A high-voltage three-core submarine cable

Abstract

The application belongs to the technical field of submarine cables and provides a high-voltage three-core submarine cable. The submarine cable comprises a cable core, a water-blocking layer, an inner sheath, an armored layer and an outer sheath. The cable core comprises at least one conductive core. The conductive core comprises a conductor and an insulation system arranged outside the conductor. The insulation system comprises a conductor shielding layer, an insulation layer and an insulation shielding layer. The conductivity of the conductor shielding layer gradually decreases from inside to outside in the radial direction of the conductive core. The conductivity of the insulation shielding layer gradually decreases from outside to inside in the radial direction of the conductive core. The interface between the conductor shielding layer and the insulation layer is prevented from gathering electric charges, and the electric field distribution between the conductor shielding layer and the insulation shielding layer is greatly optimized. Similarly, the insulation shielding layer is arranged to gradually increase in conductivity away from the insulation layer, the interface electric field between the insulation layer and the insulation shielding layer is optimized, and the electric charges at the interface of the insulation layer can be quickly introduced into the insulation shielding layer, thereby preventing the generation of partial discharge.

Description

Technical Field

[0001] This application relates to the field of submarine cable technology, specifically to a high-voltage three-core submarine cable. Background Technology

[0002] Submarine power cables typically have an armor layer consisting of multiple armored wires. These armored wires are usually spirally wound around a single or multi-core cable. The armor layer provides mechanical protection during cable installation and operation, preventing lateral impacts. In AC power cables, alternating magnetic fields can induce different types of losses within the armor layer. For example, in a plane parallel to the cable axis, a circular induced current can form inside a single wire; this type of loss is called eddy current loss.

[0003] Using non-magnetic metals such as stainless steel or copper can significantly reduce eddy current losses; however, these alternatives are much more expensive than low-carbon steel. Furthermore, using high-grade steel can increase the tensile strength of the armor, but high-grade steel is also more expensive than low-carbon steel. Some designs propose adding a plating or resin coating to the steel wires, but the gaps between the armor wires still present technical problems such as moisture infiltration or structural instability. Others have proposed using non-metallic armor wires, such as those made of aramid or para-aramid. This can increase the tensile strength of the armor and reduce weight; however, non-armored wires lack the electromagnetic shielding effect of metallic armor, and the cable will still have significant losses.

[0004] On the other hand, the losses of metal armor are also affected by the cable insulation and conductive shielding effectiveness. The dielectric constant and loss coefficient of the insulation layer directly affect the propagation speed and attenuation characteristics of electromagnetic waves in the shielding layer. Poor fit between the shielding layer and the insulation layer may cause electromagnetic waves to leak through air gaps or gaps, reducing the shielding effect and causing electromagnetic losses in the armor. For example, air gaps may exist between insulation layers due to manufacturing processes or material properties, leading to uneven electric field distribution. Potential jumps between the semiconductor shielding layer and the insulation layer may also trigger partial discharge phenomena, thereby increasing cable losses and metal armor losses. Summary of the Invention

[0005] To address the problems existing in the prior art, this application provides a high-voltage three-core submarine cable, including an insulation system. The insulation system includes a conductor shielding layer, an insulation layer, and an insulating shielding layer. The conductivity of the conductor shielding layer gradually decreases from the inside to the outside in the radial direction of the conductive core. The conductivity of the insulating shielding layer gradually decreases from the outside to the inside in the radial direction of the conductive core, thus smoothing the interface electric field between the conductor shielding layer, the insulation layer, and the insulating shielding layer, thereby solving the technical problem of partial discharge in the insulation system.

[0006] This application provides a high-voltage three-core submarine cable, including a cable core, a water-blocking layer, an inner sheath, an armor layer, and an outer sheath. The cable core includes at least one conductive core, which includes a conductor and an insulation system disposed outside the conductor. The insulation system includes a conductor shielding layer, an insulation layer, and an insulation shielding layer. The conductivity of the conductor shielding layer gradually decreases from the inside to the outside in the radial direction of the conductive core; the conductivity of the insulation shielding layer gradually decreases from the outside to the inside in the radial direction of the conductive core.

[0007] In some embodiments, the conductor shielding layer includes a substrate and conductive fillers distributed in the substrate, wherein the filling ratio of the conductive fillers gradually decreases from the inside to the outside of the substrate material.

[0008] In some embodiments, the volume resistivity of the conductor shielding layer varies within any range of 100 Ω / m to 1000 Ω / m in the direction from the inside to the outside of the conductive core, and the difference between the ranges is at least 100 Ω / m.

[0009] In some embodiments, the insulating shielding layer includes a matrix, in which conductive fillers and inorganic particles are added. The filling ratio of the conductive fillers increases sequentially from the inside to the outside of the matrix material, and the filling ratio of the inorganic particles decreases sequentially from the inside to the outside.

[0010] In some embodiments, the conductive filler in the insulating shielding layer is attached to the fiber to form conductive fibers, and the insulating shielding layer includes multiple braided layers formed of conductive fibers, with a matrix and inorganic particles filling the pores between the braided layers.

[0011] In some embodiments, the conductive fibers in each layer of the insulating shielding layer have the same conductivity, but the braiding density of the braided layers gradually decreases from the outside to the inside.

[0012] In some embodiments, the conductive fibers in each layer of the insulating shielding layer have the same braiding density, but the conductivity of the conductive fibers in each braided layer gradually decreases from the outside to the inside.

[0013] In some embodiments, the volume resistivity of the insulating shielding layer varies within any range of 100 Ω / m to 500 Ω / m in the direction from the outside to the inside of the conductive core, and the difference between the ranges is at least 100 Ω / m.

[0014] In some embodiments, the conductivity of the conductor shielding layer on the side away from the conductor is less than the conductivity of the insulating shielding layer on the side away from the conductor.

[0015] In some embodiments, the conductive filler in the conductor shielding layer and the insulating shielding layer is at least one of conductive carbon black, graphene, carbon nanotubes, silver nanowires, or copper nanowires.

[0016] Compared with the prior art, the beneficial effects achieved by this application are as follows: In this application, by setting the conductor shielding layer to a structure in which the conductivity continuously decreases near the insulating layer, the interface between the conductor shielding layer and the insulating layer is designed to prevent charge accumulation at the interface, thereby greatly optimizing the electric field distribution between the conductor shielding layer and the insulating shielding layer. Similarly, by setting the insulating shielding layer to have a conductivity that gradually increases away from the insulating layer, the interface electric field between the insulating layer and the insulating shielding layer is optimized, and the charge at the interface of the insulating layer can be quickly drawn into the insulating shielding layer, preventing the generation of partial discharge phenomena.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This application shows a schematic diagram of the structure of a high-voltage three-core submarine cable.

[0020] Figure 2 A schematic diagram of the conductor core structure in this application is shown;

[0021] Figure 3 A schematic diagram of the insulation and shielding system in this application is shown;

[0022] Figure 4 A schematic diagram of the conductor shielding structure in the insulation shielding system of this application is shown;

[0023] Figure 5 This paper shows a schematic diagram of an insulating shield structure in the insulating shield system of this application;

[0024] Figure 6 This paper shows another structural schematic diagram of the insulation shielding in the insulation shielding system of this application;

[0025] Figure 7 A schematic diagram of one structure of the composite armored shielding layer in this application is shown;

[0026] Figure 8 Another structural schematic diagram of the composite armored shielding layer in this application is shown;

[0027] Figure 9 Another structural schematic diagram of the composite armored shielding layer in this application is shown;

[0028] Figure 10 Another structural schematic diagram of the composite armored shielding layer in this application is shown;

[0029] Figure 11 Another structural schematic diagram of the composite armored shielding layer in this application is shown;

[0030] Figure 12 Another structural schematic diagram of the composite armored shielding layer in this application is shown;

[0031] Figure 13 Another structural schematic diagram of the composite armored shielding layer in this application is shown;

[0032] Figure 14 Another structural schematic diagram of the composite armored shielding layer in this application is shown;

[0033] Figure 15 Another structural schematic diagram of the high-voltage three-core submarine cable in this application is shown.

[0034] In the diagram: 1-Conductive core, 11-Conductor, 12-Conductor shielding layer, 13-Insulation layer, 14-Insulation shielding layer, 141-Substrate, 142-First braided layer, 143-Second braided layer, 144-Third braided layer, 15-Metal sheath, 2-Filling strip, 3-Fiber optic unit, 4-Water-blocking layer, 5-Inner sheath, 6-Composite armor shielding layer, 61-Matrix, 62-Magnetic layer, 631-First layer metal wire, 632-Second layer metal wire, 633-Third layer metal wire, 64-Tension fiber, 65-Adhesive tape, 634-Fourth braided layer, 635-Fifth braided layer, 636-Sixth braided layer, 637-Conductive particle, 621-First magnetic strip, 622-Second magnetic strip, 623-Magnetic particle, 7-Outer sheath, 8-Reinforcing fiber layer, σ-Conductivity, μ-Magnetic permeability. Detailed Implementation

[0035] The term "comprising" in this application specification is synonymous with "including," "containing," or "characterized in," and is inclusive or open-ended, and does not exclude additional undescribed elements or method steps.

[0036] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0037] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0038] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] This application provides a high-voltage three-core submarine cable.

[0041] As in Example 1 of this embodiment, a high-voltage three-core submarine cable, such as Figure 1 As shown, it includes, from the inside out, a cable core, a water-blocking layer 4, an inner sheath 5, a composite armored shielding layer 6, and an outer sheath 7.

[0042] The cable core includes at least one conductive core 1, such as Figure 2-3 As shown, the conductive core 1 includes a conductor 11, an insulation system, and a metal sheath 15. The insulation system includes a conductor shielding layer 12, an insulation layer 13, and an insulation shielding layer 14. In the insulation system, the conductor shielding layer 12 and the insulation shielding layer 14 have bidirectionally gradually changing conductivity relative to the insulation layer 13. Specifically, the conductivity σ of the conductor shielding layer 12 gradually decreases from the inside to the outside in the radial direction of the conductive core 1; the conductivity σ of the insulation shielding layer 14 gradually decreases from the outside to the inside in the radial direction of the conductive core 1. That is, the conductivity gradient directions of the conductor shielding layer 12 and the insulation shielding layer 14 are opposite.

[0043] Due to minute defects in the manufacturing process or abrupt changes in the conductivity of materials, micropores or charge concentrations may occur at the interface, leading to partial discharge. Preventing partial discharge at the interface between the insulated wire and the conductor shield 12 and the insulation shield 14 is one of the core objectives in the design, manufacturing, installation, and operation and maintenance of high-voltage submarine cables. By setting the conductor shield 12 to a structure with continuously decreasing conductivity σ, the interface between the conductor shield 12 and the insulation layer 13 is designed to prevent charge accumulation at the interface, significantly optimizing the electric field distribution between the conductor shield 12 and the insulation shield 14. Similarly, setting the insulation shield 14 to have a conductivity σ that gradually increases away from the insulation layer 13 optimizes the electric field between the insulation layer 13 and the insulation shield 14, and can quickly draw the charge at the interface of the insulation layer 13 into the insulation shield 14, preventing the occurrence of partial discharge.

[0044] In this embodiment, the conductor shielding layer includes a substrate 141 and conductive fillers distributed within the substrate 141. The substrate 141 is a resin material, and the conductive filler can be at least one of conductive carbon black, graphene, carbon nanotubes, silver nanowires, or copper nanowires. The filling ratio of the conductive filler decreases sequentially from the inside to the outside of the substrate 141 material, thereby achieving a continuous decrease in conductivity σ of the conductor shielding layer 12 from the inside to the outside in the radial direction of the conductive core 1. Figure 4 As shown, the arrow indicates the direction of conductivity. The increasing direction of the conductive filler in the substrate 141 ensures a continuous change in the potential of the conductor shielding layer 12, forming a smooth electric field transition, improving the shielding effect of the conductor shielding layer, and optimizing the interface performance with the insulation layer 13. Compared with the layer-by-layer wrapping structure of semiconducting shielding strips with different potentials, the conductor shielding layer 12 of this application does not have gaps caused by wrapping, avoiding partial discharge caused by wrapping gaps. Furthermore, the conductor shielding layer 12 of this application uses the substrate 141 as a medium and adopts an extrusion process, which ensures zero-gap contact between the conductor shielding layer 12 and the conductor 11, while ensuring the roundness of the conductive core 1.

[0045] In some embodiments, the filling ratio of the conductive filler gradually changes from 40% to 20% from the inside to the outside, so that the volume resistivity of the conductor shielding layer varies from 100 Ω / m to 1000 Ω / m in any range from the inside to the outside of the conductive core, and the difference between the ranges is at least 100 Ω / m. The conductivity is inversely proportional to the volume resistivity, thereby achieving a gradual decrease in conductivity σ of the conductor shielding layer 12 from the inside to the outside of the conductive core 1 in the radial direction.

[0046] In this embodiment, the insulating shielding layer 14 includes a substrate 141, to which conductive fillers and inorganic particles (not shown in the figure) are added. The filling ratio of the conductive fillers increases sequentially from the inside to the outside of the substrate 141, while the filling ratio of the inorganic particles decreases sequentially from the inside to the outside. The conductive fillers include at least one of conductive carbon black, graphene, carbon nanotubes, silver nanowires, or copper nanowires, and the inorganic fillers include alumina, boehmite, etc.

[0047] By adding inorganic fillers in a gradual doping process, the distribution ratio of conductive fillers in the matrix 141 can be controlled synchronously. Furthermore, the addition of inorganic fillers makes the conductor shielding layer 12 have higher thermal stability and mechanical strength, further strengthening the protection of the internal insulation layer 13, conductor shielding layer 12 and conductor 11, and improving the compressive strength of the conductive core 1.

[0048] Furthermore, in some embodiments, the conductive filler in the insulating shielding layer 14 is attached to the fibers to form conductive fibers. The insulating shielding layer 14 includes multiple braided layers formed of conductive fibers, with the matrix 141 and inorganic particles filling the pores between the braided layers. The multiple braided layers formed of conductive fibers are at least two layers. The conductive fiber braided layers make it easier to control the gradient ratio of the conductive filler and also increase the tensile strength of the insulating shielding layer 14.

[0049] Furthermore, in some embodiments, the conductive fibers in each layer of the insulating shielding layer 14 have the same conductivity σ, but the braiding density of the braided layers gradually decreases from the outside to the inside. Since the conductive fibers have the same conductivity σ, the pore size of the braided layers is controlled by gradually varying the braiding density. The higher the pore density of the braided layers, the higher the filling ratio of the matrix 141 material and inorganic materials, and the lower the corresponding conductivity σ; conversely, the lower the pore density of the braided layers, the higher the filling ratio of the conductive filler, and the higher the corresponding conductivity σ.

[0050] Specifically, such as Figure 5 As shown, the insulating shielding layer 14 includes a substrate 141, inorganic particles, and multiple braided layers formed by conductive fibers. The braided layers consist of three layers: a first braided layer 142, a second braided layer 143, and a third braided layer 144, arranged sequentially near the insulating layer 13. The conductive fibers used in the first braided layer 142, the second braided layer 143, and the third braided layer 144 have the same conductivity σ. The density of the first braided layer 142 is greater than that of the second braided layer 143, and the density of the second braided layer 143 is greater than that of the third braided layer 144. By gradually decreasing the braiding density of the braided layers from the outside in, the conductivity σ of the insulating shielding layer 14 decreases as it approaches the insulating layer 13, thereby reducing the potential jump between the insulating layer 13 and the insulating shielding layer 14 and preventing partial discharge between them.

[0051] Furthermore, in some embodiments, the conductive fibers in each layer of the insulating shielding layer 14 have the same braiding density, but the conductivity σ of the conductive fibers in each braided layer gradually decreases in the direction closer to the cable core. For example... Figure 6 As shown, the insulating shielding layer 14 includes a substrate 141, inorganic particles, and multiple braided layers formed of conductive fibers. The braided layers consist of three layers: a first braided layer 142, a second braided layer 143, and a third braided layer 144, sequentially arranged near the insulating layer 13. The braiding density of the first braided layer 142, the second braided layer 143, and the third braided layer 144 is the same. The conductivity σ of the conductive fibers used in the first braided layer 142 is greater than that of the conductive fibers used in the second braided layer 143, and the conductivity σ of the conductive fibers used in the second braided layer 143 is greater than that of the conductive fibers used in the third braided layer 144.

[0052] By selecting conductive fibers with different concentrations of conductive fillers, the conductivity σ of each braided layer formed by conductive fibers can be controlled, thereby controlling the potential gradient of the insulating shielding layer 14. Simultaneously, since the braided layers have the same braid density, only different conductive fibers need to be used in different layers, reducing the complexity of the manufacturing process.

[0053] In some embodiments, the conductivity σ of the conductive fibers in each braided layer gradually decreases in the direction close to the cable core, while the braiding density of the braided layer decreases to meet the requirement of a gradual gradient in conductivity σ.

[0054] In some embodiments, the conductivity σ of the conductor shielding layer 12 on the side away from the conductor 11 is less than the conductivity σ of the insulating shielding layer 14 on the side away from the conductor 11. This ensures a continuous attenuation of the electric field from the conductor shielding layer to the metal sheath 15, rapidly introducing the outer electric field into the insulating layer 13 while preventing grounding current from the metal sheath 15 from penetrating the insulating shielding layer 14, thus reducing eddy current losses. Conductivity is inversely proportional to volume resistivity. In some embodiments, the volume resistivity of the insulating shielding layer 14 varies from 100 Ω / m to 500 Ω / m in the direction from the outside to the inside of the conductive core, with the difference between these intervals being at least 100 Ω / m.

[0055] Specifically, in some embodiments, the volume resistivity of the conductor shielding layer 12 in the cable core with a gradual change in the direction from the inside to the outside is 400 Ω / m-500 Ω / m, and the volume resistivity of the insulating shielding layer 14 in the cable core with a gradual change in the direction from the outside to the inside can be 300 Ω / m-400 Ω / m. In some embodiments, if the volume resistivity of the conductor shielding layer 12 in the cable core with a gradual change in the direction from the inside to the outside is in any range of 1000 Ω / m-600 Ω / m, then the volume resistivity of the insulating shielding layer 14 in the cable core with a gradual change in the direction from the outside to the inside can be in any range of 100 Ω / m-500 Ω / m.

[0056] The matrix 141 is a cross-linked polyethylene material.

[0057] The cable core also includes a filler strip 2 and an optical fiber unit 3. The filler strip 2 is disposed between adjacent conductive cores 1, and the optical fiber unit 3 is disposed within the filler strip 2.

[0058] A composite armored shielding layer 6 is provided between the inner sheath 5 and the outer sheath. The composite armored shielding layer 6 includes a matrix 61, and conductive and magnetic materials disposed within the matrix 61. The conductive material is disposed on the side of the composite armored shielding layer 6 closer to the cable core, and the magnetic material is disposed on the side of the composite armored shielding layer 6 farther from the cable core. The conductivity σ of the composite armored shielding layer 6 gradually decreases in the direction away from the cable core. The magnetic material is a non-conductive material, and the magnetic permeability μ of the side of the composite armored shielding layer 6 away from the cable core is greater than the magnetic permeability μ of the side closer to the cable core.

[0059] The composite armored shielding layer 6 has conductive material placed on the side closer to the cable core and magnetic material placed on the side farther away from the cable core. It not only has good tensile strength and wear resistance, but also has a good shielding effect on internal high-frequency magnetic fields and external low-frequency magnetic fields, achieving bidirectional shielding against internal induced current and external interference magnetic fields, which greatly reduces the loss of submarine cables.

[0060] In some embodiments, the magnetically conductive material is at least one of ferrite or permanent magnet, and is a coating disposed on the side away from the cable core. The coating has a certain thickness, forming a magnetically conductive layer 62. The magnetically conductive layer 62 is on the outer surface of the composite armored shielding layer 6, and not only has good electromagnetic shielding function, but also excellent corrosion resistance and wear resistance.

[0061] The conductive material is at least one of copper, aluminum, tin, nickel-based alloys and steel wire, and the magnetic material is at least one of ferrite or permanent magnet.

[0062] In some embodiments, the conductive material is formed into metal wires, and the metal wires are provided in at least two layers.

[0063] like Figure 7 As shown, the composite armored shielding layer 6 includes a matrix 61, multiple layers of metal wires disposed within the matrix 61, and a magnetically conductive layer 62 located on the outer surface of the substrate 141. Specifically, there are three layers of metal wires, arranged sequentially in the direction away from the cable core: a first layer of metal wire 631, a second layer of metal wire 632, and a third layer of metal wire 633. Each metal wire is made of a material with a different conductivity σ, wherein the conductivity σ of the first layer of metal wire 631 is greater than that of the second layer of metal wire 632, and the conductivity σ of the second layer of metal wire 632 is greater than that of the third layer of metal wire 633. This design, with the conductivity σ gradually decreasing in the direction away from the cable core, quickly introduces the induced current of the cable core into the composite armored shielding layer 6, avoiding the generation of partial discharge phenomena, greatly improving the insulation performance of the submarine cable, and enhancing the stability and safety of submarine cable operation. In this embodiment, the first layer of metal wire 631, the second layer of metal wire 632, and the third layer of metal wire 633 have the same diameter. In other embodiments, the diameters of the first layer of metal wire 631, the second layer of metal wire 632, and the third layer of metal wire 633 decrease sequentially in the direction away from the cable core.

[0064] In some embodiments, the metal wires in different layers are made of the same material, the diameter of the inner layer metal wire is larger than the diameter of the adjacent outer layer metal wire, and the outer layer metal wire is also provided with tensile-resistant fibers 64 at intervals. Figure 8 As shown, the composite armor shielding layer 6 includes a matrix 61, multiple layers of metal wires disposed within the matrix 61, and a magnetically conductive layer 62 located on the outer surface of the substrate 141. Specifically, there are two layers of metal wires, with a first layer of metal wires 631 and a second layer of metal wires 632 sequentially disposed in the direction away from the cable core. The diameter of the first layer of metal wires 631 is larger than the diameter of the second layer of metal wires 632. The second layer of metal wires 632 is also interspersed with tensile fibers 64, preferably Kevlar fibers. By setting the diameter of the metal wires, the conductivity σ of the inner and outer layers of metal wires is changed. The larger the diameter, the higher the conductivity σ. Furthermore, the placement of tensile fibers between the outer layers of metal wires not only adjusts the conductivity σ of the outer layers of metal wires but also improves the tensile strength of the armor and reduces the weight of the submarine cable.

[0065] Furthermore, adhesive tape 65 can be designed between each layer of metal wires, such as... Figure 9 As shown, the adhesive tape 65 can apply radial force to the inner metal wires to make the inner metal wires tightly arranged and prevent them from flipping and misaligning with the outer metal wires during the twisting process.

[0066] In some embodiments, the conductive material is a braided layer formed of conductive fibers, the braided layer comprising at least two layers.

[0067] Furthermore, in some embodiments, the conductivity σ of the materials of the different braided layers decreases in the direction away from the cable core in the composite armor shielding layer 6, and the braiding density of each braided layer can be the same or different. For example... Figure 10 As shown, the composite armor shielding layer 6 includes a fourth braided layer 634, a fifth braided layer 635, and a sixth braided layer 636. The conductivity σ of the fourth braided layer 634 is greater than that of the fifth braided layer 635, and the conductivity σ of the fifth braided layer 635 is greater than that of the sixth braided layer 636. In this embodiment, the braiding density of the fourth braided layer 634 and the fifth braided layer 635 is the same, both greater than that of the sixth braided layer 636. In other embodiments, the densities of the fourth braided layer 634, the fifth braided layer 635, and the sixth braided layer 636 can decrease sequentially. The potential gradient within the composite armor shielding layer 6 can be controlled simultaneously by the conductivity σ of the conductive fibers and the braiding density.

[0068] In some other embodiments, the different braided layers are made of the same material, and the braiding density of each braided layer in the composite armor shielding layer 6 gradually decreases in the direction away from the cable core. For example... Figure 11 As shown, the composite armor shielding layer includes a fourth braided layer 634 and a fifth braided layer 635. The conductive fibers used in the fourth braided layer 634 and the fifth braided layer 635 have the same conductivity σ, but the braiding density of the fourth braided layer 634 is greater than that of the fifth braided layer 635, thereby reducing the conductivity σ of the composite armor shielding layer 6 in the direction away from the cable core.

[0069] In some embodiments, the permeability μ of the composite armored shielding layer 6 gradually decreases in the direction near the cable core. Specifically, magnetically conductive material forms magnetic strips, which include at least two layers. The number of magnetic strips in the composite armored shielding layer 6 gradually decreases in the direction near the cable core, thereby causing the permeability μ of the composite armored shielding layer 6 to gradually decrease in the direction near the cable core.

[0070] In the direction near the cable core, the magnetic strips can be arranged alternately with at least one of the tensile fibers or conductive materials. For example, when the conductive material is metal wire, the magnetic strips near the cable core are arranged alternately with the metal wires away from the cable core, or the magnetic strips near the cable core are arranged alternately with the metal wires away from the cable core and the tensile fiber 64. As another example, when the conductive material is conductive particles 637, the magnetic strips near the cable core are embedded in the conductive particles 637.

[0071] like Figure 12As shown, the composite armored shielding layer 6 includes a matrix 61, a first magnetic strip, a second magnetic strip, a first layer of metal wires 631, and a second layer of metal wires 632. The number of first magnetic strips is greater than the number of second magnetic strips, and the number of first layer metal wires 631 is greater than the number of second layer metal wires 632. The second magnetic strips and second layer metal wires 632 are arranged alternately. The specific number of intervals can be selected according to the electromagnetic shielding requirements. For example, when there is a lot of external interference, the number of intervals between the second magnetic strips and second layer metal wires 632 is 1, that is, the number of second layer metal wires 632 in this layer is higher than the number of second magnetic strips. When the internal induced current requirement is strong, the number of intervals between the second layer metal wires 632 is 2 or more, so that the number of second layer metal wires 632 in this layer is higher than the number of second magnetic strips.

[0072] In some other embodiments, when the number of metal wire layers is three, the second magnetic strip of the composite armor shielding layer 6 can also be arranged alternately with the third layer of metal wire 633 and tensile fiber 64. In this embodiment, if the conductivity σ of each layer of metal wire can be the same or different, the diameter of the metal wire in the direction away from the cable core of the composite armor shielding layer 6 can also gradually decrease. Figure 13 As shown, the composite armored shielding layer 6 includes a matrix 61, and a first magnetic strip, a second magnetic strip, a first layer of metal wires 631, a second layer of metal wires 632, and a third layer of metal wires 633 encased within the matrix 61. Tensile fibers 64 are spaced apart between the second layer of metal wires 632; specifically, one tensile fiber 64 is placed every two second layer of metal wires 632. A second magnetic strip and a tensile fiber 64 are spaced apart between the third layer of metal wires 633. This arrangement simultaneously achieves a decrease in conductivity σ in the direction away from the cable core and a decrease in permeability μ in the direction closer to the cable core, maximizing the rapid introduction of induced current and induced magnetic field into the composite armored shielding layer 6, thus achieving bidirectional shielding.

[0073] In this embodiment, the materials of all layers of metal wires are the same, and the conductivity σ is reduced by decreasing the diameter and number of the composite armor shielding layer 6 in the direction away from the cable core. In other embodiments, different metal materials can be used for each layer of metal wires, and the diameter and number of each layer of metal wires can be adjusted as needed.

[0074] In some embodiments, the conductive material is conductive particles 637 formed from at least one of copper, aluminum, tin, and nickel-based alloys, and the filling ratio of conductive particles 637 in the composite armored shielding layer 6 gradually decreases in the direction away from the cable core.

[0075] In some embodiments, the magnetic material is formed into magnetic particles 623 by either ferrite or permanent magnet. The filling ratio of magnetic particles 623 in the composite armor shielding layer 6 gradually decreases in the direction close to the cable core, so that the permeability μ of the composite armor shielding layer 6 gradually decreases in the direction close to the cable core.

[0076] like Figure 14 As shown, the composite armor shielding layer 6 includes conductive particles 637 and magnetic particles 623. The filling ratio of conductive particles 637 gradually decreases in the direction away from the cable core, and the filling ratio of magnetic particles 623 gradually decreases in the direction closer to the cable core. Furthermore, tensile fibers 64 are provided at the mixing point of conductive particles 637 and magnetic material to increase the tensile strength of the composite shielding layer.

[0077] Furthermore, a reinforcing fiber layer 8 can be provided on the outside of the composite armor shielding layer 6, such as... Figure 15 As shown, this further enhances the strength of the submarine cable.

[0078] The matrix 61 shown is either epoxy resin or polyethylene.

[0079] The outer sheath 7 is made of high-density polyethylene or polyethylene.

[0080] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A high-voltage three-core submarine cable, comprising a cable core, a water-blocking layer, an inner sheath, a composite armored shielding layer, and an outer sheath, wherein the cable core includes at least one conductive core, the conductive core includes a conductor and an insulation system disposed outside the conductor, the insulation system includes a conductor shielding layer, an insulation layer, and an insulation shielding layer, characterized in that, The conductivity of the conductor shielding layer gradually decreases from the inside to the outside in the radial direction of the conductive core; the conductivity of the insulating shielding layer gradually decreases from the outside to the inside in the radial direction of the conductive core. The composite armored shielding layer includes a matrix, and a conductive material disposed within the matrix on the side closer to the cable core and a magnetic material disposed on the side farther from the cable core. The conductive material has a continuously decreasing conductivity in the direction away from the cable core, and the magnetic material has a continuously decreasing magnetic permeability in the direction closer to the cable core. The magnetic material forms magnetic strips, which include at least two layers. In the composite armored shielding layer, the number of magnetic strips gradually decreases in the direction close to the cable core. The conductive material is metal wire, and there are at least two layers of metal wire. The number of metal wires in the first layer is greater than that in the second layer. The magnetic strips on the side closer to the cable core are arranged alternately with the metal wires on the side farther away from the cable core.

2. The high-voltage three-core submarine cable according to claim 1, characterized in that, The conductor shielding layer includes a substrate and conductive fillers distributed in the substrate, wherein the filling ratio of the conductive fillers gradually decreases from the inside to the outside of the substrate material.

3. The high-voltage three-core submarine cable according to claim 2, characterized in that, The volume resistivity of the conductor shielding layer changes from 100 Ω to 100 Ω in the direction from the inside to the outside of the conductive core. / m-1000 The variation occurs within any interval of / m, where the difference between the intervals is at least 100. / m.

4. The high-voltage three-core submarine cable according to claim 1, characterized in that, The insulating shielding layer includes a matrix, in which conductive fillers and inorganic particles are added. The filling ratio of the conductive fillers increases sequentially from the inside to the outside of the matrix material, while the filling ratio of the inorganic particles decreases sequentially from the inside to the outside.

5. The high-voltage three-core submarine cable according to claim 4, characterized in that, The conductive filler in the insulating shielding layer is attached to the fiber to form conductive fiber. The insulating shielding layer includes multiple braided layers formed by conductive fiber, and the matrix and inorganic particles fill the pores of the braided layers.

6. The high-voltage three-core submarine cable according to claim 5, characterized in that, Each layer of conductive fibers in the insulating shielding layer has the same conductivity, but the braiding density of the braided layers gradually decreases from the outside to the inside.

7. The high-voltage three-core submarine cable according to claim 5, characterized in that, The conductive fibers in each layer of the insulating shielding layer have the same braiding density, but the conductivity of the conductive fibers in each braided layer gradually decreases from the outside to the inside.

8. The high-voltage three-core submarine cable according to claim 4, characterized in that, The volume resistivity of the insulating shielding layer changes from 100 to 100 in the direction from the outside to the inside of the conductive core. / m-500 The variation occurs within any interval of / m, where the difference between the intervals is at least 100. / m.

9. The high-voltage three-core submarine cable according to claim 1, characterized in that, The conductivity of the conductor shielding layer on the side furthest from the conductor is less than that of the insulating shielding layer on the side furthest from the conductor.

10. The high-voltage three-core submarine cable according to claim 1, characterized in that, The conductive filler in the conductor shielding layer and the insulating shielding layer is at least one of conductive carbon black, graphene, carbon nanotubes, silver nanowires or copper nanowires.

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