阅读说明：本技术 一种超导电缆制冷系统 (Superconducting cable refrigerating system ) 是由 吴小辰 胡子珩 余建国 章彬 汪桢子 王�琦 汪伟 于 2020-12-10 设计创作，主要内容包括：本发明提供提出一种超导电缆制冷系统,包括测控模块、制冷主模块、液氮循环管道、制冷备用模块、传感模块；其中传感模块实时检测制冷主模块的运行状态参数,测控模块响应于接收到传感模块发送的制冷主模块的运行状态参数,判断制冷主模块是否故障,若故障,则发送指令控制制冷主模块停机,并控制制冷备用模块启动,当制冷机组出现故障时,超导电缆不需要立刻切除,从而提高了超导电缆系统并网运行的供电可靠性。(The invention provides a superconducting cable refrigerating system which comprises a measurement and control module, a refrigerating main module, a liquid nitrogen circulating pipeline, a refrigerating standby module and a sensing module, wherein the measurement and control module is connected with the refrigerating main module; the sensing module detects the running state parameters of the refrigeration main module in real time, the measurement and control module judges whether the refrigeration main module fails or not in response to receiving the running state parameters of the refrigeration main module sent by the sensing module, if the refrigeration main module fails, an instruction is sent to control the refrigeration main module to stop and control the refrigeration standby module to start, and when a refrigeration unit fails, a superconducting cable does not need to be cut off immediately, so that the power supply reliability of the superconducting cable system in grid-connected operation is improved.)

1. A superconducting cable refrigerating system is applied to cooling of a superconducting cable and is characterized by comprising a measurement and control module, a refrigerating main module, a liquid nitrogen circulating pipeline, a refrigerating standby module and a sensing module;

the liquid nitrogen circulation pipeline comprises a liquid nitrogen outlet and a liquid nitrogen inlet, the liquid nitrogen outlet is communicated with an inlet of a liquid nitrogen channel of the superconducting cable, the liquid nitrogen inlet is communicated with an outlet of the liquid nitrogen channel of the superconducting cable, and cooling liquid nitrogen circularly flows in the liquid nitrogen circulation pipeline;

the refrigeration main module is used for cooling the cooling liquid nitrogen circulating and flowing in the liquid nitrogen circulating pipeline in a first refrigeration mode;

the sensing module is at least used for detecting the state information of the refrigeration main module in real time and sending the state information of the refrigeration main module to the measurement and control module;

the measurement and control module is at least used for receiving the state information of the main refrigeration module, judging whether the main refrigeration module has a fault according to the state information of the main refrigeration module, controlling the main refrigeration module to stop working when the main refrigeration module has the fault, and controlling the standby refrigeration module to cool the cooling liquid nitrogen circulating and flowing in the liquid nitrogen circulating pipeline in a second refrigeration mode.

2. The superconducting cable refrigeration system according to claim 1, wherein the refrigeration main module includes a refrigeration unit, a supercooled liquid nitrogen dewar and a circulating liquid nitrogen heat exchanger; supercooled liquid nitrogen is stored in the supercooled liquid nitrogen dewar, and the circulating liquid nitrogen heat exchanger is arranged in the supercooled liquid nitrogen dewar; the refrigerating unit is arranged above the super-cooled liquid nitrogen Dewar; the refrigerating unit is used for refrigerating the supercooled liquid nitrogen in the supercooled liquid nitrogen Dewar and maintaining the supercooled liquid nitrogen in the supercooled liquid nitrogen Dewar within a target temperature range.

3. The superconducting electrical cable refrigeration system of claim 2 wherein the refrigeration main module further includes a nitrogen reliquefier disposed above and in communication with the subcooled liquid nitrogen dewar; the refrigerating unit is arranged above the nitrogen reliquefier;

part of supercooled liquid nitrogen in the supercooled liquid nitrogen dewar is evaporated into the nitrogen reliquefier after heat exchange; the refrigerating unit is used for condensing gas entering the nitrogen reliquefier to obtain cooled liquid nitrogen, and the cooled liquid nitrogen obtained by condensation flows back to the supercooled liquid nitrogen dewar under the action of gravity.

4. The superconducting cable refrigeration system according to claim 3, wherein a first through hole and a second through hole are formed at the top of the supercooled liquid nitrogen dewar, the first through hole is disposed away from the circulating liquid nitrogen heat exchanger, and the second through hole is disposed close to the circulating liquid nitrogen heat exchanger; the bottom of the nitrogen reliquefier is provided with a liquid nitrogen backflow through hole, and the right side wall of the nitrogen reliquefier is provided with a nitrogen inlet hole; the liquid nitrogen backflow through hole is communicated with the first through hole and is arranged in an up-and-down corresponding manner with the first through hole; the nitrogen inlet hole is communicated with the second through hole through a pipeline.

5. The superconducting electrical cable refrigeration system of claim 2 wherein the refrigeration backup module includes a vacuum pump, a buffer tank, a regulator valve, a first air bath vaporizer; one end of the vacuum pump, one end of the buffer tank, one end of the regulating valve and one end of the first air bath type vaporizer are sequentially connected through a pipeline; a third through hole is formed in the side wall of the super-cooling liquid nitrogen Dewar; the other end of the first air bath type vaporizer is communicated with the third through hole through a pipeline;

wherein the vacuum pump is used for providing pumping power to pump away nitrogen in the supercooled liquid nitrogen dewar, reducing the pressure in the supercooled liquid nitrogen dewar and maintaining the supercooled liquid nitrogen in the supercooled liquid nitrogen dewar in a target temperature range; the buffer tank is used for buffering gas in the nitrogen pumping process, the regulating valve is used for regulating the flow of the gas in the pipeline, and the buffer tank and the regulating valve jointly play a role in stabilizing the pumping-out pressure in a target range; the air bath vaporizer is used to heat the low temperature nitrogen to room temperature.

6. The superconducting cable cooling system of claim 5, wherein the liquid nitrogen circulation pipe includes a first pipe, a second pipe, a third pipe, and a fourth pipe; the circulating liquid nitrogen heat exchanger comprises a first heat exchanger and a second heat exchanger;

one end of the first pipeline is arranged as the liquid nitrogen inlet, and the other end of the first pipeline is used for being connected with one end of a first heat exchanger so as to send the backflow liquid nitrogen at the outlet of the superconducting cable liquid nitrogen channel to the first heat exchanger for carrying out first heat exchange cooling on the backflow liquid nitrogen;

one end of the second pipeline is used for being connected with the other end of the first heat exchanger so as to receive the returned liquid nitrogen after the first heat exchange and cooling is carried out by the first heat exchanger, and the other end of the second pipeline is connected with one end of a liquid nitrogen pump;

one end of the third pipeline is connected with the other end of the liquid nitrogen pump, and the other end of the third pipeline is used for being connected with one end of the second heat exchanger, so that the backflow liquid nitrogen subjected to the first heat exchange cooling by the first heat exchanger is sent to the second heat exchanger to be subjected to the second heat exchange cooling of the backflow liquid nitrogen;

one end of the fourth pipeline is arranged as the liquid nitrogen outlet, and the other end of the fourth pipeline is used for being connected with the other end of the second heat exchanger so as to receive the returned liquid nitrogen which is subjected to the second heat exchange cooling through the second heat exchanger and output the liquid nitrogen to the inlet of the liquid nitrogen channel of the superconducting cable.

7. The superconducting cable cooling system of claim 6, wherein the number of the liquid nitrogen pumps is 2, a first liquid nitrogen pump and a second liquid nitrogen pump; the liquid nitrogen circulating pipeline structure also comprises a fifth pipeline, a first three-way valve, a second three-way valve, a third three-way valve and a throttle valve;

the other end of the second pipeline is connected with a first end of a first three-way valve;

the second end of the first three-way valve is connected with one end of the first liquid nitrogen pump, and the other end of the first liquid nitrogen pump is connected with one end of a third pipeline;

the third end of the first three-way valve is connected with one end of the second liquid nitrogen pump, and the other end of the second liquid nitrogen pump is connected with one end of a third pipeline;

the second end of the first three-way valve is connected with one end of the first liquid nitrogen pump through a first stop valve, and the other end of the first liquid nitrogen pump is connected with the first end of the second three-way valve through a second stop valve;

the third end of the first three-way valve is connected with one end of the second liquid nitrogen pump through a second stop valve, and the other end of the second liquid nitrogen pump is connected with the third end of the second three-way valve through a fourth stop valve;

and the first end of the third three-way valve is connected with the second end of the second three-way valve, the second end of the third three-way valve is connected with one end of the third pipeline, the third end of the third three-way valve is connected with one end of the fifth pipeline through the throttle valve, and the other end of the fifth pipeline is led into the supercooled liquid nitrogen dewar.

8. A superconducting cable refrigerating system according to claim 7, wherein a fifth stop valve and a first vent valve are provided on the first pipe, a second vent valve and a first safety valve are provided on the second pipe, a third vent valve and a second safety valve are provided on the third pipe, and a sixth stop valve, a fourth vent valve, and a bypass valve are provided on the fourth pipe; a fifth exhaust valve and a third safety valve are arranged on the buffer tank; and a sixth exhaust valve and a fourth safety valve are arranged at the inlet pipeline of the first air bath type vaporizer.

9. The superconducting electrical cable refrigeration system of claim 8 further comprising a liquid nitrogen supplement; the liquid nitrogen supplementing device comprises a liquid nitrogen storage tank and a second air bath type vaporizer, a seventh exhaust valve, a fifth safety valve, a liquid injection valve and a one-way valve are arranged on the liquid nitrogen storage tank, and supercooled liquid nitrogen is stored in the liquid nitrogen storage tank; the top of one side wall of the liquid nitrogen storage tank is provided with a first opening, the bottom of the side wall of the liquid nitrogen storage tank is provided with a second opening, and the middle of the other side wall of the liquid nitrogen storage tank is provided with a third opening;

the output end of the second air bath type vaporizer is communicated with the first opening through a pipeline, and the input end of the second air bath type vaporizer is communicated with the second opening through a pipeline and a seventh stop valve; the third opening is connected with the third pipeline through a pipeline and a transfusion valve;

the measurement and control device is specifically used for controlling the second air bath type vaporizer to heat the liquid nitrogen entering the second air bath type vaporizer from the second opening hole into nitrogen gas, and sending the nitrogen gas into the liquid nitrogen storage tank through the first opening hole, so that the pressure of the nitrogen gas is used as liquid feeding power.

10. The superconducting cable refrigeration system of claim 9, wherein the sensor module includes a temperature sensor, a level gauge and a first pressure sensor disposed in the subcooled liquid nitrogen dewar and a flow meter disposed on the fourth conduit;

the temperature sensor is used for detecting the liquid nitrogen temperature parameter in the supercooled liquid nitrogen Dewar in real time; the liquid level meter is used for detecting liquid nitrogen liquid level parameters in the supercooled liquid nitrogen dewar in real time; the first pressure sensor is used for detecting liquid nitrogen pressure parameters in the supercooled liquid nitrogen dewar in real time; the liquid nitrogen state parameters in the supercooled liquid nitrogen Dewar comprise the liquid nitrogen temperature parameter, the liquid nitrogen liquid level parameter and the liquid nitrogen pressure parameter; the flowmeter is used for detecting a liquid nitrogen flow signal on the fourth pipeline in real time and sending the liquid nitrogen flow signal to the measurement and control device;

the measurement and control module is used for judging whether the refrigerating unit is in fault or not according to a comparison result of the liquid nitrogen temperature parameter and a preset temperature threshold value, a comparison result of the liquid nitrogen liquid level parameter and a preset liquid level threshold value and a comparison result of the liquid nitrogen pressure parameter and a preset pressure threshold value;

the measurement and control device is used for judging whether the flow of liquid nitrogen in the cooling circulation pipeline is low or not according to the liquid nitrogen flow signal, if so, the seventh stop valve and the infusion valve are controlled to be switched to the corresponding position states, the second air bath type vaporizer is started to provide liquid feeding power, and the supercooled liquid nitrogen in the liquid nitrogen storage tank is fed into the cooling circulation pipeline to supplement the liquid nitrogen;

the measurement and control device is used for judging whether the liquid nitrogen liquid level in the supercooled liquid nitrogen Dewar is low according to the liquid nitrogen liquid level signal, if so, the throttle valve, the seventh stop valve and the infusion valve are switched to corresponding position states, the second air bath type vaporizer is started to provide liquid conveying power, the supercooled liquid nitrogen in the liquid nitrogen storage tank is conveyed to the cooling circulation pipeline, and the supplemented supercooled liquid nitrogen finally passes through the throttle valve and the fifth pipeline and enters the supercooled liquid nitrogen Dewar to supplement the liquid nitrogen.

Technical Field

The invention relates to the technical field of superconducting cables, in particular to a superconducting cable refrigerating system for a superconducting cable.

Background

The superconducting cable refrigeration system is an important component of the superconducting cable system, the normal operation of the superconducting cable refrigeration system is a necessary condition for grid-connected operation of the superconducting cable system, and in order to ensure uniform temperature of the cable, liquid nitrogen is generally adopted as a refrigerant to continuously cool the cable. The present inventors found that the existing superconducting cable refrigeration system at least has the following technical problems:

firstly, when the refrigerator has a fault, the superconducting cable must be cut off;

secondly, the problem that the liquid nitrogen is evaporated into nitrogen gas in the heat exchange process of the circulating liquid nitrogen is not considered;

the circulating liquid nitrogen reflowing from the superconducting cable has insufficient heat exchange in the refrigerating system and poor refrigerating effect;

fourthly, the liquid nitrogen in the liquid nitrogen Dewar and the liquid nitrogen circulating pipeline cannot be supplemented in time when the amount of the liquid nitrogen is low;

the safe, reliable and stable operation of the superconducting cable can be influenced by the technical problems.

Disclosure of Invention

The invention aims to provide a superconducting cable refrigerating system which is applied to a superconducting cable system to improve the power supply reliability of grid-connected operation of the superconducting cable system.

Therefore, the embodiment of the invention provides a superconducting cable refrigeration system, which is applied to the cooling of a superconducting cable and comprises a measurement and control module, a refrigeration main module, a liquid nitrogen circulating pipeline, a refrigeration standby module and a sensing module;

the liquid nitrogen circulation pipeline comprises a liquid nitrogen outlet and a liquid nitrogen inlet, the liquid nitrogen outlet is communicated with an inlet of a liquid nitrogen channel of the superconducting cable, the liquid nitrogen inlet is communicated with an outlet of the liquid nitrogen channel of the superconducting cable, and cooling liquid nitrogen circularly flows in the liquid nitrogen circulation pipeline;

the refrigeration main module is used for cooling the cooling liquid nitrogen circulating and flowing in the liquid nitrogen circulating pipeline in a first refrigeration mode;

the sensing module is at least used for detecting the state information of the refrigeration main module in real time and sending the state information of the refrigeration main module to the measurement and control module;

the measurement and control module is at least used for receiving the state information of the main refrigeration module, judging whether the main refrigeration module has a fault according to the state information of the main refrigeration module, controlling the main refrigeration module to stop working when the main refrigeration module has the fault, and controlling the standby refrigeration module to cool the cooling liquid nitrogen circulating and flowing in the liquid nitrogen circulating pipeline in a second refrigeration mode.

Optionally, the refrigeration main module comprises a refrigeration unit, a supercooled liquid nitrogen dewar and a circulating liquid nitrogen heat exchanger; supercooled liquid nitrogen is stored in the supercooled liquid nitrogen dewar, and the circulating liquid nitrogen heat exchanger is arranged in the supercooled liquid nitrogen dewar; the refrigerating unit is arranged above the super-cooled liquid nitrogen Dewar; the refrigerating unit is used for refrigerating the supercooled liquid nitrogen in the supercooled liquid nitrogen Dewar and maintaining the supercooled liquid nitrogen in the supercooled liquid nitrogen Dewar within a target temperature range.

Optionally, the refrigeration main module further comprises a nitrogen reliquefier, and the nitrogen reliquefier is arranged above the supercooled liquid nitrogen dewar and is communicated with the supercooled liquid nitrogen dewar; the refrigerating unit is arranged above the nitrogen reliquefier;

part of supercooled liquid nitrogen in the supercooled liquid nitrogen dewar is evaporated into the nitrogen reliquefier after heat exchange; the refrigerating unit is used for condensing gas entering the nitrogen reliquefier to obtain cooled liquid nitrogen, and the cooled liquid nitrogen obtained by condensation flows back to the supercooled liquid nitrogen dewar under the action of gravity.

Optionally, a first through hole and a second through hole are formed in the top of the super-cooled liquid nitrogen dewar, the first through hole is far away from the circulating liquid nitrogen heat exchanger, and the second through hole is close to the circulating liquid nitrogen heat exchanger; the bottom of the nitrogen reliquefier is provided with a liquid nitrogen backflow through hole, and the right side wall of the nitrogen reliquefier is provided with a nitrogen inlet hole; the liquid nitrogen backflow through hole is communicated with the first through hole and is arranged in an up-and-down corresponding manner with the first through hole; the nitrogen inlet hole is communicated with the second through hole through a pipeline.

Optionally, the refrigeration backup module comprises a vacuum pump, a buffer tank, a regulating valve, and a first air bath vaporizer; one end of the vacuum pump, one end of the buffer tank, one end of the regulating valve and one end of the first air bath type vaporizer are sequentially connected through a pipeline; a third through hole is formed in the side wall of the super-cooling liquid nitrogen Dewar; the other end of the first air bath type vaporizer is communicated with the third through hole through a pipeline;

wherein the vacuum pump is used for providing pumping power to pump away nitrogen in the supercooled liquid nitrogen dewar, reducing the pressure in the supercooled liquid nitrogen dewar and maintaining the supercooled liquid nitrogen in the supercooled liquid nitrogen dewar in a target temperature range; the buffer tank is used for buffering gas in the nitrogen pumping process, the regulating valve is used for regulating the flow of the gas in the pipeline, and the buffer tank and the regulating valve jointly play a role in stabilizing the pumping-out pressure in a target range; the air bath vaporizer is used to heat the low temperature nitrogen to room temperature.

Optionally, the liquid nitrogen circulation pipeline comprises a first pipeline, a second pipeline, a third pipeline and a fourth pipeline; the circulating liquid nitrogen heat exchanger comprises a first heat exchanger and a second heat exchanger;

one end of the first pipeline is arranged as the liquid nitrogen inlet, and the other end of the first pipeline is used for being connected with one end of a first heat exchanger so as to send the backflow liquid nitrogen at the outlet of the superconducting cable liquid nitrogen channel to the first heat exchanger for carrying out first heat exchange cooling on the backflow liquid nitrogen;

one end of the second pipeline is used for being connected with the other end of the first heat exchanger so as to receive the returned liquid nitrogen after the first heat exchange and cooling is carried out by the first heat exchanger, and the other end of the second pipeline is connected with one end of a liquid nitrogen pump;

one end of the third pipeline is connected with the other end of the liquid nitrogen pump, and the other end of the third pipeline is used for being connected with one end of the second heat exchanger, so that the backflow liquid nitrogen subjected to the first heat exchange cooling by the first heat exchanger is sent to the second heat exchanger to be subjected to the second heat exchange cooling of the backflow liquid nitrogen;

one end of the fourth pipeline is arranged as the liquid nitrogen outlet, and the other end of the fourth pipeline is used for being connected with the other end of the second heat exchanger so as to receive the returned liquid nitrogen which is subjected to the second heat exchange cooling through the second heat exchanger and output the liquid nitrogen to the inlet of the liquid nitrogen channel of the superconducting cable.

Optionally, the number of the liquid nitrogen pumps is 2, and the first liquid nitrogen pump and the second liquid nitrogen pump are respectively arranged; the liquid nitrogen circulating pipeline structure also comprises a fifth pipeline, a first three-way valve, a second three-way valve, a third three-way valve and a throttle valve;

the other end of the second pipeline is connected with a first end of a first three-way valve;

the second end of the first three-way valve is connected with one end of the first liquid nitrogen pump, and the other end of the first liquid nitrogen pump is connected with one end of a third pipeline;

the third end of the first three-way valve is connected with one end of the second liquid nitrogen pump, and the other end of the second liquid nitrogen pump is connected with one end of a third pipeline;

the second end of the first three-way valve is connected with one end of the first liquid nitrogen pump through a first stop valve, and the other end of the first liquid nitrogen pump is connected with the first end of the second three-way valve through a second stop valve;

the third end of the first three-way valve is connected with one end of the second liquid nitrogen pump through a second stop valve, and the other end of the second liquid nitrogen pump is connected with the third end of the second three-way valve through a fourth stop valve;

and the first end of the third three-way valve is connected with the second end of the second three-way valve, the second end of the third three-way valve is connected with one end of the third pipeline, the third end of the third three-way valve is connected with one end of the fifth pipeline through the throttle valve, and the other end of the fifth pipeline is led into the supercooled liquid nitrogen dewar.

Optionally, a fifth stop valve and a first exhaust valve are arranged on the first pipeline, a second exhaust valve and a first safety valve are arranged on the second pipeline, a third exhaust valve and a second safety valve are arranged on the third pipeline, and a sixth stop valve, a fourth exhaust valve and a bypass valve are arranged on the fourth pipeline; a fifth exhaust valve and a third safety valve are arranged on the buffer tank; and a sixth exhaust valve and a fourth safety valve are arranged at the inlet pipeline of the first air bath type vaporizer.

Optionally, the superconducting cable refrigeration system further comprises a liquid nitrogen supplementing device; the liquid nitrogen supplementing device comprises a liquid nitrogen storage tank and a second air bath type vaporizer, a seventh exhaust valve, a fifth safety valve, a liquid injection valve and a one-way valve are arranged on the liquid nitrogen storage tank, and supercooled liquid nitrogen is stored in the liquid nitrogen storage tank; the top of one side wall of the liquid nitrogen storage tank is provided with a first opening, the bottom of the side wall of the liquid nitrogen storage tank is provided with a second opening, and the middle of the other side wall of the liquid nitrogen storage tank is provided with a third opening;

the output end of the second air bath type vaporizer is communicated with the first opening through a pipeline, and the input end of the second air bath type vaporizer is communicated with the second opening through a pipeline and a seventh stop valve; the third opening is connected with the third pipeline through a pipeline and a transfusion valve;

the measurement and control device is specifically used for controlling the second air bath type vaporizer to heat the liquid nitrogen entering the second air bath type vaporizer from the second opening hole into nitrogen gas, and sending the nitrogen gas into the liquid nitrogen storage tank through the first opening hole, so that the pressure of the nitrogen gas is used as liquid feeding power.

Optionally, the sensor module comprises a temperature sensor, a liquid level meter and a first pressure sensor disposed in the subcooled liquid nitrogen dewar and a flow meter disposed on the fourth pipeline;

the temperature sensor is used for detecting the liquid nitrogen temperature parameter in the supercooled liquid nitrogen Dewar in real time; the liquid level meter is used for detecting liquid nitrogen liquid level parameters in the supercooled liquid nitrogen dewar in real time; the first pressure sensor is used for detecting liquid nitrogen pressure parameters in the supercooled liquid nitrogen dewar in real time; the liquid nitrogen state parameters in the supercooled liquid nitrogen Dewar comprise the liquid nitrogen temperature parameter, the liquid nitrogen liquid level parameter and the liquid nitrogen pressure parameter; the flowmeter is used for detecting a liquid nitrogen flow signal on the fourth pipeline in real time and sending the liquid nitrogen flow signal to the measurement and control device;

the measurement and control module is used for judging whether the refrigerating unit is in fault or not according to a comparison result of the liquid nitrogen temperature parameter and a preset temperature threshold value, a comparison result of the liquid nitrogen liquid level parameter and a preset liquid level threshold value and a comparison result of the liquid nitrogen pressure parameter and a preset pressure threshold value;

the measurement and control device is used for judging whether the flow of liquid nitrogen in the cooling circulation pipeline is low or not according to the liquid nitrogen flow signal, if so, the seventh stop valve and the infusion valve are controlled to be switched to the corresponding position states, the second air bath type vaporizer is started to provide liquid feeding power, and the supercooled liquid nitrogen in the liquid nitrogen storage tank is fed into the cooling circulation pipeline to supplement the liquid nitrogen;

the measurement and control device is used for judging whether the liquid nitrogen liquid level in the supercooled liquid nitrogen Dewar is low according to the liquid nitrogen liquid level signal, if so, the throttle valve, the seventh stop valve and the infusion valve are switched to corresponding position states, the second air bath type vaporizer is started to provide liquid conveying power, the supercooled liquid nitrogen in the liquid nitrogen storage tank is conveyed to the cooling circulation pipeline, and the supplemented supercooled liquid nitrogen finally passes through the throttle valve and the fifth pipeline and enters the supercooled liquid nitrogen Dewar to supplement the liquid nitrogen.

The embodiment of the invention at least has the following advantages:

the superconducting cable refrigeration system comprises a measurement and control module, a refrigeration main module, a liquid nitrogen circulating pipeline, a refrigeration standby module and a sensing module; the sensing module detects the running state parameters of the refrigeration main module in real time, the measurement and control module judges whether the refrigeration main module fails or not in response to receiving the running state parameters of the refrigeration main module sent by the sensing module, if the refrigeration main module fails, an instruction is sent to control the refrigeration main module to stop and control the refrigeration standby module to start, and when a refrigeration unit fails, a superconducting cable does not need to be cut off immediately, so that the power supply reliability of the superconducting cable system in grid-connected operation is improved.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic view of a main structure of a superconducting cable refrigeration system according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a superconducting cable refrigeration system according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a main cooling module according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of a refrigeration backup module according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing a specific structure of a liquid nitrogen circulation pipeline in an embodiment of the present invention.

FIG. 6 is a schematic structural diagram of a liquid nitrogen supplementing device according to an embodiment of the present invention.

The labels in the figure are:

1-a measurement and control module;

2-refrigeration main module, 21-refrigeration unit, 22-super-cooled liquid nitrogen Dewar, 23-nitrogen reliquefier, 24-first heat exchanger, 25-second heat exchanger;

3-refrigeration standby module, 31-vacuum pump, 32-buffer tank, 33-regulating valve, 34-first air bath type vaporizer;

4-liquid nitrogen circulating pipeline, 41-liquid nitrogen inlet, 42-liquid nitrogen outlet, 43-first liquid nitrogen pump, 44-second liquid nitrogen pump;

5-a sensing module, 51-a liquid level meter;

61-a first conduit, 62-a second conduit, 63-a third conduit, 64-a fourth conduit, 65-a fifth conduit;

71-a first stop valve, 72-a second stop valve, 73-a third stop valve, 74-a fourth stop valve, 75-a fifth stop valve, 76-a sixth stop valve, 77-a seventh stop valve, 78-an eighth stop valve;

81-a first exhaust valve, 82-a second exhaust valve, 83-a third exhaust valve, 84-a fourth exhaust valve, 85-a fifth exhaust valve, 86-a sixth exhaust valve, 87-a seventh exhaust valve;

91-a first three-way valve, 92-a second three-way valve, 93-a third three-way valve;

101-first relief valve, 102-second relief valve, 103-third relief valve, 104-fourth relief valve, 105-fifth relief valve;

11-a liquid nitrogen supplementing device, 111-a liquid nitrogen storage tank, 112-a second air bath type vaporizer;

121-throttling valve, 122-liquid injection valve, 123-one-way valve, 124-transfusion valve and 125-bypass valve.

Detailed Description

Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

In addition, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some instances, well known means have not been described in detail so as not to obscure the present invention.

Referring to fig. 1 to 2, an embodiment of the invention provides a superconducting cable refrigeration system, which is applied to cooling a superconducting cable and includes a measurement and control module 1, a refrigeration main module 2, a liquid nitrogen circulation pipeline 4, a refrigeration standby module 3, and a sensing module 5; it should be noted that fig. 2 is a simplified structural diagram, and fig. 2 shows a simplified structural form of the pipeline, and a part of the pipeline is represented by a straight line.

Wherein the liquid nitrogen circulation pipe 4 comprises a liquid nitrogen outlet 42 and a liquid nitrogen inlet 41, the liquid nitrogen outlet 42 is used for communicating with an inlet of a liquid nitrogen channel of the superconducting cable, the liquid nitrogen inlet 41 is used for communicating with an outlet of the liquid nitrogen channel of the superconducting cable, and cooling liquid nitrogen circularly flows in the liquid nitrogen circulation pipe 4; it is understood that the present embodiment can be applied to various types of superconducting cables; any type of superconducting cable is provided with a liquid nitrogen channel, cooling liquid nitrogen of the liquid nitrogen cooling circulation system flows out through the liquid nitrogen outlet 42 and is sent to the inlet of the liquid nitrogen channel of the superconducting cable, and the liquid nitrogen flowing through the liquid nitrogen channel of the superconducting cable needs to flow back to the refrigerating system for re-cooling, namely flows out of the outlet of the liquid nitrogen channel of the superconducting cable and then flows back to the liquid nitrogen inlet 41 through a pipeline.

The refrigeration main module 2 is configured to cool the cooling liquid nitrogen circulating in the liquid nitrogen circulation pipeline 4 by using a first refrigeration method;

the sensing module 5 is at least used for detecting the state information of the refrigeration main module 2 in real time and sending the state information of the refrigeration main module 2 to the measurement and control module 1;

the measurement and control module 1 is at least used for receiving the state information of the main refrigeration module 2, judging whether the main refrigeration module 2 fails according to the state information of the main refrigeration module 2, controlling the main refrigeration module 2 to stop working when the main refrigeration module 2 fails, and controlling the backup refrigeration module 3 to cool the cooling liquid nitrogen circulating in the liquid nitrogen circulating pipeline 4 in a second refrigeration mode.

In the system of the embodiment, the sensing module 5 detects the running state parameters of the main refrigeration module 2 in real time, the measurement and control module 1 judges whether the main refrigeration module 2 fails or not in response to receiving the running state parameters of the main refrigeration module 2 sent by the sensing module 5, if the main refrigeration module 2 fails, the measurement and control module 1 sends an instruction to control the main refrigeration module 2 to stop and control the standby refrigeration module 3 to start, and when the refrigeration unit 21 fails, the superconducting cable does not need to be cut off immediately, so that the power supply reliability of the superconducting cable system in grid-connected operation is improved. The removal of the superconducting cable means that the protection device acts to disconnect the circuit breaker.

Illustratively, referring to fig. 3, the refrigeration main module 2 includes a refrigeration unit 21, a subcooled liquid nitrogen dewar 22 and a circulating liquid nitrogen heat exchanger; supercooled liquid nitrogen is stored in the supercooled liquid nitrogen dewar 22, and the circulating liquid nitrogen heat exchanger is arranged in the supercooled liquid nitrogen dewar 22; the refrigerating unit 21 is arranged above the supercooled liquid nitrogen dewar 22; the refrigerating unit 21 is configured to refrigerate the supercooled liquid nitrogen in the supercooled liquid nitrogen dewar 22, and maintain the supercooled liquid nitrogen in the supercooled liquid nitrogen dewar 22 within a target temperature range.

Preferably, the refrigerating unit 21 is composed of 12 AL600 refrigerating units 211.

Specifically, the refrigeration main module 2 further includes a nitrogen reliquefier 23, and the nitrogen reliquefier 23 is disposed above the supercooled liquid nitrogen dewar 22 and is communicated with the supercooled liquid nitrogen dewar 22; the refrigeration unit 21 is disposed above the nitrogen reliquefier 23; specifically, the nitrogen reliquefier 23 is a housing having a receiving cavity therein;

part of the subcooled liquid nitrogen in the subcooled liquid nitrogen Dewar 22 is subjected to heat exchange and then evaporated into the nitrogen reliquefier 23; the refrigerating unit 21 is configured to condense the gas entering the nitrogen reliquefier 23 to obtain cooled liquid nitrogen, and the condensed cooled liquid nitrogen flows back to the supercooled liquid nitrogen dewar 22 under the action of gravity.

Specifically, the refrigeration unit 21 is disposed above the nitrogen reliquefier 23; the cold air of the refrigeration unit 21 is input into the accommodating cavity of the nitrogen reliquefier 23, and the nitrogen reliquefier 23 is communicated with the supercooled liquid nitrogen dewar 22, so that the cold air can reenter the supercooled liquid nitrogen dewar 22 through the nitrogen reliquefier 23 to cool the liquid nitrogen in the supercooled liquid nitrogen dewar 22, thereby maintaining the liquid nitrogen in the supercooled liquid nitrogen dewar 22 in a target temperature range.

Illustratively, the top of the subcooled liquid nitrogen dewar 22 is provided with a first through hole and a second through hole, the first through hole is arranged far away from the circulating liquid nitrogen heat exchanger, and the second through hole is arranged close to the circulating liquid nitrogen heat exchanger, so that nitrogen gas enters the cavity of the nitrogen reliquefier 23 through the second through hole; the bottom of the nitrogen reliquefier 23 is provided with a liquid nitrogen backflow through hole so that condensed liquid nitrogen flows into the supercooled liquid nitrogen Dewar 22 under the action of gravity, and the right side wall of the nitrogen reliquefier is provided with a nitrogen inlet hole; the liquid nitrogen backflow through hole is communicated with the first through hole, and the liquid nitrogen backflow through hole and the first through hole are arranged in an up-and-down corresponding mode; the nitrogen inlet hole is communicated with the second through hole through a pipeline.

Preferably, the liquid nitrogen backflow through hole and the first through hole are both circular holes, and the diameters of the liquid nitrogen backflow through hole and the first through hole are the same; the nitrogen inlet hole and the second through hole are circular holes, and the diameters of the nitrogen inlet hole and the second through hole are the same; the aperture of the second through hole is smaller than the aperture of the first through hole.

It should be noted that, in this embodiment, the problem of liquid nitrogen heat exchange evaporation occurring in the liquid nitrogen circulation heat exchange process is considered, the nitrogen reliquefier 23 is designed to condense and liquefy evaporated nitrogen, and the condensed and liquefied liquid nitrogen returns to the supercooled liquid nitrogen dewar 22 again for recycling, so that the refrigeration effect of the refrigeration device is improved, the temperature uniformity of the cable can be ensured, and the power supply reliability of the superconducting cable system in grid-connected operation is improved. Exemplarily, referring to fig. 4, the refrigeration backup module 3 includes a vacuum pump 31, a buffer tank 32, a regulating valve 33, a first air bath vaporizer 34; one end of the vacuum pump 31, the buffer tank 32, the regulating valve 33 and one end of the first air bath type vaporizer 34 are sequentially connected through a pipeline; a third through hole is formed in the side wall of the super-cooling liquid nitrogen Dewar 22; the other end of the first air bath type vaporizer 34 is communicated with the third through hole through a pipeline;

wherein the vacuum pump 31 is used for providing a pumping power to pump away nitrogen in the subcooled liquid nitrogen dewar 22, reducing the pressure in the subcooled liquid nitrogen dewar 22, and maintaining the subcooled liquid nitrogen in the subcooled liquid nitrogen dewar 22 in a target temperature range; the nitrogen gas entering the buffer tank 32 can play a role of gas buffering in the nitrogen gas pumping process, the regulating valve 33 is used for the gas flow in the pipeline, therefore, the buffer tank 32 and the regulating valve 33 play a role of stabilizing the pumping pressure in a target range; the air bath vaporizer is used to heat the low temperature nitrogen to room temperature. Since the low-temperature environment may damage the vacuum pump 31, the low-temperature nitrogen gas is heated to room temperature and then introduced into the vacuum pump 31, and it can be understood that the other end of the vacuum pump 31 discharges the nitrogen gas.

Exemplarily, referring to fig. 5, the liquid nitrogen circulation pipe 4 includes a first pipe 61, a second pipe 62, a third pipe 63, and a fourth pipe 64; the circulating liquid nitrogen heat exchanger comprises a first heat exchanger 24 and a second heat exchanger 25;

wherein, one end of the first pipeline 61 is set as the liquid nitrogen inlet 41, i.e. the inlet of the returned liquid nitrogen flowing back from the superconducting cable, and the other end is used for connecting one end of the first heat exchanger 24, so as to send the returned liquid nitrogen at the outlet of the liquid nitrogen channel of the superconducting cable to the first heat exchanger 24 for the first heat exchange cooling of the returned liquid nitrogen;

one end of the second pipeline 62 is used for connecting the other end of the first heat exchanger 24 to receive the returned liquid nitrogen after the first heat exchange cooling is performed by the first heat exchanger 24, and the other end of the second pipeline 62 is connected with one end of a liquid nitrogen pump;

one end of the third pipeline 63 is connected to the other end of the liquid nitrogen pump, and the other end of the third pipeline 63 is used for being connected to one end of the second heat exchanger 25, so that the returned liquid nitrogen subjected to the first heat exchange cooling by the first heat exchanger 24 is sent to the second heat exchanger 25 to be subjected to the second heat exchange cooling of the returned liquid nitrogen;

one end of the fourth pipeline 64 is set as the liquid nitrogen outlet 42, and the other end is used for connecting the other end of the second heat exchanger 25, so as to receive the returned liquid nitrogen after the second heat exchange cooling is performed by the second heat exchanger 25, and output the returned liquid nitrogen to the inlet of the superconducting cable liquid nitrogen channel.

Exemplarily, the number of the liquid nitrogen pumps is 2, and the first liquid nitrogen pump 43 and the second liquid nitrogen pump 44 are respectively provided; the liquid nitrogen circulating pipeline 4 structure further comprises a fifth pipeline 65, a first three-way valve 91, a second three-way valve 92, a third three-way valve 93 and a throttle valve 121;

wherein the other end of the second pipe 62 is connected to a first end of the first three-way valve 91;

wherein, the second end of the first three-way valve 91 is connected with one end of the first liquid nitrogen pump 43, and the other end of the first liquid nitrogen pump 43 is connected with one end of the third pipeline 63;

a third end of the first three-way valve 91 is connected with one end of the second liquid nitrogen pump 44, and the other end of the second liquid nitrogen pump 44 is connected with one end of a third pipeline 63;

wherein, the second end of the first three-way valve 91 is connected to one end of the first liquid nitrogen pump 43 through a first stop valve 71, and the other end of the first liquid nitrogen pump 43 is connected to the first end of a second three-way valve 92 through a second stop valve 72;

wherein, the third end of the first three-way valve 91 is connected with one end of the second liquid nitrogen pump 44 through a second stop valve 72, and the other end of the second liquid nitrogen pump 44 is connected with the third end of the second three-way valve 92 through a fourth stop valve 74;

wherein a first end of the third three-way valve 93 is connected to a second end of the second three-way valve 92, a second end of the third three-way valve 93 is connected to one end of the third pipeline 63, a third end of the third three-way valve 93 is connected to one end of the fifth pipeline 65 through the throttle valve 121, and the other end of the fifth pipeline 65 is led to the subcooled liquid nitrogen dewar 22.

Specifically, in the present embodiment, different liquid nitrogen passages can be formed by switching the valve states of the first three-way valve 91 and the second three-way valve 92; the first liquid nitrogen pump 43 and the second liquid nitrogen pump 44 are mutually standby, and can be started simultaneously or independently, and when the first liquid nitrogen pump and the second liquid nitrogen pump are started independently, the first three-way valve 91 and the second three-way valve 92 are controlled to be switched to corresponding states, and a pipeline corresponding to the independently started liquid nitrogen pump is connected; the technical problem that when the pumping capacity of a single liquid nitrogen pump is insufficient or the circulation liquid nitrogen flow rate is reduced due to faults, a good cooling effect cannot be achieved can be solved. Illustratively, a fifth stop valve 75 and a first exhaust valve 81 are provided on the first pipe 61, a second exhaust valve 82 and a first relief valve 101 are provided on the second pipe 62, a third exhaust valve 83 and a second relief valve 102 are provided on the third pipe 63, and a sixth stop valve 76, a fourth exhaust valve 84, and a bypass valve 125 are provided on the fourth pipe 64; a fifth exhaust valve 85 and a third safety valve 103 are arranged on the buffer tank 32; a sixth vent valve 86 and a fourth relief valve 104 are provided at the inlet conduit of the first air bath vaporizer 34. Illustratively, the superconducting cable refrigeration system further comprises a liquid nitrogen supplementing device 11; referring to fig. 6, the liquid nitrogen supplementing device 11 includes a liquid nitrogen storage tank 111 and a second air-bath vaporizer 112, the liquid nitrogen storage tank 111 is provided with a seventh vent valve 87, a fifth safety valve 105, a liquid injection valve 122 and a one-way valve 123, and the supercooled liquid nitrogen is stored in the liquid nitrogen storage tank 111; a first opening is formed in the top of one side wall of the liquid nitrogen storage tank 111, a second opening is formed in the bottom of the liquid nitrogen storage tank, and a third opening is formed in the middle of the other side wall of the liquid nitrogen storage tank 111; the liquid nitrogen storage tank 111 is also provided with a liquid injection valve 122 and a one-way valve 123; the liquid injection valve 122 is connected to the check valve 123, and the liquid injection valve 122 is opened when liquid nitrogen is injected into the liquid nitrogen storage tank 111.

The output end of the second air bath vaporizer 112 is communicated with the first opening through a pipeline, and the input end is communicated with the second opening through a pipeline and a seventh stop valve 77; the third opening is connected with the third pipeline 63 through a pipeline and an infusion valve 124;

wherein an eighth stop valve 78 is arranged between the first pipe 61 and the fourth pipe 64;

specifically, the first, second, third, fourth, fifth, sixth, seventh, and eighth cut-off valves 71, 72, 73, 74, 75, 76, 77, 78 function to cut, regulate, and throttle the pipe corresponding to different pipe positions;

the first safety valve 101, the second safety valve 102, the third safety valve 103, the fourth safety valve 104 and the fifth safety valve 105 are used for releasing pressure when the pressure is too large, so that the safety reliability of the refrigeration system is improved;

the first exhaust valve 81, the second exhaust valve 82, the third exhaust valve 83, the fourth exhaust valve 84, the fifth exhaust valve 85, the sixth exhaust valve 86 and the seventh exhaust valve 87 are used for exhausting and blowing off impurities in the cooling circulation pipeline and pre-cooling the cooling circulation pipeline before filling cooling liquid nitrogen into the system pipeline, wherein the pre-cooling refers to filling cooling liquid nitrogen into the cooling circulation pipeline for pre-cooling until the temperature of the liquid nitrogen in the pipeline reaches a target temperature range.

The measurement and control device is specifically configured to control the second air bath vaporizer 112 to heat the liquid nitrogen entering the second air bath vaporizer 112 from the second opening into nitrogen gas, and send the nitrogen gas into the liquid nitrogen storage tank 111 through the first opening, so as to use the pressure of the nitrogen gas as a liquid feeding power.

Specifically, when liquid nitrogen replenishment is required, the control device controls the seventh stop valve 77 and the infusion valve 124 to switch to the corresponding state positions, liquid nitrogen enters the second air bath vaporizer 112 through the second opening and the seventh stop valve 77, the second air bath vaporizer 112 heats the liquid nitrogen entering the second air bath vaporizer 112 from the second opening into nitrogen gas, and sends the nitrogen gas into the liquid nitrogen storage tank 111 through the first opening, and at this time, the pressure in the liquid nitrogen storage tank 111 increases to send the liquid nitrogen in the liquid nitrogen storage tank 111 into the cooling circulation pipeline through a pipeline and the infusion valve 124 by using the nitrogen gas pressure as a liquid sending power; and after the liquid nitrogen is supplemented, the control device controls the seventh stop valve 77 and the infusion valve 124 to be switched to the corresponding other state position, and the liquid nitrogen supplementation is stopped.

Illustratively, the sensor module includes a temperature sensor, a level gauge 51 and a first pressure sensor provided in the subcooled liquid nitrogen dewar 22, a flow meter provided on the fourth pipe 64, a second pressure sensor provided at the inlet of the vacuum pump 31 and a third pressure sensor provided at the inlet of the first air bath vaporizer 34; a bypass valve 125 is arranged at the flowmeter, and the bypass valve 125 is used for balancing the hydraulic pressure at the corresponding pipeline flowmeter;

the temperature sensor is used for detecting the liquid nitrogen temperature parameter in the supercooled liquid nitrogen Dewar 22 in real time; the liquid level meter 51 is used for detecting liquid nitrogen liquid level parameters in the supercooled liquid nitrogen dewar 22 in real time; the first pressure sensor is used for detecting the liquid nitrogen pressure parameter in the supercooled liquid nitrogen Dewar 22 in real time; the liquid nitrogen state parameters in the supercooled liquid nitrogen Dewar 22 comprise the liquid nitrogen temperature parameter, the liquid nitrogen liquid level parameter and the liquid nitrogen pressure parameter; the flowmeter is used for detecting a liquid nitrogen flow signal on the fourth pipeline 64 in real time and sending the liquid nitrogen flow signal to the measurement and control device; the second pressure sensor is used for detecting a first pressure value of a pipeline between the vacuum pump 31 and the buffer tank 32 in real time and sending the first pressure value to the measurement and control module 1; and the third pressure sensor is used for detecting a second pressure value at the inlet of the air bath type vaporizer in real time and sending the second pressure value to the measurement and control module 1.

The measurement and control module 1 is used for judging whether the refrigerating unit 21 is in fault according to a comparison result of the liquid nitrogen temperature parameter and a preset temperature threshold value, a comparison result of the liquid nitrogen liquid level parameter and a preset liquid level threshold value, and a comparison result of the liquid nitrogen pressure parameter and a preset pressure threshold value;

the measurement and control device is used for judging whether the flow of liquid nitrogen in the cooling circulation pipeline is low or not according to the liquid nitrogen flow signal, if so, the seventh stop valve 77 and the infusion valve 124 are controlled to be switched to the corresponding position state, the second air bath type vaporizer 112 is started to provide liquid feeding power, and the supercooled liquid nitrogen in the liquid nitrogen storage tank 111 is fed into the cooling circulation pipeline to supplement the liquid nitrogen;

the measurement and control device is used for judging whether the liquid nitrogen liquid level in the supercooled liquid nitrogen dewar 22 is low or not according to the liquid nitrogen liquid level signal, if so, the throttle valve 121, the seventh stop valve 77 and the infusion valve 124 are controlled to be switched to the corresponding position state, the second air bath type vaporizer 112 is started to provide liquid conveying power, the supercooled liquid nitrogen in the liquid nitrogen storage tank 111 is conveyed to the cooling circulation pipeline, and the supplemented supercooled liquid nitrogen finally enters the supercooled liquid nitrogen dewar 22 through the throttle valve 121 and the fifth pipeline 65 to supplement the liquid nitrogen.

The measurement and control module 1 is used for responding to the received first pressure value and the second pressure value, judging whether the refrigeration spare module 3 fails according to a comparison result of the first pressure value and a first pressure threshold value, a comparison result of the second pressure value and a second pressure threshold value, and a comparison result of a difference value of the first pressure value and the second pressure value and a preset difference value, if the refrigeration spare module 3 fails, controlling the refrigeration spare module 3 to stop, and sending a cutting instruction to a protection device of the superconducting cable to control the protection device to start protection cutting of the superconducting cable.

Specifically, when any one of the liquid nitrogen temperature parameter is greater than a preset temperature threshold, the liquid nitrogen liquid level parameter is greater than a preset liquid level threshold, or the liquid nitrogen pressure parameter is greater than a preset pressure threshold is true, the fault of the refrigerating unit 21 is determined, and the state of the refrigerating unit 21 is monitored from multiple aspects; and when any one of the first pressure value is greater than a first pressure threshold value, the second pressure value is greater than a second pressure threshold value, and the difference value between the first pressure value and the second pressure value is greater than a preset difference value, judging that the refrigeration standby module 3 has a fault.

Specifically, the system of the embodiment can monitor the state information of each key position in the whole liquid nitrogen cooling circulation system in real time through the corresponding sensor; the control device is used for controlling the position states of the valves such as the first stop valve 71, the second stop valve 72, the third stop valve 73, the fourth stop valve 74, the fifth stop valve 75, the sixth stop valve 76, the seventh stop valve 77, the first three-way valve 91, the second three-way valve 92, the third three-way valve 93, the first exhaust valve 81, the second exhaust valve 82, the third exhaust valve 83, the fourth exhaust valve 84, the fifth exhaust valve 85, the sixth exhaust valve 86, the seventh exhaust valve 87, the throttle valve 121, the infusion valve 124, the bypass valve 125, the injection valve 122 and the like, and the start/close states of the refrigeration equipment, the liquid nitrogen supplementing device 11, the first liquid nitrogen pump 43 and the second liquid nitrogen pump 44 according to a preset control strategy and the state information to adjust the flow rate and the flow direction of liquid nitrogen in the circulating pipeline and control the refrigeration of the liquid nitrogen.

The preset control strategy is designed according to the cooling requirement of the superconducting cable, so that the temperature, the flow speed and the flow of the circulating liquid nitrogen in the circulating pipeline meet the target requirement, the preset control strategy is specifically related to the cooling requirement of the superconducting cable, and the cooling requirement of the superconducting cable is related to the structure and the length of the superconducting cable.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.