Insulating material for ultrahigh-voltage cable accessories

Abstract

The invention discloses an insulating material for ultrahigh-voltage cable accessories, and belongs to the technical field of cable accessory materials. The insulating material for the ultrahigh-voltage cable accessory comprises the following raw material components: a rubber base material, a filler composition for adjusting the volume resistivity of the insulating material, an activating agent, zinc oxide, an accelerant composition and a vulcanizing agent composition, wherein the rubber base material is ethylene propylene diene monomer; the filler composition can be prepared from the following components in parts by weight: 40 to 55 parts of filling material, 4 to 5 parts of carbon nano tube and 0.5 to 1 part of graphite micro powder; the filler composition can also comprise the following components in parts by weight: 50-65 parts by mass of a filling material, 2-3 parts by mass of nano zinc oxide and 16-18 parts by mass of copper calcium titanate.

Description

Technical Field

[0001] The invention relates to an insulating material for ultra-high voltage cable accessories. Background Art

[0002] With the rapid development of social economy and the growth of energy demand, the power transmission system is facing new challenges and opportunities. Especially in the field of long-distance and large-capacity power transmission, ultra-high voltage direct current (UHVDC) transmission technology has gradually become the mainstream choice with its unique advantages. The UHVDC transmission system usually operates at a voltage level of 330kV to 800kV. Compared with the traditional AC transmission method, it can not only provide a more flexible power adjustment range and a simpler power control mechanism, but also effectively reduce the reactive power loss and line voltage drop during the transmission process, thereby reducing the overall transmission cost. These characteristics make UHVDC technology show significant technical and economic benefits in multiple application scenarios such as long-distance high-power transmission, cross-sea cable transmission, and asynchronous interconnection between different power grids.

[0003] However, to achieve the transformation of long-distance power transmission to ultra-high voltage DC cable transmission, it is necessary not only to solve complex electrical engineering design and technical problems, but also to overcome challenges in material science. In particular, the manufacturing technology of ultra-high voltage DC cables and their accessories has become one of the key technical bottlenecks in this transformation process. Among these technical challenges, the development of insulating materials for ultra-high voltage DC cable accessories is particularly critical.

[0004] For the insulating materials used in UHV DC cable accessories, precise control of their volume resistivity is crucial. Since such materials are subject to the combined effects of DC electric field strength and temperature during use, their internal electric field distribution is more complicated than under AC conditions. If the volume resistivity of the insulating material is not properly selected, the electric field stress may be concentrated at the interface between the cable insulation layer and the stress cone, eventually causing the insulation material in this area to break down during long-term operation, seriously threatening the safety and reliability of the entire transmission system.

[0005] Therefore, the present invention provides an insulating material for ultra-high voltage cable accessories to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide an insulating material for ultra-high voltage cable accessories to solve the technical problems mentioned in the above background technology.

[0007] The technical solution for achieving the purpose of the present invention is:

[0008] An insulating material for ultra-high voltage cable accessories, the raw material components include a rubber base material, an activator, zinc oxide, an accelerator composition, a vulcanizer composition and a filler composition for adjusting the volume resistivity of the insulating material.

[0009] Furthermore, the rubber base material is ethylene propylene diene monomer rubber, and the rubber base material is 90 to 120 parts by weight.

[0010] Furthermore, the activator is stearic acid, and the added amount of stearic acid is 0.5 to 1 parts by weight.

[0011] Furthermore, the added amount of zinc oxide is 4 to 5 parts by weight.

[0012] Furthermore, the filler composition comprises, by weight, 40 to 55 parts by weight of filler material, 4 to 5 parts by weight of carbon nanotubes, and 0.5 to 1 part by weight of graphite powder.

[0013] Furthermore, the accelerator composition comprises, by weight, 0.2 to 0.4 parts by weight of accelerator DM and 0.1 to 0.2 parts by weight of TMTD.

[0014] Furthermore, the accelerator composition comprises, by weight, 0.2 to 0.4 parts by weight of sulfur, 0.2 to 0.4 parts by weight of DTDM, and 1 to 2 parts by weight of DCP.

[0015] Furthermore, the filler composition comprises, by weight, 50 to 65 parts by weight of filler material, 2 to 3 parts by weight of nano zinc oxide, and 16 to 18 parts by weight of copper calcium titanate.

[0016] Furthermore, the accelerator composition comprises, by weight, 0.2 to 0.4 parts by weight of accelerator DM and 0.1 to 0.2 parts by weight of TMTD.

[0017] Furthermore, the accelerator composition comprises, by weight, 1 to 2 parts by weight of sulfur, 2 to 4 parts by weight of DTDM, and 1 to 2 parts by weight of DCP.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects:

[0019] (1) The insulating material for ultra-high voltage cable accessories of the present invention controls the volume resistivity of the insulating material for ultra-high voltage cable accessories by introducing a filler composition for adjusting the volume resistivity of the insulating material. When used in ultra-high voltage DC cable accessories, it avoids the accumulation of charges inside the material to cause the electric field stress to break down during long-term operation, thereby ensuring the stable operation of the ultra-high voltage cable accessories in an ultra-high voltage electric field, thereby ensuring the safety and reliability of the entire power transmission system.

[0020] (2) The present invention selects EPDM rubber as the rubber substrate, and utilizes the advantages of EPDM rubber such as high molecular density, good tear resistance, large elastic modulus, high tensile strength, good electrical insulation, and low price to preliminarily improve the problem of space charge accumulation in insulating materials.

[0021] (3) The present invention uses stearic acid as an activator, which can accelerate the vulcanization speed and improve the vulcanization efficiency.

[0022] (4) The present invention adopts zinc oxide, which can accelerate the vulcanization speed and improve the vulcanization efficiency.

[0023] (5) The filler composition of the present invention is obtained by combining 40 to 55 parts by mass of filler material, 4 to 5 parts by mass of carbon nanotubes, and 0.5 to 1 parts by mass of graphite powder. By adding 4 to 5 parts by mass of carbon nanotubes and 0.5 to 1 parts by mass of graphite powder to adjust the overall volume resistivity of the insulating material, it is possible to avoid excessive concentration of electric field stress while ensuring that the material has sufficiently high insulation performance.

[0024] (6) The filler composition of the present invention is obtained by combining 50 to 65 parts by mass of filler material, 2 to 3 parts by mass of nano zinc oxide, and 16 to 18 parts by mass of copper calcium titanate. On the one hand, nano zinc oxide can inhibit the accumulation of space charge and can also inhibit the accumulation of space charge under temperature gradient, thereby improving the DC breakdown strength and volume resistivity of the insulating material; copper calcium titanate has a giant dielectric constant ε≈104-105 and an extremely low loss tgδ≈0.03, especially in a wide temperature range of 100-400K, the dielectric constant value is almost unchanged, and has high thermal stability of dielectric response; on the other hand, the filler composition is 2 to 3 parts by mass of filler material. The combination of 16 to 18 parts by weight of nano zinc oxide and 16 to 18 parts by weight of copper calcium titanate can effectively reduce the density of charge traps in insulating materials, inhibit the accumulation of space charges, and improve the DC breakdown strength and volume resistivity of insulating materials. The interfacial interaction between nano zinc oxide and copper calcium titanate can form a new charge transfer path, and the charges can move faster inside the material, which helps to reduce the accumulation of space charges and avoid the breakdown of electric field stress caused by charge accumulation inside the material during long-term operation, thereby ensuring the stable operation of ultra-high voltage cable accessories in ultra-high voltage electric fields, thereby ensuring the safety and reliability of the entire transmission system. DETAILED DESCRIPTION

[0025] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods.

[0026] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the protection scope of the present invention.

[0027] Charge traps are locations within a material that can capture free charges. These traps restrict the movement of charges and lead to space charge accumulation.

[0028] DM is dibenzothiazyl disulfide;

[0029] TMTD is dithiocarbonyl dimethylamine disulfide;

[0030] DTDM is 4,4′-dithiodimorpholine;

[0031] DCP is dicumyl peroxide;

[0032] The filling material is fumed silica.

[0033] (Example 1)

[0034] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 90 parts by weight of EPDM rubber, 0.5 parts by weight of stearic acid, 4 parts by weight of zinc oxide, 40 parts by weight of filler material, 4 parts by weight of carbon nanotubes, 0.5 parts by weight of graphite powder, 0.2 parts by weight of accelerator DM, 0.1 parts by weight of TMTD, 0.2 parts by weight of sulfur, 0.2 parts by weight of DTDM and 1 part by weight of DCP.

[0035] (Example 2)

[0036] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 120 parts by weight of EPDM rubber, 1 part by weight of stearic acid, 5 parts by weight of zinc oxide, 55 parts by weight of filler material, 5 parts by weight of carbon nanotubes, 1 part by weight of graphite powder, 0.4 parts by weight of accelerator DM, 0.2 parts by weight of TMTD, 0.4 parts by weight of sulfur, 0.4 parts by weight of DTDM and 2 parts by weight of DCP.

[0037] (Example 3)

[0038] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 105 parts by weight of EPDM rubber, 0.7 parts by weight of stearic acid, 4.5 parts by weight of zinc oxide, 50 parts by weight of filler material, 4.5 parts by weight of carbon nanotubes, 0.7 parts by weight of graphite powder, 0.3 parts by weight of accelerator DM, 0.2 parts by weight of TMTD, 0.3 parts by weight of sulfur, 0.3 parts by weight of DTDM and 1.5 parts by weight of DCP.

[0039] (Example 4)

[0040] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight, 90 parts by weight of EPDM rubber, 0.5 parts by weight of stearic acid, 4 parts by weight of zinc oxide, 50 parts by weight of filler material, 2 parts by weight of nano zinc oxide, 16 parts by weight of copper calcium titanate, 0.2 parts by weight of accelerator DM, 0.1 parts by weight of TMTD, 1 part by weight of sulfur, 2 parts by weight of DTDM and 1 part by weight of DCP.

[0041] (Example 5)

[0042] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 120 parts by weight of EPDM rubber, 1 part by weight of stearic acid, 5 parts by weight of zinc oxide, 65 parts by weight of filling material, 3 parts by weight of nano zinc oxide, 18 parts by weight of calcium copper titanate, 0.4 parts by weight of accelerator DM, 0.2 parts by weight of TMTD, 2 parts by weight of sulfur, 4 parts by weight of DTDM and 2 parts by weight of DCP.

[0043] (Example 6)

[0044] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 105 parts by weight of EPDM rubber, 0.7 parts by weight of stearic acid, 4.5 parts by weight of zinc oxide, 58 parts by weight of filler material, 2.5 parts by weight of nano zinc oxide, 17 parts by weight of calcium copper titanate, 0.3 parts by weight of accelerator DM, 0.2 parts by weight of TMTD, 1.5 parts by weight of sulfur, 3 parts by weight of DTDM and 1.5 parts by weight of DCP.

[0045] (Comparative Example 1)

[0046] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 105 parts by weight of EPDM rubber, 0.7 parts by weight of stearic acid, 4.5 parts by weight of zinc oxide, 58 parts by weight of filling material, 2.5 parts by weight of nano zinc oxide, 0.3 parts by weight of accelerator DM, 0.2 parts by weight of TMTD, 1.5 parts by weight of sulfur, 3 parts by weight of DTDM and 1.5 parts by weight of DCP.

[0047] (Comparative Example 2)

[0048] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 110 parts by weight of EPDM rubber, 0.8 parts by weight of stearic acid, 4.5 parts by weight of zinc oxide, 60 parts by weight of filler material, 3 parts by weight of nano zinc oxide, 20 parts by weight of calcium copper titanate, 0.3 parts by weight of accelerator DM, 0.2 parts by weight of TMTD, 1.5 parts by weight of sulfur, 3 parts by weight of DTDM and 1.5 parts by weight of DCP.

[0049] (Blank example)

[0050] The invention discloses an insulating material for ultra-high voltage cable accessories. The raw material components thereof are, by weight: 110 parts by weight of EPDM rubber, 0.8 parts by weight of stearic acid, 5 parts by weight of zinc oxide, 55 parts by weight of filling material, 0.3 parts by weight of accelerator DM, 0.1 parts by weight of TMTD, 1 part by weight of sulfur, 4 parts by weight of DTDM and 1 part by weight of DCP.

[0051] Effect example

[0052] Table 1 below shows the performance data of the insulating materials for ultra-high voltage cable accessories of Examples 1 to 6 of the present invention, Comparative Examples 1 to 2, and a blank example:

[0053] Table 1

[0054]

[0055] From the above table, it can be seen that the performance data results of the insulating materials for ultra-high voltage cable accessories of Examples 1 to 6 and Comparative Examples 1 to 2 show that the insulating materials for ultra-high voltage cable accessories of Examples 1 to 6 have better anti-puncture effect. Compared with Example 4, Comparative Example 1 does not add copper calcium titanate, and the DC breakdown strength of the positive and negative electrodes is 70 (kV / mm) and 75 (kV / mm), respectively. The DC breakdown strength does not reach the performance index of the insulating material for ultra-high voltage cable accessories, and the anti-puncture effect is poor. Compared with Example 4, Comparative Example 2 does not add nano zinc oxide. Although the positive The negative electrode DC breakdown strength is 78 (kV / mm) and 76 (kV / mm), respectively. The DC breakdown strength is higher than that of Comparative Example 1, but still does not reach the performance index of the insulating material for ultra-high voltage cable accessories, and the anti-breakdown effect is poor. It can be seen that the filler composition of Examples 4 to 6 uses 2 to 3 parts by mass of nano zinc oxide and 16 to 18 parts by mass of copper calcium titanate in combination, which meets the performance index of the insulating material for ultra-high voltage cable accessories. The nano zinc oxide and copper calcium titanate have a synergistic effect in the parts by weight, and the anti-breakdown effect is better.

[0056] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An insulating material for ultra-high voltage cable accessories, characterized in that: The raw material components include a rubber base material, an activator, zinc oxide, an accelerator composition, a vulcanizer composition and a filler composition for adjusting the volume resistivity of the insulating material.

2. The insulating material for ultra-high voltage cable accessories according to claim 1, characterized in that: The rubber base material is ethylene propylene diene monomer rubber, and the rubber base material accounts for 90 to 120 parts by weight.

3. The insulating material for ultra-high voltage cable accessories according to claim 2, characterized in that: The activator is stearic acid, and the added amount of stearic acid is 0.5 to 1 parts by weight.

4. The insulating material for ultra-high voltage cable accessories according to claim 3, characterized in that: The added amount of the zinc oxide is 4 to 5 parts by weight.

5. The insulating material for ultra-high voltage cable accessories according to claim 4, characterized in that: The filler composition comprises, by weight, 40 to 55 parts by weight of filler material, 4 to 5 parts by weight of carbon nanotubes, and 0.5 to 1 part by weight of graphite powder.

6. The insulating material for ultra-high voltage cable accessories according to claim 4, characterized in that: The filler composition comprises, by weight, 50 to 65 parts of filler material, 2 to 3 parts of nano zinc oxide, and 16 to 18 parts of copper calcium titanate.

7. The insulating material for ultra-high voltage cable accessories according to claim 5, characterized in that: The accelerator composition comprises 0.2 to 0.4 parts by weight of accelerator DM and 0.1 to 0.2 parts by weight of TMTD.

8. The insulating material for ultra-high voltage cable accessories according to claim 6, characterized in that: The accelerator composition comprises, by weight, 0.2 to 0.4 parts by weight of accelerator DM and 0.1 to 0.2 parts by weight of TMTD.

9. The insulating material for ultra-high voltage cable accessories according to claim 7, characterized in that: The accelerator composition comprises, by weight, 0.2 to 0.4 parts by weight of sulfur, 0.2 to 0.4 parts by weight of DTDM, and 1 to 2 parts by weight of DCP.

10. The insulating material for ultra-high voltage cable accessories according to claim 8, characterized in that: The accelerator composition comprises, by weight, 1 to 2 parts by weight of sulfur, 2 to 4 parts by weight of DTDM, and 1 to 2 parts by weight of DCP.

Images