Superconducting switching station and working method thereof

Abstract

The invention relates to a superconducting switching station and a working method thereof.The superconducting switching station is connected with two substations through superconducting cables, the two substations supply power to the superconducting switching station, and a first bus section and a second bus section are arranged in the superconducting switching station; the first bus section and the second bus section are connected through a normally-closed bus section switch, and the first bus section is connected with a superconducting reactor. Compared with the prior art, the high-capacity switching station, the superconducting cable, the superconducting reactor, the superconducting current limiter and other devices are integrated to establish the superconducting switching station, the closed-loop operation of the bus is realized, the short-circuit current can be limited, and the power supply capability and the power supply reliability can be improved.

Description

Technical Field

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

[0002] At present, substations in urban central areas often have limitations such as small construction land area and tight outgoing line positions. When users apply for power supply, they will face the problem of no available positions. Traditionally, most of them adopt the method of deploying switch stations to expand the power supply range of substations, but ordinary switch stations are limited by the transmission capacity of incoming lines, and the power supply capacity of a single site cannot effectively match the substation capacity.

[0003] Based on this, the existing technology considers the application of superconducting power equipment such as superconducting cables, superconducting reactors, and superconducting current limiters in the central urban area of ​​the city, so as to improve the power supply capacity and reliability of the central urban power grid. 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 to 6 conventional cables of the same voltage, or replace conventional cables with 2 higher voltage levels. For example: 35kV superconducting cable is equivalent to the transmission capacity of 220kV ordinary cable, and 10kV superconducting cable is equivalent to the transmission capacity of 110kV ordinary cable. The use of superconducting cable transmission can significantly reduce the voltage level of the substation and realize the relocation of high-voltage substation equipment in the central urban area to the suburbs; In addition, with the increasing number of cable lines in the power grid, a large amount of reactive power is reversed, resulting in insufficient inductive reactive power compensation and high voltage levels. It is necessary to install shunt reactors. Since oil-immersed reactors are noisy and dry-type reactors occupy a large area, they are difficult to use in urban substations with narrow space. Superconducting reactors that use superconducting materials as working windings have the advantages of small footprint and low noise compared to conventional reactors. The superconducting current limiter is in a "superconducting state" during normal operation, with very low impedance. When a fault occurs, it can respond quickly and become a larger impedance to suppress the short-circuit current. After the fault is cleared, it can automatically return to the "superconducting state" in time. It can quickly, smoothly and effectively limit the short-circuit current of the system, greatly reducing the breaking pressure of the circuit breaker. The conventional method is mainly to increase the impedance of the power grid through high-impedance transformers or current limiting reactors. These measures will undoubtedly increase the transmission loss and voltage drop of the power grid.

[0004] However, in order to fully utilize the advantages of superconducting power equipment, it is not enough to replace a single superconducting device. Therefore, it is urgently necessary to integrate large-capacity switch stations, superconducting cables, superconducting reactors, superconducting current limiters and other equipment to establish superconducting switch stations. Summary of the invention

[0005] The purpose of the present invention is to provide a superconducting switch station and a working method thereof in order to overcome the defects of the above-mentioned prior art, realize bus closed-loop operation, limit short-circuit current, and improve power supply capacity and power supply reliability.

[0006] The objective of the present invention can be achieved by the following technical scheme: 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 busbar section 1 and a busbar section 2 are arranged in the superconducting switch station. The busbar section 1 and the busbar section 2 are connected by a normally closed busbar sectioning switch, and the busbar section 1 is connected to a superconducting reactor.

[0007] Furthermore, the busbar section switch includes two section switches connected in series, and the two section switches are usually in a closed state.

[0008] Furthermore, a superconducting current limiter is connected between the two segment switches.

[0009] Furthermore, the busbar section is connected to the superconducting reactor via a normally closed tap switch.

[0010] Furthermore, 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.

[0011] Furthermore, the busbar section 1 and busbar section 2 are connected to the first substation and the second substation respectively through superconducting cables.

[0012] Furthermore, the busbar section 1 and the busbar section 2 are both connected to corresponding superconducting cables through normally closed switches.

[0013] Furthermore, the superconducting cable is connected to a busbar of the substation through a normally closed switch.

[0014] A method for operating a superconducting switch station includes: using two substations to supply power to the superconducting switch station through superconducting cables; The first and second busbar sections in the superconducting switch station adopt a closed-loop operation mode to achieve balanced load distribution; Use superconducting reactors connected to a section of busbar for inductive reactive power compensation; When a short circuit fault occurs at any point of the two busbar sections and their outgoing lines, the superconducting current limiter is used to limit the current from the non-faulty busbar section; When the superconducting current limiter fails or needs to be repaired, the two section switches are disconnected to cut off the power supply to the superconducting current limiter, so that the two sections of the busbar can still operate normally.

[0015] Furthermore, the superconducting reactor realizes segmented adjustment of compensation capacity through a tap switch.

[0016] Furthermore, the cold box of the superconducting cable is equipped with a refrigerator, the cold box of the superconducting cable and the cold box of the superconducting power conversion equipment are respectively provided with a first coil heat exchanger and a second coil heat exchanger, the superconducting power conversion equipment includes a superconducting reactor and a superconducting current limiter, the first coil heat exchanger has a first liquid nitrogen inside, the first liquid nitrogen is connected to the liquid nitrogen inside the superconducting cable, the first coil heat exchanger has a second liquid nitrogen outside, and the cold head of the refrigerator is immersed in the second liquid nitrogen; The interior of the second coil heat exchanger is filled with third liquid nitrogen, which is connected to the liquid nitrogen inside the superconducting power conversion equipment, and the exterior 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 a superconducting power conversion equipment cold box, and the outlet of the superconducting power conversion equipment cold box is connected to the liquid nitrogen inlet of the superconducting cable.

[0017] A shared refrigerator working method for a superconducting switch station, wherein the refrigerator provides cold energy to a cold box of a superconducting cable to maintain a low temperature of a second liquid nitrogen, the second liquid nitrogen transfers the cold energy to the first liquid nitrogen through a first coil heat exchanger, and the first liquid nitrogen flows between the first coil heat exchanger and the superconducting cable to transfer the cold energy to the superconducting cable, thereby ensuring that the superconducting cable is maintained in a low-temperature superconducting state; The first liquid nitrogen also transfers cold energy to the fourth liquid nitrogen by flowing, and the fourth liquid nitrogen transfers cold energy 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 transformer equipment, thereby transferring cold energy to the superconducting transformer equipment, ensuring that the superconducting transformer equipment is maintained in a low-temperature superconducting state.

[0018] Furthermore, the cold box of the superconducting cable is equipped with a refrigerator, the cold box of the superconducting cable and the thermostat of the superconducting power conversion equipment are respectively provided with a first coil heat exchanger and a second coil heat exchanger, the superconducting power conversion equipment includes a superconducting reactor and a superconducting current limiter, the first coil heat exchanger is filled with first liquid nitrogen, the first liquid nitrogen is connected with the liquid nitrogen inside the superconducting cable, the first coil heat exchanger is filled with second liquid nitrogen outside, and the cold head of the refrigerator is immersed in the second liquid nitrogen; 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.

[0019] A shared refrigerator working method for a superconducting switch station, wherein the refrigerator provides cold energy to a cold box of a superconducting cable to maintain a low temperature of a second liquid nitrogen, the second liquid nitrogen transfers the cold energy to the first liquid nitrogen through a first coil heat exchanger, and the first liquid nitrogen flows between the first coil heat exchanger and the superconducting cable to transfer the cold energy to the superconducting cable, thereby ensuring that the superconducting cable is maintained in a low-temperature superconducting state; The first liquid nitrogen also transfers cold energy to the second coil heat exchanger through flow, ensuring that the thermostat of the superconducting power conversion equipment is maintained in a low-temperature superconducting state.

[0020] Compared with the prior art, the present invention has the following advantages: The present invention designs a superconducting switch station to be connected to two substations respectively through superconducting cables, and the two substations supply power to the superconducting switch station, and a busbar section 1 and a busbar section 2 are arranged in the superconducting switch station, and the busbar section 1 and the busbar section 2 are connected through a normally closed busbar sectioning switch, wherein the busbar section 1 is connected to a superconducting reactor. This can greatly improve the reliability of power supply, and the closed-loop operation mode is adopted between the two busbar sections, which can realize load balanced distribution, so that the equipment capacity is fully utilized, and the overall power supply capacity is effectively improved; and the two busbar sections can share the inductive reactive concentrated compensation of the superconducting reactor, which saves the number of equipment, cost and occupied space compared with the multi-point multi-device compensation mode.

[0021] In the present invention, the busbar section switch is designed to include two normally closed section switches connected in series, and a superconducting current limiter is connected between the two section switches. When a short circuit fault occurs at any point of the two busbar sections and their outgoing lines, the superconducting current limiter can play a role to limit the current from the non-fault busbar section, thereby avoiding excessive short-circuit current at the fault point and greatly reducing the breaking pressure of the circuit breaker.

[0022] The present invention connects and installs a superconducting reactor on one section of the busbar, 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 conditions under different operating modes of the incoming and outgoing lines of the two sections of the busbar. In addition, a tap switch is designed on the reactor to achieve segmented adjustment of the compensation capacity.

[0023] The present invention proposes a scheme that a superconducting cable and a superconducting transformer equipment (including a superconducting reactor and a superconducting current limiter) share a refrigerator. A first coil heat exchanger and a second coil heat exchanger are respectively arranged in a cold box of the superconducting cable and a cold box of the superconducting transformer equipment, and an outlet of the first coil heat exchanger is connected to an inlet of a cold box of the superconducting transformer equipment, and an outlet of the cold box of the superconducting transformer equipment is connected to a liquid nitrogen inlet of the superconducting cable. Therefore, only a refrigerator needs to be arranged in the cold box of the superconducting cable, and the cold box of the superconducting transformer equipment does not need to be equipped with a refrigerator, and only needs to be connected to a liquid nitrogen pipeline of the superconducting cable. After the cold capacity of the refrigerator is transferred to the superconducting cable, the remaining cold capacity can be transferred to the superconducting transformer equipment, thereby improving the utilization rate of the refrigerator, reducing the number of refrigerators, and making the refrigerator more flexible in the spatial arrangement of the substation, and being able to meet various requirements of the substation design.

[0024] The present invention is directed to a solution in which a superconducting cable and a superconducting transformer substation share a refrigerator, and further designs to respectively set a first coil heat exchanger and a second coil heat exchanger in a cold box of the superconducting cable and a thermostat of the superconducting transformer substation, 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 a cold box of the superconducting transformer substation, which can not only achieve the purpose of sharing a refrigerator, but also make the structure of the superconducting transformer substation simpler and smaller in size, which is conducive to installing multiple superconducting power equipment in a superconducting switch station and improving the economy of construction and operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of a traditional conventional switch station; Figure 2 It is a structural schematic diagram of a superconducting switch station in Embodiment 1; Figure 3 This is a schematic diagram of the working scheme of a traditional refrigerator for superconducting cables; Figure 4 This is a schematic diagram of a shared refrigerator solution for a superconducting switch station in Embodiment 2; Figure 5 Schematic diagram of the shared refrigerator solution for the superconducting switch station in Example 3. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Embodiment 1

[0028] like Figure 1 As shown in the figure, the segmented busbars of conventional switch stations usually adopt open-loop operation mode, and the two segments of busbars come from two different substations, and the segmented switches are usually disconnected. One of the reasons for adopting this operation mode is to avoid excessive short-circuit current in the system; however, its disadvantage is that the power supply reliability is low, and after a fault occurs, it will go through the process of power outage, fault location, fault isolation, load transfer, and power supply restoration; moreover, it is easy to have unbalanced load distribution and coexistence of heavy load and light load during operation.

[0029] To this end, this scheme design integrates large-capacity switch stations, superconducting cables, superconducting reactors, superconducting current limiters and other equipment to build superconducting switch stations, such as Figure 2 As shown, the busbar section switch of the superconducting switch station is composed of two switches connected in series, a superconducting current limiter is connected in series between the two switches, and the two section switches are usually in a closed state, that is, a closed-loop operation mode is adopted.

[0030] In addition, a superconducting reactor is installed on one of the bus sections to effectively solve the problems of insufficient inductive reactive power compensation and high voltage level; the capacity of the superconducting reactor is designed according to the reactive power backflow conditions under different operating modes of the two bus sections' incoming and outgoing lines, and a tap switch is designed on the superconducting reactor when necessary to achieve segmented adjustment of the compensation capacity.

[0031] In practical applications, the voltage level of superconducting cables can be 110kV, 35kV, and 10kV, and the corresponding voltage level of high-voltage substations can be 500kV (330kV), 220kV, and 110kV (66kV). In the engineering application of superconducting switch stations, the 220kV substations in the central urban area can be replaced or transformed into 110kV or 35kV superconducting switch stations, and the original high-voltage transformers and related high-voltage substation equipment can be removed, thereby reducing the land occupation of power facilities and reducing the impact of high-voltage transformer noise on the urban environment.

[0032] Embodiment 2

[0033] like Figure 3 As shown, in the current working scheme of the refrigerator of the superconducting cable, the coil heat exchanger is immersed in the cold box 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 cold box; the cold head of the refrigerator is immersed in the second liquid nitrogen in the cold box, providing cold energy for the cold box to maintain the low temperature of the second liquid nitrogen; the second liquid nitrogen passes through the coil heat exchanger to transfer the cold energy to the first liquid nitrogen in the tube; the first liquid nitrogen flows between the coil heat exchanger and the superconducting cable, thereby transferring the cold energy to the superconducting cable, ensuring that the superconducting cable is maintained in a low-temperature superconducting state.

[0034] If a cooling design is performed for the superconducting switch station proposed in the embodiment, it is often necessary to equip the superconducting cables and superconducting transformer equipment (superconducting reactors or superconducting current limiters) with refrigerators respectively, and redundant backup refrigerators are also required, which will undoubtedly increase the construction cost and structural complexity of the superconducting switch station.

[0035] This embodiment takes into account that the cooling capacity required by superconducting cables is usually large, while the cooling capacity required by superconducting transformers is relatively small, and the difference can reach one order of magnitude. Therefore, based on the first embodiment, this embodiment proposes a working mode in which superconducting cables and superconducting transformers (superconducting reactors or superconducting current limiters) share a refrigerator, such as Figure 4 This embodiment is described by taking a superconducting reactor as an example, wherein the cold box of the superconducting cable and Figure 3The structure is similar. The cold box of the superconducting reactor is not equipped with a refrigerator. The coil heat exchanger in the cold box of the superconducting reactor is filled with the third liquid nitrogen, which is connected to the liquid nitrogen in the superconducting reactor. The coil heat exchanger in the cold box of the superconducting reactor is filled with 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 inlet of the liquid nitrogen in the superconducting cable.

[0036] During the operation of the refrigerator, the refrigerator transfers cold energy to the first liquid nitrogen through the coil heat exchanger in the superconducting cable cold box, the first liquid nitrogen transfers cold energy to the fourth liquid nitrogen through flow, the fourth liquid nitrogen transfers cold energy to the third liquid nitrogen through the coil heat exchanger in the superconducting reactor cold box, the third liquid nitrogen flows between the coil heat exchanger in the superconducting reactor cold box and the superconducting reactor, thereby transferring cold energy to the superconducting reactor, ensuring that the superconducting reactor is maintained in a low-temperature superconducting state.

[0037] Therefore, after the coldness of the refrigerator is transferred to the superconducting cable, the remaining coldness can be transferred to the superconducting reactor; thereby greatly improving the utilization rate of the refrigerator and reducing the number of refrigerators.

[0038] In addition, the refrigerator is large in size and noisy, so the installation location of the refrigerator has high requirements, and the refrigeration room needs to take noise reduction measures; in the substation, the installation locations of cables, reactors, and current limiters may be a certain distance apart; this makes it difficult to centrally arrange the refrigerator in the conventional solution, resulting in a large footprint and difficult layout. In the solution proposed in this embodiment, the cold box of the superconducting substation equipment does not need to be equipped with a refrigerator, but only needs to be connected to the liquid nitrogen pipeline of the superconducting cable to receive the cold, which is more flexible in the substation space layout and easy to meet various requirements of substation design.

[0039] Embodiment 3

[0040] This embodiment proposes a working mode in which a superconducting cable and a superconducting power conversion device (superconducting reactor or superconducting current limiter) share a refrigerator, such as Figure 5 As shown, this embodiment is also described by taking the superconducting reactor as an example. 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.

[0041] Therefore, this embodiment can realize that the superconducting cable and the superconducting substation equipment share a refrigerator, and at the same time can save the cold box of the superconducting substation equipment, realize a more compact structural design of the superconducting substation equipment, and reduce the installation volume of the superconducting substation equipment.

[0042] In summary, the superconducting switch station proposed in this scheme 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 adopts large-capacity superconducting cables. Medium-voltage superconducting cables are used to send large-capacity electric energy from the suburbs to the superconducting switch station, which serves as an extension of the medium and low voltage busbars of the suburban high-voltage substation. The application of this technical scheme has the following advantages: (1) Limit short-circuit current If a short circuit fault occurs at any point of the two busbar sections and their outgoing lines, the superconducting current limiter can play a role and limit the current from the non-faulty busbar section, thereby avoiding excessive short-circuit current at the fault point and reducing the breaking pressure of the circuit breaker.

[0043] (2) High reliability The power supply reliability is high, and a failure in either of the two power supply lines will not cause power interruption.

[0044] (3) Strong power supply capability The load of the two bus sections is evenly distributed, the capacity of the equipment is fully utilized, and the overall power supply capacity is improved.

[0045] The centralized compensation of inductive reactive power by sharing superconducting reactors on two bus sections saves the number of equipment, cost and occupied space compared with the multi-point multi-device compensation method.

[0046] (4) High utilization rate of refrigerator By installing multiple superconducting power equipment in a superconducting switch station, the refrigerator can be shared, improving the economy of construction and operation and maintenance.

[0047] (5) The busbar section switch consists of two section switches connected in series and can be operated in an open loop when necessary. When the superconducting current limiter fails or needs maintenance, the two section switches can be disconnected to shut down the superconducting current limiter and ensure that the two sections of the busbar can still operate normally.

Claims

1. A superconducting switch station, characterized in that: 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 busbar section 1 and a busbar section 2 are arranged in the superconducting switch station. The busbar section 1 and the busbar section 2 are connected through a normally closed busbar sectioning switch, and a superconducting reactor is connected to the busbar section 1.

2. A superconducting switch station according to claim 1, characterized in that: The busbar section switch comprises two section switches connected in series, and the two section switches are usually in a closed state.

3. A superconducting switch station according to claim 2, characterized in that: A superconducting current limiter is connected between the two segment switches.

4. A superconducting switch station according to claim 1, characterized in that: The busbar section is connected to the superconducting reactor through a normally closed tap switch.

5. The 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 sections of busbars.

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

7. A superconducting switch station according to claim 6, characterized in that: The busbar section 1 and busbar section 2 are both connected to corresponding superconducting cables through normally closed switches.

8. The superconducting switch station according to claim 6, characterized in that: The superconducting cable is connected to a busbar of a substation through a normally closed switch.

9. The superconducting switch station according to claim 3, characterized in that: The cold box of the superconducting cable is equipped with a refrigerator, the cold box of the superconducting cable and the cold box of the superconducting power conversion equipment are respectively provided with a first coil heat exchanger and a second coil heat exchanger, the superconducting power conversion equipment includes a superconducting reactor and a superconducting current limiter, the first coil heat exchanger is filled with first liquid nitrogen, the first liquid nitrogen is connected with the liquid nitrogen in the superconducting cable, the first coil heat exchanger is filled with second liquid nitrogen outside, and the cold head of the refrigerator is immersed in the second liquid nitrogen; The interior of the second coil heat exchanger is filled with third liquid nitrogen, which is connected to the liquid nitrogen inside the superconducting power conversion equipment, and the exterior 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 a superconducting power conversion equipment cold box, and the outlet of the superconducting power conversion equipment cold box is connected to the liquid nitrogen inlet of the superconducting cable.

10. The superconducting switch station according to claim 3, characterized in that: The cold box of the superconducting cable is equipped with a refrigerator, the cold box of the superconducting cable and the thermostat of the superconducting power conversion equipment are respectively provided with a first coil heat exchanger and a second coil heat exchanger, the superconducting power conversion equipment includes a superconducting reactor and a superconducting current limiter, the first coil heat exchanger is filled with first liquid nitrogen, the first liquid nitrogen is connected with the liquid nitrogen in the superconducting cable, the first coil heat exchanger is filled with second liquid nitrogen outside, and the cold head of the refrigerator is immersed in the second liquid nitrogen; 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.

11. A method for operating a superconducting switch station, applied to a superconducting switch station as claimed in claim 3, characterized in that: include: The superconducting switch station is powered by two substations through superconducting cables; The first and second busbar sections in the superconducting switch station adopt a closed-loop operation mode to achieve balanced load distribution; Use superconducting reactors connected to a section of busbar for inductive reactive power compensation; When a short circuit fault occurs at any point of the two busbar sections and their outgoing lines, the superconducting current limiter is used to limit the current from the non-faulty busbar section; When the superconducting current limiter fails or needs to be repaired, the two section switches are disconnected to cut off the power supply to the superconducting current limiter, so that the two sections of the busbar can still operate normally.

12. A superconducting switch station operating method according to claim 11, characterized in that: The superconducting reactor realizes segmented adjustment of compensation capacity through a tap switch.

13. A shared refrigerator operating method for a superconducting switch station, applied to a superconducting switch station as claimed in claim 9, characterized in that: The refrigerator provides cold energy to the cold box of the superconducting cable to maintain the low temperature of the second liquid nitrogen. The second liquid nitrogen transfers the cold energy 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 cold energy to the superconducting cable, thereby ensuring that the superconducting cable is maintained in a low-temperature superconducting state. The first liquid nitrogen also transfers cold energy to the fourth liquid nitrogen by flowing, and the fourth liquid nitrogen transfers cold energy 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 transformer equipment, thereby transferring cold energy to the superconducting transformer equipment, ensuring that the superconducting transformer equipment is maintained in a low-temperature superconducting state.

14. A shared refrigerator operating method for a superconducting switch station, applied to a superconducting switch station as claimed in claim 10, characterized in that: The refrigerator provides cold energy to the cold box of the superconducting cable to maintain the low temperature of the second liquid nitrogen. The second liquid nitrogen transfers the cold energy 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 cold energy to the superconducting cable, thereby ensuring that the superconducting cable is maintained in a low-temperature superconducting state. The first liquid nitrogen also transfers cold energy to the second coil heat exchanger through flow, ensuring that the thermostat of the superconducting power conversion equipment is maintained in a low-temperature superconducting state.

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