An intermediate fusion joint of a power cable, integrated method and on-line monitoring system

Abstract

This invention discloses an intermediate fusion joint for power cables, an integration method, and an online monitoring system. The joint comprises a conductor fusion connection portion, an insulation regeneration layer, and a metal shielding sleeve. The conductor fusion connection portion forms a fusion connection at the junction of two cable cores. The insulation regeneration layer covers the outside of the conductor fusion connection portion and includes a semi-conductive inner shielding portion, an insulating portion, and an outer shielding portion arranged sequentially from the inside out. The metal shielding sleeve covers the outside of the insulation regeneration layer, forming electromagnetic shielding and, together with the outer shielding portion, constituting the shielding structure of the joint area. This allows for the integrated restoration of conductor connection, electric field control, and shielding continuity in the joint area, ensuring stable electrical connection and insulation during long-term operation. This improves the withstand voltage stability and lifespan consistency of the intermediate joint under long-term load, temperature rise changes, and environmental fluctuations.

Description

Technical Field

[0001] This invention relates to the field of cable assemblies, and more particularly to an intermediate fusion joint, integration method, and online monitoring system for power cables. Background Technology

[0002] Power cables, as key transmission carriers in urban power distribution networks, industrial park power supply, rail transit, and wind-solar-storage grid connection scenarios, often use cross-linked polyethylene (XLPE) and other insulation structures to achieve long-distance transmission of medium- and high-voltage electrical energy. Due to factors such as laying length, construction conditions, maintenance and replacement, and line modification, cable splicing is unavoidable during project implementation. Among these, intermediate joints are often located at the weakest points of the cable line, and must withstand the temperature rise cycle caused by long-term load current, as well as complex environments such as humidity, soil stress, and mechanical vibration. Therefore, higher requirements are placed on the reliability of conductor connection, insulation restoration integrity, and shielding continuity of the joints.

[0003] In existing technologies, intermediate joints typically achieve electrical connection between two conductor segments through methods such as crimping, bolting, or fusion bonding. Insulation and shielding structures are restored on the outside of the conductor connection area using methods such as wrapping, heat shrinking, or prefabrication to approximate the original cable's inner and outer shielding and insulation layers. However, from the perspective of "continuous restoration of electric field and shielding," existing splicing structures often suffer from discontinuous shielding transitions, unstable interface contact, or difficulty in maintaining shielding boundaries over long periods in the conductor connection area. This can easily lead to distorted electric field distribution and localized electric field concentration in the joint area, thereby inducing partial discharge and accelerating insulation aging, reducing the intermediate joint's withstand voltage stability and reliable lifespan during long-term operation.

[0004] Therefore, it is necessary to improve the existing cable intermediate joints to solve the technical problems of difficulty in continuously restoring the electric field and shielding in the joint area after intermediate fusion connection, and easy generation of electric field concentration, which reduces the long-term insulation reliability. Summary of the Invention

[0005] The purpose of this invention is to provide an intermediate fusion joint for power cables, an integration method, and an online monitoring system to solve the above-mentioned technical problems.

[0006] To achieve this objective, the present invention adopts the following technical solution: An intermediate fusion joint for a power cable includes a conductor fusion connection portion, an insulation regeneration layer, and a metal shielding sleeve; The conductor fusion joint is used to form a fusion connection at the joint of two cable cores; The insulating regeneration layer covers the outside of the conductor fused connection portion, and the insulating regeneration layer includes a semiconductive inner shielding portion, an insulating portion, and an outer shielding portion arranged sequentially from the inside to the outside; The metal shielding sleeve covers the outside of the insulating regeneration layer.

[0007] Optionally, the semiconductive inner shield is formed by wrapping a semiconductive vulcanized tape, the insulating part is formed by wrapping an insulating vulcanized tape, and the outer shield is formed by conductive ink.

[0008] Optionally, the metal shielding sleeve is a woven mesh formed of tin-plated copper wire, the diameter of the tin-plated copper wire is 0.15mm, and the weaving density is not less than 95%.

[0009] Optionally, the intermediate fusion joint further includes: A constant force fixing spring is sleeved on the outside of the metal shielding sleeve and applies a radial clamping force to the metal shielding sleeve to achieve external fixation.

[0010] The present invention also provides an integration method for an intermediate fusion joint of a power cable, for integrating an intermediate fusion joint of a power cable as described above, the integration method comprising: Pre-process several sections of power cable; The pre-treated core ends of the two power cable sections are inserted into the cavity of the melting mold. The pre-molten filler in the melting mold is melted by heating. The molten filler fills the cavity under the guidance of the guide groove, melting and connecting the two core ends into one piece. After cooling, a conductor molten connection is formed. Semiconducting material, insulating material and conductive material are layered and coated on the outside of the conductor fusion connection to form a semiconducting inner shielding part, an insulating part and an outer shielding part arranged sequentially from the inside to the outside. The coated structure is integrally vulcanized to form an insulating regeneration layer. A metal shielding sleeve is wrapped around the outside of the insulating regeneration layer.

[0011] Optionally, the process of preprocessing several sections of power cable specifically includes: Strip the outer sheath of the cable end for a first predetermined length to expose the steel armor; A second predetermined length of steel armor is retained at the break point of the outer sheath, and the remaining steel armor is peeled off to expose the inner sheath. At the steel armor break, retain the inner sheath for a third predetermined length, peel off the remaining inner sheath to expose the copper shielding layer; A fourth predetermined length of copper shielding layer is retained at the break point of the inner sheath, and the remaining copper shielding layer is peeled off to expose the outer shielding layer. At the break point of the copper shielding layer, retain a fifth predetermined length of the outer shielding layer, peel off the remaining outer shielding layer, and expose the cable insulation layer. The exposed cable insulation layer is cut into a conical surface at the end, and a sixth predetermined length of inner shielding layer is retained at the end of the conical surface, exposing the wire core for splicing.

[0012] Optionally, the first predetermined length is 700-900mm, the second predetermined length is 20-40mm, the third predetermined length is 40-60mm, the fourth predetermined length is 500-700mm, the fifth predetermined length is 10-20mm, and the sixth predetermined length is 5-15mm.

[0013] Optionally, the melting mold includes a mold body, a melting cavity, and a flow channel; The mold body forms a loading cavity extending in the vertical direction. The lower end of the loading cavity is connected to the melting cavity through a pouring channel, so that the molten filler loaded into the loading cavity melts when heated and enters the melting cavity through the pouring channel. The melting cavity extends laterally and has mating insertion holes formed at its opposite ends for inserting two sections of power cable cores, so that the two sections of cores are coaxially mated in the melting cavity. The guide groove is disposed on the inner wall of the melting cavity and arranged along the extension direction of the melting cavity, and is used to guide the molten filler after melting to flow in a directional manner in the melting cavity to uniformly fill the gap between the wire core ends. The mold body is a graphite-based mold structure, and the mold body is provided with a fastening structure for closing and fixing the molten cavity.

[0014] The present invention also provides an online monitoring system for intermediate fusion joints of power cables, comprising an intermediate fusion joint manufactured by the above-described integrated method for intermediate fusion joints of power cables, the online monitoring system further comprising: The multi-parameter monitoring unit includes a temperature sensor embedded in the insulating regeneration layer, a partial discharge sensor integrated between the metal shield and the insulating regeneration layer, and an insulation monitoring sensor installed on the grounding wire. An inductive power supply module is mounted on the power cable body and is used to draw power from the cable and supply power to the monitoring system. The data transmission module is installed on the outside of the metal shielding sleeve and is electrically connected to the multi-parameter monitoring unit. It is used to wirelessly transmit the collected monitoring data to the back-end terminal.

[0015] Optionally, the online monitoring system may also include: A signal conditioning circuit, integrated within the data transmission module, is used to filter and amplify the signal acquired by the multi-parameter monitoring unit. The inductive power supply module includes a Rogowski coil power extraction structure and a backup lithium battery. The Rogowski coil power extraction structure is sleeved on the cable body, and the backup lithium battery is electrically connected to the Rogowski coil power extraction structure.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the intermediate fusion joint achieves fusion at the junction of the two cable cores through the conductor fusion connection part, forming a continuous low-resistance current path at the junction; on the outside of the conductor fusion connection part, the insulation regeneration layer forms a semi-conductive inner shielding part, an insulating part, and an outer shielding part from the inside out, wherein the semi-conductive inner shielding part is used to perform electric field transition and homogenization in the conductor connection area, the insulating part is used to restore the main insulation capability of the connection area, and the outer shielding part is used to restore the outer shielding interface and provide a stable reference boundary; a metal shielding sleeve is further covered on the outside of the insulation regeneration layer, the metal shielding sleeve forms electromagnetic shielding externally and together with the outer shielding part constitutes the shielding structure of the joint area, thereby restoring the continuity of conductor connection, electric field control and shielding in an integrated manner in the joint area, ensuring that the joint maintains a stable electrical connection and insulation state during long-term operation; thereby improving the withstand voltage stability and life consistency of the intermediate joint under long-term load, temperature rise changes and environmental fluctuations. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0019] Figure 1 This is a schematic diagram of the online monitoring system for the intermediate fusion joint in Embodiment 3; Figure 2 This is a schematic diagram of the intermediate fusion joint in this embodiment. Figure 3 This is a schematic diagram of cable pretreatment in the integration method of the intermediate fusion joint in Embodiment 2; Figure 4 This is a schematic diagram of the structure of the melting mold in the integration method of the intermediate melting joint in this embodiment 2.

[0020] Illustration: Intermediate fusion joint 10, conductor fusion connection 11, insulation regeneration layer 12, metal shielding sleeve 13, semi-conductive inner shielding layer 121, insulation layer 122, outer shielding layer 123, constant force fixing spring 14, power cable 20, outer sheath 21, steel armor 22, inner sheath 23, copper shielding layer 24, outer shielding layer 25, insulation layer 26 and inner shielding layer 27, wire core 28, fusion mold 30, mold body 31, fusion cavity 32, guide channel 33, loading cavity 34, heating element 36, gasket 35, online monitoring system 40, temperature sensor 41, partial discharge sensor 42, insulation monitoring sensor 43, inductive power supply module 44, data transmission module 45. Detailed Implementation

[0021] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1: Combination Figures 1 to 2 As shown, this embodiment of the invention provides an intermediate fusion joint 10 for a power cable 20, including a conductor fusion connection portion 11, an insulation regeneration layer 12, and a metal shielding sleeve 13; the conductor fusion connection portion 11 is used to form a fusion connection at the joint of two cable cores 28; the insulation regeneration layer 12 covers the outside of the conductor fusion connection portion 11, and the insulation regeneration layer 12 includes a semi-conductive inner shielding portion 121, an insulating portion 122, and an outer shielding portion 123 arranged sequentially from the inside to the outside; the metal shielding sleeve 13 covers the outside of the insulation regeneration layer 12.

[0025] It should be noted that, compared to splicing methods that only achieve conductor connection but lack sufficient shielding / insulation restoration, this joint, through a structural combination of "conductor fusion + three-layer insulation regeneration (inner shield - main insulation - outer shield) + external metal shielding sleeve 13", ensures a continuous and stable current path at the conductor core 28 connection point, and establishes a controllable electric field transition and stable shielding boundary in the conductor connection area, reducing the risk of electric field concentration and partial discharge induction in the connection area; at the same time, the metal shielding sleeve 13 suppresses electromagnetic interference, improves the joint area's anti-interference and operational reliability, thereby enhancing the withstand voltage stability and lifespan consistency of the intermediate joint under long-term load, temperature rise changes and environmental fluctuations.

[0026] The working principle of this invention is as follows: the intermediate fusion joint 10 achieves fusion at the joint of two cable cores 28 through the conductor fusion connection part 11, forming a continuous low-resistance current path at the joint; outside the conductor fusion connection part 11, the insulation regeneration layer 12 forms a semi-conductive inner shield 121, an insulating part 122, and an outer shield 123 from the inside out, wherein the semi-conductive inner shield 121 is used to perform electric field transition and homogenization in the conductor connection area, the insulating part 122 is used to restore the main insulation capability of the connection area, and the outer shield 123 is used to restore the outer shield interface and provide a stable reference boundary; a metal shielding sleeve 13 is further covered outside the insulation regeneration layer 12, the metal shielding sleeve 13 forms electromagnetic shielding externally and together with the outer shielding part 123 constitutes the shielding structure of the joint area, thereby restoring the conductor connection, electric field control, and shielding continuity in the joint area in an integrated manner, ensuring that the joint maintains a stable electrical connection and insulation state during long-term operation; thereby improving the withstand voltage stability and life consistency of the intermediate joint under long-term load, temperature rise changes, and environmental fluctuations.

[0027] In this embodiment, the semiconductive inner shielding portion 121 is formed by wrapping a semiconductive vulcanized tape, the insulating portion 122 is formed by wrapping an insulating vulcanized tape, and the outer shielding portion 123 is formed by conductive ink.

[0028] It should be noted that the semiconductive inner shield 121 is formed by wrapping with semiconductive vulcanized tape, so that a continuous semiconductive transition interface is established on the outside of the conductor connection area, which is used to homogenize the electric field and weaken the field strength concentration caused by the geometric change at the conductor connection. The insulation part 122 is formed by wrapping with insulating vulcanized tape. By wrapping, the conductor connection area can be fully covered and the thickness can be controlled, thereby restoring the main insulation withstand voltage capability of the joint area.

[0029] The outer shielding part 123 is formed by conductive ink, which forms a continuous conductive shielding interface on the outer surface of the insulating part 122, providing a stable potential boundary for the outer metal shielding sleeve 13 and reducing the risk of electric field distortion caused by uneven interface contact.

[0030] In this embodiment, it is further explained that the metal shielding sleeve 13 is a woven mesh formed by tin-plated copper wires, the diameter of the tin-plated copper wires is 0.15mm, and the weaving density is not less than 95%.

[0031] It should be noted that the braided mesh structure can form a flexible covering layer on the outer periphery of the joint, which facilitates installation and fitting, and also forms a relatively continuous conductive shielding surface in the radial direction. This achieves electromagnetic shielding and suppresses the influence of external interference on monitoring signals and the electric field environment of the joint. At the same time, the 0.15mm diameter tin-plated copper wire has good flexibility and fatigue resistance while ensuring conductivity, and can adapt to thermal expansion and contraction and slight deformation during joint operation. The braiding density of not less than 95% ensures the shielding coverage and equivalent conductive continuity, reducing the problem of shielding leakage or unstable shielding boundary caused by excessively large braiding gaps.

[0032] In this embodiment, the intermediate fusion joint 10 also includes a constant force fixing spring 14, which is sleeved on the outside of the metal shielding sleeve 13 and applies a radial clamping force to the metal shielding sleeve 13 to achieve external fixation.

[0033] It should be noted that, due to the temperature rise cycle and environmental stress experienced by the joint during long-term operation, relying solely on the friction of the covering material itself or a one-time tightening structure can easily lead to loosening of the outer shielding sleeve, changes in the fitting gap, or fluctuations in contact resistance, thereby affecting the continuity of shielding and the overall structural stability. The constant force fixing spring 14 can continuously provide a relatively constant radial clamping force, ensuring that the metal shielding sleeve 13 maintains a tight fit with its inner structure over a long period, reducing loosening caused by thermal expansion and contraction, and helping to maintain a stable shielding interface and support.

[0034] Example 2: Combination Figures 3 to 4 As shown, the present invention also provides an integration method for an intermediate fusion joint 10 of a power cable 20, for integrating an intermediate fusion joint 10 of a power cable 20 as described in Embodiment 1. The integration method includes: S1. Pre-process several sections of power cable 20; during the pre-processing process, peel off the outer sheath 21, steel armor 22, inner sheath 23, copper shielding layer 24, outer shielding layer 25, insulation layer 26, and inner shielding layer 27 in layers along the cable axis, so that the ends of the conductor 28 can be exposed and have space to be inserted into the melting mold 30, while ensuring that the copper shielding layer 24, outer shielding layer 25, inner shielding layer 27, etc. have reserved lengths for subsequent shielding restoration and electrical connection; further, grind the ends of the insulation layer 26 to form a conical surface, so that the insulation transition in the joint area is smoother and the risk of electric field concentration caused by geometric abrupt changes at the subsequent restoration structure is reduced; and remove the oxide layer from the ends of the conductor 28 to obtain a clean conductor contact surface.

[0035] S2, the pre-treated core 28 ends of the two power cable segments 20 are inserted into the cavity of the melting mold 30. The pre-molded filler in the melting mold 30 is melted by heating. The molten filler fills the cavity under the guidance of the guide groove 33, and the two core 28 ends are fused together. After cooling, a conductor molten connection part 11 is formed. The molten filler is preferably copper powder.

[0036] By utilizing the molten filler to form a continuous metal bridge, the two core segments 28 are integrated at the metallurgical level, avoiding the problems of uneven contact surfaces or long-term relaxation that may exist in traditional mechanical crimping; at the same time, the guide groove 33 is used to improve the flow path and filling uniformity of the molten metal, reducing the probability of defects such as local underfill, porosity or cold shut.

[0037] S3, a semiconductive material, an insulating material, and a conductive material are layered and coated on the outside of the conductor fusion connection part 11 to form a semiconductive inner shielding part 121, an insulating part 122, and an outer shielding part 123 arranged sequentially from the inside to the outside. The coated structure is then integrally vulcanized to form an insulating regeneration layer 12. The vulcanization conditions are vulcanization at 150°C for 30 minutes for integral molding.

[0038] It should be noted that the semiconductive inner shield 121 is used to achieve electric field homogenization and shielding transition in the conductor connection area, avoiding local field strength concentration caused by structural abrupt changes at the conductor connection point; the insulating part 122 is used to restore the main insulation withstand voltage capability of the joint area, and improves the material density, heat resistance and long-term stability through vulcanization cross-linking; the outer shield 123 is used to form a continuous conductive interface on the outside of the insulating part 122, providing a stable potential boundary for the outer metal shielding sleeve 13 and suppressing external electromagnetic interference and electric field leakage. Through "integrated vulcanization molding", a more stable interface bond can be formed between the layers, reducing the risk of interlayer peeling, voids and partial discharge during operation, thereby improving the long-term insulation reliability of the joint area.

[0039] S4, a metal shielding sleeve 13 is wrapped around the outside of the insulating regeneration layer 12. As an external conductive shielding layer, the metal shielding sleeve can form a continuous shielding path in the joint area, and together with the outer shielding part 123, it can construct a stable reference potential boundary, thereby suppressing electromagnetic radiation and external interference, and reducing the risk of field strength distortion caused by electric field leakage in the joint area.

[0040] In this embodiment, the process of pre-processing several sections of power cable 20 is specifically described as follows: The outer sheath 21 of a first predetermined length is stripped from the cable end to expose the steel armor 22; a second predetermined length of steel armor 22 is retained at the break point of the outer sheath 21, and the remaining steel armor 22 is stripped to expose the inner sheath 23; a third predetermined length of inner sheath 23 is retained at the break point of the steel armor 22, and the remaining inner sheath 23 is stripped to expose the copper shielding layer 24; a fourth predetermined length of copper shielding layer 24 is retained at the break point of the inner sheath 23, and the remaining copper shielding layer 24 is stripped to expose the outer shielding layer 25; a fifth predetermined length of outer shielding layer 25 is retained at the break point of the copper shielding layer 24, and the remaining outer shielding layer 25 is stripped to expose the cable insulation layer 26; the exposed end of the cable insulation layer 26 is cut into a conical surface, and a sixth predetermined length of inner shielding layer 27 is retained at the end of the conical surface, exposing the core 28 for splicing.

[0041] It should be noted that the pre-processed sections of power cable 20 are stripped in a layered, progressive manner from the outside in, forming a stepped stripping window in sequence: outer sheath 21—steel armor 22—inner sheath 23—copper shielding layer 24—outer shielding layer 25—insulation layer 26—inner shielding layer 27. By retaining the corresponding second to sixth predetermined lengths at each layer break, sufficient overlap and transition space is provided for the subsequent layered wrapping and integrated vulcanization of the insulation regeneration layer 12, enabling the semi-conductive inner shielding part 121, insulation part 122, and outer shielding part 123 to form a continuous and stable interlayer interface in the joint area; on the other hand, it also provides a reliable structural basis for the wrapping of the metal shielding sleeve 13, its electrical connection with the shielding layer, and its external fixation.

[0042] As an optional embodiment, the first predetermined length is 700-900mm, the second predetermined length is 20-40mm, the third predetermined length is 40-60mm, the fourth predetermined length is 500-700mm, the fifth predetermined length is 10-20mm, and the sixth predetermined length is 5-15mm. Through these range-limited definitions, the pre-processing dimensions can be adjusted and adapted to different cable specifications and different construction environments.

[0043] In this embodiment, it is further explained that the melting mold 30 includes a mold body 31, a melting cavity 32, and a guide channel 33; The mold body 31 forms a loading cavity 34 extending in the vertical direction. The lower end of the loading cavity 34 is connected to the melting cavity 32 through the pouring channel, so that the molten filler loaded into the loading cavity 34 melts after being heated and enters the melting cavity 32 through the pouring channel. A heating element 36 is provided at a preset position in the loading cavity 34, which is a gunpowder element in this solution.

[0044] The melting cavity 32 extends laterally and has mating insertion holes formed at its opposite ends for inserting the ends of the two wire cores 28 of the power cable 20, so that the ends of the two wire cores 28 are coaxially mated in the melting cavity 32. The guide channel 33 is disposed on the inner wall of the melting chamber 32 and arranged along the extension direction of the melting chamber 32. It is used to guide the molten filler after melting to flow in a directional manner in the melting chamber 32 to uniformly fill the gap between the ends of the wire core 28. A gasket 35 is provided between the guide channel 33 and the loading chamber 34 to achieve sealing and gap adjustment between the two, so as to prevent material leakage and ensure the stability of material flow.

[0045] The mold body 31 is a graphite-based mold structure, and the mold body 31 is provided with a fastening structure for closing and fixing the molten cavity 32.

[0046] It should be noted that the melting mold 30, through its flow organization structure of "loading cavity 34—pouring channel—melting cavity 32—guide groove 33," achieves controllable melting and directional filling of the molten filler, thereby improving the consistency and molding reliability of the molten connection at the ends of the wire core 28. Specifically, the mold body 31 is provided with a loading cavity 34 extending vertically, allowing the molten filler to be concentrated and melted under the action of gravity and heating, and then stably introduced into the laterally extending melting cavity 32 through the pouring channel at the lower end of the loading cavity 34, avoiding local underfilling caused by disordered dispersion of the molten filler in the cavity; the butt insertion holes at both ends of the melting cavity 32 are used to limit the axial position and coaxiality of the ends of the two sections of power cable 20 wire core 28, so that the ends of the wire core 28 are coaxially butt-joined in the cavity, structurally reducing uneven fusion or increased resistance caused by misalignment; the guide groove 33 extends along the melting cavity 32. The extension direction arrangement is used to guide the flow path of the molten filler, so that the copper liquid can uniformly cover and fill the gap between the ends of the wire core 28, reducing the probability of the generation of defects such as pores, cold shuts or inclusions. At the same time, the mold body 31 adopts a graphite-based mold structure, which has the characteristics of high temperature resistance, uniform thermal conductivity and anti-adhesion, which is conducive to achieving uniform heating and stable demolding. The mold body 31 is provided with a fastening structure for mold closing and fixing, which can maintain the sealing and dimensional stability of the molten cavity 32 during heating and molten filling, prevent leakage and displacement, thereby ensuring the forming quality and repeatability of the conductor molten connection part 11.

[0047] Example 3: Combination Figure 1 As shown, the present invention also provides an online monitoring system 40 for an intermediate fusion joint 10 of a power cable 20, comprising an intermediate fusion joint 10 manufactured by the integration method of the intermediate fusion joint 10 of the power cable 20 as described in Embodiment 2, and the online monitoring system 40 further comprising: The multi-parameter monitoring unit includes a temperature sensor 41 embedded in the insulation regeneration layer 12, a partial discharge sensor 42 integrated between the metal shielding sleeve 13 and the insulation regeneration layer 12, and an insulation monitoring sensor 43 installed on the grounding wire. The inductive power supply module 44 is sleeved on the power cable 20 body and is used to draw power from the cable and supply power to the monitoring system. The data transmission module 45 is installed on the outside of the metal shielding sleeve 13 and is electrically connected to the multi-parameter monitoring unit. It is used to wirelessly transmit the collected monitoring data to the back-end terminal.

[0048] The working principle of this invention is as follows: During the operation of the intermediate fusion joint 10, the online monitoring system 40 uses an inductive power supply module 44 mounted on the power cable 20 body and draws energy from the cable's operating current to provide power to the multi-parameter monitoring unit and the data transmission module 45. In the multi-parameter monitoring unit, a temperature sensor 41 embedded in the insulation regeneration layer 12 collects the internal temperature rise information of the joint in real time, a partial discharge sensor 42 integrated between the metal shielding sleeve 13 and the insulation regeneration layer 12 couples and collects partial discharge-related signals near the shielding boundary, and an insulation monitoring sensor 43 installed on the grounding wire acquires electrical parameters related to the insulation state of the joint. The output signals of each sensor are converged by the data transmission module 45 connected to them and then wirelessly transmitted to upload the monitoring data to the back-end terminal, realizing online continuous monitoring and remote visualization of the joint temperature, partial discharge, and insulation state.

[0049] Furthermore, compared to traditional methods that rely on power outage inspections or single-parameter detection, this system employs a multi-parameter collaborative approach, combining "embedded temperature monitoring inside the joint + near-field acquisition of partial discharge signals between shielding layers + insulation status monitoring on the grounding wire side." This ensures that the monitored objects cover the most vulnerable locations and key mechanisms (heat, discharge, insulation) of the joint. Simultaneously, it utilizes a nested inductive power supply method, avoiding the unsustainable long-term online monitoring issues caused by difficulties in external power supply wiring. The data transmission module 45 is located outside the metal shielding sleeve 13 and electrically connected to the multi-parameter monitoring unit, enabling data aggregation and wireless transmission without altering the joint's main structure. This achieves "real-time measurability, remote awareness, and early warning of anomalies" for the intermediate fused joint 10, improving operation and maintenance efficiency and reducing the risk of sudden failures.

[0050] In this embodiment, it is further explained that the online monitoring system 40 for the intermediate fusion joint 10 also includes: The signal conditioning circuit, integrated within the data transmission module 45, is used to filter and amplify the signals acquired by the multi-parameter monitoring unit. Due to the strong electromagnetic interference, large signal amplitude range, and transient characteristics in the connector's operating environment, the signal conditioning circuit suppresses power frequency and external noise interference through filtering and enhances the identifiability of weak but effective signals through amplification, thereby improving the stability and effectiveness of the acquired data and reducing the risk of false alarms and missed alarms. Furthermore, integrating the signal conditioning circuit with the data transmission module 45 helps reduce the number of external connections and interfaces, improving system compactness and reliability.

[0051] The inductive power supply module 44 includes a Rogowski coil power extraction structure and a backup lithium battery. The Rogowski coil power extraction structure is sleeved on the cable body, and the backup lithium battery is electrically connected to the Rogowski coil power extraction structure.

[0052] On the other hand, the inductive power supply module 44 adopts a Rogowski coil power extraction structure sleeved on the cable body to extract energy from the operating current, realizing self-powered power supply without external power supply; and is equipped with a backup lithium battery electrically connected to the Rogowski coil power extraction structure to maintain the continuous operation of monitoring and transmission functions under unstable power extraction conditions such as insufficient load current or no load, thereby realizing the continuous power supply and stable operation of the online monitoring system 40 under different operating conditions.

[0053] In this embodiment, it is further explained that the temperature sensor 41 is a miniature PT1000 sensor, with multiple sensors evenly arranged in the circumferential direction, and the probe is embedded in the insulating part 122 of the insulating regeneration layer 12. The partial discharge sensor 42 is an ultra-high frequency sensor with a frequency range of 300-1500MHz. Insulation monitoring sensor 43 is a high-frequency current transformer, which is snap-fitted onto the grounding wire; The data transmission module 45 is a LoRa wireless communication module; the data transmission module 45 adopts a LoRa wireless communication module, which is suitable for low power consumption and long distance data backhaul requirements, and can form a long-term online monitoring link with inductive power supply.

[0054] The metal shielding sleeve 13 is fixed to the outside of the insulating regeneration layer 12 by a constant force fixing spring 14.

[0055] It should be noted that the temperature sensor 41 uses a miniature PT1000 sensor and has multiple probes evenly arranged in the circumferential direction. The probes are embedded in the insulating part 122 of the insulating regeneration layer 12, thereby realizing multi-point temperature rise monitoring of the key insulation area of ​​the joint, which can more accurately reflect the temperature distribution inside the joint and improve the ability to locate abnormal hot spots.

[0056] The partial discharge sensor 42 is an ultra-high frequency sensor with a frequency range of 300-1500MHz, and is arranged near the shielding structure so that it can effectively couple and collect the high-frequency electromagnetic radiation signal generated by partial discharge, thereby improving the detection sensitivity and anti-interference capability of partial discharge. The insulation monitoring sensor 43 uses a high-frequency current transformer and is installed on the grounding wire in a snap-fit ​​manner, which is convenient for installation and maintenance without power interruption. At the same time, it can monitor the high-frequency components or leakage-related signals in the grounding circuit to characterize the changes in the insulation state of the joint.

[0057] In addition, the metal shielding sleeve 13 is fixed to the outside of the insulating regeneration layer 12 by a constant force fixing spring 14, so that the shielding sleeve maintains stable fit and electrical contact continuity under thermal expansion and contraction and environmental vibration conditions, further improving the stability of the shielding boundary and the consistency of the monitoring signal, thereby enhancing the long-term reliability and engineering applicability of the online monitoring system 40.

[0058] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An intermediate fusion joint for a power cable, characterized in that, This includes the conductor fusion joint, the insulation regeneration layer, and the metal shielding sleeve; The conductor fusion joint is used to form a fusion connection at the joint of two cable cores; The insulating regeneration layer covers the outside of the conductor fused connection portion, and the insulating regeneration layer includes a semiconductive inner shielding portion, an insulating portion, and an outer shielding portion arranged sequentially from the inside to the outside; The metal shielding sleeve covers the outside of the insulating regeneration layer.

2. The intermediate fusion joint of the power cable according to claim 1, characterized in that, The semi-conductive inner shield is formed by wrapping a semi-conductive vulcanized tape, the insulating part is formed by wrapping an insulating vulcanized tape, and the outer shield is formed by conductive ink.

3. The intermediate fusion joint of the power cable according to claim 1, characterized in that, The metal shielding sleeve is a woven mesh formed of tin-plated copper wire, the diameter of the tin-plated copper wire is 0.15mm, and the weaving density is not less than 95%.

4. The intermediate fusion joint of the power cable according to claim 1, characterized in that, Also includes: A constant force fixing spring is sleeved on the outside of the metal shielding sleeve and applies a radial clamping force to the metal shielding sleeve to achieve external fixation.

5. An integration method for an intermediate fusion joint of a power cable, characterized in that, For integrating an intermediate fusion joint of a power cable as described in any one of claims 1 to 4, the integration method comprises: Pre-process several sections of power cable; The pre-treated core ends of the two power cable sections are inserted into the cavity of the melting mold. The pre-molten filler in the melting mold is melted by heating. The molten filler fills the cavity under the guidance of the guide groove, melting and connecting the two core ends into one piece. After cooling, a conductor molten connection is formed. Semiconducting material, insulating material and conductive material are layered and coated on the outside of the conductor fusion connection to form a semiconducting inner shielding part, an insulating part and an outer shielding part arranged sequentially from the inside to the outside. The coated structure is integrally vulcanized to form an insulating regeneration layer. A metal shielding sleeve is wrapped around the outside of the insulating regeneration layer.

6. The integration method for intermediate fusion joints of power cables according to claim 5, characterized in that, The process of pre-processing several sections of power cable is specifically as follows: Strip the outer sheath of the cable end for a first predetermined length to expose the steel armor; A second predetermined length of steel armor is retained at the break point of the outer sheath, and the remaining steel armor is peeled off to expose the inner sheath. At the steel armor break, retain the inner sheath for a third predetermined length, peel off the remaining inner sheath to expose the copper shielding layer; A fourth predetermined length of copper shielding layer is retained at the break point of the inner sheath, and the remaining copper shielding layer is peeled off to expose the outer shielding layer. At the break point of the copper shielding layer, retain a fifth predetermined length of the outer shielding layer, peel off the remaining outer shielding layer, and expose the cable insulation layer. The exposed cable insulation layer is cut into a conical surface at the end, and a sixth predetermined length of inner shielding layer is retained at the end of the conical surface, exposing the wire core for splicing.

7. The integration method for intermediate fusion joints of power cables according to claim 6, characterized in that, The first predetermined length is 700-900mm, the second predetermined length is 20-40mm, the third predetermined length is 40-60mm, the fourth predetermined length is 500-700mm, the fifth predetermined length is 10-20mm, and the sixth predetermined length is 5-15mm.

8. The integration method for intermediate fusion joints of power cables according to claim 5, characterized in that, The melting mold includes a mold body, a melting cavity, and a flow channel; The mold body forms a loading cavity extending in the vertical direction. The lower end of the loading cavity is connected to the melting cavity through a pouring channel, so that the molten filler loaded into the loading cavity melts when heated and enters the melting cavity through the pouring channel. The melting cavity extends laterally and has mating insertion holes formed at its opposite ends for inserting two sections of power cable cores, so that the two sections of cores are coaxially mated in the melting cavity. The guide groove is disposed on the inner wall of the melting cavity and arranged along the extension direction of the melting cavity, and is used to guide the molten filler after melting to flow in a directional manner in the melting cavity to uniformly fill the gap between the wire core ends; The mold body is a graphite-based mold structure, and the mold body is provided with a fastening structure for closing and fixing the molten cavity.

9. An online monitoring system for intermediate fusion joints of power cables, characterized in that, The online monitoring system includes an intermediate fusion joint manufactured using the integrated method for intermediate fusion joints of power cables as described in any one of claims 5-8, and further includes: The multi-parameter monitoring unit includes a temperature sensor embedded in the insulating regeneration layer, a partial discharge sensor integrated between the metal shield and the insulating regeneration layer, and an insulation monitoring sensor installed on the grounding wire. An inductive power supply module is mounted on the power cable body and is used to draw power from the cable and supply power to the monitoring system. The data transmission module is installed on the outside of the metal shielding sleeve and is electrically connected to the multi-parameter monitoring unit. It is used to wirelessly transmit the collected monitoring data to the back-end terminal.

10. The online monitoring system for intermediate fusion joints of power cables according to claim 9, characterized in that, Also includes: A signal conditioning circuit, integrated within the data transmission module, is used to filter and amplify the signal acquired by the multi-parameter monitoring unit. The inductive power supply module includes a Rogowski coil power extraction structure and a backup lithium battery. The Rogowski coil power extraction structure is sleeved on the cable body, and the backup lithium battery is electrically connected to the Rogowski coil power extraction structure.

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