Power cable with distributed water blockage monitoring function and method of manufacturing the same

Abstract

The application relates to the technical field of power cables, in particular to a power cable with a distributed water blocking monitoring function and a preparation method thereof. The cable is provided with a multistage water blocking structure design of a conductor layer, an insulation layer and a sheath layer, and is combined with an embedded sensing monitoring system, early warning and accurate positioning of water seepage are realized, and the long-term reliability of the cable in a humid environment is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power cables, in particular to a power cable with distributed water-blocking monitoring function and a preparation method thereof. BACKGROUND

[0002] Some existing water-blocking and monitoring technologies may have negative effects on the electrical and mechanical properties of the cable during implementation. For example, after adding water-blocking powder, the water absorption of the water-blocking powder causes the conductor resistance to increase by 5%-15%; the disintegration of water-blocking yarns causes the mechanical strength to decrease by 40%; the slot-type optical fiber layout reduces the mechanical strength; even some cables have monitoring functions in different structural layers, these monitoring functions are often isolated from each other and cannot form effective data fusion and analysis. For example, the monitoring data of the conductor layer cannot be processed in coordination with the monitoring data of the insulation layer and the sheath layer, which cannot provide comprehensive and accurate cable moisture state information for the operation and maintenance personnel, reducing the practical value of the monitoring system; the existing cables have limited means for water monitoring and lack full-link water monitoring capability. Some cables have simple monitoring devices in the insulation layer or sheath layer, but cannot realize coordinated monitoring of the conductor, insulation, sheath and other full-structural layers, making it difficult to accurately locate the path and degree of water intrusion; the existing technology cannot accurately locate the specific position and range of water intrusion, and cannot provide strong support for timely and effective maintenance. When water intrusion occurs, it is difficult for the operation and maintenance personnel to quickly determine the affected cable section, resulting in low maintenance efficiency, increased power outage time and economic losses. SUMMARY

[0003] The technical problem to be solved by the present application is that water-blocking materials affect the electrical and mechanical properties of the cable after absorbing water, the monitoring function is isolated, and full-link water monitoring and accurate positioning cannot be realized.

[0004] The technical solution adopted by the present application to solve the technical problem is: a power cable with distributed water-blocking monitoring function, comprising a conductor layer, an insulation layer, a filling structure and a sheath layer arranged in sequence from inside to outside, wherein:

[0005] The conductor layer adopts an interlaced nested stranded structure, and a self-adhesive semiconductive water-blocking gel layer and a high-voltage resistant micro-sensing wire are arranged between adjacent stranded layers;

[0006] The insulation layer comprises a nanocomposite cross-linked polyethylene material, an aerogel felt layer and a double optical fiber array embedded therein;

[0007] The filling structure is an intelligent phase change water-blocking material, wherein conductive particles are dispersed and monitoring electrodes are pre-embedded;

[0008] The sheath layer comprises an inner liner, an alloy shielding waterproof layer and an outer sheath, wherein a conductive ink sensing net, a shielding optical fiber and a ring structure sensing belt are embedded.

[0009] The center conductor of the conductor layer is a spiral structure, and a spiral groove is arranged on the surface, and the hoop conductor is embedded in the groove.

[0010] The double-fiber array in the insulation layer comprises an inner fiber and a middle fiber, the inner fiber is 0.2mm away from the aerogel interface, and the middle fiber is 0.5mm away from the inner fiber.

[0011] The shielded optical fiber coated with a metal shielding layer is embedded in the alloy shielding and waterproof layer of the sheath layer, and the annular structure sensing belt is arranged inside the outer sheath with an interval of 1m.

[0012] A preparation method of the power cable of claim 1, comprising the following steps:

[0013] The conductor is embedded synchronously with the high-voltage resistant micro sensing wire;

[0014] The insulation layer is co-extruded and biaxially embedded with the double-fiber array;

[0015] The sheath is co-extruded and integrated with the sensing unit;

[0016] The whole structure signal is integrated and data is processed.

[0017] During the co-extrusion of the insulation layer, the aerogel felt layer is preheated to 80 DEG C, the double-fiber array is embedded into the interface or implanted in the middle through the guiding device, the co-extrusion temperature is 180~190 DEG C, and the pressure is 5~6MPa.

[0018] During the forming of the sheath layer, the inner lining layer is printed with a sensing net through a textured roller, the alloy shielding and waterproof layer is embedded with the optical fiber through laser drilling and positioning during longitudinal packaging, and the outer sheath is fixed with the annular structure sensing belt during co-extrusion.

[0019] The signal integration adopts a wavelength division multiplexing technology and a space-time correlation algorithm to realize multi-source monitoring data fusion and three-dimensional reconstruction of water intrusion.

[0020] The inner side of the sheath layer is provided with a combined elastic split monitoring tightening rope group.

[0021] The combined elastic split monitoring tightening rope group comprises a monitoring pull rope, end connecting blocks installed at two ends of the monitoring pull rope, end monitoring barrels located at the two ends of the monitoring pull rope, a reset spring installed in the middle of the end monitoring barrel, end connecting frames fixed at two ends of the reset spring, and a pressure sensor installed at one end of the end monitoring barrel, and the monitoring pull rope is connected with the reset spring by being inserted into the inside of the end connecting frame through the end connecting blocks.

[0022] The beneficial effects of the present application are:

[0023] (1) The power cable with a distributed water blocking monitoring function and the preparation method thereof form a full structure layer cooperative water blocking system, the water blocking response is rapid and efficient, and the long-term water blocking stability is strong, the water blocking elements of each layer can quickly start protection and monitoring in the initial stage of water intrusion, and the long-term reliable operation of the cable in a humid environment is ensured;

[0024] (2) The monitoring system realizes full-link water monitoring coverage, the monitoring data is accurate and reliable, the anti-interference ability is outstanding, and the water intrusion position, degree and path can be accurately reconstructed;

[0025] (3) The structural design of the application is scientific and reasonable, the structural compatibility is excellent, the mechanical performance is fully guaranteed, the material selection is highly adaptable, and the influence of the sensing unit on the electrical performance of the cable is minimal;

[0026] (4) The application can early warn the water intrusion risk through accurate monitoring, avoid sudden failures caused by insulation aging and conductor corrosion, reduce the number and cost of power outages and maintenance, and prolong the service life of the cable;

[0027] (5) By arranging the combined elastic split monitoring tightening rope group in the inner side of the sheath layer, the mechanical strength of the cable can be enhanced, the bending position of the cable can be accurately monitored, timely warning is facilitated, the timeliness is strong, and the difficulty and cost of maintenance are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0028] The application will be further described below in conjunction with the drawings and examples.

[0029] Figure 1 is a structural schematic diagram of the application.

[0030] Figure 2 is a structural schematic diagram of the conductor layer in the application.

[0031] Figure 3 is a partial schematic diagram of the combined elastic split monitoring tightening rope group in the application. DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with the drawings and examples.

[0033] In the description of the application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0034] Figure 1 、 Figure 2 and Figure 3 A power cable with distributed water barrier monitoring function shown in the figure adopts a multi-layer composite structure, specifically including the following layers (from inside to outside):

[0035] Conductor layer 1:

[0036] The conductor adopts a completely new interlaced and nested combination structure of multiple conductor units. In the center of the conductor finished product, there is a specially designed spiral rotating conductor with spiral grooves on its surface. Multiple ring-shaped conductors are tightly embedded in the spiral grooves of the center conductor at a unique angle and spacing, and are twisted and compressed, greatly reducing the gaps between the conductor filaments.

[0037] Between the adjacent twisted layers of the conductor, a "water barrier gel + sensing wire" composite structure is adopted: a self-adhesive semiconductive water barrier gel coating is coated on the bottom layer (normal flexible semi-conductor, expands several times to form a water barrier when encountering water, forms a tight water barrier, effectively prevents water from spreading along the conductor filament gap), and a high-pressure resistant micro sensing wire is embedded in parallel in the gel layer (nickel-plated copper wire with a diameter of 0.08mm, surface coated with a moisture-sensitive conductive coating). When water enters, the resistance of the sensitive coating changes in steps, and the signal is transmitted in real time through the sensing wire to realize monitoring of the conductor layer.

[0038] Insulation layer 2:

[0039] The insulation layer 2 adopts a nano-composite cross-linked polyethylene material 21, uniformly dispersing nano-inorganic particles to improve water resistance and mechanical properties. An aerogel felt layer 22 is added between the conductor and the insulation layer, and the aerogel felt layer 22 adopts a gradient pore size structure, with small inner pores to enhance water resistance and large outer pores to accommodate optical fiber sensing units, taking into account the compatibility of buffering and monitoring.

[0040] A distributed optical fiber sensing monitoring unit (single-mode optical fiber coated with humidity-sensitive fluorescent material) is embedded on the inside of the insulation layer 2 (close to the interface of the aerogel felt layer 22), uniformly distributed along the length direction of the insulation layer 2, with a monitoring point spacing of 0.5~1m. At the same time, auxiliary sensing optical fibers are added in the middle of the insulation layer 2 to form a "double optical fiber array", and the water longitudinal diffusion path is accurately located through the fluorescence intensity change and optical time domain reflectometry (OTDR) technology.

[0041] The double optical fiber array 23 in the insulation layer 2 includes an inside optical fiber and a middle optical fiber, with the inside optical fiber being 0.2mm away from the aerogel interface and the middle optical fiber being 0.5mm away from the inside optical fiber.

[0042] Filling structure 3:

[0043] The cable core gaps are filled with a smart phase-change water-blocking material based on shape memory polymers, which contains micron-sized conductive particles. When moisture penetrates, the material undergoes a phase change and expands, forming a conductive path. Resistance changes are monitored by ultra-fine wires embedded in the filling layer, which helps verify the overall moisture status of the cable core.

[0044] Sheath layer 4:

[0045] The sheath layer 4 consists of a new inner lining layer 41, an alloy shielding and waterproof layer 42, and an outer sheath 43, from the inside out.

[0046] The inner liner 41 is made of expandable thermoplastic polyurethane elastomer, and the inner surface is embedded with a conductive ink sensor mesh 44 (grid spacing 5mm×5mm) to monitor radial moisture penetration by means of resistance change.

[0047] The alloy shielding waterproof layer 42 uses copper-aluminum alloy microporous tape, with distributed optical fibers pre-embedded in the plastic layer (coated with a metal shielding layer to resist electromagnetic interference). When the micropores open when they encounter water, they trigger changes in the optical fiber intensity, achieving longitudinal water blocking and monitoring simultaneously.

[0048] An annular sensing strip (spaced 1m apart) is installed on the inner side of the outer sheath 43. It is made of conductive polymer water-resistant composite material. When it comes into contact with water, the change in conductivity is transmitted to the monitoring terminal through the wire, forming the first monitoring defense line on the outer layer of the sheath.

[0049] The inner side of the sheath layer 4 is equipped with a combined elastic split monitoring and tightening rope group 5.

[0050] Cable specifications: copper conductor 3*50+1*25, voltage rating 0.6 / 1kV.

[0051] Conductor structure: central spiral copper conductor (pitch 5mm, groove depth 0.5mm), inner circumferential conductor (φ2.0mm, 6 strands), outer circumferential conductor (φ2.0mm, 12 strands).

[0052] Adjacent stranded layers are coated with a 0.2mm thick self-adhesive semiconducting resistive hydrogel (expansion rate 350%), and embedded with φ0.08mm nickel-plated sensing wires with a spacing of 50mm between the sensing wires.

[0053] Insulation structure: a nano-composite cross-linked polyethylene insulation layer 21 (1.4 mm thick, 5% nanoparticle content), and an aerogel felt layer 22 (0.3 mm thick, gradient pore size). The inner optical fiber (φ0.125 mm, coated with fluorescent material) is 0.2 mm³ from the aerogel interface, and the middle optical fiber is 0.5 mm³ from the inner optical fiber. The monitoring point spacing is 1 m. Testing showed that this insulation layer 2 exhibits a partial discharge of ≤3 pC and an electrical strength of 22 kV / mm at 1.73 U0, with a performance attenuation of ≤1% compared to the insulation layer 2 without embedded optical fibers.

[0054] Filler structure 3: Cable core gap filling based on shape memory polymer intelligent phase change water blocking material, which mixes silver-coated nickel conductive particles with a diameter of 5-10 μm, with a mass ratio of 3%. When filling, use a special filling device to inject the cable core gap at a speed of 0.8-1.0 m / min, the filling pressure is controlled at 0.2-0.3 MPa, and the filling rate is ensured to reach more than 98%. In the middle of the filling layer, a silver-plated copper wire with a diameter of 0.1 mm is embedded as a monitoring electrode, and the wire spacing is 1 m. When moisture enters the filling layer, the material undergoes phase change and expands to 2-3 times the original volume within 30-40 s, and at the same time, a conductive path is formed, and the resistance value monitored by the wire decreases from the initial ≥10 5 Ω to ≤10³Ω, realizing auxiliary monitoring of the overall moisture state of the cable core.

[0055] Sheath structure: conductive ink sensing net 44 (grid 5 mm x 5 mm, resistance change ≥50% / 0.1 mm water film) on the inner surface of inner lining layer 41 (0.8 mm thick). Shielded optical fiber 45 (φ0.2 mm) is pre-embedded in the alloy shielding layer, and sensing band 46 (1 m apart) is arranged in the annular structure on the inner side of outer sheath 43 (1.8 mm thick).

[0056] The preparation method is as follows:

[0057] Double-process synchronous equipment: In the conductor stranding process, the ring-shaped conductor is embedded in the spiral groove through precise guide wheels. In the synchronous process, the sensing wire is embedded in the gel coating layer in parallel through a micro-tension control device, and the gel thickness (0.2-0.3 mm) is precisely controlled by a spraying device to ensure that the sensing wire is tightly combined with the gel and does not affect the conductivity of the conductor. Process parameters: stranding speed 10-15 m / min, gel spraying pressure 0.3-0.5 MPa, sensing wire tension 5-8 N.

[0058] Insulating layer 2 co-extrusion: adopt co-extrusion-biaxial embedding technology: after the aerogel felt layer 22 is preheated to 80℃, it is introduced into the co-extrusion die, the inner optical fiber is embedded into the interface between the aerogel felt layer 22 and the insulating layer 2 through horizontal guiding device, the middle optical fiber is precisely implanted into the middle of the insulating layer 2 through oblique puncture device (angle 30°), and then co-extruded with nanometer composite cross-linked polyethylene material 21, hot pressing temperature 180-190℃, pressure 5-6 MPa, to ensure that the optical fiber embedding position deviation is ≤0.1 mm. This process uses the flow characteristics of the insulating material to fill the surrounding gaps after the optical fiber is embedded, so that the optical fiber and the insulating layer 2 form a seamless combination, avoiding the formation of air gaps or local weak points, and further ensuring that the insulation performance is not affected.

[0059] Sheath multi-layer sensing synergistic forming process: when the inner liner 41 is extruded, the conductive ink is printed into a conductive ink sensing net 44 by a textured roller, and the curing temperature is 120°C; when the alloy shielding waterproof layer 42 is longitudinally packaged, the shielding optical fiber 45 is embedded into the preset groove of the plastic layer through laser drilling positioning; when the outer sheath 43 is co-extruded, the annular structure sensing belt 46 is fixed to the inner side through the annular guide, and after the three layers are synchronously formed, the interlayer adhesion is enhanced through plasma treatment, so as to ensure stable transmission of the sensing unit signal.

[0060] Full-structure layer signal integration process: a multi-channel signal demodulation terminal is developed, the monitoring data of the conductor sensing line (electric signal), the insulating optical fiber (optical signal) and the sheath sensing net (electric signal) are distinguished through wavelength division multiplexing technology, the multi-source information is fused through a time-space correlation algorithm, and three-dimensional reconstruction of the water intrusion position (positioning error ≤0.3 m), degree (error ≤5%) and path is realized.

[0061] Adopting sensing unit compatibility design in multi-medium environment: the conductor sensing line adopts high-voltage-resistant (≥1kV) insulating coating to avoid forming a potential difference with the conductor; the insulating optical fiber selects low-loss (≤0.2dB / km) fluorescent material to ensure that the signal attenuation is ≤5% in the nanocomposite medium; the sheath sensing net adopts weather-resistant conductive ink (stability ≥10 years at -40~85°C) to resist chemical corrosion of the outer sheath material.

[0062] Adopting signal anti-interference and synergistic calibration technology: the conductor layer 1 adopts differential signal transmission to suppress electromagnetic interference; the insulating layer 2 optical fiber adopts phase modulation technology to eliminate temperature cross-sensitivity; the sheath layer sensing net distinguishes radial / longitudinal signals through frequency coding. A temperature-humidity cross-sensitivity compensation model is established, and the monitoring data of each layer is mutually calibrated to ensure that the humidity measurement error is ≤3%RH.

[0063] Water blocking and monitoring function synergistic optimization: the conductor gel coating expansion rate (≥300%) is matched with the sensing line response threshold (water content ≥5%) to ensure that the warning is completed before the water blocking is started; the aerogel felt water absorption expansion rate (≤30s to reach the maximum volume) of the insulating layer is connected with the optical fiber response time (≤10s) to form a gradient defense; the alloy layer micropore opening pressure (0.2MPa) of the sheath is linked with the optical fiber light intensity change threshold to realize the synchronization of passive water blocking and active monitoring.

[0064] Full life cycle reliability guarantee: the interface bonding strength of the sensing unit and the cable structure layer is ≥1.5N / mm, and the signal integrity is ≥95% after 1000 bending cycles (bending radius is 10 times the cable diameter); the phase change cycle stability of the intelligent filling material is ≥50 times, which ensures the long-term monitoring accuracy.

[0065] The inside of the sheath layer 4 is provided with a combined elastic split monitoring tightening rope group 5, which comprises a monitoring pull rope 51, end connecting blocks 52 installed at both ends of the monitoring pull rope 51, end monitoring barrels 53 located at both ends of the monitoring pull rope 51, a reset spring 54 installed in the middle of the end monitoring barrel 53, end connecting frames 55 fixed at both ends of the reset spring 54, and a pressure sensor 56 installed at one end of the end monitoring barrel 53, the monitoring pull rope 51 is connected with the reset spring 54 by inserting the end connecting blocks 52 into the inside of the end connecting frames 55.

[0066] The above is the ideal embodiment of the present application, and the related personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A power cable with distributed water blockage monitoring function, characterized in that, It includes, from the inside out, a conductor layer (1), an insulating layer (2), a filling structure (3), and a sheath layer (4), wherein: The conductor layer (1) adopts an interleaved nested stranded structure, and a self-adhesive semiconducting hydrogel layer and a high-voltage resistant micro-sensing wire are provided between adjacent stranded layers; The insulating layer (2) includes a nanocomposite cross-linked polyethylene material (21), an aerogel felt layer (22), and a dual fiber array (23) embedded therein. The filling structure (3) is a smart phase change water-blocking material, in which conductive particles are dispersed and monitoring electrodes are pre-embedded; The sheath layer (4) includes an inner lining layer (41), an alloy shielding and waterproof layer (42), and an outer sheath (43), wherein a conductive ink sensor mesh (44), a shielded optical fiber (45), and a ring structure sensor strip (46) are embedded. The dual fiber array in the insulating layer (2) includes an inner fiber and a middle fiber. The inner fiber is 0.2 mm away from the aerogel felt layer (22), and the middle fiber is 0.5 mm away from the inner fiber. The alloy shielding waterproof layer (42) of the sheath layer (4) is pre-embedded with shielding optical fiber (45) coated with metal shielding layer, and the inner side of the outer sheath (43) is provided with a ring structure sensing strip (46) arranged at intervals of 1m. An aerogel felt layer (22) is added between the conductor layer (1) and the insulating layer (2). The aerogel felt layer (22) adopts a gradient pore structure, with a small inner pore size to enhance water resistance and a large outer pore size to accommodate the fiber optic sensing unit. The inner surface of the liner (41) is embedded with a conductive ink sensor mesh (44).

2. A power cable with distributed water blockage monitoring function according to claim 1, characterized in that, The central conductor of the conductor layer (1) has a spiral structure and a spiral groove on its surface. The circumferential conductor is embedded in the groove and twisted together.

3. A power cable with distributed water blockage monitoring function according to claim 1, characterized in that, The inner side of the sheath layer (4) is provided with a combined elastic split monitoring and tightening rope group (5).

4. A power cable with distributed water blockage monitoring function according to claim 3, characterized in that, The combined elastic split monitoring and tightening rope assembly (5) includes a monitoring pull rope (51), end connecting blocks (52) installed at both ends of the monitoring pull rope (51), end monitoring cylinders (53) located at both ends of the monitoring pull rope (51), a reset spring (54) installed in the middle of the end monitoring cylinder (53), an end connecting frame (55) fixed at both ends of the reset spring (54), and a pressure sensor (56) installed at one end of the end monitoring cylinder (53). The monitoring pull rope (51) is inserted into the end connecting frame (55) through the end connecting block (52) and connected to the reset spring (54).

5. A method for manufacturing a power cable according to claim 1, characterized in that, Includes the following steps: Conductor stranding and high-voltage resistant miniature sensing wires are embedded simultaneously; Insulating layer (2) co-extruded-biaxial embedded dual fiber array (23); Multi-layer co-extrusion of the sheath and integration with the sensing unit; Full-structure signal integration and data processing.

6. The preparation method according to claim 5, characterized in that, During the co-extrusion process of the insulating layer (2), the aerogel felt layer (22) is preheated to 80°C, and the dual fiber array (23) is embedded in the interface or punctured and implanted in the middle through the guide device. The co-extrusion temperature is 180~190°C and the pressure is 5~6MPa.

7. The preparation method according to claim 5, characterized in that, During the forming process of the sheath layer (4), the inner liner layer (41) is printed with conductive ink sensor mesh (44) by an anilox roller, the alloy shielding waterproof layer (42) is longitudinally wrapped with laser drilling to position and embed optical fiber, and the outer sheath (43) is co-extruded to fix the annular structure sensor tape (46).

8. The preparation method according to claim 5, characterized in that, The signal integration employs wavelength division multiplexing technology and spatiotemporal correlation algorithm to achieve multi-source monitoring data fusion and three-dimensional reconstruction of water intrusion.

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