Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
  • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
  • B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
  • B63B1/107—Semi-submersibles; Small waterline area multiple hull vessels and the like, e.g. SWATH
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B77/00—Transporting or installing offshore structures on site using buoyancy forces, e.g. using semi-submersible barges, ballasting the structure or transporting of oil-and-gas platforms
  • B63B77/10—Transporting or installing offshore structures on site using buoyancy forces, e.g. using semi-submersible barges, ballasting the structure or transporting of oil-and-gas platforms specially adapted for electric power plants, e.g. wind turbines or tidal turbine generators
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
  • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
  • B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
  • B63B1/12—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected rigidly
  • B63B1/125—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected rigidly comprising more than two hulls
  • B63B2001/126—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected rigidly comprising more than two hulls comprising more than three hulls
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
  • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
  • B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
  • B63B1/12—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected rigidly
  • B63B2001/128—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected rigidly comprising underwater connectors between the hulls
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
  • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
  • B63B2035/4433—Floating structures carrying electric power plants
  • B63B2035/446—Floating structures carrying electric power plants for converting wind energy into electric energy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B75/00—Building or assembling floating offshore structures, e.g. semi-submersible platforms, SPAR platforms or wind turbine platforms
• • 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
• • 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
  • F03D13/20—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors
  • F03D13/25—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors specially adapted for offshore installation
• • 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
  • F03D13/20—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors
  • F03D13/25—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors specially adapted for offshore installation
  • F03D13/256—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors specially adapted for offshore installation on a floating support, i.e. floating wind motors
• • 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 concerns a floating power plant for converting wind energy to electrical energy.
• a floating platform including a wind generator for being moored at sea in a stable position and orientation.
• the wind power plant comprises a semi-submersible platform.
• a wind turbine comprises a rotating machine which converts the kinetic energy from the wind into mechanical energy that is then converted to electric energy.
• Wind turbines have been developed for land-based installations as well as offshore installations. The land-based wind turbines are fixed to the ground and located in windy areas. Most common wind turbines have the main rotor shaft arranged horizontally. They have a horizontal rotor shaft that is pointed into the wind. Horizontal axis wind turbines generally have a tower and an electrical generator coupled to the top of the tower. The generator may be coupled directly or via a gearbox to the hub assembly and turbine blades.
• Wind turbines have also been used for offshore applications.
• Single long tower offshore systems are mounted into the sea bed. They are normally limited to shallow water depths up to 30 meters. By using a wider base, such as a framework structure for better stability, the shallow depth requirement may be extended but only marginally. In deeper water only floating systems are expected to be economically feasible.
• Shallow water resources are limited and represent only a fraction of the offshore wind resources.
• Wind turbines close to shore may also block the shore view and create navigational obstructions and potential hazards for water vessels and aircrafts.
• Spars Spars
• Tension Leg Platforms (TLP) Tension Leg Platforms
• semi-submersible systems There are known a plurality of concepts for offshore floating wind turbine platforms. Generally, these fall into three main categories: Spars; Tension Leg Platforms (TLP); and semi-submersible systems.
• Spars comprise elongated structures that are balanced with significant ballast at the bottom of the structure and buoyant tanks near the waterline. For stability purposes, the centre of gravity must be lower than the centre of buoyancy. This will insure that the spar will float upright.
• the spar is moored to the sea bottom with a plurality of anchored lines that hold the spar in position.
• spar type structures have good heave performance due to reduced response to vertical wave exciting forces. They require substantial depth, especially when wind turbine weight increase, in order to lower the centre of gravity. Spars are complicated to install due to their draught.
• a Tension Leg Platform has vertically tensioned cables or steel pipes that connect the floater directly to the bottom of the sea. There is no requirement for a low centre of gravity for stability. Only during the installation phase buoyancy modules may be temporarily added to provide sufficient stability. The TLP have very good heave and angular motions. Due to complexity of structure and the mooring installation the costs may escalate by size. Also the change in tendon tension due to tidal variations and the structural frequency coupling between the tower and the mooring system are major hurdles. TLPs have low stability before tendon connection and a very expensive anchor arrangement.
• a semi-submersible system comprises a wind generator carrying tower on a stabilizing submerged structure which is kept in balance by a plurality of buoyancy elements penetrating the sea surface.
• the wind power generation device comprises a wind power generator and a floating body. Further the device comprises a first column which is located on the upwind side of a primary wind direction and whereupon the wind power generator is installed. A second column and a third column which are located on the further downwind side of the primary wind direction than the first column is connected to the first column with two rower hulls to the first column. A plurality of mooring cables connects the floating body to anchors. At least two of the plurality of mooring cables is connected to the first column. At least one of the pluralities of mooring cables is respectively connected to the second column and the third column. Each of the plurality of mooring cables is positioned extending in radiating directions from the floating body so as not to intersect in planar view.
• the floating wind turbine platform includes a floatation frame that includes three columns that are coupled to each other with horizontal main beams.
• a wind turbine tower is mounted above a tower support column to simplify the system construction and improve the structural strength.
• the turbine blades are coupled to a nacelle that rotates on top of the tower.
• the turbine's gearbox generator and other electrical gear can be mounted either traditionally in the nacelle, or lower in the tower or in the top of the towersupporting column.
• the floatation frame includes a water ballasting system that pumps water between the columns to keep the tower in a vertical alignment regardless of the wind speed. Water-entrapment plates are mounted to the bottoms of the columns to minimize the rotational movement of the floatation frame due to waves.
• the platform is connected to seabed by anchor lines from each column.
• a primary object of the present invention is to seek ways to improve a floating wind power plant.
• a second object of the invention is to provide a light weight floating wind power platform comprising a tower and a plurality of arms, each connected to a float, for stabilizing the tower.
• each stabilizing arm of the floating wind power platform comprises a lightweight construction consisting of two kinds of building elements only.
• the first kind is a tensile resisting element designed to resist or transmit tensile forces in its longitudinal direction.
• the second kind is a pressure resisting element designed to resist or transmit pressure forces in its longitudinal direction.
• a tension resisting element consists of a catenary element.
• catenary is understood a curve assumed by a cord of uniform density and cross section that is perfectly flexible but not capable of being stretched and that hangs freely from two fixed points. Thus a catenary element is a slim element that would collapse when exposed to pressure forces.
• Examples of the first kind are cable, wire, rope, cord etc.
• a tensile resisting element is denoted a catenary element.
• Examples of the second kind are strut, brace, stick, beam, framework construction etc.
• a pressure resisting element is denoted a strut element.
• a strut element is understood a structural piece designed to resist pressure in the direction of its length.
• triangular constructions may be designed where part of the tower comprises one of the triangle arms.
• the other arms are a strut element and a catenary element.
• Such constructions are capable of withstanding severe forces in the plane of the triangle.
• two such triangles where one arm is a strut element common to both triangles great stability is achieved and great forces may be withstood.
• the lightweight elements may be used to build big constructions yet stable enough to withstand big forces.
• a stabilizing arm consists of a first and second catenary element and a strut element positioned between the catenary elements.
• the strut element is connected between a stabilizing float and a main position of the tower.
• the first catenary element is connected between the float and a first position of the tower.
• the second catenary element is connected between the float and a second position of the tower.
• the first and second catenary element may be connected to the secondary float in positions on either side of the strut element.
• the main position is arranged between the first position and the second position.
• the construction may resemble a mast on a sailing boat where the mast is supported by two prestressed stays or shrouds. However in the present embodiment the mast is aligned horizontally and the wires are prestressed against the tower.
• the strut element comprises a framework construction which results in the arm construction being an extremely lightweight construction.
• connection points comprise two rotational degrees of freedom (2RDOF).
• 2RDOF rotational degrees of freedom
• the second and third connection points also provide 2RDOF.
• the arm construction offers 1 RDOF.
• the arm construction may be seen as a hinged door that is stable in one direction and swingable in its transversal direction.
• the plurality of arms is equally connected to the tower and symmetrically spread around the tower by a connection wire.
• connection wire connects a secondary float of an arm to a secondary float of an adjacent arm.
• connection wire comprises two connecting lines arranged in parallel with each other.
• All three arms are one-dimensionally connected to the tower like hinged doors. This means that the arms can freely rotate around the tower. To prevent the tower from rotation relative to the arms the tower is locked to one of the arms.
• the second catenary element of one arm is split into two catenary elements which are connected transversally to either side of the bottom of the tower. This means that one of the stabilizing arms will prevent the tower to rotate in relation to the other arms.
• the second catenary element is attach to the tower with a wire span which is transversally attached to each sides of the tower.
• the floating wind power platform comprises a tower and a plurality of stabilizing arms.
• the tower comprises a hollow structure carrying a pivotal nacelle and includes a main float at its lower end.
• the tower is partly a framework structure.
• the tower comprises a narrow cylindric part penetrating the water surface.
• Each arm comprises a secondary float connected to its distal end.
• the main float is preferably designed to carry the tower and its equipment as well as the generator and rotor.
• An immersed operation position of the platform may be achieved by pumping water into the main float.
• each secondary float needs only to carry its own weight and part of the stabilizing arm.
• the arm may be balanced to achieve the same tension forces in the first and the second catenary element at a normal operating position of the platform.
• the strut element comprises a lattice girder or a framework construction.
• the main task of the strut element is to withstand pressure forces it must also withstand forces from the waves. It is therefore favourable to design the strut elements with a minimum exposed area, such as a framework construction with moderate diameters of tube elements.
• the strut element is made of metal such as steel and protected against oxidation and fouling by a protective paint.
• the strut element is made of a tubular hollow structure.
• the catenary elements are suitably made of metal such as steel but may also be made of synthetic fibres. Suitable reinforcement material may be coal fibres, synthetic fibres such as for instance aromatic polyamide, etc.
• the wind power platform comprises a semisubmersible platform.
• the platform comprises the tower including the main float and three stabilising arms having secondary floats. Every float comprises a water fillable container thus making the platform immersible by filling water into the floats.
• the secondary float comprises a hollow column of arbitrary cross section. In an embodiment each secondary float comprises an elongated cylindric body having a small cross section to decrease the movement in the sea.
• the platform By pumping out ballast water from the floats the platform will float in a high position during transport. This ensures the possibility for the platform to be moored to a quay and transported in shallow water.
• the platform On the site of operation the platform is docked to an existing mooring system.
• the platform By partly filling the floats with ballast water the platform will immerse and take its operation position.
• the strut elements in the operating position will be located under the sea surface and only the tower and the upper parts of the three secondary floats may be seen.
• the platform is immersed in the sea to an operating level. This is accomplished by filling water into the main float and the secondary floats.
• the volume of the secondary floats is such that it only needs to be partly filled to reach the operational position. However it needs to be elongated enough in the vertical direction to protrude through the water surface.
• the function of the secondary float makes use of Archimedes principle. Thus when moving downwards it will experience an upwardly directed force equal to the volume of the displaced water. When moving upwards it will experience a downwardly directed force equal to the volume of the non-displaced water. Since the three arms are symmetrically spread around the tower there will be an equal amount of stabilizing forces on opposite sides of the tower.
• the floats on the leeward side will exert an uprising force and simultaneously the floats on the upwind side will exert a traction force
• the floats on each side of the tower will exert opposite forces resulting in a pivoting effect which will put the tower in an upright position.
• the necessary stabilizing force for keeping the tower in an upright position is thus provided by the length of the strut element and the cross-sectional area of the secondary float.
• Cross-sectional area is the imprint of the secondary float in the sea. A longer arm and a greater cross-sectional area of the floats will increase the uprising forces. A big cross-sectional area will however make the float more affected by the wave motion.
• a small cross-sectional area is desirable.
• a cross section width being a fraction of the length of the secondary float. In an operating position the assembled cross- sectional areas of the secondary floats are minimized in order to lower the rocking frequency.
• the aim is to lower the frequency of the stabilizing forces caused by the waves. This is accomplished by minimizing the cross section area of the secondary floats.
• a small cross section area has a lower spring constant than a large cross section area.
• the ratio between the cross section width and the length of the secondary float is in the range of 6-20 %.
• the arm When decreasing the cross-sectional area of the secondary float the arm needs to be longer. However a longer arm will increase in weight and make the platform heavier. According to the invention a fair compromise is to make the arm approximately as long as the tower is high.
• the float comprises a cylindrical shape.
• the float comprises a conical or a funnel shape. In the latter case the cross-sectional area will increase by the immersion of the float and thus resulting in a non-linear increasing fore. Such design will effectively act as damping.
• one or two of the stabilizing arms may be folded in the horizontal plane to make the platform suitable for docking a quay. It is a feature of the invention that the tower can be brought very close to the quay which facilitate lifting, mounting and replacement of the heavy tower top and nacelle from land-based services.
• One connection wire may be loosened whereby one of the arms can be rotated or folded horizontally to make two arms in 180 degrees with each other and thus permit the tower section of the platform to get close to the quay while still stably floating. If the quay is short the folded arm may be folded further than 180 degrees. In an embodiment all arms are assembled in quadrant. The necessary length of the quay will the be equal to the length of an arm. When transported temporary floats and beams may be attached to the platform.
• a semi-submersible wind power platform having a tower carrying a wind generator housed in a nacelle and a plurality of arms, the tower comprising a main float and each arm comprising a secondary float to stabilize the tower.
• Each arm consists of a strut element connected between the tower in a main position and the secondary float, a first catenary element connected between the float and a first position of the tower, and a second catenary element connected between the float and a second position of the tower.
• the secondary floats comprises elongated water fillable containers having small cross section area, that the first, second and main connection point are aligned on a common axis to make the arms swingable like hinged doors, that the tower is fixed to one of the arms, that the tension resisting element comprises a catenary element and that the pressure resisting element comprises a strut element, and that the secondary floats comprises docking mean to be moored at a mooring facility at sea.
• the object is achieved by a method of building a semisubmersible wind power platform having a tower carrying a wind generator housed in a nacelle and a plurality of arms, the tower comprising a main float and each arm comprising a secondary float to stabilize the tower.
• the method comprising providing between the tower and the secondary float a first catenary element, a second catenary element, and between the first and second catenary elements a strut element, to form with part of the tower an arm.
• the method further comprises attaching the strut element between the secondary float and the tower in a main position, attaching the first catenary element between the secondary float and the tower in a first position, attaching second catenary element between the secondary float and the tower in a second position, and aligning the main connection point, the first connection point and the second connection point on a common axis, whereby the arm being swingable attached to the tower.
• the object is achieved by a method of docking a semi-submersible wind power platform to a quay for maintenance.
• the method comprising emptying water from the main float and the secondary floats thereby raising the platform to assume a transport level in the sea, transporting the platform by tug boats to a harbour facility, adjusting the connection wire to swing the arms to resume a straight line, and mooring the platform to the quay whereby the tower come close to the quay.
• fig 1. is a side view of a floating wind power platform according to an embodiment of the invention
• fig 2. is a plan view of the floating wind power platform
• fig 3. Is an embodiment of the docking means.
• a floating wind power platform 17 is shown in fig 1 and 2.
• the platform comprises a tower 1 carrying a wind generator housed in a pivotal nacelle 2.
• the generator comprises a hub 3 with a rotor having a plurality of blades 4.
• the rotor shown has three blades but according to the invention there may be any number of blades.
• the platform further comprises a plurality of stabilizing arms 6 each connected to a secondary float 12.
• the tower comprises a main float 5.
• Each arm consists of a strut element 7, a first catenary element 8 and a second catenary element 9.
• the strut element comprises a framework element and the catenary elements comprise a wire.
• the first catenary element 8 and the second catenary element 9 are pre-stressed to achieve a play-free or slack-free arm construction.
• the arm design is very stable in the vertical direction where the stabilizing forces is transferred but allow the arms to be swingable around the tower like hinged constructions. This stability is achieved by just one strut element, the framework, and two catenary elements, the wires.
• the strut element is attached to the tower in a main connection point 10.
• the secondary float 12 is attached to the distal end 11 of the strut element.
• the first catenary element 8 is connected between the secondary float 12 and the tower in a first connection point 13.
• the second catenary element is connected between the secondary float 12 and the tower in a second connection point 14.
• the main connection point 10 is located on the tower between the first connection point 13 and the second connection point 14.
• the strut element is connected to the secondary float between the connection point of the first and second catenary elements.
• the buoyant force may be balanced between the main float 5 and the three secondary floats 12. In the semi-submerged state the framework element and the second catenary element will be positioned under the water surface A. Only part of the first catenary element and part of the secondary float will be seen above the water surface positioned above the main connection point 10.
• the secondary floats 12 comprise an elongated body structure. To keep the natural frequency of the platform low the cross- sectional area of the secondary float 12 must be kept to a fraction of the length of the secondary float.
• the centre part 31 of the secondary float comprises an elongated cylinder having a cross section in the range of 6-20 % of the length of the secondary float.
• the mid portion of the tower may comprise a small cross section area to help lower the rolling frequency of the platform.
• the upper end of the secondary float 12 may comprise a funnel shaped body 32. This funnel shaped body exerts a damping effect when moving in sea heave.
• the lower end of the secondary float comprises a cylindric body 33.
• This body also exert a damping effect but also a convenient container to fill or pump out water for balancing purposes.
• the cylindric body 33 is positioned eccentric to the centre part of the secondary float. By this eccentricity the buoyancy force of the cylindric body 33 may help increasing the upraising stability of the secondary float.
• the three arms 6a, 6b and 6c are aligned symmetrically around the tower 1.
• the arm design is stable in the vertical direction where the stabilizing forces must be transferred. This stability is achieved with one pressure force resisting element, the strut element, and two catenary elements, the wires.
• the buoyant force may be balanced between the main float 5 and the three secondary floats 12.
• By increasing an air portion in the secondary float the arm will exert a lifting force that will increase the stress of the first wire.
• the platform In a semi-submerged operating position the platform is immersed by increasing the water ballast of the floats.
• part of the framework strut element and the second catenary element will be positioned under the water surface A.
• the secondary float 12 is moored to a mooring buoy 19 which is anchored with a cable 24 to an anchor (not shown).
• the cable may be connected to the mooring buoy with a span arrangement 23.
• two of the secondary floats 12 are moored to a pair of buoys 19 associated to a docking system.
• the dockable buoy comprises a lower body 22 with a water ballast compartment and an upper body 21 comprising docking means.
• the pair of buoys are anchored with a plurality of anchor lines 24 connected to the pair of buoys.
• the two buoys are held together by a distance wire 25.
• a secondary float 30 of an arbitrary semisubmerged platform comprises a first docking means 34 suitable to mate with a second docking means 35 of the mooring buoy 19 to form a unity float.
• the secondary 30 float In a first docking process the secondary 30 float is being raised by emptying water from an internal cavity of the secondary float.
• the secondary float 30 In a second process the secondary float 30 is being aligned in front of the mooring buoy 19.
• the secondary float is being immersed by filling water into the inner cavity simultaneously as an inner cavity of the mooring buoy is emptied from water. Thereby the first 34 and second docking means 35 are hooked together and form an entity.
• a submerged platform where only necessary parts penetrate the water surface is therefore beneficial to reduce slamming forces caused by waves.
• the first float and the major part of the arms are positioned under water and only the tower and the three secondary floats break the water surface. By keeping all these protruding structures small in horizontal cross section the whole platform will act calmly in the sea.
• the framework structure of the strut element reduces slamming forces caused by waves when the strut element temporary is at water surface in heavy sea states.
• the platform For transport the platform is raised to a float position by emptying ballast water from the floats. In a transporting position all floats will be filled with air and the platform will rise to a level in the sea indicated by a dashed line B in fig 1.
• the arms should be connected to a common centre axis C of the tower. Then the arm would be freely rotatable around the tower. Achieving such connections can be made with a swivel construction well known to a person skilled in the art.
• the three arms are connected with connection wires 15 that holds the three arms equally spread around the tower.
• the connection wires comprise a plurality of wires preferably arranged in parallel with each other. However the tower can still rotate relatively to the arms. In the embodiment shown the tower is rotationally fixed to one arm.
• the lower catenary element 9 of arm 6a is split into a first lower catenary element 9a and a second lower catenary element 9b connected transversally on either side of the first float 5.
• the tower rotating preventing arrangement may also comprise a span means between the end of the arm and the first float.
• connection wires 15 can be detached and adjusted to facilitate a temporary angular rotation of the arms.
• two adjacent arms would resume a straight line which makes possible the tower coming close to a quay.
• two arms may be folded further to form a preferably perpendicular angle with the first arm.
• the diameter of the rotor may be 220 m.
• the total height of the tower including the first float may be 170 m.
• the length of the arm may be in the range of 85-120 m. Hence the ratio between the arm and the tower would almost a half.
• the length of the secondary floats may be in the range of 30-50 m and the cross section may be in the range of 2-3 m.
• the transport position of the platform is about 20 m higher that the submerged position.
• the draught of the platform under transport may be less than 10 meters.
• the wires may comprise any kind of material with good tensile properties.
• the secondary floats may comprise a landing pad for a helicopter.
• the framework strut element may comprise a footbridge.
• the platform may arbitrary be moored in a traditionally way by a plurality of anchors and anchor lines.
• the tower may contain a transformer, HVDC equipment and/or other electrical equipment.

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Family Cites Families (14)

• 2020
  • 2020-11-04 SE SE2000206A patent/SE546025C2/en unknown
• 2021
  • 2021-11-04 WO PCT/SE2021/051103 patent/WO2022098286A1/en unknown
  • 2021-11-04 EP EP21889717.1A patent/EP4240965A1/de active Pending

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