Emergency mobile high-temperature superconducting transformer with air gap and light weight core

Abstract

The present application relates to a kind of light-weight iron core emergency mobile high-temperature superconducting transformer with air gap, belong to superconducting transformer technical field.It includes light-weight iron core with air gap, superconducting high-low voltage winding;The transformer core is composed of multiple air gaps, winding part is superconducting winding, and its high-low voltage winding inner iron core with air gap;Light-weight iron core superconducting mobile transformer with air gap except using superconducting winding, winding weight is reduced compared with copper winding, light-weight iron core with air gap also makes the weight of the transformer drop significantly, using the advantage of superconducting transformer, while the core adopts split design, greatly reduce the height limit of transformer transportation, break through the weight bottleneck of mobile transformer, can be applied in emergency power supply, substation reconstruction and expansion and equipment maintenance, while can better improve the problem of air core and partial iron core superconducting transformer leakage magnetic, reduce loss.

Description

Technical Field

[0001] This invention relates to a lightweight, mobile, high-temperature superconducting transformer with an air gap and an iron core, belonging to the field of superconducting transformer technology. Background Technology

[0002] With the increasing demand for reliable power supply and the growing requirement for uninterrupted power hours, mobile substation technology has seen a rapidly growing market demand and has become a key piece of equipment added to power grids in recent years. It is particularly suitable for situations where traditional power supply solutions cannot guarantee power supply, such as substation renovation, expansion, or maintenance requiring short-term replacement of equipment under maintenance; major natural disasters necessitating rapid power restoration; seasonal high loads, major holidays, events, temporary increases in electricity consumption at large construction sites when substation capacity is insufficient; and remote or inaccessible areas requiring extended short-term emergency power supply. In these cases, the rapid deployment of mobile substations for emergency power supply is an ideal technical solution.

[0003] On the other hand, in plateau regions, transportation conditions are worse than in plains areas. The demands for emergency rescue, maintenance, and temporary power supply at large construction sites far from power sources place higher requirements on the size and weight of mobile transformers. The contradiction between transportation limitations and capacity has become a key bottleneck hindering the development of mobile transformer technology. However, currently designed, manufactured, and deployed mobile transformers are mostly 35-110kV with capacities of approximately 20-50MVA. Further increasing capacity under the constraints of road transportation is extremely difficult.

[0004] While the application of superconducting technology to transformer coils has led to reductions in size and weight, a significant portion of the transformer's weight comes from the iron core. Therefore, the design concept of superconducting transformers with a partial iron core has gradually come into the researchers' view. Simulation and experimental studies have been conducted both domestically and internationally; however, the results have not been entirely satisfactory. Although the iron core weight is reduced, the magnetic circuit of partially iron-core or air-core transformers requires air passage, resulting in higher leakage flux and greater losses, directly affecting the energy transfer efficiency of the transformer under load. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a lightweight iron core emergency mobile high temperature superconducting transformer with air gap, so as to solve the problem that the capacity of existing mobile transformers is difficult to increase under the road transportation restrictions, and that some iron core or air core superconducting transformers have large leakage flux.

[0006] The technical solution of this invention is: a lightweight, portable, high-temperature superconducting transformer with an air gap, comprising an air-gap core, a superconducting coil, a cryogenic container, a cryogenic cooling device, and a bushing, wherein:

[0007] The air-gap iron core includes at least one or more air gaps and is made of stacked silicon steel sheets;

[0008] Preferably, the number of air gaps is related to the actual voltage level and weight requirements of the superconducting transformer, and there is no fixed number of air gaps.

[0009] Preferably, the air gap may exist only in the core column, the yoke, or both. The size of the air gap spacing is related to the voltage level and weight requirements of the high-temperature superconducting transformer, and there is no fixed air gap spacing.

[0010] Preferably, the gap filler in the air gap is not limited to air, but can be filled with a material with good electrical properties as needed;

[0011] Preferably, the iron core is designed to be detachable, with the upper and lower yokes and the iron core column with air gap being detachable and reassembled, and the upper and lower yokes having reserved mounting grooves for the iron core column.

[0012] Preferably, the air-gap iron core column is fitted with a bracket with good electrical performance, and the air-gap iron core, i.e. its filler, is installed into the bracket during assembly.

[0013] Furthermore, the core diameter should meet the following requirements:

[0014]

[0015] In the formula, This represents the voltage at each terminal of the transformer. f is the current per column; f is the frequency. Number of coil turns For maximum magnetic flux density, Let be the cross-sectional area of ​​the iron core column. For conductor current density, The cross-sectional area of ​​the conductor is...

[0016] in ; ;

[0017] From the above, we can deduce that:

[0018]

[0019] In the formula, (mm) is the core diameter. This is an empirical coefficient that varies with the power supply frequency, core flux density, and structure. For single-phase double windings, it is generally taken as 52-57.

[0020] (kVA) is the computing capacity. (kVA) and the number of winding cores The ratio:

[0021]

[0022] Furthermore, let the diameter of the iron core be... The series is The angle between the lines connecting each vertex to the origin and the x-axis is... ( =1, 2, 3…k), which can be used to obtain the width of any level of the frame. ;and sheet thickness They are respectively:

[0023]

[0024]

[0025] According to the formula for the area of ​​a rectangle, the area of ​​any level of iron core can be obtained. for:

[0026]

[0027] Summing the areas of all series yields the cross-sectional area of ​​the iron core column. for:

[0028]

[0029] Furthermore, the air gap volume Cross-sectional area of ​​the iron core column air gap spacing The accumulation of:

[0030]

[0031] The superconducting coil contains at least two sets of coils, one high-voltage and one low-voltage, and the coils are at a certain distance from the air gap.

[0032] Preferably, the superconducting coil is wound from second-generation high-temperature superconducting tape and placed in a cryogenic cooling device.

[0033] The cryogenic container is made of high-strength, high-density non-metallic material. The cryogenic container is an annular cryogenic device with a room temperature aperture (for the iron core to pass through) in the center. The superconducting winding and the annular cryogenic container are sleeved on the iron core column.

[0034] Preferably, the aluminum foil layer of the heat insulation and radiation protection layer between the inner wall and the outer wall vacuum space of the cryogenic container Dewar adopts an insulating separation or a slit (discontinuous) structure to avoid the formation of short-circuit loops.

[0035] Preferably, the cryogenic container uses a molecular sieve (insulating material) as a getter.

[0036] The cryogenic cooling device adopts an open immersion cooling method, in which liquid nitrogen is placed inside the cryogenic container;

[0037] Preferably, the liquid nitrogen is consumed in one go, and is evacuated by a vacuum pump. Since liquid nitrogen is a harmless gas, it flows through a heat exchanger and the vaporized liquid nitrogen is directly discharged into the atmosphere.

[0038] The bushing consists of a high-voltage bushing and a low-voltage bushing. The conductor-current lead in the bushing provides electrical connection for low-temperature and room-temperature environments. It is made of current-carrying conductors and insulating materials such as silicone rubber or ceramic and filled with oil or SF6 gas.

[0039] The beneficial effects of this invention are:

[0040] 1. This invention combines a mobile transformer with high-temperature superconducting technology. Although its principle is the same as that of a traditional transformer, it uses high-temperature superconducting materials as coil conductors, resulting in significant differences in both conductor structure and cooling methods. Superconducting tapes have a higher current-carrying capacity per unit area, which can significantly reduce the overall size and weight of the transformer. The use of high-temperature superconducting wires makes the superconducting transformer smaller in volume, total loss, and coil winding quantity compared to a traditional transformer with the same V / T value. Furthermore, compared to copper windings immersed in transformer oil, the use of pollution-free and flame-retardant liquid nitrogen-immersed superconducting windings greatly improves safety and environmental friendliness.

[0041] 2. This invention is designed for mobile emergency use, where continuous operation typically lasts only a few days to a few months. This avoids the drawbacks of long-term operation of superconducting equipment, such as the need for large auxiliary cryogenic systems and complex maintenance. Therefore, applying high-temperature superconducting technology to mobile transformers can leverage the advantages of superconductivity—lightweight design and high current density—while circumventing the high cryogenic system requirements for long-term operation.

[0042] 3. The air-gap core proposed in this invention further reduces the size and weight of high-temperature superconducting transformers, breaking through the upper limits of conventional technology in terms of capacity and voltage level. When applied to low voltage levels, it can be further miniaturized, significantly reducing the space requirements for transportation and deployment. Furthermore, the air-gap core greatly solves the problem of high leakage flux in some core or air-core transformers caused by the absence of a core, reducing transformer losses and improving transformer efficiency while decreasing size and weight.

[0043] 4. The modular iron core proposed in this invention can further reduce the restrictions on transportation height. It can be disassembled and transported in areas with poor transportation conditions, and assembled on site. It can be used for emergency power supply maintenance in remote mountainous areas, and is not restricted by transportation conditions. It can be disassembled and transported immediately, and can be installed and used immediately. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0045] Figure 1 A schematic diagram of a lightweight, mobile, high-temperature superconducting transformer with an air gap and an emergency core, provided as an embodiment of the present invention;

[0046] Figure 2 A schematic cross-sectional view of a lightweight, mobile, high-temperature superconducting transformer with an air gap provided in an embodiment of the present invention.

[0047] Figure 3 A schematic diagram of the structure of a single-phase lightweight iron core emergency mobile high-temperature superconducting mobile transformer with air gap provided in an embodiment of the present invention;

[0048] Figure 4 A schematic diagram of the structure of a three-phase lightweight iron core emergency mobile high-temperature superconducting mobile transformer with air gap provided in an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of a detachable iron core structure provided in an embodiment of the present invention.

[0050] Figure 1-5 In Chinese, the specific symbols are represented as follows:

[0051] 1-Lightweight high-temperature superconducting mobile transformer with air gap and iron core; 11-Iron core; 12-Low-voltage winding; 13-High-voltage winding; 14-High-voltage bushing; 15-Low-voltage bushing; 16-Exhaust port; 17-Shell; 18-Air gap filler; 191-High-voltage lead; 192-Low-voltage lead; 2-Transformer cross-section; 21-Air-gap core; 22-Low-voltage winding; 23-High-voltage winding; 24-Inner wall; 25-Outer wall; 26-Multi-layer insulation; 27-Vacuum; 28-Cryogenic medium; 3-Single-phase lightweight air-gap core high-temperature superconducting mobile transformer; 31-Air-gap core; 4-Three-phase lightweight air-gap core high-temperature superconducting mobile transformer; 41-Air-gap core; 5-Schematic diagram of detachable core; 51-Air gap filler; 52-Detachable air-gap core; 53-Detachable upper yoke; 54-Detachable lower yoke. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0054] See Figure 1 The present invention provides a schematic diagram of a lightweight, air-gap-equipped, mobile high-temperature superconducting transformer with an emergency high-temperature superconducting core. The high-temperature superconducting mobile transformer includes an air-gap core, a superconducting coil, a cryogenic container, a cryogenic cooling device, a bushing, an exhaust port, and a shell.

[0055] The air-gap iron core is wrapped by windings and a cryogenic container. The iron core passes through the room temperature hole of the cryogenic container. The iron core is made of stacked silicon steel sheets. The air gap is filled with epoxy resin or a lightweight material with good electrical properties to support the silicon steel sheets outside the air gap.

[0056] In the example described, the core diameter should meet the following technical requirements:

[0057]

[0058] In the formula, (mm) is the core diameter. This is an empirical coefficient that varies with the power supply frequency, core flux density, and structure. For single-phase double windings, it is generally taken as 52-57.

[0059] (kVA) is the computing capacity. (kVA) and the number of winding cores The ratio:

[0060]

[0061] In the example described, the maximum cross-sectional area of ​​the iron core meets the following technical requirements:

[0062] Let the diameter of the iron core be... The series is The angle between the lines connecting each vertex to the origin and the x-axis is... ( =1, 2, 3… This allows us to determine the width of any level of image. ;and sheet thickness They are respectively:

[0063]

[0064]

[0065] According to the formula for the area of ​​a rectangle, the area of ​​any level of iron core can be obtained. for:

[0066]

[0067] Summing the areas of all series yields the cross-sectional area of ​​the iron core column. for:

[0068]

[0069] The air gap volume Cross-sectional area of ​​the iron core column air gap spacing The accumulation of:

[0070]

[0071] The superconducting coil is made of second-generation superconducting tape. A superconducting tape is placed on the same double-panel coil frame, and two single-panel windings are wound in parallel.

[0072] Compared to copper windings, the superconducting coil windings have a stronger current-carrying capacity and smaller winding dimensions.

[0073] The double-pane coil frame is a ring, with two single-pane windings arranged side by side around the ring. Both ends of the coil are on the outermost side of the single-pane windings. The two panes are connected by the middle part of the superconducting strip and are tightly attached to the surface of the frame ring.

[0074] The cryogenic container requires a cryogenic Dewar. The cryogenic Dewar of the high-temperature superconducting transformer is similar in structure to that of a traditional cryogenic Dewar. However, since the cryogenic Dewar used in the superconducting transformer surrounds the magnetic circuit of the transformer core, fiberglass material with good insulation properties is selected. A sandwich layer is set between the inside and outside of the cryogenic container. The heat insulation and radiation protection aluminum foil layer in the sandwich layer needs to be cut and has a certain degree of separation to prevent the formation of short-circuit loops in the sandwich layer.

[0075] The dimensions of the fiberglass Dewar are related to the dimensions of the winding. The inner wall of the Dewar must maintain a certain distance from the iron core and the high-voltage winding, and the outer wall must maintain a certain distance from the outermost low-voltage winding.

[0076] Furthermore, the fiberglass material has gas release characteristics. Since the vacuum in the low-temperature container cannot be maintained for a long time, molecular sieves are placed in the vacuum jacket as getters, and the vacuum is periodically evacuated.

[0077] The cryogenic container is an open immersion cooling system that directly uses open-flowing cryogenic media such as liquid nitrogen or liquid helium to immerse the superconducting coil. After the gas is generated, it is discharged through a gas conduit.

[0078] In this embodiment of the invention, the bushing consists of three high-voltage bushings and three low-voltage bushings. The bushings are mounted on the transformer casing, through which the high-voltage and low-voltage leads are passed and fixed inside the bushings. The bushings are mainly composed of capacitor cores, oil conservators, flanges, and upper and lower porcelain bushings.

[0079] The capacitor core is the main insulation, which is composed of concentric capacitors connected in series. It is enclosed in a sealed container consisting of upper and lower porcelain bushings, oil conservator, flange and base. The container is filled with treated transformer oil, so that the internal main insulation becomes an oil-paper structure.

[0080] The flange is equipped with a vent plug, an oil sampling device, and a device for measuring the dielectric loss and partial discharge of the bushing.

[0081] The high-voltage and low-voltage leads are composite current leads, i.e., binary current leads. Conventional leads are used in the room temperature range, while leads made of high-temperature superconductors are used in the low-temperature range.

[0082] Furthermore, the low-temperature section of the high-voltage lead is connected to the high-temperature superconducting winding and then to the high-voltage bushing, while the low-temperature section of the low-voltage lead is connected to the high-temperature superconducting winding and then to the low-voltage bushing.

[0083] The high-temperature superconducting transformer casing is made of epoxy resin in a double-layer sealed shell, with a metallized corrugated foil insulation material placed in between. Simultaneously, this casing must meet the corresponding electrical and mechanical strength requirements and must not deform or crack at low temperatures.

[0084] like Figure 2 As shown, in this embodiment, the high-temperature superconducting high and low voltage windings are immersed in a low-temperature medium, and there is a certain gap between the high and low voltage windings. The iron core passes through the room temperature hole reserved in the low-temperature container. The low-temperature container Dewar has an inner wall and an outer wall, and there is a vacuum interlayer between the inner and outer walls. There are multiple layers of heat insulation in the interlayer.

[0085] The cryogenic medium should not be exactly level with the top of the cryogenic container, but should extend above the superconducting coil to be immersed.

[0086] The multi-layer insulation layer needs to be separated by cutting the aluminum foil of the insulation and radiation protection layer to prevent the formation of short-circuit rings.

[0087] The high and low voltage windings are placed in a cryogenic container and completely immersed in a cryogenic medium, with the low voltage winding placed inside the high voltage winding.

[0088] like Figure 3 As shown in the diagram of a single-phase high-temperature superconducting transformer with an air gap, the air gap is evenly distributed in the core. There is only one cryogenic container that holds the high and low voltage windings. The windings are immersed in a cryogenic medium. Only the central core passes through the room temperature hole reserved in the cryogenic container. The air gap can be set on the central core, but it is not limited to the central core. It can be set in various parts of the core according to specific needs.

[0089] The air gap serves as a support for the silicon steel sheet. The air gap needs to be filled with a lightweight material with good electrical properties, such as epoxy resin. The number of air gaps is determined according to actual needs.

[0090] like Figure 4 As shown in the diagram, in the structure of a three-phase high-temperature superconducting transformer with air gap, the air gap is similar to that of a single-phase transformer and is also evenly distributed in the core. There are three low-temperature containers, which respectively hold three sets of high and low voltage superconducting coil windings.

[0091] The superconducting coil winding is immersed in a cryogenic medium, and the three central iron cores pass through the room temperature holes reserved in the cryogenic container.

[0092] The air gap can be set at any part of the iron core, and the number of air gaps should be set according to actual needs, but it should include at least one air gap.

[0093] like Figure 5 As shown in the schematic diagram of the detachable iron core, the upper and lower yokes of the iron core, the air gap and the air gap filler can all be disassembled and transported. The iron core with the air gap in the middle column is directly inserted into the grooves of the upper and lower yokes of the iron core.

[0094] The upper and lower yoke grooves are pre-reserved for inserting the central column iron core during manufacturing, and the upper and lower yokes are disassembled and reassembled during transportation.

[0095] The air gap and air gap filler are made using a support with good electrical performance. During installation, the air gap core is directly placed into the support for assembly.

[0096] Of course, the air-gap core structure provided in this embodiment can also be applied to other high-temperature superconducting power transformer devices, which will not be elaborated here.

[0097] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0098] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A lightweight, mobile, high-temperature superconducting transformer with an air gap and an emergency-use core, characterized in that: Includes air-gap iron core, high-temperature superconducting coil, cryogenic container, cryogenic cooling device, and bushing, wherein: The air-gap iron core contains at least one air gap, which is evenly distributed on the iron core. Each air gap is filled with material to support the silicon steel sheets of the iron core. The entire iron core can be disassembled for transportation. The high-temperature superconducting coil comprises at least two coils, namely a high-voltage winding and a low-voltage winding; The cryogenic container is used to hold the superconducting coil and has a room temperature hole in the center. The cryogenic cooling device is an open immersion cooling system that stores a cryogenic medium, in which the superconducting coil is immersed. The bushings are high-voltage bushings and low-voltage bushings. The high-voltage bushings lead out the high-voltage winding leads, and the low-voltage bushings lead out the low-voltage winding leads. The bushings are placed on the top of the transformer casing. The air-gap core is made of stacked silicon steel sheets with uniformly distributed air gaps. Epoxy resin is filled in the air gaps to support the silicon steel sheets.

2. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 1, characterized in that: The high-temperature superconducting coil is a double-pancake coil wound from high-temperature superconducting second-generation tape. Adjacent high-temperature superconducting double-pancake coils are spaced apart in the axial direction, and there is also a distance between the high-voltage and low-voltage windings. The coil is placed in a cryogenic container.

3. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 1, characterized in that: The cryogenic container is annular with a room temperature hole in the center. There is a vacuum space between the inner and outer walls of the cryogenic container. The iron core passes through the room temperature hole, and the high-temperature superconducting winding and the cryogenic medium are placed in the container.

4. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 1, characterized in that: The cryogenic cooling device uses a flowing cryogenic medium to cool the superconductor and includes a cryogenic medium inlet and a gas evaporation outlet.

5. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 1, characterized in that: The leads of the transformer windings must pass through insulating bushings and be fixed in place. The main insulation is provided by capacitor cores, which are composed of concentric capacitors connected in series and enclosed in a sealed container consisting of upper and lower porcelain bushings, oil conservator, flanges, and a base.

6. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 3, characterized in that: All superconducting transformers are made of fiberglass, and the inner and outer walls of the cryogenic container inside the superconducting transformer are provided with a vacuum interlayer and a heat insulation and radiation protection layer.

7. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 6, characterized in that: Molecular sieves are used as getters within the vacuum interlayer.

8. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 6, characterized in that: The heat insulation and radiation protection layer is provided with aluminum foil, and the aluminum foil needs to have "cuts", that is, to divide the aluminum foil.

9. The lightweight, mobile, high-temperature superconducting transformer with an air gap as described in claim 1, characterized in that: The cryogenic medium is liquid nitrogen or liquid helium, which is directly poured into the cryogenic container.

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