EP4163931A1

EP4163931A1 - High-voltage dynamic submarine cable

Info

Publication number: EP4163931A1
Application number: EP20948042.5A
Authority: EP
Inventors: Haitao Wang; Pan Pan; Airong PAN; Ming Hu; Shuhong XIE
Original assignee: Zhongtian Technology Submarine Cable Co Ltd
Current assignee: Zhongtian Technology Submarine Cable Co Ltd
Priority date: 2020-08-04
Filing date: 2020-11-05
Publication date: 2023-04-12
Also published as: WO2022027849A1; CN111883310A; CN111883310B; EP4163931A4

Abstract

A high-voltage dynamic submarine cable, comprising an electric unit, an optical unit (8), a filling strip, an inner sheath (9), an armor layer (10) and an outer sheath (11). The electric unit, the optical unit (8) and the filling strip are intertwisted to form a submarine cable core, and the submarine cable core is wrapped with the inner sheath (9) and the outer sheath (11); the armor layer (10) is arranged between the inner sheath (9) and the outer sheath (11); the electric unit comprises a conductor (1); a co-extrusion structure layer (2), a water-blocking buffer layer (3), a corrugated copper sleeve (4) and a split-phase sheath (5) are sequentially wrapped outside the conductor (1); a plurality of annular or threaded relief structures are rolled on the outer side face of the corrugated copper sleeve (4) in the axial direction; and the water-blocking buffer layer (3) and the split-phase sheath (5) are in contact with and fill the relief structures on the corrugated copper sleeve (4). The submarine cable has an excellent radial water blocking effect, guarantees normal use of an ultra-clean high-voltage insulating material in deep and far-sea, high-salinity and high-water-pressure environments, provides guarantee for reliable operation of a floating booster station of future floating wind fields, and guarantees the use function of the high-voltage dynamic submarine cable.

Description

FIELD

The present application relates to the technical field of submarine cables, particularly, relates to a high-voltage dynamic submarine cable.

BACKGROUND

With development of wind turbines in deep-sea areas, floating wind power has become a development trend of offshore wind power. In Scotland, Japan, France and other foreign wind power developers and relevant institutions, a few test prototypes have been put into operation since 2009. In recent years, China's wind power operators and submarine cable manufacturers have also carried out basic research on dynamic submarine cables.
Floating wind farm must adopt floating booster station for long-distance power transmission. The AC voltage transmitted by the booster station is often greater than 110kV, and 220kV becomes the first choice of the AC voltage. To meet the long-term severe dynamic fatigue load, dynamic submarine cable adopts a wet structure in prior art, that is, water tree resistant insulation material of the dynamic submarine cable can operate in a water vapor environment for a long time. At present, water tree resistant insulation materials are generally applied at a dynamic submarine cable carried with an AC voltage below 72kV. When 110kV and above voltage levels are applied for dynamic submarine cables, insulation materials have become a design bottleneck. According to public information, the high-voltage dynamic submarine cable is still a technical blank.
Existing static submarine cables and land cables adopt super clean insulating materials, and lead sleeves and aluminum sleeves are used for radial waterproofing to form a dry design of cables. However, these metal structures have poor fatigue resistance and weak conductivity, which do not meet the design requirements of dynamic submarine cables.
In design of high-voltage land cable, an insulation core often adopts technologies such as extruded lead sheath, longitudinal wrapping welding aluminum sheath, and the highest voltage level of the high-voltage land cable can reach 500kV. However, these metal sheathing materials in the high-voltage land cable are thick and heavy, not suitable for deep water environment, and have poor fatigue resistance. In addition, an outer diameter of high-voltage dynamic submarine cable is often more than 200mm after cabling, which brings great challenges to the armoring process and the extrusion capacity of the outer sheath.
To sum up, it is particularly important to develop a high-voltage dynamic cable that can be used in deep-sea, high salinity, and high water pressure environments.

SUMMARY

A purpose of the disclosure is to provide a high-voltage dynamic submarine cable that can be used in deep-sea, high salinity and high water pressure environments.
To achieve the above purpose, the technical solution adopted by the disclosure is:
A high-voltage dynamic submarine cable, including an electric unit, an optical unit, a filling strip, an inner sheath, an armor layer, and an outer sheath. The electric unit, the optical unit, and the filling strip are intertwisted to form a submarine cable core. The submarine cable core is wrapped with the inner sheath and the outer sheath. The armor layer is arranged between the inner sheath and the outer sheath. The electric unit includes a conductor, a co-extrusion structure layer, a water-blocking buffer layer, a corrugated copper sleeve and a split-phase sheath are sequentially wrapped outside the conductor. A plurality of annular or threaded relief structures are rolled on an outer side face of the corrugated copper sleeve in an axial direction. The water-blocking buffer layer and the split-phase sheath are in contact with and fill the relief structures on the corrugated copper sleeve.
Furthermore, a thickness of the corrugated copper sleeve is 0.6-0.8mm, an inner diameter of the corrugated copper sleeve is 70∼150mm, and a pitch of the corrugated copper sleeve is 8∼18mm, a depth of the relief structures is 3~8mm, when the relief structures are in threaded structures, a spiral rise angle of the relief structure is 5 °~60 °.
Furthermore, the corrugated copper sleeve needs to be annealed, and the material of the corrugated copper sleeve includes but is not limited to at least one of copper and copper alloy.
Furthermore, the coextrusion structure layer is composed of a conductor shield layer, an insulation layer and an insulation shield layer. The co-extrusion structure layer is wrapped with two or four layers of semi conductive water blocking tapes or semi conductive buffer water blocking tapes to form the water-blocking buffer layer.
Furthermore, copper wires are also arranged between layers of the water blocking buffer layer, and the copper wires are wound in a circumferential direction between the adjacent semi conductive water blocking tapes or semi conductive buffer water blocking taps, quantity of the copper wires is 4-6.
Furthermore, the split-phase sheath is an extruded phase separation sheath with a thickness of 3~8mm. The material of the extruded phase separation sheath is a semiconducting material, including but not limited to at least one of polyethylene and polyurethane.
Furthermore, the filling strip includes at least one steel strand filling strip and at least one polyethylene filling strip, the steel strand filling strip includes a plurality of steel strands and a polyethylene sheath, the plurality of the steel strands are twisted in a strip shape, and the polyethylene sheath is wrapped on the exterior of the plurality of the steel strands, a plurality of the steel strand filling strips and the polyethylene filling strips are filled in gaps between the optical unit, the electrical unit, and the inner sheath.
Furthermore, the armor layer is formed by wrapping a plurality of flat steel wires in the form of surface contact. The number of layers of the armor layers is even and at least two. Each layer of the armor layers is coated with at least one of asphalt, ointment, lubricant and graphene.
Compared with the prior art, the present disclosure adopts the longitudinal corrugated copper sleeve as the metal shielding layer, which has functions of carrying the short circuit current and radial water resistance, and meets requirements of dynamic state. Water blocking can be achieved by setting multi-layer water blocking buffer layers. In addition, the short circuit current can be shared through the circumferential sparse winding of copper wires between two water blocking buffer layers. The extruded split-phase sheath can fill the gaps of the relief structures of the corrugated copper sleeve, achieving the longitudinal water blocking and improve the strength. The introduction of optical unit can achieved online monitoring and fault location of dynamic submarine cable temperature and vibration. Through the design of even layer flat steel wire armoring layer, the outer diameter of the high-voltage dynamic submarine cable after cabling can be greatly reduced, and the bending strength and axial tensile strength of the high-voltage submarine cable can be improved, which is convenient for transportation and construction. The submarine cable has an excellent radial water blocking effect, guarantees normal use of an ultra-clean high-voltage insulating material in deep and far-sea, high-salinity and high-water-pressure environments, provides guarantee for reliable operation of a floating booster station of future floating wind fields, and guarantees the use function of the high-voltage dynamic submarine cable.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with reference to the following drawings. The drawings in the following description are some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

FIG. 1 is a schematic drawing of the present disclosure.
FIG. 2 is a cross-sectional drawing of a corrugated copper sleeve of the present disclosure.
FIG. 3 is a cross-sectional drawing of the corrugated copper sleeve and a split-phase sheath of the present disclosure.

Description of main components or elements:

Conductor 1;
Co-extrusion structure layer 2;
Water-blocking buffer layer 3;
Corrugated copper sleeve 4;
Split-phase sheath 5;
Steel strand filling strip 6;
Polyethylene filling strip 7;
Optical unit 8;
Inner sheath 9;
Armor layer 10;
Outer sheath 11.

DETAILED DESCRIPTION

In order to better understand the above purposes, features and advantages of embodiments of the application, the application is described below in combination with the drawings and specific embodiments. It should be noted that, in the case of no conflict, the features in the embodiments of the present application can be combined with each other.
Many specific details are described in the following description to understand the embodiments of the application. The described embodiments are only part of the embodiments of the application, not all of them.
Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the technical field belonging to the embodiments of the application. The terms used in the specification of the application herein are only for the purpose of describing specific embodiments, and are not intended to limit embodiments of the application.
Referring to FIG. 1, a high-voltage dynamic submarine cable includes an electric unit, an optical unit 8, a filling strip, an inner sheath 9, an armor layer 10 and an outer sheath 11. The electric unit, the optical unit 8, and the filling strip are intertwisted to form a submarine cable core. The submarine cable core is wrapped with the inner sheath 9 and the outer sheath 11. The armor layer 10 is arranged between the inner sheath 9 and the outer sheath 11. In an embodiment of the present disclosure, the number of the electrical units is at least three. The number of optical units 8 is not less than one, which is used to transmit optical signals, and can achieve dynamic detection of submarine cables by monitoring temperature, vibration and other signals. Once the submarine cables are damaged or failed, optical units can quickly alarm and locate.
Each of the electric unit includes a conductor 1. A sectional area of the conductor 1 is not less than 500 mm². A co-extrusion structure layer 2, a water-blocking buffer layer 3, a corrugated copper sleeve 4, and a split-phase sheath 5 are sequentially wrapped outside the conductor 1. The co-extruded structure layer 2 includes conductor shielding layer, insulating layer, and insulating shielding layer. The exterior part of the co-extruded structure layer 2 is wrapped with two or four layers of semi conductive water blocking tapes or semi conductive buffer water blocking tapes to form the water-blocking buffer layer 3. The corrugated copper sleeve 4 is sleeved on the exterior part of water blocking buffer layer 3 is sleeved. The corrugated copper sleeve 4 will compress the adjacent water blocking buffer layer 3 during rolling. In an embodiment of the present disclosure, the water blocking buffer layer 3 includes a water blocking layer and a buffer layer arranged in sequence. The corrugated copper sleeve 4 compresses the water blocking layer to achieve a longitudinal water blocking effect, and the buffer layer relieves indentation of the insulation layer caused by relief structures of the corrugated copper sleeve 4 to ensure the safety of electrical operation.
In order to share the short circuit current and ensure that the corrugated copper sleeve 4 will not overload the short circuit current, copper wires (not shown in the figure) are also arranged between layers of the water blocking buffer layer 3. Specifically, 4-6 copper wires with a diameter of 0.8mm are used to be wound in a circumferential direction between adjacent semi conductive water blocking tapes or semi conductive buffer water blocking tapes.
A plurality of annular or threaded relief structures are rolled on an outer side face of the corrugated copper sleeve 4 in an axial direction. The water-blocking buffer layer 3 and the split-phase sheath 5 are in contact with and filled with the relief structures on the corrugated copper sleeve 4. Specifically, a thickness of corrugated copper sleeve 4 is 0.6-0.8mm, an inner diameter of the corrugated copper sleeve 4 is 70∼150mm, and a pitch of the corrugated copper sleeve 4 is 8∼18mm, a depth of the relief structures is 3~8mm.
Referring to FIG. 2 and FIG. 3, a plurality of annular relief structures is rolled on the outer side face of the corrugated copper sleeve 4 in the axial direction. The inner diameter of the corrugated copper sleeve 4 is 70∼150mm, and the pitch of the corrugated copper sleeve 4 is 8∼18mm, a depth of the relief structures is 3~8mm. The submarine cable of the present disclosure can adapt to requirements of cable cores with different section areas, overcome problems of argon arc welding and rolling lines under the conditions of large size, thin wall thickness and continuous length, and avoid defects such as broken welding and missing welding. The annular relief structure of the disclosure is beneficial to improve the fatigue strength and fatigue life of the corrugated copper sleeve 4, and the corrugated copper sleeve 4 can also play a role of metal shielding and radial water blocking.
Several specific embodiments of the corrugated copper sleeve 4 are listed below:
The inner diameter D1 of the corrugated copper sleeve 4 is 70mm, the pitch of the corrugated copper sleeve 4 is 8~10mm, and the depth of the relief structures is 3~4mm.
The inner diameter D1 of corrugated copper sleeve 4 is 90mm, the pitch of the corrugated copper sleeve 4 is 10~12mm, and the depth of the relief structures is 4~5mm.
The inner diameter D1 of the corrugated copper sleeve 4 is 110mm, the pitch of the corrugated copper sleeve 4 is 12~14mm, and the depth of the relief structures is 5~6mm.
The inner diameter D1 of corrugated copper sleeve 4 is 130mm, the pitch of the corrugated copper sleeve 4 is 14~16mm, and the depth of the relief structures is 6~7mm.
The inner diameter D1 of corrugated copper sleeve 4 is 150 mm, the pitch of the corrugated copper sleeve 4 is 16∼18 mm, and the depth of the relief structures is 7~8 mm.
In addition, when the relief structures are in thread structures, a spiral rise angle of the relief structure is 5 °~60 °.
The material of corrugated copper sleeve 4 includes but is not limited to at least one of copper and copper alloy. The copper alloy materials can effectively improve the welding performance during argon arc welding, and significantly improve the fatigue performance and fatigue life of the corrugated copper sleeve 4. The corrugated copper sleeve 4 has strain hardening problem after rolling. In order to reduce or eliminate strain hardening and improve the fatigue resistance of the material, the corrugated copper sleeve 4 needs to be annealed by appropriate annealing methods.
In order to prevent water vapor intrusion, increase the strength of the submarine cable core, and improve the anti fatigue performance of the submarine cable, the split-phase sheath 5 of the disclosure adopts an extrusion process, so that gaps of the relief structures on the outer face of the corrugated copper sleeve 4 can be filled. A thickness of split-phase sheath 5 is 3~8mm. Material of the split-phase sheath 5 is semi conductive material, including but not limited to at least one of polyethylene and polyurethane. The material selection of the split-phase sheath 5 can meet the mechanical protection and grounding effects of corrugated copper sleeve 4.
In order to increase cable weight and improve mechanical strength of the submarine cable, gaps of the submarine cable shall be filled with filling strips during cabling. The filing strip includes at least one of steel strand filling strip 6 and at least one of polyethylene filling strips 7. The steel strand filling strip 6 include a plurality of steel strands and a polyethylene sheath. The plurality of steel strands are twisted in a strip shape, and the polyethylene sheath is wrapped on the exterior of the plurality of the steel strands. A plurality of steel strand filling strips and polyethylene filling strips are filled in gaps between the optical unit 8, the electrical unit, and the inner sheath 9.
After the electric unit, optical unit 8, and the filling strip are twisted into a cable, the outer diameter of the dynamic submarine cable is large, and the armor layer 10 is designed with an even number of layers and at least two layers. The armor layer 10 is formed by wrapping a plurality flat steel wires in a form of surface contact, so that the friction of the armor layer is more uniform, and the wear resistance is improved. In order to effectively prevent and reduce abrasion under dynamic environmental loads and meet the requirements for long-term service life under large water depth, heavy weight and severe environmental loads, each armor layer 10 is coated with at least one of asphalt, ointment, lubricant and graphene. The armor layer 10 of the disclosure can reduce an overall outer diameter of the dynamic submarine cable, improve a bending stiffness of the submarine cable to 5.0^∗10⁵ N·mm², effectively reduce the number of steel wires, and improve an axial tensile strength of the submarine cable to 1500MN. The reduction of the outer diameter of the submarine cable is also conducive to transportation and construction.
The above embodiments are only used to describe the technical solution of the embodiments of the application, not the limitations. Although the embodiments of the application have been described in detail with reference to the above preferred embodiments, ordinary technicians in the art should understand that the technical solution of the embodiments of the application can be modified or replaced equivalently, which should not be divorced from the spirit and scope of the technical solution of the embodiments of the application.

Claims

A high-voltage dynamic submarine cable, comprising an electric unit, an optical unit, a filling strip, an inner sheath, an armor layer, and an outer sheath; the electric unit, the optical unit, and the filling strip are intertwisted to form a submarine cable core, the submarine cable core is wrapped with the inner sheath and the outer sheath, the armor layer is arranged between the inner sheath and the outer sheath, characterized in that, the electric unit comprises a conductor; a co-extrusion structure layer, a water-blocking buffer layer, a corrugated copper sleeve and a split-phase sheath are sequentially wrapped outside the conductor; a plurality of annular or threaded relief structures are rolled on an outer side face of the corrugated copper sleeve in an axial direction; the water-blocking buffer layer and the split-phase sheath are in contact with and fill the relief structures on the corrugated copper sleeve.
The high-voltage dynamic submarine cable of claim 1, characterized in that, a thickness of the corrugated copper sleeve is 0.6-0.8mm, an inner diameter of the corrugated copper sleeve is 70∼150mm, and a pitch of the corrugated copper sleeve is 8∼18mm, a depth of the relief structures is 3~8mm, when the relief structures are in threaded structures, a spiral rise angle of the relief structure is 5 °~60 °.
The high-voltage dynamic submarine cable of claim 1, characterized in that, the corrugated copper sleeve needs to be annealed, and material of the corrugated copper sleeve comprises at least one of copper and copper alloy.
The high-voltage dynamic submarine cable of claim 1, characterized in that, the co-extrusion structure layer comprises a conductor shielding layer, an insulation layer, and an insulation shielding layer, the co-extrusion structure layer is wrapped with two or four layers of semi conductive water blocking tapes or semi conductive buffer water blocking tapes to form the water-blocking buffer layer.
The high-voltage dynamic submarine cable of claim 4, characterized in that, copper wires are arranged between layers of the water-blocking buffer layer, and the copper wires are wound in a circumferential direction between the adjacent semi conductive water blocking tapes or semi conductive buffer water blocking taps, quantity of the copper wires is 4-6.
The high-voltage dynamic submarine cable of claim 1, characterized in that, the split-phase sheath is an extruded phase separation sheath with a thickness of 3~8mm, material of the extruded phase separation sheath is a semiconducting material, the semiconducting material comprises at least one of polyethylene and polyurethane.
The high-voltage dynamic submarine cable of claim 1, characterized in that, the filling strip comprises at least one steel strand filling strip and at least one polyethylene filling strip, the steel strand filling strip comprises a plurality of steel strands and a polyethylene sheath, the plurality of the steel strands are twisted in a strip shape, and the polyethylene sheath is wrapped on the exterior of the plurality of the steel strands, a plurality of the steel strand filling strips and the polyethylene filling strips are filled in gaps between the optical unit, the electrical unit, and the inner sheath.
The high-voltage dynamic submarine cable of claim 1, characterized in that, the armor layer is formed by wrapping a plurality of flat steel wires in a form of surface contact, number of the armor layers is even and at least two, each of the armor layer is coated with at least one of asphalt, ointment, lubricant and graphene.