A composite sheath structure high voltage power cable

Abstract

This invention provides a high-voltage power cable with a composite sheath structure, relating to the field of power cable technology. It includes a cable body and a grounding structure installed outside the cable body. The cable body is configured as follows: a conductor, a semi-conductive conductor shielding layer, an XLPE main insulation layer, and a semi-conductive insulation shielding layer are stacked sequentially from the inside out. A semi-conductive buffer layer is fitted onto the outer surface of the semi-conductive insulation shielding layer. This invention employs a contact finger structure driven sequentially by a first shape memory alloy and a second shape memory alloy. At 55-65°C, the sliding extension increases pressure; at 65-75°C, the deflection adheres to the wave crest. Combined with grounding current diversion and heat reduction, and further utilizing semiconductor cooling for active heat dissipation and electromagnetically driven axial migration pre-tightening, the overall design reduces electrochemical erosion between the semi-conductive buffer layer and the corrugated aluminum sheath, extending the cable's service life.

Description

Technical Field

[0001] This invention relates to the field of power cable technology, and in particular to a high-voltage power cable with a composite sheath structure. Background Technology

[0002] High-voltage cross-linked polyethylene (XLPE) insulated power cables are core equipment for urban power transmission networks and power supply to large industrial enterprises. Currently, the widely used structure at home and abroad is: copper or aluminum conductor, semi-conductive conductor shielding layer, XLPE main insulation layer, semi-conductive insulating shielding layer, semi-conductive buffer layer (wrapped with water-blocking tape), corrugated aluminum sheath, and non-metallic outer sheath.

[0003] In particular, because the corrugated aluminum sheath and the semi-conductive buffer layer have intermittent linear contact (crest contact, trough suspension), the leakage current is highly concentrated at the crest contact point. When the buffer layer becomes damp or the water-blocking powder decomposes, free OH groups are generated. - When ions are present, they undergo an alkaline etching reaction with aluminum at high temperatures, generating Al2O3 insulating white spots, which ultimately lead to insulation breakdown and ablation. While smooth aluminum sleeves can achieve surface contact and thus solve the ablation problem, their weld quality is difficult to control, and excessive compression of the buffer layer during thermal expansion and contraction can damage the insulation.

[0004] Currently, existing technologies include material modification, such as neutral water-blocking powder, high-conductivity buffer strips, or post-incident repair, such as injecting semi-conductive repair agents, to treat breakdown and ablation. However, these are all passive defenses or post-incident remedies and cannot fundamentally eliminate the vicious cycle of poor contact and heat accumulation. Summary of the Invention

[0005] To address the technical problem of electrochemical erosion of the buffer layer caused by contact between spacers in existing corrugated aluminum sheathed high-voltage cables, this invention provides a high-voltage power cable with a composite sheath structure.

[0006] The technical solutions provided by the embodiments of the present invention are as follows: The present invention provides a composite sheath structure high-voltage power cable, comprising: a cable body and a grounding structure installed outside the cable body; The cable body is configured as a conductor, a semi-conductive conductor shielding layer, an XLPE main insulation layer, and a semi-conductive insulation shielding layer stacked sequentially from the inside out; a semi-conductive buffer layer is sleeved on the outer surface of the semi-conductive insulation shielding layer. A conductive ring structure is fitted on the outer surface of the semi-conductive buffer layer. The outer peripheral surface of the conductive ring structure faces the inner surface of the corrugated aluminum sheath. The inner surface of the corrugated aluminum sheath has periodic peaks and troughs. A waterproof sheath is installed on the outer surface of the corrugated aluminum sheath. The conductive ring structure is configured as follows: Conductive ring; The contact finger structure is configured as multiple sets of contact finger structures arranged around the surface of the conductive ring sheet. At least a portion of each contact finger structure extends outward along the radial direction of the cable body, and its free end points to the inner surface of the corrugated aluminum sheath. The free end of the contact finger structure forms elastic contact with the crest (a) portion.

[0007] The beneficial effects of the technical solutions provided by the embodiments of the present invention include at least the following: In this invention, a contact finger structure driven sequentially by a first shape memory alloy and a second shape memory alloy is employed. When the local temperature rise of the cable body reaches 55°C to 65°C, the first shape memory alloy contracts, driving the connecting slide and the contact finger body to slide forward radially, increasing the contact pressure between the elastic floating contact head and the crest of the corrugated aluminum sheath, and forcibly reducing the contact resistance. When the temperature rises further to 65°C to 75°C, the second shape memory alloy contracts and drives the contact finger body to deflect by 5° to 15° through a rotating ring, so that the elastic floating contact head fits the crest arc surface at the optimal angle, realizing graded adaptive adjustment of contact pressure and fitting angle, and completely avoiding current concentration. At the same time, by setting it outside the trough... The grounding current diversion ring channel and current injection cavity on the side, when abnormal current still exists after the contact finger structure is pressed, directly guide part of the leakage current from the corrugated aluminum sheath to the ground through the grounding bolt, reducing Joule heating at the contact interface from the source. This is further enhanced by a micro-semiconductor cooling chip array continuously laid along the trough surface, which actively cools when the temperature rise exceeds the warning value, pumping heat out of the cable and preventing heat accumulation. In addition, the electromagnetic drive array composed of a ring-shaped electromagnetic coil interacts with the magnetic edge ring at the side end of the conductive ring plate, pushing the conductive ring plate structure and contact finger structure of adjacent sections along the cable axis towards the abnormal temperature rise area during the early warning stage, increasing the contact finger density in that area and achieving preventative pressure enhancement. This multi-layered synergistic protection—including sequentially driving contact finger pressing and deflection, grounding current diversion and heat reduction, active cooling and heat dissipation, and axial migration pre-tightening—solves the electrochemical ablation problem between the semi-conductive buffer layer and the corrugated aluminum sheath of traditional high-voltage cables, extending the cable's service life. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0009] Figure 1 This is a schematic diagram of a composite sheath structure high-voltage power cable provided in an embodiment of the present invention.

[0010] Figure 2This is a schematic diagram of the cable layer structure of a composite sheath structure high-voltage power cable from another perspective, provided as an embodiment of the present invention.

[0011] Figure 3 This is a cross-sectional view of the internal structure of a composite sheathed high-voltage power cable provided in an embodiment of the present invention.

[0012] Figure 4 This is a schematic diagram showing the structural separation of the cable body of a composite sheathed high-voltage power cable provided in an embodiment of the present invention.

[0013] Figure 5 This is a schematic diagram of the conductive ring structure of a composite sheathed high-voltage power cable provided in an embodiment of the present invention.

[0014] Figure 6 This is a partial structural diagram of the conductive ring structure of a composite sheathed high-voltage power cable provided in an embodiment of the present invention.

[0015] Figure 7 This is a structural diagram of the contact finger structure of a composite sheathed high-voltage power cable provided in an embodiment of the present invention.

[0016] Figure 8 An exploded view of the contact finger structure of a composite sheathed high-voltage power cable provided in an embodiment of the present invention.

[0017] Reference numerals: 100, Cable body; 110, Waterproof sheath; 120, Corrugated aluminum sheath; 120a, Corrugated peak; 120b, Corrugated trough; 130, Outer wear-resistant sheath; 140, Conductive ring structure; 141, Conductive ring; 142, Contact finger structure; 1421, Base; 1422, Contact finger body; 1423, Elastic floating contact head; 1424, Connecting slide; 1425, Restricting groove; 1426, Rotary ring; 1427, Second shape memory Alloy; 1428, First shape memory alloy; 143, Magnetic edge ring; 144, Hole; 150, Semiconducting buffer layer; 160, Semiconducting insulating shield layer; 170, XLPE main insulating layer; 180, Semiconducting conductor shield layer; 190, Conductor; 200, Grounding structure; 210, Grounding current diversion ring channel; 220, Electromagnetic drive array; 230, Grounding pin; 240, Current injection cavity; 300, Micro semiconductor cooling chip array.

[0018] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to this specific structure, device and environment. Those skilled in the art can adjust or modify these devices and environments according to specific needs. Detailed Implementation

[0019] The technical solutions of the present invention will now be described with reference to the accompanying drawings. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies. Furthermore, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0020] like Figures 1 to 8 As shown, an embodiment of the present invention provides a high-voltage power cable with a composite sheath structure, including: a cable body 100 and a grounding structure 200 installed outside the cable body 100; The cable body 100 is configured as a conductor 190, a semi-conductive conductor shielding layer 180, an XLPE main insulation layer 170 and a semi-conductive insulation shielding layer 160 stacked sequentially from the inside to the outside; a semi-conductive buffer layer 150 is sleeved on the outer surface of the semi-conductive insulation shielding layer 160. A conductive ring structure 140 is sleeved on the outer surface of the semiconductive buffer layer 150. The outer peripheral surface of the conductive ring structure 140 faces the inner surface of the corrugated aluminum sheath 120. The inner surface of the corrugated aluminum sheath 120 has periodic peaks 120a and troughs 120b. A waterproof sheath 110 is installed on the outer surface of the corrugated aluminum sheath 120. The conductive ring structure 140 is configured as follows: Conductive ring 141; The contact structure 142 is configured as multiple sets surrounding the surface of the conductive ring 141. At least a portion of each contact structure 142 extends outward along the radial direction of the cable body 100, with its free end pointing towards the inner surface of the corrugated aluminum sheath 120. The free end of the contact structure 142 forms elastic contact with the crest 120a portion.

[0021] It should be noted that the accompanying drawings of this invention show a section of cable structure. The conductor 190 in this invention is a compacted circular copper or aluminum conductor, with a semi-conductive conductor shielding layer 180, an XLPE main insulation layer 170, and a semi-conductive insulating shielding layer 160 sequentially extruded onto its exterior. These three layers are formed in one step using a three-layer co-extrusion process, ensuring a smooth interface without air gaps. The semi-conductive buffer layer 150 is made of wrapped semi-conductive nylon tape or extruded semi-conductive foam elastomer, such as… Figure 2As shown, the thickness is 1.5mm to 2.5mm, and its outer surface can be rolled with annular positioning grooves as needed. The conductive ring structure 140 is composed of multiple independent conductive rings 141 arranged at intervals along the cable axis, with a reserved gap between adjacent conductive rings 141 to allow each ring to independently adapt to local deformation when the cable is bent. The corrugated aluminum sheath 120 is made by longitudinally wrapping aluminum alloy strip and then welding it into a tube by argon arc welding, and then rolling it with a rotary die to form annular or spiral corrugations. The height difference between the crests 120a and the troughs 120b is 3mm to 6mm. Figure 3 As shown, there is a height difference. The waterproof sleeve 110 is made of extruded polyethylene or polyvinyl chloride material with a thickness of not less than 2mm, and is used to prevent external moisture penetration.

[0022] The conductive ring 141 in this invention is formed by stamping a beryllium copper or stainless steel sheet with a thickness of 0.1 mm to 0.3 mm. Its inner surface is bonded to the outer surface of the semi-conductive buffer layer 150, and the outer surface has uniformly distributed base mounting positions for mounting the finger structure 142, i.e. Figure 6 As shown, the base mounting position is hole 144. The finger structure 142 can be arranged at 2mm to 5mm intervals along the circumference of the conductive ring 141, forming a high-density finger array, depending on the actual application. The free end of the finger structure 142 extends beyond the outer surface of the conductive ring 141 in its free state. After the corrugated aluminum sheath 120 is longitudinally welded, the inner surface of the corrugated aluminum sheath 120 pre-compresses the finger structure 142, ensuring that each finger structure 142 is in a pre-compressed state. This forms at least multiple independent contact points at the crest 120a, transforming the original single-point line contact into a multi-point surface contact.

[0023] Furthermore, to improve the reliability and adaptability of the contact structure 142 during long-term cable operation, specifically, an annular groove matching the width of the conductive ring 141 can be rolled out on the outer surface of the semi-conductive buffer layer 150 using a hot press roller. This allows the conductive ring 141 to be embedded in the annular groove, preventing axial movement of the conductive ring 141 when the cable bends or experiences thermal expansion and contraction. Simultaneously, the inner wall of the conductive ring 141 is coated with semi-conductive grease to reduce friction with the buffer layer and maintain electrical continuity.

[0024] In one possible implementation, the finger structure 142 is configured for sequential triggering, including: A first shape memory alloy 1428 is arranged along the axial direction of the cable body 100. One end of the first shape memory alloy 1428 is connected to a base 1421, and the other end is connected to a connecting slider 1424. When the temperature around the contact structure 142 reaches a first threshold, the first shape memory alloy 1428 performs a first driving action. The first shape memory alloy 1428 undergoes a phase transformation from martensite to austenite and contracts along the axial direction, driving the connecting slider 1424 to slide along the outer surface of the conductive ring 141 toward the crest 120a. The finger body 1422 is rotatably connected to the connecting slide 1424 at its root, and its free end points toward the inner surface of the corrugated aluminum sheath 120. The second shape memory alloy 1427 is arranged parallel to the side of the first shape memory alloy 1428. A rotating ring 1426 is connected to one side end of the second shape memory alloy 1427, and the other end is connected to the base 1421. The rotating ring 1426 is rotatably connected to the side end of the connecting slider 1424 and connected to the finger body 1422. When the temperature reaches a second threshold higher than the first threshold, the second shape memory alloy 1427 performs a second driving action. The second shape memory alloy 1427 undergoes a phase transformation from martensite to austenite and contracts, driving the finger body 1422 to deflect and rotate around the root relative to the outer surface of the conductive ring 141. Furthermore, the motion patterns of the first driving action and the second driving action are different.

[0025] It should be noted that the base 1421 is fixedly mounted on the mounting position on the outer surface of the conductive ring 141, and its interior has a cavity for accommodating the first shape memory alloy 1428 and the second shape memory alloy 1427. The first shape memory alloy 1428 is a wire with a diameter of 0.3 mm to 0.4 mm, such as... Figure 8As shown, the cable is in a linear tensioned state, with one end fixed to the far end of the base 1421 by crimping or welding, and the other end connected to the connecting slide 1424. The connecting slide 1424 has a concave structure, with its bottom embedded in the limiting groove 1425 on the surface of the base 1421, allowing it to move axially within the limiting groove 1425. When the cable experiences a localized temperature rise due to poor contact, reaching 55°C to 65°C, the first shape memory alloy 1428 undergoes a martensitic-to-austenitic phase transformation, axially contracting and causing the connecting slide 1424 to slide towards the crest 120a near the base 1421. This causes the entire contact finger body 1422 to extend radially outward, increasing the clamping force on the corrugated aluminum sheath 120 near the base 1421. When the temperature further rises to 65°C to 75°C, the second shape memory alloy 1427 is triggered, causing a martensitic-to-austenitic phase transformation in the second shape memory alloy 1427. This axial contraction pulls the root of the finger body 1422 via the rotating ring 1426, causing the finger body 1422 to deflect 5° to 15° around the micro-axis on the connecting slider 1424. This allows the contact surface of the free end of the finger body 1422 to better fit the arc-shaped inner surface of the corrugated aluminum sheath 120 near the base 1421, where the wave crest 120a is located. The sequential triggering of the first shape memory alloy 1428 and the second shape memory alloy 1427 effectively avoids motion interference, and after cooling, the deflection is restored first, followed by the sliding, achieving automatic reset.

[0026] The first shape memory alloy 1428 is a wire with a diameter of 0.3 mm to 0.4 mm, and the second shape memory alloy 1427 is a wire with a diameter of 0.1 mm to 0.2 mm.

[0027] In one possible implementation, elastic floating contact heads 1423 are installed on both sides of the free end of the finger body 1422. The elastic floating contact heads 1423 are buoyantly connected to the finger body 1422 through micro elastic elements. The outer surface of the elastic floating contact head 1423 is arc-shaped or hemispherical and is used to form surface contact with the inner surface of the wave crest 120a. The conductive ring 141 has a hole 144 on its side end surface corresponding to the base 1421; A thin-film thermocouple is embedded in the surface of the finger body 1422.

[0028] It should be noted that the elastic floating contact head 1423 of the present invention is made of copper-tungsten alloy or silver-plated beryllium copper, and a miniature helical spring or wave spring is provided on its back, allowing the elastic floating contact head 1423 to have a floating margin in the radial direction. When the contact angle of the finger body 1422 is imperfect due to the position displacement of the crest 120a in the corrugated aluminum sheath 120, the elastic floating contact head 1423 can automatically compensate to ensure that each elastic floating contact head 1423 forms a stable contact with the inner surface of the corrugated aluminum sheath 120. The two elastic floating contact heads 1423 are respectively arranged on both sides of the free end of the finger body 1422, forming a forked structure or an outward V-shaped structure, further increasing the number of contact points. The hole 144 penetrates the wall thickness of the conductive ring 141 and is used to inject insulating curing adhesive when installing the base 1421 or to pour de-crosslinking agent during subsequent maintenance. The thin-film thermocouple is made of NiCr / NiSi thin film material and is deposited on the surface of the finger body 1422 by magnetron sputtering. The lead wire of the thin-film thermocouple is led out along the surface of the finger body 1422, the connecting slider 1424, and the back of the conductive ring 141 to a temperature acquisition device outside the cable body 100, which is used to monitor the temperature change of each finger point area in real time.

[0029] In one possible implementation, the grounding structure 200 includes: Grounding current diversion ring channel 210, wherein the grounding current diversion ring channel 210 is disposed outside the trough 120b; At least one current injection cavity 240 is provided at the position of the corrugated aluminum sheath 120 corresponding to the grounding current diversion ring channel 210. The current injection cavity 240 penetrates the wall thickness of the corrugated aluminum sheath 120 and is filled with a conductive medium to form an electrical connection path from the inner surface of the corrugated aluminum sheath 120 to the grounding current diversion ring channel 210. A grounding bolt 230 is installed at the bottom of the grounding current diversion ring channel 210. The grounding bolt 230 is connected to the earth and is used to guide a portion of the leakage current flowing through the corrugated aluminum sheath 120 to the earth after the contact finger structure 142 performs the driving action, thereby reducing the heat generation at the contact interface between the free end of the contact finger structure 142 and the wave crest 120a.

[0030] Specifically, the grounding current diversion ring channel 210 is composed of annular metal grooves, each corresponding to a corrugated aluminum sheath 120 section. The annular metal grooves are made of tin-plated copper strip or stainless steel strip bent into shape, and their inner walls are tightly attached to the outer surface of the trough of the corrugated aluminum sheath 120. An insulating film can be placed between the two, or they can be in direct contact. Figure 4As shown, the current injection channel 240 is located at the bottom of the trough of the corrugated aluminum sheath 120 and is elongated. The conductive medium filling the channel is a low-melting-point alloy, such as a tin-bismuth alloy or conductive silver paste, which is solid at room temperature. When a shunt needs to be activated, it is heated above its melting point by external electricity, and the medium melts to form a conductive path. The grounding bolt 230 is a copper bolt that passes through the waterproof sheath 110 and the outer wear-resistant sleeve 130 and connects to the external grounding busbar. When the contact finger structure 142 detects an abnormal temperature rise and performs a clamping action in conjunction with the thin-film thermocouple, the controller connected to the cable, such as a PLC controller, controls the shunt switch of this section to close, so that part of the leakage current is injected into the current injection channel 240. After the grounding current diversion ring channel 210 is guided, it directly enters the ground through the grounding bolt 230, thereby reducing the amount of current flowing through the contact interface between the contact finger structure 142 and the corrugated aluminum sheath 120 and reducing Joule heating.

[0031] It should be noted that a polyimide coating can be applied to the surface of the finger structure 142 for insulation protection. At the same time, a semi-conductive alumina ceramic coating is electroplated on the surface of the conductive ring 141 to give the interface resistivity and smooth the electric field distribution.

[0032] In one possible implementation, a miniature self-sealing micro-valve is pre-installed in the current injection channel 240. The miniature self-sealing micro-valve is normally closed when no external control signal is connected, and the circuit is connected when an external voltage is applied to trigger it. The surface of the valley 120b is provided with a micro-semiconductor cooling chip array 300 continuously laid along the axial direction.

[0033] The miniature self-sealing micro-valve employs a diaphragm valve structure molded from silicone rubber or fluororubber, with conductive metal particles embedded within the valve core. When no voltage is applied, the valve core tightly seals the cavity under the elastic force of the rubber, preventing moisture from seeping into the cable. When an external PLC controller applies DC voltage to the miniature self-sealing micro-valve, the piezoelectric ceramic or electrostatic drive element within the valve core activates, causing the valve core to move slightly. The conductive metal particles form a conductive chain, connecting the circuit. After power is cut off, the valve core automatically resets, restoring the seal. The miniature semiconductor cooling array 300 consists of Peltier elements, continuously pasted or embedded along the surface of the trough 120b. Its cold end is in close contact with the inner wall of the trough 120b of the corrugated aluminum sheath 120, while the hot end contacts the waterproof sheath 110 via thermally conductive silicone. When the temperature rise exceeds a warning value, external power activates the miniature semiconductor cooling array 300, pumping interface heat from the cold end to the hot end and dissipating it through the cable sheath, forcibly reducing the temperature of the contact area of ​​the finger structure 142.

[0034] In one possible implementation, a zinc oxide varistor or a gas discharge tube is connected in series in the grounding circuit of the grounding current diversion shunt ring channel 210 to suppress transient overvoltage during the switching of the shunt ring. The grounding circuit of the grounding current diversion ring channel 210 is also connected in series with a segmented fuse or current limiter. When the grounding current exceeds the predetermined short-circuit current threshold, the electrical connection between the grounding current diversion ring channel 210 and the corrugated aluminum sheath 120 is automatically disconnected.

[0035] The zinc oxide varistor is used to instantly conduct and absorb the overvoltage energy when the operating overvoltage generated during the shunt loop closure or opening exceeds a certain value, protecting the contact interface and other insulating components from damage. The gas discharge tube serves as backup protection, activating under higher amplitude transient overvoltages such as lightning strikes. The sectionalizing fuse is used to quickly blow and automatically isolate the faulty section when a ground fault causes a short-circuit current to flow through the shunt loop, preventing the corrugated aluminum sheath from overheating and burning through. The current limiter uses a positive temperature coefficient thermistor or electronic switch; when the detected current exceeds a threshold, it automatically increases the loop impedance to limit the current amplitude.

[0036] In one possible implementation, an electromagnetic drive array 220 is mounted on the outside of the corrugated aluminum sheath 120. The electromagnetic drive array 220 includes annular electromagnetic coils arranged at intervals along the laying path of the cable body 100. The annular electromagnetic coils are openably and closedly fitted around the outer periphery of the grounding current diversion ring channel 210, and the two are separated by a shielding ring. A magnetic edge ring 143 is installed on the side end of the conductive ring 141. The magnetic edge ring 143 enables the conductive ring 141 and the contact finger structure 142 to move along the axial direction of the cable body 100 towards the abnormal temperature rise area.

[0037] Each annular electromagnetic coil in the electromagnetic drive array 220 consists of a ferrite core and windings, with an inner diameter slightly larger than the outer diameter of the grounding current diversion ring channel 210. It is designed to be openable and closable via a ring clamp or hinge structure for easy on-site installation. The electromagnetic drive arrays 220 are arranged in a axially spaced manner along the cable, and each group of electromagnetic drive arrays 220 is driven by an independent power supply module, generating a traveling wave magnetic field along the cable axis.

[0038] The shielding ring is a thin ring-shaped sheet of copper or aluminum, fitted between the electromagnetic drive array 220 and the grounding current diversion ring channel 210, used to block the interference of the magnetic field on the electronic components inside the grounding current diversion ring channel 210. The magnetic edge ring 143 on the side end of the conductive ring 141 is made of neodymium iron boron permanent magnet material, and the magnetization direction is radial or axial. The magnetic poles generated by it interact with the traveling wave magnetic field generated by the electromagnetic coil, causing the conductive ring 141 and its contact finger structure 142 to move along the cable axis as a whole. The moving speed can be controlled by adjusting the coil current frequency. When the temperature sensor built into the cable body 100 detects an early temperature rise anomaly in a certain section but has not yet reached the trigger threshold of the first shape memory alloy 1428 and the second shape memory alloy 1427, the PLC controller drives the electromagnetic array to push the conductive ring 141 and its contact finger structure 142 of the adjacent normal section to the abnormal section, increasing the contact finger density of the abnormal section and performing preventive pressure enhancement in advance.

[0039] It should be noted that the main application scenario of the electromagnetic drive array 220 of the present invention is preventive active migration rather than emergency rapid drive. For example, when the temperature sensor in the cable body 100 detects that the temperature of a certain section is continuously and slowly rising over a period of time, and this temperature rise is lower than the first trigger threshold of 55°C, the PPC controller determines that there is a gradual contact degradation trend in that section. At this time, the electromagnetic drive array 220 is activated to slowly push one or two conductive ring structures 140 from adjacent sections to that section, increasing the contact density and preventing the degradation trend from worsening.

[0040] In one possible implementation, the first shape memory alloy 1428 and the second shape memory alloy 1427 are both made of ultra-high conductivity multi-group shape memory alloys, with a conductivity higher than that of pure Ni-Ti alloy. The phase transition temperature bandwidth of the first shape memory alloy 1428 is configured to be 55±2℃; The phase transition temperature bandwidth of the second shape memory alloy 1427 is configured to be 70±5℃; A micro heat sink is provided between the first shape memory alloy 1428 and the second shape memory alloy 1427. The micro heat sink is installed inside the base 1421. The micro heat sink is made of a high thermal conductivity metal and is used to absorb the latent heat of phase change released by the first shape memory alloy 1428 and delay the heat conduction to the second shape memory alloy 1427, so as to ensure that the temperature of the second shape memory alloy 1427 only rises to its phase change range after the first shape memory alloy 1428 has completed the phase change contraction. The mass percentage of copper in the first shape memory alloy 1428 is greater than the mass percentage of copper in the second shape memory alloy 1427, so that the conductivity of the first shape memory alloy 1428 is higher than that of the second shape memory alloy 1427 under the same temperature conditions.

[0041] The micro heat sink is a thin sheet made of pure copper or copper-tungsten alloy, with a thickness of 0.1 mm to 0.2 mm. It is embedded inside the base 1421 and located between the first shape memory alloy 1428 and the second shape memory alloy 1427. One end of the heat sink contacts the fixed end of the first shape memory alloy 1428, and the other end contacts the outer shell of the base 1421 to form a heat dissipation path. When the first shape memory alloy 1428 releases latent heat during phase change, the heat sink rapidly absorbs the heat and conducts it to the base 1421 and the conductive ring 141, significantly slowing down the temperature rise rate in the area of ​​the second shape memory alloy 1427 and ensuring sequential triggering. Furthermore, the difference in copper content also results in the first shape memory alloy 1428 having a lower resistivity, leading to a faster response when electric heating-assisted triggering may be used.

[0042] It should be noted that the first shape memory alloy 1428 can be composed of nickel, titanium, copper and silver in mass percentages according to actual conditions. The phase transformation temperature is precisely controlled at 55℃±2℃ through aging treatment, and the end temperature of the reverse martensitic phase transformation does not exceed 60℃.

[0043] The second shape memory alloy 1427 is composed of nickel, titanium, copper and iron in mass percentages, with the phase transformation temperature controlled at 70℃±5℃ and the inversion phase transformation start temperature not lower than 65℃.

[0044] In one possible implementation, the sidewall of the base 1421 is provided with a limiting groove 1425 for sliding of the connecting slider 1424.

[0045] The limiting groove 1425 is an elongated opening penetrating the sidewall of the base 1421. Its width matches the width of the sliding portion of the connecting slide 1424, and its length matches the contraction stroke of the first shape memory alloy 1428. Limiting bosses are provided at both ends of the limiting groove 1425 to prevent the connecting slide 1424 from overtraveling and dislodging. The inner wall of the limiting groove 1425 is coated with a molybdenum disulfide or diamond-like carbon anti-friction coating to reduce sliding friction. The limiting groove 1425 ensures that the connecting slide 1424 maintains strict axial guidance during sliding, preventing fatigue fracture of the first shape memory alloy 1428 due to bending caused by misalignment.

[0046] In one possible implementation, the waterproof sheath 110 is covered with an outer wear-resistant sheath 130.

[0047] The outer abrasion-resistant sleeve 130 is extruded from high-density polyethylene or nylon, and its outer surface may have color markings or embossed markings to distinguish different phase sequences. A semi-conductive tape or graphite coating may be installed between the inner wall of the abrasion-resistant sleeve and the waterproof sheath 110 to prevent static electricity accumulation. The outer abrasion-resistant sleeve 130 mainly protects the cable from dragging abrasion during laying and from external mechanical impacts during operation, while also improving the overall roundness of the cable.

[0048] In summary, the composite sheath structure high-voltage power cable designed in this invention solves the problem of buffer layer erosion in traditional high-voltage cables by sequentially driving the contact finger structure 142, the first shape memory alloy 1428, and the second shape memory alloy 1427, and integrating the grounding structure 200 into the annular gap between the semiconductive buffer layer 150 and the corrugated aluminum sheath 120. Compared with existing technologies, this invention achieves current shunting and heat reduction based on self-adjustment of contact pressure and angle, and further improves the efficiency of current shunting and heat reduction through active heat removal. Simultaneously, preventative treatment further reduces the problem of cable buffer layer erosion. All structures are based on mature machining and material processing technologies, possessing high industrial feasibility.

[0049] The beneficial effects of the technical solutions provided by the embodiments of the present invention include at least the following: In this invention, by employing a first shape memory alloy 1428 and a second shape memory alloy 1427 that are sequentially triggered, the contact finger structure 142 is driven under different temperature conditions, thereby achieving graded adjustment of the contact state of the cable semiconducting buffer layer 150. Firstly, when the contact surface experiences an early temperature rise of 55°C to 65°C due to minor defects, the first shape memory alloy 1428 contracts, driving the contact finger body 1422 to slide forward, increasing the contact pressure and forcibly reducing the contact resistance. If the temperature rise continues to 65°C to 75°C, the second shape memory alloy 1427 drives the contact finger body 1422 to deflect, causing the elastic floating contact head 1423 at the free end of the contact finger body 1422 to fit the crest 120a arc surface of the corrugated aluminum sheath 120 at an optimal angle, further uniformly distributing the contact pressure and completely avoiding current concentration. Secondly, by setting up a grounding current diversion loop channel 210, when abnormal current still exists after the contact finger body 1422 is compressed, part of the leakage current can be directly introduced into the ground from the corrugated aluminum sheath 120 through the current injection cavity 240, reducing the heat generation at the contact interface from the source. Thirdly, the micro-semiconductor cooling chip array 300 laid at the trough 120b can actively cool when the temperature rise exceeds the warning value, pumping heat out of the cable and preventing heat accumulation. Furthermore, the electromagnetic drive array 220, in conjunction with the magnetic edge ring 143, can axially push the contact finger structure 142 of adjacent sections to the abnormal area during the early warning stage, achieving preventative pressure enhancement, reducing the risk of cable buffer layer ablation, and all of its structures can be recycled or repaired in sections.

[0050] It should be noted that during the cable manufacturing stage, the high-voltage power cable with the composite sheath structure described in this invention is assembled according to the following steps.

[0051] Step 1: Lay out and straighten conductor 190, and then sequentially apply three layers of co-extruded semi-conductive conductor shielding layer 180, XLPE main insulation layer 170 and semi-conductive insulation shielding layer 160 on conductor 190 to form an insulated wire core.

[0052] Step 2: Wrap or extrude a semi-conductive buffer layer 150 around the insulated wire core, and emboss an annular positioning groove on the outer surface of the semi-conductive buffer layer 150 using a heated knurling roller.

[0053] Step 3: Prefabricate the conductive ring structure 140. This involves stamping a beryllium copper strip into a ring with an inner diameter matching the outer diameter of the buffer layer. The outer surface of the ring is then circumferentially machined with mounting holes for the base of the finger structure 142. The base 1421 of the prefabricated finger structure 142 is then fixed into the hole 144 using micro-spot welding or laser welding.

[0054] The assembly process of each finger structure 142 is as follows: First, one end of the first shape memory alloy 1428 is pressed onto the far end of the base 1421, and the other end is connected to the connecting slider 1424; then, one end of the second shape memory alloy 1427 is connected to the base 1421, and the other end is connected to the root of the finger body 1422 through the swivel ring 1426; elastic floating contact heads 1423 are installed on both sides of the free end of the finger body 1422, and a micro spring is pre-installed on the back; finally, the swivel at the root of the finger body 1422 is inserted into the shaft hole of the connecting slider 1424, and the connecting slider 1424 is installed into the limiting groove 1425 on the side wall of the base 1421. A micro heat sink is embedded inside the base 1421, positioned between the first shape memory alloy 1428 and the second shape memory alloy 1427. A thin film thermocouple is deposited on the surface of the finger body 1422 and signal lines are led out.

[0055] Step 4: Place the assembled conductive ring structure 140 one by one onto the semi-conductive buffer layer 150, so that the conductive ring 141 is completely embedded in the annular positioning groove.

[0056] Step 5: Install the magnetic edge ring 143, a neodymium iron boron permanent magnet ring, radially magnetized on the side end of the conductive ring 141 by adhesive or snap-fit.

[0057] Step Six: The aluminum alloy strip for the corrugated aluminum sheath 120 is longitudinally wrapped around the outside of the conductive ring structure 140. The longitudinal seam is welded by argon arc welding, and then rolled by a rotary die to form annular corrugations, so that the crests 120a correspond to the free ends of the contact finger structure 142, and the troughs 120b correspond to the gaps between adjacent contact finger points. The compression amount is controlled during the rolling process to give the free ends of the contact finger structure 142 an initial preload.

[0058] Step 7: On the outer surface of the trough 120b of the corrugated aluminum sheath 120, install the grounding current-diverting ring channel 210 by adhesive or clips, and form a current injection channel 240 by laser drilling at the corresponding position. The channel is filled with tin-bismuth alloy and pre-installed with a miniature self-sealing valve. A zinc oxide varistor, a gas discharge tube, and a segmented fuse are connected in series in the grounding circuit of the grounding current-diverting ring channel 210, and led out through the grounding bolt 230.

[0059] Step 8: Attach the micro-semiconductor cooling array 300 axially along the surface of the trough 120b, with the cold side facing inward and the hot side facing outward, and lead out the power supply terminal through the wire.

[0060] Step 9: Extrude a waterproof sheath 110 onto the outside of the wrinkled aluminum sheath 120, and then extrude an outer wear-resistant sheath 130 onto the outside of the waterproof sheath 110.

[0061] Step 10: On the outside of the cable outer sheath, install an electromagnetic drive array 220 every 15 meters along the laying path. The electromagnetic coil is isolated from the grounding current diversion channel 210 through the shielding ring, and the power supply and control cables of the coil are connected to the external PLC controller.

[0062] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-voltage power cable with a composite sheath structure, characterized in that, include: The cable body and the grounding structure installed outside the cable body; The cable body is configured as a conductor, a semi-conductive conductor shielding layer, an XLPE main insulation layer, and a semi-conductive insulation shielding layer stacked sequentially from the inside out; a semi-conductive buffer layer is sleeved on the outer surface of the semi-conductive insulation shielding layer. A conductive ring structure is fitted on the outer surface of the semi-conductive buffer layer. The outer peripheral surface of the conductive ring structure faces the inner surface of the corrugated aluminum sheath. The inner surface of the corrugated aluminum sheath has periodic peaks and troughs. A waterproof sheath is installed on the outer surface of the corrugated aluminum sheath. The conductive ring structure is configured as follows: Conductive ring; The contact finger structure is configured as multiple sets of contact finger structures arranged around the surface of the conductive ring sheet. At least a portion of each contact finger structure extends outward along the radial direction of the cable body, and its free end points to the inner surface of the corrugated aluminum sheath. The free end of the contact finger structure forms elastic contact with the crest portion. The finger structure is configured for sequential triggering, including: A first shape memory alloy is arranged along the axial direction of the cable body. One end of the first shape memory alloy is connected to a base, and the other end is connected to a connecting slider. When the temperature around the finger structure reaches a first threshold, the first shape memory alloy performs a first driving action. The first shape memory alloy undergoes a phase transformation from martensite to austenite and contracts along the axial direction, driving the connecting slider to slide along the outer surface of the conductive ring towards the crest direction. The finger body has its root connected to the connecting slide in a rotatable manner, and its free end points to the inner surface of the corrugated aluminum sheath. A second shape memory alloy is disposed parallel to the side of the first shape memory alloy. A rotating ring is connected to one end of the second shape memory alloy and the other end is connected to a base. The rotating ring is rotatably connected to the side end of the connecting slider and connected to the finger body. When the temperature reaches a second threshold higher than the first threshold, the second shape memory alloy performs a second driving action. The second shape memory alloy undergoes a phase transformation from martensite to austenite and contracts, driving the finger body to deflect and rotate relative to the outer surface of the conductive ring plate around the root. Furthermore, the motion patterns of the first driving action and the second driving action are different; Both sides of the free end of the finger body are equipped with elastic floating contact heads. The elastic floating contact heads are buoyantly connected to the finger body through micro elastic elements. The outer surface of the elastic floating contact head is arc-shaped or hemispherical, which is used to form surface contact with the inner surface of the wave crest. The conductive ring has holes on its side end surface corresponding to the base; A thin-film thermocouple is embedded in the surface of the finger body.

2. The high-voltage power cable with a composite sheath structure according to claim 1, characterized in that, The grounding structure includes: A grounding current diversion ring channel is provided on the outside of the trough; At least one current injection cavity is provided at the position of the corrugated aluminum sheath corresponding to the grounding current diversion ring channel. The current injection cavity penetrates the wall thickness of the corrugated aluminum sheath and is filled with a conductive medium to form an electrical connection path from the inner surface of the corrugated aluminum sheath to the grounding current diversion ring channel. A grounding bolt is installed at the bottom of the grounding current diversion ring channel. The grounding bolt is connected to the earth and is used to guide a portion of the leakage current flowing through the corrugated aluminum sheath into the earth after the finger structure performs the driving action, thereby reducing the heat generation at the interface between the free end of the finger structure and the crest.

3. The high-voltage power cable with a composite sheath structure according to claim 2, characterized in that, The current injection cavity is pre-installed with a miniature self-sealing micro-valve. The miniature self-sealing micro-valve is normally closed when no external control signal is connected, and the circuit is connected when an external voltage is applied to trigger it. The surface of the trough is provided with an array of micro-semiconductor cooling chips that are continuously laid along the axial direction.

4. The high-voltage power cable with a composite sheath structure according to claim 2, characterized in that, A zinc oxide varistor or a gas discharge tube is connected in series in the grounding circuit of the grounding current diversion ring channel to suppress transient overvoltage during the switching of the current diversion ring. The grounding circuit of the grounding current diversion ring channel is also connected in series with a segmented fuse or current limiter. When the grounding current exceeds the predetermined short-circuit current threshold, the electrical connection between the grounding current diversion ring channel and the corrugated aluminum sheath is automatically disconnected.

5. The high-voltage power cable with a composite sheath structure according to claim 1, characterized in that, An electromagnetic drive array is installed on the outside of the corrugated aluminum sheath. The electromagnetic drive array includes annular electromagnetic coils arranged at intervals along the cable body laying path. The annular electromagnetic coils are openably and closedly fitted around the outer periphery of the grounding current diversion ring channel, and the two are separated by a shielding ring. A magnetic edge ring is installed on the side end of the conductive ring plate, which enables the conductive ring plate and the contact finger structure to move along the axial direction of the cable body towards the abnormal temperature rise area.

6. The high-voltage power cable with a composite sheath structure according to claim 1, characterized in that, Both the first and second shape memory alloys are made of ultra-high conductivity multi-group shape memory alloys, with conductivity higher than that of pure Ni-Ti alloys. The phase transition temperature bandwidth of the first shape memory alloy is configured to be 55±2℃; The phase transition temperature bandwidth of the second shape memory alloy is configured to be 70±5℃; A micro heat sink is provided between the first shape memory alloy and the second shape memory alloy. The micro heat sink is installed inside the base and is made of a high thermal conductivity metal. It is used to absorb the latent heat of phase change released by the first shape memory alloy and delay the heat conduction to the second shape memory alloy, so as to ensure that the temperature of the second shape memory alloy only rises to its phase change range after the first shape memory alloy completes the phase change contraction. The mass percentage of copper in the first shape memory alloy is greater than that in the second shape memory alloy, resulting in a higher conductivity of the first shape memory alloy under the same temperature conditions compared to the second shape memory alloy.

7. The high-voltage power cable with a composite sheath structure according to claim 1, characterized in that, The base has a limiting groove on its side wall for the sliding of the connecting slide.

8. The high-voltage power cable with a composite sheath structure according to claim 1, characterized in that, The waterproof sheath is covered with an outer wear-resistant sleeve.

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