DK201800518A1

DK201800518A1 - A method of installing a crane on a portion of an offshore wind turbine generator and a vessel therefor

Info

Publication number: DK201800518A1
Application number: DKPA201800518A
Authority: DK
Inventors: Andersen Gad Jens; Melgaard Allan; Budde Frederik; Forné Peter
Original assignee: Maersk Supply Service A/S
Priority date: 2018-08-31
Filing date: 2018-08-31
Publication date: 2020-05-12
Also published as: WO2020043254A1

Abstract

A method of installing at least one portion of a crane on a portion of an offshore wind turbine generator from a vessel having a crane support structure, the method comprises suspending the portion of the crane in the support structure above the vessel. The method comprises compensating for relative motion between the portion of the offshore wind turbine generator and the vessel such the suspended portion of the crane is stable relative to the portion of the offshore wind turbine. The method also comprises transferring the suspended portion of the crane between the vessel and the portion of the offshore wind turbine.

Description

A method of installing a crane on a portion of an offshore wind turbine generator and a vessel therefor

The present invention relates to a method of installing a crane on a portion of an offshore wind turbine generator and a vessel therefor.

In order to reduce the dependence on limited fossil fuel resources around the world, there has been an increasing demand for renewable energy generation. One such source of renewable energy that has become increasingly reliable is wind energy generation.

Typically electricity is generated from the wind with wind turbine generators (WTG) installed in locations with a reliable prevailing wind. Some wind turbine generators have been installed on land in windy areas such as on hilltops. Wind turbine generators installed on land are also known as “onshore” wind turbine generators.

In recent times, the trend has been to install bigger and taller wind turbines. This increases the area that the blades of the wind turbine sweep through and increases the total potential energy production. In addition, by positioning the blades higher into the atmosphere, the wind blows more steadily, and the wind turbine blades are further from objects that may cause turbulent airflow.

The feasibility of the construction of onshore wind turbine generators can be affected by the local population objecting to the noise and other environmental impact. Accordingly, larger wind turbine generators can be installed in coastal waters. Wind turbine generators installed in coastal waters, the sea or deep ocean are also known as “offshore” wind turbine generators.

The complexity of installing offshore wind turbine generators is greatly increased with respect to installing onshore wind turbine generators. For example, the materials and structure of the offshore wind turbine generators must be transported to the installation site with a suitable vessel. Furthermore, the offshore wind turbine generator must be anchored securely in position.

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In this way, offshore wind turbine generator installation is typically carried out in separate stages. One current method of installation is to anchor a foundation to the seabed using a monopile foundation. This is a steel and / or concrete tube which is fixed to and protrudes from the seabed. A transition piece (TP) is fixed to the monopile foundation and the transition piece projects out of the water. The offshore wind turbine generator is then fixed to the transition piece.

WO2014/070024 discloses a method of installing an offshore wind turbine generator is using a jack-up vessel. The jack-up vessel comprises legs that extend down to and engage with the seabed. The jack-up vessel comprises a crane sufficiently tall to receive and install pre-assembled offshore wind turbine generators to the transition piece. A problem with a jack-up vessel is that not all types of seabed are suitable for receiving the extended legs which means this vessel cannot be operated in all coastal waters. Furthermore, the jack-up vessel is very sensitive to adverse weather which means operation of the jackup vessel is restricted to calm weather windows.

WO2007/091042 discloses an alternative method of installing an offshore wind turbine generator using a crane mounted on a vessel. In order to install the largest wind turbine generators, the crane must be suitably massive. Similar to a jack-up vessel, a crane mounted vessel is also sensitive to adverse weather conditions during operation. Another problem is that the vessel must not collide with the foundation or transition piece and this means that the vessel must operate at a safe distance. This means the height of the crane is increased even further so that the crane has sufficient outreach whilst the vessel is positioned at a safe distance from the transition piece.

Another alternative method of offshore wind turbine generator installation is contemplated in WO2017/055598. This discloses installing separate parts of a wind turbine generator with a crane mounted to part of the tower. The crane is initially winched onto the tower from a barge. A problem with this arrangement is that the cable must be pre-attached to the tower in order for the crane to be winched onto the tower. This means that the vessel must be in close proximity

DK 2018 00518 A1 to the foundation and transition piece because otherwise the crane will be immersed in water during the winching operation

It is undesirable for the vessel to be in immediate proximity of the foundation piece for a protracted period of time because this increases the risk of collision of the vessel with the foundation and transition piece. Furthermore, during the final stage of the winching, the crane can swing against the foundation piece. This means that the foundation can become damaged when the crane hits the tower. Alternatively, the impact can damage the eyes or the climbing mechanism which would render the crane inoperable.

Embodiments of the present invention aim to address the aforementioned problems.

According to an aspect of the present invention there is a method of installing at least one portion of a crane on a portion of an offshore wind turbine generator from a vessel having a crane support structure, the method comprising: suspending the portion of the crane in the support structure above the vessel; compensating for relative motion between the portion of the offshore wind turbine generator and the vessel such the suspended portion of the crane is stable relative to the portion of the offshore wind turbine; and transferring the suspended portion of the crane between the vessel and the portion of the offshore wind turbine.

Optionally, the method comprises determining the distance and position of the vessel with respect to the portion of the offshore wind turbine.

Optionally, the compensating comprises maintaining the vessel at a fixed distance and position from the portion of the offshore wind turbine generator based on the determined distance.

Optionally, the compensating comprises determining the relative motion of the portion of the crane with respect to the vessel and / or the portion of the offshore wind turbine generator.

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Optionally, the compensating comprises adjusting the position of the portion of the crane with respect to the vessel and / or the offshore wind turbine generator in one or more directions to compensate for heave, sway, surge, roll, pitch and / or yaw motion of the vessel.

Optionally, the compensating comprises adjusting a moveable actuator of the support structure coupled to a motion compensation platform with respect to the vessel.

Optionally, the compensating comprises adjusting the position and / or orientation of one or more coupling actuators with respect to vessel, wherein the one or more coupling actuators are mounted between the crane and the support structure fixed to the vessel.

Optionally, the compensating comprises adjusting the position of the crane with respect the vessel by moving one or more moveable actuators coupled to one or more adjustable arms of the support structure, wherein the adjustable arms are coupled between the vessel and the portion of the crane.

Optionally, the adjustable arms are extendable and / or pivotable with respect to the vessel.

Optionally, the adjustable arms are independently controllable.

Optionally, a first adjustable arm releasably engages the portion of the crane on a first side and a second adjustable arm releasably engages the portion of the crane on a second side.

Optionally, the method comprises securing the portion of the crane to the portion of the offshore wind turbine.

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Optionally, the securing comprises closing one or more moveable doors hinged on a body of the portion of the crane around the portion of the offshore wind turbine generator.

Optionally, the securing comprises engaging a coupler mounted on the portion of the crane with an external protrusion of the portion of the offshore wind turbine generator.

Optionally, the securing comprises suspending the portion of the crane from cables from the portion of the offshore wind turbine generator.

Optionally, the step of suspending the portion of the crane above the vessel comprises elevating the crane from a first position where the crane is adjacent to a deck of the vessel and to a second position wherein the crane is suspended above the deck of the vessel.

Optionally, the at least a portion of the crane comprises one or more portions of a tower crane.

Optionally, the support structure is transferred to the wind turbine generator together with the at least one portion of the crane.

In another aspect of the invention there is provided, a vessel comprising: a support structure mounted on a vessel for suspending and transferring a portion of crane installable on a portion of an offshore wind turbine generator; at least one moveable actuator coupled to the support structure and arranged to move the suspended portion of the crane to compensate for relative motion between the portion of the offshore wind turbine generator and the vessel such the portion of the crane is stable relative to the portion of the offshore wind turbine.

Optionally, the support structure comprises a first adjustable arm engageable with the portion of the crane on a first side and a second adjustable arm engageable with the portion of the crane on a second side.

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Various other aspects and further embodiments are also described in the following detailed description and in the attached claims with reference to the accompanying drawings, in which:

Figure 1 shows a side view of a vessel in the proximity of a wind turbine generator;

Figure 2 shows a schematic perspective view of a vessel;

Figure 3 shows a side view of a vessel with a crane in a first position according to an embodiment;

Figure 4 shows a side view of a vessel with a crane in a second position according to an embodiment;

Figure 5 shows a close up perspective view of the crane in a first position according to an embodiment;

Figure 6 shows a side view of a vessel with a crane in a first position according to an embodiment;

Figure 7 shows a side view of a vessel with a crane in a second position according to an embodiment;

Figure 8 shows a side view of a vessel with a crane according to an embodiment;

Figure 9 shows a schematic plan view a vessel with a crane according to an embodiment;

Figure 10 shows a schematic view of a vessel;

Figure 11 shows a flow diagram of a method of installing a crane on a portion of an offshore wind turbine generator;

Figure 12 shows a perspective view of a vessel with a crane according to an embodiment;

Figure 13 shows a perspective view of a vessel with a crane according to an embodiment;

Figure 14 shows a perspective view of a vessel with a crane according to an embodiment and

Figure 15 shows a perspective view of a crane mounted on a vessel according to an embodiment;

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Figure 16 shows a perspective view of a crane mounted on a vessel according to an embodiment; and

Figure 17 shows a perspective view of a crane mounted on a portion of a wind turbine generator according to an embodiment.

Figure 1 shows a side view of a vessel 100 in the proximity of a wind turbine generator (WTG) 102. For the purposes of clarity, the WTG 102 is not drawn to scale and the broken portions of the WTG 102 represent missing portions of the WTG 102. The WTG 102 comprises a foundation 104 anchored to the seabed 106. The foundation 104 is a steel and / or concrete tube which is fixed to and protrudes from the seabed 106. Typically the foundation 104 engages with the seabed 106, but in some embodiments the foundation can be floating where the ocean is particularly deep. In other embodiments, other types of foundation 104 can be used including, but not limited to: monopile foundations, tripod foundations, jacket foundations, space-type foundations, floating foundations and / or gravity-based structure foundations.

A transition piece (TP) 108 is fixed to the monopile foundation 104 and the transition piece 108 projects out from the surface of the water 110. The transition piece 108 comprises access ladders (not shown) for access to the WTG 102 from a boat. The transition piece 108 further comprises a platform 112 and a door 114 for internal access to the WTG 102.

The WTG 102 comprises a tower 116 which is fixed to the transition piece 108. The tower 116 can be a unitary element or can be constructed from a plurality of tower segments. A nacelle 118 is rotatably mounted on the top of the tower 116. The nacelle 118 can rotate about the vertical axis A-A of the tower 116. The nacelle 118 houses a generator (not shown) for converting the rotation of a hub 120 and blades 122 into electrical energy. There may a plurality of blades 122 connected to the hub. The generator is connected to an electrical substation via one or more cables (not shown). Access to the nacelle 118 can be achieved via an internal set of stairs (not shown).

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Each of the elements of the WTG 102 is installed with the vessel 100, which will be described in further detail below.

The vessel 100 as shown in Figure 1 is a subsea supply vessel. In other embodiments the vessel is another type of vessel including but not limited to an anchor handling tug supply (AHTS) vessel, a platform supply vessel (PSV), multipurpose support vessel (MSV), a tug boat, a barge or any other suitable vessel for installing WTGs 102.

The vessel 100 can be used for various marine operations such as anchor handling, towing, supply of offshore installations, and fire-fighting. The vessel 100 comprises one or more winches (not shown) for handling towlines and anchors of offshore installations such as oil rigs. The vessel 100 comprises an open aft portion 124 for storing and managing anchors.

In some embodiments, the aft portion 124 is used for stowing one or more parts of the WTG 102. In some embodiments, the aft portion 124 can be used to store disassembled parts 302, 304, 306 of the tower 116 (as shown in Figure 3), the nacelle 118, the hub 120 and / or the blades 122. In other embodiments, disassembled parts of the WTG 102 can be stowed on a separate vessel (not shown) such as a barge which is positioned close to the vessel 100 when the WTG 102 is being installed.

Figure 1 shows that the open aft portion 124 is clear from anchors and towlines for the purposes of clarity. The open aft portion 124 may comprise one or more cranes (not shown) fixed to the structure of the vessel 100 for lifting and moving objects. The vessel 100 can use the winch together with a towline for towing the barge or other floating structures, if required. Alternatively, the towline can be attached to a capstan or bollard secured to the deck 334 of the vessel 100 when towing the barge. The method of towing barges with a towline and vessel is known and will not be discussed in any further detail.

The vessel 100 comprises a plurality of propulsors for moving the vessel 100 through the water. In some embodiments, the propulsors are one or more of

DK 2018 00518 A1 the following: a propeller, a thruster, or an azimuth thruster. The vessel 100 can have any number or configuration of propulsors. The vessel 100 as shown in Figure 1 comprises two propellers 1002 (schematically represented in Figure 10). The propellers 1002 are both coupled to a diesel two stoke engine 1000 (schematically shown in Figure 10) or each propeller 1002 is coupled to a separate diesel two stroke engine 1000. Alternatively, the two propellers 1002 can be driven by one or more diesel four stroke engines 1000. In other embodiments, the propulsors can be powered with a diesel electric engine with or without a direct coupling. Under normal sailing, the propellers 1002 are principally used for moving the vessel 100 in a direction towards the bow 126 of the vessel 100. When the propellers 1002 are reversed, the vessel 100 will move in a direction towards the stern 128. In some embodiments, the vessel 100 only has one propeller mounted along the centreline X-X (as shown in Figure 2) of the vessel 100.

A rudder 130 is positioned aftwards of each propeller 1002 for steering the vessel 100. The rudder 130 is used for directing a wash which is a mass of water moved by the propellers 1002. Each propeller 1002 can have a nozzle which is a hollow tube that surrounds each propeller 1002 for increasing the propulsive force of the respective propellers 1002.

The vessel 100 comprises plurality of bow thrusters 132, 134, 136 and a plurality of stern thrusters 138, 140, 142. Each of the bow thrusters 132, 134, 136 and the stern thrusters 138, 140, 142 are mounted in a tunnel 144. For the purposes of clarity, only one tunnel 144 has been labelled. The tunnel 144 is a hollow tube integral with the hull 146 of the vessel 100 and is open at both sides, e.g. port side and starboard side of the hull 146. This means a thrust force can be imparted at either side of the vessel 100. The tunnel 146 which is integral with the hull 146 of the vessel 100 maintains a compact form and reduces drag on the thrusters 132, 134, 136, 138, 140, 142 when the vessel 100 is moving forwards.

The bow thrusters 132, 134, 136 and the stern thrusters 138, 140, 142 provide a side force with respect to the vessel 100. In this way, the thrusters 132, 134,

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136, 138, 140, 142 increase the manoeuvrability of the vessel 100. In some embodiments, the thrusters 132, 134, 136, 138, 140, 142 are driven by an electric motor 1004 (schematically shown in Figure 10). The electric motor 1004 is powered by a diesel engine which may be an auxiliary engine (not shown) in addition to the diesel engines 1000 driving the propellers 1002. Optionally, the electric motor 1004 can also drive the propellers 1002. Alternatively, the electric motors 1004 can be powered from the same engine 1000 which drives the propellers 1002. Additionally or alternatively, the electric motors 1004 of the thrusters 132, 134, 136, 138, 140, 142 are powered by a battery (not shown). In other embodiments, the thrusters 132, 134, 136, 138, 140, 142 are driven by a diesel engine 1000 and gearing and linkages (both not shown) couple the engine 1000 to the thrusters 132, 134, 136, 138, 140, 142. In operation, one or more thrusters 132, 134, 136, 138, 140, 142 can generate a thrust on a side of the vessel 100. All the thrusters 132, 134, 136, 138, 140, 142 can generate a thrust on the same side of the vessel 100 or on different sides of the vessel 100.

In other embodiments, one or more of the propellers 1002 or the thrusters 132, 134, 136, 138, 140, 142 are replaced with azimuth thrusters 1006 (as shown in Figure 10). The azimuth thruster 1006 is housed in a pod and is also known as an “azipod”. The azipod 1006 is rotatable by an angle (azimuth) around a horizontal plane parallel with a main horizontal plane of the vessel 100. In this way, the azipod 1006 can direct thrust in any direction. Similar to the thrusters 132, 134, 136, 138, 140, 142, the azipods 1006 can be driven by an engine 1000 or an electric motor 1004.

Turning back to Figure 1, control of the vessel 100 is achieved by manual controls 1008 such as joysticks, helm, wheel etc. (shown schematically in Figure 10) located in the bridge 148. The bridge 148 is usually located in position such that the crew members have good visibility of the vessel 100 and the surrounding sea. The bridge 148 as shown in Figure 1 has 360 degree visibility of the sea surrounding the vessel 100. This means that crew members operating the vessel 100 can safely and easily control the vessel 100 irrespective of whether the vessel 100 is moving forwards, backwards or side

DK 2018 00518 A1 to side. In other embodiments, the vessel 100 can be autonomously controlled with a dynamic positioning module 1010 and a vessel control module 1012 (as shown in Figure 10). Use of the dynamic positioning module 1010 will be discussed in further detail together with Figure 10 below.

Motion of the vessel 100 during operation will now be discussed in reference to Figure 2. Figure 2 shows a perspective schematic view of the vessel 100. The vessel 100 has three principle axis about which it can rotate, a longitudinal axis X-X, a transverse axis Y-Y, and a vertical axis Z-Z. Rotation about the longitudinal axis or centreline X-X of the vessel 100 is called roll. Rotation about the transverse axis Y-Y which is the perpendicular to the longitudinal axis X-X, is called pitch. Rotation about the vertical axis Z-Z is called yaw. In addition to rotational motion about the axes X-X, Y-Y and Z-Z, the vessel 100 can also experience translational motion along each of the axes. Translational motion about the longitudinal axis X-X, the transverse axis Y-Y and the vertical axis ZZ is respectively known as surge, sway and heave.

During operation of the vessel 100, motion compensation of the vessel 100 is carried out to compensate for one or more of roll, pitch, yaw, sway, surge, and heave. In order to compensate for the motion of the vessel 100, measurement of the motion of the vessel 100 is carried out by one or more sensors. Figure 2 schematically represents a pitch motion sensor, 200, a roll sensor 202, a yaw sensor 204, a surge sensor 206, a sway sensor 208 and a heave sensor 210.

In some embodiments, the sensors for detecting the motion of the vessel 100 can be accelerometers, gyroscopes, cameras, or any other suitable sensor for detecting motion of the vessel 100. In some embodiments, alternatively, or additionally the translation movement of the vessel 100 in a plane substantially parallel to the surface of the water is detected with a global positioning system (GPS) 1016 of the vessel 100. This means that the sway sensor 208 and the surge sensor 206 can optionally be omitted. The one or more sensors 200, 202, 204, 206, 208, 210 in some embodiments, can be one or more accelerometers for detecting motion in three perpendicular axes. In some embodiments, one or more sensors (not shown) can detect motion of the vessel 100 in all six

DK 2018 00518 A1 degrees of freedom (roll, pitch, yaw, surge, sway, heave). The sensors 200, 202, 204, 206, 208, 210 are connected to a motion compensation module 1014. The motion compensation module 1014 determines the motion of the vessel 100 due to the wind and the waves based on the received sensor information. The compensating for the motion of the vessel 100 will be described in further detail below.

Turning to Figure 3, installation of the WTG 102 will be described in further detail. Figure 3 shows a side view of a vessel 100 with a crane 300 in a first position according to an embodiment. In the first position, the crane 300 is positioned at the aftmost part of the vessel 100. In the first position, the crane 300 is mounted on the deck 334 or positioned on a platform 324 mounted on the deck 334. The crane 300 is arranged to hoist the parts of the WTG 102 during installation of the WTG 102 when mounted on the WTG 102. The crane 300 can be any suitable shape, size or form for lifting the parts of the WTG 102.

The crane 300 is mountable on a portion 308 of the WTG 102. The portion 308 of the WTG 102 is a first section 308 of the tower 116. The first section 308 has been installed and fixed to the transition piece 108 before the crane 300 is mounted on the WTG 102. In other embodiments, the crane 300 is mountable on other parts of the WTG 102 such as the transition piece 108 or the foundation 104.

The crane 300 comprises a crane body 310 engageable with the tower 116. Briefly turning to Figure 9, the crane body 310 will be described in further detail. Figure 9 shows a plan view of the crane 300. As shown in Figure 9, in some embodiments the crane body 310 optionally comprises a first door 900, and a second door 902 pivotally hinged to the crane body 310. The first and second doors 900, 902 are arranged to move between a first position in which the doors 900, 902 in an open position and a second position in which the doors 900, 902 are in a closed position. In the open position, the crane body 310 can be positioned around the tower 116. In the closed position, the crane body 310 envelops the tower 116 and secures the crane body 310 to the tower 116. In some embodiments, as discussed below one or more other mechanisms for

DK 2018 00518 A1 securing the crane body 310 to the tower 116 are additionally or alternatively used. In some other embodiments, the doors 900, 902 do not perform a securing function but instead when the doors 900, 902 are closed, the crane body 310 guides the vertical movement of the crane 300 on the WTG 102. The doors 900, 902 are actuated with hydraulic arms (not shown for clarity). The doors 900, 902 can be held together with a locking mechanism (not shown). The hydraulic arms can be connected to the vessel hydraulic system 1022.

In some other embodiments, the crane body 310 comprises a single pivotally hinged door (not shown). In other embodiments, the doors 900, 902 slide against the crane body. In yet other embodiments, the crane body 310 does not have doors. Optionally there is a strap or other securing mechanism which secures around the tower 116 when there are no doors.

The crane body 310 comprises one or more shock absorbers 904 for engaging with an external surface 906 of the tower 116. The shock absorbers 904 can be sprung mounted to absorb the impact of the crane body 310 abutting against the tower 116. In some embodiments, the shock absorbers 904 are sprung mounted wheels. The wheels reduce the friction between the inside surface 908 of the crane body 310 and the external surface 906 of the tower 116. Additionally or alternatively, the shock absorbers are resiliently deformable pads made from rubber or a similar material. The one or more shock absorbers 904 guide the vertical movement of the crane 300 on the WTG 102 and protect both the WTG 102 and the crane 300 from damage.

In some embodiments, when the crane body 310 surrounds the tower 116, a plurality of shock absorbers 904 engage the tower 116. Figure 9 shows three shock absorbers 904 surrounding the tower 116, however there can be any number of shock absorbers positioned on the inside surface 908 of the crane body 310. The position and orientation of the plurality of shock absorbers 904 can be in any suitable arrangement. In some embodiments, the shock absorbers 904 are arranged in a plurality of circles and each circle of shock absorbers 904 is positioned at a different height on the crane body 310.

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Turning back to Figure 3, the crane 300 will be described in further detail. The crane 300 comprises a boom 312 which is pivotally coupled to the crane body 310 at pivot 314. The crane 300 comprises one or more cables 316 which are coupled to a winch 318. The cable 316 is connected to yoke 320 for engaging with a load, such as a tower segment 302, 304, 306 to be lifted. The boom 312 projects laterally from the crane body 310 so that the load can be lifted clear from the crane body 310. In some embodiments, the boom 312 is optionally pivotally connected to an additional jib portion (not shown). The jib portion fixed to the boom 312 or is pivotally mounted to the boom 312 and increase the lateral reach of the crane 300.

In some embodiments, the crane 300 comprises a counterweight 322 positioned on the opposite side of the crane body 310 to the boom 312. In some embodiments, the counterweight 322 is a water filled container suspended from the crane body 310. In this way, the counterweight 322 is emptied of water when the crane 300 is being transferred from the vessel 100 to the WTG 102. This reduces the weight of the crane 300 during the lift operation.

As mentioned previously, the crane 300 as shown in Figure 3 is mounted in a first position on the aftmost portion of the vessel 100. The crane 300 is removably mounted on the stern 128 of the vessel 100. In some embodiments, the crane 300 is attached to the vessel 100 with quick release fixings. This means that the crane 300 can be fixed in place when the vessel 100 sails to the location of the WTG 102. Once the vessel 100 is in the proximity of the WTG 102, the crane 300 can be released from the vessel 100 and prepared for the transfer to the WTG 102. In some embodiments, the crane 300 is mounted on a moveable platform 324. The moveable platform 324 can be mounted on wheels or rails (not shown) on the deck 334 of the vessel 100. This means that the moveable platform 324 can undergo a translational movement on the deck 334 of the vessel 100. In this way, the crane 300 can be moved from a stowed position on the aft portion 124 of the vessel 100 to a transfer position at the aftmost part of the vessel 100 (as shown in Figure 3). The parts of the WTG

DK 2018 00518 A1 stowed on the vessel 100 can also be mounted on moveable platforms (not shown) to move them from a stowed position to a position ready for transfer.

The crane 300 is releasably coupled to a support structure 332 arranged to suspend the crane 300 above the deck 334 of the vessel 100 as shown in Figure 4. The support structure 332 comprises a first adjustable arm 326 which is releasably engageable to a first side of the crane 300 and a second adjustable arm 500 (better viewed from Figure 5) releasably engageable to a second side of the crane 300.

The first and second adjustable arms 326, 500 (as shown in Figure 5) are moveably mountable to the platform 324. In other embodiments, the adjustable arm 326 is moveably mounted on the vessel 100. In some embodiments, the adjustable arms 326, 500 are each pivotally mountable with first and second orthogonal pivoting joints 508. In other embodiments, the adjustable arms are mounted in ball and socket joints. In yet other embodiments the adjustable arms 326, 500 can be moveably mounted using any suitable mechanism for permitting multiple degrees of freedom.

The adjustable arms 326, 500 are configured to pivot with respect to the longitudinal axis X-X of the vessel 100. In this way, the adjustable arms 326, 500 can increase the outreach of the crane 300 as the adjustable arms 326, 500 tends towards the horizontal.

Similarly, the adjustable arms 326, 500 are configured to pivot with respect to the vertical axis Z-Z of the vessel 100. Accordingly, as the vessel 100 experiences roll or pitch in the X-X axis or Y axis respectively due to waves, the adjustable arms 326, 500 can be moved to remain upright.

Optionally, the crane body 310 comprises one or more crane couplings 502. Figure 5 shows a first crane coupling 502 mounted on a first side of the crane body 310. The opposite side of the crane body 310 comprises a second crane coupling (not shown). The first and second crane couplings 502 are configured to mount the crane 300 to the support structure 332 during the transfer

DK 2018 00518 A1 operation. In some embodiments, the first and second crane couplings 502 permit relative movement between the crane 300 and the support structure 332. In some embodiments, the crane couplings 502 permit pivotal movement of the crane 300 about the centre axis B-B of the crane couplings 502. This means that as the angle between the adjustable arms 326, 500 and the longitudinal axis X-X varies as the adjustable arms extend, the crane 300 pivots in the plane of the longitudinal axis X-X and the vertical axis Z-Z and the crane 300 remains vertical. The difference in the angle between the adjustable arms 326, 500 and the longitudinal axis X-X is visible between Figures 3 and 4.

In some embodiments, the first adjustable arm 326 and the second adjustable arm 500 are independently controllable. In this way, the first adjustable arm 326 can be moved with respect to the second adjustable arm 500. The relative movement between the first and second adjustable arms 326, 500 can be due to pivotal movement or extension of the telescopic arms. This means that the crane 300 can be tilted and rotated due to the relative movement between the first and second adjustable arms 326, 500. Where the first and second adjustable arms 326, 500 are independently controllable, the crane couplings 502 permit movement in more than one degree of freedom. In this way, the crane couplings 502 can be ball and socket joints or a plurality of orthogonal pivoting joints.

In some other embodiments, the crane couplings 502 only permit pivoting movement along the X-X axis. Accordingly, the relative movement of crane 300 with respect to the adjustable arms 326, 500 is constrained. Instead in some embodiments, the support structure 332 is mounted on a motion compensated platform 324. This means that the roll, pitch and heave of the vessel is compensated by the platform 324. In this way, the pivoting movement of the crane 300 about axis B-B is to compensate for the change in angle of the adjustable arms 326, 500 as the adjustable arms 326, 500 extend from the first position to the second position.

Referring back to Figure 3, in some embodiments, the platform 324 is rotatable with respect to the vessel 100 about an axis parallel with the Z-Z axis of the

DK 2018 00518 A1 vessel 100. Indeed, the platform 324 comprises a rotatable bearing (not shown) mounted on the deck 334 of the vessel 100. In this way, the crane 300 can slew whilst mounted to the vessel 100.

Discussion of the method installing the crane 300 on the WTG 102 will now be discussed in reference to Figures 4, 5, 10 and 11. Figure 10 is a schematic view of the components and control systems of the vessel 100. Figure 11 is a flow diagram of the method installing the crane 300 on the WTG 102.

In order to transfer the crane 300 to the WTG 102, the crane 300 is suspended in the support structure 332. The support structure 332 will be further described in reference to Figure 4. Figure 4 is the same as the arrangement shown in Figure 3, except that the adjustable arms 326 are extended.

The adjustable arms 326 are telescopic and have extended from the first, transfer position as shown in Figure 3 to a second position in which the crane 300 is in a suspended position in Figure 4. As the adjustable arms 326, 500 extend, the crane 300 is moved closer to the tower 116. In some embodiments, the telescopic arms are hydraulically actuated. In other embodiments, the extension of the telescopic arms 326, 500 is carried out with a rack and pinion mechanism (not shown) or any other suitable mechanism. In some embodiments, the extension of the telescopic arms is controllable via a hydraulic system 1022 (as shown in Figure 10). The adjustable arms 326, 500 extend along their longitudinal axis. Optionally, the adjustable arms 326, 500 can also pivot with respect to the vessel 100.

In the suspended position, the crane 300 is ready to be mounted on the tower 116. As shown in Figure 4, the crane body 310 is surrounding the tower 116. When the crane 300 is being suspended from the support structure 332, movement of the vessel 100 from the wind and the waves are exaggerated. Optionally, the boom 312 is in a horizontal position as shown in Figure 4. Placing the boom 312 in a horizontal position can protect the crane 300 during the transfer of the crane 300 from the vessel 100 to the WTG 102. Accordingly, the doors 900, 902 of the crane body 310 have been closed and secured

DK 2018 00518 A1 together. Accordingly, the motion of the vessel 100 is compensated in order to keep the suspended crane stable relative to the tower 116. This means that the movement of the vessel due to the waves and wind does not affect the position of the crane 300 with respect to the tower 116. Instead, translational movement of the crane 300 with respect to the tower 116 is due to transferring the crane 300 from the vessel 100 to the tower 116. In this way, the translational movement of the crane 300 is with respect to the tower 116 is due to the extension of the support structure 332 or from a controlled thrust of the vessel itself required to move the crane 300 closer to the tower 116.

Accordingly the crane 300 is suspended in the support structure 332 above the vessel 100 as shown in step 1100 of Figure 11.

Compensation for relative motion between the portion of the offshore wind turbine generator 102 and the vessel 100 is then carried out as shown in step 1102 of Figure 11. Discussion of compensating the motion of the vessel 100 will now be discussed in reference to Figures 5 and 10.

Turning to Figure 10, the vessel 100 comprises a plurality of different modules for controlling one or more aspects of the vessel 100. The modules may be implemented on hardware, firmware or software operating on one or more processors or computers. A single processor can operate the different module functionalities or separate individual processors, or separate groups of processors can operate each module functionality.

The vessel 100 further comprises modules for determining parameter information relating the vessel 100. Figure 10 is a non-exhaustive list of the different control modules of a vessel 100. The vessel 100 comprises a vessel control module 1012 for controlling the movement, positioning and orientation of the vessel 100 by sending instructions to the propulsors e.g. the propellers 1002, the thrusters 132, 134, 136, 138, 140, 142 and / or azipods 1006. The vessel control module 1012 can control one or more other aspects of the vessel 100 such as the motion compensation module 1014.

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The vessel control module 1012 receives position information from a dynamic positioning module 1010. The dynamic position module 1010 receives positioning information from one or more inputs such as a global positioning system (GPS) 1016, global navigation satellite system (GLONASS) 1018, and a compass 1020 for determining the current position and heading of the vessel 100. The dynamic positioning module 1010 can receive additional positioning input information from other input sources, if required such as a WTG distance module 1026. The dynamic position module 1010 sends target position information to vessel control module 1012. The target position information received from the dynamic positioning module 1010 is position information for moving the vessel 100 from a current position to a desired target position of the vessel 100. For example, the target position information can be position information for maintaining the vessel 100 in a static position for the vessel 100 or a maintaining the vessel on a course or heading.

Additionally or alternatively, at least one beacon or 400 is placed on a surface of the WTG 102 for measuring the distance between the WTG 102 and the vessel 100 by the WTG distance module 1026. The beacon 400 can be passive and provide a surface which is better for reflecting the measurement signals e.g. light, radio waves, sound waves. In this way, the beacon 400 can be made from a reflective material such as foil. In alternative embodiments, the beacon 400 can be active and send a signal to a distance sensor 1024 for measuring the distance. The distance sensor 1024 can be a laser range finder, LIDAR, a camera, radar, sonar or any other suitable sensor for measuring distance between the vessel 100 and the WTG 102. For example, the active beacon 400 can comprises a GPS detector for determining position of the WTG 102 which is sent to the distance sensor 1024. In some embodiments, the beacon 400 can be launched from the vessel 100 to the WTG 102 using a drone, cannon or any other suitable means for delivering the beacon 400 to the WTG 102.

In some embodiments, the WTG distance module 1026 sends target position information based on the measured distance between the WTG 102 and the vessel 100. Based on the measured distance, the WTG distance module 1026

DK 2018 00518 A1 issues a command to the dynamic positioning system to move the vessel 100 to a safe operating distance. In this way, the WTG distance sensor 1024 can provide accurate distance information to the dynamic positioning module 1010 which the dynamic positioning module 1010 may not be able to determine using only information from the GPS sensor 1016.

Accordingly, the dynamic positioning module 1010 can compensate for vessel motion due to drift from the wind and the waves. That is the sway, surge and yaw motion of the vessel 100 can be compensated with use of the thrusters and propellers.

As mentioned above, the vessel 100 can also experience motion due to roll, pitch and heave from the waves. The motion compensation module 1014 moves the support structure 332 in order to compensate for the roll, pitch and heave of the vessel 100.

The support structure 332 will be discussed in more detail with reference to Figure 5. Figure 5 shows a close up perspective view of the crane 300 mounted on the vessel 100. Only the aft portion of the vessel 100 is shown for the purposes of clarity.

The support structure 332 is suspending the crane 300 above the deck 334 of the vessel 100. Indeed, the first and second adjustable arms 326, 500 are in the extended, second position. The doors 900, 902 of the crane body 310 are open so that the crane body 310 can be positioned to surround the tower 116. In comparison with Figure 4, the doors 900, 902 are in the closed position.

In some embodiments, the support structure 332 comprises at least one actuator for moving the suspended crane 300 with respect to the vessel 100. In the embodiment shown in Figure 5, there is a first actuator 328 and a second actuator 330 for moving the first adjustable arm 326. Similarly the second adjustable arm 500 comprises first and second actuators 504, 506 for moving the second adjustable arm 500. The actuators 328, 330, 504, 506 are configured to move the adjustable arms 326, 500 to compensate for the motion

DK 2018 00518 A1 of the vessel. In some embodiments, there are any number of actuators for moving the support structure 332. The actuators 328, 330, 504, 506 are hydraulically actuated extendable pistons and are coupled to the hydraulic system 1022. In some embodiments, the actuators 328, 330, 504, 506 moved by linkages and gearing or any other suitable mechanism.

The pitch, roll and heave motion of the vessel 100 is detected using the pitch motion sensor, 200, the roll sensor 202, and the heave sensor 210. The motion compensation module 1014 receives the sensor data relating to the detected motion of the vessel 100. The motion compensation module 1014 determines the deviation of the crane 300 due to the detected motion of the vessel from a stable crane position.

The stable crane position is a position whereby the movement of the vessel 100 due to the waves and wind does not affect the position of the crane 300 with respect to the tower 116. Instead, translational movement of the crane 300 with respect to the tower 116 is due to transferring the crane 300 from the vessel 100 to the tower 116. In this way, the translational movement of the crane 300 is with respect to the tower 116 is due to the extension of the support structure 332 or from a controlled thrust of the vessel 100 itself required to move the crane 300 closer to the tower 116.

In some embodiments, the motion compensation module 1014 calculates the deviation from a position of the crane suspended above the vessel at a height corresponding to the position on the WTG 102 where the crane 300 is to be transferred to. On detection of deviation from a stable crane position, the motion compensation module 1014 then sends one or more instructions to the actuators 328, 330, 504, 506 to move the crane 300 back to a stable position. In this way, the motion compensation module 1014 controls the actuators 328, 330, 504, 506 to keep the crane 300 fixed at a height with respect to the WTG 102.

Additionally or alternatively, in some embodiments, the motion compensation module 1014 generates a model of the motion of the vessel 100 over a period

DK 2018 00518 A1 time based on observed vessel motion. Accordingly, the generated model is a prediction of the motion of the vessel 100 based on recent motion on the vessel. The motion compensation model sends control instructions to the actuators 328, 330, 504, 506 based on the vessel motion model.

Additionally or alternatively, the platform 324 is coupled to actuators connected to the motion compensation module 1014. Accordingly, the platform 324 can be used for loading the crane 300 and / or parts 302, 304, 306 of the WTG 102 and stabilized.

Once the crane 300 is in a stable position and in a suspended position, the crane can be transferred to a portion of the WTG 102 as shown in step 1104 of Figure 11.

During the transfer step 1104, the crane 300 is positioned such that it is orientated around the tower 116 as shown in Figure 4. Accordingly the crane 300 can be transferred and secured to the WTG 102. The crane 300 can be secured to any portion of the offshore wind turbine 102. In some embodiments, as mentioned above the securing comprises abutting shock absorbers 904 against the outer surface 906 of the WTG 102.

Additionally or alternatively, the crane 300 is secured to the WTG 102 by engaging a coupler (not shown) mounted on the crane 300 with an external protrusion of the portion of the offshore wind turbine generator 102. In some embodiments, the coupler moves between a retracted and a deployed position when the crane 300 is being secured. The coupler engages with a flange, eye, bracket or any other suitable protrusion on the outer surface 906 of the WTG 102. When the coupler is engaged with the outer surface 906 of the WTG 102, the weight of the crane 300 is supported by the coupler.

Additionally or alternatively, the crane 300 is secured to the WTG 102 by suspending the crane 300 from cables 316 from the portion of the offshore wind turbine generator. In some embodiments, the cables 316 are attached to the

DK 2018 00518 A1 top of the tower 116 or the nacelle 118. In this way, the cables 316 support the weight of the crane 300.

Once the crane 300 is secured to the WTG 102, the vessel 100 can move away from the WTG 102. The crane 300 can then hoist parts 302, 304, 306 of the WTG 102 to be installed from the vessel 100 or another vessel such as a barge (not shown).

This means that the crane 300 can be transferred to the WTG 102 without endangering the vessel 100 or damaging the WTG 102 or the crane 300. Furthermore by suspending at least one portion of the crane or the entire crane 300 above the vessel 100, the crane 300 does not have to climb the WTG 102 up to an operational height. This means that the crane 300 will move less along the WTG 102, have less physical contact with the WTG 102, and cause less damage to the WTG 102.

The method as described in reference to Figures 10 and 11 for transferring the crane 300 to the WTG and compensating for the motion of the vessel 100 can be applied to any of the described embodiments in this application.

Another embodiment will now be described in reference to Figures 6 and 7. Figures 6 and 7 show a side view of a vessel 100 with a crane 300 in a first position and a second position. Identical reference numbers will be used for the same features which have been previously described.

The embodiments shown in Figures 6 and 7 are the same as shown in Figures 1 to 5 except that the support structure 332 is modified. Instead of extendable adjustable arms as shown in Figures 3, 4 and 5, the support structure 332 comprises a pivoting frame 600 which pivots with respect to the vessel 100. The pivoting frame 600 is arranged to move the crane 300 from a first position on the deck 334 of the vessel 100 as shown in Figure 6 to a second, suspended position as shown in Figure 7.

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The pivoting frame 600 comprises a two pairs of pivoting arms 602, 604. Each pair of pivoting arms 602, 604 is positioned on each side of the crane body 310, similar to the arrangement as shown in Figure 5. Figures 6 and 7 only show one pair of the pivoting arms 602, 604. The first pivoting arm 602 is pivotally mounted to the vessel 100 and the second arm 604 is pivotally mounted to the first pivoting arm 602. The first pivoting arm 602 comprises a free end 606 which can use support the boom 312 during the step of transfer 1104. The second pivoting arm 604 is pivotally mounted to the crane body 310 via crane couplings 608.

Each of the first and second pivoting arms 602, 604 comprise actuators 610, 612 for moving the first and second pivoting arms 602, 604. The operation and control of the actuators 610, 612 for motion compensation and movement of the pivoting frame 600 is the same as previously discussed in reference to the previous embodiments.

Once the crane 300 has been moved to the suspended position as shown in Figure 7, the boom 312 no longer rests on the free end 606 of the first pivoting arm 602. The crane 300 is then transferred to the WTG 102 according to step 1104.

The fixed length pivoting arms 602, 604 mean that the support structure 332 can move a heavier crane 300. Fixed length pivoting arms 602, 604 can be preferable because the telescopic extending mechanism as shown in Figure 5 may require enhanced maintenance in the marine environment.

In other embodiments, the support structure 332 can be any suitable structure for suspending the crane 300 above the deck 334 of the vessel 100 and transferring the crane 300 to the WTG 102. Indeed in some embodiments, the support structure 332 is a structure fixed with respect to the vessel 100. In other embodiments, the support structure 332 is releasably mountable on the motion compensation platform 324. Optionally the support structure is transferrable to the WTG 102 together with the crane 300.

DK 2018 00518 A1

Such a fixed support structure 800 will now be described in reference to Figures 8 and 9. Figure 8 shows a side view of a support structure 800 holding the crane 300. Figure 9 shows a plan view of the support structure 800.

The fixed support structure 800 comprises a lattice structure with a fixed length boom 802. The fixed length boom 802 couples to the crane 300 via couplings 910, 912. In this way, the crane 300 is suspended above the vessel 100. The crane 300 is mounted on the fixed support structure 800 remote from the WTG 102. In some embodiments, the crane 300 is loaded on to the fixed support structure 800 in port. Alternatively another vessel can load the crane 300 on to the fixed support structure.

The fixed support structure 800 may be mounted on a motion compensation platform 324. The motion compensation platform 324 may comprise one or more actuators (not shown) for moving the entire fixed support structure 800. The actuators are connected to the motion compensation module 1014 to compensate for the motion of the vessel 100. The compensation of the motion of the vessel 100 is the same as described in connect to the previous embodiments.

Additionally or alternatively the couplings 910, 912 are hydraulically moveable arms connected to the crane body 310. This means that the couplings 910, 912 can move the crane 300 with respect to the vessel. In this way, the couplings 910, 912 are connected to the motion compensation module 1014. The coupling 910, 912 are connected to the motion compensation module 1014 to compensate for the motion of the vessel 100. The compensation of the motion of the vessel 100 is the same as described in connect to the previous embodiments.

In some embodiments, the motion compensated platform 324 can compensate for large movements and the couplings 910, 912 can fine tune the motion compensation.

DK 2018 00518 A1

As mentioned previously, the support structure 332 can be releasably mountable on the vessel 100. The embodiments discussed in reference to Figures 1 to 11 discussed the entire crane 300 being suspended by the support structure 332. However in alternative embodiments, only a portion of the crane is suspended by the support structure 1228 above the vessel.

An embodiment will now be discussed in reference to Figure 12. Figure 12 shows a perspective view of a vessel 100 with a crane 1200 mounted on the deck. The parts of only one WTG 102 are shown in Figure 12, however the vessel 100 is capable of transporting more WTGs 102.

The crane 1200 is shown in a first position according to an embodiment. In the first position, the crane 1200 is positioned at the aftmost part of the vessel 100. In the first position, the crane 1200 is mounted on the deck or optionally positioned on a motion compensation platform 324 mounted on the deck. The motion compensation platform 324 will be discussed in further detail below.

The crane 1200 is removably mounted on the stern 128 of the vessel 100. In some embodiments, the crane 1200 is attached to the vessel 100 or to the motion compensation platform 324 with quick release fixings (not shown).

The crane 1200 is an erectable tower crane 1200 which comprises a plurality of connectable tower segments 1204, 1206, 1208 when erected. Whilst Figure 12 shows three additional connectable tower segments 1204, 1206, 1208, the erected tower crane 1200 can comprise any number of connectable tower segments. This means that the height of the tower crane 1200 is variable.

The connectable tower segments 1204, 1206, 1208 comprise a hollow lattice structure. Advantageously, this reduces the weight of the components of the tower crane 1200 and can make installation of the tower crane 1200 on the transition piece 108 easier.

The tower crane 1200 comprises a slewing hoisting unit 1210 mounted on a first tower segment 1212. The slewing hoisting unit 1210 is rotatably mounted

DK 2018 00518 A1 on the first tower segment 1212 and is rotatable about a central longitudinal axis W-W of the tower crane 1200. This means that the tower crane 1200 can hoist loads in a circular working area about the axis W-W.

The tower crane 1200 comprises a boom 1214 which is pivotally coupled to the crane body 1218 at pivot 1216. The tower crane 1200 comprises one or more cables 1220 which are coupled to a winch 1222 mounted in the crane body 1218. The cable 1220 is connected to yoke 1224 for engaging with a load, such as a WTG tower or any other suitable load.

As shown in Figure 12, the hoisting unit 1210 is raising a removeable crane adapter 1226. In some embodiments, the tower crane 1200 is arranged to hoist the removeable crane adapter 1226 on to the transition piece 108 of the WTG 102 whilst the tower crane 1200 is mounted on the vessel 100. In this way, the tower crane 1200 is optionally configured to be operational whilst mounted on the vessel 100.

The boom 1214 projects laterally from the crane body 1218 so that the load can be lifted clear from the crane body 1218. In some embodiments, the boom 1214 is optionally pivotally connected to an additional jib portion (not shown). The jib portion fixed to the boom 1214 or is pivotally mounted to the boom 1214 and increases the lateral reach of the tower crane 1200.

In some embodiments, the tower crane 1200 comprises a counterweight (not shown) positioned on the opposite side of the crane body 1218 to the boom 1214 for limiting the turning moment about the tower crane structure 1228.

Figure 12 shows a tower crane 1200 with a slewing hoisting unit 1210 with a pivoting boom 1214 such that the angle that the boom 1214 makes with the longitudinal axis W-W can be varied. This means that the lateral reach of the tower crane 1200 can be varied by changing the angle the boom 1214 makes with the longitudinal axis W-W. This can be advantageous to avoid the boom 1214 colliding with nearby tall objects such as the WTG tower 110 on the vessel 100.

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The tower crane 1200 is mountable on a portion of the WTG 102 via the removeable crane adapter 1226. The portion of the WTG 102 as shown in Figure 12 is the transition piece 108 of the WTG 102. In other embodiments, the tower crane 1200 is mountable via the removeable crane adapter 1226 on other parts of the WTG 102 such as the foundation 104, a part of the WTG tower 110 or the entire WTG tower 110. In other embodiments, the tower crane 1200 is directly mountable on a portion of the WTG 102. In this case, the portion of the WTG 102 such as the foundation 104, the transition piece 108 or the WTG tower comprises mounting elements, such as bolts, brackets, pad eyes, loops, hooks or any other suitable fixing for supporting the weight of the tower crane 1200.

The tower crane 1200 comprises a tower segment receiving unit 1230. The tower segment receiving unit 1230 is mountable directly on the WTG 102 or to the removeable crane adapter 1226 mounted on the WTG 102. When the tower segment receiving unit 1230 engages the WTG 102 or the adapter 1226, the tower segment receiving unit 1230 supports the weight of the tower crane structure 1228. This means that the foundation 104 of the WTG 102 supports the weight of both the tower crane 1200 and the WTG 102.

The tower segment receiving unit 1230 is arranged to receive new connectable tower segments 1204, 1206, 1208 to couple to the existing crane tower structure 1228 to increase the height of the tower crane 1200. Installation of the tower crane 1200 will be described in further detail below.

The tower segment receiving unit 1230 comprises a frame 1234 which surrounds a portion of the tower crane structure 1228 formed from the first tower segment 1212 and/ or the connectable tower segments 1204, 1206, 1208. The frame 1234 as shown in Figure 12 comprises solid walls, but in other embodiments the frame 1234 can comprise a lattice structure similar to the connectable tower segments 1204, 1206, 1208. The frame 1234 is in mechanical engagement with the tower crane structure 1228. This means that the tower segment receiving unit 1230 can be fixed in position with respect to

DK 2018 00518 A1 the tower crane structure 1228. However, the tower segment receiving unit 1230 is moveable with respect to the tower crane structure 1228. This means that the tower segment receiving unit 1230 can be fixed with respect to the WTG 102 and the tower crane structure 1228 can move with respect to the WTG 102 and the tower segment receiving unit 1230. Movement of the tower segment receiving unit 1230 will be discussed later on.

The tower segment receiving unit 1230 as shown in Figure 12 is in a lowered position adjacent to the motion compensation platform 324 on the deck 118 of the vessel 100. As mentioned previously, the tower crane 1200 as shown in Figure 12 is mounted on the motion compensation platform 324. The motion compensation platform 324 is coupled to at least one actuator 1232 connected to a motion compensation module 1014 for controlling actuation of the at least one actuator 232. In some embodiments, there are a plurality of actuators 1232 for moving the motion compensation platform 324 in multiple degrees of freedom.

Accordingly, the motion compensation platform 324 can be used for stabilizing the tower crane 1200 whilst transferring the tower crane 1200 to the WTG 102 and / or during operation of the tower crane 1200 when mounted on the vessel 100 as shown in step 1102 of Figure 11. Indeed, the motion compensation platform 324 method is used for attaching the removeable crane adapter 1226 to the transition piece 108 as shown in Figure 12. Accordingly, the movement of the vessel 100 due to the vessel 100 does not affect movement of the removeable crane adapter 1226 when hoisted and transferred to the transition piece 108.

In some embodiments, the pitch, roll and heave motion of the vessel 100 is detected using sensors (not shown) for determining pitch, roll, and/ or heave. The motion compensation module 1014 receives the sensor data relating to the detected motion of the vessel 100. The motion compensation module 1014 determines the deviation of the tower crane 1200 mounted on the motion compensation platform 324 due to the detected motion of the vessel 100 from

DK 2018 00518 A1 a stable crane position. The motion compensation method is similar to the method discussed with reference to the previous embodiments.

The stable crane position can be a predetermined position whereby the movement of the vessel 100 due to the waves and wind does not affect the position of the tower crane 1200 with respect to the transition piece 108. Whilst the tower crane 1200 is mounted on the activated motion compensation platform 324, any translational movement of the tower crane 1200 with respect to the WTG 102 may due to a controlled thrust of the vessel 100. The controlled thrust of the vessel 100 may be required to move the tower crane 1200 closer to the WTG 102 for transfer.

In some embodiments, the motion compensation module 1014 calculates the deviation of a portion of the tower crane 1200 from the predetermined stable crane position. The predetermined stable crane position is a height of the portion of the tower crane 1200 above the vessel 100 required during transferred of the tower crane 1200 to the WTG 102. On detection of deviation from a stable crane position, the motion compensation module 1014 then sends one or more instructions to the actuators 1232, to move the motion compensation platform 324. In this way, the motion compensation module 1014 controls the actuators 1232 to keep the tower crane 1200 fixed at a height with respect to the WTG 102.

The removeable crane adapter 1226 as shown in Figure 12 is attachable to the to the transition piece 108 or the foundation 104 or another part of the WTG 102. In some embodiments, the removeable crane adapter 1226 is circular in cross section and circumferentially surrounds the transition piece 108. Accordingly, in some embodiments the tower crane 1200 lifts the removeable crane adapter 1226 above the transition piece 108 and lowers the removeable crane adapter 1226 so that the transition piece 108 projects through the removeable crane adapter 1226. The removeable crane adapter 1226 is bolted to the transition piece 108. However, in other embodiments the removeable crane adapter 1226 clamps onto a flange at the top of the transition piece 108. Additionally or alternatively, the removeable crane adapter 1226 can use hooks,

DK 2018 00518 A1 loops, brackets, clamps, clips, welds or any other suitable fastening device for fixing the removeable crane adapter 1226 to the transition piece 108.

The removeable crane adapter 1226 is arranged to support the weight of the tower crane 1200 when the tower crane 1200 is installed on the WTG 102. The removeable crane adapter 1226 can be any shape or size and need not be circular in cross section.

The removeable crane adapter 1226 allows the tower crane 1200 to be mounted on the WTG 102 without scratching the WTG tower 110 or the transition piece 108. This means that the WTG 102 will not need an additional coat of paint to treat scratches left by the installation and operation of the tower crane 1200.

Since the removeable crane adapter 1226 can be removed after the tower crane 1200 has been removed from the WTG 102, the removeable crane adapter 1226 is reusable. This reduces the cost of the WTG 102 installation. In some embodiments, the removeable crane adapter 1226 is preinstalled on the transition piece 108. Alternatively, the tower crane 1200 can be directly mounted to the transition piece 108 without an intermediary element between the tower crane 1200 and the transition piece 108. This means that the step of installing the removeable crane adapter 1226 is optional.

Discussion of the method installing the tower crane 1200 on the WTG 102 will now be discussed in further detail in reference to Figures 13 and 14. Figures 13 and 14 show a perspective view of a crane according to an embodiment.

Turning to Figure 13, the removeable crane adapter 1226 has been installed on the transition piece 108 and is ready to receive the tower segment receiving unit 1230.

The tower segment receiving unit 1230 has been raised with respect to the tower crane structure 1228 such that it is aligned slightly above a fixing position on the WTG 102. In this way, the tower segment receiving unit 1230 has been

DK 2018 00518 A1 raised such that it is at the same height as the removeable crane adapter 1226 mounted on the transition piece 108. Accordingly one portion, e.g. the tower segment receiving unit 1230 is suspended above the deck of the vessel 100.

In this way, the tower crane structure 1228 is a support structure 1228 which suspends at least one portion of the crane 1200 above the vessel as shown in step 1100 of Figure 11.

The tower segment receiving unit 1230 optionally comprises a drive mechanism (not shown) mounted in the frame 1234 for lifting the tower segment receiving unit 1230 up the tower crane structure 1228.

The drive mechanism comprises a drive pinion coupled to a drive shaft of a motor (not shown). The drive pinion engages with one or more racks on one or more surfaces of the first tower segment 1212 and also the new tower segments 1204, 1206, 1208. As the drive pinions engage the rack and rotate, the rack moves with respect to the drive pinions. Accordingly, the tower segment receiving unit 1230 moves with respect to the first tower segment 1212. This means that the tower segment receiving unit 1230 can climb the tower structure 1228 and move from the lowered position as shown in Figure 12 to the raised suspend position as shown in Figure 13.

Optionally, the tower segment receiving unit 1230 does not move from the lowered position to the raised suspended position. Instead, the tower segment receiving unit 1230 is transported on the vessel 100 to the transition piece 102 of the WTG 102 in the raised suspended position.

Optionally, the motion compensation platform 324 comprises a lifting platform for raising the first tower segment 1212 or new connectable tower segments 1204, 1206, 1208 relative to the WTG 102. The lifting platform can comprise hydraulic actuators (not shown) coupled to a scissor linkage for changing the height of the lifting platform.

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Returning to Figure 13, the tower segment receiving unit 1230 comprises a first coupling arm 1300 and a second coupling arm 1302. The first and second coupling arms 1300, 1302 are arranged to be positioned either side of the transition piece 108. The first coupling arm 1300 comprises at least one first notch 1304 which is engageable with at least one first protruding peg 1306 on the removeable crane adapter 1226. The second coupling arm 1302 comprises at least one second notch 1308 which is engageable with at least one second protruding peg 1310 on the removeable crane adapter 1226. Figure 13 shows that the first and second coupling arms 1300, 1302 each comprise two notches 1304, 1308 which engage with respective pegs 1306, 1310.

Once the tower segment receiving unit 1230 has been moved to the raised position as shown in Figure 13, the vessel 100 is moved towards the transition piece 108 and relative movement between the vessel 100 and the WTG 102 is compensated as shown in step 1102 of Figure 11.

Figure 14 shows the tower segment receiving unit 1230 mounted on the removeable crane adapter 1226. Accordingly, the suspended tower segment receiving unit 1230 is transferred between the vessel 100 and the WTG 102 as shown in step 1104 in Figure 11.

In this way, the transition piece 108 and the foundation 104 are entirely supporting the weight of the tower crane 1200 since the tower segment receiving unit 1230 is fixed to the transition piece 108 via the removeable crane adapter 1226. At the same time the support structure 1228 provides a dual purpose. Firstly, the support structure 1228 allows the tower segment receiving unit 1230 to be suspended above the vessel 100. Secondly, the support structure 1228 is the tower crane structure 1228 for providing the vertical height of the tower crane 1200.

In some embodiments, the vessel 100 is optionally tethered to the transition piece 108 by a tether 1400. The tether 1400 can be used to limit the movement of the vessel 100 with respect to the transition piece 108 in one or more directions. The tether 1400 as shown in Figure 14 is a strap wrapped around

DK 2018 00518 A1 the transition piece 108, but the tether 1400 can be a mooring line attached at one end to the transition piece 108 and to the vessel 100 at the other end. In other embodiments, the tether 1400 can be any number of straps, lines or ropes or any other suitable means for attaching the vessel 100 to the transition piece 108. By tethering the vessel 100 to the transition piece 108, the relative movement of the vessel 100 with respect to the transition piece 108 of WTG 102 can be limited. This can make the motion compensation when transferring the tower crane 1200 easier because there will be fewer degrees of relative movement between the vessel 100 and the transition piece 108. Additionally or alternatively, the vessel 100 can use dynamic positioning to fix the position of the vessel 100 with respect to the transition piece 108 as mentioned above.

The tower segment receiving unit 1230 is then lowered on to the removeable crane adapter 1226 so that the coupling arms 1300, 1302 engage the pegs 306, 310 of the crane adapter 1226. Once the first and second coupling arms 1300, 1302 are in engagement with the removeable crane adapter 1226, the first and second coupling arms can optionally be further secured to the transition piece 108. The first and second coupling arms 1300, 1302 can be bolted, clipped or clamped to the removeable crane adapter 1226 to prevent the tower crane 1200 from moving with respect to the transition piece 108.

Additionally or alternatively, the removeable crane adapter comprises a locking mechanism 1406 for actively securing the coupling arms 1300, 1302 to the adapter 1226. The locking mechanism 1406 comprises a first latch 1402 and a second latch 1404 arranged to move between a released position and a locked position. When in the locked position, the first and second latches 1402, 1404 physically engage the first and second coupling arms 1300, 1302 and counteract any turning moment the tower crane 1200 is creating about the removeable crane adapter 1226. In some embodiments, the locking mechanism 1406 is hydraulically actuated.

The tower crane structure 1228, as shown in Figure 14, has also moved with respect to the tower segment receiving unit 1230 and the transition piece 108. The driving mechanism which is used by the tower segment receiving unit 1230

DK 2018 00518 A1 to climb the tower crane structure 1228 is optionally also a lifting mechanism to lift the tower crane structure 1228 to an operational position. The arrow as shown in Figure 14 indicates the direction that the tower crane structure 1228 is lifted by the tower segment receiving unit 1230.

Another embodiment will now be described in reference to Figures 15 to 17. Figures 15 to 17 show a perspective view of the tower crane 1200 mounted on the vessel 100 or the transition piece 108.

The tower crane 1200 as shown in Figures 15 to 17 is the same as described in reference to the previous embodiments shown in Figures 12 to 14 and the installation of the tower crane structure 228 is the same. However, the embodiment differs in that a crane adapter 1500 mounts differently on the tower segment receiving unit 1230.

The crane adapter 1500 is mountable on the tower crane receiving unit 1230 during transportation of the tower crane 1200 to the WTG 102 installation site. Accordingly, the crane adapter 1500 takes up less space on the vessel 100.

In contrast to the preceding embodiments, the crane adapter 1500 comprises first and second coupling arms 1508, 1510 each comprising a notch 1512, 1514 which engage with a projecting peg 1306, 1310 on the transition piece 108. The coupling arms 1508, 1510 engage with the transition piece 108 in a similar way to the previous embodiments.

In addition, the crane adapter 1500 comprises a first and second stabilizing arm 1502, 1504 for engagement with a first and a second projecting stop elements 1506 mounted on the transition piece 108. The stabilizing arms 1502, 1504, engage with the first and second stop elements 1506 and prevent the tower crane 1200 and the adapter 1500 tilting with respect to the transition piece 108. In other embodiments, the first and second stabilising arms 1502, 1504 are the same as the first and second coupling arms 1508, 1510 and similarly notches for engagement with additional projecting studs (not shown) from the transition piece 108.

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Figure 16 shows the first stabilizing arm 1502 engaged with the first projecting stop element 1506. The stabilizing arms as shown in Figures 15 to 17 can be used in combination with the coupling arms as described in any of the preceding embodiments.

Figure 16 shows the crane adapter 1500 mounted on the transition piece 108. The tower crane 1200 has hoisted the crane adapter 1500 on to the transition piece 108 similar to the process as described in reference to the previous embodiments.

The crane adapter 1500 comprises a first winch 1600 and a second winch 1602 arranged to hoist the tower crane 1200 up to the crane adapter 1500 mounted on the transition piece 108. In other embodiments, the crane adapter 1500 can have a single winch. The tower segment receiving unit 1230 comprises one or more brackets 1604 for coupling to cables 1606 from the first and second winches 1602, 1604. This means that there are only cable connections between the crane adapter 1500 and the tower crane 1200 when the tower crane 1200 is transferred to the transition piece 108. This can make the transfer simpler and require less motion compensation. In some embodiments, the cables 1606 are always connected between the crane adapter 1500 and the tower segment receiving unit 1230. This means that time can be saved installing the tower crane 1200 on the crane adapter 1500.

The crane adapter 1500 comprises a notch 1608 for receiving a projecting stud 1610 on each side of the tower segment receiving unit 1230. When the tower crane 1200 is hoisted by the first and second winches 1600, 1602, the stud 1610 engages an inclined surface 1612 on the underside of the crane adapter 1500 as the tower segment receiving unit 1230 approaches the crane adapter 1500. The inclined surface 1612 guides the stud 1610 into the notch 1608. Accordingly, the first and second winches only need to hoist the tower crane 1200 from the vessel 100 in a vertical direction and the underside of the crane adapter 1500 is shaped to guide the tower crane 1200 into engagement with the crane adapter 1500.

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Figure 17 shows the tower crane 1200 in mechanical engagement with the crane adapter 1500. Once the inclined surface 1612 abuts a reciprocally inclined surface 1702 of the tower segment receiving unit 1230, the tower crane 1200 is secured to the crane adapter 1500.

In some embodiments, the crane adapter 1500 comprises a locking mechanism 1700 for securing the stud 1610 in position in the notch 1608. The locking mechanism comprises a bar which is moveable between an unlocked position and a locked, secured position. In the locked, secured position, the bar 1700 is below the projecting stud 1610 and prevents the stud 1610 from being removed from the notch 1608. In this way, the crane adapter comprises a first coupling with the transition piece 108 and a second coupling with the tower crane 120.

When the tower crane 1200 is hoisted into the position as shown in Figure 17 with respect to the crane adapter 1500, the locking mechanism is moved to the secure position and the tower crane 1200 is secured to the crane adapter 1500. In some embodiments, the locking mechanism is hydraulically actuated. Once the locking mechanism 1700 has been actuated, the first and second winches 1600, 1602 can be disengaged. In other embodiments, any other suitable securing mechanism can be used to securely fix the crane adapter 1500 to the tower crane 1200 such as bolts, moveable pins, clamps, etc. In other embodiments, the locking mechanism is not required and the first and second winches 1600, 1602 positively hold the tower crane 1200 against the crane adapter 1500. In some embodiments, the first and second winches 1600, 1602 comprise brakes for holding the winches 1600, 1602 with the cables 1606 a fully retracted state. Accordingly, the first and second winches 1600, 1602 are a redundancy for keeping the tower crane 1200 fixed with respect to the crane adapter 1500 and the WTG 102. In order to uninstall the tower crane 120, the reverse steps are taken to the installation described herein.

In another embodiment two or more embodiments are combined. Features of one embodiment can be combined with features of other embodiments.

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Embodiments of the present invention have been discussed with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the 5 scope of the invention.

Claims

Claims

1. A method of installing at least one portion of a crane on a portion of an offshore wind turbine generator from a vessel having a crane support structure, the method comprising:

suspending the portion of the crane in the support structure above the vessel;

compensating for relative motion between the portion of the offshore wind turbine generator and the vessel such the suspended portion of the crane is stable relative to the portion of the offshore wind turbine; and transferring the suspended portion of the crane between the vessel and the portion of the offshore wind turbine.
2. A method according to claim 1 wherein the method comprises determining the distance and position of the vessel with respect to the portion of the offshore wind turbine.
3. A method according to any of the preceding claims wherein the compensating comprises maintaining the vessel at a fixed distance and position from the portion of the offshore wind turbine generator based on the determined distance.
4. A method according to any of the preceding claims wherein the compensating comprises determining the relative motion of the portion of the crane with respect to the vessel and / or the portion of the offshore wind turbine generator.
5. A method according to any of the preceding claims wherein the compensating comprises adjusting the position of the portion of the crane with respect to the vessel and / or the offshore wind turbine generator in one or more directions to compensate for heave, sway, surge, roll, pitch and / or yaw motion of the vessel.

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6. A method according to any of the preceding claims wherein the compensating comprises adjusting a moveable actuator of the support structure coupled to a motion compensation platform with respect to the vessel.
7. A method according to any of the preceding claims wherein the compensating comprises adjusting the position and / or orientation of one or more coupling actuators with respect to vessel, wherein the one or more coupling actuators are mounted between the crane and the support structure fixed to the vessel.
8. A method according to any of the preceding claims wherein the compensating comprises adjusting the position of the crane with respect the vessel by moving one or more moveable actuators coupled to one or more adjustable arms of the support structure, wherein the adjustable arms are coupled between the vessel and the portion of the crane.
9. A method according to claim 8 wherein the adjustable arms are extendable and / or pivotable with respect to the vessel.
10. A method according to claims 8 or 9 wherein the adjustable arms are independently controllable.
11. A method according to any of claims 8 to 10 wherein a first adjustable arm releasably engages the portion of the crane on a first side and a second adjustable arm releasably engages the portion of the crane on a second side.
12. A method according to any of the preceding claims wherein the method comprises securing the portion of the crane to the portion of the offshore wind turbine.
13. A method according to claim 12 wherein the securing comprises closing one or more moveable doors hinged on a body of the portion of the crane around the portion of the offshore wind turbine generator.

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14. A method according to any of claims 12 or 13 wherein the securing comprises engaging a coupler mounted on the portion of the crane with an external protrusion of the portion of the offshore wind turbine generator.
15. A method according to any of claims 12 to 14 wherein the securing comprises suspending the portion of the crane from cables from the portion of the offshore wind turbine generator.
16. A method according to any of the preceding claims wherein the step of suspending the portion of the crane above the vessel comprises elevating the crane from a first position where the crane is adjacent to a deck of the vessel and to a second position wherein the crane is suspended above the deck of the vessel.
17. A method according to any of the preceding claims wherein the at least a portion of the crane comprises one or more portions of a tower crane.
18. A method according to any of the preceding claims wherein the support structure is transferred to the wind turbine generator together with the at least one portion of the crane.
19. A vessel comprising:

a support structure mounted on a vessel for suspending and transferring a portion of crane installable on a portion of an offshore wind turbine generator;

at least one moveable actuator coupled to the support structure and arranged to move the suspended portion of the crane to compensate for relative motion between the portion of the offshore wind turbine generator and the vessel such the portion of the crane is stable relative to the portion of the offshore wind turbine.
20. A vessel according to claim 19 wherein the support structure comprises a first adjustable arm engageable with the portion of the crane on a first side and a second adjustable arm engageable with the portion of the crane on a second side.