Direct current composite submarine cable and method for manufacturing direct current composite submarine cable

Abstract

The application provides a DC composite submarine cable and a manufacturing method thereof. The DC composite submarine cable comprises, from inside to outside, a cable core, an inner cushion layer, an armored layer and an outer sheath layer; the cable core comprises a cabling tape, a positive electrode wire core, a negative electrode wire core and a composite wire core arranged in the cabling tape in sequence along the circumference of the cabling tape, and further comprises a filling structure and at least one optical fiber unit arranged between the positive electrode wire core, the negative electrode wire core and the composite wire core; the composite wire core comprises, from inside to outside, an optical unit, an armored structure, a repeater conductive layer and a first sheath layer, the armored structure is twisted by a plurality of metal filaments, and the repeater conductive layer is configured to be connected with a repeater to amplify an optical signal. The scheme can integrate the positive electrode submarine cable, the negative electrode submarine cable, the optical cable and the return flow submarine cable into one composite submarine cable, so as to save marine route resources, reduce engineering cost, effectively utilize the spare return flow line and avoid resource waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of submarine cable, in particular to a DC composite submarine cable and a manufacturing method thereof. BACKGROUND

[0002] The submarine cable generally refers to a cable laid on the seabed and underwater of rivers, which can be divided into submarine communication optical cable and submarine power cable according to functions, and the submarine power cable can be divided into AC submarine power cable and DC submarine power cable according to different power systems, and the submarine communication optical cable can be divided into relayed submarine communication optical cable and non-relayed submarine communication optical cable according to different transmission distances. The DC submarine power cable and the relayed submarine communication optical cable are generally used for long-distance power or optical communication transmission in the open sea, the relayed submarine optical cable has both optical transmission function and power supply function, and is used for long-distance transoceanic communication, and the transmission distance can reach thousands of kilometers, so a repeater should be used to amplify the optical signal with power on the seabed, so as to ensure good optical signal at the receiving end.

[0003] At present, the relayed DC submarine cable is a single-core structure, and the DC power transmission system includes a positive line, a negative line and a return line. For an application environment requiring true bipolar DC transmission and communication signal transmission at the same time, three DC submarine cables (i.e. a positive submarine cable, a negative submarine cable and a return submarine cable) and a submarine optical cable need to be laid, so that a large amount of marine route resources are occupied, and the construction cost of laying four submarine cables needs to be spent, and when the DC system is normally working, the return submarine cable is in an idle state for a long time, causing waste. SUMMARY

[0004] The main purpose of the present application is to provide a DC composite submarine cable and a manufacturing method thereof, so as to solve the problems of high cost of the DC composite submarine cable in the prior art and waste caused by long-term idle of the return submarine cable.

[0005] In order to achieve the above purpose, according to one aspect of the present application, a DC composite submarine cable is provided, which comprises a cable core, an inner pad layer, an armor layer and an outer sheath layer arranged in sequence from inside to outside; the cable core comprises a cabling tape and a positive line core, a negative line core and a composite line core arranged in sequence along the circumference of the cabling tape and arranged in the cabling tape; the cable core further comprises a filling structure and at least one optical fiber unit arranged between the positive line core, the negative line core and the composite line core; wherein the composite line core comprises an optical unit, an armor structure, a repeater conductive layer and a first sheath layer arranged in sequence from inside to outside, the armor structure is twisted by a plurality of metal monofilaments, and the repeater conductive layer is configured to be connected to a repeater to amplify the optical signal.

[0006] Further, the armor structure comprises a plurality of conductor layers from inside to outside, each conductor layer is twisted by a plurality of metal monofilaments, and the outer diameters of the plurality of metal monofilaments in each conductor layer are the same.

[0007] Further, the outer diameter of the metal filaments in the outer conductor layer is greater than the outer diameter of the metal filaments in the inner conductor layer; or the outer diameter of the metal filaments in the adjacent two conductor layers is the same.

[0008] Further, the water-blocking material is filled between the plurality of metal filaments; and / or the outer diameter of the metal filaments in the plurality of conductor layers increases successively from inside to outside along the radial direction of the composite core.

[0009] Further, the composite core further comprises a third sheath layer arranged between the optical unit and the armor structure, and the metal filaments in each conductor layer, the optical unit and the third sheath layer satisfy the following relationship:

[0010]

[0011] wherein n represents the number of layers of the conductor layers, N n is the maximum number of metal filaments in the nth conductor layer, d n is the outer diameter of the metal filaments in the nth conductor layer, D n is the outer diameter of the nth conductor layer, P n is the pitch of the nth conductor layer, n is an integer greater than or equal to 1, S3 is the total cross-sectional area of the armor structure of the composite core, d0 is the thickness of the third sheath layer, and D is the diameter of the optical unit.

[0012] Further, the armor structure comprises 6 layers of conductor layers, and the outer diameter and the pitch of the metal filaments in each conductor layer further satisfy the following relationship:

[0013] 2.0≤d1≤2.3, N1≤12, P1=22~25D1;

[0014] 2.3≤d2≤2.6, N2≤18, P2=20~22D2;

[0015] 2.6≤d3≤2·9, N3≤24, P3=17~19D3;

[0016] 2.9≤d4≤3.2, N4≤30, P4=15~17D4;

[0017] 3.2≤d5≤3.5, N5≤36, P5=13~15D5;

[0018] 3.5≤d6≤3.8, N6≤42, P6=11~13D6

[0019] wherein n represents the number of layers of the conductor layers, n is an integer greater than or equal to 1; N n is the maximum number of metal filaments in the nth conductor layer, d nD is the outer diameter of the metal monofilament in the n th conductor layer (unit: mm) n P is the outer diameter of the n th conductor layer (unit: mm) n P is the outer diameter of the n th conductor layer (unit: mm)

[0020] Further, the composite core further comprises a first insulating layer arranged between the armored structure and the repeater conductive layer, a semi-conductive shielding layer arranged on at least one side of the first insulating layer, a first longitudinal water-blocking layer arranged on at least one side of the repeater conductive layer, and a first metal shielding layer arranged between the repeater conductive layer and the first sheath layer.

[0021] Further, the optical unit comprises a stainless steel tube and a plurality of optical fibers arranged in the stainless steel tube, and a water-blocking ointment filled at gaps between the plurality of optical fibers; and / or, the positive core comprises, from inside to outside, a conductor structure, a conductor shielding layer, a second insulating layer, an insulating shielding layer, a second longitudinal water-blocking layer, a second metal shielding layer, and a second sheath layer, wherein the conductor structure comprises, from inside to outside, a plurality of conductor layers, each of which is twisted by a plurality of metal monofilaments, and the negative core has the same structure as the positive core.

[0022] Further, the optical unit comprises a stainless steel tube and a plurality of optical fibers arranged in the stainless steel tube, the wall thickness of the stainless steel tube is greater than or equal to 0.5 mm, and the outer diameter D of the stainless steel tube ranges from 2.5 mm to 4.5 mm; and / or, the number of the optical fibers ranges from 2 to 96, and the optical fibers are high-temperature-resistant optical fibers with a temperature resistance greater than or equal to 300℃.

[0023] According to another aspect of the present application, there is also provided a manufacturing method of a DC composite submarine cable, the manufacturing method being used to manufacture the DC composite submarine cable described above, and the manufacturing method comprising: an armored structure twisting step of twisting a plurality of metal monofilaments at the outer periphery of the optical unit to form the armored structure; and a step of sequentially arranging, outside the armored structure, the repeater conductive layer and the first sheath layer to form the composite core.

[0024] Further, the armored structure comprises a plurality of conductor layers from inside to outside, each of which is twisted by a plurality of metal monofilaments, and before the armored structure twisting step, the manufacturing method further comprises a metal monofilament selection step of selecting the specifications of the metal monofilaments used in each conductor layer, wherein the outer diameters of the metal monofilaments in different conductor layers are the same or different, and the outer diameters of the plurality of metal monofilaments in the same conductor layer are the same, so that the cross-sectional area of the armored structure is the same as the total cross-sectional area of the conductor structures in the positive core and / or the negative core.

[0025] Further, the composite core further comprises a third sheath layer arranged between the optical unit and the armored structure, and before the armored structure twisting step, the manufacturing method further comprises an extrusion step of extruding the third sheath layer at the outer periphery of the optical unit.

[0026] Further, the armored structure comprises a plurality of conductor layers arranged from inside to outside, each conductor layer being stranded by a plurality of metal filaments, the stranding step of the armored structure comprising: a step of stranding the plurality of conductor layers; and a welding step of welding the conductor layer to an adjacent conductor layer after stranding each conductor layer.

[0027] Further, in the welding step, two adjacent conductor layers are welded to form a welding point, and two adjacent welding points have a spacing in the axial direction of the composite core; and / or in the welding step, the welding is performed by using an argon arc welding process.

[0028] Further, the spacing between the two adjacent welding points is greater than 30 cm.

[0029] The technical scheme of the present application can be summarized as follows: when the positive core and the negative core can work normally, the optical unit in the composite core transmits a communication signal, and the repeater conductive layer connects the repeater and amplifies the optical signal; when any one of the positive core and the negative core fails to transmit current, the composite core can act as a return line to ensure that half of the load of the DC power transmission system works normally; at this time, since the armored structure is composed of metal filaments, it has the function of conducting electricity, and the armored structure can act as a conductor to transmit current. In this way, the positive core, the negative core, the composite core (i.e., the line core that acts as a return and transmits an optical signal), and the optical fiber unit are integrated into a composite submarine cable, which can not only reduce the construction cost of the submarine cable and save marine route resources, but also effectively utilize the standby return submarine cable, avoiding the problem of resource waste and reduced service life caused by long-term idling of the return submarine cable. BRIEF DESCRIPTION OF DRAWINGS

[0030] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application given below, make an explanation of the application, and do not constitute an improper limitation of the application. In the drawings:

[0031] Figure 1 A structure schematic diagram of an embodiment of the DC composite submarine cable according to the present application is shown;

[0032] Figure 2 A flowchart of a manufacturing method of the DC composite submarine cable according to the present application is shown;

[0033] Figure 3 A flowchart of a manufacturing method of the DC composite submarine cable according to the present application is shown; Figure 2

[0034] Figure 4 A production device used in the manufacturing method of the DC composite submarine cable according to the present application is shown; and Figure 2

[0035] ​​Figure 5 A schematic diagram of a welding point of an armor structure in a manufacturing method of a DC composite submarine cable is shown. Figure 2 A schematic diagram of a welding point of an armor structure in a manufacturing method of a DC composite submarine cable is shown.

[0036] Wherein, the above drawings include the following reference signs:

[0037] 1, positive electrode core; 11, conductor structure; 12, conductor shielding layer; 13, second insulation layer; 14, insulation shielding layer; 15, second longitudinal water-blocking layer; 16, second metal shielding layer; 17, second sheath layer; 2, negative electrode core; 3, composite core; 31, optical unit; 310, first metal shielding layer; 311, first sheath layer; 32, third sheath layer; 33, armor structure; 35, first insulation layer; 36, semi-conductive shielding layer; 37, first longitudinal water-blocking layer; 38, repeater conductive layer; 4, filling structure; 5, optical fiber unit; 6, cabling tape; 7, inner pad layer; 8, armored layer; 9, outer sheath layer; 400, accommodation space. DETAILED DESCRIPTION

[0038] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0039] As shown in Figure 1 , the embodiment of the present application provides a DC composite submarine cable. The DC composite submarine cable comprises, from inside to outside, a cable core, an inner pad layer 7, an armored layer 8 and an outer sheath layer 9; the cable core comprises a cabling tape 6 and a positive electrode core 1, a negative electrode core 2 and a composite core 3 arranged in the cabling tape 6 in sequence along the circumference of the cabling tape 6, the cable core further comprises a filling structure 4 and at least one optical fiber unit 5 arranged between the positive electrode core 1, the negative electrode core 2 and the composite core 3; wherein the composite core 3 comprises, from inside to outside, an optical unit 31, an armor structure 33, a repeater conductive layer 38 and a first sheath layer 311, the armor structure 33 is twisted by a plurality of metal filaments, and the repeater conductive layer 38 is configured to be able to connect a repeater to amplify an optical signal.

[0040] In the above technical solution, the outer wall of the composite core 3 abuts and is tangent to the outer walls of the positive core 1 and the negative core 2, respectively; the filling structure 4 is a shaped filling strip or filling rope or a combination of shaped filling strip and filling rope; the number of optical fiber units 5 is one; the optical fiber unit 5 is set between the positive core 1 and the negative core 2 and is supported and protected by the filling structure 4; the cabling wrapping tape 6 is a wrapping non-woven fabric, cotton tape or other tape material to wrap the positive core 1, the negative core 2 and the composite core 3 into a whole; the inner padding layer 7 is the armor inner padding layer, which is wrapped with polypropylene rope around the outer periphery of the cable core; the armor layer 8 is wrapped with steel wire or copper wire or other metal and non-metal wires; the outer sheath layer 9 is the armor outer sheath layer, which is wrapped with polypropylene rope around the outer periphery of the armor layer 8.

[0041] With the above configuration, when both the positive core 1 and the negative core 2 are functioning normally, the optical unit 31 within the composite core 3 transmits communication signals, and the repeater conductive layer 38 connects to the repeater and amplifies the optical signal. When either the positive core 1 or the negative core 2 fails and cannot transmit current, the composite core 3 can act as a return line to ensure the normal operation of half of the DC transmission system's load. In this case, the armor structure 33, composed of metal monofilaments, has conductive properties and can act as a conductor to transmit current. In this way, the positive core 1, the negative core 2, the composite core 3 (i.e., the core that serves as the return line and transmits optical signals), and the optical fiber unit 5 can be integrated into a single composite submarine cable. This reduces the construction cost of the submarine cable, saves marine route resources, and effectively utilizes the spare return cable, avoiding resource waste and reduced service life due to long-term idleness of the return cable.

[0042] In another embodiment of the present invention, the number of optical fiber units 5 may also be set to 2 or 3; or, optical fiber units 5 may not be set.

[0043] like Figure 1 As shown, in an embodiment of the present invention, the armor structure 33 includes multiple conductor layers from the inside out, each conductor layer being composed of multiple metal monofilaments twisted together, and the multiple metal monofilaments in each conductor layer having the same outer diameter.

[0044] In the above technical solution, the outer diameter of the metal filaments in the outer conductor layer is greater than the outer diameter of the metal filaments in the inner conductor layer, and the outer diameter of the metal filaments in the plurality of conductor layers gradually increases from the inside to the outside along the radial direction of the composite core 3. Since the outer diameter of the metal filaments in the inner conductor layer of the plurality of conductor layers should not be too large, otherwise the large gap between the metal filaments will affect the longitudinal water-blocking performance of the armored structure 33, and the number of metal filaments in each conductor layer is limited, by adjusting the outer diameter of the metal filaments in each conductor layer, on the one hand, the longitudinal water-blocking performance of the inner conductor layer can be ensured, and on the other hand, the total cross-sectional area of the armored structure 33 is the same as the cross-sectional area of the conductor structure 11 in the positive core 1 or the negative core 2, so that the composite core 3 and the positive core 1 or the negative core 2 have the same current transmission capacity.

[0045] In another embodiment of the present application, the outer diameter of the metal filaments in the adjacent two conductor layers can also be the same, that is, the outer diameter of the metal filaments in each conductor layer of the plurality of conductor layers included in the armored structure 33 is the same; or the outer diameter of the metal filaments in part of the conductor layers is the same, and the outer diameter of the metal filaments in part of the conductor layers is different.

[0046] In the embodiment of the present application, the plurality of metal filaments are filled with water-blocking materials, which can be water-blocking powder, water-blocking tape, water-blocking yarn, water-blocking glue or other water-blocking materials.

[0047] In the embodiment of the present application, the composite core 3 further comprises a third sheath layer 32 arranged between the light unit 31 and the armored structure 33, and the metal filaments in each conductor layer, the light unit 31 and the third sheath layer 32 satisfy the following relationship:

[0048]

[0049]

[0050] Wherein, n represents the number of conductor layers, N n is the maximum number of metal filaments in the nth conductor layer, d n is the outer diameter of the metal filaments in the nth conductor layer, D n is the outer diameter of the nth conductor layer, P n is the pitch of the nth conductor layer, n is an integer greater than or equal to 1, S3 is the total cross-sectional area of the armored structure 33 of the composite core 3, d0 is the thickness of the third sheath layer, and D is the diameter of the light unit 31.

[0051] It should be noted that the meaning of formula 1 is that the total cross-sectional area of the metal filaments of the multi-layer conductor layer is greater than or equal to the total cross-sectional area of the armored structure 33, and the meaning of formula 2-1 to formula 2-n is that the maximum number of metal filaments that can be accommodated by a certain layer of the conductor layer is calculated by the outer diameter of the layer of the conductor layer and the outer diameter of the metal filaments in the layer of the conductor layer.

[0052] In the above technical solution, the values of N1 to N n are first calculated by formula 2-1 to formula 2-n, the outer diameters d1 to d n of the metal filaments in each layer of the conductor layer are selected, and then the values of N1 to N n and d1 to d n are brought into formula 1. When the condition of formula 1 is met, it means that the selected outer diameter values of the metal filaments in each layer of the conductor layer meet the requirements.

[0053] It should be noted that since the total cross-sectional area of the armored structure 33 needs to be the same as the cross-sectional area of the conductor structure 11 in the positive core 1 or the negative core 2, the value of S3 can be substituted into the cross-sectional area of the conductor structure 11 in the positive core 1 or the negative core 2 during calculation. In addition, since d n and N n are obtained by iterative calculation, the total on the left side of formula 1 does not need to be exactly equal to the value of S3, and can be slightly larger than S3, that is, the total cross-sectional area of each layer of the conductor layer of the armored structure 33 is not less than the total cross-sectional area of the conductor structure 11 in the positive core 1 or the negative core 2.

[0054] Through the above setting, according to the relationship between the metal filaments in each layer of the conductor layer, the light unit 31 and the third sheath layer 32 in the armored structure 33, the outer diameter of the metal filaments in each layer of the conductor layer of the armored structure 33 can be calculated. According to the above method, the armored structure 33 is designed, on the one hand, the armored structure 33 can protect the internal light unit 31, on the other hand, the armored structure 33 also has the function of longitudinal water resistance.

[0055] In an embodiment of the present application, the third sheath layer 32 is formed by extrusion of semi-conductive polyethylene, and the thickness is 1.0mm-1.5mm.

[0056] In an embodiment of the present application, in order to avoid the loss of weight and imbalance of the three-phase disc during cabling, the design single weight deviation of the composite core 3 and the positive core 1 or the negative core 2 should be controlled within 5%.

[0057] In an embodiment of the present application, the armored structure 33 includes 6 layers of conductor layers, and the outer diameter and pitch of the metal filaments in each layer of the conductor layer satisfy the following relationship:

[0058] 2.0≤d1≤2.3, N1≤12, P1=22~25D1;

[0059] 2.3≤d2≤2.6, N2≤18, p2=20~22D2;

[0060] 2.6≤d3≤2.9, N3≤24, P3=17~19D3;

[0061] 2.9≤d4≤3.2, N4≤30, P4=15~17D4;

[0062] 3.2≤d5≤3.5, N5≤36, P5=13~15D5;

[0063] 3.5≤d6≤3.8, N6≤42, P6=11~13D6;

[0064] Where n is the number of conductor layers, and n is an integer greater than or equal to 1; N n d represents the maximum number of metal monofilaments within the nth conductor layer. n D is the outer diameter (in mm) of the metal filament within the nth conductor layer. n P is the outer diameter (in mm) of the nth conductor layer. n Let be the pitch of the nth conductor layer.

[0065] It should be noted that "the pitch of the nth conductor layer" refers to the pitch of all the metal filaments within the nth conductor layer.

[0066] like Figure 1 As shown, in an embodiment of the present invention, the composite core 3 further includes a first insulating layer 35 disposed between the armor structure 33 and the repeater conductive layer 38, a semiconductive shielding layer 36 disposed on at least one side of the first insulating layer 35, a first longitudinal water-blocking layer 37 disposed on at least one side of the repeater conductive layer 38, and a first metal shielding layer 310 disposed between the repeater conductive layer 38 and the first sheath layer 311.

[0067] It should be noted that "at least one side of the first insulating layer 35" refers to at least one side of the inner and outer sides of the first insulating layer 35, and "at least one side of the repeater conductive layer 38" refers to at least one side of the inner and outer sides of the repeater conductive layer 38.

[0068] In the technical solution, the semi-conductive shielding layer 36 is formed by extruding a semi-conductive shielding material or by winding a semi-conductive tape and a semi-conductive shielding material; the first insulating layer 35 is formed by extruding a cross-linked polyethylene insulating material; the first longitudinal water-blocking layer 37 is formed by winding a semi-conductive water-blocking tape; the repeater conductive layer 38 is formed by winding a copper tape; the first metal shielding layer 310 is formed by extruding an alloy lead, winding a copper wire, winding a copper tape, or a combination of the above; and the first sheath layer 311 is formed by extruding an insulating polyethylene or a semi-conductive polyethylene or other materials that can be used for sheath extrusion.

[0069] In an embodiment of the application, the thickness of the first insulating layer 35 can be adjusted so that the outer diameter of the composite core 3 is the same as the outer diameter of the positive core 1 or the negative core 2.

[0070] As shown in FIG. 1, in an embodiment of the application, the filling structure 4 includes a first mating surface that mates with an adjacent core surface, a second mating surface that mates with another adjacent core surface, and a third mating surface that mates with the cable wrapping tape 6, the third mating surface is provided with an opening and a receiving space 400 that communicates with the opening, and the optical fiber unit 5 is located in the receiving space 400. Figure 1 It should be noted that the "core" refers to any one of the positive core 1, the negative core 2, and the composite core 3.

[0071] In the technical solution, the filling structure 4 is provided in three, and the three filling structures are respectively located at the gaps formed between the three cores.

[0072] Through the above arrangement, the filling structure 4 can mate with the two adjacent core surfaces through the first mating surface and the second mating surface, which can ensure that the filling structure 4 closely mates with the core, thereby better playing a filling role. The optical fiber unit 5 is located in the receiving space 400, and the filling structure 4 can support the optical fiber unit 5.

[0073] As shown in FIG. 1, in an embodiment of the application, the optical unit 31 includes a stainless steel tube and a plurality of optical fibers arranged in the stainless steel tube, and a water-blocking ointment filled in the gaps between the plurality of optical fibers to play a water-blocking role.

[0074] Figure 1 In an embodiment of the application, the wall thickness of the stainless steel tube is greater than or equal to 0.5 mm, and the outer diameter D of the stainless steel tube ranges from 2.5 mm to 4.5 mm, so that the stainless steel tube has a certain strength and can avoid the optical fibers in the stainless steel tube being flattened during the stranding of the armored structure 33.

[0075] In an embodiment of the application, the wall thickness of the stainless steel tube is greater than or equal to 0.5 mm, and the outer diameter D of the stainless steel tube ranges from 2.5 mm to 4.5 mm, so that the stainless steel tube has a certain strength and can avoid the optical fibers in the stainless steel tube being flattened during the stranding of the armored structure 33.

[0076] ​In one embodiment of the present invention, the number of optical fibers ranges from 2 to 96, and the optical fibers are high-temperature resistant optical fibers with a temperature resistance greater than or equal to 300°C.

[0077] like Figure 1 As shown, in an embodiment of the present invention, the positive electrode core 1 includes a conductor structure 11, a conductor shielding layer 12, a second insulating layer 13, an insulating shielding layer 14, a second longitudinal water-blocking layer 15, a second metal shielding layer 16, and a second sheath layer 17 arranged sequentially from the inside to the outside. The conductor structure includes multiple conductor layers arranged sequentially from the inside to the outside, and each conductor layer is made of multiple metal monofilaments twisted together. The negative electrode core 2 has the same structure as the positive electrode core 1.

[0078] In the above technical solution, the conductor structure 11 is made of copper, aluminum, aluminum alloy or other metal materials; the conductor structure 11 is filled with water-blocking powder, water-blocking tape, water-blocking yarn, water-blocking adhesive or other water-blocking materials, and the structure of the conductor structure 11 is a tightly compressed round, irregular or other cable conductor type; the conductor shielding layer 12 is made by extruding semi-conductive shielding material, or by wrapping semi-conductive tape with extruded semi-conductive shielding material; the second insulation layer 13 is made by extruding cross-linked polyethylene insulation material; the insulation shielding layer 14 is made by extruding semi-conductive shielding material; the second longitudinal water-blocking layer 15 is made by wrapping semi-conductive water-blocking tape; the second metal shielding layer 16 is made by extruding alloy lead, or by wrapping copper wire, or by wrapping copper tape, or a combination of the above forms; the second sheath layer 17 is made of insulating polyethylene or semi-conductive polyethylene or other materials that can be used for sheath extrusion.

[0079] like Figure 2 As shown, an embodiment of the present invention also provides a method for manufacturing a DC composite submarine cable. The manufacturing method is used to manufacture the above-mentioned DC composite submarine cable. The manufacturing method includes: an armor structure stranding step, in which multiple metal monofilaments are stranded around the outer periphery of the optical unit 31 to form an armor structure 33; and a step of sequentially distributing a repeater conductive layer 38 and a first sheath layer 311 outside the armor structure 33 to form a composite core 3.

[0080] In the above technical solution, the repeater conductive layer 38 and the first sheath layer are wrapped around the armor structure 33, and the first sheath layer 311 is extruded to form the outermost layer of the composite core 3. The above-mentioned wrapping and extrusion processes are existing technologies and will not be described in detail here.

[0081] like Figure 3As shown, in the embodiment of the present application, the armored structure 33 comprises a plurality of conductor layers from inside to outside, each conductor layer is twisted by a plurality of metal filaments, before the armored structure twisting step, the manufacturing method further comprises: a metal filament selection step of selecting the specification of the metal filament used in each conductor layer, wherein the outer diameters of the metal filaments in different conductor layers are the same or different, and the outer diameters of the plurality of metal filaments in the same conductor layer are the same, so that the total cross-sectional area of the armored structure 33 is the same as the total cross-sectional area of the conductor structure in the positive electrode core 1 and / or the negative electrode core 2.

[0082] Through the above arrangement, since the outer diameter of the metal filaments in the conductor layers on the inside in the plurality of conductor layers is not too large, otherwise it will affect the longitudinal water blocking performance of the armored structure 33 due to the large gap between the metal filaments, and the number of metal filaments in each conductor layer has an upper limit, therefore, by adjusting the outer diameter of the metal filaments in each conductor layer, on the one hand, it can ensure that the longitudinal water blocking performance of the conductor layer on the inside is not affected, on the other hand, it can also ensure that the total cross-sectional area of the armored structure 33 is the same as the cross-sectional area of the conductor structure 11 in the positive electrode core 1 or the negative electrode core 2, thereby ensuring that the composite core 3 and the positive electrode core 1 or the negative electrode core 2 have the same current transmission capacity.

[0083] In the embodiment of the present application, in the metal filament selection step, the following relationship is satisfied between the metal filaments in each conductor layer, the light unit 31 and the third sheath layer 32:

[0084]

[0085] Wherein, n represents the number of conductor layers, N n is the maximum number of metal filaments in the nth conductor layer, d n is the outer diameter of the metal filaments in the nth conductor layer, D n is the outer diameter of the nth conductor layer, P n is the pitch of the nth conductor layer, n is an integer greater than or equal to 1, S3 is the total cross-sectional area of the armored structure 33 of the composite core 3, d0 is the thickness of the third sheath layer, and D is the diameter of the light unit 31.

[0086] It should be noted that the meaning of formula 1 is that the total cross-sectional area of the metal filaments of the plurality of conductor layers is greater than or equal to the total cross-sectional area of the armored structure 33, and the meaning of formula 2-1 to formula 2-n is that the maximum number of metal filaments that can be accommodated by a certain conductor layer is calculated by the outer diameter of the conductor layer and the outer diameter of the metal filaments in the conductor layer.

[0087] In the above technical solution, first, the values of N1 to N n are calculated by formula 2-1 to formula 2-n, and the outer diameters d1 to dn , and d1 to dN n , and d1 to dN n , and d1 to dN

[0088] It should be noted that since the total cross-sectional area size of the armor structure 33 needs to be the same as the cross-sectional area size of the conductor structure 11 in the positive electrode core 1 or the negative electrode core 2, the value of S3 can be substituted into the cross-sectional area size of the conductor structure 11 in the positive electrode core 1 or the negative electrode core 2 when calculating. In addition, since d1 to dN n and N n are obtained through iterative calculation, the sum on the left side of formula 1 does not need to be exactly equal to the value of S3, and can be slightly larger than S3, that is, the sum of the cross-sectional areas of the conductor layers of the armor structure 33 is not less than the total cross-sectional area of the conductor structure 11 in the positive electrode core 1 or the negative electrode core 2.

[0089] Through the above setting, according to the relationship between the metal filaments in each conductor layer of the armor structure 33, the light units 31, and the third sheath layer 32, the outer diameter of the metal filaments in each conductor layer of the armor structure 33 can be calculated. According to the above method for designing the armor structure 33, on the one hand, the armor structure 33 can protect the internal light units 31, and on the other hand, the armor structure 33 also has a longitudinal water-blocking function.

[0090] As shown in FIG. 8, in an embodiment of the present application, the composite core 3 further comprises a third sheath layer 32 arranged between the light units 31 and the armor structure 33, and before the armor structure stranding step, the manufacturing method further comprises an extrusion step of extruding the third sheath layer 32 on the outer periphery of the light units 31. Figure 3 As shown in FIG. 9, in an embodiment of the present application, in the extrusion step, the first sheath material and the second sheath material are used for extrusion, the first sheath material and the second sheath material respectively have different markers, and the first sheath material and the second sheath material are arranged alternately along the circumference of the composite core 3, and the armor structure stranding step comprises: a paying-off step of paying off the integrated structure formed by the light units 31 and the third sheath layer 32 through the paying-off rack B1 and moving along the center line of the stranding device B; simultaneously with the paying-off step, using a visual sensor to identify the position of the second sheath material; when the position of the second sheath material deviates from the preset axis, the visual sensor transmits a corresponding retreat signal to the paying-off rack B1 according to the identified position information; the paying-off rack B1 rotates by a corresponding angle according to the retreat signal, so that the second sheath material moves along the preset axis.

[0091] Figure 4

[0092] ​​In the above technical solution, the first sheath material is black, and the second sheath material is yellow. The ratio of the outer surface area of ​​the first sheath material to that of the second sheath material is 4:1. The stranding equipment B adopts a multi-layer frame stranding equipment. With the above settings, the third sheath layer 32 adopts a two-color sheath extrusion. The integrated structure formed by the optical unit 31 and the third sheath layer 32 moves along the center line of the stranding equipment B after being released by the pay-off frame B1. When the integrated structure undergoes self-twist (i.e., rotates around its own central axis), the yellow sheath material part on the outer surface of the third sheath layer 32 deviates from the preset axis. The visual sensor can identify this signal and transmit it to the pay-off frame B1. The pay-off frame B1 can rotate the corresponding angle (i.e., "rewind") according to the twisting direction and angle of the integrated structure, thereby ensuring that during the stranding of the armor structure 33, the self-twist deformation of the integrated structure formed by the optical unit 31 and the third sheath layer 32 will not affect the stranding.

[0093] In an embodiment of the present invention, the armor structure 33 includes a plurality of conductor layers arranged from the inside to the outside, each conductor layer being formed by stranding multiple metal monofilaments. The stranding step of the armor structure includes: a step of stranding multiple conductor layers; and a welding step of welding the conductor layers to adjacent conductor layers after stranding each conductor layer.

[0094] In the above technical solution, during the welding step, adjacent conductor layers are welded to form a solder joint (e.g., Figure 5 As shown, adjacent solder joints are spaced apart in the axial direction of the composite core 3. This avoids the problem of excessively high local temperature in the composite core 3 due to concentrated solder joints, and the staggered welding also improves the tensile strength of the composite core 3.

[0095] In one embodiment of the present invention, the interval between two adjacent solder joints is greater than 30cm.

[0096] In one embodiment of the present invention, in the welding step, argon arc welding is used for welding. The entire welding process is placed in a nitrogen cooling device and the dimensions of the welding point are monitored by thermocouples. If the welding temperature exceeds the limit, forced cooling with nitrogen is required.

[0097] In an embodiment of the present invention, the optical unit 31 is connected by a crimping method with sleeves at both ends.

[0098] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects: when the positive pole core and the negative pole core can work normally, the optical unit in the composite core transmits the communication signal, and the repeater conductive layer connects the repeater and amplifies the optical signal; when any one of the positive pole core and the negative pole core fails and cannot transmit the current, the composite core can serve as a return flow line to ensure that half of the load of the direct current power transmission system works normally, at this time, since the armored structure is composed of metal monofilaments and has the function of conducting electricity, the armored structure can act as a conductor to transmit the current. In this way, the positive pole core, the negative pole core, the composite core (i.e. the core that plays the role of return flow and transmits the optical signal) and the optical fiber unit are integrated into a composite submarine cable, which can not only reduce the construction cost of the submarine cable and save the marine route resources, but also can avoid the problems of waste and reduced service life caused by long-term idling of the return flow submarine cable.

[0099] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A DC composite submarine cable, characterized by The cable core comprises a cable core, an inner cushion layer (7), an armor layer (8) and an outer sheath layer (9) arranged in turn from inside to outside; the cable core comprises a cabling tape (6) and a positive core (1), a negative core (2) and a composite core (3) arranged in turn along the circumference of the cabling tape (6) inside the cabling tape (6), the cable core further comprises a filling structure (4) and at least one optical fiber unit (5) arranged between the positive core (1), the negative core (2) and the composite core (3); Wherein, the composite core (3) comprises an optical unit (31), an armor structure (33), a repeater conductive layer (38) and a first sheath layer (311) arranged in turn from inside to outside, the armor structure (33) is twisted by a plurality of metal filaments, the repeater conductive layer (38) is configured to be able to connect the repeater to amplify the optical signal; the armor structure (33) comprises a plurality of conductor layers from inside to outside, each conductor layer is twisted by a plurality of metal filaments, and the outer diameters of the plurality of metal filaments in each conductor layer are the same.

2. The DC composite submarine cable according to claim 1, characterized by In the adjacent two conductor layers, the outer diameter of the metal filaments in the conductor layer on the outer side is greater than the outer diameter of the metal filaments in the conductor layer on the inner side; or the outer diameters of the metal filaments in the adjacent two conductor layers are the same.

3. The DC composite submarine cable according to claim 1, characterized by A plurality of water-blocking materials are filled between the plurality of metal filaments; and / or, the outer diameters of the metal filaments in the plurality of conductor layers increase in turn from inside to outside along the radial direction of the composite core (3).

4. The DC composite submarine cable according to claim 2, characterized by The composite core (3) further comprises a third sheath layer (32) arranged between the optical unit (31) and the armor structure (33), and the metal filaments in each conductor layer, the optical unit (31) and the third sheath layer (32) satisfy the following relationship: ； ； ； … ； wherein n represents the number of layers of the conductor layer, is the maximum number of metal filaments in the n-th layer of the conductor layer, is the outer diameter of the metal filaments in the n-th layer of the conductor layer, n is an integer greater than or equal to 1, S3 is the total cross-sectional area of the armor structure of the composite core, d0 is the thickness of the third sheath layer, and D is the diameter of the optical unit.

5. The DC composite submarine cable according to claim 4, characterized by The armor structure (33) comprises six conductor layers, and the outer diameters and pitches of the metal filaments in each conductor layer further satisfy the following relationship: ； ； ； ； ； ； Wherein, n is the layer number of the conductor layer, n is an integer greater than or equal to 1; is the maximum number of metal filaments in the nth conductor layer, is the outer diameter of the metal filaments in the nth conductor layer, in mm, is the outer diameter of the nth conductor layer, in mm, is the pitch of the nth conductor layer.

6. The DC composite submarine cable according to any one of claims 1 to 5, characterized in that, The composite core (3) further comprises a first insulating layer (35) arranged between the armor structure (33) and the repeater conductive layer (38), a semi-conductive shielding layer (36) arranged on at least one side of the first insulating layer (35), a first longitudinal water-blocking layer (37) arranged on at least one side of the repeater conductive layer (38), and a first metal shielding layer (310) arranged between the repeater conductive layer (38) and the first sheath layer (311).

7. The DC composite submarine cable according to any one of claims 1 to 5, characterized in that, The optical unit (31) comprises a stainless steel tube and a plurality of optical fibers arranged in the stainless steel tube, and a water-blocking ointment filled in the gap between the plurality of optical fibers; and / or, The positive core (1) comprises, from inside to outside, a conductor structure (11), a conductor shielding layer (12), a second insulation layer (13), an insulation shielding layer (14), a second longitudinal water-blocking layer (15), a second metal shielding layer (16) and a second sheath layer (17), wherein the conductor structure comprises, from inside to outside, a plurality of conductor layers, each of the conductor layers is twisted by a plurality of metal filaments, and the negative core (2) has the same structure as the positive core (1).

8. The DC composite submarine cable according to any one of claims 1 to 5, characterized by The optical unit (31) comprises a stainless steel tube and a plurality of optical fibers arranged in the stainless steel tube, The wall thickness of the stainless steel tube is greater than or equal to 0.5 mm, and the outer diameter D of the stainless steel tube ranges from 2.5 mm to 4.5 mm; and / or, The number of the optical fibers ranges from 2 to 96, the optical fibers are high-temperature-resistant optical fibers, and the high-temperature-resistant optical fibers have a temperature resistance greater than or equal to 300 DEG C.

9. A method of manufacturing a DC composite submarine cable, characterized by, The manufacturing method is used for manufacturing the DC composite submarine cable in any one of claims 1 to 8, and the manufacturing method comprises: a sheath structure twisting step of twisting a plurality of the metal filaments at the outer periphery of the optical unit (31) to form the sheath structure (33); and a step of sequentially arranging the repeater conductive layer (38) and the first sheath layer (311) outside the sheath structure (33) to form the composite core (3).

10. The method of manufacturing a DC composite submarine cable according to claim 9, characterized by, Before the sheath structure twisting step, the manufacturing method further comprises: a metal filament selection step of selecting the specifications of the metal filaments used in each of the conductor layers, wherein the outer diameters of the metal filaments in different conductor layers are the same or different, and the outer diameters of the metal filaments in the same conductor layer are the same, so that the cross-sectional area of the sheath structure (33) is the same as the total cross-sectional area of the conductor structures in the positive core (1) and / or the negative core (2).

11. The method of manufacturing a DC composite submarine cable according to claim 9, characterized by, The composite core (3) further comprises a third sheath layer (32) arranged between the optical unit (31) and the sheath structure (33), and the manufacturing method further comprises an extrusion step of extruding the third sheath layer (32) at the outer periphery of the optical unit (31) before the sheath structure twisting step.

12. The method of manufacturing a DC composite submarine cable according to claim 9, characterized by, The sheath structure (33) comprises a plurality of conductor layers arranged from inside to outside, and each of the conductor layers is twisted by a plurality of the metal filaments, and the sheath structure twisting step comprises: a step of twisting a plurality of the conductor layers; and a welding step of welding the conductor layer to the adjacent conductor layer after twisting each of the conductor layers.

13. The method of manufacturing a DC composite submarine cable according to claim 12, characterized by, In the welding step, two adjacent conductor layers are welded to form a welding point, and two adjacent welding points have a spacing in the axial direction of the composite core (3); and / or, In the welding step, the welding is performed by using an argon arc welding process.

14. The method of manufacturing a DC composite submarine cable according to claim 13, characterized by, The spacing between two adjacent welding points is greater than 30 cm.

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