High-temperature superconducting current limiter
Technical Field
The invention relates to a current limiting device, in particular to a high-temperature superconducting current limiter.
Background
With the rapid development of economy, the scale of the power grid in China is continuously enlarged, the interconnection degree is continuously improved, and the technical requirements are increasingly increased. However, stability, safety, reliability issues of the grid are always important indicators of the quality of the grid, wherein a short-circuit fault is one of the serious faults that endanger the safety of the power system, resulting in huge economic losses. The resistive high-temperature superconducting current limiter which utilizes the quench resistance of the high-temperature superconductor to limit current can effectively solve the problems and has good application and market prospect. At present, the core technology of the current limiter is generally to wind a single second generation high-temperature superconducting strip into a pancake coil from the middle position in a double-belt parallel winding mode to realize the reversal of the circulating current so as to eliminate a magnetic field to manufacture a non-inductive pancake coil, and then a plurality of non-inductive pancake coils are combined in series and parallel. This configuration typically employs an intermediate "S" or "U" shape for current reversal. Meanwhile, there is also a single straight-cylinder type non-inductive connection mode at present, which uses a single straight cylinder as a unit, the strips with reverse current are placed on the surface of the cylinder in parallel with the axis, and then two adjacent strips are connected in series by using a copper block, so that the two adjacent parallel strips are connected with reverse current. . For the pie coil, because the bending radius of each layer is different, and an insulating spacing layer needs to be arranged between the belts, the flowing lengths of opposite currents introduced into each turn of superconducting tape are inconsistent, and the magnetic field counteracting effect is poor; due to the limitation of the production process, the longer the length of a single superconducting tape is, the higher the selling price is, and a plurality of tapes are wound on the same cake and generally need to be welded, so that the uniformity of the superconducting tapes is poor, and the current limiting effect is influenced. Secondly, for the straight-tube current-limiting winding mode, the phenomenon that the joints are quenched to burn the strip materials when short-circuit overcurrent occurs due to excessive joints is caused, and the potential hidden trouble of stable operation of the superconducting current-limiting device is caused.
Disclosure of Invention
The invention aims to overcome the defects of complex structure, incomplete magnetic field offset, excessive welding joints, poor length and uniformity of a single high-temperature superconducting strip and the like of the conventional non-inductive superconducting current limiting device and provides a high-temperature superconducting current limiter.
The invention provides a high-temperature superconducting current limiter, which comprises cylindrical winding units, the number of which is at least 2, and the cylindrical winding units are vertically arranged;
each columnar winding unit is provided with at least 1 circumferential winding grooves;
and a current conversion joint is arranged in the winding groove of the last columnar winding unit in the current limiter, and spacing blocks with the same thickness are arranged in the winding grooves of other columnar winding units.
Preferably, the number of winding grooves of each columnar winding unit is 1, and the heights of the winding grooves are the same.
Preferably, the number of winding grooves of each winding unit is greater than 1 and equal, and the heights of the winding grooves of each winding unit on the same layer are the same.
Preferably, two parallel high-temperature superconducting tapes are continuously wound in the winding grooves on the same layer of the columnar winding unit respectively.
Preferably, the columnar winding units are distributed in a zigzag wave shape, and the distribution of the columnar winding units is suitable for the length and the bending threshold of the high-temperature superconducting tape.
Preferably, the cylindrical winding unit includes: the device comprises a columnar winding framework and at least 2 fixing rings sleeved on the framework; the space between the fixing rings forms the winding groove.
Preferably, the number of the fixing rings on each cylindrical bobbin is equal, and the heights of the fixing rings on the same layer are equal.
Preferably, the spacing block is an insulating block with a certain angle or radian, the thickness of the fast spacing block is the same as the depth of the winding groove where the fast spacing block is located, and the spacing block is located between two parallel high-temperature superconducting tapes in contact with the winding groove.
Preferably, the commutation connectors are conductors, and the commutation connectors are fixed in the corresponding winding grooves through fixing pieces.
Preferably, the cylindrical bobbin is cylindrical, and the fixing ring is circular.
Preferably, the commutation joint is wedge-shaped, the two high-temperature superconducting tapes are welded on two sides of the end with the larger thickness, and the thickness of the end is equal to that of the spacing block.
Preferably, the material of the commutation joint comprises the following components in percentage by mass:
fe: 0.002-0.004%, Ni: 0.002-0.003%, Pb: 0.003 to 0.005%, Sn: 0.002-0.003%, S: 0.003-0.005%, Zn: 0.002-0.003%, P not more than 0.001%, and the balance of copper.
Preferably, the material of the commutation joint comprises the following components in percentage by mass:
fe: 0.003%, Ni: 0.0025%, Pb: 0.004%, Sn: 0.003%, S: 0.005%, Zn: 0.002%, P: 0.001% and the balance copper.
Preferably, the winding framework and the fixing ring are both made of epoxy materials, and the epoxy materials comprise the following components in percentage by mass:
3% -12% of epoxy resin;
5% -15% of rubber;
73-92% of solvent.
Preferably, the epoxy material comprises the following components in percentage by mass:
10% of epoxy resin;
10% of rubber;
and 80% of a solvent.
Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:
1. according to the technical scheme provided by the invention, the circumferential winding groove in the columnar winding unit is matched with the spacing block and the current conversion connector in the groove for use, after the current is electrified, the current with completely opposite directions can be ensured to flow on two high-temperature superconducting strips which are parallel to each other and have the same length, the dead-against area of the surfaces of the two strips is close to 100%, and the effects of offsetting a magnetic field and reducing loss are realized to the maximum extent. Furthermore, the method is simple. Two parallel-wound high-temperature superconducting tapes on each layer are only connected in sequence at the commutation joint, so that the joints are few, and the welding is few, thereby improving the uniformity of the high-temperature superconducting tapes, greatly reducing the possibility of burning the tapes due to short circuit, and realizing the stable current limiting effect.
2. According to the technical scheme provided by the invention, the design of the cylindrical winding framework and the fixing ring enables the high-temperature superconducting strip to be wound more conveniently and simply, the operability is strong, the labor and the cost of assembly are reduced, the requirement on the shape of the strip after winding is simple, the bending at a larger angle is avoided, the use effect is improved, and the service life is prolonged.
3. The wedge-shaped current conversion joint in the technical scheme provided by the invention not only realizes the purpose of reverse current conversion of the two superconducting tapes, but also ensures that the joint has smaller resistance, and is firm and stable.
4. According to the technical scheme provided by the invention, the mechanical property of the winding framework and the epoxy material of the fixing ring can be ensured, so that the two superconducting tapes can be always fixed in parallel, and a good insulating effect can be achieved.
5. The material design of the current conversion joint in the technical scheme provided by the invention ensures low-resistance communication of the two superconducting tapes, and the material also reduces the welding temperature and avoids high-temperature damage to the superconducting tapes.
Drawings
The invention will be further described with reference to the accompanying drawings in which:
FIG. 1: the structure schematic diagram of the high-temperature superconducting current limiting device is shown;
FIG. 2: the current flow diagram of the high-temperature superconducting current-limiting device is shown;
FIG. 3: schematic view of the spacer of the present invention;
FIG. 4: a schematic diagram of a commutation junction of the invention;
FIG. 5: the converter joint and the superconducting tape are assembled schematically;
wherein: 1-fixing ring, 2-winding framework, 3-forward circulation superconducting strip, 4-reverse circulation superconducting strip, 5-commutation joint, 6-spacing block, 7-winding groove fixing screw hole, 8-commutation joint fixing screw hole, 9-countersunk head bolt and 10-superconducting strip welding position.
Detailed Description
The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the drawings in the embodiments of the present application.
As shown in fig. 1 to 5, the present invention provides a high temperature superconducting current limiter, which includes at least 2 vertically arranged cylindrical winding units, each of the cylindrical winding units is respectively provided with circumferential winding grooves with a number greater than 1, and if the number of the winding grooves of each of the cylindrical winding units is 1, the heights of the winding grooves are the same.
If the number of the winding grooves of each winding unit is more than 1 and equal, the heights of the winding grooves on the same layer are the same.
Each columnar winding unit comprises a cylindrical winding framework 2 and annular fixing rings 1 which are serially sleeved and fixed on the framework, wherein the number of the fixing rings is larger than 2, and the spaces among the fixing rings 1 form winding grooves.
The number of the fixing rings 1 on each columnar winding framework 2 is equal, and the heights of the fixing rings 1 on the same layer are equal.
A commutation joint 5 is fixedly arranged in the winding groove of the last columnar winding unit, spacing blocks 6 with the same thickness are respectively arranged in the winding grooves of other columnar winding units,
the spacing block 6 is a semicircular insulating block matched with the winding groove in shape, and the thickness of the spacing block 6 is preferably equal to the depth of the winding groove in which the spacing block is arranged.
The commutation joint 5 is wedge-shaped, the two high-temperature superconducting tapes are welded on two sides of the end with the larger thickness, and the thickness of the end is equal to that of the spacing block. Two parallel high-temperature superconducting tapes, namely a forward-flowing superconducting tape 3 and a reverse-flowing superconducting tape 4, are continuously wound in the winding grooves on the same layer of the columnar winding unit respectively, the tail end of each layer of the parallel double-layer superconducting tapes is connected with a current conversion joint 5, and the current conversion joint 5 is fixed in the winding grooves to realize the current reversal.
The positive through-flow superconducting strips 3 and the reverse through-flow superconducting strips 4 are wound along the winding grooves of the columnar winding units, wavy lines are wound in a positive and negative bending mode according to the positions of the winding units, the spacing blocks 6 are embedded between the two superconducting strips and placed in the winding grooves, and the positive through-flow superconducting strips 3 and the reverse through-flow superconducting strips 4 are respectively wound on the inner surface and the outer surface of the spacing blocks 6 in a penetrating mode in the winding process.
According to the technical scheme provided by the invention, the circumferential winding groove in the columnar winding unit is matched with the spacing block 6 and the current conversion connector 5 in the groove for use, after the current is electrified, the current with completely opposite directions can be ensured to flow on two high-temperature superconducting strips which are parallel to each other and have the same length, the surface dead area of the two strips is close to 100%, and the effects of offsetting a magnetic field and reducing loss are realized to the greatest extent. Furthermore, the method is simple. Two parallel-wound high-temperature superconducting tapes on each layer are only connected in sequence at the commutation joint, so that the joints are few, and the welding is few, thereby improving the uniformity of the high-temperature superconducting tapes, greatly reducing the possibility of burning the tapes due to short circuit, and realizing the stable current limiting effect.
According to the technical scheme provided by the invention, the design of the cylindrical winding framework 2 and the annular fixing ring 1 enables the high-temperature superconducting strip to be wound more conveniently and simply, the operability is strong, the labor and the cost of assembly are reduced, the requirement on the shape of the strip after winding is simple, the bending at a larger angle is avoided, the use effect is improved, and the service life is prolonged.
The commutation joint 5 is wedge-shaped, and the inner bending direction and the outer bending direction of the commutation joint are respectively along the tangential direction of the winding groove and are embedded into the winding groove at the tail end of the winding unit. The forward-flow high-temperature superconducting strip 3 and the reverse-flow superconducting strip 4 are welded at superconducting strip welding positions 10 on the inner surface and the outer surface of the commutation joint 5 through low-temperature soldering tin to complete series connection, two commutation joint fixing screw holes 8 are formed in the wedge-shaped end portion of the commutation joint 5, two fixing screw holes 7 are formed in the position of a winding framework corresponding to the commutation joint, and the commutation joint 5 and the winding framework 2 are fixed from the outer side of a winding unit through two countersunk bolts 9 to be connected into a whole.
The wedge-shaped current conversion joint 5 in the technical scheme provided by the invention not only realizes the purpose of reverse current conversion of the two superconducting tapes, but also ensures that the joint has smaller resistance, and is firm and stable.
The columnar winding units are distributed in a turn-back type wave shape, and the distribution of the columnar winding units is suitable for the length and the bending threshold of the high-temperature superconducting strip.
The number of the columnar winding units and the number of layers of the winding grooves are designed according to the actual requirements of two high-temperature superconducting tapes required by current limiting.
The material of the commutation joint 5 comprises the following components in percentage by mass:
fe: 0.003%, Ni: 0.0025%, Pb: 0.004%, Sn: 0.003%, S: 0.005%, Zn: 0.002%, P: 0.001% and the balance copper.
The material design of the current conversion joint 5 ensures the low resistance communication of the two superconducting tapes, and the material also reduces the welding temperature and avoids the high temperature damage to the superconducting tapes.
The winding framework 2 and the fixing ring 1 are both made of epoxy materials, and the epoxy materials comprise the following components in percentage by mass:
10% of epoxy resin;
10% of rubber;
80 percent of solvent,
the epoxy material design of the winding framework 2 and the fixing ring 1 can ensure the mechanical property thereof, so that the two superconducting tapes can be fixed in parallel with each other all the time, and the good insulation effect can be achieved.
Finally, it should be noted that: the embodiments described are only a part of the embodiments of the present application, and not all embodiments, and all other embodiments obtained by those skilled in the art without making creative efforts based on the embodiments in the present application belong to the protection scope of the present application.