A 72.5kV detachable light environment-friendly GIL bus unit

Abstract

This invention discloses a 72.5kV detachable lightweight and environmentally friendly GIL busbar unit, characterized by comprising a center conductor, male and female plug contacts, a shield, a metal shell, a modified porous methacrylimide copolymer dielectric (MPPD), conductive springs, and positioning copper rods. The MPPD completely fills the space between the center conductor and the metal shell, replacing traditional insulators and SF₆ insulating gas. Flexible electrical connection is achieved between the male and female plug contacts using spring-loaded contact fingers. The shield covers the outside of the plug-in position. The shield and the male plug are detachably axially positioned via the conductive springs and positioning copper rods. The shell and center conductor are coaxially arranged, with the center conductor having an outer diameter of 8-12mm, the shell having an inner diameter of 25-35mm, and a shell thickness of 4-8mm. This invention significantly reduces density, resulting in significantly lower transportation and installation costs. The MPPD eliminates SF₆ gas, thus eliminating strong greenhouse gas emissions at the source.

Description

Technical Field

[0001] This invention relates to high-voltage power transmission and transformation equipment technology, specifically to a 72.5kV detachable lightweight and environmentally friendly GIL busbar unit. Background Technology

[0002] Gas-insulated transmission lines (GILs) offer high transmission capacity, low loss, and flexible layout, making them a core component of high-voltage transmission equipment. Traditional GILs, however, suffer from the following drawbacks:

[0003] 1) Basin-type insulators have high density and heavy weight, making transportation and installation complex;

[0004] 2) The interior is filled with SF6, which has an extremely strong greenhouse effect, with a GWP value 23,900 times that of CO2. Leakage will cause environmental hazards.

[0005] 3) Existing plug-in connections are mostly rigid and fixed, which is inconvenient to disassemble and assemble, the electric field is easy to concentrate, and maintenance is difficult;

[0006] 4) The insulation and support structures are separated, making it difficult to achieve lightweight, high insulation, and high mechanical reliability at the same time.

[0007] Existing technologies mostly focus on gas replacement, insulator modification, or contact shielding improvement, but have not achieved integrated innovation in insulation medium, support structure, and connection method, and cannot fundamentally solve the problems of weight, environmental protection, disassembly and assembly, and insulation synergistic optimization. Summary of the Invention

[0008] To address the following technical problems in existing technologies: 1. reducing the overall weight of GIL (Gas Insulation Line) and simplifying installation and transportation; 2. replacing SF6 gas and eliminating strong greenhouse gas emissions; 3. achieving detachable and quick assembly / disassembly to improve maintenance convenience; 4. ensuring high insulation strength, uniform electric field distribution, and qualified temperature rise levels, this invention proposes a detachable, lightweight, and environmentally friendly GIL busbar unit.

[0009] Technical solution:

[0010] This invention discloses a 72.5kV detachable lightweight and environmentally friendly GIL busbar unit, comprising a center conductor, male and female plug contacts, a shield, a metal shell, a modified porous methacrylimide copolymer dielectric (MPPD), a conductive spring, and a positioning copper rod. The MPPD is fully filled between the center conductor and the metal shell, replacing traditional insulators and SF6 insulating gas. The male and female plug contacts are connected by spring fingers to achieve flexible electrical connection. The shield covers the outside of the plug position. The shield and the male plug are detachably axially positioned by the conductive spring and the positioning copper rod. The shell and the center conductor are coaxially arranged, with the outer diameter of the center conductor being 8~12mm, the inner diameter of the shell being 25~35mm, and the shell thickness being 4~8mm.

[0011] Preferably, the MPPD has a density <0.1g / cm³, a power frequency breakdown field strength of 33.1kV / mm, a broadband dielectric constant <2.5, a dielectric loss tanδ≤0.1, and a thermal decomposition temperature of 320℃.

[0012] Preferably, the male and female plug contacts adopt a male and female plug-in form, and multiple sets of circumferentially distributed spring contact fingers are provided between the male and female plugs.

[0013] Preferably, the arc-shaped shield is a cylindrical structure with rounded transitions at both ends on the outer side and a uniform gap between the inner side and the outer wall of the contact, so as not to generate a floating potential.

[0014] Preferably, during assembly, a conductive spring pushes the copper rod into the groove of the shielding cover to achieve axial positioning; during disassembly, a pin presses the copper rod through the through hole of the shielding cover to separate the male and female plugs.

[0015] Preferably, when the rated current is 315A, the highest temperature of the center conductor is about 53°C, with a temperature rise of 33°C; the outer casing temperature is close to the ambient temperature, meeting the requirements of GB / T11022 standard.

[0016] Preferably, the male plug, female plug, shield, and outer shell are made of aluminum, the spring contacts are made of beryllium bronze, and the center conductor is made of oxygen-free copper.

[0017] Preferably, MPPD is obtained through the following steps:

[0018] S1. Preparation of prepolymer: Magnesium oxide (MgO) and allyl methacrylate (AMA) are mixed in a mass ratio of (6~7):5 and dissolved in 400~500 parts by mass of methacrylate (MAA) to obtain a crosslinking agent;

[0019] Separately take 450-750 parts by weight of acrylonitrile AN, 0.5-1 parts by weight of dodecyl peroxide LPO, 0.5-1 parts by weight of tert-butyl peroxide (2-ethylhexanoate) OT, 0.5 parts by weight of tert-butyl peroxide TBPB, 60-80 parts by weight of isoacetone, 50-70 parts by weight of formamide, and 20 parts by weight of carbamide and mix with the crosslinking agent and stir for the first time. After heating, stir for the second time.

[0020] S2. Preparation of polymethacrylimide porous insulating electrical material MPPD: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2-3 hours at 45-65℃, 65-85℃, and 85-105℃. Then, it was subjected to heat treatment at 150-160℃ / 2 hours and foaming treatment at 190-200℃ / 2 hours. After cooling to room temperature, MPPD was obtained.

[0021] Preferably, MPPD is obtained through the following steps:

[0022] S1. Preparation of prepolymer: Magnesium oxide (MgO) and allyl methacrylate (AMA) are mixed in a mass ratio of (6~7):5 and dissolved in 400~500 parts by mass of methacrylate (MAA) to obtain a crosslinking agent;

[0023] Separately take 550-650 parts by weight of acrylonitrile AN, 0.5-1 parts by weight of dodecyl peroxide LPO, 0.5-1 parts by weight of tert-butyl peroxide (2-ethylhexanoate) OT, 0.5 parts by weight of tert-butyl peroxide TBPB, 60-80 parts by weight of isoacetone, 50-70 parts by weight of formamide, and 20 parts by weight of carbamide and mix with the crosslinking agent. Stir for the first time for 1-2 hours, heat to 40-50℃ and then stir for the second time for 72-84 hours.

[0024] S2. Preparation of polymethacrylimide porous insulating electrical material MPPD: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2-3 hours at 50-60℃, 70-80℃, and 90-100℃. Then, it was subjected to heat treatment at 150-160℃ / 2 hours and foaming treatment at 190-200℃ / 2 hours. After cooling to room temperature, MPPD was obtained.

[0025] Preferably, AN, LPO, OT, TBPB, crosslinking agent, isopropanol, formamide, and carbamide are added in sequence and mixed.

[0026] Beneficial effects of the present invention

[0027] 1. Ultra-lightweight: The density is greatly reduced, resulting in significantly lower transportation and installation costs.

[0028] 2. Green and environmentally friendly: MPPD eliminates SF6 gas, thus eliminating strong greenhouse gas emissions at the source.

[0029] 3. High insulation reliability: The field strength and partial discharge level are far below the material's tolerance value, and the insulation margin is sufficient.

[0030] 4. Quick disassembly and assembly: The plug-in structure combined with detachable positioning facilitates inspection and replacement.

[0031] 5. Temperature rise compliance: The temperature rise during current flow meets national standards and ensures stable long-term operation. Attached Figure Description

[0032] Figure 1 Cross-sectional structural diagram of the GIL bus unit of this invention.

[0033] Figure 2 The image shows the Weibull distribution of the power frequency breakdown field strength of the MPPD in this embodiment.

[0034] Figure 3 The diagram shows the relative permittivity of the MPPD in this embodiment.

[0035] Figure 4 This is a diagram showing the dielectric loss tangent of the MPPD in the embodiment. Detailed Implementation

[0036] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:

[0037] 1. Overall Structure

[0038] like Figure 1 As shown, the 72.5kV pluggable lightweight and environmentally friendly GIL busbar unit includes: a center conductor, a male plug, a female plug, spring contacts, an arc-shaped shield, a conductive spring, a positioning copper rod, a 6061 aluminum alloy shell, and MPPD porous material. The MPPD is fully filled between the conductor and the shell, achieving integrated insulation and support.

[0039] 2. Material parameters

[0040] Material parameters are shown in Table 1:

[0041] Table 1 Material parameters of 72.5kV pluggable lightweight environmentally friendly GIL busbar unit

[0042]

[0043] 3. Connection and Positioning

[0044] The male and female plugs interlock to achieve electrical conduction, while evenly distributed circumferential spring contacts ensure a flexible and reliable electrical connection. An arc-shaped shield covers the plug joint, with rounded ends providing a uniform electric field transition. A conductive spring and copper rod are installed between the shield and the male plug: during assembly, the spring lifts the copper rod, locking it into the groove of the shield and limiting axial displacement; during disassembly, a pin is used to press the copper rod through the through-hole of the shield to remove the male plug.

[0045] 4. Size Design

[0046] According to GB / T22383-2017, the rated lightning impulse withstand voltage is 325kV, and the dimensions are determined as shown in Table 2:

[0047] Table 2 Dimension Design of 72.5kV Pluggable Lightweight and Environmentally Friendly GIL Busbar Unit

[0048]

[0049] It has a short-time withstand current of 31.5kA and the casing will not be burned through by an electric arc within 0.2s.

[0050] 5. Mechanical adaptation

[0051] MPPD meets support requirements through global stress dispersion. The actual stress is far lower than the tensile and bending strength of the material, eliminating the need for traditional pot-type insulators, thus simplifying the structure and reducing weight.

[0052] The electrical performance of the MPPD was verified by combining specific implementation examples and conducting performance tests.

[0053] Experimental reagents: Acrylonitrile (AN, 99%), tert-butyl peroxide (OT, 98%), tert-butyl peroxide (TBPB, 98%), magnesium oxide (MgO, 98%), dodecyl peroxide (LPO, 98%), allyl methacrylate (AMA, 98%), formamide (≥99.5%), and carbamide (99%) were provided by Shanghai Maclean Biochemical Technology Co., Ltd.; methacrylic acid (MAA, ≥99%), isopropanol (IPA, ≥99.7%), anhydrous ethanol (H2O≤0.2%), and anhydrous sodium chloride (≥99%) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0054] Example 1:

[0055] MPPD-1:

[0056] (1) Preparation of prepolymer: Take 0.5g MgO and 0.5g AMA and dissolve them in 45g MAA to prepare crosslinking agent. At room temperature, add 45~55g AN, 0.05g LPO, 0.05g OT, 0.05g TBPB, crosslinking agent, 7g isopropanol, 6g formamide and 2g carbamide to a three-necked flask and stir for 1h. Heat the water bath to 40℃ and stir for 96h.

[0057] (2) Preparation of MPPD-1: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2 hours at 60℃, 80℃ and 100℃. Then it was subjected to heat treatment at 160℃ / 2 hours and foaming treatment at 200℃ / 2 hours. After cooling to room temperature, MPPD-1 was obtained.

[0058] Example 2:

[0059] MPPD-2:

[0060] (1) Preparation of prepolymer: Take 0.5g MgO and 0.5g AMA and dissolve them in 45g MAA to prepare crosslinking agent. At room temperature, add 55~65g AN, 0.05g LPO, 0.05g OT, 0.05g TBPB, crosslinking agent, 7g isopropanol, 6g formamide and 2g carbamide to a three-necked flask and stir for 1h. Heat the water bath to 40℃ and stir for 96h.

[0061] (2) Preparation of MPPD-2: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2 hours at 60℃, 80℃ and 100℃. Then it was subjected to heat treatment at 160℃ / 2 hours and foaming treatment at 200℃ / 2 hours. After cooling to room temperature, MPPD-2 was obtained.

[0062] Example 3:

[0063] Preparation of MPPD-3:

[0064] (1) Preparation of prepolymer: Take 0.5g MgO and 0.5g AMA and dissolve them in 45g MAA to prepare crosslinking agent. At room temperature, add 65~75g AN, 0.05g LPO, 0.05g OT, 0.05g TBPB, crosslinking agent, 7g isopropanol, 6g formamide and 2g carbamide to a three-necked flask and stir for 1h. Heat the water bath to 40℃ and stir for 96h.

[0065] (2) Preparation of MPPD-3: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2 hours at 60℃, 80℃ and 100℃. Then it was subjected to heat treatment at 160℃ / 2 hours and foaming treatment at 200℃ / 2 hours. After cooling to room temperature, MPPD-3 was obtained.

[0066] Material density: The density of MPPD-1 is 0.02~0.04 g / cm³. 3 The density of MPPD-2 is 0.06~0.08 g / cm³. 3 The density of MPPD-3 is 0.04~0.06 g / cm³. 3 .

[0067] Electrical insulation performance: To evaluate the electrical insulation performance of MPPD materials, this application tested the breakdown field strength of MPPD and compared it with the insulation strength of pure SF6 gas at 0.4 MPa. Each test was repeated 10 times. The breakdown field strength at a failure probability of 63.2% was selected as the characteristic breakdown field strength, and the two-parameter Weibull distribution parameters were calculated. The experimental results are as follows: Figure 2 As shown, the breakdown field strength of MPPD-1 is 32.7 kV / mm, which is 61.1% higher than that of 0.4MPa SF6; the breakdown field strength of MPPD-2 is 28.3 kV / mm, which is 39.4% higher than that of 0.4MPa SF6; and the breakdown field strength of MPPD-3 is 28.3 kV / mm, which is 29.6% higher than that of 0.4MPa SF6.

[0068] Dielectric properties: The dielectric properties of insulating materials depend on the material itself and its microstructure. MPPDs have many internal air pores; therefore, MPPDs have a relatively low dielectric constant, as shown in experimental results. Figure 3 and Figure 4 As shown, the dielectric constant increases with increasing MPPD density. This is because the dielectric constant of the solid material inside the MPPD is higher than that of the air in the pores. When the MPPD density increases, the proportion of the solid phase increases accordingly, while the proportion of air decreases. The overall dielectric constant of the MPPD approaches that of the solid material, exhibiting a law that the dielectric constant increases with increasing density. Furthermore, tests show that the dielectric loss tangent of the MPPD is less than 0.1. In conclusion, MPPD possesses excellent dielectric properties.

[0069] It should be noted that, as verified, MPPD-1 can achieve similar electrical effects within the following mixing ratio range:

[0070] S1. Preparation of prepolymer: Magnesium oxide (MgO) and allyl methacrylate (AMA) are mixed in a mass ratio of (6~7):5 and dissolved in 400~500 parts by mass of methacrylate (MAA) to obtain a crosslinking agent;

[0071] Separately take 450-550 parts by weight of acrylonitrile AN, 0.5-1 parts by weight of dodecyl peroxide LPO, 0.5-1 parts by weight of tert-butyl peroxide (2-ethylhexanoate) OT, 0.5 parts by weight of tert-butyl peroxide TBPB, 60-80 parts by weight of isoacetone, 50-70 parts by weight of formamide, and 20 parts by weight of carbamide and mix with the crosslinking agent. Stir for the first time for 1-2 hours, heat to 40-50℃ and then stir for the second time for 60-72 hours.

[0072] S2. Preparation of polymethacrylimide porous insulating electrical material MPPD: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2-3 hours at 55-65℃, 75-85℃, and 95-105℃. Then, it was subjected to heat treatment at 150-160℃ / 2 hours and foaming treatment at 190-200℃ / 2 hours. After cooling to room temperature, MPPD was obtained.

[0073] MPPD-2 can achieve similar electrical effects within the following ratio range:

[0074] S1. Preparation of prepolymer: Magnesium oxide (MgO) and allyl methacrylate (AMA) are mixed in a mass ratio of (6~7):5 and dissolved in 400~500 parts by mass of methacrylate (MAA) to obtain a crosslinking agent;

[0075] Separately take 550-650 parts by weight of acrylonitrile AN, 0.5-1 parts by weight of dodecyl peroxide LPO, 0.5-1 parts by weight of tert-butyl peroxide (2-ethylhexanoate) OT, 0.5 parts by weight of tert-butyl peroxide TBPB, 60-80 parts by weight of isoacetone, 50-70 parts by weight of formamide, and 20 parts by weight of carbamide and mix with the crosslinking agent. Stir for the first time for 1-2 hours, heat to 40-50℃ and then stir for the second time for 72-84 hours.

[0076] S2. Preparation of polymethacrylimide porous insulating electrical material MPPD: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2-3 hours at 50-60℃, 70-80℃, and 90-100℃. Then, it was subjected to heat treatment at 150-160℃ / 2 hours and foaming treatment at 190-200℃ / 2 hours. After cooling to room temperature, MPPD was obtained.

[0077] MPPD-3 can achieve similar electrical effects within the following ratio range:

[0078] S1. Preparation of prepolymer: Magnesium oxide (MgO) and allyl methacrylate (AMA) are mixed in a mass ratio of (6~7):5 and dissolved in 400~500 parts by mass of methacrylate (MAA) to obtain a crosslinking agent;

[0079] Separately take 650-750 parts by weight of acrylonitrile AN, 0.5-1 parts by weight of dodecyl peroxide LPO, 0.5-1 parts by weight of tert-butyl peroxide (2-ethylhexanoate) OT, 0.5 parts by weight of tert-butyl peroxide TBPB, 60-80 parts by weight of isoacetone, 50-70 parts by weight of formamide, and 20 parts by weight of carbamide and mix with the crosslinking agent. Stir for the first time for 1-2 hours, heat to 40-50℃ and then stir for the second time for 84-96 hours.

[0080] S2. Preparation of polymethacrylimide porous insulating electrical material MPPD: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2-3 hours at 45-55℃, 65-75℃, and 85-95℃. Then, it was subjected to heat treatment at 150-160℃ / 2 hours and foaming treatment at 190-200℃ / 2 hours. After cooling to room temperature, MPPD was obtained.

[0081] in conclusion

[0082] This invention provides a 72.5kV pluggable lightweight and environmentally friendly GIL busbar unit, which replaces the traditional insulator-SF6 system with MPPD porous material. Combined with pluggable connection and detachable shielding positioning structure, it achieves lightweight, high insulation, easy maintenance, and zero SF6 emissions. The field strength and temperature rise both meet national standards, and it has broad prospects for engineering applications.

[0083] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A 72.5kV detachable lightweight and environmentally friendly GIL busbar unit, characterized in that, It includes a center conductor, male and female plug contacts, a shield, a metal shell, a modified porous methacrylimide copolymer dielectric (MPPD), a conductive spring, and a positioning copper rod. The MPPD is fully filled between the center conductor and the metal shell, replacing the traditional insulator and SF6 insulating gas. The male and female plug contacts are connected by spring fingers to achieve flexible electrical connection. The shield covers the outside of the plug position. The shield and the male plug are detachably axially positioned by the conductive spring and the positioning copper rod. The shell and the center conductor are coaxially arranged. The outer diameter of the center conductor is 8~12mm, the inner diameter of the shell is 25~35mm, and the shell thickness is 4~8mm.

2. The GIL bus unit according to claim 1, characterized in that, The MPPD has a density of <0.1 g / cm³, a power frequency breakdown field strength of 33.1 kV / mm, a broadband dielectric constant of <2.5, a dielectric loss tanδ≤0.1, and a thermal decomposition temperature of 320℃.

3. The GIL bus unit according to claim 1, characterized in that, The male and female plug contacts adopt a male and female plug-in form, and multiple sets of circumferentially distributed spring contact fingers are set between the male and female plugs.

4. The GIL bus unit according to claim 1, characterized in that, The arc-shaped shield is a cylindrical structure with rounded transitions at both ends on the outer side and a uniform gap between the inner side and the outer wall of the contact, thus preventing the generation of a floating potential.

5. The GIL bus unit according to claim 1, characterized in that, During assembly, the conductive spring pushes the copper rod into the groove of the shielding cover to achieve axial positioning; during disassembly, the pin presses the copper rod through the through hole of the shielding cover to separate the male and female plugs.

6. The GIL bus unit according to claim 1, characterized in that, When the rated current is 315A, the highest temperature of the center conductor is about 53℃, with a temperature rise of 33℃; the outer casing temperature is close to the ambient temperature, which meets the requirements of GB / T11022 standard.

7. The GIL bus unit according to claim 1, characterized in that, The male plug, female plug, shield, and outer shell are made of aluminum, the spring contacts are made of beryllium bronze, and the center conductor is made of oxygen-free copper.

8. The GIL bus unit according to claim 1, characterized in that, MPPD is obtained through the following steps: S1. Preparation of prepolymer: Magnesium oxide (MgO) and allyl methacrylate (AMA) are mixed in a mass ratio of (6~7):5 and dissolved in 400~500 parts by mass of methacrylate (MAA) to obtain a crosslinking agent; Separately take 450-750 parts by weight of acrylonitrile AN, 0.5-1 parts by weight of dodecyl peroxide LPO, 0.5-1 parts by weight of tert-butyl peroxide (2-ethylhexanoate) OT, 0.5 parts by weight of tert-butyl peroxide TBPB, 60-80 parts by weight of isoacetone, 50-70 parts by weight of formamide, and 20 parts by weight of carbamide and mix with the crosslinking agent and stir for the first time. After heating, stir for the second time. S2. Preparation of polymethacrylimide porous insulating electrical material MPPD: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2-3 hours at 45-65℃, 65-85℃, and 85-105℃. Then, it was subjected to heat treatment at 150-160℃ / 2 hours and foaming treatment at 190-200℃ / 2 hours. After cooling to room temperature, MPPD was obtained.

9. The GIL bus unit according to claim 8, characterized in that, MPPD is obtained through the following steps: S1. Preparation of prepolymer: Magnesium oxide (MgO) and allyl methacrylate (AMA) are mixed in a mass ratio of (6~7):5 and dissolved in 400~500 parts by mass of methacrylate (MAA) to obtain a crosslinking agent; Separately take 550-650 parts by weight of acrylonitrile AN, 0.5-1 parts by weight of dodecyl peroxide LPO, 0.5-1 parts by weight of tert-butyl peroxide (2-ethylhexanoate) OT, 0.5 parts by weight of tert-butyl peroxide TBPB, 60-80 parts by weight of isoacetone, 50-70 parts by weight of formamide, and 20 parts by weight of carbamide and mix with the crosslinking agent. Stir for the first time for 1-2 hours, heat to 40-50℃ and then stir for the second time for 72-84 hours. S2. Preparation of polymethacrylimide porous insulating electrical material MPPD: The prepolymer was placed in an electric thermostatic drying oven and left to stand for 2-3 hours at 50-60℃, 70-80℃, and 90-100℃. Then, it was subjected to heat treatment at 150-160℃ / 2 hours and foaming treatment at 190-200℃ / 2 hours. After cooling to room temperature, MPPD was obtained.

10. The GIL bus unit according to claim 8, characterized in that, Add AN, LPO, OT, TBPB, crosslinking agent, isopropanol, formamide, and carbamide in sequence and mix.

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