Superconducting current lead device with adjustable power-on length and adjusting method thereof

Abstract

The invention relates to a superconducting current lead device with an adjustable power-on length and an adjusting method thereof.The device comprises a current lead conducting rod, a connector, a telescopic arm, an electric device, a power-on flexible wire, a power-on bus and a superconducting cable, a motor for driving the telescopic arm to stretch out and draw back is arranged in the electric device, the telescopic arm stretches out and draws back to drive the connector to be connected with or separated from the current lead conducting rod, the power-on length of the current lead conducting rod is changed, the connector is further connected with a power-on bus through a power-on flexible wire, one end of the power-on bus is connected with the power-on flexible wire, and the other end of the power-on bus is connected with a superconducting cable. Compared with the prior art, the length of the superconducting current lead can be automatically adjusted, heat leakage caused by the current lead in a superconducting cable or a superconducting device system is effectively reduced, and the effect of adjusting the length of the current lead according to current so as to reduce heat loss is achieved.

Description

Technical Field

[0001] The invention relates to the field of electric power technology, and in particular to a superconducting current lead device with adjustable conduction length and an adjustment method thereof. Background Art

[0002] A current lead is a conductive line that connects a power source and a load and is widely used in the power field. In the field of superconductivity, many applications such as superconducting magnets and superconducting cables require the use of current leads to connect external power sources and internal loads. However, since superconductivity only has superconducting properties at low temperatures, in the field of superconductivity, the temperature difference between the two sections of the current lead is extremely large, usually exceeding 200°C, and can even reach 300°C. Conventional superconducting current leads use metals with good conductivity such as copper and aluminum as conductors, and conductors with good conductivity usually have good thermal conductivity, so the heat leakage of the current lead is also extremely large. The currently commonly used method is to calculate the optimal aspect ratio of the current lead to minimize heat leakage.

[0003] However, the optimal aspect ratio only applies to the case where the current is constant. In the actual application of superconducting cables, the current is usually affected by many factors such as load, time, day and night, season, etc., and there will be large fluctuations. Therefore, the fixed length of the current lead will cause greater heat loss when the current fluctuates.

[0004] Chinese patent CN101446598B discloses a variable cross-section current lead suitable for a high-temperature superconducting tape critical current characteristic test system, which belongs to the field of applied superconducting technology, including: a straight copper rod variable cross-section current lead, which uses an improved air-cooled current lead segmentation calculation method to optimize the geometric parameters of the variable cross-section current lead; a hybrid lead segment welded in parallel with a copper strand and a BSCCO strip, which is used to connect the end of the straight copper rod variable cross-section lead with the YBCO strip. The variable cross-section current lead designed by the invention has the advantages of low heat leakage, high cooling efficiency, and saving lead materials and refrigeration costs. However, the disadvantage of the prior art is that even if the variable cross-section technology is used, it still cannot be automatically adjusted according to the current, and its optimal aspect ratio is only applicable to a small range of current. When the current fluctuates too much, especially in the application scenario where the transmission cable has a great difference between day and night cables, when the current passing through the superconducting cable is not a constant value, its heat leakage cannot reach the theoretical minimum value. How to adjust the length of the current lead according to the current is a difficult problem that must be solved to reduce the heat leakage of the cable system. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a superconducting current lead device with adjustable power-on length and its adjustment method, and to propose a current lead whose length can be automatically adjusted according to the current size, thereby reducing the heat loss caused by the current lead.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A superconducting current lead device with adjustable current length, comprising:

[0008] Current lead conductive rod, connector, telescopic arm, electric device, energized flexible wire, energized bus and superconducting cable, wherein the plurality of connectors are connected to the electric device through the telescopic arm, each connector is connected to one end of the energized bus through the energized flexible wire, and the other end of the energized bus is connected to the superconducting cable;

[0009] The electric device is provided with a motor for driving the telescopic arm to extend and retract. The extension or retraction of the telescopic arm drives different connectors to connect or separate with the current lead conductive rod, thereby changing the energized length of the current lead conductive rod.

[0010] Furthermore, the electric device controls the motor according to the magnitude of the current passing through the current lead conductive rod, and the motor drives the telescopic arm to drive different connectors, thereby changing the energized length of the current lead conductive rod.

[0011] Furthermore, the distance between the connectors should satisfy the following formula:

[0012]

[0013] Where L is the distance between the connectors, V is the rated voltage applied to the current lead conductive rod, and d is the dielectric strength.

[0014] Furthermore, the number of the telescopic arms is equal to the number of the connectors, and the telescopic arms are insulated.

[0015] Furthermore, the current lead conductive rod is provided with vertically arranged grooves whose number is equal to the number of connectors, and the shape and size of the grooves match the shape and size of the connectors, and the grooves correspond to the connectors one by one.

[0016] Furthermore, the current lead conductive rod is connected to an external power source.

[0017] Furthermore, the number of the energized flexible wires is equal to the number of the connectors, and the energized flexible wires are insulated from each other.

[0018] A method for adjusting the conduction length of a superconducting current lead device with adjustable conduction length, the method comprising:

[0019] Calculate an estimated optimal length-to-diameter ratio based on device parameters and an estimated initial current through the current lead conductive rod, and set the current lead device based on the optimal length-to-diameter ratio;

[0020] Select a connector according to the estimated optimal aspect ratio, and connect the connector to the current lead conductive rod through an electric device;

[0021] After the current lead conductive rod is powered on, the current flowing through the current lead conductive rod is monitored in real time to determine whether the connector needs to be switched; if switching is required, the optimal aspect ratio is recalculated based on the equipment parameters and the current passing through the current lead conductive rod, and the connector is switched through an electric device;

[0022] Among them, the equipment parameters include the length of the current lead conductive rod, the cross-sectional area of ​​the current lead conductive rod, the temperature of the current lead conductive rod, the average thermal conductivity of the current lead conductive rod and the average Lorentz constant of the current lead conductive rod.

[0023] Furthermore, the formula for the optimal aspect ratio is:

[0024]

[0025] When x=0, T=T L ,

[0026] When x=L, T=T H ,

[0027] Where L is the length of the current lead conductive rod, l is the length of the current lead conductive rod during integration, A is the area of ​​the current lead conductive rod, T is the temperature of the current lead conductive rod during integration, and T L is the low temperature side temperature, T H is the high temperature side temperature, I is the current load of the current lead conductive rod, k ave is the average thermal conductivity of the current lead conductive rod material, L ave is the average Lorentz constant of the current lead conducting rods.

[0028] Furthermore, it is characterized in that when the current flowing through the current lead conductive rod changes, the connector needs to be switched.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention is equipped with a matching electric device and a telescopic arm, which can automatically control the switching of the connector during the power-on process, change the length of the current lead conductive rod, and realize contactless lead length change, making the operation of adjusting the lead length safer and simpler, saving labor costs;

[0031] 2. The present invention can automatically switch the length of the current lead conductive rod according to the change of the current flowing through the current lead conductive rod, thereby reducing the Joule heat of the current lead itself, greatly reducing the heat leakage caused by the current lead in the superconducting cable or superconducting device system, reducing heat loss, reducing the use of cooling medium, and improving the energy utilization efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1A diagram of a superconducting current lead device of the present invention;

[0033] Figure 2 It is a top view schematic diagram of the connection state of the connector of the present invention;

[0034] Figure 3 Schematic diagram of two connectors with different structures in one embodiment of the present invention;

[0035] Figure 4 It is a partially enlarged schematic diagram of a superconducting current lead device with a conductive strap in one embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the minimum safe distance between two connectors of the present invention;

[0037] Figure 6 A schematic diagram of a connector switching process in an embodiment of the present invention;

[0038] In the figure, 1-current lead conductive rod, 2-connector, 3-telescopic arm, 4-electric device, 5-powered flexible wire, 6-powered bus, 7-superconducting cable, 11-connection hole, 21-bismuth telluride connector, 22-copper connector, 23-conductive strap. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0040] Example 1

[0041] This embodiment intends to disclose a superconducting current lead device with adjustable current length, the device is specifically as follows Figure 1 As shown, it includes a current lead conductive rod 1, a connecting head 2, a telescopic arm 3, an electric device 4, a power cord 5, a power bus 6 and a superconducting cable 7.

[0042] In the present device, changing the energized length of the current lead conductive rod 1 can actually be equivalent to changing the length of the current lead.

[0043] The current lead conductive rod 1 and the electric device 4 are independent of each other and do not directly contact each other. The electric device 4 and the superconducting cable 7 are independent of each other and do not directly contact each other. The superconducting cable 7 is located below the electric device 4 .

[0044] The current lead conductive rod 1 is connected to an external power source, and is provided with vertically arranged grooves equal in number to the connectors 2 , and the shapes and sizes of the grooves match those of the connectors 2 , and the grooves correspond to the connectors 2 one by one.

[0045] The superconducting current lead device has a plurality of connectors 2, which are connected to an electric device 4 via a telescopic arm 3; a motor is provided inside the electric device 4, which can drive the telescopic arm 3 to extend and retract in the horizontal direction, each telescopic arm 3 is connected to a connector 2, and the electric device 4 can operate any number of telescopic arms 3 to extend and retract individually or simultaneously.

[0046] The safety distance between each connector 2 is as follows: Figure 5 As shown, the following formula should be satisfied:

[0047]

[0048] Wherein, L is the distance between the connectors 2, V is the rated voltage applied to the current lead conductive rod, and d is the dielectric strength.

[0049] The number of telescopic arms 3 is equal to the number of connectors 2, and the telescopic arms 3 are insulated. The extension or contraction of the telescopic arms 3 drives the connector 2 to connect or separate with the current lead conductive rod 1. Each telescopic arm 3 can be independently controlled. In the electrical experiments of the system, usually including power frequency withstand voltage tests and lightning impulse tests, the telescopic arms 3 can protect the electric device from electrical damage such as breakdown.

[0050] The connector 2 is also connected to the power bus 6 via the power cord 5 . One end of the power bus 6 is connected to the power cord 5 , and the other end is connected to the superconducting cable 7 . The connection bus 6 is insulated from the electric device 4 .

[0051] The number of the power cords 5 is equal to the number of the connectors 2 , and the power cords 5 are insulated from each other.

[0052] In this embodiment, the current lead conductive rod 1, the connecting head 2, the power-carrying soft wire 5 and the power-carrying bus 6 are made of copper, aluminum or other common materials with good conductivity that can be used to make conductive elements; the telescopic arm 3 is made of epoxy resin, epoxy fiberglass or other common materials with good insulation properties that can be used to make insulating parts.

[0053] The current lead conductive rod 1 is arranged on the left side of the electric device 4 .

[0054] Since superconductivity has superconducting properties only at low temperatures, the device is set in a container filled with a cooling medium in actual application, and the superconducting cable 7 is immersed in liquid nitrogen. For the safe operation of the motor, the electric device 4 is not immersed in liquid nitrogen but above the liquid level of the cooling medium. The position of the connector 2 at the lower end of the electric device 4 matches the position of the lower end groove of the current lead conductive rod 1. When the connector 2 at the lower end of the electric device 4 is used to connect to the current lead conductive rod 1, the energized length of the current lead conductive rod 1 is its own length.

[0055] When the connector 2 is not powered, the connector looks like Figure 2 The upper example is separated from the current lead conductive rod 1. When the connector 2 is energized, the connector is shaped like Figure 2 As shown in the example diagram below, the telescopic arm 3 pushes the connector 2 and comes into close contact with the current lead conductive rod 1 to form an electrical path.

[0056] Example 2

[0057] Based on the above-mentioned embodiment 1, this embodiment designs a superconducting current lead device with adjustable current length. The difference between its structure and that of embodiment 1 is that the material of the connector 2 is different.

[0058] like Figure 3 As shown, the connector 2 includes a bismuth telluride connector 21 and a copper connector 22. The bismuth telluride connector 21 and the copper connector 22 can be as shown in FIG. Figure 3 Connect side by side as shown in the example above, or Figure 2 The nested connection shown in the example diagram in the lower part is sufficient as long as the connection strength between the two material connectors can be guaranteed and the current can pass through the bismuth telluride connector 21 and the copper connector 22 in sequence.

[0059] There is no restriction on the order in which the current passes through the bismuth telluride connector 21 and the copper connector 22 . The current can first pass through the bismuth telluride connector 21 or the copper connector 22 .

[0060] The copper connector 22 may be made of aluminum or other common materials with good electrical conductivity that can be used to make conductive elements, and the bismuth telluride connector 21 may also be made of other new materials with good electrical conductivity but poor thermal conductivity.

[0061] The current-carrying flexible wire 5 can be connected to the bismuth telluride connector 21 or the copper connector 22 , but it must be ensured that the current passes through the bismuth telluride connector 21 and the copper connector 22 in sequence.

[0062] The remaining parts of the superconducting current lead device in this embodiment are consistent with those in Embodiment 1, and the specific details can be understood by referring to the relevant descriptions and effects in Embodiment 1.

[0063] Example 3

[0064] Based on the above-mentioned embodiments 1 and 2, this embodiment designs a superconducting current lead device with adjustable current length. The difference between its structure and that of the above-mentioned embodiments lies in the different structures of the current lead conductive rod 1 and the connector 2.

[0065] like Figure 4 As shown, the current lead conductive rod 1 has connection holes 11 whose number is not less than the number of the connection heads 2 , and the size of the connection holes 11 matches the size of the connection heads 2 .

[0066] The connector 2 has a conductive strap 23, which fits tightly with the connector 2. After the connector 2 is sent into the connecting hole 11 by the telescopic arm 3, the conductive strap 23, the connector 2 and the connecting hole 11 fit tightly to better ensure the electrification effect.

[0067] There is no limit to the number of conductive straps 23 on each connector 2, and the number can be increased or decreased as desired according to the current being supplied.

[0068] The conductive strap 23 can be made of copper, aluminum or other common materials with good conductivity that can be used to make conductive elements.

[0069] The remaining parts of the superconducting current lead device in this embodiment are consistent with those in Embodiment 1, and the specific details can be understood by referring to the relevant descriptions and effects in Embodiment 1.

[0070] Example 4

[0071] Based on the above embodiments, this embodiment designs a method for adjusting the current length of a superconducting current lead with adjustable current length, and the method comprises the following steps:

[0072] Step 1, calculating an estimated optimal aspect ratio according to equipment parameters and an estimated initial current, and installing a current lead device according to the optimal aspect ratio;

[0073] The equipment parameters include the length of the current lead conductive rod, the cross-sectional area of ​​the current lead conductive rod, the temperature of the current lead conductive rod at the initial moment, the average thermal conductivity of the current lead conductive rod and the average Lorentz constant of the current lead conductive rod;

[0074] The formula for the optimal aspect ratio is:

[0075]

[0076] When x=0, T=T L ,

[0077] When x=L, T=T H ,

[0078] Wherein, L is the length of the current lead conductive rod 1, l is the length of the current lead conductive rod 1 during integration, A is the area of ​​the current lead conductive rod 1, T is the temperature of the current lead conductive rod 1 during integration, T L is the low temperature side temperature, T H is the high temperature side temperature, I is the current load, k ave is the average thermal conductivity of the current lead conductive rod 1 material, L ave is the average Lorentz constant of the current lead conductive rod 1.

[0079] The specific process of step 1 includes:

[0080] Calculate and design the length and diameter of the current lead conductive rod 1 according to the maximum current given by the system;

[0081] Producing a current lead conductive rod 1 according to the calculated length and diameter;

[0082] According to the depth of the container where the current lead conductive rod 1 is located, select an electric device 4 of suitable length, and a suitable number of connectors 2 and telescopic arms 3;

[0083] The lower end of the electric device 4 should be higher than the liquid level of the cooling medium in the container, while the current lead conductive rod 1 is not limited, and the connector 2 and the telescopic arm 3 are divided into appropriate numbers according to actual conditions;

[0084] When designing the number of connectors 2 and telescopic arms 3, in a stable state, since the gas medium inside the container is usually nitrogen with high purity, the medium can be regarded as a uniform and stable gas, and the connection between the energized and unenergized connectors 2 can be regarded as point-to-point discharge, so it should be maintained as follows. Figure 5 Safety distance shown.

[0085] Step 2, selecting a connector 2 according to the estimated optimal aspect ratio, and connecting the connector 2 to the current lead conductive rod 1 through the electric device 4.

[0086] The process of step 2 specifically includes: selecting a suitable connector 2 according to the estimated optimal aspect ratio, controlling the electric device 4, driving the motor of the electric device 4, pushing the connector 2, and connecting the designated connector 2 to the current lead conductive rod 1 to form an electrical path.

[0087] Step 3, after the current lead conductive rod 1 is powered on, the current flowing through the current lead conductive rod 1 is monitored in real time to determine whether the connector 2 needs to be switched; if switching is required, the optimal aspect ratio is recalculated and the connector 2 is switched through the electric device 4.

[0088] The process of step 3 specifically includes:

[0089] like Figure 6As shown in the schematic diagram of the device on the left, the current passing through the current lead conductive rod 1 is monitored in real time to determine whether the connector 2 needs to be switched;

[0090] If a large change in current is detected, it is determined that the connector 2 needs to be switched. The length with the minimum heat leakage is calculated according to the current current and the cross-sectional area of ​​the current lead conductive rod 1 by the optimal aspect ratio formula, and the connector 2 closest to the length is selected to drive the motor of the electric device 4 to push the connector 2. Figure 6 As shown in the schematic diagram of the device on the right, the more suitable connector 2 below is connected to the current lead conductive rod 1;

[0091] The motor of the electric device 4 is driven to pull back the connectors 2 , disconnect all connectors 2 except the appropriate connectors 2 , and restore the original positions of these connectors 2 .

[0092] If the above method is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device, such as a personal computer, a server, or a network device, to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory ROM, Read-Only Memory, random access memory RAM, Random Access Memory, disk or optical disk, and other media that can store program codes.

[0093] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A superconducting current lead device with adjustable current length, characterized in that: The device comprises: A current lead conductive rod (1), a connector (2), a telescopic arm (3), an electric device (4), an energized flexible wire (5), an energized bus (6) and a superconducting cable (7), wherein a plurality of connectors (2) are connected to the electric device (4) via the telescopic arm (3), each connector (2) is connected to one end of the energized bus (6) via the energized flexible wire (5), and the other end of the energized bus (6) is connected to the superconducting cable (7); A motor for driving the telescopic arm (3) to extend or retract is arranged in the electric device (4); the extension or retraction of the telescopic arm (3) drives the connector (2) at different positions to connect or separate with the current lead conductive rod (1), thereby changing the energized length of the current lead conductive rod (1).

2. A superconducting current lead device with adjustable current length according to claim 1, characterized in that: The electric device (4) controls the motor according to the magnitude of the current passing through the current lead conductive rod (1), and the motor drives the telescopic arm (3) to drive different connectors (2), thereby changing the energized length of the current lead conductive rod (1).

3. A superconducting current lead device with adjustable current length according to claim 1, characterized in that: The distance between the connectors (2) should satisfy the following formula: Wherein, L is the distance between the connectors (2), V is the rated voltage applied to the current lead conductive rod (1), and d is the dielectric strength.

4. A superconducting current lead device with adjustable current length according to claim 1, characterized in that: The number of the telescopic arms (3) is equal to the number of the connecting heads (2), and the telescopic arms (3) are insulated.

5. A superconducting current lead device with adjustable current length according to claim 1, characterized in that: The current lead conductive rod (1) is provided with vertically arranged grooves in a number equal to the number of the connectors (2), and the shape and size of the grooves match the shape and size of the connectors (2), and the grooves correspond to the connectors (2) one by one.

6. A superconducting current lead device with adjustable current length according to claim 1, characterized in that: The current lead conductive rod (1) is connected to an external power source.

7. A superconducting current lead device with adjustable current length according to claim 1, characterized in that: The number of the energized flexible wires (5) is equal to the number of the connectors (2), and the energized flexible wires (5) are insulated from each other.

8. A method for adjusting the conduction length of a superconducting current lead device with adjustable conduction length according to any one of claims 1 to 7, characterized in that: The method comprises: Calculating an estimated optimal length-to-diameter ratio based on device parameters and an estimated initial current passing through the current lead conductive rod (1), and setting the current lead device based on the optimal length-to-diameter ratio; Selecting a connector (2) according to the estimated optimal aspect ratio, and connecting the connector (2) to the current lead conductive rod (1) through an electric device (4); After the current lead conductive rod (1) is energized, the current flowing through the current lead conductive rod (1) is monitored in real time to determine whether the connector (2) needs to be switched; if switching is required, the optimal aspect ratio is recalculated based on the device parameters and the current passing through the current lead conductive rod (1), and the connector (2) is switched through the electric device (4); The equipment parameters include the length of the current lead conductive rod (1), the cross-sectional area of ​​the current lead conductive rod (1), the temperature of the current lead conductive rod (1), the average thermal conductivity of the current lead conductive rod (1), and the average Lorentz constant of the current lead conductive rod (1).

9. The method for adjusting the energized length according to claim 8, characterized in that: The formula for the optimal aspect ratio is: When x=0, T=T L , When x=L, T=T H , Wherein, L is the length of the current lead conductive rod (1), l is the length of the current lead conductive rod (1) during integration, A is the area of ​​the current lead conductive rod (1), T is the temperature of the current lead conductive rod (1) during integration, T L is the low temperature side temperature, T H is the high temperature side temperature, I is the current load of the current lead conductive rod (1), k ave is the average thermal conductivity of the material of the current lead conductive rod (1), L ave is the average Lorentz constant of the current lead conducting rod (1).

10. The method for adjusting the energized length according to claim 8, characterized in that: When the current flowing through the current lead conductive rod (1) changes, the connector (2) needs to be switched.

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