A distributed optical fiber temperature measurement method and terminal based on double light intensity dynamic calibration and multi-stage compensation

Abstract

The application discloses a kind of based on double light intensity dynamic calibration and multistage compensation distributed optical fiber temperature measurement method and terminal, by being placed in distributed optical fiber temperature measurement device with reference optical fiber, temperature sensing device in distributed optical fiber temperature measurement device temperature data as reference point temperature. The actual stokes light intensity curve of the optical fiber line to be measured, the actual anti-stokes light intensity curve, the theoretical stokes light intensity curve and the theoretical anti-stokes light intensity curve are obtained;The actual curve is calibrated using the theoretical curve, and the calibration value is obtained;According to the ratio of the anti-stokes light intensity and the stokes light intensity, the ratio is segmented linearly compensated;Further based on the compensated ratio and the reference point temperature, the initial temperature field of the optical fiber line to be measured is calculated, and the initial temperature field is compensated based on the reference point temperature, the more the reference point temperature deviates, the greater the temperature value to be compensated, and the final temperature field is obtained. In this way, the accuracy of optical fiber temperature measurement can be effectively improved.

Description

Technical Field

[0001] This invention relates to the technical field of fiber optic temperature measurement, and in particular to a distributed fiber optic temperature measurement method and terminal based on dual-intensity dynamic calibration and multi-level compensation. Background Technology

[0002] Existing distributed fiber optic temperature measurement typically uses dynamic Stokes light calibration, which involves setting up (for example, placing a 90m long fiber in a constant temperature water bath) as a reference segment of the fiber to simulate the Stokes light intensity distribution of the entire fiber at a reference temperature in real time.

[0003] However, directly exposing the reference bare fiber to the host machine involves a significant workload in environmental setup and is prone to damage or breakage of the exposed fiber. Furthermore, most current fiber optic temperature measurement methods simply obtain the theoretical Stokes and anti-Stokes intensity curves for the entire line and calculate the temperature by fitting the curves. This method is relatively limited and only applicable to homogeneous, non-fusion-splitter optical fibers in laboratory environments. In practical engineering applications, optical fibers often suffer from aging, bending, and fusion splicing, thus affecting the accuracy of temperature measurements in real-world applications. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a distributed optical fiber temperature measurement method and terminal based on dual-intensity dynamic calibration and multi-level compensation, which can improve the accuracy of optical fiber temperature measurement.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A distributed optical fiber temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation is applied to a temperature measurement system. The system includes a distributed optical fiber temperature measurement device with a built-in temperature sensor. The optical fiber line under test is segmented, and one segment is placed as a reference fiber within the distributed optical fiber temperature measurement device. The temperature data from the temperature sensor is used as a reference point temperature. The method includes the following steps: Obtain the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the optical fiber line under test; Obtain the theoretical Stokes intensity curve and the theoretical anti-Stokes intensity curve of the optical fiber line under test. The actual Stokes light intensity curve is calibrated proportionally using the theoretical Stokes light intensity curve to obtain the first calibration value. The actual anti-Stokes light intensity curve is calibrated proportionally using the theoretical anti-Stokes light intensity curve to obtain the second calibration value. The ratio of anti-Stokes light intensity to Stokes light intensity is calculated based on the first calibration value and the second calibration value, and piecewise linear compensation is performed on the ratio. The initial temperature field of the optical fiber line under test is calculated using the compensated ratio and the reference point temperature. The initial temperature field is then compensated based on the reference point temperature to obtain the final temperature field.

[0006] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows: A distributed fiber optic temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps of the distributed fiber optic temperature measurement based on dual-intensity dynamic calibration and multi-level compensation.

[0007] The beneficial effects of this invention are as follows: By placing the reference optical fiber inside a distributed optical fiber temperature measurement device and using the temperature data from the temperature sensor in the device as the reference temperature, the workload of environmental setup and deployment during the test can be reduced, while avoiding damage or breakage of exposed bare fibers. The invention involves acquiring the actual Stokes intensity curve, actual anti-Stokes intensity curve, theoretical Stokes intensity curve, and theoretical anti-Stokes intensity curve of the optical fiber under test; using the theoretical Stokes intensity curve to perform a proportional calibration on the actual Stokes intensity curve to obtain a first calibration value; using the theoretical anti-Stokes intensity curve to perform a proportional calibration on the actual anti-Stokes intensity curve to obtain a second calibration value; calculating the ratio of the anti-Stokes intensity to the Stokes intensity based on the first and second calibration values, and performing piecewise linear compensation on the ratio; then calculating the initial temperature field of the optical fiber under test based on the compensated ratio and the reference temperature; compensating for the initial temperature field based on the reference temperature; the greater the deviation from the reference temperature, the larger the temperature value to be compensated, resulting in the final temperature field. This method effectively improves the accuracy of optical fiber temperature measurement. Attached Figure Description

[0008] Figure 1 This is a flowchart of a distributed optical fiber temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the removal of the DC component of light intensity according to an embodiment of the present invention; Figure 3 This is a flowchart illustrating the process of obtaining the theoretical light intensity curve according to an embodiment of the present invention; Figure 4 This is a flowchart illustrating the specific steps of a distributed optical fiber temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation, according to an embodiment of the present invention. Figure 5 This is a schematic diagram of a distributed fiber optic temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation according to an embodiment of the present invention. Figure 6 This is a schematic diagram illustrating different reference point temperatures in embodiments of the present invention.

[0009] Label Explanation: 1. A distributed fiber optic temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation; 2. Memory; 3. Processor. Detailed Implementation

[0010] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0011] Before detailing the embodiments of this application, some related concepts will first be explained: Stokes lines are characteristic spectral lines produced in Raman scattering and are a component of the Raman spectrum. When an incident photon undergoes an inelastic collision with a molecule, the molecule absorbs the photon energy and transitions to a virtual energy level before falling into a higher vibrational energy level. This results in the scattered light having a frequency lower than the incident light frequency, and the resulting spectral lines are called Stokes lines. Correspondingly, anti-Stokes lines have a higher frequency than the incident light, and the two are symmetrically distributed on either side of the Rayleigh scattering lines. Stokes intensity corresponds to the scattering process from the molecule's ground state; it has a strong signal and is the primary focus of conventional Raman spectroscopy analysis. Anti-Stokes intensity corresponds to the scattering process from the molecule's excited state; it has a weak signal, but its intensity ratio to the Stokes intensity is extremely sensitive to temperature, making it suitable for non-contact precision temperature measurement.

[0012] In existing technologies, distributed fiber optic temperature measurement employs dynamic Stokes light calibration, which uses a reference segment (e.g., placing a 90m long fiber in a constant-temperature water bath) as a reference to simulate the Stokes light intensity distribution of the entire fiber at a reference temperature in real time. This experiment shows that within the range of 35℃-95℃, the dynamic Stokes light calibration method reduces the temperature measurement deviation from -5.8℃~1.0℃ to -0.8~0.9℃ compared to traditional methods; the root mean square error (RMS) decreases from 4.0℃ to 0.5℃ (with a further 8.9℃ improvement in accuracy after Rayleigh noise suppression).

[0013] However, the above methods expose the bare fiber directly to the host, resulting in a large workload for environmental setup and a high risk of damage or breakage to the exposed fiber. Furthermore, most current temperature measurement methods only obtain the theoretical Stokes and anti-Stokes intensity curves for the entire line and then calculate the temperature of the entire line by fitting the curves; or they only compensate for the ratio of anti-Stokes intensity to Stokes intensity before calculating the overall temperature. These methods are relatively simplistic and only suitable for laboratory environments with homogeneous, non-fusion-splitter optical fibers. In practical engineering applications, optical fibers often suffer from aging, bending, fusion splices, and reference point temperature deviations.

[0014] To at least solve the above problems, please refer to Figure 1This invention provides a distributed optical fiber temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation, applied to a temperature measurement system. The temperature measurement system includes a distributed optical fiber temperature measurement device with a built-in temperature sensor. The optical fiber line under test is segmented, and one segment is placed as a reference fiber within the distributed optical fiber temperature measurement device. The temperature data from the temperature sensor is used as a reference point temperature. The method includes the following steps: Obtain the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the optical fiber line under test; Obtain the theoretical Stokes intensity curve and the theoretical anti-Stokes intensity curve of the optical fiber line under test. The actual Stokes light intensity curve is calibrated proportionally using the theoretical Stokes light intensity curve to obtain the first calibration value. The actual anti-Stokes light intensity curve is calibrated proportionally using the theoretical anti-Stokes light intensity curve to obtain the second calibration value. The ratio of anti-Stokes light intensity to Stokes light intensity is calculated based on the first calibration value and the second calibration value, and piecewise linear compensation is performed on the ratio. The initial temperature field of the optical fiber line under test is calculated using the compensated ratio and the reference point temperature. The initial temperature field is then compensated based on the reference point temperature to obtain the final temperature field.

[0015] As described above, the beneficial effects of this invention are as follows: by placing the reference optical fiber inside the distributed optical fiber temperature measurement device and using the temperature measurement data from the temperature sensor in the distributed optical fiber temperature measurement device as the reference point temperature, the workload of environmental setup and deployment during the test process can be reduced, while avoiding damage or breakage of exposed bare fibers. The actual Stokes intensity curve, actual anti-Stokes intensity curve, theoretical Stokes intensity curve, and theoretical anti-Stokes intensity curve of the optical fiber line under test are obtained; the actual Stokes intensity curve is calibrated proportionally using the theoretical Stokes intensity curve to obtain a first calibration value; the actual anti-Stokes intensity curve is calibrated proportionally using the theoretical anti-Stokes intensity curve to obtain a second calibration value; the ratio of the anti-Stokes intensity to the Stokes intensity is calculated based on the first and second calibration values, and piecewise linear compensation is performed on the ratio; then, the initial temperature field of the optical fiber line under test is calculated based on the compensated ratio and the reference point temperature, and the initial temperature field is compensated based on the reference point temperature. The greater the deviation from the reference point temperature, the larger the temperature value to be compensated, resulting in the final temperature field. In this way, the accuracy of optical fiber temperature measurement can be effectively improved.

[0016] Please refer to Figure 2 Furthermore, the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the fiber optic line under test are obtained, including: Obtain the actual Stokes intensity and actual anti-Stokes intensity at each sampling point of the fiber optic line under test; Obtain the segments of the fiber optic line under test in a steady state, and calculate the average Stokes light intensity and the average anti-Stokes light intensity of the segments. Subtract the average Stokes light intensity from the actual Stokes light intensity at each sampling point of the optical fiber line under test to construct the actual Stokes light intensity curve. The actual anti-Stokes light intensity curve is constructed by subtracting the average anti-Stokes light intensity from the actual anti-Stokes light intensity at each sampling point of the optical fiber line under test.

[0017] As described above, the DC component needs to be removed before processing Stokes and anti-Stokes intensity data. The DC component refers to the steady-state portion or average value of the signal over a long period; it represents the signal's offset or baseline level and does not include AC fluctuations. The steady-state portion of the signal extends a short distance beyond the line length. Taking the average value of this short section as the DC component of the intensity eliminates baseline drift caused by light source power drift and detector dark current, thus improving measurement accuracy.

[0018] Please refer to Figure 3 Furthermore, the theoretical Stokes intensity curve and the theoretical anti-Stokes intensity curve of the optical fiber line under test are obtained, including: Select segments at the same temperature at the front and rear ends of the optical fiber line under test, and calculate the middle position of the segment, the mean value of the Stokes intensity AC component, and the mean value of the anti-Stokes intensity AC component. By combining the exponential decay model with the calculated midpoint of the segments, the mean value of the Stokes intensity AC component, and the mean value of the anti-Stokes intensity AC component, theoretical Stokes intensity curves and theoretical anti-Stokes intensity curves are generated.

[0019] As described above, at least one isothermal segment is selected at both the front and back ends of the line. The mean value of the AC component of the Stokes light intensity and the mean value of the AC component of the anti-Stokes light intensity are calculated at the midpoint of the segment. These values ​​are then used to fit and generate the theoretical Stokes light intensity curve and the theoretical anti-Stokes light intensity curve by combining them with the exponential decay model. In this way, by modeling the light intensity decay of the entire line and converting the light intensity proportionally, accurate compensation for the nonlinear loss of the optical fiber is achieved.

[0020] Further, piecewise linear compensation is performed on the ratio, including: Obtain the compensation interval of the fiber optic line under test [z] start , z end ], and generate a sampling point sequence r based on the interval to be compensated. data =[z start , …, z end ]; Dynamically obtain the calibration sampling points with known temperatures in the interval to be compensated.data =[(z l , T l ), …]; The calibration sampling point z l Insert the sampling point sequence r data The adjacent sampling points z of the calibration sampling point are obtained. ll and z lr And calculate the compensation slope left based on the adjacent sampling points. k and right k ; Piecewise linear compensation is performed on the ratio R(z) of the sampling points using the adjacent sampling points and their compensation slopes: R(z) = R(z) + left k ·(z z ll ), z∈[z ll , z l ]; R(z) = R(z) + right k ·(z lr z), z∈[z l , z lr ].

[0021] As described above, the compensation slope is calculated using the interval to be compensated and its calibration sampling points, and then piecewise linear compensation is performed on the ratio of the sampling points. If the quality of the optical fiber and the laser source is sufficiently high, the step of ratio linear compensation can be omitted. In this way, the initial temperature field can be established by combining dual light intensity and ratio compensation, thereby improving the accuracy of temperature measurement.

[0022] Further, the initial temperature field is compensated based on the reference point temperature to obtain the final temperature field, including: Segments are selected within a preset range from the reference fiber as temporary reference areas and measurement areas; The temporary reference area and the measurement area are placed in separate water baths and the temperature is gradually increased. The measured temperature of the temporary reference area, the measured temperature of the measurement area, and the temperature field predicted by the measurement area are recorded. The fitting coefficient is obtained by fitting the measured temperature of the temporary reference area, the measured temperature of the measurement area, and the temperature field predicted by the measurement area. The initial temperature field is compensated by combining the fitting coefficients and the reference point temperature to obtain the final temperature field.

[0023] As described above, by fitting the measured temperature of the temporary reference area, the measured temperature of the measurement area, and the temperature field predicted by the measurement area to obtain the fitting coefficient, and by compensating the initial temperature field with the fitting coefficient and the reference point temperature to obtain the final temperature field, it is possible to correct the situation where the calculated absolute temperature value is lower than the actual temperature due to deviation from the internal temperature of the host.

[0024] Please refer to Figure 5 Another embodiment of the present invention provides a distributed optical fiber temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps of the above-mentioned distributed optical fiber temperature measurement based on dual-intensity dynamic calibration and multi-level compensation.

[0025] The distributed fiber optic temperature measurement method and terminal based on dual-intensity dynamic calibration and multi-level compensation described above are applicable to improving the accuracy of distributed fiber optic temperature measurement. The following detailed implementation methods illustrate these methods: Please refer to Figure 4 One embodiment of the present invention is as follows: A distributed fiber optic temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation is applied to a temperature measurement system. The system includes a distributed fiber optic temperature measurement device with a built-in temperature sensor. The fiber optic line under test is segmented, and one segment is placed as a reference fiber within the distributed fiber optic temperature measurement device. The temperature data measured by the temperature sensor is used as a reference point temperature. (The reference point temperature is referenced from...) Figure 6 The x-axis represents the actual temperature, and the y-axis represents the temperature calculated through dynamic self-calibration. For example, when the actual temperature is 50℃, the calculated temperature will be different under different reference temperatures. This method includes the following steps: S1. Obtain the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the optical fiber line under test.

[0026] S11. Obtain the actual Stokes intensity and actual anti-Stokes intensity at each sampling point of the fiber optic line under test. Specifically, obtain the actual measured Stokes intensity I at each sampling point of the fiber optic line under test. S and anti-Stokes light intensity I AS .

[0027] S12. Obtain the segments of the optical fiber line under test in a steady state, and calculate the average Stokes light intensity and the average anti-Stokes light intensity of the segments.

[0028] For details, please refer to Figure 2Before processing Stokes and anti-Stokes intensity data, the DC component needs to be removed. The DC component refers to the steady-state portion or average value of the signal over a long period; it represents the signal's offset or baseline level and does not include AC fluctuations. The steady-state portion of the signal extends a short distance beyond the fiber optic cable's length. These are additional sampling points not actually part of the fiber itself. The intensity of these points is unaffected by changes in physical quantities along the fiber and can therefore be considered the steady-state (DC) component. For example, if a fiber is 2000 meters long and requires 5000 sampling points, a length of 2100 meters would require 5250 sampling points. The signal from these latter 250 points is simply the system's residual response, also known as system noise floor, and can be considered the DC component, independent of the fiber. In this embodiment, the calculated average Stokes intensity is denoted as DC. S The average anti-Stokes light intensity is denoted as DC. AS .

[0029] S13. Subtract the average value of the Stokes light intensity from the actual Stokes light intensity at each sampling point of the optical fiber line under test to construct the actual Stokes light intensity curve; subtract the average value of the anti-Stokes light intensity from the actual anti-Stokes light intensity at each sampling point of the optical fiber line under test to construct the actual anti-Stokes light intensity curve.

[0030] Please refer to Figure 2 The AC component I' is obtained by subtracting the DC component of the Stokes light intensity from the Stokes light intensity at each sampling point along the entire line. S The AC component I' is obtained by subtracting the DC component of the anti-Stokes light intensity from the anti-Stokes light intensity at each point. AS .

[0031] S2. Obtain the theoretical Stokes intensity curve and the theoretical anti-Stokes intensity curve of the optical fiber line under test.

[0032] S21. Select segments with the same temperature at the front and rear ends of the optical fiber line under test, and calculate the middle position of the segment, the mean value of the Stokes intensity AC component, and the mean value of the anti-Stokes intensity AC component.

[0033] For details, please refer to Figure 3 At least one isothermal zone (length ≥ 2 meters) is selected at both the front and rear ends of the line to obtain its I'. S The average value of I' AS The average value and the center position of the segment.

[0034] S22. Combining the exponential decay model with the calculated midpoint of the segment, the mean value of the Stokes light intensity AC component, and the mean value of the anti-Stokes light intensity AC component, the theoretical Stokes light intensity curve and the theoretical anti-Stokes light intensity curve are fitted and generated.

[0035] Please refer to Figure 3 Using the exponential decay model I th (z)=a·e (–b·z) And the Stokes intensity fitting function I for the entire line is generated by fitting the position and average value. S,th (z) and anti-Stokes intensity fitting function I AS,th (z); where a represents the initial light intensity, a constant; b represents the attenuation coefficient, a constant; and z represents the distance, the location number of the sampling point (z=0,1,2,3,4,5....), which is equivalent to the axial distance along the fiber because the spatial resolution is fixed. If the obtained theoretical curve is not ideal, several points can be selected along the entire line, and a piecewise fitting method can be adopted, fitting a function for every two adjacent points.

[0036] S3. Use the theoretical Stokes light intensity curve to perform a proportional calibration on the actual Stokes light intensity curve to obtain the first calibration value. Use the theoretical anti-Stokes light intensity curve to perform a proportional calibration on the actual anti-Stokes light intensity curve to obtain the second calibration value.

[0037] Specifically, a fixed scaling factor K (e.g., 1000) is selected, and the first calibration value I is calculated point by point. S,cal (z) and the second calibration value I AS,cal (z): I S,cal (z)=I' S (z)·K / I S,th (z) I AS,cal (z)=I' AS (z)·K / I AS,th (z) This completes the adaptive attenuation correction for the entire line.

[0038] S4. Calculate the ratio of anti-Stokes light intensity to Stokes light intensity based on the first calibration value and the second calibration value, and perform piecewise linear compensation on the ratio.

[0039] S41. Calculate the ratio of anti-Stokes light intensity to Stokes light intensity: R(z)=I AS,cal (z) / I S,cal (z).

[0040] S42. Perform piecewise linear compensation on the ratio. This step can be omitted if the quality of the optical fiber and the laser source is sufficiently high; otherwise, the following steps are performed.

[0041] Obtain the compensation interval of the fiber optic line under test [z] start , z end ], and generate a sampling point sequence r based on the interval to be compensated. data =[z start , …, z end ].

[0042] Dynamically obtain the calibration sampling points with known temperatures in the interval to be compensated. data =[(z l , T l For example, there are two points to be compensated: [(5200, 27.2), (9800, 27.2)], where 5200 and 9800 are the locations of the compensation points, and 27.2 is the temperature at the compensation location. (The rest of the text appears to be a series of characters and symbols, possibly representing a mathematical expression or a corrupted file.) l Inversely calculate the ideal ratio r z_th And read the actual ratio r z_real =R(z l ).

[0043] The calibration sampling point z l Insert the sampling point sequence r data The adjacent sampling points z of the calibration sampling point are obtained. ll and z lr And calculate the compensation slope left based on the adjacent sampling points. k and right k Record the compensation tuple [z] ll , z l ,z lr left k , right k ]To the compensation table dt.

[0044] Furthermore, traverse each sampling point in the compensation table dt and check z. ll Is it valid and in the range of 0? If so, then from z... ll+1 Traverse to z l Perform compensation calculations within the effective range; check z lr Is it valid and in z l If so, then from z l+1 Traverse to z lr Compensation calculations are performed within the effective range. Specifically, piecewise linear compensation is applied to R(z) using dt, meaning piecewise linear compensation is applied to the ratio R(z) of the sampling points using the adjacent sampling points and their compensation slopes. R(z) = R(z) + left k ·(z z ll ), z∈[z ll , z l ]; R(z) = R(z) + right k ·(z lr z), z∈[z l , z lr ].

[0045] S5. Calculate the initial temperature field of the optical fiber line under test using the compensated ratio and the reference point temperature, and compensate the initial temperature field based on the reference point temperature to obtain the final temperature field.

[0046] S51. Calculate the initial temperature field T(z) of the fiber optic line under test using the compensated ratio and the reference point temperature:

[0047] In the formula, k represents Boltzmann constant; h represents Planck constant; Δν represents Raman frequency shift; and T(0) represents the reading of the internal temperature sensor of DTS.

[0048] If step S42 has been executed, substitute the compensated R(z) into the above equation to obtain the initial temperature field T(z).

[0049] S52. Select segments within a preset range from the reference fiber as temporary reference areas and measurement areas. Place the temporary reference areas and measurement areas in independent water baths and gradually increase the temperature. Record the measured temperature of the temporary reference areas, the measured temperature of the measurement areas, and the temperature field predicted by the measurement areas. Fit the measured temperature of the temporary reference areas, the measured temperature of the measurement areas, and the temperature field predicted by the measurement areas to obtain fitting coefficients. Combine the fitting coefficients and the reference point temperature to compensate for the initial temperature field to obtain the final temperature field.

[0050] Specifically, near the reference point, select: temporary reference area A, length ≥ 2 m; measurement area B, length ≥ 2 m (set at the end of the biased fiber). Place A and B in independent water baths, and control the temperature in the sequence of 30 ℃→40 ℃→…→90 ℃, recording the measured temperature T of area A. base The measured temperature in zone B and the temperature field predicted using zone B are used to determine the coefficients A to F by performing least squares fitting based on the measured temperature in zone A, the measured temperature in zone B, and the temperature field predicted using zone B.

[0051] Using a polynomial model: T real = 2·Tcalc f(T calc , T base ) f(x,y)=A·x³+B·x²+C·x+D+E·y+F·y² Substitute T(z) into the above equation for T calc Substituting the reference point temperature into T in the above formula base .

[0052] According to T real The final temperature field T is obtained final (z).

[0053] In summary, the overall process of this embodiment is: DC component removal → dual-intensity segmented proportional calibration → ratio compensation → temperature calculation using dynamic self-calibration → temperature compensation correction for deviation from the reference point. These steps must be strictly performed in sequence (if the quality of the line fiber and laser source is sufficiently high, the ratio compensation step can be omitted, but the other steps still need to be performed in order). Compared to existing methods that expose bare fibers directly outside the host, this embodiment embeds the reference fiber segment directly within the host, reducing the workload of environmental setup and deployment during the testing process, while avoiding damage or breakage of exposed bare fibers. By modeling the entire line for intensity attenuation and performing proportional conversion of intensity, accurate compensation for fiber nonlinear loss is achieved. By comprehensively applying the methods and steps proposed in this embodiment and processing the data step by step, the final line temperature measurement value is more accurate.

[0054] According to another aspect of the invention, Figure 5 This is a schematic diagram illustrating a distributed fiber optic temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation according to an embodiment of the present invention. The electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the various steps of the distributed fiber optic temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation as described above.

[0055] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A distributed fiber optic temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation, characterized in that, The system, applied to a temperature measurement system, includes a distributed optical fiber temperature measurement device with a built-in temperature sensor. The optical fiber line to be measured is segmented, and one segment is placed as a reference fiber within the distributed optical fiber temperature measurement device. The temperature data measured by the temperature sensor is used as a reference point temperature. The process includes the following steps: Obtain the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the fiber optic line under test; To obtain the theoretical Stokes intensity curve and the theoretical anti-Stokes intensity curve of the optical fiber line under test: Select segments with the same temperature at the front and rear ends of the optical fiber line under test, and calculate the middle position of the segment, the mean value of the AC component of the Stokes intensity, and the mean value of the AC component of the anti-Stokes intensity. By combining the exponential decay model with the calculated midpoint of the segment, the mean value of the Stokes light intensity AC component, and the mean value of the anti-Stokes light intensity AC component, the theoretical Stokes light intensity curve and the theoretical anti-Stokes light intensity curve are generated. The actual Stokes light intensity curve was calibrated proportionally using the theoretical Stokes light intensity curve to obtain the first calibration value. The actual anti-Stokes light intensity curve was then calibrated proportionally using the theoretical anti-Stokes light intensity curve to obtain the second calibration value. Using a fixed scaling factor K, the first calibration value I is calculated point by point. S,cal (z) and the second calibration value I AS,cal (z): I S,cal (z)=I’ S (z)·K / I S,th (z) I AS,cal (z)=I’ AS (z)·K / I AS,th (z) In the formula, I' S (z) represents the actual Stokes intensity curve, I S,th (z) represents the theoretical Stokes intensity curve, I AS,cal (z) represents the actual anti-Stokes intensity curve, I AS,th (z) represents the theoretical anti-Stokes intensity curve; The ratio of anti-Stokes light intensity to Stokes light intensity is calculated based on the first calibration value and the second calibration value, and piecewise linear compensation is performed on the ratio. The initial temperature field T(z) of the fiber optic line under test is calculated using the compensated ratio and the reference point temperature: In the formula, k represents Boltzmann constant; h represents Planck constant; Δν represents Raman frequency shift; T(0) represents the reading of the internal temperature sensor of DTS; R(z) represents the ratio after compensation; The initial temperature field is compensated based on the reference point temperature to obtain the final temperature field, including: selecting segments within a preset range from the reference fiber as temporary reference areas and measurement areas; placing the temporary reference areas and the measurement areas in independent water baths and gradually increasing the temperature, recording the measured temperature of the temporary reference areas, the measured temperature of the measurement areas, and the temperature field predicted by the measurement areas; fitting the measured temperature of the temporary reference areas, the measured temperature of the measurement areas, and the temperature field predicted by the measurement areas to obtain fitting coefficients A to F; and compensating the initial temperature field by combining the fitting coefficients and the reference point temperature to obtain the final temperature field. The polynomial model is used here: T real = 2·T calc f(T calc , T base ) f(x,y)=A·x³+B·x²+C·x+D+E·y+F·y² Substituting T(z) into the above equation... calc Substituting the reference point temperature into T in the above formula base .

2. The distributed fiber optic temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation according to claim 1, characterized in that, Obtain the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the fiber optic line under test, including: Obtain the actual Stokes intensity and actual anti-Stokes intensity at each sampling point of the fiber optic line under test; Obtain the segments of the fiber optic line under test in a steady state, and calculate the average Stokes light intensity and the average anti-Stokes light intensity of the segments. Subtract the average Stokes light intensity from the actual Stokes light intensity at each sampling point of the optical fiber line under test to construct the actual Stokes light intensity curve. The actual anti-Stokes light intensity curve is constructed by subtracting the average anti-Stokes light intensity from the actual anti-Stokes light intensity at each sampling point of the optical fiber line under test.

3. The distributed fiber optic temperature measurement method based on dual-intensity dynamic calibration and multi-level compensation according to claim 1, characterized in that, Piecewise linear compensation of the ratio includes: Obtain the compensation interval of the fiber optic line under test [z] start , z end ], and generate a sampling point sequence r based on the interval to be compensated. data =[z start , …, z end ]; Dynamically obtain the calibration sampling points with known temperatures in the interval to be compensated. data =[(z l , T l ), …]; The calibration sampling point z l Insert the sampling point sequence r data The adjacent sampling points z of the calibration sampling point are obtained. ll and z lr And calculate the compensation slope left based on the adjacent sampling points. k and right k ; Piecewise linear compensation is performed on the ratio R(z) of the sampling points using the adjacent sampling points and their compensation slopes: R(z)=R(z)+left k ·(z z ll ), z∈[z ll , z l ]; R(z)=R(z)+right k ·(z lr z), z∈[z l , z lr ]。 4. A distributed fiber optic temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The system is applied to a temperature measurement system, which includes a distributed optical fiber temperature measurement device with a built-in temperature sensor. The optical fiber line to be measured is segmented, and one segment is placed as a reference fiber within the distributed optical fiber temperature measurement device. The temperature data measured by the temperature sensor is used as a reference point temperature. When the processor executes the computer program, it performs the following steps: Obtain the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the fiber optic line under test; To obtain the theoretical Stokes intensity curve and the theoretical anti-Stokes intensity curve of the optical fiber line under test: Select segments with the same temperature at the front and rear ends of the optical fiber line under test, and calculate the middle position of the segment, the mean value of the AC component of the Stokes intensity, and the mean value of the AC component of the anti-Stokes intensity. By combining the exponential decay model with the calculated midpoint of the segment, the mean value of the Stokes light intensity AC component, and the mean value of the anti-Stokes light intensity AC component, the theoretical Stokes light intensity curve and the theoretical anti-Stokes light intensity curve are generated. The actual Stokes light intensity curve was calibrated proportionally using the theoretical Stokes light intensity curve to obtain the first calibration value. The actual anti-Stokes light intensity curve was then calibrated proportionally using the theoretical anti-Stokes light intensity curve to obtain the second calibration value. Using a fixed scaling factor K, the first calibration value I is calculated point by point. S,cal (z) and the second calibration value I AS,cal (z): I S,cal (z)=I’ S (z)·K / I S,th (z) I AS,cal (z)=I’ AS (z)·K / I AS,th (z) In the formula, I' S (z) represents the actual Stokes intensity curve, I S,th (z) represents the theoretical Stokes intensity curve, I AS,cal (z) represents the actual anti-Stokes intensity curve, I AS,th (z) represents the theoretical anti-Stokes intensity curve; The ratio of anti-Stokes light intensity to Stokes light intensity is calculated based on the first calibration value and the second calibration value, and piecewise linear compensation is performed on the ratio. The initial temperature field T(z) of the fiber optic line under test is calculated using the compensated ratio and the reference point temperature: In the formula, k represents Boltzmann constant; h represents Planck constant; Δν represents Raman frequency shift; T(0) represents the reading of the internal temperature sensor of DTS; R(z) represents the ratio after compensation; The initial temperature field is compensated based on the reference point temperature to obtain the final temperature field, including: selecting segments within a preset range from the reference fiber as temporary reference areas and measurement areas; placing the temporary reference areas and the measurement areas in independent water baths and gradually increasing the temperature, recording the measured temperature of the temporary reference areas, the measured temperature of the measurement areas, and the temperature field predicted by the measurement areas; fitting the measured temperature of the temporary reference areas, the measured temperature of the measurement areas, and the temperature field predicted by the measurement areas to obtain fitting coefficients A to F; and compensating the initial temperature field by combining the fitting coefficients and the reference point temperature to obtain the final temperature field. The polynomial model is used here: T real = 2·T calc f(T calc , T base ) f(x,y)=A·x³+B·x²+C·x+D+E·y+F·y² Substituting T(z) into the above equation... calc Substituting the reference point temperature into T in the above formula base .

5. A distributed fiber optic temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation according to claim 4, characterized in that, Obtain the actual Stokes intensity curve and the actual anti-Stokes intensity curve of the fiber optic line under test, including: Obtain the actual Stokes intensity and actual anti-Stokes intensity at each sampling point of the fiber optic line under test; Obtain the segments of the fiber optic line under test in a steady state, and calculate the average Stokes light intensity and the average anti-Stokes light intensity of the segments. Subtract the average Stokes light intensity from the actual Stokes light intensity at each sampling point of the optical fiber line under test to construct the actual Stokes light intensity curve. The actual anti-Stokes light intensity curve is constructed by subtracting the average anti-Stokes light intensity from the actual anti-Stokes light intensity at each sampling point of the optical fiber line under test.

6. A distributed fiber optic temperature measurement terminal based on dual-intensity dynamic calibration and multi-level compensation according to claim 4, characterized in that, Piecewise linear compensation of the ratio includes: Obtain the compensation interval of the fiber optic line under test [z] start , z end ], and generate a sampling point sequence r based on the interval to be compensated. data =[z start , …, z end ]; Dynamically obtain the calibration sampling points with known temperatures in the interval to be compensated. data =[(z l , T l ), …]; The calibration sampling point z l Insert the sampling point sequence r data The adjacent sampling points z of the calibration sampling point are obtained. ll and z lr And calculate the compensation slope left based on the adjacent sampling points. k and right k ; Piecewise linear compensation is performed on the ratio R(z) of the sampling points using the adjacent sampling points and their compensation slopes: R(z)=R(z)+left k ·(z z ll ), z∈[z ll , z l ]; R(z)=R(z)+right k ·(z lr z), z∈[z l , z lr ]。

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