Subsea cable

Abstract

The present invention relates to a subsea cable which is provided with a dynamic subsea cable section and a static subsea cable section in one subsea cable, can connect land and offshore facilities by using a single subsea cable, and is characterized by comprising a first section for the main purpose of laying on a subsea surface and a second section for the main purpose of laying in water, the armor layer comprising the armor wires of the cable is fixed in the boundary region of the first and second segments, in particular by means of an inner fixing ring and an outer fixing ring.

Description

Technical Field

[0001] The present invention relates to a submarine cable. More specifically, the present invention relates to a submarine cable in which a dynamic submarine cable section and a static submarine cable section are respectively provided in one submarine cable without an intermediate connector, so that a single submarine cable can be used to connect a land and a marine facility. Background Art

[0002] In recent years, a renewable energy system that generates electricity by installing a wind turbine or the like in the open sea at a preset distance from the land where the wind is sufficient and the wind direction is stable, and then supplies the electricity by connecting to a power device on the land using a power cable has attracted much attention.

[0003] When the water depth in the sea where a wind turbine or the like is installed is relatively shallow, a structure can be installed on the seabed surface and a wind turbine can be installed on its upper part. However, when the water depth is relatively deep, the wind turbine can be installed in a floating manner.

[0004] A floating wind turbine, a power conversion device, etc. are supported by a floating object for floating and thus float on the sea surface. The floating object can be connected to an anchor installed on the seabed surface by a support line to be restricted from moving.

[0005] In addition, a wind turbine installed in the sea or a substation connecting the wind turbine and power equipment on the ground can be connected by using a submarine cable laid in the water.

[0006] Here, since the section from the power equipment on the ground to the seabed surface near the offshore wind turbine is a section where a submarine cable is laid on the seabed surface, and the cable does not move during power transmission after the cable is laid, this section is called a static section, and the submarine cable laid in this section is usually called a static submarine cable. Since the section from the seabed surface near the wind turbine to the floating wind turbine or substation is affected by ocean currents, sea waves, etc. and the movement of the cable is large, this section is called a dynamic section, and the submarine cable laid in this section is called a dynamic submarine cable.

[0007] In such a dynamic section, since the cable is subjected to more tensile force, torsion or bending, more mechanical durability is required for the dynamic submarine cable compared to the static submarine cable.

[0008] Furthermore, although the movement of a wind turbine or the like installed on a structure fixed to the seabed surface is small, since a generator or the like installed in a floating manner is continuously moved by sea waves or weather, etc., it is difficult to ensure sufficient durability when connecting with an ordinary static submarine cable, and thus a dynamic submarine cable needs to be used for connection.

[0009] In the case of dynamic submarine cables and static submarine cables, although the configuration of the core part including more than one power unit for power transmission is similar, due to the different laying environments of dynamic submarine cables and static submarine cables, the configuration of the cable protection part such as the armor layer is different, and thus there are differences in cable manufacturing costs.

[0010] Therefore, in the prior art, a method is used in which a static submarine cable is provided in a static section from a power device on the ground to the seabed surface near an offshore wind turbine, and a dynamic submarine cable is provided in a dynamic section from the seabed surface to a floating wind turbine or a substation.

[0011] In this case, in order to connect the static submarine cable and the dynamic submarine cable, cable connection is usually performed using an intermediate connector.

[0012] At this time, in order to form a connection between submarine cables that are different from each other (the connection between cables is called an intermediate connection), a method is used in which a marine vessel in the connection area uses an intermediate connector to connect the dynamic submarine cable and the static submarine cable and then lays them. However, in the case where the vessel performs the cable connection operation, due to the labor cost of skilled engineers for connection and the influence of the extended operation time caused by the connection, there is a problem that the vessel use cost for submarine cable laying increases significantly. Summary of the Invention

[0013] Problems to be Solved by the Invention

[0014] The problem to be solved by the present invention is to provide a submarine cable in which a dynamic submarine cable section and a static submarine cable section are respectively provided in one submarine cable, so that a single submarine cable can be used to connect a land and a marine facility.

[0015] Means for Solving the Problem

[0016] To solve the above problems, the present invention provides a submarine cable, which includes a cable core part and a cable protection part. The cable core part includes one or more power units for power transmission. The cable protection part surrounds the outside of the cable core part. The submarine cable includes a first section mainly for laying on the seabed surface and a second section mainly for laying in water in the length direction. The cable protection part includes an armor layer formed by winding a plurality of armor wires. The armor layer includes a first armor layer and a second armor layer. The first armor layer is continuously formed in the first section and the second section. The second armor layer is formed outside the first armor layer in the second section. The cable protection part includes an armor fixing part. The armor fixing part fixes the second armor layer to the first armor layer in the boundary area between the first section and the second section. The armor fixing part includes: an inner fixing ring installed in the boundary area to surround the first armor layer in the circumferential direction; and an outer fixing ring installed at a position different from that of the inner fixing ring along the cable length direction to surround the second armor layer disposed outside the inner fixing ring in the circumferential direction.

[0017] The cable protection part of the first section may include an outer sheath layer formed by winding yarn around the outside of the first armor layer, and the cable protection part of the second section may include a sheath layer formed by covering the outside of the second armor layer with a polymer resin.

[0018] In addition, the power unit may include: a conductor; an inner semi-conductive layer surrounding the conductor; an insulating layer surrounding the inner semi-conductive layer; an outer semi-conductive layer surrounding the insulating layer; and a metal shielding layer surrounding the outer semi-conductive layer.

[0019] Here, the inner fixing ring may expand the end of the second armor layer outward in the boundary area and then be installed to surround the first armor layer. After the installation of the inner fixing ring is completed, the expanded second armor layer is restored. The outer fixing ring may be installed to surround the second armor layer.

[0020] In this case, the outer fixing rings may be respectively arranged on the left and right of the installation position of the inner fixing ring.

[0021] In addition, the first armor layer may be a first metal armor layer formed by metal armor wires, and the second armor layer may be a second metal armor layer formed by metal armor wires.

[0022] Furthermore, the inner fixing ring may be welded and fixed to the first metal armor layer.

[0023] In addition, welding portions welded in the circumferential direction may be provided between the left and right edges of the inner fixing ring and the metal armor wires constituting the first metal armor layer, so that the inner fixing ring is fixed to the first metal armor layer.

[0024] Here, a plurality of the welding portions may be separately provided at intervals along the circumferential direction of the left and right edges of the inner fixing ring.

[0025] In this case, the inner fixing ring and the outer fixing ring may be constituted by two split rings, and may be formed into a circular ring by joining the ends of the respective split rings to each other.

[0026] In addition, the respective joint surfaces of the split rings may have inclined surfaces in opposite directions to inject welding melt between the joint surfaces.

[0027] In addition, the ends of the respective split rings may be provided in an oblique line shape not parallel to the length direction of the cable.

[0028] In addition, the thickness of the central portion of the cross-sectional thickness of the split ring may be the thickest.

[0029] Here, at least one carbon tape layer may be additionally provided in the boundary region, and the carbon tape layer surrounds and winds around the outside of the armor fixing portion.

[0030] Advantageous Effects of the Invention

[0031] According to the submarine cable of the present invention, the first section for laying on the seabed surface and the second section for laying in water are provided in different sections along the length direction of a single submarine cable, so that additional intermediate connection operations or intermediate connectors can be omitted.

[0032] In addition, according to the submarine cable of the present invention, the armor fixing portion provided in the boundary region between the first section and the second section of the submarine cable can stably fix the second armor layer additionally provided in the second section. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 An example of the configuration of an offshore wind power generation system connected by using the submarine cable of the present invention is shown.

[0034] Figure 2 A perspective view of multi-layer peeling of the first section area for laying on the seabed surface in the submarine cable of the present invention is shown.

[0035] Figure 3 A perspective view of multi-layer peeling of the second section area for laying in water in the submarine cable of the present invention is shown.

[0036] Figure 4Shows the state in which the outermost layers of the first section and the second section in the boundary area between the first section and the second section of the submarine cable of the present invention are removed.

[0037] Figure 5 Shows the state in which the second metal armor layer of the second section is unfolded in the boundary area between the first section and the second section of the submarine cable of the present invention in order to install an internal fixing ring for internal fixing.

[0038] Figure 6 Shows the process of installing an internal fixing ring in the form of a split ring on the outer peripheral surface of the first metal armor layer of the submarine cable of the present invention.

[0039] Figure 7 Shows the state in which, after installing an internal fixing ring in the form of a split ring on the outer peripheral surface of the first metal armor layer of the submarine cable of the present invention, the fixing ring is fixed by joining using a welding method.

[0040] Figure 8 Shows the process of restoring the second metal armor layer and installing an external fixing ring to surround the second metal armor layer in the state where the internal fixing ring is installed on the outer peripheral surface of the first metal armor layer of the submarine cable of the present invention.

[0041] Figure 9 Shows the state in which the installation of the external fixing ring is completed on the outer peripheral surface of the second metal armor layer of the submarine cable of the present invention.

[0042] Figure 10 Shows the process of forming a carbon tape layer by winding a carbon tape around the periphery of the armor fixing part in the state where the external fixing ring is installed.

[0043] Figure 11 Shows the state in which the armor fixing part of the submarine cable of the present invention is completed with a carbon tape layer.

[0044] Figure 12 Shows the test equipment for the submarine cable of the present invention.

[0045] Figures 13 to 15 Shows an example of an internal fixing ring or an external fixing ring used in the armor fixing part of the submarine cable of the present invention. Detailed Description of the Invention

[0046] Hereinafter, with reference to the drawings, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described in the specification and can also be embodied in other ways. On the contrary, the embodiments described herein are provided to make the disclosed content thorough and complete and to fully convey the idea of the invention to those skilled in the art. Throughout the specification, the same reference numerals denote the same components.

[0047] Figure 1 An example of the configuration of an offshore wind power generation system connected by the submarine cable 100 of the present invention is shown.

[0048] Wind turbines wb are increasing in number, which are installed in the far sea at a preset distance from the land where the wind volume is sufficient and the wind direction is stable.

[0049] Considering areas with sufficient and stable wind volume, wind turbines wb are often installed in waters with relatively deep water depths rather than along the coast of the land. Although in the case of wind turbines installed in shallow coastal waters, they are installed on vertical structures on the seabed surface, in deeper waters, since it is often impossible to install structures on the seabed surface, they can be installed in the following way: the wind turbine wb is installed in a floating manner, an anchor a is driven into the seabed surface, and the wind turbine wb is connected by a fixing wire r, so as to fix only the position of the wind turbine wb.

[0050] In addition, the offshore wind turbines wb are not configured individually, but a plurality of wind turbines wb are installed to form a large-scale power generation area. After the power generated by the plurality of wind turbines wb is collected, it can be supplied to the power equipment ps on the land through the power conversion equipment ts in a manner that minimizes power loss.

[0051] In this case, the power equipment ps on the land and the power conversion equipment ts at sea can be connected by the submarine cable 100.

[0052] Figure 1 The shown submarine cable 100 can be connected to the power equipment ps on the land and can be laid on the seabed surface near the power conversion equipment at sea. However, in order to connect from the seabed surface near the power conversion equipment to the power conversion equipment ts at sea installed in a floating manner, it needs to be laid in the water.

[0053] Here, the submarine cable installed on the seabed surface is usually embedded in the seabed surface or covered by a protective material, etc. On the contrary, the submarine cable in the section from the seabed surface to the sea level is exposed in the water and is affected by various external forces such as tidal currents and sea waves. The submarine cable set from the seabed surface to the sea level is called underwater laying. In addition, the submarine cable can be connected to power conversion equipment, etc. installed on the sea level, and the section on the sea level can also be regarded as an underwater laying section.

[0054] Therefore, a part of the section of the submarine cable 100 for connecting the power equipment ps on the land and the power conversion equipment ts at sea can be installed on the seabed surface g, and another section can be installed in the water.

[0055] In the case of the submarine cable 100, the cable protection parts of the section disposed on the seabed surface and the section disposed in water are preferably configured differently from each other according to the environmental differences of each. The area disposed in water is a section where waves or currents continuously affect the cable, and the cable protection part needs to be strengthened compared with the area disposed on the seabed surface g.

[0056] According to the differences of the cable protection parts as described above, the submarine cable 100 is divided into a dynamic submarine cable and a static submarine cable. As Figure 1 shown, according to different areas, the submarine cable 100 for connecting the power equipment ps on land and the substation equipment ts at sea needs a dynamic submarine cable and a static submarine cable. In the prior art, the dynamic submarine cable and the static submarine cable are connected by an intermediate connector on the ship and then disposed on the seabed. However, due to a significant increase in cost, the present invention omits the intermediate connector by manufacturing a single submarine cable 100 with different cable protection parts disposed at intervals along the length direction of the submarine cable.

[0057] In addition, as Figure 1 shown, in the overall length of the submarine cable 100 for connecting the power equipment ps on land and the substation equipment ts at sea, the length of the section disposed in water is relatively less than the length of the section disposed on the seabed surface. Therefore, it is unreasonable in terms of cost to form the entire submarine cable 100 with a dynamic submarine cable.

[0058] That is, the submarine cable 100 of the present invention has a structural feature that it is composed of a single cable without an intermediate connection, and has a first section 100s area as a static submarine cable section mainly for laying on the seabed surface and a second section 100d area as a dynamic submarine cable section mainly for laying in water according to different sections.

[0059] Herein, the section of the submarine cable for laying on the seabed surface is divided into the first section area, and the section for laying in water is divided into the second section area, but this does not mean a completely consistent division. On the contrary, for safety, it is preferable that a part of the second section area is disposed in the section for laying on the seabed surface.

[0060] First, referring to Figure 2 and Figure 3 , after studying the differences between the first section 100s area and the second section 100d area in the internal structures of the first section 100s area mainly for laying on the seabed surface and the second section 100d area mainly for laying in water in the submarine cable according to the present invention, referring to Figure 4The following figures illustrate the structure and fixing method of the armor fixing part 100j in which different cable armor layers are fixed to the boundary regions thereof.

[0061] Figure 2 A three-dimensional view of the multi-layer peeling of the first section 100s area for laying on the seabed surface in the submarine cable 100 of the present invention is shown. Figure 3 A three-dimensional view of the multi-layer peeling of the second section 100d area for laying in water in the submarine cable 100 of the present invention is shown.

[0062] Refer to Figure 2 and Figure 3 In the submarine cable 100 according to an embodiment of the present invention, a cable core part and a cable protection part are included. The cable core part includes one or more power units 10 for power transmission. The cable protection part surrounds the outside of the cable core part. The cable core part may include three power units 10, an optical unit 20, and a filling member 30. The cable protection part may include a lining layer 70, armor layers 80a and 80b, and an outer sheath layer 90 or a sheath layer 110 corresponding to the outermost layer. Each component will be described in detail later.

[0063] In the embodiment of the present invention, a three-pair cable having three power units 10 is illustrated as an example, but the present invention is not limited thereto and can also be applied to a case having one power unit or a different number of power units.

[0064] Each of the power units 10 may be configured to include a conductor 11, an inner semi-conductive layer 12, an insulating layer 13, an outer semi-conductive layer 14, a metal shielding layer 15, and a polymer sheath 16.

[0065] The conductor 11 serves as a path for current flow to transmit power and may be made of a material having excellent conductivity that can minimize power loss and is suitable for cable manufacturing and use, such as copper or aluminum, and having strength and flexibility.

[0066] As Figure 2 shown, the conductor 11 may be a combined conductor in which a plurality of circular wires are twisted and assembled into a circular shape. Specifically, it may be a combined conductor twisted in the S direction or the Z direction. Further, it may be a flat conductor having a flat conductor layer formed by a circular center wire and flat wires twisted to surround the circular center wire and having a circular cross-section as a whole. In the case where the conductor is the latter flat conductor, compared with a circular compressed conductor, the filling rate is relatively high, and thus it has the advantage of being able to reduce the outer diameter of the cable.

[0067] However, due to the uneven surface of the conductor 11, the electric field may be uneven, making it prone to local corona discharge. In addition, if a gap is generated between the surface of the conductor 11 and the insulating layer 13 described later, the insulation performance may deteriorate.

[0068] To solve the above problems, an internal semiconductive layer 12 can be provided outside the conductor 11. The internal semiconductive layer 12 can have semiconductivity by adding conductive particles such as carbon black, carbon nanotubes, carbon nanoplates, and graphite to an insulating material.

[0069] The internal semiconductive layer 12 functions to prevent a sharp change in the electric field between the conductor 11 and the insulating layer 13 described later to stabilize the insulation performance. In addition, the electric field can be made uniform by suppressing the uneven charge distribution on the conductor surface, and corona discharge, insulation breakdown, etc. can be suppressed by preventing the formation of a gap between the conductor 11 and the insulating layer 13.

[0070] The insulating layer 13 is provided outside the internal semiconductive layer 12 to electrically insulate the internal semiconductive layer 12 from the outside so that current does not leak to the outside along the conductor 11. Generally, the insulating layer 13 needs to have a high breakdown voltage and be able to maintain stable insulation performance for a long time. In addition, it also needs to have anti-high-temperature properties such as low dielectric loss and heat resistance. Therefore, the insulating layer 13 can use polyolefin resins such as polyethylene and polypropylene, and the polyethylene resin can be composed of a cross-linked resin.

[0071] An external semiconductive layer 14 can be provided outside the insulating layer 13. Similar to the internal semiconductive layer 12, the external semiconductive layer 14 is formed as a semiconductive material by adding conductive particles such as carbon black, carbon nanotubes, carbon nanoplates, and graphite to an insulating substance, so that the uneven charge distribution between the insulating layer 13 and the metal shielding layer 15 described later can be suppressed to stabilize the insulation performance. In addition, the external semiconductive layer 14 makes the surface of the insulating layer 13 smooth in the cable to relieve the electric field concentration and prevent corona discharge, and at the same time plays a role in physically protecting the insulating layer 13.

[0072] The power unit 10 can be additionally provided with a moisture absorption part (not shown) to prevent moisture from penetrating into the cable interior. The moisture absorption part can be formed between the wires constituting the conductor 11 and / or outside the conductor 11. The moisture absorption part is configured to include a super absorbent polymer (SAP) powder, tape, coating layer, film, etc., which has a fast moisture absorption rate into the cable and excellent ability to maintain the absorption state, thereby preventing moisture from penetrating along the cable length direction. In addition, the moisture absorption part can have semi-conductivity to prevent a sharp electric field change.

[0073] A metal shielding layer 15 and a polymer sheath 16 can be additionally provided outside the external semi-conductive layer 14. The metal shielding layer 15 and the polymer sheath 16 can protect the cable power unit from various environmental factors such as moisture penetration, mechanical damage, corrosion, etc. and fault current that may affect the power transmission performance of the cable.

[0074] The metal shielding layer 15 is grounded at the cable end, which can not only serve as a conduction path for fault current when a fault such as a ground fault or short circuit occurs, but also protect the cable from external impacts and simultaneously shield to prevent the electric field from discharging to the outside of the cable.

[0075] The metal shielding layer 15 can use a metal sheath or a wire shielding structure. Generally, in the case of a static submarine cable, a metal sheath is used as the metal shielding layer. However, in the case of a dynamic submarine cable, there is a risk of fatigue fracture of the metal sheath due to cable movement. Therefore, a wire shielding structure in which a plurality of metal wires such as copper are wound can be used as the metal shielding layer.

[0076] According to an embodiment of the present invention, the first section corresponding to the static submarine cable section can form a metal shielding layer with a metal sheath, the second section corresponding to the dynamic submarine cable section can form a wire shielding structure, and the metal sheath of the first section and the wire shielding structure of the second section can be joined and used in the boundary area between the first section and the second section.

[0077] The metal sheath is formed to seal the interior, so it can prevent foreign matters such as moisture from infiltrating and reducing the insulation performance. For example, by performing molten metal extrusion molding outside the external semi-conductive layer to form a seamless continuous outer surface, the waterproof performance can be improved. As the metal of the metal sheath, lead or aluminum is used. In particular, lead with excellent seawater corrosion resistance is preferably used for submarine cables. To improve the mechanical properties, a lead alloy added with metal elements is more preferably used.

[0078] An outer polymer sheath 16 made of resins such as polyvinyl chloride (PVC) and polyethylene is formed outside the metal shielding layer 15, thereby improving the corrosion resistance, waterproofness, etc. of the submarine cable, and serving as a function of protecting the cable from mechanical damage, heat, ultraviolet rays and other external environmental factors. In particular, the submarine cable is preferably made of polyethylene resin with excellent waterproof performance.

[0079] In addition, in the power unit 10, a copper wire inlay tape (not shown) to a moisture absorption layer (not shown) can be additionally provided between the metal shielding layer 15 and the outer semiconductive layer 14. The copper wire inlay tape can be composed of a copper wire and a non-woven fabric tape, etc., and can play a role in making the electrical contact between the outer semiconductive layer and the metal sheath smooth. The moisture absorption layer (not shown) can be configured to include a super absorbent polymer (SAP) powder, tape, coating layer, film, etc. that has a fast water absorption rate when water penetrates into the cable and excellent function of maintaining the absorption state. Thus, the moisture absorption layer can prevent moisture from penetrating along the length direction of the cable. In addition, in order to prevent a sharp electric field change from occurring in the moisture absorption layer, a copper wire can also be included in the moisture absorption layer.

[0080] In particular, when a wire shielding structure is used as the metal shielding layer 15, the waterproof performance is reduced compared to the metal sheath. Therefore, in order to improve the waterproof performance, it is preferable to additionally provide a moisture absorption layer (not shown).

[0081] On the other hand, the submarine cable 100 can also be provided with an optical unit 20.

[0082] Here, the optical unit 20 can have at least one optical fiber 21 and a tube 22 that houses the optical fiber 21.

[0083] Each of the optical units 20 has a specified number of optical fibers 21, and the optical fibers 21 are built into the tube 22 together with a filler. The tube can use a rigid material such as stainless steel. In addition, the optical unit 20 can also have a metal sheath 23 and a polymer sheath 24 that surround the tube 22.

[0084] On the other hand, Figure 2 An example of setting a single protection tube inside a single sheath is shown, but this is only an example. For example, it can also be a configuration in which a plurality of protection tubes are provided inside one sheath, and at least one optical fiber is provided inside each of the protection tubes.

[0085] On the other hand, Figure 2The submarine cable 100 shown is disposed on the seabed surface, and thus can have various protective layers to protect the internal components in harsh environments such as seawater and salt in the sea.

[0086] As Figure 2 shown, according to an embodiment of the present invention, the cable protection part of the submarine cable can have a cushion layer 70 made of polypropylene (PP: Polypropylene) yarns or the like that surrounds the power unit 10 and the optical unit 20, an armor layer 80a disposed outside the cushion layer 70 to enhance the mechanical strength of the submarine cable 100, and an outer sheath layer 90 disposed outside the armor layer 80a.

[0087] The armor layer 80a can be formed by arranging a plurality of armor wires 81 in a parallel helical winding manner outside the cushion layer 70, which not only functions to strengthen the mechanical characteristics and performance of the submarine cable 100, but also additionally protects the cable from external forces.

[0088] The armor wire 81 constituting the armor layer 80a is preferably made of a metal material, but can also be a non-metal material with high tensile strength.

[0089] The metal armor wire 81 is made of steel, galvanized steel, copper, brass, bronze, etc., and its cross-sectional shape can be formed by winding wires such as circular and flat angles. In the case of a non-metal armor wire 81, materials such as aramid fiber or ultra-high molecular weight polyethylene fiber of high tensile materials can be formed into a wire shape for use.

[0090] Hereinafter, in the embodiment of the present invention, the metal armor layer formed by the metal armor wire 81 will be described, but the present invention is not limited thereto.

[0091] The armor wire constituting the metal armor layer can be wound around the outer peripheral surface of the cushion layer 70 or the like in a spiral shape, and preferably, can be wound in the Z direction or the S direction, which is the opposite direction of the collective twisting direction of the power unit.

[0092] In addition, Figure 2 the metal armor layer 80a of the first section 100s shown is Figure 3 continuously configured with the metal armor layer 80a disposed inside the second section. Later, the metal armor layer will be described in detail.

[0093] The outer sheath layer 90 can be made of polypropylene yarns or the like, and protects the cable as the outermost layer formed outside the metal armor layer 80. The outer sheath layer 81 formed on the outermost layer can be made of two or more materials with different colors, so as to ensure the visibility of the cable laid on the seabed.

[0094] On the other hand, in the submarine cable 100 of the present invention, a filling member 30 may also be provided between the power unit 10 and the optical unit 20 and the cushion layer 70 of the cable core portion to protect the above-mentioned power unit 10 and optical unit 20. The above-mentioned filling member 30 is provided in the empty space inside the submarine cable 100, and functions to keep the submarine cable 100 circular and protect the power unit and the optical unit. As Figure 2 or Figure 3 shown, a plastic medium 30 having a shape corresponding to the empty space may be used, or a plurality of circular plastic media or fibers such as yarns of polypropylene material may be filled into the empty space to form it.

[0095] Figure 2 The submarine cable 100 shown in the figure shows a first section 100s for being arranged on the seabed surface. Although it has various protective layers for protecting internal components in harsh environments such as seawater and salt in the ocean, since it is supported on the seabed surface and laid, the influence of sea waves or tides is relatively small.

[0096] In the section connecting the power equipment ps on the ground and the substation equipment ts on the sea, etc., the first section 100s area of the submarine cable 100 can be laid on the seabed surface, but the second section 100d area for connecting from the seabed surface to the substation equipment ts arranged in a floating manner, etc. generates continuous movement under the influence of tides and sea waves. Therefore, the second section 100d area needs to further strengthen the protective layer compared to the first section 100s area.

[0097] Figure 3 In the case of the second section 100d area of the submarine cable 100 shown in the figure, the metal armor layer provided outside the cushion layer 70 and improving the mechanical strength of the submarine cable 100 can be provided in multiple layers. Therefore, a sheath layer 110 made of a polymer resin material can be provided outside the multi-layer armor layer. As the outermost layer, the sheath layer 110 serves as the outer sheath of the cable instead of the outer covering layer.

[0098] Therefore, the metal armor layer may be configured to include a first metal armor layer 80a continuously arranged in the first section 100s and the second section 100d and a second metal armor layer 80b only arranged in the second section 100d.

[0099] In addition, as Figure 3As shown, when the first metal armor layer 80a disposed on the inner side is wound in the Z direction or the S direction, which is the opposite direction to the collective stranding direction of the three power units, the second metal armor layer 80b disposed on the outer side is preferably wound in the opposite direction to the first metal armor layer 80a. Both the first metal armor layer 80a and the second metal armor layer 80b can be made of any one of steel, galvanized steel, copper, brass, and bronze. Similarly, wires with a circular or flat-angled cross-sectional shape can be wound.

[0100] On the outer side of the second metal armor layer 80b of the second section 100d, a sheath layer 110 made of a polymeric resin such as polyvinyl chloride (PVC) or polyethylene is formed by an extrusion molding method. While protecting the metal armor layer, it can minimize cable damage caused by waves and currents in the passing water environment, thereby ensuring sufficient durability.

[0101] As described above, the submarine cable 100 is preferably configured with different cable protection parts in different sections along the length direction of the cable according to the laying environment. However, in order to form a single submarine cable 100 by setting different cable protection parts in different sections, it is necessary to stably fix the cable protection part in the second section 100d area, especially the second metal armor layer 80b, at the boundary area between the first section 100s and the second section 100d.

[0102] That is, the second section 100d is a dynamic area where continuous movement may occur, and a second metal armor layer is additionally provided. Therefore, the second metal armor layer needs to be fixed at the boundary area between the first section 100s and the second section 100d in order to form a single submarine cable 100.

[0103] The cable protection part of the submarine cable 100 of the present invention includes an armor fixing part that fixes the second metal armor layer 80b to the first metal armor layer 80a at the boundary area between the first section 100s and the second section 100d. In addition, the armor fixing part includes an inner fixing ring and an outer fixing ring. The inner fixing ring is installed at the boundary area between the first section 100s and the second section 100d to surround the first armor layer 80a in the circumferential direction, and the outer fixing ring is installed at a position different from that of the inner fixing ring along the cable length direction to surround the second armor layer disposed outside the inner fixing ring in the circumferential direction.

[0104] Hereinafter, with reference to Figures 4 to 11 , the fixing method of the end of the boundary area between the first section 100s and the second section 100d and the second metal armor layer 80b in the second section 100d area will be described.

[0105] Figures 4 to 11Shows the formation process of the armor fixing part 100j at the boundary between the first section 100s area and the second section 100d area of the submarine cable of the present invention.

[0106] Specifically, Figure 4 Shows the state where the outer sheath layer 90, which is the outermost layer of the first section 100s, and the sheath layer 110, which is the outermost layer of the second section 100d, are removed in the boundary area between the first section 100s and the second section 100d of the submarine cable 100 of the present invention. Figure 5 Shows the state where the metal wires of the second metal armor layer 80b that constitutes the second section 100d are individually unfolded outward in the boundary area between the first section 100s and the second section 100d of the submarine cable 100 of the present invention for the installation of the internal fixing ring 120.

[0107] As Figure 4 shown, in order to install the internal fixing ring 120, the outer sheath layer 90 of the first section 100s and the sheath layer 110 of the second section 100d are removed in the boundary area between the first section 100s and the second section 100d. As Figure 5 shown, the metal armor wires of the second metal armor layer 80b that constitutes the second section 100d are unfolded outward. The unfolding of the second metal armor layer 80b is to install the internal fixing ring 120 inside the second metal armor layer 80b.

[0108] The submarine cable 100 of the present invention has a first section 100s and a second section 100d for being arranged in static areas and dynamic areas on the seabed. However, as a power cable, there are differences in the cable armor layers in different cable length direction sections. The second section 100d of the submarine cable 100 of the present invention is a dynamic section that is continuously affected by sea waves or tides, so tensile forces and torsions continuously occur in the cable.

[0109] That is, although the first metal armor layer 80a is provided throughout the first section 100s and the second section 100d and has little influence on the tensile forces applied to the overall cable, since the end of the second metal armor layer 80b is arranged in the boundary area between the first section 100s and the second section 100d, the helical winding state may be untied or the end position of the second metal armor layer 80b may be changed due to tensile force torsion. Therefore, it is necessary to stably fix the end of the second metal armor layer 80b in the boundary area between the first section 100s and the second section 100d.

[0110] In order to stably fix the end of the second metal armor layer 80b in the boundary area between the first section 100s and the second section 100d of the submarine cable 100 of the present invention, an internal fixing ring 120 and an external fixing ring 130 are used in the embodiments of the present invention.

[0111] Although methods such as simply joining the end of the second metal armor layer 80b to the outer peripheral surface of the first metal armor layer 80a can be considered, the joining fixing force by welding cannot provide sufficient fixing force against tensile forces applied to the submarine cable 100. Therefore, in the embodiments of the present invention, the internal fixing ring 120 and the external fixing ring 130 can be used to strengthen the structural fixing force.

[0112] In addition, as Figure 5 shown, when the internal fixing ring 120 is installed, since the fixing ring has a thickness, in order to minimize the increase in the outer diameter caused by the thickness of the fixing ring, before installing the internal fixing ring, a compression process of compressing the outer peripheral surface of the first metal armor layer 80a at the installation site of the internal fixing ring 120, and a wire alignment operation for preventing wire twisting can also be performed.

[0113] The compression process of compressing the outer peripheral surface of the first metal armor layer 80a at the installation site of the internal fixing ring can use a fixture or the like. For example, the fixture can be removed after compressing the installation site of the internal fixing ring 120 on the outer peripheral surface of the first metal armor layer 80a, and the internal fixing ring 120 can be installed at the compressed installation site.

[0114] On the other hand, a plurality of fixtures can also be used. For example, the compression process can be performed by using two of the three fixtures to first compress the left and right sides of the installation site of the internal fixing ring 120, and then using the remaining one fixture to compress the installation site of the internal fixing ring 120. Although the fixtures at the installation site of the internal fixing ring 120 are removed before the installation of the internal fixing ring 120, the fixtures on the left and right sides of the installation site of the internal fixing ring 120 can be removed after the installation of the internal fixing ring 120 is completed. In this case, damage to the first metal armor layer 80a that may occur during the compression process of the outer peripheral surface or the installation process of the internal fixing ring described later can be prevented.

[0115] Figure 6 shows the process of installing the internal fixing ring 120 in the form of a split ring on the peripheral edge of the outer peripheral surface of the first metal armor layer 80a in the submarine cable 100 of the present invention, Figure 7 shows the state where the internal fixing ring 120 in the form of a split ring in the submarine cable 100 of the present invention is installed on the outer peripheral surface of the first metal armor layer 80a and joined and fixed by a welding method.

[0116] As Figure 6 shown, the internal fixing ring 120 can be made of a metal material formed in the form of split rings 120a and 120b, and the internal fixing ring 120 in the form of a circular ring is formed by joining the two ends to each other.

[0117] In addition, as Figure 7As shown, a pair of split fixed rings can be joined at both ends in a state where they are installed on the outer peripheral surface of the first metal armor layer 80a to fix the inner fixed ring 120, and the inner fixed ring 120 can be additionally welded to the outer peripheral surface of the first metal armor layer 80a.

[0118] When the inner fixed ring 120 is additionally welded to the outer peripheral surface of the first metal armor layer 80a, the position of the inner fixed ring 120 can be reliably fixed on the outer peripheral surface of the first metal armor layer 80a.

[0119] For example, welding portions s are provided along the circumferential direction between the left and right frames of the inner fixed ring 120 and the metal armor wires constituting the first metal armor layer 80a, so that the inner fixed ring 120 can be fixed to the first metal armor layer 80a. The welding portions s can be formed by continuously welding both edges of the inner fixed ring 120 and the outer peripheral surface of the first metal armor layer 80a to form two parallel ring shapes, but it is not limited thereto.

[0120] As another example, as Figure 7 shown, when the inner fixed ring 120 is joined to the outer peripheral surface of the first metal armor layer 80a, a plurality of welding portions s can be provided at intervals along the circumferences of the left and right edges of the inner fixed ring 120. In this case, the operation time can be shortened and the cost can be reduced.

[0121] Furthermore, in order to minimize the overall length of the welding portions s but make the circumferential fixing state of the inner fixed ring 120 and the first metal armor layer 80a uniform, the welding portions on the left and right sides of the inner fixed ring 120 are preferably configured to be spaced apart without overlapping along the length direction of the cable.

[0122] That is, as Figure 7 shown, a plurality of welding portions s are respectively formed at intervals on the left and right sides of the inner fixed ring 120, but do not overlap in the width direction of the inner fixed ring 120, so that the overall length of the welding portions can be minimized while providing a stable fixing force by the welding portions.

[0123] In addition, after the welding operation of the inner fixed ring 120 is completed, corrosion can be prevented by applying a zinc rust inhibitor (not shown) to the armor fixing portion 100j.

[0124] Figure 8 The process of restoring the second metal armor layer 80b and installing the outer fixed ring 130 to surround the second metal armor layer 80b in a state where the inner fixed ring 120 is installed on the outer peripheral surface of the first metal armor layer 80a of the submarine cable 100 of the present invention is shown. Figure 9The state of the installation of the external fixing ring 130 on the outer circumferential surface of the second metal armor layer 80b of the submarine cable 100 of the present invention is shown.

[0125] If the internal fixing ring 120 is fixed on the outer circumferential surface of the first metal armor layer 80a by means such as welding, then as Figure 8 shown, the second metal armor layer 80b that has been expanded outward for the installation of the internal fixing ring 120 can be restored to its original position, and the external fixing ring 130 can be installed on the second metal armor layer 80b.

[0126] As Figure 8 shown, similarly, in the state where the internal fixing ring 120 is installed, even if the second metal armor layer 80b is restored, the area where the internal fixing ring 120 is installed keeps the second metal armor layer 80b in a raised state due to the thickness of the internal fixing ring 120, etc. The external fixing ring 130 is a fixing ring installed in a manner of surrounding the second metal armor layer 80b in the circumferential direction in a state where the second metal armor layer 80b is disposed outside the internal fixing ring 120, and its shape or material is the same as that of the internal fixing ring 120.

[0127] The external fixing ring 130 can be installed along the cable length direction at a position different from that of the internal fixing ring 120. That is, the external fixing ring 130 can be installed at a position different from the installation position of the internal fixing ring 120 that keeps the second metal armor layer 80b in a raised state.

[0128] For example, at least one external fixing ring 130 can be provided on each of the left and right sides of the installation position of the internal fixing ring 120.

[0129] In addition, in the state where the second metal armor layer 80b is restored, compression operations and wire alignment operations of twisting can also be performed on the installation position of the internal fixing ring 120 and the position where the external fixing ring 130 is to be installed by means of jigs, etc.

[0130] Therefore, as Figure 9 shown, if at least one external fixing ring 130 is installed on each of the left and right sides of the installation position of the internal fixing ring 120, the internal fixing ring 120 welded and fixed on the outer circumferential surface of the first metal armor layer 80a can play a wedge locking role in preventing the second metal armor layer 80b from moving relative to the first metal armor layer 80a.

[0131] For example, in Figure 9In the illustrated embodiment, when the second metal armor layer 80b slides relative to the first metal armor layer 80a to the right, the left external fixing ring 130 is stuck to the fixed internal fixing ring 120, thereby blocking the displacement of the second metal armor layer 80b to the right. Similarly, when the first metal armor layer 80a slides relative to the second metal armor layer 80b to the left, the right external fixing ring 130 is stuck to the fixed internal fixing ring 120, thereby blocking the displacement of the second metal armor layer 80b to the right, thus playing a wedge locking role in two directions.

[0132] That is, even if a tensile force or torsion that causes the second metal armor layer 80b to slide or separate relative to the first metal armor layer 80a is generated, the end of the second metal armor layer 80b is blocked from opening under the action of the external fixing ring 130, and the external fixing ring 130 is stuck to the internal fixing ring 120, thereby blocking the displacement of the second metal armor layer 80b relative to the first metal armor layer 80a.

[0133] In this case, the process of additionally welding the external fixing ring 130 installed on the second metal armor layer 80b to the outer peripheral surface of the second metal armor layer 80b can be omitted. This is because the internal fixing ring has been joined to the first metal armor layer and sufficiently plays a wedge locking role in a state where the possibility of moving in the cable length direction is blocked.

[0134] Figure 10 The process of winding the periphery of the armor fixing part 100j in the state where the external fixing ring 130 is installed with a carbon tape to form a carbon tape layer is shown. Figure 11 The state where the armor fixing part 100j of the submarine cable 100 of the present invention is completed with a carbon tape layer is shown.

[0135] If the installation of the external fixing ring 130 is completed, it is preferable to form a boundary area protective layer outside the armor fixing part 100j which is the boundary area between the first section 100s and the second section 100d.

[0136] According to an embodiment of the present invention, as Figure 10 shown, a carbon tape layer is formed by winding a carbon tape in the boundary area between the first section 100s and the second section 100d to finish the boundary area.

[0137] The carbon tape layer 140 can be composed of at least one layer or more, and the carbon tape layer 140 can be fixed by spraying adhesive during the carbon tape winding process to complete the finishing of the armor fixing part 100j.

[0138] Figure 12 The test device of the submarine cable 100 of the present invention is shown.

[0139] The submarine cable 100 of the present invention has a first section 100s and a second section 100d for laying on the seabed surface and in water, and the armor fixing part 100j is formed by the above method.

[0140] The first section 100s and the second section 100d of the thus-constituted submarine cable 100 are respectively laid in the static section and the dynamic section, and it is necessary to stably maintain the fixed state and the finishing state of their respective metal armor layers at the armor fixing part 100j described above.

[0141] Therefore, Figure 12 In the submarine cable 100 of the present invention, the first section 100s and the second section 100d sections where the armor fixing part 100j is provided at the boundary are installed in a bending and tensile force test device (T-B test loop), and in the situation of simultaneously applying bending and tensile forces, it is judged whether abnormalities occur inside the submarine cable 100 including the armor fixing part 100j.

[0142] To achieve bending, the test device is set to be able to rotate in a horizontal state, and includes a test wheel th whose diameter size is proportional to the outer diameter of the test object cable. After setting the test object submarine cable 100 on the test wheel th, traction lines r are respectively connected to both ends of the test object submarine cable 100, and then the traction lines are connected to a traction wheel dh and traction is alternately reversed, so as to apply a tensile force to the whole test object submarine cable 100 and perform the above steps multiple times, so that the armor fixing part 100j, which is the boundary area between the first section 100s and the second section 100d, is repeatedly bent and stretched on the test wheel.

[0143] As a test result, no abnormality was found in the communication test using the optical fiber of the optical unit included in the submarine cable 100. A slight trauma was found on the carbon tape layer that finishes the armor fixing part 100j, but no damage to the internal structures such as metal wires or damage to fixing rings, etc. was found inside, so it can be confirmed that the function of the armor fixing part 100j is very good.

[0144] Figures 13 to 15 An example of an internal fixing ring 120 or an external fixing ring 130 used in the armor fixing part 100j of the submarine cable 100 of the present invention is shown.

[0145] Specifically, Figure 13 A state of a pair of split ring assemblies is shown. Figure 14 A cross-sectional view (I-I′) along the thickness direction of the split ring is shown. Figure 15 A cross-sectional view (II-II′) of the joint parts 125 and 135 of the split ring is shown.

[0146] In order to minimize the diameter before welding the fixing ring, a fixture or the like can be used for compression. To prevent damage to the metal wires or the like constituting the metal armor layer due to the inner edge angle of the fixing ring during compression, as Figure 14 shown, the thickness t at the center in the width direction can be formed to be the thickest.

[0147] In addition, as described above, the internal fixing ring 120 and the external fixing ring 130 are of a split-ring structure, and the ends are joined by methods such as welding to each other. When the ends of the split rings forming the joint portions 125 and 135 are configured to be parallel to the length direction of the submarine cable, the welding joint length is insufficient, resulting in insufficient joint strength of the split rings.

[0148] Therefore, in order to have a sufficient joint length for their respective joint ends, as Figure 13 shown, the ends of the split rings forming the joint portions 125 and 135 can be set to an inclined shape not parallel to the length direction of the submarine cable.

[0149] In addition, when the joint surfaces of the split rings are vertically formed and in surface contact, it is difficult to sufficiently supply the welding melt between the joint surfaces during the process of joining the split rings to each other, resulting in possible insufficient joint strength of the split rings.

[0150] Therefore, in order to sufficiently inject the welding melt into the joint portions 125 and 135, as Figure 15 shown, the joint surfaces of the split rings are preferably set to inclined surfaces facing each other in order to inject the welding melt therebetween. Although this specification has been described with reference to the preferred embodiments of the present invention, those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention recited in the appended claims. Therefore, the modified implementations basically including the constituent elements of the claims of the present invention should be regarded as all included in the technical scope of the present invention.

Claims

1. An undersea cable It is characterized in that it includes: a cable core part including one or more power units for power transmission; and a cable protection part surrounding the outside of the cable core part. The submarine cable includes a first section mainly for laying on the seabed surface and a second section mainly for laying in water in the length direction. The cable protection part includes an armor layer formed by winding a plurality of armor wires. The armor layer includes: a first armor layer continuously formed on the first section and the second section; and a second armor layer formed on the outside of the first armor layer on the second section. The cable protection part includes an armor fixing part that fixes the second armor layer to the first armor layer in the boundary area between the first section and the second section. The armor fixing part includes: an inner fixing ring installed in the boundary area to surround the first armor layer in the circumferential direction; and an outer fixing ring installed at a position different from the inner fixing ring along the cable length direction to surround the second armor layer arranged outside the inner fixing ring in the circumferential direction.

2. The submarine cable according to claim 1, characterized in that the cable protection part of the first section includes an outer covering layer formed by winding yarn around the outside of the first armor layer, and the cable protection part of the second section includes a sheath layer formed by covering the outside of the second armor layer with a polymeric resin.

3. The submarine cable according to claim 1, characterized in that the power unit includes: a conductor; an inner semiconductive layer surrounding the conductor; an insulating layer surrounding the inner semiconductive layer; an outer semiconductive layer surrounding the insulating layer; and a metal shielding layer surrounding the outer semiconductive layer.

4. The submarine cable according to claim 1, characterized in that after the inner fixing ring expands the end of the second armor layer outward in the boundary area and installs it to surround the first armor layer, the expanded second armor layer is restored after the installation of the inner fixing ring, and the outer fixing ring is installed to surround the second armor layer.

5. The submarine cable according to claim 1, characterized in that the outer fixing rings are respectively arranged on the left and right of the installation position of the inner fixing ring.

6. The submarine cable according to claim 1, characterized in that the first armor layer is a first metal armor layer formed by metal armor wires, and the second armor layer is a second metal armor layer formed by metal armor wires.

7. The submarine cable according to claim 6, characterized in that the inner fixing ring is welded and fixed to the first metal armor layer.

8. The submarine cable according to claim 7, characterized in that welding parts welded in the circumferential direction are provided between the left and right edges of the inner fixing ring and the metal armor wires constituting the first metal armor layer to fix the inner fixing ring to the first metal armor layer.

9. The submarine cable according to claim 8, characterized in that a plurality of the welding parts are respectively arranged at intervals in the circumferential direction along the left and right edges of the inner fixing ring.

10. The submarine cable according to claim 1, characterized in that The inner fixing ring and the outer fixing ring are composed of two half rings, and a circular ring is formed by joining the ends of the respective half rings to each other.

11. The submarine cable according to claim 10, wherein the joint surfaces of the respective half rings have inclined surfaces in opposite directions to each other so that welding melt is injected between the joint surfaces.

12. The submarine cable according to claim 10, wherein the ends of the respective half rings are provided in an oblique line shape that is not parallel to the length direction of the cable.

13. The submarine cable according to claim 10, wherein the thickness of the central portion of the cross-sectional thickness of the half ring is the thickest.

14. The submarine cable according to claim 1, wherein at least one carbon tape layer is further provided in the boundary region, and the carbon tape layer surrounds and winds around the outside of the armor fixing portion.

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