and the separate hinge tool is removed from the tower after the second section of the tower, in its upright position, has been locked to the first section of the tower.
  • a separate hinge tool that is mounted between the first section and the second section of the tower before raising of the tower, and the separate hinge tool is removed from the tower after the second section of the tower, in its upright position, has been locked to the first section of the tower.
  • the separate hinge tool comprises a wire drive, a hydraulic actuator or other suitable mechanism for opening and closing the separate hinge tool.
  • the mechanism for opening and closing the separate hinge tool does not have to be mounted separately to the tower, and the installation procedure is thereby facilitated.
  • the separate hinge tool comprises at least one pontoon, preferably in combination with a ballast tank, and thereby forms at least a part of the vessel and/or at least a part of the separate floating vessel.
  • the tower may be further stabilized during transport on the sea.
  • a separate mounting procedure whereby the tower is mounted on the vessel may be avoided.
  • the vessel is formed by at least one ballast tank com- prised by the separate hinge tool and by at least one ballast tank comprised by a separate tool mounted on the second section of the tower.
  • a dedicated mounting procedure for the tower may be followed, whereby a cumbersome mounting procedure of the tower on one or more transport vessels in the form of barges or the like may be avoided.
  • the present invention further relates to a combination of an offshore wind turbine and a floating vessel, the offshore wind turbine comprising a tower composed by at least a first section and a second section, the floating vessel being adapted to carry the tower to an installation location in a non-upright position of the tower, and the tower being adapted to be raised to its upright position at the installation location.
  • the combination of an offshore wind turbine and a floating vessel is characterized in that the first section and the second section of the tower are adapted to, at least during raising of the tower, be connected pivotally about a hinge axis, in that the first section of the tower is adapted to be swung about the hinge axis down into the sea to its upright position when the second section of the tower is still carried in a non-upright position by the floating vessel, and in that the second section of the tower is adapted to, subsequent to installation of the first section of the tower on the seabed, be swung about the hinge axis to its upright position and locked to the first section of the tower in this position.
  • the first section of the tower is provided with a so-called bucket foundation comprising at least one bucket-like structure having an opening facing the seabed in the mounting position of the first section of the tower, and a pump is provided to pump water out from the interior of the at least one bucket-like structure, so that the bucket-like structure may be pressed down into the seabed.
  • the tower is combined by a lattice tower and a tubular tower, so that the first section of the tower is a lattice construction, and the second section is composed by a lower lattice construction and an upper tubular construction, the lower lattice construction being adapted to be connected pivotally to the first section of the tower.
  • a standard tubular wind turbine tower may be employed for the upper tubular construction, whereby only the lower lattice construction of the second section and the first section need to be a specially adapted construction.
  • the present invention further relates to a wind turbine comprising a tower composed by at least a first section and a second section, the first section and the second section of the tower being adapted to, at least during raising of the tower, be connected pivotally about a hinge axis.
  • the wind turbine is characterized in that it is an offshore wind turbine, in that the first section of the tower is provided with a so-called bucket foundation comprising at least one bucket-like structure having an opening facing the seabed in the mounting position of the first section of the tower, and in that a pump is provided to pump water out from the interior of the at least one bucket-like structure, so that the bucket-like structure may be pressed down into the seabed.
  • the present invention further relates to a hinge tool adapted to be mounted between a first section and a second section of a tower of an offshore wind turbine before raising of the tower and adapted to be removed from the tower after raising of the tower, the hinge tool comprising a first hinge part adapted to be mounted at an upper end of the first section of the tower and a second hinge part adapted to be mounted at a lower end of the second section of the tower, the first hinge part and the second hinge part being hingedly interconnected, and the hinge tool comprising at least one pontoon, preferably in combination with a ballast tank.
  • the present invention further relates to a combination of a hinge tool as described above and a separate tool adapted to be mounted on the second section of the tower.
  • the combination is characterized in that the separate tool is adapted to be mounted at an upper end of the second section and comprises at least one pontoon, preferably in combination with a ballast tank.
  • a dedicated mounting procedure for the tower may be followed, whereby a cumbersome mounting procedure of the tower on one or more transport vessels in the form of barges or the like may be avoided.
  • Figs. 1 to 8 show different steps of a method of installation of an offshore wind turbine according to the invention
  • Fig. 9 illustrates another embodiment of the method of installation according to the invention.
  • Fig. 1 shows the transportation of an offshore wind turbine 1 comprising a tower 2 composed by a first section 3 and a second section 4.
  • the first sec- tion 3 comprises a lower end 5 and an upper end 6
  • the second section 4 comprises a lower end 7 and an upper end 8.
  • the upper end 6 of the first section 3 is by means of a hinge connection 9 connected pivotally about a hinge axis 10 to the lower end 7 of the second section 4.
  • the offshore wind turbine 1 comprises at the upper end 8 of the second section 4 a nacelle 11 on which two or three rotor blades 12 may be premounted.
  • the tower 2 is lying down in a non-upright position, whereby the second section 4 of the tower is carried mainly by a vessel 13 floating a the sea surface 16, and the first section 3 of the tower at its lower end 5 is carried by a separate floating vessel 14 and at its upper end 6 is carried by the vessel 13 via the second section 4 and the hinge connection 9.
  • the first section 3 of the tower 2 as well as the second section 4 of the tower are positioned with their longitudinal axes in a substantially horizontal direction during transportation by means of the vessels 13, 14.
  • first and second sections 3, 4 may be transported in other non-upright positions, such as with their longitudinal axes in an inclined position of, for instance, 30, 50, 70 degrees or any other suitable angle to the horizontal.
  • the sections 3, 4 need not be transported with their longitudinal axes extending in the same direction; this fact is indicated in Fig. 1 , whereby the first section 3 is slightly inclined downwards in relation to the second section 4 during transportation.
  • the vessel 13 further carries a generator 15 to be mounted on the nacelle 11 after installation of the tower 2 on the seabed.
  • the generator 15 could also be mounted on the nacelle 11 already before installation of the tower on the seabed.
  • the generator may be very heavy so that it may be preferred to install it after the installation of the tower.
  • the tower 2 may be transported and installed on the seabed, and the nacelle 11 , the rotor blades 12 and the generator 15 may be mounted subsequently by known methods, such as by means of wire drive or crane.
  • the tower equipped with all of, or some of the following components: the nacelle 11 , the rotor blades 12 and the generator 15 may be transported and installed on the seabed by the method according to the invention.
  • relative indications such as lower and upper refer to the offshore wind turbine in the erected position of the tower 2 such as shown in Figs. 7 and 8.
  • the invention is exemplified by means of a horizontal axis wind turbine (HAWT), however, the invention is equally applicable to other kinds of wind turbines, such as for example a vertical axis wind turbine (VAWT).
  • the tower 2 of the wind turbine is illustrated as a lattice construction, however, according to the invention, the tower may just as well be a tubular tower or a combination of a lattice construction and a tubular tower.
  • the first section 3 of the tower is to be installed on the seabed 17 by means of a pre-established foundation 18.
  • the foundation 18 may be of any suitable type, such as the monopile foundation, the gravitation foundation or the so-called bucket foundation, whereby a bucket-like structure of the foundation is placed with its opening facing the seabed, and, subsequently, water is pumped out from the interior of the bucket-like structure, so that the bucket-like structure is pressed down into the seabed by means of suction pressure.
  • the separate floating vessel 14 is illustrated as a simple balloon which in Fig. 1 is inflated, so that the first section 3 of the tower 2 is floating above the sea surface 16, and which in Fig. 2 is deflated partly so that the first section 3 is beginning to swing down into the sea.
  • This swinging motion of the first section 3 is further controlled by means of a wire 19 illus- trated in Figs. 2 to 6 and connecting a point 20 on the lower end 7 of the second section 4 of the tower 2 with a point 21 on the upper end 6 of the first section 3 of the tower.
  • the wire is rolled out from a not shown wire drive. As it may be seen in Fig.
  • the points 20, 21 meet each other.
  • the points 20, 21 are positioned below the hinge axis 10 in the erected position of the tower, however, this position may be different.
  • the hinge axis 10 may be so positioned that the first section 3 may swing in either direction from the position in which its longitudinal axis coin- cides with the longitudinal axis of the second section 4.
  • the procedure illustrated in the Figs. 1 to 3 of swinging down the first section 3 by means of a combination of a separate floating vessel 14 in the form of a simple balloon and a wire 19 is only one possible embodiment of the procedure.
  • the separate floating vessel 14 could be used alone and could be in the form of a pontoon possibly in combination with a ballast tank, that is, a pontoon being itself a ballast tank or a pontoon combined with a separate ballast tank.
  • the wire 19 could be used alone and/or could be extended between the first section 3 and the separate floating vessel 14 or any other suitable floating vessel or any other suitable structure, such as also, for instance, the vessel 13.
  • the separate floating vessel 14 could therefore also be located floating above the first section 3 of the tower 2.
  • the vessel 13 may utilize a not shown ballast tank to take in or pump out ballast water.
  • waves on the sea may result in up- and down movements of the first section 3 of the tower during attachment of the first section 3 to the pre-established foundation 18.
  • the first section 3 may by means of said ballast tank be lowered until a certain distance remains between the first section 3 and the foundation 18, and the first section 3 may then be pulled the last distance to the foundation 18 by means of a wire drive or the like established between the first section 3 and the foundation 18.
  • the erection of the second section 4 of the tower is assisted by means of a second wire 22 that connects a point 23 at the middle of the second section 4 and the vessel 13.
  • the second wire 22 is rolled out from the vessel 13 by means of a not shown wire drive. Thereby, the second wire 22 counteracts the upward swinging of the second section 4, so that a too fast motion is avoided.
  • the second section 4 of the tower could alternatively be erected by means of the wires 19, 22 shown and/or other wires, whereby the wires employed for the erection could be connected to any other suitable floating or non-floating vessels or structures than those illustrated in the drawings.
  • Fig. 7 shows the tower 2 in its fully erected state
  • Fig. 8 shows how the generator 15 may be lifted to the upper end 8 of the second section 4 of the tower 2 by means of a wire, possibly the second wire 22 also used for the erection of the second section 4.
  • Fig. 9 illustrates another embodiment of the method of installation of an offshore wind turbine on the seabed according to the invention.
  • the offshore wind turbine may be transported to its installation site and installed on the seabed by means of specially adapted floating tools 24, 25, 26, whereby the employment of conventional floating vessels such as barges or the like for carrying the wind turbine may be avoided.
  • Fig. 9 shows the step of the method of installation, whereby the wind turbine has been transported to its installation site, and whereby the first section 3 of the tower has been swung down into the sea and is to be installed to the seabed by means of a so-called bucket foundation.
  • a separate floating hinge tool 24 is mounted between the first section 3 and the second section 4 of the tower 2, before the tower is transported on the sea. Furthermore, a separate floating tool 25 is attached to the upper end 8 of the second section 4 of the tower.
  • the separate hinge tool 24 comprises a first part 27 and a second part 28 that are hingedly interconnected by means of a hinge 29.
  • the first part 27 is attached to the upper end 6 of the first section 3 of the tower 2
  • the second part 28 is attached to the lower end 7 of the second section 4 of the tower.
  • the hinge 29 either part 27, 28 of the separate hinge tool 24 is connected to either end of a hydraulic cylinder 30, respectively, whereby the separate hinge tool 24 may be operated.
  • the separate hinge tool 24 may be operated by means of a wire drive or any other suitable drive mechanism.
  • a further example of such drive mechanism may be a combination of a hydraulic actuator and a wire drive, whereby a wire may connect one or both ends of the hydraulic actuator to either part 27, 28, respectively, of the separate hinge tool 24.
  • the separate hinge tool 24 may be operated to open, whereby the first section 4 of the tower 2 may swing down into the sea to reach the position shown in Fig. 9, and secondly, it may be operated to close, whereby the second section 4 of the tower may be erected and the flanges 31 , 32 of the first and second section 3, 4, respectively, may be brought together for connection by means of not shown bolts or any other suitable means.
  • the separate hinge tool 24 may be removed from the tower 2.
  • the separate floating tool 25 may be removed from the tower 2.
  • the separate hinge tool 24 and the separate floating tool 25 each comprises at least one pontoon and/or a ballast tank, so that the tools may carry the tower 2 on the sea and so that the swinging motion of the first section 3 of the tower down into the sea and the vertical positioning and adaptation to the tide level of the tower during installation on the seabed may be controlled.
  • the separate hinge tool 24 may comprise at least one pontoon and/or a ballast tank in either one of the first and second part 27, 28, whereby better control of the installation procedure may be obtained.
  • Fig. 9 illustrates the employment of bucket-like structures 26 for the foundation of the first section 3 of the tower on the seabed 17.
  • each leg of the lattice construction of the first section 3 is provided with one bucket-like structure 26 placed with its opening facing the seabed, and, subsequently, water is pumped out from the interior of the bucket-like structures, so that these are pressed down into the seabed.
  • the suction pressure of each bucket-like structure, respectively, during the pressing down the correct vertical direction of the longitudinal axis of the tower may be achieved.
  • one large bucket-like structure may be utilized for the foundation instead of one for each leg of the tower.
  • the correct vertical direction of the tower may also in this manner, according to well-known techniques, be achieved by controlling the viscosity of the seabed and the friction during pressing down of the bucket-like structure.
  • they may also be utilized as pontoons and/or ballast tanks during swinging down into the sea of the first section 3 of the tower. During this use, their openings may be covered by a lid or the like.
  • the separate hinge tool and/or the bucket-like structure or structures may be employed without incorporated pontoon or ballast tank and/or in combination with more conventional vessels for transportation of the wind turbine on the sea.

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Abstract

A tower (2) of an offshore wind turbine is composed by a first section (3) and a second section (4) and is by means of a vessel (13) transported to an installation location in a non-upright position. The first section (3) and the second section (4) of the tower (2) are during raising of the tower connected pivotally about a hinge axis (10), and the first section (3) of the tower is swung about the hinge axis (10) down into the sea to its upright position when the second section (4) of the tower is still carried in a non-upright position by the vessel (13). The first section (3) of the tower is installed on the seabed (17), and, subsequently, the second section (4) of the tower is swung about the hinge axis (10) to its upright position and locked to the first section (3) of the tower in this position.

Description

Method of installation of an offshore wind turbine and combination of an offshore wind turbine and a floating vessel
The present invention relates to a method of installation of an offshore wind turbine on the seabed, the offshore wind turbine comprising a tower composed by at least a first section and a second section, whereby the tower by means of a vessel is transported to an installation location in a non-upright position of the tower, and whereby the tower is raised to its upright position at the installation location.
EP 1 234 978 A2 discloses a method of installation of an offshore wind turbine, whereby the complete assembled wind turbine is transported on a barge with the tower of the wind turbine in its horizontal position. In order to erect the tower, it is moored by means of wires and tilted over the edge of the barge to its vertical position. However, it may be difficult to control the tilting operation of the long and heavy tower.
DE 103 32 382 A1 discloses a method of installation of an offshore wind turbine, whereby a foundation is established on the seabed comprising a pile with a connection piece just above the sea surface. Subsequently, the wind turbine is transported to the installation site on a floating vessel. The tower of the turbine is carried in an inclined position on the vessel, and, at the installation site, the bottom of the tower is engaged with the connection piece, whereby the tower may be erected to its vertical position. However, the float- ing vessel required is very large and the installation procedure consequently very costly. Furthermore, the foundation has to be installed in a separate process.
EP 1 321 671 A1 discloses a floating transport platform for transportation of a completely assembled offshore wind turbine on the sea. The transport platform comprises a tiltable gripping mechanism for engagement with the tower of the wind turbine. The gripping mechanism may be tilted between a position in which the tower of the wind turbine is in an inclined position and a position in which the tower is in its vertical position. In this way, the wind turbine may be transported to an installation site in the inclined position and erected to its vertical position at the installation site, whereupon the tower may be mounted on a connection piece located just above the sea surface and arranged on a foundation pile established on the seabed. The floating transport platform required is very large, and the foundation has to be installed in a separate process.
WO 2008/119863 A1 discloses a land-based wind turbine comprising a lattice tower composed by a lower section and an upper section that are hingedly connected. The lower section is also hingedly connected to a foundation on ground so that it may be erected by means of a traction wire. Sub- sequently, the upper section may also be erected by means of a traction wire.
The object of the present invention is to provide a simple and reliable method of installation of an offshore wind turbine on the seabed.
In view of this object, the first section and the second section of the tower, at least during raising of the tower, are connected pivotally about a hinge axis, the first section of the tower is swung about the hinge axis down into the sea to its upright position when the second section of the tower is still carried in a non-upright position by the vessel, the first section of the tower is installed on the seabed, and, subsequently, the second section of the tower is swung about the hinge axis to its upright position and locked to the first section of the tower in this position.
In this way, the first section of the tower may easily be carefully and precisely positioned during the installation on the seabed, and the second section of the tower may likewise be erected under controlled conditions, whereby the complete installation procedure may be performed without any need for large and heavy cranes. Consequently, the wind turbine may be transported by means of a much smaller vessel than would otherwise be required. The off- shore wind turbine may in this way be erected much faster than it is the case according to conventional methods, and the method of installation may require smaller investments than is required by conventional methods of installation.
In an embodiment, the first section of the tower is carried by a separate floating vessel. Thereby, the complete tower may be transported to the installation location without the need for displacement of the tower on the vessel before swinging the first section of the tower about the hinge axis down into the sea.
In an embodiment, the separate floating vessel comprises at least one balloon, and the first section of the tower is allowed to swing down into the sea by allowing gas to escape from the at least one balloon. Thereby, a simple way of positioning the first section of the tower may be obtained in that the need for a winding gear may be eliminated.
In an embodiment, the separate floating vessel comprises at least one pontoon, and the first section of the tower is allowed to swing down into the sea by allowing ballast water to enter the at least one pontoon. Thereby, a simple way of positioning the first section of the tower may be obtained in that the need for a wire drive may be eliminated.
In an embodiment, the first section of the tower is allowed to swing down into the sea by rolling out a wire from the separate floating vessel, said wire carry- ing the first section of the tower. Thereby, the separate floating vessel may have the form of a simple barge or the like. In an embodiment, the first section of the tower is allowed to swing down into the sea by rolling out a wire extended between the first and the second section of the tower. Thereby, the need for a separate floating vessel carrying the first section of the tower during swinging down this section may be eliminated.
In an embodiment, during transportation to the installation location, the hinge axis of the pivotal connection between the first section and the second sec- tion of the tower is located between edges of the vessel, so that a good balance of the vessel may be obtained, and, before that the first section of the tower is allowed to swing down into the sea, the tower is displaced along the vessel, so that the hinge axis is located over the sea, thereby enabling the first section of the tower to be swung down into the sea to its upright position. Thereby, the need for a separate floating vessel carrying the first section of the tower may be eliminated.
In an embodiment, the second section of the tower is swung about the hinge axis to its upright position by means of a traction wire extended between the first and the second section of the tower and by means of a winding gear winding up the traction wire. Thereby, the second section of the tower may be erected without the need for any crane or similar high structure.
In an embodiment, the second section of the tower is swung about the hinge axis to its upright position by means of a traction wire extended between the second section of the tower and the separate floating vessel and by means of a winding gear winding up the traction wire. Thereby, the second section of the tower may be erected without the need for any crane or similar high structure. In an embodiment, the first section of the tower is installed on the seabed by means of a pre-established foundation.
In an embodiment, the first section of the tower is installed on the seabed by means of a so-called bucket foundation, whereby at least one bucket-like structure mounted on the first section of the tower is placed with its opening facing the seabed, and, subsequently, water is pumped out from the interior of the at least one bucket-like structure, so that the bucket-like structure is pressed down into the seabed. Thereby, a very simple and fast installation of the offshore wind turbine may be obtained, as the foundation by means of the at least one bucket-like structure may be facilitated in that the position of the bucket-like structure may be controlled by the vessel on which the second section of the tower is carried. Therefore, separate means for controlling the position of and/or for guiding the bucket-like structure during the establish- ment of the foundation may be omitted. In other words, a synergistic effect is obtained when the at least one bucket-like structure mounted on the first section of the tower is guided by means of the tower itself.
In an embodiment, the at least one bucket-like structure is utilized as a bal- last tank during the operation of swinging the first section of the tower down into the sea, whereby the opening of the bucket-like structure is covered by a removable lid and ballast water is allowed to enter the interior of the bucket- like structure gradually through a controlled valve, and whereby the removable lid is removed from the bucket-like structure before installation of the first section of the tower on the seabed. Thereby, a separate floating vessel comprising a pontoon or ballast tank for carrying the first section may be omitted or have reduced capacity, or a traction wire for carrying the first section during the operation of swinging may be assisted.
In an embodiment, at least during installation of the offshore wind turbine, the height position of the vessel is controlled by means of pumping ballast water to or from at least one ballast tank comprised by the vessel. Thereby, during installation of the tower on the seabed, the height position of the tower may be adapted according to the tide level so that the first section is in the correct position for mounting on the seabed. In the case that a bucket-like structure is utilized for the foundation, the height position of the tower may be adjusted accordingly by means of the at least one ballast tank during pressing down of the bucket-like structure into the seabed.
In an embodiment, the pivotal connection between the first section and the second section of the tower is accomplished by means of a separate hinge tool that is mounted between the first section and the second section of the tower before raising of the tower, and the separate hinge tool is removed from the tower after the second section of the tower, in its upright position, has been locked to the first section of the tower. Thereby, only one hinge tool is necessary for installation of several offshore wind turbines, as the hinge tool may be re-used several times. Furthermore, the design of the offshore wind turbine need not to be affected by the hinge tool, as it is removed after use. Consequently, a rather large hinge tool may be employed; for instance, rather long levers may be incorporated into the tool in order to assist the opening and closing mechanism for the hinge tool. As the effective forces on the hinge tool may be large, the hinge tool may be rather costly and it may therefore be of advantage that only one hinge tool is necessary for the installation of several wind turbines.
In an embodiment, the separate hinge tool comprises a wire drive, a hydraulic actuator or other suitable mechanism for opening and closing the separate hinge tool. Thereby, the mechanism for opening and closing the separate hinge tool does not have to be mounted separately to the tower, and the installation procedure is thereby facilitated. In an embodiment, the separate hinge tool comprises at least one pontoon, preferably in combination with a ballast tank, and thereby forms at least a part of the vessel and/or at least a part of the separate floating vessel. Thereby, the tower may be further stabilized during transport on the sea. In the case that the vessel is formed entirely by at least one ballast tank comprised by the separate hinge tool, a separate mounting procedure whereby the tower is mounted on the vessel may be avoided.
In an embodiment, the vessel is formed by at least one ballast tank com- prised by the separate hinge tool and by at least one ballast tank comprised by a separate tool mounted on the second section of the tower. Thereby, a dedicated mounting procedure for the tower may be followed, whereby a cumbersome mounting procedure of the tower on one or more transport vessels in the form of barges or the like may be avoided.
The present invention further relates to a combination of an offshore wind turbine and a floating vessel, the offshore wind turbine comprising a tower composed by at least a first section and a second section, the floating vessel being adapted to carry the tower to an installation location in a non-upright position of the tower, and the tower being adapted to be raised to its upright position at the installation location. The combination of an offshore wind turbine and a floating vessel is characterized in that the first section and the second section of the tower are adapted to, at least during raising of the tower, be connected pivotally about a hinge axis, in that the first section of the tower is adapted to be swung about the hinge axis down into the sea to its upright position when the second section of the tower is still carried in a non-upright position by the floating vessel, and in that the second section of the tower is adapted to, subsequent to installation of the first section of the tower on the seabed, be swung about the hinge axis to its upright position and locked to the first section of the tower in this position. Thereby, the above-mentioned features may be obtained. In an embodiment, the first section of the tower is provided with a so-called bucket foundation comprising at least one bucket-like structure having an opening facing the seabed in the mounting position of the first section of the tower, and a pump is provided to pump water out from the interior of the at least one bucket-like structure, so that the bucket-like structure may be pressed down into the seabed. Thereby, the above-mentioned features may be obtained.
In an embodiment, the tower is combined by a lattice tower and a tubular tower, so that the first section of the tower is a lattice construction, and the second section is composed by a lower lattice construction and an upper tubular construction, the lower lattice construction being adapted to be connected pivotally to the first section of the tower. Thereby, a standard tubular wind turbine tower may be employed for the upper tubular construction, whereby only the lower lattice construction of the second section and the first section need to be a specially adapted construction.
The present invention further relates to a wind turbine comprising a tower composed by at least a first section and a second section, the first section and the second section of the tower being adapted to, at least during raising of the tower, be connected pivotally about a hinge axis. The wind turbine is characterized in that it is an offshore wind turbine, in that the first section of the tower is provided with a so-called bucket foundation comprising at least one bucket-like structure having an opening facing the seabed in the mounting position of the first section of the tower, and in that a pump is provided to pump water out from the interior of the at least one bucket-like structure, so that the bucket-like structure may be pressed down into the seabed.
The present invention further relates to a hinge tool adapted to be mounted between a first section and a second section of a tower of an offshore wind turbine before raising of the tower and adapted to be removed from the tower after raising of the tower, the hinge tool comprising a first hinge part adapted to be mounted at an upper end of the first section of the tower and a second hinge part adapted to be mounted at a lower end of the second section of the tower, the first hinge part and the second hinge part being hingedly interconnected, and the hinge tool comprising at least one pontoon, preferably in combination with a ballast tank. Thereby, the above-mentioned features may be obtained.
The present invention further relates to a combination of a hinge tool as described above and a separate tool adapted to be mounted on the second section of the tower. The combination is characterized in that the separate tool is adapted to be mounted at an upper end of the second section and comprises at least one pontoon, preferably in combination with a ballast tank. Thereby, a dedicated mounting procedure for the tower may be followed, whereby a cumbersome mounting procedure of the tower on one or more transport vessels in the form of barges or the like may be avoided.
The invention will now be explained in more detail below by means of exam- pies of embodiments with reference to the very schematic drawing, in which
Figs. 1 to 8 show different steps of a method of installation of an offshore wind turbine according to the invention, and
Fig. 9 illustrates another embodiment of the method of installation according to the invention.
Fig. 1 shows the transportation of an offshore wind turbine 1 comprising a tower 2 composed by a first section 3 and a second section 4. The first sec- tion 3 comprises a lower end 5 and an upper end 6 and the second section 4 comprises a lower end 7 and an upper end 8. The upper end 6 of the first section 3 is by means of a hinge connection 9 connected pivotally about a hinge axis 10 to the lower end 7 of the second section 4. Furthermore, the offshore wind turbine 1 comprises at the upper end 8 of the second section 4 a nacelle 11 on which two or three rotor blades 12 may be premounted. At this stage of the method of installation of the offshore wind turbine on the seabed, the tower 2 is lying down in a non-upright position, whereby the second section 4 of the tower is carried mainly by a vessel 13 floating a the sea surface 16, and the first section 3 of the tower at its lower end 5 is carried by a separate floating vessel 14 and at its upper end 6 is carried by the vessel 13 via the second section 4 and the hinge connection 9. In the embodiment of the method of installation illustrated in Fig. 1 , the first section 3 of the tower 2 as well as the second section 4 of the tower are positioned with their longitudinal axes in a substantially horizontal direction during transportation by means of the vessels 13, 14. However, it is, of course, possible that the first and second sections 3, 4 may be transported in other non-upright positions, such as with their longitudinal axes in an inclined position of, for instance, 30, 50, 70 degrees or any other suitable angle to the horizontal. In fact, the sections 3, 4 need not be transported with their longitudinal axes extending in the same direction; this fact is indicated in Fig. 1 , whereby the first section 3 is slightly inclined downwards in relation to the second section 4 during transportation.
The vessel 13 further carries a generator 15 to be mounted on the nacelle 11 after installation of the tower 2 on the seabed. Of course, the generator 15 could also be mounted on the nacelle 11 already before installation of the tower on the seabed. However, especially in the case of a gearless drive, the generator may be very heavy so that it may be preferred to install it after the installation of the tower.
According to the invention, the tower 2 may be transported and installed on the seabed, and the nacelle 11 , the rotor blades 12 and the generator 15 may be mounted subsequently by known methods, such as by means of wire drive or crane. Alternatively, the tower equipped with all of, or some of the following components: the nacelle 11 , the rotor blades 12 and the generator 15 may be transported and installed on the seabed by the method according to the invention.
It should be noted that in the present context, relative indications such as lower and upper refer to the offshore wind turbine in the erected position of the tower 2 such as shown in Figs. 7 and 8.
In the figures, the invention is exemplified by means of a horizontal axis wind turbine (HAWT), however, the invention is equally applicable to other kinds of wind turbines, such as for example a vertical axis wind turbine (VAWT). The tower 2 of the wind turbine is illustrated as a lattice construction, however, according to the invention, the tower may just as well be a tubular tower or a combination of a lattice construction and a tubular tower.
As it may be seen in Fig. 1 , the first section 3 of the tower is to be installed on the seabed 17 by means of a pre-established foundation 18. The foundation 18 may be of any suitable type, such as the monopile foundation, the gravitation foundation or the so-called bucket foundation, whereby a bucket-like structure of the foundation is placed with its opening facing the seabed, and, subsequently, water is pumped out from the interior of the bucket-like structure, so that the bucket-like structure is pressed down into the seabed by means of suction pressure.
In Figs. 1 and 2, the separate floating vessel 14 is illustrated as a simple balloon which in Fig. 1 is inflated, so that the first section 3 of the tower 2 is floating above the sea surface 16, and which in Fig. 2 is deflated partly so that the first section 3 is beginning to swing down into the sea. This swinging motion of the first section 3 is further controlled by means of a wire 19 illus- trated in Figs. 2 to 6 and connecting a point 20 on the lower end 7 of the second section 4 of the tower 2 with a point 21 on the upper end 6 of the first section 3 of the tower. During this swinging motion, the wire is rolled out from a not shown wire drive. As it may be seen in Fig. 7, in the erected position of the tower 2, the points 20, 21 meet each other. In the embodiment shown in Figs. 1 to 8, the points 20, 21 are positioned below the hinge axis 10 in the erected position of the tower, however, this position may be different. For instance, the hinge axis 10 may be so positioned that the first section 3 may swing in either direction from the position in which its longitudinal axis coin- cides with the longitudinal axis of the second section 4.
In Fig. 3, the separate floating vessel 14 has been removed and the swinging motion downwards of the first section 3 of the tower is controlled entirely by means of the wire 19.
The procedure illustrated in the Figs. 1 to 3 of swinging down the first section 3 by means of a combination of a separate floating vessel 14 in the form of a simple balloon and a wire 19 is only one possible embodiment of the procedure. The separate floating vessel 14 could be used alone and could be in the form of a pontoon possibly in combination with a ballast tank, that is, a pontoon being itself a ballast tank or a pontoon combined with a separate ballast tank. Furthermore, the wire 19 could be used alone and/or could be extended between the first section 3 and the separate floating vessel 14 or any other suitable floating vessel or any other suitable structure, such as also, for instance, the vessel 13. The separate floating vessel 14 could therefore also be located floating above the first section 3 of the tower 2.
In Fig. 4, the lower end 5 of the first section 3 of the tower has been secured to the pre-established foundation 18. In order to control the height position of the first section 3 accurately during attachment of the lower end 5 to the foundation 18, the vessel 13 may utilize a not shown ballast tank to take in or pump out ballast water. However, waves on the sea may result in up- and down movements of the first section 3 of the tower during attachment of the first section 3 to the pre-established foundation 18. In order to avoid such movements, the first section 3 may by means of said ballast tank be lowered until a certain distance remains between the first section 3 and the foundation 18, and the first section 3 may then be pulled the last distance to the foundation 18 by means of a wire drive or the like established between the first section 3 and the foundation 18.
In Fig. 5, the second section 4 of the tower 2 is being erected by means of the wire 19 that is rolled in again by means of the above-mentioned not shown wire drive, whereby the second section 4 swings about the hinge axis 10.
As it may be seen in Figs. 5 and 6, the erection of the second section 4 of the tower is assisted by means of a second wire 22 that connects a point 23 at the middle of the second section 4 and the vessel 13. The second wire 22 is rolled out from the vessel 13 by means of a not shown wire drive. Thereby, the second wire 22 counteracts the upward swinging of the second section 4, so that a too fast motion is avoided. Naturally, the second section 4 of the tower could alternatively be erected by means of the wires 19, 22 shown and/or other wires, whereby the wires employed for the erection could be connected to any other suitable floating or non-floating vessels or structures than those illustrated in the drawings.
Fig. 7 shows the tower 2 in its fully erected state, and Fig. 8 shows how the generator 15 may be lifted to the upper end 8 of the second section 4 of the tower 2 by means of a wire, possibly the second wire 22 also used for the erection of the second section 4. Fig. 9 illustrates another embodiment of the method of installation of an offshore wind turbine on the seabed according to the invention. According to this embodiment, the offshore wind turbine may be transported to its installation site and installed on the seabed by means of specially adapted floating tools 24, 25, 26, whereby the employment of conventional floating vessels such as barges or the like for carrying the wind turbine may be avoided. Fig. 9 shows the step of the method of installation, whereby the wind turbine has been transported to its installation site, and whereby the first section 3 of the tower has been swung down into the sea and is to be installed to the seabed by means of a so-called bucket foundation.
According to the method of installation illustrated in Fig. 9, a separate floating hinge tool 24 is mounted between the first section 3 and the second section 4 of the tower 2, before the tower is transported on the sea. Furthermore, a separate floating tool 25 is attached to the upper end 8 of the second section 4 of the tower.
The separate hinge tool 24 comprises a first part 27 and a second part 28 that are hingedly interconnected by means of a hinge 29. As it may be seen, the first part 27 is attached to the upper end 6 of the first section 3 of the tower 2, and the second part 28 is attached to the lower end 7 of the second section 4 of the tower. Opposite the hinge 29, either part 27, 28 of the separate hinge tool 24 is connected to either end of a hydraulic cylinder 30, respectively, whereby the separate hinge tool 24 may be operated. Alterna- tively, the separate hinge tool 24 may be operated by means of a wire drive or any other suitable drive mechanism. A further example of such drive mechanism may be a combination of a hydraulic actuator and a wire drive, whereby a wire may connect one or both ends of the hydraulic actuator to either part 27, 28, respectively, of the separate hinge tool 24. Firstly, the separate hinge tool 24 may be operated to open, whereby the first section 4 of the tower 2 may swing down into the sea to reach the position shown in Fig. 9, and secondly, it may be operated to close, whereby the second section 4 of the tower may be erected and the flanges 31 , 32 of the first and second section 3, 4, respectively, may be brought together for connection by means of not shown bolts or any other suitable means. After connection of the flanges 31 , 32, the separate hinge tool 24 may be removed from the tower 2. Similarly, after transportation of the tower to the installation site, the separate floating tool 25 may be removed from the tower 2.
According to the method of installation illustrated in Fig. 9, the separate hinge tool 24 and the separate floating tool 25 each comprises at least one pontoon and/or a ballast tank, so that the tools may carry the tower 2 on the sea and so that the swinging motion of the first section 3 of the tower down into the sea and the vertical positioning and adaptation to the tide level of the tower during installation on the seabed may be controlled. The separate hinge tool 24 may comprise at least one pontoon and/or a ballast tank in either one of the first and second part 27, 28, whereby better control of the installation procedure may be obtained.
Furthermore, Fig. 9 illustrates the employment of bucket-like structures 26 for the foundation of the first section 3 of the tower on the seabed 17. In the embodiment shown, each leg of the lattice construction of the first section 3 is provided with one bucket-like structure 26 placed with its opening facing the seabed, and, subsequently, water is pumped out from the interior of the bucket-like structures, so that these are pressed down into the seabed. By controlling the suction pressure of each bucket-like structure, respectively, during the pressing down, the correct vertical direction of the longitudinal axis of the tower may be achieved. Alternatively, one large bucket-like structure may be utilized for the foundation instead of one for each leg of the tower. The correct vertical direction of the tower may also in this manner, according to well-known techniques, be achieved by controlling the viscosity of the seabed and the friction during pressing down of the bucket-like structure. In addi- tion to this purpose of the bucket-like structures, they may also be utilized as pontoons and/or ballast tanks during swinging down into the sea of the first section 3 of the tower. During this use, their openings may be covered by a lid or the like.
Alternatively, according to the invention it is also foreseen that the separate hinge tool and/or the bucket-like structure or structures may be employed without incorporated pontoon or ballast tank and/or in combination with more conventional vessels for transportation of the wind turbine on the sea.

Claims

Claims
1. A method of installation of an offshore wind turbine (1 ) on the seabed (17), the offshore wind turbine comprising a tower (2) composed by at least a first section (3) and a second section (4), whereby the tower by means of a vessel (13) is transported to an installation location in a non-upright position of the tower, and whereby the tower (2) is raised to its upright position at the installation location, characterized by that the first section (3) and the second section (4) of the tower (2), at least during raising of the tower, are connected pivotally about a hinge axis (10), by that the first section (3) of the tower is swung about the hinge axis (10) down into the sea to its upright position when the second section (4) of the tower is still carried in a non-upright position by the vessel (13), by that the first section (3) of the tower is installed on the seabed (17), and by that, subsequently, the second section (4) of the tower is swung about the hinge axis (10) to its upright position and locked to the first section (3) of the tower in this position.
2. A method of installation of an offshore wind turbine according to claim 1 , characterized by that the first section (3) of the tower (2) is carried by a sepa- rate floating vessel (14).
3. A method of installation of an offshore wind turbine according to claim 2, characterized by that the separate floating vessel (14) comprises at least one balloon, and by that the first section (3) of the tower (2) is allowed to swing down into the sea by allowing gas to escape from the at least one balloon.
4. A method of installation of an offshore wind turbine according to claim 2, characterized by that the separate floating vessel (14) comprises at least one pontoon, and by that the first section (3) of the tower (2) is allowed to swing down into the sea by allowing ballast water to enter the at least one pontoon.
5. A method of installation of an offshore wind turbine according to claim 2, characterized by that the first section (3) of the tower (2) is allowed to swing down into the sea by rolling out a wire (19) from the separate floating vessel (14), said wire (19) carrying the first section (3) of the tower (2).
6. A method of installation of an offshore wind turbine according to claim 1 , characterized by that the first section (3) of the tower (2) is allowed to swing down into the sea by rolling out a wire (19) extended between the first and the second section of the tower.
7. A method of installation of an offshore wind turbine according to any one of the preceding claims, characterized by that, during transportation to the installation location, the hinge axis (10) of the pivotal connection (9) between the first section (3) and the second section (4) of the tower (2) is located be- tween edges of the vessel (13), so that a good balance of the vessel (13) may be obtained, and by that, before that the first section (3) of the tower is allowed to swing down into the sea, the tower (2) is displaced along the vessel (13), so that the hinge axis (10) is located over the sea, thereby enabling the first section (3) of the tower to be swung down into the sea to its upright position.
8. A method of installation of an offshore wind turbine according to any one of the preceding claims, characterized by that the second section (4) of the tower (2) is swung about the hinge axis (10) to its upright position by means of a traction wire (19) extended between the first and the second section (3, 4) of the tower and by means of a winding gear winding up the traction wire (19).
9. A method of installation of an offshore wind turbine according to any one of the preceding claims, characterized by that the first section (3) of the tower
(2) is installed on the seabed (17) by means of a so-called bucket foundation, whereby at least one bucket-like structure (26) mounted on the first section (3) of the tower (2) is placed with its opening facing the seabed (17), and by that, subsequently, water is pumped out from the interior of the at least one bucket-like structure (26), so that the bucket-like structure is pressed down into the seabed (17).
10. A method of installation of an offshore wind turbine according to claim 9, characterized by that the at least one bucket-like structure (26) is utilized as a ballast tank during the operation of swinging the first section (3) of the tower (2) down into the sea, whereby the opening of the bucket-like structure (26) is covered by a removable lid and ballast water is allowed to enter the interior of the bucket-like structure gradually through a controlled valve, and whereby the removable lid is removed from the bucket-like structure before installation of the first section of the tower on the seabed.
11. A method of installation of an offshore wind turbine according to any one of the preceding claims, characterized by that, at least during installation of the offshore wind turbine (1 ), the height position of the vessel (13) is controlled by means of pumping ballast water to or from at least one ballast tank comprised by the vessel.
12. A method of installation of an offshore wind turbine according to any one of the preceding claims, characterized by that the pivotal connection (9) between the first section (3) and the second section (4) of the tower (2) is ac- complished by means of a separate hinge tool (24) that is mounted between the first section (3) and the second section (4) of the tower (2) before raising of the tower, and by that the separate hinge tool (24) is removed from the tower after the second section (4) of the tower, in its upright position, has been locked to the first section (3) of the tower.
13. A combination of an offshore wind turbine and a floating vessel, the offshore wind turbine (1 ) comprising a tower (2) composed by at least a first section (3) and a second section (4), the floating vessel (13) being adapted to carry the tower (2) to an installation location in a non-upright position of the tower, and the tower being adapted to be raised to its upright position at the installation location, characterized in that the first section (3) and the second section (4) of the tower are adapted to, at least during raising of the tower, be connected pivotally about a hinge axis (10), in that the first section (3) of the tower is adapted to be swung about the hinge axis (10) down into the sea to its upright position when the second section (4) of the tower is still carried in a non-upright position by the floating vessel (13), and in that the second section (4) of the tower is adapted to, subsequent to installation of the first section (3) of the tower on the seabed (17), be swung about the hinge axis (10) to its upright position and locked to the first section (3) of the tower in this position.
14. A combination of an offshore wind turbine and a floating vessel according to claim 13, characterized in that the first section (3) of the tower (2) is provided with a so-called bucket foundation comprising at least one bucket-like structure (26) having an opening facing the seabed (17) in the mounting position of the first section (3) of the tower (2), and in that a pump is provided to pump water out from the interior of the at least one bucket-like structure (26), so that the bucket-like structure may be pressed down into the seabed.
15. A combination of an offshore wind turbine and a floating vessel according to claim 13 or 14, characterized in that the tower (2) is combined by a lattice tower and a tubular tower, so that the first section (3) of the tower is a lattice construction, and the second section (4) is composed by a lower lattice construction and an upper tubular construction, the lower lattice construction be- ing adapted to be connected pivotally to the first section of the tower.
16. A wind turbine (1 ) comprising a tower (2) composed by at least a first section (3) and a second section (4), the first section (3) and the second section (4) of the tower being adapted to, at least during raising of the tower, be connected pivotally about a hinge axis (10), characterized in that the wind turbine is an offshore wind turbine, in that the first section (3) of the tower (2) is provided with a so-called bucket foundation comprising at least one bucket-like structure (26) having an opening facing the seabed (17) in the mounting position of the first section (3) of the tower (2), and in that a pump is provided to pump water out from the interior of the at least one bucket-like structure (26), so that the bucket-like structure may be pressed down into the seabed.
17. A hinge tool (24) adapted to be mounted between a first section and a second section of a tower (2) of an offshore wind turbine (1 ) before raising of the tower and adapted to be removed from the tower after raising of the tower, the hinge tool (24) comprising a first hinge part (27) adapted to be mounted at an upper end (6) of the first section (3) of the tower (2) and a second hinge part (28) adapted to be mounted at a lower end (7) of the second section (4) of the tower, the first hinge part (27) and the second hinge part (28) being hingedly interconnected, and the hinge tool (24) comprising at least one pontoon, preferably in combination with a ballast tank.
18. A combination of a hinge tool according to claim 17 and a separate tool (25) adapted to be mounted on the second section (4) of the tower (2), char- acterized in that the separate tool (25) is adapted to be mounted at an upper end (8) of the second section (4) and comprises at least one pontoon, preferably in combination with a ballast tank.
PCT/EP2010/057706 2009-06-04 2010-06-02 Method of installation of an offshore wind turbine and combination of an offshore wind turbine and a floating vessel WO2010139725A1 (en)

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CN102092645A (en) * 2011-01-12 2011-06-15 大连华锐股份有限公司 Method for arranging wind power generation equipment in shallow water of intertidal zone
CN102322409A (en) * 2011-08-24 2012-01-18 三一电气有限责任公司 A kind of offshore wind turbine transportation mountion plate and luffing device thereof
CN102425145A (en) * 2011-10-27 2012-04-25 三一电气有限责任公司 Offshore wind turbine installation platform and hoisting device thereof
EP3792486A1 (en) * 2019-09-16 2021-03-17 Siemens Gamesa Renewable Energy A/S Method of offshore mounting a wind turbine
US11404854B2 (en) 2017-06-21 2022-08-02 C-Ling Limited Pull-in head assembly
US11411376B2 (en) 2017-06-21 2022-08-09 C-Ling Limited Pull-in head assembly
US11418016B2 (en) 2017-06-21 2022-08-16 C-Ling Limited Pull-in head assembly
US11473563B2 (en) 2016-09-28 2022-10-18 C-Ling Limited Annular seal member locatable against a wall element of an offshore structure

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CN102092645A (en) * 2011-01-12 2011-06-15 大连华锐股份有限公司 Method for arranging wind power generation equipment in shallow water of intertidal zone
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CN102322409A (en) * 2011-08-24 2012-01-18 三一电气有限责任公司 A kind of offshore wind turbine transportation mountion plate and luffing device thereof
CN102425145A (en) * 2011-10-27 2012-04-25 三一电气有限责任公司 Offshore wind turbine installation platform and hoisting device thereof
CN102425145B (en) * 2011-10-27 2014-01-15 三一电气有限责任公司 Offshore wind turbine installation platform and hoisting device thereof
US11473563B2 (en) 2016-09-28 2022-10-18 C-Ling Limited Annular seal member locatable against a wall element of an offshore structure
US11404854B2 (en) 2017-06-21 2022-08-02 C-Ling Limited Pull-in head assembly
US11411376B2 (en) 2017-06-21 2022-08-09 C-Ling Limited Pull-in head assembly
US11418016B2 (en) 2017-06-21 2022-08-16 C-Ling Limited Pull-in head assembly
EP3792486A1 (en) * 2019-09-16 2021-03-17 Siemens Gamesa Renewable Energy A/S Method of offshore mounting a wind turbine
WO2021052683A1 (en) * 2019-09-16 2021-03-25 Siemens Gamesa Renewable Energy A/S Method of offshore mounting a wind turbine

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