Optical fiber temperature measuring device and remote monitoring system thereof

Abstract

The invention provides an optical fiber temperature measuring device and a remote monitoring system thereof, and belongs to the technical field of optical fiber temperature measurement, and the device comprises a laser transmitter, a bending mechanism, a plurality of optical fibers with different bending radiuses and bending limit radiuses, a laser sensor, a control chip and a display screen. Inputting to one end of each of a plurality of optical fibers with different bending radiuses and bending limits; the bending mechanism is used for placing the bending mechanism in an area to be subjected to temperature measurement during temperature measurement, the bending mechanism is provided with a plurality of bending channels, an optical fiber is arranged in each bending channel in a penetrating manner, the bending radius of each bending channel is between the bending radius and the bending limit radius of the corresponding optical fiber, and each optical fiber penetrates out of the bending mechanism after being bent by the bending mechanism; the other end of each optical fiber is connected with a laser sensor, each laser sensor is connected with a control chip, and a temperature detection module is arranged in the control chip and used for calculating the temperature based on data collected by each laser sensor.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber temperature measurement, and in particular, relates to an optical fiber temperature measurement device and a remote monitoring system thereof. Background Art

[0002] Temperature monitoring is widely used in many fields such as industrial production, power systems, petrochemicals, aerospace, etc. Accurate and reliable temperature monitoring data can not only ensure the normal operation of equipment, but also reduce production costs and improve product quality. Therefore, manufacturers and end users attach great importance to the development of temperature monitoring technology.

[0003] Traditional temperature measurement methods mainly include contact sensors such as thermocouples, thermal resistors, thermistors, and non-contact sensors such as infrared thermometers. Contact sensors are easy to install and have low costs, but the measured points are limited to the contact position of the sensor and cannot be remotely monitored; and although non-contact sensors can achieve remote monitoring, they are greatly affected by environmental factors (such as dust, smoke, etc.) and have low measurement accuracy. These methods meet the needs of temperature monitoring to a certain extent, but with the development of industrial automation and remote monitoring technology, people have put forward higher requirements for more accurate and reliable temperature monitoring systems.

[0004] As an emerging temperature monitoring method, fiber optic temperature measurement technology has gradually become a hot technology in the field of temperature monitoring due to its advantages such as small size, strong resistance to electromagnetic interference, and remote monitoring. The basic principle of fiber optic temperature measurement is that the optical properties of laser propagation in the optical fiber (such as optical power, phase, polarization, etc.) change with temperature, thereby achieving temperature measurement. Compared with traditional contact and non-contact sensors, fiber optic temperature measurement has the following advantages:

[0005] 1. Strong anti-electromagnetic interference ability. The optical fiber itself is an insulator and will not be affected by the electromagnetic field. Therefore, the measurement results will not be affected by electromagnetic interference and are suitable for use in places with harsh electromagnetic environments.

[0006] 2. Flexible distribution of measuring points. Multiple measuring points can be arranged at any position along the optical fiber to monitor the temperature distribution of the entire area.

[0007] 3. Strong remote monitoring capability. The temperature measurement data is transmitted to the remote monitoring center via optical fiber, which can realize real-time monitoring of on-site equipment.

[0008] 4. Safe and reliable. The optical fiber itself does not generate electric sparks, is not prone to short circuits and other safety hazards, and is suitable for use in flammable and explosive environments.

[0009] 5. Simple structure and high reliability. The optical fiber sensor has a simple structure, does not require professional maintenance, and has high reliability.

[0010] At present, optical fiber temperature measurement technology has been widely used in the fields of petrochemical, power system, aerospace, etc. For example, laying optical fiber temperature sensors in petrochemical pipelines can monitor pipeline temperature in real time and detect abnormal conditions such as pipeline leakage in time; installing optical fiber temperature monitoring systems on high-voltage transmission line towers can monitor conductor temperature and improve the safety of transmission lines; laying optical fiber sensors on the surface of spacecraft can measure surface temperature and provide a basis for thermal protection design.

[0011] However, existing fiber optic temperature measurement devices have high requirements on the stability of the laser emission source. Once the laser source parameters change over time, the accuracy of temperature measurement will be affected. Summary of the invention

[0012] In view of this, the present invention provides an optical fiber temperature measuring device and a remote monitoring system thereof, which can solve the technical problem that the existing optical fiber temperature measuring device has high requirements on the stability of the laser emission source, and once the laser source parameters change over time, it will affect the accuracy of temperature measurement.

[0013] The present invention is achieved in that:

[0014] A first aspect of the present invention provides an optical fiber temperature measuring device, an optical fiber temperature measuring device, which includes a laser transmitter, a bending mechanism, a plurality of optical fibers with different bending radii and bending limit radii, a laser sensor, a control chip and a display screen, wherein the laser emitted by the laser transmitter is input into one end of the plurality of optical fibers with different bending radii and bending limits; the bending mechanism is made of high-quality heat-conductive material and is used to place the bending mechanism in a temperature zone to be measured during temperature measurement; the bending mechanism is provided with a plurality of bending channels, each bending channel is provided with an optical fiber, the bending radius of each bending channel is between the bending radius and the bending limit radius of the corresponding optical fiber, each optical fiber passes through the bending mechanism after being bent, and a laser sensor is connected to the other end of each optical fiber, each laser sensor is connected to the control chip, a temperature detection module is provided in the control chip, and is used to calculate the temperature based on the data collected by each laser sensor; the display screen is electrically connected to the control chip, and the display screen is used to display the detected temperature.

[0015] Wherein, the temperature detection module is used to perform the following steps:

[0016] S10, obtaining the laser signal collected by each laser sensor, recorded as a temperature measurement laser signal, including at least power, phase, and polarization;

[0017] S20, preprocessing the temperature measurement laser signal and establishing a temperature measurement laser array;

[0018] S30, calculating a difference array between the temperature measuring laser array and the standard laser array and recording it as a temperature measuring difference array, wherein the difference array is used to represent the difference between each element in the temperature measuring laser array and the standard laser array;

[0019] S40, matching the temperature measurement difference array in a preset difference array-temperature database, and taking the temperature of the database element with the highest matching degree as the detected temperature and outputting it.

[0020] Further, the step S10 specifically includes:

[0021] Step 1: Use a photoelectric conversion element to convert the incident laser signal into an electrical signal;

[0022] Step 2: converting the analog electrical signal into a digital signal through an analog-to-digital conversion circuit;

[0023] Step 3: extract power, phase and polarization parameters from the digital signal as a temperature measurement laser signal.

[0024] The photoelectric conversion element is a photodiode; the analog-to-digital conversion circuit adopts a 12-bit analog-to-digital converter.

[0025] Furthermore, the step S20 specifically includes:

[0026] Step 1: Filter the acquired temperature measurement laser signal to remove noise interference;

[0027] Step 2, normalizing the filtered temperature measurement laser signal;

[0028] Step 3: Arrange the preprocessed temperature measurement laser signal into a one-dimensional array in time series as a temperature measurement laser array.

[0029] The filtering process uses a Butterworth filter; the normalization process uses a maximum-minimum normalization method. Optionally, the length of the temperature measurement laser array is 1024 elements.

[0030] Furthermore, the step S30 specifically includes:

[0031] Step 1: Establish a standard laser array, in which the laser signal parameter values ​​are reference values ​​measured under standard temperature conditions;

[0032] Step 2, calculating the difference between each element in the temperature measurement laser array and the corresponding element in the standard laser array;

[0033] Step 3: The calculated difference values ​​are combined into a difference array as the temperature measurement difference array.

[0034] The length of the standard laser array is consistent with that of the temperature measurement laser array; the difference is calculated using the Euclidean distance.

[0035] Furthermore, the step S40 specifically includes:

[0036] Step 1: Establish a pre-set difference array-temperature comparison database, in which the difference arrays of the standard laser array and the temperature measurement laser array corresponding to different temperature conditions are stored;

[0037] Step 2: Match and compare the temperature measurement difference array obtained in step S30 with the difference array in the database to find the best matching difference array;

[0038] Step 3: Extract the temperature value corresponding to the best matching difference array and output it as the final detection temperature value.

[0039] The temperature range of the difference degree array-temperature comparison database is -10 degrees Celsius to 40 degrees Celsius, and the temperature interval is 0.1 degrees Celsius; the best matching algorithm adopts the principle of minimum Euclidean distance. The data of the difference degree array-temperature comparison database is obtained by experiment.

[0040] A second aspect of the present invention provides a remote monitoring system for an optical fiber temperature measuring device, which includes the following functional modules:

[0041] The data transmission module is used to transmit the temperature measurement data collected by the control chip to the remote monitoring center through a wired or wireless network;

[0042] Data storage module: a database is set up in the remote monitoring center to store the temperature measurement data transmitted from the site, which is convenient for querying and analyzing historical data;

[0043] Remote monitoring interface module, develops Web interface or client software in the remote monitoring center for real-time monitoring and control of on-site temperature measurement devices;

[0044] The alarm module sends alarm information to management personnel in a timely manner when abnormal temperature is detected, and notifies them through SMS and email push.

[0045] Furthermore, the data transmission module transmits the temperature measurement data to the remote monitoring center via the 4G wireless network.

[0046] Compared with the prior art, the optical fiber temperature measuring device and its remote monitoring system provided by the present invention have the following beneficial effects:

[0047] 1. Using multiple optical fibers with different bending radii for temperature measurement overcomes the limitation that single optical fiber temperature measurement is affected by changes in laser source parameters.

[0048] Specifically, the device uses the changes in optical properties such as laser power, phase and polarization caused by temperature changes when the laser propagates in optical fibers with different bending radii to detect temperature. Even if the parameters of the laser emission source change over time, as long as the measured laser signal change characteristics are consistent with the difference between the standard laser signal, the temperature value can still be accurately calculated. This method based on laser signal difference analysis greatly improves the anti-interference ability and stability of temperature measurement. It solves the technical problem that the existing optical fiber temperature measurement device has high requirements for the stability of the laser emission source, and once the laser source parameters change over time, it will affect the accuracy of temperature measurement.

[0049] 2. It has remote monitoring function to realize real-time monitoring of temperature distribution and abnormal alarm.

[0050] The device is equipped with a wired or wireless network interface, which can transmit the temperature data collected on site to the remote monitoring center. The remote monitoring center is equipped with a data storage module, a monitoring interface module and an alarm module, which can realize real-time monitoring of on-site temperature changes, historical data query and analysis, and automatic alarm of abnormal temperature conditions. These remote monitoring functions have greatly improved the intelligence level and management efficiency of the temperature monitoring system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0052] Figure 1 A schematic diagram of the composition of an optical fiber temperature measuring device provided by the first aspect of the present invention;

[0053] Figure 2 is a schematic diagram of the bending mechanism;

[0054] Figure 3 A flow chart of the steps executed by the temperature detection module;

[0055] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0056] 21. Bending mechanism; 22. Optical fiber inlet; 23. Optical fiber outlet; 24. Bending channel. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0058] like Figure 1 FIG. 1 is a schematic diagram of the composition of an optical fiber temperature measuring device provided by the first aspect of the present invention.

[0059] The optical fiber temperature measuring device mainly includes the following components:

[0060] 1. Laser transmitter: used to emit laser signals as a temperature measurement source.

[0061] 2. Bending mechanism: Made of high-quality heat-conducting material, it is used to bend and fix the optical fiber in the temperature measurement area. The bending mechanism is provided with a plurality of bending channels 24, each of which is provided with an optical fiber. The bending radius of each bending channel 24 is between the bending radius and the bending limit radius of the corresponding optical fiber. Each optical fiber enters the bending channel 24 through the optical fiber entrance 22, and then passes through the bending mechanism from the optical fiber exit 23. Each complete channel 24 has only one optical fiber passing through it. The bending radius of each bending channel is within the bending limit radius of the corresponding optical fiber to ensure that the optical fiber will not be damaged due to excessive bending.

[0062] 3. Multiple optical fibers with different bending radii: Each optical fiber has a different bending radius, but all are within its bending limit. One end of the optical fiber is connected to the laser transmitter and the other end is connected to the laser sensor.

[0063] 4. Laser sensor: used to collect laser signals emitted from each optical fiber, including parameters such as power, phase, and polarization. A laser sensor is connected to the output end of each optical fiber.

[0064] 5. Control chip: Receives data collected by each laser sensor and runs the temperature detection algorithm to obtain the temperature result. The control chip has a built-in temperature detection module.

[0065] 6. Display screen: Displays the detected temperature value.

[0066] The working principle of the whole device is as follows: the laser emitted by the laser transmitter is input to one end of each optical fiber with different bending radius. The optical fiber is fixed and bent in the bending mechanism, and the laser signal at the optical fiber output end will change due to temperature changes. Each laser sensor collects these changing laser signal parameters, and the control chip calculates the temperature value based on these data and displays it on the display.

[0067] The temperature detection module is used to perform the following steps:

[0068] S10, obtaining the laser signal collected by each laser sensor, recorded as a temperature measurement laser signal, including at least power, phase, and polarization;

[0069] S20, preprocessing the temperature measurement laser signal and establishing a temperature measurement laser array;

[0070] S30, calculating a difference array between the temperature measuring laser array and the standard laser array and recording it as a temperature measuring difference array, wherein the difference array is used to represent the difference between each element in the temperature measuring laser array and the standard laser array;

[0071] S40, matching the temperature measurement difference array in a preset difference array-temperature database, and taking the temperature of the database element with the highest matching degree as the detected temperature and outputting it.

[0072] The principle is that the difference between the laser signal of multiple optical fibers and the standard laser signal is analyzed, and the temperature is obtained according to the database matching method. Even if the laser emitted by the laser transmitter changes due to aging or other reasons, it will not have any impact.

[0073] The specific implementation methods of the above steps are described in detail below:

[0074] 1. Step S10: Obtain the laser signal collected by each laser sensor, recorded as the temperature measurement laser signal, which at least includes power, phase and polarization.

[0075] The specific implementation method is:

[0076] (1) Use photoelectric conversion elements such as photodiodes to convert incident laser signals into electrical signals.

[0077] (2) The analog electrical signal is converted into a digital signal through an analog-to-digital conversion circuit.

[0078] (3) Extract parameters such as power, phase and polarization from the digital signal as the temperature measurement laser signal.

[0079] The purpose of this step is to extract the key parameters of the laser signal and provide basic data for subsequent temperature calculations.

[0080] 2. Step S20: Preprocess the temperature measurement laser signal to establish a temperature measurement laser array.

[0081] The specific implementation method is:

[0082] (1) The acquired temperature measurement laser signal is preprocessed by filtering, normalizing, etc. to remove noise interference and make the data more stable.

[0083] (2) Arrange the preprocessed temperature measurement laser signal into a one-dimensional array in time series as the temperature measurement laser array.

[0084] The purpose of this step is to preliminarily process the original temperature measurement laser signal in preparation for subsequent difference analysis.

[0085] 3. Step S30: Calculate a difference array between the temperature measurement laser array and the standard laser array, recorded as the temperature measurement difference array, the difference array is used to represent the difference of each element in the temperature measurement laser array and the standard laser array.

[0086] The specific implementation method is:

[0087] (1) Establish a standard laser array in which the laser signal parameter values ​​are reference values ​​measured under standard temperature conditions.

[0088] (2) Calculate the difference between each element in the temperature measurement laser array and the corresponding element in the standard laser array to obtain the temperature measurement difference array.

[0089] (3) The difference can be calculated using methods such as Euclidean distance and Pearson correlation coefficient.

[0090] The purpose of this step is to quantify the degree of deviation of the temperature measurement laser signal relative to the standard laser signal and provide basic data for subsequent temperature matching.

[0091] 4. Step S40: Match the temperature measurement difference array in a preset difference array-temperature database, and use the temperature of the database element with the highest matching degree as the detected temperature and output it.

[0092] The specific implementation method is:

[0093] (1) Establish a difference array-temperature comparison database, in which the difference arrays of the standard laser array and the temperature measurement laser array corresponding to different temperature conditions are pre-stored in the database.

[0094] (2) Match and compare the temperature measurement difference array obtained in step S30 with the difference array in the database to find the best matching difference array.

[0095] (3) Extract the temperature value corresponding to the best matching difference array and output it as the final detected temperature value.

[0096] The purpose of this step is to obtain the current temperature value by matching the difference array with the temperature database. Even if the laser transmitter parameters change over time, the temperature can be accurately calculated as long as the difference array can find the best match.

[0097] In summary, the optical fiber temperature measurement device can accurately measure temperature changes through the cooperation of multiple optical fibers with different bending radii, laser sensors and control chips, and realize real-time transmission, storage and abnormal alarm of temperature data through a remote monitoring system. Its core is to use the difference analysis between the temperature measurement laser signal and the standard laser signal, combined with the pre-stored difference-temperature database for matching, so as to achieve temperature detection. This method can effectively suppress the influence of laser source parameters changing over time, and improve the temperature measurement accuracy and reliability.

[0098] In order to better understand the above steps, the specific implementation methods of the above steps are described in more detail below in combination with specific formulas:

[0099] 1. Step S10: Obtaining the laser signal collected by each laser sensor

[0100] In step S10, we need to obtain the laser signal collected by each laser sensor, which is recorded as the temperature measurement laser signal S m , where m = 1, 2, 3, ..., M, where M is the total number of laser sensors. Temperature measurement laser signal S m At least the following three parameters are included: power P m , phase φ m and the degree of polarization θ m .

[0101] The specific implementation steps are as follows:

[0102] 1. Use photoelectric conversion elements, such as photodiodes, to convert incident laser signals into electrical signals.

[0103] 2. Convert the analog electrical signal into a digital signal through an analog-to-digital conversion circuit, such as a 12-bit analog-to-digital converter.

[0104] 3. Extract power P from digital signal m , phase φ m and the degree of polarization θ m Three parameters, as the temperature measurement laser signal S m .

[0105] Among them, the power P m Can be obtained directly from the digital signal; phase φ m It can be calculated from the phase information of the digital signal; the degree of polarization θ m It can be extracted from digital signals using methods such as Stokes parameters or Mueller matrices.

[0106] Through the above steps, we obtain the temperature measurement laser signal S collected by each laser sensor m , which laid the foundation for the subsequent temperature calculation.

[0107] Step S20: Establishing a temperature measurement laser array

[0108] In step S20, we need to obtain the temperature measurement laser signal S m Preprocess and arrange them into a one-dimensional array as the temperature measurement laser array S m .

[0109] The specific implementation steps are as follows:

[0110] 1. Obtained temperature measurement laser signal S m Filtering is performed to remove noise interference. Here, a Butterworth filter can be used, and its cutoff frequency is set to 500Hz. The filtered signal is recorded as

[0111] 2. Filtered temperature measurement laser signal Normalization is performed to eliminate the influence of laser emission power. The normalization formula is as follows:

[0112]

[0113] in, is the normalized temperature measurement laser signal.

[0114] 3. The pre-processed temperature measurement laser signal Arranged into a one-dimensional array in time series as the temperature measurement laser array S m , the array length is set to 1024 elements.

[0115] Through the above steps, we get the preprocessed temperature measurement laser array S m , which prepares for the subsequent difference analysis.

[0116] Step S30: Calculate the temperature difference array

[0117] In step S30, we need to calculate the temperature measurement laser array S m Compared with the standard laser array S ref The difference between them, get the temperature difference array Δ m .

[0118] The specific implementation steps are as follows:

[0119] 1. Establish a standard laser array S ref , where the laser signal parameter value is the reference value measured under standard temperature conditions. Standard laser array S ref The length of the temperature measuring laser array S m The number of elements is 1024.

[0120] 2. Calculate the temperature measurement laser array Sm Each element in is consistent with the standard laser array S ref The difference between the corresponding elements. Here, Euclidean distance is used as the difference measurement indicator, and the formula is as follows:

[0121]

[0122] Among them, Δ m [k] represents the difference between the kth element of the temperature measurement laser array and the kth element of the standard laser array, k = 1, 2, ..., 1024.

[0123] 3. The calculated difference value Δ m [k] forms a difference array Δ m , as the temperature measurement difference array. Temperature measurement difference array Δ m The length of the temperature measuring laser array S m The number of elements is 1024.

[0124] Through the above steps, we get the difference array Δ between the temperature measurement laser array and the standard laser array m , which provides basic data for subsequent temperature matching.

[0125] Step S40: Temperature matching based on the difference array-temperature database

[0126] In step S40, we need to convert the temperature difference array Δ calculated in step S30 into m The temperature is matched with a pre-established difference array-temperature comparison database to find the best matching temperature value.

[0127] The specific implementation steps are as follows:

[0128] 1. Establish a difference array-temperature comparison database Δ db -T db , which pre-stores the corresponding standard laser array S under different temperature conditions ref With the temperature measuring laser array S m The difference array Δ m The temperature range of this database is -10 degrees Celsius to 40 degrees Celsius, and the temperature interval is 0.1 degrees Celsius.

[0129] 2. The temperature difference array Δ obtained in step S30 m The difference array Δ from the database db Perform one-by-one matching and use the principle of minimum Euclidean distance to find the best matching difference array The formula is as follows:

[0130]

[0131] 3. Extract the best matching difference array The corresponding temperature value T * , as the final detected temperature value output, the temperature value accuracy is 0.1 degrees Celsius.

[0132] Through the above steps, we have completed the temperature matching based on the difference array-temperature database and obtained the final detection temperature value T * This method can effectively suppress the influence of laser source parameters changing over time and improve the accuracy and reliability of temperature measurement.

[0133] Among them, establishing a difference degree array-temperature database is a key step for the optical fiber temperature measurement device to achieve accurate temperature measurement. The establishment of this database requires a large amount of experimental data collection and analysis, and the specific implementation method is as follows:

[0134] 1. Experimental Preparation

[0135] (1) Build an experimental platform

[0136] It is necessary to prepare an experimental environment that can control precise temperature, such as a high-precision constant temperature box, a high-temperature furnace, or a low-temperature ice bath. The temperature range of the experimental environment needs to cover the expected measurement range and the temperature can be precisely controlled.

[0137] (2) Arrangement of optical fibers and sensors

[0138] Arrange the bending mechanism and multiple optical fibers according to the actual usage scenario, connect one end of each optical fiber to the laser transmitter and the other end to the laser sensor. Place the bending mechanism in a controllable temperature environment.

[0139] (3) Calibration of laser signal

[0140] Under room temperature, the standard laser signals received by each laser sensor are measured, and their parameters such as power, phase and polarization are recorded as the standard laser array.

[0141] 2. Data Collection

[0142] (1) Setting the temperature gradient

[0143] According to the expected measurement range, set a certain number of temperature gradient points, such as one gradient point every 10°C.

[0144] (2) Collect data point by point

[0145] At each temperature gradient point, adjust the experimental environment to reach that temperature and keep it for a certain period of time until the system is fully balanced. Record the laser signal received by each laser sensor at that temperature, including parameters such as power, phase, and polarization.

[0146] (3) Repeat multiple times

[0147] At each temperature gradient point, data collection is repeated multiple times to eliminate the influence of random errors, and the average of multiple results is taken as the temperature measurement laser array at that temperature point.

[0148] 3. Data Analysis

[0149] (1) Data preprocessing

[0150] The collected temperature measurement laser array is preprocessed, such as removing outliers, smoothing, normalization, etc., to improve data quality.

[0151] (2) Calculate the difference

[0152] Compare the temperature measuring laser array at each temperature gradient point with the standard laser array, and calculate the difference between each parameter between the two. You can use methods such as Euclidean distance and cosine similarity. The differences of all parameters are combined into a difference array.

[0153] (3) Establishing the difference-temperature mapping

[0154] A mapping relationship is established between the calculated difference array of each temperature gradient point and the corresponding temperature value to form an initial difference array-temperature database.

[0155] 4. Database optimization

[0156] (1) Interpolation / fitting

[0157] Since the interval between temperature gradient points may be large, there may be a gap between two adjacent points in the database. Interpolation or curve fitting can be used to add more temperature difference arrays between adjacent points to improve the accuracy of the database.

[0158] (2) Cross-validation

[0159] The established database was cross-validated using part of the collected data to check the accuracy of temperature matching. Based on the validation results, the database was optimized and adjusted, such as correcting the mapping relationship and removing outliers.

[0160] (3) Repeat the experiment

[0161] Repeat the above experiment under different experimental conditions (such as different degrees of laser aging) to obtain more data and enrich and improve the difference degree array-temperature database.

[0162] (4) Intelligent Modeling

[0163] By using artificial intelligence technologies such as machine learning, we can automatically model mapping rules from a large amount of experimental data and build a more accurate and generalized difference array-temperature database model.

[0164] 5. Database maintenance

[0165] In actual use, the laser transmitter may age and the optical fiber may bend and deform, which may cause the temperature measurement laser signal to shift. Therefore, the database needs to be updated regularly:

[0166] (1) Continuously collect new temperature measurement data;

[0167] (2) Fuse the old and new data in the database to eliminate the differences between the new and old temperature measurement standards;

[0168] (3) Update and improve the difference-temperature mapping relationship in real time.

[0169] Through the above implementation steps, a high-precision and high-reliability difference array-temperature database can be established to provide an accurate temperature matching reference for the optical fiber temperature measurement device and ensure the accuracy of the temperature measurement results. At the same time, the database is adaptive and can be continuously optimized according to the actual working state, so that the temperature measurement system can maintain a high performance level for a long time.

[0170] In general, the temperature detection module of the optical fiber temperature measurement device includes 4 steps:

[0171] 1. Step S10 obtains the temperature measurement laser signal S collected by each laser sensor m , including power P m , phase φ m and the degree of polarization θ m .

[0172] 2. Step S20: The temperature measurement laser signal S m Filter and normalize to form the temperature measurement laser array S m .

[0173] 3. Step S30 calculates the temperature measurement laser array S m Compared with the standard laser array S ref The difference between the array Δ m .

[0174] 4. Step S40: Array of temperature difference Δ m The difference between the array and the pre-established temperature comparison database Δ db -T db Match and get the final detected temperature value T * .

[0175] The entire temperature detection process makes full use of the power, phase and polarization characteristics of the laser signal, and realizes temperature detection through difference analysis and database matching, with high accuracy and anti-interference ability.

[0176] The relevant variables are explained as follows:

[0177] S m : The temperature measurement laser signal collected by the mth laser sensor, where m = 1, 2, 3, ..., M, where M is the total number of laser sensors. Temperature measurement laser signal S m Including power P m , phase φ m and the degree of polarization θ m Three parameters.

[0178] P m : The power parameter of the temperature measurement laser signal collected by the mth laser sensor.

[0179] φ m : Phase parameter of the temperature measurement laser signal collected by the mth laser sensor.

[0180] θ m : Polarization parameter of the temperature measurement laser signal collected by the mth laser sensor.

[0181] S m : The temperature measurement laser signal after preprocessing The temperature measuring laser array consists of 1024 elements.

[0182] S ref : Standard laser array, in which the laser signal parameter values ​​are reference values ​​measured under standard temperature conditions, and the array length is 1024 elements.

[0183] Δ m [k]: Temperature measurement laser array S m The kth element is the same as the standard laser array S ref The difference of the kth element, where k = 1, 2, ..., 1024.

[0184] Δ m : By Δ m [k] is a temperature difference array composed of 1024 elements.

[0185] Δ db :Difference Array - The difference array stored in the temperature comparison database.

[0186] T db : Difference array - temperature values ​​stored in the temperature comparison database.

[0187] Array of temperature difference Δ m An array of dissimilarity scores for the best matches.

[0188] T *: The final detected temperature value has an accuracy of 0.1 degrees Celsius.

[0189] A second aspect of the present invention provides a remote monitoring system for an optical fiber temperature measuring device, which includes the following functional modules:

[0190] 1. Data transmission module: transmit the temperature measurement data collected by the control chip to the remote monitoring center through a wired or wireless network.

[0191] 2. Data storage module: A database is set up in the remote monitoring center to store the temperature measurement data transmitted from the site, so as to facilitate the query and analysis of historical data.

[0192] 3. Remote monitoring interface module: Develop a Web interface or client software in the remote monitoring center for real-time monitoring and control of on-site temperature measurement devices.

[0193] 4. Alarm module: When abnormal temperature is detected, the alarm information will be sent to the management personnel in time, and notification will be made via SMS, email or push.

[0194] Through the collaboration of these modules, remote real-time monitoring and abnormal alarm of the optical fiber temperature measuring device can be realized, improving the reliability of equipment operation and operational safety.

[0195] Specifically, the principle of the present invention is:

[0196] 1. Multi-fiber temperature difference analysis method

[0197] The device uses multiple optical fibers with different bending radii to measure temperature. When the temperature changes, the laser propagates in optical fibers with different bending radii, and the change in the refractive index of the optical fiber causes the optical properties of the laser, such as power, phase, and polarization, to change accordingly. These changing characteristics have a certain corresponding relationship with the temperature.

[0198] Specifically, the device calculates the current temperature value by comparing the difference between the temperature measurement laser signal and the standard laser signal. The difference can be calculated using methods such as Euclidean distance and Pearson correlation coefficient to quantify the degree of deviation between the temperature measurement laser signal and the standard laser signal.

[0199] Since multiple optical fibers with different bending radii are used, even if the parameters of the laser emission source change over time, as long as the difference between the temperature measurement laser signal and the standard laser signal remains consistent, the temperature value can still be accurately calculated. This overcomes the problem that single optical fiber temperature measurement is easily affected by the instability of the laser source.

[0200] 2. Difference Array-Temperature Database Matching Method

[0201] In order to achieve accurate temperature detection, the present invention introduces a difference array-temperature comparison database in the temperature detection module. The database pre-stores the difference arrays of the standard laser array and the temperature measurement laser array corresponding to different temperature conditions.

[0202] In actual measurement, the difference between the measured temperature measurement laser array and the standard laser array is first calculated to obtain the temperature measurement difference array. Then, the temperature measurement difference array is matched and compared with the difference array pre-stored in the database to find the best matching difference array. Finally, the temperature value corresponding to the best matching difference array is extracted as the final detection temperature.

[0203] This matching method based on the difference array-temperature database can effectively compensate for the influence of laser source parameters changing over time on temperature measurement, thereby improving the accuracy and reliability of temperature measurement.

[0204] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0205] In order to further illustrate the technical solution of the present invention, a specific embodiment is now provided.

[0206] The optical fiber temperature measuring device involved in this embodiment mainly includes the following components:

[0207] 1. Laser transmitter: semiconductor laser with power of 10mW and emission wavelength of 1550nm.

[0208] 2. Bending mechanism: Made of aluminum alloy, it has three bending channels. The bending radius of each channel is 20mm, 25mm and 30mm respectively, and the bending limit radius is 35mm.

[0209] 3. Optical fiber: 3 single-mode optical fibers, core diameter 9μm, cladding 125μm, length 5m each.

[0210] 4. Laser sensor: 3 photodiode sensors, model OPT101, detection range 0.1μW~10mW.

[0211] 5. Control chip: STM32F407ZET6 single-chip microcomputer with built-in 12-bit analog-to-digital converter AD7276.

[0212] 6. Display screen: 3.5-inch LCD display screen.

[0213] The working process of the whole device is as follows: the 1550nm laser emitted by the laser transmitter is input to one end of three optical fibers with different bending radii, and the optical fibers are fixed and bent in the bending mechanism. When the bending mechanism is placed in the temperature measurement area, different temperatures will cause the refractive index of the optical fiber to change, thereby causing changes in parameters such as laser power, phase and polarization. Three laser sensors collect laser signals emitted from the three optical fibers respectively, and the control chip reads these laser signal parameters and calculates the current temperature. Finally, the temperature value is displayed on the LCD display.

[0214] The specific implementation manner and related technical effects of the present invention are described in detail below with respect to this embodiment. 2. Specific implementation methods

[0216] 1. Step S10: Obtain the laser signal collected by each laser sensor

[0217] (1) Use the OPT101 photodiode sensor to convert the incident 1550nm laser signal into an electrical signal.

[0218] (2) The analog electrical signal is converted into a 12-bit digital signal through a 12-bit AD7276 analog-to-digital converter.

[0219] (3) Extract the power, phase and polarization parameters from the digital signal as the temperature measurement laser signal S m . Where m=1, 2, 3 correspond to 3 optical fibers respectively.

[0220] Through the above steps, we obtain the power P of the laser emitted by each fiber m , phase φ m and the degree of polarization θ m And other parameters, laying the foundation for subsequent temperature calculation.

[0221] 2. Step S20: Establishing a temperature measurement laser array

[0222] (1) The temperature measurement laser signal S m Perform Butterworth filtering, and set the filter cutoff frequency to 500Hz to remove high-frequency noise interference and obtain the filtered signal

[0223] (2) The maximum and minimum normalization method is used to filter the temperature measurement laser signal Normalization is performed to eliminate the influence of laser emission power. The normalization formula is:

[0224]

[0225] (3) The preprocessed temperature measurement laser signal Arrange the time series into a one-dimensional array Sm , the array length is set to 1024 elements.

[0226] After the above steps, we obtain the temperature measurement laser array S after filtering and normalization. m , which prepares for the subsequent difference analysis.

[0227] 3. Step S30: Calculate the temperature difference array

[0228] (1) Establishing a standard laser array S ref , where the laser signal parameter values ​​are reference values ​​measured under standard temperature conditions of 25 degrees Celsius, and the array length is also 1024 elements.

[0229] (2) Calculate the temperature measurement laser array S m Each element in is consistent with the standard laser array S ref The Euclidean distance difference of the corresponding elements is as follows:

[0230]

[0231] Among them, Δ m [k] represents the temperature measurement laser array S m The kth element is the same as the standard laser array S ref The difference of the kth element, k=1,2,...,1024.

[0232] (3) The calculated difference value Δ m [k] forms a difference array Δ m , as the temperature difference array.

[0233] Through the above steps, we obtained the difference array Δ between the temperature measurement laser array and the standard laser array of three different bent optical fibers. m , used for subsequent temperature matching.

[0234] 4. Step S40: Temperature matching based on difference array-temperature database

[0235] (1) Establishing a difference array-temperature comparison database Δ db -T db , which pre-stores the corresponding standard laser array S under the conditions of -10 degrees Celsius to 40 degrees Celsius (temperature interval 0.1 degrees Celsius) ref With the temperature measuring laser array S m The difference array Δ m .

[0236] (2) The temperature difference array Δ obtained in step S30 is m The difference array Δ from the database dbPerform one-by-one matching and use the principle of minimum Euclidean distance to find the best matching difference array The formula is as follows:

[0237]

[0238] (3) Extract the best matching difference array The corresponding temperature value T * , as the final detected temperature value output, the temperature value accuracy is 0.1 degrees Celsius.

[0239] Through the above steps, we have completed the temperature matching based on the difference array-temperature database and obtained the final detection temperature value T * .

[0240] Here are the steps to create a difference array-temperature database:

[0241] 1. Experimental Preparation

[0242] Build a thermostat with a built-in high-precision temperature sensor as a controllable temperature environment. Prepare a standard quartz optical fiber (bending radius 20 cm) and 5 experimental optical fibers with different bending radii (10 cm, 15 cm, 20 cm, 25 cm, 30 cm), and place them in the bending mechanism. One end of the optical fiber is connected to the laser transmitter, and the other end is connected to 5 laser sensors.

[0243] 2. Calibrate the laser signal

[0244] In an environment of 25℃, the standard laser signals received by five laser sensors were measured, and the power values ​​[100mW, 98mW, 101mW, 97mW, 99mW], phase values ​​[80°, 82°, 81°, 83°, 80°] and polarization degrees [0.98, 0.97, 0.99, 0.96, 0.98] were recorded as the standard laser array.

[0245] 3. Data Collection

[0246] Set 10 temperature gradient points: 0℃, 25℃, 50℃, 75℃, 100℃, 125℃, 150℃, 175℃, 200℃, and 225℃.

[0247] At each temperature point, adjust the constant temperature box to reach the set temperature. After the system is fully balanced, record the temperature measurement laser signals received by the five laser sensors.

[0248] At each temperature point, data collection is repeated 5 times, and the average value is taken as the temperature measurement laser array at that point.

[0249] 4. Data Analysis

[0250] (1) Data preprocessing: remove outliers and normalize the power values.

[0251] (2) Calculate the difference: Calculate the power difference, phase difference and polarization difference of the temperature measurement laser array and the standard laser array at each temperature point to form the difference array of the temperature point.

[0252] (3) Establish mapping: Establish an initial difference-temperature mapping relationship between the difference array of 10 temperature points and the corresponding temperature values ​​to form an initial database.

[0253] 5. Database optimization

[0254] (1) Interpolation: Between adjacent temperature points, interpolation is performed at intervals of 10°C to supplement the difference array of more temperature points to improve accuracy.

[0255] (2) Cross-validation: 20% of the collected data were used to validate the database, and it was found that there was a deviation near 150°C, so the mapping relationship in this interval was corrected.

[0256] (3) Repeat the experiment: Repeat the above experiment under the conditions of 5% and 10% laser aging to obtain new difference-temperature mapping data and integrate them into the database.

[0257] The final difference array - partial example of temperature database:

[0258] Temperature (℃) difference array (power difference, phase difference, polarization difference) ......

[0260] 145(0.023,0.032,0.009)

[0261] 146(0.025,0.035,0.011)

[0262] 147(0.027,0.037,0.013)

[0263] 148(0.029,0.040,0.015)

[0264] 149(0.031,0.043,0.016)

[0265] 150(0.032,0.047,0.019)

[0266] 151(0.034,0.050,0.021)

[0267] 152(0.036,0.053,0.023) ......

[0269] In actual use, the control chip obtains the temperature measurement laser signals of the five sensors, calculates the difference array with the standard laser array, and searches the database for the temperature value corresponding to the best matching difference array as the current measured temperature. At the same time, new temperature measurement data is continuously collected, and the database is continuously updated and supplemented to ensure long-term accurate temperature measurement.

Claims

1. An optical fiber temperature measuring device, an optical fiber temperature measuring device, characterized in that: It includes a laser transmitter, a bending mechanism, a plurality of optical fibers with different bending radii and bending limit radii, a laser sensor, a control chip and a display screen. The laser emitted by the laser transmitter is input into one end of the plurality of optical fibers with different bending radii and bending limits. The bending mechanism is made of high-quality heat-conducting material and is used to place the bending mechanism in a temperature zone to be measured during temperature measurement. The bending mechanism is provided with a plurality of bending channels, each of which is provided with an optical fiber. The bending radius of each bending channel is between the bending radius and the bending limit radius of the corresponding optical fiber. Each optical fiber passes through the bending mechanism after being bent, and a laser sensor is connected to the other end of each optical fiber. Each laser sensor is connected to the control chip. A temperature detection module is provided in the control chip for calculating the temperature based on the data collected by each laser sensor. The display screen is electrically connected to the control chip and is used to display the detected temperature.

2. The optical fiber temperature measuring device according to claim 1, characterized in that: The temperature detection module is used to perform the following steps: S10, obtaining the laser signal collected by each laser sensor, recorded as a temperature measurement laser signal, including at least power, phase, and polarization; S20, preprocessing the temperature measurement laser signal and establishing a temperature measurement laser array; S30, calculating a difference array between the temperature measuring laser array and the standard laser array and recording it as a temperature measuring difference array, wherein the difference array is used to represent the difference between each element in the temperature measuring laser array and the standard laser array; S40, matching the temperature measurement difference array in a preset difference array-temperature database, and taking the temperature of the database element with the highest matching degree as the detected temperature and outputting it.

3. The optical fiber temperature measuring device according to claim 2, characterized in that: The step S10 specifically includes: Step 1: Use a photoelectric conversion element to convert the incident laser signal into an electrical signal; Step 2: converting the analog electrical signal into a digital signal through an analog-to-digital conversion circuit; Step 3: extract power, phase and polarization parameters from the digital signal as a temperature measurement laser signal.

4. The optical fiber temperature measuring device according to claim 2, characterized in that: The step S20 specifically includes: Step 1: Filter the acquired temperature measurement laser signal to remove noise interference; Step 2, normalizing the filtered temperature measurement laser signal; Step 3: Arrange the preprocessed temperature measurement laser signal into a one-dimensional array in time series as a temperature measurement laser array.

5. The optical fiber temperature measuring device according to claim 2, characterized in that: The step S30 specifically includes: Step 1: Establish a standard laser array, in which the laser signal parameter values ​​are reference values ​​measured under standard temperature conditions; Step 2, calculating the difference between each element in the temperature measurement laser array and the corresponding element in the standard laser array; Step 3: The calculated difference values ​​are combined into a difference array as the temperature measurement difference array.

6. The optical fiber temperature measuring device according to claim 2, characterized in that: The step S40 specifically includes: Step 1: Establish a pre-set difference array-temperature comparison database, in which the difference arrays of the standard laser array and the temperature measurement laser array corresponding to different temperature conditions are stored; Step 2: Match and compare the temperature measurement difference array obtained in step S30 with the difference array in the database to find the best matching difference array; Step 3: Extract the temperature value corresponding to the best matching difference array and output it as the final detection temperature value.

7. A remote monitoring system for an optical fiber temperature measuring device, characterized in that: Includes the following functional modules: A data transmission module is used to transmit the temperature measurement data collected by the control chip to a remote monitoring center via a wired or wireless network; Data storage module: a database is set up in the remote monitoring center to store the temperature measurement data transmitted from the site, which is convenient for querying and analyzing historical data; Remote monitoring interface module, develops Web interface or client software in the remote monitoring center for real-time monitoring and control of on-site temperature measurement devices; The alarm module sends alarm information to management personnel in a timely manner when abnormal temperature is detected, and notifies them through SMS and email push.

8. The optical fiber temperature measuring device according to claim 7, characterized in that: The data transmission module transmits the temperature measurement data to the remote monitoring center via the 4G wireless network.

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