Low-wind-resistance insulated cable

Abstract

A low-wind-resistance insulated cable disclosed by the present invention comprises a conductor layer and an outer protection layer, the conductor layer and the outer protection layer are mutually combined for use to play a role, the outer protection layer comprises an insulating layer and a conductor shielding layer, the surface of the insulating layer is provided with a water-drop-like structure, the water-drop-like structure is a groove annularly arrayed on the surface of the insulating layer, the curvature radius of arcs at two ends of the groove is 2.4 mm, and the curvature radius of the arcs at two ends of the groove is 2.4 mm. The insulating layer is provided with a plurality of grooves, the depth of the grooves is 1.09 mm, the number of the grooves in the surface of the insulating layer is 12, the opening angle of the grooves is 30 degrees, the wind resistance is far better than that of an existing insulating cable in the market, the optimal structural state is achieved through special setting of surface structural parameters of the insulating layer, and therefore the wind resistance coefficient of 0.75 can be achieved.

Description

Technical Field

[0001] The invention relates to the field of overhead insulated cables, in particular to a low wind resistance insulated cable. Background Art

[0002] Typhoons often cause large-scale power transmission and distribution line tripping, tower collapse, and line disconnection, and storms also bring great difficulties to emergency repairs and fault recovery. Although the impact of wind speed is generally considered in the design of overhead power grids, when the wind speed exceeds a certain value, the mechanical load of line equipment in the horizontal direction facing the wind will increase, making it easy to cause accidents such as short circuits, posing an objective threat to the safe operation of overhead transmission lines.

[0003] Low wind resistance cables help reduce the impact of wind on cables. Compared with traditional steel core aluminum stranded wires, low wind resistance cables have a smaller wind resistance coefficient, that is, they bear less wind load, when the cable diameter is the same.

[0004] Although domestic and foreign patents with publication numbers CN201126737Y, CN201233737Y, EP3496113A1, CN215417612U, CN103617838A, CN102945704A, CN221261990U, WO2018025776A1, JP2022106223A, and CN205406120U disclose relevant content about low wind resistance cables, most of them are low wind resistance designs for bare cables. Of course, there are also corresponding low wind resistance designs for overhead insulated cables. However, the low wind resistance structural shapes of the above designs have not been able to significantly improve the low wind resistance effect of the insulated cables after wind tunnel tests. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a low wind resistance insulated cable to solve the above problems.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions.

[0007] A low wind resistance insulated cable comprises a conductor layer and an outer protective layer, wherein the outer protective layer is wrapped around the outside of the conductor layer, the conductor layer comprises a plurality of aluminum single wires, the outer protective layer comprises an insulating layer and a conductor shielding layer, a surface of the insulating layer is provided with a teardrop-shaped structure, the teardrop-shaped structure is a circular array of grooves on the surface of the insulating layer, the radius of curvature of the arcs at both ends of the groove is 2.4 mm, the depth of the groove is 1.09 mm, the number of the grooves in the circular array on the surface of the insulating layer is 12, the opening angle of the groove is 30°, the wind resistance is far superior to the existing insulated cables on the market, and the optimal structural state is achieved by special setting of the surface structural parameters of the insulating layer, thereby achieving a wind resistance coefficient of 0.75.

[0008] Preferably, the conductor layer includes 37 aluminum wires.

[0009] Preferably, the diameter of the aluminum single wire is 2.9 mm, and the cross-sectional area of ​​the conductor layer is 244.39 mm 2 .

[0010] Preferably, the insulating layer is made of cross-linked polyethylene.

[0011] Preferably, the average thickness of the insulating layer is not less than 3.40 mm, the thickness at the thinnest point is not less than 2.96 mm, and the maximum eccentricity is 15%.

[0012] Preferably, the conductor shielding layer comprises a base material and carbon black.

[0013] Preferably, the conductor shielding layer is a non-metallic layer extruded on the conductor layer.

[0014] Preferably, the non-metallic layer is at the same potential as the aluminum single wire.

[0015] Preferably, the average thickness of the conductor shielding layer is 0.60 mm, and the thickness at the thinnest point is 0.44 mm.

[0016] Preferably, the base material is a cross-linked semi-conductive inner shielding material.

[0017] Compared with the prior art, the present invention discloses a low wind resistance insulated cable, comprising a conductor layer and an outer protective layer, which are used in combination with each other to play a role. The outer protective layer comprises an insulating layer and a conductor shielding layer. The surface of the insulating layer is provided with a teardrop-shaped structure. The teardrop-shaped structure is a circular array of grooves on the surface of the insulating layer. The radius of curvature of the arcs at both ends of the groove is 2.4 mm, the depth of the groove is 1.09 mm, the number of grooves in the circular array on the surface of the insulating layer is 12, and the opening angle of the groove is 30°. The wind resistance is far superior to the existing insulated cables on the market. By specially setting the surface structural parameters of the insulating layer, the optimal structural state is achieved, thereby achieving a wind resistance coefficient of 0.75. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the low wind resistance insulated cable of the present invention;

[0019] Figure 2 It is a structural schematic diagram of a common round cable of the present invention;

[0020] Figure 3 It is a schematic diagram of the structure of the golf-like cable of the present invention;

[0021] Figure 4 It is a schematic diagram of the structure of the dune-like cable of the present invention;

[0022] Figure 5 The wind resistance coefficient diagram of the low wind resistance insulated cable in different shapes of the present invention;

[0023] Figure 6 It is a structural schematic diagram of the R2d1.2C8 insulated cable of the present invention;

[0024] Figure 7 It is a structural schematic diagram of the R2d1.2C10 insulated cable of the present invention;

[0025] Figure 8 It is a structural schematic diagram of the R2d1.2C12 insulated cable of the present invention;

[0026] Fig. 9 It is a structural schematic diagram of the R2d1.5C10 insulated cable of the present invention;

[0027] Fig.10 It is a structural schematic diagram of the R0.6d1.2C8 insulated cable of the present invention;

[0028] Fig.11 It is a structural schematic diagram of the R0.6d1.2C10 insulated cable of the present invention;

[0029] Fig.12 It is a structural schematic diagram of the R0.6d1.2C12 insulated cable of the present invention;

[0030] Fig.13 It is a structural schematic diagram of the R2.4d1.09C12 insulated cable of the present invention;

[0031] Fig.14 It is a structural schematic diagram of a common insulated cable of the present invention;

[0032] Fig.15 The wind resistance coefficient diagram of the low wind resistance insulated cable with different slot numbers of the present invention;

[0033] Fig.16 The wind resistance coefficient diagram of the low wind resistance insulated cable under different curvature radii of the present invention;

[0034] Fig.17 The wind resistance coefficient diagram of the low wind resistance insulated cable at different groove depths of the present invention;

[0035] Fig.18 This is a wind tunnel test result diagram of the wind resistance performance verification test of the present invention;

[0036] Fig.19 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 10 m / s;

[0037] Fig. 20 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 15 m / s;

[0038] Fig.21 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 20 m / s;

[0039] Fig. 22 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 25 m / s;

[0040] Fig.23 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 30 m / s;

[0041] Fig.24 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 35 m / s;

[0042] Fig.25 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 40 m / s;

[0043] Fig.26 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 45 m / s;

[0044] Fig. 27 This is a simulation experiment diagram of the low wind resistance insulated cable of the present invention at a wind speed of 50m / s. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0046] A low wind resistance insulated cable, comprising a conductor layer and an outer protective layer, wherein the outer protective layer is wrapped around the outside of the conductor layer, the conductor layer comprises a plurality of aluminum single wires, the outer protective layer comprises an insulating layer and a conductor shielding layer, the surface of the insulating layer is provided with a teardrop-like structure, the teardrop-like structure is a groove in a circular array on the surface of the insulating layer, the radius of curvature of the circular arcs at both ends of the groove is 2.4 mm, the depth of the groove is 1.09 mm, the number of the grooves in the circular array on the surface of the insulating layer is 12, and the opening angle of the groove is 30°.

[0047] The conductor layer includes 37 aluminum single wires, the diameter of the aluminum single wire is 2.9 mm, and the cross-sectional area of ​​the conductor layer is 244.39 mm 2 .

[0048] The insulating layer is made of cross-linked polyethylene, the average thickness of the insulating layer is not less than 3.40 mm, the thickness at the thinnest part is not less than 2.96 mm, and the maximum eccentricity is 15%.

[0049] The conductor shielding layer includes a base material and carbon black.

[0050] The conductor shielding layer is a non-metallic layer extruded on the conductor layer. The non-metallic layer has the same potential as the aluminum single wire. The average thickness of the conductor shielding layer is 0.60 mm, and the thinnest thickness is 0.44 mm.

[0051] The matrix material is a cross-linked semi-conductive inner shielding material.

[0052] The low-drag cable with a fan-shaped cross-section of the outer strands has been found through field tests to have a wind resistance coefficient of less than 70% of that of ordinary cables within a wind speed range of 30 to 60 m / s. Four types of grooved cables are now used as research objects, indicating that within the range of 10 to 20 m / s, the cable wind resistance coefficient increases linearly with the increase in the roughness of the cable cross section. Within the range of 20 to 60 m / s, the cable wind resistance coefficient is determined by a two-variable quadratic function consisting of the number of cross-sectional grooves and the groove radius.

[0053] The convex arc of the outer single wire of the low-drag cable is changed to a concave arc, and the wind resistance coefficient of the cable is reduced by designing the depth of the concave arc. For insulated cables, the surface shape of the insulation layer can be optimized and designed using the fluid mechanics turbulence theory to effectively reduce wind resistance. At present, due to the influence of the special-shaped extrusion process of the insulation layer, there are few research results on low-drag insulated cables at home and abroad, and the research on low-drag insulated cables is still in its infancy. Therefore, the process of obtaining the best model based on the following experiments is as follows:

[0054] S1. According to the theory of flow around cylinder, the surface of the insulating layer is designed to imitate the golf ball type, water drop type and sand dune type. The specific analysis steps are as follows:

[0055] The surface structure of the insulation layer is designed for golf-like surface structure, water drop-like structure of free fall motion, and sand dune-like structure. These three types are compared with ordinary insulated cables through CFD simulation. The turbulence model of low wind resistance insulated cable uses Shear Stress Transport k-εModel during CFD simulation, and the finite volume method and SIMPLEC algorithm are used to solve it. The momentum, turbulent kinetic energy k and turbulent dissipation rate ε are all discrete in second-order precision format. The air density and viscosity are both default values, and the cable model size is consistent with the actual size. (The wind speed during simulation is from 10m / s-50m / s, the interval is 5m / s, and the wind deflection angle is 90°). Through CFD simulation, it can be concluded that the wind resistance of low wind resistance insulated cable is better than that of ordinary round cable at wind speeds above 20m / s. Among them, the wind resistance coefficient of water drop-like insulated cable decreases significantly with the increase of wind speed when it is 20m / s~50m / s, which is better than the other three cables.

[0056] ① When there are dimples on the golf-like surface, the dimples promote turbulent transition, and the turbulent boundary layer is less likely to separate, which reduces the low-pressure area behind the ball and reduces the resistance, thus increasing the flying distance of the golf ball.

[0057] ② The water drop-like shape of free fall is a streamlined shape, characterized by a smooth front and a flat rear, which reduces the pressure difference resistance of the object flowing around;

[0058] ③ The stress-bearing parts of the dune-like shape that are subject to large wind resistance will gradually deform and eventually form a shape with minimal wind resistance. The formation of this shape is conducive to the flow of wind, that is, the wind flow resistance is small.

[0059] Then, different groove numbers, groove depths, and curvature radii of the arcs at both ends of the grooves were designed for the teardrop-shaped structure, and the actual objects were made and compared with ordinary round cables in wind tunnel experiments. The cable was made by a frame stranding machine and an extruder, and the wind tunnel experiment was carried out in a low-speed reflux wind tunnel laboratory. The laboratory can generate wind speeds of 0m / s to 60m / s, with a uniform wind field and continuously adjustable wind speed. The wind tunnel experiment wind speed loading interval is 5m / s, the sampling frequency is 1000Hz, the sampling time is 30s, the cable length is 1m, fixed on the bracket, and a six-dimensional force balance is installed on the bracket. The wind resistance of the cable can be obtained based on the force applied to the bracket before and after the experiment. The calculation formula for the wind resistance coefficient of the cable is as follows:

[0060]

[0061] Among them, C d is the wind resistance coefficient of the cable, F D is the resistance of the cable, ρ is the air density, V is the actual wind speed, D is the diameter of the cable, and L is the effective length of the cable.

[0062] Through wind tunnel experiments on cables with different teardrop-shaped structures and ordinary insulated cables, it was found that the radius of curvature of the arcs at both ends of the groove has a greater effect on wind resistance than the depth of the groove. Too deep grooves may even have a negative effect on wind resistance. As for the number of grooves, by comparing the calculated data of different numbers of grooves under the same groove shape, it was found that the number of grooves is negatively correlated with wind resistance.

[0063] The first step is to study the effect of the number of grooves on the wind resistance coefficient of low wind resistance insulated cables. The number of grooves is equal to 360° divided by the cable surface opening angle. Due to the limitations of processing technology and installation grip requirements, the number of grooves is generally set to an even number and not more than 12. Therefore, four cable models are designed for comparative analysis, in which the curvature radius R of the arc at both ends of the groove is 0.6mm, the groove depth d is 1.2mm, and the number of grooves C is 6, 8, 10, and 12 respectively. As follows Fig.15 The figure shows the wind resistance coefficient of the cable with different numbers of slots. It can be concluded that when the wind speed is greater than 25m / s, the more slots there are, the lower the wind resistance coefficient is.

[0064] The second step is to study the effect of the radius of curvature of the arc at both ends of the groove on the wind resistance coefficient of the low wind resistance insulated cable. Due to the limitation of processing technology and the thickness of the outer insulation layer is generally 3mm to 3.4mm, the radius of curvature of the arc at both ends of the groove is generally in the range of 0.6mm to 2mm. Therefore, two cable models are designed for comparative analysis, in which the groove depth d is 1.2mm, the number of grooves C is 12, and the curvature radius R is 0.6mm and 2mm respectively. As follows Fig.16 The figure shows the wind resistance coefficient of the cable under different curvature radii. It can be concluded that the larger the curvature radius, the lower the wind resistance coefficient.

[0065] The third step is to study the effect of groove depth on the wind resistance coefficient of low wind resistance insulated cables. Too deep grooves will reduce the contact surface of the hardware, causing problems with the installation grip. Therefore, when the number of grooves does not exceed 10, the groove depth is generally not more than 1.5mm, and when the number of grooves does not exceed 12, the groove depth is not more than 1.2mm. Therefore, three cable models are designed for comparative analysis, in which the curvature radius R is 2mm, the number of grooves C is 12, and the groove depths d are 1mm, 1.2mm, and 1.5mm respectively. As follows Fig.17 The figure shows the cable drag coefficient at different groove depths. It can be concluded that when the wind speed is less than 30m / s, the smaller the groove depth, the lower the drag coefficient. When the wind speed is greater than 30m / s, the drag coefficient is the smallest when the groove depth is 1.2mm.

[0066] In summary, the curvature radius and the number of grooves of the outer surface structure of the teardrop-shaped insulated cable are inversely proportional to the drag coefficient. At low wind speeds, the groove depth is proportional to the drag coefficient, and at high wind speeds, the drag coefficient is optimal when the groove depth is about 1.2 mm. At the same time, due to the limitations of the outer insulation size, processing technology, installation grip requirements and other conditions, various structural parameters need to be comprehensively considered when developing and selecting low-drag insulated cables.

[0067] Finally, based on the structural parameter design results and the need to resist strong winds, eight types of teardrop-shaped low wind resistance insulated cables, namely R2d1.2C8, R2d1.2C10, R2d1.2C12, R2d1.5C10, R0.6d1.2C8, R0.6d1.2C10, R0.6d1.2C12, and R2.4d1.09C12, were selected for trial production, and a total of nine types of insulated cables, together with ordinary round conductors, were tested for wind resistance verification.

[0068] The wind tunnel test results are as follows: Fig.18 As shown, Figure 19-Figure 27They are respectively the simulation experiment diagrams of R2.4d1.09C12 type teardrop-shaped low wind resistance insulated cable from 10m / s to 50m / s. It is finally concluded that R2.4d1.09C12 type (curvature radius is 2.4mm, groove depth is 1.09mm, number of grooves is 12, opening angle is 30°) teardrop-shaped low wind resistance insulated cable has the best strong wind resistance performance, which is more than 30% higher than ordinary insulated cables.

[0069] The insulation layer is made of black cross-linked polyethylene, with an average minimum thickness of 3.40 mm, a minimum thickness of 2.96 mm at the thinnest point, and a maximum eccentricity of 15%. The insulation eccentricity calculation formula is:

[0070]

[0071] The conductor shielding layer is a non-metallic layer extruded on the cable conductor and has the same potential as the conductor. Its average thickness is 0.60mm and the thinnest thickness is 0.44mm. The base material of the conductor shielding layer is a cross-linked semi-conductive inner shielding material, which is usually consistent with the material of the conductor and has a density of 1.2g / cm 3 .

[0072] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0073] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low wind resistance insulated cable, characterized in that: It includes a conductor layer and an outer protective layer, the outer protective layer is wrapped around the outside of the conductor layer, the conductor layer includes a plurality of aluminum single wires, the outer protective layer includes an insulating layer and a conductor shielding layer, the surface of the insulating layer is provided with a water drop-like structure, the water drop-like structure is a groove in a circular array on the surface of the insulating layer, the radius of curvature of the arc at both ends of the groove is 2.4mm, the depth of the groove is 1.09mm, the number of the grooves in the circular array on the surface of the insulating layer is 12, and the opening angle of the groove is 30°.

2. The low wind resistance insulated cable according to claim 1, characterized in that: The conductor layer includes 37 aluminum single wires.

3. The low wind resistance insulated cable according to claim 2, characterized in that: The diameter of the aluminum single wire is 2.9 mm, and the cross-sectional area of ​​the conductor layer is 244.39 mm 2 .

4. The low wind resistance insulated cable according to claim 1, characterized in that: The insulating layer is made of cross-linked polyethylene.

5. The low wind resistance insulated cable according to claim 4, characterized in that: The average thickness of the insulating layer is not less than 3.40 mm, the thickness at the thinnest part is not less than 2.96 mm, and the maximum eccentricity is 15%.

6. The low wind resistance insulated cable according to claim 1, characterized in that: The conductor shielding layer includes a base material and carbon black.

7. The low wind resistance insulated cable according to claim 6, characterized in that: The conductor shielding layer is a non-metallic layer extruded on the conductor layer.

8. The low wind resistance insulated cable according to claim 7, characterized in that: The non-metallic layer is at the same potential as the aluminum single wire.

9. The low wind resistance insulated cable according to claim 6, characterized in that: The average thickness of the conductor shielding layer is 0.60 mm, and the thickness at the thinnest part is 0.44 mm.

10. The low wind resistance insulated cable according to claim 6, characterized in that: The matrix material is a cross-linked semi-conductive inner shielding material.

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