GB2642093A

GB2642093A - Power cable guide means, system and method with the same

Info

Publication number: GB2642093A
Application number: GB2409065.6A
Authority: GB
Inventors: De Araujp Bernardo Leonardo; Correa De Oliviera Guliherme
Original assignee: Technip UK Ltd
Current assignee: Technip UK Ltd
Priority date: 2024-06-25
Filing date: 2024-06-25
Publication date: 2025-12-31
Also published as: GB202409065D0; WO2026003029A1

Abstract

A power cable guide means end piece 100 for an offshore structure power cable guide means 20, the guide means is securable to the offshore structure 10 and configured to guide a power cable 30 from a body of water 40 to a position to be connected to the offshore structure, the power cable guide means end piece is elongate and has an upper end 110 that is part of or secured to the guide means, and a free end 120 for receiving the power cable, the power cable guide means end piece has a flexible portion 130 which is increasingly flexible in a longitudinal direction towards the free end, and that the internal diameter of the flexible portion is greater at the free end than at the upper end, i.e. is conical or tapered flexible end. The flexible portion may comprise metallic strips 160 (Figure 2). The end piece may comprise a first solid walled portion 140 and a second solid walled portion 150 (Figure 3)

Description

[0001] POWER CABLE GUIDE MEANS, SYSTEM AND METHOD WITH THE SAME

[0002] Technical Field

[0003] The present disclosure relates generally to bend control and impact absorption for power cables in the field of offshore structures and more generally to the renewable energy industry. More specifically, the present invention relates to a power cable guide means end piece for an offshore floating platform power cable guide means; an offshore power cable guide unit with such a power cable guide means end piece; a system for increasing a service life of a power cable attached to an offshore platform comprising the power cable guide means end piece; an offshore floating platform having the offshore power cable guide unit; and a method for installing a power cable on an offshore floating platform.

[0004] Background

[0005] An offshore structure producing energy has normally at least a power cables connected to the offshore structure. The power cable is protected against impact, abrasion, fatigue, and damaging movement such as over-bending at vulnerable locations. Such protection of the power cable is particularly important for floating offshore wind turbines which use dynamic cables to enable movement. Cable protection systems including topside and subsea bend control, are used to reduce costs involved with maintaining, repairing or replacing cables. Power cable protection systems help to preserve the cables at vulnerable locations from wave and current action. How to protect a power cable is a problem, especially in shallow waters. The use of an I-tube in shallow waters increases complexity and reduces the life of the power cable, especially for places with extreme weathers and dynamic environment.

[0006] Increasing flexibility, such as increasing floater excursion, especially in shallow waters, is a problem.

[0007] Bend stiffeners impact costs on transportation, handling, and installation, are expensive, and increase the temperature on the power cable. Bend stiffener connections are complex and expensive. A bellmouth address these problems, but introduces other problems. The bend stiffener is large and cumbersome to handle and to install. It is desirable to be able to exclude the bend stiffener and the bellmouth.

[0008] To achieve good protection and a power cable protection system that works well with existing equipment is also a problem. It is desirable to provide a cable protection system and method that is inexpensive to manufacture, is easy to manufacture and assemble, and is robust and reliable in use. The present disclosure is directed to overcoming one or more of the problems as set forth above.

[0009] SUMMARY

[0010] It is an objective of the present invention to provide a power cable guide means end piece for an offshore floating platform power cable guide means; an offshore power cable guide unit with such a power cable guide means end piece; a system for increasing a service life of a power cable attached to an offshore platform comprising the power cable guide means end piece; an offshore floating platform having the offshore power cable guide unit; and a method for installing a power cable on an offshore floating platform. This objective can be achieved by the features as defined in the independent claims. Further characteristics are defined by the dependent claims.

[0011] According to one embodiment, a power cable guide means end piece 100 for an offshore structure power cable guide means 20 is provided. The guide means 20 is securable to the offshore structure 10 and configured to guide a power cable 30 from a body of water 40 to a position to be connected to the offshore structure 10. The power cable guide means end piece 100 being elongate and having an upper end 110 that is part of, or secured to, the guide means 20, and a free end 120 for receiving the power cable 30 from the body of water 40. The power cable guide means end piece 100 has at least a flexible portion 130 which is increasingly flexible in a longitudinal direction towards the free end 120, and the internal diameter of the flexible portion 130 is greater at the free end 120 than at the upper end 110. The end piece 100 of the power cable guide means 20 may be used without a bend stiffener or a bend stiffener connector, or without a bellmouth. The power cable guide means end piece 100 is not a bend stiffener or bellmouth. The power cable guide means end piece 100 may comprise stiffness similar to a bend stiffener and control curvature similar to a rigid bellmouth.

[0012] The flexible portion 130 may comprises a conical shape from the upper end to the free end 120, for example like a bell-shaped free end 120. The flexible portion 130 may comprises a cylindrical shape or any other shape. The power cable guide means end piece 100 may comprise a flared-shaped free end 120. The power cable guide means end piece 100 may comprise, in a longitudinal direction, a first solid-walled portion 140, and a second flexible portion 150. The flexible portion 130 may comprise a series of elongate metallic strips 160. The power cable guide means end piece 100 may comprise two or more material layers 140, 150. At least one material layer may be a polymeric layer 150.

[0013] According to one embodiment, an offshore power cable guide unit is disclosed. The offshore power cable guide unit comprises an offshore structure power cable guide means 20 securable to an offshore structure 10 and configured to guide a power cable 30 from a body of water 40 to a position to be connected to the offshore structure 10. The offshore structure power cable guide means 20 comprises an I-tube, a U-tube, or a balcony hang-off. The offshore power cable guide unit further comprising a power cable guide means end piece 100 as defined herein. The offshore power cable guide unit comprises the guide means 20 and the power cable guide means end piece 100. They may be attached to each other directly, i.e. without any additional means therebetween. The power cable guide means end piece 100 may be positioned under water or in air and it may be attached to a main structure onshore or offshore.

[0014] According to one embodiment, a system for increasing a service life of a power cable 30 attached to an offshore structure 10, is disclosed. The system comprises: an offshore structure power cable guide means 20, the guide means 20 being securable to the offshore structure 10 and configured to guide the power cable 30 from a body of water 40 to a position to be connected to the offshore structure 10; a power cable guide means end piece 100 having an upper end 110 that is part of or secured to the guide means 20, and a free end 120 for receiving the power cable 30; a power cable 30 having a first portion of length arranged mainly vertically along the offshore structure 10, and a second portion of length deviating out from the offshore structure 10 to extend through the body of water, wherein a transition area 34 between the first and second portions of length defines a main fatigue region. The power cable guide means end piece 100 further comprises a flexible portion 130 engageable with the transition area 34 of the power cable 30, which flexible portion is increasingly flexible in a longitudinal direction towards the free end 120, and that the internal diameter of the flexible portion is greater at the free end 120 than at the upper end 110.

[0015] The system may comprise the power cable guide means end piece 100 is as described herein. The system may comprise that the offshore structure power cable guide means 20 and the power cable guide means end piece 100 form an offshore power cable guide unit comprising an I-tube, a J-tube, or a balcony hang-off.

[0016] The system may comprise that the smallest internal diameter of the cable guide means end piece 100 is larger than a diameter of the power cable 30, and may further comprise a pull-in means 70 connectable to an end of the power cable 30 allowing the power cable 30 to be pulled through the cable guide means end piece 100 and the offshore structure power cable guide means 20. The cable guide means end piece 100 may be an integral part, fully machined or fabricated as a single piece, or it may be split into two or more parts to allow other installation methods in addition to pull-in.

[0017] According to one embodiment, an offshore structure 10 comprises an offshore power cable guide unit as defined herein is disclosed. According to one embodiment, an offshore structure 10 comprises the system as described herein. The offshore structure 10 according to any one of these embodiments may comprise a wind turbine 60.

[0018] According to one embodiment, a method for installing a power cable 30 on an offshore structure 10 as described herein is disclosed. The method comprises at least the steps of: pulling the power cable 30 through the power cable guide means end piece 100 and the offshore structure power cable guide means 20 from a body of water 40 to a position to be connected to an offshore structure 10; and connecting the power cable 30 to a connection point on the offshore structure 10.

[0019] One or more of the embodiments described herein describes a power cable guide means end piece, a system, and a method whereby a power cable is protected against impact, abrasion, fatigue, and damaging movement, such as over-bending at vulnerable locations. At least one embodiment provides protection of the power cable for a floating offshore structure, for example with a wind turbine, which use dynamic cables to enable movement. At least one embodiment can be used independently of other systems or equipment. At least one embodiment prolongs the usable life of the power cable. At least one embodiment allows that no use of a bend stiffener or a bellmouth is required.

[0020] At least one of the above embodiments provides one or more solutions to the problems and disadvantages with the background art. Other technical advantages of the present disclosure will be readily apparent to one skilled in the art from the following description and claims. Various embodiments of the present application obtain only a subset of the advantages set forth. No one advantage is critical to the embodiments. Any claimed embodiment may be technically combined with any other claimed embodiment or embodiments.

[0021] Brief Description of the Drawings

[0022] The disclosure will be further described with reference to examples depicted as schematic illustrations in the accompanying figures in which: FIG. 1 is a schematic illustration of an offshore structure with the system and the power cable guide means end piece according to an embodiment of the invention; FIG. 2 is a schematic illustration of the power cable guide means end piece according to an embodiment of the invention; and FIG. 3 is a schematic illustration of cuts through the power cable guide means end piece according to an embodiment of the invention.

[0023] Detailed Description

[0024] Embodiments of the present invention illustrate in figures 1 to 3 a power cable guide means end piece for an offshore floating platform power cable guide means; an offshore power cable guide unit with such a power cable guide means end piece; a system for increasing a service life of a power cable attached to an offshore platform comprising the power cable guide means end piece; an offshore floating platform having the offshore power cable guide unit; and a method for installing a power cable on an offshore floating platform. Figure 1 is a schematic illustration of an example of the offshore structure, power cable, wind turbine, power cable guide means end piece 100, and offshore structure power cable guide means 20 on one side and a hang-off balcony 15 with a power cable guide means end piece 100 on the other side. Figure 2 is a schematic illustration of the power cable guide means end piece 100 according to an embodiment of the invention when it is detached from the offshore structure power cable guide means 20. Figure 3 is a schematic illustration of a cut along an axis of the power cable guide means end piece 100 according to an embodiment of the invention, and three cuts perpendicular to the axis of power cable guide means end piece 100. For a better understanding, the figures have not been made to scale.

[0025] Figures 1 to 3 illustrate a power cable guide means end piece 100 for an offshore structure power cable guide means 20. The guide means 20 is securable to the offshore structure 10 and configured to guide a power cable 30 from a body of water 40 to a position to be connected to the offshore structure 10. The power cable guide means end piece 100 being elongate and having an upper end 110 that is part of, or secured to, the guide means 20, and a free end 120 for receiving the power cable 30 from the body of water 40. The power cable guide means end piece 100 has at least a flexible portion 130 which is increasingly flexible in a longitudinal direction towards the free end 120, and the internal diameter of the flexible portion 130 is greater at the free end 120 than at the upper end 110. The power cable guide means end piece 100 may comprise a complete circular cross section perpendicular to its axis, or may comprise two semi-circular cross sections that are fitted together to form one complete power cable guide means end piece 100. The end piece 100 of the power cable guide means 20 may be used preferably without a bend stiffener and may be used without a bellmouth. The power cable guide means end piece 100 is not a bend stiffener or bellmouth.

[0026] The guide means 20 may be an I-tube, or a J-tube, or a balcony hang-off. The end piece 100 here fore may be directly connected to the guide means 20, without any extra means between the two. The flexible portion 130 provides a gradual stiffness transition between the power cable 30 and the stiffer steel structure of the guide means 20, and the flexible portion 130 absorbs bending moments and shear forces. No bend stiffener or bellmouth needs to be used. This eliminates problems from use of a bend stiffener and/or a bellmouth, such as increased temperature on the power cable, handling and packing limitations of the power cable, bend stiffener, and bellmouth, and high cost and complexity of the connector for the bend stiffener. As best illustrated in figures 2 and 3, a fanged or welded flexible portion 130 may be attached to the bottom of the guide means 20, or the hang-off balcony 15. Based on the design, the stiffness of the joint will gradually move from flexible at the free end 120 of the funnel to a very stiff cone at the upper end 110. A polymeric liner 150 can be introduced inside to increase the fatigue life and eliminate problems with wear of the power cable 30 in contact with the solid portion 140 or the hard surface of the guide means 20. Figures 1 to 3 illustrate an example how the power cable guide means end piece 100 works with the offshore structure, and how the diameters and thickness are changing, especially the thickness of the steel material 140 and the flexible material 150, and how the design illustrated in figures 2 and 3 may move from flexible to stiff, having at least a flexible portion 130 which is increasingly flexible in a longitudinal direction towards the free end 120 and is stiff at the upper end 110.

[0027] On the left-hand side of the offshore structure 10 is a further example of the power cable guide means end piece 100 arranged on a hang-off balcony 15. In this example the power cable guide means end piece 100 hangs in the air and the power cable 30 extends from the body of water 40 up through the power cable guide means end piece 100 to the hang-off balcony 15. The hang-off balcony may comprise an opening through which the power cable 30 may extend to a position to be connected to the offshore structure 10. The example shown on the left-hand side is in principle similar to the right-hand example.

[0028] As best illustrated in figures 2 and 3, the flexible portion 130 may comprises a conical shape from the upper end 110 to the free end 120, for example like a bell-shaped free end 120. The power cable guide means end piece 100 may comprise a flared-shaped free end 120. The power cable guide means end piece 100 may comprise, in a longitudinal direction, a first solid-walled portion 140, and a second flexible portion 150. The flexible portion 130 may comprise a series of elongate metallic strips 160. The power cable guide means end piece 100 may comprise two or more material layers 140, 150. At least one material layer may be a polymeric layer 150.

[0029] The power cable guide means end piece 100 may comprise a complete circular cross section perpendicular to its axis, or may comprise two semi-circular cross sections that are fitted together to form one complete power cable guide means end piece 100. The two parts may allow the power cable guide means end piece 100 to be split, along its axis, allowing the power cable 30 to be inserted from the side. Subsequently the power cable guide means end piece 100 may be closed surrounding the power cable 30 inside.

[0030] The power cable guide means end piece 100 may comprise at least two different material layers 140, 150. One of the material layer 150 may be on the inside of the power cable guide means end piece 100 and the other material layer 140 may be on the outside thereof. The inner material layer 150 may be a polymeric layer 150. The inner material layer 150 may stretch circumferentially on the inside, from the free end 120 and up to the upper end 110. The flexible portion 130 may extend from the free end 120 and towards the upper end 110. The flexible portion 130 may extend from the free end 120 to about half to four fifths of the entire length of the power cable guide means end piece 100. The inner material layer 150 may be thicker closer to the free end 120 and thinner closer to the upper end 110. The flexible portion may comprise, in addition to the inner material layer 150, a series of elongate metallic strips 160 and in between the elongate metallic strips 160 there may be a series of elongate flexible strips 170. This is best illustrated in figures 2 and

[0031] B

[0032] 3. The series of elongate flexible strips 170 may polymeric elongate flexible strips 170. These strips may be along the entire flexible portion 130. The width of each elongate metallic strip 160 may be larger than the width of each elongate flexible strip 170.

[0033] The upper end 110 may comprise a flange for connecting the power cable guide means end piece 100 directly to the guide means 20. The flange may be made out of steel. The power cable guide means end piece 100 may have the shape of a truncated cone, with the two planes of the frustum going through the free end 120 and the upper end 110, respectively. The power cable guide means end piece 100 may be one continuous body with the two layers 140, 150 being continuous and forming the power cable guide means end piece 100.

[0034] According to one embodiment, an offshore power cable guide unit is disclosed by figures 1 to 3. The offshore power cable guide unit comprises an offshore structure power cable guide means 20 securable to an offshore structure 10 and configured to guide a power cable 30 from a body of water 40 to a position to be connected to the offshore structure 10. The offshore structure power cable guide means 20 comprises an I-tube, a J-tube, or a balcony hang-off. The offshore power cable guide unit further comprising a power cable guide means end piece 100 as defined herein. The offshore power cable guide unit comprises the guide means 20 and the power cable guide means end piece 100. They may be attached to each other directly, i.e. without any additional means therebetween. The power cable guide means end piece 100 may be integrated and part of, for example permanently fixed to, the guide means 20. The offshore power cable guide unit may be prefabricated and subsequently attached to the offshore structure 10.

[0035] According to one embodiment, a system for increasing a service life of a power cable 30 attached to an offshore structure 10, is disclosed. The system comprises: an offshore structure power cable guide means 20, the guide means 20 being securable to the offshore structure 10 and configured to guide the power cable 30 from a body of water 40 to a position to be connected to the offshore structure 10; a power cable guide means end piece 100 having an upper end 110 that is part of or secured to the guide means 20, and a free end 120 for receiving the power cable 30; a power cable 30 having a first portion of length arranged mainly vertically along the offshore structure 10, and a second portion of length deviating out from the offshore structure 10 to extend through the body of water, wherein a transition area 34 between the first and second portions of length defines a main fatigue region. The power cable guide means end piece 100 further comprises a flexible portion 130 engageable with the transition area 34 of the power cable 30, which flexible portion is increasingly flexible in a longitudinal direction towards the free end 120, and that the internal diameter of the flexible portion is greater at the free end 120 than at the upper end 110. The system reduces impact, abrasion, fatigue, and damaging movement such as over-bending at the transit area 34, i.e. the fatigue region. This protection of the power cable 30 of especially relevant for floating wind turbines with I-or J-tubes which use dynamic cables to enable movement in shallow waters. The power cable guide means end piece 100 may be any power cable guide means end piece 100 as mentioned herein. The offshore structure power cable guide means 20 and the power cable guide means end piece 100 may form an offshore power cable guide unit comprising an I-tube, a J-tube, or a balcony hang-off.

[0036] According to one embodiment, the smallest internal diameter of the cable guide means end piece 100 may be larger than a diameter of the power cable 30 and/or a pull head connected to the end of the power cable 30. The power cable 30 may run freely through the cable guide means end piece 100. There may be a predefined play between the power cable 30 and the smallest internal diameter of the cable guide means end piece 100. The system may further comprise a pull-in means 70 connectable to an end of the power cable 30 allowing the power cable 30 to be pulled through the cable guide means end piece 100 and the offshore structure power cable guide means 20. This allows the power cable to be installed from the body of water, through the cable guide means end piece 100, up onto the offshore structure. The pull-in means 70 may be a crane or a davit, including a winch and may be arranged on the offshore structure 10 or an installation vessel. In the example where the cable guide means end piece 100 is split in two parts, then the power cable 30 may be brought in from the side and then subsequently close the cable guide means end piece 100 around the power cable 30.

[0037] According to one embodiment, an offshore structure 10 comprises an offshore power cable guide unit as defined herein is disclosed. According to one embodiment, an offshore structure 10 comprises the system as described herein.

[0038] The offshore structure 10 according to any one of these embodiments may comprise a wind turbine 60.

[0039] According to one embodiment, a method for installing a power cable 30 on an offshore structure 10 as described herein is disclosed. The method comprises at least the steps of: pulling the power cable 30 through the power cable guide means end piece 100 and the offshore structure power cable guide means 20 from a body of water 40 to a position to be connected to an offshore structure 10; and connecting the power cable 30 to a connection point on the offshore structure 10.

[0040] It will be apparent to those skilled in the art that various modifications and variations can be made to the power cable guide means end piece, the systems, the offshore structure, and method. At least one embodiment allows to exclude a bend stiffener and a bellmouth, i.e. embodiments described herein replace both the bend stiffener and the bellmouth. One or more of the embodiments described herein describes a power cable guide means end piece, a system, and a method whereby a power cable is protected against impact, abrasion, fatigue, and damaging movement, such as over-bending at vulnerable locations. At least one embodiment provides protection of the power cable for a floating offshore structure, for example with a wind turbine, which use dynamic cables to enable movement. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed system and method. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.

Claims

1. CLAIMS1. A power cable guide means end piece (100) for an offshore structure power cable guide means (20), the guide means (20) being securable to the offshore structure (10) and configured to guide a power cable (30) from a body of water (40) to a position to be connected to the offshore structure (10), the power cable guide means end piece (100) being elongate and having an upper end (110) that is part of or secured to the guide means (20), and a free end (120) for receiving the power cable (30) from the body of water (40); characterised in that power cable guide means end piece (100) has at least a flexible portion (130) which is increasingly flexible in a longitudinal direction towards the free end (120), and that the internal diameter of the flexible portion (130) is greater at the free end (120) than at the upper end (110).

2. The power cable guide means end piece (100) wherein the flexible portion (130) comprises a conical shape from the upper end (110) to the free end (120), a bell-shaped free end (120).

3. The power cable guide means end piece (100) according to claim 1 or 2, comprising a flared-shaped free end (120).

4. The power cable guide means end piece (100) according to any one of the preceding claims, comprising in a longitudinal direction a first solid-walled portion (140), and a second flexible portion (150).

5. The power cable guide means end piece (100) according to any one of the preceding claims, wherein the flexible portion (130) comprises a series of elongate metallic strips (160).

6. The power cable guide means end piece (100) according to any one of the preceding claims comprising two or more material layers (140, 150).

7. The power cable guide means end piece (100) according to claim 6 wherein at least one layer (150) is a polymeric layer.

8. An offshore power cable guide unit comprising an offshore structure power cable guide means (20) securable to an offshore structure (10) and configured to guide a power cable (30) from a body of water (40) to a position to be connected to the offshore structure (10), the offshore structure power cable guide means (20) comprising an I-tube, a J-tube, or a balcony hang-off; and the offshore power cable guide unit further comprising a power cable guide means end piece (100) as defined in any one of claims 1 to 7.

9. A system for increasing a service life of a power cable (30) attached to an offshore structure (10), the system comprising: an offshore structure power cable guide means (20), the guide means (20) being securable to the offshore structure (10) and configured to guide the power cable (30) from a body of water (40) to a position to be connected to the offshore structure (10); a power cable guide means end piece (100) having an upper end (110) that is part of or secured to the guide means (20), and a free end (120) for receiving the power cable (30); a power cable (30) having a first portion of length arranged mainly vertically along the offshore structure (10), and a second portion of length deviating out from the offshore structure (10) to extend through the body of water; wherein a transition area (34) between the first and second portions of length defines a main fatigue region; and wherein the power cable guide means end piece (100) further comprises a flexible portion (130) engageable with the transition area (34) of the power cable (30), which flexible portion is increasingly flexible in a longitudinal direction towards the free end (120), and that the internal diameter of the flexible portion is greater at the free end (120) than at the upper end (110).

10. The system as claimed in claim 10 wherein the power cable guide means end piece (100) is as defined in any one of claims 1 to 7.

11. A system as claimed in claim 9 or claim 10 wherein the offshore structure power cable guide means (20) and the power cable guide means end piece (100) form an offshore power cable guide unit comprising an I-tube, a J-tube, or a balcony hang-off.

12. The system as claimed in any one of claims 9 to 11 wherein the smallest internal diameter of the cable guide means end piece (100) is larger than a diameter of the power cable (30), and the system further comprising a pull-in means (70) connectable to an end of the power cable (30) allowing the power cable (30) to be pulled through the cable guide means end piece (100) and the offshore structure power cable guide means (20).

13. An offshore structure (10) comprising an offshore power cable guide unit as defined in claim 8.

14. An offshore structure (10) comprising the system as claimed in any one of the claims 9 to 12 and further comprising a wind turbine (60).

15. A method for installing a power cable (30) on an offshore structure (10) as defined in claim 13 or 14, comprising at least the steps of: pulling the power cable (30) through the power cable guide means end piece (100) and the offshore structure power cable guide means (20) from a body of water (40) to a position to be connected to an offshore structure (10); and connecting the power cable (30) to a connection point on the offshore structure (10).