Calibration device of distributed optical fiber temperature measurement sensing system

Abstract

The utility model relates to a calibration device of a distributed optical fiber temperature measurement sensing system. The calibration device comprises a temperature control device, a sensing optical fiber, optical fiber temperature measurement equipment and an electronic thermometer, the temperature control device is provided with a temperature adjusting unit for controlling the temperature change; at least one section of the sensing optical fiber is placed in the temperature control device, the sensing optical fiber is provided with the optical fiber temperature measuring equipment and the electronic thermometer, and the optical fiber temperature measuring equipment and the electronic thermometer are used for measuring the temperature of the sensing optical fiber part placed in the temperature control device. According to the calibration device, non-linear calibration is carried out on the whole sensing optical fiber by using the measured value of the high-precision thermometer, and the obtained wide-temperature-range calibration parameter can be applied to the measurement point of the whole sensing optical fiber and has good precision.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber temperature measurement. Background Art

[0002] Distributed fiber temperature measurement system (DTS) is a widely used temperature measurement technology. DTS obtains the SLE (slope) and CAL (calibration) parameters of the optical fiber through temperature measurement experiments in advance, and calibrates the optical fiber temperature measurement based on these parameters. During the temperature measurement experiment, the DTS device confirms the SLE and CAL parameters by measuring the temperature of two sections of optical fiber placed in different constant temperature (T1, T2) devices. When the temperature difference between T1 and T2 is small, it can be assumed that the measurement result is in line with linear changes. When the measurement temperature range is large, the measurement result between T1 and T2 is usually nonlinear. If the two constant temperature oil tanks are 30℃ and 60℃ respectively, the SLE and CAL parameters calibrated by these two devices can generally only ensure that the temperature measurement in the temperature range of 30℃ to 60℃ will be relatively accurate, but the temperature measurement far below 30℃ or far above 60℃ will have a large error. This error is caused by the nonlinearity of the system. Therefore, there is room for improvement in the existing DTS calibration method. Utility Model Content

[0003] The technical problem solved by the present disclosure is to provide a calibration device for distributed optical fiber temperature measurement.

[0004] The utility model solves the technical problem by adopting the following technical solution: a calibration device for a distributed optical fiber temperature measurement sensing system, the calibration device comprising a temperature control device, a sensing optical fiber, an optical fiber temperature measurement device and an electronic thermometer; the temperature control device has a temperature adjustment unit to control temperature changes; at least one section of the sensing optical fiber is placed in the temperature control device, the sensing optical fiber is provided with the optical fiber temperature measurement device and the electronic thermometer, and the optical fiber temperature measurement device and the electronic thermometer measure the temperature of the sensing optical fiber portion placed in the temperature control device.

[0005] As described above, in the calibration device for a distributed optical fiber temperature sensing system, the sensing optical fiber extends out of the temperature control device and is connected to the optical fiber temperature measuring device.

[0006] As described above, in the calibration device for a distributed optical fiber temperature sensing system, the electronic thermometer has a probe, and the probe extends into the temperature control device to contact the sensing optical fiber.

[0007] As described above, in the calibration device for a distributed optical fiber temperature sensing system, the temperature control device has a limiting structure to ensure that the probe maintains stable contact with the sensing optical fiber.

[0008] In the calibration device of a distributed optical fiber temperature sensing system as described above, the limiting structure is a box, a section of the sensing optical fiber enters the temperature control device and is accommodated in the box, and the probe extends into the box.

[0009] The beneficial effects of the present disclosure are as follows: In the distributed optical fiber temperature measurement and calibration device, an electronic thermometer and a distributed optical fiber temperature measurement device are used to measure the same section of optical fiber, and a functional relationship is constructed based on the temperature values ​​measured by the two to obtain the temperature value after the distributed optical fiber temperature measurement calibration. This can be used in environments with a large measurement temperature range to obtain better results. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Some specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings in an exemplary but non-restrictive manner, in which the same reference numerals indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale.

[0011] In the attached figure:

[0012] Figure 1 This is a schematic diagram of the calibration device of the utility model;

[0013] Figure 2 This is the temperature measurement curve of the distributed optical fiber temperature measurement equipment (DTS) before calibration;

[0014] Figure 3 It is the temperature measurement curve of the electronic thermometer;

[0015] Figure 4 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer before calibration;

[0016] Figure 5 This is a comparison chart of the 0℃ temperature measurement curves of DTS and electronic thermometer before calibration;

[0017] Figure 6 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer at 30℃ before calibration;

[0018] Figure 7 This is a comparison chart of the 60℃ temperature measurement curves of DTS and electronic thermometer before calibration;

[0019] Figure 8 This is a comparison chart of the 90℃ temperature measurement curves of DTS and electronic thermometer before calibration;

[0020] Fig. 9 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer at 120℃ before calibration;

[0021] Fig.10 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer at 139℃ before calibration;

[0022] Fig.11 This is the DTS temperature measurement curve after calibration;

[0023] Fig.12 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer after calibration;

[0024] Fig.13 This is a comparison chart of the 0℃ temperature measurement curves of DTS and electronic thermometer after calibration;

[0025] Fig.14 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer at 30℃ after calibration;

[0026] Fig.15 This is a comparison chart of the 60℃ temperature measurement curves of the calibrated DTS and electronic thermometer;

[0027] Fig.16 This is a comparison chart of the 90℃ temperature measurement curves of the calibrated DTS and electronic thermometer;

[0028] Fig.17 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer at 120℃ after calibration;

[0029] Fig.18 This is a comparison chart of the temperature measurement curves of DTS and electronic thermometer at 139℃ after calibration; DETAILED DESCRIPTION

[0030] To make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments.

[0031] Based on the described embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Unless otherwise defined, the technical terms or scientific terms used in this disclosure should be the common meanings understood by people with ordinary skills in the field to which the utility model belongs.

[0032] The words "first", "second" and similar terms used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" do not indicate a quantitative limitation, but rather indicate the presence of at least one. Words such as "include" or "comprise" and similar terms mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0033] See attached Figure 1 , a calibration device for implementing the above-mentioned calibration method is provided, the calibration device includes a temperature control device, a sensing optical fiber, an optical fiber temperature measuring device and an electronic thermometer; the temperature control device has a temperature adjustment unit to control temperature changes; at least one section of the sensing optical fiber is placed in the temperature control device, the sensing optical fiber is equipped with the optical fiber temperature measuring device and the electronic thermometer, and the optical fiber temperature measuring device and the electronic thermometer measure the temperature of the sensing optical fiber portion placed in the temperature control device.

[0034] The temperature control device equipped with a temperature adjustment unit can use a temperature cycle test box. The sensing optical fiber placed in the temperature control device extends to the outside and is connected to the optical fiber temperature measuring device, so that the optical fiber temperature measuring device can obtain the temperature of the sensing optical fiber in the temperature control device in real time.

[0035] A high-precision electronic thermometer is used. The specific accuracy requirement can be selected according to the required accuracy of the measurement. For example, an electronic thermometer with an accuracy of 0.05 is selected. The electronic thermometer has a probe, which is inserted into the temperature control device to maintain contact with the sensing optical fiber so as to continuously obtain the temperature of this part of the sensing optical fiber in real time.

[0036] In some embodiments, the temperature control device has a limiting structure to keep the probe in stable contact with the sensing optical fiber. The limiting structure can be a box, a section of the sensing optical fiber enters the temperature control device and is accommodated in the box, and the probe extends into the box.

[0037] A calibration method for a distributed optical fiber temperature sensing system is provided. The calibration method comprises the following steps: placing a section of sensing optical fiber in a temperature control device capable of adjusting the temperature; adjusting the temperature of the temperature control device so that the temperature of the temperature control device remains stable at a plurality of preset temperature points; measuring the temperature values ​​of the sensing optical fiber at the corresponding temperature points by an optical fiber temperature measuring device and an electronic thermometer; and using the temperature values ​​X and Y measured by the optical fiber temperature measuring device and the electronic thermometer at the plurality of temperature points, as well as the equation: Y=a0+a1X+a2X 2 +…+a n X n Construct an n-order system of equations, where n is less than the number of temperature points; solve the n-order system of equations to obtain the polynomial coefficients a0, a1, a2, ...a n ;

[0038] Construct functions using polynomial coefficients:

[0039] The temperature value of the optical fiber temperature measuring device after calibration = a0+a1T+a2T 2 +…+a n T n , T is the temperature value measured by the optical fiber temperature measuring device before calibration.

[0040] The preferred number of n is the number of temperature points minus 1. For example, if 5 temperature points are selected, n is 4. When the temperature control device is stable at multiple temperature points, the corresponding temperature values ​​measured by the electronic thermometer are Y1, Y2, ...Y n When the temperature control device is stable at multiple temperature points, the corresponding temperature values ​​measured by the optical fiber temperature measuring device are X1, X2, ...X n , the constructed n-order equation system is:

[0041] Y1=a0+a1X1+a2X1 2 +…+a n X1 n

[0042] Y2=a0+a1X2+a2X2 2 +…+a n X2 n

[0043] Y3=a0+a1X3+a2X3 2 +…+a n X3 n

[0044] …

[0045] Y n =a0+a1X n +a2X n 2 +…+an X n n .

[0046] By solving the equations, we can obtain the polynomial coefficients a0, a1, a2, ...a n Then substitute the value of a0+a1T+a2T 2 +…+a n T n , you can get the calibrated optical fiber measurement temperature value.

[0047] In some embodiments, the fiber optic temperature measurement device is connected to a sensing optical fiber, a section of which is placed in the temperature control device, the sensing optical fiber is equipped with a high-precision electronic thermometer, and the probe of the electronic thermometer enters the temperature control device and measures the temperature of the sensing optical fiber.

[0048] In some embodiments, the temperature control device is provided with a limiting member for maintaining stable contact between the sensing optical fiber and the probe of the electronic thermometer. The limiting member allows the probe of the electronic thermometer to be together with the sensing optical fiber in the temperature control device, ensuring that the electronic thermometer performs real-time temperature measurement on the sensing optical fiber.

[0049] The temperature control device is adjusted to change the temperature therein and remain stable at multiple temperature points so that the DTS device and the electronic thermometer can measure the temperature of the sensing optical fiber in the temperature control device at the corresponding temperature point. The temperature change of the temperature control device can be heating or cooling. It is preferred to control the temperature control device to remain stable at a preset temperature point during the heating process.

[0050] Specifically, the DTS device is connected to a sensing optical fiber. A box-shaped limiting structure is placed in the temperature cycling test box. A section of the sensing optical fiber (such as 10 meters) is placed in the box inside the temperature control device. In addition, a probe of a high-precision electronic thermometer is extended into the box and placed together with the sensing optical fiber. Both the DTS device and the high-precision electronic thermometer record the temperature value at the sensing optical fiber in the box in real time.

[0051] Adjust the temperature of the temperature cycle test box so that the temperature value gradually rises from the lowest value to the highest value, and stays at the specified temperature points in the middle to wait for the temperature to stabilize. For example, the temperature in the temperature cycle test box rises to 60°C, and the temperature is maintained until the electronic thermometer measures a stable temperature value through the probe for a period of time (for example, one hour), which is generally around 60°C, and then the temperature cycle test box is controlled to rise to the next temperature stability point, such as 90°C, and so on, and stays at multiple temperature points to stabilize and measure the temperature value.

[0052] After stabilization and measurement of multiple temperature points, the temperature data of the DTS device is exported to determine the stabilization time and corresponding temperature value of each temperature point, as shown in Table 1 and Appendix. Figure 2 As shown,

[0053] time Distributed optical fiber temperature measurement equipment measurement value t1 x1 t2 x2 t3 x3 t4 x4 t5 x5 t6 x6

[0054] Table 1

[0055] Export the temperature data of the high-precision electronic thermometer and determine the stabilization time of each temperature point and the corresponding temperature value, as shown in Table 2 and Appendix Figure 3 As shown,

[0056] time High-precision electronic thermometer measurement value t1 y1 t2 y2 t3 y3 t4 y4 t5 y5 t6 y6

[0057] Table 2

[0058] See attached Figure 4-10 By comparing the measurement values ​​of the high-precision electronic thermometer and the distributed optical fiber temperature measurement equipment, it can be found that both have certain deviations at various stable temperature points, such as 0℃, 30℃, 60℃, 90℃, 120℃, and 139℃, with the maximum value close to 1℃.

[0059] The n-order equation group is constructed using the electronic thermometer measurement values ​​and the distributed optical fiber temperature measurement device measurement values ​​when the temperature is stable. n is less than the number of stable points. It is preferred that n is 1 less than the number of stable points, which is beneficial to improving the accuracy of calibration. For example, if there are 6 stable points, a maximum of 5-order equation group can be constructed.

[0060]

[0061] At the six stable points of 0℃, 30℃, 60℃, 90℃, 120℃, and 139℃, the measured values ​​of the distributed optical fiber temperature measurement equipment and the electronic thermometer are shown in Table 3.

[0062] time DTS measurement value (℃) High-precision thermometer measurement value (℃) t1 0.76359 1.46 t2 30.5634 30.4 t3 61.1458 60.68 t4 90.5604 89.92 t5 120.16 120.04 t6 136.506 137.2

[0063] Using the above, we can build a system of equations:

[0064] 1.46=a0+a1*0.76359+a2*(0.76359) 2 +a3*(0.76359) 3 +a4*(0.76359) 4 +a5*(0.76359) 5

[0065] 30.4=a0+a1*30.5634+a2*(30.5634) 2 +a3*(30.5634) 3 +a4*(30.5634) 4+a5*(30.5634) 5

[0066] 60.68=a0+a1*61.1458+a2*(61.1458) 2 +a3*(61.1458) 3 +a4*(61.1458) 4 +a5*(61.1458) 5

[0067] 89.92=a0+a1*90.5604+a2*(90.5604) 2 +a3*(90.5604) 3 +a4*(90.5604) 4 +a5*(90.5604) 5

[0068] 120.04=a0+a1*120.16+a2*(120.16) 2 +a3*(120.16) 3 +a4*(120.16) 4 +a5*(120.16) 5

[0069] 137.2=a0+a1*136.506+a2*(136.506) 2 +a3*(136.506) 3 +a4*(136.506) 4 +a5*(136.506) 5 Solve the above polynomial equations and get the polynomial coefficients a0, a1, a2, ..., an as shown in the following table:

[0070] coefficient value a0 0.742603 a1 0.938248 a2 0.00166511 a3 -2.49194e-05 a4 1.68992e-07 a5 -3.78463e-10

[0071] Use the coefficients in the table above to construct a conversion function to obtain the temperature value of the distributed optical fiber temperature measurement device after calibration:

[0072] 0.742603+0.938248x+0.00166511x 2 +-2.49194e-05x 3 +1.68992e-07x 4 +-3.8463e-10x 5

[0073] Use the above formula to recalculate the temperature value (after calibration) measured by the distributed optical fiber temperature measurement device and the error value of each temperature point. Figure 11-18It can be seen that after calibration, the error between the temperature value measured by the distributed optical fiber temperature measurement device and the temperature value measured by the high-precision electronic thermometer is reduced, thereby improving the measurement accuracy.

[0074] In summary, this calibration device uses the measurement values ​​of a high-precision thermometer to perform nonlinear calibration on the entire sensing optical fiber. The obtained wide temperature range calibration parameters can be applied to the measurement points of the entire sensing optical fiber, and can also be used in the wide temperature range calibration of other types of distributed temperature sensors.

[0075] The above description is only the preferred embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications, combinations and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the scope of the claims of the utility model.

Claims

1. A calibration device for a distributed optical fiber temperature sensing system, characterized in that: The calibration device includes a temperature control device, a sensing optical fiber, an optical fiber temperature measuring device and an electronic thermometer; The temperature control device has a temperature adjustment unit to control temperature changes; At least one section of the sensing optical fiber is placed in the temperature control device. The sensing optical fiber is equipped with the optical fiber temperature measuring device and the electronic thermometer. The optical fiber temperature measuring device and the electronic thermometer measure the temperature of the sensing optical fiber portion placed in the temperature control device.

2. A calibration device for a distributed optical fiber temperature sensing system according to claim 1, characterized in that: The sensing optical fiber extends out of the temperature control device and is connected to the optical fiber temperature measuring equipment.

3. A calibration device for a distributed optical fiber temperature sensing system according to claim 2, characterized in that: The electronic thermometer has a probe which extends into the temperature control device to contact the sensing optical fiber.

4. A calibration device for a distributed optical fiber temperature sensing system according to claim 3, characterized in that: The temperature control device has a limiting structure to ensure that the probe and the sensing optical fiber maintain stable contact.

5. A calibration device for a distributed optical fiber temperature sensing system as claimed in claim 4, characterized in that: The limiting structure is a box body, a section of the sensing optical fiber enters the temperature control device and is accommodated in the box body, and the probe extends into the box body.

Images