Aluminum alloy core double-core water-blocking photovoltaic direct-current cable and preparation method thereof

Abstract

The application discloses an aluminum alloy core double-core water-blocking photovoltaic direct-current cable and a preparation method thereof, and relates to the technical field of photovoltaic cables. The aluminum alloy core double-core water-blocking photovoltaic direct-current cable comprises two parallel wire core units, and the two wire core units are both coated with an inner sheath and an outer sheath. The wire core unit comprises, from inside to outside, an aluminum alloy conductor, an insulation layer and an insulation water-blocking layer. The aluminum alloy conductor is filled with water-blocking yarn at the gap. The two outer sheaths are integrally connected through a hollow connecting rib. The outer sheath and the inner sheath are spirally provided with a barrier strip. The insulation water-blocking layer and the inner sheath form a honeycomb-shaped buffer multi-chamber structure. The buffer multi-chamber structure is filled with water-swelling powder. The aluminum alloy single wire is twisted to form the conductor, the water-blocking yarn is filled in the gap, the insulation water-blocking layer is arranged on the wire core unit, and the water-swelling powder in the buffer multi-chamber structure is combined, so that the water-blocking of the conductor, the insulation layer and the interlayer is realized in all dimensions.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cable technology, specifically to an aluminum alloy core dual-core water-blocking photovoltaic DC cable and its preparation method. Background Technology

[0002] With the rapid development of the photovoltaic power generation industry, photovoltaic DC cables, as the core component for power transmission in photovoltaic systems, are mostly used in outdoor open-air environments. They often face complex working conditions such as high temperature, ultraviolet radiation, rain and snow erosion, and mechanical vibration. At the same time, they need to meet the requirements of lightweight, low loss, and high reliability. Especially in special areas such as coastal areas, rainy areas, and humid areas, the water resistance, structural stability, and ease of installation of cables have become key factors affecting the long-term stable operation of photovoltaic systems.

[0003] The existing patent application, with publication number CN120356728A and publication date of July 22, 2025, is titled "A Dual-Core Water-Blocking and Weather-Resistant Photovoltaic DC Cable and Its Preparation Method." This patent includes two cable bodies, each consisting of, from the inside out, a tin-plated conductor, water-blocking adhesive, an insulation layer, a water-blocking tape, and a sheath layer. A connecting rib is fixedly arranged between the two sheath layers. The water-blocking tape is double-layered and wrapped around the insulation layer, with the double layers being a PET substrate and an acrylic adhesive, respectively. The insulation layer… It features a double-layer design: the inner layer is XLPE with 3% nano-aluminum hydroxide, and the outer layer is XLPE with 5% nano-carbon black. A hot-melt water-blocking adhesive is applied between the tin-plated conductor and the insulation layer for longitudinal water blocking, and a double-layer water-blocking strip is used for radial water blocking, effectively improving its water-blocking performance. The inner insulation layer is XLPE with 3% nano-aluminum hydroxide, which effectively improves its flame-retardant performance, while the outer layer is XLPE with 5% nano-carbon black, which is UV-resistant and water-resistant, enhancing its water-blocking and UV-resistant properties.

[0004] The aforementioned applications have shortcomings. Dual-core cables simply bind two single-core cables together using a simple connection structure. The gaps formed by the twisting of multiple aluminum alloy monofilaments are prone to water ingress, and there is a lack of effective internal water-blocking structures. Once water seeps in, it corrodes the conductor, damages the insulation performance, and shortens the cable's service life. The external water-blocking designs are often quite simple, only adding water-blocking materials to the sheath layer or using simple water-blocking tape. After water seeps in, it can also penetrate vertically to other parts, failing to achieve full-dimensional water-blocking protection. When the cable sheath is damaged due to outdoor aging or mechanical wear, water can easily seep in along the damaged areas, penetrating the insulation layer and contacting the conductor, causing safety hazards such as short circuits and leakage. At the same time, the connection points of existing dual-core cables are prone to water accumulation and lack effective drainage structures. Long-term water accumulation will accelerate the aging and damage of the connection points, further reducing the cable's water-blocking reliability and making it difficult to adapt to rainy and humid outdoor conditions. Summary of the Invention

[0005] The purpose of this invention is to provide an aluminum alloy core dual-core water-blocking photovoltaic DC cable and its preparation method, so as to overcome the shortcomings of the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A dual-core water-blocking photovoltaic DC cable with an aluminum alloy core includes two parallel core units. Each core unit is covered with an inner sheath and an outer sheath. From the inside out, each core unit includes an aluminum alloy conductor, an insulation layer, and an insulating water-blocking layer. The aluminum alloy conductor is made of multiple strands of aluminum alloy monofilaments twisted together, with water-blocking yarn filling the gaps. The two outer sheaths are integrally connected by a hollow connecting rib. A barrier strip is spirally wound between the outer sheath and the inner sheath. A honeycomb-shaped buffer multi-chamber structure is formed between the insulating water-blocking layer and the inner sheath. The buffer multi-chamber structure is filled with water-swellable powder. Arc-shaped water-guiding grooves and several drainage holes are respectively opened on both sides of the hollow connecting rib. Tear lines are longitudinally distributed in the hollow connecting rib between adjacent drainage holes. A hydrophobic layer is provided on the side of the inner sheath and the outer sheath near the dual-core connecting rib.

[0008] Preferably, the insulating water-blocking layer and the insulating layer are co-extruded in two layers, the insulating layer is a weather-resistant radiation cross-linked halogen-free low-smoke polyolefin, and the insulating water-blocking layer is a polyethylene or nylon layer.

[0009] Preferably, the honeycomb-shaped buffer multi-chamber structure consists of independent sealed chambers continuously distributed along the longitudinal direction of the cable, with the water-swellable powder independently filling each chamber to form a segmented water-blocking unit.

[0010] Preferably, the hollow connecting rib is filled with a permeable support core and a flexible water-blocking core sequentially along the length of the cable.

[0011] Preferably, the arc-shaped water guide channel has a V-shaped tearing groove longitudinally formed inside, the V-shaped tearing groove is connected to each drainage hole, and a baffle is embedded inside the V-shaped tearing groove between adjacent drainage holes.

[0012] Preferably, the inner sheath is a semi-conductive polyethylene layer, and the outer sheath is a weather-resistant, radiation-crosslinked, halogen-free, low-smoke polyolefin layer.

[0013] Preferably, the outer wall of the insulating water-blocking layer is provided with multiple annular water-blocking protrusions at equal intervals along the longitudinal direction. The annular water-blocking protrusions are interference-fitted with the inner wall of the inner sheath to form a multi-segment circumferential sealing partition.

[0014] Preferably, a pair of vertically distributed reinforcing ribs are embedded at the connection points between the two outer sheaths and the hollow connecting ribs.

[0015] Preferably, the outer surface of the inner sheath is provided with longitudinally spirally distributed snap-fit ​​protrusions, and the inner surface of the barrier strip is provided with an engagement groove that matches the snap-fit ​​protrusions.

[0016] A method for preparing the above-mentioned aluminum alloy core dual-core water-blocking photovoltaic DC cable includes the following steps:

[0017] S1. Preparation of aluminum alloy conductor: The aluminum alloy rod is drawn into wire and continuously annealed. When multiple strands of monofilament are twisted together, water-swellable water-blocking yarn is filled simultaneously to form an aluminum alloy conductor with water-blocking yarn for waterproofing.

[0018] S2. Co-extrusion of insulation layer and water-blocking insulation layer: A double-layer co-extruded insulation layer and water-blocking insulation layer are formed on the outside of the aluminum alloy conductor, and cross-linked by electron accelerator irradiation to form the core body;

[0019] S3. Barrier strip and multi-chamber molding: A honeycomb-shaped buffer multi-chamber structure is formed on the outside of the insulating water-blocking layer of the core body. Water-swellable powder is filled into each independent sealed chamber. Then, an inner sheath is extruded on the outside of the buffer multi-chamber structure. Finally, a barrier strip is spirally wound on the outer surface of the inner sheath.

[0020] S4. Dual-core cabling pretreatment: Arrange two core units that have been processed in step S in parallel and symmetrically, maintaining the preset spacing between the two core units to form a dual-core arrangement structure. At the same time, check the wrapping of the barrier strip on the outer surface of the inner sheath.

[0021] S5. Extrusion of hydrophobic layer and outer sheath: An integrated co-extrusion process is adopted to extrude the outer sheath and hollow connecting rib simultaneously, so that the hollow connecting rib is located between the two core units and is formed integrally with the outer sheath. During the extrusion process, tear lines are embedded inside the hollow connecting rib along the length of the cable.

[0022] In the above technical solution, a conductor is formed by twisting multiple aluminum alloy monofilaments together, with water-blocking yarn filling the gaps between the strands. Simultaneously, an insulating water-blocking layer is set in the core unit. Combined with water-swellable powder within the buffer multi-chamber structure, this achieves full-dimensional water blocking of the conductor, insulation layer, and interlayer layers, meeting both longitudinal and radial water blocking requirements. This effectively prevents moisture from penetrating and corroding the conductor and damaging the insulation. Tear-off wires are installed within the hollow connecting ribs for easy and quick separation of the two cores during installation. Arc-shaped water-guiding grooves and drainage holes are also provided on the surface of the connecting ribs. Combined with a hydrophobic layer on the outer sheath near the connecting ribs, this allows for rapid drainage of accumulated water, preventing water accumulation and aging at the connection points. The spirally wound barrier strip between the outer and inner sheaths further enhances interlayer bonding and mechanical protection. A honeycomb-shaped buffer multi-chamber structure is also set between the insulating water-blocking layer and the inner sheath, which not only buffers outdoor mechanical vibration and external pressure but also further enhances the water-blocking effect through the water-swellable powder, delaying interlayer peeling and aging.

[0023] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit this disclosure.

[0024] This application provides an overview of various implementations or examples of the technology described in this disclosure, and is not a full disclosure of the entire scope or all features of the disclosed technology. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0026] Figure 1 This is a schematic diagram of the overall structure of a dual-core water-blocking photovoltaic DC cable with an aluminum alloy core according to the present invention.

[0027] Figure 2 This is a schematic cross-sectional view of a dual-core water-blocking photovoltaic DC cable with an aluminum alloy core according to the present invention.

[0028] Figure 3 In this invention Figure 2 Enlarged view of the structure at point A;

[0029] Figure 4 This is a cross-sectional view of the outer sheath and hollow connecting ribs of a double-core water-blocking photovoltaic DC cable with an aluminum alloy core according to the present invention.

[0030] Figure 5 This is a schematic diagram of the structure of the core unit in a dual-core water-blocking photovoltaic DC cable with an aluminum alloy core according to the present invention.

[0031] Figure 6 This is a schematic diagram showing the connection between the insulating water-blocking layer and the buffer multi-chamber structure in an aluminum alloy core dual-core water-blocking photovoltaic DC cable of the present invention.

[0032] Figure 7 This is a schematic diagram of the inner sheath and barrier strip in a dual-core water-blocking photovoltaic DC cable with an aluminum alloy core according to the present invention.

[0033] Figure 8 This is a schematic diagram of the inner sheath structure in a dual-core water-blocking photovoltaic DC cable with an aluminum alloy core according to the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Core unit; 11. Aluminum alloy conductor; 12. Insulation layer; 13. Water-blocking insulating layer; 14. Water-blocking yarn; 15. Annular water-blocking protrusion; 2. Inner sheath; 21. Snap-fit ​​protrusion; 3. Outer sheath; 31. Reinforcing rib; 4. Hollow connecting rib; 41. Tear line; 42. Arc-shaped water guide groove; 43. Drain hole; 44. Water-permeable support core; 45. Flexible water-blocking core; 46. V-shaped tear groove; 47. Block; 5. Barrier strip; 51. Engaging groove; 6. Buffer multi-chamber structure; 61. Water-swellable powder; 7. Hydrophobic layer. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0037] Please see Figure 1-8 This invention provides an aluminum alloy core dual-core water-blocking photovoltaic DC cable, comprising two parallel core units 1, each covered by an inner sheath 2 and an outer sheath 3. Each core unit 1, from the inside out, comprises an aluminum alloy conductor 11, an insulation layer 12, and an insulating water-blocking layer 13. The aluminum alloy conductor 11 is formed by twisting multiple aluminum alloy monofilaments, with water-blocking yarn 14 filling the gaps. The two outer sheaths 3 are integrally connected by a hollow connecting rib 4. A barrier strip 5 is spirally wound between the outer sheath 3 and the inner sheath 2. A honeycomb-shaped buffer multi-chamber structure 6 is formed between the insulating water-blocking layer 13 and the inner sheath 2. The buffer multi-chamber structure 6 is filled with water-swellable powder 61. Arc-shaped water-guiding grooves 42 and several drainage holes 43 are respectively opened on both sides of the hollow connecting rib 4. Tear lines 41 are longitudinally distributed within the hollow connecting rib 4, located between adjacent drainage holes 43. A hydrophobic layer 7 is provided on the side of both the inner sheath 2 and the outer sheath 3 near the dual-core connecting rib.

[0038] Specifically, the aluminum alloy conductor 11 uses multiple aluminum alloy monofilaments twisted together, reducing the construction cost and difficulty associated with copper core cables. During conductor twisting, polyacrylamide-based water-blocking yarn 14 is filled to ensure no gaps, achieving the first layer of water-blocking protection inside the conductor. This effectively solves the problem of water ingress and corrosion in the twisting gaps of the aluminum alloy conductor 11, meeting the long-term outdoor operation requirements of large-scale ground-mounted photovoltaic power stations. The honeycomb-shaped buffer multi-chamber structure 6 formed between the inner sheath 2 and the insulating water-blocking layer 13 is integrally molded using a special mold, with a uniform ring distribution. Each chamber has a regular hexagonal cross-section and is filled with water-swellable powder 61. The water-swellable powder 61 is made of polyacrylamide-based expanding material. When water seeps in, the expanding powder quickly absorbs water and expands, filling the chambers and blocking the seepage channels, achieving the third layer of water-blocking protection. The barrier strip between the outer sheath 3 and the inner sheath 2 is a metal strip, which not only enhances the bonding force between the inner sheath 2 and the outer sheath 3, preventing interlayer peeling, but also blocks external mechanical damage and ultraviolet radiation from reaching the internal water-blocking layer and insulation. Layer 12 provides all-around protection. The hydrophobic layer 7 on the side of the inner sheath 2 and outer sheath 3 near the hollow connecting rib 4 reduces the adhesion of water at the connection point. Water flows along the hydrophobic layer 7 into the arc-shaped water guide groove 42 and then quickly exits the cable through the drainage hole 43, preventing water accumulation and aging at the connection point. This multi-stage water blocking effectively prevents water from lingering inside the cable, protecting the conductor and insulation structure from corrosion and damage. It avoids the water treeing phenomenon that easily occurs in ordinary cables under the long-term effects of water and electric field, and prevents water from spreading longitudinally along the conductor, causing connector corrosion. This ensures the stability of the cable during long-term outdoor operation in large-scale ground-mounted photovoltaic power stations. The two core units 1 are connected as a whole by the hollow connecting rib 4, ensuring the integrity of the dual-core structure and facilitating the batch laying and organization of large-scale ground-mounted photovoltaic power stations. When it is necessary to separate the dual cores at the inverter interface, simply pull the tear line 41 inside the hollow connecting rib 4 to quickly separate the two core units 1 without the need for cutting tools, making the operation simple.

[0039] Compared with the prior art, the embodiments of the present invention use multiple strands of aluminum alloy monofilaments twisted together to form a conductor, fill the gaps between the strands with water-blocking yarn 14, and simultaneously set an insulating water-blocking layer 13 in the core unit 1. Combined with the water-swellable powder 61 in the buffer multi-chamber structure 6, it achieves full-dimensional water blocking of the conductor, insulation layer 12, and interlayers, meeting the requirements for longitudinal and radial water blocking, effectively preventing water from penetrating and corroding the conductor and damaging the insulation. A tear-off line 41 is set in the hollow connecting rib 4 to facilitate quick separation of the two cores during installation. At the same time, on the surface of the connecting rib... The arc-shaped water-guiding groove 42 and drainage hole 43 are set up in conjunction with the hydrophobic layer 7 on the side of the outer sheath 3 near the connecting rib to achieve rapid drainage of accumulated water and avoid water accumulation and aging at the connection point. The spirally wound barrier strip 5 between the outer sheath 3 and the inner sheath 2 enhances the interlayer bonding force and mechanical protection capability. At the same time, a honeycomb buffer multi-chamber structure 6 is set between the insulating water-blocking layer 13 and the inner sheath 2, which can not only buffer outdoor mechanical vibration and external pressure, but also further improve the water-blocking effect through the water-swelling powder 61, delaying interlayer peeling and aging.

[0040] In a further embodiment of the present invention, the insulating water-blocking layer 13 and the insulating layer 12 are co-extruded in two layers. The insulating layer 12 is a weather-resistant irradiated cross-linked halogen-free low-smoke polyolefin, and the insulating water-blocking layer 13 is a polyethylene or nylon layer. Specifically, the insulating layer 12 covers the outside of the aluminum alloy conductor 11 and is made of 125℃ irradiated cross-linked low-smoke halogen-free material. This material not only has excellent insulation and high-temperature resistance, and can adapt to the 125℃ working environment for a long time, effectively isolating the conductor from the outside electrical connection and avoiding leakage hazards, but also has the environmentally friendly characteristics of low smoke and halogen-free. It will not produce toxic and harmful smoke in the event of a fire, improving the operational safety of large-scale ground photovoltaic power stations and meeting the environmental protection requirements of power stations. The insulating water-blocking layer 13 covers the outside of the insulating layer 12 and can be made of polyethylene or nylon. Both materials have excellent water-blocking performance and flexibility, and can be tightly attached to the insulating layer 12, effectively preventing water from penetrating the insulating layer 12 and achieving a second layer of water-blocking protection.

[0041] In a further embodiment of the present invention, the buffer multi-chamber structure 6 is a honeycomb-shaped sealed chamber continuously distributed along the longitudinal direction of the cable. Water-swellable powder 61 is independently filled in each chamber to form a segmented water-blocking unit. Specifically, each independent sealed chamber is separated by a diaphragm. The diaphragm is heat-sealed with the insulating water-blocking layer 13 and the inner wall of the inner sheath 2 to ensure that each chamber is completely independent. This segmented design can effectively avoid the overall water-blocking performance from the failure of a single chamber. When a certain section of the chamber expands when exposed to water, the unaffected chambers can still maintain the complete water-blocking function, forming a protection mechanism that prevents the spread of local failure. The filling amount of water-swellable powder 61 is 60%-70% of the volume of each chamber, which ensures that the chamber is fully filled after expansion and avoids overfilling that could cause the chamber to rupture, and can respond quickly to water seepage.

[0042] In a further embodiment of the present invention, the hollow connecting rib 4 is filled with a permeable support core 44 and a flexible water-blocking core 45 sequentially along the length of the cable. Specifically, the permeable support core 44 can effectively improve the overall tensile strength of the hollow connecting rib 4, preventing the hollow connecting rib 4 from breaking and the two cores from separating due to tensile force during long-distance cable laying. The permeable support core 44 has a porous structure and corresponds to the drainage hole 43, improving the overall structure and drainage reliability of the two core connection part. The flexible water-blocking core 45 has flexible characteristics that can adapt to the bending of the cable, preventing the flexible water-blocking core from being damaged due to cable bending. At the same time, it can prevent the water inside the hollow connecting rib 4 from flowing freely in the longitudinal direction, realizing water-blocking isolation inside the hollow connecting rib 4, preventing water from penetrating into the core unit 1 along the inner wall of the hollow connecting rib 4, and further strengthening the all-dimensional water-blocking effect of the cable.

[0043] In a further embodiment of the present invention, a V-shaped tearing groove 46 is longitudinally formed within the arc-shaped water guide channel 42. The V-shaped tearing groove 46 is connected to each drainage hole 43, and a stop block 47 is embedded inside the V-shaped tearing groove 46 between adjacent drainage holes 43. Specifically, the V-shaped tearing groove 46 is formed along the longitudinal central axis of the arc-shaped water guide channel 42, extending through the entire length of the arc-shaped water guide channel 42. The V-shaped tearing groove 46 corresponds one-to-one with each drainage hole 43 and is interconnected. The top of each drainage hole 43 is connected to the bottom of the V-shaped tearing groove 46. The connection point adopts a smooth transition design without sharp edges to prevent water from stagnating at the connection point and ensure that the accumulated water in the arc-shaped water guide channel 42 can flow smoothly into each drainage hole 43 through the V-shaped tearing groove 46. 3. Quickly discharge the cable to the outside. The V-shaped tear groove 46 is designed to work in conjunction with the tear line 41. When it is necessary to separate the two cores, the V-shaped tear groove 46 can be used to quickly position the tear line 41. At the same time, the V-shaped tear groove 46 can be used to guide the tear line 41 more easily, avoiding deviation or jamming of the tear line 41 during the tearing process. The baffle 47 can separate the water remaining in the V-shaped tear groove 46, preventing the water from forming a continuous water flow and spreading longitudinally in the groove, further improving the local water blocking effect. The baffle 47 is integrally formed with the same material as the hollow connecting rib 4, and its height is less than the depth of the V-shaped tear groove 46. It does not affect the normal pulling of the tear line 41, and can effectively block the water flow path.

[0044] In a further embodiment of the present invention, the inner sheath 2 is a semi-conductive polyethylene layer, and the outer sheath 3 is a weather-resistant irradiated cross-linked halogen-free low-smoke polyolefin layer. Specifically, the inner sheath 2 is made of semi-conductive polyethylene material, which can eliminate the accumulation of interface charge between the insulation layer 12 and the inner sheath 2, reduce the local electric field strength, and can also be tightly bonded to the insulating water-blocking layer 13 to form a continuous semi-conductive path, thereby improving the operational safety of the cable. The outer sheath 3 is made of weather-resistant irradiated cross-linked halogen-free low-smoke polyolefin material. After irradiation cross-linking treatment, it has excellent resistance to ultraviolet aging, high and low temperature resistance, and mechanical strength. It can operate stably for a long time in different environments and effectively resist the corrosion of the cable by the harsh outdoor environment. At the same time, the surface of the outer sheath 3 can also be provided with anti-slip texture as needed to increase the friction during laying and prevent the cable from sliding and shifting during installation.

[0045] In a further embodiment of the present invention, multiple annular water-blocking protrusions 15 are arranged at equal intervals along the longitudinal direction on the outer wall of the insulating water-blocking layer 13. The annular water-blocking protrusions 15 are interference-fitted with the inner wall of the inner sheath 2 to form a multi-segment circumferential sealing barrier. Specifically, the annular water-blocking protrusions 15 are integrally formed using the same material as the insulating water-blocking layer 13, and can be flexibly adjusted according to the humidity conditions of the cable laying environment. When water attempts to penetrate longitudinally along the gap between the insulating water-blocking layer 13 and the inner sheath 2, the annular water-blocking protrusions 15 can be tightly squeezed against the inner wall of the inner sheath 2 to form a physical barrier, extending the water penetration path. Combined with the water-swellable powder 61 in the honeycomb buffer multi-chamber structure 6, multiple longitudinal water-blocking barriers are formed, further improving the reliability of interlayer water blocking and avoiding the overall waterproof performance decline due to the failure of a single water-blocking structure.

[0046] In a further embodiment of the present invention, a pair of vertically distributed reinforcing ribs 31 are embedded at the connection between the two outer sheaths 3 and the hollow connecting ribs 4. Specifically, the length of the reinforcing ribs 31 is consistent with that of the hollow connecting ribs 4, and they are continuously distributed along the longitudinal direction of the cable. Their surfaces are roughened to increase the bonding area with the materials of the outer sheaths 3 and the hollow connecting ribs 4. They are integrally formed with the outer sheaths 3 and the hollow connecting ribs 4 through a hot-melt process to ensure uniform stress distribution. This effectively disperses the stress at the connection and prevents cracking at the connection due to stress concentration when the cable is bent or pulled.

[0047] In a further embodiment of the present invention, the outer surface of the inner sheath 2 is provided with longitudinally spirally distributed snap-fit ​​protrusions 21, and the inner surface of the barrier strip 5 is provided with an engagement groove 51 that matches the snap-fit ​​protrusions 21. Specifically, the snap-fit ​​protrusions 21 and the engagement grooves 51 are in a one-to-one correspondence. The cross-section of the snap-fit ​​protrusions 21 is an isosceles trapezoid, and the shape of the engagement grooves 51 is adapted to the snap-fit ​​protrusions 21. The corresponding spiral groove structure is adopted, and the trajectories of the two are completely overlapped. When the barrier strip 5 is spirally wound, the interlocking groove 51 is automatically guided and fitted along the spiral trajectory of the snap-fit ​​protrusion 21 without manual adjustment, thus achieving efficient production. The two achieve tight interlocking through interference fit, which can significantly enhance the connection between the barrier strip 5 and the inner sheath 2, prevent the barrier strip 5 from shifting or falling off during cable bending or vibration, and ensure that the barrier strip 5 always maintains a stable spiral winding state, thereby continuously playing its role in enhancing interlayer bonding and mechanical protection. At the same time, the interlocking structure of the snap-fit ​​protrusion 21 and the interlocking groove 51 can also increase the path length of water penetration, further improve the water-blocking performance between layers, and form effective protection for the internal structure of the cable.

[0048] A method for preparing the above-mentioned aluminum alloy core dual-core water-blocking photovoltaic DC cable includes the following steps:

[0049] S1. Preparation of aluminum alloy conductor 11: Aluminum alloy rod is drawn and continuously annealed. Multiple aluminum alloy monofilaments are twisted together by a stranding machine. At the same time, water-blocking yarn 14 is added to the stranding pan. The water-blocking yarn 14 is evenly distributed in the conductor gap by the wire separating plate to form an aluminum alloy conductor 11 with water-blocking yarn 14.

[0050] S2, Co-extrusion of insulation layer 12 and water-blocking insulation layer 13: Double-layer co-extrusion of insulation layer 12 and water-blocking insulation layer 13 on the outside of aluminum alloy conductor 11, cross-linked by electron accelerator irradiation to form the core body;

[0051] S3, Barrier Strip 5 and Multi-chamber Forming: A honeycomb-shaped buffer multi-chamber structure 6 is formed on the outside of the insulating water-blocking layer 13 of the core body. Water-swellable powder 61 is filled into each independently sealed chamber. Then, an inner sheath 2 is extruded on the outside of the buffer multi-chamber structure 6. Then, a barrier strip 5 is spirally wound on the outer surface of the inner sheath 2.

[0052] S4. Pre-processing of double-core cabling: Arrange two core units 1 that have been processed in step S in parallel and symmetrically, maintaining the preset spacing between the two core units 1 to form a double-core arrangement structure. At the same time, check the wrapping of the barrier strip 5 on the outer surface of the inner sheath 2.

[0053] S5, Extrusion of hydrophobic layer 7 and outer sheath 3: An integrated co-extrusion process is adopted to extrude the outer sheath 3 and hollow connecting rib 4 simultaneously, so that the hollow connecting rib 4 is located between the two core units 1 and is formed integrally with the outer sheath 3. During the extrusion process, tear lines 41 are embedded inside the hollow connecting rib 4 along the length of the cable.

[0054] Compared with existing technologies, the preparation method of this invention achieves water blocking inside the conductor and optimizes the stranding process by simultaneously filling water-blocking yarn 14 during the stranding of aluminum alloy conductor 11, eliminating the need for additional water blocking steps. The method adopts double-layer co-extrusion of insulation layer 12 and water-blocking insulation layer 13 and cross-linking by electron accelerator irradiation, which simplifies the production process and improves the integrity and stability of the insulation structure. The honeycomb buffer multi-chamber structure 6 is integrally formed by a special mold and combined with the segmented filling of water-swellable powder 61, which ensures the water blocking effect while achieving efficient chamber forming. The dual-core cable adopts a parallel symmetrical arrangement and an integral co-extrusion outer sheath 3 and hollow connecting ribs 4 process, which ensures the integrity of the dual-core structure and the stability of the connecting ribs. The embedded design of tear line 41 simplifies the subsequent separation operation. All links in the entire preparation process are closely connected, realizing the integrated production of the entire process from conductor to outer sheath 3, which effectively improves production efficiency, reduces production costs, and ensures the water blocking performance, mechanical properties and installation convenience of the cable, meeting the high requirements of large-scale ground photovoltaic power stations for cables.

[0055] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A double-core water-blocking photovoltaic DC cable with an aluminum alloy core, characterized in that, It includes two parallel wire core units (1), and both wire core units (1) are covered with an inner sheath (2) and an outer sheath (3). The core unit (1) includes, from the inside out, an aluminum alloy conductor (11), an insulation layer (12), and an insulating and water-blocking layer (13). The aluminum alloy conductor (11) is made of multiple strands of aluminum alloy monofilaments twisted together, and the gaps are filled with water-blocking yarn (14). The two outer sheaths (3) are integrally connected by a hollow connecting rib (4). A barrier strip (5) is spirally wound between the outer sheath (3) and the inner sheath (2). A honeycomb buffer multi-chamber structure (6) is formed between the insulating water-blocking layer (13) and the inner sheath (2). The buffer multi-chamber structure (6) is filled with water-swellable powder (61). The hollow connecting rib (4) has an arc-shaped water guide groove (42) and several drainage holes (43) on both sides. Tear lines (41) are longitudinally distributed in the hollow connecting rib (4) between adjacent drainage holes (43). The inner sheath (2) and the outer sheath (3) are provided with a hydrophobic layer (7) on the side close to the double core connecting rib.

2. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, The insulating water-blocking layer (13) and the insulating layer (12) are co-extruded together. The insulating layer (12) is a weather-resistant irradiated cross-linked halogen-free low-smoke polyolefin, and the insulating water-blocking layer (13) is a polyethylene or nylon layer.

3. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, The honeycomb-shaped buffer multi-chamber structure (6) consists of independent sealed chambers continuously distributed along the longitudinal direction of the cable. The water-swellable powder (61) is independently filled in each chamber to form a segmented water-blocking unit.

4. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, The hollow connecting rib (4) is filled with a permeable support core (44) and a flexible water-blocking core (45) in sequence along the length of the cable.

5. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, The arc-shaped water guide channel (42) has a V-shaped tearing groove (46) longitudinally opened inside. The V-shaped tearing groove (46) is connected to each drainage hole (43), and a baffle (47) is embedded inside the V-shaped tearing groove (46) between adjacent drainage holes (43).

6. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, The inner sheath (2) is a semi-conductive polyethylene layer, and the outer sheath (3) is a weather-resistant irradiated cross-linked halogen-free low-smoke polyolefin layer.

7. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, The outer wall of the insulating water-blocking layer (13) is provided with multiple annular water-blocking protrusions (15) at equal intervals along the longitudinal direction. The annular water-blocking protrusions (15) are interference-fitted with the inner wall of the inner sheath (2) to form a multi-segment circumferential sealing partition.

8. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, A pair of reinforcing ribs (31) are embedded at the connection between the two outer sheaths (3) and the hollow connecting ribs (4).

9. The aluminum alloy core dual-core water-blocking photovoltaic DC cable according to claim 1, characterized in that, The outer surface of the inner sheath (2) is provided with longitudinally spirally distributed snap-fit ​​protrusions (21), and the inner surface of the barrier strip (5) is provided with a bite groove (51) that matches the snap-fit ​​protrusions (21).

10. A method for preparing a double-core water-blocking photovoltaic DC cable with an aluminum alloy core as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Preparation of aluminum alloy conductor (11): The aluminum alloy rod is drawn into wire and continuously annealed. When multiple strands of single wire are twisted together, water-swellable water-blocking yarn (14) is filled simultaneously to form an aluminum alloy conductor (11) with water-blocking yarn (14) for waterproofing. S2, Co-extrusion of insulation layer (12) and water-blocking insulation layer (13): Double-layer co-extrusion of insulation layer (12) and water-blocking insulation layer (13) on the outside of aluminum alloy conductor (11) is cross-linked by electron accelerator irradiation to form the core body; S3, Barrier Strip (5) and Multi-chamber Forming: A honeycomb-shaped buffer multi-chamber structure (6) is formed on the outside of the insulating water-blocking layer (13) of the core body. Water-swellable powder (61) is filled into each independently sealed chamber. Then, an inner sheath (2) is extruded on the outside of the buffer multi-chamber structure (6). Then, a barrier strip (5) is spirally wound on the outer surface of the inner sheath (2). S4. Pre-processing of double-core cabling: Arrange two core units (1) after the processing of step S3 in parallel and symmetrically, maintain the preset distance between the two core units (1) to form a double-core arrangement structure, and at the same time check the winding of the barrier strip (5) on the outer surface of the inner sheath (2). S5. Extrusion of hydrophobic layer (7) and outer sheath (3): The outer sheath (3) and hollow connecting rib (4) are extruded simultaneously using an integrated co-extrusion process, so that the hollow connecting rib (4) is located between the two core units (1) and is formed integrally with the outer sheath (3). During the extrusion process, tear lines (41) are embedded inside the hollow connecting rib (4) along the length of the cable.

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