Composite insulation direct current cable structure
Patent Information
- Application Number
- CN202522171624.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-14
- Publication Date
- 2026-09-11
- Estimated Expiration
- 2035-10-14
AI Technical Summary
其绝缘结构在直流电场下易积聚空间电荷，导致电场畸变，威胁安全
[0010]本实用新型的一种复合绝缘直流电缆结构，所述外护套能够为整个电缆结构提供保护作用，通过设定所述内层绝缘层介电常数高于所述外层外绝缘层介电常数，利用电阻电容分压原理，在直流电压下使电场强度从内向外自然呈更均匀的分布，从物理结构上降低了导体附近的最大场强，所述主导体采用型线绞合导体提高了导体填充系数，使电缆外径更小，电流分布更均匀，结构更稳定，通过所述半导电阻水缓冲层和所述外护套两道实体防线，分别实现了纵向阻水和径向防潮，大大提升了电缆在潮湿环境下的可靠性，所述复合绝缘层外表面的所述凸起结构与所述半导电阻水缓冲层形成机械嵌合，极大增强了两者间的结合力，防止运行过程中因热胀冷缩而产生的层间分离，提升了整体机械稳定性与界面电气性能。
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Figure CN224745485U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of cable technology, and in particular to a composite insulated DC cable structure. Background Technology
[0002] In recent years, direct current (DC) transmission has developed rapidly in power systems due to its low line loss, absence of reactive power, and high energy transmission efficiency. Considering the cost of AC-DC conversion during transmission and distribution, DC transmission is more economical for long-distance, large-capacity applications. High-voltage DC cables are key equipment for projects such as renewable energy transmission and inter-regional grid interconnection. However, their insulation structure is prone to accumulating space charge under a DC electric field, leading to electric field distortion and threatening safety.
[0003] Existing technologies mostly focus on improving insulation materials, but there is insufficient innovation in the overall physical structure of cables, especially in how to improve the electric field, enhance the bonding force between layers, and improve the overall protection capabilities through physical structure (rather than simply relying on materials). There is still room for improvement in these areas. Utility Model Content
[0004] The purpose of this invention is to provide a composite insulated DC cable structure that solves the problem that existing technologies mainly improve the insulation material, but lack innovation in the overall physical structure of the cable. In particular, there is still room for improvement in how to improve the electric field, enhance the bonding force between layers, and improve the overall protection capability through physical structure (rather than simply relying on materials).
[0005] To achieve the above objectives, this utility model provides a composite insulated DC cable structure, including a main body and a covering device. The covering device includes an inner semiconductor shielding layer, a composite insulation layer, an outer semiconductor shielding layer, a metal shielding layer, and an outer sheath. The inner semiconductor shielding layer is installed outside the main body, the composite insulation layer is installed outside the inner semiconductor shielding layer, the outer semiconductor shielding layer is installed outside the composite insulation layer, the metal shielding layer is installed outside the outer semiconductor shielding layer, and the outer sheath is installed outside the metal shielding layer. The composite insulation layer is formed into an integral double-layer structure by co-extrusion of the inner and outer insulation layers. The dielectric constant of the inner insulation layer is higher than that of the outer insulation layer.
[0006] The inner semiconductor shielding layer is further provided with a spiral guide groove, which is disposed on the inner side of the inner semiconductor shielding layer.
[0007] An optical fiber sensing unit is provided between the outer sheath and the metal shielding layer, and the optical fiber sensing unit is distributed along the axis of the main body.
[0008] The composite insulating layer is further provided with a semiconducting resistive water buffer layer on its outer side, and the semiconducting resistive water buffer layer is also fixed inside the outer semiconductor shielding layer.
[0009] A raised structure is provided between the composite insulating layer and the semiconducting resistive water buffer layer. The semiconducting resistive water buffer layer is extruded and covers the raised structure and is embedded in the raised structure.
[0010] This utility model discloses a composite insulated DC cable structure. The outer sheath provides protection for the entire cable structure. By setting the dielectric constant of the inner insulation layer to be higher than that of the outer insulation layer, the electric field strength under DC voltage is naturally distributed more evenly from the inside to the outside using the principle of resistor-capacitor voltage division. This reduces the maximum field strength near the conductor from a physical structure perspective. The main conductor uses stranded wire to improve the conductor fill factor, resulting in a smaller cable outer diameter, more uniform current distribution, and a more stable structure. The semiconducting water-resistant buffer layer and the outer sheath provide two physical defenses, achieving longitudinal water resistance and radial moisture protection, respectively, greatly improving the reliability of the cable in humid environments. The raised structure on the outer surface of the composite insulation layer forms a mechanical interlock with the semiconducting water-resistant buffer layer, greatly enhancing the bonding force between the two and preventing interlayer separation caused by thermal expansion and contraction during operation, thus improving the overall mechanical stability and interface electrical performance. Attached Figure Description
[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0012] Figure 1 This is a schematic diagram of the overall structure of a composite insulated DC cable according to this utility model.
[0013] Figure 2 This is a schematic diagram of the spiral guide groove of this utility model.
[0014] In the diagram: 101-Main body, 102-Inner semiconductor shielding layer, 103-Composite insulation layer, 104-Outer semiconductor shielding layer, 105-Metal shielding layer, 106-Outer sheath, 107-Inner insulation layer, 108-Outer insulation layer, 109-Spiral guide groove, 110-Fiber optic sensing unit, 111-Semiconductor resistive water buffer layer, 112-Protruding structure. Detailed Implementation
[0015] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.
[0016] The embodiment of this application is as follows:
[0017] Please see Figure 1-2 , Figure 1 This is a schematic diagram of the overall structure of a composite insulated DC cable according to this utility model. Figure 2 This is a schematic diagram of the spiral guide groove of this utility model.
[0018] This utility model provides a composite insulated DC cable structure, including a main body 101 and a covering device. The covering device includes an inner semiconductor shielding layer 102, a composite insulation layer 103, an outer semiconductor shielding layer 104, a metal shielding layer 105, and an outer sheath 106. The inner semiconductor shielding layer 102 is also provided with a spiral guide groove 109. An optical fiber sensing unit 110 is also provided between the outer sheath 106 and the metal shielding layer 105. A semiconducting resistive water buffer layer 111 is also provided on the outside of the composite insulation layer 103. A protruding structure 112 is also provided between the composite insulation layer 103 and the semiconducting resistive water buffer layer 111. The above-mentioned solution solves the problem that the existing technology mainly improves the insulation material modification, but lacks innovation in the overall physical structure of the cable, especially in how to improve the electric field, enhance the bonding force between layers, and improve the comprehensive protection capability through physical structure (rather than simply relying on materials).
[0019] In this embodiment, the main body 101, inner semiconductor shielding layer 102, composite insulation layer 103, outer semiconductor shielding layer 104, metal shielding layer 105 and outer sheath 106 work together to improve the electric field, enhance the bonding force between the layers and improve the overall protection capability.
[0020] The inner semiconductor shielding layer 102 is installed outside the main body 101, the composite insulating layer 103 is installed outside the inner semiconductor shielding layer 102, the outer semiconductor shielding layer 104 is installed outside the composite insulating layer 103, the metal shielding layer 105 is installed outside the outer semiconductor shielding layer 104, and the outer sheath 106 is installed outside the metal shielding layer 105. The composite insulating layer 103 is a one-piece double-layer structure formed by co-extrusion of an inner insulating layer 107 and an outer insulating layer 108. The dielectric constant of the inner insulating layer 107 is higher than that of the outer insulating layer 108. The inner semiconductor shielding layer 102 is a smooth conductive layer formed by extrusion. The main conductor 101 is a stranded wire conductor. The outer sheath 106 can provide protection for the entire cable structure. By setting the dielectric constant of the inner insulation layer 107 to be higher than that of the outer insulation layer, the electric field strength under DC voltage is naturally more uniformly distributed from the inside to the outside, which reduces the maximum field strength near the conductor from a physical structure perspective. The use of stranded wire conductor in the main conductor 101 improves the conductor fill factor, making the cable outer diameter smaller, the current distribution more uniform, and the structure more stable.
[0021] Secondly, the spiral guide groove 109 is disposed inside the inner semiconductor shielding layer 102. The spiral guide groove 109 has a spiral structure and forms a gap channel between the main body 101 and the inner semiconductor shielding layer 102. During the vulcanization and cross-linking stage of the cable manufacturing process, the spiral guide groove 109 provides an escape path for water vapor and volatiles released from the insulation material. Furthermore, when the cable is under load, the main body 101 heats up and expands. The spiral guide groove 109 structure can accommodate and buffer the slight radial expansion of the main body 101, thereby improving long-term operational reliability.
[0022] Secondly, the fiber optic sensing unit 110 is distributed along the axis of the main body 101. The fiber optic sensing unit 110 can be used to monitor the temperature, strain and partial discharge of the cable in real time, realize online diagnosis and fault warning of the cable status, and improve the level of intelligent operation and maintenance.
[0023] Furthermore, the semiconducting resistive water buffer layer 111 is also fixed inside the outer semiconductor shielding layer 104. The semiconducting resistive water buffer layer 111 simultaneously possesses the triple functions of water blocking, buffering mechanical stress, and homogenizing the interface electric field. It can prevent water from penetrating longitudinally, absorb the stress generated by cable bending and thermal expansion and contraction, and also serve as a soft transition layer.
[0024] Finally, the semiconducting resistive water buffer layer 111 is extruded and covers the raised structure 112 and is fitted with the raised structure 112. The raised structure 112 is arranged in a ring. Through the arrangement of the raised structure 112, mechanical locking between the semiconducting resistive water buffer layer 111 and the composite insulating layer 103 can be achieved and the contact area can be increased, preventing relative displacement or delamination between the semiconducting resistive water buffer layer 111 and the composite insulating layer 103, and ensuring the long-term stability of the interface electrical performance.
[0025] In this embodiment, the outer sheath 106 provides protection for the entire cable structure. By setting the dielectric constant of the inner insulation layer 107 to be higher than that of the outer insulation layer, the electric field strength is naturally distributed more evenly from the inside to the outside under DC voltage using the principle of voltage division by resistance and capacitance. This reduces the maximum field strength near the conductor from a physical structure perspective. The main conductor 101 uses stranded conductors to improve the conductor fill factor, resulting in a smaller cable outer diameter, more uniform current distribution, and a more stable structure. Through the two physical defenses of the semiconducting water-resistant buffer layer 111 and the outer sheath 106, longitudinal water resistance and radial moisture resistance are achieved, greatly improving the reliability of the cable in humid environments. The raised structure 112 on the outer surface of the composite insulation layer 103 forms a mechanical interlock with the semiconducting water-resistant buffer layer 111, greatly enhancing the bonding force between the two and preventing interlayer separation caused by thermal expansion and contraction during operation, thus improving the overall mechanical stability and interface electrical performance.
[0026] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.
Claims
1. A composite insulated DC cable structure, comprising a main body, characterized in that, It also includes a covering device; The encapsulation device includes an inner semiconductor shielding layer, a composite insulating layer, an outer semiconductor shielding layer, a metal shielding layer, and an outer sheath. The inner semiconductor shielding layer is installed outside the main body, the composite insulating layer is installed outside the inner semiconductor shielding layer, the outer semiconductor shielding layer is installed outside the composite insulating layer, the metal shielding layer is installed outside the outer semiconductor shielding layer, and the outer sheath is installed outside the metal shielding layer. The composite insulating layer is formed into an integral double-layer structure by co-extrusion of the inner and outer insulating layers. The dielectric constant of the inner insulating layer is higher than that of the outer insulating layer.
2. The composite insulated DC cable structure as described in claim 1, characterized in that, The inner semiconductor shielding layer is also provided with a spiral guide groove, which is disposed on the inner side of the inner semiconductor shielding layer.
3. The composite insulated DC cable structure as described in claim 1, characterized in that, An optical fiber sensing unit is also provided between the outer sheath and the metal shielding layer, and the optical fiber sensing unit is distributed along the axis of the main body.
4. The composite insulated DC cable structure as described in claim 1, characterized in that, The composite insulating layer is further provided with a semiconducting resistive water buffer layer on its outer side, and the semiconducting resistive water buffer layer is also fixed inside the outer semiconductor shielding layer.
5. The composite insulated DC cable structure as described in claim 4, characterized in that, A raised structure is provided between the composite insulating layer and the semiconducting resistive water buffer layer. The semiconducting resistive water buffer layer is extruded and covers the raised structure and is embedded in the raised structure.