Deterioration inspection device capable of protecting superconducting coil

Abstract

The present invention relates to: a deterioration inspection device capable of protecting a superconducting coil from high current during deterioration inspection of the superconducting coil; and a method for manufacturing same. A deterioration inspection device according to the present invention comprises: a power supply unit for supplying power to a superconducting coil to be tested; a plurality of connection bus bars for connecting the superconducting coil and the power supply unit in parallel; a protection bus bar connected in parallel to the superconducting coil and the power supply unit and connecting the plurality of connection bus bars; a sheet resistor inserted between each of the connection bus bars and the protection bus bar; a first current sensor that measures a current flowing through the superconducting coil; and a second current sensor that measures a current flowing through the protection bus bar. When a high current that is less than a critical current of the superconducting coil is applied to the superconducting coil by the power supply unit, if a current value measured by the first current sensor is greater than a current value measured by the second current sensor, it is determined that the superconducting coil is defective, thereby protecting the superconducting coil from overcurrent.

Description

Deterioration inspection device capable of protecting superconducting coils

[0001] The present invention relates to a device for inspecting deterioration of a superconducting coil of a device, and more particularly, to a deterioration inspection device capable of protecting a superconducting coil from high current.

[0002] A superconducting current limiter (FCL) is a device that protects the power system by limiting the fault current within a short period of time (several milliseconds) when an accident such as a ground fault or short circuit occurs in the power system.

[0003] Superconducting coils are components used in these superconducting current limiters. They have superconductivity below the critical current, allowing current to flow, but when the critical current flows above the critical current, they change into normal conductors and have resistance, thus limiting the current.

[0004] To use superconducting coils as components in superconducting current limiters, a process is required to verify that the produced superconducting coils possess a certain critical current. This verification test, called a thermal degradation test, involves applying a high current corresponding to the critical current for a very short time to verify that the coils possess the intended critical current.

[0005] However, there is a problem that the high current applied in the thermal inspection test for low-quality superconducting coils with a critical current lower than the normal value may be greater than the critical current, which may damage the expensive superconducting coil.

[0006] To prevent such damage, a method can be used that applies high current for a very short time, such as 50 ms, but since the test equipment that can apply current for such a short time is very expensive, there are limits to replacing existing test equipment.

[0007] The inventors of the present invention have devoted extensive research efforts to addressing the problems inherent in conventional superconducting coil deterioration detection devices. After extensive research and development, they have developed a deterioration detection device capable of detecting critical currents without damaging low-quality superconducting coils.

[0008] The purpose of the present invention is to provide a deterioration inspection device capable of checking the critical current of a superconducting coil without damaging the superconducting coil.

[0009] In addition, a deterioration inspection device capable of protecting a superconducting coil even when overcurrent is applied due to a tester's error or a malfunction of a test device is provided.

[0010] Meanwhile, other unspecified purposes of the present invention will be additionally considered within the scope that can be easily inferred from the detailed description and effects thereof below.

[0011] A superconducting coil deterioration inspection device according to the present invention comprises: a power supply unit for supplying power to a superconducting coil to be tested; a plurality of connection bus bars for connecting the superconducting coil and the power supply unit in parallel; a protection bus bar connected in parallel with the superconducting coil and the power supply unit and connecting between the plurality of connection bus bars; a sheet resistor inserted between the connection bus bar and the protection bus bar; a first current sensor for measuring a current flowing in the superconducting coil; a second current sensor for measuring a current flowing in the protection bus bar; and a control unit; wherein the control unit is characterized in that, when a high current less than a critical current of the superconducting coil is applied to the superconducting coil by the power supply unit, if the first current is smaller than the second current, the superconducting coil is determined to be defective.

[0012] When a high current lower than the critical current of the superconducting coil is applied to the superconducting coil by the power supply, if the current value measured by the first current sensor is greater than the current value measured by the second current sensor, the superconducting coil is judged to be defective.

[0013] The resistance value when the above protection bus bar and sheet resistor are connected is characterized in that it is greater than the resistance value of the superconducting coil when a current less than the critical current flows through the superconducting coil, and smaller than the resistance value of the superconducting coil when a current greater than the critical current flows through the superconducting coil.

[0014] The above sheet resistor is characterized by being an indium sheet.

[0015] The resistance value of the above-mentioned protective busbar and sheet resistor is characterized in that it is controlled by the fastening strength when the above-mentioned connecting busbar and the above-mentioned protective busbar are combined.

[0016] A method for manufacturing a superconducting coil deterioration inspection device according to another embodiment of the present invention is characterized by including the steps of: providing a power supply unit for supplying power to a superconducting coil to be tested and a plurality of connection bus bars for connecting the superconducting coil and the power supply unit in parallel; providing a protection bus bar and a sheet resistor for connecting between the plurality of connection bus bars and being connected in parallel with the superconducting coil and the power supply; fastening the plurality of connection bus bars so that the protection bus bar connects them, wherein the sheet resistor is inserted between the connection bus bar and the protection bus bar; and applying a test current to the connection bus bar by the power supply unit to adjust the resistance values ​​of the connection bus bar and the sheet resistor by a voltage measured at the connection bus bar.

[0017] The step of adjusting the resistance value is characterized in that the resistance value is adjusted by a fastening strength that connects the protective bus bar between the plurality of connecting bus bars.

[0018] The above sheet resistor is characterized by being an indium sheet.

[0019] The resistance value when the above protection bus bar and sheet resistor are connected is characterized in that it is greater than the resistance value of the superconducting coil when a current less than the critical current flows through the superconducting coil, and smaller than the resistance value of the superconducting coil when a current greater than the critical current flows through the superconducting coil.

[0020] According to the present invention, there is an effect of protecting a low-quality superconducting coil from overcurrent.

[0021] Additionally, it has the advantage of preventing damage to normal superconducting coils due to overcurrent applied due to malfunction of the thermal inspection device or tester's mistake.

[0022] Meanwhile, even if the effect is not explicitly mentioned herein, it is added that the effect and its provisional effect described in the following specification expected by the technical features of the present invention are treated as described in the specification of the present invention.

[0023] FIG. 1 is a schematic structural diagram of a superconducting coil deterioration inspection device according to a preferred embodiment of the present invention.

[0024] Figure 2 is a schematic structural diagram of a connection part of a superconducting coil deterioration inspection device according to a preferred embodiment of the present invention.

[0025] FIG. 3 is a schematic structural diagram for setting the resistance of a protection bus bar of a superconducting coil deterioration inspection device according to a preferred embodiment of the present invention.

[0026] Figure 4 is a schematic flowchart of a method for manufacturing a superconducting coil deterioration inspection device according to another preferred embodiment of the present invention.

[0027] Figure 5 is a schematic structural diagram of a superconducting coil deterioration inspection device according to the prior art.

[0028] It is to be understood that the attached drawings are provided for reference only to help understand the technical concept of the present invention, and the scope of the present invention is not limited thereby.

[0029] Hereinafter, with reference to the drawings, the configuration of the present invention, guided by various embodiments thereof, and the effects resulting from such configurations will be examined. In describing the present invention, detailed descriptions of related, well-known functions that are obvious to those skilled in the art and that may unnecessarily obscure the gist of the present invention will be omitted.

[0030] Terms such as "first" and "second" may be used to describe various components, but the components should not be limited by these terms. These terms may only be used to distinguish one component from another. For example, without departing from the scope of the present invention, a "first component" may be referred to as a "second component," and similarly, a "second component" may also be referred to as a "first component." Furthermore, singular expressions include plural expressions unless the context clearly dictates otherwise. Terms used in the embodiments of the present invention may be interpreted as having meanings commonly known to those of ordinary skill in the art, unless otherwise defined.

[0031] Hereinafter, with reference to the drawings, the configuration of the present invention guided by various embodiments of the present invention and the effects resulting from the configuration will be examined.

[0032] Figure 5 is a schematic structural diagram of a superconducting coil deterioration inspection device according to the prior art.

[0033] A typical superconducting coil deterioration inspection device (500) includes a power supply unit (510), a connection bus bar (522, 524), a current sensor (530), and a voltage sensor (540).

[0034] A superconducting coil (1) exhibits the properties of a conductor with zero resistance because it has superconductivity when a current less than the critical current flows, and when a current greater than the critical current flows, it changes into a normal conductor and has a constant resistance.

[0035] In order to test the critical current of such a superconducting coil (1), a deterioration inspection device (500) as shown in Fig. 5 is used, which checks whether superconductivity is present by flowing a high current lower than the critical current through the superconducting coil (1) by a power supply (510).

[0036] For example, if the critical current of a normal superconducting coil (1) is 550 A, a test current of 500 A is applied to check whether the superconducting coil (1) exhibits normal superconductivity. In the case of a normal superconducting coil (1), superconductivity is exhibited at a current lower than the critical current, so the resistance exhibits a characteristic close to 0, and therefore the value measured by the voltage sensor (540) will be close to 0.

[0037] However, a superconducting coil (1) of poor quality will have a lower critical current value than normal, for example, 450 A, and then will change into a normal conductor at a test current of 500 A and have a constant resistance. If the resistance is not 0, a quench phenomenon will occur in which a high voltage is generated by the high current, and if a high current of 500 A continues to flow, the superconducting coil (1) may be completely damaged. If a low-quality superconducting coil (1) is completely damaged in this way, it is difficult to identify the cause of the low quality of the superconducting coil (1), and in severe cases, there is a risk of other accidents such as a fire occurring.

[0038] In addition, even if the superconducting coil (1) is a superconducting coil of normal quality, if the applied current is increased too much due to a worker's mistake or a high current exceeding the critical current flows through the superconducting coil (1) due to a failure or abnormal operation of the power supply (510), there is a problem that even a normal superconducting coil (1) may be damaged.

[0039] Therefore, the thermal inspection device according to the present invention can protect the superconducting coil (1) by distributing current through a bus bar connected in parallel with the superconducting coil (1).

[0040] FIG. 1 is a schematic structural diagram of a superconducting coil deterioration inspection device according to a preferred embodiment of the present invention.

[0041] A superconducting coil deterioration inspection device (100) according to the present invention may include a power supply unit (110), a connection bus bar (122, 124), a protection bus bar (130), a sheet resistor (140), a first current sensor (150), a second current sensor (160), a voltage sensor (170), and a control unit (180).

[0042] The power supply (110) is used to apply a high current, which is a test current, to the superconducting coil (1).

[0043] For example, if the critical current of the superconducting coil (1) is 550 A, a test current of approximately 500 A can be applied to the superconducting coil (1).

[0044] The connecting busbar (122, 124) is used to connect the superconducting coil (1), the power supply (110), and the protection busbar (130).

[0045] The superconducting coil (1) and the protection busbar (130) are connected in parallel to the power supply (110) by the connecting busbar (122, 124).

[0046] The protection bus bar (130) connects between the connection bus bars (122, 124) and is connected in parallel with the superconducting coil (1) to distribute the current flowing in the superconducting coil (1) and thereby protect the superconducting coil (1).

[0047] A sheet resistor (140) can be inserted between the connecting bus bar (122) and the protection bus bar (130) so that the protection bus bar (130) exhibits a constant resistance value.

[0048] Indium, etc. can be used as the sheet resistor (140), but is not limited thereto.

[0049] Indium can be easily processed into sheet form, is soft, and has low electrical conductivity, making it suitable for use as a sheet resistor (140).

[0050] In addition, it has the advantage of being easy to use in the present invention because it can be made thick by stacking thin plates and is easy to process to the point where it can be torn by hand.

[0051] In general, the resistance of the busbar is close to 0, but the part connected to the protection busbar (130) has a certain resistance due to the resistance value of the sheet resistance (140) and the contact resistance caused by the connection with the connection busbar (122), so the superconducting coil (1) can be protected by the current distribution function with the superconducting coil (1).

[0052] The first current sensor (150) measures the first current flowing in the superconducting coil (1) and provides measurement information to the control unit (180).

[0053] The second current sensor (160) measures the second current flowing in the protection bus bar (130) and provides measurement information to the control unit (180).

[0054] The voltage sensor (170) measures the voltage applied across the superconducting coil (1) or the protective bus bar (130) and provides the measurement information to the control unit (180).

[0055] The control unit (180) may include a processor and memory. The control unit (180) may compare the magnitudes of the first current and the second current to determine whether the superconducting coil is defective.

[0056] When a defect in a superconducting coil is determined, the control unit (180) can transmit the information to a user terminal or output it through a display or speaker that can be connected to the control unit (180).

[0057] Figure 2 is a schematic structural diagram of a connection part of a superconducting coil deterioration inspection device according to a preferred embodiment of the present invention.

[0058] The superconducting coil (1) is ideally 0 ohm, but has a resistance in the microohm (μΩ) range due to contact resistance with the connecting busbar (122, 124) or a conductive section such as a copper terminal.

[0059] Therefore, by using this, the superconducting coil deterioration inspection device (100) according to the present invention protects the superconducting coil (1) by controlling the amount of current flowing in the superconducting coil (1).

[0060] In FIGS. 2a and 2b, a sheet resistor (130) is inserted between the protection bus bar (130) and the connection bus bar (122) and is fastened by a bolt (180).

[0061] Fig. 2a shows a sheet resistance (140) with a larger resistance value than Fig. 2b, with the bonding strength being weaker, and Fig. 2b shows a sheet resistance (140) with a smaller resistance value than that of Fig. 2a.

[0062] For example, in FIG. 2a, when the bolt (180) is connected with a tightening torque of 10 N·m, the sheet resistance (140) may exhibit a resistance value of 1 mΩ, and in FIG. 2b, when the bolt (180) is connected with a tightening torque of 30 N·m, the sheet resistance (140) may exhibit a resistance value of 0.1 mΩ.

[0063] FIG. 3 is a schematic structural diagram for setting the resistance of a protection bus bar of a superconducting coil deterioration inspection device according to a preferred embodiment of the present invention.

[0064] Figure 3 shows the configuration of a superconducting coil deterioration inspection device (100) before the superconducting coil (1) is connected.

[0065] Before the superconducting coil (1) is connected, all current generated from the power supply (110) flows to the protection bus bar (130). Therefore, by measuring the voltage displayed by the protection bus bar (130) and the sheet resistor (140) through the voltage sensor (170), the resistance value displayed by the combination of the protection bus bar (130) and the sheet resistor (140) can be calculated.

[0066] The resistance value displayed in this way can be set to a desired value by adjusting the fastening strength between the protective bus bar (130) and the connecting bus bar (122) as shown in the example of Fig. 2, thereby performing a deterioration inspection of the superconducting coil (1).

[0067] In a normal case, the superconducting coil (1) exhibits a very small resistance of about 10 μΩ, and the protection bus bar (130) together with the sheet resistance (140) has a resistance value greater than that of the superconducting coil (1), for example, a resistance value of 100 μΩ, so that most of the current generated by the power supply (110) flows to the superconducting coil (1) at a ratio of 10:1.

[0068] However, in the case of a low-quality superconducting coil (1), when the critical current is low, for example, when the critical current is about 450 A, quenching occurs by applying a current of 550 A from the power supply (110), and the resistance has a resistance value of about 10 mΩ, which is much larger than the normal case.

[0069] Then, unlike in the normal case, the resistance value of the protection bus bar (130) becomes much smaller than the resistance value of the low-quality superconducting coil (1), so that most of the current flows through the protection bus bar (130) rather than the superconducting coil (1), and thus the low-quality superconducting coil (1) can be protected from damage due to the quench phenomenon or continuous application of high current.

[0070] The control unit (180) can compare the first current by the first current sensor (150) and the second current by the second current sensor (160) and determine that the superconducting coil (1) is defective if the second current is greater than the first current even though a current less than the critical current is applied.

[0071] At this time, the resistance values ​​of the protection bus bar (130) and sheet resistor (140) should be optimally adjusted according to the resistance value of the superconducting coil (1).

[0072] When the resistance value of the superconducting coil (1) is large compared to the resistance value of the protection busbar (130), most of the current flows through the protection busbar (130) during the deterioration inspection of the normal superconducting coil (1). Then, in order to make the same current flow through the superconducting coil (1), a larger current is required, and the capacities of the power supply (110) and the protection busbar (130) must be much larger. Instead, when resistance occurs in the superconducting coil (1) due to quenching, a larger current can flow through the protection busbar (130) even with a small resistance, so that the protection sensitivity for the superconducting coil (1) can be further improved.

[0073] On the other hand, if the resistance value of the superconducting coil (1) is small compared to the resistance value of the protection bus bar (130), most of the current flows through the normal superconducting coil (1) when inspecting for deterioration of the normal superconducting coil (1). Then, only a small current is required to flow the same current to the superconducting coil (1), and there is an advantage in that the capacity of the power supply (110) and the protection bus bar (130) can be reduced. Instead, if resistance due to quenching occurs in the superconducting coil (1), contrary to the previous case, more current will flow to the superconducting coil (1), so the protection sensitivity for the superconducting coil (1) will be weakened.

[0074] Therefore, the resistance value presented by the protection bus bar (130) should be adjusted taking these points into consideration.

[0075] If the protective bus bar (130) according to the present invention is structured in parallel with the superconducting coil (1), it has the effect of protecting the superconducting coil (1) even if a current much greater than intended is applied due to a user's mistake or a failure of the power supply (110).

[0076] For example, if a large current of 1010A is applied due to a user's mistake, even if the superconducting coil (1) has a resistance of about 10mΩ due to quenching, the resistance of the protection bus bar (130) has a much smaller resistance of 100μΩ, so a current of 1000A flows to the protection bus bar (130), and only a small current of 10A flows to the superconducting coil (1), so the superconducting coil (1) can be protected.

[0077] Figure 4 is a schematic flowchart of a method for manufacturing a superconducting coil deterioration inspection device according to another preferred embodiment of the present invention.

[0078] In order to manufacture a superconducting coil deterioration inspection device, a power supply unit and a connecting bus bar for connecting the power supply unit and the superconducting coil are first provided (S110).

[0079] The power supply generates a test current to inspect the superconducting coil for deterioration.

[0080] The following protective busbar and sheet resistance are provided (S120).

[0081] The protection busbar connects between multiple connecting busbars and is connected in parallel with the superconducting coil so that the test current generated by the power supply is distributed to the superconducting coil and the protection busbar.

[0082] It is inserted between the protective busbar and the connecting busbar when the sheet resistance is connected, and is used to adjust the resistance value of the protective busbar.

[0083] The protection busbar and the connection busbar are connected with a sheet resistance inserted between them (S130). As previously discussed, the resistance value of the protection busbar varies depending on the connection strength.

[0084] Finally, the resistance value indicated by the protection busbar together with the sheet resistance is adjusted according to the resistance value of the superconducting coil (S140).

[0085] The resistance value can be adjusted by the fastening strength of the connecting busbar and the protective busbar as previously discussed. Alternatively, it can be adjusted by selecting the resistance value of the sheet resistor inserted between the connecting busbar and the protective busbar.

[0086] According to the superconducting coil deterioration inspection device according to the present invention, even a low-quality superconducting coil can be prevented from being damaged by high current application during testing, and even a normal superconducting coil can be prevented from being damaged by operator error or power supply failure.

[0087] The scope of protection of the present invention is not limited to the description and expression of the embodiments explicitly described above. Furthermore, it should be noted that the scope of protection of the present invention may not be limited by obvious modifications or substitutions within the technical field to which the present invention pertains.

Claims

1. Power supply unit for supplying power to the superconducting coil to be tested; A plurality of connecting bus bars for connecting the superconducting coil and the power supply unit in parallel; A protective busbar connected in parallel with the superconducting coil and the power supply and connecting between the plurality of connecting busbars; A sheet resistor inserted between the above connecting bus bar and the above protecting bus bar; A first current sensor measuring a first current flowing in the superconducting coil; A second current sensor measuring a second current flowing in the above protection busbar; and Control unit; Including, but not limited to, A deterioration inspection device capable of protecting a superconducting coil, characterized in that the control unit determines that the superconducting coil is defective when a high current lower than the critical current of the superconducting coil is applied to the superconducting coil by the power supply unit, and the first current is smaller than the second current.

2. In paragraph 1, A deterioration inspection device capable of protecting a superconducting coil, characterized in that the resistance value when the protection bus bar and sheet resistance are connected is greater than the resistance value of the superconducting coil when a current less than a critical current flows through the superconducting coil, and is smaller than the resistance value of the superconducting coil when a current greater than a critical current flows through the superconducting coil.

3. In paragraph 2, A deterioration inspection device capable of protecting a superconducting coil, characterized in that the above sheet resistance is an indium sheet.

4. In paragraph 2, A deterioration inspection device capable of protecting a superconducting coil, characterized in that the resistance value when the above protection busbar and sheet resistance are connected is controlled by the fastening strength when the above connection busbar and the above protection busbar are connected.

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