Distributed optical fiber temperature measurement method, equipment and device for dynamic attenuation compensation

Abstract

The invention discloses a distributed optical fiber temperature measurement method, equipment and device for dynamic attenuation compensation, and relates to the technical field of optical information, and the method comprises the following steps: obtaining a corresponding relation between a Raman scattering signal attenuation coefficient and a Rayleigh scattering signal attenuation coefficient; obtaining Raman scattering signal power and a Rayleigh scattering signal attenuation coefficient of the temperature measurement optical fiber at the first preset position at the first preset temperature and the to-be-measured temperature respectively; the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measurement optical fiber at the first preset position at the first preset temperature are calculated; determining the temperature of the to-be-measured environment according to the corresponding relation between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measurement optical fiber at the first preset position at the to-be-measured temperature. The attenuation change of the Raman anti-Stokes signal is monitored in real time, the influence of optical fiber dynamic attenuation on temperature measurement in the temperature monitoring and demodulation process is compensated, and the temperature measurement stability and reliability of the system are improved.

Description

Technical Field

[0001] The present application relates to the field of optical information technology, and in particular to a distributed optical fiber temperature measurement method, equipment and device with dynamic attenuation compensation. Background Art

[0002] As one of the most promising technologies in optical fiber sensing technology, the optical fiber temperature sensing system has the advantages of corrosion resistance, no electromagnetic interference, low transmission loss, long-distance real-time online detection, and working in harsh environments such as flammable and explosive environments compared to traditional electrical temperature sensing systems.

[0003] At present, the common distributed fiber optic temperature sensing system is based on optical time-domain reflectometry (OTDR), which uses OTDR to detect and analyze the backscattered light signal with temperature information, so as to obtain the distribution of temperature information along the fiber through a single measurement. However, the distributed fiber optic temperature sensing system has the problem of large temperature monitoring deviation and even failure of the temperature measurement system, which affects the accuracy of temperature measurement. Summary of the invention

[0004] The present application provides a distributed optical fiber temperature measurement method, equipment and device with dynamic attenuation compensation to solve the problem that the existing distributed optical fiber temperature sensing system has a large temperature monitoring deviation, or even failure of the temperature measurement system, which affects the accuracy of temperature measurement.

[0005] In a first aspect, the present application provides a distributed optical fiber temperature measurement method with dynamic attenuation compensation, comprising the following steps:

[0006] Obtaining the corresponding relationship between the attenuation coefficient of the Raman scattering signal and the attenuation coefficient of the Rayleigh scattering signal;

[0007] Respectively obtain the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the first preset temperature and the temperature to be measured;

[0008] The temperature of the environment to be measured is determined according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the temperature to be measured.

[0009] In the present application, the signal power of the Rayleigh scattering signal is independent of the temperature, while the signal power of the Raman anti-Stokes signal is dependent on the temperature. Based on the distributed optical fiber temperature sensing technology, the relationship between the attenuation coefficients of the Rayleigh scattering signal and the Raman anti-Stokes signal is obtained, and the Raman anti-Stokes signal attenuation coefficient is converted into an expression of the Rayleigh scattering signal attenuation coefficient. The temperature of the environment to be measured is determined by the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at a first preset position under a first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position under the measured temperature, the attenuation change of the Raman anti-Stokes signal is monitored in real time, the influence of the dynamic attenuation of the optical fiber on the temperature measurement effect during temperature monitoring and demodulation is compensated, and the temperature measurement stability and reliability of the system are improved.

[0010] It should be noted that the first preset temperature is usually a known accurate temperature between 15 and 40°C, which can be confirmed by measuring with a thermometer. The first preset position is a specific position in the temperature measurement environment, and it is necessary to ensure that the power and attenuation coefficient of the Rayleigh scattering signal and the Raman scattering signal are measured at the same position at the first preset temperature and the temperature to be measured.

[0011] In some embodiments, obtaining the correspondence between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient includes:

[0012] Obtaining the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of the temperature measuring optical fiber at different positions at a second preset temperature;

[0013] The attenuation coefficients of the Rayleigh scattering signal and the Raman scattering signal at different positions are fitted with quadratic curves to obtain the corresponding relationship between the attenuation coefficient of the Raman scattering signal and the attenuation coefficient of the Rayleigh scattering signal.

[0014] By obtaining the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of the temperature measuring optical fiber at different positions at the second preset temperature, the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of multiple points can be obtained, and the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of multiple points are fitted to obtain the relationship between the attenuation coefficients of the Rayleigh scattering signal and the Raman anti-Stokes signal. Since the power of the Rayleigh scattering signal is not related to the temperature, while the power of the Raman anti-Stokes signal is related to the temperature, the attenuation coefficient of the Rayleigh scattering signal related to the temperature is not related to the temperature, and the attenuation coefficient of the Raman anti-Stokes signal related to the temperature can be converted into the attenuation coefficient of the Rayleigh scattering signal that is not related to the temperature, thereby achieving the accuracy of temperature measurement. It should be noted that the second preset temperature is usually 0 to 40°C, and it is required that each measuring point on the temperature measuring optical fiber is consistent at the second preset temperature, and the temperature of the temperature measuring points on the entire optical fiber is uniform.

[0015] In some embodiments, the correspondence between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient includes: a correspondence between the Raman scattering signal attenuation coefficient and a quadratic equation of the Rayleigh scattering signal attenuation coefficient.

[0016] In some embodiments, the Raman scattering signal attenuation coefficient is α αs , the attenuation coefficient of the Rayleigh scattering signal is α R , the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient is:

[0017] α as =a*α R 2 +b*α R +c;

[0018] Among them, a is the first coefficient, which is obtained by quadratic curve fitting;

[0019] b is the second coefficient, obtained from quadratic curve fitting;

[0020] c is the third coefficient, which is obtained by quadratic curve fitting.

[0021] In some embodiments, the calculation formula of the temperature of the environment to be measured satisfies:

[0022]

[0023] in:

[0024] I as0 is the Raman anti-Stokes signal power of the temperature measuring optical fiber at a first preset temperature;

[0025] I as is the Raman anti-Stokes signal power of the temperature measuring optical fiber at the temperature to be measured;

[0026] T is the temperature to be measured;

[0027] T0 is the first preset temperature;

[0028] h is Planck's constant, which is 6.62607015×10 -34 J.s;

[0029] △v is the Raman frequency shift of the sensing fiber, which is a constant related to the fiber material;

[0030] a is the first coefficient, obtained from quadratic curve fitting;

[0031] b is the second coefficient, obtained from quadratic curve fitting;

[0032] c is the third coefficient, obtained from quadratic curve fitting;

[0033] k is the Boltzmann constant, specifically 1.380649×10 -23 J / K;

[0034] α R is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the temperature to be measured;

[0035] α r is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the first preset temperature;

[0036] L is the distance between the temperature measurement point to be measured and the light source.

[0037] Since the power of the Rayleigh scattering signal is not related to the temperature of the test environment, it can be roughly considered that the power of the Rayleigh scattering signal at the first preset temperature is equal to the power of the Rayleigh scattering signal at the temperature to be measured. The expression for the temperature to be measured T is obtained according to the following formula:

[0038]

[0039] P0=P;

[0040] α as =a*α R 2 +b*α R +c;

[0041] Wherein, P0 is the output power of the light source at the first preset temperature, P is the output power of the light source at the temperature to be measured, and K as is the coefficient related to the cross section of the optical fiber scattering end, v r is the frequency of Rayleigh scattered light, v as is the frequency of anti-Stokes light, R as(T0)is the temperature modulation function of the anti-Stokes signal at the first preset temperature, h is the Planck constant, k is the Boltzmann constant, △v is the Raman frequency shift of the sensing fiber, S is the scattering cross-sectional area, T0 is the first preset temperature, S e is a constant, L is the distance between the measuring point of the optical fiber to be measured temperature and the optical signal; α r is the attenuation coefficient of the Rayleigh scattering signal at the first preset temperature; α as0 is the Raman anti-Stokes signal attenuation coefficient at the first preset temperature; T is the temperature to be measured, a is the first coefficient, which is obtained by quadratic curve fitting, b is the second coefficient, which is obtained by quadratic curve fitting, c is the third coefficient, which is obtained by quadratic curve fitting, α R is the attenuation coefficient of the Rayleigh scattering signal at the temperature to be measured, α as is the Raman anti-Stokes signal attenuation coefficient at the measured temperature.

[0042] It should be noted that in the existing measurement methods, in actual measurement, usually I as0 It is assumed that the loss of the optical fiber is constant at the first preset temperature and the temperature to be tested, that is, the default is -(α R +α as ) and -(α r +α as0 ) are equal, and in fact, in the present application, it is found that the loss of the optical fiber at the preset temperature and at the temperature to be measured is dynamic and not constant, and the difference in loss cannot be ignored. By establishing a corresponding relationship between the attenuation coefficient of the Raman scattering signal and the attenuation coefficient of the Rayleigh scattering signal, the optical fiber loss at different temperatures can be reflected, and dynamic compensation for the temperature to be measured can be achieved at different measurement temperatures, thereby achieving accuracy in temperature measurement.

[0043] In some embodiments, determining the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured comprises:

[0044] Respectively obtaining the power of the Rayleigh scattering signal and the attenuation coefficient of the Rayleigh scattering signal at the second preset position of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the temperature to be measured;

[0045] According to the power of the Rayleigh scattering signal when the temperature measuring optical fiber measures the first preset temperature and the temperature measuring optical fiber measures the temperature to be measured at the second preset position of the reference optical fiber and the attenuation coefficient of the Rayleigh scattering signal, a ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is obtained;

[0046] The temperature of the environment to be measured is determined based on the ratio of the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature, the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured, and the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured.

[0047] It is generally believed that the light source power of the temperature measuring optical fiber at the first preset temperature is consistent with the light source power at the temperature to be measured, that is, the power of the Rayleigh scattering signal at the first preset temperature and the temperature to be measured is equal. In fact, although the Rayleigh scattering signal is not related to temperature, in different measurement environments, the attenuation coefficient of the Rayleigh scattering signal will also be affected by other factors, such as the power of the light source. In fact, there will be slight differences in the light source power at each measurement, and these differences will also affect the accuracy of temperature measurement. By setting the reference optical fiber, the reference optical fiber is in a temperature-stable environment during the entire test phase, and its attenuation coefficient is not changed by external factors such as external force and climate environment. At the same time, the influence of temperature on the power of the Rayleigh scattering signal is extremely small and can be ignored. Therefore, the power of the Rayleigh scattering signal at the reference optical fiber position is only affected by the power of the light source. Therefore, the ratio of the power of the Rayleigh scattering signal of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the power of the Rayleigh scattering signal of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is the ratio of the light source power at the first preset temperature to the light source power at the temperature to be measured. Thereby, the influence of the light source power on the accuracy of the measurement result during measurement can be eliminated. It should be noted that, usually, the reference optical fiber is connected between the light source and the temperature measuring optical fiber through an optical fiber interface, and the reference optical fiber is usually placed inside the machine in a fixed position. The machine is in a stable temperature environment. When the temperature measuring optical fiber changes the measuring temperature, the temperature of the reference optical fiber remains unchanged, so that the power of the Rayleigh scattering signal of the reference optical fiber is only affected by the light source power.

[0048] In some embodiments, according to the power of the Rayleigh scattering signal when the temperature measuring fiber measures the first preset temperature and the temperature measuring fiber measures the temperature to be measured at the second preset position of the reference optical fiber and the attenuation coefficient of the Rayleigh scattering signal, the ratio of the light source output power of the reference optical fiber when the temperature measuring fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring fiber measures the temperature to be measured is obtained:

[0049] The ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is β, and the power of the Rayleigh scattering signal of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature is I rl0 The power of the Rayleigh scattered signal of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is I Rl0, the light source output power when the temperature measuring optical fiber measures the first preset temperature is P0, and the light source output power when the temperature measuring optical fiber measures the temperature to be measured is P, where: β = I rl0 / I Rl0 =P0 / P.

[0050] Specifically, the expression of β can be derived in the following way:

[0051]

[0052] Among them, K r is the coefficient related to the cross section of the reference fiber and the fiber scattering end;

[0053] S is the scattering cross section of the reference fiber;

[0054] v r is the frequency of Rayleigh scattered light;

[0055] α0 is the Rayleigh scattering attenuation coefficient of the reference optical fiber;

[0056] l1 is the distance between the measurement point of the reference optical fiber and the light source.

[0057] By measuring the power of the Rayleigh scattering signal of the reference optical fiber at the first preset temperature with the temperature measuring optical fiber and the power of the Rayleigh scattering signal of the reference optical fiber at the temperature to be measured with the temperature measuring optical fiber, the light source power compensation coefficient can be obtained to improve the measurement accuracy.

[0058] It should be noted that the reference optical fiber is usually placed in an environment with stable temperature and known distance. During measurement, the light source first passes through the reference optical fiber and then through the temperature measuring optical fiber. There are detectors at the reference optical fiber and the temperature measuring optical fiber. Since the temperature measuring optical fiber will have temperature changes at the first preset temperature and the temperature to be measured, and the reference optical fiber is in a constant temperature environment, it is not affected by temperature changes and is only affected by the light source power. Therefore, the reference optical fiber can reduce the impact of light source power changes on the temperature measurement results, further improving the accuracy of the temperature measurement results.

[0059] In some embodiments, the calculation formula of the temperature of the environment to be measured satisfies:

[0060]

[0061] Wherein, β is the ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured;

[0062] I as0 is the Raman anti-Stokes signal power of the temperature measuring optical fiber at a first preset temperature;

[0063] I asis the Raman anti-Stokes signal power of the temperature measuring optical fiber at the temperature to be measured;

[0064] T is the temperature to be measured;

[0065] T0 is the first preset temperature;

[0066] h is Planck's constant;

[0067] △v is the Raman frequency shift of the sensing fiber;

[0068] a is the first coefficient;

[0069] b is the second coefficient;

[0070] c is the third coefficient;

[0071] k is the Boltzmann constant;

[0072] α R is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the temperature to be measured;

[0073] α r is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the first preset temperature;

[0074] L is the distance between the temperature measurement point to be measured and the light source.

[0075] The accuracy of optical fiber temperature measurement can be further improved by correcting the ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured.

[0076] In a second aspect, the present application provides a distributed optical fiber temperature measurement device with dynamic attenuation compensation, comprising:

[0077] A light source, comprising a pulse light source and a wavelength division multiplexer, wherein an output end of the pulse light source is connected to an input end of the wavelength division multiplexer;

[0078] a temperature measurement component, comprising a temperature measurement optical fiber, the first output end of the wavelength division multiplexer being connected to the temperature measurement optical fiber; and

[0079] The signal processing component includes a photodetector, a signal collector and a signal processor, wherein the second output end of the wavelength division multiplexer is connected to the input end of the photodetector, the output end of the photodetector is connected to the input end of the signal collector, and the output end of the signal collector is connected to the input end of the signal processor;

[0080] The distributed optical fiber temperature measurement device with dynamic attenuation compensation can be used to implement the steps of the distributed optical fiber temperature measurement method with dynamic attenuation compensation described in the first aspect.

[0081] It should be noted that, in some embodiments, the temperature measurement component further includes a reference optical fiber, and the input end of the reference optical fiber is connected to the output end of the wavelength division multiplexer.

[0082] In a third aspect, the present application proposes a distributed optical fiber temperature measurement device with dynamic attenuation compensation, comprising:

[0083] an acquisition unit, used to acquire a corresponding relationship between a Raman scattering signal attenuation coefficient and a Rayleigh scattering signal attenuation coefficient; and

[0084] The control unit is used to determine the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0086] Figure 1 This is a flow chart of a distributed optical fiber temperature measurement method with dynamic attenuation compensation according to an embodiment of the present application.

[0087] Figure 2 This is a flow chart of a distributed optical fiber temperature measurement method with dynamic attenuation compensation according to another embodiment of the present application.

[0088] Figure 3 This is a flow chart of a distributed optical fiber temperature measurement method with dynamic attenuation compensation according to yet another embodiment of the present application.

[0089] Figure 4 A schematic diagram of a distributed optical fiber temperature measurement device with dynamic attenuation compensation according to an embodiment of the present application.

[0090] Figure 5 A schematic diagram of a distributed optical fiber temperature measurement device with dynamic attenuation compensation according to an embodiment of the present application.

[0091] Figure 6 Schematic diagram of a distributed optical fiber temperature measurement device with dynamic attenuation compensation according to an embodiment of the present application.

[0092] Description of Figure Numbers:

[0093] 100 distributed optical fiber temperature measurement equipment with dynamic attenuation compensation; 1 light source; 11 pulse light source; 12 wavelength division multiplexer; 2 temperature measurement component; 21 temperature measurement optical fiber; 22 reference optical fiber; 3 signal processing component; 31 photoelectric detector; 32 signal collector; 33 signal processor. DETAILED DESCRIPTION

[0094] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0095] As one of the most promising technologies in optical fiber sensing technology, the optical fiber temperature sensing system has the advantages of corrosion resistance, no electromagnetic interference, low transmission loss, long-distance real-time online detection, and working in harsh environments such as flammable and explosive environments compared to traditional electrical temperature sensing systems.

[0096] The common distributed fiber temperature sensing system is based on optical time-domain reflectometry (OTDR), which uses OTDR to detect and analyze the backscattered light signal with temperature information, so as to obtain the distribution of temperature information along the fiber through a single measurement. Since distributed fiber temperature measurement uses the change in scattered signal light power to directly demodulate temperature information, this sensing technology is particularly sensitive to changes in light power and is easily affected by fluctuations in light source power and fiber attenuation, which causes changes in Raman scattering signal power and directly affects the temperature measurement effect. At the same time, various factors such as ambient temperature, mechanical damage, aging, nuclear radiation, etc. will cause random changes in the attenuation of the optical fiber in the temperature measurement cable, resulting in great deviations in temperature monitoring and even failure of the temperature measurement system.

[0097] In view of this, the present application provides a distributed optical fiber temperature measurement method, equipment and device with dynamic attenuation compensation to solve the problem that the existing distributed optical fiber temperature sensing system has extremely large temperature monitoring deviations and even failure of the temperature measurement system, affecting the accuracy of temperature measurement.

[0098] In a first aspect, the present application provides a distributed optical fiber temperature measurement method with dynamic attenuation compensation, comprising the following steps:

[0099] S100, obtaining a corresponding relationship between a Raman scattering signal attenuation coefficient and a Rayleigh scattering signal attenuation coefficient;

[0100] S200, respectively obtaining the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the first preset temperature and the temperature to be measured;

[0101] S300, determining the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the temperature to be measured.

[0102] In the present application, the power of the Rayleigh scattering signal is independent of the temperature, while the power of the Raman anti-Stokes signal is dependent on the temperature. Based on the distributed optical fiber temperature sensing technology, the relationship between the attenuation coefficients of the Rayleigh scattering signal and the Raman anti-Stokes signal is obtained, and the Raman anti-Stokes signal attenuation coefficient is converted into an expression of the Rayleigh scattering signal attenuation coefficient. The temperature of the environment to be measured is determined by the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at a first preset position under a first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position under the measured temperature. The attenuation change of the Raman anti-Stokes signal is monitored in real time, the influence of the dynamic attenuation of the optical fiber on the temperature measurement effect during temperature monitoring and demodulation is compensated, and the temperature measurement stability and reliability of the system are improved.

[0103] It should be noted that the first preset temperature is usually a known accurate temperature between 15 and 40°C, which can be confirmed by measuring with a thermometer. The first preset position is a specific position in the temperature measurement environment, and it is necessary to ensure that the power and attenuation coefficient of the Rayleigh scattering signal and the Raman scattering signal are measured at the same position at the first preset temperature and the temperature to be measured.

[0104] In combination with the first aspect, in some embodiments provided in the present application, obtaining the correspondence between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient includes:

[0105] S101, obtaining the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of the temperature measuring optical fiber at different positions at a second preset temperature;

[0106] S102, fitting the attenuation coefficients of the Rayleigh scattering signal and the Raman scattering signal at different positions by quadratic curves to obtain a corresponding relationship between the attenuation coefficient of the Raman scattering signal and the attenuation coefficient of the Rayleigh scattering signal.

[0107] By obtaining the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of the temperature measuring optical fiber at different positions at the second preset temperature, the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of multiple points can be obtained, and the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of multiple points are fitted to obtain the relationship between the attenuation coefficients of the Rayleigh scattering signal and the Raman anti-Stokes signal. Since the power of the Rayleigh scattering signal is not related to the temperature, while the power of the Raman anti-Stokes signal is related to the temperature, the attenuation coefficient of the Rayleigh scattering signal related to the temperature is not related to the temperature, and the attenuation coefficient of the Raman anti-Stokes signal related to the temperature can be converted into the attenuation coefficient of the Rayleigh scattering signal that is not related to the temperature, thereby achieving the accuracy of temperature measurement. It should be noted that the second preset temperature is usually 0 to 40°C, and it is required that each measuring point on the temperature measuring optical fiber is consistent at the second preset temperature, and the temperature of the temperature measuring points on the entire optical fiber is uniform.

[0108] In combination with the first aspect, in some embodiments provided in the present application, the correspondence between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient includes: the correspondence between the Raman scattering signal attenuation coefficient and the quadratic equation of the Rayleigh scattering signal attenuation coefficient.

[0109] In combination with the first aspect, in some embodiments provided in the present application, the Raman scattering signal attenuation coefficient is α αs , the attenuation coefficient of the Rayleigh scattering signal is α R , the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient is:

[0110] α as =a*α R 2 +b*α R +c;

[0111] Among them, a is the first coefficient, which is obtained by quadratic curve fitting;

[0112] b is the second coefficient, obtained from quadratic curve fitting;

[0113] c is the third coefficient, which is obtained by quadratic curve fitting.

[0114] In combination with the first aspect, in some embodiments provided in the present application, the calculation formula for the temperature of the environment to be measured satisfies:

[0115]

[0116] in:

[0117] I as0 is the Raman anti-Stokes signal power of the temperature measuring optical fiber at a first preset temperature;

[0118] Ias is the Raman anti-Stokes signal power of the temperature measuring optical fiber at the temperature to be measured;

[0119] T is the temperature to be measured;

[0120] T0 is the first preset temperature;

[0121] h is Planck's constant, which is 6.62607015×10 -34 J.s;

[0122] △v is the Raman frequency shift of the sensing fiber, which is a constant related to the fiber material;

[0123] a is the first coefficient, obtained from quadratic curve fitting;

[0124] b is the second coefficient, obtained from quadratic curve fitting;

[0125] c is the third coefficient, obtained from quadratic curve fitting;

[0126] k is the Boltzmann constant, specifically 1.380649×10 -23 J / K;

[0127] α R is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the temperature to be measured;

[0128] α r is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the first preset temperature;

[0129] L is the distance between the temperature measurement point to be measured and the light source.

[0130] Since the attenuation coefficient of the Rayleigh scattering signal is not related to the temperature of the test environment, it can be roughly considered that the power of the Rayleigh scattering signal at the first preset temperature is equal to the power of the Rayleigh scattering signal at the temperature to be measured. The expression for the temperature to be measured T is obtained according to the following formula:

[0131]

[0132] P0=P;

[0133] α as =a*α R 2 +b*α R +c;

[0134] Wherein, P0 is the output power of the light source at the first preset temperature, P is the output power of the light source at the temperature to be measured, and K as is the coefficient related to the cross section of the optical fiber scattering end, v r is the frequency of Rayleigh scattered light, v asis the frequency of anti-Stokes light, R as(T0) is the temperature modulation function of the anti-Stokes signal at the first preset temperature, h is the Planck constant, k is the Boltzmann constant, △v is the Raman frequency shift of the sensing fiber, S is the scattering cross-sectional area, T0 is the first preset temperature, S e is a constant, L is the distance between the measuring point of the optical fiber to be measured temperature and the optical signal; α r is the attenuation coefficient of the Rayleigh scattering signal at the first preset temperature; α as0 is the Raman anti-Stokes signal attenuation coefficient at the first preset temperature; T is the temperature to be measured, a is the first coefficient, which is obtained by quadratic curve fitting, b is the second coefficient, which is obtained by quadratic curve fitting, c is the third coefficient, which is obtained by quadratic curve fitting, α R is the attenuation coefficient of the Rayleigh scattering signal at the temperature to be measured, α as is the Raman anti-Stokes signal attenuation coefficient at the measured temperature.

[0135] It should be noted that in the existing measurement methods, in actual measurement, usually I as0 It is assumed that the loss of the optical fiber is constant at the first preset temperature and the temperature to be tested, that is, the default is -(α R +α as ) and -(α r +α as0 ) are equal, and in fact, in the present application, it is found that the loss of the optical fiber at the preset temperature and at the temperature to be measured is dynamic and not constant, and the difference in loss cannot be ignored. By establishing a corresponding relationship between the attenuation coefficient of the Raman scattering signal and the attenuation coefficient of the Rayleigh scattering signal, the optical fiber loss at different temperatures can be reflected, and dynamic compensation for the temperature to be measured can be achieved at different measurement temperatures, thereby achieving accuracy in temperature measurement.

[0136] In combination with the first aspect, in some embodiments provided in the present application, determining the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured includes:

[0137] S301, respectively obtaining the power of the Rayleigh scattering signal and the attenuation coefficient of the Rayleigh scattering signal at the second preset position of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the temperature to be measured;

[0138] S302, obtaining a ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured according to the power of the Rayleigh scattering signal and the attenuation coefficient of the Rayleigh scattering signal when the temperature measuring optical fiber measures the first preset temperature at the second preset position of the reference optical fiber;

[0139] S303, determine the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature, the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured, and the ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured.

[0140] It is generally believed that the light source power of the temperature measuring optical fiber at the first preset temperature is consistent with the light source power at the temperature to be measured, that is, the power of the Rayleigh scattering signal at the first preset temperature and the temperature to be measured is equal. In fact, although the Rayleigh scattering signal is not related to temperature, in different measurement environments, the attenuation coefficient of the Rayleigh scattering signal will also be affected by other factors, such as the power of the light source. In fact, there will be slight differences in the light source power at each measurement, and these differences will also affect the accuracy of temperature measurement. By setting the reference optical fiber, the reference optical fiber is in a temperature-stable environment during the entire test phase, and its attenuation coefficient is not changed by external factors such as external force and climate environment. At the same time, the influence of temperature on the power of the Rayleigh scattering signal is extremely small and can be ignored. Therefore, the power of the Rayleigh scattering signal at the reference optical fiber position is only affected by the power of the light source. Therefore, the ratio of the power of the Rayleigh scattering signal of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the power of the Rayleigh scattering signal of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is the ratio of the light source power at the first preset temperature to the light source power at the temperature to be measured. Thereby, the influence of the light source power on the accuracy of the measurement result during measurement can be eliminated. It should be noted that, usually, the reference optical fiber is connected between the light source and the temperature measuring optical fiber through an optical fiber interface, and the reference optical fiber is usually placed inside the machine in a fixed position. The machine is in a stable temperature environment. When the temperature measuring optical fiber changes the measuring temperature, the temperature of the reference optical fiber remains unchanged, so that the power of the Rayleigh scattering signal of the reference optical fiber is only affected by the light source power.

[0141] In combination with the first aspect, in some embodiments provided in the present application, according to the power of the Rayleigh scattering signal when the temperature measuring fiber measures the first preset temperature and the temperature measuring fiber measures the temperature to be measured at the second preset position of the reference optical fiber and the attenuation coefficient of the Rayleigh scattering signal, the ratio of the light source output power of the reference optical fiber when the temperature measuring fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring fiber measures the temperature to be measured is obtained:

[0142] The ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is β, and the power of the Rayleigh scattering signal of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature is I rl0 The power of the Rayleigh scattered signal of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is I Rl0 , the light source output power when the temperature measuring optical fiber measures the first preset temperature is P0, and the light source output power when the temperature measuring optical fiber measures the temperature to be measured is P, where: β = I rl0 / I Rl0 =P0 / P.

[0143] Specifically, the expression of β can be derived in the following way:

[0144]

[0145] Among them, K r is the coefficient related to the cross section of the reference fiber and the fiber scattering end;

[0146] S is the scattering cross section of the reference fiber;

[0147] v r is the frequency of Rayleigh scattered light;

[0148] α0 is the Rayleigh scattering attenuation coefficient of the reference optical fiber;

[0149] l1 is the distance between the measurement point of the reference optical fiber and the light source.

[0150] By measuring the power of the Rayleigh scattering signal of the reference optical fiber at the first preset temperature with the temperature measuring optical fiber and the power of the Rayleigh scattering signal of the reference optical fiber at the temperature to be measured with the temperature measuring optical fiber, the light source power compensation coefficient can be obtained to improve the measurement accuracy.

[0151] It should be noted that the reference optical fiber is usually placed in an environment with stable temperature and known distance. During measurement, the light source first passes through the reference optical fiber and then through the temperature measuring optical fiber. There are detectors at the reference optical fiber and the temperature measuring optical fiber. Since the temperature measuring optical fiber will have temperature changes at the first preset temperature and the temperature to be measured, and the reference optical fiber is in a constant temperature environment, it is not affected by temperature changes and is only affected by the light source power. Therefore, the reference optical fiber can reduce the impact of light source power changes on the temperature measurement results, further improving the accuracy of the temperature measurement results.

[0152] In combination with the first aspect, in some embodiments provided in the present application, the calculation formula for the temperature of the environment to be measured satisfies:

[0153]

[0154] Wherein, β is the ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured;

[0155] I as0 is the Raman anti-Stokes signal power of the temperature measuring optical fiber at a first preset temperature;

[0156] I as is the Raman anti-Stokes signal power of the temperature measuring optical fiber at the temperature to be measured;

[0157] T is the temperature to be measured;

[0158] T0 is the first preset temperature;

[0159] h is Planck's constant;

[0160] △v is the Raman frequency shift of the sensing fiber;

[0161] a is the first coefficient;

[0162] b is the second coefficient;

[0163] c is the third coefficient;

[0164] k is the Boltzmann constant;

[0165] α R is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the temperature to be measured;

[0166] α r is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the first preset temperature;

[0167] L is the distance between the temperature measurement point to be measured and the light source.

[0168] The accuracy of optical fiber temperature measurement can be further improved by correcting the ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured.

[0169] In a second aspect, the present application provides a distributed optical fiber temperature measurement device 100 with dynamic attenuation compensation, comprising:

[0170] The light source 1 comprises a pulse light source 11 and a wavelength division multiplexer 12, wherein the output end of the pulse light source 11 is connected to the input end of the wavelength division multiplexer 12;

[0171] The temperature measuring component 2 comprises a temperature measuring optical fiber 21, and the first output end of the wavelength division multiplexer 12 is connected to the temperature measuring optical fiber 21; and

[0172] The signal processing component 3 includes a photodetector 31, a signal collector 32 and a signal processor 33, wherein the second output end of the wavelength division multiplexer 12 is connected to the input end of the photodetector 31, the output end of the photodetector 31 is connected to the input end of the signal collector 32, and the output end of the signal collector 32 is connected to the input end of the signal processor 33;

[0173] The distributed optical fiber temperature measurement device 100 with dynamic attenuation compensation can be used to implement the steps of the distributed optical fiber temperature measurement method with dynamic attenuation compensation described in the first aspect.

[0174] It should be noted that, in some embodiments, the temperature measurement component further includes a reference optical fiber 22 , and the input end of the reference optical fiber 22 is connected to the output end of the wavelength division multiplexer 12 .

[0175] Specifically, the system controls the acquisition module so that the pulse light source outputs a pulse signal which is incident on the reference optical fiber and the sensing optical fiber through a wavelength division multiplexer; the pulse laser generates spontaneous Raman scattering and Rayleigh scattering when propagating in the optical fiber, thereby generating Raman anti-Stokes signals and Rayleigh scattering signals at each position of the multimode sensing optical fiber; the Raman anti-Stokes signals and Rayleigh scattering signals generated in the optical fiber are respectively sent to the input end of the photodetector through the wavelength division multiplexer for photoelectric conversion and amplification, and finally enter the high-speed data acquisition card and the signal processing module to obtain the position and intensity information of the Raman anti-Stokes signals and Rayleigh scattering signals along the optical fiber.

[0176] In a third aspect, the present application proposes a distributed optical fiber temperature measurement device with dynamic attenuation compensation, comprising:

[0177] an acquisition unit, used to acquire a corresponding relationship between a Raman scattering signal attenuation coefficient and a Rayleigh scattering signal attenuation coefficient; and

[0178] The control unit is used to determine the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured.

[0179] The power of the Rayleigh scattering signal is not related to temperature, while the attenuation coefficient of the Raman anti-Stokes signal is related to temperature. Based on the distributed optical fiber temperature sensing technology, the relationship between the attenuation coefficients of the Rayleigh scattering signal and the Raman anti-Stokes signal is obtained, and the Raman anti-Stokes signal attenuation coefficient is converted into an expression of the Rayleigh scattering signal attenuation coefficient. The temperature of the environment to be measured is determined by the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position under the first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position under the measured temperature. The attenuation change of the Raman anti-Stokes signal is monitored in real time, the influence of the dynamic attenuation of the optical fiber on the temperature measurement effect during temperature monitoring and demodulation is compensated, and the temperature measurement stability and reliability of the system are improved.

[0180] The present application will be described below in conjunction with specific embodiments.

[0181] Example 1

[0182] A distributed optical fiber temperature measurement method with dynamic attenuation compensation comprises the following steps:

[0183] The sensing optical fiber was placed at a constant temperature of 25°C for 60 minutes to keep the temperature along the optical fiber consistent.

[0184] The pulse light source outputs a pulse signal which is incident on the reference optical fiber and the sensing optical fiber; the pulse laser generates spontaneous Raman scattering and Rayleigh scattering when propagating in the optical fiber, thereby generating Raman anti-Stokes signals and Rayleigh scattering signals at each position of the multimode sensing optical fiber; the Raman anti-Stokes signals and Rayleigh scattering signals generated in the optical fiber are respectively subjected to photoelectric conversion and amplification, and finally enter into acquisition and signal processing to obtain the position and intensity information of the Raman anti-Stokes signals and Rayleigh scattering signals along the optical fiber, which is expressed as [P R1 , P R2 , P R3 , ..., P Rn ] and [P a1 , P a2 , P a3 , ..., P an ];

[0185] The relationship between the backscattered light power P and the optical fiber position can be expressed as:

[0186]

[0187] Where P0 is the transmission power of the OTDR light source, K r is the coefficient related to the cross section of the optical fiber scattering end, v ris the frequency of Rayleigh scattered light, S is the scattering cross section, α is the fiber attenuation coefficient (in dB / km), and L is the distance between the measurement position and the starting point of the light source.

[0188] Further data processing and analysis using P(L) yields the attenuation coefficient sequences of the backscattered Rayleigh signal and Raman anti-Stokes signal at each point along the optical fiber: α R =[α R1 , α R2 , α R3 , ..., α Rn ] and α as =[α as1 , α as2 , α as3 , ..., α asn ];

[0189] The wavelength of the pulse light source is 1550nm, the pulse width is 10ns, and the repetition frequency is 8kHz. A dual-channel avalanche photodetector is used to detect the optical signal, and its bandwidth is 100MHz and the spectral response range is 900-1700nm. A wavelength division multiplexer with a wavelength of 1450nm / 1550nm / 1660nm is used for wavelength division. A data acquisition card with 2 channels is used for sampling, with a sampling rate of 200M / s and a bandwidth of 100MHz. A multimode optical fiber with a gradient refractive index is used as the sensing optical fiber.

[0190] Analyze the relationship between Rayleigh scattering and Raman anti-Stokes signal attenuation coefficient

[0191] The attenuation coefficient α at different positions of the optical fiber R , α as Perform a quadratic fit to get α as =a*α R 2 +b*α R +c;

[0192] Initial temperature calibration

[0193] The sensing fiber is kept at a constant temperature of 35°C, and the system collects the backscattered Rayleigh scattering signal and Raman anti-Stokes signal to obtain the Rayleigh scattering signal power I at the reference fiber position l0. rl0 , and further obtain the attenuation coefficient α of the Rayleigh scattering signal r , Raman anti-Stokes signal power I as0 and the reference fiber Rayleigh scattering signal power I rl0 Respectively expressed as:

[0194]

[0195] R as0(T0) = [exp(hΔν / kT0)-1] -1 ;

[0196]

[0197] Where P0 is the output power of the light source, K r , K as is the coefficient related to the cross section of the optical fiber scattering end, v r 、v as are the frequencies of Rayleigh scattered light and anti-Stokes light, R as (T0) is the temperature modulation function of the anti-Stokes signal, h and k are Planck constant and Boltzmann constant respectively, △v is the Raman frequency shift of the sensing fiber, S is the scattering cross section, and α0 is the attenuation coefficient of the Rayleigh scattering signal of the reference fiber;

[0198] The length of the calibration fiber ring is 10 meters, and the position of the reference fiber ring is 100 meters; Temperature measurement stage

[0199] The system collects the backscattered Rayleigh scattering signal and Raman anti-Stokes signal at the test temperature and obtains the attenuation coefficient α of the Rayleigh scattering signal. R , and the Rayleigh scattered signal power I at the reference fiber position l0 Rl0 , and the Raman anti-Stokes signal power I as ;

[0200]

[0201] R as (T) = [exp(hΔν / kT)-1] -1 ;

[0202]

[0203] Temperature information demodulation along the optical fiber

[0204] According to the above measurement results, combined with the demodulation formula, all the temperature information along the optical fiber is calculated;

[0205] First, solve the light source power compensation coefficient in the calibration stage and the temperature measurement stage. During the entire test phase, the reference optical fiber is in a stable indoor chassis environment, and its attenuation coefficient is not affected by external factors such as external force and climate environment. At the same time, the effect of temperature on the Rayleigh scattering signal power is extremely small and can be ignored. Therefore, the Rayleigh scattering signal power at the reference optical fiber position is only affected by the light source power, that is, the light source power compensation coefficient can be expressed as:

[0206]

[0207] Comparing the Raman anti-Stokes new signal power in the calibration stage and the temperature measurement stage, it can be expressed as:

[0208]

[0209] The temperature demodulation formula can be obtained by combining:

[0210]

[0211] Where: k and h are Boltzmann constant and Planck constant respectively, k = 1.380649 × 10 -23 J / K, h = 6.62607015 × 10 -34 J.s;

[0212] △v is the Raman frequency shift in the optical fiber, △v = 13.2THz;

[0213] T0 is the temperature of the optical fiber during the calibration phase;

[0214] α r , α R are the attenuation coefficients of the Rayleigh scattering signal of the optical fiber during the calibration stage and the test stage respectively;

[0215] β is the light source compensation coefficient, and β=P0 / P=I rl0 / I Rl0 , where I rl0 is the Rayleigh scattered signal power at the reference optical fiber position during the calibration phase, I Rl0 is the Rayleigh scattering signal power at the reference optical fiber position during the test phase;

[0216] a, b, c are the attenuation coefficients α of the corresponding points of the optical fiber R , α as For quadratic fitting coefficients, a is the quadratic term coefficient, b is the linear term coefficient, and c is the constant term.

[0217] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0218] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0219] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; the “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0220] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0221] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0222] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A distributed optical fiber temperature measurement method with dynamic attenuation compensation, characterized in that: The following steps are involved: Obtaining the corresponding relationship between the attenuation coefficient of the Raman scattering signal and the attenuation coefficient of the Rayleigh scattering signal; Respectively obtain the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the first preset temperature and the temperature to be measured; The temperature of the environment to be measured is determined according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first preset position at the temperature to be measured.

2. The distributed optical fiber temperature measurement method with dynamic attenuation compensation according to claim 1, characterized in that: The obtaining of the correspondence between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient comprises: Obtaining the Rayleigh scattering signal attenuation coefficient and the Raman scattering signal attenuation coefficient of the temperature measuring optical fiber at different positions at a second preset temperature; The attenuation coefficients of the Rayleigh scattering signal and the Raman scattering signal at different positions are fitted with quadratic curves to obtain the corresponding relationship between the attenuation coefficient of the Raman scattering signal and the attenuation coefficient of the Rayleigh scattering signal.

3. The distributed optical fiber temperature measurement method with dynamic attenuation compensation according to claim 2, characterized in that: The corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient includes: the corresponding relationship between the Raman scattering signal attenuation coefficient and the quadratic equation of the Rayleigh scattering signal attenuation coefficient.

4. The distributed optical fiber temperature measurement method with dynamic attenuation compensation according to claim 2, characterized in that: The Raman scattering signal attenuation coefficient is α αs , the attenuation coefficient of the Rayleigh scattering signal is α R , the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient is: a as =a*a R 2 +b*a R +c; Where a is the first coefficient; b is the second coefficient; c is the third coefficient.

5. The distributed optical fiber temperature measurement method with dynamic attenuation compensation according to claim 4, characterized in that: The calculation formula of the temperature of the environment to be measured satisfies: in: I as0 is the Raman anti-Stokes signal power of the temperature measuring optical fiber at a first preset temperature; I as is the Raman anti-Stokes signal power of the temperature measuring optical fiber at the temperature to be measured; T is the temperature to be measured; T0 is the first preset temperature; h is Planck's constant; △v is the Raman frequency shift of the sensing fiber; a is the first coefficient; b is the second coefficient; c is the third coefficient; k is the Boltzmann constant; α R is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the temperature to be measured; α r is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the first preset temperature; L is the distance between the temperature measurement point to be measured and the light source.

6. The distributed optical fiber temperature measurement method with dynamic attenuation compensation according to claim 1, characterized in that: Determining the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured comprises: Respectively obtaining the power of the Rayleigh scattering signal and the attenuation coefficient of the Rayleigh scattering signal at the second preset position of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the temperature to be measured; According to the power of the Rayleigh scattering signal when the temperature measuring optical fiber measures the first preset temperature and the temperature measuring optical fiber measures the temperature to be measured at the second preset position of the reference optical fiber and the attenuation coefficient of the Rayleigh scattering signal, a ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is obtained; The temperature of the environment to be measured is determined based on the ratio of the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature, the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured, and the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured.

7. The distributed optical fiber temperature measurement method with dynamic attenuation compensation according to claim 6, characterized in that: The power of the Rayleigh scattering signal and the attenuation coefficient of the Rayleigh scattering signal when the temperature measuring fiber measures the first preset temperature and the temperature to be measured according to the second preset position of the reference optical fiber are obtained, and the ratio of the light source output power of the reference optical fiber when the temperature measuring fiber measures the first preset temperature and the light source output power of the reference optical fiber when the temperature measuring fiber measures the temperature to be measured is obtained: The ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is β, and the power of the Rayleigh scattering signal of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature is I rl0 The power of the Rayleigh scattered signal of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured is I Rl0 , the light source output power when the temperature measuring optical fiber measures the first preset temperature is P0, and the light source output power when the temperature measuring optical fiber measures the temperature to be measured is P, where: β = I rl0 / I Rl0 =P0 / P.

8. The distributed optical fiber temperature measurement method with dynamic attenuation compensation according to claim 7, characterized in that: The calculation formula of the temperature of the environment to be measured satisfies: Wherein, β is the ratio of the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the first preset temperature to the light source output power of the reference optical fiber when the temperature measuring optical fiber measures the temperature to be measured; I as0 is the Raman anti-Stokes signal power of the temperature measuring optical fiber at a first preset temperature; I as is the Raman anti-Stokes signal power of the temperature measuring optical fiber at the temperature to be measured; T is the temperature to be measured; T0 is the first preset temperature; h is Planck's constant; △v is the Raman frequency shift of the sensing fiber; a is the first coefficient; b is the second coefficient; c is the third coefficient; k is the Boltzmann constant; α R is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the temperature to be measured; α r is the attenuation coefficient of the Rayleigh scattering signal of the temperature measuring optical fiber at the first preset temperature; L is the distance between the temperature measurement point to be measured and the light source.

9. A distributed optical fiber temperature measurement device with dynamic attenuation compensation, characterized in that: include: A light source, comprising a pulse light source and a wavelength division multiplexer, wherein an output end of the pulse light source is connected to an input end of the wavelength division multiplexer; A temperature measurement component, comprising a temperature measurement optical fiber, the first output end of the wavelength division multiplexer being connected to the temperature measurement optical fiber; as well as The signal processing component includes a photodetector, a signal collector and a signal processor, wherein the second output end of the wavelength division multiplexer is connected to the input end of the photodetector, the output end of the photodetector is connected to the input end of the signal collector, and the output end of the signal collector is connected to the input end of the signal processor; The distributed optical fiber temperature measurement device with dynamic attenuation compensation can be used to implement the steps of the distributed optical fiber temperature measurement method with dynamic attenuation compensation as described in any one of claims 1 to 8.

10. A distributed optical fiber temperature measurement device with dynamic attenuation compensation, characterized in that: include: An acquisition unit, used to acquire a corresponding relationship between a Raman scattering signal attenuation coefficient and a Rayleigh scattering signal attenuation coefficient; The control unit is used to determine the temperature of the environment to be measured according to the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the first preset temperature, the corresponding relationship between the Raman scattering signal attenuation coefficient and the Rayleigh scattering signal attenuation coefficient, and the Raman scattering signal power and the Rayleigh scattering signal attenuation coefficient of the temperature measuring optical fiber at the first set position at the temperature to be measured.

Images