Water-tree-resistant ultrahigh-voltage power cable

Abstract

The invention discloses a water-tree-resistant ultra-high-voltage power cable which comprises a water-blocking conductor, an insulation shielding layer, a metal water-blocking layer and an outer protective layer which are sequentially arranged from inside to outside in a wrapping mode, and the insulation shielding layer comprises a wrapping conductor shielding layer, an extruded conductor shielding layer, an extruded insulation layer and an extruded insulation shielding layer which are sequentially arranged from inside to outside. The metal water-blocking layer comprises a longitudinal water-blocking layer, a metal shielding layer, a metal binding layer, a shielding wrapping layer and a radial water-blocking layer which are sequentially arranged from inside to outside, the water-blocking conductor comprises a plurality of stranded conductor units, the outer side of each conductor unit is provided with a longitudinal wrapping double-sided insulating water-blocking tape, water-blocking powder is filled among the conductor units, and the longitudinal wrapping double-sided insulating water-blocking tape is provided with a longitudinal wrapping double-sided insulating water-blocking tape. And the outer protective layer is formed by high-density polyethylene and a wear-resistant anti-termite nylon sheath through double-layer co-extrusion. The method has the advantages that water trees are reduced, the reliability and the long service life of the ultrahigh-voltage power cable are guaranteed, and the transverse size of the ultrahigh-voltage cable is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power cables, and in particular to an anti-water-tree ultra-high voltage power cable. Background Art

[0002] As an important part of power transmission, the safety and reliability of power cables are crucial to the stable operation of power systems. During the use of power cables, water trees are easily formed in the cable insulation layer due to factors such as environmental humidity and temperature changes. Water trees are a tree-like structure formed in the cable insulation layer due to water penetration and electric field action, and are one of the main causes of cable insulation performance degradation and failure.

[0003] As the main power source for power transmission, the safety and reliability of ultra-high voltage power cables are very important. Ordinary cross-linked polyethylene (XLPE) insulated cables have excellent electrical insulation performance in dry environments, but in actual applications, the cable laying environment is usually harsh, and the cables often need to be immersed in water for a short or long time, or in environments with high humidity such as southern my country or coastal areas. After long-term use, water trees are easily generated, which eventually turn into electrical trees and cause insulation breakdown, greatly reducing their lifespan, which will bring huge economic losses and safety hazards.

[0004] In addition, in the prior art, the voltage level of ultra-high voltage cables is generally 110kV and above, and a corrugated aluminum sheath structure is often used. The cable has a large outer diameter, a high cost, and poor waterproofing ability.

[0005] Therefore, it is necessary to design a water-tree-resistant ultra-high voltage power cable with smaller lateral dimensions. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides an anti-water-tree ultra-high voltage power cable, which reduces water tree formation, ensures the reliability and long life of the ultra-high voltage power cable, and reduces the lateral size of the ultra-high voltage cable.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: A water-tree resistant ultra-high voltage power cable comprises a water-blocking conductor, an insulating shielding layer, a metal water-blocking layer and an outer sheath which are sequentially coated from the inside to the outside, the insulating shielding layer comprises a wrapped conductor shielding layer, an extruded conductor shielding layer, an extruded insulating layer and an extruded insulating shielding layer which are sequentially coated from the inside to the outside, the metal water-blocking layer comprises a longitudinal water-blocking layer, a metal shielding layer, a metal binding layer, a shielding wrapped layer and a radial water-blocking layer which are sequentially coated from the inside to the outside, the water-blocking conductor comprises a plurality of twisted conductor units, each conductor unit is provided with a longitudinally wrapped double-sided insulating water-blocking tape on the outside, the conductor units are filled with water-blocking powder, and the outer sheath is made of double-layer co-extrusion of high-density polyethylene and wear-resistant and anti-ant nylon sheath.

[0008] The water-blocking conductor is matched with the insulating shielding layer, the metal water-blocking layer and the outer sheath to form a fully water-blocking structure, which improves the reliability of the cable. The outer sheath is made of a double-layer co-extruded high-density polyethylene and a wear-resistant anti-ant nylon sheath, which can inhibit or delay the formation of water trees, reduce water trees caused by long-term operation of the cable, and extend the service life of the ultra-high voltage cable in areas with high incidence of ant damage, thus ensuring high reliability and long-life ultra-high voltage cable operation conditions in many aspects. In the prior art, ultra-high voltage cables often use corrugated aluminum sheaths, and the outer diameter of the cable is relatively large. The metal water-blocking layer used in the present invention includes a metal shielding layer, a metal binding layer, a shielding wrapping layer and a radial water-blocking layer, which can continuously bind each layer, thereby reducing the outer diameter of the cable and reducing costs.

[0009] Preferably, the shielding layer of the wrapped conductor is a plurality of water-blocking tape layers and nylon tape layers. The nylon layer and the water-blocking tape layer cooperate to achieve complete water blocking of the conductor. When the cable changes from a cold state to a hot state, the expansion between the conductor units due to the increase in temperature will have an uncontrollable adverse effect on the performance of the power cable. The nylon material of the nylon layer has a certain elasticity, which can cooperate with the thermal expansion of the water-blocking conductor when in use, and provide a margin for expansion buffering.

[0010] Preferably, the extruded conductor shielding layer is made of a semi-conductive shielding material; the extruded insulation layer is made of a water-tree resistant cross-linked polyethylene insulation material; the extruded insulation shielding layer is made of a semi-conductive shielding material, and the extruded conductor shielding layer, the extruded insulation layer and the extruded insulation shielding layer are a three-layer co-extrusion structure. The extruded conductor shielding layer and the extruded insulation shielding layer can balance the electric field of the cable and avoid partial discharge of the cable. The extruded insulation layer is arranged on the basis of the outer sheath to further effectively inhibit the formation of water trees.

[0011] Preferably, the longitudinal water-blocking layer is formed by wrapping a plurality of layers of semi-conductive water-blocking tapes. The longitudinal water-blocking layer cooperates with the radial water-blocking layer to enhance the longitudinal water-blocking capability of the cable.

[0012] Preferably, the metal shielding layer is a copper wire shielding layer with a gap of less than 4 mm, so as to improve the electromagnetic shielding performance of the cable.

[0013] Preferably, the metal binding layer is a spiral copper tape binding a copper wire shielding layer, which plays a role in constricting the lateral dimension of the cable and enhancing the structural stability of the cable.

[0014] Preferably, the shielding wrapping layer is made of super absorbent water-blocking yarn and water-blocking tape wrapped in overlapping layers. By wrapping the super absorbent water-blocking yarn and water-blocking tape and longitudinally wrapping the double-sided aluminum-plastic composite tape, a full-face water-blocking effect in the longitudinal and radial directions is achieved, thereby improving the water-blocking performance of the cable.

[0015] Preferably, the radial water-blocking layer is a longitudinally wrapped double-sided aluminum-plastic composite tape structure, which further enhances the radial water-blocking capability of the cable.

[0016] Preferably, a graphite layer is provided on the surface of the outer sheath to improve the wear resistance of the outer sheath and avoid partial discharge on the cable surface.

[0017] Preferably, the thickness of the extruded insulating layer is greater than the sum of the thickness of the extruded conductor shielding layer and the thickness of the extruded insulating shielding layer, the thickness of the insulating shielding layer is greater than the thickness of the metal water-blocking layer, and the thickness of the insulating shielding layer is greater than 1 / 3 of the radius of the water-blocking conductor and less than 1 / 2 of the radius of the water-blocking conductor. The extruded insulating layer is made of water-tree resistant cross-linked polyethylene insulating material, and has reliable insulation and shielding effects. The thickness of the extruded insulating layer is selected to ensure reliable coating of the water-blocking conductor, and can also be used as a reference to facilitate thickness control of the metal water-blocking layer and the outer sheath layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a water-tree resistant ultra-high voltage power cable proposed in one embodiment of the present invention.

[0019] In the figure: water-blocking conductor 1, wrapped conductor shielding layer 2, extruded conductor shielding layer 3, extruded insulation layer 4, extruded insulation shielding layer 5, longitudinal water-blocking layer 6, metal shielding layer 7, metal binding layer 8, shielding wrapping layer 9, radial water-blocking layer 10, outer sheath 11. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0021] An embodiment of the present invention provides an anti-water tree ultra-high voltage power cable, such as Figure 1 As shown, it includes a water-blocking conductor 1, an insulating shielding layer, a metal water-blocking layer and an outer protective layer 11 which are sequentially wrapped from the inside to the outside.

[0022] The water-blocking conductor 1 includes a plurality of twisted conductor units, each of which is provided with a longitudinally wrapped double-sided insulating water-blocking tape on the outside, and the conductor units are filled with water-blocking powder. The plurality of conductor units are distributed in a plurality of concentric circles from the axis of the power cable outward, and each layer is longitudinally wrapped with a double-sided insulating water-blocking tape. The water-blocking conductor 1 itself has a certain water-blocking ability.

[0023] The insulating shielding layer includes a wrapped conductor shielding layer 2, an extruded conductor shielding layer 3, an extruded insulating layer 4 and an extruded insulating shielding layer 5 which are arranged in sequence from the inside to the outside. The wrapped conductor shielding layer 2 includes several layers of water-blocking tape layers and several layers of nylon tape layers wrapped around the outside of the water-blocking conductor 1. The extruded conductor shielding layer 3 is made of a semi-conductive shielding material; the extruded insulating layer 4 is made of a water-tree resistant cross-linked polyethylene insulating material; the extruded insulating shielding layer 5 is made of a semi-conductive shielding material, and the surface of the semi-conductive shielding material is smooth after extrusion molding. The extruded conductor shielding layer 3, the extruded insulating layer 4 and the extruded insulating shielding layer 5 are a three-layer co-extrusion structure. That is, after the wrapped conductor shielding layer 2 is wrapped around the outside of the water-blocking conductor 1, the extruded conductor shielding layer 3, the extruded insulating layer 4 and the extruded insulating shielding layer 5 are formed on the outside of the wrapped conductor shielding layer 2 in a three-layer co-extrusion manner. The molding efficiency is high, and the reliability of the wrapped conductor shielding layer 2 on the surface of the water-blocking conductor 1 can be ensured.

[0024] The metal water-blocking layer includes a longitudinal water-blocking layer 6, a metal shielding layer 7, a metal binding layer 8, a shielding wrapping layer 9 and a radial water-blocking layer 10 which are arranged in sequence from the inside to the outside. The longitudinal water-blocking layer 6 is composed of several layers of semi-conductive water-resistant tapes. The metal shielding layer 7 is a copper wire shielding layer with a gap of less than 4 mm. The metal binding layer 8 is a copper wire shielding layer bundled with a spiral copper tape. The shielding wrapping layer 9 is made of a highly absorbent water-blocking yarn and a water-blocking tape that are overlapped and wrapped. The longitudinal water-blocking layer 6, the metal shielding layer 7, the metal binding layer 8, the shielding wrapping layer 9 and the radial water-blocking layer 10 are arranged in sequence outside the insulating shielding layer. The metal water-blocking layer not only provides a water-blocking effect, but also enhances the strength of the power cable through the metal shielding layer 7 and the metal binding layer 8, and plays the role of a metal shield. In addition, the two metal layers can converge the lateral dimensions of the power cable and reduce the volume of the cable.

[0025] The outer sheath 11 is made of a double-layer co-extrusion of high-density polyethylene and a wear-resistant and anti-ant nylon sheath. The surface of the outer sheath is coated with a semi-conductive graphite layer.

[0026] In the present application, the water-blocking conductor 1 cooperates with the insulating shielding layer, the metal water-blocking layer and the outer sheath 11 to form a fully water-blocking structure, which can improve the reliability of the cable. The outer sheath 11 is made of a double-layer co-extruded high-density polyethylene and a wear-resistant anti-ant nylon sheath, which can inhibit or delay the formation of water trees, reduce the water tree branches caused by long-term operation of the cable, and extend the service life of the ultra-high voltage cable in areas with high incidence of ant damage, thereby ensuring high reliability and long-life ultra-high voltage cable operation conditions in many aspects. Ultra-high voltage cables in the prior art often use corrugated aluminum sheaths, and the outer diameter of the cable is relatively large. The metal water-blocking layer used in the present invention includes a metal shielding layer 7, a metal binding layer 8, a shielding wrapping layer 9 and a radial water-blocking layer 10, which can play a role in continuously tightening each layer, thereby reducing the outer diameter of the cable and reducing the cost of the cable.

[0027] like Figure 1As shown, the thickness of the extruded insulating layer 4 is greater than the sum of the thickness of the extruded conductor shielding layer 3 and the thickness of the extruded insulating shielding layer 5, the thickness of the insulating shielding layer is greater than the thickness of the metal water-blocking layer, and the thickness of the insulating shielding layer is greater than 1 / 3 of the radius of the water-blocking conductor 1 and less than 1 / 2 of the radius of the water-blocking conductor 1. The thickness of the outer sheath is close to the thickness of the metal water-blocking layer. The specific ratio of the thickness of each layer relative to the radius of the water-blocking conductor 1 can refer to the lateral dimension ratio of each layer in the attached figure. The extruded insulating layer 4 is made of water-tree resistant cross-linked polyethylene insulation material, and the insulation and shielding effects are reliable. The thickness of the extruded insulating layer 4 can ensure the reliable coating of the water-blocking conductor 1, and can also be used as a reference to facilitate the thickness control of the metal water-blocking layer and the outer sheath.

Claims

1. A water-tree resistant ultra-high voltage power cable, characterized in that: It includes a water-blocking conductor, an insulating shielding layer, a metal water-blocking layer and an outer sheath which are sequentially wrapped from the inside to the outside. The insulating shielding layer includes a wrapped conductor shielding layer, an extruded conductor shielding layer, an extruded insulating layer and an extruded insulating shielding layer which are sequentially arranged from the inside to the outside. The metal water-blocking layer includes a longitudinal water-blocking layer, a metal shielding layer, a metal binding layer, a shielding wrapping layer and a radial water-blocking layer which are sequentially arranged from the inside to the outside. The water-blocking conductor includes a plurality of twisted conductor units. A longitudinally wrapped double-sided insulating water-blocking tape is provided on the outside of each conductor unit. Water-blocking powder is filled between the conductor units. The outer sheath is made of double-layer co-extrusion of high-density polyethylene and wear-resistant and ant-proof nylon sheath.

2. The water-tree resistant ultra-high voltage power cable according to claim 1, characterized in that: The wrapped conductor shielding layer comprises several layers of water blocking tape and nylon tape.

3. The water-tree resistant ultra-high voltage power cable according to claim 1 is characterized in that: The extruded conductor shielding layer is made of semi-conductive shielding material; the extruded insulating layer is made of water-tree resistant cross-linked polyethylene insulating material; the extruded insulating shielding layer is made of semi-conductive shielding material, and the extruded conductor shielding layer, the extruded insulating layer and the extruded insulating shielding layer are a three-layer co-extruded structure.

4. The water-tree resistant ultra-high voltage power cable according to claim 1, characterized in that: The longitudinal water-blocking layer is formed by wrapping a plurality of layers of semi-conductive water-blocking tapes.

5. The water-tree resistant ultra-high voltage power cable according to claim 1, characterized in that: The metal shielding layer is a copper wire shielding layer with a gap less than 4mm.

6. The water-tree resistant ultra-high voltage power cable according to claim 1, characterized in that: The metal binding layer is a spiral copper tape-bound copper wire shielding layer.

7. The water-tree resistant ultra-high voltage power cable according to claim 1, characterized in that: The shielding wrapping layer is made of super absorbent water-blocking yarn and water-blocking tape wrapped in an overlapping manner.

8. The water-tree resistant ultra-high voltage power cable according to claim 3 is characterized in that: The radial water-blocking layer is a longitudinally wrapped double-sided aluminum-plastic composite tape structure.

9. The water-tree resistant ultra-high voltage power cable according to any one of claims 1 to 7, characterized in that: A graphite layer is provided on the surface of the outer sheath.

10. The water-tree resistant ultra-high voltage power cable according to claim 3, characterized in that: The thickness of the extruded insulating layer is greater than the sum of the thickness of the extruded conductor shielding layer and the thickness of the extruded insulating shielding layer, the thickness of the insulating shielding layer is greater than the thickness of the metal water-blocking layer, and the thickness of the insulating shielding layer is greater than 1 / 3 of the radius of the water-blocking conductor and less than 1 / 2 of the radius of the water-blocking conductor.

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