Ultra-large-capacity dry-type transformer with variable load

Abstract

The invention discloses a load-variable ultra-large-capacity dry-type transformer, and relates to the technical field of dry-type transformers, the load-variable ultra-large-capacity dry-type transformer comprises three groups of main iron core columns and three groups of auxiliary iron core columns, the section of each main iron core column is in a stepped shape, and three layers of amorphous alloy belts are laminated in each main iron core column; the thickness of the middle layer of the three layers of amorphous alloy belts is set to be 1.2-1.5 times that of the two side layers, and independent lap joint pieces are arranged at the joints of the lamination sets in the auxiliary iron core column. The stepped sections of the three groups of main iron core columns are combined with the magnet yokes with thin tops and thick bottoms, so that the magnetic flux density is uniformly distributed, the capacity of a single column is improved, the problems that the capacity of a single traditional dry-type transformer is limited and the whole transformer needs to be replaced during capacity expansion are solved, the occupied area is reduced through modular splicing, the capacity of a single group of iron core columns is increased, and the no-load loss is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of dry-type transformers, and specifically to an extra-large-capacity dry-type transformer with variable load. Background Art

[0002] In recent years, with the accelerated construction of smart cities and new power systems, the application depth of high-reliability dry-type transformers in fields such as rail transit, new energy grid connection, and data centers has been continuously expanding. These scenarios pose stringent requirements for equipment in terms of high voltage levels, extra-large rated powers, and wide load regulation ranges. However, they have exposed the inherent contradictions of traditional dry-type transformers - the winding eddy current loss increases exponentially with the increase in voltage, the DC resistance loss under dynamic load fluctuates, exacerbating local hot spot aggregation, and the thermal resistance bottleneck of air cooling leads to over-temperature rise, threatening the insulation life.

[0003] Therefore, it is very necessary for this application to propose an extra-large-capacity dry-type transformer with variable load to solve the problems in the background.

[0004] Patent CN115985632B discloses a cold-resistant large-capacity dry-type transformer. The above patent realizes the synchronous rotation of two threaded rods, and then drives the synchronous movement of two threaded sleeves, so as to adjust the height of the inner shell, and can adjust the staggering situation of the first ventilation opening and the second ventilation opening, playing the roles of ventilation, sealing, heat insulation, and heat preservation.

[0005] The above patent realizes the functions of ventilation, sealing, heat insulation, and heat preservation by staggering and adjusting the first ventilation opening and the second ventilation opening provided on both sides of the outer shell. However, under the condition of extra-large capacity, the dynamic load will drive the fluctuation of DC resistance loss, which in turn causes local hot spot aggregation.

[0006] For this reason, this application proposes an extra-large-capacity dry-type transformer with variable load that can realize the formation of a closed loop of flux homogenization by combining stepped amorphous alloy laminations with a thin top and a thick bottom yoke, breaking through the single-unit capacity limit of traditional dry-type transformers, and the cross-shaped copper busbars and ring-shaped finger interfaces between modules support hot pluggable "plug and play". Summary of the Invention

[0007] The purpose of the present invention is to provide an extra-large-capacity dry-type transformer with variable load to solve the technical problems raised in the above background art, namely, the winding eddy current loss increases exponentially with the increase in voltage, the DC resistance loss under dynamic load fluctuates, exacerbating local hot spot aggregation, and the thermal resistance bottleneck of air cooling leads to over-temperature rise, threatening the insulation life.

[0008] To achieve the above object, the present invention provides the following technical solution: A super-large-capacity dry-type transformer with variable load, including three groups of main iron core columns and three groups of auxiliary iron core columns. At the top and bottom of the outer walls of the main iron core columns and the auxiliary iron core columns, magnetic yokes are fixedly installed respectively, and the magnetic yokes are connected to form a closed-loop magnetic circuit; The cross-section of the main iron core column is set in a stepped shape. The inside of the main iron core column is laminated by three layers of amorphous alloy strips. The thickness of the middle layer of the three layers of amorphous alloy strips is set to be 1.2 to 1.5 times that of the two side layers. An independent overlapping sheet is provided at the joint of the laminated sheet group inside the auxiliary iron core column. The overlapping gap between the overlapping sheet and the laminated sheet group is filled with iron-based nanocrystals. The top thickness of the magnetic yoke is 10 mm less than the bottom thickness. The joint surface between the magnetic yoke and the iron core column is coated with epoxy resin adhesive.

[0009] Preferably, a high-voltage winding and a low-voltage winding are sleeved on the outer wall of the iron core column. The high-voltage winding is composed of N parallel sub-windings. Each sub-winding is composed of a copper foil conductor and a stranded wire. Multiple stranded wires are wound around the outer wall of the copper foil conductor. The copper foil conductor and the stranded wire are bonded through a semi-conductive silicone rubber layer. The width of the copper foil conductor is set to be 60% to 80% of the axial length of the high-voltage winding. The stranding pitch between the stranded wires is set to be 2 to 3 times the diameter of a single wire; The low-voltage winding is divided into three sections, namely L1, L2, and L3. The three sections of windings are respectively wound in layers on the outer wall of the iron core column. The start and end terminals of the three sections of windings are respectively connected to both ends of a magnetically controlled vacuum circuit breaker. The magnetically controlled coils of the magnetically controlled vacuum circuit breakers connected to each section are connected to a decoder through control lines. The connection between the magnetically controlled vacuum circuit breaker and the winding conductor is coated with a boron nitride ceramic insulating layer. The boron nitride ceramic insulating layer is provided with a wire passing hole for the control line. The cross-sectional area of the L1 section conductor is 1.5 - 2 times that of the L3 section. The L2 section conductor uses a trapezoidal copper bar with a gradually changing cross-section. An epoxy glass cloth transition layer is provided between the layers of the three sections of windings. Axial heat dissipation channels are opened on the outer surface of the transition layer. A semiconductor refrigeration sheet is embedded in the heat dissipation channels. The cold end of the semiconductor refrigeration sheet is attached to and extends to the contact area of the magnetically controlled vacuum circuit breaker.

[0010] Preferably, the main body of the boron nitride ceramic insulating layer is composed of a modified silicone rubber matrix, and boron nitride nanosheets and silicon carbide fibers with a mass fraction of 5% - 8% are uniformly distributed in the matrix; An annular heat dissipation air duct is provided on the outer walls of the high-voltage winding and the low-voltage winding. A porous ceramic coating is sprayed on the inner wall of the annular heat dissipation air duct. The porosity of the porous ceramic coating is set to be 40% - 60%. The annular heat dissipation air duct is connected to a centrifugal fan through an integrated annular bracket. A gear ring is fixedly installed on the inner side surface of the integrated annular bracket. A gear meshes with the gear ring inside. The gear is coaxially fixedly installed with a rotating shaft. The other end of the rotating shaft is fixedly connected to the tail end of a guide vane. The guide vanes are circumferentially distributed and the inclination angle is 15° - 45°. A temperature rise probe is embedded in the inner wall of the annular heat dissipation air duct. The temperature rise probe is connected to a controller through a twisted pair.

[0011] Preferably, a magnetic conduction partition is arranged between the iron core column and the winding. The magnetic conduction partition is formed by alternately laminating amorphous alloy strips and insulating paper, and the lamination ratio is set to 1:3; The inner layer of the surface of the iron core column is coated with an epoxy resin-based ferrite coating, and the outer surface of the epoxy resin-based ferrite coating is coated with a graphene-modified silicone rubber coating.

[0012] Preferably, a passive LC resonance sensor is embedded at the node of the high-voltage winding and the low-voltage winding. The passive LC resonance sensor includes an amorphous thin strip and a polyimide thin film. The amorphous thin strip is attached to the outer surface of the conductors of the high-voltage winding and the low-voltage winding, and the polyimide thin film covers the amorphous thin strip and is fixed on the inner surface of the boron nitride ceramic insulating layer; The passive LC resonance sensor is transmitted to an external monitoring module through a connected near-field coupling antenna. The coupling antenna is fixedly wound around the insulating brackets at the ends of the high-voltage winding and the low-voltage winding. The monitoring module is built-in with a thermal-mechanical coupling algorithm, and the thermal-mechanical coupling algorithm generates a three-dimensional temperature rise field and a deformation field distribution map. A spring finger is fixedly installed on the outer wall of the monitoring module, and the spring finger is connected to a magnetically controlled vacuum circuit breaker through a cable.

[0013] Preferably, a housing is arranged on the outer wall of the transformer body. The transformer body is composed of independent modules spliced together. The independent modules include M1 to Mn modules. Between the M1 module and the M2 module, a busbar trough is poured with epoxy resin for parallel expansion. Conductors are fixedly installed on the inner wall of the busbar trough. The conductors in the busbar trough are formed by stacking laminations in multiple layers. A positioning pin is fixedly installed on the splicing surface between the M1 module and the M2 module. A sealing strip is fixedly attached to the outer wall of the positioning pin. A port of the busbar trough at the splicing surface is connected to an overload protection unit; A branch of the busbar trough is connected to an M0 spare module. A disconnector is fixedly installed at the node between the M0 spare module and the branch of the busbar trough. The disconnector is connected to the overload protection unit through a cable. The overload protection unit integrates thermal accumulation integration, and the heat accumulation of the thermal accumulation integration is based on the continuous integration from the start of the load to the current time t.

[0014] Preferably, shock-absorbing mechanisms are fixedly installed at the bottom ends of the outer walls of the main iron core column and the auxiliary iron core column. The shock-absorbing mechanisms are arranged in two layers. The first layer is provided with damping rubber pads fixed to the bases of the main iron core column and the auxiliary iron core column by bolts. The second layer is provided with elastic bodies. Elastic bodies are fixedly installed at the bottom ends of the outer walls of the damping rubber pads. Electromagnetic coils are wrapped inside the elastic bodies. Input ports are led out from the ends of the electromagnetic coils and connected to vibration sensors. The vibration sensors are embedded at the bottom of the damping rubber pads; Silencing rings are fixedly installed at the ends of the windings. Porous sound-absorbing cotton is filled inside the silencing rings. Each adjacent layer of silencing rings is communicated through Helmholtz resonators.

[0015] Preferably, the outer shell is provided with a double-layer structure. The inner layer is an aluminum alloy frame, and the grid of the aluminum alloy frame is embedded with insulating supports. The outer layer is a fluorocarbon resin coating. Ventilation holes are reserved at the bottom inside the aluminum alloy frame. The aluminum alloy frame is connected to a circulation pipeline through the ventilation holes, and dry nitrogen is introduced into the circulation pipeline. The outer wall of the aluminum alloy frame is fixedly installed with a composite board through a back-bolt structure. A diversion groove is reserved at the splicing joint of the composite board. The generator electrode is fixedly installed along the circumference of the inner wall of the outer shell. A plug-in sleeve is embedded on the left side of the composite board. The axis of the plug-in sleeve coincides with the center of the bus duct. A base is fixedly installed at the bottom end of the outer wall of the outer shell. Two parallel guide rails are opened at the bottom end of the outer wall of the base. A wireless charging coil is buried in the guide rail groove. A phased array acoustic probe is embedded at the end of the guide rail. The wireless charging coil couples the access coil of the phased array acoustic probe depending on the electromagnetic field in the air gap.

[0016] Preferably, a compensation wire group is wound around the outer wall of the auxiliary iron core column. A power electronic module is nested at the bottom of the auxiliary iron core column. A sub-box is fixedly installed on the side of the conductor where the low-voltage winding is located. A control module is embedded and installed in the inner wall of the sub-box through a guide rail buckle. The power electronic module is connected to the head end of the compensation wire group and is grounded at the same time. The input side of the power electronic module is connected to the neutral point tap at the bottom of the auxiliary iron core column through an insulated copper busbar. The control module is rigidly connected to the auxiliary iron core column through a corrugated pipe.

[0017] Preferably, an adjustable magnetic flux branch is provided between the main iron core column and the auxiliary iron core column. The adjustable magnetic flux branch is composed of a U-shaped magnetic conductor. The open ends of the U-shaped magnetic conductor are respectively connected to the side of the main iron core column and the top of the auxiliary iron core column through wedge-shaped joints. A permanent magnet array is embedded inside the U-shaped magnetic conductor. The N-S poles of the permanent magnet array are arranged alternately along the axial direction. The outer wall of the permanent magnet array is wrapped with a permalloy shielding layer. An adjusting rod is led out from the end of the shielding layer, and the adjusting rod extends to the side of the outer wall of the transformer outer shell.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By combining the stepped cross-sections of the three groups of main iron core columns with a yoke that is thin at the top and thick at the bottom, the present invention achieves a uniform distribution of magnetic flux density, increases the capacity of a single column, solves the problem that the capacity of a traditional dry-type transformer is limited for a single unit and the whole machine needs to be replaced for capacity expansion. The modular splicing reduces the occupied area, increases the capacity of a single group of iron core columns, and reduces the no-load loss. 2. By simultaneously connecting the low-voltage winding composed of three conductors in different states of L1-L3 to the circuit breaker, the present invention realizes the dynamic switching of winding combinations to adjust the load, solves the problem that the load adjustment of a dry-type transformer depends on mechanical tap changers, has a slow response and is prone to generate electric arcs, and meets the requirements of power grid fluctuations and new energy grid connection. 3. The present invention embeds porous ceramic coatings in the heat dissipation duct and links adjustable guide vanes to achieve that when the centrifugal fan drives the airflow, the porous ceramics enhance turbulent heat exchange, the semiconductor refrigeration sheet directionally cools the hot spot area, and the phase change material absorbs transient heat, thereby solving the problem of insulation aging caused by local temperature rise under ultra-large capacity and insufficient efficiency of traditional air cooling, and extending the life cycle of the transformer; 4. The present invention realizes the suppression of electromagnetic interference between modules by connecting independent modules in parallel with epoxy resin cast bus duct, solves the problem that the transformer needs to be replaced as a whole for capacity expansion and the electromagnetic compatibility is poor, the capacity expansion means is "plug and play" and the capacity expansion effect is doubled. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a front view structural schematic diagram of the present invention; Figure 2 It is a schematic diagram of the front structure of the present invention; Figure 3 It is a schematic diagram of the heat dissipation duct structure of the present invention; Figure 4 It is a schematic diagram of the structure of the monitoring module of the present invention; Figure 5 It is a schematic diagram of the high voltage winding structure of the present invention; Figure 6 It is a schematic diagram of the structure of the shock absorbing mechanism of the present invention; Figure 7 It is a schematic diagram of the structure of the boron nitride ceramic insulation layer of the present invention; Figure 8 It is a schematic diagram of the structure of the magnetic conductive partition of the present invention.

[0020] In the figure: 1. Main iron core column; 2. Auxiliary iron core column; 3. Magnetic yoke; 4. Lap; 5. High-voltage winding; 6. Copper foil conductor; 7. Stranded wire; 8. Semi-conductive silicone rubber layer; 9. Low-voltage winding; 10. Magnetron vacuum circuit breaker; 11. Boron nitride ceramic insulation layer; 12. Boron nitride nanosheets; 13. Silicon carbide fiber; 14. Annular heat dissipation duct; 15. Guide vane; 16. Integrated annular bracket; 17. Rotating shaft; 18. Gear ring; 19. Magnetic partition; 20. Amorphous alloy Gold tape; 21. Insulating paper; 22. Passive LC resonant sensor; 23. Monitoring module; 24. Spring contact finger; 25. Bus duct; 26. Disconnector; 27. Overload protection unit; 28. Shock absorption mechanism; 29. ​​Damping rubber pad; 30. Elastomer; 31. Silence ring; 32. Housing; 33. Aluminum alloy frame; 34. Generator electrode; 35. Base; 36. Power electronic module; 37. Sub-box; 38. Adjustable flux branch; 39. Adjustment rod; 40. Heat dissipation channel. DETAILED DESCRIPTION

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "backend", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0024] Please refer to Figure 1 、 Figure 2 and Figure 3 , an embodiment provided by the present invention: a super-large-capacity dry-type transformer with variable load, including three groups of main iron core columns 1 and three groups of auxiliary iron core columns 2. Magnetic yokes 3 are fixedly installed at the top and bottom of the outer walls of the main iron core columns 1 and the auxiliary iron core columns 2, and the magnetic yokes 3 are connected to form a closed magnetic circuit; the cross-section of the main iron core column 1 is set in a stepped shape, and the inside of the main iron core column 1 is laminated by three layers of amorphous alloy tapes 20. The thickness of the middle layer of the three layers of amorphous alloy tapes 20 is set to be 1.2 to 1.5 times that of the two side layers. Independent overlapping pieces 4 are arranged at the joints of the laminated core groups inside the auxiliary iron core columns 2, and the overlapping gaps between the overlapping pieces 4 and the laminated core groups are filled with iron-based nanocrystals. The top thickness of the magnetic yoke 3 is 10 mm less than the bottom thickness, and the joint surface between the magnetic yoke 3 and the iron core column is coated with epoxy resin adhesive; A magnetic conduction partition 19 is arranged between the iron core column and the winding. The magnetic conduction partition 19 is alternately laminated with amorphous alloy tapes 20 and insulating paper 21, and the lamination ratio is set to 1:3; the inner layer of the iron core column surface is coated with an epoxy resin-based ferrite coating, and the outer surface of the epoxy resin-based ferrite coating is coated with a graphene-modified silicone rubber coating; Furthermore, firstly, the main core column 1 adopts a three-layer amorphous alloy strip 20 laminated structure, the thickness of the middle layer is 1.3 times that of the two side layers, when laminated, the middle layer is pre-bent 3° along the axial direction, and the lamination direction is inclined at 10° to the axis, the magnetic conductive partition 19 adopts amorphous alloy strip 20 and insulating paper 21 alternately laminated at a ratio of 1:3, and the edge of the amorphous strip is processed with a zigzag cut with a phase difference of 30°, the lamination group of the auxiliary core column 2 is embedded with an independent lap sheet 4 at the joint, and the lap gap is filled with iron-based nanocrystalline material, which improves the local magnetic permeability, the top thickness of the yoke 3 is 10 mm smaller than the bottom, forming a "narrow on top and wide on the bottom" yoke structure, the bottom thick layer bears the additional magnetic flux caused by the deadweight of the winding, the top thin layer reduces the no-load excitation loss, and the joint surface is coated with epoxy resin adhesive.

[0025] Then, a tap adjustment mechanism is installed on the top of the main core column 1. The tap adjustment mechanism includes a movable silicon steel sheet group and a servo push rod. The silicon steel sheet group is slidably nested in the top of the core column through a dovetail groove. The servo push rod drives its axial displacement through a ceramic connecting rod. The control line of the servo push rod passes through the metal conduit embedded in the yoke 3 and is led to the control box of the shell 32.

[0026] Finally, an expansion connection port is set at the bottom of the core column, the I-shaped magnetic conductor is inserted into the prefabricated groove at the bottom of the main core column, the horizontal section extends outward to form an expansion interface, and the π-shaped conductive row is clamped on both sides of the I-shaped magnetic conductor and fixed by an insulating clamp. When the magnetic flux density of the core column reaches 1.4T, the leakage magnetic field of the partition is reduced by 22% compared with the traditional lamination, and the axial leakage magnetic field distortion rate of the winding end is reduced by 18%.

[0027] See also Figure 1 , Figure 3 and Figure 4, an embodiment provided by the present invention: a super-large-capacity dry-type transformer with variable load. A high-voltage winding 5 and a low-voltage winding 9 are sleeved on the outer wall of the iron core column. The high-voltage winding 5 is composed of N parallel sub-windings. Each sub-winding is composed of a copper foil conductor 6 and a stranded wire 7. Multiple strands of stranded wire 7 are wound around the outer wall of the copper foil conductor 6. The copper foil conductor 6 and the stranded wire 7 are bonded through a semi-conductive silicone rubber layer 8. The width of the copper foil conductor 6 is set to be 60% - 80% of the axial length of the high-voltage winding 5. The stranding pitch between the stranded wires 7 is set to be 2 - 3 times the diameter of a single wire; the low-voltage winding 9 is divided into three sections, namely L1, L2, and L3. The three sections of windings are respectively wound in layers on the outer wall of the iron core column. The starting and ending ends of the three sections of windings are respectively connected to both ends of a magnetron vacuum circuit breaker 10. The magnetron coils of each magnetron vacuum circuit breaker 10 connected are connected to a decoder through a control line. The connection between the magnetron vacuum circuit breaker 10 and the winding conductor is coated with a boron nitride ceramic insulating layer 11. The boron nitride ceramic insulating layer 11 is provided with a threading hole position for the control line. The cross-sectional area of the L1 section conductor is 1.5 - 2 times that of the L3 section. The L2 section conductor adopts a trapezoidal copper bar with a gradually changing cross-section. An epoxy glass cloth transition layer is provided between the layers of the three sections of windings. Axial heat dissipation channels 40 are opened on the outer surface of the transition layer. A semiconductor refrigeration sheet is embedded in the heat dissipation channels 40. The cold end of the semiconductor refrigeration sheet is attached to and extends to the contact area of the magnetron vacuum circuit breaker 10; The main body of the boron nitride ceramic insulating layer 11 is composed of a modified silicone rubber matrix. Boron nitride nanosheets 12 and silicon carbide fibers 13 with a mass fraction of 5% - 8% are uniformly distributed in the matrix; an annular heat dissipation air duct 14 is provided on the outer walls of the high-voltage winding 5 and the low-voltage winding 9. A porous ceramic coating is sprayed on the inner wall of the annular heat dissipation air duct 14. The porosity of the porous ceramic coating is set to be 40% - 60%. The annular heat dissipation air duct 14 is connected to a centrifugal fan through an integrated annular bracket 16. A gear ring 18 is fixedly installed on the inner side surface of the inner wall of the integrated annular bracket 16. A gear is meshed inside the gear ring 18. The gear is coaxially fixedly installed with a rotating shaft 17. The other end of the rotating shaft 17 is fixedly connected to the tail end of a guide vane 15. The guide vanes 15 are circumferentially distributed and the inclination angle is 15° - 45°. A temperature rise probe is embedded in the inner wall of the annular heat dissipation air duct 14. The temperature rise probe is connected to a controller through a twisted pair; Further, first, the high-voltage winding 5 is composed of 4 parallel sub-windings. The width of the copper foil conductor 6 of each sub-winding is 70% of the axial length. Stranded wire 7 is wound around the outer wall. The stranding pitch is 2.5 times the diameter of a single wire. The copper foil and the stranded wire are bonded through a semi-conductive silicone rubber layer 8, reducing the high-frequency eddy current loss by 35%; Then, the low-voltage winding 9 is divided into three sections, namely L1, L2, and L3, and wound in layers. The cross-sectional area of the conductor in the L1 section is 1.8 times that of the L3 section. The L2 section uses a trapezoidal gradually changing cross-section copper bar. An epoxy glass cloth transition layer is provided between layers and an axial heat dissipation channel 40 is opened. A semiconductor refrigerating sheet is embedded, and the cold end extends to the contact area of the magnetron vacuum circuit breaker 10 to suppress the temperature rise. When the load rate of the L1 section exceeds 80%, the refrigerating sheet starts, the temperature difference ΔT≥15°C, and the contact temperature rise drops from 110°C to 85°C.

[0028] Finally, the ends of the three windings are connected to the magnetron vacuum circuit breaker 10. The magnetron coil of the magnetron vacuum circuit breaker 10 is controlled to be turned on and off through a decoder. The connection of the magnetron vacuum circuit breaker 10 is coated with a boron nitride ceramic insulation layer 11, and 6% boron nitride nanosheets 12 and silicon carbide fibers 13 are incorporated inside. The monitoring module 23 collects the winding temperature rise data in real time through the passive LC resonance sensor 22 and drives the magnetron vacuum circuit breaker 10 to dynamically switch the load.

[0029] Please refer to Figure 1 、 Figure 2 and Figure 7 As shown in and The housing 32 is provided with a double-layer structure. The inner layer is an aluminum alloy frame 33, and the grid of the aluminum alloy frame 33 is embedded with insulating supports. The outer layer is a fluorocarbon resin coating. Vent holes are reserved at the bottom inside the aluminum alloy frame 33. The aluminum alloy frame 33 is connected to a circulation pipeline through the vent holes, and dry nitrogen is introduced into the circulation pipeline. The outer wall of the aluminum alloy frame 33 is fixedly installed with a composite board through a back-bolt structure, and a diversion groove is reserved at the splicing joint of the composite board. The generator electrode 34 is fixedly installed along the circumference on the inner wall of the housing 32. Further, first, a porous ceramic coating with a porosity of 50% is sprayed on the inner wall of the annular heat dissipation air duct 14, and an external centrifugal fan is connected. A secondary cooling unit is added inside the annular heat dissipation air duct 14. The annular integrated bracket 16 is embedded with a gear ring 18 that meshes with a gear, and the driving shaft 17 drives the diversion vane 15 with an inclination angle of 30° to rotate, enhancing the air flow disturbance.

[0030] Then, the secondary cooling unit is composed of a honeycomb metal matrix and a phase change energy storage tube. The pores of the metal matrix are arranged at a 90° intersection with the diversion vane 15. The phase change energy storage tube is encapsulated with a paraffin-nano aluminum composite material, and needle-shaped heat dissipation fins are welded to the outer wall and extend into the main air duct. The phase change latent heat is used to absorb transient heat. In the 120°C overload test, the phase change latent heat absorption of the energy storage tube reduces the average temperature rise rate of the winding by 0.6°C / min, extending the overload time by 20 minutes compared with traditional air cooling.

[0031] Finally, the temperature rise probe is embedded in the inner wall of the air duct, and the rotation speed of the centrifugal fan and the inclination angle of the diversion vane 15 are adjusted through a controller; when the temperature exceeds the threshold value, the semiconductor refrigeration sheet starts in the heat dissipation channel 40, and the cold end directly cools the contacts of the magnetron vacuum circuit breaker 10, forming active-passive collaborative heat dissipation.

[0032] Please refer to Figure 1 、 Figure 6 and Figure 8 , an embodiment provided by the present invention: a super-large-capacity dry-type transformer with variable load. The bottom ends of the outer walls of the main iron core column 1 and the auxiliary iron core column 2 are fixedly installed with shock absorption mechanisms 28. The shock absorption mechanisms 28 are arranged in two layers. The first layer is provided with damping rubber pads 29 that are fixedly connected to the bases of the main iron core column 1 and the auxiliary iron core column 2 through bolts. The second layer is provided with elastic bodies 30. The elastic bodies 30 are fixedly installed at the bottom ends of the outer walls of the damping rubber pads 29. Electromagnetic coils are wrapped inside the elastic bodies 30, and input ports are led out from the ends of the electromagnetic coils and connected to vibration sensors. The vibration sensors are embedded at the bottom of the damping rubber pads 29; silencing rings 31 are fixedly installed at the ends of the windings, and porous sound-absorbing cotton is filled inside the silencing rings 31. Each adjacent layer of silencing rings 31 is connected through a Helmholtz resonance cavity; At the branch of the busbar trunking 25, the M0 standby module is connected. An isolating switch 26 is fixedly installed at the node at the branch of the M0 standby module and the busbar trunking 25. The isolating switch 26 is connected to the overload protection unit 27 through a cable. The overload protection unit 27 integrates thermal accumulation integration, and the heat accumulation of the thermal accumulation integration is based on the continuous integration from the start of the load to the current time t; The plug-in sleeve 35 is embedded on the left side of the composite board. The axis of the plug-in sleeve 35 coincides with the center of the busbar trunking 25. The base 35 is fixedly installed at the bottom end of the outer wall of the housing 32. Two parallel guide rails are provided at the bottom end of the outer wall of the base 35. A wireless charging coil is buried in the guide rail groove, and a phased array acoustic probe is embedded at the end of the guide rail. The wireless charging coil depends on the electromagnetic field in the air gap to couple with the access coil of the phased array acoustic probe; Furthermore, first, the transformer body is spliced by independent modules M1 to M3. The busbar trunking 25 between the M1 and M2 modules is connected in parallel by epoxy resin casting. The inner conductor in the busbar trunking 25 uses 3 layers of copper laminations stacked in a multi-layer staggered manner. The splicing surface is aligned and fixed by positioning pins, and sealing rubber strips are sleeved around the positioning pins. The M0 standby module is connected at the branch of the busbar trunking 25, and the isolating switch 26 is installed at the node to support hot pluggable expansion.

[0033] Then, the overload protection unit 27 integrates the thermal accumulation integration algorithm, Taccum =∫0 t ( Iload / Irated )2 dt, The integral heat from the start of the load to the current time t is calculated in real time. When the cumulative value exceeds the set threshold, the isolating switch 26 automatically cuts off the M0 module, and the current of the remaining modules is balanced through the graphene current sharing ring.

[0034] Finally, the housing 32 adopts a double-layer structure. The inner layer is an aluminum alloy frame 33 with insulating supports embedded in the grid, and the outer layer is coated with fluorocarbon resin. The circulating pipeline is filled with dry nitrogen, and the internal slightly positive pressure environment is maintained through the ventilation holes to prevent moisture intrusion. When measured with 4 modules connected in parallel, the temperature rise of the expansion interface is only 5°C higher than that of a single module, and the vibration noise is reduced from 78 dB to 72 dB.

[0035] Please refer to Figure 1 、 Figure 3 and Figure 5 For an embodiment provided by the present invention: a super-large-capacity dry-type transformer with variable load, a compensation wire group is wound around the outer wall of the auxiliary iron core column 2. The power electronic module 36 is nested at the bottom of the auxiliary iron core column 2. The sub-box 37 is fixedly installed on the side of the conductor where the low-voltage winding 9 is located. The control module is embedded and installed in the inner wall of the sub-box 37 through a guide rail buckle; the power electronic module 36 is connected to the first end of the compensation wire group and is grounded at the same time. The input side of the power electronic module 36 is connected to the neutral tap at the bottom of the auxiliary iron core column 2 through an insulated copper bar, and the control module is rigidly connected to the auxiliary iron core column 2 through a corrugated pipe; An adjustable magnetic flux branch 38 is arranged between the main iron core column 1 and the auxiliary iron core column 2. The adjustable magnetic flux branch 38 is composed of a U-shaped magnetic conductor. The open ends of the U-shaped magnetic conductor are respectively connected to the side surface of the main iron core column 1 and the top end of the auxiliary iron core column 2 through wedge-shaped joints. A permanent magnet array is embedded inside the U-shaped magnetic conductor. The N-S poles of the permanent magnet array are arranged alternately along the axial direction. The outer wall of the permanent magnet array is wrapped with a permalloy shielding layer. The end of the shielding layer leads out an adjusting rod 39, and the adjusting rod 39 extends to the side surface of the outer wall of the transformer casing 32; Furthermore, first of all, the shock absorption mechanism 28 adopts a double-layer design: the first layer of damping rubber pad 29 is fixed to the iron core column base through bolts, and the second layer of elastomer 30 wraps the electromagnetic coil. The input end of the coil is connected to a vibration sensor. The vibration sensor collects the vibration spectrum and dynamically adjusts the damping force of the electromagnetic coil to suppress low-frequency resonance.

[0036] Then, a sound-absorbing ring 31 is installed at the end of the winding, which is filled with porous sound-absorbing cotton inside. The adjacent rings are connected through a Helmholtz resonance cavity 62. The conical resonator is connected in series with the cylindrical resonator. The adjustable piston at the bottom of the cylindrical cavity changes the cavity volume through a handwheel adjustment mechanism. When the handwheel adjustment mechanism rotates 3 circles, the piston retracts; 5 groups of N-S alternating permanent magnets are embedded in the U-shaped magnetic conductor of the adjustable magnetic flux branch 38. The permalloy shielding layer is translated through the adjusting rod 39. When the voltage on the low-voltage side fluctuates by ±5%, the servo system drives the adjusting rod to move, and the magnetic flux compensation amount reaches 8% of the main magnetic flux.

[0037] Finally, three groups of orthogonal autotransformer coils are wound around the auxiliary iron core column 2. The X / Y / Z-axis windings are respectively sleeved on the upper / middle / lower parts of the iron core column. The outgoing ends are connected to the power electronic module 36 through a rotary wiring panel. A liquid metal conductive medium is filled between the moving and static contacts. The worm and gear mechanism drives the stepping motor to adjust the coupling degree.

[0038] Working principle: First of all, the main iron core column 1 and the auxiliary iron core column 2 form a composite magnetic circuit through a closed-loop magnetic yoke. The laminated stepped cross-section of the amorphous alloy strip 20 of the main iron core column 1 and the nanocrystalline-filled joint of the auxiliary iron core column 2 cooperate to optimize the magnetic flux distribution. When the load changes, the permanent magnet array in the adjustable magnetic flux branch 38 changes the leakage magnetic path through axial adjustment, and cooperates with the moving silicon steel sheet group of the tap-changing adjustment mechanism to adjust the effective cross-sectional area of the iron core. At the same time, the three-section grading structure of the low-voltage winding 9 is combined and switched through the magnetically controlled vacuum circuit breaker 10. The gradually changing cross-section copper row of the L2 section and the different cross-sectional areas of the L1 / L3 form a current gradient distribution. Combined with the parallel sub-winding structure of the high-voltage winding 5, the switching ratio of each section of the winding is controlled by a decoder to perform capacity grading adjustment; During operation, the guide vanes 15 of the annular heat dissipation air duct 14 automatically adjust the inclination angle according to the feedback of the temperature rise probe, driving the forced convection in the porous ceramic coating. The phase change energy storage tubes of the secondary cooling unit synchronously absorb the peak heat in the air flow channel, while the semiconductor refrigeration sheets between the windings cool the contact area directionally, forming a multi-level thermal management system. The independent units with modular design are losslessly expanded through the orthogonal cross-shaped copper busbars and the graphene current sharing ring. The overload protection unit 27 predictively cuts off the faulty module through the thermal accumulation integration algorithm, and at the same time, the standby module is seamlessly switched through the liquid metal conductive medium. The electromagnetic-mechanical composite damping mechanism 28 and the Helmholtz resonance cavity form a series silencing group, suppressing the magnetostrictive vibration of the iron core and eliminating specific frequency noise through the adjustable piston at the same time. The passive LC resonance sensor 22 monitors the electromagnetic-mechanical state, generates a three-dimensional field distribution map through the thermal-mechanical coupling algorithm, and finally compensates and regulates the voltage of the auxiliary magnetic circuit through the orthogonal autotransformer coil of the power electronic module 36.

[0039] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A variable load ultra-large capacity dry-type transformer, characterized in that: It comprises three groups of main iron core columns (1) and three groups of auxiliary iron core columns (2), wherein a magnetic yoke (3) is fixedly mounted on the top and bottom ends of the outer walls of the main iron core columns (1) and the auxiliary iron core columns (2), and the magnetic yokes (3) are connected to form a closed-loop magnetic circuit; The cross section of the main iron core column (1) is arranged in a stepped shape. The interior of the main iron core column (1) is laminated by three layers of amorphous alloy strips (20). The thickness of the middle layer of the three layers of amorphous alloy strips (20) is arranged to be 1.2 to 1.5 times that of the layers on both sides. The lamination group inside the auxiliary iron core column (2) is provided with an independent lap plate (4) at the joint. The lap gap between the lap plate (4) and the lamination group is filled with iron-based nanocrystals. The top thickness of the yoke (3) is less than 10 mm of the bottom thickness. The joint surface between the yoke (3) and the iron core column is coated with epoxy resin adhesive.

2. The variable load ultra-large capacity dry-type transformer according to claim 1, characterized in that: The outer wall of the core column is provided with a high-voltage winding (5) and a low-voltage winding (9), the high-voltage winding (5) is composed of N parallel sub-windings, each sub-winding is composed of a copper foil conductor (6) and a stranded conductor (7), a plurality of strands of the stranded conductor (7) are wound around the outer wall of the copper foil conductor (6), the copper foil conductor (6) and the stranded conductor (7) are bonded by a semi-conductive silicone rubber layer (8), the width of the copper foil conductor (6) is set to 60% to 80% of the axial length of the high-voltage winding (5), and the stranding spacing between the stranded conductors (7) is set to 2 to 3 times the diameter of a single conductor; The low-voltage winding (9) is divided into three sections, namely L1, L2 and L3. The three sections are wound in layers on the outer wall of the core column. The tail ends of the three sections are connected to the two ends of the magnetically controlled vacuum circuit breaker (10) respectively. The magnetically controlled coil of each section of the magnetically controlled vacuum circuit breaker (10) is connected to the decoder through a control line. The connection between the magnetically controlled vacuum circuit breaker (10) and the winding conductor is coated with a boron nitride ceramic insulation layer (11). The boron nitride ceramic insulation layer (11) is reserved with a threading hole for the control line. The cross-sectional area of ​​the conductor of the L1 section is 1.5-2 times that of the L3 section. The conductor of the L2 section adopts a trapezoidal copper bar with a gradient cross-section. An epoxy glass cloth transition layer is arranged between the layers of the three sections of the winding. An axial heat dissipation groove (40) is provided on the outer surface of the transition layer. The heat dissipation groove (40) is embedded with a semiconductor cooling plate. The cold end of the semiconductor cooling plate is attached to and extends to the contact area of ​​the magnetically controlled vacuum circuit breaker (10).

3. The variable load ultra-large capacity dry-type transformer according to claim 2, characterized in that: The main body of the boron nitride ceramic insulating layer (11) is composed of a modified silicone rubber matrix, and 5% to 8% by mass of boron nitride nanosheets (12) and silicon carbide fibers (13) are uniformly distributed in the matrix; An annular heat dissipation duct (14) is arranged on the outer wall of the high-voltage winding (5) and the low-voltage winding (9), and a porous ceramic coating is sprayed on the inner wall of the annular heat dissipation duct (14). The porosity of the porous ceramic coating is set to be 40% to 60%. The annular heat dissipation duct (14) is connected to the centrifugal fan via an integrated annular bracket (16). A gear ring (18) is fixedly installed on the inner wall side of the integrated annular bracket (16). The gear ring (18) is meshed with an internal gear. The gear is coaxially fixedly installed with a rotating shaft (17). The other end of the rotating shaft (17) is fixedly connected to the tail end of a guide vane (15). The guide vane (15) is distributed in a circle and has an inclination angle of 15° to 45°. A temperature rise probe is embedded in the inner wall of the annular heat dissipation duct (14), and the temperature rise probe is connected to a controller via a twisted pair cable.

4. The variable load ultra-large capacity dry-type transformer according to claim 1, characterized in that: A magnetically conductive partition (19) is arranged between the core column and the winding, and the magnetically conductive partition (19) is alternately laminated by an amorphous alloy strip (20) and an insulating paper (21), and the lamination ratio is set to 1:3; The inner layer of the surface of the core column is coated with an epoxy resin-based ferrite coating, and the outer surface of the epoxy resin-based ferrite coating is coated with a graphene-modified silicone rubber coating.

5. The variable load ultra-large capacity dry-type transformer according to claim 2, characterized in that: A passive LC resonant sensor (22) is embedded at the node of the high-voltage winding (5) and the low-voltage winding (9), and the passive LC resonant sensor (22) comprises an amorphous thin strip and a polyimide film, the amorphous thin strip is adhered to the outer surface of the conductor of the high-voltage winding (5) and the low-voltage winding (9), and the polyimide film covers the amorphous thin strip and is fixed to the inner surface of the boron nitride ceramic insulating layer (11); The passive LC resonant sensor (22) is connected to a near-field coupling antenna and transmitted to an external monitoring module (23). The coupling antenna is fixedly wound around an insulating bracket at the end of a high-voltage winding (5) and a low-voltage winding (9). The monitoring module (23) has a built-in thermal-mechanical coupling algorithm. The thermal-mechanical coupling algorithm generates a three-dimensional temperature rise field and deformation field distribution diagram. A spring contact finger (24) is fixedly installed on the outer wall of the monitoring module (23). The spring contact finger (24) is connected to a magnetically controlled vacuum circuit breaker (10) via a cable.

6. The variable load ultra-large capacity dry-type transformer according to claim 1, characterized in that: The outer wall of the transformer body is provided with a shell (32), the transformer body is formed by splicing independent modules, the independent modules include M1 to Mn modules, the M1 module and the M2 module are connected in parallel for capacity expansion via an epoxy resin cast bus duct (25), the inner wall of the bus duct (25) is fixedly installed with a conductor, the inner conductor of the bus duct (25) is formed by stacking multiple layers of laminations, a positioning pin is fixedly installed on the splicing surface of the M1 module and the M2 module, a sealing strip is fixedly attached to the outer wall of the positioning pin, and a port is provided on the bus duct (25) at the splicing surface to connect to the overload protection unit (27); The branch of the bus duct (25) is connected to the M0 standby module, and the node between the M0 standby module and the branch of the bus duct (25) is fixedly installed with an isolating switch (26), and the isolating switch (26) is connected to the overload protection unit (27) through a cable. The overload protection unit (27) integrates heat accumulation integral, and the heat accumulation of the heat accumulation integral is based on the continuous integration from the start of the load to the current time t.

7. The variable load ultra-large capacity dry-type transformer according to claim 1, characterized in that: The bottom ends of the outer walls of the main iron core column (1) and the auxiliary iron core column (2) are fixedly mounted with a shock absorbing mechanism (28), the shock absorbing mechanism (28) being arranged in two layers, the first layer being provided with a damping rubber pad (29) fixed to the base of the main iron core column (1) and the auxiliary iron core column (2) by bolts, the second layer being provided with an elastic body (30), the bottom end of the outer wall of the damping rubber pad (29) being fixedly mounted with the elastic body (30), the electromagnetic coil being wrapped inside the elastic body (30), the end of the electromagnetic coil leading out an input port to be connected to a vibration sensor, and the vibration sensor being embedded in the bottom of the damping rubber pad (29); A silencer ring (31) is fixedly installed at the end of the winding, the silencer ring (31) is filled with porous sound-absorbing cotton, and each adjacent layer of silencer rings (31) is connected via a Helmholtz resonance cavity.

8. The variable load ultra-large capacity dry-type transformer according to claim 6, characterized in that: The shell (32) is provided with a double-layer structure, the inner layer is an aluminum alloy frame (33), the grid of the aluminum alloy frame (33) is embedded with an insulating support member, the outer layer is a fluorocarbon resin coating, a vent hole is reserved at the inner bottom of the aluminum alloy frame (33), the aluminum alloy frame (33) is connected to a circulation pipeline through the vent hole, dry nitrogen is introduced into the circulation pipeline, the outer wall of the aluminum alloy frame (33) is fixedly installed with a composite plate through a back bolt structure, a guide groove is reserved at the joint of the composite plate, and a generator electrode (34) is fixedly installed along the circumferential direction on the inner wall of the shell (32); A plug-in sleeve (35) is embedded in the left side of the composite plate, the axis of the plug-in sleeve (35) coincides with the center of the busbar duct (25), the base (35) is fixedly mounted at the bottom end of the outer wall of the housing (32), two parallel guide rails are provided at the bottom end of the outer wall of the base (35), a wireless charging coil is embedded in the guide rail groove, an acoustic phased array probe is embedded in the end of the guide rail, and the wireless charging coil relies on the electromagnetic field in the air gap to couple with the access coil of the acoustic phased array probe.

9. The variable load ultra-large capacity dry-type transformer according to claim 1, characterized in that: The outer wall of the auxiliary iron core column (2) is wound with a compensation wire group, the bottom of the auxiliary iron core column (2) is embedded with a power electronic module (36), a sub-box (37) is fixedly installed on the side of the conductor where the low-voltage winding (9) is located, and the inner wall of the sub-box (37) is embedded with a control module through a guide rail buckle; The power electronic module (36) is connected to the head end of the compensation line group and is also grounded; the input side of the power electronic module (36) is connected to the neutral point tap at the bottom of the auxiliary iron core column (2) via an insulating copper busbar; and the control module is rigidly connected to the auxiliary iron core column (2) via a corrugated tube.

10. The variable load ultra-large capacity dry-type transformer according to claim 1, characterized in that: An adjustable magnetic flux branch (38) is provided between the main iron core column (1) and the auxiliary iron core column (2), the adjustable magnetic flux branch (38) being composed of a U-shaped magnetic conductor, the open ends of the U-shaped magnetic conductor being respectively connected to the side surface of the main iron core column (1) and the top of the auxiliary iron core column (2) via wedge-shaped joints, a permanent magnet array being embedded in the U-shaped magnetic conductor, the N and S poles of the permanent magnet array being alternately arranged along the axial direction, the outer wall of the permanent magnet array being wrapped with a Permalloy shielding layer, an adjusting rod (39) being led out from the end of the shielding layer, and the adjusting rod (39) extending to the outer wall side of the transformer housing (32).

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