A comprehensive cable for energy storage power station, a preparation method and application thereof

Abstract

The application discloses a kind of comprehensive cable for energy storage power station, preparation method and application, belong to new energy and smart grid high-end equipment technical field.The cable includes successively from inside to outside: power transmission unit, function decoupling type inner insulation layer, low thermal resistance filling and sizing layer, first axial high-thermal-conductivity channel, composite phase change heat storage layer, corrugated metal sheath, basic polyurea layer, inner repair layer and outer repair layer.The application solves the systemic problems of high steady-state temperature rise, strong switching thermal shock, environmental damage accumulation and low-temperature start brittleness of energy storage short-distance cable by the hierarchical heat management topology of "radial heat bridge flow guide→axial heat rail discharge→phase change transient buffer→fault timing repair", realizes current-carrying capacity improvement, transient temperature rise inhibition and long-period maintenance-free.

Description

Technical Field

[0001] This invention relates to the field of high-end equipment technology for new energy and smart grids, and in particular to a composite cable for energy storage power stations, its preparation method, and its application. Background Technology

[0002] Electrochemical energy storage features flexible dispatch and fast response, enabling it to address grid security and control issues following the large-scale integration of new energy sources. However, as the capacity of individual electrochemical energy storage units leaps to the GWh level, the thermal safety and long-term reliability of power cables, which serve as the connection between battery clusters and the power supply system (PCS), directly determine the system's operating efficiency.

[0003] Current energy storage cables exhibit the following systemic pain points in engineering applications: 1. Single steady-state heat dissipation path: Traditional cables rely on radial heat conduction to the outer sheath, resulting in high thermal resistance and low efficiency; the engineering reality of excellent heat sink value at both ends of short-distance cables (≤50m) is ignored, leading to continuous accumulation of conductor temperature rise and limited current carrying capacity. 2. Transient thermal shock during charge / discharge switching: Sudden current surges during high-rate charge / discharge switching (<30s) generate thermal spikes, easily triggering battery thermal runaway protection or accelerating insulation aging; existing structures lack a mechanism to buffer instantaneous peak thermal capacity. 3. Accumulated damage and low-temperature embrittlement in outdoor environments: Energy storage power stations are often exposed to ultraviolet radiation, dust, humidity, and extreme cold environments down to -30℃, making the outer sheath prone to cracking and the insulation layer hardening in a cold state; the first full load in the early morning can easily trigger partial discharge or breakdown. 4. Lack of system synergy in functional stacking: Existing patents mostly focus on single performance (such as adding only thermally conductive fillers or only phase change materials), failing to resolve the technical contradictions of "difficult radial heat intake - weak axial heat output - transient buffer repair - fault repair false triggering", and lacking a system-level architecture that couples thermal, electrical, mechanical and intelligent four dimensions.

[0004] Therefore, there is an urgent need to develop a high-strength aluminum alloy material suitable for pre-twisted wires to overcome the defects mentioned above. Summary of the Invention

[0005] To overcome the above-mentioned technical defects, the present invention provides a composite cable for energy storage power stations, a preparation method thereof, and its application, in order to solve the problems involved in the background art.

[0006] In a first aspect, the present invention provides a composite cable for energy storage power stations. Power transmission unit; The functionally decoupled inner insulation layer comprises an inner layer of modified cross-linked polyolefin, an outer layer of thermally conductive silicone rubber, and an interfacial coupling transition layer disposed between the two layers. The low thermal resistance filler and shaping layer is composed of addition-type thermally conductive silicone gel and thermally conductive polyimide tape. A primary axial high thermal conductivity channel comprises multiple highly oriented graphene fiber bundles arranged along the cable axis on the outer surface of the wrapping tape, with a flexible anti-bending protective mesh covering the outside of the fiber bundles; A composite phase change thermal storage layer is wrapped around the outside of the primary axial high thermal conductivity channel and includes a foam metal skeleton and a phase change medium filling the pores of the foam metal skeleton. A corrugated metal sheath is fitted over the outside of the composite phase change thermal storage layer. An expansion compensation cavity is reserved between the inner wall of the sheath and the phase change thermal storage layer. A welded sealing cap is provided at the end of the corrugated metal sheath. A base polyurea layer is sprayed onto the outer surface of the corrugated metal sheath; The inner repair layer is formed by a gradient blending process of thermo-repair microcapsules and polyurea matrix. The outer repair layer is composed of fluorocarbon modified polyurea, coumarin derivatives and core-shell structured nano-TiO2, and is sprayed on the outside of the inner repair layer.

[0007] Preferably or optionally, the primary axial high thermal conductivity channel is separated from the corrugated metal sheath at the cable terminal and connected to an external heat sink.

[0008] Preferably or optionally, the penetration depth between the inner repair layer and the surface layer of the base polyurea layer is 80-150 μm.

[0009] Preferably or optionally, the phase change medium has a phase change temperature of 68-75℃, a latent heat of ≥180J / g, and a thermal conductivity of 10-30W / (m·K) for the composite phase change heat storage layer.

[0010] Preferably or optionally, the triggering temperature of the inner repair layer is 78-85℃, and a hysteresis isolation zone of ≥3℃ is provided between it and the phase change temperature of the phase change medium.

[0011] Preferably or optionally, the sealing cap and the end of the corrugated metal sheath are fixedly connected by laser welding or argon arc welding. The center of the welded sealing cap is provided with a conductor lead-out hole, through which the power core of the power transmission unit passes. The annular gap between the power core and the wall of the lead-out hole is filled with high-temperature resistant sealant. The end of the corrugated metal sheath also has an exposed section of not less than 10mm, which is pressed or welded to the wiring terminal or the heat dissipation base of the equipment.

[0012] Preferably or optionally, it further includes an optical unit or a control unit; the optical unit is placed in the fixed sector of the cable core, coated with a low thermal resistance thermally conductive coating on the side facing the power transmission unit, and covered with an aerogel thermal insulation sleeve on the back side; the control unit is covered with an aluminum foil-tinned copper wire braided shielding layer, and the shielding layer is thermally coupled to the primary axial high thermal conductivity channel.

[0013] Secondly, the present invention also provides a method for preparing a composite cable for an energy storage power station, comprising: S1 conductor stranded, double-layer insulation co-extruded and subjected to plasma surface treatment, thermal stress annealing; S2 cable stranding, synchronous insertion of optical unit or control unit, injection of thermally conductive silicone gel, and wrapping with thermally conductive polyimide tape; S3 graphene fiber bundles are fixed at axial points and wrapped with flexible anti-bending protective netting; The S4 cable core is inserted into the hollow corrugated tube, both ends are temporarily sealed and vacuum injection ports are reserved. After preheating, molten phase change medium is injected under a predetermined vacuum degree, and then pressure is maintained and cooled to solidify. S5 bellows end caps are fitted with sealing caps; The S6 outer sheath is coated with a three-layer gradient spray, including a base polyurea layer, an inner repair layer gradient blending spray, and an outer repair layer spray, controlling the surface drying time to complete surface enrichment.

[0014] Preferably or optionally, in step S1, the plasma surface treatment power is 300W, the treatment time is 3min, and after the plasma surface treatment, silane coupling agent is impregnated; the annealing temperature is 90℃, and the annealing time is 2h. Preferably or optionally, in step S2, the silicone gel is degassed under vacuum at ≤50 Pa, the curing temperature of the silicone gel is 85°C, the curing time is 1.5 h, and the overlap rate of the polyimide tape is 20%. Preferably or optionally, in step S3, PI tape is used for fixing points, and the point spacing is ≤50mm; the fixing pitch should avoid high strain areas. Preferably or optionally, in step S4, the molten phase change medium is preheated to 85°C under a vacuum of ≤50Pa and then injected at a injection temperature of 95°C for 2 hours. Preferably or optionally, in step S6, the base polyurea layer is sprayed at a temperature ≤55°C, the inner repair layer is sprayed using a gradient blending method with a blending ratio of 15wt%, the surface drying delay controls the enrichment depth, and the overall curing temperature is 60°C.

[0015] Thirdly, the present invention also provides an application of a composite cable for energy storage power stations in electrochemical energy storage power stations, characterized in that the composite cable for energy storage power stations is used for short-distance connection between 1500V energy storage battery clusters and converters, with a length ≤50m.

[0016] This invention relates to a composite cable for energy storage power stations, its manufacturing method, and its application. Compared with existing technologies, it has the following advantages: Firstly, this invention reduces the radial thermal resistance from the conductor to the primary channel to ≤0.08 K·m / W through an interface coupling layer and thermally conductive gel, enabling the axial thermal track to efficiently manage heat and avoiding the engineering paradox of "channels without heat flow." A ≥3℃ hysteresis band is set through a phase change layer (68-75℃) and a repair layer (78-85℃), combined with a time threshold (<30s vs >5min) to achieve "transient buffering without premature repair and fault repair without accidental triggering." By coating the fiber with a low thermal resistance coating (λ≥2.0) on the power core side and encapsulating it with aerogel (λ≤0.02) on the back side, the response time is <3s. The control line shielding layer combines electromagnetic shielding and auxiliary thermal conduction functions, directing heat into the graphene fiber bundle. By adopting a hierarchical thermal management topology of "radial thermal bridge diversion → axial thermal rail discharge → phase change transient buffering → fault sequence repair", the systemic problems of steady-state temperature rise, strong switching thermal shock, environmental damage accumulation and low-temperature start-up embrittlement of short-distance energy storage cables are solved, thereby achieving increased current carrying capacity, suppression of transient temperature rise and long-term maintenance-free operation.

[0017] Secondly, the present invention employs a two-stage solid-state axial heat conduction channel and a large-capacity continuous phase change layer design. Specifically, this invention uses a corrugated metal sheath as the carrier container for the phase change material (PCM). The PCM fills the entire annular space between the sheath and the insulated core, which is fundamentally different from the existing "microtube-filled PCM" solution: 1. Significant volume difference: The PCM accounts for 30-50% of the cable cross-sectional area, and its heat storage capacity is 5-10 times that of the microtube solution. It can absorb longer-term and higher-intensity charge-discharge thermal shocks, meeting the heat dissipation requirements of high-rate charge-discharge in energy storage power stations; 2. Integrated structure and function: The corrugated sheath simultaneously performs the functions of mechanical armor, sealing and encapsulation, and PCM container, eliminating the need for additional independent components such as PCM microtubes, simplifying the structure and reducing costs; 3. Optimized heat exchange path: The PCM directly contacts the heat source through a low thermal resistance filling layer, without the additional thermal resistance of the microtube wall, significantly improving the thermal response speed; 4. Long-term reliability: The large-volume continuous PCM zone combined with the foam metal skeleton avoids the thermal imbalance problem of "local saturation and local unmelting" in the microtube solution.

[0018] Thirdly, this invention employs an anti-gravity migration and circulation uniformity design. Specifically, it uses a foam metal skeleton (pore diameter 50-150μm) combined with paraffin wax. The capillary pressure (approximately 1-5kPa) generated by liquid paraffin wax in the micropores is much greater than the gravity-driven pressure (≤0.2kPa / m) generated by the cable laying inclination angle. Therefore, even under inclined or vertical laying conditions, the melted paraffin wax will not undergo macroscopic migration under gravity, and will be uniformly distributed after one-time solidification. During cooling and resolidification, the paraffin wax crystallizes in situ within the pores of the foam metal, without segregation or void formation. Verified by 100 melting-solidification cycle tests, the thickness difference between the upper and lower layers of the phase change layer is ≤5%, maintaining a concentric and uniform distribution, ensuring consistent thermal management performance of the cable in all directions, and solving the persistent engineering problem of "dry upper layer and accumulated lower layer" in traditional phase change cables. The foamed metal skeleton has a pore diameter of 50-150 μm. The capillary pressure (approximately 1-5 kPa) generated by the liquid paraffin in the pores is much greater than the gravity-driven pressure (≤0.2 kPa / m) generated by the cable laying inclination angle. Therefore, even during long-term thermal cycling, the paraffin will not undergo macroscopic migration inside the cable, and the phase change layer thickness remains uniform. Simultaneously, the vacuum infusion process ensures no gaps between the skeleton and the inner wall of the corrugated sheath, and the addition of 5% SEBS to the paraffin forms a gel state, further preventing liquid flow.

[0019] Fourthly, this invention employs a safety design using gelled phase change materials. 5wt% SEBS is added to paraffin wax to form a gel state, which, upon melting, becomes a high-viscosity paste (viscosity ≥ 5000 mPa•s), unlike liquid paraffin which flows freely. Even if the corrugated sheath fails to seal due to accidental damage, the gelled paraffin wax will not leak into the cable or battery module, fundamentally eliminating safety risks such as short circuits and fires. This design is deeply compatible with the high safety requirements of energy storage power stations and represents an "intrinsically safe" improvement over traditional pure paraffin phase change cables, possessing unique value in the energy storage industry. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the cross-section of the composite cable used in the energy storage power station in this invention.

[0021] The attached figures are labeled as follows: 1. Power transmission unit; 21. Inner layer modified cross-linked polyolefin; 22. Outer layer thermally conductive silicone rubber; 31. Addition-type thermally conductive silicone gel; 32. Thermally conductive polyimide wrapping tape; 4. Primary axial high thermal conductivity channel; 5. Composite phase change heat storage layer; 6. Corrugated metal sheath; 7. Base polyurea layer; 8. Inner repair layer + outer repair layer; 9. Optical unit or control unit. Detailed Implementation

[0022] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0023] Application Overview: On one hand, the present invention provides a composite cable for energy storage power stations, the cable comprising, from the inside out: a power transmission unit, a functionally decoupled inner insulation layer, a low thermal resistance filling and shaping layer, a primary axial high thermal conductivity channel, a composite phase change thermal storage layer, a corrugated metal sheath, a basic polyurea layer, an inner repair layer and an outer repair layer.

[0024] Power transmission unit The power transmission unit is a high-voltage DC conductor specifically designed for energy storage power stations. It uses tin-plated copper wire stranded together, with a cross-sectional area of ​​120mm² and a rated voltage of 1500V DC. The tin plating effectively improves the conductor's corrosion resistance in complex environments, while the stranded structure ensures the necessary flexibility for installation. In energy storage power stations, this integrated cable is used for short-distance connections between 1500V energy storage battery clusters and converters, with a length ≤50m and a line loss of less than 0.45%. It is a key component for the high-voltage DC connection on the battery side, and its high reliability and low loss characteristics directly affect the overall efficiency and operational economy of the power station.

[0025]

Functional Decoupling Type Inner Insulation Layer

[0026] The plasma surface treatment has a power of 300W and a treatment time of 3 minutes. It activates the surface of the inner layer modified cross-linked polyolefin, forming micro-pits and introducing polar groups. After plasma surface treatment, a silane coupling agent is impregnated. One end of the silane coupling agent chemically bonds to the plasma-activated silicone rubber surface, and the other end bonds to the molecular chains of the inner layer polyolefin. This achieves a high-strength chemical bond between the inner layer modified cross-linked polyolefin and the outer layer thermally conductive silicone rubber, preventing delamination during long-term thermal cycling of the energy storage cable. The annealing temperature is 90℃, and the annealing time is 2 hours. This ensures that the silane coupling agent completes a full cross-linking reaction and eliminates internal stress generated during processing, stabilizing the final dimensions of the material and preventing shrinkage or performance changes during subsequent use.

[0027] Low thermal resistance filler and shaping layer The low thermal resistance filling and shaping layer is composed of addition-type thermally conductive silicone gel and thermally conductive polyimide tape. The thermally conductive silicone gel (λ=2.0) serves as the filler layer, eliminating the bottleneck of localized overheating caused by the "air gap" in traditional stranded conductors. The thermally conductive polyimide tape (λ=1.3) provides the necessary mechanical framework, forming a multi-layered protection system together with the electrical insulation barrier and the functionally decoupled inner insulation layer. The heat generated by the conductor is first efficiently conducted to the inner side of the insulation layer by the thermally conductive gel, and then uniformly dissipated radially and axially by the thermally conductive polyimide tape, significantly reducing the thermal resistance at the conductor-insulator interface. The dielectric properties of the gel enhance the partial discharge suppression capability, while the polyimide tape provides additional high-temperature resistance and flame retardant barriers.

[0028] The silicone gel is degassed under a vacuum of ≤50Pa. This high vacuum environment eliminates microbubbles, ensuring full contact between the silicone gel and the insulation layer. The silicone gel is cured at 85℃ for 1.5 hours. The curing temperature is slightly lower than the annealing temperature, avoiding secondary high-temperature heat treatment of the already stabilized insulation layer and preventing material aging due to repeated heating. The polyimide tape has a 20% overlap rate, ensuring that the tape layer does not unravel or form gaps when the cable is bent. It also avoids uneven tape layer thickness and excessively high local rigidity caused by excessive overlap, maintaining the overall flexibility of the cable.

[0029] [Primary Axial High Thermal Conductivity Channel] The primary axial high thermal conductivity channel consists of 3-4 highly oriented graphene fiber bundles arranged along the cable axis on the outer surface of the wrapping tape. The diameter φ of the highly oriented graphene fiber bundles is 1.2mm, and the thermal conductivity λ=900. Utilizing the extremely high axial thermal conductivity of graphene fibers, heat accumulated inside the cable (especially at the conductor-insulation interface) is rapidly "drawn" along the cable length to the end or heat sink, breaking the bottleneck of traditional cables that rely solely on slow radial heat dissipation. The fiber bundles are covered with a flexible, bend-resistant protective mesh, such as an aramid silicone mesh, to prevent the graphene fiber bundles from breaking under stress and ensure the overall flexibility of the cable.

[0030] The graphene fiber bundles are axially fixed at points and wrapped with a flexible, bend-resistant protective mesh. The fixing points are non-continuously fixed using polyimide (PI) tape, rather than tightly wrapped. The short spacing of ≤50mm ensures that the fiber bundles do not slip or twist relative to each other when the cable is bent; avoiding high-strain areas (such as near joints) is to prevent the fixing points from being subjected to excessive shear forces that could lead to failure.

[0031] In summary, by using an interface coupling layer and thermally conductive gel to reduce the radial thermal resistance from the conductor to the primary channel to ≤0.08 K·m / W, the axial thermal track can efficiently manage heat transfer, avoiding the engineering paradox of "having a channel but no heat flow".

[0032] Composite phase change thermal storage layer A composite phase change thermal storage layer is wrapped around the outside of the primary axial high thermal conductivity channel. It comprises a foamed metal skeleton with a porosity of 90-95% and a phase change medium filled within the pores. The phase change temperature of the phase change medium is 68-75℃. Since the steady-state operating temperature of the cable is below 68℃, the phase change medium is solid. When the conductor temperature rapidly rises to 68-75℃, the phase change medium begins to melt, absorbing a large amount of latent heat (≥180 J / g) while its own temperature remains essentially unchanged. The foamed copper skeleton phase change layer suppresses the temperature rise peak during charge-discharge switching by ≥8℃, effectively preventing accidental triggering of battery thermal runaway. The thermal conductivity of the composite phase change thermal storage layer is 10-30 W / (m·K), and the composite material itself becomes a highly efficient radial heat dissipation layer. The foamed metal skeleton is preferably foamed copper (92% porosity), and the phase change medium includes, but is not limited to, industrial-grade paraffin wax (Tm=72℃, λ=18, latent heat 190 J / g).

[0033] The capillary pressure (approximately 1-5 kPa) generated by the liquid paraffin in the micropores is much greater than the gravity-driven pressure (≤0.2 kPa / m) generated by the cable laying inclination angle. Therefore, even under inclined or vertical laying conditions, the melted paraffin will not undergo macroscopic migration under gravity, and will be uniformly distributed after one-time solidification. During cooling and resolidification, the paraffin crystallizes in situ within the pores of the foam metal, without segregation or void formation. Verified by 100 melting-solidification cycle tests, the thickness difference between the upper and lower layers of the phase change layer is ≤5%, maintaining a uniform concentric distribution, ensuring consistent thermal management performance of the cable in all directions, and solving the persistent engineering problem of "dry upper layer and accumulated lower layer" in traditional phase change cables. The pore diameter of the foam metal skeleton is 50-150 μm, and the capillary pressure (approximately 1-5 kPa) generated by the liquid paraffin in the pores is much greater than the gravity-driven pressure (≤0.2 kPa / m) generated by the cable laying inclination angle. Therefore, even during long-term thermal cycling, paraffin wax does not undergo macroscopic migration within the cable, and the phase change layer thickness remains uniform. Simultaneously, the vacuum infusion process ensures a gapless connection between the skeleton and the inner wall of the corrugated sheath, and the addition of 5% SEBS to the paraffin wax forms a gel state, further preventing liquid flow.

[0034] Preferably, 5 wt% SEBS is added to the paraffin wax to form a gel state. After melting, it becomes a high-viscosity paste (viscosity ≥ 5000 mPa•s), which does not flow freely like liquid paraffin wax. Even if the corrugated sheath fails to seal due to accidental damage, the gelled paraffin wax will not flow or leak to the outside of the cable or into the battery module, fundamentally eliminating safety risks such as short circuits and fires. This design is deeply matched to the high safety requirements of energy storage power stations and is an "intrinsically safe" improvement that differs from traditional pure paraffin phase change cables, possessing unique value in the energy storage industry.

[0035] The cable core is inserted into an empty corrugated tube, and both ends are temporarily sealed with vacuum injection ports. After preheating, molten phase change medium is injected under a predetermined vacuum degree, and then pressure is maintained and cooled to solidify. The preheating temperature is raised to 85℃ and the vacuum degree is ≤50Pa. The preheating removes moisture and air from the skeleton and cable core. Molten phase change medium is injected at a injection temperature of 95℃ and pressure is maintained for 2 hours to ensure that the medium completely fills all micropores under capillary action.

[0036]

Corrugated Metal Sheath

[0037] Using a corrugated metal sheath as the carrier container for the phase change material (PCM), with the PCM filling the entire annular space between the sheath and the insulated core, this approach differs fundamentally from existing "microtube-filled PCM" solutions: 1. Significant volume difference: The PCM accounts for 30-50% of the cable cross-sectional area, with a heat storage capacity 5-10 times that of the microtube solution. This allows it to absorb longer and more intense charge-discharge thermal shocks, meeting the heat dissipation requirements of high-rate charge-discharge in energy storage power stations. 2. Integrated structure and function: The corrugated sheath simultaneously serves as mechanical armor, sealing, and the PCM container, eliminating the need for additional independent components such as PCM microtubes, simplifying the structure and reducing costs. 3. Optimized heat exchange path: The PCM directly contacts the heat source through a low thermal resistance filling layer, eliminating the additional thermal resistance of the microtube wall and significantly improving thermal response speed. 4. Long-term reliability: The large-volume continuous PCM zone, combined with a foamed metal skeleton, avoids the thermal imbalance problem of "local saturation and local unmelting" found in microtube solutions.

[0038] [Basic Polyurea Layer] A base polyurea layer is sprayed onto the outer surface of the corrugated metal sheath at a spraying temperature of ≤55°C. This base polyurea layer ensures that it does not have a thermal impact on internal precision structures (such as phase change materials). It provides basic protection, including mechanical strength, waterproof sealing, electrical insulation, and strong adhesion to the metal sheath, serving as a substrate for subsequent coatings.

[0039] [Inner Repair Layer] The inner repair layer is formed on the surface of the base polyurea layer through a gradient blending process of thermotropic repair microcapsules and polyurea matrix, with a penetration depth of 80-150 μm and an increasing concentration from the inside to the outside, ensuring efficient repair of surface damage. The key to this process lies in controlling the spraying parameters to achieve the enrichment of repair microcapsules on the surface.

[0040] When microcracks appear on the surface due to external forces, the microcapsules rupture and release a repair agent. Triggered by ambient heat or conductor operating heat, the damage is automatically repaired, thereby actively preventing the intrusion of moisture and corrosive media and improving the reliability of the cable during long-term operation.

[0041]

Outer Repair Layer

[0042] [Optical unit or control unit] During the cable stranding process, the optical unit and the power transmission unit are simultaneously placed into the fixed sector of the cable core. A low thermal resistance thermal conductive coating is applied to the side facing the power transmission unit to efficiently dissipate the heat generated by the optical unit itself and the adjacent cables, ensuring its stable operating temperature. An aerogel heat insulation sleeve is wrapped on the back side to effectively isolate heat from other areas of the cable core and achieve directional thermal management.

[0043] The control unit is covered with an aluminum foil-tinned copper wire braided shielding layer, which is thermally coupled to a primary axial high thermal conductivity channel. This allows the heat generated by the control unit during operation to be efficiently directed into the axial heat dissipation channel, thereby synergistically improving the thermal management and signal integrity of the entire cable.

[0044] The present invention will be further described below with reference to the embodiments. The examples described are intended to explain the present invention and should not be construed as limiting the present invention.

[0045] Test method: Thermal shock suppression during charge / discharge switching: Test equipment: Charge / discharge test platform (supports 3C / 0.5C step switching), FBG demodulator (sampling rate 1kHz, wavelength resolution 1pm) and data acquisition system. Test steps: (1) Place the cable in a constant temperature chamber (40℃), load 65% of the rated current, and wait for the temperature to stabilize at 65℃. (2) Control the charge / discharge test platform to perform the step condition of "3C charging for 30s → immediately switching to 0.5C discharging". (3) Continuously monitor the conductor temperature change through the FBG optical unit and record the peak temperature. (4) Repeat 5 times and take the average value.

[0046] Heat repair cycle life: A 0.5mm standard cut is made on the outer sheath of the cable, and the cable is kept in an 80℃ constant temperature chamber for 24 hours to complete one repair cycle. The strength retention rate after 50 heat repair cycles = strength after 50 heat repair cycles / initial strength.

[0047] Step response test: The constant temperature water bath step temperature method (50℃→70℃) was used, and the wavelength change was continuously recorded by an FBG demodulator.

[0048] Temperature deviation test: Place the optical unit and the standard PT100 platinum resistance thermometer in the same constant temperature bath, and take a set of data every 15℃ within the range of -30℃ to 85℃. Record the maximum deviation between the FBG demodulated value and the PT100 standard value.

[0049] Current carrying capacity (air laying at 40℃): Refer to TICW 15-2012.

[0050] Anti-gravity migration (cycle uniformity): Vertically laid for 1m, 80 melting-solidification cycles, and the thickness difference between the upper and lower parts of the phase change layer is recorded.

[0051] Gelation leak prevention (intrinsically safe): The sheath is artificially perforated, heated to 80°C in a liquid state, tilted at 30° for 24 hours, and the leakage amount of the phase change material is recorded.

[0052] Thermal cycling sealing: 100 cycles from 40℃ to 85℃, measuring quality changes and appearance.

[0053] FBG temperature measurement response speed: measures the response time of the FBG sensing unit to a 10% to 90% change in the temperature of the cable conductor from 50℃ to 70℃.

[0054] Example 1: This example provides a 1500V / 120mm² basic intelligent cable. The conductor of this cable is 120mm² tinned copper wire stranded together, with an operating voltage of 1500V DC and a nominal line loss of 0.45%. The inner insulation adopts a double-layer structure: an inner layer of 0.7mm modified XLPO and an outer layer of 0.4mm thermally conductive silicone rubber (λ=1.1 W / (m·K)), with the interface treated by plasma. The outer layer of the conductor is filled with a thermally conductive silicone gel (λ=2.0 W / (m·K)) and a BN-PI thermally conductive wrapping tape (λ=1.3 W / (m·K)). The axial high thermal conductivity channel is composed of four φ1.2mm highly oriented graphene fiber bundles (λ=900 W / (m·K)) wrapped with an aramid silicone mesh. The outer composite phase change thermal storage layer uses copper foam with a porosity of 92% as its framework and is filled with paraffin medium with a phase change temperature of 72℃ and a latent heat of 190 J / g. The overall thermal conductivity is 18 W / (m·K). This layer is covered with a 0.5mm thick, 2.0mm deep aluminum alloy corrugated tube sheath, with a sealing cap at the end. The sealing cap is fixedly connected to the end of the corrugated metal sheath by laser welding. A conductor lead-out hole is opened in the center of the welded sealing cap, through which the power core of the power transmission unit passes. The annular gap between the power core and the wall of the lead-out hole is filled with high-temperature sealant with a temperature resistance of ≥150℃. The end of the corrugated metal sheath also has an exposed section of not less than 10mm, which is pressed or welded to the wiring terminal or the equipment heat dissipation base. The outermost layer is a gradient-coated outer sheath: a 0.8mm base polyurea layer, a 110μm thick thermo-tonic repair microcapsule inner layer (trigger temperature 80℃), and a 0.6mm fluorocarbon polyurea-based photo-triggered repair / self-cleaning outer layer (containing coumarin derivatives and SiO2@TiO2). The optical unit is a single-core cable, embedded in a low thermal resistance filler layer.

[0055] Test results: Compared with PVC insulated cables of the same cross-section, the current carrying capacity is increased by 21%. Compared with the reference cable of the same structure but without the phase change heat storage layer, the switching temperature rise peak is suppressed by 9.2℃. After 50 heat repair cycles, the strength retention rate is 82%, which is much higher than the 40-50% retention rate of conventional non-repairable materials.

[0056] Example 2: This example provides a 1.5kV / 150mm² basic energy storage cable, designed for low-voltage, high-current connections between energy storage battery clusters and PCS, focusing on improving current carrying capacity and suppressing thermal shock. The cable conductor uses 150mm² tinned copper wire stranded together, operates at 1.5kV DC, and has a nominal line loss of 0.45%. The inner insulation layer has a double-layer structure: the inner layer is 1.2mm modified XLPO, and the outer layer is 0.4mm thermally conductive silicone rubber (thermal conductivity λ≥1.0W / (m·K)), with a breakdown strength ≥28kV / mm. The conductor outer layer is filled with a low thermal resistance shaping layer, composed of thermally conductive silicone gel (λ=2.0W / (m·K)) and thermally conductive PI tape. The cable has two-stage axial heat-conducting channels: the first stage consists of four highly oriented graphene fiber bundles (φ1.2mm, λ=900W / (m·K)), and the second stage consists of an aluminum alloy corrugated sheath wall (λ≈200W / (m·K)). The second-stage channel contributes 22% of steady-state heat dissipation. The outer layer is a high-capacity continuous phase change layer, with a 92% porosity copper foam skeleton, filled with 95wt% paraffin wax and 5wt% PVC with a phase change temperature of 68-75℃. SEBS composite dielectric, the phase change layer accounts for 42% of the cable cross-sectional area, and is covered with an aluminum alloy corrugated metal sheath (2.0mm depth, 0.5mm thickness), which takes into account the functions of phase change bearing, armoring and secondary heat conduction; the ends are equipped with laser-welded sealing caps and high-temperature sealant (temperature resistance ≥150℃) to achieve reliable sealing; the outermost layer is a three-layer gradient sprayed outer sheath, including a basic polyurea layer, an 80℃ triggered inner repair layer and an outer repair layer.

[0057] Test results: The current carrying capacity is increased by 28% compared with PVC insulated cables of the same cross-section (test method refers to TICW 15-2012). Compared with cables without phase change layer, the switching temperature rise peak suppression is greater than 10℃, and the switching temperature rise peak suppression is 56%.

[0058] Discussion: This embodiment uses a two-stage axial heat conduction channel to quickly conduct steady-state heat to the heat sinks at both ends. Combined with a large-capacity phase change layer accounting for 42% of the cable cross-sectional area to absorb transient thermal shock, it achieves a 28% increase in current carrying capacity and a 56% suppression of thermal spikes. At the same time, the foam metal skeleton ensures that the phase change material does not migrate during vertical laying and that the thickness is uniform after cycling, meeting the requirements of high-rate charging and discharging and long-term operation of energy storage power stations.

[0059] Example 3: This example provides a 10kV / 185mm² basic energy storage cable, targeting the 10kV industrial and commercial energy storage step-up connection scenario, focusing on solving the intrinsic safety and thermal cycling reliability issues under high voltage and high power conditions. The cable conductor uses 185mm²... 2The cable is constructed with tin-plated copper wire strands, operating at 10kV AC. The inner insulation layer is a double-layer structure: an inner layer of 4.5mm modified XLPO and an outer layer of 0.5mm thermally conductive silicone rubber, with a breakdown strength ≥28kV / mm. The conductor's outer layer is filled with a low thermal resistance shaping layer, composed of thermally conductive silicone gel (λ=2.0W / (m·K)) and PI tape. An integrated optical fiber unit (FBG) is integrated inside the cable, using single-mode optical fiber with asymmetric wrapping. A low-resistance thermally conductive coating (λ=2.5) is applied to the conductor side, while aerogel (λ=0.018) is wrapped around the conductor side. The entire unit is embedded in the filling layer and tightly adheres to the insulation layer, enabling rapid and accurate temperature measurement. A primary axial heat-conducting channel is provided, consisting of four φ1.3mm highly oriented graphene fiber bundles (λ=950W / (m·K)). The outer composite gelled phase change layer has a porosity of 90% and a pore size of 60μm. The foamed copper core serves as the skeleton, filled with a paraffin / 5% SEBS composite medium with a phase change temperature of 70-78℃, in a liquid paste state (viscosity ≥5000mPa·s), ensuring inherent safety against leakage. The phase change layer is covered with an aluminum alloy corrugated sheath (0.55mm thick), which serves as a "three-in-one" structure, simultaneously functioning as mechanical armor, a phase change container, and secondary heat conduction. To achieve leak-free operation during hot and cold cycles, a multi-stage volume expansion containment structure is designed, effectively absorbing phase change volume changes through four levels of synergy: foamed metal micropores, corrugated gaps (2.0mm depth), 0.2mm pre-reserved pipe wall, and terminal elastic sealant. The ends are reliably sealed by argon arc welding of the sealing cap and high-temperature sealant (15mm exposed section). The outermost layer is a three-layer gradient sprayed outer sheath (same as in Example 1).

[0060] Test results: 1. Gelation leak prevention: After opening the sheath, heating to 80℃ liquid, and placing it at a 30° angle for 24 hours, the leakage was 0g (leakage of pure paraffin solution ≥20g); 2. Cold and hot cycle sealing: After 100 cycles from -40℃ to 85℃, the mass loss was ≤0.1%, and there was no bulging (bulging rate of non-multi-stage containment solution ≥30%); 3. FBG temperature measurement response speed: The response time for step temperature change from 50℃ to 70℃ and from 10% to 90% was 2.3 seconds (the response time of traditional fully encapsulated aerogel solution ≥12 seconds).

[0061] Discussion: This embodiment employs an innovative combination of "intrinsically safe gelation + multi-stage volume expansion containment + three-in-one corrugated sheath + FBG asymmetric encapsulation." The gelled phase change material achieves intrinsic safety (no leakage even in the event of seal failure), the four-stage volume expansion containment structure ensures no leakage after 100 thermal cycles, the three-in-one corrugated sheath significantly simplifies the structure and reduces weight, and the FBG asymmetric encapsulation achieves millisecond-level temperature response (2.3s), providing real-time thermal field data for the BMS. These performance characteristics directly address the core requirements of energy storage power stations for safety, long lifespan, and intelligence.

[0062] Example 4: This example provides a smart cable with FBG optical units. Based on Example 1, in the cable stranding S2 step, the FBG optical fiber is placed in the fixed sector (non-torsion zone) of the cable core. A low thermal resistance thermally conductive coating (λ=2.5 W / (m·K), 0.2 mm thick) is sprayed onto the side facing the power core, and an aerogel insulation tube (λ=0.018 W / (m·K)) is fitted onto the side facing away from the environment.

[0063] Actual Results: Based on Example 1, FBG asymmetric coating (low-resistivity coating + aerogel) was applied. Compliance tests included step response testing and temperature deviation testing. Step Response Testing: A constant-temperature water bath step temperature method (50℃→70℃) was used, with wavelength changes continuously recorded using an FBG demodulator. Test results showed that at a sampling distance of 10m, the optical unit's response time was 2.1s. Temperature Deviation Testing: The optical unit and a standard PT100 platinum resistance thermometer were placed in the same constant-temperature bath, and data was collected every 15℃ within the range of -30℃ to 85℃. The maximum deviation between the FBG demodulated value and the PT100 standard value was ±0.8℃.

[0064] Example 5: This example provides a smart cable with FBG optical units. In this example, based on Example 1, the optical fiber is simultaneously inserted into the BMS control cable during the cable stranding step S2. An aluminum foil + tinned copper wire braided shielding layer is provided. The shielding layer is grounded and thermally coupled to the graphene fiber bundle via a thermally conductive silicone pad.

[0065] Actual results: Compared with the control unit of the same structure where the shielding layer is only grounded but not thermally coupled to the graphene fiber bundle, the temperature rise of the control unit in this embodiment is reduced by 4.5℃ and the EMC radiation suppression reaches 40dB.

[0066] In summary, this embodiment achieves efficient axial heat dissipation in steady state by constructing a radial-axial thermal resistance gradient network; the phase change layer (68-75℃) is specifically designed to buffer transient thermal shocks during charge-discharge switching; and the inner repair layer (78-85℃) and phase change window are equipped with a ≥3℃ hysteresis band to achieve fault timing triggering. This invention solves the problems of temperature rise accumulation, strong thermal shock, environmental damage, and low-temperature embrittlement in short-distance energy storage cables, increases current carrying capacity by 18-25%, suppresses transient temperature rise by ≥8℃, and provides a repair cycle life of ≥50 cycles. It is suitable for short-distance connections between 1500V energy storage battery clusters and PCS.

[0067] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A composite cable for an energy storage power station, characterized in that, From the inside out, the following are included: Power transmission unit; The functionally decoupled inner insulation layer comprises an inner layer of modified cross-linked polyolefin, an outer layer of thermally conductive silicone rubber, and an interfacial coupling transition layer disposed between the two layers. The low thermal resistance filler and shaping layer is composed of addition-type thermally conductive silicone gel and thermally conductive polyimide tape. A primary axial high thermal conductivity channel comprises multiple highly oriented graphene fiber bundles arranged along the cable axis on the outer surface of the wrapping tape, with a flexible anti-bending protective mesh covering the outside of the fiber bundles; A composite phase change thermal storage layer is wrapped around the outside of the primary axial high thermal conductivity channel and includes a foam metal skeleton and a phase change medium filling the pores of the foam metal skeleton. A corrugated metal sheath is fitted over the outside of the composite phase change thermal storage layer. An expansion compensation cavity is reserved between the inner wall of the sheath and the phase change thermal storage layer. A welded sealing cap is provided at the end of the corrugated metal sheath. A base polyurea layer is sprayed onto the outer surface of the corrugated metal sheath; The inner repair layer is formed by a gradient blending process of thermo-repair microcapsules and polyurea matrix. The outer repair layer is composed of fluorocarbon modified polyurea, coumarin derivatives and core-shell structured nano-TiO2, and is sprayed on the outside of the inner repair layer.

2. The composite cable for energy storage power stations according to claim 1, characterized in that, The primary axial high thermal conductivity channel separates from the corrugated metal sheath at the cable terminal and is connected to an external heat sink.

3. The composite cable for energy storage power stations according to claim 1, characterized in that, The penetration depth between the inner repair layer and the surface layer of the base polyurea layer is 80-150 μm.

4. The composite cable for energy storage power stations according to claim 1, characterized in that, The phase change medium has a phase change temperature of 68-75℃, a latent heat of ≥180J / g, and a thermal conductivity of 10-30W / (m·K) for the composite phase change heat storage layer.

5. The composite cable for energy storage power stations according to claim 1, characterized in that, The trigger temperature of the inner repair layer is 78-85℃, and a hysteresis isolation zone of ≥3℃ is provided between it and the phase change temperature of the phase change medium.

6. The composite cable for energy storage power stations according to claim 1, characterized in that, The sealing cap and the end of the corrugated metal sheath are fixedly connected by laser welding or argon arc welding. The center of the welded sealing cap is provided with a conductor lead-out hole through which the power core of the power transmission unit passes. The annular gap between the power core and the wall of the lead-out hole is filled with high-temperature resistant sealant. The end of the corrugated metal sheath also has an exposed section of not less than 10mm, which is pressed or welded to the wiring terminal or the heat dissipation base of the equipment.

7. The composite cable for energy storage power stations according to claim 1, characterized in that, It also includes an optical unit or a control unit; the optical unit is placed in the low thermal resistance filling and shaping layer, coated with a low thermal resistance thermally conductive coating on the side facing the power transmission unit, and covered with an aerogel thermal insulation sleeve on the back side; the control unit is covered with an aluminum foil-tinned copper wire braided shielding layer, and the shielding layer is thermally coupled to the primary axial high thermal conductivity channel.

8. A manufacturing process for a composite cable for an energy storage power station based on any one of claims 1 to 8, characterized in that, include: S1 conductor stranded, double-layer insulation co-extruded and subjected to plasma surface treatment, thermal stress annealing; S2 cable stranding, synchronous insertion of optical unit or control unit, injection of thermally conductive silicone gel, and wrapping with thermally conductive polyimide tape; S3 graphene fiber bundles are fixed at axial points and wrapped with flexible anti-bending protective netting; The S4 cable core is inserted into the hollow corrugated tube, both ends are temporarily sealed and vacuum injection ports are reserved. After preheating, molten phase change medium is injected under a predetermined vacuum degree, and then pressure is maintained and cooled to solidify. S5 bellows end caps are fitted with sealing caps; The S6 outer sheath is coated with a three-layer gradient spray, including a base polyurea layer, an inner repair layer gradient blending spray, and an outer repair layer spray, controlling the surface drying time to complete surface enrichment.

9. The composite cable for energy storage power stations according to claim 8, characterized in that, In step S1, the plasma surface treatment power is 300W, the treatment time is 3min, and after the plasma surface treatment, silane coupling agent is impregnated; the annealing temperature is 90℃, and the annealing time is 2h. In step S2, the silicone gel is degassed under vacuum at ≤50Pa, the curing temperature of the silicone gel is 85℃, the curing time is 1.5h, and the overlap rate of the polyimide tape is 20%. In step S3, PI tape is used for fixing points, with a point spacing of ≤50mm; the fixing pitch must avoid high strain areas; In step S4, the preheating temperature is raised to 85°C, and the molten phase change medium is injected at a injection temperature of 95°C under a vacuum of ≤50Pa, and the pressure is maintained for 2 hours. In step S6, the base polyurea layer is sprayed at a temperature ≤55℃, the inner repair layer is sprayed with a gradient blending ratio of 15wt%, the surface drying delay controls the enrichment depth, and the overall curing temperature is 60℃.

10. An application of the composite cable for energy storage power stations according to any one of claims 1 to 8 in an electrochemical energy storage power station, characterized in that, The integrated cable used in the energy storage power station is used for short-distance connection between the 1500V energy storage battery cluster and the converter, with a length ≤50m.

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