A crosslinked polyethylene insulated optical fiber submarine cable

Abstract

The utility model discloses a kind of crosslinked polyethylene insulated optical fiber submarine cable, optical fiber unit in conductor is arranged in the center of water-blocking conductor, conductor shielding layer is arranged outside water-blocking conductor, insulating layer is arranged outside conductor shielding layer, insulating shielding layer is arranged outside insulating layer, water-blocking tape wrapping layer is arranged outside insulating shielding layer, metal sheath is arranged outside water-blocking tape wrapping layer, non-metal sheath is arranged outside metal sheath, insulated outer optical fiber unit is arranged outside non-metal sheath, inner liner is arranged outside insulated outer optical fiber unit, armor layer is arranged outside inner liner, outer sheath is arranged outside armor layer;Optical fiber unit in conductor is composed of high-temperature resistant optical fiber, high-temperature resistant oil paste, stainless steel pipe and expansion buffer water-blocking tape.This structure can monitor insulation external temperature parameter, indirectly control the temperature of insulation and conductor, also can directly monitor the temperature of submarine cable conductor, through mutual detection verification, intelligent, high-accuracy temperature detection.

Description

Technical Field

[0001] This utility model relates to the technical field of submarine cables, and in particular to the structure of a cross-linked polyethylene insulated optical fiber submarine cable. Background Technology

[0002] 220kV submarine cable systems are suitable for high-power submarine power transmission for offshore oil and gas platforms, offshore wind power, and island interconnection. They are also suitable for capacity expansion and upgrade projects for submarine cables used in island interconnection. To increase the transmission capacity of submarine cable systems, reduce the weight of submarine cables, and facilitate maintenance, single-core submarine cables are generally designed for power transmission.

[0003] 220kV submarine cables, laid on the seabed, endure various mechanical stresses in complex and harsh working environments, requiring mechanical protection. Based on the characteristics of the mechanical stresses experienced by the submarine cables and the feasibility and economy of their manufacture, galvanized steel wire armor is generally used for protection. Galvanized steel wire armored submarine cables offer good mechanical protection performance. However, the armor has high resistance, the galvanized steel wire is magnetic, easily forming eddy currents, and exhibits significant losses. In large-section submarine cables, the armor loss can even exceed the conductor loss. Excessive losses generate heat, significantly reducing the submarine transmission capacity.

[0004] Existing 220kV submarine cables use either three-core steel wire armored or single-core armored types. Due to the skin effect and proximity effect, the conductor resistance of submarine cables increases significantly, conductor loss increases significantly, and transmission power decreases significantly. Three-core submarine cables generate far more heat than single-core submarine cables, resulting in concentrated heat and a significant reduction in rated current carrying capacity. The armor wires are magnetic, and higher wire resistance also increases armor loss. Currently, submarine cables generally use steel wire armor, which is magnetic and has high resistance. Single-core submarine cables have high armor loss. Using copper wire or other materials with low magnetic properties and low resistance increases the current carrying capacity of submarine cables.

[0005] In single-core fiber optic composite submarine cables, the fiber optic unit is typically designed outside the sheath, with the remaining space within the unit filled with a strip of the same diameter. The diameter of the fiber optic unit is the same as the diameter of the circular filler strip. This design results in greater pressure on both the fiber optic unit and the filler strip, making the fiber optic unit more susceptible to compression from the external armor, particularly radial compression, which can damage it. Even using the same material and specifications for the circular filler strip can lead to tangential compressive stress from the fiber optic unit's structural layers during bending or installation, potentially causing damage to the fiber optic unit.

[0006] The current-carrying capacity of submarine cables is related to the operating temperature of the conductor. Currently, the conductor temperature of submarine cables is obtained through calculation. However, when a short circuit fault occurs or the transmission capacity changes, the dynamic current within the conductor makes the temperature calculation extremely complex and inaccurate. It is also impossible to accurately understand the temperature distribution of the submarine cable. In actual operation, there are localized areas where the conductor temperature of the submarine cable is too high, affecting the normal operation of the product, but it is impossible to accurately detect the overheating of the conductor. Placing sensors in the core layer of the conductor enables real-time monitoring and detection of the conductor temperature of the entire submarine cable. Utility Model Content

[0007] The purpose of this invention is to provide a cross-linked polyethylene insulated optical fiber submarine cable with rated voltage, which can not only monitor the external temperature parameters of the insulation and indirectly control the temperature of the insulation and conductor, but also directly monitor the temperature of the submarine cable conductor. Through mutual detection and verification, the temperature can be detected intelligently and with high accuracy.

[0008] To achieve the above objectives, the technical solution of this utility model is as follows:

[0009] A cross-linked polyethylene insulated optical fiber submarine cable includes a water-blocking conductor, a conductor shielding layer, an insulation layer, an insulating shielding layer, a water-blocking tape wrapping layer, a metallic sheath, a non-metallic sheath, an outer insulating optical fiber unit, an inner liner, an armor layer, an outer jacket layer, and an inner conductor optical fiber unit. The inner conductor optical fiber unit is located at the center of the water-blocking conductor. The conductor shielding layer is located outside the water-blocking conductor. The insulation layer is located outside the conductor shielding layer. The insulating shielding layer is located outside the insulation layer. The water-blocking tape wrapping layer is located outside the insulating shielding layer. The metallic sheath is located on top of the water-blocking tape wrapping layer. Outside the outer layer, the non-metallic sheath is located outside the metallic sheath, the insulating outer optical fiber unit is located outside the non-metallic sheath, the inner liner is located outside the insulating outer optical fiber unit, the armor layer is located outside the inner liner, and the outer sheath is located outside the armor layer; the insulation layer uses XLPE cross-linked polyethylene insulation material; the inner optical fiber unit consists of high-temperature resistant optical fiber, high-temperature resistant grease, stainless steel tube, and expansion buffer water-blocking tape. The high-temperature resistant optical fiber is located in the stainless steel tube, the high-temperature resistant grease is filled between the high-temperature resistant optical fiber and the stainless steel tube, and the expansion buffer water-blocking tape is wrapped around the stainless steel tube.

[0010] The insulated outer optical fiber unit consists of an optical fiber, water-blocking grease, a stainless steel tube, a filler rope, a wrapping layer, and a plastic sheath. The optical fiber is placed inside the stainless steel tube, and water-blocking grease is filled between the optical fiber and the stainless steel tube. The filler rope is wrapped around the stainless steel tube, the wrapping layer is placed on the filler rope, and the plastic sheath is placed outside the wrapping layer.

[0011] The insulated outer optical fiber unit is further reinforced with an insect-proof layer, a PP rope wrapping layer, a filler strip, and a plastic-coated aluminum alloy wire. The insect-proof layer is located outside the non-metallic sheath, and a PP rope wrapping layer is placed on top of the insect-proof layer. The insulated outer optical fiber unit, filler strip, and plastic-coated aluminum alloy wire are located outside the PP rope wrapping layer and are on the same circumference. The filler strip is evenly distributed circumferentially and is made of materials such as polyethylene, polyvinyl chloride, and nylon. The filler material supports and protects the optical unit from damage. The plastic-coated aluminum alloy wire is also evenly distributed circumferentially. The plastic-coated aluminum alloy wire has better hardness than the filler strip and the insulated outer optical fiber unit. A filler strip is placed between the plastic-coated aluminum alloy wire and the insulated outer optical fiber unit, which ensures protection for the insulated outer optical fiber unit and avoids damage to the insulated outer optical fiber unit due to excessive hardness and resilience of the plastic-coated aluminum alloy wire. The inner lining layer is located on the same circumference formed by the insulated outer optical fiber unit, the filler strip, and the plastic-coated aluminum alloy wire.

[0012] An insect-proof layer and an extruded sheath are added to the insulated outer optical fiber unit; the insulated outer optical fiber unit is located on the non-metallic sheath, the extruded sheath is located outside the non-metallic sheath, the insulated outer optical fiber unit is located in the extruded sheath so that the insulated outer optical fiber unit and the extruded sheath are integrated into a whole, the insect-proof layer is located outside the whole of the insulated outer optical fiber unit and the extruded sheath, and the inner lining layer is located on the insect-proof layer.

[0013] The water-blocking conductor is made of tightly compressed circular or segmented annealed copper conductor without metal plating. The conductor is longitudinally wrapped with a high-expansion, low-harmful-gas water-blocking tape covering the gaps in the stranded conductor. Alternatively, a cross-linkable, low-harmful-gas-escape solid filler can be used.

[0014] The conductor shielding layer is composed of a water-blocking tape wrapped around a water-blocking conductor and an extruded semi-conductive shielding material. The water-blocking tape is a high-water-blocking, high-strength, low-harmful-gas-by-product type water-blocking tape, and the semi-conductive shielding material is an ultra-clean and ultra-smooth semi-conductive shielding material. The water-blocking tape is wrapped around the water-blocking conductor, and the semi-conductive shielding material is extruded onto the water-blocking tape.

[0015] The conductor shielding layer, insulation layer, and insulation shielding layer are produced by three-layer synchronous extrusion, with nitrogen rapid cooling at the die head and then rapid heating for cross-linking.

[0016] The insulation layer is made of ultra-clean cross-linked polyethylene material uniformly extruded onto the conductor shielding layer.

[0017] The insulating shielding layer is made by extruding an ultra-smooth semi-conductive shielding material onto the insulating layer.

[0018] The water-blocking tape wrapping layer uses semi-conductive water-blocking tape material wrapped around the insulating shielding layer to avoid damage to the insulated wire core by the external metal sheath. The material expands when it comes into contact with water, which can play a water-blocking role.

[0019] The metal protective layer uses E alloy lead or 1 / 2E alloy lead continuous extrusion structure as a radial waterproof layer, and can also serve as a path for charging current and withstand corresponding short-circuit current.

[0020] The non-metallic sheath is made of semi-conductive or insulating polyethylene, polypropylene, polyvinyl chloride, thermoplastic elastomer, etc., extruded onto the metallic sheath. It can serve as a radial waterproof layer and protect the internal wire core.

[0021] The insect-proof layer is protected by copper strip, stainless steel strip, brass strip or other metal strips, and can also serve as a path for short-circuit current.

[0022] The insulated outer optical fiber unit is equipped with 1-6 groups of high-stress submarine cable-specific optical fibers. The stainless steel tube is made of 316L stainless steel tube and titanium alloy steel tube shear welding, which has high corrosion resistance. The plastic sheath is made of materials with high temperature resistance, excellent water resistance and high mechanical properties.

[0023] The inner lining layer adopts a high-strength polypropylene (PP) fiber rope wrapping structure with a diameter of 1.0-2.0 mm, or a high-strength fiber tape wrapping structure, to protect the insulated outer optical fiber unit from damage to the armor layer.

[0024] The armor layer can be made of copper wire, steel wire, or a mixture of copper and steel wire. Copper wire and steel wire can be connected in a single submarine cable for different laying conditions. Alternatively, a double-layer armor structure design can be adopted, with the inner layer being made of copper wire and the outer layer being made of steel wire.

[0025] The outer sheath consists of an asphalt coating and polypropylene (PP) fiber rope directly wrapped around the armor layer. The asphalt is a special asphalt with high melting point, high adhesion, and resistance to cracking, and the PP fiber rope is made of high-strength materials such as wear-resistant and corrosion-resistant materials.

[0026] By adopting the above solution, this utility model has the following advantages:

[0027] 1. This utility model realizes the interconnection of islands and the supply of power from the land to the islands; it has the advantages of high transmission capacity and low loss.

[0028] 2. This utility model uses non-magnetic, low-resistance armor material, which reduces armor loss of submarine cables and increases transmission capacity under harsh transmission conditions.

[0029] 3. This utility model uses an external optical fiber unit to monitor the external temperature parameters of the insulation in submarine cables. The temperature of the insulation and conductor is indirectly controlled by calculation. At the same time, this utility model designs an internal optical fiber unit in the center of the conductor to directly monitor the temperature of the submarine cable conductor. This combines the direct detection and monitoring of the internal temperature of the conductor with the indirect monitoring of the temperature of the conductor and insulation from the outside, forming a loop. Through mutual detection and verification, the temperature is detected intelligently and with high accuracy through optical fiber.

[0030] 4. This utility model proposes a design and control method for the insulated outer optical fiber unit to ensure that the insulated outer optical fiber unit has excellent mechanical properties.

[0031] 5. This utility model proposes a design and control method for the optical fiber unit inside the conductor, which ensures that the optical fiber unit inside the conductor has excellent mechanical properties, solves the problem of copper single wire stranding damaging the optical unit during the conductor production process, and solves the design and technology process for the optical unit to maintain excellent water-blocking performance without being subjected to tight pressure. Attached Figure Description

[0032] Figure 1 This is a structural schematic diagram of Embodiment 1 of the present invention;

[0033] Figure 2 This is a structural diagram of an insulated external optical fiber unit;

[0034] Figure 3 yes Figure 1 Distribution diagram of the insulated outer optical fiber unit, filler strip, and plastic-coated aluminum alloy wire;

[0035] Figure 4 It is a diagram showing the displacement and force of the insulated outer fiber unit and the filled strip.

[0036] Figure 5 This is a structural diagram of an optical fiber unit within a conductor;

[0037] Figure 6 This is a production flow chart of the optical fiber unit and water-blocking conductor inside the conductor;

[0038] Figure 7 This is a schematic diagram of the fiber optic temperature intelligent detection principle for submarine cable systems.

[0039] Figure 8 This is an analysis diagram of the fiber optic temperature intelligent detection system for submarine cable systems;

[0040] Figure 9 This is the equivalent thermal circuit diagram of an intelligent submarine cable;

[0041] Figure 10 This is a structural schematic diagram of Embodiment 2 of this utility model.

[0042] Label Explanation

[0043] 1. Water-blocking conductor; 2. Conductor shielding layer; 3. Insulation layer; 4. Insulation shielding layer; 5. Water-blocking tape wrapping layer; 6. Metallic sheath; 7. Non-metallic sheath; 8. Insect-proof layer; 9. PP rope wrapping layer; 10. Insulating outer optical fiber unit; 10. Optical fiber; 101. Water-blocking grease; 102. Stainless steel tube; 103. Filler rope; 104. Wrapping layer; 105. Plastic sheath; 106. Filler strip; 11. Plastic-coated aluminum alloy wire; 12. Inner lining layer; 13. Armoring layer; 14. Outer sheath layer; 15. Inner optical fiber unit of conductor; 16. High-temperature resistant optical fiber; 161. High-temperature resistant grease; 162. Stainless steel tube; 163. Expansion buffer water-blocking tape; 164. Extruded sheath; 17. Detailed Implementation

[0044] See Figures 1 to 10 As shown, the present invention discloses a cross-linked polyethylene insulated optical fiber submarine cable, comprising a water-blocking conductor 1, a conductor shielding layer 2, an insulation layer 3, an insulation shielding layer 4, a water-blocking tape wrapping layer 5, a metallic sheath 6, a non-metallic sheath 7, an insulating outer optical fiber unit 10, an inner liner layer 13, an armor layer 14, an outer sheath layer 15, and an inner optical fiber unit 16.

[0045] The water-blocking conductor 1 is made of tightly compressed circular or segmented annealed copper conductor without metal plating. The conductor is longitudinally wrapped with a high-expansion, low-harmful-gas water-blocking tape covering the gaps in the stranded conductor. Alternatively, a cross-linkable, low-harmful-gas-escape solid filler can be used.

[0046] The optical fiber unit 16 inside the conductor is located at the center of the water-blocking conductor 1, in conjunction with... Figure 5 As shown, the conductor inner optical fiber unit 16 is composed of high temperature resistant optical fiber 161, high temperature resistant grease 162, stainless steel tube 163 and expansion buffer water-blocking tape 164. The high temperature resistant optical fiber 161 is disposed in the stainless steel tube 163, the high temperature resistant grease 162 is filled between the high temperature resistant optical fiber 161 and the stainless steel tube 163, and the expansion buffer water-blocking tape 164 is wrapped around the stainless steel tube 163.

[0047] The conductor shielding layer 2 is disposed outside the water-blocking conductor 1. The conductor shielding layer 2 is composed of a water-blocking tape wrapped around the water-blocking conductor and an extruded semi-conductive shielding material. The water-blocking tape is a high-water-blocking, high-strength, low-harmful-gas-by-product type water-blocking tape. The semi-conductive shielding material is an ultra-clean and ultra-smooth semi-conductive shielding material. The water-blocking tape is wrapped around the water-blocking conductor, and the semi-conductive shielding material is extruded onto the water-blocking tape.

[0048] The insulation layer 3 is disposed outside the conductor shielding layer 2, and the insulation layer 3 is made of ultra-clean XLPE cross-linked polyethylene insulation material uniformly extruded onto the conductor shielding layer 2.

[0049] The insulating shielding layer 4 is disposed outside the insulating layer 3, and the insulating shielding layer 4 is made of ultra-smooth semi-conductive shielding material extruded onto the insulating layer 3. The conductor shielding layer 2, the insulating layer 3, and the insulating shielding layer 4 can be extruded simultaneously in three layers, using a nitrogen rapid cooling and then rapid heating cross-linking technology at the die head exit.

[0050] The water-blocking tape wrapping layer 5 is located outside the insulating shielding layer 4. The water-blocking tape wrapping layer 5 is made of semi-conductive water-blocking tape material wrapped around the insulating shielding layer 4 to avoid damage to the insulating core by the external metal sheath. The material expands when it comes into contact with water, which can play a water-blocking role.

[0051] The metal protective layer 6 is disposed outside the water-blocking tape wrapping layer 5. The metal protective layer 6 is made of E alloy lead or 1 / 2E alloy lead continuous extrusion structure as a radial waterproof layer, and can also serve as a path for charging current and withstand the corresponding short-circuit current.

[0052] The non-metallic sheath 7 is disposed outside the metallic sheath 6. The non-metallic sheath 7 is made of semi-conductive or insulating polyethylene, polypropylene, polyvinyl chloride, thermoplastic elastomer, etc., extruded onto the metallic sheath 6. It can serve as a radial waterproof layer and can protect the internal wire core.

[0053] The insulated outer optical fiber unit 10 is disposed outside the non-metallic sheath 7, in conjunction with... Figure 2 As shown, the insulated outer optical fiber unit 10 consists of an optical fiber 101, a water-blocking grease 102, a stainless steel tube 103, a filler rope 104, a cladding layer 105, and a plastic sheath 106. The optical fiber 101 is disposed within the stainless steel tube 103, with water-blocking grease 102 filling the space between the optical fiber 101 and the stainless steel tube 103. The filler rope 104 is wound around the stainless steel tube 103, the cladding layer 105 is disposed on the filler rope 104, and the plastic sheath 106 is disposed outside the cladding layer 105. The insulated outer optical fiber unit 10 has 1-6 groups, and different colored filler strips 11 can be selected on both sides for differentiation. The optical fiber 101 is selected from high-stress submarine cable-specific optical fibers. The stainless steel tube 103 is made of 316L stainless steel tube and titanium alloy steel tube shear welding, possessing high corrosion resistance. The plastic sheath 106 is made of a material with high temperature resistance, excellent water-blocking performance, and superior mechanical properties.

[0054] The inner liner 13 is disposed outside the insulating outer optical fiber unit 10. The inner liner 13 adopts a high-strength polypropylene PP fiber rope wrapping structure with a diameter of 1.0-2.0mm, or it can adopt a high-strength fiber tape wrapping, to protect the insulating outer optical fiber unit 10 from damage by the armor layer 14.

[0055] Figure 1 The image shown is an embodiment of this utility model, in conjunction with... Figure 3 and Figure 4As shown, the insulating outer optical fiber unit 10 is further equipped with an insect-proof layer 8, a PP rope wrapping layer 9, a filler strip 11, and a plastic-coated aluminum alloy wire 12. The insect-proof layer 8 is located outside the non-metallic sheath 7, and the PP rope wrapping layer 9 is provided on the insect-proof layer 8. The insect-proof layer 8 is protected by copper strip, stainless steel strip, brass strip, or other metal strips, and can also serve as a path for short-circuit current. The PP rope wrapping layer 9 adopts a high-strength polypropylene PP fiber rope wrapping structure with a diameter of 1.0-2.0mm, or it can adopt a high-strength fiber tape wrapping. The insulating outer optical fiber unit 10, the filler strip 11, and the plastic-coated aluminum alloy wire 12 are located outside the PP rope wrapping layer 9 and are on the same circumference. The filler strip 11 is evenly distributed circumferentially, and the filler strip 11 is made of polyethylene. The inner lining layer 13 is composed of materials such as polyvinyl chloride and nylon. The filling material supports and protects the insulating outer optical fiber unit 10 from damage. The plastic-coated aluminum alloy wires 12 are evenly distributed around the circumference. The plastic-coated aluminum alloy wires 12 have better hardness than the filling strips 11 and the insulating outer optical fiber unit 10. A filling strip 11 is placed between the plastic-coated aluminum alloy wires 12 and the insulating outer optical fiber unit 10, which not only ensures the protection of the insulating outer optical fiber unit 10, but also avoids damage to the insulating outer optical fiber unit 10 due to excessive hardness and resilience of the plastic-coated aluminum alloy wires 12. Different colored filling strips 11 can also be selected for differentiation. The inner lining layer 13 is located on the same circumference formed by the insulating outer optical fiber unit 10, the filling strips 11, and the plastic-coated aluminum alloy wires 12.

[0056] The armor layer 14 is located outside the inner liner layer 13. The armor layer 14 can be made of copper wire armor, steel wire armor, or both copper wire and steel wire armor. Copper wire and steel wire can be connected in a submarine cable for different laying conditions. Alternatively, a double-layer armor structure design can be adopted, with the inner layer made of copper wire armor and the outer layer made of steel wire armor.

[0057] The outer sheath 15 is disposed outside the armor layer 14. The outer sheath 15 is composed of asphalt coating and polypropylene (PP) fiber rope directly wrapped around the armor layer 14. The asphalt is a special asphalt with high melting point, high adhesion and brittleness resistance, and the PP fiber rope is made of high-strength materials such as wear resistance and corrosion resistance.

[0058] Specifically, in the design, the outer diameter of the insulated outer fiber optic unit 10 is d, the diameter of the plastic-coated aluminum alloy wire 12 and the filler strip 11 between the plastic-coated aluminum alloy wire 12 and the insulated outer fiber optic unit 10 is (d+1.0) mm, the diameter of the other filler strips 11 is (d+0.5) mm, and the diameter of the plastic-coated aluminum alloy wire is (d+1.0) mm. When the submarine cable is subjected to tensile stress, the armor layer 14 steel wire will be radially compressed, and the inner insulated outer fiber optic unit 10 will bear compressive stress. Excessive compressive stress will cause the insulated outer fiber optic unit 10 to be squeezed and deformed. A reasonable design of the filler and the dimensions and protective materials of the insulated outer fiber optic unit 10 significantly reduces the stress borne by the insulated outer fiber optic unit 10. Figure 4The diagram shows the deformation, displacement, and force of the insulated outer optical fiber unit 10 and the filler strip 11. The relationship between the pressure and deformation of the filler strip 11 and the insulated outer optical fiber unit 10 is listed below:

[0059]

[0060] The design and manufacturing process of this utility model for a large-section fiber optic composite compacted conductor water-blocking structure are as follows:

[0061] 1) Design of the conductive part of the composite conductor with built-in water-blocking conductor 1 and fiber unit 16 inside the conductor

[0062] If the conductor is produced using a 169 or 127 coil stranding process, the single wire design diameter d is 4.67 mm or 5.37 mm.

[0063] 2) Design of the fiber optic unit 16 inside the conductor

[0064] The stainless steel tube 163 of the inner fiber unit 16 has a diameter of 2.5 mm and an excess length of 0.5%. The stainless steel tube 163 is covered with a 0.5 mm expansion buffer water-blocking tape 164. The outer diameter of the inner fiber unit 16 is 4.6 mm.

[0065] 3) Manufacturing process design for the 16-unit composite water-blocking conductor within the conductor.

[0066] Cooperate Figure 6 As shown, a 169-reel stranding machine is used for stranding. The inner fiber unit 16 is located in the center layer of the water-blocking conductor 1. Six layers, 12 layers, 18 layers, 24 layers, 30 layers, 36 layers, and 42 layers are stranded sequentially outside the inner fiber unit 16. Seawater-expanding water-blocking material is filled between each layer to ensure the water-blocking performance of the submarine cable.

[0067] This utility model relates to temperature detection and intelligent algorithms for the conductor-inner optical fiber unit 16 and the insulated outer optical fiber unit 10, in conjunction with... Figure 7 , Figure 8 and Figure 9 As shown, the fiber optic unit 16 inside the conductor and the fiber optic unit 10 outside the insulation of the submarine cable are respectively connected to the host of the fiber optic monitoring equipment. The computer converts the optical signal inside the conductor into a temperature electrical signal, compares, analyzes, calculates and corrects the collected fiber optic signal inside the conductor and the temperature signal outside the insulation, and outputs an accurate temperature signal.

[0068] This utility model can be simplified in design according to the application environment. The armor layer 14 adopts single-layer stainless steel wire armor, flat copper wire armor, multi-layer flat copper wire armor, and multi-layer round copper wire armor. Compared with the original solution, the use of multi-layer armor has the advantages of high impact resistance and high tensile strength when applied in laying environments with high pressure.

[0069] Figure 10 The following is a second embodiment of the present invention. The insulating outer optical fiber unit 10 is further provided with an insect-proof layer 8 and an extruded sheath 17. The insulating outer optical fiber unit 10 is disposed on the non-metallic sheath 7, and the extruded sheath 17 is disposed outside the non-metallic sheath. The insulating outer optical fiber unit 10 is located in the extruded sheath 17 so that the insulating outer optical fiber unit 10 and the extruded sheath 17 are integrated into a whole. The insect-proof layer 8 is disposed outside the whole of the insulating outer optical fiber unit 10 and the extruded sheath 17, and the inner lining layer 13 is disposed on the insect-proof layer 8.

[0070] This utility model can also be modified by changing the outer outer layer 15 to an extruded protective layer according to engineering needs, thereby improving the corrosion resistance of the armor.

[0071] This invention provides a cross-linked polyethylene insulated optical fiber submarine cable that enables direct testing of conductor temperature via optical fiber. Compared to the traditional method of testing conductor temperature outside the insulation, this method offers more accurate, sensitive, and direct temperature response, solving the problem that traditional externally insulated optical fiber units cannot test the temperature of short-circuited cables.

[0072] This invention simultaneously tests the conductor temperature and the external insulation temperature, establishes an equivalent thermal circuit model for calculation and analysis, realizes the temperature distribution of the entire cable cross-section, and solves the problem that test data from only fiber optic sensing units inside the conductor or only from optical units outside the insulation cannot accurately reflect the temperature of each layer of the cable.

[0073] This invention designs an optical fiber unit 16 inside a conductor, and designs the relationship between the deformation of the conductor's central part and the compressive stress of the central unit, solving the mechanical damage to the optical unit during the production of the compacted conductor and ensuring the water-blocking problem between the gap of the optical unit and the gap of the copper conductor.

[0074] This utility model designs the insulating outer optical fiber unit 10 and the filling strip 11, and designs the dimensional relationship between the optical fiber unit and the filling strip to ensure that when the submarine cable is under stress, the main stress is transferred to the filling strip, and the insulating outer optical fiber unit 10 is very small in deformation and is not subjected to stress.

[0075] This utility model is applied to intelligent submarine cable solutions with voltage levels of 220kV and below.

[0076] This utility model is applicable to important power transmission equipment for large-capacity island interconnection and interconnection between offshore booster stations and onshore stations in large offshore wind farms. The submarine cable structure of this utility model features two temperature detection structures: an inner conductor fiber optic unit 16 and an outer insulated fiber optic unit 10. These structures can accurately measure the temperature distribution of the conductor and the entire cross-section of the submarine cable. The main application technologies are as follows:

[0077] (1) This utility model is particularly suitable for upgrading and expanding the original submarine cable transmission system. The original voltage system is not changed, and the entire transmission system architecture does not need to be changed. Only the capacity can be increased, avoiding complex project demonstrations, feasibility studies, etc.

[0078] (2) The underwater working conditions are complex, there are transmission bottlenecks, and the safety margin is relatively small for submarine cable transmission systems.

[0079] (3) This utility model is particularly suitable for transmission systems with large and unstable power generation loads, such as offshore wind farms.

[0080] (4) This utility model is particularly suitable for transmission systems where the short-circuit current in the submarine cable transmission system is uncertain, the short-circuit cable is large, and short circuits occur frequently.

[0081] The embodiments described above are only for illustrating the technical ideas and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly, but they do not limit the patent scope of this utility model. All equivalent changes or modifications made in accordance with the spirit disclosed in this utility model should still be covered within the patent scope of this utility model.

Claims

1. A cross-linked polyethylene insulated submarine optical fiber cable, characterized in that: It includes a water-blocking conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, a water-blocking tape wrapping layer, a metallic sheath, a non-metallic sheath, an insulating outer fiber optic unit, an inner liner, an armor layer, an outer sheath, and an inner fiber optic unit within the conductor. The inner fiber optic unit is located at the center of the water-blocking conductor. The conductor shielding layer is located outside the water-blocking conductor. The insulation layer is located outside the conductor shielding layer. The insulation shielding layer is located outside the insulation layer. The water-blocking tape wrapping layer is located outside the insulation shielding layer. The metallic sheath is located outside the water-blocking tape wrapping layer. The non-metallic sheath is located outside the metallic sheath. The insulating outer fiber optic unit is located outside the non-metallic sheath. The inner liner is located outside the insulating outer fiber optic unit. The armor layer is located outside the inner liner. The outer sheath is located outside the armor layer. The insulation layer uses XLPE cross-linked polyethylene insulation material. The inner fiber optic unit consists of high-temperature resistant optical fiber, high-temperature resistant grease, a stainless steel tube, and an expansion buffer water-blocking tape. The high-temperature resistant optical fiber is located inside the stainless steel tube, the high-temperature resistant grease fills the space between the high-temperature resistant optical fiber and the stainless steel tube, and the expansion buffer water-blocking tape wraps around the stainless steel tube.

2. The cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: The insulated outer optical fiber unit consists of an optical fiber, water-blocking grease, a stainless steel tube, a filler rope, a wrapping layer, and a plastic sheath. The optical fiber is placed inside the stainless steel tube, and water-blocking grease is filled between the optical fiber and the stainless steel tube. The filler rope is wrapped around the stainless steel tube, the wrapping layer is placed on the filler rope, and the plastic sheath is placed outside the wrapping layer.

3. The cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: The insulated outer optical fiber unit is further equipped with an insect-proof layer, a PP rope wrapping layer, a filler strip, and a plastic-coated aluminum alloy wire. The insect-proof layer is located outside the non-metallic sheath, and the PP rope wrapping layer is located on the insect-proof layer. The insulated outer optical fiber unit, the filler strip, and the plastic-coated aluminum alloy wire are located outside the PP rope wrapping layer and are on the same circumference. The filler strip is evenly distributed around the circumference. The plastic-coated aluminum alloy wire is evenly distributed around the circumference, and there is a filler strip between the plastic-coated aluminum alloy wire and the insulated outer optical fiber unit. The inner lining layer is located on the same circumference formed by the insulated outer optical fiber unit, the filler strip, and the plastic-coated aluminum alloy wire.

4. The cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: An insect-proof layer and an extruded sheath are added to the insulated outer optical fiber unit; the insulated outer optical fiber unit is located on the non-metallic sheath, the extruded sheath is located outside the non-metallic sheath, the insulated outer optical fiber unit is located in the extruded sheath so that the insulated outer optical fiber unit and the extruded sheath are integrated into a whole, the insect-proof layer is located outside the whole of the insulated outer optical fiber unit and the extruded sheath, and the inner lining layer is located on the insect-proof layer.

5. A cross-linked polyethylene insulated submarine optical fiber cable according to claim 3 or 4, characterized in that: The insect-proof layer is made of copper strip, stainless steel strip, or brass strip.

6. The cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: The water-blocking conductor is made of tightly compressed circular or segmented annealed copper conductor without metal plating. The conductor is longitudinally wrapped with a high-expansion, low-harmful-gas water-blocking tape covering the gaps in the stranded conductor, or it is filled with a cross-linkable, low-harmful-gas-escape solid filler.

7. The cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: The conductor shielding layer is composed of a water-blocking tape wrapped around a water-blocking conductor and an extruded semi-conductive shielding material. The water-blocking tape is a high-water-blocking, high-strength, low-harmful-gas-by-product type water-blocking tape, and the semi-conductive shielding material is an ultra-clean and ultra-smooth semi-conductive shielding material. The water-blocking tape is wrapped around the water-blocking conductor, and the semi-conductive shielding material is extruded onto the water-blocking tape.

8. A cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: The conductor shielding layer, the insulation layer, and the insulation shielding layer are produced by simultaneous extrusion of three layers.

9. A cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: The water-blocking tape wrapping layer is made of semi-conductive water-blocking tape material wrapped around the insulating shielding layer; the metal sheath is made of E alloy lead or 1 / 2E alloy lead continuous extrusion structure; the non-metallic sheath is made of semi-conductive or insulating polyethylene, polypropylene, polyvinyl chloride, or thermoplastic elastomer extruded onto the metal sheath.

10. A cross-linked polyethylene insulated submarine optical fiber cable according to claim 1, characterized in that: The inner lining layer adopts a high-strength polypropylene PP fiber rope wrapping structure with a diameter of 1.0-2.0mm or a high-strength fiber tape wrapping structure; the armor layer adopts copper wire armor, steel wire armor, or a mixture of copper wire and steel wire armor, or adopts a double-layer armor structure design, that is, the inner layer is copper wire armor and the outer layer is steel wire armor; the outer sheath layer is composed of asphalt coating and polypropylene PP fiber rope directly wrapped around the armor layer.

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