A special aluminum alloy sheathed environmentally friendly ultra-high voltage cable

Abstract

The present invention belongs to the field of cables, and proposes a special aluminum alloy sheathed environmentally friendly ultra-high voltage cable, comprising a plurality of cable cores, the exterior of which is provided with an insulating layer, an outer semi-conductive layer, a metal shielding layer, an aluminum alloy sheath and an outer sheath, wherein the plurality of cable cores include a polygonal cable core and a curved cable core, the arc surface section of the curved cable core is provided with an outer shaping buffer, the outer side of the outer shaping buffer is provided with a first aluminum sheath, the outer side of the first aluminum sheath is provided with a second aluminum sheath, the joints of the first aluminum sheath and the joints of the second aluminum sheath are both welded to form a welding busbar, the second aluminum sheath is arranged on the inner side of the insulating layer, an extruded inner sheath is arranged between the metal shielding layer and the aluminum alloy sheath, the extruded inner sheath is made of a montmorillonite-modified polyethylene nanocomposite material, and the outer sheath is made of a low-smoke halogen-free flame-retardant polyolefin material. The present invention has reasonable design, good waterproofness, insulation, electrical breakdown resistance and flame retardancy.

Description

Technical Field

[0001] The invention belongs to the field of cables, and in particular relates to a special aluminum alloy sheathed environment-friendly ultra-high voltage cable. Background Art

[0002] Wires and cables are essential basic products in the construction of power infrastructure, new smart grids, and new energy industries. Ultra-high voltage cables are a type of power cables, which are used to transmit power between 275kv and 800kv, and are mostly used in power transmission and distribution. The thickness of the insulation layer of ultra-high voltage cables is much greater than that of ordinary wires and cables, in order to prevent high voltage breakdown, and preventing high voltage breakdown has always been one of the main development directions of ultra-high voltage cables.

[0003] At present, regarding the conductor part of the ultra-high voltage cable, some adopt a fan-shaped distribution, while others adopt a circular stranded distribution. The former, such as the existing patent CN202122766944.8, discloses a smooth special aluminum alloy sheathed energy-saving and environmentally friendly ultra-high voltage cable and CN206040294U discloses a physical termite-proof ultra-high voltage cable. The latter, such as the existing patent CN202120931948.4, discloses an aluminum core nitrile insulated ultra-high voltage cable and CN202121861188.0 discloses a highly protective ultra-high voltage cable. Among them, the insulation of the former cable core with fan-shaped distribution is weaker than that of the latter cable core with insulation design for the stranded cable cores. However, the physical position stability and compressive resistance of the latter cable core inside the cable are poor, and it is easy to have internal deformation and local fatigue during long-term service, affecting the actual service life of the ultra-high voltage cable; secondly, the process characteristics of the wrapping structure used in the existing ultra-high voltage cable will affect the smoothness of the surface of the cable insulation layer, and the uneven surface is one of the causes of water tree problems inside the insulation layer, thereby affecting the electrical breakdown resistance of the insulation layer material, and then affecting the utilization rate of the ultra-high voltage cable and the cost of the power system. Summary of the invention

[0004] In view of the technical problems existing in the above-mentioned ultra-high voltage cables, the present invention proposes a special aluminum alloy sheathed environment-friendly ultra-high voltage cable with reasonable design, good waterproofness, insulation, electrical breakdown resistance and flame retardancy.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: the present invention provides a special aluminum alloy sheathed environmentally friendly ultra-high voltage cable, comprising a plurality of cable cores, the outside of which is provided with an insulating layer, an outer semi-conductive layer, a metal shielding layer, an aluminum alloy sheath and an outer sheath, the plurality of cable cores comprising a polygonal cable core and a plurality of curved cable cores corresponding one-to-one to the side surfaces of the polygonal cable cores, the curved cable core comprising a straight surface segment corresponding to the side surfaces of the polygonal cable core, both sides of the straight surface segment being inclined surface segments, arc surface segments being arranged between the straight surface segments, the straight surface segments, the inclined surface segments and the arc surface segments being used for extrusion wrapping of a plurality of lateral conductors, the inclined surface segments of adjacent curved cable cores being extruded and contacted with each other and a groove being formed at the junction of the extruded contact surfaces, and the outside of the arc surface segment being provided with an external shaping buffer The external shaped buffer is made of an aluminum alloy sheet to form a double-layer structure and includes an inner aluminum layer and an outer aluminum layer. The inner aluminum layer is wrapped and matched with the arc surface segment. The two sides of the inner aluminum layer are stamped to form a pair of C-shaped segments. The C-shaped segments on both sides of the same aluminum alloy sheet each lead out an outer aluminum layer and overlap each other on the surface of the inner aluminum layer. A first aluminum sheath is arranged on the outside of the external shaped buffer, and a second aluminum sheath is arranged on the outside of the first aluminum sheath. The seam of the first aluminum sheath and the seam position of the second aluminum sheath are both welded to form a welding busbar belt. The second aluminum sheath is arranged on the inner side of the insulating layer. An extruded inner sheath is arranged between the metal shielding layer and the aluminum alloy sheath. The extruded inner sheath is made of montmorillonite-modified polyethylene nanocomposite material, and the outer sheath is made of low-smoke halogen-free flame-retardant polyolefin material.

[0006] Preferably, the polygonal cable core comprises a plurality of central conductors which are gathered into a circular cross-section, an inner insulating layer is arranged outside all the central conductors, the inner insulating layer is an inner circle and outer edge structure, the outer side of the inner insulating layer is a regular dodecagon, an outer insulating layer is arranged outside the inner insulating layer, and the inner and outer sides of the outer insulating layer are a regular dodecagon and a regular hexagon, respectively.

[0007] Preferably, the regular hexagonal side of the outer insulating layer corresponds to the six side surfaces of the regular dodecagon of the inner insulating layer, the other six side surfaces of the regular dodecagon correspond to the side corners of the outer insulating layer, and an internal shaping buffer is provided inside the side corners of the outer insulating layer.

[0008] Preferably, the cross-section of the inner shaped buffer is Ω-shaped, and the inner shaped buffer includes an arched section, the arched side of the arched section is opposite to the side edge of the outer insulating layer, and the arched section is provided with planar shaped sections on both sides of the inner insulating layer for extrusion contact with the inner insulating layer.

[0009] Preferably, a plurality of curved buffer grooves spaced apart along the length direction of the inner shaped buffer are arranged on the outer side surface of the inner shaped buffer.

[0010] Preferably, a tensile rope is provided inside the C-shaped segment.

[0011] Preferably, the welding busbar strips of the first aluminum sheath and the welding busbar strips of the second aluminum sheath are distributed alternately.

[0012] Preferably, the outer surface of the second aluminum sheath is provided with a screen printing layer, and the screen printing layer is coated with a mixed coating of graphite and paraffin.

[0013] Compared with the prior art, the advantages and positive effects of the present invention are:

[0014] 1. A special aluminum alloy sheathed environmentally friendly ultra-high voltage cable provided by the present invention adopts a polygonal cable core and a curved cable core design, which can improve the stability of the physical position of all cable cores inside the cable and improve the compressive performance of the cable on the one hand, and cooperate with an external shaping buffer, a first aluminum sheath and a second aluminum sheath to ensure the smoothness of the structure inside the insulating layer, which is beneficial to suppressing the development of water trees inside the insulating layer. In addition, each cable has independent insulation protection, which can effectively improve the overall insulation and electrical breakdown resistance of the cable; the use of extruded inner and outer sheaths can improve the flame retardancy, waterproofness and environmental protection of the cable, which is beneficial to improving the comprehensive utilization rate of the cable and is suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A cross-sectional view of a special aluminum alloy sheathed environmentally friendly ultra-high voltage cable provided in an embodiment;

[0017] Figure 2 A schematic diagram of the folding of the external shaped buffer provided in the embodiment;

[0018] Figure 3 A front view of an external shaped buffer provided in an embodiment;

[0019] Figure 4 A partial top view of an internally shaped buffer provided in an embodiment;

[0020] In the above figures, 1, cable core; 11, polygonal cable core; 111, central conductor; 112, inner insulation layer; 113, outer insulation layer; 114, inner shaped buffer; 1141, arched section; 1142, plane shaped section; 1143, curved buffer groove; 12, curved cable core; 121, straight section; 122, inclined section; 123, arc section; 124, lateral conductor; 13, groove; 2, first aluminum sheath; 21, welded busbar tape; 3, second aluminum sheath; 4, insulation layer; 5, outer semi-conductive layer; 6, metal shielding layer; 7, extruded inner sheath; 8, aluminum alloy sheath; 9, outer sheath; 10, outer shaped buffer; 101, inner aluminum layer; 102, outer aluminum layer; 103, C-shaped section; 104, tensile rope. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear below, they only indicate that the upper, lower, left and right directions are consistent with the accompanying drawings themselves, and do not limit the structure.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0023] Examples, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the present invention provides a special aluminum alloy sheathed environmentally friendly ultra-high voltage cable, comprising a plurality of cable cores 1, and the exterior of the plurality of cable cores 1 is provided with an insulating layer 4, an outer semi-conductive layer 5, a metal shielding layer 6, an aluminum alloy sheath 8 and an outer sheath 9. Among them, the insulating layer 4, the outer semi-conductive layer 5 and the metal shielding layer 6 can make the cable have basic insulation and shielding properties, the aluminum alloy sheath 8 as an armor layer can improve the compression resistance, tension resistance and insect bite resistance of the cable, and the outer sheath 9 plays the role of external protection, which can ensure that the cable has basic wear resistance, flame retardancy, heat resistance and UV resistance. On this basis, the present invention proposes beneficial improvements to the distribution form of the plurality of cable cores 1 and the structure that affects the smoothness of the inner wall of the insulating layer 4.

[0024] Specifically, the plurality of cable cores 1 provided by the present invention include a polygonal cable core 11 and a plurality of curved cable cores 12 corresponding one to one with the side surfaces of the polygonal cable core 11, the curved cable core 12 including a straight segment 121 corresponding to the side surfaces of the polygonal cable core 11, the straight segment 121 having inclined segments 122 on both sides, and an arc segment 123 arranged between the straight segments 121, the straight segment 121, the inclined segment 122 and the arc segment 123 being used for extrusion wrapping of a plurality of lateral conductors, the inclined segments 122 of adjacent curved cable cores 12 being pressed and contacted with each other and forming an arc transition groove 13 at the junction of the extruded contact surfaces, the outer portion of the arc segment 123 being provided with an external shaping buffer 10, the external shaping buffer 10 being made of an aluminum alloy sheet and having a double-layer structure and including an inner aluminum layer 101 and an outer Aluminum layer 102, inner aluminum layer 101 and arc surface segment 123 are wrapped and matched, two sides of the inner aluminum layer 101 are punched to form a pair of C-shaped segments 103, the C-shaped segments 103 on both sides of the same aluminum alloy sheet each lead out an outer aluminum layer 102 and overlap each other on the surface of the inner aluminum layer 101, a first aluminum sheath 2 is arranged on the outside of the external shaping buffer 10, a second aluminum sheath 3 is arranged on the outside of the first aluminum sheath 2, the seams of the first aluminum sheath 2 and the seams of the second aluminum sheath 3 are both welded to form a welding busbar 21, the second aluminum sheath 3 is arranged on the inner side of the insulating layer 4, an extruded inner sheath 7 is arranged between the metal shielding layer 6 and the aluminum alloy sheath 8, the extruded inner sheath 7 is made of montmorillonite modified polyethylene nanocomposite material, and the outer sheath 9 is made of low-smoke halogen-free flame-retardant polyolefin material.

[0025] The present invention provides a special aluminum alloy sheath 8 environmentally friendly ultra-high voltage cable, wherein adjacent curved cable cores 12 are mutually squeezed and enclosed to form an outer circle and inner edge structure, and the design of the outer circle and inner edge corresponds to the inner circle and outer edge characteristics of the polygonal cable core 11, and can form an extrusion relationship with the polygonal cable core 11, which is beneficial to ensure the stability of the physical structure of each cable core 1 inside the cable, and is also beneficial to prevent the torsion resistance of the center conductor 111 and the lateral conductor. The straight section 121, the inclined section 122 and the arc section 123 of the curved cable core 12 are integrally extruded and molded, and each includes at least one insulating protective layer. At the same time, the polygonal cable core 11 also has its own insulating protective layer, which can effectively improve the insulation performance of all cable cores 1. Furthermore, the external shaped buffer 10 is buckled on the outside of the arc surface segment 123, and cooperates with the groove 13 to ensure the anti-extrusion performance and relative position stability between adjacent curved cable cores 12; the first aluminum sheath 2 and the second aluminum sheath 3 are used to wrap all cable cores 1 and the external shaped buffer 10, and the welding seam tape is used at the respective seam positions to ensure the continuity and anti-extrusion performance of each curved surface, and replaces the traditional wrapping structure to obtain a relatively smooth and continuous wrapping surface, ensure the roundness of the structure within the insulating layer 4, which is beneficial to suppress the development of water trees inside the insulating layer 4, and each cable has independent insulation protection, which can effectively improve the overall insulation and electrical breakdown resistance of the cable.

[0026] Furthermore, the extruded inner sheath 7 provided by the present invention can provide uniform protection for its internal structure on the one hand, and on the other hand, the montmorillonite-modified polyethylene nanocomposite material used in the present invention has inorganic montmorillonite material dispersed at nanometer level in polyethylene material, which has characteristics not found in general traditional composite materials. Compared with traditional composite materials, it not only has high strength, high toughness and good heat resistance, but also has positive significance in inhibiting the development of water trees, and can improve the good aging resistance and electrical breakdown resistance of the cable, thereby further ensuring the working performance of the cable under ultra-high voltage environment, and helping to reduce the long-term cost of the power system. During the extrusion process, some tensile steel wires can be added to the extruded inner sheath 7, and the tensile steel wires are drawn out along the traction direction of the cable. The continuous unwinding action of the tensile steel wires matches the extrusion rate of the extruded inner sheath 7, thereby extruding the extruded inner sheath with inner steel wires to improve the mechanical properties of the extruded inner sheath 7. The outer sheath 9 is made of low-smoke halogen-free flame-retardant polyolefin material, which has good flame retardancy, water resistance and wear resistance, and has environmental protection advantages, which can further extend the actual service life of the cable.

[0027] In order to improve the stability and insulation of the polygonal cable core 11 inside the cable, the polygonal cable core 11 provided by the present invention includes a plurality of central conductors 111 with a circular cross-section, and an inner insulating layer 112 is arranged outside all the central conductors 111. The inner insulating layer 112 has an inner circle and outer edge structure, and the outer side of the inner insulating layer 112 is a regular dodecagon. An outer insulating layer 113 is arranged outside the inner insulating layer 112, and the inner and outer sides of the outer insulating layer 113 are a regular dodecagon and a regular hexagon, respectively. Among them, the inner circle of the inner insulating layer 112 provides a reasonable basic environment for all the central conductors 111, which can improve the bonding performance of the inner insulating layer 112 with the central conductor 111 during the extrusion process of all the central conductors 111, and the outer edges of the inner insulating layer 112 are plasticized through the regular dodecagonal clamping plate and the cooling medium on the extrusion path; the outer insulating layer 113 is wrapped with the inner insulating layer 112 and extruded and molded from the side of the regular dodecagon. The regular hexagonal characteristics formed can match the inner insulating layer 112, balance the pressure from the side of the regular dodecagon, and at the same time ensure that the curved cable core 12 sitting on its outer edge surface will not slip over a large area, thereby improving the stability of all cable cores 1.

[0028] In order to improve the anti-extrusion performance of the shape of the inner insulating layer 112, the regular hexagonal side of the outer insulating layer 113 provided by the present invention corresponds to the 6 side surfaces of the regular dodecagon of the inner insulating layer 112, and the other 6 side surfaces of the regular dodecagon correspond to the side edges and corners of the outer insulating layer 113, and an internal shaping buffer 114 is provided inside the side edges and corners of the outer insulating layer 113. Among them, the 6 side surfaces of the outer insulating layer 113 are in face-to-face extrusion contact with the 6 side surfaces of the regular dodecagon, and the 6 corner positions of the outer insulating layer 113 are provided with shaping pressure by the internal shaping buffer 114, so that the other 6 side surfaces of the regular dodecagon are subjected to the wrapping pressure of the curved cable core 12 and the structure outside, so that the adjacent side surfaces can maintain good plastic characteristics, thereby ensuring the reliability of the inner circle and outer edge structure characteristics of the inner insulating layer 112.

[0029] Furthermore, the cross section of the inner shaping buffer 114 provided by the present invention is Ω-shaped, and the inner shaping buffer 114 includes an arched section 1141, and the arched side of the arched section 1141 is opposite to the side edge of the outer insulating layer 113, and the arched side of the arched section 1141 is arranged on both sides of the inner insulating layer 112 with a plane shaping section 1142 that is in compression contact with the inner insulating layer 112. Among them, the arched section 1141 can bear a certain load, and can produce a certain angle of opening deformation in the event of real-time disturbance, and the opening surface of the plane shaping section 1142 is always attached to the other 6 side faces of the regular dodecagon. The anti-deformation reaction force generated between the inner shaping buffer 114 and the outer edge of the inner insulating layer 112 can make the inner shaping buffer automatically return to the equilibrium position in a short time, while ensuring the stability of the design of the outer circle and inner edge of the inner insulating layer 112.

[0030] In order to improve the bending performance of the inner shaping buffer 114 during the winding process of the cable, the outer surface of the inner shaping buffer 114 provided by the present invention is provided with a plurality of bending buffer grooves 1143 spaced apart along the length direction thereof. Therefore, during the bending process of the inner shaping buffer 114 during the winding process of the cable, the bending buffer grooves 1143 thereof can produce real-time bending deformation to ensure the uniformity of the structure with the inner insulating layer 112 and the outer insulating layer 113, further improving the practicality and utilization rate of the cable.

[0031] In order to improve the tensile performance of the external shaped buffer 10, the present invention provides a tensile rope 10 inside the C-shaped segment 103, the outer surface of the tensile rope is frictionally matched with the inner wall of the C-shaped segment to resist the strong axial tensile force inside the cable.

[0032] In order to improve the continuity of the first aluminum sheath 2 and the second aluminum sheath 3 in the cross-section, the present invention performs online welding on the respective seams of the two, and in order to ensure the stability of the aluminum package structure formed by the first aluminum sheath 2 and the second aluminum sheath 3, the welding busbar belt 21 of the first aluminum sheath 2 and the welding busbar belt of the second aluminum sheath 3 provided by the present invention adopt a staggered distribution design, which can avoid local collapse caused by excessive concentration of pressure at a single position.

[0033] In order to improve the insulation of the cable, the present invention provides a screen printing layer on the outer surface of the second aluminum sheath 3, and a graphite and paraffin mixed coating is coated on the screen printing layer. The graphite in the graphite and paraffin mixed coating can ensure the smoothness and semi-conductivity of the outer surface of the second aluminum sheath 3; the paraffin oil has certain waterproof and anti-magnetic interference properties. Therefore, the graphite and paraffin mixed coating further inhibits the development of water trees in the insulating layer 4 material from the aspects of creating smooth surface conditions and waterproofing, and further improves the insulation of the cable.

[0034] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A special aluminum alloy sheathed environmentally friendly ultra-high voltage cable, comprising a plurality of cable cores, the exterior of which is provided with an insulating layer, an outer semi-conductive layer, a metal shielding layer, an aluminum alloy sheath and an outer sheath, characterized in that: The plurality of cable cores include polygonal cable cores and a plurality of curved cable cores corresponding to the side surfaces of the polygonal cable cores one by one. The curved cable cores include straight surface segments corresponding to the side surfaces of the polygonal cable cores. The straight surface segments are provided with inclined surface segments on both sides. Arc surface segments are provided between the straight surface segments. The straight surface segments, inclined surface segments and arc surface segments are used for extrusion wrapping of a plurality of lateral conductors. The inclined surface segments of adjacent curved cable cores are mutually extruded and contacted and grooves are formed at the junction of the extruded contact surfaces. An external shaping buffer is provided on the outside of the arc surface segment. The external shaping buffer is made of an aluminum alloy sheet and has a double-layer structure and includes an inner aluminum layer and an outer aluminum layer. The inner aluminum layer is wrapped and matched with the arc surface segment. A pair of C-shaped segments are formed by stamping the two sides of the inner aluminum layer. The C-shaped sections on both sides of the same aluminum alloy sheet each lead out an outer aluminum layer and overlap each other on the surface of the inner aluminum layer, a first aluminum sheath is arranged on the outer side of the outer shaping buffer, a second aluminum sheath is arranged on the outer side of the first aluminum sheath, the joints of the first aluminum sheath and the joints of the second aluminum sheath are both welded to form a welding busbar, the second aluminum sheath is arranged on the inner side of the insulating layer, an extruded inner sheath is arranged between the metal shielding layer and the aluminum alloy sheath, the extruded inner sheath is made of montmorillonite-modified polyethylene nanocomposite material, and the outer sheath is made of low-smoke halogen-free flame-retardant polyolefin material; a screen-printed layer is arranged on the outer surface of the second aluminum sheath, and a mixed coating of graphite and paraffin is coated on the screen-printed layer.

2. The special aluminum alloy sheathed environmentally friendly ultra-high voltage cable according to claim 1, characterized in that: The polygonal cable core includes a plurality of central conductors gathered into a circular cross-section, an inner insulating layer is arranged outside all the central conductors, the inner insulating layer is an inner circle and outer edge structure, the outer side of the inner insulating layer is a regular dodecagon, an outer insulating layer is arranged outside the inner insulating layer, and the inner side and outer side of the outer insulating layer are a regular dodecagon and a regular hexagon respectively.

3. The special aluminum alloy sheathed environmentally friendly ultra-high voltage cable according to claim 2, characterized in that: The regular hexagonal side of the outer insulating layer corresponds to the six side surfaces of the regular dodecagon of the inner insulating layer, and the other six side surfaces of the regular dodecagon correspond to the side corners of the outer insulating layer. An inner shaping buffer is provided inside the side corners of the outer insulating layer.

4. The special aluminum alloy sheathed environmentally friendly ultra-high voltage cable according to claim 3, characterized in that: The cross section of the inner shaping buffer is Ω-shaped, and the inner shaping buffer comprises an arched section, the arched side of the arched section is opposite to the side edge of the outer insulating layer, and the arched section is provided with planar shaping sections on both sides facing the inner insulating layer for extrusion contact with the inner insulating layer.

5. The special aluminum alloy sheathed environmentally friendly ultra-high voltage cable according to claim 4, characterized in that: The outer side surface of the inner shaped buffer is provided with a plurality of curved buffer grooves which are distributed at intervals along the length direction thereof.

6. The special aluminum alloy sheathed environmentally friendly ultra-high voltage cable according to claim 1, characterized in that: An anti-tension rope is arranged inside the C-shaped segment.

7. The special aluminum alloy sheathed environmentally friendly ultra-high voltage cable according to claim 1, characterized in that: The welding busbar strips of the first aluminum sheath and the welding busbar strips of the second aluminum sheath are distributed alternately.

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