JP2003088092A - Superconducting generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make compact in size a superconducting generator. SOLUTION: The superconducting generator can be made compact in size without increasing the magnetomotive force of field winding by employing a magnetic body in the winding shaft of a rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting power generator, and more particularly to a superconducting power generator having a magnetic material for a winding shaft to which a superconducting field winding is attached.

[0002]

2. Description of the Related Art The superconducting field winding of a conventional superconducting generator has been attached to a winding shaft made of a non-magnetic high strength material as described in, for example, Japanese Patent Laid-Open No. 10-127043.

[0003]

As a high strength material having sufficient strength and toughness at extremely low temperatures and suitable for the winding axis of the superconducting field winding of a superconducting generator, a non-magnetic A286 alloy or a weak magnetic material at extremely low temperatures is used. Inconel material with is known. The rotor of the superconducting generator is made of non-magnetic material in the parts other than the winding axis as well, and the magnetic shield inner diameter is entirely magnetic with the armature winding, which is a void winding. Is. Although it has advantages such as a low reactance generator and improved system stability, it has reached the limit in terms of further miniaturization by increasing the air gap magnetic flux.

In view of the above problems, the object of the present invention is to maintain the toughness of the winding shaft at an extremely low temperature and to increase the air gap magnetic flux without increasing the magnetomotive force of the field winding. To provide.

[0005]

The present invention is characterized in that a winding shaft provided with a field winding is formed of a magnetic metal having sufficient toughness and magnetism at a temperature in a superconducting state.

By doing so, the magnetic flux density of the air gap can be increased without increasing the magnetomotive force of the superconducting field winding.
In addition, since the toughness does not deteriorate at extremely low temperatures, a robust and compact superconducting generator can be realized.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a rotary electric machine according to the present invention will be described below with reference to the drawings of the embodiments.

A conventional example will be described in comparison.

FIG. 1 shows a superconducting generator which is a first embodiment. The superconducting generator has a superconducting field winding 5 in the rotor portion, and a very large magnetomotive force of the superconducting field winding can generate a large magnetic flux density in the armature winding 2. Therefore, the armature winding 2 is a void winding. In the rotor, the superconducting field winding 5 is attached to the winding shaft 6. In addition, the rotor has a damper winding function, a room temperature damper 3 for shielding high frequency magnetic flux from the armature winding and a radiation shield function, and a low temperature damper capable of shielding low frequency magnetic flux from the armature winding. 4 and a liquid helium storage tank 7 having liquid helium (refrigerant) used for cooling the superconducting field winding. The stator serves as a yoke for field magnetic flux, and there is a magnetic shield 1 having a function of shielding magnetic flux to the outside. In such a configuration, the superconducting generator rotor uses a magnetic material for the winding shaft of the rotor.

A more detailed description will be given. The rotor is the axis of rotation,
It has a disk-shaped support disk and a cylindrical room-temperature damper 3.
The winding shaft 6 is placed so as to fit in the internal space of the room temperature damper 3. The room temperature damper 3 is attached to a disk-shaped support disk provided on the rotating shaft of the rotor. A low temperature damper 4 is arranged between the outer circumference of the winding shaft 6 and the inner circumference of the room temperature damper 3.

A coolant cover is provided between the inner circumference of the low temperature damper 4 and the outer circumference of the winding shaft 6. A field winding 5 is provided so as to be embedded on the outer peripheral side of the winding shaft 6, and a liquid helium storage tank 7 (bore) is provided inside thereof. Cylindrical portions are provided on both outer peripheral side ends of the winding shaft 6, and the tip ends are joined to the support disk. Since the supporting disk side is at room temperature and the bore side is at extremely low temperature, the cylindrical portion has an extremely large temperature gradient between the tip side and the root side.

The refrigerant supplied from the supply hole of the rotary shaft so as to be stored in the liquid helium storage tank 7 (bore) is supplied to the field winding 5 from the communication hole communicating with the embedded portion of the field winding 5 from the bore, The field winding 5 is cooled. A coolant cover is provided to prevent the coolant that has cooled the field winding 5 from leaking to the outside. The refrigerant in the refrigerant cover is recovered via the refrigerant recovery channel.

FIG. 2 shows a conventional superconducting generator using a non-magnetic material for the winding axis of the field winding.

This conventional superconducting generator has substantially the same construction as that of the embodiment shown in FIG. 1 except that the winding shaft 8 is made of a non-magnetic material.

Regarding the magnetic flux density of these generators (the present embodiment and the conventional example), the results of the examination based on a non-magnetic winding shaft superconducting generator having an output capacity of 200 MW are shown below.

As shown in Table 1, the magnetic winding shaft superconducting generator having the same size as the generator having the non-magnetic winding shaft can bring the magnetomotive force to 75% of that of the non-magnetic winding shaft. The magnetomotive force is determined by the rated current. The value of 75% is obtained from the rated current. When the magnetomotive force of the magnetic winding shaft superconducting generator is made the same as that of the non-magnetic winding shaft superconducting generator, as shown in Table 1, the 200 MW generator output can be increased to 130 MW, 260 MW.

[0017]

[Table 1] FIG. 3 (conventional example) shows a magnetic flux density distribution at the rated output of a 200 MW superconducting generator using a non-magnetic winding shaft. FIG. 4 (embodiment of the present invention) is a case where 200 MW is output using a magnetic winding shaft in a superconducting generator of the same size. FIG. 5 (embodiment of the present invention) shows a magnetic flux density distribution when a magnetic winding shaft is used in a superconducting power generator of the same size and a magnetomotive force is applied to the nonmagnetic winding shaft 200 MW superconducting power generator. 3, 4 and 5 are the calculation results by the finite element method, and the results shown in Table 1 were obtained by these calculations.

The bore diameter of the winding shaft to which the superconducting field winding of the 200 MW class superconducting generator is attached is usually 3 in terms of strength.
It is set to 00 mm or more. 350 mm for 600 MW machine
More than that. Therefore, the bore diameter is 250 mm to 300
If it is set to mm, the cross-sectional area of the magnetic path of the magnetic winding shaft is increased, and the air gap magnetic flux can be further increased. The inside of the bore is used as a storage tank for liquid helium, which is a liquid refrigerant used to cool the superconducting field winding. FIG. 6 shows a superconducting generator which is a second embodiment. Unlike the linear portion of the field winding, which is arranged along the axial direction of the winding axis, it is not necessary to secure the magnetic flux path of the field magnetic flux at the end of the field winding. The diameter can be made as large as possible in terms of strength, and the function as a liquid helium storage tank can be enhanced. In other words, the bore has a small diameter in the central portion of the bore where the linear portion of the field winding is arranged, and has a large diameter on both end sides.

The magnetic material usually used for the rotor of a generator cannot be used as a winding shaft of a superconducting field winding of a superconducting generator because its toughness is remarkably reduced at extremely low temperatures. 13 mass% Ni and 3 mass% Mo as magnetic winding shaft materials
The use of the iron-based alloys of the series enables superconducting field windings having sufficient toughness and strength and having a magnetic winding axis. This metallic material has excellent toughness and strength even at room temperature, and retains ferromagnetism.

Examples of iron-based alloys containing 13 mass% Ni and 3 mass% Mo will be described in more detail below. A basic study was conducted using a small ingot.

NiCrMoV low alloy steel, which is an existing material and is used as a general rotor shaft material, is a ferromagnetic material. However, brittleness becomes remarkable at extremely low temperatures, so it is suitable for a winding shaft material of a superconducting generator. Absent. However, a martensitic Fe-Ni-based alloy containing a large amount of Ni may satisfy both ferromagnetism and low temperature toughness. Therefore, 13 mass% Ni
And a 3 mass% Mo-based iron-based alloy were manufactured, and tensile properties and magnetic properties were measured in the temperature range from room temperature to extremely low temperature.

13 mass% Ni according to an embodiment of the present invention
The 3 mass% Mo-based iron-based alloys are characterized by a low Al (aluminum) content and a small amount of Zr and Mg. Since Al impairs the low temperature toughness, it is set to 0.020 mass% or less. Zr and Mg are deoxidizing and desulfurizing elements, and since they are effective in improving the forgeability and weldability of the alloy, they are added up to 0.05 mass% each. Large forged products such as winding shafts of superconducting generators are prone to forge cracking, but 13 ma with Zr and Mg added
The ss% Ni and 3 mass% Mo-based iron-based alloy is less likely to cause forging cracks. In addition, the winding shaft has many welding points with other parts such as low temperature dampers, but 13 ma with Zr and Mg added
The ss% Ni and 3 mass% Mo-based iron-based alloy is less likely to cause weld cracking. Further, according to the present invention, 13 mass% Ni and 3 ma
The ss% Mo-based iron-based alloy is characterized by allowing carbon to remain at the time of smelting, since C can be allowed up to 0.10 mass% at the maximum.

Table 2 shows 13 mass according to the embodiment of the present invention.
% Ni and 3 mass% Mo-based iron-based alloy, and the chemical components of Inconel according to the conventional example given as a comparative material are shown. 30 kg
The ingot produced after vacuum melting was hot-forged into a rectangular shape, heat-treated, and then a test piece was sampled to measure its characteristics. The material according to the example of the present invention was subjected to heat treatment of 900 ° C. quenching, and the comparative material was solution treated at 980 ° C. × 1 h and 8 hours.
A heat treatment of 45 ° C. × 3 h + 720 ° C. × 8 h + 620 ° C. × 8 h was applied.

[0024]

[Table 2] FIG. 7 shows the tensile properties of the material N1 according to the embodiment of the present invention, and FIG. 8 shows the tensile properties of the material N2 according to the embodiment of the present invention. 9 shows the magnetic characteristics of the material N1 according to the example of the present invention, FIG. 10 shows the material N2 of the example of the present invention, and FIG. 11 shows the magnetic characteristics of Inconel according to the conventional example given as a comparative material. 13 mass% Ni and 3 ma
ss% Mo-based iron-based alloy has a tensile strength of 0.2% at room temperature of 600
It exhibits an elongation of 20% at MPa and 4K, and exhibits stronger ferromagnetism than Inconel in the temperature range of room temperature to 5K. From this result, it is clear that the 13 mass% Ni and 3 mass% Mo-based iron-based alloys are ferromagnetic, high strength and high toughness materials suitable for the winding axis. This 13 mass% Ni and 3 m
The ass% Mo-based iron-based alloy has a feature that the material cost is low because the amount of Ni is smaller than that of the A286 alloy and Inconel which are conventionally used for the field winding mounting shaft.

[0025]

According to the superconducting generator according to the present invention described above, it is possible to reduce the size of the superconducting generator by increasing the air gap magnetic flux without imposing a performance burden on the superconducting field winding. .

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a superconducting generator according to a first example illustrating an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a superconducting generator according to a conventional example.

FIG. 3 200 MW using a non-magnetic winding shaft according to a conventional example
It is a figure which shows the magnetic flux density distribution at the time of a rated output of a superconducting generator.

FIG. 4 is a diagram showing a magnetic flux density distribution when 200 MW is output using a magnetic winding shaft in a superconducting generator having the same size as that of FIG. 3, according to an embodiment of the present invention.

FIG. 5 relates to an embodiment of the present invention, in which a magnetic winding shaft is used in a superconducting generator having the same size as in FIG. 3, and a non-magnetic winding shaft 20 is used.
It is a figure which shows the magnetic flux density distribution when the same magnetomotive force is given as a 0 MW superconducting generator.

FIG. 6 relates to a second example showing an embodiment of the present invention and is a diagram showing a configuration of a superconducting generator.

FIG. 7 relates to an example of the present invention and shows the tensile properties of material N1.

FIG. 8 is a diagram related to the example of the present invention and showing the tensile properties of the material N2.

FIG. 9 is a diagram showing a magnetic characteristic of the material N1 according to the example of the present invention.

FIG. 10 is a diagram showing a magnetic characteristic of the material N2 according to the example of the present invention.

FIG. 11 is a diagram showing magnetic characteristics of Inconel according to a conventional example given as a comparative material.

[Explanation of symbols]

1 ... Magnetic shield, 2 ... Air gap armature winding, 3 ... Room temperature damper, 4 ... Low temperature damper, 5 ... Superconducting field winding, 6 ... Magnetic winding axis, 7 ... Liquid helium storage tank, 8 ... Nonmagnetic winding axis.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mori Yoshinobu             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. F term (reference) 5H655 BB01 BB04 BB09 CC02 CC15                       DD03 DD12 EE29

Claims (6)

[Claims] 1. A superconducting generator for maintaining a superconducting state by cooling a field winding attached to a winding shaft with a refrigerant, wherein the winding shaft is made of a magnetic metal having sufficient toughness and magnetism at a temperature of the superconducting state. Is a superconducting generator. 2. The superconducting generator according to claim 1, wherein the winding shaft is made of a metal material containing an iron-based alloy of 13 mass% Ni and 3 mass% Mo. 3. The field magnet according to claim 1 or 2, wherein a bore for accumulating the refrigerant is provided inside the winding shaft, and the bore is arranged along an axial direction of the winding shaft. The diameter of the central part of the bore corresponding to the straight part of the winding is 2
A superconducting generator characterized by having a thickness of 50 mm to 300 mm. 4. The superconducting generator according to claim 3, wherein the diameter of both ends of the bore is larger than the diameter of the central portion of the bore. 5. A magnetic shield as a stator provided with an armature winding, a rotor provided with a field winding, a rotating shaft of the rotor, and a field winding provided on the rotating shaft. It has a winding shaft provided, and a bore provided inside the winding shaft and in which a coolant for cooling the field winding is accumulated, and the winding shaft has sufficient toughness and magnetism at a temperature in a superconducting state. A superconducting generator characterized by being formed of magnetic metal. 6. A magnetic shield as a stator provided with an armature winding, a rotor provided with a field winding, a rotation shaft of the rotor, and a field winding provided on the rotation shaft. The winding shaft has a winding shaft and a bore provided inside the winding shaft and in which a coolant for cooling the field winding is accumulated. The winding shaft has sufficient toughness and magnetic properties at superconducting temperature and room temperature. A superconducting power generator characterized by being formed from a magnetic metal having