CN112466545B - High-voltage direct-current cable for high-speed rail traction locomotive and preparation method thereof - Google Patents
High-voltage direct-current cable for high-speed rail traction locomotive and preparation method thereof Download PDFInfo
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- CN112466545B CN112466545B CN202011345697.8A CN202011345697A CN112466545B CN 112466545 B CN112466545 B CN 112466545B CN 202011345697 A CN202011345697 A CN 202011345697A CN 112466545 B CN112466545 B CN 112466545B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B7/00—Insulated conductors or cables characterised by their form
- H01B7/42—Insulated conductors or cables characterised by their form with arrangements for heat dissipation or conduction
- H01B7/428—Heat conduction
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
- H01B13/06—Insulating conductors or cables
- H01B13/14—Insulating conductors or cables by extrusion
- H01B13/148—Selection of the insulating material therefor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
- H01B13/22—Sheathing; Armouring; Screening; Applying other protective layers
- H01B13/24—Sheathing; Armouring; Screening; Applying other protective layers by extrusion
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
- H01B13/22—Sheathing; Armouring; Screening; Applying other protective layers
- H01B13/26—Sheathing; Armouring; Screening; Applying other protective layers by winding, braiding or longitudinal lapping
- H01B13/2613—Sheathing; Armouring; Screening; Applying other protective layers by winding, braiding or longitudinal lapping by longitudinal lapping
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B7/00—Insulated conductors or cables characterised by their form
- H01B7/42—Insulated conductors or cables characterised by their form with arrangements for heat dissipation or conduction
- H01B7/421—Insulated conductors or cables characterised by their form with arrangements for heat dissipation or conduction for heat dissipation
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Abstract
A high-voltage direct-current cable for a high-speed rail traction locomotive comprises a conductor core (10), an insulating filler layer (20), a functional shielding layer (30) and a functional sheath layer (40) which are arranged in sequence from inside to outside; the cooling layer (50) is arranged between the functional shielding layer (30) and the functional sheath layer (40); the bottom surface of the foam metal spiral belt (60) contacts any layer of the functional shielding layer (30) in a low-heat resistance mode and is spirally arranged outside the layer coaxially, when the coextrusion process is carried out, the lower portion of the foam metal spiral belt (60) is filled with a molten material of the cooling layer to be combined with the layer, and the upper portion of the foam metal spiral belt is filled with a molten material of the functional sheath layer (40) to enable the top surface of the foam metal spiral belt (60) to coincide with the outer curved surface of the functional sheath layer (40). The high-voltage direct-current cable for the high-speed rail traction locomotive greatly increases the heat dissipation capacity.
Description
Technical Field
The invention relates to the technical field of power cables, in particular to a high-voltage direct-current cable for a high-speed rail traction locomotive and a preparation method thereof.
Background
Cables for railways, subways and high-speed railways are divided into four main categories according to the application: cables for tractors, cables for communication equipment, cables for vehicle electrical parts, and cables for station platform electrical parts. The cable for the high-speed rail traction locomotive has high technical requirements, and the 30kV single-phase power cable for the locomotive is mainly used for connecting high-voltage equipment such as a pantograph, a main circuit breaker, a traction transformer and the like inside and outside the traction locomotive to transmit electric energy for power supply equipment of the traction locomotive. The cable has a severe use environment, and has the characteristics of environmental protection, high safety, oil resistance, acid and alkali corrosion resistance, ozone resistance, moisture resistance, sunlight resistance, impact resistance, high temperature resistance and the like.
The high-speed rail high-voltage direct-current cable in the prior art mainly has the problem of temperature gradient effect. In the working condition operation process, the inner conductor of the direct-current high-voltage cable can generate large heat, and due to the coating effect of the insulating layer on the inner conductor, the self heat-conducting property of the insulating layer and other problems, the insulating layer has large temperature difference from inside to outside, and a non-uniform temperature field is formed inside the cable insulating material. If the dc conductivity of the insulating material is greatly affected by temperature, a non-uniform temperature field will cause the spatial distribution of the conductivity within the insulating material to vary by up to about 3 orders of magnitude, thereby causing distortion of the electric field and even reversal of the polarity of the electric field. The distribution of electric fields in the insulating layer of the XLPE insulated high-voltage insulated cable is related to the temperature gradient of the insulating layer, and the temperature gradient of the insulating layer directly influences the insulation state and the service life of the cable. Therefore, the cable should be concerned not only with conductor temperature, but also with insulation layer temperature gradients.
The key point for solving the temperature gradient effect of the insulating layer is to improve the heat-conducting property of the insulating material, and the method which is most applied by researchers at home and abroad at present is to dope nanoparticles with high heat conductivity (such as SiC, MgO and the like) in the insulating material.
Insulating filler for cable disclosed by Wuhu space special cable plant GmbH and preparation method thereofCN108623841 A20181009) Mixing activated carbon, chitosan and hydrogen fluoride, drying and calcining to obtain fluorine-doped carbon; 2) mixing and grinding mica powder, the fluorine-doped carbon, the white carbon black, the ceramic fiber, the boron nitride and the aluminum nitride, and then carrying out heat treatment. The insulating filler for the cable is used as a preparation raw material of the insulating sheath of the point cable, and can improve the insulating property, the heat conducting property and the mechanical property of the prepared cable sheath. The prepared insulating filler for cables a1-A3 gave only tensile strength after aging and gave no relative data on the improvement of thermal conductivity.
How to enable the conductor and the cable insulating filler to have improved heat conductivity and better softness while not reducing the dielectric property of the insulating filler is a key technical problem in the field of high-voltage direct-current cables.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a high-voltage direct-current cable for a high-speed rail traction locomotive and a preparation method thereof, and solves the heat conduction problem of conductors and insulating fillers.
The high-voltage direct-current cable for the high-speed rail traction locomotive comprises a conductor core, an insulating filler layer, a functional shielding layer and a functional sheath layer which are sequentially arranged from inside to outside;
the cooling layer is arranged between the functional shielding layer and the functional sheath layer and is used for absorbing heat of the conductor core and the insulating filler layer; the cooling layer and the functional sheath layer are formed by extrusion through a multi-layer co-extrusion process;
the bottom surface of the foam metal spiral belt contacts any layer of the functional shielding layer in a low-thermal resistance manner and is coaxially and spirally arranged outside the layer, when the co-extrusion process is used for extrusion, the lower part of the foam metal spiral belt is filled with the molten material of the cooling layer and is combined with the layer, and the upper part of the foam metal spiral belt is filled with the molten material of the functional sheath layer, so that the top surface of the foam metal spiral belt is coincided with the outer curved surface of the functional sheath layer.
Furthermore, the insulating filler layer is formed by mixing XLPE insulating filler into a non-metal network section, and nano non-metal heat conduction particles are sprayed on the surface of the non-metal network section.
Further, the functional shielding layer sequentially comprises a metal shielding layer, a wrapping waterproof belt, an aluminum-plastic composite belt, a high-flame-retardant belt and an optional copper strip armor from inside to outside, and the functional shielding layer is formed by a wrapping process; when the bottom surface of the foam metal spiral belt is bonded to any layer of the functional shielding layer through the heat-conducting polymer, a subsequent layer needing to be wrapped is lapped with the foam metal spiral belt and is simultaneously wrapped and formed, the cooling layer and the functional sheath layer are formed by extrusion through a multi-layer co-extrusion process, and the foam metal spiral belt is successively filled in the cooling layer and the functional sheath layer.
Furthermore, the foam metal spiral belt comprises a plurality of sections of foam metal spiral sections which are arranged end to end at intervals, and the bottom surfaces of the foam metal spiral sections are respectively bonded to the base fabric which is impregnated with the heat-conducting glue.
Further, the non-metallic vegetable sponge section (21) is a loofah sponge fiber section, and the loofah sponge fiber section is extracted from an air-dried loofah sac and cut into short fiber sections with the length of 3-5 mm; the non-metal network section is mixed with the insulating filler layer, and the mixing proportion of the non-metal network section is 5-10 wt%.
Further, the cooling layer is a high thermal conductivity polymer matrix composite material, and the thermal conductivity lambda of the high thermal conductivity polymer matrix composite material is greater than 2.5W/(m.K).
Further, the foam metal spiral belt is open-cell foam copper and aluminum, and the cell density is 80-10 PPI; the width of the foam metal spiral belt is 3-15mm, and the wrapping pitch is 15-65 mm.
And the second cooling layer is co-extruded with the functional sheath layer and the cooling layer, and is combined with the top curved surface of the foamed metal spiral belt.
A manufacturing method of the high-voltage direct-current cable for the high-speed rail traction locomotive,
the method comprises the following steps:
1) conductor core made by winding conductor petals
a, a conductor segment, a plurality of copper conductor stranding machines are stranded into one strand, and the strand passes through a compacting die with a certain cross section shape to be extruded with a semi-conductive composite layer to form the conductor segment;
b, winding to form a conductor core, and twisting at least 3 conductor petals, clamping the inner core body, and winding to form a mica tape to be tightly bound into a circular section with a certain outer diameter;
2) extruded insulation packing layer
a preparing the heat-conducting fiber,
extracting plant fiber, cutting into non-metal network segments, spraying nanometer conductive particles, and drying;
b, preparing heat-conducting insulating filler, mixing 5-10 wt% of non-metallic net segment with XLPE insulating filler, and uniformly mixing to obtain the heat-conducting insulating filler;
c, extruding an insulating filler layer, penetrating a conductor core into an extrusion type mold core, feeding the heat-conducting insulating filler into an extruder, and continuously compressing and extruding the melted heat-conducting insulating filler into an annular cavity between a mold sleeve and the mold core to form the insulating filler layer;
3) wrapping function shielding layer
Each layer of the functional shielding layer is sequentially wrapped outside the insulating filler layer;
4) wrapped foam metal spiral belt
Wrapping the foamed metal spiral belt to the outside of the functional shielding layer to obtain a co-extruded cable core;
5) co-extrusion of cooling layer and functional sheath layer
The center of a mold core of the extrusion type mold is penetrated with the co-extrusion cable core, and a cooling layer and a functional sheath layer are sequentially extruded and coated outside the co-extrusion cable core;
6) degassing, and putting the whole section of cable into a constant temperature oven at 70 ℃ for 170-200h to obtain the high-voltage direct-current cable for the high-speed rail traction locomotive.
Further, the inner core body is an insulating rope, and the insulating rope is prepared by extruding and molding water-absorbing polyurethane foam into a cylinder shape and curing for 1h at 120 ℃.
The high-voltage direct-current cable for the high-speed rail traction locomotive is provided with the cooling structure consisting of the cooling layer and the foam metal spiral belt, and the insulating filler layer is mixed with the heat conducting fibers, so that the heat dissipation capacity is greatly increased, compared with a commercial high-voltage direct-current XLPE insulating cable of the same model without the structure, in a 24-hour continuous power transmission test, the temperatures of the conductor and the insulating filler layer are respectively reduced by 27% and 35%, and the rated unit area current-carrying capacity of the high-voltage direct-current cable and the laid environmental temperature requirement are greatly increased.
Drawings
Fig. 1 is a front sectional view of a first embodiment of a high voltage dc cable for a high speed railway traction vehicle according to the present invention.
Fig. 2 is a top view of a first embodiment of the high voltage dc cable for a high speed rail traction vehicle according to the present invention.
Fig. 3 is a partially enlarged view of a first embodiment of the high-voltage direct-current cable for the high-speed rail traction locomotive.
Fig. 4 is a partially enlarged view of a second embodiment of the intumescent flame retardant power cable of the invention.
Reference numerals in the above figures:
10 conductor core, 11 conductor lobe, 12 inner core body and 13 synthetic mica tape
20 insulating filler layer, 21 non-metallic segment, 22 arc groove and 23 temperature measuring optical fiber
30 functional shielding layers, 31 metal shielding layers, 32 wrapped waterproof tapes, 33 aluminum-plastic composite tapes, 34 copper tape armors and 35 high-flame-retardant wrapping tapes
40 functional sheath layers, 41 polyolefin inner sheaths and 42 low-smoke halogen-free flame-retardant polyolefin outer sheaths
50 cooling layer, 51 second cooling layer, 60 metal foam spiral belt
Detailed Description
The following detailed description of the embodiments of the present invention is provided in connection with the accompanying drawings, but is not intended to limit the scope of the invention.
Example 1
A high-voltage direct-current cable for a high-speed rail traction locomotive is an extension body with a cross section extending along a central axis A, wherein the cross section is circular, rectangular or square. Including conductor core 10, insulating packing layer 20, function shielding layer 30 and function restrictive coating 40, be equipped with cooling layer 50 between function shielding layer 30 and function restrictive coating 40, cooling layer 50 and function restrictive coating 40 adopt the crowded package shaping of multilayer crowded technology altogether, and during crowded package altogether, place cooling layer 50 and function restrictive coating 40 in foam metal spiral strip 60 places simultaneously in, foam metal spiral strip top surface and function restrictive coating top surface are equal.
The conductor core 10 comprises at least 3 fan-shaped conductor petals 11, a central clamp inner core body 12, a mica tape 13, a circular cross section and a conductor shielding layer 13, wherein the inner core body 12 is twisted and wound to form a mica tape, and the mica tape is tightly bound to the circular cross section with a certain outer diameter; and the conductor shielding layer 13, the insulating filler layer 20 and the cooling layer 30 are co-extruded. The conductor lobe 11 is a 0.3-0.5mm tinned copper wire stranded drawing process, is tightly pressed into a sector section and is extruded with a semi-conductive composite layer. The conductor compression coefficient reaches over 0.9. The thickness of the semiconductive composite layer is 0.6-0.8 mm;
if the high voltage dc cable is buried in a laying groove in the ground, the inner core 12 is an insulation rope provided for the purpose of reducing the amount of water transferred from the divided conductor to the insulation layer, suppressing the generation of voids and water trees in the insulation layer, and maintaining stable insulation performance for a long time. The insulating rope is made of water-absorbing polyurethane foam, is extruded into a cylinder shape and is cured for 1 hour at 120 ℃.
If the high voltage dc cable is erected at a high place, the inner core body 12 is a steel wire for providing high elastic support for the erection of the cable.
The insulating filler layer 20 is formed by mixing XLPE insulating filler into a non-metallic network section 21, and nano heat conduction particles SiC are sprayed on the surface of the non-metallic network section 21. The non-metallic vegetable sponge section 21 is made of plant fiber, and the plant fiber is loofah sponge fiber. The thickness of the insulating filler layer 20 can not be less than 4.5mm, and the insulating eccentricity is not more than 10%.
The extrusion wrapping method of the insulating filler layer 20 comprises the following steps:
1) making loofah sponge skeleton
Airing the loofah to obtain loofah sponge, extracting loofah sponge fibers from the loofah sponge, and cutting into short fiber sections with the length of 3-5 mm;
2) spraying nanometer heat conducting particles on the surface of the short fiber segment of the loofah sponge to prepare a non-metal sponge segment 21;
3) mixing the non-metal segment 21 into the insulating filler layer 20, wherein the mixing proportion is 5-10 wt%;
4) extruding and wrapping an insulating filler layer;
the insulating and shielding layer 21 is extruded outside the insulating and filling layer 20 to ensure gapless water-proof and moisture-proof in the production process.
The functional shielding layer 30 comprises a metal shielding layer 31, a wrapping waterproof tape 32, an aluminum-plastic composite tape 33, a copper tape armor 34 and a high-flame-retardant wrapping tape 35, and the functional shielding layer 30 is a wrapping process. The metal shielding layer 31 is required to be wrapped by a copper strip gap with the thickness of two layers of 0.1mm and the width of 40mm because the cable adopts an arc suppression coil grounding system and the grounding fault current is large.
The functional sheath layer 40 is a low-smoke halogen-free flame-retardant polyolefin outer sheath 42, and a polyolefin inner sheath 41 is optionally arranged in the outer sheath 42, so that the cost can be saved.
The cooling layer 50 is a heat-conducting polymer matrix composite material with the heat conductivity lambda > 2.5W/(m.K), high-heat-conducting nano-particles are added into a thermoplastic polymer resin base material, and the high-heat-conducting nano-particles comprise metals (Ag, Cu, Al and the like), non-metal simple substances (graphite, carbon fibers, CNT and the like), oxides (BeO, Al2O3, TiO2 and the like) and other binary compounds (such as SiC, AlN, BN and the like); PE (polyethylene), polypropylene (PP) and PA (polyimide) are used as polymer matrix materials; preferably, the graphene oxide nano sheet/silicone resin is selected, namely, more than 0.015 wt% of graphene oxide nano sheet is added into the silicone resin, and the thermal conductivity of the graphene oxide nano sheet/silicone resin reaches 2.758W/(m.K).
The foamed metal spiral belt 60 is open-cell foamed copper and aluminum, and the cell density is 80-10 PPI. The foam metal spiral belt 60 is matched with the cooling layer 50 to dissipate heat of the conductor core 10 and the insulating filler layer 30, the foam metal spiral belt comprises a plurality of sections of foam metal spiral sections which are arranged end to end at intervals, and the bottom surfaces of the foam metal spiral sections are respectively bonded to base fabrics impregnated with heat-conducting glue, so that the cable meets the bending radius standard.
By adopting the coextrusion process, the foam metal spiral belt 60, the cooling layer 50 and the cooling layer are integrally formed, and the interface thermal resistance between the foam metal spiral belt and the cooling layer is greatly reduced.
Regarding the test of the temperature of the high-voltage direct-current cable, a temperature measuring optical fiber 23 is arranged outside the conductor core 10 and/or the insulating packing layer 20 along the axis, specifically, an arc groove 22 is arranged on the outer circle of the insulating packing layer 20, and the temperature measuring optical fiber 23 is arranged in the arc groove 22 along the axis a and is used for detecting the temperature of the insulating packing layer 20. The temperature of the conductor can be obtained by a method of presumptive calculation without arranging a temperature measuring optical fiber outside the conductor core 10.
A method for manufacturing a high-voltage direct-current cable for a high-speed rail traction locomotive,
the method comprises the following steps:
1) conductor core made by winding conductor petals
a, a conductor segment, a plurality of copper conductor stranding machines are stranded into one strand, and a semi-conductive composite layer is extruded through a compaction die with a certain cross section shape to form a conductor segment (11);
b, wrapping to form a conductor core, and twisting at least 3 conductor petals (11) center clamp inner core bodies (12) and wrapping to form a mica tape (13) to be tightly bound to form a circular section with a certain outer diameter;
2) extruded insulation packing layer
a preparing the heat-conducting fiber,
extracting plant fiber, cutting into non-metal network segments, spraying nanometer conductive particles, and drying;
b, preparing heat-conducting insulating filler, mixing 5-10 wt% of non-metallic net segment with XLPE insulating filler, and uniformly mixing to obtain the heat-conducting insulating filler;
c, extruding an insulating filler layer, penetrating a conductor core into an extrusion type mold core, feeding the heat-conducting insulating filler into an extruder, and continuously compressing and extruding the melted heat-conducting insulating filler into an annular cavity between a mold sleeve and the mold core to form the insulating filler layer;
3) wrapping function shielding layer
Each layer of the functional shielding layer is sequentially wrapped outside the insulating filler layer;
4) wrapped foam metal spiral belt
Wrapping the foamed metal spiral belt (60) outside the functional shielding layer to obtain a co-extruded cable core;
5) co-extrusion of cooling layer and functional sheath layer
The center of a mold core of the extrusion type mold is penetrated with the co-extrusion cable core, and a cooling layer and a functional sheath layer are sequentially extruded and coated outside the co-extrusion cable core;
6) degassing, and putting the whole section of cable into a constant temperature oven at 70 ℃ for 170-plus-200 h to obtain the high-voltage direct-current cable for the high-speed rail traction locomotive.
Example 2
Because the function shielding layer 30 is a multi-layer wrapping process, the circuit wrapping layer is easy to loosen in the production process, an alternate structure of the wrapping process and the extrusion process is adopted, and other structures are the same as those in embodiment 1.
The utility model provides a high-voltage direct current cable for high-speed railway traction engine, function shielding layer 30, the range upon range of realization of cooling layer 50 and function restrictive coating 40 does, set up metallic shield 31 outside insulating packing layer 20, metallic shield 31 is outer to be wrapped around waterproofing area 32 and aluminium-plastic composite tape 33, then crowded package cooling layer 50, cooling layer 50 is outer to be wrapped around high fire-retardant band 34 of package and copper strips armor 35 simultaneously, set up foam metal spiral area 60 around the package interval, crowded package function restrictive coating 40 after the package is accomplished, during crowded package, foam metal spiral area 40 and cooling layer 50 combination are filled to function restrictive coating 40 molten material.
Or the extruded cooling layer 50 is directly arranged outside the metal shielding layer 31, the extruded cooling layer 50 is respectively wrapped with the water blocking tape 32, the aluminum-plastic composite tape 33, the high flame retardant wrapping tape 34 and the copper strip armor 35, and the foam metal spiral tapes 60 are arranged at intervals in the wrapping manner. The metal foam spiral tape 60 is filled with the functional sheathing layer 40 when the functional sheathing layer 40 is extruded.
In order to facilitate the simultaneous lapping of the foam metal spiral belt 60 and the functional shielding layer, the bottom of the foam metal spiral belt 60 is provided with a flange part of a thin layer, and the flange part is convenient to lap the functional shielding layer without a gap.
For the sake of the appearance of the cable, a second cooling layer 51 may be extruded outside the functional sheath layer 40, and the second cooling layer 51 is made of a heat conductive resin material. Or a black metal layer is electroplated on the top curved surface of the foam metal spiral belt 60 to form a spiral black belt with beautiful appearance, and actually, a smooth black metal plating layer is formed on the surface of the foam metal spiral belt 60 for dissipating heat.
In order to reduce the thermal resistance of the wrapping functional shielding layer, a layer of heat-conducting polymer with the heat conductivity lambda being more than 2.5W/(m.K) is roll-coated on the bottom surface of the functional shielding layer, and specifically is graphene oxide nanosheet/silicone resin.
Experimental data
Temperature measuring optical fibers 14 and 23 are respectively arranged on the surfaces of the conductor core 1 and the insulating filler layer 20 along an axis A, the high-voltage direct-current cable for the high-speed rail traction locomotive of the embodiment 1 is produced by adopting the structure size No. 1 of the following table 1, and the high-voltage direct-current cable for the high-speed rail traction locomotive of the embodiment 2 is produced by adopting the structure size No. 2 of the following table 1. No. 3 is a commercial XLPE insulated high voltage direct current cable of the same diameter without a cooling structure as a comparative example.
TABLE 11 # high-voltage DC cable construction size
| Name of structure | Knot outer diameter (mm)1# |
| |
13.25 |
| |
14.05 |
| XLPE insulating |
24.05 |
| |
26.05 |
| |
29.05 |
| |
39.05 |
TABLE 22 # HVDC Cable construction size
| Name of structure | Knot outer diameter (mm)2# |
| |
13.25 |
| |
14.05 |
| XLPE insulating |
24.05 |
| |
25.25 |
| |
28.25 |
| High |
29.05 |
| |
39.05 |
The temperature measurement and electrification test platform is constructed, the cable adopts XLPE insulated direct current land cable, and the sectional area of the cable conductor is 250mm2And the thickness of the insulating filler layer is 5 mm. 3 groups of polar direct current voltages are respectively 30KV, 75KV and 100KV, 24h load tests are carried out, the temperature is monitored and recorded every 2 hours at the room temperature of 25 ℃, and finally the average temperature is obtained, wherein the test results are shown in table 3.
TABLE 324 h average temperature distribution (. degree.C.) of cables for load test
Now, the high-voltage direct-current cable for the high-speed rail tractor according to the present invention is analyzed to solve the technical problem of how to make the conductor and the cable insulation filler have improved thermal conductivity and better softness without reducing the dielectric property of the insulation filler by the following means:
(1) heat radiation structure formed by cooling layer and foam metal spiral belt
And a cooling layer 50 is additionally arranged between the functional shielding layer 30 and the functional sheath layer 40, the cooling layer 50 absorbs the heat of the insulating filler layer and transmits the heat to the metal foam spiral belt 60, and the metal foam spiral belt 60 is dissipated from the surface of the functional sheath layer 40. The cooling layer combines the foam metal spiral strip, and the cooling layer absorbs heat from the whole external diameter of the function shielding layer 30 of cable to give foam metal spiral strip 60 with heat transfer, provide the heat dissipation route from inside to outside for the heat dissipation of high voltage direct current cable under the prerequisite of not losing cable integrality.
Since the foamed metal spiral tape 60 is filled with the molten material during the extrusion of the functional sheathing layer 40, the wrapping gaps of the functional shielding layer, such as the water blocking tape 32, the aluminum-plastic composite tape 33, the high flame retardant wrapping tape 34 and the copper tape armor 35 of example 2, are filled, and the function of the functional layer is not reduced.
For the functional shielding layer 30 of embodiment 1, the heat conducting capability of the functional shielding layer 30 outside the insulating filler layer 20 is reduced, but the thermal interface resistance between the cooling layer and the foamed metal spiral tape 60 is greatly reduced by the co-extrusion of the foamed metal spiral tape 60, the cooling layer and the functional sheath layer, and the heat dissipation function is not reduced.
(2) The insulating filler is mixed with heat-conducting fiber
In order to increase the heat conduction capability of the insulating filler layer, a non-metal network section 21 is mixed in the insulating filler layer, and nano heat conduction particles SiC are sprayed on the surface of the non-metal network section 21 to form heat conduction fibers. The heat conducting fiber is more directional than directly added heat conducting particles, and simultaneously, the fiber adopts plant fiber, especially cool plant fiber, such as loofah sponge fiber. The fiber is added, so that the strength of the insulating filler layer is increased, the heat conducting capability is enhanced, the heat conducting capability of the insulating filler is increased, and the heat generated by the conductor is more easily dissipated from the surface of the cable through the insulating filler layer, the cooling layer and the foam metal spiral band, thereby achieving three purposes.
The high-voltage direct-current cable for the high-speed rail traction locomotive is provided with the cooling structure consisting of the cooling layer and the foam metal spiral belt, and the insulating filler layer is mixed with the heat conducting fibers, so that the heat dissipation capacity is greatly increased, compared with a commercial high-voltage direct-current XLPE insulating cable of the same model without the structure, in a 24-hour continuous power transmission test, the temperatures of the conductor and the insulating filler layer are respectively reduced by 27% and 35%, and the rated unit area current-carrying capacity of the high-voltage direct-current cable and the laid environmental temperature requirement are greatly increased.
Claims (9)
1. A high-voltage direct-current cable for a high-speed rail traction locomotive is characterized by comprising a conductor core (10), an insulating filler layer (20), a functional shielding layer (30) and a functional sheath layer (40) which are arranged in sequence from inside to outside;
a cooling layer (50), the cooling layer (50) being arranged between the functional shielding layer (30) and the functional sheathing layer (40), the cooling layer (50) being used to absorb heat from the conductor core and the insulating filler layer (20); the cooling layer (50) and the functional sheath layer (40) are formed by extrusion through a multi-layer co-extrusion process;
the bottom surface of the foamed metal spiral belt (60) is in low-heat resistance contact with any layer of the functional shielding layer (30) and is coaxially and spirally arranged outside the layer, when the co-extrusion process is used for extrusion, the molten material of the cooling layer is filled to the lower part of the foamed metal spiral belt (60) to be combined with the layer, and the molten material of the functional sheath layer (40) is filled to the upper part of the foamed metal spiral belt to enable the top surface of the foamed metal spiral belt (60) to be superposed with the outer curved surface of the functional sheath layer (40);
the insulating filler layer (20) is formed by mixing XLPE insulating filler into a non-metallic network section (21), and nano heat conduction particles are sprayed on the surface of the non-metallic network section (21).
2. The high-voltage direct-current cable for the high-speed rail tractor is characterized in that the functional shielding layer (30) sequentially comprises a metal shielding layer (31), a wrapping waterproof tape (32), an aluminum-plastic composite tape (33), a high-flame-retardant wrapping tape (35) and an optional copper strip armor (34) from inside to outside, and the functional shielding layer (30) is formed by a wrapping process; when the bottom surface of the foam metal spiral belt (60) is bonded to any layer of the functional shielding layer (30) through the heat-conducting polymer, a subsequent layer needing to be wrapped is lapped with the foam metal spiral belt (60) and is simultaneously wrapped and formed, the cooling layer (50) and the functional sheath layer (40) are formed by extrusion coating through a multi-layer co-extrusion process, and the foam metal spiral belt (60) is successively filled in the cooling layer (50) and the functional sheath layer (40).
3. The high-voltage direct-current cable for high-speed rail tractors as claimed in claim 1, wherein the foamed metal spiral strip (60) comprises a plurality of foamed metal spiral sections arranged end to end at intervals, and the bottom surfaces of the foamed metal spiral sections are respectively bonded to the base fabric impregnated with the heat-conducting adhesive.
4. The high-voltage direct-current cable for the high-speed railway tractor according to claim 1, wherein the non-metallic vegetable sponge segment (21) is a vegetable sponge fiber segment, and the vegetable sponge fiber segment is extracted from dried vegetable sponge and cut into a short fiber segment with the length of 3-5 mm; the non-metal network section (21) is mixed with the insulating filler layer (20), and the mixing proportion of the non-metal network section (21) is 5-10 wt%.
5. The high-voltage direct current cable for high-speed rail tractors as claimed in claim 1, wherein the cooling layer (50) is a high-thermal conductivity polymer matrix composite material having a thermal conductivity λ > 2.5W/(m-K).
6. The high-voltage direct-current cable for high-speed rail tractors according to claim 1, wherein the foamed metal spiral tape (60) is open-cell type foamed copper, aluminum, with a cell density of 80-10 PPI; the width of the foam metal spiral belt (60) is 3-15mm, and the wrapping pitch is 15-65 mm.
7. The high-voltage direct-current cable for the high-speed rail traction locomotive according to claim 1, further comprising a second cooling layer (51) positioned outside the functional sheath layer (40), wherein the second cooling layer (51) is co-extruded with the functional sheath layer (40) and the cooling layer (50), and the second cooling layer (51) is combined with the top curved surface of the foamed metal spiral belt (60).
8. The method for manufacturing a high-voltage direct current cable for a high-speed railway traction locomotive according to any one of claims 1 to 7, comprising the following steps:
1) conductor core made by winding conductor petals
a, a conductor segment, a plurality of copper conductor stranding machines are stranded into one strand, and a semi-conductive composite layer is extruded through a compaction die with a certain cross section shape to form a conductor segment (11);
b, wrapping to form a conductor core, and twisting at least 3 conductor petals (11) center clamp inner core bodies (12) and wrapping to form a mica tape (13) to be tightly bound to form a circular section with a certain outer diameter;
2) extruded insulation packing layer
a preparing the heat-conducting fiber,
extracting plant fiber, cutting into non-metal network segments, spraying nanometer conductive particles, and drying;
b, preparing heat-conducting insulating filler, mixing 5-10 wt% of non-metallic net segment with XLPE insulating filler, and uniformly mixing to obtain the heat-conducting insulating filler;
c, extruding an insulating filler layer, penetrating a conductor core into an extrusion type mold core, feeding the heat-conducting insulating filler into an extruder, and continuously compressing and extruding the melted heat-conducting insulating filler into an annular cavity between a mold sleeve and the mold core to form the insulating filler layer;
3) wrapping function shielding layer
Each layer of the functional shielding layer is sequentially wrapped outside the insulating filler layer;
4) wrapped foam metal spiral belt
Wrapping the foamed metal spiral belt (60) outside the functional shielding layer to obtain a co-extruded cable core;
5) co-extrusion of cooling layer and functional sheath layer
The center of a mold core of the extrusion mold is penetrated through the co-extrusion cable core, and the cooling layer and the functional sheath layer are successively extruded and coated outside the co-extrusion cable core;
6) degassing, and putting the whole section of cable into a constant temperature oven at 70 ℃ for 170-plus-200 h to obtain the high-voltage direct-current cable for the high-speed rail traction locomotive.
9. The manufacturing method of the high-voltage direct current cable for the high-speed rail traction locomotive according to claim 8, wherein the inner core body (12) is an insulating rope, and the insulating rope is made by extruding and molding water-absorbing polyurethane foam into a cylinder shape and performing post-curing at 120 ℃ for 1 hour.
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