High performance composite structure power cable and its preparation method

Abstract

The application relates to the technical field of cable materials, and particularly discloses a high-efficiency composite-structure power cable and a preparation method thereof; the high-efficiency composite-structure power cable comprises a conductor, an insulation layer, an asymmetric shielding layer and an outer jacket layer, the insulation layer comprises an inner layer, a middle layer and an outer layer, the inner layer raw material comprises a nano-porous polyolefin matrix, the middle layer raw material comprises boron nitride and elastic silica gel, and the outer layer raw material comprises a voltage stabilizer and cross-linked polyethylene. The inner layer, the middle layer and the outer layer which are composed of different raw materials form a gradient insulation system; under the synergistic action of various components, electric field uniform distribution is realized, local discharge is effectively inhibited, the strength and impact resistance of the cable in a high-voltage power transmission scene are improved, and the service life of the cable is prolonged.

Description

Technical Field

[0001] This application relates to the field of cable material technology, and in particular to a high-efficiency composite structure power cable and its preparation method. Background Technology

[0002] High-voltage transmission cables play a vital role in modern power transmission. With increasing power demand and longer transmission distances, higher requirements are placed on the current-carrying capacity, insulation performance, and mechanical strength of these cables. Currently, the industry primarily improves cable performance by increasing conductor cross-sectional area, optimizing insulation materials, and refining shielding structures.

[0003] However, these methods cannot solve the problem of reduced current carrying capacity of traditional cables due to the skin effect in high-voltage transmission scenarios; the insulation performance of a single insulation material will gradually decline when faced with complex voltage environments and heat accumulation, and it cannot effectively guarantee the long-term stable operation of the cable; at the same time, this insulation layer is difficult to suppress the occurrence of partial discharge, which will accelerate the aging and damage of the insulation material, further reducing the service life of the cable. Summary of the Invention

[0004] To improve the service life of cables in high-voltage power transmission scenarios, this application provides a high-efficiency composite structure power cable and its preparation method.

[0005] In the first aspect, this application provides a high-efficiency composite structure power cable, which adopts the following technical solution: A high-efficiency composite structure power cable includes a conductor, an insulation layer, an asymmetric shielding layer, and an outer jacket layer. The insulation layer includes an inner layer, a middle layer, and an outer layer. The inner layer material includes a nanoporous polyolefin matrix, the middle layer material includes boron nitride and elastic silicone, and the outer layer material includes a voltage stabilizer and cross-linked polyethylene.

[0006] By adopting the above technical solution, a gradient insulation system is formed by using inner, middle, and outer layers of insulation composed of different raw materials. Through the synergistic effect of each component, a uniform electric field distribution is achieved, effectively suppressing partial discharge. The double protection of an asymmetric shielding layer and an outer jacket layer outside the insulation layer allows the asymmetric shielding layer to guide charge distribution, eliminating electric field distortion caused by traditional symmetric shielding and delaying insulation aging. The outer jacket layer enhances the cable's strength and impact resistance in high-voltage transmission scenarios, extending the cable's service life.

[0007] Preferably, the inner layer comprises the following raw materials in parts by weight: 40-50 parts of polyolefin resin, 5-10 parts of compatibilizer, and 3-8 parts of porous silica; the outer layer comprises the following raw materials in parts by weight: 40-50 parts of cross-linked polyethylene and 1-3 parts of voltage stabilizer.

[0008] By adopting the above technical solution, porous silica is added to the inner layer. Utilizing its large specific surface area, it captures charges to form a space charge field, offsetting some external charges, promoting a uniform electric field distribution, inhibiting space charge accumulation, and effectively hindering the initiation and growth of electrical trees. Adding porous silica to the inner layer directly improves the cable's heat resistance and strength, absorbs internal stress, and enhances the cable's impact resistance and thermal stability. Using cross-linked polyethylene in the outer layer further improves the insulation's heat resistance and strength, enhancing the stability of the insulation structure during cable operation. Adding an appropriate amount of voltage stabilizer to the outer layer improves the cable's resistance to corona aging and tracking, delays the chemical aging process of the insulation material under strong electric fields, and extends its service life.

[0009] Preferably, the voltage stabilizer is m-aminobenzoic acid.

[0010] Preferably, the middle layer comprises the following raw materials in parts by weight: 40-50 parts of elastic silicone, 5-15 parts of boron nitride nanosheets, and 1-3 parts of pentaerythritol diphosphite; wherein the elastic silicone is methyl vinyl silicone rubber.

[0011] By adopting the above technical solution, using elastic silicone as the matrix in the middle layer provides good stress buffering and toughness. It can absorb and buffer stress through its large deformation, preventing delamination or cracking at the interface between the inner and outer layers due to excessive modulus differences. Filling the middle layer material with boron nitride nanosheets effectively suppresses the space charge accumulation phenomenon in silicone rubber, improves the electrical insulation performance and thermal stability of the insulation layer, and further enhances the durability of the cable in high-voltage transmission environments.

[0012] Preferably, the boron nitride nanosheets are pre-modified with polydopamine, and the modification method includes the following specific steps: Boron nitride nanosheets, dopamine hydrochloride, and anhydrous ethanol were mixed and added to a tris(hydroxymethyl)aminomethane buffer solution. The mixture was then ultrasonically dispersed and reacted. The product was washed, filtered, and freeze-dried under vacuum to obtain polydopamine-modified boron nitride.

[0013] By adopting the above technical solution, boron nitride nanosheets modified with polydopamine can exhibit good dispersibility in elastic silicone systems, reduce the aggregation of boron nitride nanosheets, and further improve the electrical performance and strength of cables.

[0014] Preferably, the mass ratio of the boron nitride nanosheets, dopamine hydrochloride, and tris(hydroxymethyl)aminomethane is 1:(0.3-0.8):(0.1-0.3).

[0015] Preferably, the asymmetric shielding layer is woven from aluminum foil and conductive fibers, with the aluminum foil arranged in a wavy pattern along the cable axis and the conductive fibers woven at 45° to cover the trough areas.

[0016] By adopting the above technical solution, an asymmetric corrugated shielding layer is used to actively guide charge distribution, eliminate the electric field distortion caused by traditional symmetrical shielding, delay the aging of cable insulation structure, and improve the stability of cable structure.

[0017] Preferably, the outer layer is a composite of corrugated tubular thermoplastic polyurethane elastomer and aramid fiber web, wherein the corrugated walls of the thermoplastic polyurethane elastomer alternate circumferentially, and the aramid fibers are densely woven at the crests.

[0018] Preferably, the conductor is a layered spiral annealed copper wire bundle.

[0019] By adopting the above technical solution, the current path is optimized through the layered spiral conductor structure, the skin effect loss is reduced, and the power transmission efficiency of the cable is improved.

[0020] Secondly, this application provides a method for preparing a high-efficiency composite structure power cable, which adopts the following technical solution: A method for preparing a high-efficiency composite structure power cable includes the following specific steps: After melting the inner layer raw material, middle layer raw material, and outer layer raw material, they are extruded and coated onto the outside of the conductor in sequence to form an insulation layer. Then, an asymmetric shielding layer and an outer jacket layer are sequentially laminated on the outside of the insulation layer to obtain a high-efficiency composite structure power cable.

[0021] By adopting the above technical solutions, the synergistic effect of multi-layer structure and multiple components can improve the stability of insulation structure, reduce partial discharge, and improve the stability and service life of cable materials in high-voltage power transmission scenarios.

[0022] In summary, this application has the following beneficial effects: 1. Because this application uses different components as raw materials to construct the inner, middle, and outer layers, forming a gradient insulation system, it achieves a uniform electric field distribution and suppresses partial discharge. The double protection of the insulation layer by an asymmetric shielding layer and an outer jacket enhances the strength and impact resistance of the cable in high-voltage transmission scenarios and extends the aging period of the insulation structure.

[0023] 2. This application employs porous silica added to the inner layer of the insulation layer to suppress space charge accumulation and effectively inhibit the initiation and growth of electrical trees, thereby improving the cable's impact resistance and thermal stability. Cross-linked polyethylene and voltage stabilizers are used in the outer layer of the insulation layer to improve the cable's resistance to corona aging and tracking, delaying the chemical aging process of the insulation material under a strong electric field and extending its service life. Elastic silicone is used as the matrix in the middle layer of the insulation layer to prevent peeling or cracking at the interface between the inner and outer layers due to excessive modulus differences. Detailed Implementation

[0024] The present application will be further described in detail below with reference to the embodiments.

[0025] All raw materials used in the examples are commercially available. Example

[0026] Example 1 This embodiment provides a high-efficiency composite structure power cable, including a conductor, an insulation layer, an asymmetric shielding layer, and an outer jacket. The insulation layer includes an inner layer, a middle layer, and an outer layer. The conductor is a layered spiral annealed copper wire bundle. The asymmetric shielding layer is woven from aluminum foil and conductive fibers, with the conductive fibers being carbon fiber. The aluminum foil is arranged in a wavy pattern along the cable axis, and the conductive fibers are woven at 45° intervals to cover the trough areas. The outer jacket is a composite of corrugated tubular thermoplastic polyurethane elastomer and aramid fiber web. The corrugated walls of the thermoplastic polyurethane elastomer alternate circumferentially, and the aramid fibers are densely woven at the crests.

[0027] The inner layer of the insulation layer comprises the following raw materials in parts by weight: 45 kg of polyolefin resin, 8 kg of compatibilizer, and 5 kg of porous silica; wherein the porous silica has a specific surface area of ​​700 m². 2 / g, the polyolefin resin is linear low-density polyethylene, the number average molecular weight of linear low-density polyethylene is 40,000, the compatibilizer is maleic anhydride-grafted polypropylene, and the grafting rate is 0.8%.

[0028] The outer layer of the insulation layer comprises the following raw materials in parts by weight: 45 kg of cross-linked polyethylene and 2 kg of voltage stabilizer; the cross-linked polyethylene is 220 kV / XLPE granules purchased from Zhejiang Wanma Polymer Materials Group Co., Ltd., and the voltage stabilizer is m-aminobenzoic acid.

[0029] The middle layer of the insulation layer comprises the following raw materials in parts by weight: 45 kg of elastic silicone, 10 kg of boron nitride nanosheets, and 2 kg of pentaerythritol diphosphite; the elastic silicone is methyl vinyl silicone rubber, and the boron nitride nanosheets have an average particle size of 150 nm and a thickness of 10 nm.

[0030] This embodiment provides a method for preparing a high-efficiency composite structure power cable, including the following specific steps: S1: Polyolefin resin, compatibilizer, and porous silica are mixed, heated to 130°C, and melt-extruded onto the outside of the conductor to form the inner layer; elastic silicone, boron nitride nanosheets, and pentaerythritol diphosphite are mixed, heated to 150°C, and melt-extruded onto the outside of the inner layer to form the middle layer; cross-linked polyethylene and voltage stabilizer are mixed, heated to 160°C, and melt-extruded onto the outside of the middle layer to form the outer layer, which is the insulating layer.

[0031] S2: Aluminum foil and conductive fibers are woven around the outside of the insulation layer to form an asymmetric shielding layer. The aluminum foil is arranged in a wavy pattern along the cable axis, and the conductive fibers are woven at 45° to cover the trough area. Thermoplastic polyurethane elastomer corrugated pipe wall alternates circumferentially on the outside of the asymmetric shielding layer, and aramid fibers are densely woven at the crest to form an outer jacket layer.

[0032] Example 2

[0033] The difference between Example 2 and Example 1 is that the inner layer of the insulating layer includes the following raw materials in parts by weight: 40 kg of polyolefin resin, 5 kg of compatibilizer, and 8 kg of porous silica.

[0034] Example 3

[0035] The difference between Example 3 and Example 1 is that the inner layer of the insulating layer includes the following raw materials in parts by weight: 50 kg of polyolefin resin, 10 kg of compatibilizer, and 3 kg of porous silica.

[0036] Example 4

[0037] The difference between Example 4 and Example 1 is that the outer layer of the insulating layer includes the following raw materials in parts by weight: 40 kg of cross-linked polyethylene and 1 kg of voltage stabilizer.

[0038] Example 5 The difference between Example 5 and Example 1 is that the outer layer of the insulating layer includes the following raw materials in parts by weight: 50 kg of cross-linked polyethylene and 3 kg of voltage stabilizer.

[0039] Example 6

[0040] The difference between Example 6 and Example 1 is that the middle layer of the insulating layer includes the following raw materials in parts by weight: 40 kg of elastic silicone, 15 kg of boron nitride nanosheets, and 1 kg of pentaerythritol diphosphite.

[0041] Example 7

[0042] The difference between Example 7 and Example 1 is that the middle layer of the insulating layer includes the following raw materials in parts by weight: 50 kg of elastic silicone, 5 kg of boron nitride nanosheets, and 3 kg of pentaerythritol diphosphite.

[0043] Example 8

[0044] The difference between Example 8 and Example 1 is that the boron nitride nanosheets in the middle layer of the insulating layer are pre-modified with polydopamine.

[0045] This embodiment provides a method for preparing a high-efficiency composite structure power cable, including the following specific steps: S1: Boron nitride nanosheets, dopamine hydrochloride, and anhydrous ethanol were mixed and added to a tris(hydroxymethyl)aminomethane buffer solution. The tris(hydroxymethyl)aminomethane buffer solution was a mixture of tris(hydroxymethyl)aminomethane and water in a mass ratio of 1:0.8. The mass ratio of boron nitride nanosheets, dopamine hydrochloride, and tris(hydroxymethyl)aminomethane was 1:0.3:0.1. After ultrasonic dispersion for 30 min, the reaction was continued for 10 h. The product was washed, filtered, and freeze-dried under vacuum to obtain polydopamine-modified boron nitride.

[0046] S2: Polyolefin resin, compatibilizer, and porous silica are mixed, heated to 130°C, and melt-extruded onto the outside of the conductor to form the inner layer; elastic silicone, polydopamine-modified boron nitride, and pentaerythritol diphosphite are mixed, heated to 150°C, and melt-extruded onto the outside of the inner layer to form the middle layer; cross-linked polyethylene and voltage stabilizer are mixed, heated to 160°C, and melt-extruded onto the outside of the middle layer to form the outer layer, i.e., the insulating layer.

[0047] S3: Aluminum foil and conductive fibers are woven around the outside of the insulation layer to form an asymmetric shielding layer. The aluminum foil is arranged in a wavy pattern along the cable axis, and the conductive fibers are woven at 45° to cover the trough area. Thermoplastic polyurethane elastomer corrugated pipe wall alternates circumferentially on the outside of the asymmetric shielding layer, and aramid fibers are densely woven at the crest to form an outer jacket layer.

[0048] Example 9

[0049] The difference between Example 9 and Example 8 is that the mass ratio of boron nitride nanosheets, dopamine hydrochloride, and tris(hydroxymethyl)aminomethane is 1:0.8:0.3.

[0050] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the high-efficiency composite structure power cable does not use a middle layer.

[0051] This embodiment provides a method for preparing a high-efficiency composite structure power cable, including the following specific steps: S1: Mix polyolefin resin, compatibilizer, and porous silica, heat to 130°C, melt and extrude onto the outside of the conductor to form the inner layer; mix cross-linked polyethylene and voltage stabilizer, heat to 160°C, melt and extrude onto the outside of the inner layer to form the outer layer, i.e., the insulation layer.

[0052] S2: Aluminum foil and conductive fibers are woven around the outside of the insulation layer to form an asymmetric shielding layer. The aluminum foil is arranged in a wavy pattern along the cable axis, and the conductive fibers are woven at 45° to cover the trough area. Thermoplastic polyurethane elastomer corrugated pipe wall alternates circumferentially on the outside of the asymmetric shielding layer, and aramid fibers are densely woven at the crest to form an outer jacket layer.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the high-efficiency composite structure power cable does not use inner and middle layers in its raw materials.

[0054] A method for preparing a high-efficiency composite structure power cable includes the following specific steps: S1: After mixing cross-linked polyethylene and voltage stabilizer, heat to 160°C and melt-extrude onto the outside of the conductor to form an insulating layer.

[0055] S2: Aluminum foil and conductive fibers are woven around the outside of the insulation layer to form an asymmetric shielding layer. The aluminum foil is arranged in a wavy pattern along the cable axis, and the conductive fibers are woven at 45° to cover the trough area. Thermoplastic polyurethane elastomer corrugated pipe wall alternates circumferentially on the outside of the asymmetric shielding layer, and aramid fibers are densely woven at the crest to form an outer jacket layer.

[0056] The high-efficiency composite structure power cables provided in Examples 1-9 and Comparative Examples 1-2 of this application were subjected to the following performance tests, and the specific test results are shown in Table 1.

[0057] I. Space Charge The space charge characteristics of the high-efficiency composite power cable prepared in this application were measured using the electroacoustic pulse method. The electrode was a semi-conductive electrode with a diameter of 1.8 cm. The test was conducted at room temperature with a test field strength of 50 kV / mm, a pulse voltage of 500 V, a pulse width of 10 ns, a polarization time of 30 min, and a depolarization time of 10 min. The distribution of space charge inside the sample under polarization and depolarization conditions was measured, and the maximum charge density during polarization was recorded.

[0058] II. Mechanical Properties Referring to the standard GB / T528—2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", stress-strain curves were tested using an electronic universal testing machine under standard test conditions at a tensile rate of 500 mm / min. The tensile strength and elongation at break of the high-efficiency composite structure power cable prepared in this application were then tested.

[0059] Table 1: Performance Test Results Data Table

[0060] The performance test results show that the high-efficiency composite structure power cable prepared in this application has good strength and toughness, while achieving uniform electric field distribution, suppressing space charge accumulation, and reducing partial discharge. Comparing Comparative Examples 1-2 with Example 1, it is evident that Comparative Example 1 does not use a middle layer, and Comparative Example 2 does not use an inner layer or a middle layer. The performance test results show that the overall performance of the prepared cables is significantly reduced, and the service life of the cables is also significantly shortened. Furthermore, the mechanical properties of the cable prepared in Comparative Example 1 are significantly reduced, further demonstrating that through the synergistic effect of the various components of the middle layer, it can absorb and buffer stress through its large deformation, preventing peeling or cracking at the interface between the inner and outer layers due to excessive modulus differences, thus improving the durability of the cable in high-voltage transmission environments.

[0061] As shown in Examples 8-9, boron nitride nanosheets in the middle layer of the insulation layer are pre-modified with polydopamine. The performance test results show that the strength of the cable material is further improved. This further illustrates that the boron nitride nanosheets modified with polydopamine can have good dispersibility in the elastic silicone system, reduce the agglomeration of boron nitride nanosheets, and further improve the electrical performance and strength of the cable.

[0062] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-efficiency composite structure power cable, characterized in that, The material comprises a conductor, an insulating layer, an asymmetric shielding layer, and an outer layer. The insulating layer includes an inner layer, a middle layer, and an outer layer. The inner layer comprises the following raw materials in parts by weight: 40-50 parts polyolefin resin, 5-10 parts compatibilizer, and 3-8 parts porous silica. The middle layer comprises the following raw materials in parts by weight: 40-50 parts elastic silicone rubber, 5-15 parts boron nitride nanosheets, and 1-3 parts pentaerythritol diphosphite. The elastic silicone rubber is methyl vinyl silicone rubber. The outer layer comprises the following raw materials in parts by weight: 40-50 parts cross-linked polyethylene and 1-3 parts voltage stabilizer.

2. The high-efficiency composite structure power cable according to claim 1, characterized in that, The voltage stabilizer is m-aminobenzoic acid.

3. The high-efficiency composite structure power cable according to claim 1, characterized in that, The boron nitride nanosheets are pre-modified with polydopamine, and the modification method includes the following specific steps: Boron nitride nanosheets, dopamine hydrochloride, and anhydrous ethanol were mixed and added to a tris(hydroxymethyl)aminomethane buffer solution. The mixture was then ultrasonically dispersed and reacted. The product was washed, filtered, and freeze-dried under vacuum to obtain polydopamine-modified boron nitride.

4. The high-efficiency composite structure power cable according to claim 3, characterized in that, The mass ratio of the boron nitride nanosheets, dopamine hydrochloride, and tris(hydroxymethyl)aminomethane is 1:(0.3-0.8):(0.1-0.3).

5. The high-efficiency composite structure power cable according to claim 1, characterized in that, The asymmetric shielding layer is woven from aluminum foil and conductive fibers. The aluminum foil is arranged in a wavy pattern along the cable axis, and the conductive fibers are woven at 45° to cover the trough areas.

6. The high-efficiency composite structure power cable according to claim 1, characterized in that, The outer layer is a composite of corrugated tubular thermoplastic polyurethane elastomer and aramid fiber web, with the corrugated walls of the thermoplastic polyurethane elastomer alternating circumferentially and the aramid fibers densely woven at the crests.

7. The high-efficiency composite structure power cable according to claim 1, characterized in that, The conductor is a layered spiral annealed copper wire bundle.

8. A method for preparing a high-efficiency composite structure power cable as described in any one of claims 1-7, characterized in that, The specific steps include the following: After melting the inner layer raw material, middle layer raw material, and outer layer raw material, they are extruded and coated onto the outside of the conductor in sequence to form an insulation layer. Then, an asymmetric shielding layer and an outer jacket layer are sequentially laminated on the outside of the insulation layer to obtain a high-efficiency composite structure power cable.

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