Variable load super capacity dry type transformer

Abstract

The application discloses a variable-load super-large capacity dry-type transformer, relates to the related technical field of dry-type transformers, and comprises three groups of main iron core columns and three groups of auxiliary iron core columns, wherein the main iron core column section is provided in a stepped shape, the inside of the main iron core column is stacked by three layers of amorphous alloy strips, the thickness of the middle layer of the three layers of amorphous alloy strips is 1.2-1.5 times that of the two side layers, and the lamination groups in the inside of the auxiliary iron core column are provided with independent lap pieces at the joints. The application realizes uniform magnetic flux density distribution and single-column capacity improvement by combining the stepped section of the three groups of main iron core columns with the magnetic yoke which is thin at the top and thick at the bottom, solves the problems that the single capacity of the traditional dry-type transformer is limited and the whole machine needs to be replaced for capacity expansion, reduces the occupied volume through modular splicing, increases the capacity of a single group of iron core columns, and reduces the no-load loss.

Description

Technical Field

[0001] This invention relates to the technical field of dry-type transformers, specifically to an ultra-large capacity dry-type transformer with variable load. Background Technology

[0002] In recent years, with the accelerated construction of smart cities and new power systems, the application of high-reliability dry-type transformers in rail transit, new energy grid connection, and data centers has continued to expand. These scenarios place stringent requirements on equipment, including high voltage levels, ultra-large rated power, and wide load regulation range. However, this exposes the inherent contradictions of traditional dry-type transformers: winding eddy current losses increase quadratically with voltage, DC resistance losses fluctuate under dynamic loads, exacerbating local hot spot accumulation, and the thermal resistance bottleneck of air cooling leads to excessive temperature rise, threatening insulation life.

[0003] Therefore, it is essential to propose an ultra-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 patent enables the synchronous rotation of two threaded rods, which in turn drives two threaded sleeves to move synchronously. This allows for adjustment of the height of the inner shell and the offset of the first and second ventilation openings, thus providing ventilation, sealing, heat insulation, and heat preservation.

[0005] The aforementioned patent achieves ventilation and sealing for heat insulation by staggering the first and second ventilation openings on both sides of the outer casing. However, in the case of ultra-large capacity, dynamic load will cause fluctuations in DC resistance loss, which in turn will cause local hot spots to accumulate.

[0006] To this end, this application proposes an ultra-large capacity dry-type transformer that can achieve magnetic flux homogenization closed loop by combining stepped amorphous alloy laminations with a magnetic yoke that is thin at the top and thick at the bottom, breaking through the capacity limitation of a single dry-type transformer in traditional models. The cross copper busbars and ring contact finger interfaces between modules support "plug and play" with variable loads under power. Summary of the Invention

[0007] The purpose of this invention is to provide an ultra-large capacity dry-type transformer with variable load to solve the technical problems mentioned in the background art, such as the winding eddy current loss increasing quadratically with voltage, the DC resistance loss fluctuation under dynamic load exacerbating the accumulation of local hot spots, and the thermal resistance bottleneck of air cooling causing excessive temperature rise, which threatens the insulation life.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a variable load ultra-large capacity dry-type transformer, comprising three sets of main core columns and three sets of auxiliary core columns, wherein magnetic yokes are fixedly installed at the top and bottom of the outer walls of the main core columns and the auxiliary core columns, and the magnetic yokes are connected to form a closed-loop magnetic circuit.

[0009] The main core column has a stepped cross-section and is made of three layers of amorphous alloy strips. The thickness of the middle layer of the three layers of amorphous alloy strips is 1.2 to 1.5 times that of the two side layers. The laminations inside the auxiliary core column have independent overlapping pieces at the joints. The overlap gap between the overlapping pieces and the laminations 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 core column is coated with epoxy resin adhesive.

[0010] Preferably, the outer wall of the main core column is fitted with a high-voltage winding and a low-voltage winding. The high-voltage winding consists of N parallel sub-windings. Each sub-winding consists of a copper foil conductor and stranded wires. The outer wall of the copper foil conductor is wound with multiple strands of stranded wires. The copper foil conductor and the stranded wires are bonded together by a semi-conductive silicone rubber layer. The width of the copper foil conductor is set to 60% to 80% of the axial length of the high-voltage winding. The stranding spacing between the stranded wires is set to 2 to 3 times the diameter of a single wire.

[0011] The low-voltage winding is divided into three sections, namely L1, L2 and L3. The three windings are wound in layers on the outer wall of the iron core column. The ends of the three windings are connected to the two ends of the magnetically controlled vacuum circuit breaker. The magnetic control coil of the magnetically controlled vacuum circuit breaker connected to each section is connected to the decoder through the control line. The connection between the magnetically controlled vacuum circuit breaker and the winding conductor is covered with a boron nitride ceramic insulation layer. The boron nitride ceramic insulation layer has reserved holes for the control line to pass through. The cross-sectional area of ​​the conductor of L1 section is 1.5-2 times that of L3 section. The conductor of L2 section adopts a trapezoidal copper busbar with a gradually changing cross section. An epoxy glass cloth transition layer is set between the layers of the three windings. An axial heat dissipation channel is opened on the outer surface of the transition layer. The heat dissipation channel is embedded with a semiconductor cooling chip. The cold end of the semiconductor cooling chip is attached to and extends to the contact area of ​​the magnetically controlled vacuum circuit breaker.

[0012] Preferably, the boron nitride ceramic insulating layer is composed of a modified silicone rubber matrix, in which boron nitride nanosheets and silicon carbide fibers with a mass fraction of 5% to 8% are uniformly distributed.

[0013] The outer walls of the high-voltage and low-voltage windings are equipped with annular heat dissipation ducts. The inner walls of the annular heat dissipation ducts are coated with a porous ceramic coating with a porosity of 40% to 60%. The annular heat dissipation ducts are connected to the centrifugal fan via an integrated annular bracket. A gear ring is fixedly installed on the inner side of the integrated annular bracket, and a gear meshes inside the gear ring. A rotating shaft is fixedly installed coaxially with the gear. The other end of the rotating shaft is fixedly connected to the tail end of the guide vanes. The guide vanes are circumferentially distributed with an inclination angle of 15° to 45°. A temperature rise probe is embedded in the inner wall of the annular heat dissipation duct, and the temperature rise probe is connected to the controller via a twisted pair cable.

[0014] Preferably, a magnetic separator is provided between the core column and the winding, and the magnetic separator is formed by alternating layers of amorphous alloy strip and insulating paper, with a layering ratio of 1:3.

[0015] The inner layer 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.

[0016] Preferably, a passive LC resonant sensor is embedded at the node of the high-voltage winding and the low-voltage winding. The passive LC resonant sensor includes an amorphous thin strip and a polyimide film. The amorphous thin strip is attached to the outer surface of the conductors of the high-voltage winding and the low-voltage winding. The polyimide film covers the amorphous thin strip and is fixed to the inner surface of the boron nitride ceramic insulating layer.

[0017] The passive LC resonant sensor transmits data to an external monitoring module via a near-field coupling antenna. The coupling antenna is fixedly wound around the end insulating brackets of the high-voltage winding and the low-voltage winding. The monitoring module has a built-in thermo-mechanical coupling algorithm that generates a three-dimensional temperature rise field and deformation field distribution map. A spring contact finger is fixedly installed on the outer wall of the monitoring module, and the spring contact finger is connected to a magnetically controlled vacuum circuit breaker via a cable.

[0018] Preferably, the outer wall of the transformer body is provided with an outer shell, and the transformer body is assembled from independent modules. The independent modules include modules M1 to Mn. Modules M1 and M2 are connected in parallel to expand capacity through epoxy resin cast busbars. Conductors are fixedly installed on the inner wall of the busbars. The conductors in the busbars are formed by multiple layers of laminated sheets. Positioning pins are fixedly installed on the splicing surface of modules M1 and M2. Sealing strips are fixedly attached to the outer wall of the positioning pins. The busbars at the splicing surface are provided with ports connected to overload protection units.

[0019] The M0 backup module is connected to the branch of the bus trunking. The disconnect switch is fixedly installed at the node between the M0 backup module and the branch of the bus trunking. The disconnect switch is connected to the overload protection unit through a cable. The overload protection unit integrates thermal accumulation integral. The heat accumulation of the thermal accumulation integral is based on the continuous integration from the start of the load to the current time t.

[0020] Preferably, a damping mechanism is fixedly installed at the bottom of the outer wall of the main core column and the auxiliary core column. The damping mechanism is configured as two layers. The first layer is provided with a damping pad and is fixed to the base of the main core column and the auxiliary core column by bolts. The second layer is provided with an elastic body. The elastic body is fixedly installed at the bottom of the outer wall of the damping pad. An electromagnetic coil is wrapped inside the elastic body. The input port of the electromagnetic coil is led out and connected to a vibration sensor. The vibration sensor is embedded in the bottom of the damping pad.

[0021] A noise-absorbing ring is fixedly installed at the end of the winding. The inside of the noise-absorbing ring is filled with porous sound-absorbing cotton. Each adjacent layer of noise-absorbing ring is connected by a Helmholtz resonant cavity.

[0022] Preferably, the outer shell has a double-layer structure, with an inner layer of aluminum alloy frame and an insulating support embedded in the mesh of the aluminum alloy frame, and an outer layer of fluorocarbon resin coating. Ventilation holes are reserved at the bottom of the inner side of the aluminum alloy frame, and the aluminum alloy frame is connected to a circulation pipe through the ventilation holes. Dry nitrogen is introduced into the circulation pipe. A composite plate is fixedly installed on the outer wall of the aluminum alloy frame through a back bolt structure, and a guide groove is reserved at the splice of the composite plate. The generator electrode is fixedly installed on the inner wall of the outer shell along the circumference.

[0023] A plug-in sleeve is embedded on the left side of the composite plate. The axis of the plug-in sleeve coincides with the center of the busbar groove. A base is fixedly installed at the bottom of the outer wall of the outer shell. Two parallel guide rails are opened at the bottom of the outer wall of the base. A wireless charging coil is embedded in the guide rail groove. An acoustic phased array probe is embedded at the end of the guide rail. The wireless charging coil relies on the electromagnetic field in the air gap to couple the access coil of the acoustic phased array probe.

[0024] Preferably, the auxiliary core column has a compensation wire group wound on its outer wall, a power electronic module nested at the bottom of the auxiliary core column, a sub-box fixedly installed on the side of the conductor where the low voltage winding is located, and a control module embedded in the inner wall of the sub-box through guide rail clips.

[0025] The power electronic module is connected to the first end of the compensation line 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.

[0026] Preferably, an adjustable magnetic flux branch is provided between the main core column and the auxiliary core column. The adjustable magnetic flux branch is composed of a U-shaped magnetic conductor. The open end of the U-shaped magnetic conductor is connected to the side of the main core column and the top of the auxiliary core column through a wedge joint. A permanent magnet array is embedded inside the U-shaped magnetic conductor. The N and 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 adjustment rod is led out from the end of the shielding layer and extends to the side of the outer wall of the transformer shell.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. This invention achieves uniform magnetic flux density distribution and increases single-column capacity by combining three sets of stepped cross-section main core columns with a magnetic yoke that is thin at the top and thick at the bottom. It solves the problem that the capacity of a single dry-type transformer is limited and that expansion requires the replacement of the entire unit. The modular splicing reduces the floor space, increases the capacity of a single core column, and reduces no-load loss.

[0029] 2. This invention uses three low-voltage windings consisting of conductors in different states (L1-L3) to be simultaneously connected to the circuit breaker, thereby realizing dynamic switching of winding combinations to adjust the load. This solves the problem that load adjustment of dry-type transformers relies on mechanical taps, which has a slow response and is prone to arcing. It adapts to the needs of grid fluctuations and new energy grid connection.

[0030] 3. This invention uses a porous ceramic coating embedded in the heat dissipation duct and adjustable guide vanes to achieve enhanced turbulent heat transfer by the porous ceramic coating when the centrifugal fan drives the airflow, directional cooling of hot spots by the semiconductor refrigeration chip, and absorption of transient heat by the phase change material. This solves the problem of insulation aging caused by local temperature rise under ultra-large capacity and insufficient efficiency of traditional air cooling, thus extending the life cycle of the transformer.

[0031] 4. This invention achieves the suppression of electromagnetic interference between modules by connecting independent modules in parallel with epoxy resin cast busbars, solving the problems of needing to replace the entire transformer for capacity expansion and poor electromagnetic compatibility. The capacity expansion method is "plug and play" and the capacity expansion effect is doubled. Attached Figure Description

[0032] Figure 1 This is a front view structural diagram of the present invention;

[0033] Figure 2 This is a schematic diagram of the front part of the present invention;

[0034] Figure 3 This is a schematic diagram of the heat dissipation duct structure of the present invention;

[0035] Figure 4 This is a schematic diagram of the monitoring module structure of the present invention;

[0036] Figure 5 This is a schematic diagram of the high-voltage winding structure of the present invention;

[0037] Figure 6 This is a schematic diagram of the shock absorption mechanism of the present invention;

[0038] Figure 7 This is a schematic diagram of the boron nitride ceramic insulating layer structure of the present invention;

[0039] Figure 8 This is a schematic diagram of the magnetic separator structure of the present invention.

[0040] In the diagram: 1. Main core column; 2. Auxiliary core column; 3. Magnetic yoke; 4. Lap joint; 5. High-voltage winding; 6. Copper foil conductor; 7. Stranded wire; 8. Semi-conductive silicone rubber layer; 9. Low-voltage winding; 10. Magnetic 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 support; 17. Shaft; 18. Gear ring; 19. Magnetic guide plate; 20. Amorphous composite 21. Gold strip; 22. Insulating paper; 23. Passive LC resonant sensor; 24. Monitoring module; 25. Spring contact finger; 26. Busbar trunking; 27. Disconnecting switch; 28. Overload protection unit; 29. ​​Shock absorption mechanism; 30. Damping pad; 31. Elastomer; 32. Silencing ring; 33. Housing; 34. Aluminum alloy frame; 35. Generator electrode; 36. Base; 37. Power electronic module; 38. Sub-box; 39. Adjustable magnetic flux branch; 40. Adjusting rod; 51. Heat dissipation channel. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" 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 a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Please see Figure 1 , Figure 2 and Figure 3This invention provides an embodiment of a variable-load, ultra-large capacity dry-type transformer, comprising three sets of main core columns 1 and three sets of auxiliary core columns 2. Magnetic yokes 3 are fixedly installed at the top and bottom of the outer walls of the main core columns 1 and auxiliary core columns 2, and the magnetic yokes 3 are connected to form a closed-loop magnetic circuit. The main core column 1 has a stepped cross-section, and its interior is composed of three layers of amorphous alloy strips 20. The thickness of the middle layer of the three amorphous alloy strips 20 is set to 1.2 to 1.5 times that of the two side layers. The laminations inside the auxiliary core columns 2 have independent overlapping pieces 4 at the joints. The overlap gap between the overlapping piece 4 and the laminations is filled with iron-based nanocrystals. The top thickness of the magnetic yoke 3 is 10 mm less than the bottom thickness. The interface between the magnetic yoke 3 and the core column is coated with epoxy resin adhesive.

[0045] A magnetic separator 19 is provided between the core column and the winding. The magnetic separator 19 is formed by alternating layers of amorphous alloy strip 20 and insulating paper 21, with a layering ratio of 1:3. The inner layer of the 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.

[0046] Furthermore, firstly, the main core column 1 adopts a three-layer amorphous alloy strip 20 stacked structure, with the thickness of the middle layer being 1.3 times that of the two side layers. During stacking, the middle layer is pre-bent 3° along the axial direction, and the stacking direction is inclined at a 10° angle to the axis. The magnetic conductive plate 19 adopts an amorphous alloy strip 20 and insulating paper 21 stacked alternately in a 1:3 ratio. The edge of the amorphous strip is processed with a serrated cut with a 30° phase difference. The lamination group of the auxiliary core column 2 has an independent overlapping piece 4 embedded at the joint. The overlapping gap is filled with iron-based nanocrystalline material. This method improves the local magnetic permeability. The top thickness of the magnetic yoke 3 is 10 mm smaller than that of the bottom, forming a "narrow at the top and wide at the bottom" magnetic yoke structure. The thick bottom layer bears the additional magnetic flux caused by the self-weight of the winding, while the thin top layer reduces the no-load excitation loss. The joint surface is coated with epoxy resin adhesive.

[0047] 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 on the top of the core column through a dovetail groove. The servo push rod is driven to move axially through a ceramic connecting rod. The control line of the servo push rod passes through the metal conduit embedded in the magnetic yoke 3 and is led to the control box of the outer casing 32.

[0048] Finally, an expansion port is set at the bottom of the core column, and 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. The π-shaped conductive strip is clamped to both sides of the I-shaped magnetic conductor and fixed by insulating clamps. When the magnetic flux density of the core column reaches 1.4T, the leakage magnetic flux of the partition is reduced by 22% compared with the traditional lamination, and the axial leakage magnetic field distortion rate at the winding end is reduced by 18%.

[0049] Please see Figure 1 , Figure 3 and Figure 4 This invention provides an embodiment of a high-capacity dry-type transformer with variable load. The main core column is fitted with a high-voltage winding 5 and a low-voltage winding 9. The high-voltage winding 5 consists of N parallel sub-windings, each composed of a copper foil conductor 6 and stranded wires 7. Multiple strands of stranded wires 7 are wound around the outer wall of the copper foil conductor 6. The copper foil conductor 6 and the stranded wires 7 are bonded together by a semi-conductive silicone rubber layer 8. The width of the copper foil conductor 6 is set to 60%–80% of the axial length of the high-voltage winding 5, and the stranding spacing between the stranded wires 7 is set to 2–3 times the diameter of a single wire. The low-voltage winding 9 is divided into three segments, L1, L2, and L3, which are layered on the outer wall of the core column. The winding is completed, and the ends of the three windings are respectively connected to the two ends of the magnetically controlled vacuum circuit breaker 10. The magnetic control coil of each segment of the magnetically controlled vacuum circuit breaker 10 is connected to the decoder through the control line. The connection between the magnetically controlled vacuum circuit breaker 10 and the winding conductor is covered with a boron nitride ceramic insulation layer 11. The boron nitride ceramic insulation layer 11 has reserved holes for the control line. The cross-sectional area of ​​the L1 conductor is 1.5-2 times that of the L3 conductor. The L2 conductor adopts a trapezoidal copper busbar with a gradually changing cross section. An epoxy glass cloth transition layer is set between the three windings. An axial heat dissipation channel 40 is opened on the outer surface of the transition layer. A semiconductor cooling chip is embedded in the heat dissipation channel 40. The cold end of the semiconductor cooling chip is attached and extends to the contact area of ​​the magnetically controlled vacuum circuit breaker 10.

[0050] The boron nitride ceramic insulation layer 11 is mainly composed of a modified silicone rubber matrix, in which boron nitride nanosheets 12 and silicon carbide fibers 13 with a mass fraction of 5% to 8% are uniformly distributed. The outer walls of the high-voltage winding 5 and the low-voltage winding 9 are provided with annular heat dissipation ducts 14. The inner wall of the annular heat dissipation ducts 14 is sprayed with a porous ceramic coating with a porosity of 40% to 60%. The annular heat dissipation ducts 14 are connected to the centrifugal fan through an integrated annular bracket 16. A gear ring 18 is fixedly installed on the inner side of the integrated annular bracket 16. The gear ring 18 meshes with a gear. A rotating shaft 17 is fixedly installed on the gear coaxially. The other end of the rotating shaft 17 is fixedly connected to the tail end of the guide vane 15. The guide vane 15 is circumferentially distributed and has an inclination angle of 15° to 45°. A temperature rise probe is embedded in the inner wall of the annular heat dissipation ducts 14. The temperature rise probe is connected to the controller through a twisted pair cable.

[0051] Furthermore, firstly, the high-voltage winding 5 consists of four parallel sub-windings. The width of the copper foil conductor 6 in each sub-winding is 70% of its axial length, and the outer wall is wrapped with stranded wire 7. The stranding spacing is 2.5 times the diameter of a single wire. The copper foil and the stranded wire are bonded together by a semi-conductive silicone rubber layer 8, which reduces the high-frequency eddy current loss by 35%.

[0052] Then, the low-voltage winding 9 is divided into three layers: L1, L2, and L3. The conductor cross-sectional area of ​​L1 is 1.8 times that of L3. L2 adopts a trapezoidal gradient cross-section copper busbar, with an epoxy glass cloth transition layer between layers and an axial heat dissipation channel 40. It has an embedded semiconductor cooling chip, and the cold end extends to the contact area of ​​the magnetically controlled vacuum circuit breaker 10 to suppress the temperature rise. When the load rate of L1 exceeds 80%, the cooling chip starts, the temperature difference ΔT ≥ 15℃, and the contact temperature rise drops from 110℃ to 85℃.

[0053] Finally, the ends of the three windings are connected to the magnetically controlled vacuum circuit breaker 10. The magnetically controlled coil of the magnetically controlled vacuum circuit breaker 10 is controlled to open and close by a decoder. The connection of the magnetically controlled vacuum circuit breaker 10 is covered with a boron nitride ceramic insulation layer 11, which is doped with 6% boron nitride nanosheets 12 and silicon carbide fibers 13. The monitoring module 23 collects the winding temperature rise data in real time through the passive LC resonant sensor 22 and drives the magnetically controlled vacuum circuit breaker 10 to dynamically switch the load.

[0054] Please see Figure 1 , Figure 2 and Figure 7 An embodiment of the present invention provides: a variable-load ultra-large capacity dry-type transformer, wherein a passive LC resonant sensor 22 is embedded at the node of the high-voltage winding 5 and the low-voltage winding 9. The passive LC resonant sensor 22 includes an amorphous thin strip and a polyimide film. The amorphous thin strip is attached to the outer surface of the conductors of the high-voltage winding 5 and the low-voltage winding 9. 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 transmits data to an external monitoring module 23 through a near-field coupling antenna. The coupling antenna is fixedly wound around the insulating support at the end of the high-voltage winding 5 and the low-voltage winding 9. The monitoring module 23 has a built-in thermo-mechanical coupling algorithm that generates a three-dimensional temperature rise field and deformation field distribution map. 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 through a cable.

[0055] The transformer body is provided with an outer shell 32 on its outer wall. The transformer body is assembled from independent modules, including modules M1 to Mn. Modules M1 and M2 are connected in parallel for capacity expansion through epoxy resin cast busbar 25. Conductors are fixedly installed on the inner wall of the busbar 25. The conductors in the busbar 25 are formed by multiple layers of laminated sheets. Positioning pins are fixedly installed on the splicing surface of modules M1 and M2. Sealing strips are fixedly attached to the outer wall of the positioning pins. The busbar 25 at the splicing surface is provided with a port for connecting to an overload protection unit 27.

[0056] The outer shell 32 has a double-layer structure. The inner layer is an aluminum alloy frame 33 with an insulating support embedded in the mesh of the aluminum alloy frame 33. The outer layer is coated with fluorocarbon resin. Ventilation holes are reserved at the bottom of the inner side of the aluminum alloy frame 33. The aluminum alloy frame 33 is connected to the circulation pipe through the ventilation holes. Dry nitrogen is introduced into the circulation pipe. The composite plate is fixedly installed on the outer wall of the aluminum alloy frame 33 by a back bolt structure. The flow guide groove is reserved at the splice of the composite plate. The generator electrode 34 is fixedly installed on the inner wall of the outer shell 32 along the circumference.

[0057] Furthermore, firstly, a porous ceramic coating with a porosity of 50% is sprayed on the inner wall of the annular heat dissipation duct 14, and an external centrifugal fan is connected. A secondary cooling unit is added inside the annular heat dissipation duct 14. The integrated annular bracket 16 has a toothed ring 18 embedded in it that meshes with a gear, driving the rotating shaft 17 to rotate the guide vanes 15 with an inclination angle of 30°, thereby enhancing airflow disturbance.

[0058] Then, the secondary cooling unit consists of a honeycomb metal substrate and a phase change energy storage tube. The metal substrate channels and the guide vanes 15 are arranged at 90° intervals. The phase change energy storage tube is encapsulated with paraffin-nano-aluminum composite material, and the outer wall is welded with needle-shaped heat dissipation fins that extend into the main air duct. It uses the latent heat of phase change to absorb transient heat. In the 120℃ overload test, the latent heat absorption of the energy storage tube caused the average temperature rise rate of the winding to decrease by 0.6℃ / min, which extended the overload time by 20 minutes compared with the traditional air cooling.

[0059] Finally, the temperature rise probe is embedded in the inner wall of the air duct, and the speed of the centrifugal fan and the tilt angle of the guide vane 15 are adjusted by the controller. When the temperature exceeds the threshold, the semiconductor cooling chip is activated in the heat dissipation channel 40, and the cold end directly cools the contacts of the magnetically controlled vacuum circuit breaker 10, forming a combination of active and passive heat dissipation.

[0060] Please see Figure 1 , Figure 6 and Figure 8 The present invention provides an embodiment of a variable-load, ultra-large capacity dry-type transformer. A damping mechanism 28 is fixedly installed at the bottom of the outer wall of the main core column 1 and the auxiliary core column 2. The damping mechanism 28 is configured in two layers. The first layer consists of damping pads 29 fixed to the bases of the main core column 1 and the auxiliary core column 2 by bolts. The second layer consists of an elastic body 30, with the elastic body 30 fixedly installed at the bottom of the outer wall of the damping pads 29. An electromagnetic coil is wrapped inside the elastic body 30, and an input port is led out from the end of the electromagnetic coil to connect to a vibration sensor. The vibration sensor is embedded in the bottom of the damping pads 29. A noise-absorbing ring 31 is fixedly installed at the winding end, and the noise-absorbing ring 31 is filled with porous sound-absorbing cotton. Each adjacent layer of noise-absorbing rings 31 is connected through a Helmholtz resonant cavity.

[0061] The branch of the bus trunking 25 is connected to the M0 backup module. The M0 backup module and the node of the branch of the bus trunking 25 are fixedly installed with the disconnect switch 26. The disconnect switch 26 is connected to the overload protection unit 27 through the cable. The overload protection unit 27 integrates the heat accumulation integral. The heat accumulation integral is based on the continuous integration from the load start to the current time t.

[0062] A plug-in sleeve is embedded on the left side of the composite plate. The axis of the plug-in sleeve coincides with the center of the busbar trough 25. The base 35 is fixedly installed at the bottom of the outer wall of the outer shell 32. Two parallel guide rails are opened at the bottom of the outer wall of the base 35. The wireless charging coil is filled in the guide rail groove. The acoustic phased array probe is embedded at the end of the guide rail. The wireless charging coil relies on the electromagnetic field in the air gap to couple the access coil of the acoustic phased array probe.

[0063] Furthermore, firstly, the main body of the transformer is assembled from independent modules M1 to M3. The M1 and M2 modules are connected in parallel through an epoxy resin cast busbar 25. The conductors inside the busbar 25 are made of three layers of copper laminates with multiple layers of staggered overlap. The splicing surfaces are aligned and fixed by positioning pins. The positioning pins and the surrounding area are covered with sealing strips. The branch of the busbar 25 is connected to the M0 spare module, and the node is equipped with a disconnect switch 26 to support hot-swappable capacity expansion.

[0064] Then, the overload protection unit 27 integrates a thermal accumulation integral algorithm, Taccum=∫0t(Iload / Irated)2dt, to calculate the integral heat from the start of the load to the current time t in real time. When the accumulated value exceeds the set threshold, the disconnect switch 26 automatically cuts off the M0 module and balances the current of the remaining module through the graphene current sharing ring.

[0065] Finally, the outer shell 32 adopts a double-layer structure. The inner aluminum alloy frame 33 has an embedded insulating support component in the mesh, and the outer layer is coated with fluorocarbon resin. Dry nitrogen is introduced through the circulation pipe, and the internal micro-positive pressure environment is maintained through the vent hole to prevent moisture intrusion. When the four modules are 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 78dB to 72dB.

[0066] Please see Figure 1 , Figure 3 and Figure 5 The present invention provides an embodiment of an ultra-large capacity dry-type transformer with variable load. The auxiliary core column 2 has a compensation wire group wound on its outer wall. A power electronic module 36 is nested at the bottom of the auxiliary core column 2. A sub-box 37 is fixedly installed on the side of the conductor where the low-voltage winding 9 is located. A control module is embedded in the inner wall of the sub-box 37 via guide rail clips. The power electronic module 36 is connected to the first end of the compensation wire group and shares a common ground. The input side of the power electronic module 36 is connected to the neutral point tap at the bottom of the auxiliary core column 2 via an insulated copper busbar. The control module is rigidly connected to the auxiliary core column 2 via a corrugated pipe.

[0067] 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 is composed of a U-shaped magnetic conductor. The open end of the U-shaped magnetic conductor is connected to the side of the main iron core column 1 and the top of the auxiliary iron core column 2 through a wedge joint. A permanent magnet array is embedded inside the U-shaped magnetic conductor. The N and 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 adjustment rod 39 is led out from the end of the shielding layer and extends to the side of the outer wall of the transformer shell 32.

[0068] Furthermore, firstly, the damping mechanism 28 adopts a double-layer design: the first layer of damping pads 29 is fixed to the iron core column base by bolts, and the second layer of elastic body 30 wraps the electromagnetic coil. The input end of the coil is connected to a vibration sensor, which collects the vibration spectrum and dynamically adjusts the damping force of the electromagnetic coil to suppress low-frequency resonance.

[0069] Then, a silencing ring 31 is installed at the end of the winding, and the inside is filled with porous sound-absorbing cotton. Adjacent rings are connected through a Helmholtz resonant cavity 62. The conical resonator and the cylindrical resonator are connected in series. 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 turns, the piston retracts. The U-shaped magnetic conductor of the adjustable magnetic flux branch 38 is embedded with 5 sets of alternating NS permanent magnets. The permalloy shielding layer is translated through the adjustment rod 39. When the low voltage side voltage fluctuates by ±5%, the servo system drives the adjustment rod to move, and the magnetic flux compensation reaches 8% of the main magnetic flux.

[0070] Finally, three sets of orthogonal autocoupling coils are wound on 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 output end is connected to the power electronic module 36 through a rotary terminal block. Liquid metal conductive medium is filled between the moving and stationary contacts. The worm gear mechanism drives the stepper motor to adjust the coupling degree.

[0071] Working principle: First, the main core column 1 and the auxiliary core column 2 form a composite magnetic circuit through a closed-loop magnetic yoke. The amorphous alloy strip 20 of the main core column 1 and the nanocrystalline filled joint of the auxiliary core column 2 work together 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. The moving silicon steel sheet group of the tap adjustment mechanism adjusts the effective cross-sectional area of ​​the core. At the same time, the three-stage graded structure of the low-voltage winding 9 is combined and switched by the magnetically controlled vacuum circuit breaker 10. The gradually changing cross-section copper busbar of the L2 section and the difference in cross-sectional area between L1 and L3 form a current gradient distribution. Combined with the parallel sub-winding structure of the high-voltage winding 5, the switching ratio of each winding is controlled by the decoder to adjust the capacity in stages.

[0072] During operation, the guide vanes 15 of the annular heat dissipation duct 14 automatically adjust their tilt angle based on feedback from the temperature rise probe, driving forced convection within the porous ceramic coating. The phase change energy storage tube of the secondary cooling unit simultaneously absorbs peak heat in the airflow channel, while the semiconductor cooling chip between the winding layers provides directional cooling to the contact area, forming a multi-level thermal management system. The modularly designed independent unit achieves lossless capacity expansion through orthogonal cross-shaped copper busbars and graphene flow equalization rings. The overload protection unit 27 predictively cuts off faulty modules using a thermal accumulation integral algorithm, while the backup module seamlessly switches over using a liquid metal conductive medium. The electromagnetic-mechanical composite damping mechanism 28 and the Helmholtz resonant cavity form a series silencing group, suppressing magnetostrictive vibration of the iron core while eliminating noise at specific frequencies through an adjustable piston. The passive LC resonant sensor 22 monitors the electromagnetic-mechanical state, generates a three-dimensional field distribution map through a thermo-mechanical coupling algorithm, and finally compensates and regulates the auxiliary magnetic circuit through the orthogonal autocoupling coil of the power electronics module 36.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-capacity dry-type transformer with variable load, characterized in that: It includes three sets of main iron core columns (1) and three sets of auxiliary iron core columns (2). The top and bottom of the outer walls of the main iron core columns (1) and the auxiliary iron core columns (2) are each fixedly installed with a magnetic yoke (3). The magnetic yokes (3) are connected to form a closed-loop magnetic circuit. The main core column (1) has a stepped cross section. The main core column (1) is made of three layers of amorphous alloy strips (20) stacked inside. The thickness of the middle layer of the three layers of amorphous alloy strips (20) is 1.2 to 1.5 times that of the two side layers. The lamination group inside the auxiliary core column (2) has independent overlapping pieces (4) at the joint. The overlapping gap between the overlapping piece (4) and the lamination group is filled with iron-based nanocrystals. The top thickness of the magnetic yoke (3) is 10 mm less than the bottom thickness. The joint surface of the magnetic yoke (3) and the 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 main iron core column is fitted 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 consists of a copper foil conductor (6) and a stranded wire (7). The outer wall of the copper foil conductor (6) is wrapped with multiple strands of stranded wire (7). The copper foil conductor (6) and the stranded wire (7) are bonded together 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). The stranding distance between the stranded wires (7) is set to 2 to 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 are wound in layers on the outer wall of the iron core column. The ends of the three sections are connected to the two ends of the magnetically controlled vacuum circuit breaker (10). The magnetic control coil of the magnetically controlled vacuum circuit breaker (10) connected to each section is connected to the decoder through the control line. The connection between the magnetically controlled vacuum circuit breaker (10) and the winding conductor is covered with a boron nitride ceramic insulation layer (11). The boron nitride ceramic insulation layer (11) has reserved holes for the control line. The cross-sectional area of ​​the conductor of section L1 is 1.5-2 times that of section L3. The conductor of section L2 adopts a trapezoidal copper busbar with a gradually changing cross section. An epoxy glass cloth transition layer is set between the layers of the three sections of winding. An axial heat dissipation channel (40) is opened on the outer surface of the transition layer. The heat dissipation channel (40) is embedded with a semiconductor cooling chip. The cold end of the semiconductor cooling chip is attached and extends to the contact area of ​​the magnetically controlled vacuum circuit breaker (10).

3. A variable-load, ultra-large capacity dry-type transformer according to claim 2, characterized in that: The boron nitride ceramic insulating layer (11) is mainly composed of a modified silicone rubber matrix, in which boron nitride nanosheets (12) and silicon carbide fibers (13) with a mass fraction of 5% to 8% are uniformly distributed. The outer walls of the high voltage winding (5) and the low voltage winding (9) are provided with annular heat dissipation ducts (14). The inner wall of the annular heat dissipation ducts (14) is sprayed with a porous ceramic coating. The porosity of the porous ceramic coating is set to 40% to 60%. The annular heat dissipation ducts (14) are connected to the centrifugal fan through an integrated annular bracket (16). A gear ring (18) is fixedly installed on the inner side of the integrated annular bracket (16). The gear ring (18) meshes with a 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 the guide vane (15). The guide vane (15) is circumferentially distributed and has an inclination angle of 15° to 45°. A temperature rise probe is embedded in the inner wall of the annular heat dissipation ducts (14). The temperature rise probe is connected to the controller through a twisted pair cable.

4. The ultra-large capacity dry-type transformer with variable load according to claim 1, characterized in that: A magnetic separator (19) is provided between the core column and the winding. The magnetic separator (19) is alternately stacked with an amorphous alloy strip (20) and insulating paper (21), and the stacking ratio is set to 1:

3. The inner layer 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. A 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). The passive LC resonant sensor (22) includes an amorphous thin strip and a polyimide film. The amorphous thin strip is attached to the outer surface of the conductors of the high voltage winding (5) and the low voltage winding (9). 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) transmits data to the external monitoring module (23) via a near-field coupling antenna. The coupling antenna is fixedly wound around the end insulating brackets of the high-voltage winding (5) and the low-voltage winding (9). The monitoring module (23) has a built-in thermo-mechanical coupling algorithm, which generates a three-dimensional temperature rise field and deformation field distribution map. 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 the magnetically controlled vacuum circuit breaker (10) via a cable.

6. A variable-load, ultra-large capacity dry-type transformer according to claim 1, characterized in that: The transformer body is provided with an outer shell (32). The transformer body is assembled from independent modules. The independent modules include M1 to Mn modules. The M1 module and the M2 module are connected in parallel to expand capacity through an epoxy resin cast busbar trunking (25). Conductors are fixedly installed on the inner wall of the busbar trunking (25). The conductors in the busbar trunking (25) are formed by multiple layers of laminated sheets. Positioning pins are fixedly installed on the splicing surface of the M1 module and the M2 module. Sealing strips are fixedly attached to the outer wall of the positioning pins. The busbar trunking (25) at the splicing surface is provided with a port connected to the overload protection unit (27). The M0 spare module is connected to the branch of the bus trunking (25). The disconnect switch (26) is fixedly installed at the node of the M0 spare module and the branch of the bus trunking (25). The disconnect switch (26) is connected to the overload protection unit (27) through a cable. The overload protection unit (27) integrates thermal accumulation integral. The thermal accumulation integral is based on the continuous integration from the start of the load to the current time t.

7. A variable-load, ultra-large capacity dry-type transformer according to claim 1, characterized in that: The main core column (1) and the auxiliary core column (2) are fixedly installed with a damping mechanism (28) at the bottom of the outer wall. The damping mechanism (28) is set in two layers. The first layer is set with a damping pad (29) and fixed to the base of the main core column (1) and the auxiliary core column (2) by bolts. The second layer is set with an elastic body (30). The elastic body (30) is fixedly installed at the bottom of the outer wall of the damping pad (29). The elastic body (30) is wrapped with an electromagnetic coil. The input port of the electromagnetic coil is led out and connected to the vibration sensor. The vibration sensor is embedded in the bottom of the damping pad (29). A silencing ring (31) is fixedly installed at the end of the winding. The silencing ring (31) is filled with porous sound-absorbing cotton. Each adjacent layer of silencing ring (31) is connected by a Helmholtz resonant cavity.

8. A variable-load, ultra-large capacity dry-type transformer according to claim 6, characterized in that: The outer shell (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 support components. The outer layer is coated with fluorocarbon resin. Ventilation holes are reserved at the bottom of the inner side of the aluminum alloy frame (33). The aluminum alloy frame (33) is connected to the circulation pipe through the ventilation holes. Dry nitrogen is introduced into the circulation pipe. The composite plate is fixedly installed on the outer wall of the aluminum alloy frame (33) through a back bolt structure. A guide groove is reserved at the splice of the composite plate. The generator electrode (34) is fixedly installed on the inner wall of the outer shell (32) along the circumference. A plug-in sleeve is embedded on the left side of the composite plate. The axis of the plug-in sleeve coincides with the center of the busbar groove (25). The base (35) is fixedly installed at the bottom of the outer wall of the outer shell (32). Two parallel guide rails are opened at the bottom of the outer wall of the base (35). The wireless charging coil is filled in the guide rail groove. The acoustic phased array probe is embedded at the end of the guide rail. The wireless charging coil relies on the electromagnetic field in the air gap to couple the access coil of the acoustic phased array probe.

9. A variable-load, ultra-large capacity dry-type transformer according to claim 1, characterized in that: The auxiliary core column (2) has a compensation wire group wound on its outer wall, the auxiliary core column (2) has a power electronic module (36) nested at its bottom, the sub-box (37) is fixedly installed on the side of the conductor where the low voltage winding (9) is located, and the control module is embedded in the inner wall of the sub-box (37) through the guide rail buckle. The power electronic module (36) is connected to the first end of the compensation line group and is grounded at the same time. 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) through an insulated copper busbar. The control module is rigidly connected to the auxiliary iron core column (2) through a corrugated pipe.

10. A 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 core column (1) and the auxiliary core column (2). The adjustable magnetic flux branch (38) is composed of a U-shaped magnetic conductor. The open end of the U-shaped magnetic conductor is connected to the side of the main core column (1) and the top of the auxiliary core column (2) through a wedge joint. A permanent magnet array is embedded inside the U-shaped magnetic conductor. The N and N poles of the permanent magnet array are arranged alternately along the axis. The outer wall of the permanent magnet array is wrapped with a permalloy shielding layer. An adjustment rod (39) is led out from the end of the shielding layer. The adjustment rod (39) extends to the side of the outer wall of the transformer shell (32).

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