Intelligent repairing method for microcapsule type high-voltage cable buffer layer

Abstract

The invention provides an intelligent repairing method for a microcapsule type high-voltage cable buffer layer. The intelligent repairing method comprises the following steps: introducing a microcapsule containing a repairing agent into the cable buffer layer; when the composite buffer layer is ablated during operation of the cable and the local temperature rises to the cracking temperature of the microcapsules, the microcapsules are heated and cracked, and the repairing agent is released; the repairing agent is diffused into pores or cracks of the ablation area in a physical filling mode and used for recovering electrical connection between the outer shield and the aluminum sheath and reducing interface resistance. According to the method, the repairing process can be triggered only through local temperature rise generated by ablation without depending on repairing equipment, and the universality of the repairing method is remarkably improved; and meanwhile, the repairing agent is released at the defect part and physically fills pores and cracks, so that the problem of uneven distribution caused by manual injection is effectively avoided, and the diffusion uniformity and repairing reliability of the repairing agent are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power cables, in particular to a microcapsule type high-voltage cable buffer layer intelligent repair method. BACKGROUND

[0002] With the wide application of high-voltage cables in power systems, the problem of cable buffer layer ablation defects has become increasingly prominent, posing a serious threat to the safe and stable operation of the power grid. In recent years, several cable failures caused by buffer layer discharge ablation have occurred in many regions at home and abroad. The starting position of such failures is located in the buffer layer between the insulation shielding layer and the aluminum sheath, and the outer surface of the insulation shielding layer, the buffer layer and the inner surface of the aluminum sheath all have ablation marks and white powder.

[0003] At present, domestic and foreign researchers have made some achievements in addressing this type of cable defect, but most of the achievements focus on the research of the formation mechanism of the buffer layer defect, and the effective detection method and preventive measures for the buffer layer defect need to be further explored. The formation reasons of buffer layer ablation defects are complex and diverse, mainly including water intrusion and electrochemical reaction, poor contact between buffer layer and aluminum sheath, and insufficient performance of buffer layer material, etc. The ablation phenomenon is manifested as ablation points and ablation marks, white powder adhesion and decline of cable insulation performance, etc. In order to ensure the safe and stable operation of the cable, effective repair methods and preventive measures need to be taken to address these reasons and phenomena.

[0004] The repair devices currently proposed mainly adopt the repair method of injecting special repair liquid or graphite powder. However, these methods have limitations in the scope of application of the device. For different specifications or types of cables, corresponding adjustments or redesigns are required, limiting the universality of the repair device. In addition to the lack of applicability, the injection repair needs to consider the diffusion effect of the repair agent. Since the injection repair device generally adopts the method of injecting from both ends or the middle, the injected repair liquid or graphite powder may not diffuse uniformly, resulting in the inability to diffuse and cover all the areas to be repaired, affecting the repair effect. Liquid injection and gas injection generally require pressure to pump in the repair agent, and the pressure needs to be adjusted according to the actual situation. Inappropriate injection pressure may damage the original cable structure and cause new problems. SUMMARY

[0005] In view of this, the present application proposes a microcapsule type high-voltage cable buffer layer intelligent repair method, aiming to solve the problem of poor repair effect of cable buffer layer ablation defects caused by uneven diffusion of repair agent and poor universality of repair device in the prior art. The present application proposes a microcapsule type high-voltage cable buffer layer intelligent repair method, comprising: introducing microcapsules containing repair agents into the cable buffer layer; When the composite buffer layer of the cable is ablated during operation, the local temperature rises to the rupture temperature of the microcapsules, causing the microcapsules to rupture due to heat and release the repair agent. The repair agent diffuses into the pores or cracks of the ablation area through physical filling, in order to restore the electrical connection between the outer shield and the aluminum sheath and reduce the interface resistance.

[0006] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layer, the rupture temperature is 200-300℃.

[0007] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layer, the step of introducing microcapsules containing repair agent into the cable buffer layer includes: during the cable production process, uniformly coating the microcapsules onto the surface of the buffer layer using a coating device, and then wrapping the buffer layer coated with the microcapsules around the outside of the outer shielding layer and encasing it inside the aluminum sheath, so that the microcapsules are located in the interface area between the aluminum sheath and the buffer layer.

[0008] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layer, the step of introducing microcapsules containing repair agent into the cable buffer layer includes: during cable operation, after detecting an ablation defect in the buffer layer, injecting microcapsules into the area where the ablation defect is located using an injection device, based on the location and size of the ablation defect.

[0009] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layers, the injection device includes a micro-injector or a coating robot.

[0010] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layers, the capsule wall material of the microcapsules has temperature responsiveness and its volume resistivity is less than 1×10⁻⁶. 6 Ω·cm.

[0011] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layer, the particle size of the microcapsules is 50-200 micrometers.

[0012] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layer, the repair agent is a conductive or semi-conductive repair liquid.

[0013] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layer, the capsule wall material contains temperature-sensitive additives.

[0014] Furthermore, in the above-mentioned intelligent repair method for microcapsule-type high-voltage cable buffer layers, the microcapsules are prepared by phase separation or emulsification.

[0015] In this invention, microcapsules containing a repair agent are introduced into the cable buffer layer. When the buffer layer is ablated during cable operation and the local temperature rises to the microcapsule rupture temperature, the microcapsules rupture due to heat and release the repair agent. The repair agent diffuses into the pores or cracks of the ablated area through physical filling, restoring the electrical connection between the outer shield and the aluminum sheath and reducing the interface resistance. This method does not rely on repair equipment; the repair process can be triggered solely by the local temperature rise caused by ablation, significantly improving the versatility of the repair method. At the same time, the repair agent is released at the defect site and physically fills the pores and cracks, effectively avoiding the problem of uneven distribution caused by manual injection, and significantly improving the diffusion uniformity and repair reliability of the repair agent. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic flowchart illustrating the intelligent repair method for microcapsule-type high-voltage cable buffer layer provided in this embodiment of the invention; Figure 2 This is a schematic diagram of the structure in which microcapsules are pre-embedded in the cable buffer layer in the intelligent repair method for microcapsule-type high-voltage cable buffer layer provided in the embodiments of the present invention; Figure 3 This is a three-dimensional cross-sectional schematic diagram of the microcapsules in the intelligent repair method for microcapsule-type high-voltage cable buffer layer provided in the embodiments of the present invention. Detailed Implementation

[0017] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] See Figures 1-2 The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to embodiments of the present invention includes: Step S1: Introduce microcapsules containing repair agents into the cable buffer layer.

[0019] Specifically, in this embodiment of the invention, the buffer layer refers to a water-blocking semi-conductive buffer layer located between the aluminum sheath and the insulating shield. It is composed of a water-absorbing and swelling layer 1 (e.g., fluffy cotton), a water-blocking powder filling layer 2, and a non-woven fabric layer 3, arranged sequentially from the inside out. The microcapsules 4 can be pre-embedded in the pores of the non-woven fabric layer or introduced by injection after a fault. The presence of the microcapsules does not affect the water-blocking or conductive properties of the buffer layer.

[0020] The particle size of microcapsules 4 can be determined according to actual conditions, for example, it can be preferably 50-200 micrometers.

[0021] The capsule wall 41 of the microcapsule 4 can be made of thermoplastic polymer (e.g., thermoplastic polyurethane in post-failure repair scenarios) or thermosetting resin (e.g., epoxy resin in pre-embedding scenarios during the production stage) depending on the application scenario, and an appropriate amount of temperature-sensitive additives (e.g., thermally expandable graphite) can be added to ensure that it ruptures at 200–300℃ and meets the requirement that the volume resistivity is less than 1×10⁻⁶. 6 Ω·cm. The amount of temperature-sensitive additive can be 5%–20% of the total mass of the capsule wall material, for example, 10%.

[0022] The core material 42 of microcapsule 4 is the repair agent, which is a conductive or semi-conductive repair liquid. Different types can be selected in different application scenarios. For example, in the repair scenario after a failure, a semi-conductive repair liquid can be used, such as one composed of acrylic resin, ethyl acetate, superconducting carbon black and polyurethane dispersant. In the pre-embedding scenario during the production stage, a conductive repair liquid is used, such as one containing nano-conductive fillers, catalysts and surfactants.

[0023] Those skilled in the art can prepare this repair-functional microcapsule by combining it with conventional microcapsule preparation processes (such as phase separation method and emulsification method) according to actual needs.

[0024] In this embodiment, the rupture temperature of the microcapsules can be 200-300℃. The capsule wall material of the microcapsules has temperature responsiveness and a volume resistivity of less than 1×10⁻⁶. 6 Ω•cm, preferably 10 4 -5×10 5 Ω·cm.

[0025] In one embodiment of this example, introducing microcapsules containing a repair agent into the cable buffer layer includes: during the cable production process, uniformly coating the microcapsules onto the surface of the buffer layer using a coating device, then wrapping the buffer layer coated with the microcapsules around the outside of the outer shielding layer and encasing it inside the aluminum sheath, so that the microcapsules are located in the interface region between the aluminum sheath and the buffer layer.

[0026] In practice, during cable production, microcapsules are mixed with anhydrous ethanol, acrylate adhesives, and dispersants (such as sodium dodecylbenzenesulfonate) to form a coatable liquid slurry. Anhydrous ethanol serves as a volatile solvent, the acrylate adhesive as a film-forming matrix, and the dispersant improves the wettability and stability of the microcapsules in the slurry. The components are placed in a dispersion device and sheared and stirred at 5000-10000 rpm for 3-10 minutes to ensure uniform dispersion of the microcapsules. Subsequently, the cable is laid flat on a conveyor belt using a water-blocking buffer tape, and the slurry is uniformly coated onto the surface of the buffer tape using an adjustable-gap scraper or slit coating head. After coating, it is cured by hot air drying at 50-80℃. The drying time is dynamically adjusted according to the coating thickness, generally 3-10 minutes, allowing the solvent to evaporate and forming a composite buffer layer containing microcapsules.

[0027] In another embodiment of this example, introducing the microcapsules containing the repair agent into the cable buffer layer includes: after detecting an ablation defect in the buffer layer, injecting the microcapsules into the area where the ablation defect is located using an injection device, based on the location and size of the ablation defect.

[0028] In practice, if an ablation defect is detected in the buffer layer during cable operation, it can be repaired locally using an injection method. The injection device includes a micro-injector (e.g., a glass or quartz micro-injector with a capacity of 10–50 μL, fitted with a flat-headed needle with an inner diameter of 0.2–0.5 mm, and a minimum graduation of 0.1 μL to precisely control the injection volume) or a coating robot.

[0029] First, the abnormal heating area of ​​the cable body can be located using high-precision infrared thermal imaging technology, which serves as the target location for microcapsule injection. At the same time, the total puncture depth required by the injection needle is calculated based on the thickness of the cable's outer sheath and aluminum sheath, and a limiter is installed on the injection device to restrict the needle insertion depth and prevent accidental puncture or damage to the internal structure.

[0030] Specifically, microcapsules containing the repair agent are dispersed in anhydrous ethanol to form a low-viscosity suspension (viscosity of about 1-3 mPa·s at 25°C). This suspension has good fluidity, making it easy to inject through a microneedle. The injection volume is determined according to the size of the defect (e.g., 0.5-1 mL of suspension per square millimeter of defect area), and the injection pressure and needle insertion depth are adjusted according to the depth of the defect to ensure that the repair solution is accurately injected into the ablation defect area.

[0031] The suspension is precisely injected into the ablation defect area using devices such as micro-syringes. Due to the good volatility and permeability of anhydrous ethanol, the microcapsules are able to distribute evenly in the defect pores or cracks and adhere stably to the ablation site after the solvent evaporates.

[0032] Step S2: When the composite buffer layer is ablated during cable operation, the local temperature rises to the rupture temperature of the microcapsules, causing the microcapsules to rupture due to heat and release the repair agent.

[0033] Specifically, during cable operation, when the local temperature rises to 200–300°C, the microcapsule walls rupture due to heat, releasing the internal repair agent, which then diffuses and fills the ablated area.

[0034] Step S3: The repair agent is diffused into the pores or cracks of the ablation area by physical filling, in order to restore the electrical connection between the outer shield and the aluminum sheath and reduce the interface resistance.

[0035] Specifically, the repair agent, through its conductive or semi-conductive properties, rebuilds the electrical path between the outer shield and the aluminum sheath after filling the ablated area, thereby effectively reducing the interface resistance. The conductive or semi-conductive properties of the repair agent can be achieved by adding conductive fillers to ensure effective restoration of the conductive connection between the outer semi-conductive shield and the aluminum sheath after repair. It is evident from the above that the intelligent repair method for microcapsule-type high-voltage cable buffer layers provided in this embodiment introduces microcapsules containing repair agents into the cable buffer layer. When the buffer layer undergoes ablation during cable operation and the local temperature rises to the microcapsule rupture temperature, the microcapsules rupture due to heat and release the repair agent. This repair agent diffuses into the pores or cracks of the ablated area through physical filling, restoring the electrical connection between the outer shield and the aluminum sheath and reducing the interface resistance. This method does not rely on repair equipment; the repair process is triggered solely by the local temperature rise caused by ablation, significantly improving the versatility of the repair method. Simultaneously, the release of the repair agent at the defective location and its physical filling of pores and cracks effectively avoids the uneven distribution problem caused by manual injection, significantly improving the diffusion uniformity and repair reliability of the repair agent.

[0036] The present invention will now be described in detail with reference to two specific embodiments.

[0037] Example 1 The microcapsule walls are made of thermoplastic polyurethane with thermally expandable graphite incorporated as a temperature-sensitive additive to enhance their response to localized temperature rises. The core is a semi-conductive repair fluid composed of anhydrous acrylic resin as the film-forming matrix, ethyl acetate as the volatile solvent, superconducting carbon black as the conductive filler, and a polyurethane dispersant. The microcapsules are prepared using a phase separation method, with particle sizes controlled between 50 and 200 micrometers to ensure smooth injection via a micro-injector.

[0038] During repair, a micro-injector is used to inject a microcapsule suspension into the ablation defect area of ​​the cable buffer layer. By controlling the depth and position of the needle, the microcapsules are evenly distributed in the defect area. When the temperature of the buffer layer rises to 200–300°C due to local discharge, the capsule wall softens and ruptures, releasing the repair agent. The repair agent diffuses into the cracks or pores, restoring the electrical connection between the outer shield and the aluminum sheath through its semi-conductive properties, and forming a stable repair layer, thereby restoring the function of the buffer layer.

[0039] Example 2 The capsule walls are composed of epoxy resin and thermally expandable graphite, giving them temperature responsiveness. The core is a conductive repair fluid containing nano-conductive fillers (such as carbon black), catalysts, and surfactants to achieve good conductivity and interfacial compatibility. Microcapsules are prepared using an emulsification method, and their particle size distribution is controlled to make them suitable for coating processes.

[0040] During cable production, a repair coating containing the microcapsules is uniformly applied to the surface of a water-blocking buffer strip using a coating machine. Subsequently, during the coating curing process, the microcapsules are embedded in the buffer layer, located between the aluminum sheath and the outer shield. When an ablation fault occurs during cable operation, the local temperature rises to the microcapsule rupture temperature, triggering the microcapsules to rupture and release the conductive repair agent. The repair agent diffuses and interacts with the ablation products, restoring the conductivity and mechanical strength of the buffer layer and effectively inhibiting defect propagation.

[0041] Those skilled in the art should understand that the capsule wall material, core material assembly, and preparation method of the microcapsules in the embodiments of the present invention can be selected based on existing technologies. As long as the microcapsules have the function of rupturing at 200-300°C and releasing conductive / semi-conductive repair agents, the technical effects of the present invention can be achieved.

[0042] This invention introduces microcapsules containing a repair agent into the cable buffer layer. When the buffer layer ablates during cable operation and the local temperature rises to the microcapsule rupture temperature, the microcapsules rupture and release the repair agent. This repair agent diffuses into the pores or cracks of the ablated area through physical filling, restoring the electrical connection between the outer shield and the aluminum sheath and reducing the interface resistance. This method eliminates the need for repair equipment, relying solely on the local temperature rise caused by ablation to trigger the repair process, significantly improving the versatility of the repair method. Simultaneously, the repair agent is released at the defect location and physically fills the pores and cracks, effectively avoiding the uneven distribution problem caused by manual injection, significantly improving the diffusion uniformity and repair reliability of the repair agent.

[0043] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for intelligent repair of microcapsule-type high-voltage cable buffer layers, characterized in that, include: Microcapsules containing repair agents are introduced into the cable buffer layer; When the composite buffer layer of the cable is ablated during operation, the local temperature rises to the rupture temperature of the microcapsules, causing the microcapsules to rupture due to heat and release the repair agent. The repair agent diffuses into the pores or cracks of the ablation area through physical filling, in order to restore the electrical connection between the outer shield and the aluminum sheath and reduce the interface resistance.

2. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The rupture temperature is 200-300℃.

3. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The process of introducing microcapsules containing repair agents into the cable buffer layer includes: during the cable production process, uniformly coating the microcapsules onto the surface of the buffer layer using a coating device, then wrapping the buffer layer coated with the microcapsules around the outside of the outer shielding layer and encasing it inside the aluminum sheath, so that the microcapsules are located in the interface area between the aluminum sheath and the buffer layer.

4. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The step of introducing microcapsules containing repair agents into the cable buffer layer includes: during cable operation, after detecting an ablation defect in the buffer layer, injecting microcapsules into the area where the ablation defect is located using an injection device, based on the location and size of the ablation defect.

5. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 4, characterized in that, The injection device includes a micro-injector or a coating robot.

6. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The capsule wall material is temperature-responsive, with a volume resistivity of less than 1×10⁻⁶. 6 Ω·cm.

7. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The microcapsules have a particle size of 50-200 micrometers.

8. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The repair agent is a conductive or semi-conductive repair solution.

9. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The capsule wall material contains temperature-sensitive additives.

10. The intelligent repair method for microcapsule-type high-voltage cable buffer layer according to claim 1, characterized in that, The microcapsules are prepared by phase separation or emulsification.

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