Ultra-high voltage bushing and manufacturing method thereof

Abstract

The invention discloses an ultra-high voltage bushing, whose capacitor screen adopts the design concept of long and short screens and equal margins, which can reduce the amount of aluminum foil used and reduce the overall manufacturing cost of the bushing; the long and short capacitor screens are punched, and the rolled tubes and the current-carrying tubes are cross-punched, so that the insulating cable paper near the current-carrying tubes can form convection with the inner side of the current-carrying tubes through the pores, and the water vapor evaporation channel is increased when the capacitor core is dried, which can accelerate the evaporation rate of the water in the insulating cable paper, shorten the vacuum pumping time, and improve the oil immersion speed and efficiency, thereby shortening the process cycle and reducing energy consumption and cost; the invention also discloses a manufacturing method for the ultra-high voltage bushing, which adopts clean rolling, vacuum drying, vertical assembly, vacuum pressure oil immersion and other processes, and can ensure the stability of the electrical performance of the bushing.

Description

Technical Field

[0001] The invention relates to an ultra-high voltage bushing and a manufacturing method thereof, belonging to the technical field of ultra-high voltage bushing and manufacturing thereof. Background Art

[0002] At present, my country's cross-regional power transmission demand is constantly increasing, and ultra-high voltage efficient transmission is highly favored. As an important component of the core equipment of ultra-ultra-high voltage substation, the operation reliability of ultra-high voltage bushing is directly related to the safe and stable operation of ultra-ultra-high voltage transformers, high-voltage reactors and converter transformers.

[0003] The UHV bushing capacitor core has a large diameter and a long length, and has many capacitor screen layers. If the capacitor core is designed according to conventional design concepts, the overall production process time of the bushing will be much longer than that of conventional high-voltage bushing products, making it difficult to achieve mass production of UHV bushings. If the process time is insufficient, the insulation effect of the capacitor core will be greatly affected, and the electrical performance of the bushing will not be guaranteed. Summary of the invention

[0004] In order to solve the deficiencies of the above technical problems, the present invention provides an ultra-high voltage bushing and a manufacturing method thereof, so as to solve the problems of great difficulty in producing the existing ultra-high voltage bushing, long process cycle and high cost.

[0005] The technical solution adopted by the present invention is:

[0006] A UHV bushing comprises a head structure, an outer insulation, a capacitor core, a current-carrying tube and a tail structure, wherein the upper end of the current-carrying tube is electrically connected to the head structure, the lower end of the current-carrying tube is electrically connected to the tail structure, the outer insulation is coaxially sleeved on the outside of the current-carrying tube, the upper end of the outer insulation is sealedly connected to the head structure, the lower end of the outer insulation is sealedly connected to the tail structure, an annular space is formed between the inner wall of the outer insulation and the outer wall of the current-carrying tube, the capacitor core is sleeved outside the current-carrying tube body and is located in the annular space, a gap is provided between the outer surface of the capacitor core and the inner wall of the outer insulation and is filled with insulating oil,

[0007] The capacitor core comprises a winding tube, several groups of insulating cable paper layers, several groups of short capacitor screen layers and several groups of long capacitor screen layers, the winding tube is sleeved on the outside of the current-carrying tube body, the several groups of insulating cable paper layers, the several groups of short capacitor screen layers and the several groups of long capacitor screen layers are alternately wound on the outer wall of the winding tube from the inside to the outside, and a layer of insulating cable paper layer is wound outside the long capacitor screen layer located at the outermost layer, each layer of insulating cable paper layer comprises an insulating cable paper layer, each layer of long capacitor screen layer comprises a long capacitor screen, each layer of short capacitor screen layer comprises two staggered short capacitor screens, and a layer of insulating cable paper layer is wound between two adjacent short capacitor screen layers, between two adjacent long capacitor screen layers and between adjacent short capacitor screen layers and long capacitor screen layers;

[0008] Along the length direction of the current-carrying tube and the rolled tube, a plurality of through hole groups 1 and a plurality of through hole groups 2 are respectively and sequentially opened on the current-carrying tube and the rolled tube, and the through holes 1 on two adjacent through hole groups 1 and the through holes 2 on two adjacent through hole groups 2 are staggered with each other; through holes 3 are respectively opened on the long capacitor screen and the short capacitor screen, and after rolling, the through holes 3 on the long capacitor screen and the short capacitor screen are in a spiral shape that spreads outward with the current-carrying tube as the center.

[0009] As a preferred embodiment of the present invention, the number of layers of the insulating cable paper layer in each layer group is at least 1 layer, the number of layers of the short capacitor screen in each layer group is 1-3 layers, and the number of layers of the long capacitor screen in each layer group is 1-8 layers.

[0010] As a preferred embodiment of the present invention, the external insulation includes an upper porcelain sleeve, a sleeve flange and a lower porcelain sleeve connected in sequence from top to bottom, the upper end of the upper porcelain sleeve is sealed connected to the head structure, the lower end of the upper porcelain sleeve is sealed connected to the upper end flange of the sleeve flange, the lower end of the sleeve flange is sealed connected to the upper end of the lower porcelain sleeve, and the lower end of the lower porcelain sleeve is sealed connected to the tail structure.

[0011] As a preferred embodiment of the present invention, the head structure includes an oil pillow, an upper wiring board and a spring clamping device. The oil pillow is a cylindrical structure which is closed at the top and bottom and hollow inside. The lower end of the oil pillow is fixedly arranged in the upper end sleeve of the upper porcelain sleeve. A conductive sealing head is arranged at the upper end of the oil pillow. Through holes for the upper end of the current-carrying tube to pass through are correspondingly opened at the upper and lower ends of the oil pillow and the conductive sealing head. The current-carrying tube passes through the corresponding two through holes on the oil pillow and the through hole on the conductive sealing head from bottom to top and extends to above the upper end of the oil pillow. A sealing ring for sealing is arranged between the current-carrying tube and the through hole. The upper wiring board is arranged at the upper end of the current-carrying tube.

[0012] The spring clamping device includes a support ring sleeved on the current-carrying tube located in the oil pillow and fixedly connected to the lower end of the oil pillow, a plurality of springs, and a pressure plate fixedly arranged on the tube body of the current-carrying tube located in the oil pillow and above the support ring. The plurality of springs are evenly spaced and arranged along the circumference of the current-carrying tube and are respectively positioned above the support ring through positioning columns fixedly connected to the support ring at the bottom ends. Several positioning columns are inserted through the pressure plate. The plurality of springs are sleeved on the positioning columns between the pressure plate and the support ring in a compressed state.

[0013] An oil filling port is provided on one side of the oil pillow, and insulating oil is injected into the oil pillow through the oil filling port.

[0014] As a preferred embodiment of the present invention, the head structure further includes a pressure equalizing ring, which includes two first ring bodies symmetrically arranged at the upper end and the lower end and two second ring bodies symmetrically arranged between the two first ring bodies, the inner diameter of the first ring body is smaller than the inner diameter of the second ring body, a plurality of first connecting tubes are arranged between adjacent first ring bodies and second ring bodies and between two adjacent second ring bodies, and a plurality of second connecting tubes are vertically arranged between the two first ring bodies;

[0015] The pressure equalizing ring sleeve is arranged outside the oil pillow, a fixed cover is arranged on the conductive sealing head, and fixing rods fixedly connected to the corresponding side fixed covers are respectively arranged on the first connecting tube between the two second ring bodies and on the first connecting tube between the first ring body and the second ring body at the upper end.

[0016] As a preferred embodiment of the present invention, the tail structure includes a base current-carrying disk with a convex structure and a vertical hole, a wiring base arranged at the lower end of the base current-carrying disk, and a lower wiring board arranged at the lower end of the wiring base, the inner diameter of the vertical hole in the small diameter section of the upper end of the base current-carrying disk is larger than the inner diameter of the vertical hole in the large diameter section of the lower end of the base current-carrying disk, the small diameter section of the upper end of the base current-carrying disk is fixedly embedded in the lower end sleeve of the lower porcelain sleeve, and the upper end surface of the large diameter section of the lower end of the base current-carrying disk is abutted against the lower end of the lower porcelain sleeve, the lower end of the rolled tube is inserted into the vertical hole on the small diameter section of the upper end of the base current-carrying disk and fits with the inner wall of the vertical hole, the current-carrying tube is inserted through the small diameter section and the vertical hole in the large diameter section of the base current-carrying disk from top to bottom in sequence and extends to the wiring base at the lower end of the base current-carrying disk, and a sealing ring for sealing is also provided between the current-carrying tube and the vertical hole in the large diameter section of the lower end of the base current-carrying disk.

[0017] Any of the above-mentioned methods for manufacturing ultra-high voltage bushings comprises the following steps:

[0018] Step 1: Pretreatment: Cut the insulating cable paper according to the size, and then dry the paper reel; punch holes in the current-carrying tube and the coiled tube, and the position, size, orientation and spacing of the holes are obtained through fluid temperature field simulation; punch holes in the long capacitor screen and the short capacitor screen, and use a fully automatic capacitor screen punching machine to control the size and position of the holes;

[0019] Step 2: Clean rolling: Wipe and fix the rolling tube to the capacitor core rolling machine, and then roll the insulating cable paper, long capacitor screen, and short capacitor screen onto the rolling tube in sequence according to the capacitor core structure. By controlling the gradient of each screen, the starting angle of the capacitor screen rolling, and the punching position on the capacitor screen, the upper and lower screen holes are staggered;

[0020] Step 3: Vacuum drying of capacitor core: the rolled capacitor core is transferred to a vacuum drying tank for vacuum drying;

[0021] Step 4: Vertical assembly: Assemble the components of the UHV bushing according to the product structure;

[0022] Step 5: Vacuum pressure oil immersion: The assembled UHV bushing is transferred to the vacuum pressure oil immersion equipment for vacuum pressure oil immersion treatment;

[0023] Step 6: Post-processing: The UHV bushings after vacuum pressure oil immersion treatment are inspected, packaged and re-inspected in sequence. After passing the re-inspection, they can be put into storage and wait for delivery.

[0024] As a preferred embodiment of the present invention, the specific method for treating the capacitor core transported to the vacuum drying tank in the step 3 of vacuum drying the capacitor core is:

[0025] Step 1: High temperature drying treatment under normal pressure: the temperature in the tank is set to 100°C and the heating time is 12h;

[0026] Step 2: High-temperature drying treatment by pressure-variable method: The temperature in the tank is set to 105°C, and the tank is evacuated and broken in cycles. Each evacuation is ≤1000Pa, and the heating time for each evacuation is 4 hours. The total time for high-temperature drying treatment by pressure-variable method is 200 hours.

[0027] Step 3: Low vacuum and high temperature drying: vacuum degree ≤ 140Pa, the temperature in the tank is set to 115℃, and the heating time is 50h;

[0028] Step 4: High vacuum and high temperature drying: vacuum degree ≤ 2Pa, the temperature in the tank is set to 115℃, and the heating time is 110h;

[0029] Step 5: Vacuum cooling: vacuum degree ≤ 2Pa, the temperature inside the tank drops to 50°C;

[0030] Step 6: Break the vacuum tank and take it out: Break the vacuum tank, lift the capacitor core out of the vacuum tank, and then load it into the assembly workshop.

[0031] As a preferred embodiment of the present invention, the specific method of vacuum pressure oil immersion treatment of the capacitor core transported to the vacuum pressure oil immersion equipment in the step 5 of vacuum drying of the capacitor core is:

[0032] Step 1: Connect the hose on the oil-immersed pipeline to the oil filling ports of the casing head structure and tail structure, and perform leak detection on the casing;

[0033] Step 2: After the casing leak detection is completed, heat the drying room and keep the temperature at 75°C;

[0034] Step 3: Evacuate the casing to a vacuum degree of ≤2Pa for 200h;

[0035] Step 4: Circulate the casing to evacuate and oil it, with the vacuum degree of each evacuation ≤2Pa, and maintain it for 30 hours, with a total time of 180 hours;

[0036] Step 5: Pressure impregnation: Apply oil pressure of 0.3MPa to the inside of the casing, keep the oil temperature at 75℃, and the impregnation time is 330h;

[0037] Step 6: Start the pipeline oil circulation, the circulation time is 10 hours;

[0038] Step 7: Cool down and evacuate the air. The temperature drops to 30℃ and the evacuation time is 50h.

[0039] The beneficial effects of the present invention are:

[0040] 1. The capacitive screen uses a long and short screen, which can reduce the amount of aluminum foil, shorten the process cycle, and reduce the overall manufacturing cost of the casing;

[0041] 2. Punch holes in the capacitor screen, coiled tubes and cross-punch holes in the coiled tubes, so that the cable paper near the current-carrying tube can form convection with the inner side of the current-carrying tube through the pores. When the capacitor core is dried, it can increase the water vapor evaporation channel and accelerate the evaporation rate of the cable paper. The vacuuming and oil immersion can also be more sufficient, and the vacuuming time can be shortened, the speed and efficiency of oil immersion can be improved, and the process cycle can be shortened while reducing energy consumption and costs;

[0042] 3. The use of clean rolling, vacuum drying, vertical assembly, vacuum pressure oil immersion and other process technologies can ensure the stability of the electrical performance of the bushing;

[0043] 4. By taking the above measures, the casing cost can be saved by about 1 / 5 and the process cycle can be shortened by about 1 / 3. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of the overall structure of the UHV bushing provided by the present invention;

[0045] Figure 2A schematic diagram of the head structure of the UHV bushing provided by the present invention;

[0046] Figure 3 A schematic diagram of the structure of the external insulation of the UHV bushing provided by the present invention;

[0047] Figure 4 A schematic diagram of the tail structure of the UHV bushing provided by the present invention;

[0048] Figure 5 A schematic structural diagram of a capacitor core of an ultra-high voltage bushing provided by the present invention;

[0049] Figure 6 A top view of the capacitor core of the UHV bushing provided by the present invention;

[0050] Figure 7 A schematic diagram of the punching positions of the rolled tube in the capacitor core of the UHV bushing provided by the present invention;

[0051] Figure 8 for Figure 7 A-direction view of the pipe during rolling;

[0052] Fig. 9 for Figure 7 Cross-sectional view of the middle rolled pipe at BB;

[0053] Fig.10 for Figure 7 Cross-sectional view of CC of the middle rolled pipe;

[0054] Fig.11 for Figure 7 Cross-sectional view of the middle rolled pipe at DD;

[0055] Fig.12 Schematic diagram of punching holes in short capacitive screen;

[0056] Fig.13 Schematic diagram of punching holes in a long capacitive screen;

[0057] Fig.14 A schematic diagram of a capacitive screen arrangement corresponding to two long capacitive screens and one short capacitive screen above and below;

[0058] Fig.15 The equivalent circuit diagram corresponding to two long capacitive screens and one short capacitive screen above and below;

[0059] Fig.16 A schematic diagram of a capacitive screen arrangement corresponding to two long capacitive screens and two short capacitive screens above and below;

[0060] Fig.17 It is the equivalent circuit diagram corresponding to two long capacitive screens and two short capacitive screens above and below. DETAILED DESCRIPTION

[0061] The present invention will be specifically described below in conjunction with the accompanying drawings and embodiments.

[0062] Example 1: Figure 1-17 As shown, this embodiment is a UHV bushing, comprising a head structure 1, an outer insulation 2, a capacitor core 3, a current-carrying tube 4 and a tail structure 5, the upper end of the current-carrying tube 4 is electrically connected to the head structure 1, the lower end of the current-carrying tube 4 is electrically connected to the tail structure 5, the outer insulation 2 is coaxially sleeved on the outside of the current-carrying tube 4, the upper end of the outer insulation 2 is sealed with the head structure 1, the lower end of the outer insulation 2 is sealed with the tail structure 5, an annular space is formed between the inner wall of the outer insulation 2 and the outer wall of the current-carrying tube 4, the capacitor core 3 is sleeved outside the tube body of the current-carrying tube 4 and is located in the annular space, and there is a gap between the outer surface of the capacitor core 3 and the inner wall of the outer insulation 2 and is filled with insulating oil.

[0063] See also Figure 5-Figure 13 As shown, the capacitor core 3 includes a winding tube 31, several layers of insulating cable paper layers 32, several layers of short capacitor screen layers and several layers of long capacitor screen layers. The winding tube 31 is sleeved on the outside of the current-carrying tube 4. Several layers of insulating cable paper layers 32, several layers of short capacitor screen layers and several layers of long capacitor screen layers are alternately wound on the outer wall of the winding tube 31 from the inside to the outside, and a layer of insulating cable paper layer 32 is wound outside the long capacitor screen layer located on the outermost layer. Each insulating cable paper layer 32 includes an insulating cable paper layer 32, each long capacitor screen layer includes a long capacitor screen 34, and each short capacitor screen layer includes two staggered short capacitor screens 33. An insulating cable paper layer 32 is wound between two adjacent short capacitor screen layers, between two adjacent long capacitor screen layers, and between adjacent short capacitor screen layers and long capacitor screen layers. The two short capacitor screens 33 are wound on the outer walls of both ends of the inner insulating cable paper layer 32 with a certain gradient.

[0064] Along the length direction of the current-carrying tube 4 and the rolled tube 31, a plurality of through hole groups 1 and a plurality of through hole groups 2 are respectively and sequentially opened on the current-carrying tube 4 and the rolled tube 31, and the through holes 1 on two adjacent through hole groups 1 and the through holes 2 on two adjacent through hole groups 2 are arranged alternately with each other; through holes 3 are respectively opened on the long capacitor screen 34 and the short capacitor screen 33, and after being rolled according to a certain gradient, the through holes 3 on the long capacitor screen 34 and the short capacitor screen 33 are in a spiral shape that spreads outward with the current-carrying tube 4 as the center.

[0065] In actual application, the insulating cable paper layer 32, the short capacitor screen layer and the long capacitor screen layer can be directly rolled onto the current-carrying tube 4, and the rolling tube 31 can be omitted. The current-carrying tube 4 can realize the current-carrying function and the rolling function, which can effectively avoid the discharge phenomenon that occurs when using double guide tubes, and at the same time achieve the purpose of simplifying the structure, improving the ease of assembly and reducing production costs.

[0066] The number of layers of the insulating cable paper layer 32 in each group is at least 1 layer, the number of layers of the short capacitor screen 33 in each group is 1-3 layers, and the number of layers of the long capacitor screen layer in each group is 1-8 layers.

[0067] In this embodiment, the capacitor core 3 is designed with a long and short capacitor screen 33 and an equal margin concept, and the design concept is as follows:

[0068] The length of the long capacitive screen 34 is defined as , the short capacitive screen 33 length is defined as , ;

[0069] The gradient between capacitive screens is defined as , ;

[0070] The radius of the capacitive screen is defined as ;

[0071] The upper and lower letters in the definition have no actual meaning and are only used to distinguish the capacitive screens located at the upper end and the lower end, and n>1;

[0072] Two long capacitive screens 34, one short capacitive screen 33 on each side, the capacitive screen layout diagram and equivalent circuit diagram are shown in Fig.14 , Fig.15 As shown,

[0073] Two long capacitive screens 34, two short capacitive screens 33 on the upper and lower sides, the capacitive screen arrangement diagram and equivalent circuit diagram are shown in Fig.16 , Fig.17 As shown,

[0074] The capacitance between the two capacitive screens is calculated as:

[0075] ,

[0076] In the formula is the relative dielectric constant, is the dielectric constant of vacuum;

[0077] The radial electric field between the two capacitive screens is calculated as:

[0078] ,

[0079] In the formula is the voltage division of each layer of capacitive screen;

[0080] Through the equivalent circuit diagram, according to the capacitance voltage division principle, the voltage division of each layer of the long capacitance screen 34 and the short capacitance screen 33 can be calculated;

[0081] The axial electric field between the two capacitive screens is calculated as:

[0082] ,

[0083] The partial discharge starting voltage at the edge of each layer of capacitive screen is calculated as:

[0084] ,

[0085] The partial discharge starting voltage margin of each layer of capacitor screen is:

[0086] ,

[0087] By adjusting the layer thickness, gradient and length of the capacitor screen, the partial discharge starting voltage margin of each layer of the capacitor screen can be equal, that is, an equal margin capacitor core can be obtained.

[0088] See also Figure 2 As shown, the external insulation 2 includes an upper porcelain sleeve 21, a sleeve flange 24 and a lower porcelain sleeve 23 connected in sequence from top to bottom, the upper end of the upper porcelain sleeve 21 is sealedly connected to the head structure 1, the lower end of the upper porcelain sleeve 21 is flange-connected to the upper end of the sleeve flange 24, the lower end of the sleeve flange 24 is sealedly connected to the upper end of the lower porcelain sleeve 23, and the lower end of the lower porcelain sleeve 23 is sealedly connected to the tail structure 5.

[0089] See also Figure 3 As shown, the head structure 1 includes an oil pillow 11, an upper terminal block 12 and a spring clamping device. The oil pillow 11 is a cylindrical structure which is closed at the top and bottom and hollow inside. The lower end of the oil pillow 11 is fixedly arranged in the upper end sleeve of the upper porcelain sleeve 21, and a conductive sealing head 13 is arranged at the upper end of the oil pillow 11. The conductive sealing head 13 is detachably connected to the oil pillow 11. Through holes for the upper end of the current-carrying tube 4 to pass through are correspondingly opened at the upper and lower ends of the oil pillow 11 and the conductive sealing head 13. The current-carrying tube 4 is sequentially inserted through the corresponding two through holes on the oil pillow 11 and the through hole on the conductive sealing head 13 from bottom to top and extends to above the upper end of the oil pillow 11. A sealing ring for sealing is arranged between the current-carrying tube 4 and the through hole, and the upper terminal block 12 is arranged at the upper end of the current-carrying tube 4.

[0090] The spring clamping device includes a support ring 14 which is sleeved on the current-carrying tube 4 located in the oil pillow 11 and fixedly connected to the lower end of the oil pillow 11, a plurality of springs 15, and a pressure plate 16 which is fixedly arranged on the tube body of the current-carrying tube 4 located in the oil pillow 11 and above the support ring 14. The plurality of springs 15 are evenly spaced along the circumference of the current-carrying tube 4 and are positioned above the support ring 14 through positioning columns 17 which are fixedly connected to the support ring 14 at their bottom ends. Several positioning columns 17 are inserted through the pressure plate 16. The plurality of springs 15 are sleeved on the positioning columns 17 between the pressure plate 16 and the support ring 14 in a compressed state.

[0091] In actual application, a positioning screw hole is provided on the support ring 14 for the bottom of the positioning column 17 to be screwed into. First, the spring 15 is placed on the support ring 14, and then the pressure plate 16 is screwed on the current-carrying tube 4 to press down on the spring 15, so that the spring 15 is in a compressed state, and then the positioning column 17 is inserted through the through hole on the pressure plate 16 and the bottom end of the positioning column 17 is screwed into the positioning screw hole on the support ring 14.

[0092] An oil filling port is provided on one side of the oil pillow 11, and insulating oil is injected into the oil pillow 11 through the oil filling port. Oil holes are provided on the support ring 14 and the lower end of the oil pillow 11 to allow the insulating oil to flow into the annular space.

[0093] See also Figure 3 As shown, the head structure 1 also includes a pressure equalizing ring 18, which includes two first ring bodies 19 symmetrically arranged at the upper end and the lower end and two second ring bodies 110 symmetrically arranged between the two first ring bodies 19, the inner diameter of the first ring body 19 is smaller than the inner diameter of the second ring body 110, and a plurality of first connecting tubes 111 are arranged between adjacent first ring bodies 19 and second ring bodies 110 and between two adjacent second ring bodies 110, and a plurality of second connecting tubes 112 are vertically arranged between the two first ring bodies 19.

[0094] The pressure-equalizing ring 18 is sleeved on the outside of the oil pillow 11, and a fixed cover 113 with an inverted convex structure and covering the top of the oil pillow 11 is fixedly arranged on the conductive sealing head 13. A through hole for the conductive sealing head 13 to pass through is also opened on the top of the fixed cover 113. Fixed rods 114 fixedly connected to the corresponding side fixed covers 113 are respectively arranged on the first connecting tube 111 between the two second ring bodies 110 and on the first connecting tube 111 between the first ring body 19 at the upper end and the second ring body 110; the setting of the pressure-equalizing ring 18 can effectively reduce the field strength of the head structure 1.

[0095] The above-mentioned arrangement of the pressure equalizing ring 18 and the fixed cover 113 is only a preferred embodiment of the present invention. Those skilled in the art may also select a fixed cover 113 and a pressure equalizing ring 18 with other structures, and the present invention is not limited thereto.

[0096] join Figure 4As shown, the tail structure 5 includes a base current-carrying disk 51 with a convex structure and a vertical hole, a wiring base 52 arranged at the lower end of the base current-carrying disk 51, and a lower wiring board 53 arranged at the lower end of the wiring base 52. The inner diameter of the vertical hole in the small diameter section at the upper end of the base current-carrying disk 51 is larger than the inner diameter of the vertical hole in the large diameter section at the lower end of the base current-carrying disk 51. The small diameter section at the upper end of the base current-carrying disk 51 is fixedly embedded in the lower end sleeve opening of the lower porcelain sleeve 23, and the upper end surface of the large diameter section at the lower end of the base current-carrying disk 51 abuts against the lower end port of the lower porcelain sleeve 23. The lower end of the lower porcelain sleeve 23 The opening and the base current-carrying disk 51 can be in abutment contact with each other, and a sealing ring is arranged on the contact surface to achieve a sealing effect. The lower end of the rolled tube 31 is inserted into the vertical hole on the small diameter section at the upper end of the base current-carrying disk 51 and fits against the inner wall of the vertical hole. The current-carrying tube 4 passes through the small diameter section and the vertical holes in the large diameter section of the base current-carrying disk 51 from top to bottom and extends to the wiring base 52 at the lower end of the base current-carrying disk 51 and abuts against the inner wall of the wiring base 52. A sealing ring for sealing is also arranged between the current-carrying tube 4 and the vertical hole in the large diameter section at the lower end of the base current-carrying disk 51.

[0097] The connection methods between the head structure 1, the tail structure 5 and the external insulation 2 are not limited to the above-mentioned connection methods. Those skilled in the art may also choose other connection methods as long as the sealed connection required by the present invention can be achieved. The specific structures of the components not described in detail in the present invention are all common structures in the prior art and will not be repeated here.

[0098] The UHV bushing structure provided by the present invention adopts a long-short screen design concept for the capacitor screen, which can reduce the amount of aluminum foil used, shorten the process cycle, and reduce the overall manufacturing cost of the bushing; the capacitor screen is punched, and the rolled tube 31 and the current-carrying tube 4 are cross-punched, which can reduce energy consumption and reduce costs in the vacuum drying process and oil immersion process of the UHV bushing.

[0099] Embodiment 2: Based on the UHV bushing structure in Embodiment 1, this embodiment further discloses a method for manufacturing the UHV bushing, comprising the following steps:

[0100] Step 1: Pretreatment: Cut the insulating cable paper according to size and then dry the paper roll;

[0101] The current-carrying tube 4 and the rolled tube 31 are punched, and the position, size, orientation and spacing of the holes are obtained through fluid temperature field simulation. The transformer oil flow channel inside the UHV bushing is simulated through fluid temperature field simulation. The influence of heat conduction, heat convection and heat radiation is considered, and simulation calculation is performed according to the actual operation of the bushing to obtain the optimal punching parameters on the current-carrying tube 4 and the rolled tube 31;

[0102] Punch holes in the long capacitive screen 34 and the short capacitive screen 33 using a fully automatic capacitive screen punching machine to control the size and position of the holes;

[0103] Step 2: Clean rolling: Wipe and fix the rolling tube 31 to the capacitor core 3 rolling machine, and then roll the insulating cable paper, long capacitor screen 34, and short capacitor screen 33 onto the rolling tube 31 in sequence according to the structure of the capacitor core 3. When rolling the long capacitor screen 34 and the short capacitor screen 33, it is necessary to avoid the upper and lower screen holes facing each other. When designing, simulate the gradient of the rolled capacitor screen, the starting angle of rolling, and the punching position on the capacitor screen in advance, and then import the data into the fully automatic capacitor core 3 rolling machine. Through the fully automated equipment, the gradient of the capacitor screen, the starting angle of the capacitor screen rolling, and the punching position on the capacitor screen are precisely controlled, and then the upper and lower screen holes are staggered;

[0104] Step 3: Vacuum drying of the capacitor core 3: The rolled capacitor core 3 is transferred to a vacuum drying tank for vacuum drying;

[0105] Step 4: Vertical assembly: Assemble the components of the UHV bushing according to the product structure;

[0106] Step 5: Vacuum pressure oil immersion: The assembled UHV bushing is transferred to the vacuum pressure oil immersion equipment for vacuum pressure oil immersion treatment;

[0107] Step 6: Post-processing: The UHV bushings after vacuum pressure oil immersion treatment are inspected, packaged and re-inspected in sequence. After passing the re-inspection, they can be put into storage and wait for delivery.

[0108] The specific method for treating the capacitor core 3 transported to the vacuum drying tank during the vacuum drying of the capacitor core 3 in step 3 is as follows:

[0109] Step 1: High temperature drying treatment under normal pressure: the temperature in the tank is set to 100°C and the heating time is 12h;

[0110] Step 2: High-temperature drying treatment by pressure-variable method: The temperature in the tank is set to 105°C, and the tank is evacuated and broken in cycles. Each evacuation is ≤1000Pa, and the heating time for each evacuation is 4 hours. The total time for high-temperature drying treatment by pressure-variable method is 200 hours.

[0111] Step 3: Low vacuum and high temperature drying: vacuum degree ≤ 140Pa, the temperature in the tank is set to 115℃, and the heating time is 50h;

[0112] Step 4: High vacuum and high temperature drying: vacuum degree ≤ 2Pa, the temperature in the tank is set to 115℃, and the heating time is 110h;

[0113] Step 5: Vacuum cooling: vacuum degree ≤ 2Pa, the temperature inside the tank drops to 50°C;

[0114] Step 6: Break the vacuum tank and take it out: Break the vacuum tank, lift the capacitor core 3 out of the vacuum tank, and then put it into the assembly workshop.

[0115] Step 5: During the vacuum drying of the capacitor core 3, the specific method for vacuum pressure oil immersion treatment of the capacitor core 3 transported to the vacuum pressure oil immersion equipment is as follows:

[0116] Step 1: Connect the hose on the oil-immersed pipeline to the oil pillow 11 of the casing head structure 1 and the oil filling port on the base current-carrying plate 51 of the tail structure 5 to check the casing for leaks;

[0117] Step 2: After the casing leak detection is completed, heat the drying room and keep the temperature at 75°C;

[0118] Step 3: Evacuate the casing to a vacuum degree of ≤2Pa for 200h;

[0119] Step 4: Circulate the casing to evacuate and oil it, with the vacuum degree of each evacuation ≤2Pa, and maintain it for 30 hours, with a total time of 180 hours;

[0120] Step 5: Pressure impregnation: Apply oil pressure of 0.3MPa to the inside of the casing, keep the oil temperature at 75℃, and the impregnation time is 330h;

[0121] Step 6: Start the pipeline oil circulation, the circulation time is 10 hours;

[0122] Step 7: Cool down and evacuate the air. The temperature drops to 30℃ and the evacuation time is 50h.

[0123] Since the capacitor screen is perforated, the winding tube 31 and the current-carrying tube 4 are cross-perforated, the cable paper near the current-carrying tube 4 can form convection with the inner side of the current-carrying tube 4 through the pores, and the water vapor evaporation channel can be increased when the capacitor core 3 is dried, thereby accelerating the evaporation rate of the cable paper; and the vacuuming and oil immersion can be more sufficient, which can shorten the vacuuming time, improve the speed and efficiency of oil immersion, shorten the process cycle, and reduce energy consumption and cost; the use of clean rolling, vacuum drying, vertical assembly, vacuum pressure oil immersion and other process technologies can also ensure the stability of the electrical performance of the bushing; in actual applications, the above ultra-high voltage bushing structure and manufacturing method are adopted, the bushing cost is saved by about 1 / 5, and the process cycle is shortened by about 1 / 3.

[0124] The above is only a preferred implementation of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. A UHV bushing, comprising a head structure, an outer insulation, a capacitor core, a current-carrying tube and a tail structure, wherein the upper end of the current-carrying tube is electrically connected to the head structure, the lower end of the current-carrying tube is electrically connected to the tail structure, the outer insulation is coaxially sleeved on the outside of the current-carrying tube, the upper end of the outer insulation is sealed and connected to the head structure, the lower end of the outer insulation is sealed and connected to the tail structure, an annular space is formed between the inner wall of the outer insulation and the outer wall of the current-carrying tube, the capacitor core is sleeved outside the current-carrying tube body and is located in the annular space, a gap is provided between the outer surface of the capacitor core and the inner wall of the outer insulation and is filled with insulating oil, and the bushing is characterized in that: The capacitor core comprises a rolled tube, several groups of insulating cable paper layers, several groups of short capacitor screen layers and several groups of long capacitor screen layers. The rolled tube is sleeved on the outside of the current-carrying tube body. Several groups of insulating cable paper layers, several groups of short capacitor screen layers and several groups of long capacitor screen layers are alternately wound on the outer wall of the rolled tube from inside to outside, and a layer of insulating cable paper layer is wound outside the long capacitor screen layer located at the outermost layer. Each long capacitor screen layer comprises a long capacitor screen, and each short capacitor screen layer comprises two staggered short capacitor screens. An insulating cable paper layer is wound between two adjacent short capacitor screen layers, between two adjacent long capacitor screen layers and between adjacent short capacitor screen layers and long capacitor screen layers. Two short capacitor screens are wound on the outer walls of both ends of the inner insulating cable paper layer with a certain gradient. Along the length direction of the current-carrying tube and the rolled tube, a plurality of through hole groups 1 and a plurality of through hole groups 2 are respectively and sequentially opened on the current-carrying tube and the rolled tube, and the through holes 1 on two adjacent through hole groups 1 and the through holes 2 on two adjacent through hole groups 2 are staggered with each other; through holes 3 are respectively opened on the long capacitor screen and the short capacitor screen, and after rolling, the through holes 3 on the long capacitor screen and the short capacitor screen are in a spiral shape that spreads outward with the current-carrying tube as the center.

2. The UHV bushing according to claim 1, characterized in that: The number of layers of the insulating cable paper layer in each layer group is at least 1 layer, the number of layers of the short capacitor screen in each layer group is 1-3 layers, and the number of layers of the long capacitor screen in each layer group is 1-8 layers.

3. The UHV bushing according to claim 1, characterized in that: The external insulation includes an upper porcelain sleeve, a sleeve flange and a lower porcelain sleeve connected in sequence from top to bottom, the upper end of the upper porcelain sleeve is sealed connected to the head structure, the lower end of the upper porcelain sleeve is connected to the upper end flange of the sleeve flange, the lower end of the sleeve flange is sealed connected to the upper end of the lower porcelain sleeve, and the lower end of the lower porcelain sleeve is sealed connected to the tail structure.

4. The UHV bushing according to claim 3, characterized in that: The head structure includes an oil pillow, an upper terminal block and a spring clamping device. The oil pillow is a cylindrical structure that is closed at the top and bottom and hollow inside. The lower end of the oil pillow is fixedly arranged in the upper end sleeve of the upper porcelain sleeve. A conductive sealing head is arranged at the upper end of the oil pillow. Through holes for the upper end of the current-carrying tube to pass through are correspondingly opened at the upper and lower ends of the oil pillow and the conductive sealing head. The current-carrying tube passes through the corresponding two through holes on the oil pillow and the through hole on the conductive sealing head from bottom to top and extends to the upper end of the oil pillow. A sealing ring for sealing is arranged between the current-carrying tube and the conductive sealing head. The upper terminal block is arranged at the upper end of the current-carrying tube. The spring clamping device includes a support ring sleeved on the current-carrying tube located in the oil pillow and fixedly connected to the lower end of the oil pillow, a plurality of springs, and a pressure plate fixedly arranged on the tube body of the current-carrying tube located in the oil pillow and above the support ring. The plurality of springs are evenly spaced and arranged along the circumference of the current-carrying tube and are respectively positioned above the support ring through positioning columns fixedly connected to the support ring at the bottom ends. Several positioning columns are inserted through the pressure plate. The plurality of springs are sleeved on the positioning columns between the pressure plate and the support ring in a compressed state. An oil filling port is provided on one side of the oil pillow, and insulating oil is injected into the oil pillow through the oil filling port.

5. The UHV bushing according to claim 4, characterized in that: The head structure also includes a pressure equalizing ring, which includes two first ring bodies symmetrically arranged at the upper end and the lower end and two second ring bodies symmetrically arranged between the two first ring bodies, the inner diameter of the first ring body is smaller than the inner diameter of the second ring body, a plurality of first connecting tubes are arranged between adjacent first ring bodies and second ring bodies and between two adjacent second ring bodies, and a plurality of second connecting tubes are vertically arranged between the two first ring bodies; The pressure equalizing ring sleeve is arranged outside the oil pillow, a fixed cover is arranged on the conductive sealing head, and fixing rods fixedly connected to the corresponding side fixed covers are respectively arranged on the first connecting tube between the two second ring bodies and on the first connecting tube between the first ring body and the second ring body at the upper end.

6. The UHV bushing according to claim 3, characterized in that: The tail structure includes a base current-carrying disk with a convex structure and a vertical hole, a wiring base arranged at the lower end of the base current-carrying disk, and a lower wiring board arranged at the lower end of the wiring base. The inner diameter of the vertical hole in the small diameter section of the upper end of the base current-carrying disk is larger than the inner diameter of the vertical hole in the large diameter section of the lower end of the base current-carrying disk. The small diameter section of the upper end of the base current-carrying disk is fixedly embedded in the lower end sleeve of the lower porcelain sleeve, and the upper end surface of the large diameter section of the lower end of the base current-carrying disk abuts against the lower end of the lower porcelain sleeve. The lower end of the rolled tube is inserted into the vertical hole on the small diameter section of the upper end of the base current-carrying disk and fits with the inner wall of the vertical hole. The current-carrying tube is inserted through the small diameter section and the vertical hole in the large diameter section of the base current-carrying disk from top to bottom in sequence and extends to the wiring base at the lower end of the base current-carrying disk. A sealing ring for sealing is also provided between the current-carrying tube and the vertical hole in the large diameter section of the lower end of the base current-carrying disk.

7. A method for manufacturing an ultra-high voltage bushing according to claim 1, characterized in that: The steps include: Step 1: Pretreatment: Cut the insulating cable paper according to the size, and then dry the paper reel; punch holes in the current-carrying tube and the coiled tube, and the position, size, orientation and spacing of the holes are obtained through fluid temperature field simulation; punch holes in the long capacitor screen and the short capacitor screen, and use a fully automatic capacitor screen punching machine to control the size and position of the holes; Step 2: Clean rolling: Wipe and fix the rolling tube to the capacitor core rolling machine, and then roll the insulating cable paper, long capacitor screen, and short capacitor screen onto the rolling tube in sequence according to the capacitor core structure. By controlling the gradient of each screen, the starting angle of the capacitor screen rolling, and the punching position on the capacitor screen, the upper and lower screen holes are staggered; Step 3: Vacuum drying of capacitor core: the rolled capacitor core is transferred to a vacuum drying tank for vacuum drying; Step 4: Vertical assembly: Assemble the components of the UHV bushing according to the product structure; Step 5: Vacuum pressure oil immersion: The assembled UHV bushing is transferred to the vacuum pressure oil immersion equipment for vacuum pressure oil immersion treatment; Step 6: Post-processing: The UHV bushings after vacuum pressure oil immersion treatment are inspected, packaged and re-inspected in sequence. After passing the re-inspection, they can be put into storage and wait for delivery.

8. The method for manufacturing an ultra-high voltage bushing according to claim 7, characterized in that: The specific method for treating the capacitor core transported to the vacuum drying tank in the step 3 of vacuum drying the capacitor core is: Step 1: High temperature drying treatment under normal pressure: the temperature in the tank is set to 100°C and the heating time is 12h; Step 2: High-temperature drying treatment by pressure-variable method: The temperature in the tank is set to 105°C, and the tank is evacuated and broken in cycles. Each evacuation is ≤1000Pa, and the heating time for each evacuation is 4 hours. The total time for high-temperature drying treatment by pressure-variable method is 200 hours. Step 3: Low vacuum and high temperature drying: vacuum degree ≤ 140Pa, the temperature in the tank is set to 115℃, and the heating time is 50h; Step 4: High vacuum and high temperature drying: vacuum degree ≤ 2Pa, the temperature in the tank is set to 115℃, and the heating time is 110h; Step 5: Vacuum cooling: vacuum degree ≤ 2Pa, the temperature inside the tank drops to 50°C; Step 6: Break the vacuum tank and take it out: Break the vacuum tank, lift the capacitor core out of the vacuum tank, and then load it into the assembly workshop.

9. The method for manufacturing an ultra-high voltage bushing according to claim 7, characterized in that: The specific method of vacuum pressure oil immersion treatment of the capacitor core after vacuum drying in step 5 and transporting it to the vacuum pressure oil immersion equipment is as follows: Step 1: Connect the hose on the oil-immersed pipeline to the oil filling ports of the casing head structure and tail structure, and perform leak detection on the casing; Step 2: After the casing leak detection is completed, heat the drying room and keep the temperature at 75°C; Step 3: Evacuate the casing to a vacuum degree of ≤2Pa for 200h; Step 4: Circulate the casing to evacuate and oil it, with the vacuum degree of each evacuation ≤2Pa, and maintain it for 30 hours, with a total time of 180 hours; Step 5: Pressure impregnation: Apply oil pressure of 0.3MPa to the inside of the casing, keep the oil temperature at 75℃, and the impregnation time is 330h; Step 6: Start the pipeline oil circulation, the circulation time is 10 hours; Step 7: Cool down and evacuate the air. The temperature drops to 30℃ and the evacuation time is 50h.

Images