Compact three-phase superconductive air-core reactor

Abstract

The invention relates to a compact three-phase superconductive air-core reactor which comprises a vacuum heat insulation container, a cooling medium is contained in the vacuum heat insulation container, the vacuum heat insulation container comprises a vacuum heat insulation shell and a vacuum heat insulation cover, and a plurality of hanging rods extending into the vacuum heat insulation shell are arranged on the vacuum heat insulation cover; the three-phase superconducting magnet is immersed in the cooling medium, the three-phase superconducting magnet is formed by vertically stacking three single-phase superconducting magnets which sleeve the plurality of suspenders at intervals, and each single-phase superconducting magnet is of an iron-core-free hollow structure; the three low-temperature sleeve assemblies correspond to the single-phase superconducting magnets one to one, each low-temperature sleeve assembly comprises two low-temperature sleeves, the low-temperature sleeves partially extend into the vacuum heat insulation shell from the vacuum heat insulation cover, and the ends, located outside the vacuum heat insulation shell, of the low-temperature sleeves are connected into a power grid; and one end in the vacuum heat insulation shell is connected with the corresponding single-phase superconducting magnet through a current lead. The application scene of the reactor is expanded, and the problem that reactive compensation of a power grid is insufficient is effectively solved.

Description

Technical Field

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

[0002] As the urban power grid's overhead lines are buried underground and the rate of cabling increases, the problem of insufficient inductive reactive power compensation becomes more prominent, and voltage rises beyond the limit in many places, threatening the safe operation of the power grid. The need for local reactive power consumption is very urgent. Shunt reactors are an effective solution to the problem of local reactive power consumption, but existing conventional reactors occupy a large area and are noisy, making it difficult to renovate old substations with insufficient storage space. Summary of the invention

[0003] The purpose of the present invention is to provide a compact three-phase superconducting hollow reactor in order to overcome at least one of the defects of the above-mentioned prior art. The compact three-phase superconducting hollow reactor is a three-phase winding of the reactor wound with superconducting tape, which is cooled by a cooling medium to the temperature at which the superconducting tape enters the superconducting state. The high current carrying capacity of the superconducting material and the vertical stacking of the three-phase winding are utilized to effectively reduce the footprint and volume of the reactor. The coreless structure not only reduces the noise of the reactor from 75 decibels of the conventional iron core reactor to below 60 decibels, but also has the characteristic of small magnetic leakage, which greatly expands the application scenarios of the reactor and effectively solves the problem of insufficient reactive power compensation of 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, wherein a cooling medium is contained in the vacuum insulation container, the vacuum insulation container comprises a vacuum insulation shell and a vacuum insulation cover, and the vacuum insulation cover is provided with a plurality of suspension rods extending into the vacuum insulation shell;

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

[0008] A cryogenic bushing assembly, wherein the cryogenic bushing assembly has three groups and corresponds to the single-phase superconducting magnets one by one, each group of cryogenic bushing assemblies comprises two cryogenic bushings, the cryogenic bushing parts extend from the outside of the vacuum insulation cover into the vacuum insulation shell, one end of the cryogenic bushing outside the vacuum insulation shell is connected to the power grid, and the other end inside the vacuum insulation shell is connected to the corresponding single-phase superconducting magnet through a current lead.

[0009] Furthermore, the vacuum insulation shell is a double-layer structure shell with interlayer vacuum, and a cooling medium inlet and a cooling medium outlet are arranged on the side wall of the vacuum insulation shell, and 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; winding wires, the winding wires include 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 skeleton lower cover plate and the skeleton upper cover plate, and is used to connect with the current lead; a skeleton connecting plate, which is arranged on the skeleton lower cover plate and the skeleton upper cover plate, and is used to connect with the pair of outer support rings; a support rod, which is arranged on the skeleton lower cover plate and the skeleton upper cover plate, and is used to connect with 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 long to ensure sufficient creepage distance to prevent breakdown, and the lower part is long to make the temperature transition from the cooling medium temperature to the room temperature to prevent frost on the upper part.

[0018] Furthermore, the current lead is a hard wire with insulation on the surface, so that the current leads used by 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 air-core 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 flux and reduce losses.

[0022] (3) In the compact three-phase superconducting air-core reactor provided by the present invention, the cooling medium inlet and outlet are configured as a structure with bellows in consideration of shrinkage and heat leakage reduction at low temperatures. 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 increased losses 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 racetrack-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 embodiments, (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 A 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 The third assembly diagram of the single-phase superconducting magnet in the embodiment;

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

[0032] Fig. 9 A schematic diagram of a cryogenic sleeve in an embodiment;

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

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

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

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

[0037] Figure 1-9 As shown in the middle number: 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] Fig.10 As shown in the marking 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 in conjunction with 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 have high noise, 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 insulation container, wherein a cooling medium is contained in the vacuum insulation container, wherein the vacuum insulation container comprises a vacuum insulation shell 4 and a vacuum insulation cover 2, wherein the vacuum insulation cover 2 is provided with a plurality of suspension rods 6 extending into the vacuum insulation 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 sleeved on a plurality of the suspension rods 6 and stacked vertically, and the single-phase superconducting magnet 5 is a coreless hollow structure;

[0044] A cryogenic bushing assembly, wherein there are three groups of cryogenic bushing assemblies corresponding to the single-phase superconducting magnets 5 one by one, each group of cryogenic bushing assemblies comprises two cryogenic bushings 1, wherein the cryogenic bushings 1 partially extend from the outside of the vacuum insulation cover 2 into the vacuum insulation shell 4, wherein one end of the cryogenic bushings 1 outside the vacuum insulation shell 4 is connected to the power grid, and the other 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 shell with vacuum between layers. The side wall of the vacuum insulation shell 4 is provided with a cooling medium inlet 3 and a cooling medium outlet 7. The cooling medium inlet 3 and the cooling medium outlet 7 are connecting pipes with a bellows structure. Since the sleeve, sensor, etc. need to be drilled in the vacuum insulation cover 2, the vacuum insulation cover 2 is a non-double-layer structure.

[0046] In this embodiment, 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 .

[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 arranged between the upper fixing plate 502 and the lower fixing plate 506; the coil assembly includes 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 arranged at intervals 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 are used as support, the inner support ring 503 and the outer support ring are fixed by the slots, and the screw locking structure design prevents the superconducting magnet coil 505 from being deformed or displaced under electric force or external vibration.

[0048] In this embodiment, the superconducting magnet coil 505 comprises: a skeleton 5052; a skeleton lower cover plate 5057 and a skeleton upper cover plate 5051 respectively arranged at the outer edges of both sides of the skeleton 5052; a dividing plate 5055 arranged 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; a winding wire 5053, the winding wire 5053 comprises 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. A dividing plate 5056 is also arranged between the skeleton lower cover plate 5057 and the skeleton 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 annular 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 losses 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 the mechanical strength, alleviates the obstruction to the fluidity of the cooling medium during operation, and achieves the effect of convection.

[0052] In this embodiment, the superconducting magnet coil 505 is preferably a racetrack-shaped coil. Since the three-phase magnets are in the same space, special attention should be paid to magnetic flux leakage to avoid increased losses caused by the mutual inductance of the three magnets. The specific means are to optimize the shape and size of the coil and increase the number of magnet coils. Since optimizing the coil size and increasing the number of magnet coils will increase the amount of strip material used, significantly increasing the cost, the coil shape is finally selected as a racetrack-shaped coil through comparison, so that the amount of strip material used is minimized when the magnetic flux leakage meets the requirements.

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

[0054] Based on the requirement of compact superconducting shunt reactor, in order to reduce the size of superconducting shunt reactor and reduce the amount of tape, this embodiment proposes four types of coil winding structure selection, namely circular, D-type, reverse D-type and racetrack type, such as Figure 2 After given other key parameters such as overall inductance and operating current amplitude, by comparing the reactor size and strip usage based on the four coil unit geometries, the magnet design scheme that saves the most strip usage of the superconducting shunt reactor when the leakage flux meets the requirements is determined, thus 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 number of parallel branches p = 2, the number of coil windings M = 24, the distance R from the center of the coil to the axis R = 0.4m, the strip width 6mm, and the coil thickness 0.44mm as an example, Table 1 shows the size and strip usage of the single-phase superconducting shunt reactor based on circular, D-type, reverse D-type and racetrack coils. It can be seen that the change in the geometric structure of the coil winding can significantly improve the overall size of the single-phase toroidal superconducting reactor. Replacing the circular coil with the racetrack coil achieves the compact size of the superconducting shunt reactor and the need to save 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 the radial position of 1 meter (i.e., 30 cm outside the winding) is only 0.002 mT, which is much smaller 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 distribution of eddy currents generated on the inner and outer cavities when the three phases of the reactor are connected in parallel with different phases of operating current is given. The corresponding eddy current loss is almost negligible compared with the AC loss of the reactor coil winding. This indirectly shows that the ring reactor structure effectively constrains the magnetic field of the magnet, and there is almost no changing magnetic field in the space outside the reactor, which will not cause additional metal eddy current losses.

[0060] In this embodiment, two cryogenic bushings 1 need to be connected to each phase of the three-phase magnet, so there are a total of 6 bushings on the vacuum insulation cover 2. The cryogenic bushing 1 is divided into two parts, the upper part is a copper column insulated by silicone rubber, and the lower part is a copper column wrapped by G10. The two are connected by a stainless steel flange. The upper part is left long to ensure sufficient creepage distance to prevent breakdown; the lower part is left long to make the temperature transition from the cooling medium temperature to room temperature and prevent frost on the upper part. Considering the limitation of space size, the minimum upper and lower sizes are determined by 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 property parameters are from the NIST official website. The simulation results are shown in Fig.10 .

[0062] See also Fig.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 connected separately. The lead distances at the head and the end meet the insulation requirements. The two bridge wires are separated by an insulating pad 5, and the insulating pad 5 has a hole and is fixed by binding.

[0063] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A compact three-phase superconducting air-core reactor, characterized in that: include: A vacuum insulation container, wherein a cooling medium is contained in the vacuum insulation container, the vacuum insulation container comprising a vacuum insulation shell (4) and a vacuum insulation cover (2), wherein the vacuum insulation cover (2) is 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 is immersed in the cooling medium, the three-phase superconducting magnet is composed of three single-phase superconducting magnets (5) spaced apart and arranged on a plurality of suspension rods (6) in a vertically stacked manner, and the single-phase superconducting magnet (5) is a coreless hollow structure; A cryogenic bushing assembly, wherein the cryogenic bushing assembly has three groups and corresponds to the single-phase superconducting magnets (5) one by one, 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 a 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 arranged 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. A 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. A compact three-phase superconducting air-core reactor according to claim 4, characterized in that: The superconducting magnet coil (505) comprises: Skeleton(5052); A frame lower cover plate (5057) and a frame upper cover plate (5051) respectively arranged on the outer edges of both sides of the frame (5052); A dividing plate (5055) is arranged between a lower frame cover plate (5057) and an upper frame cover plate (5051), wherein an area enclosed by the dividing plate (5055) and the lower frame cover plate (5057) is a first cavity, and an area enclosed by the dividing plate (5055) and the upper frame cover plate (5051) is a second cavity; The winding conductor (5053) includes a first winding conductor arranged in a first cavity and a second winding conductor arranged in a second cavity, and the innermost turns of the first winding conductor and the second winding conductor are connected through the gap of the dividing plate.

6. A 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 connecting 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); A support rod (5054), wherein the support rod (5054) is disposed on the lower cover plate (5057) of the skeleton and the upper cover plate (5051) of the skeleton, and is used to be connected to the pair of inner support rings (503).

7. A 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. A 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. A 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. A 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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