CN112467692B - Cable protection system and method based on temperature change waveform along cable - Google Patents
Cable protection system and method based on temperature change waveform along cable Download PDFInfo
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- CN112467692B CN112467692B CN202011386143.2A CN202011386143A CN112467692B CN 112467692 B CN112467692 B CN 112467692B CN 202011386143 A CN202011386143 A CN 202011386143A CN 112467692 B CN112467692 B CN 112467692B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/001—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for superconducting apparatus, e.g. coils, lines, machines
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Abstract
The invention provides a cable protection system and a method thereof based on a temperature change waveform along a cable, wherein the system comprises: the temperature measuring optical fiber is used for measuring the temperature along the line of the high-temperature superconducting cable; the monitoring system comprises a data receiving unit, a waveform characteristic obtaining unit and an instruction generating unit, wherein the data receiving unit is used for receiving the temperature along the line detected by the temperature measuring optical fiber; the waveform characteristic acquisition unit is used for acquiring a waveform characteristic diagram of temperature variation along the line of the superconducting cable according to the temperature along the line; the instruction generating unit is used for determining whether to generate a cutting instruction or an alarm instruction according to the temperature change waveform characteristic diagram, and issuing the cutting instruction to the protection device or issuing the alarm instruction to the alarm; the alarm is used for responding to the received alarm instruction and carrying out quench alarm on the high-temperature superconducting cable; the protection device is used for cutting off the high-temperature superconducting cable in response to receiving the cutting instruction. The invention can improve the accuracy of judging the cable quench according to the temperature parameter of the high-temperature superconducting cable.
Description
Technical Field
The invention relates to the technical field of high-temperature superconducting cables, in particular to a cable protection system and method based on a waveform of temperature change along a cable.
Background
As the density of the electrical loads increases, the load of the power cable continues to rise. The super-strong load capacity of the superconducting cable is a solution for guaranteeing long-time power supply under high load. The first kilometer level superconducting cable is built in China, and the construction application and operation and maintenance management technology of the superconducting cable are becoming mature.
The factors for causing the quench fault of the superconducting cable are more, and the factors mainly comprise cooling system faults, superconducting cable body anomalies, power system short-circuit faults and the like. The temperature of the high-temperature superconducting cable body is an important criterion for judging the abnormality of the high-temperature superconducting cable body, a thermocouple or a thermal resistor is mainly adopted for temperature detection at present, and when the detected temperature is greater than a set threshold value, the abnormality of the superconducting cable body is judged, and the superconducting cable is cut and protected.
Temperature sensors of conventional thermocouples or thermal resistors are used for point measurement, for example, a PT100 platinum resistance sensor is used for measuring the temperature distribution of a 500m long cable, if one sensor is arranged every 1 meter, 500 sensor probes are required to be installed inside the cable, and each sensor needs 4 signal wires, so that 2000 signal wires are required, and each signal wire needs to be connected to a measurement and control monitoring system along the cable. More sensors and signal lines are required to obtain a more accurate temperature profile. Such a large number of signal lines can present great difficulties in wiring, outgoing lines and cable fabrication, as well as adversely affecting the structure of the superconducting cable itself and its insulation properties, which is not possible in engineering practice applications.
In addition, the high-temperature superconducting cable generally operates under the condition of high voltage and high current, and the temperature sensor of the traditional thermocouple or thermal resistor is greatly affected by electromagnetic interference and can influence the accuracy of a measurement result; therefore, misjudgment is easily generated, and thus the superconducting cable is cut off by misoperations.
Disclosure of Invention
The invention aims to provide a cable protection system and a method based on a waveform of temperature change along a cable so as to improve the accuracy of judging cable quench according to the temperature of a high-temperature superconducting cable.
Therefore, according to a first aspect, an embodiment of the present invention provides a cable protection system based on a waveform of temperature change along a cable, where the system includes a monitoring system, and a temperature measuring optical fiber, an alarm, and a protection device electrically connected to the monitoring system;
the temperature measuring optical fiber is used for measuring the temperature along the line of the high-temperature superconducting cable and sending the measured temperature along the line to the monitoring system;
the monitoring system comprises a data receiving unit, a waveform characteristic obtaining unit and an instruction generating unit, wherein the data receiving unit is used for receiving the temperature along the line detected by the temperature measuring optical fiber and forwarding the temperature along the line to the waveform characteristic obtaining unit; the waveform characteristic acquisition unit is used for acquiring a waveform characteristic diagram of temperature variation along the superconducting cable according to the temperature along the line and outputting the waveform characteristic diagram to the instruction generation unit; the instruction generating unit is used for determining whether to generate a cutting instruction or an alarm instruction according to the temperature change waveform characteristic diagram, and issuing the cutting instruction to a protection device or issuing the alarm instruction to an alarm;
the alarm is used for responding to the alarm instruction to perform high-temperature superconducting cable quench alarm;
the protection device is used for responding to the receiving of the cutting instruction and cutting off the high-temperature superconducting cable.
Optionally, the waveform characteristic acquisition unit is specifically configured to: performing multi-resolution morphological gradient transformation according to the temperature along the line to obtain a waveform characteristic diagram of the temperature change;
the instruction generation unit is specifically configured to: determining the position and the width of one or more local quench areas according to the temperature change waveform characteristic diagram, and determining whether to generate a cutting instruction or an alarm instruction according to the width of the one or more local quench areas; the region between any adjacent positive narrow peak and negative narrow peak in the temperature change waveform characteristic diagram is a local quench region.
Optionally, the instruction generating unit is specifically configured to:
when the width of any local quench zone satisfies d i >r L Or a plurality of local quench regions, satisfy the widthGenerating an alarm instruction;
when the width of any local quench zone satisfies d i >r H Or a plurality of local quench regions, satisfy the widthWhen the cutting instruction is generated;
wherein d i The width of the ith local quench zone, l is the length of the high-temperature superconductive cable, r L ，r H ，r L-av ，r H-av Respectively preset thresholds.
Optionally, the system further comprises:
the notification unit is used for responding to the instruction generation unit to generate a cutting instruction or an alarm instruction, generating corresponding notification information and sending the notification information to a mobile phone of a preset operation and maintenance person; wherein the notification information includes location information of one or more local quench areas, and ablation instruction or alert instruction information.
Optionally, the superconducting cable is a three-phase coaxial superconducting cable, and the three-phase coaxial superconducting cable is sequentially provided with a cable framework, a first insulating layer, an A-phase conductor layer, a second insulating layer, a B-phase conductor layer, a third insulating layer, a C-phase conductor layer, a fourth insulating layer, a shielding layer and a thermostat from inside to outside, wherein cavities are arranged inside the cable framework, between the thermostat and the shielding layer, and the cavities are used for liquid nitrogen circulation to cool the superconducting cable; the number of the temperature measuring optical fibers is multiple, the temperature measuring optical fibers are arranged between any two layers or in any one layer of the cable skeleton, the A-phase conductor layer, the first insulating layer, the B-phase conductor layer, the second insulating layer, the C-phase conductor layer, the third insulating layer and the shielding layer, and the temperature measuring optical fibers are uniformly arranged;
the data receiving unit is specifically configured to: receiving the temperatures along the line detected by the plurality of temperature measuring optical fibers, and sending the temperatures along the line detected by the plurality of temperature measuring optical fibers to the waveform characteristic acquisition unit according to the temperatures along the line detected by the plurality of temperature measuring optical fibers;
the waveform characteristic acquisition unit is specifically configured to: obtaining a plurality of corresponding temperature change waveform characteristic diagrams according to the temperatures along the line detected by the plurality of temperature measuring optical fibers, and superposing waveforms of the plurality of temperature change waveform characteristic diagrams to obtain a temperature change waveform characteristic diagram of the high-temperature superconducting cable along the line, or carrying out weighted summation on waveforms of the plurality of temperature change waveform characteristic diagrams to obtain a temperature change waveform characteristic diagram of the high-temperature superconducting cable along the line.
Optionally, the plurality of temperature measuring optical fibers are spirally wound or embedded in the groove of the cable skeleton along the outer surface of the cable skeleton.
Optionally, the A phase conductor layer, the B phase conductor layer and the C phase conductor layer sequentially comprise a first layer of superconducting tape, a carbon paper layer and a second layer of superconducting tape from inside to outside respectively; the plurality of temperature measuring optical fibers are arranged in gaps among strips of the first layer of superconducting strips of the B-phase conductor layer.
Optionally, the diameters of the plurality of temperature measurement optical fibers are smaller than the thickness of the first layer of superconducting tapes, gaps among the tapes of the first layer of superconducting tapes are filled with polyimide resin, and the polyimide resin is used for adhering and fixing the plurality of temperature measurement optical fibers and enhancing the mechanical strength of the plurality of temperature measurement optical fibers.
Optionally, the plurality of temperature measuring optical fibers are arranged between the fourth insulating layer and the shielding layer, and the laying mode adopts spiral winding or linear laying.
According to a second aspect, an embodiment of the present invention proposes a cable protection method based on a waveform of a temperature change along a cable, which is implemented based on the cable protection system according to the first aspect, the method comprising the steps of:
the temperature measuring optical fiber measures the temperature along the line of the high-temperature superconducting cable and sends the measured temperature along the line to the monitoring system;
the data receiving unit of the monitoring system receives the temperature along the line detected by the temperature measuring optical fiber and forwards the temperature to the waveform characteristic acquisition unit;
the waveform characteristic acquisition unit is used for responding to the received temperature along the line, acquiring a waveform characteristic diagram of temperature variation along the superconducting cable according to the temperature along the line and outputting the waveform characteristic diagram to the instruction generation unit;
the instruction generating unit is used for responding to the received temperature change waveform characteristic diagram, determining whether to generate a cutting instruction or an alarm instruction according to the temperature change waveform characteristic diagram, and issuing the cutting instruction to a protection device or issuing the alarm instruction to an alarm;
the alarm responds to the receiving of the alarm instruction to perform the quench alarm of the high-temperature superconducting cable;
and the protection device is used for cutting off the high-temperature superconducting cable in response to receiving the cutting instruction.
The embodiment of the invention provides a cable protection system and a method based on a temperature change waveform along a cable, which can more accurately identify local quench faults according to the peak position and the peak width of an axial temperature distribution curve of a superconducting cable, can reflect various quench faults, and can realize quench region positioning; compared with the prior art, the embodiment of the invention improves the overall performance of the temperature-based quench protection of the superconducting cable.
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 invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a cable protection system based on a waveform of temperature variation along a cable according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a multi-resolution morphological gradient transformation according to an embodiment of the invention.
FIG. 3 is a schematic diagram of another embodiment of a monitoring and protecting system for high temperature superconductive cable.
FIG. 4 is a schematic diagram showing an arrangement of the temperature measuring optical fiber according to the first example of the embodiment of the present invention.
FIG. 5 is a schematic diagram showing an arrangement of a temperature measuring optical fiber according to a second example of the embodiment of the present invention.
FIG. 6 is a schematic diagram showing a specific arrangement of the temperature measuring optical fiber according to a second example of the embodiment of the present invention.
FIG. 7 is a schematic diagram showing another embodiment of the temperature measuring optical fiber according to the second example of the present invention.
FIG. 8 is a schematic diagram illustrating an arrangement of a temperature measuring optical fiber according to a third example of the embodiment of the present invention.
FIG. 9 is a flow chart of a method for monitoring and protecting a high temperature superconductive cable according to an embodiment of the present invention.
The marks in the figure:
the system comprises a 1-monitoring system, a 11-data receiving unit, a 12-waveform characteristic acquisition unit, a 13-instruction generation unit and a 14-notification unit; 2-temperature measuring optical fiber; 3-an alarm; 4-protection device.
Detailed Description
Various exemplary embodiments, features and aspects of the disclosure will be described in detail below with reference to the drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
In addition, numerous specific details are set forth in the following examples in order to provide a better illustration of the 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 in order to not obscure the present invention.
Referring to fig. 1, an embodiment of the present invention proposes a cable protection system based on a waveform of temperature variation along a cable, where the system includes a monitoring system 1, and a temperature measuring optical fiber 2, an alarm 3, and a protection device 4 electrically connected to the monitoring system 1;
the temperature measuring optical fiber 2 is used for measuring the temperature along the high-temperature superconducting cable and sending the measured temperature along the high-temperature superconducting cable to the monitoring system 1; the temperature along the line includes a temperature value at any point along the superconducting cable.
Wherein the monitoring system 1 comprises a data receiving unit 11, a waveform characteristic acquisition unit 12 and an instruction generation unit 13;
the data receiving unit 11 is configured to receive the line temperature detected by the temperature measuring optical fiber 2, and forward the line temperature to the waveform characteristic obtaining unit 12;
the waveform characteristic acquisition unit 12 is used for acquiring a waveform characteristic diagram of temperature variation along the superconducting cable according to the temperature along the line and outputting the waveform characteristic diagram to the instruction generation unit 13;
the instruction generating unit 13 is configured to determine whether to generate a cutting instruction or an alarm instruction according to the temperature change waveform feature map, and issue the cutting instruction to the protection device 4 or issue the alarm instruction to the alarm 3.
The alarm device 3 is used for responding to the alarm instruction to perform high-temperature superconducting cable quench alarm;
specifically, the alarm mode of the alarm device 3 may be a voice alarm, an indicator light alarm or a combination of the two.
Wherein the protection device 4 is used for cutting off the high-temperature superconducting cable in response to receiving the cutting instruction;
specifically, the protection device 4 outputs a breaker trip signal to the breaker of the high-temperature superconducting cable according to the cutting instruction, controls the breaker to trip, and cuts off the high-temperature superconducting cable.
Specifically, the temperature measuring optical fiber 2 not only uses the optical fiber as a light transmission channel, but also uses the optical fiber as a temperature sensing element, so that a large number of probes are not required to be arranged, the installation is convenient, the wiring is simple, and the occupied space is small. Besides the common advantages of the optical fiber sensor, the temperature measuring optical fiber 2 can also realize continuous measurement in the space area along the optical fiber so as to obtain temperature values of all places, and the distributed optical fiber temperature measurement can position the distance by utilizing an optical time domain reflection technology (Optical Time Domain Reflection is called OTDR for short), so that the difficult problem that other temperature sensors are difficult to be qualified in many special occasions is solved.
In some embodiments, the waveform characteristics acquisition unit 12 is specifically configured to: performing multi-resolution morphological gradient transformation according to the temperature along the line to obtain a waveform characteristic diagram of the temperature change;
specifically, mathematical morphology is applied to many aspects of an electric power system as a novel signal analysis means, and is based on a structural element filling transformation method, and expansion and corrosion are the most basic 2 morphological transformations, so that concepts such as morphological opening and closing operation, morphological gradient and the like are defined. Let f (x) and g (x) respectively represent a one-dimensional input signal and a structural element, let D f E (E is European space) and D g />E is the set of domains for these 2 functions, respectively. The expansion and corrosion of the structural element g on the signal f are defined as:
defining the Morphological Gradient (MG) as:
MG is commonly used to detect edges, so that abrupt features in the signal can be extracted. Recently, a multi-resolution morphological gradient transform (MMG) has been proposed, in which 2 flat structural elements with variable lengths and different origin positions (i.e., the amplitude of each element is 0) are designed for extracting the rising edge and the falling edge in the signal:
wherein: the structural elements g+ and g-are used for extracting the upper edge and the lower edge in the waveform respectively; structural element width l=2 1-α l 1 Alpha is the analysis layer number of MMG, l 1 Initial width at layer 1 for the structural element; the underlined mark points g in g+ and g-represent their origin positions, respectively. Defining gray-value multi-resolution morphological gradients using the concepts of MG and variable flattened structural elementsThe method comprises the following steps:
when α=1, ρ 0 =f is the input signal.
According to the definition of the Multiresolution Morphological Gradient (MMG), a layer of multiresolution morphological gradient transformation is carried out on temperature data along the line of the superconducting cable, and the transformation result is shown in figure 2.
Wherein the instruction generating unit 13 is specifically configured to: determining the position and the width of one or more local quench areas according to the temperature change waveform characteristic diagram, and determining whether to generate a cutting instruction or an alarm instruction according to the width of the one or more local quench areas; the region between any adjacent positive narrow peak and negative narrow peak in the temperature change waveform characteristic diagram is a local quench region.
Specifically, referring to fig. 2, comparing the temperature curve along the line with the multi-resolution morphological gradient transformation results, it can be found that a combination of a positive narrow peak and a negative narrow peak can be obtained after the multi-resolution morphological gradient transformation of the peaks along the temperature curve, and the non-peak area on the temperature curve is almost zero after transformation, so that the position of local quench on the superconducting cable can be determined by the positive and negative narrow peak pairs of the multi-resolution morphological gradient transformation results, and the width of the quench area can be estimated according to the distance between the peaks of the positive and negative narrow peak pairs.
In some embodiments, the instruction generating unit 13 is specifically configured to:
when the width of any local quench zone satisfies d i >r L Or a plurality of local quench regions, satisfy the widthGenerating an alarm instruction;
when the width of any local quench zone satisfies d i >r H Or a plurality of local quench regions, satisfy the widthWhen the cutting instruction is generated;
wherein d i The width of the ith local quench zone, l is the length of the high-temperature superconductive cable, r L ，r H ，r L-av ，r H-av The threshold values are preset respectively, and are a low threshold value and a high threshold value of the maximum quench width along the line, and a low threshold value and a high threshold value of the total quench width ratio in sequence.
Specifically, when the superconducting cable is subjected to local quench timeout, a great amount of joule heat can be accumulated in the quench area, so that the temperature of the quench area is rapidly increased, and the temperature of the non-quench area is slowly changed, so that a peak is formed in the quench area by the superconducting cable axial temperature distribution curve, and the peak is an important basis for distinguishing local quench from normal operation and overall quench. The peak width of the axial temperature distribution curve (the sum of the widths of all peaks on the curve) reflects the size of the quench area, namely the severity of local quench, so that the local quench fault can be identified more accurately according to the peak position and the peak width of the axial temperature distribution curve of the superconducting cable, and the overall performance of quench protection is further improved.
Specifically, the instruction generating unit 13 is configured to generate, in response to receiving a determination result of the first determining unit, the second determining unit, or the third determining unit, a corresponding alarm instruction according to the determination result, where alarm contents are different, and specific alarm instruction contents are different, and the alarm 3 performs different types of alarms according to different alarm instructions, for example, using different color indicator lamps, also using different frequency audible alarms, and so on.
In some embodiments, referring to fig. 3, the system further comprises:
a notification unit 14, configured to generate a cutting instruction or an alarm instruction in response to the instruction generation unit 13, generate corresponding notification information, and send the notification information to a mobile phone of a preset operation and maintenance person; wherein the notification information includes location information of one or more local quench areas, and ablation instruction or alert instruction information.
In some embodiments, the superconducting cable is a three-phase coaxial superconducting cable, and a cable skeleton, a first insulating layer, an A-phase conductor layer, a second insulating layer, a B-phase conductor layer, a third insulating layer, a C-phase conductor layer, a fourth insulating layer, a shielding layer and a thermostat are sequentially arranged on the three-phase coaxial superconducting cable from inside to outside, wherein cavities are arranged inside the cable skeleton and between the thermostat and the shielding layer, and are used for liquid nitrogen circulation to cool the superconducting cable; the number of the temperature measuring optical fibers 2 is multiple, the temperature measuring optical fibers 2 are arranged between any two layers or in any one layer of the cable skeleton, the A-phase conductor layer, the first insulating layer, the B-phase conductor layer, the second insulating layer, the C-phase conductor layer, the third insulating layer and the shielding layer, and the temperature measuring optical fibers 2 are uniformly arranged;
the data receiving unit 11 is specifically configured to: receiving the temperatures along the line detected by the plurality of temperature measuring optical fibers 2, and sending the temperatures along the line detected by the plurality of temperature measuring optical fibers 2 to the waveform characteristic acquisition unit 12;
the waveform characteristic acquisition unit 12 specifically functions to: and obtaining a plurality of corresponding temperature change waveform characteristic diagrams according to the temperatures along the line detected by the plurality of temperature measuring optical fibers 2, and superposing waveforms of the plurality of temperature change waveform characteristic diagrams to obtain a temperature change waveform characteristic diagram of the high-temperature superconducting cable along the line, or carrying out weighted summation on waveforms of the plurality of temperature change waveform characteristic diagrams to obtain the temperature change waveform characteristic diagram of the high-temperature superconducting cable along the line.
Specifically, for each temperature measuring fiber 2, a certain measurement error inevitably exists, and the temperature measurement results of the plurality of temperature measuring fibers 2 for the same target object may deviate, so in this embodiment, the temperature measuring test is performed on the plurality of temperature measuring fibers 2 in advance, the deviation of the plurality of temperature measuring fibers 2 is determined, and a weight coefficient is given according to the deviation condition, and waveforms and weight coefficients corresponding to the plurality of temperatures along the line measured by the plurality of temperature measuring fibers 2 obtain a temperature variation waveform characteristic diagram of the real temperatures along the line of the superconducting cable.
The thickness of the three-phase coaxial superconducting cable strip is about 0.3mm, the number of the strip layers is two, and the thickness of the insulating layer is about 1.5 mm. Considering the optical fiber winding, fixing, mechanical strength, and influence on the superconducting cable conductor layer winding and electric field, it is preferable that the present embodiment gives the following three specific optical fiber layout examples.
In the first example, as shown in fig. 4, the number of the plurality of temperature measuring optical fibers 2 is 3, and the angular intervals between the 3 temperature measuring optical fibers 2 are 120 degrees, so as to increase the reliability of the optical fiber temperature measurement and detect the position of the abnormal temperature point in time; the 3 temperature measuring optical fibers 2 are spirally wound or embedded in the grooves of the cable frame along the outer surface of the cable frame.
Specifically, two 0.5mm nonmetallic bushings tightly wrap the double-core optical fibers to be spirally wound along a cable skeleton, and an insulating layer is wound on the cable skeleton, and then an A-phase conductor is wound; if the corrugated pipe has a spiral pitch and the distance is far, the optical fiber is optimally arranged in the groove on the framework. The embedded schematic diagram is shown in fig. 4.
In this example, 3 fibers can directly detect the temperature distribution of the a-phase conductor, and if a hot spot occurs on the B, C-phase conductor, the heat transfer is detected radially by the cable. The optical fiber and the cable conductor layer are convenient to wind, and the influence on cable insulation is small.
In a second example, referring to fig. 5, the number of the plurality of temperature measuring optical fibers 2 is 4, and the angle between the 4 temperature measuring optical fibers 2 is 90 ° so as to increase the reliability of the optical fiber temperature measurement and detect the position of the abnormal temperature point in time; the A-phase conductor layer, the B-phase conductor layer and the C-phase conductor layer sequentially comprise a first layer of superconducting tape, a carbon paper layer and a second layer of superconducting tape from inside to outside respectively; the 4 temperature measuring optical fibers 2 are arranged in gaps among strips of the first layer of superconducting strips of the B-phase conductor layer.
Specifically, in this example, 4 bare optical fibers of 0.165mm or nonmetallic jacketed optical fibers of 0.5mm were installed in the gaps between the B-phase superconducting tapes, and the layout thereof is schematically shown in FIG. 5.
Since the B phase conductor is located between the a phase and the C phase, the heat dissipation condition is relatively poor with respect to the A, C two phase conductor, and heat accumulation relatively more easily occurs. In addition, the three-phase coaxial superconducting cable has compact structure and small volume, so that the optical fiber is embedded in a gap between the superconducting tapes of the same layer of B phase, the temperature distribution of the B phase can be directly detected, and the temperature change condition of A, C two phases can be timely detected.
In order to ensure that the local temperature change on the phase conductor layer can be detected in time, 4 bare optical fibers with the thickness of 0.165mm or nonmetallic casing tightly wrapping optical fibers with the thickness of 0.5mm are arranged on the phase B, and the angle interval of each optical fiber is 90 degrees. Since the thickness of the superconducting tape used for the phase conductors is about 0.3mm, the number of layers of each phase tape is 2, and the pre-burying of the 0.165mm bare optical fiber and the 0.5mm tightly-packed optical fiber is different, for example, the differences are shown in fig. 6 and 7.
The 0.165mm bare optical fiber is smaller than the thickness of the superconducting tapes, can be directly placed in a gap between the two superconducting tapes, and is filled with an adhesive, such as polyimide resin, so that on one hand, the optical fiber can be fixed, on the other hand, the mechanical strength of the optical fiber can be enhanced, and the influence of the optical fiber protrusion on cable insulation can be reduced as much as possible.
The size of the tightly packed optical fiber with the thickness of 0.5mm is larger than that of the superconducting tape, but the diameter of the internal bare optical fiber is 0.165mm, the extrusion resistance of the tightly packed outer sleeve is high, after the optical fiber is pre-buried into a gap between the first layer of tapes, the tightly packed outer sleeve of the optical fiber can be extruded through carbon paper and an insulating layer when the second layer of tapes are paved, so that the bulge of the pre-buried position of the optical fiber caused by the fact that the size of the optical fiber is larger than that of the tapes is avoided.
In the example, the temperature measuring optical fiber 2 can directly monitor the temperature of the B-phase conductor, can timely detect the position of thermal disturbance or abnormal temperature point on the B-phase conductor, and can monitor the temperature of the A, C-phase conductor through inter-phase heat transfer. The shortcoming is that the strength of the 0.165mm bare fiber is low, and for the superconducting cable with the length of 400m, the breakage probability of the 0.165mm bare fiber in the pre-buried process is high, so that the cable cannot be directly used in a long-distance superconducting cable, and is suitable for a short-distance superconducting cable. The 0.5mm tight-sleeved optical fiber has larger size relative to the thickness of the superconducting tape (about 0.3 mm), can cause certain influence on the cable structure, and has large embedding difficulty, so that the scheme of the 0.5mm tight-sleeved optical fiber is suitable for the scene of thicker superconducting tape thickness, and can properly increase the superconducting tape thickness.
In a third example, the number of the plurality of temperature measuring optical fibers 2 is 3, and the angular intervals among the 3 temperature measuring optical fibers 2 are 120 degrees, so that the reliability of optical fiber temperature measurement is improved, and the positions of abnormal temperature points are detected in time; the 3 temperature measuring optical fibers 2 are arranged between the fourth insulating layer and the shielding layer, and the laying mode adopts spiral winding or linear laying.
Specifically, in this example, a 0.5mm tightly-packed optical fiber is pre-buried between a C-phase insulating layer and a shielding layer, and the laying mode is spiral winding or linear laying, and the pre-buried schematic is shown in fig. 8. In the example, the influence of the pre-embedding of the optical fiber on the cable structure and the insulation performance is small, the difficulty of pre-embedding of the optical fiber is small, and the implementation is easy.
Table 1 comparison of three fiber lay-out examples
In summary, the first example has lower installation difficulty and less influence on the cable structure; the defect is that the temperature distribution of the single A phase or C phase conductor can be monitored, and the temperature measurement effect on the other two phases is poor. In the second example, the optical fiber is directly arranged in a gap between the B-phase conductors, so that the temperature distribution of the B-phase conductors can be directly monitored, and meanwhile, the temperature of the A, C phase can be monitored through inter-phase heat transfer due to the fact that the optical fiber is positioned in an intermediate phase; the defects are that the optical fiber has low strength and is easy to break, the optical fiber is difficult to embed, and the insulation of the cable is also adversely affected; and A, C phase temperature is monitored through inter-phase heat transfer, so that the temperature measurement effect is not ideal. The three examples each have advantages and disadvantages and can be redetermined specifically in combination with specific application conditions (e.g., cable length, superconducting tape thickness, etc.) and three-phase conductor temperatures of the three-phase coaxial cable A, B, C.
Referring to fig. 9, another embodiment of the present invention provides a cable protection method based on a waveform of temperature variation along a cable, which is implemented based on the cable protection system described in the foregoing embodiment, and the method includes the following steps:
s1, measuring the temperature along the high-temperature superconducting cable by using a temperature measuring optical fiber, and transmitting the measured temperature along the high-temperature superconducting cable to a monitoring system;
s2, a data receiving unit of the monitoring system receives the temperature along the line detected by the temperature measuring optical fiber and forwards the temperature to a waveform characteristic obtaining unit;
step S3, a waveform characteristic obtaining unit responds to the received temperature along the line, obtains a waveform characteristic diagram of temperature variation along the superconducting cable according to the temperature along the line, and outputs the waveform characteristic diagram to an instruction generating unit;
step S4, the instruction generating unit responds to the received temperature change waveform characteristic diagram, determines whether to generate a cutting instruction or an alarm instruction according to the temperature change waveform characteristic diagram, and sends the cutting instruction to a protection device or sends the alarm instruction to an alarm;
s5, responding to the alarm instruction by the alarm device, and carrying out quench alarm on the high-temperature superconducting cable;
and S6, the protection device responds to the receiving of the cutting instruction to cut off the high-temperature superconducting cable.
Preferably, the method further comprises:
step S7, a notification unit responds to the instruction generation unit to generate a cutting instruction or an alarm instruction, generates corresponding notification information and sends the notification information to a mobile phone of a preset operation and maintenance person; wherein the notification information includes location information of one or more local quench areas, and ablation instruction or alert instruction information.
It should be noted that, the method of this embodiment corresponds to the system of the above embodiment, so the specific step flows of the steps S1 to S7 can be obtained by referring to the system of the above embodiment, and will not be described herein again.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or 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 various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the technical improvements in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (3)
1. The cable protection system based on the waveform of temperature change along the cable is characterized by comprising a monitoring system, a plurality of temperature measuring optical fibers, an alarm, a protection device and a notification unit, wherein the temperature measuring optical fibers, the alarm, the protection device and the notification unit are electrically connected with the monitoring system;
the superconducting cable is a three-phase coaxial superconducting cable, and the three-phase coaxial superconducting cable is sequentially provided with a cable framework, a first insulating layer, an A-phase conductor layer, a second insulating layer, a B-phase conductor layer, a third insulating layer, a C-phase conductor layer, a fourth insulating layer, a shielding layer and a thermostat from inside to outside, wherein cavities are formed inside the cable framework, between the thermostat and the shielding layer, and the cavities are used for liquid nitrogen to circulate so as to cool the superconducting cable; the plurality of temperature measuring optical fibers are uniformly arranged; the A-phase conductor layer, the B-phase conductor layer and the C-phase conductor layer sequentially comprise a first layer of superconducting tape, a carbon paper layer and a second layer of superconducting tape from inside to outside respectively; the plurality of temperature measuring optical fibers are arranged in gaps among strips of the first layer of superconducting strips of the B-phase conductor layer; the diameters of the plurality of temperature measuring optical fibers are smaller than the thickness of the first layer of superconducting tape, gaps among the tapes of the first layer of superconducting tape are filled with polyimide resin, and the polyimide resin is used for bonding and fixing the plurality of temperature measuring optical fibers and enhancing the mechanical strength of the plurality of temperature measuring optical fibers;
the temperature measuring optical fibers are used for measuring the temperature along the line of the high-temperature superconducting cable and sending the measured temperature along the line to the monitoring system;
the monitoring system comprises a data receiving unit, a waveform characteristic obtaining unit and an instruction generating unit, wherein the data receiving unit is used for receiving the line temperatures detected by the plurality of temperature measuring optical fibers and forwarding the line temperatures to the waveform characteristic obtaining unit; the waveform characteristic acquisition unit is used for acquiring a waveform characteristic diagram of temperature variation along the superconducting cable according to the temperature along the line and outputting the waveform characteristic diagram to the instruction generation unit; the method for obtaining the waveform characteristic diagram of the temperature variation along the line of the superconducting cable according to the temperature along the line comprises the following steps: obtaining a plurality of corresponding temperature change waveform characteristic diagrams according to the temperatures along the line detected by the plurality of temperature measuring optical fibers, and superposing waveforms of the plurality of temperature change waveform characteristic diagrams to obtain a high-temperature super-temperatureCarrying out weighted summation on waveforms of the plurality of temperature change waveform characteristic diagrams to obtain a temperature change waveform characteristic diagram of the superconducting cable along the line; the instruction generating unit is used for determining the position and the width of one or more local quench areas according to the temperature change waveform characteristic diagram, determining whether to generate a cutting instruction or an alarm instruction according to the width of the one or more local quench areas, and sending the cutting instruction to a protection device or sending the alarm instruction to an alarm; the area between any adjacent positive narrow peak and negative narrow peak in the temperature change waveform characteristic diagram is a local quench area; when the width of any local quench zone satisfies d i >r L Generating an alarm instruction; when the width of any local quench zone satisfies d i >r H When the cutting instruction is generated; wherein d i Is the width of the ith local quench zone, r L 、r H Respectively preset threshold values;
the alarm is used for responding to the alarm instruction to perform high-temperature superconducting cable quench alarm;
the protection device is used for responding to the receiving of the cutting instruction and cutting off the high-temperature superconducting cable;
the notification unit is used for responding to the instruction generation unit to generate a cutting instruction or an alarm instruction, generating corresponding notification information and sending the notification information to a mobile phone of a preset operation and maintenance person; wherein the notification information includes location information of one or more local quench areas, and ablation instruction or alert instruction information.
2. The cable protection system based on a waveform of temperature variation along a cable according to claim 1, wherein the waveform characteristic obtaining unit is specifically configured to: and carrying out multi-resolution morphological gradient transformation according to the temperature along the line to obtain the temperature change waveform characteristic diagram.
3. A cable protection method based on a waveform of temperature variation along a cable, implemented based on a cable protection system according to any one of claims 1-2, characterized in that the method comprises the steps of:
the temperature measuring optical fibers measure the temperature along the line of the high-temperature superconducting cable and send the measured temperature along the line to the monitoring system;
the data receiving unit receives the line temperatures detected by the plurality of temperature measuring optical fibers and forwards the line temperatures to the waveform characteristic obtaining unit;
the waveform characteristic acquisition unit is used for responding to the received temperature along the line, acquiring a waveform characteristic diagram of temperature variation along the superconducting cable according to the temperature along the line and outputting the waveform characteristic diagram to the instruction generation unit; the method for obtaining the waveform characteristic diagram of the temperature variation along the line of the superconducting cable according to the temperature along the line comprises the following steps: obtaining a plurality of corresponding temperature change waveform characteristic diagrams according to the temperatures along the line detected by the plurality of temperature measuring optical fibers, and superposing waveforms of the plurality of temperature change waveform characteristic diagrams to obtain a temperature change waveform characteristic diagram of the high-temperature superconducting cable along the line, or carrying out weighted summation on waveforms of the plurality of temperature change waveform characteristic diagrams to obtain a temperature change waveform characteristic diagram of the high-temperature superconducting cable along the line;
the instruction generating unit is used for responding to the received temperature change waveform characteristic diagram, determining the position and the width of one or more local quench areas according to the temperature change waveform characteristic diagram, determining whether to generate a cutting instruction or an alarm instruction according to the width of the one or more local quench areas, and sending the cutting instruction to a protection device or sending the alarm instruction to an alarm; the area between any adjacent positive narrow peak and negative narrow peak in the temperature change waveform characteristic diagram is a local quench area; when the width of any local quench zone satisfies d i >r L Generating an alarm instruction; when the width of any local quench zone satisfies d i >r H When the cutting instruction is generated; wherein d i Is the width of the ith local quench zone, r L 、r H Respectively preset threshold values;
the alarm responds to the receiving of the alarm instruction to perform the quench alarm of the high-temperature superconducting cable;
the protection device responds to the receiving of the cutting instruction to cut off the high-temperature superconducting cable;
the notification unit responds to the instruction generation unit to generate a cutting instruction or an alarm instruction, generates corresponding notification information and sends the notification information to a mobile phone of a preset operation and maintenance person; wherein the notification information includes location information of one or more local quench areas, and ablation instruction or alert instruction information.
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| CN109659088A (en) * | 2019-01-23 | 2019-04-19 | 深圳供电局有限公司 | A kind of new type high temperature hyperconductive cable of built-in fiber and preparation method thereof |
| CN109855759A (en) * | 2019-01-23 | 2019-06-07 | 深圳供电局有限公司 | A kind of high-temperature superconductive cable temperature measurement system |
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