Oil-immersed capacitor external insulation structure, processing method and corresponding capacitor

Abstract

The invention discloses an oil-immersed capacitor external insulation structure which comprises a plurality of composite insulation layers, each composite insulation layer is composed of a layer of cable paper and a layer of non-polar polyolefin material, and the non-polar polyolefin material has low dielectric constant and high breakdown field strength. The capacitor is compounded with cable paper to improve partial discharge extinguishing voltage of the capacitor pole to the shell; wherein an impregnant is impregnated between the adjacent cable paper and non-polar polyolefin material layer, and the impregnant is insulating oil. The invention also discloses a corresponding processing method and a corresponding capacitor. According to the invention, the non-polar polyolefin material with low dielectric constant and high breakdown field strength is introduced for composite insulation with the cable paper, so that the partial discharge extinguishing voltage of the capacitor pole to the shell is obviously improved, the installation structure of the capacitor is simplified, the reliability is improved, the occupied area of the device is reduced, and the device has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of power capacitors, and in particular to an external insulation structure of an oil-immersed capacitor, a processing method and a corresponding capacitor. Background Art

[0002] The maximum relative ground voltage of systems of 110kV and below can reach the line voltage level. If the power capacitor needs to be installed directly on the ground, its pole-to-shell partial discharge extinction voltage must exceed the maximum value of the system line voltage to ensure safe operation.

[0003] At present, capacitor pole-to-shell insulation generally uses multiple layers of oil-impregnated cable paper, such as Figure 1 As shown, a schematic diagram of the structure of an existing oil-immersed capacitor external insulation structure is shown, which is formed by winding a capacitor core with multiple layers of oil-immersed cable paper 1', and insulating oil 2' is impregnated on the cable paper 1'. The pole-to-shell extinction voltage of this structure is generally around 12kV to 15kV, which can meet the use of 10kV systems, but cannot meet the use requirements of 20kV and above systems.

[0004] The current solution is to place the capacitor on an insulating platform to reduce the insulation level requirements of the capacitor pole to the shell, but this increases the complexity and footprint of the device. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an external insulation structure, a processing method and a corresponding capacitor of an oil-immersed capacitor, by introducing a non-polar polyolefin material (such as a polypropylene film) with a low dielectric constant and a high breakdown field strength and a composite insulation of cable paper to significantly improve the partial discharge extinction voltage of the capacitor pole to the shell, so that the capacitor can be directly and safely installed in a system above 10kV.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: As a first aspect of the present invention, an external insulation structure of an oil-immersed capacitor is provided, which comprises:

[0007] A multi-layer composite insulation layer, each composite insulation layer is composed of a layer of cable paper and a layer of non-polar polyolefin material, wherein the non-polar polyolefin material has a low dielectric constant and a high breakdown field strength and is composited with the cable paper to increase the partial discharge extinction voltage of the capacitor pole to shell;

[0008] Wherein, an impregnating agent is impregnated between the adjacent cable paper and non-polar polyolefin material layers, and the impregnating agent is insulating oil.

[0009] Optionally, the non-polar polyolefin material is a polypropylene film with a thickness between 10 and 20 microns.

[0010] Optionally, the cable paper has a thickness of 0.08 mm and is alternately laminated with a non-polar polyolefin material to form a composite insulation layer.

[0011] Optionally, the outer surface of the composite insulating layer is provided with holes, and the diameter of the holes is between 1 and 3 mm to increase the permeability of the impregnating agent.

[0012] Optionally, the composite insulating layer is wrapped around the outer ring of the capacitor core for at least 32 turns to increase the pole-to-shell extinction voltage by at least 30%.

[0013] Accordingly, as another aspect of the present invention, a method for processing an outer insulation structure of an oil-immersed capacitor is provided, which is used to manufacture the outer insulation structure of the oil-immersed capacitor as described above, and the method comprises the following steps:

[0014] Prepare cable paper and non-polar polyolefin materials;

[0015] Punching holes in the non-polar polyolefin material through a punching roller;

[0016] The punched non-polar polyolefin material and the cable paper are alternately wound on the capacitor core;

[0017] Rotate the capacitor core to make the material wrap evenly;

[0018] The fixing and packaging treatment is carried out to form a multi-layer composite insulation structure, and then an impregnation treatment is carried out.

[0019] Optionally, the punching roller is composed of two rollers, on which circular needles are installed, and the diameter of the circular needles is between 1 and 3 mm, which are used to punch holes on the surface of the non-polar polyolefin material.

[0020] Optionally, the non-polar polyolefin material is a polypropylene film with a thickness between 10 and 20 microns and a width 40 mm higher than the height of the capacitor core. When winding, the capacitor core is located in the middle of the polypropylene film.

[0021] Optionally, the cable paper has a thickness of 0.08 mm and is alternately stacked and wound on a capacitor core with a non-polar polyolefin material to form a multi-layer composite insulation layer.

[0022] Optionally, the method further includes a step of compacting the composite insulating layer after winding is completed, so as to ensure that each layer of material fits tightly together and improve the insulation performance.

[0023] Optionally, the processing method further comprises performing an impregnation treatment on the formed multi-layer composite insulation structure, so that the impregnating agent fully penetrates into the composite insulation layer to further improve the insulation performance.

[0024] As another aspect of the present invention, there is also provided an oil-immersed capacitor, comprising:

[0025] Capacitor core;

[0026] The capacitor core is wrapped with the aforementioned oil-immersed capacitor outer insulation structure.

[0027] The implementation of the embodiments of the present invention has the following beneficial effects:

[0028] The present invention provides an external insulation structure of an oil-immersed capacitor, a processing method and a corresponding capacitor. By introducing a non-polar polyolefin material (such as a polypropylene film) with a low dielectric constant and a high breakdown field strength and a cable paper composite insulation in the external insulation structure of the oil-immersed capacitor, the partial discharge extinction voltage of the capacitor pole to the shell can be significantly improved, so that the capacitor can be directly and safely installed in a system above 10kV, for example, it can meet the use requirements of a system of 20kV and above.

[0029] The present invention simplifies the capacitor installation structure, does not require an additional insulating platform, reduces device complexity, improves reliability and reduces device footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0031] Figure 1 It is a structural schematic diagram of an existing external insulation structure of an oil-immersed capacitor;

[0032] Figure 2 It is a structural schematic diagram of an embodiment of an external insulation structure of an oil-immersed capacitor provided by the present invention;

[0033] Figure 3 A structural schematic diagram of an embodiment of a method for processing an external insulation structure of an oil-immersed capacitor provided by the present invention;

[0034] Figure 4 for Figure 3 Schematic diagram of the structure of the processing equipment used. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] like Figure 2FIG. 1 is a schematic diagram showing a structure of an embodiment of an external insulation structure of an oil-immersed capacitor provided by the present invention; in this embodiment, an external insulation structure of an oil-immersed capacitor is provided, which includes:

[0037] A multi-layer composite insulation layer, each composite insulation layer is composed of a layer of cable paper 1 and a layer of non-polar polyolefin material (i.e., polymer 2 in the figure), the non-polar polyolefin material 2 has a low dielectric constant and a high breakdown field strength, and is composited with the cable paper 1 to increase the partial discharge extinction voltage of the capacitor pole to shell, and the non-polar polyolefin material can be, for example, a polypropylene film;

[0038] Wherein, an impregnating agent 3 is impregnated between the adjacent cable paper 1 and the non-polar polyolefin material layer 2, and the impregnating agent 3 is insulating oil.

[0039] In a specific example, the non-polar polyolefin material 2 is a polypropylene film, and its thickness is between 10 and 20 microns.

[0040] In a specific example, the cable paper 1 has a thickness of 0.08 mm and is alternately laminated with the non-polar polyolefin material 1 to form a composite insulation layer.

[0041] Optionally, the outer surface of the composite insulating layer is provided with holes, and the diameter of the holes is between 1 and 3 mm to increase the permeability of the impregnating agent.

[0042] Optionally, the composite insulating layer is wrapped around the outer ring of the capacitor core for at least 32 turns to increase the pole-to-shell extinction voltage by at least 30%.

[0043] It is understandable that the existing capacitor external insulation structure such as Figure 1 The figure shows a multilayer structure of cable paper and insulating oil. Its electric field distribution is inversely proportional to the dielectric constant of the material. That is,

[0044]

[0045] Where: E P is the electric field strength on the cable paper; E o is the electric field strength on the insulating oil; ε O is the dielectric constant of the insulating oil (approximately equal to 2.6), which indicates the polarization degree of the insulating oil in the electric field; ε P is the dielectric constant of the cable paper (approximately equal to 6.8), which indicates the polarization degree of the cable paper in the electric field. U is the voltage across the capacitor; do is the thickness of the insulating oil; d P : The thickness of cable paper.

[0046] Among them, the field strength on the insulating oil is 2 to 3 times that of the cable paper. Under normal circumstances, partial discharge occurs in the insulating oil. The electric field strength in the insulating oil of this structure is significantly higher than that in the cable paper, so the partial discharge performance of this structure is poor.

[0047] In the embodiment of the present invention, a non-polar polymer solid medium is added to the dielectric structure. The non-polar polymer has a low dielectric constant and high withstand voltage strength, which can effectively improve the field strength distribution of the insulating layer and significantly reduce the electric field strength in the insulating oil without significantly increasing the thickness of the insulating material.

[0048]

[0049] Among them, ε f is the dielectric constant of the non-polar polymer film, which is lower than the dielectric constant ε of the insulating oil o In this formula, d P Cable paper (or polymer film added later, but in this formula, d P After adding the non-polar polymer, the total thickness of the insulating layer and the dielectric constant distribution have changed, so the distribution of the electric field strength has also changed. By choosing a non-polar polymer with a lower dielectric constant (i.e., ε f <ε o ), can significantly reduce the value of the electric field strength Eo' in the insulating oil, and The bigger the effect, the more obvious it is.

[0050] like Figure 3 As shown, a schematic diagram of the main process of a method for processing an external insulation structure of an oil-immersed capacitor provided by the present invention is shown, and combined with Figure 4 As shown, in this embodiment, the method is used to manufacture the external insulation structure of the oil-immersed capacitor as described above, which adopts Figure 4 Specifically, the method comprises the following steps:

[0051] Step S1, preparing cable paper and non-polar polyolefin material, ensuring that the width of the material is slightly larger than the height of the capacitor core so as to completely wrap it;

[0052] Step S2, punching holes in the non-polar polyolefin material through a punching roller; specifically, using Figure 4 A packaging tool comprising a core fixing device and an outer insulation fixing device, and a punching roller with round needles; punching holes through the punching roller to increase the permeability of an impregnating agent (such as insulating oil);

[0053] Step S3, alternately winding the punched non-polar polyolefin material and the cable paper on the capacitor core;

[0054] Step S4, rotating the capacitor core to make the material evenly wrapped;

[0055] Step S5, performing fixing and packaging treatment to form a multi-layer composite insulation structure, and performing impregnation treatment.

[0056] like Figure 4 As shown, optionally, the perforating roller is composed of two rollers, on which circular needles are installed, and the diameter of the circular needles is between 1 and 3 mm, which are used to perforate the surface of the non-polar polyolefin material to facilitate the entry of the impregnating agent.

[0057] In a specific example, the non-polar polyolefin material is a polypropylene film with a thickness between 10 and 20 microns and a width 40 mm higher than the height of the capacitor core. When winding, the capacitor core is located in the middle of the polypropylene film.

[0058] In a specific example, the thickness of the cable paper is 0.08 mm, the non-polar polyolefin material is a 10-20 micron polypropylene film, the width of the non-polar polyolefin material is 40 mm higher than the core height, and the core is in the middle of the polymer when winding. The cable paper and the non-polar polyolefin material are alternately stacked and wound on the capacitor core to form a multi-layer composite insulation layer. The number of turns of the outer insulation is the same as that of a normal capacitor.

[0059] In a specific example, the method further includes the step of compacting the composite insulating layer after winding is completed, so as to ensure that each layer of material fits tightly together and improve the insulation performance.

[0060] In a specific example, the processing method further includes performing an impregnation treatment on the formed multi-layer composite insulation structure, so that the impregnating agent fully penetrates into the composite insulation layer to further improve the insulation performance.

[0061] Specifically, after the cable paper and the non-polar polyolefin material are alternately wound on the capacitor core to form a multi-layer composite insulation layer, the insulating oil can be injected between these adjacent insulating material layers. This process may be achieved by dipping, that is, immersing the entire multi-layer composite insulation structure in the insulating oil, or by other methods (such as injection, dripping, etc.) to evenly distribute the insulating oil between the layers.

[0062] Alternatively, after the multi-layer composite insulation layer is formed and subjected to necessary treatment (such as compaction, shaping, etc.), but before the final fixing and packaging treatment, the insulating oil can be added between the layers. This ensures that the insulating oil can fully penetrate and fill the gaps between the layers, thereby improving the insulation performance and stability of the capacitor.

[0063] In a specific example, if the cable paper is 0.08 mm thick and is wrapped 32 times, the pole-to-shell extinction voltage can be increased by 30%. Table 1 below shows a comparison of the normal temperature pole-to-shell extinction voltages of the existing structure and the improved structure of the present invention.

[0064] Table 1

[0065]

[0066] For more details, please refer to and combine the above Figure 2 The description is not repeated here.

[0067] As another aspect of the present invention, there is also provided an oil-immersed capacitor, comprising:

[0068] Capacitor core;

[0069] The capacitor core is wrapped with the aforementioned Figure 1 The outer insulation structure of the oil-immersed capacitor described is as follows Figure 2 , Figure 3 For more details, please refer to the above Figures 1 to 3 The description is not repeated here.

[0070] The implementation of the embodiments of the present invention has the following beneficial effects:

[0071] The present invention provides an external insulation structure of an oil-immersed capacitor, a processing method and a corresponding capacitor. By introducing a non-polar polyolefin material (such as a polypropylene film) with a low dielectric constant and a high breakdown field strength and a cable paper composite insulation in the external insulation structure of the oil-immersed capacitor, the partial discharge extinction voltage of the capacitor pole to the shell can be significantly improved, so that the capacitor can be directly and safely installed in a system above 10kV, for example, it can meet the use requirements of a system of 20kV and above.

[0072] The present invention simplifies the capacitor installation structure, does not require an additional insulating platform, reduces device complexity, improves reliability and reduces device footprint.

[0073] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An external insulation structure of an oil-immersed capacitor, characterized in that: It includes: A multi-layer composite insulation layer, each composite insulation layer is composed of a layer of cable paper and a layer of non-polar polyolefin material, wherein the non-polar polyolefin material has a low dielectric constant and a high breakdown field strength and is composited with the cable paper to increase the partial discharge extinction voltage of the capacitor pole to shell; Wherein, an impregnating agent is impregnated between the adjacent cable paper and non-polar polyolefin material layers, and the impregnating agent is insulating oil.

2. The outer insulation structure of the oil-immersed capacitor according to claim 1, characterized in that: The non-polar polyolefin material is a polypropylene film, and the thickness thereof is between 10 and 20 microns.

3. The outer insulation structure of the oil-immersed capacitor according to claim 2, characterized in that: The thickness of the cable paper is 0.08 mm, and the cable paper is alternately stacked with non-polar polyolefin material to form a composite insulating layer; the outer surface of the composite insulating layer is provided with holes, and the diameter of the holes is between 1 and 3 mm to increase the permeability of the impregnating agent.

4. The external insulation structure of the oil-immersed capacitor according to claim 3, characterized in that: The composite insulating layer is wrapped around the outer ring of the capacitor core for at least 32 turns to increase the pole-to-shell extinction voltage by at least 30%.

5. A method for processing an external insulation structure of an oil-immersed capacitor, used to manufacture the external insulation structure of an oil-immersed capacitor as claimed in any one of claims 1 to 4, characterized in that: The method comprises the following steps: Prepare cable paper and non-polar polyolefin materials; Punching holes in the non-polar polyolefin material through a punching roller; The punched non-polar polyolefin material and the cable paper are alternately wound on the capacitor core; Rotate the capacitor core to make the material wrap evenly; The fixing and packaging treatment is carried out to form a multi-layer composite insulation structure, and then an impregnation treatment is carried out.

6. The method according to claim 5, characterized in that The punching roller is composed of two rollers, on which round needles are installed. The diameter of the round needles is between 1 and 3 mm and is used for punching holes on the surface of non-polar polyolefin materials.

7. The method according to claim 6, characterized in that in: The non-polar polyolefin material is a polypropylene film with a thickness between 10 and 20 microns and a width 40 millimeters higher than the height of the capacitor core. When winding, the capacitor core is located in the middle of the polypropylene film. The cable paper has a thickness of 0.08 mm and is alternately stacked and wound with non-polar polyolefin material on a capacitor core to form a multi-layer composite insulation layer.

8. The method according to claim 7, characterized in that The method also includes the step of compacting the composite insulation layer after winding is completed, so as to ensure that each layer of material fits closely together and improve insulation performance.

9. The method according to any one of claims 5 to 8, characterized in that: The processing method also includes performing an impregnation treatment on the formed multi-layer composite insulation structure, so that the impregnating agent fully penetrates into the composite insulation layer to further improve the insulation performance.

10. An oil-immersed capacitor, characterized in that: include: Capacitor core; The capacitor core is wrapped with the outer insulation structure of the oil-immersed capacitor according to any one of claims 1 to 4.

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