Offshore wind power plant servicing

Abstract

A method of removing a component (110) from an offshore wind power plant (100), the method comprising: arranging a crane (101) at a top part (100a) of the offshore wind power plant (100); operating the crane (101) to lift the component (110) off the offshore wind power plant (100); lowering the component (110) adjacent the offshore wind power plant (100) while supporting the component (110) by the crane (101) via at least one hoisting line (140); moving the component (110) horizontally to a position above a deck (121) of a vessel (120) by pulling the component (110) by means of a winch (131) arranged on the vessel (120), while supporting the component (110) by the crane (101); and landing the component (110) at a motion compensated landing apparatus (130) arranged on the deck (121) and transferring a weight of the component (110) to the landing apparatus (130).

Description

[0001] OFFSHORE WIND POWER PLANT SERVICING

[0002] The present disclosure relates to servicing of offshore wind power plants, for example replacement of components of an offshore wind power plant.

[0003] BACKGROUND

[0004] Offshore wind power has established itself as a viable technology for electric power generation, and installed offshore wind power plants (often simply referred to as “wind turbines”) already provide a notable contribution to the electric power production in many countries. Further developments and further increase in installed offshore wind power capacity are expected in the future. Such offshore wind power plants may be bottom-fixed or floating, with currently existing plants being almost exclusively bottom-fixed. Nevertheless, it is expected that also floating wind power plants will increasingly be used in the future.

[0005] For such offshore wind power plants, technical servicing can pose a challenge. Required servicing may involve maintenance or repair work, overhauling, and / or replacement of parts / components of the power plant, for example replacement of transmission components (like bearings and gearboxes), electric generator parts or turbine blades. Compared with land-based plants, accessibility for servicing operations can be more challenging at offshore plants. This can increase the costs and complexity of such servicing operations, and also lead to increased downtimes with corresponding lost power production from the plant. Health-and-safety (HSE) aspects for servicing work carried out at offshore locations may also be more demanding, and HSE requirements more stringent.

[0006] There is consequently a need for improved technology in this area, for example in order to allow safe and efficient servicing operations at offshore wind power plants. The present disclosure has the objective to provide such improvements, or at least useful alternatives to the state of the art. SUMMARY

[0007] In an example, there is provided a method of removing a component from an offshore wind power plant, the method comprising: arranging a crane at a top part of the offshore wind power plant; operating the crane to lift the component off the offshore wind power plant; lowering the component adjacent the offshore wind power plant while supporting the component by the crane via at least one hoisting line; moving the component horizontally to a position above a deck of a vessel by pulling the component towards the vessel by means of a winch arranged on the vessel, while supporting the component by the crane; and landing the component at a motion compensated landing apparatus arranged on the deck and transferring a weight of the component to the landing apparatus.

[0008] In other examples, there is provided a method of installing a component at an offshore wind power plant, a motion compensated landing apparatus for handling a component of an offshore wind power plant on a vessel, an assembly for handling a component of an offshore wind power plant, a vessel for handling a component of an offshore wind power plant, and methods of receiving and providing a component for an offshore wind power plant at / from a vessel.

[0009] The appended claims and detailed description below outlines further examples and embodiments.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and other characteristics will become clear from the following description of illustrative, non-restrictive examples, with reference to the attached drawings, in which:

[0012] Figs 1-10 illustrate various operations associated with removing a component from an offshore wind power plant according to an example method, and example equipment suitable for use with the example method. Figs 11 -13 illustrate a motion compensated landing apparatus according to an example.

[0013] Figs 14-17 illustrate a motion compensated landing apparatus and associated equipment arranged on a vessel deck, and examples of the use thereof to remove, install or replace a component of an offshore wind power plant.

[0014] DETAILED DESCRIPTION

[0015] Illustrated in Figs 1 -10, in an example, there is provided a method of removing a component 1 10 from an offshore wind power plant 100. The skilled reader will understand that similar steps as those illustrated, but in substantially reversed order, may be used to install a component 1 10 to the offshore wind power plant 100.

[0016] Fig. 1 illustrates a service vessel 120 positioned adjacent an offshore wind power plant 100. The offshore wind power plant 100 may be a bottom-fixed plant, as is illustrated here, or a floating offshore wind power plant. The offshore wind power plant 100 conventionally comprises a base 103, a tower 11 1 , a nacelle structure 150 (see Figs 5 and 6) and blades 102.

[0017] A crane 101 can be arranged at a top part 100a of the offshore wind power plant 100, for example at a nacelle structure 150 (see Figs 5 and 6). The crane 101 can be provided from the vessel 120, from another vessel, or from the offshore wind power plant 100. The crane 101 may, for example, be a permanent feature of the offshore wind power plant 100. The crane 101 may be a so-called up-tower crane. In the present example, the crane 101 is provided from the vessel 1 as a self-hoisting up-tower crane. The crane 101 is brought into position at the top part 100a via selfhoisting crane cables 156. Installation of the crane 101 can, for example, be carried out as described in international patent application WO 2020 / 201237 A2.

[0018] The vessel 120 has a motion compensated landing apparatus 130 arranged on the deck 121 . Illustrated in Fig. 9, the motion compensated landing apparatus 130 has a base 133 configured to support the landing apparatus 130 on the deck 121 of the vessel 120 and a heave compensated receiver part 134. The heave compensated receiver part 134 comprises a landing face 135 for supporting the component 110. In this example, the component 110 is a gearbox, and is handled via a yoke 132. The yoke 132 is configured to be able to land and rest at the heave compensated receiver part 134, as illustrated in Figs 2 and 3.

[0019] To remove the component 110, the yoke 132 is brought to a position above the component 110, as illustrated in Fig. 5. The crane 101 handles the yoke 132 via hoisting lines 140, for example wire ropes, for this purpose. The hoisting lines 140 may, for example, be coupled to a winch at (or otherwise associated with) the crane 101 . Fig. 6 illustrates the component 110 having been lifted out of the nacelle structure 150. The component 110 is then lowered adjacent the offshore wind power plant 100, as illustrated in Figs 7-8. The component 110 may be lowered substantially vertically adjacent the tower 111 , while being supported by the crane 101 via the hoisting lines 140. The component 110 may be suspended freely from the crane 101 during this process, i.e. such that the component 110 simply hangs vertically below the crane 101 , such as below a wire block at the tip of a crane arm which extends outwardly such as to space the component 110 from the tower 111. The component 110 can, for example, be lowered to a position horizontally adjacent a lower part 111 a of the tower 111 , and / or horizontally adjacent the base 103. This may involve lowering the component 110 vertically or substantially vertically a distance which is at least 50%, at least 75% or at least 90% of a height of the tower 111.

[0020] With the component at the lowered position, as illustrated in Figs 8 and 9, the component 110 is moved to a position above the deck 121 of the vessel 120 while supporting the component 110 by the crane 101 . Pull-in-lines 143 can be used for this purpose. In the illustrated example, two pull-in-lines 143 are connected to the yoke 132, and one pull-in-line 143 is connected to a yoke connector 132a (Fig. 9), but various other pull-in-line arrangements are possible. The pull-in-lines 143 may, for example, be fixed to the component 110. The pull-in-lines 143 are connected to winches 131 such as to allow the component 110 to be moved towards the vessel 120 while the vessel 120 maintains its position adjacent the offshore wind power plant 100. The component 110 is pulled towards the vessel 120 and above the deck 121 such as to bring the component 1 10 into engagement with the heave compensated receiver part 134. The component 1 10 can then be landed at the motion compensated landing apparatus 130, as illustrated in Fig. 10. During this process, the motion compensated landing apparatus 130 can be in an active operational configuration such as to control the position and / or orientation of the heave compensated receiver part 134 relative to the component 1 10 / the yoke 132. In this way, the component 1 10 can be landed and its weight transferred to the vessel 120 in a controlled manner and with reduced risk of damage to components as compared to, for example, landing the component 1 10 directly at the deck 121 .

[0021] The hoisting lines 140 may be paid out (or continuously adjusted) simultaneously in order to help position the component 110 at the heave compensated receiver part 134.

[0022] Advantageously, the component 1 10 may be pulled into direct or indirect horizontal engagement with the landing apparatus 130 by means of the winches 131 (as in Fig. 10) and held in that position by the winches 131 prior to transferring the weight to the landing apparatus 130 by paying out the hoisting lines 140.

[0023] Once the weight of the component 1 10 is transferred fully to the landing apparatus 130, the tension in the hoisting lines 140 can be relaxed. The hoisting lines 140 may remain connected to the yoke 132 or temporarily fixed to the heave compensated receiver part 134. The hoisting lines 140 can, for example, be controlled to maintain a moderate tension such as to hold the hoisting lines 140 stretched (so as to avoid slack and not interfere with other operations), but without providing any significant hoisting force. The yoke 132 may be temporarily locked in place at the landing apparatus 130 after landing the component 110 / the yoke 132.

[0024] After landing, the component 1 10 may be released from the yoke 132 and the hoisting lines 140.

[0025] In the examples illustrated in Figs 1 -10, the motion compensated landing apparatus 130 comprises two parts 130a and 130b. The heave compensated receiver part 134 is arranged on a first part 130a, while the winches 131 are arranged on a second part 130b. The second part 130b may be configured with suitable sheaves, guides, etc. for the pull-in lines 143, for example arranged in a frame or truss structure 129. This configuration may ease transportation and rig-up of the landing apparatus 130.

[0026] Alternatively, as illustrated in Figs 11-17, the motion compensated landing apparatus 130 with the abovementioned components may be arranged as a single unit, having a common base 133.

[0027] The landing apparatus 130 may have two horizontally spaced compensation arms 137a,b (indicated in Fig. 13, but also visible in other figures, such as Figs 3 and 4). The landing apparatus 130 may have two landing faces 135, and each of the two landing faces 135 may be arranged in conjunction with one of the horizontally spaced compensation arms 137a,b, e.g. directly or substantially directly above the respective compensation arm 137a,b. The two horizontally spaced compensation arms 137a,b may be independently operable, whereby for example alignment of the landing faces 135 relative to the lifting yoke 132 can be provided. The two compensation arms 137a,b may, for example, each comprise a hydraulic cylinder assembly operable to adjust the extension of the respective compensation arm 137a,b.

[0028] The heave compensated receiver part 134 may be arranged as a two-part structure, as illustrated in the examples shown in Figs 1 -4 and 9-10. Each part of the two-part structure may in this example be associated with one compensation arm 137a,b. Alternatively, as illustrated in Figs 11-17, the heave compensated receiver part 134 may be a single structure connected to both compensation arms 137a,b. Alternatively, the heave compensated receiver part 134 can be arranged with a single compensation arm.

[0029] Also, most clearly visible in Figs 11-17, the heave compensated receiver part 134 may be pivotable about two orthogonal horizontal axes 136,144 relative to the base 133 (see Fig. 11 ). The axes 136,144 may each be parallel with the deck 121. Compensation actuators 139,145, such as hydraulic cylinders, may be provided to adjust the orientation of the heave compensated receiver part 134 relative to each of the two orthogonal horizontal axes 136,144. In the illustrated example (see particularly Figs 11 , 13 and 16), cylinders 145 are operable to adjust the orientation of the receiver part 134 about axis 144 via a subframe 146 which is pivotably arranged as part of the base 133. Cylinders 139 are operable to adjust the orientation of the receiver part 134 about axis 136. In the illustrated example, cylinders 139 are fixed to the compensation arms 137a,b and to the subframe 146, and the compensation arms 137a,b are arranged pivotable relative to the subframe 146.

[0030] In this manner, the motion compensated landing apparatus 130 can provide motion compensation which partially or fully compensates for vessel 120 roll and pitch. Heave motion of the vessel 120 may be compensated by the extension / retraction of the compensation arms 137a,b. Vessel 120 surge, sway and yaw motion can, if required, be compensated for by the vessel’s 120 propulsion machinery.

[0031] Also illustrated in e.g. Figs 10 and 11 , the heave compensated receiver part 134 may advantageously be pivotable about a horizontal axis 136 such as to allow the component 110 to be moved relative to the deck 121 when the component 110 is supported by the landing apparatus 130. For example, when the component 110 is landed and supported by the landing apparatus 130 as shown in Fig. 10, a pivotable part 138 which comprises the heave compensated receiver part 134 may be pivoted relative to the base 133 such as to lower the component 110. The pivotable part 138 may, for example, comprise the heave compensated receiver part 134 and the two horizontally spaced compensation arms 137a,b (see Fig. 13). This may, for example, be done by means of a hinged or otherwise rotatable mechanical link between the base 133 and the pivotable part 138, and actuators, such as the hydraulic cylinders 139, operable to control the orientation of the pivotable part 138 relative to the base 133. This mechanism may be shared with a compensation mechanism operable to adjust the orientation of the receiver part 134 about axis 136, as described above. In the illustrated example, the link is provided between the subframe 146 and the pivotable part 138, which is movable relative to the subframe 146 as indicated by the double arrow in Fig. 16 by extension or contraction of the hydraulic cylinders 139.

[0032] Indicated particularly in Fig. 13, the heave compensated receiver part 134 may be configured to receive the component 110 at a first side 148 thereof, and to lay down the component 110 at a second side 149 thereof. The first side 148 may be a side of the heave compensated receiver part 134 facing the offshore wind power plant 100 when in use (see e.g. Figs 8 and 9). The second side 149 may be the opposite side of the heave compensated receiver part 134, where for example associated equipment is arranged on the deck 121. The compensation arms 137a,b may be configured to pass the component 110 therebetween (i.e., between the arms 137a, b) when moving the component 110 from the first side 148 to the second side 149, during the pivoting motion of the heave compensated receiver part 134.

[0033] Alternatively, the landing apparatus 130 may be configured with a single compensation arm or an equivalent single compensation structure.

[0034] The component 110 may be laid down at a transport rack 170 (see Figs 14 and 15) at the second side 149. Alternatively, the component 110 may, for example, be laid down directly on the deck 121 , onto a temporary holder, or in a different manner. The component 110 may, for example, be laid down positioned for it to be picked up by other equipment, such as a crane or vehicle operating on the deck 121.

[0035] In the examples illustrated in Figs 14-17, the vessel 120 comprises a transport rack 170 provided on and operable to be moved on a plurality of rails or tracks 171 arranged on the deck 121 . Optionally, the transport rack 170 may be provided for example on (or configured to be handled by) a self-propelled modular transporter (SPMT, such as a “multi-wheeler” or belt-driven vehicle), on a skid supported directly on the deck 121 , or in another manner. In such a case, the transport rack 170 may be freely movable on the deck 121 . A plurality of parking racks 172 are also arranged on the deck 121 , in this example adjacent the rails or tracks 171. The parking racks 172 may be configured to hold a component 110 prior to installation or after removal, such as during transport to or from a site of the offshore wind power plant 100. The parking racks 172 may, if-and-as required, comprise appropriate seafastening arrangements for this purpose.

[0036] The transport rack 170 is movable between a lay-down position adjacent the heave compensated receiver part 134 (the position in which the transport rack 170 is illustrated in Figs 14-17) and to other positions adjacent one of the parking racks 172. The transport rack 170 may, for example, be moved by means of skidding or rolling, either self-propelled or moved by other, associated equipment. When the transport rack 170 is positioned adjacent one of the parking racks 172, the component 110 may, for example, be moved over to the parking rack 172 by skidding, lifting, rolling or by other means. The transport rack 170 and the parking racks 172 may, for example, have support surfaces for the component 110 having the same height, such that the component 110 may be skidded horizontally from a support surface of the transport rack 170 and to a support surface of the parking rack 172.

[0037] In the same manner as described here, but in substantially reverse order, a new component 110 may be provided to the landing apparatus 130 for installation at the offshore wind power plant 100. A new component 110 may be picked up from a parking rack 172 by the transport rack 170 and provided at the motion compensated landing apparatus 130 to be connected to the hoisting lines 140 and lifted to the nacelle structure 150.

[0038] The component 110 may, during such handling on the deck 121 , be positioned on or in a support structure 177 (see Fig. 17), such as a component holder, base or handling frame. Such a support structure 177 may be specifically designed for the component 110 in question, for example having prepared receptacles and / or fixation means for engagement with the component 110. The component 110 may be laid down into or onto the support structure 177 by the heave compensated receiver part 134 at the lay-down position. (Or, in the reverse, be lifted off or out of the support structure 177 by the heave compensated receiver part 134 at the lay-down position.)

[0039] The transport rack 170 and / or the parking racks 172 may, for example, be a frame, a plate, a shelf, a truss structure, beams, rails, or the like, configured to hold the component 110 either directly or via a support structure 177.

[0040] In any of the examples or embodiments described or claimed herein, the motion compensated landing apparatus 130 may comprise a frame or truss structure 129 comprising sheaves 128 (indicated in Figs 9 and 13, but also visible in the other figures). The sheaves 128 may be arranged at a suitable height such as to facilitate substantially horizontal pull-in of the component 110 and / or the yoke 132. The motion compensated landing apparatus 130 may further comprise a guide 127, such as a wireline guide (see Figs 1 1 -13) arranged to guide the pull-in lines 143. The guide 127 may be arranged at the heave compensated receiver part 134 and movable therewith.

[0041] In the illustrated examples, the motion compensated landing apparatus 130 has two horizontally spaced landing faces 135 arranged on the heave compensated receiver part 134 and configured to receive the component 1 10 or the lifting yoke 132. (One of which is indicated in Fig. 9, and also visible also in other figures.) The landing faces 135 may be arranged to provide vertical support of the component 1 10, either directly (for example if the component 110 has suitable support faces for this purpose, such as outward-extending lifting rods, lugs or the like) or via the yoke 132. The landing faces 135 may, for example, be configured to engage with respective outer end parts of the yoke 132 and allow the yoke 132 to rest on the receiver part 134.

[0042] Alternatively, for example if a one-part heave compensated receiver part 134 is used, there may only be a single landing face 135. A single landing face 135 may, for example, be arranged centrally on the heave compensated receiver part 134, for example at a middle section of a horizontal beam forming part of the heave compensated receiver part 134.

[0043] In any of the examples or embodiments described or claimed herein, the heave compensated receiver part 134 may further comprise guide faces 126 (see Fig. 9) arranged to guide the component 1 10 (directly or indirectly via the yoke 132) into a position above the landing faces 135. The guide faces 126 may, for example, be vertical or substantially vertical faces arranged to provide horizontal alignment / guiding of the component 110 and / or the yoke 132 towards the landing faces 135. As the component 110 is being moved towards the motion compensated landing apparatus 130 by means of the pull-in lines 143, the guide faces 126 may provide alignment of the component 110 and / or the yoke 132 with the landing faces 135 before the weight of the component 110 is transferred to the motion compensated landing apparatus 130.

[0044] The crane 101 may be a temporary crane, and may be removed after having removed and / or installed a component 110 at the offshore wind power plant 100. In any of the examples or embodiments described or claimed herein, the vessel 120 may be a floating vessel.

[0045] Further inventive aspects and embodiments according to the present disclosure are outlined in the following numbered clauses.

[0046] C1 .A method of removing a component (1 10) from an offshore wind power plant (100), the method comprising: arranging a crane (101 ) at a top part (100a) of the offshore wind power plant (100); operating the crane (101 ) to lift the component (110) off the offshore wind power plant (100), such as off or out of a nacelle structure (150) of the offshore wind power plant (100); lowering the component (110) adjacent the offshore wind power plant

[0047] (100) while supporting the component (110) by the crane (101 ); moving, for example horizontally moving or substantially horizontally moving, the component (1 10) to a position above a deck (121 ) of a vessel (120) while supporting the component (110) by the crane (101 ); and landing the component (110) at a motion compensated landing apparatus (130) arranged on the deck (121 ).

[0048] C2.The method of any preceding clause, wherein the step of lowering the component (110) comprises lowering the component (110) vertically or substantially vertically along and adjacent a tower (111 ) of the offshore wind power plant (100).

[0049] C3.The method of any preceding clause, wherein the step of supporting the component (110) by the crane (101 ) comprises supporting the component (110) from the crane (101 ) via at least one hoisting line (140), such as a wire rope.

[0050] C4.The method of any preceding clause, wherein the step of lowering the component (110) comprises lowering the component (110) with the component (110) suspended from the crane (101 ) via at least one hoisting line (140), such as suspended freely or substantially freely from the crane

[0051] (101 ) via the at least one hoisting line (140). C5.The method of any preceding clause, wherein the step of lowering the component (110) comprises lowering the component (110) vertically a distance which is at least 50%, at least 75% or at least 90% of a height of the tower (111).

[0052] C6.The method of any preceding clause, wherein the step of lowering the component (110) comprises lowering the component to a position which is horizontally adjacent a base (103) of the offshore wind power plant (100).

[0053] C7.The method of any preceding clause, wherein the step of lowering the component (110) is carried out prior to the step of moving the component (110) to the position above the deck (121).

[0054] C8.The method of any preceding clause, wherein the step of moving the component (110) to the position above the deck (121 ) of a vessel (120) comprises pulling the component (110) towards the vessel (120) by means of a winch (131) arranged on the vessel (120), such as on the deck (121).

[0055] C9.The method of any preceding clause, wherein the step of landing the component (110) comprises: pulling the component (110) into direct or indirect horizontal engagement with the landing apparatus (130) by means of the winch (131), and with the component (110) in direct or indirect horizontal engagement with the landing apparatus (130), paying out a hoisting line (140) such as to transfer a weight of the component (110) to the landing apparatus (130).

[0056] C10. The method of any preceding clause, comprising releasing the hoisting line (140) from the component (110).

[0057] C11 . The method of any preceding clause, comprising: fixing a lifting yoke (132) to the component (110), lifting and supporting the component (110) from the crane (101 ) via the lifting yoke (132), and wherein the step of landing the component (110) comprises bringing the lifting yoke (132) into engagement with the landing apparatus (130).

[0058] C12. The method of any preceding clause, wherein the component (110) is suspended from the lifting yoke (132).

[0059] C13. The method of any preceding clause, wherein the step of landing the component (110) comprises: bringing the component (110) into indirect horizontal engagement with the landing apparatus (130) via the lifting yoke (132), and / or transferring a weight of the component (110) to the landing apparatus (130) via the lifting yoke (132).

[0060] C14. A method of installing a component (110) at an offshore wind power plant (100), the method comprising: arranging a crane (101 ) at a top part (100a) of the offshore wind power plant (100); providing the component (110) at a motion compensated landing apparatus (130) arranged on a deck (121) of a vessel (120); moving, for example horizontally moving or substantially horizontally moving, the component (110) from a position above the deck (121) to a position adjacent the offshore wind power plant (100) while supporting the component (110) by the crane (101); lifting the component (110) adjacent the offshore wind power plant (100) while supporting the component (110) by the crane (101); and operating the crane (101 ) to position the component (110) at the offshore wind power plant (100), such as at or into of a nacelle structure (150) of the offshore wind power plant (100).

[0061] C15. The method of any preceding clause, wherein the step of lifting the component (110) comprises lifting the component (110) vertically or substantially vertically along and adjacent a tower (111) of the offshore wind power plant (100).

[0062] C16. The method of any preceding clause, wherein the step of supporting the component (110) by the crane (101 ) comprises supporting the component (110) from the crane (101) via at least one hoisting line (140), such as a wire rope.

[0063] C17. The method of any preceding clause, wherein the step of lifting the component (110) comprises lifting the component (110) with the component (110) suspended from the crane (101) via at least one hoisting line (140), such as suspended freely or substantially freely from the crane (101) via the at least one hoisting line (140).

[0064] C18. The method of any preceding clause, wherein the step of lifting the component (110) comprises lifting the component (110) vertically a distance which is at least 50%, at least 75% or at least 90% of a height of the tower (111).

[0065] C19. The method of any preceding clause, wherein the step of moving the component (110) to the position adjacent the offshore wind power plant (100) comprises moving the component to a position which is horizontally adjacent a base (103) of the offshore wind power plant (100).

[0066] C20. The method of any preceding clause, wherein the step of moving the component (110) to the position adjacent the offshore wind power plant (100) is carried out prior to the step of lifting the component (110).

[0067] C21 . The method of any preceding clause, wherein the step of moving the component (110) from the position above the deck (121 ) to the position adjacent the offshore wind power plant (100) comprises holding the component (110) by means of a winch (131 ) arranged on the vessel (120), such as on the deck (121 ), and paying out the winch (131).

[0068] C22. The method of any preceding clause, wherein the step of moving the component (110) from the position above the deck (121 ) to the position adjacent the offshore wind power plant (100) comprises: pulling the component (110) into direct or indirect horizontal engagement with the landing apparatus (130) by means of the winch (131), and with the component (110) in direct or indirect horizontal engagement with the landing apparatus (130), reeling in a hoisting line (140) such as to transfer a weight of the component (110) off the landing apparatus (130).

[0069] C23. The method of any preceding clause, comprising releasing the hoisting line (140) from the component (110).

[0070] C24. The method of any preceding clause, comprising: fixing a lifting yoke (132) to the component (110), and lifting and supporting the component (110) from the crane (101 ) via the lifting yoke (132).

[0071] C25. The method of any preceding clause, wherein the step of providing the component (110) at the motion compensated landing apparatus (130) comprises supporting the lifting yoke (132) at the landing apparatus (130).

[0072] C26. The method of any preceding clause, wherein the component (110) is suspended from the lifting yoke (132). C27. The method of any preceding clause, wherein the step of moving the component (110) from the position above the deck (121 ) to the position adjacent the offshore wind power plant (100) comprises: pulling the component (110) into indirect horizontal engagement with the landing apparatus (130) via the lifting yoke (132), and / or transferring a weight of the component (110) off the landing apparatus (130) via the lifting yoke (132).

[0073] C28. A motion compensated landing apparatus (130) for handling a component (110) of an offshore wind power plant (100) on a vessel (120), the landing apparatus (130) comprising: a base (133) configured to support the landing apparatus (130) on a deck (121) of the vessel (120); and a heave compensated receiver part (134), the heave compensated receiver part (134) comprising a landing face (135) for supporting the component (110).

[0074] C29. The motion compensated landing apparatus (130) according to any preceding clause, wherein the landing face (135) is configured to receive the component (110) or a lifting member, such as a lifting yoke (132), holding the component (110).

[0075] C30. The motion compensated landing apparatus (130) according to any preceding clause, wherein the heave compensated receiver part (134) is pivotable relative to the base (133) about two orthogonal horizontal axes (136,144).

[0076] C31 . The motion compensated landing apparatus (130) according to any preceding clause, comprising compensation actuators (139,145) operable to adjust the orientation of the heave compensated receiver part (134) relative to the two orthogonal horizontal axes (136,144).

[0077] C32. The motion compensated landing apparatus (130) according to any preceding clause, wherein the compensation actuators (139,145) are configured to at least partly compensate for a roll and a pitch motion of the vessel (120).

[0078] C33. The motion compensated landing apparatus (130) according to any preceding clause, wherein each of the axes (136,144) is parallel with the deck (121). C34. The motion compensated landing apparatus (130) according to any preceding clause, comprising two horizontally spaced landing faces (135) configured to receive the component (110) or a lifting member, such as a lifting yoke (132), holding the component (110).

[0079] C35. The motion compensated landing apparatus (130) according to any preceding clause, comprising two horizontally spaced compensation arms (137a,b) supporting the heave compensated receiver part (134).

[0080] C36. The motion compensated landing apparatus (130) according to any preceding clause, wherein the two horizontally spaced compensation arms (137a,b) are configured to receive the component (110) therebetween.

[0081] C37. The motion compensated landing apparatus (130) according to any preceding clause, wherein each of the two horizontally spaced landing faces (135) is arranged in conjunction with a respective horizontally spaced compensation arm (137a,b), such as located vertically above the respective horizontally spaced compensation arm (137a,b).

[0082] C38. The motion compensated landing apparatus (130) according to any preceding clause, wherein each of the two horizontally spaced compensation arms (137a,b) is independently operable.

[0083] C39. The motion compensated landing apparatus (130) according to any preceding clause, comprising a winch (131) arranged to pull the component (110) into direct or indirect engagement with the heave compensated receiver part (134).

[0084] C40. The motion compensated landing apparatus (130) according to any preceding clause, wherein the heave compensated receiver part (134) is arranged on a first part (130a) of the motion compensated landing apparatus (130) and the winch (131) is arranged on a second part (130b) of the motion compensated landing apparatus (130), the second part (130b) being separate from the first part (130a).

[0085] C41 . The motion compensated landing apparatus (130) according to any preceding clause, wherein the heave compensated receiver part (134) is configured to receive the component (110) at a first side (148) thereof, and the heave compensated receiver part (134) is pivotable about a horizontal axis (136) parallel with the deck (121 ) such as to lay down the component ( 110) at a second side ( 149) thereof. C42. The motion compensated landing apparatus (130) according to any preceding clause, wherein the heave compensated receiver part (134) is pivotable about the horizontal axis (136) such as to lay down the component (110) at a transport rack (170) at the second side (149).

[0086] C43. The motion compensated landing apparatus (130) according to any preceding clause, wherein the motion compensated landing apparatus (130) comprises two horizontally spaced compensation arms (137a,b) configured to pass the component (110) therebetween when moving the component (110) from the first side (148) to the second side (149).

[0087] C44. The motion compensated landing apparatus (130) according to any preceding clause, further comprising a guide (127), such as a wireline guide, arranged to guide a pull-in line (143)

[0088] C45. The motion compensated landing apparatus (130) according to any preceding clause, wherein the guide (127) is arranged at the heave compensated receiver part (134) and movable therewith.

[0089] C46. An assembly for handling a component (110) of an offshore wind power plant (100), the assembly comprising: the motion compensated landing apparatus (130) according to any preceding clause, a plurality of rails or tracks (171 ) configured for positioning on the deck (121) adjacent the base (133), and a transport rack (170) operable to be moved on the rails or tracks (171) while supporting the component (110) thereon.

[0090] C47. A vessel (120) for handling a component (110) of an offshore wind power plant (100), the vessel (120) comprising: the motion compensated landing apparatus (130) according to any preceding clause arranged on the deck (121 ) of the vessel (120), a plurality of rails or tracks (171) positioning on the deck (121 ), and a transport rack (170) provided on and operable to be moved on the rails or tracks (171) while supporting the component (110) thereon.

[0091] C48. The vessel (120) according to any preceding clause, wherein the transport rack (170) is movable on the rails or tracks (171 ) between a lay- down position adjacent the heave compensated receiver part (134) and a position spaced from the lay-down position.

[0092] C49. The vessel (120) according to any preceding clause, further comprising: a plurality of parking racks (172) arranged on the deck (121) adjacent the rails or tracks (171), wherein each of the parking racks (172) is configured to support the component (110) or another component (110) thereon.

[0093] C50. The vessel (120) according to any preceding clause, wherein the transport rack (170) is movable on the rails or tracks (171 ) between a lay- down position adjacent the heave compensated receiver part (134) and a position adjacent one of the plurality of parking racks (172).

[0094] C51 . The vessel (120) according to any preceding clause, wherein the transport rack (170) is movable on the rails or tracks (171 ) between a lay- down position adjacent the heave compensated receiver part (134) and a plurality of other positions, where each of the plurality of other positions is a position adjacent one of the plurality of parking racks (172).

[0095] C52. A method according to any of clauses C1 -C27, wherein: the motion compensated landing apparatus (130) is a motion compensated landing apparatus (130) according to any of clauses C28-C45, and / or the vessel (120) is a vessel (120) according to any of clauses C47- C51.

[0096] C53. A method of receiving a component (110) for an offshore wind power plant (100) at a vessel (120), the method comprising: operating a motion compensated landing apparatus (130) according to any of clauses C28-C45 at the deck (121 ) of the vessel (120); and receiving the component (110) at the motion compensated landing apparatus (130).

[0097] C54. The method of receiving a component (110) according to any preceding clause, comprising operating the motion compensated landing apparatus (130) to lay down the component (110) at a transport rack (170) provided on and operable to be moved on the deck (121). C55. The method of receiving a component (110) according to any preceding clause, wherein the transport rack (170) is operable to be moved at a plurality of rails or tracks (171 ) arranged on the deck (121 ).

[0098] C56. The method of receiving a component (110) according to any preceding clause, further comprising moving the component (110) to a parking rack (172) on the deck (121 ), for example moving the component (110) at the rails or tracks (171 ) to a parking rack (172) arranged adjacent the rails or tracks (171 ) on the deck (121).

[0099] C57. The method of receiving a component (110) according to any preceding clause, wherein the step of moving the component (110) to a parking rack (172) comprises moving the transport rack (170) to a position adjacent, such as directly adjacent, the parking rack (172), and moving, such as skidding, the component (110) off the transport rack (170) onto the parking rack (172).

[0100] C58. The method of receiving a component (110) according to any preceding clause, comprising receiving the component (110) at a first side (148) of the heave compensated receiver part (134), pivoting the heave compensated receiver part (134) about a horizontal axis (136) parallel with the deck (121 ), and laying down the component (110) at the transport rack (170) at a second side (149) of the heave compensated receiver part (134).

[0101] C59. The method of receiving a component (110) according to any preceding clause, comprising laying down the component (110) into or onto a support structure (177), for example a support structure (177) positioned at a transport rack (170).

[0102] C60. A method of providing a component (110) for an offshore wind power plant (100) from a vessel (120), the method comprising: operating a motion compensated landing apparatus (130) according to any of clauses C28-C45 at the deck (121 ) of the vessel (120); and providing the component (110) at the motion compensated landing apparatus (130).

[0103] C61 . The method of providing a component (110) according to any preceding clause, comprising operating the motion compensated landing apparatus (130) to pick up the component (110) from a transport rack (170) provided on and operable to be moved on the deck (121).

[0104] C62. The method of providing a component (110) according to any preceding clause, wherein the transport rack (170) is operable to be moved at a plurality of rails or tracks (171 ) arranged on the deck (121 ).

[0105] C63. The method of providing a component (110) according to any preceding clause, further comprising moving the component (110) from a parking rack (172) on the deck (121 ), for example moving the component (110) at the rails or tracks (171) from a parking rack (172) arranged adjacent the rails or tracks (171 ) on the deck (121).

[0106] C64. The method of providing a component (110) according to any preceding clause, wherein the step of moving the component (110) from a parking rack (172) comprises moving the transport rack (170) to a position adjacent, such as directly adjacent, the parking rack (172), and moving, such as skidding, the component (110) off the parking rack (172) onto the transport rack (170).

[0107] C65. The method of providing a component (110) according to any preceding clause, comprising picking up the component (110) from the transport rack (170) at a second side (149) of the heave compensated receiver part (134), pivoting the heave compensated receiver part (134) about a horizontal axis (136) parallel with the deck (121), and providing the component (110) at a first side (148) of the heave compensated receiver part (134).

[0108] C66. The method of providing a component (110) according to any preceding clause, comprising picking up the component (110) from a support structure (177), for example a support structure (177) positioned at a transport rack (170).

[0109] The invention is not limited by the embodiments described above; reference should be had to the appended claims.

Claims

CLAIMS1 . A method of removing a component (1 10) from an offshore wind power plant (100), the method comprising: arranging a crane (101 ) at a top part (100a) of the offshore wind power plant (100); operating the crane (101 ) to lift the component (110) off the offshore wind power plant (100); lowering the component (110) adjacent the offshore wind power plant (100) while supporting the component (110) by the crane (101 ) via at least one hoisting line (140); moving the component (1 10) horizontally to a position above a deck (121 ) of a vessel (120) by pulling the component (1 10) towards the vessel (120) by means of a winch (131 ) arranged on the vessel (120), while supporting the component (1 10) by the crane (101 ); and landing the component (110) at a motion compensated landing apparatus (130) arranged on the deck (121 ) and transferring a weight of the component (110) to the landing apparatus (130).

2. The method of claim 1 , wherein the step of operating the crane (101 ) to lift the component (1 10) off the offshore wind power plant (100) comprises lifting the component (1 10) out of a nacelle structure (150) of the offshore wind power plant (100).

3. The method of any preceding claim, wherein the step of lowering the component (110) comprises lowering the component (1 10) vertically along and adjacent a tower (111 ) of the offshore wind power plant (100) with the component (110) suspended substantially freely from the crane (101 ) via the at least one hoisting line (140).

4. The method of any preceding claim, wherein the step of lowering the component (110) comprises lowering the component (1 10) vertically a distance which is at least 90% of a height of the tower (1 11 ).

5. The method of any preceding claim, wherein the step of lowering the component (110) comprises lowering the component to a position which is horizontally adjacent a base (103) of the offshore wind power plant (100).

6. The method of any preceding claim, wherein the step of lowering the component (110) is carried out prior to the step of moving the component (110) to the position above the deck (121).

7. The method of any preceding claim, wherein the step of landing the component (110) comprises: pulling the component (110) into direct or indirect horizontal engagement with the landing apparatus (130) by means of the winch (131), and with the component (110) in direct or indirect horizontal engagement with the landing apparatus (130), paying out the at least one hoisting line (140) such as to transfer the weight of the component (110) to the landing apparatus (130).

8. The method of any preceding claim, comprising: fixing a lifting yoke (132) to the component (110), lifting and supporting the component (110) from the crane (101 ) via the lifting yoke (132), and wherein the step of landing the component (110) comprises bringing the lifting yoke (132) into engagement with the landing apparatus (130).

9. The method of claim 8, wherein the step of landing the component (110) comprises: bringing the component (110) into indirect horizontal engagement with the landing apparatus (130) via the lifting yoke (132), and transferring the weight of the component (110) to the landing apparatus (130) via the lifting yoke (132).

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