An aluminum core submarine cable system and method of manufacture

Abstract

The application provides an aluminum core submarine cable system and a preparation method, relates to the technical field of submarine cables, and comprises three filler bodies, water-blocking aluminum conductors penetrating through the inner sides of the filler bodies, and layered wrapping structures extending in the inner sides of the filler bodies; the layered wrapping structures comprise an insulation assembly, an internal protection assembly and an external protection assembly. The application adopts a layered wrapping conductor shielding, a wrapping type crosslinked polyethylene insulation and a tubular insulation shielding layer and carries out an integral vulcanization process to restore the factory joint insulation, and combines electromagnetic-thermal-force multi-physical field coupling simulation in the design stage, so that the joint insulation structure is realized without air gap and densified forming, the electrical, mechanical and thermal performances are optimized in advance through the simulation means, the insulation integrity, field strength distribution and long-term thermal mechanical stability of the joint are ensured to be highly consistent with the cable body, and the risk of partial discharge or breakdown caused by interface defects is effectively eliminated.

Description

Technical Field

[0001] This invention relates to the field of submarine cable technology, and in particular to an aluminum core submarine cable system and its manufacturing method. Background Technology

[0002] As global offshore wind power develops towards deeper waters and larger capacities, submarine cables with voltage levels of 66kV and above have become a key carrier for power transmission capacity. Replacing traditional copper conductors with aluminum conductors can significantly reduce material costs and cable weight, facilitating construction and laying, and has become a clear technological development trend in the industry.

[0003] Existing technologies mostly focus on the local optimization of aluminum rod composition or single process parameters, lacking a comprehensive collaborative solution that covers the entire chain from material basis to connection system, and from process innovation to digital verification, thus failing to systematically meet the engineering requirements for high-reliability power transmission in deep sea. Summary of the Invention

[0004] To address the technical problem that existing technologies often focus on localized optimization of aluminum rod composition or single process parameters, lacking a comprehensive, chain-wide collaborative solution from material fundamentals to connection systems, and from process innovation to digital verification, thus failing to systematically meet the engineering requirements for high-reliability power transmission in deep seas, this invention provides an aluminum core submarine cable system and its preparation method.

[0005] The technical solutions provided by the embodiments of the present invention are as follows: The present invention provides an aluminum core submarine cable system and manufacturing method, comprising: three filler bodies, a water-blocking aluminum conductor penetrating the inner side of the filler bodies, and a layered wrapping structure extending from the inner side of the filler bodies; The layered wrapping structure includes an insulating component, an internal protective component, and an external protective component; The insulation components include an XLPE insulation sleeve, an insulation shielding sleeve, an alloy lead sleeve, and a semi-conductive PE inner sheath; The internal protective components include a conductive stress cone, a copper-aluminum transition connector, an inner shielding tube, a main insulating material, and a copper shell. The external protective components include a first polypropylene rope, galvanized steel wire armor, a second polypropylene rope, and a third polypropylene rope.

[0006] The insulating component is sleeved on the outside of the water-blocking aluminum conductor.

[0007] Furthermore, the outer arc surface of the filling material body is provided with an inwardly recessed groove, and an optical unit is provided on the inner side of the groove; The optical units are arranged in a ring array along the center point of multiple filler bodies.

[0008] Furthermore, the water-blocking aluminum conductor is made from a high-purity aluminum ingot that has undergone boronizing treatment, and three water-blocking aluminum conductors are provided, and the three water-blocking aluminum conductors are distributed in an equidistant array along the center of the three filler bodies. The water-blocking aluminum conductor at the joint is argon-arc welded using aluminum-silicon welding wire with a melting point of 577℃~660℃.

[0009] Furthermore, the metal connection part of the copper-aluminum transition connector uses an integral tin-plated or silver-plated copper-aluminum bolted connection tube to connect the aluminum conductor and the copper conductor, and the clamping bolts of the copper-aluminum transition connector are spirally distributed.

[0010] Furthermore, the inner shielding tube is arranged in a ring shape and is sleeved on the outside of the connection ends of the two water-blocking aluminum conductors.

[0011] Furthermore, the first polypropylene ropes are distributed in an equidistant array to form a ring, and the first polypropylene ropes forming the ring are sleeved on the outer arc surface of the ring formed by the three filler bodies.

[0012] Furthermore, the galvanized steel wire armor is disposed between the first polypropylene rope and the second polypropylene rope, and the galvanized steel wire armor is distributed in a ring array.

[0013] Furthermore, multiple second polypropylene ropes are provided, and the multiple second polypropylene ropes are distributed in a ring array.

[0014] Furthermore, the third polypropylene rope is arranged in a circular array along the center point of the three filler bodies; In a second aspect of the present invention, a method for preparing an aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system is proposed, which is applied to the aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system of the first aspect, and includes the following steps; Step 1: First, using aluminum ingots with a purity ≥ 99.85% as raw material, an Al-B master alloy is added during smelting for boronizing treatment. The melt is then degassed, filtered, continuously cast and rolled, and solution treated at 530-540℃ to obtain the resistivity. The aluminum rod is drawn into a single wire and then twisted on a frame stranding machine. At the same time, it is wrapped with semi-conductive water-resistant binding tape with an overlap rate of 15%~20%. The conductor must pass 10 thermal cycles and be subjected to a water pressure of 1.0 MPa to ensure that there is no water leakage at the end. Step Two: Subsequently, in a Class 1000 cleanroom environment, using a barrier-type screw with a length-to-diameter ratio of 30:1 and a multi-layer co-extrusion die head, the conductor shielding material, the XLPE insulation material mixed with peroxide crosslinking agent, and the insulation shielding material are simultaneously coated in one go. Then, they enter the VCV pipeline and are rapidly heated to approximately 280°C. High-purity nitrogen gas at a pressure ≥1.0 MPa is introduced into the pipeline for protective crosslinking and defect suppression. After crosslinking, the core wire is cooled and then treated in a three-stage gradient degassing chamber for 72-120 hours, with the final insulation eccentricity ≤1.5%. Step 3: Subsequently, a production line is constructed by connecting a lead extruder and a plastic extruder. The alloy lead sleeve is made of lead-antimony-copper alloy. The lead melting furnace is controlled at 360-380℃ and the die base at 270-290℃. After the alloy lead sleeve is extruded and initially water-cooled, it is immediately coated with an epoxy anti-corrosion layer and then pulled to the plastic extruder to extrude a semi-conductive PE inner sheath. By precisely matching the traction speed, the difference in eccentricity between the semi-conductive PE inner sheath and the alloy lead sleeve is controlled to ≤0.6mm. The production line is equipped with a UPS and a "one-in-use-one-backup" motor to ensure continuous and stable operation. Step 4: Then wrap a layer of inner lining with PP rope. For galvanized steel wire armor, the galvanized high carbon steel wire is first stress-relieved by a pre-twist device, and then dipped twice with 120-150℃ hot asphalt on a vertical cable forming and armoring machine. During armoring, the gap between the steel wires is controlled to be less than or equal to the diameter of a single wire to form a tight armor layer without skipped wires. After armoring, two layers of PP rope with opposite directions and the inner layer coated with asphalt are tightly wrapped, and the wrapping tension is controlled to be 50±5 N to form the final outer protective layer. Step 5: Fabrication and simulation optimization of the flexible joint in the factory. The conductor is welded using aluminum-silicon welding wire for argon arc welding with ER4043 welding wire. Immediately after welding, the adjustable air cooling system is started for rapid cooling. Within 180 seconds, the temperature of the welded area drops from 620℃ to 58℃. The tensile strength of the joint is 105 MPa. The insulation restoration adopts a process of layered wrapping of conductor shielding, insulation, and insulation shielding, followed by integrated vulcanization. In the joint design stage, the welding temperature field, stress distribution, and electric field strength are simulated and optimized by combining finite element analysis and electromagnetic-thermal-mechanical multiphysics field coupling simulation to ensure that the electrical performance, mechanical strength, and thermal stability of the joint meet the requirements of deep-sea operation. Step Six: Preparation of aluminum transition connecting pipe. The conductor is crimped using an integral tin-plated / silver-copper-aluminum connecting pipe fastened with spiral bolts. The integral prefabricated insulating component with high interface strength is then installed using co-extrusion one-time molding technology. Step 7: Finally, connect the cable body, factory flexible joint, and copper-aluminum transition connector to form a complete system. The system undergoes comprehensive electrical, mechanical, and long-term cyclic testing. It passes the combined cyclic test of 132kV / 30min withstand voltage, ±550kV lightning impulse, and 50kN tension-30D bending-1.5MPa water pressure, and its performance fully meets the standards.

[0015] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this invention, a process of layered wrapping conductor shielding, wrapping cross-linked polyethylene insulation, and tubular insulation shielding layer followed by integrated vulcanization is used to restore the factory joint insulation. In the design stage, electromagnetic-thermal-mechanical multi-physics field coupling simulation is combined. The advantage is that the joint insulation structure is air gap-free and densely formed. The electrical, mechanical, and thermal performance is pre-optimized through simulation, ensuring that the insulation integrity, field strength distribution, and long-term thermomechanical stability of the joint are highly consistent with the cable body, effectively eliminating the risk of partial discharge or breakdown caused by interface defects. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of an aluminum core submarine cable system and its manufacturing method provided in an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the main cross-sectional structure of the filler in an aluminum core submarine cable system and its preparation method provided in an embodiment of the present invention.

[0019] Figure 3 An aluminum core submarine cable system and its manufacturing method are provided in this embodiment of the invention. Figure 2 Enlarged structural diagram at point A in the middle.

[0020] Figure 4 This is a schematic diagram of the overall cross-sectional structure of an aluminum core submarine cable system and its manufacturing method provided in an embodiment of the present invention.

[0021] Figure 5 This is a side view of the filler body structure of an aluminum core submarine cable system and its preparation method provided in an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of the connection structure between the filler body and the optical unit in an aluminum core submarine cable system and its preparation method provided in an embodiment of the present invention.

[0023] Figure 7 This is a side view of the copper shell structure of an aluminum core submarine cable system and its manufacturing method provided in an embodiment of the present invention.

[0024] Figure 8 A cross-sectional view of the copper shell of an aluminum core submarine cable system and its manufacturing method provided in an embodiment of the present invention.

[0025] Figure 9 This is a schematic diagram of the copper shell cross-section structure of an aluminum core submarine cable system and its manufacturing method provided in an embodiment of the present invention.

[0026] Figure 10 An aluminum core submarine cable system and its manufacturing method are provided in this embodiment of the invention. Figure 9 Enlarged structural diagram at point B.

[0027] Reference numerals: 1. Main filler; 2. Water-blocking aluminum conductor; 3. XLPE insulating sleeve; 4. Insulating shielding sleeve; 5. Alloy lead sleeve; 6. Semi-conductive PE inner sheath; 7. Conductive stress cone; 8. Copper-aluminum transition connector; 9. Inner shielding tube; 10. Main insulating material; 11. Copper shell; 12. Optical unit; 13. First polypropylene rope; 14. Galvanized steel wire armor; 15. Second polypropylene rope; 16. Third polypropylene rope.

[0028] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to this specific structure, device and environment. Those skilled in the art can adjust or modify these devices and environments according to specific needs. Detailed Implementation

[0029] The technical solutions of the present invention will now be described with reference to the accompanying drawings. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies. Furthermore, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0030] like Figures 1 to 10 As shown, an embodiment of the present invention provides an aluminum core submarine cable system and a manufacturing method, comprising: three filler bodies 1, a water-blocking aluminum conductor 2 penetrating the inner side of the filler bodies 1, and a layered wrapping structure extending from the inner side of the filler bodies 1. The layered wrapping structure includes an insulating component, an internal protective component, and an external protective component; The insulation assembly includes an XLPE insulation sleeve 3, an insulation shielding sleeve 4, an alloy lead sleeve 5, and a semi-conductive PE inner sheath 6. The internal protective components include a conductive stress cone 7, a copper-aluminum transition connector 8, an inner shielding tube 9, a main insulating material 10, and a copper shell 11. The external protective components include a first polypropylene rope 13, a galvanized steel wire armor 14, a second polypropylene rope 15, and a third polypropylene rope 16.

[0031] The insulating component is sleeved on the outside of the water-blocking aluminum conductor 2; In this embodiment of the invention, during the cable manufacturing process, the water-blocking aluminum conductor 2 of the cable body is made from high-purity aluminum ingots that have undergone boronizing treatment. The aluminum ingots, after continuous casting and rolling and specific processing, result in an aluminum rod whose resistivity at a specified time does not exceed a certain threshold. The monofilaments drawn from this aluminum rod are stranded into a 3*1200mm diameter cable. 2 The cross-section conductor is specifically designed for environments with a water depth of 150 meters. Then, the water-blocking aluminum conductor 2 at the joint is argon-arc welded using aluminum-silicon welding wire with a melting point of 577℃~660℃. Immediately after welding, an adjustable air-cooling device is used to rapidly cool the welded area, requiring the temperature of the heat-affected zone to decrease by more than 90℃ within a certain time, thereby minimizing the loss of single-wire strength. The completed joint conductor has an outer diameter deviation from the cable body's outer diameter controlled within ±0.8%, and an overall tensile strength of not less than 100. MPa, the insulation restoration of the joint adopts a layered wrapping type XLPE insulating sleeve 3, insulating shielding sleeve 4, alloy lead sleeve 5, and semi-conductive PE inner sheath 6, and is integrally vulcanized. The metal connection part of the copper-aluminum transition connector 8 adopts an integral tin-plated or silver-plated copper-aluminum bolted connecting pipe 8 to achieve the connection between the water-blocking aluminum conductor 2 and the copper conductor. The clamping bolts of the copper-aluminum transition connector 8 are spirally distributed to ensure uniform pressure. At the same time, the insulation component of the copper-aluminum transition connector 8 is an integral prefabricated structure, and the dielectric strength of its insulation material is not less than 38kV / mm. The insulation component is manufactured by a co-extrusion one-time molding process of inner shielding tube 9, main insulation material 10, and copper shell 11 to ensure that the interface bonding strength is not less than 3.6. To completely eliminate internal air gaps, after preparation, a layer of inner lining is wrapped with the first polypropylene rope 13. The galvanized high-carbon steel wire used for armoring is first stress-relieved by a pre-twist device, and then dipped twice with hot asphalt at 120-150℃ on a vertical cable-forming and armoring machine. During armoring, the spacing between the steel wires is controlled to be ≤ the diameter of a single wire, so as to form galvanized steel wire armor 14. After armoring, two layers of reverse-directional second polypropylene rope 15 and third polypropylene rope 16 with the inner layer coated with asphalt are tightly wrapped, and the wrapping tension is controlled to be 50±5 N, forming the final outer protective layer.

[0032] In one possible implementation, the outer arc surface of the filling body 1 is provided with an inwardly recessed groove, and an optical unit 12 is provided on the inner side of the groove. The optical units 12 are distributed in a ring array along the center point of multiple filler bodies 1; In this embodiment of the invention, the optical unit 12 disposed inside the filling body 1 is used to undertake the two core functions of information communication transmission and distributed status monitoring, and has technical advantages such as anti-electromagnetic interference, small size and light weight, and large transmission capacity.

[0033] In one possible implementation, the water-blocking aluminum conductor 2 is made from a high-purity aluminum ingot that has undergone boronizing treatment, and three water-blocking aluminum conductors 2 are provided, and the three water-blocking aluminum conductors 2 are distributed in an equidistant array along the center of the three filler bodies 1. Among them, the water-blocking aluminum conductor 2 at the joint is argon arc welded using aluminum-silicon welding wire with a melting point of 577℃~660℃; In this embodiment of the invention, the water-blocking aluminum conductor 2, which is made by argon arc welding of aluminum-silicon welding wire with a melting point of 577℃~660℃, can minimize the loss of single wire strength. The outer diameter of the completed joint conductor is controlled within ±0.8% of the outer diameter of the cable body, and the overall tensile strength is not less than 100 MPa.

[0034] In one possible implementation, the metal connection portion of the copper-aluminum transition connector 8 is made of an integral tin-plated or silver-plated copper-aluminum bolted connection tube to connect the aluminum conductor and the copper conductor, and the clamping bolts of the copper-aluminum transition connector 8 are spirally distributed. In this embodiment of the invention, the clamping bolts of the copper-aluminum transition connector 8 are spirally distributed to ensure uniform pressure, and their tensile strength is not less than 75% of the cable body strength.

[0035] In one possible implementation, the inner shielding tube 9 is arranged in a ring shape, and the inner shielding tube 9 is sleeved on the outside of the connection ends of the two water-blocking aluminum conductors 2. In this embodiment of the invention, the inner shielding tube 9 sleeved on the outside of the water-blocking aluminum conductor 2 can provide effective insulation.

[0036] In one possible implementation, the first polypropylene ropes 13 are distributed in an equidistant array to form a ring, and the first polypropylene ropes 13 forming the ring are sleeved on the outer arc surface of the ring formed by the three filler bodies 1. In this embodiment of the invention, the combination of the first polypropylene rope 13, the second polypropylene rope 15 and the third polypropylene rope 16 can facilitate the subsequent improvement of the structural strength of the entire cable itself, while also providing effective protection.

[0037] In one possible implementation, the galvanized steel wire armor 14 is disposed between the first polypropylene rope 13 and the second polypropylene rope 15, and the galvanized steel wire armor 14 is distributed in a ring array. In this embodiment of the invention, the galvanized steel wire armor 14 controls the gap between the steel wires to be less than or equal to the diameter of a single wire during armoring, thereby forming a tight armor layer without skipped wires.

[0038] In one possible implementation, multiple second polypropylene ropes 15 are provided, and the multiple second polypropylene ropes 15 are distributed in a ring array. In this embodiment of the invention, the annular array arrangement of the second polypropylene rope 15 can further provide effective protection for the internal water-blocking aluminum conductor 2.

[0039] In one possible implementation, the third polypropylene rope 16 is arranged in a circular array along the center point of the three filler bodies 1; In this embodiment of the invention, multiple third polypropylene ropes 16 arranged in a ring array can control the wrapping tension to form the final outer protective layer.

[0040] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this invention, a resistivity is prepared by adding trace elements to high-purity aluminum ingots and performing boronizing treatment. The high-conductivity aluminum rod solves the industry problem of balancing conductivity and mechanical strength in water-blocking aluminum conductors from the material source, enabling its design for applications in water depths of up to 150 meters and 3*1200mm rods. 2 The large cross-section submarine cable conductor provides performance assurance, enabling the quantifiable design of its tensile, torsional, and bending stiffness. At the same time, it reduces the overall cost of aluminum core submarine cables by about 23.5% compared to copper core solutions, achieving a balance between high performance and high economy. In this invention, aluminum-silicon welding wire with a melting point of 577℃~660℃ is used for argon arc welding, and an adjustable air cooling device is innovatively used to rapidly cool the welding area. The advantage is that it greatly reduces the range of the welding heat-affected zone, minimizes the strength loss of the aluminum conductor wire caused by welding heat input, ensures that the overall tensile strength of the conductor of the factory flexible joint exceeds 100MPa, and controls the deviation between the outer diameter and the body within ±0.8%, thereby fundamentally improving the mechanical reliability of the joint and making it no longer a weak link in the system. In this invention, a process of layered wrapping conductor shielding, wrapping cross-linked polyethylene insulation and tubular insulation shielding layer and integral vulcanization is used to restore the factory joint insulation. In the design stage, electromagnetic-thermal-mechanical multi-physics field coupling simulation is combined. The advantage is that the joint insulation structure is air gap-free and densely formed. The electrical, mechanical and thermal performance is pre-optimized by simulation, ensuring that the insulation integrity, field strength distribution and long-term thermomechanical stability of the joint are highly consistent with the cable body, effectively eliminating the risk of partial discharge or breakdown caused by interface defects. In this invention, the high-performance water-blocking aluminum conductor, the highly reliable factory flexible joint, and the highly stable copper-aluminum transition connector are integrated into a complete submarine cable system. Through full-process process control and simulation verification, the advantage is that a set of aluminum core submarine cable solutions that have been optimized and verified from materials and components to the whole system have been constructed, systematically solving the four core challenges of conductivity, mechanics, connection and insulation of aluminum core submarine cables in deep-sea applications.

[0041] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A composite submarine cable system with aluminum core, cross-linked polyethylene insulated optical fiber, characterized in that, include: Three main filler bodies, a water-blocking aluminum conductor penetrating the inner side of the main filler bodies, and a layered wrapping structure extending from the inner side of the main filler bodies; The layered wrapping structure includes an insulating component, an internal protective component, and an external protective component; The insulation components include an XLPE insulation sleeve, an insulation shielding sleeve, an alloy lead sleeve, and a semi-conductive PE inner sheath; The internal protective components include a conductive stress cone, a copper-aluminum transition connector, an inner shielding tube, a main insulating material, and a copper shell. The external protective components include a first polypropylene rope, galvanized steel wire armor, a second polypropylene rope, and a third polypropylene rope; The insulating component is sleeved on the outside of the water-blocking aluminum conductor.

2. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 1, characterized in that, The outer arc surface of the filling material body is provided with an inwardly recessed groove, and an optical unit is provided on the inner side of the groove. The optical units are arranged in a ring array along the center point of multiple filler bodies.

3. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 2, characterized in that, The water-blocking aluminum conductor is made from a high-purity aluminum ingot that has undergone boronizing treatment, and three water-blocking aluminum conductors are provided, and the three water-blocking aluminum conductors are distributed in an equidistant array along the center of the three filler bodies. The water-blocking aluminum conductor at the joint is argon-arc welded using aluminum-silicon welding wire with a melting point of 577℃~660℃.

4. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 3, characterized in that, The metal connection part of the copper-aluminum transition connector uses an integral tin-plated or silver-plated copper-aluminum bolted connection tube to connect the aluminum conductor and the copper conductor. The clamping bolts of the copper-aluminum transition connector are spirally distributed.

5. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 4, characterized in that, The inner shielding tube is arranged in a ring shape and is sleeved on the outside of the connection ends of the two water-blocking aluminum conductors.

6. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 5, characterized in that, The first polypropylene ropes are distributed in an equidistant array to form a ring, and the first polypropylene ropes forming the ring are sleeved on the outer arc surface of the ring formed by the three filler bodies.

7. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 6, characterized in that, The galvanized steel wire armor is disposed between the first polypropylene rope and the second polypropylene rope, and the galvanized steel wire armor is distributed in a ring array.

8. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 7, characterized in that, Multiple second polypropylene ropes are provided, and the multiple second polypropylene ropes are distributed in a ring array.

9. The aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to claim 8, characterized in that, The third polypropylene rope is distributed in a circular array along the center point of the three filler bodies.

10. The method for preparing an aluminum core cross-linked polyethylene insulated optical fiber composite submarine cable system according to any one of claims 1 to 9, characterized in that... Includes the following steps; Step 1: First, using aluminum ingots with a purity ≥ 99.85% as raw material, an Al-B master alloy is added during smelting for boronizing treatment. The melt is then degassed, filtered, continuously cast and rolled, and solution treated at 530-540℃ to obtain the resistivity. The aluminum rod is drawn into a single wire and then twisted on a frame stranding machine. At the same time, it is wrapped with semi-conductive water-resistant binding tape with an overlap rate of 15%~20%. The conductor must pass 10 thermal cycles and be subjected to a water pressure of 1.0 MPa to ensure that there is no water leakage at the end. Step Two: Subsequently, in a Class 1000 cleanroom environment, using a barrier-type screw with a length-to-diameter ratio of 30:1 and a multi-layer co-extrusion die head, the conductor shielding material, the XLPE insulation material mixed with peroxide crosslinking agent, and the insulation shielding material are simultaneously coated in one go. Then, they enter the VCV pipeline and are rapidly heated to approximately 280°C. High-purity nitrogen gas at a pressure ≥1.0 MPa is introduced into the pipeline for protective crosslinking and defect suppression. After crosslinking, the core wire is cooled and then treated in a three-stage gradient degassing chamber for 72-120 hours, with the final insulation eccentricity ≤1.5%. Step 3: Subsequently, a production line is constructed by connecting a lead extruder and a plastic extruder. The alloy lead sleeve is made of lead-antimony-copper alloy. The lead melting furnace is controlled at 360-380℃ and the die base at 270-290℃. After the alloy lead sleeve is extruded and initially water-cooled, it is immediately coated with an epoxy anti-corrosion layer and then pulled to the plastic extruder to extrude a semi-conductive PE inner sheath. By precisely matching the traction speed, the difference in eccentricity between the semi-conductive PE inner sheath and the alloy lead sleeve is controlled to ≤0.6mm. The production line is equipped with a UPS and a "one-in-use-one-backup" motor to ensure continuous and stable operation. Step 4: Then wrap a layer of inner lining with PP rope. For galvanized steel wire armor, the galvanized high carbon steel wire is first stress-relieved by a pre-twist device, and then dipped twice with 120-150℃ hot asphalt on a vertical cable forming and armoring machine. During armoring, the gap between the steel wires is controlled to be less than or equal to the diameter of a single wire to form a tight armor layer without skipped wires. After armoring, two layers of PP rope with opposite directions and the inner layer coated with asphalt are tightly wrapped, and the wrapping tension is controlled to be 50±5 N to form the final outer protective layer. Step 5: Fabrication and simulation optimization of the flexible joint in the factory. The conductor is welded using aluminum-silicon welding wire for argon arc welding with ER4043 welding wire. Immediately after welding, the adjustable air cooling system is started for rapid cooling. Within 180 seconds, the temperature of the welded area drops from 620℃ to 58℃. The tensile strength of the joint is 105 MPa. The insulation restoration adopts a process of layered wrapping of conductor shielding, insulation, and insulation shielding, followed by integrated vulcanization. In the joint design stage, the welding temperature field, stress distribution, and electric field strength are simulated and optimized by combining finite element analysis and electromagnetic-thermal-mechanical multiphysics field coupling simulation to ensure that the electrical performance, mechanical strength, and thermal stability of the joint meet the requirements of deep-sea operation. Step Six: Preparation of aluminum transition connecting pipe. The conductor is crimped using an integral tin-plated / silver-copper-aluminum connecting pipe fastened with spiral bolts. The integral prefabricated insulating component with high interface strength is then installed using co-extrusion one-time molding technology. Step 7: Finally, connect the cable body, factory flexible joint, and copper-aluminum transition connector to form a complete system. The system undergoes comprehensive electrical, mechanical, and long-term cyclic testing. It passes the combined cyclic test of 132kV / 30min withstand voltage, ±550kV lightning impulse, and 50kN tension-30D bending-1.5MPa water pressure, and its performance fully meets the standards.

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