Heat leakage monitoring system and method for high-temperature superconducting cable refrigeration system

Abstract

The present invention provides a heat leakage monitoring system and method for a high-temperature superconducting cable refrigeration system, comprising: a measuring optical fiber installed in the high-temperature superconducting cable refrigeration system for collecting temperature signals; an optical fiber sensing device connected to the measuring optical fiber for acquiring the temperature signals; and heat leakage monitoring of the high-temperature superconducting cable refrigeration system based on the temperature signals. Compared to existing technologies, the present invention utilizes a measuring optical fiber embedded in the high-temperature superconducting cable refrigeration system, combined with distributed optical fiber sensing technology based on Raman scattering principles, to monitor heat leakage in the high-temperature superconducting cable refrigeration system in real time, thereby enabling rapid and effective protection of the high-temperature superconducting cable.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting cables, and in particular to a heat leakage monitoring system and method for a high-temperature superconducting cable refrigeration system. Background Art

[0002] Compared to traditional power cables, superconducting cable systems offer advantages such as low loss, high transmission capacity, compact cable size, and enhanced system safety and stability. Cold-insulated high-temperature superconducting cables have minimal electromagnetic and thermal interference, and offer stable current-carrying capacity. These cables hold great promise for underground cable systems in densely populated metropolitan areas or for specific high-capacity power transmission applications. A high-temperature superconducting cable system typically consists of a superconducting cable, a cryogenic refrigeration system, and a monitoring and protection system. The cryogenic refrigeration system is crucial for ensuring the proper operation of the superconducting cable, and its reliability directly impacts its safety.

[0003] Currently, superconducting cable refrigeration systems mostly utilize liquid nitrogen forced-flow cooling. The basic principle is to use liquid nitrogen to draw heat generated by the high-temperature superconducting cable into a refrigerator, where it is then cooled and returned to the cable, forming a closed liquid nitrogen circulation loop. Due to the structural characteristics of superconducting cables and their refrigeration systems, they have multiple sources of heat load, or heat leakage. These include AC losses in the superconducting cable itself, losses in superconducting cable joints, heat leakage from the superconducting cable thermostat, and heat leakage from the superconducting cable terminal thermostat system. If excessive heat leakage occurs in a particular part of the superconducting cable system, such as loss in a superconducting cable joint, the refrigeration system will be unable to promptly remove this heat, leading to the risk of a superconducting cable quench, seriously impacting the cable's current-carrying capacity and, consequently, its operational safety. Furthermore, the heat load sources in superconducting cable systems are relatively dispersed, existing in nearly every part of the system. Therefore, existing technologies are unable to effectively monitor heat leakage in high-temperature superconducting cables.

[0004] Patent document CN109855759B discloses a high-temperature superconducting cable temperature measurement system for use in interconnected high-temperature superconducting cables and terminal cooling systems. The system includes a low-temperature temperature measurement optical fiber installed in the high-temperature superconducting cable and a thermal resistor installed in the terminal cooling system; an optical fiber temperature measurement host for receiving temperature measurement information from each measurement point of the low-temperature temperature measurement optical fiber; a thermal resistor temperature monitor for receiving temperature information from the thermal resistor; and a temperature measurement control device that receives the temperature measurement and temperature information, evaluates and determines the protection action and protection zone of the connected cable operation control host based on the temperature measurement and temperature information, and controls the cable operation control host to perform corresponding operations. However, this method does not achieve real-time monitoring of heat leakage in the high-temperature superconducting cable cooling system, thereby providing rapid and effective protection for the high-temperature superconducting cable. Summary of the Invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a heat leakage monitoring system and method for a high-temperature superconducting cable refrigeration system.

[0006] According to the present invention, a heat leakage monitoring system for a high-temperature superconducting cable refrigeration system is provided, comprising:

[0007] The measuring optical fiber is set in the high-temperature superconducting cable cooling system to collect temperature signals;

[0008] An optical fiber sensing device connected to the measuring optical fiber for obtaining a temperature signal;

[0009] Heat leakage monitoring of high-temperature superconducting cable refrigeration system is carried out through temperature signals.

[0010] Preferably, the measuring optical fiber is laid in a high-temperature superconducting cable refrigeration system.

[0011] Preferably, the high-temperature superconducting cable refrigeration system includes a superconducting cable body;

[0012] The measuring optical fiber is spirally wound on the superconducting cable body and fixed with epoxy resin glue.

[0013] Preferably, the high-temperature superconducting cable refrigeration system further includes a liquid nitrogen circulation pipeline:

[0014] The measuring optical fiber is attached to the inner wall of the liquid nitrogen flow pipe and fixed with epoxy resin glue.

[0015] Preferably, the high-temperature superconducting cable refrigeration system further includes a refrigerator;

[0016] The measuring optical fiber extends from the refrigerator and is connected to the optical fiber sensing device.

[0017] According to the present invention, a method for monitoring heat leakage of a high-temperature superconducting cable refrigeration system includes: measuring optical fiber, and optical fiber sensing equipment;

[0018] Step 1: Collect the temperature signal of the high-temperature superconducting cable cooling system through the measuring optical fiber;

[0019] Step 2: Use the temperature signal obtained by the optical fiber sensing device to monitor the heat leakage of the high-temperature superconducting cable refrigeration system.

[0020] Preferably, step 2 includes:

[0021] Step 201: Acquire an anti-Stokes light signal from a temperature signal;

[0022] Step 202: Perform heat leakage monitoring on the high-temperature superconducting cable refrigeration system through anti-Stokes optical signals.

[0023] Preferably, the method further comprises:

[0024] Step 3: Adjust the time resolution of the fiber optic sensing device to optimize the rate of heat leakage monitoring.

[0025] Preferably, the temperature signal includes an anti-Stokes optical signal and a Stokes optical signal.

[0026] Preferably, it includes:

[0027] Step 4: Send the temperature signal to the display device for display.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention ensures the safety of the high-temperature superconducting cable by performing heat leakage monitoring on the refrigeration system of the high-temperature superconducting cable.

[0030] 2. The present invention measures the temperature signals of various parts of the high-temperature superconducting cable refrigeration system by laying the measuring optical fiber in the high-temperature superconducting cable refrigeration system, thereby realizing heat leakage monitoring and ensuring the safe operation of the high-temperature superconducting cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0032] Figure 1 It is a structural schematic diagram of the present invention;

[0033] Figure 2 This is a schematic diagram of the installation of the measuring optical fiber of the high-temperature superconducting cable body of the present invention;

[0034] Figure 3 This is a schematic diagram of the installation of optical fiber for measuring the liquid nitrogen flow pipeline of the present invention;

[0035] Figure 4 Schematic diagram of the time resolution versus quench response speed of the present invention.

[0036] Reference numerals:

[0037] 1-High temperature superconducting cable body;

[0038] 2-Superconducting cable terminal;

[0039] 3-Liquid nitrogen storage tank;

[0040] 4-Liquid nitrogen valve;

[0041] 5-Refrigerator;

[0042] 6-Liquid nitrogen buffer tank;

[0043] 7-Compressor;

[0044] 8-Measurement fiber;

[0045] 9-Fiber optic sensing equipment;

[0046] 10-Display device;

[0047] 11-liquid nitrogen circulation pipeline wall;

[0048] 12-Epoxy resin glue. DETAILED DESCRIPTION

[0049] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0050] Figure 1 It is a structural diagram of the present invention, as shown in FIG. Figure 1 As shown, the present invention provides a heat leakage monitoring system for a high-temperature superconducting cable refrigeration system, comprising: a high-temperature superconducting cable body 1, a superconducting cable terminal 2, a liquid nitrogen storage tank 3, a liquid nitrogen valve 4, a refrigerator 5, a liquid nitrogen buffer tank 6, a compressor 7, a measuring optical fiber 8, an optical fiber sensing device 9, and a display device 10. The high-temperature superconducting cable refrigeration system comprises the high-temperature superconducting cable body 1, the superconducting cable terminal 2, the liquid nitrogen storage tank 3, the liquid nitrogen valve 4, the refrigerator 5, the liquid nitrogen buffer tank 6, and the compressor 7. The present invention lays the measuring optical fiber 8 throughout the entire high-temperature superconducting cable refrigeration system. For example, the measuring optical fiber 8 is connected to the optical fiber sensing device 9 and enters the high-temperature superconducting cable refrigeration system through the refrigerator 5. The measuring optical fiber 8 is laid throughout the entire high-temperature superconducting cable refrigeration system and extends through another refrigerator 5. The optical fiber sensing device 9 transmits the temperature signal of the high-temperature superconducting cable refrigeration system to the display device 10, which displays the distribution curve of the temperature signal in real time.

[0051] It can be seen that the fact that the measuring optical fiber 8 extends out of the high-temperature superconducting cable refrigeration system indicates that the measuring optical fiber 8 is connected inside the high-temperature superconducting cable refrigeration system and that the length of the measuring optical fiber 8 is sufficient; the outdoor temperature can be measured through the extended measuring optical fiber 8 to determine the accuracy of the temperature measurement of the heat leakage monitoring system.

[0052] in, Figure 1 The arrow in FIG. 1 indicates the flow direction of liquid nitrogen in the high-temperature superconducting cable refrigeration system when the valve on the left side of the liquid nitrogen valve 4 is opened.

[0053] The following is a detailed description of the heat leakage monitoring system of the high-temperature superconducting cable refrigeration system provided by the present invention:

[0054] The measuring optical fiber is installed in the high-temperature superconducting cable cooling system to collect temperature signals.

[0055] As can be seen, the heat load sources in a high-temperature superconducting cable system are relatively dispersed, occurring in nearly every part of the system. Therefore, to promptly monitor heat leakage and temperature changes in each part of the high-temperature superconducting cable, distributed, rapid, and effective heat leakage monitoring is necessary. The present invention lays measurement optical fibers throughout various parts of the high-temperature superconducting cable refrigeration system to collect temperature signals from each component.

[0056] Specifically, since the measuring optical fiber is continuous inside the high-temperature superconducting cable refrigeration system, continuous measurement of the temperature signal of the high-temperature superconducting cable refrigeration system can be achieved. Not only the temperature signals of a few key points can be measured, but also the entire high-temperature superconducting cable refrigeration system can be effectively monitored for heat leakage.

[0057] It is known that the present invention can collect temperature signals at all points on the measuring optical fiber, that is, it can achieve continuous measurement of temperature signals. For example, it can locate a specific position and collect the temperature signal on the measuring optical fiber.

[0058] Preferably, the measuring optical fiber is laid in a high-temperature superconducting cable refrigeration system.

[0059] Specifically, the measuring optical fiber is laid in the liquid nitrogen circulation pipeline of the high-temperature cable refrigeration system. The liquid nitrogen circulation pipeline includes the high-temperature superconducting cable body, the superconducting cable terminal, and the remaining liquid nitrogen infusion pipeline. The superconducting cable terminal is used to connect the high-temperature superconducting cable body and the liquid nitrogen infusion pipeline, acting as a connector.

[0060] The optical fiber laying method of the high-temperature superconducting cable body in the present invention is different from that of other liquid nitrogen circulation pipelines.

[0061] Preferably, the high-temperature superconducting cable cooling system comprises a superconducting cable body; the measuring optical fiber is spirally wound around the superconducting cable body and fixed with epoxy resin glue.

[0062] Preferably, the high-temperature superconducting cable refrigeration system further comprises a liquid nitrogen circulation pipeline: the measuring optical fiber is attached to the inner wall of the liquid nitrogen circulation pipeline and fixed with epoxy resin glue.

[0063] Figure 2 This is a schematic diagram of the installation of the measuring optical fiber of the high-temperature superconducting cable body of the present invention, as shown in FIG. Figure 2 As shown, it includes: a measuring optical fiber 8 and a high-temperature superconducting cable body 1. The measuring optical fiber 1 is spirally wound on the high-temperature superconducting cable body 1 and fixed with epoxy resin glue.

[0064] Figure 3This is a schematic diagram of the installation of optical fiber for measuring the liquid nitrogen flow pipeline of the present invention, as shown in FIG. Figure 3 As shown, it includes: a liquid nitrogen circulation pipeline wall 11, a measuring optical fiber 8 and epoxy resin glue 12, and the measuring optical fiber 8 is laid on the liquid nitrogen circulation pipeline wall 11.

[0065] Specifically, the measuring optical fiber 8 is adhered to the inner wall of the liquid nitrogen circulation pipe using epoxy resin glue.

[0066] The optical fiber sensing device is connected to the measuring optical fiber and is used to obtain the temperature signal.

[0067] Preferably, the high-temperature superconducting cable refrigeration system further includes a refrigerator; the measuring optical fiber extends from the refrigerator and is connected to the optical fiber sensing device.

[0068] Heat leakage monitoring of high-temperature superconducting cable refrigeration system is carried out through temperature signals.

[0069] Specifically, one measuring optical fiber or a plurality of measuring optical fibers bundled together form an optical cable, according to Figure 2 and Figure 3 The laying method shown is implanted as Figure 1 In the high-temperature superconducting cable refrigeration system shown, the measuring optical fiber will pass through the entire liquid nitrogen circulation loop, including the high-temperature superconducting cable body, superconducting cable terminal, liquid nitrogen storage tank, and refrigerator. The end of the measuring optical fiber will extend from the refrigerator and be connected to the optical fiber sensing device. Depending on the actual situation, the optical fiber sensing device can realize multi-channel signal measurement; anti-Stokes light signal is collected and analog-to-digital converted to obtain anti-Stokes light intensity distribution information of the superconducting cable refrigeration system; the optical fiber sensing device transmits the anti-Stokes light intensity distribution signal of the refrigeration system to the display device, and its distribution curve is displayed in real time.

[0070] The present invention provides a method for monitoring heat leakage of a high-temperature superconducting cable refrigeration system, comprising: using a heat leakage monitoring system of a high-temperature superconducting cable refrigeration system to perform the following steps.

[0071] Step 1: Collect the temperature signal of the high-temperature superconducting cable cooling system through the measuring optical fiber.

[0072] The present invention utilizes a measuring optical fiber implanted in a high-temperature superconducting cable refrigeration system, combined with distributed optical fiber sensing technology based on the Raman scattering principle, to monitor the heat leakage of the entire refrigeration system of the high-temperature superconducting cable in real time.

[0073] The following is a detailed explanation of the Raman scattering temperature measurement principle through formula (1), formula (2) and formula (3):

[0074]

[0075]

[0076]

[0077] Among them, I as represents the anti-Stokes intensity; I s represents the Stokes intensity; R represents the Raman ratio; h represents the Planck constant; K s and K as are the position-dependent scattering loss factors of Stokes light and anti-Stokes light, respectively; k is the Boltzmann constant; Δυ is the Raman frequency shift; and T is the Kelvin temperature.

[0078] Raman scattering signals contain two frequency components, namely anti-Stokes light and Stokes light. In general, we use the anti-Stokes light intensity (I as ) and Stokes intensity (I s ) ratio to demodulate the temperature signal. Formulas (1), (2), and (3) above respectively show the expressions for the anti-Stokes intensity, the Stokes intensity, and the Raman ratio. The anti-Stokes intensity is very sensitive to temperature, while the Stokes intensity is insensitive to temperature. During the temperature demodulation process, the Stokes intensity is used as a reference signal to remove the remaining environmental variables carried by the anti-Stokes signal.

[0079] Step 2: Use the temperature signal obtained by the optical fiber sensing device to monitor the heat leakage of the high-temperature superconducting cable refrigeration system.

[0080] Preferably, step 2 includes: step 201: acquiring an anti-Stokes optical signal in the temperature signal; step 202: performing heat leakage monitoring on the high-temperature superconducting cable refrigeration system through the anti-Stokes optical signal.

[0081] Preferably, the method further comprises: Step 3: adjusting the time resolution of the optical fiber sensing device to optimize the rate of heat leakage monitoring.

[0082] Preferably, the temperature signal includes an anti-Stokes optical signal and a Stokes optical signal.

[0083] Specifically, to improve the sensitivity of heat leakage monitoring and ensure timely signal measurement, the present invention only detects the anti-Stokes optical signal in the measurement fiber to represent the temperature signal, without performing temperature demodulation. This saves demodulation time and achieves rapid monitoring. Furthermore, the temperature monitoring rate can be further improved by adjusting the time resolution of the fiber optic sensing device, optimizing the temperature monitoring effect.

[0084] Figure 4 Schematic diagram of the time resolution of the present invention versus the quench response speed, as shown in FIG. Figure 4As shown, the horizontal axis is time in seconds (s), the vertical axis is anti-Stokes intensity, TR is time resolution, i peak Represents the pulse current, the discrete triangles on the way represent the data, the curve where the solid circle is located represents the curve of the anti-Stokes light intensity when the TR is 300 milliseconds (ms), and the curve where the triangle is located represents the curve of the anti-Stokes light intensity when the TR is 30 milliseconds (ms). In the present invention, an i is applied during the process from 0 seconds to 2 seconds. peak =700A current to test the effect of different time resolutions on the response speed of the quench.

[0085] like Figure 4 Figure 2 shows the changes in anti-Stokes intensity measured by the fiber optic sensor when the coil under test is subjected to a short, high current surge at time resolutions of 30ms and 300ms. It can be seen that when the time resolution is 30ms, the anti-Stokes intensity change occurs approximately 500ms earlier than when the time resolution is 300ms, demonstrating that optimizing the time resolution of optical sensing equipment can effectively improve condition monitoring rates.

[0086] It is known that the process of superconducting materials changing from a superconducting state to a normal conducting state is called quenching.

[0087] Preferably, the method includes: Step 4: sending the temperature signal to a display device for display.

[0088] Compared with the prior art, the present invention has the following beneficial effects:

[0089] 1. The present invention ensures the safety of the high-temperature superconducting cable by performing heat leakage monitoring on the refrigeration system of the high-temperature superconducting cable.

[0090] 2. The present invention measures the temperature signals of various parts of the high-temperature superconducting cable refrigeration system by laying the measuring optical fiber in the high-temperature superconducting cable refrigeration system, thereby realizing heat leakage monitoring and ensuring the safe operation of the high-temperature superconducting cable.

[0091] Those skilled in the art will appreciate that, in addition to implementing the system, device, and various modules provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method submodule M. Therefore, the system, device, and various modules provided by the present invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0092] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A heat leakage monitoring system for a high-temperature superconducting cable refrigeration system, characterized in that: include: A measuring optical fiber is provided in the high-temperature superconducting cable refrigeration system and is used to collect temperature signals; an optical fiber sensing device, connected to the measuring optical fiber, for acquiring the temperature signal; Performing heat leakage monitoring on the high-temperature superconducting cable refrigeration system through the temperature signal; The measuring optical fiber is laid in the high-temperature superconducting cable refrigeration system; The high-temperature superconducting cable refrigeration system includes a superconducting cable body; Helically winding the measuring optical fiber on the superconducting cable body and fixing it with epoxy resin glue; The high-temperature superconducting cable refrigeration system further includes a liquid nitrogen circulation pipeline: The measuring optical fiber is attached to the inner wall of the liquid nitrogen circulation pipe and fixed with epoxy resin glue.

2. The heat leakage monitoring system for a high-temperature superconducting cable refrigeration system according to claim 1, characterized in that: The high-temperature superconducting cable refrigeration system further includes a refrigerator; The measuring optical fiber extends from the refrigerator and is connected to the optical fiber sensing device.

3. A method for monitoring heat leakage in a high-temperature superconducting cable refrigeration system, characterized in that: include: The heat leakage monitoring system for a high-temperature superconducting cable refrigeration system according to claim 1 is used, and the following steps are performed: Step 1: collecting the temperature signal of the high-temperature superconducting cable refrigeration system through the measuring optical fiber; Step 2: performing heat leakage monitoring on the high-temperature superconducting cable refrigeration system using the temperature signal obtained by the optical fiber sensing device; The step 2 includes: Step 201: Acquire an anti-Stokes optical signal in the temperature signal; Step 202: performing heat leakage monitoring on the high-temperature superconducting cable refrigeration system using the anti-Stokes optical signal; The temperature signal includes an anti-Stokes optical signal and a Stokes optical signal.

4. The method for monitoring heat leakage of a high-temperature superconducting cable refrigeration system according to claim 3, characterized in that: The method further comprises: Step 3: Adjust the time resolution of the fiber optic sensing device to optimize the rate of the heat leakage monitoring.

5. The method for monitoring heat leakage of a high-temperature superconducting cable refrigeration system according to claim 3, characterized in that: include: Step 4: Send the temperature signal to a display device for display.

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