A 110kV water-tree resistant cross-linked polyethylene insulated power cable

Abstract

The present invention provides a 110kV water-tree resistant cross-linked polyethylene insulated power cable, comprising a conductor, wherein the conductor is provided with a conductor shielding layer, an insulating layer, an insulating shielding layer, a wrapping layer, a metal shielding layer, a metal shielding wrapping layer, an outer sheath and a semi-conductive layer in sequence from the inside to the outside; wherein the insulating layer is made of an anti-water-tree improved XLPE insulating material by extrusion. The present invention reduces water trees generated by the long-term operation of the cable through the anti-water-tree improved XLPE insulating material, which may form electrical trees under the action of overvoltage and eventually lead to insulation breakdown, thereby improving the purpose of the cable life, and can eliminate the radial waterproof layer, that is, the corrugated aluminum sleeve, which can greatly reduce the outer diameter of the cable and reduce the cost.

Description

Technical Field

[0001] The invention belongs to the technical field of electric wires and cables, and relates to a cross-linked polyethylene insulated power cable, and in particular to a 110kV water-tree resistant cross-linked polyethylene insulated power cable. Background Art

[0002] Wires and cables are essential basic equipment for transmitting electrical energy and manufacturing various motors, instruments, and meters to achieve point-to-point energy conversion. There are many types of wires and cables with a wide range of applications, involving industries such as electricity, construction, communications, and manufacturing. With the continuous expansion of the scale of industries such as the electric power industry, data communications industry, urban rail transit industry, automobile industry, and shipbuilding industry, the requirements for wires and cables will also grow rapidly.

[0003] As the main power source for power transmission, the safety and reliability of ultra-high voltage cables are of vital importance. Ordinary cross-linked polyethylene (XLPE) insulated cables have excellent electrical and mechanical properties in a dry environment. However, in actual applications, the cable laying environment is usually harsh. Cables often need to be immersed in water for a short or long time, or are placed in a very humid environment. After long-term use, water trees are easily generated, which eventually turn into electrical trees and cause insulation breakdown, greatly reducing their lifespan.

[0004] The use of water-tree-resistant XLPE insulation material can eliminate the radial waterproof layer, i.e. the corrugated aluminum sleeve, which can greatly reduce the outer diameter of the cable and also reduce costs.

[0005] At present, most European and American countries have replaced ordinary insulating materials with water-tree resistant insulating materials, and even use water-tree resistant insulating materials on high-voltage cables. It is of great significance to study higher voltage level water-tree resistant insulating materials. Summary of the invention

[0006] The technical problem to be solved by the present invention is that: at present, water-tree resistant insulation materials of voltage levels of 66 kV and below have basically reached the world level, but there is a lack of water-tree resistant cross-linked polyethylene insulated power cables of 66 kV and above, especially 110 kV.

[0007] Therefore, the present invention provides a 110kV water-tree resistant cross-linked polyethylene insulated power cable. The present invention can reduce the formation of water trees through the anti-water-tree improved XLPE insulating material, thereby extending the service life of the cable, and can eliminate the radial waterproof layer, that is, the corrugated aluminum sleeve, which can greatly reduce the outer diameter of the cable and also reduce the cost.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention provides a 110kV water-tree resistant cross-linked polyethylene insulated power cable, comprising a conductor, wherein the conductor is provided with a conductor shielding layer, an insulating layer, an insulating shielding layer, a wrapping layer, a metal shielding layer, a metal shielding wrapping layer, an outer sheath and a semi-conductive layer in sequence from the inside to the outside; wherein the insulating layer is made of extruded anti-water-tree improved XLPE insulating material.

[0010] As a preferred solution of the present invention, the conductor is copper.

[0011] As a preferred embodiment of the present invention, the raw materials of the water-tree-resistant improved XLPE insulating material include, by weight: 90-95 parts of low-density polyethylene, 0.3-3 parts of polyethylene glycol, 1-5 parts of a compatibilizer ethylene-acrylic acid copolymer, 0.1-0.3 parts of a light stabilizer 4050H, 1.4-2.5 parts of a cross-linking agent diisopropyl peroxide, 0.1-0.5 parts of a co-cross-linking agent triallyl isocyanurate and 0.1-0.4 parts of an antioxidant.

[0012] As a preferred embodiment of the present invention, the water-tree resistant improved XLPE insulating material is prepared by the following method: adding the remaining components except the cross-linking agent and the auxiliary cross-linking agent into a twin-screw extruder for mixing, extruding and granulating; after mixing the cross-linking agent and the auxiliary cross-linking agent, post-absorbing is performed to obtain the water-tree resistant improved XLPE insulating material.

[0013] As a preferred embodiment of the present invention, the mixing temperature is 85-200°C.

[0014] As a preferred embodiment of the present invention, the absorption temperature is 60-80°C and the absorption time is 12-24h.

[0015] As a preferred solution of the present invention, the metal shielding layer is made of copper wire.

[0016] As a preferred solution of the present invention, the wrapping layer is made of semi-conductive nylon tape and non-woven fabric.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) The present invention uses an anti-water tree improved XLPE insulating material to reduce water tree formation caused by long-term operation of the cable. Water tree formation may form electrical tree formation under the action of overvoltage, which eventually leads to insulation breakdown, thereby improving the service life of the cable. In addition, the radial waterproof layer, i.e., the corrugated aluminum sleeve, can be eliminated, which can greatly reduce the outer diameter of the cable and reduce the cost.

[0019] 2) The present invention coats the insulating shielding layer outside the insulating layer to provide a complete interface for the insulating layer to homogenize the electric field.

[0020] 3) The metal shielding layer of the present invention can carry short-circuit current, and when the cable is laid on the seabed, the copper wire can bear the tension. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] In the figure, 1, conductor; 2, conductor shielding layer; 3, insulation layer; 4, insulation shielding layer; 5, wrapping layer; 6, metal shielding layer; 7, metal shielding wrapping layer; 8, outer sheath; 9, semi-conductive layer. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The water tree-resistant improved XLPE insulating material used in the present invention is prepared by mixing, extruding and granulating low-density polyethylene as the main raw material, adding water tree inhibitor, compatibilizer, light stabilizer, antioxidant, crosslinking agent and the like.

[0025] The anti-water tree improved XLPE insulating material includes the following components and weight proportions: 90-95 parts of low-density polyethylene (LDPE), 0.3-3 parts of polyethylene glycol, 1-5 parts of compatibilizer ethylene-acrylic acid copolymer (EAA), 0.1-0.3 parts of light stabilizer (HALS) 4050H, 1.4-2.5 parts of cross-linking agent diisopropyl peroxide (DCP), 0.1-0.5 parts of auxiliary cross-linking agent triallyl isocyanurate (TAIC), and 0.1-0.4 parts of antioxidant (300#).

[0026] The above components (except the cross-linking agent and the auxiliary cross-linking agent) are added into a twin-screw extruder for mixing, extrusion and granulation, and the mixing temperature is 85-200°C; and after the cross-linking agent and the auxiliary cross-linking agent are mixed, post-absorption is performed to obtain an anti-water tree improved XLPE insulation material, and the absorption temperature is 60-80°C and the absorption time is 12-24h.

[0027] In the present invention, the preparation process of the 110kV water-tree resistant cross-linked polyethylene insulated power cable is the conventional preparation process of the applicant company, which will not be described in detail below.

[0028] Example 1

[0029] See also Figure 1The present invention provides a 110kV water-tree resistant cross-linked polyethylene insulated power cable, the 110kV water-tree resistant cross-linked polyethylene insulated power cable comprises a conductor 1, the conductor 1 is provided with a conductor shielding layer 2 (thickness 1.0mm), an insulating layer 3 (thickness 16.0mm), an insulating shielding layer 4 (thickness 1.0mm), a wrapping layer 5 (thickness 4.0mm), a metal shielding layer 6 (thickness 2.0mm), a metal shielding wrapping layer 7 (thickness 2.0mm), an outer sheath 8 (thickness 4.5mm) and a semi-conductive layer 9 (thickness 0.5mm) in sequence from inside to outside; wherein the insulating layer 3 is made of extruded anti-water-tree improved XLPE insulating material.

[0030] Copper is used as the material of the conductor 1 to transmit electrical energy.

[0031] A conductor shielding layer 2 is formed on the surface of the conductor 1 by using a mixture of polyolefin and carbon black, in order to provide a complete interface for the insulating layer 3 to homogenize the electric field.

[0032] The insulating layer 3 is formed on the surface of the conductor shielding layer 2 by using anti-water tree improved XLPE insulating material, in order to reduce the water tree branches generated by the long-term operation of the cable. The water tree branches may form electrical tree branches under the action of overvoltage, and finally lead to the occurrence of insulation breakdown, thereby increasing the service life of the cable.

[0033] The components and weight proportions of the anti-water tree improved XLPE insulation material are: 90 parts of low-density polyethylene (LDPE), 0.3 parts of polyethylene glycol, 1 part of compatibilizer ethylene-acrylic acid copolymer (EAA), 0.1 part of light stabilizer (HALS) 4050H, 1.4 parts of cross-linking agent diisopropyl peroxide (DCP), 0.1 part of auxiliary cross-linking agent triallyl isocyanurate (TAIC), and 0.1 part of antioxidant (300#).

[0034] The above components (except the cross-linking agent and the auxiliary cross-linking agent) are added into a twin-screw extruder for mixing, extrusion and granulation, and the mixing temperature is 85-200°C; and after the cross-linking agent and the auxiliary cross-linking agent are mixed, post-absorption is performed to obtain an anti-water tree improved XLPE insulation material, and the absorption temperature is 60-80°C and the absorption time is 12-24h.

[0035] An insulating shielding layer 4 is formed on the surface of the insulating layer 3 using a mixture of polyolefin (polypropylene) and carbon black, in order to provide a complete interface for the insulating layer 3 to homogenize the electric field.

[0036] A semi-conductive nylon tape and non-woven fabric are used to form a wrapping layer 5 on the surface of the insulating shielding layer 4, in order to protect the shielding integrity of the insulating shielding layer 4 and prevent the copper wire from damaging the cable.

[0037] Copper wires are used to form a metal shielding layer 6 on the surface of the sheath 5 in order to carry the short-circuit current. When the cable is laid on the seabed, the copper wires bear some tension.

[0038] A non-woven fabric is used to form a metal shielding wrapping layer 7 on the surface of the metal shielding layer 6 in order to fasten the metal shielding layer 6 .

[0039] Polyethylene is used to form an outer sheath 8 on the surface of the metal shielding wrapping layer 7, which plays a role in flame retardancy and protecting the cable.

[0040] A mixture of polyethylene and carbon black is used to form a semi-conductive layer 9 on the surface of the outer sheath 8, which forms a loop with the metal shielding layer 6 during detection to check the integrity of the sheath.

[0041] Example 2

[0042] The present invention provides a 110kV water-tree resistant cross-linked polyethylene insulated power cable, comprising a conductor 1, wherein the conductor 1 is provided with a conductor shielding layer 2, an insulating layer 3, an insulating shielding layer 4, a wrapping layer 5, a metal shielding layer 6, a metal shielding wrapping layer 7, an outer sheath 8 and a semi-conductive layer 9 in sequence from the inside to the outside; wherein the insulating layer 3 is made of extruded XLPE insulating material with improved water-tree resistant properties.

[0043] Copper is used as the material of the conductor 1 to transmit electrical energy.

[0044] A conductor shielding layer 2 is formed on the surface of the conductor 1 by using a mixture of polyolefin and carbon black, in order to provide a complete interface for the insulating layer 3 to homogenize the electric field.

[0045] The insulating layer 3 is formed on the surface of the conductor shielding layer 2 by using anti-water tree improved XLPE insulating material, in order to reduce the water tree branches generated by the long-term operation of the cable. The water tree branches may form electrical tree branches under the action of overvoltage, and finally lead to the occurrence of insulation breakdown, thereby increasing the service life of the cable.

[0046] The components and weight proportions of the anti-water tree improved XLPE insulation material are: 92 parts of low-density polyethylene (LDPE), 1 part of polyethylene glycol, 3 parts of compatibilizer ethylene-acrylic acid copolymer (EAA), 0.2 parts of light stabilizer (HALS) 4050H, 2 parts of cross-linking agent diisopropyl peroxide (DCP), 0.3 parts of auxiliary cross-linking agent triallyl isocyanurate (TAIC), and 0.25 parts of antioxidant (300#).

[0047] The above components (except the cross-linking agent and the auxiliary cross-linking agent) are added into a twin-screw extruder for mixing, extrusion and granulation, and the mixing temperature is 85-200°C; and after the cross-linking agent and the auxiliary cross-linking agent are mixed, post-absorption is performed to obtain an anti-water tree improved XLPE insulation material, and the absorption temperature is 60-80°C and the absorption time is 12-24h.

[0048] An insulating shielding layer 4 is formed on the surface of the insulating layer 3 using a mixture of polyolefin (polypropylene) and carbon black, in order to provide a complete interface for the insulating layer 3 to homogenize the electric field.

[0049] A semi-conductive nylon tape and non-woven fabric are used to form a wrapping layer 5 on the surface of the insulating shielding layer 4, in order to protect the shielding integrity of the insulating shielding layer 4 and prevent the copper wire from damaging the cable.

[0050] Copper wires are used to form a metal shielding layer 6 on the surface of the sheath 5 in order to carry the short-circuit current. When the cable is laid on the seabed, the copper wires bear some tension.

[0051] A non-woven fabric is used to form a metal shielding wrapping layer 7 on the surface of the metal shielding layer 6 in order to fasten the metal shielding layer 6 .

[0052] Polyethylene is used to form an outer sheath 8 on the surface of the metal shielding wrapping layer 7, which plays a role in flame retardancy and protecting the cable.

[0053] A mixture of polyethylene and carbon black is used to form a semi-conductive layer 9 on the surface of the outer sheath 8, which forms a loop with the metal shielding layer 6 during detection to check the integrity of the sheath.

[0054] Example 3

[0055] The present invention provides a 110kV water-tree resistant cross-linked polyethylene insulated power cable, comprising a conductor 1, wherein the conductor 1 is provided with a conductor shielding layer 2, an insulating layer 3, an insulating shielding layer 4, a wrapping layer 5, a metal shielding layer 6, a metal shielding wrapping layer 7, an outer sheath 8 and a semi-conductive layer 9 in sequence from the inside to the outside; wherein the insulating layer 3 is made of extruded XLPE insulating material with improved water-tree resistant properties.

[0056] Copper is used as the material of the conductor 1 to transmit electrical energy.

[0057] A conductor shielding layer 2 is formed on the surface of the conductor 1 by using a mixture of polyolefin and carbon black, in order to provide a complete interface for the insulating layer 3 to homogenize the electric field.

[0058] The insulating layer 3 is formed on the surface of the conductor shielding layer 2 by using anti-water tree improved XLPE insulating material, in order to reduce the water tree branches generated by the long-term operation of the cable. The water tree branches may form electrical tree branches under the action of overvoltage, and finally lead to the occurrence of insulation breakdown, thereby increasing the service life of the cable.

[0059] The components and weight proportions of the water tree resistant improved XLPE insulation material are as follows: 95 parts of low-density polyethylene (LDPE), 3 parts of polyethylene glycol, 5 parts of compatibilizer ethylene-acrylic acid copolymer (EAA), 0.3 parts of light stabilizer (HALS) 4050H, 2.5 parts of cross-linking agent diisopropyl peroxide (DCP), 0.5 parts of auxiliary cross-linking agent triallyl isocyanurate (TAIC), and 0.4 parts of antioxidant (300#).

[0060] The above components (except the cross-linking agent and the auxiliary cross-linking agent) are added into a twin-screw extruder for mixing, extrusion and granulation, and the mixing temperature is 85-200°C; and after the cross-linking agent and the auxiliary cross-linking agent are mixed, post-absorption is performed to obtain an anti-water tree improved XLPE insulation material, and the absorption temperature is 60-80°C and the absorption time is 12-24h.

[0061] An insulating shielding layer 4 is formed on the surface of the insulating layer 3 using a mixture of polyolefin (polypropylene) and carbon black, in order to provide a complete interface for the insulating layer 3 to homogenize the electric field.

[0062] A semi-conductive nylon tape and non-woven fabric are used to form a wrapping layer 5 on the surface of the insulating shielding layer 4, in order to protect the shielding integrity of the insulating shielding layer 4 and prevent the copper wire from damaging the cable.

[0063] Copper wires are used to form a metal shielding layer 6 on the surface of the sheath 5 in order to carry the short-circuit current. When the cable is laid on the seabed, the copper wires bear some tension.

[0064] A non-woven fabric is used to form a metal shielding wrapping layer 7 on the surface of the metal shielding layer 6 in order to fasten the metal shielding layer 6 .

[0065] Polyethylene is used to form an outer sheath 8 on the surface of the metal shielding wrapping layer 7, which plays a role in flame retardancy and protecting the cable.

[0066] A mixture of polyethylene and carbon black is used to form a semi-conductive layer 9 on the surface of the outer sheath 8, which forms a loop with the metal shielding layer 6 during detection to check the integrity of the sheath.

[0067] The 110 kV water-tree resistant cross-linked polyethylene insulated power cable prepared in Example 1 was tested, and the data are as follows:

[0068] Water tree test (0.1mol / L NaCl solution, 15d): 15d water tree performance requirements: water tree length ≤ 0.230mm, water tree relative length ≤ 40%.

[0069] Optical impurity content (pieces / kg): Sample belt detection (1kg): 75μm, number ≤8; d≥100μm, none.

[0070] Cable anti-water tree performance: Cable power frequency step-by-step breakdown test after 365-day accelerated water tree aging test: Insulation withstand power frequency voltage breakdown strength ≥30kV / mm.

[0071] Partial discharge test: Under 1.75U0, partial discharge ≤4.0pC.

[0072] Power frequency withstand voltage: Apply 2.5U0 for 30 minutes, and the insulation should not be broken down.

[0073] Insulation eccentricity: ≤4.7%.

[0074] Water tree resistance (after 365 days of accelerated water tree aging test) (test standard: CIGRE TB 722):

[0075] a. Partial discharge at 1.75U0 ≤ 4.2pC;

[0076] b. Insulation withstand power frequency voltage breakdown strength ≥ 30kV / mm;

[0077] c. Insulation withstand lightning impulse strength ≥60kV / mm.

[0078] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A 110kV water-tree resistant cross-linked polyethylene insulated power cable, characterized in that: The 110kV water-tree resistant cross-linked polyethylene insulated power cable comprises a conductor, which is provided with a conductor shielding layer, an insulating layer, an insulating shielding layer, a wrapping layer, a metal shielding layer, a metal shielding wrapping layer, an outer sheath and a semi-conductive layer in sequence from the inside to the outside; wherein the insulating layer is made of extruded water-tree resistant improved XLPE insulating material.

2. A 110kV water-tree resistant cross-linked polyethylene insulated power cable according to claim 1, characterized in that: The conductor is copper.

3. A 110kV water-tree resistant cross-linked polyethylene insulated power cable according to claim 1, characterized in that: The raw materials of the water-tree-resistant improved XLPE insulating material include, by weight: 90-95 parts of low-density polyethylene, 0.3-3 parts of polyethylene glycol, 1-5 parts of a compatibilizer ethylene-acrylic acid copolymer, 0.1-0.3 parts of a light stabilizer 4050H, 1.4-2.5 parts of a cross-linking agent diisopropyl peroxide, 0.1-0.5 parts of a co-cross-linking agent triallyl isocyanurate and 0.1-0.4 parts of an antioxidant.

4. A 110kV water-tree resistant cross-linked polyethylene insulated power cable according to claim 3, characterized in that: The water-tree-resistant improved XLPE insulating material is prepared by the following method: adding the remaining components except the cross-linking agent and the auxiliary cross-linking agent into a twin-screw extruder for mixing, extruding and granulating; after mixing the cross-linking agent and the auxiliary cross-linking agent, post-absorbing is performed to obtain the water-tree-resistant improved XLPE insulating material.

5. A 110kV water-tree resistant cross-linked polyethylene insulated power cable according to claim 4, characterized in that: The mixing temperature is 85-200°C.

6. A 110kV water-tree resistant cross-linked polyethylene insulated power cable according to claim 4, characterized in that: The absorption temperature is 60-80℃ and the absorption time is 12-24h.

7. A 110kV water-tree resistant cross-linked polyethylene insulated power cable according to claim 1, characterized in that: The metal shielding layer is made of copper wire.

8. A 110kV water-tree resistant cross-linked polyethylene insulated power cable according to claim 1, characterized in that: The wrapping layer is made of semi-conductive nylon tape and non-woven fabric.

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