An insulating device for use in a gas-liquid mixed medium

Abstract

The present invention provides an insulating device for use in a gas-liquid mixed medium, belonging to the field of high-voltage insulation, and the insulating device comprises: a first insulator segment, a second insulator segment and a third insulator segment; the first insulator segment and the second insulator segment are both truncated cone-shaped; the third insulator segment is cylindrical; the upper bottom surface of the first insulator segment is connected to a high-potential metal body, and the lower bottom surface is fixed to the lower bottom surface of the second insulator segment; one bottom surface of the third insulator segment is connected to a low-potential metal body, and the other bottom surface is fixed to the upper bottom surface of the second insulator segment; the side surface of the first insulator segment, the side surface of the second insulator segment and the side surface of the third insulator segment are all in the shape of a sine function curve in the axial direction. The problem of the gas-liquid mixed medium gathering on the surface of the insulating device, resulting in a decrease in insulation performance, is avoided, that is, the insulation performance of the insulating device in the gas-liquid mixed medium is improved.

Description

Technical Field

[0001] The invention relates to the field of high voltage insulation, and in particular to an insulation device used in a gas-liquid mixed medium. Background Art

[0002] Fluorocarbons and other materials with excellent insulation properties, non-flammability, good chemical stability, and low boiling point (40-70°C) will take away a lot of heat during the phase change (liquid-gas) process, so they are used in the heat dissipation of hydro-generators and computers in big data centers. This type of material that uses the phase change heat transfer process to cool the device is usually called a phase change heat transfer medium. The application of this type of medium in the heat dissipation field of high-voltage equipment is not yet mature. At present, it has only been initially explored in power transformers, capacitors, converter valves and other equipment, and has not yet been widely used.

[0003] High-voltage direct current transmission equipment such as converter valves have an important demand for a heat dissipation system with high reliability. Take the deionized water cooling system used for converter valve cooling as an example. According to statistics, among the 47 emergency major defects of converter valves in 3 years, 21 (45%) were caused by the water cooling system. After analysis, the main reasons are water leakage (9 times), water pump failure (7 times) and valve cooling controller failure (5 times). The reason is that the heat dissipation system with water as the cooling medium often leads to insulation failure after leakage; and the water cooling system has more equipment and complex control, which will increase the failure rate of the converter valve. Materials such as fluorocarbons have excellent insulation properties and chemical stability. If the phase change process is used for heat dissipation, it can achieve a fundamental innovation in the refrigeration technology of the converter valve system. However, when it comes to the specific design of the converter valve system, there are unresolved technical problems in the fields of internal insulation structure design, external insulation matching, incompatible material selection, type test methods, operation and maintenance methods, and so on, and the technology to support the long-term reliable operation of the system has not yet been formed. Summary of the invention

[0004] The object of the present invention is to provide an insulating device for use in a gas-liquid mixed medium, which can avoid the problem of the gas-liquid mixed medium gathering on the surface of the insulating device and causing the insulation performance to deteriorate.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An insulating device for use in a gas-liquid mixed medium, comprising: a first insulator segment, a second insulator segment and a third insulator segment;

[0007] The first insulator segment and the second insulator segment are both truncated cone-shaped; the third insulator segment is cylindrical;

[0008] The upper bottom surface of the first insulator segment is connected to the high-potential metal body, and the lower bottom surface is fixed to the lower bottom surface of the second insulator segment;

[0009] One bottom surface of the third insulator segment is connected to the low-potential metal body, and the other bottom surface is fixed to the upper bottom surface of the second insulator segment;

[0010] The side surface of the first insulator segment, the side surface of the second insulator segment, and the side surface of the third insulator segment are all in the shape of a sine function curve in the axial direction.

[0011] Optionally, the diameter of the upper bottom surface of the first insulator segment is greater than or equal to the diameter of the high-potential metal body.

[0012] Optionally, a diameter of a lower bottom surface of the first insulator segment is twice a diameter of an upper bottom surface of the first insulator segment.

[0013] Optionally, the diameter of the lower bottom surface of the second insulator segment is equal to the diameter of the lower bottom surface of the first insulator segment; the diameter of the upper bottom surface of the second insulator segment is equal to the diameter of the upper bottom surface of the first insulator segment.

[0014] Optionally, a bottom diameter of the third insulator segment is equal to an upper bottom diameter of the second insulator segment.

[0015] Optionally, the axial curve length of the side surface of the first insulator segment is:

[0016]

[0017] Among them, l 1 is the axial curve length of the side of the first insulator segment, h 2 is the bottom diameter of the first insulator segment, h 1 is the upper base diameter of the first insulator segment.

[0018] Optionally, the axial curve function of the side surface of the first insulator segment is:

[0019]

[0020] Among them, x 1 is the distance between the upper bottom surface of the first insulator segment and the lower bottom surface of the first insulator segment, r 0 is the maximum bubble diameter when the medium is boiling, l 1 is the axial curve length of the side surface of the first insulator segment; if the value range of A does not exist, the side surface of the first insulator segment adopts a straight line.

[0021] Optionally, the direction of the axial curve function of the side surface of the second insulator segment is opposite to the direction of the axial curve function of the side surface of the first insulator segment.

[0022] Optionally, the axial curve function of the side surface of the third insulator segment is:

[0023]

[0024] Among them, x 2 is the distance between the upper bottom surface of the second insulator segment and the low-potential metal body, l 1 is the axial curve length of the side of the first insulator segment, d 3 is the projected length of the axial curve on the side of the third insulator segment, l 1 is the axial curve length of the side of the first insulator segment, ceiling() is the rounding function, d 3 = l T -2l 1 , l T is the shortest creepage length of the insulating device, E is the breakdown field strength of the phase change heat medium in liquid state, l 0 The withstand voltage is |U H -U L |The creepage length of the insulator, U H is the potential of the high potential metal body, U L is the potential of the low-potential metal body, p is the boiling degree of the phase-change heat medium liquid, k is the coefficient, and kE is the field strength inside the bubble after the phase-change heat medium boils and vaporizes.

[0025] According to the specific embodiment provided by the present invention, the present invention discloses the following technical effects: by setting two truncated cone-shaped insulator segments and one cylindrical insulator segment, and the side surfaces of the three insulator segments are all in the shape of a sine function curve in the axial direction, the upper bottom surface of the first insulator segment is connected to the high-potential metal body, and the lower bottom surface is fixed to the lower bottom surface of the second insulator segment; one bottom surface of the third insulator segment is connected to the low-potential metal body, and the other bottom surface is fixed to the upper bottom surface of the second insulator segment, thereby avoiding the problem of gas-liquid mixed medium gathering on the surface of the insulating device and causing the insulation performance to decrease, that is, the insulation performance of the insulating device in the gas-liquid mixed medium is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 It is an overall schematic diagram of the insulating device used in a gas-liquid mixed medium of the present invention.

[0028] Explanation of symbols:

[0029] A first insulator segment-1, a second insulator segment-2, a third insulator segment-3, a high-potential metal body-4, and a low-potential metal body-5. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The purpose of the present invention is to provide an insulating device for use in a gas-liquid mixed medium. By reasonably setting the shapes of the three insulator segments, the problem of the gas-liquid mixed medium gathering on the surface of the insulating device and causing the insulation performance to decrease is avoided, that is, the insulation performance of the insulating device in the gas-liquid mixed medium is improved.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The present invention designs an insulating device based on the insulator immersed in the phase-change heat medium inside the converter valve when the phase-change heat medium is used. The air insulators usually designed are mostly umbrella skirt structures, and only the insulation performance under high voltage at both ends needs to be considered. In addition to considering the creepage distance to ensure the insulation performance, the insulating device provided by the present invention focuses on the gas-liquid mixed state of the phase-change heat medium under boiling conditions. In order to avoid bubbles gathering on the surface of the insulator and causing the insulation performance to decrease, the curvature and length of the insulator surface are designed.

[0034] like Figure 1 As shown, the insulating device for gas-liquid mixed medium of the present invention comprises: a first insulator segment 1, a second insulator segment 2 and a third insulator segment 3.

[0035] The first insulator segment 1 and the second insulator segment 2 are both truncated cone-shaped. The third insulator segment 3 is cylindrical. That is, the first insulator segment 1, the second insulator segment 2, and the third insulator segment 3 are all composed of two circular bottom surfaces and side surfaces. The diameters of the upper bottom surfaces of the first insulator segment 1 and the second insulator segment 2 are both smaller than the diameter of the lower bottom surface. The diameters of the two ground surfaces of the third insulator segment 3 are equal.

[0036] The upper bottom surface of the first insulator segment 1 is connected to the high-potential metal body 4 , and the lower bottom surface is fixed to the lower bottom surface of the second insulator segment 2 .

[0037] One bottom surface of the third insulator segment 3 is connected to the low-potential metal body 5 , and the other bottom surface is fixed to the upper bottom surface of the second insulator segment 2 .

[0038] The side surface of the first insulator segment 1 , the side surface of the second insulator segment 2 , and the side surface of the third insulator segment 3 are all in the shape of a sine function curve in the axial direction.

[0039] In fact, since the side surfaces of the first insulator segment 1, the second insulator segment 2 and the third insulator segment 3 are all in the shape of a sine function curve in the axial direction, the first insulator segment 1 and the second insulator segment 2 are approximately truncated cone-shaped, and the third insulator segment 3 is approximately cylindrical.

[0040] Since the first insulator segment 1 is adjacent to the high voltage area, the field strength in this area is high. In order to improve the field strength distribution, the first insulator segment 1 adopts a structure similar to a truncated cone, and in order to increase the creepage distance, a sine function curve shape is adopted on the side of the truncated cone. The third insulator segment 3 is far away from the high field strength area, so it adopts a cylindrical structure and a sine function curve shape is adopted on the surface.

[0041] In this embodiment, the diameter h of the upper bottom surface of the first insulator segment 1 is 1 is greater than or equal to the diameter d of the high potential metal body 4. (U H is the potential of the high potential metal body 4, U L is the potential of the low potential metal body 5, both in kV), then h 1 Pick (Unit: cm).

[0042] The lower bottom diameter h of the first insulator segment 1 2 (i.e. the maximum diameter of the first insulator segment 1) is the upper bottom surface diameter h of the first insulator segment 1 1 2 times: h 2 =2h 1 .

[0043] The diameter of the lower bottom surface of the second insulator segment 2 is equal to the diameter of the lower bottom surface of the first insulator segment 1 .

[0044] The diameter of the upper bottom surface of the second insulator segment 2 is equal to the diameter of the upper bottom surface of the first insulator segment 1 .

[0045] The bottom diameter h of the third insulator segment 3 3 The diameter is equal to the upper bottom surface diameter of the second insulator segment 2.

[0046] Specifically, the axial curve length of the side surface of the first insulator segment 1 (the side curve of the first insulator segment 1 from the surface adjacent to the high-potential metal body 4 to the maximum diameter) is:

[0047]

[0048] Among them, l 1 is the axial curve length of the side of the first insulator segment, h 2 is the bottom diameter of the first insulator segment, h 1 is the upper base diameter of the first insulator segment.

[0049] The axial curve function of the side of the first insulator segment is:

[0050]

[0051] Among them, x 1 is the distance between the upper bottom surface of the first insulator segment and the lower bottom surface of the first insulator segment, ranging from 0 to l 1 A is controlled by the boiling degree of the liquid. The maximum bubble diameter when the phase change medium boils is r 0 , the value range of A is 5r 0 <A<l 1 / 6. In practical applications, if the bubble is large, resulting in the non-existence of the value range of A, the side of the first insulator segment adopts a straight line. In addition, if A>5r 0 , then directly take A=l 1 / 6.

[0052] Figure 1 In the example, the length of the first insulator segment 1 (l 1 The projection of 1 , the length of the second insulator segment 2 is d 2 (The axial curve length l of the side of the second insulator segment 2 2 The length of the third insulator segment 3 is d 3 (The axial curve length l of the side of the third insulator segment 3 3 projection).

[0053] The axial curve function of the side surface of the second insulator segment 2 is the same as the axial curve function of the side surface of the first insulator segment 1 , but in the opposite direction.

[0054] The axial curve function of the side surface of the third insulator segment 3 is:

[0055]

[0056] Among them, x 2 is the distance between the upper bottom surface of the second insulator segment and the low potential metal body, ranging from 0 to d 3 , l 1 is the axial curve length of the side of the first insulator segment, d 3is the projected length of the axial curve on the side of the third insulator segment, l 1 is the axial curve length of the side surface of the first insulator segment, and ceiling() is a rounding-up function.

[0057] Specifically, the value of N is determined by the creepage distance. The breakdown field strength of the phase change heat medium in liquid state is E (in kV / mm), and the field strength inside the bubble after the phase change heat medium boils and vaporizes is kE. (Usually, it can be taken as ).

[0058] According to the design principle of creepage length of insulator under current air insulation, for the withstand voltage of |U H -U L |The insulator has a creepage length of l 0 , then the shortest creepage length of the insulation device of the present invention is Where p is the boiling degree of the phase change heat medium liquid, indicating the proportion of liquid after the phase change heat medium boils.

[0059] Therefore, 3 Take l T -2l 1 .

[0060] Based on the above expression, That is: N is Add one to the integer part of .

[0061] The present invention designs the insulator surface curvature, insulator creepage length and grading ring in the high field strength area at the insulator end respectively by taking into account the size of gas-liquid mixed bubbles, bubble density and the angle of electric field change inside and outside the bubbles, thereby improving the insulation performance of the insulator in the gas-liquid mixed medium.

[0062] In order to better understand the solution of the present invention, it is further described below in conjunction with specific embodiments.

[0063] This embodiment takes the structure used in a 100kV valve section as an example. H -U L | is 100kV.

[0064] (1)h 1 : Without considering the value of the diameter d of the high-potential metal body, h 1 =5cm.

[0065] (2)h 2 : Maximum diameter of the first insulator segment, h 2 =10cm.

[0066] (3)h 3 : The maximum diameter of the third insulator segment, h3 =5cm.

[0067] (4)l 1 :l 1 The projection length is d 1 , l 1 =10cm. 1 The curve function is If the bubbles are small,

[0068] (5)l 2 :Curve function and l 1 Same, opposite direction.

[0069] (6)l 3 :l 3 The curve function is

[0070] The breakdown field strength of the phase change heat medium in the liquid state is 15kV / mm, and the field strength in the bubble after the medium boils and vaporizes is 5kV / mm, that is, After boiling, the liquid volume accounts for 90%.

[0071] If the creepage length l 0 =80cm, then:

[0072] At this time 3 According to l T -2l 1 The calculation result is a negative number, indicating that the third insulator segment is not required.

[0073] This embodiment takes the structure used in a 500kV valve section as an example. H -U L | is 500kV.

[0074] (1)h 1 : Without considering the value of the diameter d of the high-potential metal body, h 1 =25cm.

[0075] (2)h 2 : Maximum diameter of the first insulator segment, h 2 =50cm.

[0076] (3)h 3 : The maximum diameter of the third insulator segment, h 3 =25cm.

[0077] (4)l 1 :l 1 The projection length is d 1 , l 1=50cm. 1 The curve function is If the bubbles are small,

[0078] (5)l 2 : The function is the same as l1, but in the opposite direction.

[0079] (6)l 3 :The curve function is

[0080] The breakdown field strength of the phase change heat medium in the liquid state is 15kV / mm, and the field strength in the bubble after the medium boils and vaporizes is 5kV / mm, that is, After boiling, the liquid volume accounts for 90%.

[0081] If the creepage length l 0 =600cm, then:

[0082] At this time 3 According to l T -2l 1 Calculated, the result is 28.57cm.

[0083] Therefore, N follows Calculate and the result is 2.

[0084] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0085] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An insulating device for use in a gas-liquid mixed medium, characterized in that: The insulating device used in a gas-liquid mixed medium comprises: a first insulator segment, a second insulator segment and a third insulator segment; The first insulator segment and the second insulator segment are both truncated cone-shaped; the third insulator segment is cylindrical; The upper bottom surface of the first insulator segment is connected to the high-potential metal body, and the lower bottom surface is fixed to the lower bottom surface of the second insulator segment; One bottom surface of the third insulator segment is connected to the low-potential metal body, and the other bottom surface is fixed to the upper bottom surface of the second insulator segment; The side surface of the first insulator segment, the side surface of the second insulator segment and the side surface of the third insulator segment are all in the shape of a sine function curve in the axial direction; The axial curve function of the side surface of the first insulator segment is: Wherein, x1 is the distance between the upper bottom surface of the first insulator segment and the lower bottom surface of the first insulator segment, r0 is the maximum bubble diameter when the medium is boiling, l1 is the axial curve length of the side surface of the first insulator segment; if the value range of A does not exist, the side surface of the first insulator segment adopts a straight line; The axial curve function of the side surface of the second insulator segment is in the opposite direction to the axial curve function of the side surface of the first insulator segment; The axial curve function of the side surface of the third insulator segment is: Wherein, x2 is the distance between the upper bottom surface of the second insulator segment and the low-potential metal body, l1 is the axial curve length of the side of the first insulator segment, d3 is the projection length of the axial curve of the side of the third insulator segment, l1 is the axial curve length of the side of the first insulator segment, ceiling() is the rounding function, d3=l T -2l1,l T is the shortest creepage length of the insulating device, E is the breakdown field strength of the phase change heat medium in liquid state, l0 is the withstand voltage |U H -U L |The creepage length of the insulator, U H is the potential of the high potential metal body, U L is the potential of the low-potential metal body, p is the boiling degree of the phase-change heat medium liquid, k is the coefficient, and kE is the field strength inside the bubble after the phase-change heat medium boils and vaporizes.

2. The insulating device for use in a gas-liquid mixed medium according to claim 1, characterized in that: The diameter of the upper bottom surface of the first insulator segment is greater than or equal to the diameter of the high-potential metal body.

3. The insulating device for use in a gas-liquid mixed medium according to claim 1 or 2, characterized in that: The diameter of the lower bottom surface of the first insulator segment is twice the diameter of the upper bottom surface of the first insulator segment.

4. The insulating device for use in a gas-liquid mixed medium according to claim 1, characterized in that: The diameter of the lower bottom surface of the second insulator segment is equal to the diameter of the lower bottom surface of the first insulator segment; the diameter of the upper bottom surface of the second insulator segment is equal to the diameter of the upper bottom surface of the first insulator segment.

5. The insulating device for use in a gas-liquid mixed medium according to claim 1, characterized in that: The bottom surface diameter of the third insulator segment is equal to the upper bottom surface diameter of the second insulator segment.

6. The insulating device for use in a gas-liquid mixed medium according to claim 1, characterized in that: The axial curve length of the side surface of the first insulator segment is: Wherein, l1 is the axial curve length of the side surface of the first insulator segment, h2 is the lower base diameter of the first insulator segment, and h1 is the upper base diameter of the first insulator segment.

Images