High-strength low-relaxation ultrahigh-voltage longitudinal watertight cable for smart power grid

Abstract

The invention relates to the technical field of cables, in particular to a high-strength low-relaxation ultrahigh-voltage longitudinal watertight cable for an intelligent power grid, and solves the problems that an existing ultrahigh-voltage longitudinal watertight cable is low in strength and high in stress relaxation rate. Comprising a cross-shaped high-strength protection framework mechanism, the cross-shaped high-strength protection framework mechanism comprises a cross-shaped high-hardness protection support, the four end corners of the outer surface of the cross-shaped high-hardness protection support are each provided with a fan-shaped groove, the inner side of each fan-shaped groove is provided with a plurality of wire cores, and the outer surfaces of the wire cores are fixedly sleeved with conductor shielding layers; and an insulating layer is arranged on the outer side of the plurality of conductor shielding layers in the same fan-shaped groove. By means of the net-shaped stress diffusion framework structure and the cross-shaped high-strength protection framework structure, the cable achieves three-dimensional enhancement from the inner core to the outer protection, and meanwhile the excellent low-relaxation characteristic is achieved.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to high-strength, low-relaxation, ultra-high voltage longitudinal watertight cables for smart grids. Background Technology

[0002] A cable is an electrical energy or signal transmission device, usually composed of several or several groups of conductors. Cables include power cables, control cables, compensating cables, shielded cables, high-temperature cables, computer cables, signal cables, coaxial cables, fire-resistant cables, marine cables, mining cables, aluminum alloy cables, ultra-high voltage longitudinal watertight cables, etc.

[0003] Ultra-high voltage longitudinal watertight cable is a special transmission equipment designed for extreme environments such as deep-sea exploration, marine energy development and smart grids. Its core lies in achieving excellent high watertightness through precise internal structural design.

[0004] However, existing ultra-high voltage longitudinal watertight cables have low strength, and under long-term high-load operation, their internal conductors and sheaths may gradually undergo plastic deformation, resulting in overall cable elongation and cross-sectional shrinkage. This irreversible deformation may change the electrical parameters of the cable, and may even cause local electric field distortion and increase the risk of insulation breakdown. The stress relaxation rate of this cable is high. Therefore, it does not meet the current requirements. In response, we propose a high-strength, low-relaxation ultra-high voltage longitudinal watertight cable for smart grids. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength, low-relaxation ultra-high voltage longitudinal watertight cable for smart grids, in order to solve the problems mentioned in the background art, such as the low strength of existing ultra-high voltage longitudinal watertight cables, and the possibility that the conductors and sheaths inside the cables may gradually undergo plastic deformation under long-term high-load operation, resulting in overall cable elongation and cross-sectional shrinkage. This irreversible deformation may change the electrical parameters of the cable, and may even cause local electric field distortion and increase the risk of insulation breakdown. The cable also has a high stress relaxation rate.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids, comprising a cross-shaped high-strength protective frame mechanism, wherein the cross-shaped high-strength protective frame mechanism comprises a cross-shaped high-hardness protective bracket, each of the four corners of the outer surface of the cross-shaped high-hardness protective bracket is provided with a sector-shaped groove, each sector-shaped groove is provided with multiple wire cores on its inner side, the outer surface of the wire cores is fixedly sleeved with a conductor shielding layer, an insulating layer is provided on the outer side of the multiple conductor shielding layers located inside the same sector-shaped groove, and an arc-shaped protective bracket fixed inside the sector-shaped groove is provided on the outer side of the insulating layer;

[0007] The outer side of the cross-shaped high-strength protective frame structure is provided with a mesh stress diffusion frame structure. The mesh stress diffusion frame structure has multiple stress diffusion rings. The outer surface of the stress diffusion ring is provided with a strip groove, and the inner wall of each strip groove is provided with a cylindrical slot.

[0008] Multiple first fiber ropes are fixed to the front and rear ends of the stress diffusion ring. The ends of the first fiber ropes are connected to first connecting rods. The first connecting rod located in front of the stress diffusion ring is inserted into the strip groove on the outer surface of the first stress diffusion ring in front of the stress diffusion ring. The first connecting rod located behind the stress diffusion ring is inserted into the strip groove on the outer surface of the first stress diffusion ring behind the stress diffusion ring.

[0009] A second fiber rope is fixed to the outer surface of the stress diffusion ring on one side of the first fiber rope. A second connecting rod is connected to the end of the second fiber rope. The second connecting rod located in front of the stress diffusion ring is inserted into the strip groove on the outer surface of the second stress diffusion ring in front of this stress diffusion ring. The second connecting rod located behind the stress diffusion ring is inserted into the strip groove on the outer surface of the second stress diffusion ring behind this stress diffusion ring.

[0010] A third fiber rope is fixed to the outer surface of the stress diffusion ring on one side of the second fiber rope. A third connecting rod is connected to the end of the third fiber rope. The third connecting rod located in front of the stress diffusion ring is inserted into the strip groove on the outer surface of the third stress diffusion ring in front of this stress diffusion ring. The third connecting rod located behind the stress diffusion ring is inserted into the strip groove on the outer surface of the third stress diffusion ring behind this stress diffusion ring.

[0011] Preferably, the front and rear ends of the cross-shaped high-hardness protective bracket are each provided with a circular groove, and an insulating layer for filling is provided between two opposite circular grooves.

[0012] Preferably, the front and rear ends of the arc-shaped protective bracket are fixed with multiple connecting rings, and the outer surface of the connecting ring is fitted with a connecting pull ring. A connecting metal rope is connected between two opposite connecting pull rings, and the connecting metal rope passes laterally through the insulating layer used to fill the partition.

[0013] Preferably, an armored programming layer is fixed to the outside of the plurality of insulating layers used for filling the interlayer, and the surface of the armored programming layer facing the cross-shaped high-hardness protective bracket is fixed to the cross-shaped high-hardness protective bracket.

[0014] Preferably, the mesh stress diffusion skeleton structure further includes multiple fixed supports, the number of which is four times that of the stress diffusion rings. The multiple fixed supports are respectively fixed to the four end corners of the inner wall of the multiple stress diffusion rings, and the faces of the fixed supports facing the cross-shaped high-strength protective skeleton structure are fixed to the cross-shaped high-strength protective skeleton structure.

[0015] Preferably, an XLPE insulating layer for gap filling is fixed to the outer side of the plurality of stress diffusion rings, and a binding and fixing layer is provided on the outer side of the XLPE insulating layer for gap filling. An arc-shaped pressing block is fixed at the position corresponding to the strip groove on the inner wall of the binding and fixing layer, and the arc-shaped pressing block is attached to the first connecting rod and the stress diffusion ring by penetrating the XLPE insulating layer for gap filling.

[0016] Preferably, a push rod is movably inserted into the outer surface of the first, second, and third connecting rods facing the arc-shaped pressing block. Both sides of the outer surface of the bottom end of the push rod are inclined surfaces. An L-shaped plug fixing block, which is movably inserted into the first connecting rod, is connected to one side of the inclined surface. Multiple conical plugs are fixed to the L-shaped plug fixing block facing the inner wall of the cylindrical slot.

[0017] Preferably, the inner wall of the cylindrical slot is provided with a rubber sleeve at a position corresponding to the conical plug, and the conical plug is inserted into the inside of the rubber sleeve.

[0018] Preferably, a water-blocking buffer layer is fixed to the outside of the mesh stress diffusion skeleton structure, a copper wire shielding layer is fixed to the outside of the water-blocking buffer layer, a corrugated aluminum sheath is fixed to the outside of the copper wire shielding layer, and an asphalt anti-corrosion layer is fixed to the outside of the corrugated aluminum sheath.

[0019] Preferably, a PE sheath is fixed to the outside of the asphalt anticorrosion layer, and the outer surface of the PE sheath is coated with an electroplating coating.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention utilizes multiple cross-shaped high-hardness protective supports within a cross-shaped high-strength protective frame mechanism. When the cable is subjected to external pressure such as deep-sea high pressure, rock impact, or lateral pressure during installation, this metal arc-shaped support acts like a skeleton to support the cable's outline, preventing the outer sheath from collapsing inward and protecting the wire core inside the fan-shaped groove on the outer surface of the cross-shaped high-hardness protective support from being flattened or cut. Through the physical structure in the above technical solution, it can actively resist external mechanical damage, reduce cable breakage, water ingress, and other faults caused by external forces, lower the maintenance frequency and replacement cost of deep-sea cables, and thus improve the overall strength of the cable.

[0022] 2. This invention utilizes a mesh-like stress diffusion framework structure where each stress diffusion ring is connected to multiple stress diffusion rings located before and after it. Through this connection structure, when the cable is subjected to tensile force at a certain point, the force is rapidly transmitted and dispersed to other connected stress diffusion rings via the stress diffusion ring closest to that point. Subsequently, the force is further transmitted to adjacent stress diffusion rings in a relay manner through the stress diffusion rings connected to other stress diffusion rings, thus forming a mesh-like stress diffusion structure. This transforms concentrated local tensile force into a distributed load shared by multiple stress diffusion rings. This technical solution not only enhances the overall tensile strength and impact resistance of the cable through a multi-ring sharing mechanism, preventing breakage or sheath damage due to excessive local stress, but also, through the synergistic effect of the stable framework formed by multiple stress diffusion rings, limits the plastic deformation of the cable under long-term stress, giving it superior low-relaxation performance and ensuring structural stability during long-term operation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 This is a top view of the overall structure of the invention;

[0025] Figure 3 For the present invention Figure 2 Enlarged view of the structure at point A in the middle;

[0026] Figure 4 This is a front view of the structure of the present invention without the mesh stress diffusion skeleton structure;

[0027] Figure 5 For the present invention Figure 4 Enlarged view of the structure at point B;

[0028] Figure 6 This is a schematic diagram of the connection structure between multiple stress diffusion rings in the mesh stress diffusion skeleton structure of the present invention.

[0029] In the diagram: 1. Cross-shaped high-hardness protective bracket; 2. Mesh stress diffusion skeleton structure; 201. Stress diffusion ring; 202. Fixing bracket; 203. Strip groove; 204. Cylindrical slot; 205. First fiber rope; 206. Second fiber rope; 207. Third fiber rope; 208. First connecting rod; 209. Push rod; 210. Inclined surface; 211. L-shaped rod fixing block; 212. Conical plug; 213. Rubber sleeve; 214. XLPE insulation layer for gap filling; 215. Binding and fixing layer; 21 6. Arc-shaped pressing block; 217. Second connecting rod; 218. Third connecting rod; 3. Fan-shaped groove; 4. Wire core; 5. Conductor shielding layer; 6. Insulation layer; 7. Arc-shaped protective bracket; 8. Circular groove; 9. Insulation layer for interlayer filling; 10. Armored programming layer; 11. Connecting ring; 12. Connecting pull ring; 13. Connecting metal rope; 14. Water-blocking buffer layer; 15. Copper wire shielding layer; 16. Corrugated aluminum sheath; 17. Asphalt anti-corrosion layer; 18. PE sheath; 19. Electroplating layer; 20. Cross-shaped high-strength protective frame mechanism. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] Please see Figures 1 to 6 An embodiment of the present invention provides a high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids, comprising a cross-shaped high-strength protective skeleton mechanism 20. The cross-shaped high-strength protective skeleton mechanism 20 includes a cross-shaped high-hardness protective bracket 1. Each of the four corners of the outer surface of the cross-shaped high-hardness protective bracket 1 is provided with a fan-shaped groove 3. Multiple wire cores 4 are provided inside each fan-shaped groove 3. A conductor shielding layer 5 is fixedly sleeved on the outer surface of the wire core 4. An insulation layer 6 is provided on the outer side of the multiple conductor shielding layers 5 located inside the same fan-shaped groove 3. An arc-shaped protective bracket 7 fixed inside the fan-shaped groove 3 is provided on the outer side of the insulation layer 6. Through the multiple cross-shaped high-hardness protective brackets 1 in the cross-shaped high-strength protective skeleton mechanism 20, when the cable is subjected to external pressure such as deep-sea high pressure, rock impact, or lateral pressure during installation, this metal arc-shaped bracket can support the outline of the cable like a skeleton, preventing the outer sheath from collapsing inward and protecting the wire cores 4 located inside the fan-shaped grooves 3 on the outer surface of the cross-shaped high-hardness protective bracket 1 from being flattened or cut.

[0032] The physical structure of the above technical solution can actively resist external mechanical damage, reduce cable breakage and water ingress caused by external forces, reduce the maintenance frequency and replacement cost of deep-sea cables, and thus improve the overall strength of the cable.

[0033] The front and rear ends of the cross-shaped high-hardness protective bracket 1 are provided with a circular groove 8, and an insulating layer 9 for filling is provided between two opposite circular grooves 8. The insulating layer 9 for filling between two adjacent cross-shaped high-hardness protective brackets 1 can fill the gap between multiple cross-shaped high-hardness protective brackets 1, thereby avoiding the occurrence of gaps in the cable outlet and ensuring the overall strength of the cable.

[0034] Multiple connecting rings 11 are fixed to the front and rear ends of the arc-shaped protective bracket 7. A connecting pull ring 12 is sleeved on the outer surface of the connecting ring 11. A connecting metal rope 13 is connected between two opposite connecting pull rings 12, and the connecting metal rope 13 passes laterally through the insulating layer 9 for the partition filling. An armored programming layer 10 is fixed to the outside of the multiple insulating layers 9 for the partition filling, and the armored programming layer 10 is fixed to the cross-shaped high-hardness protective bracket 1 with the face of the cross-shaped high-hardness protective bracket 1. Through the connecting rings 11, connecting pull rings 12 and connecting metal rope 13, multiple cross-shaped high-hardness protective brackets 1 can be connected in series to form a rigid truss that runs through the entire length of the cable. The rigid truss in the above technical solution not only enhances the axial tensile strength of the cable, but also limits the lateral deformation of the cable under lateral pressure, so that the cable can maintain a stable circular profile during installation, laying and long-term operation, avoid the degradation of electrical performance due to structural deformation, and ensure the reliability of ultra-high voltage power or signal transmission.

[0035] The outer side of the cross-shaped high-strength protective frame structure 20 is provided with a mesh stress diffusion frame structure 2. The mesh stress diffusion frame structure 2 has multiple stress diffusion rings 201. The outer surface of the stress diffusion ring 201 is provided with a strip groove 203. The inner wall of each strip groove 203 is provided with a cylindrical slot 204.

[0036] Multiple first fiber ropes 205 are fixed to the front and rear ends of the stress diffusion ring 201. The ends of the first fiber ropes 205 are connected to first connecting rods 208. The first connecting rods 208 located in front of the stress diffusion ring 201 are inserted into the strip groove 203 on the outer surface of the first stress diffusion ring 201 in front of this stress diffusion ring 201. The first connecting rods 208 located behind the stress diffusion ring 201 are inserted into the strip groove 203 on the outer surface of the first stress diffusion ring 201 behind this stress diffusion ring 201.

[0037] A second fiber rope 206 is fixed to the outer surface of the stress diffusion ring 201 on one side of the first fiber rope 205. The end of the second fiber rope 206 is connected to a second connecting rod 217. The second connecting rod 217 located in front of the stress diffusion ring 201 is inserted into the strip groove 203 on the outer surface of the second stress diffusion ring 201 located in front of this stress diffusion ring 201. The second connecting rod 217 located behind the stress diffusion ring 201 is inserted into the strip groove 203 on the outer surface of the second stress diffusion ring 201 located behind this stress diffusion ring 201.

[0038] A third fiber rope 207 is fixed to the outer surface of the stress diffusion ring 201 on one side of the second fiber rope 206. A third connecting rod 218 is connected to the end of the third fiber rope 207. The third connecting rod 218 located in front of the stress diffusion ring 201 is inserted into the strip groove 203 on the outer surface of the third stress diffusion ring 201 located in front of this stress diffusion ring 201. The third connecting rod 218 located behind the stress diffusion ring 201 is inserted into the strip groove 203 on the outer surface of the third stress diffusion ring 201 located behind this stress diffusion ring 201. The mesh stress diffusion skeleton structure 2 also includes multiple fixing brackets 202, four times the number of stress diffusion rings 201. The multiple fixing brackets 202 are respectively fixed to the four corners of the inner wall of the multiple stress diffusion rings 201, and the faces of the fixing brackets 202 facing the cross-shaped high-strength protective skeleton mechanism 20 are fixed to the cross-shaped high-strength protective skeleton mechanism 20. The fixing brackets 202 can connect the multiple stress diffusion rings 201 to multiple... The cross-shaped high-hardness protective brackets 1 are fixedly connected. Through this connection structure, when the cable is subjected to tensile force at a certain point, the force will be transmitted to the stress diffusion ring 201 through the cross-shaped high-hardness protective brackets 1 and the fixed bracket 202. When the stress diffusion ring 201 receives this force, it will be transmitted to multiple stress diffusion rings 201 located in front of and behind it through the first fiber rope 205, the second fiber rope 206, the third fiber rope 207 fixed to its front and rear ends, and the first connecting rod 208, the second connecting rod 217, and the third connecting rod 218 respectively fixed to the outer surface of the first fiber rope 205, the second fiber rope 206, and the third fiber rope 207. Subsequently, the force is further transmitted to the adjacent stress diffusion rings 201 in a relay manner through the stress diffusion rings 201 connected to other stress diffusion rings 201, thereby forming a mesh stress diffusion structure, thereby converting the concentrated local tensile force into a distributed load jointly borne by multiple stress diffusion rings 201.

[0039] The above technical solution not only enhances the overall tensile strength and impact resistance of the cable through a multi-ring stress-sharing mechanism to prevent breakage or sheath damage caused by excessive local stress, but also limits the plastic deformation of the cable under long-term stress through the synergistic effect of the stable skeleton composed of multiple stress diffusion rings 201, giving it excellent low relaxation performance and ensuring that the cable maintains structural stability during long-term operation.

[0040] A gap-filling XLPE insulating layer 214 is fixed to the outer side of multiple stress diffusion rings 201. A binding and fixing layer 215 is provided on the outer side of the gap-filling XLPE insulating layer 214. An arc-shaped pressing block 216 is fixed at the position corresponding to the strip groove 203 on the inner wall of the binding and fixing layer 215. The arc-shaped pressing block 216 is attached to the first connecting rod 208 and the stress diffusion ring 201 by penetrating the gap-filling XLPE insulating layer 214. The gap-filling XLPE insulating layer 214 located on the outer side of multiple stress diffusion rings 201 can fill the gap between the stress diffusion ring 201 and the binding and fixing layer 215.

[0041] Push rods 209 are movably inserted into the outer surfaces of the first connecting rod 208, the second connecting rod 217, and the third connecting rod 218 facing the arc-shaped pressing block 216. Both sides of the outer surface of the bottom end of the push rod 209 are inclined surfaces 210. One side of the inclined surface 210 is connected to an L-shaped rod fixing block 211, which is movably inserted into the first connecting rod 208. Multiple conical plugs 212 are fixed to the L-shaped rod fixing block 211 facing the inner wall of the cylindrical slot 204. A rubber sleeve 213 is provided on the inner wall of the cylindrical slot 204 at a position corresponding to the conical plugs 212, and the conical plugs 212 are inserted into the rubber sleeve 213. A binding and fixing layer 215 is laid on the outer surface of the multiple stress diffusion rings 201. The arc-shaped pressing block 216 fixed to the inner wall of the binding and fixing layer 215 will contact the outer surface of the movably inserted first connecting rod 208. The push rod 209 is pushed inward. As the push rod 209 moves, the inclined surface 210 on the outer surface of the push rod 209 will contact the L-shaped plug fixing block 211 and gradually push the L-shaped plug fixing block 211 outward. When the L-shaped plug fixing block 211 is gradually pushed outward, the conical plug 212 fixed on the outer surface of the L-shaped plug fixing block 211 will be inserted into the rubber sleeve 213 on the inner wall of the cylindrical slot 204, thereby fixing the first connecting plug 208, the second connecting plug 217 and the third connecting plug 218 inside the cylindrical slot 204. At the same time, through the contact of the arc-shaped pressing block 216, the first connecting plug 208, the second connecting plug 217 and the third connecting plug 218 can be double fixed inside the cylindrical slot 204 and on the outer surface of the stress diffusion ring 201.

[0042] By applying double fixation to the outer surface of the first connecting rod 208 in the above technical solution, a solid mechanical locking defense line can be formed when the cable is subjected to severe axial tension or external mechanical impact. This prevents the internal connectors from coming off, loosening, or separating due to excessive force. At the same time, this structure ensures that the internal functional units of the cable can maintain a stable relative position under harsh working conditions such as vertical laying in deep sea or long-distance traction, maintaining the continuity and stability of signal and power transmission. This enhances the disaster resistance and long-term reliability of the entire cable system under complex dynamic load environments.

[0043] A water-blocking buffer layer 14 is fixed to the outside of the mesh stress diffusion skeleton structure 2. A copper wire shielding layer 15 is fixed to the outside of the water-blocking buffer layer 14. A corrugated aluminum sheath 16 is fixed to the outside of the copper wire shielding layer 15. An asphalt anti-corrosion layer 17 is fixed to the outside of the corrugated aluminum sheath 16. A PE sheath 18 is fixed to the outside of the asphalt anti-corrosion layer 17. An electroplating coating 19 is applied to the outer surface of the PE sheath 18. Through the above technical solution, a multi-layer composite protection system from the inside to the outside is constructed, thereby ensuring the basic performance of the ultra-high voltage longitudinal watertight cable as a whole, enabling it to have all-weather protection capabilities to adapt to complex scenarios such as deep sea and underground pipe corridors.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids, comprising a cross-shaped high-strength protective frame structure (20), characterized in that: The cross-shaped high-strength protective frame mechanism (20) includes a cross-shaped high-hardness protective bracket (1). Each of the four corners of the outer surface of the cross-shaped high-hardness protective bracket (1) is provided with a fan-shaped groove (3). Each fan-shaped groove (3) is provided with multiple wire cores (4) on its inner side. The outer surface of the wire cores (4) is fixedly covered with a conductor shielding layer (5). An insulating layer (6) is provided on the outer side of the multiple conductor shielding layers (5) located inside the same fan-shaped groove (3). An arc-shaped protective bracket (7) fixed inside the fan-shaped groove (3) is provided on the outer side of the insulating layer (6). The outer side of the cross-shaped high-strength protective frame structure (20) is provided with a mesh stress diffusion frame structure (2). The mesh stress diffusion frame structure (2) has multiple stress diffusion rings (201). The outer surface of the stress diffusion ring (201) is provided with a strip groove (203). The inner wall of each strip groove (203) is provided with a cylindrical slot (204). Multiple first fiber ropes (205) are fixed to the front and rear ends of the stress diffusion ring (201). The ends of the first fiber ropes (205) are connected to first connecting rods (208). The first connecting rod (208) located in front of the stress diffusion ring (201) is inserted into the strip groove (203) on the outer surface of the first stress diffusion ring (201) in front of the stress diffusion ring (201). The first connecting rod (208) located behind the stress diffusion ring (201) is inserted into the strip groove (203) on the outer surface of the first stress diffusion ring (201) behind the stress diffusion ring (201). A second fiber rope (206) is fixed to the outer surface of the stress diffusion ring (201) on one side of the first fiber rope (205). The end of the second fiber rope (206) is connected to a second connecting rod (217). The second connecting rod (217) located in front of the stress diffusion ring (201) is inserted into the strip groove (203) on the outer surface of the second stress diffusion ring (201) located in front of this stress diffusion ring (201). The second connecting rod (217) located behind the stress diffusion ring (201) is inserted into the strip groove (203) on the outer surface of the second stress diffusion ring (201) located behind this stress diffusion ring (201). A third fiber rope (207) is fixed to the outer surface of the stress diffusion ring (201) on one side of the second fiber rope (206). The end of the third fiber rope (207) is connected to a third connecting rod (218). The third connecting rod (218) located in front of the stress diffusion ring (201) is inserted into the strip groove (203) on the outer surface of the third stress diffusion ring (201) in front of this stress diffusion ring (201). The third connecting rod (218) located behind the stress diffusion ring (201) is inserted into the strip groove (203) on the outer surface of the third stress diffusion ring (201) behind this stress diffusion ring (201).

2. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 1, characterized in that: The front and rear ends of the cross-shaped high-hardness protective bracket (1) are provided with a circular groove (8), and an insulating layer (9) for filling is provided between two opposite circular grooves (8).

3. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 2, characterized in that: The front and rear ends of the arc-shaped protective bracket (7) are fixed with multiple connecting rings (11). The outer surface of the connecting ring (11) is fitted with a connecting pull ring (12). A connecting metal rope (13) is connected between two opposite connecting pull rings (12), and the connecting metal rope (13) passes through the insulating layer (9) of the partition filling laterally.

4. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 3, characterized in that: An armored programming layer (10) is fixed to the outside of the plurality of insulating layers (9) used for filling the partitions, and the surface of the armored programming layer (10) facing the cross-shaped high-hardness protective bracket (1) is fixed to the cross-shaped high-hardness protective bracket (1).

5. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 1, characterized in that: The mesh stress diffusion skeleton structure (2) also includes a plurality of fixed supports (202) whose number is four times that of the stress diffusion rings (201). The plurality of fixed supports (202) are respectively fixed to the four end corners of the inner wall of the plurality of stress diffusion rings (201), and the face of the fixed support (202) facing the cross-shaped high-strength protective skeleton mechanism (20) is fixed to the cross-shaped high-strength protective skeleton mechanism (20).

6. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 5, characterized in that: A gap-filling XLPE insulating layer (214) is fixed to the outside of the plurality of stress diffusion rings (201). A binding and fixing layer (215) is provided on the outside of the gap-filling XLPE insulating layer (214). An arc-shaped pressing block (216) is fixed at the position corresponding to the strip groove (203) on the inner wall of the binding and fixing layer (215). The arc-shaped pressing block (216) is attached to the first connecting rod (208) and the stress diffusion ring (201) by penetrating the gap-filling XLPE insulating layer (214).

7. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 6, characterized in that: Push rods (209) are movably inserted into the outer surfaces of the first connecting rod (208), the second connecting rod (217), and the third connecting rod (218) facing the arc-shaped pressing block (216). Both sides of the outer surface of the bottom end of the push rod (209) are inclined surfaces (210). One side of the outer surface of the inclined surface (210) is connected to an L-shaped rod fixing block (211) that is movably inserted into the first connecting rod (208). Multiple conical plugs (212) are fixed on the surface of the L-shaped rod fixing block (211) facing the inner wall of the cylindrical slot (204).

8. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 7, characterized in that: The inner wall of the cylindrical slot (204) is provided with a rubber sleeve (213) at the position corresponding to the conical plug (212), and the conical plug (212) is inserted into the inside of the rubber sleeve (213).

9. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 1, characterized in that: The outer side of the mesh stress diffusion skeleton structure (2) is fixed with a water-blocking buffer layer (14), the outer side of the water-blocking buffer layer (14) is fixed with a copper wire shielding layer (15), the outer side of the copper wire shielding layer (15) is fixed with a corrugated aluminum sheath (16), and the outer side of the corrugated aluminum sheath (16) is fixed with an asphalt anti-corrosion layer (17).

10. The high-strength, low-relaxation, ultra-high voltage longitudinal watertight cable for smart grids according to claim 9, characterized in that: The outer side of the asphalt anticorrosion layer (17) is fixed with a PE sheath (18), and the outer surface of the PE sheath (18) is coated with an electroplating coating (19).

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