A BOTDR-based multi-strand twisted optical fiber composite carbon fiber core conductor breakage identification method, system, device and storage medium

Abstract

The application discloses a kind of multi-strand twisted optical fiber composite carbon fiber core conductor broken strand identification method, system, equipment and storage medium based on BOTDR, it is related to transmission line state monitoring and optical fiber distributed sensing technical field, method includes: when wire is intact, the frequency shift reference under different tension is calibrated, in online operation, by comparing real-time data with reference, according to the overall shift of remote frequency shift, broken strand is early warned;Each optical fiber frequency shift is scanned in early warning area, according to the characteristics of twisted core " valley " and center core " peak " at broken strand point, according to the ratio of peak value near broken strand point and remote increment, match feature library to determine broken strand number;The application realizes the on-line monitoring of carbon fiber core broken strand buried in the wire inside, can accurately identify the occurrence of broken strand, and accurately position broken strand section, judge broken strand number, whole process does not need power-off and disassembly, provides early warning for line safety.

Description

Technical Field

[0001] This invention relates to the field of power transmission line condition monitoring and fiber optic distributed sensing technology, and in particular to a method, system, device and storage medium for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR. Background Technology

[0002] With the advancement of inter-regional interconnection and ultra-high voltage transmission projects, the span length of transmission lines is continuously increasing, and the operating environment is becoming increasingly complex. Conductors are subjected to a combination of wind loads, icing loads, temperature cycles, and galloping vibrations over long periods, leading to increasingly prominent internal damage issues. Carbon fiber composite core conductors offer advantages such as light weight, high elastic modulus, and low coefficient of linear expansion, which are beneficial for improving the safety of lines in heavy icing and long-span scenarios. However, the carbon fiber core rods inside carbon fiber composite core conductors are susceptible to localized bending, impact, and fatigue during manufacturing, transportation, installation, and operation, posing a risk of micro-cracks, delamination, and even strand breakage. Because the carbon fiber core rods are encased in aluminum stranded wire and sheathing, internal defects are difficult to visually observe through inspection, posing a significant hidden danger to the safety of power grid operation.

[0003] Current methods for detecting defects in carbon fiber composite core conductors mainly rely on the following approaches: First, judging the overall stiffness change of the conductor by changes in sag, tension, or vibration characteristics. However, this method is easily affected by factors such as ambient temperature, wind speed, and span differences, and lacks sensitivity to a few broken strands in the core rod. Second, offline inspection of short sections of conductors is carried out using non-destructive testing techniques such as X-rays and ultrasound. This method is inefficient, costly, and unsuitable for long-distance lines in service. Third, local deployment of fiber optic gratings or other strain sensors is used, but this has limited sensing points and requires additional power supply and complex wiring, making it difficult to cover the entire line. Based on Brillouin optical time-domain reflectometry, temperature and strain distribution data along the entire optical fiber can be obtained under single-end or double-end access conditions. It has advantages such as long measurement distance, high spatial resolution, and strong resistance to electromagnetic interference. By pre-embedding optical fibers in the carbon core of the carbon fiber composite core conductor, the conductor body can be combined with distributed sensing data to achieve online monitoring of the conductor's internal temperature and strain, providing a new technical approach for identifying internal strand breakage defects. Existing fiber composite core monitoring work mainly focuses on the overall temperature and sag changes of the conductor. For local structural damage such as broken strands of single or a few carbon fiber cores, there is still a lack of systematic mechanical-optical coupling models and broken strand identification methods for engineering applications. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention provides a method, system, device and storage medium for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR.

[0005] Therefore, the technical problem solved by the present invention is that traditional methods cannot accurately identify the location and number of broken strands of the carbon fiber core inside the optical fiber composite carbon fiber core conductor covered by aluminum stranded wire online.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR, comprising: With the conductor to be identified intact, several representative tension levels are selected, and the frequency shift distribution along the optical fiber in each channel is obtained by BOTDR measurement to form a reference database. Based on the benchmark database, during the operation of the conductor to be identified, real-time frequency shift data is collected and compared with the benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it is determined whether there is a broken strand and the severity is initially estimated. At the distance where the fiber is suspected to be broken, the frequency shift increment of the central fiber and each stranded fiber is spatially scanned to identify the location of the broken fiber. Near the break point, the peak frequency shift increment of the statistical center fiber and the intact stranded fiber, and their ratio to the average frequency shift increment at the far end, were compared with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under working conditions, the number of broken strands can be determined.

[0007] As a preferred embodiment of a method for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR, wherein: With the conductor to be identified intact, several representative tension levels are selected, and the frequency shift distribution along each fiber channel is measured using BOTDR to form a benchmark database, including: During the manufacturing process of the conductor, single-mode optical fibers are pre-embedded along the axial direction in the central carbon fiber core rod and each stranded carbon fiber core rod, thereby forming multiple independent distributed optical fiber sensing channels inside the conductor. A multi-stage tensile loading was applied to the intact conductor sample. Under each stage of stable tensile force, Brillouin frequency shift distribution data along the length of the conductor were collected simultaneously from all built-in sensing channels.

[0008] As a preferred embodiment of a method for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR, wherein: The process of selecting several representative tension levels under the condition that the conductor to be identified is intact, and measuring the frequency shift distribution along the optical fiber in each channel using BOTDR to form a reference database also includes: Based on the linear relationship between Brillouin frequency shift and optical fiber axial strain and temperature, the strain sensitivity coefficient of the optical fiber is obtained by fitting multi-level tensile data under the condition of constant temperature control. Based on the material properties and structural parameters of the conductor, the theoretical strain distribution of the central core rod and the stranded core rod under various tensile forces was calculated using a mechanical model. Using the strain sensitivity coefficient, the calculated theoretical strain distribution of each mandrel is converted into the corresponding theoretical Brillouin frequency shift distribution; Integrate the theoretical Brillouin frequency shift distributions of all sensing channels under different tensile levels to establish a complete benchmark database.

[0009] As a preferred embodiment of a method for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR, wherein: The process, based on a benchmark database, involves collecting real-time frequency shift data during the operation of the conductor to be identified and comparing it with a benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it is determined whether there is a broken strand and the severity is initially estimated. The tension status of the conductor is monitored in real time. When the current tension is detected to reach or approach the preset tension level in the reference database, the system automatically triggers the acquisition of real-time Brillouin frequency shift distribution data along the length of the conductor from all sensor channels. The collected real-time frequency shift distribution data is compared with the corresponding reference frequency shift distribution data under the same tension level in the reference database, and the real-time frequency shift increment distribution along each sensing channel is obtained through differential calculation.

[0010] The beneficial effects of this preferred technical solution are as follows: by using tension-triggered acquisition and differential comparison with a benchmark under the same working condition, the strain background caused by the load itself is effectively removed, thereby highlighting the abnormal strain changes caused by structural damage (strand breakage). This processing method significantly improves the detection sensitivity of damage signals and is a key prerequisite for realizing online automatic early warning.

[0011] As a preferred embodiment of a method for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR, wherein: The process of collecting real-time frequency shift data during the operation of the conductor to be identified, based on a benchmark database, and comparing it with a benchmark under the same operating conditions, to determine whether there is a broken strand and to preliminarily estimate the severity by analyzing the overall offset of the far-end frequency shift, also includes: From the real-time frequency shift increment distribution, select multiple stable sections far from local disturbances within each span of the conductor as the analysis interval, calculate the spatial average value of the frequency shift increment of the sensing channel representing the state of the stranded mandrel within the analysis interval, and use it as the far-end average frequency shift increment. Based on the mechanical model of the conductor when different numbers of strands of the stranded core break, the corresponding theoretical strain amplification factor is calculated, and then the theoretical range of the change of the far-end average frequency shift increment under different numbers of strands is deduced. The measured values ​​of the calculated far-end average frequency shift increment are compared one by one with the theoretical range of change calculated based on different numbers of broken strands. If the measured value is significantly greater than zero and falls within the theoretical variation range corresponding to a certain number of broken strands, the conductor is suspected of having broken strands in the stranded core rod, and an early warning signal containing suspected span information and a preliminary estimated range of broken strands is generated.

[0012] The beneficial effects of this preferred technical solution are as follows: by analyzing the average frequency shift increment of the "far-end" stable section, interference from local stress concentration areas is effectively avoided, and the macroscopic effect of the overall conductor stiffness reduction caused by strand breakage is captured. Comparing this with the theoretical range derived from the mechanical model based on the number of broken strands achieves a leap from "detecting anomalies" to "preliminary quantitative assessment of the severity of damage (strand count range)," providing important guidance for subsequent precise location and determination.

[0013] As a preferred embodiment of a method for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR, wherein: The step of spatially scanning the frequency shift increments of the central optical fiber and each stranded optical fiber at the distance where a suspected strand breakage is identified includes: The real-time frequency shift increment distribution data of all fiber optic sensing channels within the suspected span is obtained. The real-time frequency shift increment is obtained by the difference between the real-time frequency shift distribution and the reference frequency shift distribution under the same operating condition. Based on the mechanical model of strain redistribution near the broken section, high-resolution synchronous spatial scanning analysis was performed on the real-time frequency shift increment distribution data of all fiber optic sensing channels within the suspected span. In the scanning analysis, spatial location points that simultaneously meet the following two conditions are identified and located: First, the frequency shift increment of at least one fiber optic sensing channel representing the stranded core rod shows a significant local negative peak at this point; Second, the frequency shift increment of the fiber optic sensing channel representing the central core rod shows a significant local positive peak at the same spatial location point. The spatial location coordinates that simultaneously meet the two conditions are determined as the precise cross-sectional location of the stranded core rod breakage inside the conductor.

[0014] As a preferred embodiment of a method for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR, wherein: Near the breakage location, the peak frequency shift increment of the central fiber and the intact stranded fiber, and their ratio to the average frequency shift increment at the far end, are analyzed by comparing them with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under operating conditions, the number of broken strands can be determined, including: Extract the real-time frequency shift increment peak value of the optical fiber sensing channel representing the central bearing core near the strand breakage location, and obtain the average frequency shift increment of the sensing channel representing the stranded core rod in the section far from the strand breakage location. The ratio between the peak frequency shift increment of the core bearing the calculation center and the average frequency shift increment of the stranded core rod; Beforehand, through theoretical analysis or experimental calibration, a database containing the characteristic range of ratios corresponding to different numbers of broken strands is established. The measured data of the calculated ratios are then matched and compared with the characteristic ranges of different numbers of broken strands stored in the database. Based on the matching results, the number of broken strands corresponding to the feature range that best matches the measured data is determined as the final number of broken strands.

[0015] Secondly, the present invention provides a system for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR, comprising: The calibration and benchmark establishment module is used to select several representative tension levels under the condition that the conductor to be identified is intact, and obtain the frequency shift distribution along the optical fiber of each channel by measuring with BOTDR to form a benchmark database; The online monitoring and anomaly early warning module is used to collect real-time frequency shift data during the operation of the conductor to be identified based on a benchmark database and compare it with a benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it can determine whether there is a broken strand and make a preliminary estimate of the severity. The positioning and feature scanning module is used to spatially scan the frequency shift increment of the central optical fiber and each stranded optical fiber in the span that is suspected of being broken at a distance, and to identify the location of the broken strand. The quantitative analysis and root count module is used to statistically analyze the peak frequency shift increment of the central fiber and intact stranded fibers near the breakage location, and the ratio of this peak value to the average frequency shift increment at the far end. This is done by comparing the peak value with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under working conditions, the number of broken strands can be determined.

[0016] Thirdly, the present invention provides a computer device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the method for identifying broken strands in multi-strand stranded optical fiber composite carbon fiber core conductors based on BOTDR.

[0017] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of a method for identifying broken strands in a BOTDR-based multi-stranded optical fiber composite carbon fiber core conductor.

[0018] The beneficial effects of this invention are as follows: Starting from the forces acting on the central core rod and stranded core rod inside the conductor, this invention establishes a unified force-strain-frequency shift model under both intact and broken strand conditions, achieving a connection between the mechanical and optical mechanisms, and can quantitatively distinguish between 1 to 3 broken strand conditions; This invention also utilizes the overall change in the far-end frequency shift-tension slope and the local peak-valley characteristics of the frequency shift of the central fiber and stranded fiber near the broken strand point for comprehensive discrimination, mutually verifying each other and improving the robustness and accuracy of broken strand identification; This invention uses pre-embedded optical fibers and BOTDR (Brillouin Optical Time Domain Reflectometry) devices inside the conductor, eliminating the need for additional power supply and complex sensor wiring, enabling long-distance continuous monitoring in strong electromagnetic environments, and is suitable for high-voltage and ultra-high-voltage long-distance carbon fiber composite core overhead conductors; This invention establishes a model based on the structure of typical fiber composite carbon fiber core conductors and experimental calibration results, and each parameter can be adjusted according to different conductor specifications and materials, exhibiting good versatility and engineering feasibility. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an overall flowchart of a method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR, provided by the present invention. Detailed Implementation

[0021] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0022] Example 1, referring to Figure 1 This is the first embodiment of the present invention, which provides a method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR, comprising: S1: With the conductor to be identified intact, select several representative tension levels and use BOTDR to measure the frequency shift distribution along the optical fiber in each channel to form a reference database; S2: Based on the benchmark database, during the operation of the conductor to be identified, real-time frequency shift data is collected and compared with the benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it is determined whether there is a broken strand and the severity is initially estimated. S3: At the distance where the fiber is suspected to be broken, spatial scanning is performed on the frequency shift increment of the central fiber and each stranded fiber to identify the location of the broken fiber. S4: Near the breakage location, the peak frequency shift increment of the statistical center fiber and the intact stranded fiber, and their ratio to the average frequency shift increment at the far end, are compared with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under working conditions, the number of broken strands can be determined.

[0023] It should be noted that through steps S1-S4, a complete technical system from mechanism modeling and benchmark calibration to online diagnosis was constructed. This system not only established a quantitative mapping relationship between the internal mechanical state of the conductor and the distributed optical fiber sensing signal, but also achieved online, quantitative, and distributed identification of hidden strand breakage defects by integrating the dual criteria of overall strain offset at the far end and local peak-valley characteristics. It can accurately determine the occurrence of strand breakage, locate the breakage section, and assess the degree of damage (number of broken strands) without power outages or disassembly of the conductor, providing an effective technical means for condition monitoring and early warning of optical fiber composite carbon fiber core conductors.

[0024] Example 2, refer to Figure 1 As an embodiment of the present invention, based on the previous embodiment, a method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR is provided, comprising: In this embodiment, in step S1 above, with the conductor to be identified intact, several representative tension levels are selected, and the frequency shift distribution along the fiber optic cable in each channel is measured using BOTDR to form a reference database, including: During the conductor manufacturing process, single-mode optical fibers are axially embedded in one central carbon fiber core rod and six surrounding stranded carbon fiber core rods, forming a 7-channel distributed sensing unit. Let the total carbon fiber cross-sectional area be... The cross-sectional area of ​​a single mandrel is / 7.

[0025] In another possible implementation, when constructing multiple independent distributed optical fiber sensing channels, an optical fiber can be pre-embedded in the central core rod. Instead of pre-embedding each carbon fiber core rod individually in the stranded layer, several stranded core rods (such as 6) are treated as a whole, and an optical fiber is spirally wound or placed side by side in their common outer protective layer or gap, thereby forming a sensing channel in the form of "1 (center) + N (stretched group)".

[0026] In another possible implementation, when constructing multiple independent distributed optical fiber sensing channels, spatial division multiplexing or wavelength division multiplexing technology can be used to inscribe or manufacture multiple sensing units that are spatially or wavelength-isolated in a single special optical fiber pre-embedded in the core rod. This physically reduces the number of optical fibers, but logically decouples independent strain information representing different core rods or regions.

[0027] Indoors, a tensile testing machine was used to subject intact conductor samples to multiple levels of loading. Under each stable tensile force F, the Brillouin frequency shift along the seven optical fibers was simultaneously acquired using a BOTDR device. .

[0028] A linear relationship is established between Brillouin frequency shift, strain, and temperature, expressed as: in, This represents the change in axial strain of the optical fiber. The change in temperature , These are the strain and temperature sensitivity coefficients, respectively.

[0029] In isothermal ( Under the experimental conditions, based on the linear relationship between Brillouin frequency shift, strain, and temperature, the strain sensitivity coefficient of the optical fiber was simplified and fitted to obtain the result. .

[0030] Meanwhile, based on the conductor structure parameters (elastic modulus of carbon fiber composite material) Single core cross-sectional area Twisting helix angle The theoretical strain of each mandrel under tensile force F was calculated using a well-established mechanical model. The strain of the central core was also calculated. Strain of a single stranded core Calculated using the following formulas respectively: Core strain: Strain of a single stranded core: Obtained by calibration The theoretical strain is converted into the theoretical frequency shift, thereby establishing a sound state benchmark database covering different tensile strengths. The theoretical frequency shifts of the center core and the stranded core are respectively: = = .

[0031] In another possible implementation, when constructing the benchmark database, Brillouin frequency shift data of each channel fiber can be collected and screened over a long period of time during the historical safe operation of the conductor under different environmental temperatures and different loads (such as wind load and ice load). After statistical analysis, a dynamic benchmark database containing multivariate coupling relationships can be formed.

[0032] In another possible implementation, the benchmark database can also be constructed by combining finite element simulation and physical calibration. First, a digital twin model is established using the precise geometric and material parameters of the conductor, and the theoretical strain distribution under various tensile forces is simulated and calculated. Then, the simulation results are corrected and calibrated through tensile tests on a small number of physical specimens, ultimately generating a high-fidelity theoretical benchmark database.

[0033] In another possible implementation, the synchronous acquisition of Brillouin frequency shift distribution data along the conductor length of all built-in sensor channels can also be achieved using a BOTDR device combined with a fiber optic switch matrix. The device rapidly and cyclically switches to each sensor channel for measurement according to a preset timing sequence. Since the switching and acquisition speed is much higher than the speed of change in the conductor state, it can be approximated as synchronous acquisition.

[0034] In another possible implementation, when synchronously acquiring Brillouin frequency shift distribution data along the length of the conductor for all built-in sensing channels, multiple BOTDR devices or a single device with multi-channel parallel acquisition capabilities can be used. Each sensing channel is simultaneously excited and detected by an independent acquisition module or device, thereby physically achieving strict synchronous acquisition of all channel data and ensuring that the data timestamps are completely consistent.

[0035] In this embodiment, step S2 above, based on a benchmark database, involves collecting real-time frequency shift data during the operation of the conductor to be identified and comparing it with a benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it is determined whether there is a broken strand and the severity is initially estimated, including: During online monitoring, when the conductor tension is detected to be close to or reach a certain calibrated tension level F in the reference database, the BOTDR is automatically triggered to acquire the current real-time frequency shift distribution of the seven optical fibers. Subsequently, the benchmark database generated in step S1 is invoked, and after temperature compensation and noise reduction processing of the real-time data, the frequency shift increment at each point along the line is calculated: To eliminate localized interference, within each span, several "far-end" stable sub-segments far from any obvious anomalies were selected, and the spatial average value of the frequency shift increment of all stranded fibers was calculated to obtain the measured value of the far-end average frequency shift increment. Compare this measured value with the value based on the number of broken strands. ( The theoretical increment predicted by the distal force model (=1,2,3) is compared. This theoretical increment is expressed as: in, The strain amplification factor is expressed as: like Significantly greater than zero, and with a certain If the theoretical increment range matches, then the corresponding gap will be output as a warning of potential stock breakage, and the number of potential breakage cycles will be preliminarily estimated. .

[0036] In another possible implementation, when analyzing the overall offset of the far-end frequency shift, the correlation coefficient or root mean square error between the real-time data and the reference data in the selected far-end segment can also be calculated. When a break occurs that causes a change in the strain distribution pattern, these statistical characteristics will deviate systematically. The significance of the offset can be determined by setting a threshold.

[0037] In another possible implementation, when analyzing the overall offset of the far-end frequency shift, a regression model of "load-far-end average frequency shift" can be established. Under normal conditions, this model has a definite slope. After the strand is broken, the far-end average frequency shift value under the same load will deviate significantly from the prediction range of this regression model. By monitoring this deviation, the overall offset can be analyzed.

[0038] In this embodiment, step S3 above, which involves spatially scanning the frequency shift increments of the central optical fiber and each stranded optical fiber at the distance where a suspected strand break is determined, to identify the break location, includes: After receiving the suspected break-even gap warning output in step S2, focus on the detailed frequency shift increment data within that gap. Based on the local stress distribution model of the broken strand, the cross-section of the broken strand... A unique strain redistribution occurs in the vicinity, a phenomenon that can be described by the following exponential recovery model: in, For remote response, Let be the local strain amplification (or reduction) factor for the i-th carbon core. To restore length. The broken strand mandrel in nearby The value is negative, while the value is positive for intact carbon cores and increases with the number of broken strands.

[0039] The corresponding Brillouin frequency shift distribution is: Based on this, the seven frequency shift increment curves High-resolution synchronous spatial scanning analysis was performed. The specific identification criterion was: to find the existence of a location point where one or more stranded-core optical fibers... It exhibits obvious frequency shift "valleys" (i.e., local negative peaks, corresponding to broken strand cores). Meanwhile, the central core fiber is at the same location. It exhibits a distinct frequency shift "peak" (i.e., a local positive spike, corresponding to the central core). The spatial location corresponding to this "peak-valley" is the point where the stress change is most intense, and it is determined and output as the precise coordinates of the fracture section. .

[0040] In this embodiment, in step S4 above, near the breakage location, the peak frequency shift increment of the central fiber and the intact stranded fiber, and their ratio to the average frequency shift increment at the far end, are statistically analyzed by comparing them with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under operating conditions, the number of broken strands can be determined, including: Obtain the precise break point output in step S3. Then, the detailed feature quantities near this location are first extracted from the data: the central core fiber is calculated in... Local frequency shift peak increment Simultaneously, obtain the average frequency shift increment at the far end of the range obtained in step S2. Calculate the ratio of the two: It should be noted that this ratio With the number of broken strands Strong correlation, because the peak increment includes the local strain concentration factor. The impact.

[0041] The calculated ratio The measured values, compared with the different numbers of broken strands established in advance through theoretical derivation and experimental calibration ( The feature criterion database is used for matching. Finally, the number of broken strands corresponding to the range in which the measured feature values ​​fall is output as the final result of the broken strand count determination. .

[0042] Example 3: The above is an illustrative scheme of a method for identifying broken strands in a BOTDR-based multi-stranded fiber composite carbon fiber core conductor. It should be noted that the technical solution of a BOTDR-based multi-stranded fiber composite carbon fiber core conductor broken strand identification system and the above-described BOTDR-based multi-stranded fiber composite carbon fiber core conductor broken strand identification method belong to the same concept. Details not described in detail in the BOTDR-based multi-stranded fiber composite carbon fiber core conductor broken strand identification system of this embodiment can be found in the description of the above-described BOTDR-based multi-stranded fiber composite carbon fiber core conductor broken strand identification method.

[0043] This embodiment also provides a BOTDR-based multi-strand stranded optical fiber composite carbon fiber core conductor strand breakage identification system, including: The calibration and benchmark establishment module is used to select several representative tension levels under the condition that the conductor to be identified is intact, and obtain the frequency shift distribution along the optical fiber of each channel by measuring with BOTDR to form a benchmark database; The online monitoring and anomaly early warning module is used to collect real-time frequency shift data during the operation of the conductor to be identified based on a benchmark database and compare it with a benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it can determine whether there is a broken strand and make a preliminary estimate of the severity. The positioning and feature scanning module is used to spatially scan the frequency shift increment of the central optical fiber and each stranded optical fiber in the span that is suspected of being broken at a distance, and to identify the location of the broken strand. The quantitative analysis and root count module is used to statistically analyze the peak frequency shift increment of the central fiber and intact stranded fibers near the breakage location, and the ratio of this peak value to the average frequency shift increment at the far end. This is done by comparing the peak value with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under working conditions, the number of broken strands can be determined.

[0044] This embodiment also provides an electronic device applicable to a method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR, including: The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement a method for identifying broken strands in a multi-stranded fiber composite carbon fiber core conductor based on BOTDR, as proposed in the above embodiments.

[0045] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements a method for identifying broken strands in a multi-stranded fiber composite carbon fiber core conductor based on BOTDR as proposed in the above embodiment.

[0046] The storage medium proposed in this embodiment belongs to the same inventive concept as the method for identifying broken strands of multi-stranded optical fiber composite carbon fiber core conductor based on BOTDR proposed in the above embodiment. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0047] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR, characterized in that, include: With the conductor to be identified intact, several representative tension levels are selected, and the frequency shift distribution along the optical fiber in each channel is obtained by BOTDR measurement to form a reference database. Based on the benchmark database, during the operation of the conductor to be identified, real-time frequency shift data is collected and compared with the benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it is determined whether there is a broken strand and the severity is initially estimated. At the distance where the fiber is suspected to be broken, the frequency shift increment of the central fiber and each stranded fiber is spatially scanned to identify the location of the broken fiber. Near the break point, the peak frequency shift increment of the statistical center fiber and the intact stranded fiber, and their ratio to the average frequency shift increment at the far end, were compared with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under working conditions, the number of broken strands can be determined.

2. The method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR as described in claim 1, characterized in that, With the conductor to be identified intact, several representative tension levels are selected, and the frequency shift distribution along each fiber channel is measured using BOTDR to form a benchmark database, including: During the manufacturing process of the conductor, single-mode optical fibers are pre-embedded along the axial direction in the central carbon fiber core rod and each stranded carbon fiber core rod, thereby forming multiple independent distributed optical fiber sensing channels inside the conductor. A multi-stage tensile loading was applied to the intact conductor sample. Under each stage of stable tensile force, Brillouin frequency shift distribution data along the length of the conductor were collected simultaneously from all built-in sensing channels.

3. The method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR as described in claim 2, characterized in that... The process of selecting several representative tension levels under the condition that the conductor to be identified is intact, and measuring the frequency shift distribution along the optical fiber in each channel using BOTDR to form a reference database also includes: Based on the linear relationship between Brillouin frequency shift and optical fiber axial strain and temperature, the strain sensitivity coefficient of the optical fiber is obtained by fitting multi-level tensile data under the condition of constant temperature control. Based on the material properties and structural parameters of the conductor, the theoretical strain distribution of the central core rod and the stranded core rod under various tensile forces was calculated using a mechanical model. Using the strain sensitivity coefficient, the calculated theoretical strain distribution of each mandrel is converted into the corresponding theoretical Brillouin frequency shift distribution; Integrate the theoretical Brillouin frequency shift distributions of all sensing channels under different tensile levels to establish a complete benchmark database.

4. The method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR as described in claim 3, characterized in that... The process, based on a benchmark database, involves collecting real-time frequency shift data during the operation of the conductor to be identified and comparing it with a benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it is determined whether there is a broken strand and the severity is initially estimated. The tension status of the conductor is monitored in real time. When the current tension is detected to reach or approach the preset tension level in the reference database, the system automatically triggers the acquisition of real-time Brillouin frequency shift distribution data along the length of the conductor from all sensor channels. The collected real-time frequency shift distribution data is compared with the corresponding reference frequency shift distribution data under the same tension level in the reference database, and the real-time frequency shift increment distribution along each sensing channel is obtained through differential calculation.

5. The method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR as described in claim 4, characterized in that... The process of collecting real-time frequency shift data during the operation of the conductor to be identified, based on a benchmark database, and comparing it with a benchmark under the same operating conditions, to determine whether there is a broken strand and to preliminarily estimate the severity by analyzing the overall offset of the far-end frequency shift, also includes: From the real-time frequency shift increment distribution, select multiple stable sections far from local disturbances within each span of the conductor as the analysis interval, calculate the spatial average value of the frequency shift increment of the sensing channel representing the state of the stranded mandrel within the analysis interval, and use it as the far-end average frequency shift increment. Based on the mechanical model of the conductor when different numbers of strands of the stranded core break, the corresponding theoretical strain amplification factor is calculated, and then the theoretical range of the change of the far-end average frequency shift increment under different numbers of strands is deduced. The measured values ​​of the calculated far-end average frequency shift increment are compared one by one with the theoretical range of change calculated based on different numbers of broken strands. If the measured value is significantly greater than zero and falls within the theoretical variation range corresponding to a certain number of broken strands, the conductor is suspected of having broken strands in the stranded core rod, and an early warning signal containing suspected span information and a preliminary estimated range of broken strands is generated.

6. The method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR as described in claim 5, characterized in that... The step of spatially scanning the frequency shift increments of the central optical fiber and each stranded optical fiber at the distance where a suspected strand breakage is identified includes: The real-time frequency shift increment distribution data of all fiber optic sensing channels within the suspected span is obtained. The real-time frequency shift increment is obtained by the difference between the real-time frequency shift distribution and the reference frequency shift distribution under the same operating condition. Based on the mechanical model of strain redistribution near the broken section, high-resolution synchronous spatial scanning analysis was performed on the real-time frequency shift increment distribution data of all fiber optic sensing channels within the suspected span. In the scanning analysis, spatial location points that simultaneously meet the following two conditions are identified and located: First, the frequency shift increment of at least one fiber optic sensing channel representing the stranded core rod shows a significant local negative peak at this point; Second, the frequency shift increment of the fiber optic sensing channel representing the central core rod shows a significant local positive peak at the same spatial location point. The spatial location coordinates that simultaneously meet the two conditions are determined as the precise cross-sectional location of the stranded core rod breakage inside the conductor.

7. The method for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR as described in claim 6, characterized in that... Near the breakage location, the peak frequency shift increment of the central fiber and the intact stranded fiber, and their ratio to the average frequency shift increment at the far end, are analyzed by comparing them with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under operating conditions, the number of broken strands can be determined, including: Extract the real-time frequency shift increment peak value of the optical fiber sensing channel representing the central bearing core near the strand breakage location, and obtain the average frequency shift increment of the sensing channel representing the stranded core rod in the section far from the strand breakage location. The ratio between the peak frequency shift increment of the core bearing the calculation center and the average frequency shift increment of the stranded core rod; Beforehand, through theoretical analysis or experimental calibration, a database containing the characteristic range of ratios corresponding to different numbers of broken strands is established. The measured data of the calculated ratios are then matched and compared with the characteristic ranges of different numbers of broken strands stored in the database. Based on the matching results, the number of broken strands corresponding to the feature range that best matches the measured data is determined as the final number of broken strands.

8. A system for identifying broken strands in a multi-strand stranded optical fiber composite carbon fiber core conductor based on BOTDR, using the method described in any one of claims 1 to 7, characterized in that, include: The calibration and benchmark establishment module is used to select several representative tension levels under the condition that the conductor to be identified is intact, and obtain the frequency shift distribution along the optical fiber of each channel by measuring with BOTDR to form a benchmark database; The online monitoring and anomaly early warning module is used to collect real-time frequency shift data during the operation of the conductor to be identified based on a benchmark database and compare it with a benchmark under the same operating conditions. By analyzing the overall offset of the far-end frequency shift, it can determine whether there is a broken strand and make a preliminary estimate of the severity. The positioning and feature scanning module is used to spatially scan the frequency shift increment of the central optical fiber and each stranded optical fiber in the span that is suspected of being broken at a distance, and to identify the location of the broken strand. The quantitative analysis and root count module is used to statistically analyze the peak frequency shift increment of the central fiber and intact stranded fibers near the breakage location, and the ratio of this peak value to the average frequency shift increment at the far end. This is done by comparing the peak value with different... By comparing the characteristic ranges obtained from theoretical or experimental calibration under working conditions, the number of broken strands can be determined.

9. An electronic device, characterized in that, include: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions, which, when executed by the processor, implement the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores computer-executable instructions that, when executed by a processor, implement the steps of the method according to any one of claims 1 to 7.

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