WO2020151032A1 - High-temperature superconducting cable temperature measurement system - Google Patents

Abstract

A high-temperature superconducting cable temperature measurement system, which is applied to a high-temperature superconducting cable (11) and terminal cooling systems (4) which are connected to each other, comprising: low-temperature temperature measurement optical fibers (9) provided in the high-temperature superconducting cable (11), and thermal resistors (5) provided in the terminal cooling systems (4); an optical fiber temperature measurement host (1) for receiving temperature measurement information from each measurement point of the low-temperature temperature measurement optical fibers (9); a thermal resistor temperature monitor (2) for receiving temperature information from the thermal resistor (5); a temperature measurement and control device (3) for receiving the temperature measurement information and the temperature information, performing evaluation and determination according to the temperature measurement information and the temperature information to determine a protection action and a protection region of a cable operation control host (6) connected thereto, and controlling the cable operation control host (6) to perform corresponding operations. The present system has the features of easy use and simple structure, etc., and can accurately monitor and position temperature abnormal points of the high-temperature superconducting cable, facilitating clearing of faults during maintenance and test of the superconducting cable, reducing the fault range, and reducing the fault processing time.

Description

A high-temperature superconducting cable temperature measurement system

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on January 23, 2019, the application number is 201910062551.3, and the invention title is "a high temperature superconducting cable temperature measurement system". The entire content of the above patent is incorporated by reference In this application.

Technical field

The invention relates to the application field of power transmission technology, in particular to a high-temperature superconducting cable temperature measurement system.

Background technique

With the rapid development of my country's economy, electricity consumption in many cities has increased year by year. The power load in the central area of the city has increased sharply, and the transmission and distribution capacity has increased significantly, reducing power grid losses and improving grid operation stability. At present, the power grid system has a large loss in the transmission and distribution links, so all countries are looking for solutions to reduce power grid losses. Among them, superconducting materials are one of the most important solutions to reduce power grid losses. The commercial production of high-temperature superconducting tapes has promoted The extensive research and application of guide devices all over the world. Compared with conventional power cables, high-temperature superconducting cables have received widespread attention because of their strong flow capacity, large capacity, compact structure, and no electromagnetic radiation pollution. At present, there are already many high-temperature superconducting cables running on the network worldwide. .

Different from the application of conventional power cables, the operating environment of high-temperature superconducting cables must be at least below the temperature of liquid nitrogen (-196°C), and their size is smaller and more compact. Therefore, the large-scale application of high-temperature superconducting cables in the power grid has the following two technical difficulties:

(1) When the high-temperature superconducting cable is running, the superconducting cable needs to be cooled to below the critical temperature (-196℃) from the outside, otherwise it will not operate. However, when a part of the superconducting cable is transformed from a superconducting state to a normal state due to thermal disturbance in some areas of the superconducting cable when it is energized, the generated Joule heat will increase the temperature of the superconducting cable, thereby promoting the normal conduction transition around it. Enlarge the area of the normal conduction state (quench phenomenon);

(2) The whole line of high-temperature superconducting cable runs in liquid nitrogen, so its structure is very different from conventional power cables. Its smaller size and compact structure make it impossible to install traditional temperature sensors such as thermal resistance and thermal resistance. The temperature along the conducting cable is monitored (the insulation performance of the cable is destroyed and the temperature measurement performance of the temperature sensor is affected by electromagnetic interference).

The above two points limit the popularization and application of high-temperature superconducting cables in the power grid, and because of the above-mentioned difficulty, the current temperature monitoring range of superconducting cable systems is limited to the temperature monitoring of the terminal cooling system, and the temperature along the high-temperature superconducting cable has not yet appeared Measurement.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a high-temperature superconducting cable temperature measurement system, which has the characteristics of convenient use and simple structure, can accurately monitor and locate the abnormal temperature along the high-temperature superconducting cable, and is convenient for the superconducting cable Troubleshooting during maintenance and inspection, narrow the scope of the fault, and reduce the troubleshooting time.

In order to solve the above technical problems, embodiments of the present invention provide a high-temperature superconducting cable temperature measurement system, which is applied to interconnected high-temperature superconducting cables and terminal cooling systems, which includes:

A low-temperature temperature measuring optical fiber arranged in the high-temperature superconducting cable, and a thermal resistor arranged in the terminal cooling system;

The optical fiber temperature measurement host is used to receive temperature measurement information from various measurement points of the low temperature temperature measurement optical fiber;

Thermal resistance temperature monitor, used to receive temperature information from thermal resistance;

The temperature measurement control device is connected to the optical fiber temperature measurement host and the thermal resistance temperature monitor, receives the temperature measurement information and temperature information, and performs evaluation and judgment based on the temperature measurement information and temperature information to determine the The cable operation controls the protection action and protection area of the host, and the cable operation control host operates the corresponding converter system or circuit breaker according to the protection action and the protection area.

Preferably, the optical fiber temperature measurement host further includes:

The collection information receiving unit is used to separately collect the Stokes light and the anti-Stokes light scattered at each temperature measurement point of the low temperature temperature measurement fiber;

The first calculation unit is used to calculate the Stokes light and the anti-Stokes light at each temperature measurement point to obtain the temperature of the temperature measurement point. The calculation formula is as follows:

Formula, I _AS to the anti-Stokes light intensity; I _S Stokes light intensity; H is Planck's constant; Blue K is Boltzmann's constant; V is the frequency of the laser; v _i is the frequency of vibration ; T is the absolute temperature; after laser source is determined, v is a constant; v _i is determined by the fiber material, the fiber is determined, which is a constant;

The position measuring unit is used to position each temperature measurement point of the low temperature temperature measurement optical fiber based on optical time domain reflectometry (OTDR) technology, and obtain position information of each temperature measurement point.

Preferably, the thermal resistance is a T100 temperature sensor.

Preferably, the temperature measurement system includes:

The signal receiving and processing unit is used to obtain the temperature T along the cable, the average value T _{av of the} temperature along the cable and the cooling system temperature T _c after the temperature measurement control device 3 receives the temperature signal,

The protection action determination unit is used to combine the value obtained by the signal receiving and processing unit with the preset cable temperature alarm value T _l , the maximum allowable cable temperature T _max , the lower threshold value of the cable average temperature T _L , and the higher average cable temperature The threshold value T _H is compared with the maximum allowable temperature T _{cH of the} cooling system to determine the protection action of the cable operation control host;

The protection area determination unit is used to obtain the temperature curve along the cable after obtaining the value, and obtain the schematic diagram of the temperature abnormal point obtained by the morphological gradient-based wave crest width identification method through simulation, and the temperature abnormality point diagram is positive The relative position of the negative narrow peak pair is used to determine the position of the abnormal temperature point on the cable, thereby determining the protection area;

The protection information sending unit is used to send the protection action and protection area information to the cable operation control host connected to it.

Preferably, the protection action determination unit uses the following strategy to determine the protection action:

When the comparison result is (T>T _l )∨(T _av >T _L ), the generated protection action is an alarm command. When the cable operation control host receives the alarm command and protection zone information, it controls the protection described in the converter system High-temperature superconducting cable power transmission in the region;

When comparison result _{(T> T max) ∨ (} T av> T H) ∨ (T c> T cH), protective action is generated a trip command, the control cable running in the host to pick up the trip command and the protected area When the information is available, control the circuit breaker to timely cut off the faulty high-temperature superconducting cable in the protection area from the power grid.

Preferably, the high-temperature superconducting cable includes from outside to inside: a cryostat, a shielding layer, at least one insulating layer and a phase conductor, and a cable skeleton; between the cryostat and the shielding layer and between The cable skeleton is filled with liquid nitrogen, of which,

The high temperature superconducting cable is further equipped with a low temperature resistant temperature measuring optical fiber, and the low temperature resistant temperature measuring optical fiber is installed at least in one of the following three positions: the outer surface of the shielding layer, the outermost insulating layer and the outermost layer Between the phase conductors and the inner surface of the cable skeleton.

Preferably, the low-temperature-resistant and temperature-measuring optical fiber adopts a quartz-based multi-mode optical fiber, and a coating material is coated around the optical fiber cladding in a manner that the cross section of the optical fiber is concentric circles, or a non-metallic tight-clad tube is sheathed; The non-metal tightly wrapped casing is selected from fiber reinforced composite plastic casing, PBT loose casing, and fenlon kevlar casing.

Preferably, the low-temperature resistant optical fiber adopts a linear laying or S-shaped laying method.

Preferably, the cryostat 12 is made of double-layer stainless steel welding with a vacuum interlayer, and multiple layers of thermal insulation materials and activated carbon are arranged in the vacuum interlayer of the double-layer stainless steel;

The shielding layer is a copper shielding layer, and its single end or double ends are grounded;

The insulating layer is made of polypropylene laminated paper, aromatic polyamide paper or polyimide material;

The phase conductor is the second-generation high-temperature superconducting tape YBCO, the width of which is ≥5mm, the thickness of which is required to be ≈0.3mm, and the copper layer is plated as a stable layer;

The cable skeleton is a metal corrugated pipe covered with a dense metal mesh, which is a reference support for the superconducting tape to be wound, and is also used for liquid nitrogen circulation pipelines.

Preferably, the high-temperature superconducting cable is a three-phase independent superconducting cable structure, a three-phase parallel-axis superconducting cable structure or a three-phase coaxial superconducting cable structure.

Implementing the embodiments of the present invention has the following beneficial effects:

The high-temperature superconducting cable temperature measurement system provided by the present invention is based on the combined use of traditional temperature sensors (thermal resistance) and optical fiber temperature measurement technology. The optical fiber is installed in the superconducting cable in advance when the superconducting cable is made, and the thermal The resistor is arranged at the terminal of the superconducting cable (terminal cooling system) to form a composite temperature measuring component of optical fiber temperature measurement and thermal resistance temperature measurement to measure the temperature along the high-temperature superconducting cable and the temperature of the terminal cooling system. The system can accurately grasp the temperature distribution along the high-temperature superconducting cable in real time, so as to control the transmission current of the cable or control the superconducting cable protection device according to the operating temperature of the superconducting cable; it can detect the cable operation defects related to thermal disturbance in time, and Send an alarm signal to ensure the safe operation of the high-temperature superconducting cable; propose a method to accurately locate the abnormal temperature along the high-temperature superconducting cable by the position of the positive and negative narrow peak pairs of the morphological gradient, which is convenient for the troubleshooting of the superconducting cable during maintenance and detection. Reduce the scope of the fault and reduce the troubleshooting time.

The high-temperature superconducting cable temperature measurement system provided by the present invention can be applied to the temperature measurement and monitoring protection of high-temperature superconducting cables in power grids. Depending on the structure of the high-temperature superconducting cable, it can cover high, medium and low voltage levels. High stability and reliability.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, without creative labor, obtaining other drawings based on these drawings still belongs to the scope of the present invention.

Fig. 1 is a schematic structural diagram of an embodiment of a high-temperature superconducting cable temperature measurement system provided by the present invention;

Figure 2 is a schematic cross-sectional view of the high-temperature superconducting cable involved in Figure 1;

Figure 3 is a schematic structural diagram of the optical fiber temperature measurement host involved in Figure 1;

Fig. 4 is a schematic structural diagram of the temperature measurement control device involved in Fig. 1;

Fig. 5 is a schematic diagram of the principle of Top-Hat transformation of the morphological algorithm involved in the protection area determination unit in Fig. 4;

Fig. 6 is a diagram of input and output involved in the protection area determination unit in Fig. 4.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

As shown in Figure 1, it is a schematic structural diagram of an embodiment of the high-temperature superconducting cable temperature measurement system provided by the present invention; in conjunction with the subsequent drawings, in this embodiment, the embodiment of the present invention provides a high-temperature superconducting cable temperature measurement system. The conducting cable temperature measurement system is applied to the interconnected high-temperature superconducting cable 11 and the terminal cooling system 44, which includes:

The low-temperature temperature measurement optical fiber 9 arranged in the high-temperature superconducting cable 11, and the thermal resistance 5 arranged in the terminal cooling system 4;

Optical fiber temperature measurement host 1 for receiving temperature measurement information from various measurement points of the low temperature temperature measurement optical fiber 9;

Thermal resistance temperature monitor 2 for receiving temperature information from thermal resistance 5;

The temperature measurement control device 3 is connected to the optical fiber temperature measurement host 1 and the thermal resistance temperature monitor 2 to receive the temperature measurement information and temperature information, and perform evaluation and judgment based on the temperature measurement information and temperature information to determine The connected cable operation controls the protection action and protection area of the host 6, and the cable operation control host 6 operates the corresponding converter system 7 or circuit breaker 8 according to the protection action and protection area.

It can be understood that, in the embodiment of the present invention, the present invention preliminarily installs a low temperature resistant (below -196°C) temperature measuring optical fiber 9 inside the high temperature superconducting cable 11, and arranges a thermal resistor 5 inside the terminal cooling system 4, and The temperature measurement control device 3 judges the cable operation status according to the temperature signal, and thus presets the action of the cable operation control host 6. The judgment is based on the comparison result between the actual measured temperature and the preset temperature thresholds, and is based on the form Analyze the waveform characteristics of the learning gradient to determine the location of the abnormal temperature point. The cable operation control host 6 controls the commutation system 77 or the circuit breaker 8 according to the determination result to ensure that the high-temperature superconducting cable 11 is in a safe operation state or to cut off the faulty cable in time.

In order to facilitate the understanding of the structure of the present invention, various components involved in the present invention will be described in detail below. First, the structure of the high-temperature superconducting cable 11 involved in the present invention will be described.

The high-temperature superconducting cable 119 involved in the present invention can be divided into three categories according to the relationship between the cable phase and the phase conductor: (a) three-phase independent superconducting cable structure, (b) three-phase parallel axis superconducting cable structure, and (c) ) Three-coaxial superconducting cable structure. Among them, three-phase independent superconducting cable refers to a cable jacket containing only one phase conductor. In order to avoid electromagnetic interference between phases, three-phase independent superconducting cables can be used in medium and high voltage levels; three-phase parallel The three phases of the shaft superconducting cable are contained in the same insulator and cable jacket, which greatly saves space, and has low conductor loss. It does not require a metal protective layer for shielding electromagnetic fields and can be used in medium voltage levels; and the three are the same The three-phase conductors of the axial superconducting cable are wound along the same axis, which saves more space, and the entire cable uses only one shielding layer 13, which also saves materials, but this structure also increases the difficulty of electrical insulation. It is only suitable for medium and low voltage voltage levels.

In this embodiment, the description is made with a three-coaxial superconducting cable structure. It is understandable that the present invention can also adopt two other types of superconducting cable structures.

As shown in FIG. 2, in the embodiment of the present invention, the high-temperature superconducting cable 11 includes from the outside to the inside: a cryostat 12, a shielding layer 13, at least one insulating layer and phase conductors, and a cable skeleton 16. Among them, at least one insulating layer includes the C-phase insulating layer 14 at the outermost layer, and at least one layer of the phase conductor includes the C-phase conductor 15, followed by the B-phase insulating layer, the B-phase conductor, the A-phase insulating layer, Phase A conductor; liquid nitrogen 17 is filled between the cryostat 12 and the shielding layer 13 and in the cable skeleton 16, so that the high-temperature superconducting cable 11 works below the operating temperature (-196°C).

A low temperature resistant temperature measuring optical fiber 9 is further installed in the high temperature superconducting cable 11, and the low temperature resistant temperature measuring optical fiber 9 is installed in at least one of the following three positions: the outer surface of the shielding layer 13 and the outermost insulating layer (Namely the C-phase insulating layer 14) and the outermost phase conductor (namely the C-phase conductor 15) on the inner surface of the cable skeleton 16.

Wherein, the cryostat 12 is made of double-layer stainless steel welding with a vacuum interlayer. In the vacuum interlayer of the double-layer stainless steel, multiple layers of thermal insulation materials and activated carbon are further arranged to ensure the liquid nitrogen entering and exiting the superconducting cable 11. The temperature remains constant;

The shielding layer 13 is a copper shielding layer, its single-ended or double-ended grounding, its main function is to shield the electric field, no current flows through itself;

The insulating layer is made of polypropylene laminated paper (PPLP), aromatic polyamide paper (Nomex) or polyimide material (PI), and these materials are all composite materials that are normally used at low temperatures; it is understandable Yes, the design of the insulating layer depends on factors such as the characteristics of the insulating material, the operating voltage, and the size of the cable. Considering factors such as electrical performance, thermal performance, mechanical performance, and process difficulty, in this embodiment, PPLP may be preferred as the low-temperature insulating material.

In this embodiment, the second-generation high-temperature superconducting tape YBCO is used as the phase conductor, with a width ≥5mm and a thickness of ≈0.3mm, and is plated with a copper layer as a stable layer; it is understandable that the second-generation The high-temperature superconducting tape YBCO refers to the rare earth film conductor grown epitaxially on the metal substrate (someone calls it the rare earth coating conductor). This material is first coated with a chemically stable layer that is conducive to the extension of the crystal structure on the base tape of nickel or nickel alloy, and the high temperature superconducting material RBa ₂ Cu ₃ O ₇ (R Represents a certain rare earth element, the most commonly used is Y series), and then plated with a protective layer of silver or copper. At present, the manufacturer can provide the second-generation high-temperature superconducting tape with a width of 4-12mm, and its thickness is generally 0.3mm or less.

The cable skeleton 16 is a metal corrugated pipe covered with a dense metal mesh, which is a reference support for the superconducting tape to be wound, and is also used as a liquid nitrogen flow pipeline.

The low-temperature resistant temperature measuring optical fiber 9 adopts a quartz-based multimode optical fiber. Specifically, the material constituting the quartz-based optical fiber can be pure quartz glass, germanium (Ge)-doped quartz glass (with increased refractive index), etc. Choose appropriately.

It is understandable that the temperature measuring fiber 9 used in the high-temperature superconducting cable 11 needs to be able to withstand extremely low temperature (below -196°C) environment, and the optical signal can propagate normally in the low-temperature-resistant fiber 9 without being affected by temperature The influence of other physical factors such as stress;

Based on the consideration of not damaging the insulation performance of the high-temperature superconducting cable 11 after installing the optical fiber and not increasing the difficulty of installation as much as possible, the size of the low-temperature-resistant temperature measuring optical fiber 9 should be as small as possible and cannot be equipped with metal armor. Therefore, the temperature measurement optical fiber 9 can be a bare optical fiber (lower strength) coated with polyimide or a non-metallic tight-sleeved optical fiber. The non-metal tightly wrapped sleeve is generally selected from fiber-reinforced composite plastic sleeve, PBT loose sleeve, fenlon kevlar sleeve, etc., which can protect the optical fiber, increase its strength, and make it difficult to be broken.

The high-temperature superconducting cable 11 used in this embodiment is a three-coaxial superconducting cable structure, which has a compact structure and a small size. Therefore, the selected temperature measuring optical fiber 9 is not easy to be too large in size to avoid occupying too much internal space of the superconducting cable and not affecting the insulation performance of the cable. In the embodiment, the bare optical fiber coated with only polyimide or the non-metallic tightly sheathed optical fiber with a small size is selected, and the installation position inside the high-temperature superconducting cable 11 is shown in FIG. 2 .

A small bare fiber coated with polyimide material can be installed between the C-phase conductor 15 and the C-phase insulating layer 14 to more directly detect the temperature of the phase conductor, but the bare fiber should be noted The strength is low, and if the bare optical fiber is directly installed in the preparation process of the superconducting cable, it is easy to be damaged and broken during the complicated preparation process (the installation is extremely difficult). In order to reduce the installation difficulty, consider the use of smaller non-metallic tightly sheathed optical fiber, which has high strength and hardly affects the insulation performance of the cable. It can be installed on the cable skeleton 16 of the high-temperature superconducting cable 11 or It is installed in the gap between the shielding layer 13 and the cryostat 12.

In the actual project, you can choose the optical fiber installation position and quantity according to the specific temperature measurement requirements: the above installation position can install multiple temperature measurement fibers at the same time, or you can choose to install one of the temperature measurement fibers.

The temperature measuring optical fiber 9 installed between the C-phase conductor 15 and the C-phase insulating layer 14 inside the high-temperature superconducting cable 11 can be laid on the C-phase conductor 15 in a straight line, and along with the C-phase conductor 15 Winding together; the temperature measuring optical fiber 9 installed in the cable skeleton 16 of the high-temperature superconducting cable 11 or installed between the shielding layer 13 and the cryostat 12 can be laid in an S-shaped laying method.

For the other two types of superconducting cables, the optical fiber installation position and method are the same as the three-coaxial high-temperature superconducting cable 11 selected in this example.

Next, the optical fiber measurement host involved in the present invention will be described. As shown in FIG. 3, in this embodiment, the optical fiber temperature measurement host 1 further includes:

The collection information receiving unit 100 is configured to separately collect the Stokes light and the anti-Stokes light scattered at each temperature measurement point of the low-temperature temperature measurement optical fiber 9;

The first calculation unit 110 is used to calculate the Stokes light and the anti-Stokes light of each temperature measurement point to obtain the temperature of the temperature measurement point. The calculation formula is as follows:

Formula, I _AS to the anti-Stokes light intensity; I _S Stokes light intensity; H is Planck's constant; Blue K is Boltzmann's constant; V is the frequency of the laser; v _i is the frequency of vibration ; T is the absolute temperature; after laser source is determined, v is a constant; v _i is determined by the fiber material, the fiber is determined, which is a constant;

The position measurement unit 120 is configured to position each temperature measurement point of the low-temperature temperature measurement optical fiber 9 based on optical time domain reflectometry (OTDR) technology, and obtain position information of each temperature measurement point.

Specifically, the position measurement unit 120 locates the temperature measurement points along the optical fiber based on optical time domain reflectometry (OTDR) technology. The basic principle is: the pulsed light emitted by the laser source is injected into the optical fiber for transmission. It is assumed that the moment when the incident light enters the optical fiber is the zero time of the timing starting point. The scattered light occurs at a distance from the laser source L, and the backscattered light returns along the core of the fiber. The time to the incident end is denoted as t, then

Among them, v refers to the propagation speed of light waves in the fiber, c refers to the speed of light under vacuum, and n refers to the refractive index of the fiber. Therefore, the distance between the measuring point and the incident port can be obtained from the time t, and positioning can be realized. This technology that uses the data collection time interval of incident light and reflected light to achieve spatial positioning is optical time domain reflectometry (OTDR).

It is understandable that the Stokes light and anti-Stokes light scattered at each temperature measurement point are collected separately through the optical signal collection channel on the optical fiber temperature measurement host 11, and the temperature is demodulated by the ratio of the intensities of the two. Signal; Among them, the temperature measurement point is set by the temperature measurement software configured by the optical fiber temperature measurement host 11, that is, the optical signal sampling interval point (in this example, the sampling interval is set to 0.4m), and the optical fiber temperature measurement host 11 will measure each temperature measurement point The light signal of the sensor is collected and its position is located.

For the thermal resistance temperature monitor 2, the connected thermal resistance 5 is based on the characteristic that the resistance value of the metal conductor changes with temperature to perform temperature measurement, if its resistance value increases with the temperature rise , Then it is called a positive resistivity temperature resistance sensor, on the contrary, if its resistance value decreases with temperature rise, it is called a negative resistivity resistance temperature sensor. The thermal resistance 5 is mostly made of pure metal materials, and platinum and copper are currently the most widely used. In addition, materials such as nickel, manganese and rhodium have now been used to make thermal resistance. Among them, platinum thermal resistance 5 (PT100 temperature sensor) has the highest measurement accuracy. It is not only widely used in industrial temperature measurement, but also made into a standard reference instrument. The temperature measurement range of PT100 is -200℃-650℃, and the measurement accuracy can reach 0.1℃. It has good stability and fast response speed. It is an ideal choice for temperature measurement in low temperature environments. Therefore, in this embodiment, a PT100 platinum resistance is used as a temperature sensor to monitor the temperature of the terminal cooling system 4.

Continue to introduce the temperature measurement control device 3, as shown in FIG. 4, in the embodiment of the present invention, the temperature measurement control device 3 includes:

The signal receiving and processing unit 300 is used to obtain the temperature T along the cable, the average value T _{av of the} temperature along the cable, and the terminal cooling system temperature T _c after receiving the temperature signal,

The protection action determination unit 310 is used to combine the value obtained by the signal receiving and processing unit 300 with the preset cable temperature alarm value T _l , the maximum allowable cable temperature T _max , the low cable average temperature threshold T _L , and the cable average The high temperature threshold T _H is compared with the maximum allowable temperature T _{cH of the} terminal cooling system to determine the protection action of the cable operation control host 6;

The protection area determination unit 320 is configured to obtain the temperature curve along the cable after obtaining the value, and obtain a schematic diagram of temperature abnormalities obtained by the method of identifying the peak width based on the morphological gradient through simulation, and pass the temperature abnormalities in the schematic diagram of the temperature abnormalities The relative position of the pair of positive and negative narrow peaks is used to determine the position of the abnormal temperature point on the cable, thereby determining the protection area;

The protection information sending unit 330 is configured to send the protection action and protection area information to the cable operation control host 6 connected thereto.

Preferably, the protection action determining unit 310 uses the following strategy to determine the protection action:

When the comparison result is (T>T _l )∨(T _av >T _L ) (that is, when any of the above judgment results appear), the generated protection action is an alarm command, and the cable operation control host 6 receives the alarm command and When protecting area information, control the high-temperature superconducting cable 11 in the protection area described by the converter system 7 to transmit power;

(I.e., when any of the above determination result appears) to _{(T> T max) ∨ (} T av> T H) ∨ (T c> T cH) in contrast to the results, the resulting protective action tripping command, control cable runs When the host 6 receives the trip command and the protection area information, it controls the circuit breaker 8 to timely cut off the faulty high temperature superconducting cable 11 in the protection area from the power grid.

In the embodiment of the present invention, the protection area determination unit 320 uses a morphological gradient-based wave crest width identification method to determine the protection area (that is, the fault area).

Among them, mathematical morphology (Mathematical Morphology) is a mathematical method for analyzing geometric shapes and structures. It is based on set algebra and is a discipline that uses set theory to quantitatively describe the geometric structure of a target. Among them, morphological operations and corrosion images are the two most basic operations in morphology:

Corrosion-means using a certain "probe" (that is, a primitive or structural element of a certain shape) to detect an image in order to find out the area within the image where the primitive can be oriented. Corrosion is similar to shrinking the image. It is defined as follows:

数学形式为

Set A is corroded by set B, expressed as

The mathematical form is

Expansion-the dual operation of the corrosion operation, similar to expansion, its mathematical form is

Calculating the morphological gradient of an image is one of the important operations of morphology, which is composed of two basic operations of corrosion and expansion. There is a gray value morphology algorithm in the morphological gradient. The Top-Hat (top hat) transformation has the function of monitoring the peak. The schematic diagram is shown in Figure 5. It is defined as the signal is corroded by the primitive, and the Top-Hat is obtained by the open operation. -Hat transform to detect the peak of the signal.

In summary, the temperature measurement control device 3 inputs the temperature signal along the cable, and detects the approximate temperature abnormality area through the corrosion and expansion in the morphological gradient, and then detects the peak of the temperature abnormality point through the Top-Hat transformation. Determine the location of abnormal temperature.

The peak width identification method based on morphological gradient simulates the abnormal temperature along the cable. The simulation result is shown in Figure 6. The temperature measurement control device 3 inputs the temperature curve along the cable (above), and the output is based on the morphological gradient Schematic diagram of abnormal temperature points obtained by the method of identifying the peak width of the wave (below). Each peak on the temperature curve corresponds to a gradient combination of a positive narrow peak and a negative narrow peak. Therefore, the position of the local quench (temperature abnormal point) can be determined by the positive and negative narrow peak pair of the morphological gradient, and the position of the local quench (temperature abnormal point) can be determined according to the positive and negative narrow peak. The distance between the peaks of the peak pair estimates the width of the quench zone.

More specifically, the optical fiber temperature measurement host 11 used in the high temperature superconducting cable temperature measurement system of the present invention can be a DTS optical fiber temperature measurement host 1N4385B, the computer interface has USB and Ethernet (LAN), and the communication protocol supports SCPI and Modbus. TCP/IP (option -060); the thermal resistance temperature monitor 22 uses Keithley 3700 series digital multimeter, its host can support up to 576 two-wire multiplexer channels, and can simultaneously connect to multiple PT platinum resistance sensors for measurement Signal; the composite temperature measurement component composed of the optical fiber temperature measurement host 11 and the thermal resistance temperature monitor 22 outputs the temperature signal to the temperature measurement control device 3. The system is based on the Labview program development software to combine the optical fiber temperature measurement and the thermal resistance 5 temperature measurement, and The measurement and determination platform is built, which is equivalent to a virtual instrument platform, which greatly improves the integration of data information, provides a good human-computer interaction interface, and increases the flexibility of the system.

Implementing the embodiments of the present invention has the following beneficial effects:

The high-temperature superconducting cable temperature measurement system provided by the present invention is based on the combined use of traditional temperature sensors (thermal resistance) and optical fiber temperature measurement technology. The optical fiber is installed in the superconducting cable in advance when the superconducting cable is made, and the thermal The resistor is arranged at the terminal of the superconducting cable (terminal cooling system) to form a composite temperature measuring component of optical fiber temperature measurement and thermal resistance temperature measurement to measure the temperature along the high-temperature superconducting cable and the temperature of the terminal cooling system. The system can accurately grasp the temperature distribution along the high-temperature superconducting cable in real time, so as to control the transmission current of the cable or control the superconducting cable protection device according to the operating temperature of the superconducting cable; it can detect the cable operation defects related to thermal disturbance in time, and Send an alarm signal to ensure the safe operation of the high-temperature superconducting cable; propose a method to accurately locate the abnormal temperature along the high-temperature superconducting cable by the position of the positive and negative narrow peak pairs of the morphological gradient, which is convenient for the troubleshooting of the superconducting cable during maintenance and detection. Reduce the scope of the fault and reduce the troubleshooting time.

The high-temperature superconducting cable temperature measurement system provided by the present invention can be applied to the temperature measurement and monitoring protection of high-temperature superconducting cables in power grids. Depending on the structure of the high-temperature superconducting cable, it can cover high, medium and low voltage levels. High stability and reliability.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply one of these entities or operations. There is any such actual relationship or order between. Moreover, the terms "include", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes those that are not explicitly listed Other elements of, or also include elements inherent to this process, method, article or equipment. If there are no more restrictions, the element defined by the sentence "including a..." does not exclude the existence of other same elements in the process, method, article, or equipment that includes the element.

The above are only specific implementations of this application. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of this application, several improvements and modifications can be made. These improvements and modifications are also Should be regarded as the scope of protection of this application.

Claims (10)

A high-temperature superconducting cable temperature measurement system, which is used in interconnected high-temperature superconducting cables and terminal cooling systems, including: A low-temperature temperature measuring optical fiber arranged in the high-temperature superconducting cable, and a thermal resistor arranged in the terminal cooling system; The optical fiber temperature measurement host is used to receive temperature measurement information from various measurement points of the low temperature temperature measurement optical fiber; Thermal resistance temperature monitor, used to receive temperature information from thermal resistance; The temperature measurement control device is connected to the optical fiber temperature measurement host and the thermal resistance temperature monitor, receives the temperature measurement information and temperature information, and performs evaluation and judgment based on the temperature measurement information and temperature information to determine the The cable operation controls the protection action and protection area of the host, and the cable operation control host operates the corresponding converter system or circuit breaker according to the protection action and the protection area. A high-temperature superconducting cable temperature measurement system according to claim 1, wherein the optical fiber temperature measurement host further comprises: The collection information receiving unit is used to separately collect the Stokes light and the anti-Stokes light scattered at each temperature measurement point of the low temperature temperature measurement fiber; The first calculation unit is used to calculate the Stokes light and the anti-Stokes light at each temperature measurement point to obtain the temperature of the temperature measurement point. The calculation formula is as follows:

Formula, I _AS to the anti-Stokes light intensity; I _S Stokes light intensity; H is Planck's constant; Blue K is Boltzmann's constant; V is the frequency of the laser; v _i is the frequency of vibration ; T is the absolute temperature; after laser source is determined, v is a constant; v _i is determined by the fiber material, the fiber is determined, which is a constant; The position measuring unit is used to position each temperature measurement point of the low temperature temperature measurement optical fiber based on optical time domain reflectometry (OTDR) technology, and obtain position information of each temperature measurement point. A high-temperature superconducting cable temperature measurement system according to claim 2, wherein the thermal resistance is a T100 temperature sensor. A high-temperature superconducting cable temperature measurement system according to claim 3, wherein the temperature measurement system comprises: The signal receiving and processing unit is used to obtain the temperature T along the cable, the average value T _{av of the} temperature along the cable and the cooling system temperature T _c after the temperature measurement control device 3 receives the temperature signal, The protection action determination unit is used to combine the value obtained by the signal receiving and processing unit with the preset cable temperature alarm value T _l , the maximum allowable cable temperature T _max , the lower threshold value of the cable average temperature T _L , and the higher average cable temperature The threshold value T _H is compared with the maximum allowable temperature T _{cH of the} cooling system to determine the protection action of the cable operation control host; The protection area determination unit is used to obtain the temperature curve along the cable after obtaining the value, and obtain the schematic diagram of the temperature abnormal point obtained by the morphological gradient-based wave crest width identification method through simulation, and the temperature abnormality point diagram is positive The relative position of the negative narrow peak pair is used to determine the position of the abnormal temperature point on the cable, thereby determining the protection area; The protection information sending unit is used to send the protection action and protection area information to the cable operation control host connected to it. A high-temperature superconducting cable temperature measurement system according to claim 4, wherein the protection action determination unit determines the protection action by the following strategy: When the comparison result is (T>T _l )∨(T _av >T _L ), the generated protection action is an alarm command. When the cable operation control host receives the alarm command and protection zone information, it controls the protection described in the converter system High-temperature superconducting cable power transmission in the region; When comparison result _{(T> T max) ∨ (} T av> T H) ∨ (T c> T cH), protective action is generated a trip command, the control cable running in the host to pick up the trip command and the protected area When the information is available, control the circuit breaker to timely cut off the faulty high-temperature superconducting cable in the protection area from the power grid. A high-temperature superconducting cable temperature measurement system according to any one of claims 1 to 5, wherein the high-temperature superconducting cable includes from outside to inside: a cryostat, a shielding layer, and at least one insulating layer And the phase conductor, and the cable skeleton; between the cryostat and the shielding layer and in the cable skeleton are filled with liquid nitrogen, wherein, The high temperature superconducting cable is further equipped with a low temperature resistant temperature measuring optical fiber, and the low temperature resistant temperature measuring optical fiber is installed at least in one of the following three positions: the outer surface of the shielding layer, the outermost insulating layer and the outermost layer Between the phase conductors and the inner surface of the cable skeleton. A high-temperature superconducting cable temperature measurement system according to claim 6, wherein the low-temperature temperature measurement optical fiber adopts a quartz-based multi-mode optical fiber, and is coated around the fiber cladding in a manner that the cross-section of the optical fiber is concentric circles. Covering material is applied, or a non-metal tightly wrapped sleeve is sheathed; the non-metal tightly wrapped sleeve is selected from fiber-reinforced composite plastic sleeve, PBT loose sleeve, and fenlon kevlar sleeve. The high-temperature superconducting cable temperature measurement system according to claim 7, wherein the low-temperature resistant optical fiber adopts a linear laying or an S-shaped laying method. A high-temperature superconducting cable temperature measurement system according to claim 8, wherein the cryostat 12 is made of double-layer stainless steel welding with a vacuum interlayer, and the vacuum interlayer of the double-layer stainless steel is provided with Layer insulation materials and activated carbon; The shielding layer is a copper shielding layer, and its single end or double ends are grounded; The insulating layer is made of polypropylene laminated paper, aromatic polyamide paper or polyimide material; The phase conductor is the second-generation high-temperature superconducting tape YBCO, the width of which is ≥5mm, the thickness of which is required to be ≈0.3mm, and the copper layer is plated as a stable layer; The cable skeleton is a metal corrugated pipe covered with a dense metal mesh, which is a reference support for the superconducting tape to be wound, and is also used for liquid nitrogen circulation pipelines. A high-temperature superconducting cable temperature measurement system according to claim 9, wherein the high-temperature superconducting cable is a three-phase independent superconducting cable structure, a three-phase parallel-axis superconducting cable structure, or a three-phase coaxial superconducting cable structure .

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