A superconducting switch station and its working method

Abstract

The present invention relates to a superconducting switch station and its working method. The superconducting switch station is connected to two substations respectively through superconducting cables, and the two substations supply power to the superconducting switch station. A first busbar and a second busbar are arranged in the superconducting switch station, and the first busbar and the second busbar are connected through a normally closed bus-section switch. The first busbar is connected with a superconducting reactor. Compared with the prior art, the present invention integrates devices such as a large-capacity switch station, superconducting cables, superconducting reactors, superconducting fault current limiters, etc. to establish a superconducting switch station, realize closed-loop operation of the busbar, and can limit short-circuit current, improve power supply capacity and power supply reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting power equipment, and particularly to a superconducting switch station and its working method. Background Art

[0002] Currently, substations in the central urban areas often have limitations such as small construction land area and tight outgoing line bays. When users apply for power supply, they will face the problem of no available bays. Traditionally, the method of distributing switch stations is mostly used to expand the power supply range of substations. However, ordinary switch stations are limited by the transmission capacity of the incoming line, and the power supply capacity of a single station cannot effectively match the capacity of the substation.

[0003] Based on this, the prior art considers applying superconducting power equipment such as superconducting cables, superconducting reactors, and superconducting fault current limiters in the central urban areas to improve the power supply capacity and reliability of the power grid in the central urban areas. Among them, the outstanding advantages of superconducting cables are large capacity, low loss, self-limiting current, and environmental friendliness. Its transmission capacity can replace at least 4 - 6 circuits of conventional cables of the same voltage, or replace conventional cables of two voltage levels higher. For example, a 35kV superconducting cable is equivalent to the transmission capacity of a 220kV ordinary cable, and a 10kV superconducting cable is equivalent to the transmission capacity of a 110kV ordinary cable. Using superconducting cables for power transmission can significantly reduce the voltage level of substations and realize the relocation of high-voltage substation equipment in the central urban areas to the suburbs.

[0004] In addition, with the continuous increase of cable lines in the power grid, a large amount of reactive power is inverted, resulting in insufficient inductive reactive power compensation and high voltage levels. It is necessary to install shunt reactors. Due to the large noise of oil-immersed reactors and the large floor area of dry-type reactors, it is very difficult to apply them in urban substations with narrow space. Compared with conventional reactors, superconducting reactors using superconducting materials as working windings have the advantages of small floor area and low noise.

[0005] The superconducting fault current limiter presents a "superconducting state" during normal operation with very low impedance. When a fault occurs, it can quickly respond to become a larger impedance to suppress the short-circuit current, and can automatically return to the "superconducting state" in time after the fault is cleared; it can play a role in quickly, stably, and effectively limiting the system short-circuit current, greatly reducing the opening pressure of the circuit breaker; the conventional method mainly increases the impedance of the power grid through high-impedance transformers or current-limiting reactors, etc. These measures will undoubtedly increase the power transmission loss and voltage drop of the power grid.

[0006] However, to fully utilize the advantages of superconducting power equipment, it cannot be solved by replacing a single superconducting device. Therefore, there is an urgent need to integrate equipment such as large-capacity switch stations, superconducting cables, superconducting reactors, and superconducting fault current limiters to establish a superconducting switch station. Summary of the Invention

[0007] The object of the present invention is to overcome the defects of the above-mentioned existing technologies and provide a superconducting switch station and its working method, which can realize the closed-loop operation of the bus, limit the short-circuit current, and improve the power supply capacity and reliability.

[0008] The object of the present invention can be achieved through the following technical solutions: A superconducting switch station is connected to two substations respectively through superconducting cables, and the two substations supply power to the superconducting switch station. A first bus section and a second bus section are arranged in the superconducting switch station. The first bus section and the second bus section are connected through a normally closed bus sectionalizing switch, and the first bus section is connected with a superconducting reactor.

[0009] Further, the bus sectionalizing switch includes two series-connected sectionalizing switches, and the two sectionalizing switches are both in a closed state during normal operation.

[0010] Further, a superconducting fault current limiter is connected between the two sectionalizing switches.

[0011] Further, the first bus section is connected to the superconducting reactor through a normally closed tap-off switch.

[0012] Further, the capacity of the superconducting reactor is specifically designed according to the reactive power reverse transmission conditions under different operating modes of the incoming and outgoing lines of the two bus sections.

[0013] Further, the first bus section and the second bus section are respectively connected to the first substation and the second substation through superconducting cables.

[0014] Further, both the first bus section and the second bus section are connected to the corresponding superconducting cables through normally closed switches.

[0015] Further, the superconducting cable is connected to the bus of the substation through a normally closed switch.

[0016] A working method of a superconducting switch station includes: using two substations to supply power to the superconducting switch station through superconducting cables;

[0017] The first bus section and the second bus section in the superconducting switch station adopt a closed-loop operation mode to achieve an even distribution of the load;

[0018] Using the superconducting reactor connected to the first bus section for inductive reactive power compensation;

[0019] When a short-circuit fault occurs at any point on the two bus sections and their outgoing lines, the superconducting fault current limiter is used to limit the current from the non-faulty bus section;

[0020] When the superconducting fault current limiter fails or needs to be overhauled, the two sectionalizing switches are opened to cut off the power supply of the superconducting fault current limiter, so that the two bus sections can still operate normally.

[0021] Furthermore, the superconducting reactor realizes segmented adjustment of the compensation capacity through a tap changer.

[0022] Furthermore, a refrigerator is configured in the cryostat of the superconducting cable. A first coil heat exchanger and a second coil heat exchanger are respectively arranged in the cryostat of the superconducting cable and the cryostat of the superconducting power conversion equipment. The superconducting power conversion equipment includes a superconducting reactor and a superconducting fault current limiter. The inside of the first coil heat exchanger is filled with first liquid nitrogen, and the first liquid nitrogen is communicated with the liquid nitrogen inside the superconducting cable. The outside of the first coil heat exchanger is filled with second liquid nitrogen, and the cold head of the refrigerator is immersed in the second liquid nitrogen.

[0023] The inside of the second coil heat exchanger is filled with third liquid nitrogen, and the third liquid nitrogen is communicated with the liquid nitrogen inside the superconducting power conversion equipment. The outside of the second coil heat exchanger is filled with fourth liquid nitrogen.

[0024] The outlet of the first coil heat exchanger is connected to the inlet of the cryostat of the superconducting power conversion equipment, and the outlet of the cryostat of the superconducting power conversion equipment is connected to the liquid nitrogen inlet of the superconducting cable.

[0025] A method for the shared refrigerator of a superconducting switchyard to operate. The refrigerator provides cooling capacity to the cryostat of the superconducting cable to maintain the low temperature of the second liquid nitrogen. The second liquid nitrogen transfers the cooling capacity to the first liquid nitrogen through the first coil heat exchanger. The first liquid nitrogen flows between the first coil heat exchanger and the superconducting cable to transfer the cooling capacity to the superconducting cable, ensuring that the superconducting cable is maintained in the low-temperature superconducting state.

[0026] The first liquid nitrogen also transfers the cooling capacity to the fourth liquid nitrogen through flow. The fourth liquid nitrogen transfers the cooling capacity to the third liquid nitrogen through the second coil heat exchanger. The third liquid nitrogen flows between the second coil heat exchanger and the superconducting power conversion equipment, thereby transferring the cooling capacity to the superconducting power conversion equipment, ensuring that the superconducting power conversion equipment is maintained in the low-temperature superconducting state.

[0027] Furthermore, a refrigerator is configured in the cryostat of the superconducting cable. A first coil heat exchanger and a second coil heat exchanger are respectively arranged in the cryostat of the superconducting cable and the thermostat of the superconducting power conversion equipment. The superconducting power conversion equipment includes a superconducting reactor and a superconducting fault current limiter. The inside of the first coil heat exchanger is filled with first liquid nitrogen, and the first liquid nitrogen is communicated with the liquid nitrogen inside the superconducting cable. The outside of the first coil heat exchanger is filled with second liquid nitrogen, and the cold head of the refrigerator is immersed in the second liquid nitrogen.

[0028] The inlet of the second coil heat exchanger is connected to the outlet of the first coil heat exchanger, and the outlet of the second coil heat exchanger is connected to the liquid nitrogen inlet of the superconducting cable.

[0029] A working method of a shared refrigerator for a superconducting switch station, where the refrigerator provides cooling capacity to the cold box of the superconducting cable to maintain the low temperature of the second liquid nitrogen. The second liquid nitrogen transfers the cooling capacity to the first liquid nitrogen through the first coil heat exchanger. The first liquid nitrogen flows between the first coil heat exchanger and the superconducting cable to transfer the cooling capacity to the superconducting cable, ensuring that the superconducting cable is maintained in the low-temperature superconducting state;

[0030] The first liquid nitrogen also transfers the cooling capacity to the second coil heat exchanger through flow, ensuring that the thermostat of the superconducting power conversion equipment is maintained in the low-temperature superconducting state.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] The present invention designs that the superconducting switch station is connected to two substations through superconducting cables respectively. The two substations supply power to the superconducting switch station, and a first bus section and a second bus section are arranged in the superconducting switch station. The first bus section and the second bus section are connected by a normally closed bus sectionalizing switch. Among them, the first bus section is connected with a superconducting reactor. This can greatly improve the power supply reliability. The two bus sections adopt a closed-loop operation mode, which can realize the balanced distribution of the load, make full use of the equipment capacity, and effectively improve the overall power supply capacity; and the two bus sections can share the inductive reactive power centralized compensation of the superconducting reactor. Compared with the multi-point and multi-device compensation method, it saves the number of devices, cost and occupied space.

[0033] In the present invention, the bus sectionalizing switch is designed to include two normally closed sectionalizing switches connected in series. A superconducting fault current limiter is connected between the two sectionalizing switches. When a short-circuit fault occurs at any point on the two bus sections and their outgoing lines, the superconducting fault current limiter can play a role in restricting the current from the non-faulty bus section, thereby avoiding excessive short-circuit current at the fault point and greatly reducing the opening pressure of the circuit breaker.

[0034] The present invention connects and installs a superconducting reactor on the first bus section, which can effectively solve the problems of insufficient inductive reactive power compensation and high voltage level. In practice, the capacity of the superconducting reactor can be designed according to the reactive power reverse transmission situation under different operating modes of the incoming and outgoing lines of the two bus sections. In addition, a tap-changing switch is designed on the reactor to realize the sectional adjustment of the compensation capacity.

[0035] The present invention proposes a solution for sharing a refrigerator between a superconducting cable and superconducting power conversion equipment (including a superconducting reactor and a superconducting fault current limiter). It is designed to respectively arrange a first coil heat exchanger and a second coil heat exchanger in the cryostat of the superconducting cable and the cryostat of the superconducting power conversion equipment. Connect the outlet of the first coil heat exchanger to the inlet of the cryostat of the superconducting power conversion equipment, and connect the outlet of the cryostat of the superconducting power conversion equipment to the liquid nitrogen inlet of the superconducting cable. Thus, only a refrigerator needs to be configured in the cryostat of the superconducting cable, and the cryostat of the superconducting power conversion equipment does not need to be equipped with a refrigerator and only needs to be connected to the liquid nitrogen pipeline of the superconducting cable. After the cooling capacity of the refrigerator is transferred to the superconducting cable, the remaining cooling capacity can be transferred to the superconducting power conversion equipment, thereby improving the utilization rate of the refrigerator, reducing the number of refrigerators, and making the layout of the refrigerator in the substation more flexible, capable of meeting various requirements of substation design.

[0036] For the solution of sharing a refrigerator between a superconducting cable and superconducting power conversion equipment, the present invention also designs to respectively arrange a first coil heat exchanger and a second coil heat exchanger in the cryostat of the superconducting cable and the thermostat of the superconducting power conversion equipment. Connect the inlet of the second coil heat exchanger to the outlet of the first coil heat exchanger, and connect the outlet of the second coil heat exchanger to the liquid nitrogen inlet of the superconducting cable. Thus, a more compact design is achieved, and there is no need to set up a cryostat for the superconducting power conversion equipment. It can not only achieve the purpose of sharing a refrigerator, but also make the structure of the superconducting power conversion equipment simpler and smaller, which is beneficial to installing multiple superconducting power equipment in the superconducting switch station and improving the economy of construction and operation and maintenance. Brief Description of the Drawings

[0037] Figure 1 It is a schematic structural diagram of a traditional conventional switch station;

[0038] Figure 2 It is a schematic structural diagram of a superconducting switch station in Embodiment 1;

[0039] Figure 3 It is a schematic diagram of the working scheme of a traditional refrigerator for a superconducting cable;

[0040] Figure 4 It is a schematic diagram of the shared refrigerator scheme of a superconducting switch station in Embodiment 2;

[0041] Figure 5 It is a schematic diagram of the shared refrigerator scheme of a superconducting switch station in Embodiment 3. Detailed Embodiments

[0042] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0043] Embodiment 1

[0044] As Figure 1As shown, the sectional busbars of a conventional switchyard usually operate in an open-loop mode. The two busbars come from two different substations respectively, and the sectional switch is normally in the open state. One of the reasons for traditionally adopting this operation mode is to avoid excessive short-circuit current in the system; however, its disadvantage is relatively low power supply reliability. After a fault occurs, there will be a process of power outage, fault location, fault isolation, load transfer, and power restoration; moreover, during operation, phenomena such as unbalanced load distribution, coexistence of heavy load and light load are likely to occur.

[0045] Therefore, this solution designs to integrate equipment such as large-capacity switchyards, superconducting cables, superconducting reactors, and superconducting fault current limiters to establish a superconducting switchyard, as Figure 2 shown. The busbar sectional switch of the superconducting switchyard is composed of two switches connected in series. A superconducting fault current limiter is connected in series between the two switches. The two sectional switches are normally in the closed state, that is, adopting a closed-loop operation mode.

[0046] In addition, one superconducting reactor is installed on one of the busbars to effectively solve the problems of insufficient inductive reactive power compensation and relatively high voltage level; the capacity of the superconducting reactor is designed according to the reactive power reverse transmission conditions under different operation modes of the incoming and outgoing lines of the two busbars. When necessary, a tap switch is designed on the superconducting reactor to realize sectional adjustment of the compensation capacity.

[0047] In practical applications, the voltage class of the superconducting cable can be 110 kV, 35 kV, 10 kV, and the corresponding voltage class of the high-voltage substation can be 500 kV (330 kV), 220 kV, 110 kV (66 kV). In the engineering application of the superconducting switchyard, the 220 kV substation in the central urban area can be replaced or transformed into an 110 kV or 35 kV superconducting switchyard, and the original high-voltage transformer and related high-voltage substation equipment can be removed, thereby reducing the land occupation of power facilities and the impact of noise from high-voltage transformers on the urban environment.

[0048] Embodiment 2

[0049] As Figure 3 shown, in the current working scheme of the refrigerating machine of the superconducting cable, the coil heat exchanger is immersed in the cryostat of the superconducting cable. The inside of the coil heat exchanger is the first liquid nitrogen, which is connected to the liquid nitrogen inside the superconducting cable; the outside of the coil heat exchanger is the second liquid nitrogen, which is located inside the cryostat; the cold head of the refrigerating machine is immersed in the second liquid nitrogen inside the cryostat to provide cold for the cryostat to maintain the low temperature of the second liquid nitrogen; the second liquid nitrogen transfers the cold to the first liquid nitrogen inside the pipe through the coil heat exchanger; the first liquid nitrogen flows between the coil heat exchanger and the superconducting cable, thereby transferring the cold to the superconducting cable to ensure that the superconducting cable maintains the low-temperature superconducting state.

[0050] If a refrigeration design is carried out for the superconducting switch station proposed in the embodiment, it is often necessary to equip refrigerators for superconducting cables and superconducting power conversion equipment (superconducting reactors or superconducting fault current limiters) respectively, and redundant standby refrigerators also need to be configured, which will undoubtedly increase the construction cost and structural complexity of the superconducting switch station.

[0051] In this embodiment, considering that generally the superconducting cable requires a large amount of cooling, while the superconducting power conversion equipment requires a relatively small amount of cooling, with a difference of up to one order of magnitude. Therefore, on the basis of Embodiment 1, this embodiment proposes a working mode in which the superconducting cable and the superconducting power conversion equipment (superconducting reactor or superconducting fault current limiter) share a refrigerator, as Figure 4 shown. This embodiment is illustrated by taking a superconducting reactor as an example. Among them, the cold box of the superconducting cable is similar in structure to that in Figure 3 . The cold box of the superconducting reactor is not equipped with a refrigerator. The internal of the coil heat exchanger in the cold box of the superconducting reactor is the third liquid nitrogen, which is connected to the liquid nitrogen inside the superconducting reactor. The outside of the coil heat exchanger in the cold box of the superconducting reactor is the fourth liquid nitrogen; the outlet of the coil heat exchanger in the cold box of the superconducting cable is connected to the inlet of the cold box of the superconducting reactor, and the outlet of the cold box of the superconducting reactor is connected to the liquid nitrogen inlet of the superconducting cable.

[0052] During the working process of the refrigerator, the refrigerator transfers the cooling capacity to the first liquid nitrogen through the coil heat exchanger in the cold box of the superconducting cable. The first liquid nitrogen transfers the cooling capacity to the fourth liquid nitrogen through flow. The fourth liquid nitrogen transfers the cooling capacity to the third liquid nitrogen through the coil heat exchanger in the cold box of the superconducting reactor. The third liquid nitrogen flows between the coil heat exchanger in the cold box of the superconducting reactor and the superconducting reactor, thereby transferring the cooling capacity to the superconducting reactor to ensure that the superconducting reactor maintains the low-temperature superconducting state.

[0053] Thus, after the cooling capacity of the refrigerator is transferred to the superconducting cable, the remaining cooling capacity can be transferred to the superconducting reactor; thereby greatly improving the utilization rate of the refrigerator and reducing the number of refrigerators.

[0054] In addition, the refrigerator is large in volume and noisy, so there are relatively high requirements for the installation location of the refrigerator, and noise reduction measures need to be taken in the refrigerator room; in a substation, the installation locations of cables, reactors, and fault current limiters may be at a certain distance; this results in that in the conventional scheme, it is difficult to centrally arrange the refrigerators, leading to a large floor area and difficult layout of the refrigerators. In the scheme proposed in this embodiment, the cold box of the superconducting power conversion equipment does not need to be equipped with a refrigerator, and only needs to be connected to the liquid nitrogen pipeline of the superconducting cable to receive the cooling capacity, which is more flexible in the spatial layout of the substation and is easy to meet various requirements of the substation design.

[0055] Embodiment 3

[0056] This embodiment proposes a working mode in which the superconducting cable and the superconducting power conversion equipment (superconducting reactor or superconducting fault current limiter) share a refrigerator, as Figure 5As shown in the figure, this embodiment also takes the superconducting reactor as an example for illustration. The difference from the second embodiment is that in this embodiment, the coil heat exchanger is arranged inside the thermostat of the superconducting reactor. The inlet of the coil heat exchanger inside the thermostat of the superconducting reactor is connected to the outlet of the coil heat exchanger of the superconducting cable, and the outlet of the coil heat exchanger inside the thermostat of the superconducting reactor is connected to the liquid nitrogen inlet of the superconducting cable. The rest of the structural design is the same as that of the second embodiment.

[0057] Therefore, this embodiment can enable the superconducting cable and the superconducting power conversion equipment to share the refrigerator, and at the same time can eliminate the cold box of the superconducting power conversion equipment, realize a more compact structural design of the superconducting power conversion equipment, and reduce the installation volume of the superconducting power conversion equipment.

[0058] In summary, the superconducting switch station proposed by this solution has the advantage of large capacity. One superconducting switch station can replace 4 to 5 conventional switch stations. The incoming line of the superconducting switch station uses a large-capacity superconducting cable, and medium-voltage superconducting cables are used to send large-capacity electric energy from the suburbs into the superconducting switch station to serve as an extension of the medium- and low-voltage busbars in the suburban high-voltage substation. Applying this technical solution has the following advantages:

[0059] (1) Limiting short-circuit current

[0060] When a short-circuit fault occurs at any point on the two busbars and their outgoing lines, the superconducting fault current limiter can play a role to limit the current from the non-faulty busbar section, thereby avoiding excessive short-circuit current at the fault point and reducing the breaking pressure on the circuit breaker.

[0061] (2) High reliability

[0062] The power supply reliability is high, and the power supply will not be interrupted even if any one of the two power supply incoming lines fails.

[0063] (3) Strong power supply capacity

[0064] The loads of the two busbars are evenly distributed, and the capacity of the equipment is fully utilized, improving the overall power supply capacity.

[0065] The two busbars share the inductive reactive power centralized compensation of the superconducting reactor. Compared with the multi-point and multi-device compensation method, it saves the number of devices, cost, and occupied space.

[0066] (4) High utilization rate of the refrigerator

[0067] Installing multiple superconducting power equipment in a superconducting switch station can share the refrigerator, improving the economy of construction and operation and maintenance.

[0068] (5) The bus section switch is composed of two series-connected section switches and can be operated in an open-loop manner when necessary. When the superconducting fault current limiter fails or needs to be overhauled, the two section switches can be disconnected to cut off the power supply of the superconducting fault current limiter to ensure that the two busbars can still operate normally.

Claims

1. A superconducting switch station, characterized in that, It is connected to two substations respectively through superconducting cables, and the two substations supply power to the superconducting switchyard. A first bus section and a second bus section are arranged in the superconducting switchyard. The first bus section and the second bus section are connected through a normally closed bus sectionalizing switch. The first bus section is connected with a superconducting reactor. The bus sectionalizing switch includes two series-connected sectionalizing switches, and the two sectionalizing switches are normally in a closed state during normal operation. A superconducting fault current limiter is connected between the two sectionalizing switches; The cryostat of the superconducting cable is equipped with a refrigerator. A first coil heat exchanger and a second coil heat exchanger are respectively arranged in the cryostat of the superconducting cable and the cryostat of the superconducting substation equipment. The superconducting substation equipment includes a superconducting reactor and a superconducting fault current limiter. The inside of the first coil heat exchanger is filled with first liquid nitrogen, and the first liquid nitrogen is communicated with the liquid nitrogen inside the superconducting cable. The outside of the first coil heat exchanger is filled with second liquid nitrogen, and the cold head of the refrigerator is immersed in the second liquid nitrogen; The inside of the second coil heat exchanger is filled with third liquid nitrogen, and the third liquid nitrogen is communicated with the liquid nitrogen inside the superconducting substation equipment. The outside of the second coil heat exchanger is filled with fourth liquid nitrogen; The outlet of the first coil heat exchanger is connected to the inlet of the cryostat of the superconducting substation equipment, and the outlet of the cryostat of the superconducting substation equipment is connected to the liquid nitrogen inlet of the superconducting cable.

2. A superconducting switch station according to claim 1, characterized in that, The first bus section is connected to the superconducting reactor through a normally closed tapping switch.

3. A superconducting switch station according to claim 1, characterized in that, The capacity of the superconducting reactor is specifically designed according to the reactive power reverse transmission conditions under different operation modes of the incoming and outgoing lines of the two bus sections.

4. A superconducting switch station according to claim 1, characterized in that, The first bus section and the second bus section are respectively connected to the first substation and the second substation through superconducting cables.

5. A superconducting switch station according to claim 4, characterized in that, Both the first bus section and the second bus section are connected to the corresponding superconducting cables through normally closed switches.

6. A superconducting switch station according to claim 4, characterized in that, The superconducting cable is connected to the bus of the substation through a normally closed switch.

7. A working method of a superconducting switch station, applied to a superconducting switch station as described in claim 1, characterized in that Including: Two substations supply power to the superconducting switchyard through superconducting cables; The first bus section and the second bus section in the superconducting switchyard adopt a closed-loop operation mode to achieve balanced load distribution; The superconducting reactor connected to the first bus section is used for inductive reactive power compensation; When a short-circuit fault occurs at any point on the two bus sections and their outgoing lines, the superconducting fault current limiter is used to limit the current from the non-faulty bus section; When the superconducting fault current limiter fails or needs to be overhauled, the two sectionalizing switches are opened to cut off the power supply of the superconducting fault current limiter, so that the two bus sections can still operate normally.

8. A working method of a superconducting switch station according to claim 7, characterized in that, The compensation capacity of the superconducting reactor is adjusted in sections through a tapping switch.

9. A working method of a shared refrigerator for a superconducting switch station, applied to a superconducting switch station as described in claim 1, characterized in that, The refrigerator provides cooling capacity to the cryostat of the superconducting cable to maintain the low temperature of the second liquid nitrogen. The second liquid nitrogen transfers the cooling capacity to the first liquid nitrogen through the first coil heat exchanger. The first liquid nitrogen flows between the first coil heat exchanger and the superconducting cable to transfer the cooling capacity to the superconducting cable, ensuring that the superconducting cable is maintained in the low-temperature superconducting state; The first liquid nitrogen also transfers the cooling capacity to the fourth liquid nitrogen through flow. The fourth liquid nitrogen transfers the cooling capacity to the third liquid nitrogen through the second coil heat exchanger. The third liquid nitrogen flows between the second coil heat exchanger and the superconducting substation equipment, thereby transferring the cooling capacity to the superconducting substation equipment, ensuring that the superconducting substation equipment is maintained in the low-temperature superconducting state.

Images