A compact three-phase superconducting air-core reactor

Abstract

The present invention relates to a compact three-phase superconducting hollow-core reactor, comprising a vacuum insulation container containing a cooling medium, a vacuum insulation shell and a vacuum insulation cover, the vacuum insulation cover being provided with a plurality of suspension rods extending into the vacuum insulation shell; a three-phase superconducting magnet immersed in the cooling medium, the three-phase superconducting magnet being composed of three single-phase superconducting magnets spaced apart and arranged on the plurality of suspension rods in a vertical stacking manner, the single-phase superconducting magnet being a hollow structure without an iron core; a cryogenic bushing assembly having three groups corresponding one to one with the single-phase superconducting magnets, each group of cryogenic bushing assemblies comprising two cryogenic bushings, the cryogenic bushing portion extending from the outside of the vacuum insulation cover into the vacuum insulation shell, the end of the cryogenic bushing outside the vacuum insulation shell being connected to the power grid, and the end inside the vacuum insulation shell being connected to the corresponding single-phase superconducting magnet via a current lead. The present invention expands the application scenarios of the reactor and effectively solves the problem of insufficient reactive power compensation in the power grid.

Description

Technical Field

[0001] The present invention relates to the field of superconducting power applications, and in particular to a compact three-phase superconducting air-core reactor. Background Art

[0002] As urban power grids increasingly use underground overhead lines and cables, the problem of insufficient inductive reactive power compensation becomes increasingly prominent. Voltages in many locations are exceeding limits, threatening the safe operation of the power grid. The need for local reactive power consumption is urgent. Shunt reactors are an effective solution for local reactive power consumption. However, existing conventional reactors require large floor space and generate high noise levels, making retrofitting old substations with limited storage space difficult. Summary of the Invention

[0003] The purpose of the present invention is to provide a compact three-phase superconducting hollow-core reactor in order to overcome at least one of the above-mentioned deficiencies in the prior art. This compact three-phase superconducting hollow-core reactor is a three-phase winding made of superconducting tape. The reactor is cooled by a cooling medium to a temperature at which the superconducting tape enters a superconducting state. By utilizing the high current-carrying capacity of the superconducting material and the vertical stacking of the three-phase winding, the reactor's footprint and volume are effectively reduced. Furthermore, the coreless structure not only reduces the reactor's noise level from 75 decibels compared to conventional iron-core reactors to below 60 decibels, but also features low magnetic leakage, greatly expanding the reactor's application scenarios and effectively solving the problem of insufficient reactive power compensation in the power grid.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A compact three-phase superconducting air-core reactor, comprising:

[0006] A vacuum insulation container containing a cooling medium, the vacuum insulation container comprising a vacuum insulation shell and a vacuum insulation cover, the vacuum insulation cover being provided with a plurality of suspension rods extending into the vacuum insulation shell;

[0007] A three-phase superconducting magnet, immersed in the cooling medium, composed of three single-phase superconducting magnets spaced apart and stacked vertically on a plurality of the suspension rods, the single-phase superconducting magnet being a coreless hollow structure;

[0008] Cryogenic sheath assemblies, there are three groups of cryogenic sheath assemblies and they correspond one to one with the single-phase superconducting magnets. Each group of cryogenic sheath assemblies includes two cryogenic sheaths. The cryogenic sheaths partially extend from the outside of the vacuum insulation cover into the vacuum insulation shell. The ends of the cryogenic sheaths outside the vacuum insulation shell are connected to the power grid, and the ends inside the vacuum insulation shell are connected to the corresponding single-phase superconducting magnets through current leads.

[0009] Furthermore, the vacuum insulation shell is a double-layer structure shell with vacuum extraction between layers, and a cooling medium inlet and a cooling medium outlet are provided on the side wall of the vacuum insulation shell. The cooling medium inlet and the cooling medium outlet are connecting pipes with a bellows structure.

[0010] Furthermore, the cooling medium outlet is arranged on one side near the bottom of the vacuum insulation shell, and a cooling medium pipeline is surrounded by the periphery of the inner shell of the vacuum insulation shell.

[0011] Furthermore, the single-phase superconducting magnet includes an upper fixing plate and a lower fixing plate arranged in parallel, and a coil assembly arranged between the upper fixing plate and the lower fixing plate; the coil assembly includes a pair of inner support rings and a pair of outer support rings arranged concentrically, and a plurality of superconducting magnet coils arranged in a ring shape and spaced apart between the pair of inner support rings and the pair of outer support rings.

[0012] Furthermore, the superconducting magnet coil includes: a skeleton; a skeleton lower cover plate and a skeleton upper cover plate respectively arranged on the outer edges of both sides of the skeleton; a dividing plate arranged between the skeleton lower cover plate and the skeleton upper cover plate, the area enclosed by the dividing plate and the skeleton lower cover plate is a first cavity, and the area enclosed by the dividing plate and the skeleton upper cover plate is a second cavity; a winding wire, the winding wire includes a first winding wire arranged in the first cavity and a second winding wire arranged in the second cavity, and the innermost turns of the first winding wire and the second winding wire are connected through the gap of the dividing plate.

[0013] Furthermore, the superconducting magnet coil also includes: a copper connector, which is arranged on the lower cover plate of the skeleton and the upper cover plate of the skeleton, and is used to connect to the current lead; a skeleton connecting plate, which is arranged on the lower cover plate of the skeleton and the upper cover plate of the skeleton, and is used to connect to the pair of outer support rings; a support rod, which is arranged on the lower cover plate of the skeleton and the upper cover plate of the skeleton, and is used to connect to the pair of inner support rings.

[0014] Furthermore, the upper fixing plate, the lower fixing plate, the inner support ring and the outer support ring are made of G10 glass fiber material.

[0015] Furthermore, the upper fixing plate, the lower fixing plate and the superconducting magnet coil have a hollow structure.

[0016] Furthermore, the superconducting magnet coil is one of a circular coil, a D-shaped coil, an inverted D-shaped coil or a racetrack coil, preferably a racetrack coil.

[0017] Furthermore, the cryogenic sleeve is divided into two parts, the upper part is left longer to ensure sufficient creepage distance to prevent breakdown, and the lower part is left longer to allow the temperature to transition from the cooling medium temperature to room temperature to prevent frost on the upper part.

[0018] Furthermore, the current leads are hard wires with insulation on the surface, so that the current leads used in each single-phase superconducting magnet are spaced apart from each other and the distance between the ends meets the insulation requirements.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) In the compact three-phase superconducting hollow reactor provided by the present invention, the single-phase superconducting magnet adopts a hollow structure without an iron core, which can effectively reduce vibration, reduce noise, and improve inductance linearity; and the three-phase superconducting magnet is arranged on multiple suspension rods in a vertical stacking manner. Compared with other stacking methods, the vertical stacking can reduce the area of ​​the vacuum insulation cover and reduce heat leakage.

[0021] (2) In the compact three-phase superconducting air-core reactor provided by the present invention, the single-phase superconducting magnet is composed of coils arranged in a ring shape, which can effectively reduce leakage magnetic flux and lower losses.

[0022] (3) In the compact three-phase superconducting hollow reactor provided by the present invention, taking into account the shrinkage and reduction of heat leakage at low temperatures, the cooling medium inlet and outlet are configured as a structure with bellows. At the same time, the inner tube at the cooling medium outlet at the bottom shrinks sharply, and a circle of cooling medium pipelines is formed around the outer side of the inner tube of the cooling medium tank to reduce the impact of low-temperature deformation.

[0023] (4) In the compact three-phase superconducting air-core reactor provided by the present invention, since the three-phase superconducting magnets are in the same space, leakage flux is prone to occur. In order to avoid the increased loss caused by the mutual inductance of the three superconducting magnets, the present invention increases the number of magnet coils, optimizes the shape and size of the coils, and finally selects a runway-type coil and determines the optimal size to minimize the leakage flux. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of a compact three-phase superconducting air-core reactor in an embodiment;

[0025] Figure 2 Schematic diagram of the superconducting coil winding structure in the embodiment, (a) circular, (b) D-type, (c) inverted D-type, (d) racetrack type;

[0026] Figure 3 The annular reactor based on the racetrack-shaped coil winding and the radial space magnetic field distribution when four circuits are connected in parallel in the embodiment;

[0027] Figure 4 Schematic diagram of a single-phase superconducting magnet in an embodiment;

[0028] Figure 5 This is one of the assembly diagrams of a single-phase superconducting magnet in the embodiment;

[0029] Figure 6 This is the second assembly diagram of the single-phase superconducting magnet in the embodiment;

[0030] Figure 7 This is the third assembly diagram of the single-phase superconducting magnet in the embodiment;

[0031] Figure 8 Schematic diagram of a superconducting magnet coil in an embodiment;

[0032] Figure 9 Schematic diagram of a cryogenic sleeve in an embodiment;

[0033] Figure 10 The temperature distribution diagram of the casing in the embodiment;

[0034] Figure 11 This is a schematic diagram of lead fixing in the embodiment;

[0035] Figure 12 The eddy current distribution in the inner cavity of the vacuum insulation container of the reactor in the embodiment;

[0036] Figure 13 The eddy current distribution of the outer cavity of the vacuum insulation container of the reactor in the embodiment;

[0037] Figure 1-9 The bid numbers are as follows: 1-cryogenic sleeve; 2-vacuum insulation cover; 3-cooling medium inlet; 4-vacuum insulation shell; 5-single-phase superconducting magnet; 501-copper connector; 502-upper fixing plate; 503-inner support ring; 504-outer support ring; 505-superconducting magnet coil; 5051-skeleton upper cover plate; 5052-skeleton; 5053-winding wire; 5054-support rod; 5055-channel plate; 5056-channel guard plate; 5057-skeleton lower cover plate; 5058-skeleton connecting plate; 506-lower fixing plate; 507-support column; 6-suspender rod; 7-cooling medium outlet; 8-cooling medium pipeline;

[0038] Figure 10 As shown in the bid numbers: 1-A phase lead; 2-B phase lead; 3-C phase lead; 4-bridge wire; 5-insulating spacer; 6-wire clamp. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0040] Example

[0041] In order to overcome the problem that the existing conventional reactors occupy a large area and are noisy, making it difficult to renovate old substations with insufficient storage space, this embodiment provides a compact three-phase superconducting air-core reactor. The specific structure is shown in Figure 1-10 ,include:

[0042] A vacuum insulated container containing a cooling medium, the vacuum insulated container comprising a vacuum insulated shell 4 and a vacuum insulated cover 2, the vacuum insulated cover 2 being provided with a plurality of suspension rods 6 extending into the vacuum insulated shell 4;

[0043] A three-phase superconducting magnet, which is immersed in the cooling medium and is composed of three single-phase superconducting magnets spaced apart and stacked vertically on a plurality of the suspension rods 6. The single-phase superconducting magnet 5 is a coreless hollow structure.

[0044] Cryogenic sheath assemblies, there are three groups of cryogenic sheath assemblies and they correspond one to one with the single-phase superconducting magnets 5. Each group of cryogenic sheath assemblies includes two cryogenic sheaths 1. The cryogenic sheaths 1 partially extend from the outside of the vacuum insulation cover 2 into the vacuum insulation shell 4. The end of the cryogenic sheath 1 outside the vacuum insulation shell 4 is connected to the power grid, and the end inside the vacuum insulation shell 4 is connected to the corresponding single-phase superconducting magnet 5 through a current lead.

[0045] In this embodiment, the vacuum insulation shell 4 is a double-layer structure with evacuated layers between the layers. A cooling medium inlet 3 and a cooling medium outlet 7 are provided on the sidewalls of the vacuum insulation shell 4. These inlet 3 and outlet 7 are communicating pipes with a bellows structure. Because casings, sensors, and the like require holes to be drilled in the vacuum insulation cover 2, the vacuum insulation cover 2 does not have a double-layer structure.

[0046] In this embodiment, the cooling medium outlet 7 is provided on one side near the bottom of the vacuum insulation shell 4 , and a cooling medium pipeline 8 surrounds the periphery of the inner shell of the vacuum insulation shell 4 .

[0047] In this embodiment, the single-phase superconducting magnet 5 includes an upper fixing plate 502 and a lower fixing plate 506 arranged in parallel, and a coil assembly disposed between the upper fixing plate 502 and the lower fixing plate 506. The coil assembly includes a pair of concentrically arranged inner support rings 503 and a pair of outer support rings 504, and a plurality of superconducting magnet coils 505 arranged in a ring shape and spaced apart between the pair of inner support rings 503 and the pair of outer support rings 504. The upper fixing plate 502 and the lower fixing plate 506 serve as support, the inner support rings 503 and the outer support rings are fixed in place by slots, and the screw locking structure design prevents deformation and displacement of the superconducting magnet coils 505 under electrodynamic forces or external vibrations.

[0048] In this embodiment, the superconducting magnet coil 505 includes: a frame 5052; a frame lower cover plate 5057 and a frame upper cover plate 5051 respectively disposed at the outer edges of the frame 5052; a divider plate 5055 disposed between the frame lower cover plate 5057 and the frame upper cover plate 5051, wherein the area enclosed by the divider plate 5055 and the frame lower cover plate 5057 is a first cavity, and the area enclosed by the divider plate 5055 and the frame upper cover plate 5051 is a second cavity; and winding wires 5053, wherein the winding wires 5053 include a first winding wire disposed in the first cavity and a second winding wire disposed in the second cavity, wherein the innermost turns of the first winding wire and the second winding wire are connected through the gap of the divider plate. A divider guard plate 5056 is also disposed between the frame lower cover plate 5057 and the frame upper cover plate 5051.

[0049] In this embodiment, the superconducting magnet coil 505 also includes: a copper connector 501, which is arranged on the skeleton lower cover plate 5057 and the skeleton upper cover plate 5051 for connecting to the current lead; a skeleton connecting plate 5058, which is arranged on the skeleton lower cover plate 5057 and the skeleton upper cover plate 5051 for connecting to the pair of outer support rings 504; a support rod 5054, which is arranged on the skeleton lower cover plate 5057 and the skeleton upper cover plate 5051 for connecting to the pair of inner support rings 503; a support column 507, which is arranged along the circumferential direction on one side of a pair of outer support rings 504 facing the upper fixed plate 502 and the lower fixed plate 506 respectively, for fixing the pair of outer support rings 504 to the upper fixed plate 502 and the lower fixed plate 506 respectively.

[0050] In this embodiment, the upper fixing plate 502, the lower fixing plate 506, the inner support ring 503 and the outer support ring 504 are made of G10 glass fiber material, which can avoid generating additional operating AC loss and have no additional impact on the spatial magnetic field; the copper connector 501 is made of T2 copper.

[0051] In this embodiment, the upper fixing plate 502, the lower fixing plate 506 and the superconducting magnet coil 505 have a hollow structure, which reduces the weight of the skeleton while ensuring mechanical strength, alleviates the obstruction to the fluidity of the cooling medium during operation, and achieves a convection effect.

[0052] In this embodiment, the superconducting magnet coil 505 is preferably a racetrack-shaped coil. Since the three-phase magnets are coexisting in the same space, special attention must be paid to magnetic flux leakage to prevent increased losses due to mutual inductance among the three magnets. Specific measures include optimizing coil shape and size and increasing the number of magnet coils. However, since optimizing coil size and increasing the number of magnet coils increase the amount of ribbon used, significantly increasing costs, a racetrack-shaped coil shape was ultimately selected after comparison, minimizing ribbon usage while meeting magnetic flux leakage requirements.

[0053] Specifically, for a single-phase ring-topology superconducting reactor, the parameters that determine its structure include the constant overall inductance L, the operating current I op , strip width, coil thickness, and variable parallel branch number p, coil winding number M, the distance R between the coil center and the axis center, and the size and structural parameters of the double-pancake coil winding itself corresponding to each group (p, M, R), including the coil large radius r1, small radius r2, coil turns N and coil thickness × N / 2 determined by the coil turns N and other parameters.

[0054] Based on the demand for compact superconducting shunt reactors, in order to reduce the size of superconducting shunt reactors and reduce the amount of tape used, this embodiment proposes four coil winding structure selections, namely circular, D-type, inverted D-type and racetrack type. Figure 2 Given other key parameters such as overall inductance and operating current amplitude, the design of the magnet that minimizes superconducting shunt reactor tape usage while meeting magnetic flux leakage requirements is determined by comparing reactor dimensions and tape usage based on these four coil unit geometries, thereby optimizing the coil winding structure.

[0055] Table 1 Single-phase dimensions and strip usage when the leakage flux of superconducting shunt reactors based on different coil winding structures meets the requirements when two typical lines are connected in parallel

[0056]

[0057] Taking the example of p = 2 parallel branches, M = 24 coil windings, R = 0.4 m distance from coil center to axis, 6 mm strip width, and 0.44 mm coil thickness, Table 1 shows the dimensions and strip usage of single-phase superconducting shunt reactors based on circular, D-type, inverted D-type, and racetrack coils. It can be seen that changes in the coil winding geometry can significantly improve the overall dimensions of a single-phase toroidal superconducting reactor. Replacing circular coils with racetrack coils achieves the compact size of the superconducting shunt reactor and reduces strip usage.

[0058] Figure 3The annular inductor based on the racetrack-type coil winding and the radial spatial magnetic field distribution when four paths are connected in parallel show that the spatial leakage magnetic field at a radial distance of 1 meter (i.e., about 30 cm outside the winding) is only 0.002 mT, which is much less than 1 mT. This directly indicates that the annular inductor structure based on the racetrack-type coil effectively constrains the magnetic field of the magnet and suppresses the spatial leakage magnetic field. Therefore, the coil winding structure of this embodiment preferably adopts the racetrack-type coil.

[0059] The indirect assessment of the space magnetic flux leakage level is based on the calculation of the eddy current loss of the vacuum insulation container. The inner and outer cavities of the vacuum insulation container are appropriately simplified and regarded as two layers of metal cylinders made of stainless steel. Figure 12-13 The eddy current distributions generated in the inner and outer cavities of a four-way parallel reactor are presented when operating currents of different phases flow through the three phases. The corresponding eddy current losses are calculated to be negligible compared to the AC losses in the reactor coil windings. This indirectly demonstrates that the toroidal reactor structure effectively confines the magnetic field, resulting in virtually no varying magnetic field outside the reactor, thus avoiding additional metal eddy current losses.

[0060] In this embodiment, each phase of the three-phase magnet requires two cryogenic sleeves 1, resulting in a total of six sleeves on the vacuum insulation cover 2. The cryogenic sleeve 1 consists of two parts: the upper part is a copper cylinder insulated with silicone rubber, and the lower part is a copper cylinder wrapped with G10. The two are connected by a stainless steel flange. The upper part is left longer to ensure sufficient creepage distance to prevent breakdown; the lower part is left longer to allow the temperature to transition from the cooling medium temperature to room temperature and prevent frost on the upper part. Considering the space constraints, the minimum upper and lower dimensions were determined through simulation.

[0061] To facilitate simulation, the casing geometry is simplified and meshed as follows: the part that has a significant impact on heat transfer is retained while the edge geometry is ignored. The physical properties of G10 are used to replace silicone rubber. The RRR of the copper used in the simulation is taken as 50. All physical properties are from the NIST official website. The simulation results are shown in Figure 10 .

[0062] See Figure 11 In this embodiment, the current leads are all hard wires with insulation on the surface, which can be divided into A-phase lead, B-phase lead and C-phase lead. The above leads are fixed by wire clamps 6 through perforation and binding. The lead spacing between A-phase lead, B-phase lead and C-phase lead meets the insulation requirements; the coil is a 4*6 parallel structure, with the two ends bridged by a bridge wire 4, and then the wires are output separately. The distance between the head end and the end lead meets the insulation requirements; the two bridge wires are separated by an insulating spacer 5, the insulating spacer 5 has a hole, and is fixed by binding.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A compact three-phase superconducting air-core reactor, characterized in that: include: A vacuum insulation container containing a cooling medium, the vacuum insulation container comprising a vacuum insulation shell (4) and a vacuum insulation cover (2), the vacuum insulation cover (2) being provided with a plurality of suspension rods (6) extending into the vacuum insulation shell (4); A three-phase superconducting magnet, the three-phase superconducting magnet being immersed in the cooling medium, the three-phase superconducting magnet being composed of three single-phase superconducting magnets (5) spaced apart and arranged on a plurality of the suspension rods (6) in a vertically stacked manner, the single-phase superconducting magnets (5) being a coreless hollow structure; A cryogenic bushing assembly, wherein the cryogenic bushing assembly has three groups and corresponds one to one with the single-phase superconducting magnets (5), each group of cryogenic bushing assemblies comprises two cryogenic bushings (1), the cryogenic bushings (1) partially extending from the outside of the vacuum insulation cover (2) into the vacuum insulation shell (4), the end of the cryogenic bushing (1) outside the vacuum insulation shell (4) is connected to the power grid, and the end inside the vacuum insulation shell (4) is connected to the corresponding single-phase superconducting magnet (5) through a current lead.

2. A compact three-phase superconducting air-core reactor according to claim 1, characterized in that: The vacuum insulation shell (4) is a double-layer structure shell with vacuum extraction between layers. A cooling medium inlet (3) and a cooling medium outlet (7) are provided on the side wall of the vacuum insulation shell (4). The cooling medium inlet (3) and the cooling medium outlet (7) are connecting pipes with a bellows structure.

3. A compact three-phase superconducting air-core reactor according to claim 2, characterized in that: The cooling medium outlet (7) is arranged on one side near the bottom of the vacuum insulation shell (4), and a cooling medium pipeline (8) surrounds the periphery of the inner shell of the vacuum insulation shell (4).

4. The compact three-phase superconducting air-core reactor according to claim 1, characterized in that: The single-phase superconducting magnet (5) comprises an upper fixing plate (502) and a lower fixing plate (506) arranged in parallel, and a coil assembly arranged between the upper fixing plate (502) and the lower fixing plate (506); The coil assembly comprises a pair of inner support rings (503) and a pair of outer support rings (504) arranged concentrically, and a plurality of superconducting magnet coils (505) arranged in a ring shape and spaced between the pair of inner support rings (503) and the pair of outer support rings (504).

5. The compact three-phase superconducting air-core reactor according to claim 4, characterized in that: The superconducting magnet coil (505) comprises: skeleton(5052); A skeleton lower cover plate (5057) and a skeleton upper cover plate (5051) are respectively arranged on the outer edges of both sides of the skeleton (5052); A dividing plate (5055) is provided between the skeleton lower cover plate (5057) and the skeleton upper cover plate (5051); the area enclosed by the dividing plate (5055) and the skeleton lower cover plate (5057) is a first cavity, and the area enclosed by the dividing plate (5055) and the skeleton upper cover plate (5051) is a second cavity; The winding wire (5053) includes a first winding wire arranged in a first cavity and a second winding wire arranged in a second cavity, wherein the innermost turns of the first winding wire and the second winding wire are connected through the gap of the dividing plate.

6. The compact three-phase superconducting air-core reactor according to claim 5, characterized in that: The superconducting magnet coil (505) further comprises: A copper connector (501), the copper connector (501) being arranged on the skeleton lower cover plate (5057) and the skeleton upper cover plate (5051) and being used for connection with a current lead; a skeleton connecting plate (5058), the skeleton connecting plate (5058) being arranged on the skeleton lower cover plate (5057) and the skeleton upper cover plate (5051), and being used for connecting with the pair of external support rings (504); Support rods (5054), the support rods (5054) are arranged on the skeleton lower cover plate (5057) and the skeleton upper cover plate (5051), and are used to connect with the pair of inner support rings (503).

7. The compact three-phase superconducting air-core reactor according to claim 4, characterized in that: The upper fixing plate (502), the lower fixing plate (506), the inner support ring (503) and the outer support ring (504) are made of G10 glass fiber material.

8. The compact three-phase superconducting air-core reactor according to claim 4, characterized in that: The upper fixing plate (502), the lower fixing plate (506) and the superconducting magnet coil (505) have a hollow structure.

9. The compact three-phase superconducting air-core reactor according to claim 4, characterized in that: The superconducting magnet coil (505) is one of a circular coil, a D-shaped coil, an inverted D-shaped coil or a racetrack coil.

10. The compact three-phase superconducting air-core reactor according to claim 1, characterized in that: The current lead is a hard wire with insulation on the surface.

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