US-12620788-B2 - Submarine cable system and method for laying a submarine cable system

US12620788B2US 12620788 B2US12620788 B2US 12620788B2US-12620788-B2

Abstract

A submarine cable system includes a submarine cable with two energy lines between two distal ends. An energy line includes a stranded wire and an insulation layer surrounding the stranded wire. The two energy lines are guided in a common metallic reinforcement surrounded by an outer insulation layer. A first section of the submarine cable is formed starting from a first of the distal ends of the submarine cable to a transition region. A second section is formed starting from the transition region to a second of the distal ends of the submarine cable. A sleeve-shaped transition piece has through opening with the transition region disposed within the through opening. A cable duct has an opening formed to receive the transition piece such that an outer shell surface of the transition piece abuts an inner shell surface of the cable duct in the region of the opening.

Inventors

Stefan Dominguez Ebitsch
Sebastian Obermeyer

Assignees

Stefan Dominguez Ebitsch
Sebastian Obermeyer

Dates

Publication Date: 20260505
Application Date: 20240508
Priority Date: 20211130

Claims (13)

1 . Submarine cable system comprising: a submarine cable with at least two energy lines guided between two distal ends of the submarine cable, wherein each respective energy line comprises a stranded wire, and at least one insulation layer surrounding the stranded wire, and the two energy lines are guided in a common metallic reinforcement and an outer insulation layer surrounding the metallic reinforcement, and wherein a first section of the submarine cable is formed starting from a first of the distal ends of the submarine cable up to a transition region, wherein in the first section the energy lines are guided in the metallic reinforcement and the outer insulation layer surrounding the metallic reinforcement, and a second section of the submarine cable is formed starting from the transition region up to a second of the distal ends of the submarine cable, wherein in the second section the energy lines are free of the metallic reinforcement and the outer insulation layer surrounding the metallic reinforcement, a sleeve-shaped transition piece having a through opening, wherein the transition region is disposed within the through opening, wherein a cable duct is provided, wherein at a first end of the cable duct an opening of the cable duct is formed to receive the transition piece such that an outer shell surface of the transition piece abuts an inner shell surface of the cable duct in the region of the opening; and wherein at a second end of the cable duct, opposite the first end, the cable duct is configured to provide connection to a connection bracket of an onshore station or transition joint bay.
2 . Submarine cable system of claim 1 , wherein the transition piece has a flange-like radial projection.
3 . Submarine cable system of claim 2 , wherein the flange-like projection abuts against an end face of the cable duct.
4 . Submarine cable system of claim 1 , wherein the transition piece is formed in two parts, the two parts being attached to one another by a respective projection.
5 . Submarine cable system of claim 1 , wherein an outer lateral surface of the transition piece is fixed to an inner lateral surface of the cable duct in a force-locking and/or form-locking manner.
6 . Submarine cable system of claim 5 , wherein radial projections on the outer lateral surface of the transition piece engage in radial recesses on the inner lateral surface of the cable duct.
7 . Submarine cable system of claim 1 , wherein the reinforcement is fastened to the transition piece in a force-fitting and/or form-fitting manner.
8 . Submarine cable system of claim 7 , wherein the force-fitting and/or form-fitting manner is a clamping manner.
9 . Submarine cable system of claim 1 , wherein the submarine cable is guided with its first section starting from an offshore station to the transition piece, is guided through the transition piece into the cable duct and is guided with its second section within the cable duct underground to the onshore station/transition joint bay (TJB).
10 . Submarine cable system of claim 1 , wherein the cable duct is at least partially a horizontal bore duct.
11 . Submarine cable system comprising: a submarine cable with at least two energy lines guided between two distal ends of the submarine cable, wherein each respective energy line comprises a stranded wire, and at least one insulation layer surrounding the stranded wire, and the two energy lines are guided in a common metallic reinforcement and an outer insulation layer surrounding the metallic reinforcement, and wherein a first section of the submarine cable is formed starting from a first of the distal ends of the submarine cable up to a transition region, wherein in the first section the energy lines are guided in the metallic reinforcement and the outer insulation layer surrounding the metallic reinforcement, and a second section of the submarine cable is formed starting from the transition region up to a second of the distal ends of the submarine cable, wherein in the second section the energy lines are free of the metallic reinforcement and the outer insulation layer surrounding the metallic reinforcement, a sleeve-shaped transition piece having a through opening, wherein the transition region is disposed within the through opening, wherein a cable duct is provided, wherein an opening of the cable duct is formed to receive the transition piece such that an outer shell surface of the transition piece abuts an inner shell surface of the cable duct in the region of the opening; wherein the transition piece is formed in two parts, the two parts being attached to one another by a respective projection, wherein the first part of the transition piece extends towards the first section of the submarine cable, and that the second part of the transition piece extends towards the second section of the submarine cable.
12 . Method of laying a submarine cable system comprising: a submarine cable system comprising: a submarine cable with at least two energy lines guided between two distal ends of the submarine cable, wherein each respective energy line comprises a stranded wire, and at least one insulation layer surrounding the stranded wire, and the two energy lines are guided in a common metallic reinforcement and an outer insulation layer surrounding the metallic reinforcement, and wherein a first section of the submarine cable is formed starting from a first of the distal ends of the submarine cable up to a transition region, wherein in the first section the energy lines are guided in the metallic reinforcement and the outer insulation layer surrounding the metallic reinforcement, and a second section of the submarine cable is formed starting from the transition region up to a second of the distal ends of the submarine cable, wherein in the second section the energy lines are free of the metallic reinforcement and the outer insulation layer surrounding the metallic reinforcement, a sleeve-shaped transition piece having a through opening, wherein the transition region is disposed within the through opening, wherein a cable duct is provided, wherein an opening of the cable duct is formed to receive the transition piece such that an outer shell surface of the transition piece abuts an inner shell surface of the cable duct in the region of the opening, wherein the submarine cable is assembled onshore with the first and second sections, the first section is mechanically and electrically connected to an offshore station, the submarine cable with the transition region is inserted into the through opening of the transition piece, the reinforcement of the submarine cable is mechanically fixed to the transition piece, and the submarine cable with the second section is guided starting from the transition piece at least partially through the buried cable duct towards an onshore station/transition joint bay (TJB).
13 . Method of claim 12 , wherein the submarine cable is inserted onshore with the transition section into the through-opening of the transition piece and meanwhile the reinforcement of the submarine cable is mechanically fixed onshore to the transition piece.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS This patent application is a continuation of International Application No. PCT/EP2022/081758, filed on Nov. 14, 2022, which claims the benefit of priority to German Patent Application No. 10 2021 131 422.4, filed Nov. 30, 2021, the entire teachings and disclosures of both applications are incorporated herein by reference thereto. FIELD OF THE INVENTION The subject matter relates to a submarine cable system and a method for laying such a submarine cable system. BACKGROUND OF THE INVENTION Due to the increasing expansion of electrical power generation on the high seas (offshore), electrical submarine cables are also increasingly being laid between an offshore plant and an onshore plant. Usually, several generation plants, for example wind turbines, are connected offshore to a transformer station, also called a sub-station. Starting from this sub-station, the electrical energy generated by the generation plants is transmitted via an electrical submarine cable to an onshore plant. Via the onshore plant, the electrical energy is fed into the electrical grid. On the one hand, submarine cables must be able to transport high electrical power. Therefore, they must have a large current carrying capacity. This leads to considerable conductor cross-sections in the electrical energy lines. Furthermore, the submarine cables are subjected to high mechanical loads, so that appropriate mechanical protection must be provided. This can be mechanical protection against tensile, shear, bending, torsional or other forces. Such protection is usually provided by metallic reinforcement. One or more reinforcement layers may be provided in a submarine cable for this purpose. In addition, submarine cables are usually exposed to salt water, which is highly corrosive. The strands of the energy lines must also be protected against this, so various insulation layers are provided to prevent the ingress of seawater or the diffusion of seawater as completely as possible. These two requirements for both mechanical stability and stability against environmental influences run counter to the need to carry high electrical power in the submarine cable. On the one hand, the high electrical powers cause the strands to heat up due to ohmic losses. These ohmic losses are minimized as far as possible by selecting the cable cross-section as large as possible and by using a metal with a high conductivity value, such as aluminum, copper or a copper alloy. On the other hand, however, when the submarine cable is used as an AC line, induced currents occur within the reinforcement due to the metallic reinforcement. These induced eddy currents also generate ohmic losses in the reinforcement. Both lead to thermal losses and, consequently, heating of the cable. The thermal losses along the submarine cable are usually well dissipated by the surrounding water and/or the seabed, so that sufficient heat dissipation of the submarine cable is provided, even when very high electrical powers are transmitted. As mentioned above, the submarine cable is routed to an onshore installation (station). For this purpose, the submarine cable is nowadays transferred to an underground cable duct near the coast at a transition point. Such a cable duct, often designed as HDD (Horizontal Directional Drilling) Duct, runs underground from the transition point of the submarine cable to the onshore facility or Transition Joint Bay (TJB), where the transition to the onshore cable takes place. The cable duct is often empty (the cable is surrounded by air), but can be filled with fill material, usually grout or another fill material, preferably mineral, to improve the thermal conductivity of the cable. The plastic tube results in additional thermal insulation of the submarine cable. The lack of water and the harsher conditions (cables installed very deep, possibly surrounded by air in plastic pipes) results in the submarine cable not being cooled as well as it would be if it were installed underwater or in the seabed. Overall, this type of installation onshore results in the maximum power that can be transmitted by the submarine cables being limited compared to installing the submarine cables exclusively underwater/in the seabed. To compensate for these disadvantages, nowadays either electrical power transmitted via the submarine cable has to be throttled or the cable cross-sections have to be significantly increased. Both result in considerable additional costs. SUMMARY OF THE INVENTION The subject matter was based on the object of increasing the maximum current carrying capacity of a laid submarine cable. This object is solved by a submarine cable system and a method according to the claims listed below. A submarine cable according to the subject matter has two distal ends. At least two energy lines extend between these two distal ends. Preferably, however, more than two, in particular three, four or five energy lines may be routed within a su