A variable resistivity ultra-high voltage valve side outlet device and its design method

Abstract

The present invention belongs to the field of transformer valve-side outlets, and specifically discloses a variable resistivity ultra-high voltage valve-side outlet device, characterized in that it includes: a rising seat, a voltage-equalizing ball fixed inside the rising seat, a valve-side sleeve with its tail end inserted into the voltage-equalizing ball, and a shielding tube with its head inserted into the voltage-equalizing ball; the outside of the voltage-equalizing ball is provided with an insulating layer, an inner insulating part, and an outer insulating part in sequence, an insulating oil channel is provided between the insulating layer and the inner insulating part, and an insulating oil channel is provided between the inner insulating part and the outer insulating part. A variable resistivity ultra-high voltage valve-side outlet device in the present invention adopts a combination of a voltage-equalizing ball, an insulating layer, an inner insulating part, and an outer insulating part to effectively reduce the DC and AC electric field strengths on the surface of the voltage-equalizing ball, reduce the DC creepage field strength on the surface of the insulating layer, the surface of the inner insulating part, and the surface of the outer insulating part, and ensure the electrical strength and insulation reliability of the voltage-equalizing ball.

Description

Technical Field

[0001] The present invention belongs to the technical field of transformer outlets, and in particular relates to a variable resistivity ultra-high voltage valve-side outlet device and a design method thereof. Background Art

[0002] The outgoing conductors of converter transformers are divided into valve-side and grid-side types. The valve-side outgoing conductor is an insulating device that connects the valve-side bushing of the converter transformer to the transformer winding. The valve-side outgoing conductor differs from the AC outgoing conductor because it must withstand not only AC voltage but also DC voltage. The interaction mechanisms of DC and AC voltages in oil-paper insulation differ. Therefore, the structural design of the valve-side outgoing conductor requires consideration of the electric field distribution under DC voltage compared to the AC outgoing conductor. This outgoing conductor consists of a voltage-equalizing ball, a shielding tube, an insulating molded part, and an insulating paper tube. It improves the surrounding electric field distribution and provides sufficient safety margin between the bushing and the raised seat wall, ensuring safe operation of the transformer.

[0003] The valve-side lead-out device of a converter transformer is typically installed within the valve-side raised seat. Because the valve-side leads must withstand DC withstand voltage, a large number of insulating components are required. Currently, two valve-side lead-out device configurations exist. One utilizes a grading ball wrapped in sufficiently thick insulation paper. Between the grading ball and the raised seat wall, a multi-layered insulation shielding tube made of insulating paperboard of equal resistivity, separated by oil gaps, is used to withstand both AC and DC withstand voltages. In this lead-out device, the DC creepage field strength at the interface between the grading ball's paper insulation and the transformer oil is very high, resulting in a very low insulation margin. The AC field strength at the oil gap between the grading ball and the insulation tube is high, resulting in a low insulation safety margin. Furthermore, the DC creepage field strength on the surface of the shielding tube supporting the grading ball is also very high, resulting in a very low insulation safety margin. Electric field calculations using two-dimensional finite element methods and safety margins calculated using creepage and power line insulation margin verification methods for all three locations yielded values ​​less than 1.0. This configuration has encountered numerous problems in previous engineering applications, with discharge failures occurring at all three locations during factory testing.

[0004] Another type of lead-out device consists of a pressure-equalizing ball covered with paper pulp, directly above the paper pulp with insulating paperboard of the same resistivity, separated by oil gaps. This second type of lead-out device is too complex and requires high operator skill to install. Improper installation can also lead to discharge accidents.

[0005] Therefore, the current outgoing line device has problems such as complex structure, insufficient insulation margin and proneness to safety accidents, and there is currently no suitable solution. Summary of the Invention

[0006] The present invention provides a variable resistivity ultra-high voltage valve side outlet device, which is used to solve the problems of complex structure, insufficient insulation margin and easy occurrence of safety accidents in current outlet devices.

[0007] In order to solve the above technical problems, the technical solution of the present invention is: the variable resistivity ultra-high voltage valve side line outlet device, which includes: a lifting seat, a pressure equalizing ball fixed inside the lifting seat, a valve side sleeve with the tail end inserted into the pressure equalizing ball, and a shielding tube with the head inserted into the pressure equalizing ball; the outside of the pressure equalizing ball is provided with an insulating layer, an inner insulating part and an outer insulating part in sequence, and an insulating oil channel is between the insulating layer and the inner insulating part, and an insulating oil channel is between the inner insulating part and the outer insulating part.

[0008] In a preferred embodiment of the present invention, the insulating layer is provided on the outer surface of the pressure-equalizing ball, the top and the bottom of the pressure-equalizing ball are both sharp ends, and the insulating layer covers the sharp ends.

[0009] In a preferred embodiment of the present invention, the inner insulating member includes, from top to bottom, an inner equipotential segment, an inner contoured segment, a bent segment, and an inner vertical segment connected end to end. The setting angle of the inner equipotential segment is the same as the angle of the electric field, the inner contoured segment has the same shape as the equalizing ball, and the bent segment is bent inward 25-40 degrees.

[0010] In a preferred embodiment of the present invention, the external insulating member includes, from top to bottom, an external equipotential segment, an external contoured segment, and an external vertical segment. The setting angle of the external equipotential segment is the same as the angle of the electric field, the external contoured segment has the same shape as a voltage-equalizing ball, and the upper end of the external vertical segment is at the same height as the center of the voltage-equalizing ball.

[0011] In a preferred embodiment of the present invention, the inner insulating member and the outer insulating member have the same structure, including insulating bars and an insulating layer covering the insulating bars, and the insulating bars are made of laminated paperboard.

[0012] In a preferred embodiment of the present invention, a shielding ring is provided between the shielding tube and the voltage-equalizing ball, and the surface of the shielding ring is provided with insulating paint; the shielding ring, the shielding tube and the voltage-equalizing ball are electrically connected to form an equipotential body through metal parts.

[0013] In a preferred embodiment of the present invention, the shielding tube is an aluminum round tube, the top of the shielding tube is trumpet-shaped, the end of the shielding tube is a smooth structure, and the outside of the shielding tube is provided with heat-modified insulating paper.

[0014] In a preferred embodiment of the present invention, a plurality of insulating component groups are provided outside the shielding tube, and the insulating component groups are evenly distributed along the outer circumference of the shielding tube. The insulating component groups include inner support bars and outer support bars, and the inner support bars and the outer support bars are both made of cardboard, and there is an oil gap between the inner support bars and the outer support bars.

[0015] In a preferred embodiment of the present invention, a plurality of insulating paper tubes are provided between the pressure-equalizing ball and the inner wall of the raising seat, and the insulating paper tubes are corrugated paper tubes made of T3 cardboard or T4 cardboard.

[0016] The present invention also discloses a method for calculating the placement position of an insulating member of a variable resistivity ultra-high voltage valve-side outlet device, which comprises the following steps:

[0017] S1: Modeling, inputting electrode voltages, and setting boundary conditions;

[0018] S2: Use electric field calculation software to calculate AC and DC electric fields;

[0019] S3: Draw the AC electric field power lines and perform oil gap field strength safety margin on the points on the power lines;

[0020] S4: Perform creepage check on the oil-paper insulation interface;

[0021] S5: Use DC electric field to check the maximum DC field strength of each insulating component and the DC creepage field strength at the interface between the insulating component and the oil;

[0022] S6: Determine the placement position of the insulating member based on the verification results in steps S3, S4 and S5.

[0023] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0024] The variable resistivity UHV valve-side outlet device of the present invention utilizes a combination of a voltage-equalizing ball, an insulating layer, an inner insulator, and an outer insulator to effectively reduce the DC and AC electric field strengths on the surface of the voltage-equalizing ball, as well as the DC creepage field strength on the surfaces of the insulating layer, the inner insulator, and the outer insulator, thereby ensuring the electrical strength and insulation reliability of the voltage-equalizing ball. The two-layer molded part surrounding the voltage-equalizing ball adopts an antelope-shaped structure. The inner and outer equipotential segments extending from the upper ends can attract equipotential lines, reducing the DC electric field strength in the voltage-equalizing ball pulp and the creepage field strength on the surface of the voltage-equalizing ball pulp. The oil gap between the inner and outer insulators and the voltage-equalizing ball is divided. The inner and outer insulators divide the large oil gap between the voltage-equalizing ball and the insulating tube into three smaller oil gaps, increasing the safety margin of the AC electric field in the oil gap on the surface of the voltage-equalizing ball. At the same time, under the action of DC voltage, the equipotential lines in the insulation layer of the voltage-equalizing ball enter the oil and then diverge into the insulation of the shielding tube, thus reducing the creepage field strength on the surface of the shielding tube. In the outer multi-layer insulation tube, according to the calculation results, insulating paper boards with different resistivities are used according to the electric field distribution of the branches at different locations. This makes the electric field distribution more uniform and increases the safety margin of the electric field. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, they can also obtain drawings of other embodiments based on these drawings.

[0026] Figure 1 Schematic diagram of a variable resistivity ultra-high voltage valve side outlet device according to one embodiment of the present invention;

[0027] Figure 2 yes Figure 1 A magnified schematic diagram of part A;

[0028] Figure 3 This is a schematic diagram of an inner insulating component of a variable resistivity ultra-high voltage valve-side outlet device according to one embodiment of the present invention;

[0029] Figure 4 It is a schematic diagram of an outer insulating component of a variable resistivity ultra-high voltage valve side outlet device described in one embodiment of the present invention.

[0030] As shown in the figure:

[0031] 101-rising seat; 102-valve side sleeve; 103-shielding tube; 201-equalizing ball; 202-insulating layer; 203-inner insulating member; 2031-inner equipotential section; 2032-inner contoured section; 2033-bending section; 2034-inner vertical section; 204-outer insulating member; 2041-outer equipotential section; 2042-outer contoured section; 2043-outer vertical section; 301-shielding ring; 401-inner support bar; 402-outer support bar; 501-insulating tube. DETAILED DESCRIPTION

[0032] For ease of understanding, the variable resistivity ultra-high voltage valve-side outlet device is described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations and positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0035] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0036] like Figure 1 As shown, a variable resistivity ultra-high voltage valve-side outlet device of the present invention includes: an elevation seat 101, a valve-side bushing 102, a shielding cylinder 103 and an insulating cylinder 501.

[0037] Reference Figure 2As shown, a pressure equalizing ball 201 is provided in the lifting seat 101 , the tail end of the valve side sleeve 102 is inserted into the pressure equalizing ball 201 , and the head of the shielding tube 103 is inserted into the pressure equalizing ball 201 .

[0038] The outside of the pressure equalizing ball 201 is provided with an insulating layer 202, an inner insulating member 203 and an outer insulating member 204 in sequence. An insulating oil channel is provided between the insulating layer 202 and the inner insulating member 203, and an insulating oil channel is provided between the inner insulating member 203 and the outer insulating member 204.

[0039] The voltage-equalizing ball 201 is made of aluminum, and its surface is formed by combining an insulating layer 202, an inner insulating part 203, and an outer insulating part 204, which effectively reduces the DC and AC electric field strengths on the surface of the voltage-equalizing ball 201, and reduces the DC creepage field strength on the surface of the insulating layer 202, the surface of the inner insulating part 203, and the surface of the outer insulating part 204, thereby ensuring the electrical strength and insulation reliability of the voltage-equalizing ball 201.

[0040] The insulating layer 202 is provided on the outer surface of the voltage balancing ball 201. The top and bottom of the voltage balancing ball 201 are both sharp ends, and the insulating layer 202 covers the sharp ends to prevent electric field spikes from being generated at these locations, thereby greatly reducing the safety risks of the device.

[0041] like Figure 3 As shown, the inner insulating part 203 includes, from top to bottom, an inner equipotential section 2031, an inner contoured section 2032, a bent section 2033 and an inner vertical section 2034 connected end to end. The setting angle of the inner equipotential section 2031 is the same as the angle of the electric field, the inner contoured section 2032 has the same shape as the equalizing ball 201, and the bent section 2033 is bent inward by 25-40 degrees.

[0042] like Figure 4 As shown, the outer insulating member 204 includes, from top to bottom, an outer equipotential segment 2041, an outer contoured segment 2042, and an outer vertical segment 2043. The setting angle of the outer equipotential segment 2041 is the same as the angle of the electric field, the outer contoured segment 2042 has the same shape as the equalizing ball 201, and the upper end of the outer vertical segment 2043 is at the same height as the center of the equalizing ball 201.

[0043] The two-layer molded part surrounding the voltage-equalizing ball 201 adopts an antelope-shaped structure. The inner equipotential section 2031 and outer equipotential section 2041 extending from the upper end can attract equipotential lines, reducing the DC electric field strength in the pulp of the voltage-equalizing ball 201 and the creepage electric field strength on the pulp surface of the voltage-equalizing ball 201. The oil gap between the inner and outer insulating parts 203, 204, and the voltage-equalizing ball 201 is divided. The inner and outer insulating parts 203, 204 divide the large oil gap between the voltage-equalizing ball 201 and the insulating tube 501 into three smaller oil gaps, increasing the safety margin of the AC electric field in the oil gap on the surface of the voltage-equalizing ball 201. At the same time, under the action of DC voltage, the equipotential lines in the insulating layer 202 of the voltage-equalizing ball 201 enter the oil and then diverge into the insulation of the shielding tube 103, further reducing the creepage electric field strength on the surface of the shielding tube 103.

[0044] Reference Figure 2 As shown, a shielding ring 301 is installed between the shielding tube 103 and the voltage-equalizing ball 201. The surface of the shielding ring 301 is coated with insulating varnish. The shielding ring 301, the shielding tube 103, and the voltage-equalizing ball 201 are electrically connected to form an equipotential body via metal fittings. The placement of the shielding ring 301 between the voltage-equalizing ball 201 and the shielding tube 103 effectively reduces the DC creepage field strength at the thin insulation area at the end of the shielding tube 103.

[0045] The inner insulating member 203 and the outer insulating member 204 have the same structure, including insulating bars and an insulating layer 202 covering the insulating bars. The insulating bars are made of laminated paperboard.

[0046] Continue to refer to Figure 2 As shown, the shielding tube 103 is an aluminum round tube. The top of the shielding tube 103 is trumpet-shaped, the end of the shielding tube 103 is a smooth structure, and the outside of the shielding tube 103 is provided with heat-modified insulating paper. The shielding tube 103 is provided with a plurality of insulating component groups on the outside. The insulating component groups are evenly distributed along the outer circumference of the shielding tube 103. The insulating component groups include inner support bars 401 and outer support bars 402. The inner support bars 401 and the outer support bars 402 are both made of cardboard. There is an oil gap between the inner support bars 401 and the outer support bars 402. These two layers of insulating components effectively reduce the DC creepage field strength on the surface of the shielding tube 103, ensuring the insulation reliability of the shielding tube 103.

[0047] A plurality of insulating paper tubes are provided between the pressure-equalizing ball 201 and the inner wall of the raising seat 101 . The insulating paper tubes are corrugated paper tubes made of T3 paperboard or T4 paperboard.

[0048] The length of the insulating tube 501 is determined according to the size of the tail end of the selected sleeve 102, that is, this outlet device can match all sleeves 102, such as the insulating sleeve 102 and the dry sleeve 102. A fixed disk and a bracket are provided in the raising seat 101, and the insulating tube 501 and the corrugated cardboard tube are fixed in the raising seat 101 through the fixed disk and the bracket. The metal tubes for fixing the cardboard and the corrugated cardboard on the fixed disk are evenly distributed along the circumference, and the number and diameter of the metal tubes are determined according to the weight of the insulating tube 501 as a whole. There is a thicker supporting insulating tube 501 between the insulating tube 501 and the wall of the raising seat 101. The supporting tube is fixed to the wall of the raising seat 101 through insulating parts. The outside of the insulating tube 501 is wrapped with insulating angle rings in many places, and the insulating angle rings are supported on the supporting tube. The supporting structure has high strength and is both firm and safe.

[0049] The present invention also discloses a method for calculating the placement position of an insulating member of a variable resistivity ultra-high voltage valve-side outlet device, which comprises the following steps:

[0050] S1: Modeling, inputting electrode voltages, and setting boundary conditions;

[0051] S2: Use electric field calculation software to calculate AC and DC electric fields;

[0052] S3: Draw the AC electric field power lines and perform oil gap field strength safety margin on the points on the power lines;

[0053] S4: Perform creepage check on the oil-paper insulation interface;

[0054] S5: Use DC electric field to check the maximum DC field strength of each insulating component and the DC creepage field strength at the interface between the insulating component and the oil;

[0055] S6: Determine the placement position of the insulating member based on the verification results in steps S3, S4 and S5.

[0056] In summary, combined Figure 2As shown, the variable resistivity UHV valve-side outlet device of the present invention utilizes a combination of a voltage-equalizing ball 201, an insulating layer 202, an inner insulating member 203, and an outer insulating member 204 to effectively reduce the DC and AC electric field strengths on the surface of the voltage-equalizing ball 201, as well as the DC creepage field strength on the surfaces of the insulating layer 202, the inner insulating member 203, and the outer insulating member 204, thereby ensuring the electrical strength and insulation reliability of the voltage-equalizing ball 201. The two-layer molded member surrounding the voltage-equalizing ball 201 adopts an antelope-shaped structure. The inner and outer equipotential segments 2031 and 2041 extending from the upper ends attract equipotential lines, reducing the DC electric field strength in the pulp of the voltage-equalizing ball 201 and the creepage field strength on the pulp surface of the voltage-equalizing ball 201. The oil gap between the inner insulating part 203, the outer insulating part 204 and the equalizing ball 201 is divided. The inner insulating part 203 and the outer insulating part 204 divide the large oil gap from the equalizing ball 201 to the insulating tube 501 into three small oil gaps, thereby improving the safety margin of the AC electric field in the oil gap on the surface of the equalizing ball 201. At the same time, under the action of DC voltage, the equipotential lines in the insulating layer 202 of the equalizing ball 201 enter the oil and then diverge into the insulation of the shielding tube 103, thereby reducing the creepage electric field strength on the surface of the shielding tube 103.

[0057] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art will appreciate that the technical solutions described in the above embodiments may be modified or some or all of the technical features thereof may be replaced with equivalents, and that such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the various embodiments of the present invention.

Claims

1. A variable resistivity ultra-high voltage valve side outlet device, characterized in that: include: An elevating seat, a pressure-equalizing ball fixed inside the elevating seat, a valve-side sleeve with its tail end inserted into the pressure-equalizing ball, and a shielding cylinder with its head inserted into the pressure-equalizing ball; an insulating layer, an inner insulating member, and an outer insulating member are sequentially provided on the outside of the pressure-equalizing ball; an insulating oil passage is provided between the insulating layer and the inner insulating member, and an insulating oil passage is provided between the inner insulating member and the outer insulating member; The insulating layer is arranged on the outer surface of the pressure equalizing ball, the top and the bottom of the pressure equalizing ball are both sharp ends, and the insulating layer covers the sharp ends; The inner insulating member includes, from top to bottom, an inner equipotential section, an inner contour section, a bent section, and an inner vertical section connected end to end. The setting angle of the inner equipotential section is the same as the angle of the electric field. The inner contour section has the same shape as the voltage-equalizing ball. The bent section is bent inward by 25-40 degrees from top to bottom. The outer insulating part includes an outer equipotential segment, an outer contour segment and an outer vertical segment from top to bottom. The setting angle of the outer equipotential segment is the same as the angle of the electric field. The outer contour segment has the same shape as the equalizing ball. The upper end of the outer vertical segment is at the same height as the center of the equalizing ball.

2. The variable resistivity UHV valve side outlet device according to claim 1, characterized in that: The inner insulating member and the outer insulating member have the same structure, including insulating bars and an insulating layer covering the insulating bars, and the insulating bars are made of laminated paperboard.

3. The variable resistivity UHV valve side outlet device according to claim 1, characterized in that: A shielding ring is provided between the shielding cylinder and the voltage-equalizing ball, and the surface of the shielding ring is provided with insulating paint; the shielding ring, the shielding cylinder and the voltage-equalizing ball are electrically connected to form an equipotential body through metal parts.

4. The variable resistivity UHV valve side outlet device according to claim 1, characterized in that: The shielding tube is an aluminum round tube, the top of the shielding tube is trumpet-shaped, the end of the shielding tube is a smooth structure, and the outside of the shielding tube is provided with heat-modified insulating paper.

5. The variable resistivity UHV valve-side outlet device according to claim 4, characterized in that: A plurality of insulating component groups are provided outside the shielding tube, and the insulating component groups are evenly distributed along the outer circumference of the shielding tube. The insulating component groups include inner support bars and outer support bars, and the inner support bars and the outer support bars are both made of cardboard, and there is an oil gap between the inner support bars and the outer support bars.

6. The variable resistivity UHV valve-side outlet device according to claim 1, characterized in that: A plurality of insulating paper tubes are provided between the pressure-equalizing ball and the inner wall of the raising seat. The insulating paper tubes are corrugated paper tubes made of T3 paperboard or T4 paperboard.

7. The design method of a variable resistivity ultra-high voltage valve-side outlet device according to any one of claims 1 to 6, characterized in that: The method for calculating the placement of insulation includes the following steps: S1: Modeling, inputting electrode voltages, and setting boundary conditions; S2: Use electric field calculation software to calculate AC and DC electric fields; S3: Draw the AC electric field power lines and perform oil gap field strength safety margin on the points on the power lines; S4: Perform creepage check on the oil-paper insulation interface; S5: Use DC electric field to check the maximum DC field strength of each insulating component and the DC creepage field strength at the interface between the insulating component and the oil; S6: Determine the placement position of the insulating member based on the verification results in steps S3, S4 and S5.

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