CN116399378A - Enhancement method and system for BOTDA equipment spatial resolution - Google Patents

Enhancement method and system for BOTDA equipment spatial resolution Download PDF

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CN116399378A
CN116399378A CN202310457282.7A CN202310457282A CN116399378A CN 116399378 A CN116399378 A CN 116399378A CN 202310457282 A CN202310457282 A CN 202310457282A CN 116399378 A CN116399378 A CN 116399378A
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optical fiber
abnormal
section
spatial resolution
botda
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刘云鹏
黎晏霖
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Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
North China Electric Power University
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Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
North China Electric Power University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35338—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using other arrangements than interferometer arrangements
    • G01D5/35354—Sensor working in reflection
    • G01D5/35358—Sensor working in reflection using backscattering to detect the measured quantity
    • G01D5/35364—Sensor working in reflection using backscattering to detect the measured quantity using inelastic backscattering to detect the measured quantity, e.g. using Brillouin or Raman backscattering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D18/00—Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for
    • G01D21/02—Measuring two or more variables by means not covered by a single other subclass
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
    • G01K11/322—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Brillouin scattering

Abstract

The invention discloses a method and a system for enhancing the spatial resolution of BOTDA equipment, which belong to the technical field of distributed optical fiber sensing, when the length of a disturbed optical fiber is smaller than the spatial resolution, a PSO-LM algorithm is adopted to carry out double-peak Lorentz fitting on a Brillouin scattering spectrum of a transition region point, the accurate positioning of an abnormal section is realized according to the falling edge of a secondary peak scattering intensity curve representing abnormal section scattering information, the traditional fitting result is corrected by the secondary peak corresponding to the Brillouin frequency shift, the actual abnormal optical fiber section information is demodulated, and the spatial resolution of the existing integrated BOTDA equipment is further improved on the basis of not increasing the complexity of system hardware. The invention can stably improve the spatial resolution of the BOTDA sensing system to within half of the original spatial resolution, the maximum can be 2 times of the sampling resolution, and the relative error is controlled within 5%.

Description

Enhancement method and system for BOTDA equipment spatial resolution
Technical Field
The invention relates to the technical field of distributed optical fiber sensing, in particular to a method and a system for enhancing the spatial resolution of BOTDA equipment.
Background
In the distributed optical fiber sensing technology, the brillouin optical time domain analysis technology (Brillouin optical time domain analysis, BOTDA) has long sensing distance, high spatial resolution and high measurement accuracy, and is far greater than other optical fiber sensing technologies in practical application. The brillouin scattering gain spectrum generated in the optical fiber is in a lorentz spectrum line shape under the influence of phonon attenuation, and a specific equation is shown as follows:
Figure BDA0004199634500000011
wherein g 0 Peak power for the brillouin gain spectrum; v B Is Brillouin frequency shift; deltav B Is the full width at half maximum of the brillouin gain spectrum. The Brillouin frequency shift can be extracted from the Brillouin gain spectrum, and the BOTDA realizes distributed sensing by utilizing the linear relation between the variation of the stimulated Brillouin scattering optical frequency shift of the optical fiber and the temperature and the strain.
When the light pulse propagates along the optical fiber, the light pulse interacts with the detection light to obtain a brillouin gain spectrum of the whole optical fiber, but the brillouin gain spectrum corresponding to a certain point on the optical fiber is formed by the sum of gains generated by each section of optical fiber with the spatial resolution corresponding to the effective pulse length. When the optical fiber senses that local hot spots or deformation smaller than spatial resolution exists, the Brillouin scattering spectrum of the transition region between the background optical fiber and the abnormal section is not a single lorentz type spectrum, but a bimodal scattering spectrum exists, if the abnormal Brillouin scattering spectrum is still subjected to unimodal lorentz fitting, the fitting effect cannot meet the precision requirement, the Brillouin frequency shift has huge deviation, and the actual value of the temperature or strain variation cannot be accurately reflected.
In the prior art, differential pulse pair (Differential pulse-width pairs, DPP), pulse pre-pumping technology, double pulse technology and the like are used for improving the spatial resolution of BOTDA, and the existing BOTDA integrated equipment mainly uses the best-effect differential pulse pair brillouin optical time domain analysis technology (DPP-BOTDA), but still has the condition that the measurement accuracy is rapidly reduced when the length of a disturbed optical fiber is smaller than the spatial resolution, so that an enhancement method and an enhancement system for the spatial resolution of the BOTDA equipment are needed, and the technical problem that the existing optical fiber sensing integrated equipment cannot accurately measure abnormal section information smaller than the spatial resolution is solved.
Disclosure of Invention
In order to solve the problems, the invention aims to start from the mechanism of the Brillouin scattering gain spectrum, utilizes a bimodal fitting algorithm and combines the edge analysis of an abnormal peak curve to provide a method for improving the BOTDA spatial resolution on the basis of not increasing the complexity of system hardware so as to realize the positioning of an abnormal section optical fiber and demodulation of disturbed information and meet the detection requirement.
In order to achieve the above technical object, the present application provides an enhancement method for spatial resolution of a BOTDA device, including the following steps:
performing optical fiber full-section detection on BOTDA equipment through unimodal Lorentz fitting, and collecting the Brillouin scattering gain spectrum and Brillouin frequency shift information of the whole optical fiber;
based on the Brillouin scattering gain spectrum with abnormal offset, obtaining an abnormal section, performing double-peak Lorentz fitting on the abnormal section through a combined algorithm of a PSO algorithm and an LM algorithm, obtaining a secondary peak scattering intensity curve, and positioning the abnormal optical fiber section;
and acquiring the sub-peak Brillouin frequency shift of the abnormal optical fiber section, correcting a single-peak fitting frequency shift result of the abnormal optical fiber section, and demodulating information of the abnormal optical fiber section according to the relation between the Brillouin frequency shift and the temperature and the strain, so as to enhance the spatial resolution of BOTDA equipment.
Preferably, in the process of carrying out optical fiber full-segment detection on BOTDA equipment, a LM algorithm is used for carrying out unimodal Lorentz fitting, and a Brillouin scattering gain spectrum and Brillouin frequency shift information are obtained.
Preferably, in the process of acquiring the abnormal section, the length of the disturbed optical fiber corresponding to the abnormal section is smaller than the spatial resolution of the BOTDA device.
Preferably, in the process of carrying out the double-peak lorentz fitting on the abnormal section, the secondary fitting range is determined by acquiring optical fiber scattering spectrum information around the abnormal section, and the brillouin scattering information representing the secondary peak of the optical fiber abnormal section is extracted according to a combination algorithm to generate a secondary peak scattering intensity curve.
Preferably, in the process of obtaining the secondary peak scattering intensity curve through the combination algorithm, carrying out double-peak lorentz fitting on the abnormal section according to the PSO algorithm to obtain fitting parameter approximate values comprising the primary and secondary peak scattering intensities and the Brillouin frequency shift;
based on an LM algorithm, carrying out iterative solution on the fitting parameter approximation value to obtain a bimodal Lorentz fitting parameter;
and carrying out double-peak Lorentz fitting on the abnormal section based on the double-peak Lorentz fitting parameters to obtain a secondary-peak scattering intensity curve.
Preferably, in the process of positioning the abnormal optical fiber section, the secondary peak scattering intensity curve is subjected to edge analysis, the optical fiber length corresponding to the falling edge of the secondary peak scattering intensity curve is obtained, and the abnormal optical fiber section is positioned.
Preferably, in the process of improving the spatial resolution of the BOTDA equipment, when the Brillouin scattering gain spectrum of the whole optical fiber is collected and no abnormal deviation exists, demodulating the Brillouin frequency shift to obtain the temperature or strain information of the whole optical fiber, and obtaining the relation between the Brillouin frequency shift and the temperature and strain;
based on the relation, demodulating according to the corrected single-peak fitting frequency shift result of the abnormal optical fiber section, and obtaining the information of the abnormal optical fiber section.
The invention provides an enhancement system for the spatial resolution of BOTDA equipment, which comprises the following components:
the data acquisition module is used for carrying out optical fiber full-section detection on the BOTDA equipment through unimodal lorentz fitting and collecting the Brillouin scattering gain spectrum and Brillouin frequency shift information of the whole optical fiber;
the data screening module is used for acquiring a Brillouin scattering gain spectrum with abnormal offset;
the positioning module is used for acquiring an abnormal section based on the Brillouin scattering gain spectrum with abnormal offset, carrying out double-peak Lorentz fitting on the abnormal section through a combined algorithm of a PSO algorithm and an LM algorithm, acquiring a secondary peak scattering intensity curve and positioning the abnormal optical fiber section;
the correction module is used for correcting a single-peak fitting frequency shift result of the abnormal optical fiber section by acquiring a secondary-peak Brillouin frequency shift of the abnormal optical fiber section, demodulating information of the abnormal optical fiber section according to the relation between the Brillouin frequency shift and the temperature and the strain, and enhancing the spatial resolution of BOTDA equipment.
Preferably, the data acquisition module is further configured to perform a unimodal lorentz fit by the LM algorithm.
Preferably, the positioning module is further configured to perform edge analysis on the secondary peak scattering intensity curve, obtain an optical fiber length corresponding to a falling edge of the secondary peak scattering intensity curve, and position the abnormal optical fiber segment.
The invention discloses the following technical effects:
according to the invention, accurate positioning of the abnormal section is realized according to the falling edge of the secondary peak scattering intensity curve, the traditional fitting result is corrected by the secondary peak corresponding to the Brillouin frequency shift, the actual abnormal optical fiber section information is demodulated, and the spatial resolution of the existing integrated BOTDA equipment is further improved;
the invention realizes the positioning of the abnormal section optical fiber and demodulates the disturbed information so as to meet the detection requirement, and has strong applicability and high measurement precision.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of the present invention;
FIG. 2 is a schematic diagram of a technical process flow of the present invention.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, as provided in the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to be within the scope of the present application.
As shown in fig. 1-2, the present invention provides.
The invention provides a method for improving BOTDA spatial resolution based on peak edge analysis, which comprises the following steps:
step one: and carrying out optical fiber full-section detection by adopting unimodal lorentz fitting, and collecting Brillouin scattering gain spectrum and frequency shift information of the whole optical fiber.
Step two: judging whether the three-dimensional Brillouin scattering spectrum has abnormal offset, if not, entering a step eight to directly obtain temperature or strain information of the whole optical fiber according to Brillouin frequency shift demodulation, otherwise, entering a step three.
Step three: and taking the scattering spectrum information of the abnormal section and the surrounding parts thereof.
Step four: and (3) carrying out double-peak Lorentz fitting on the gain spectrum obtained in the step three by using a particle swarm optimization algorithm (Particle Swarm Optimization, PSO) to obtain the main and secondary peak scattering intensity and the Brillouin frequency shift approximate value.
Step five: and (3) taking the scattering spectrum fitting information obtained in the step four as an initial value of a Levenberg-Marquardt algorithm (LM), and iteratively solving a bimodal Lorentz fitting parameter.
Step six: and carrying out edge analysis on the secondary peak scattering intensity curve, and taking the optical fiber length corresponding to the falling edge of the secondary peak scattering intensity curve as the position information of the abnormal optical fiber section.
Step seven: and correcting a single-peak fitting frequency shift result according to the Brillouin frequency shift of the secondary peak corresponding to the abnormal optical fiber section.
Step eight: the information of the abnormal section is demodulated from the relationship between the brillouin frequency shift and the temperature and strain.
Example 1: in order to solve the problem that the existing optical fiber sensing integrated equipment cannot accurately measure abnormal section information smaller than spatial resolution, the invention provides a method for improving BOTDA spatial resolution on the basis of not increasing system hardware complexity.
The basic principle diagram of the invention is shown in fig. 1, and the backward brillouin scattering signal of a certain point on an optical fiber obtained by a pulse light wave incident optical fiber of the BOTDA equipment is not only a single-point signal, but also contains scattering information of the point and a section of optical fiber adjacent to the point, and the length of the small section of optical fiber is the spatial resolution corresponding to the light pulse. When the actual length of the disturbance event is smaller than the spatial resolution, the brillouin scattering spectrum of the transition region point contains abnormal disturbance information and scattering information of a normal background optical fiber, so that the abnormal disturbance information and the normal background optical fiber are not standard lorentz type spectral lines, namely the scattering spectrum is distorted, the lorentz type curve corresponding to the secondary peak in the double-peak region represents the temperature information of the hot spot section, and the brillouin frequency shift corresponding to the main peak is basically consistent with the brillouin frequency shift of the single-peak region and reflects the undisturbed part in the optical fiber.
FIG. 2 is a schematic diagram of a technical process flow of the present invention, in which, because the manual measurement of the distance between an abnormal optical fiber segment and the optical fiber head end is time-consuming and laborious and easily causes a large error, the first step of the present invention is to perform a unimodal Lorentz fitting by using an LM algorithm, perform a preliminary detection on the whole optical fiber segment, and collect the Brillouin scattering gain spectrum and frequency shift information of the whole optical fiber; judging whether the three-dimensional Brillouin scattering spectrum has abnormal offset information or not, if not, entering a step eight to directly obtain temperature or strain information of the whole optical fiber according to Brillouin frequency shift demodulation, otherwise, entering a step three; step three, taking information of the optical fiber scattering spectra of the abnormal section and the surrounding part thereof, determining a secondary fitting range, and fitting the abnormal section with the double-peak Lorentz again; because the LM algorithm is very dependent on an initial value when the LM algorithm is used for fitting a curve, if the set initial value deviates too much from an actual value, the LM algorithm is caused to fall into a local optimal solution, and the Brillouin frequency shift is caused to be larger, therefore, the method aims at the Brillouin scattering spectrum of a transition region, the Brillouin scattering information of a secondary peak representing an abnormal section of the optical fiber is extracted by adopting a PSO and LM algorithm combined mode, the step four is to firstly perform double-peak Lorentz fitting on the gain spectrum obtained in the step three by using the PSO algorithm, and perform a large-scale search and solution to obtain fitting parameter approximate values such as main and secondary peak scattering intensity, brillouin frequency shift and the like, and the final double-peak Lorentz fitting parameter is obtained by performing iterative solution as initial value input of the step five LM algorithms, so that the combination of the PSO algorithm and the LM algorithm can mutually compensate the respective defects, and the problem that the double-peak Lorentz fitting excessively depends on the initial value and is easy to fall into the local optimal solution is solved; step six, carrying out edge analysis on a secondary peak scattering intensity curve representing abnormal section information, taking the falling edge of the secondary peak scattering intensity curve to correspond to the length of the optical fiber, and realizing accurate positioning as the position information of the abnormal optical fiber section according to the schematic diagram shown in fig. 1; step seven, correcting a unimodal fitting frequency shift result according to the Brillouin frequency shift of the corresponding secondary peak of the abnormal optical fiber section, and reducing the measurement error of the sensing system; and step eight, demodulating the information of the abnormal section according to the relation between the Brillouin frequency shift and the temperature and strain, so as to improve the spatial resolution of the distributed sensing system.
The method for improving the BOTDA spatial resolution based on peak edge analysis is introduced in detail, the method for improving the BOTDA spatial resolution based on the peak edge analysis is provided by combining the Brillouin gain spectrum principle and the double-peak fitting principle to carry out edge analysis on an abnormal peak intensity curve at a disturbed optical fiber, when the length of the disturbed optical fiber is smaller than the spatial resolution, the accurate positioning of an abnormal section is realized according to the falling edge of a secondary peak scattering intensity curve, the traditional fitting result is corrected according to the Brillouin frequency shift corresponding to a secondary peak, and the actual abnormal section disturbed information is demodulated. The invention can stably improve the spatial resolution of the BOTDA sensing system to within half of the original spatial resolution, the maximum can be 2 times of the sampling resolution, and the relative error is controlled within 5%.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (10)

1. An enhancement method for the spatial resolution of a BOTDA device, comprising the steps of:
performing optical fiber full-section detection on BOTDA equipment through unimodal Lorentz fitting, and collecting the Brillouin scattering gain spectrum and Brillouin frequency shift information of the whole optical fiber;
based on the Brillouin scattering gain spectrum with abnormal offset, obtaining an abnormal section, performing double-peak Lorentz fitting on the abnormal section through a combined algorithm of a PSO algorithm and an LM algorithm, obtaining a secondary peak scattering intensity curve, and positioning the abnormal optical fiber section;
and acquiring the secondary-peak Brillouin frequency shift of the abnormal optical fiber section, correcting a unimodal fitting frequency shift result of the abnormal optical fiber section, and demodulating information of the abnormal optical fiber section according to the relation between the Brillouin frequency shift and the temperature and the strain, so as to enhance the spatial resolution of the BOTDA equipment.
2. An enhancement method for the spatial resolution of a BOTDA device according to claim 1, characterized in that:
and in the process of carrying out optical fiber full-section detection on BOTDA equipment, carrying out unimodal Lorentz fitting by using an LM algorithm to obtain the Brillouin scattering gain spectrum and the Brillouin frequency shift information.
3. An enhancement method for the spatial resolution of a BOTDA device according to claim 2, characterized in that:
in the process of acquiring the abnormal section, the length of the disturbed optical fiber corresponding to the abnormal section is smaller than the spatial resolution of the BOTDA equipment.
4. A method for enhancing spatial resolution of a BOTDA device as claimed in claim 3, wherein:
and in the process of carrying out double-peak Lorentz fitting on the abnormal section, determining a secondary fitting range by acquiring optical fiber scattering spectrum information around the abnormal section, extracting sub-peak Brillouin scattering information representing the optical fiber abnormal section according to the combination algorithm, and generating the sub-peak scattering intensity curve.
5. An enhancement method for spatial resolution of a BOTDA device as in claim 4, wherein:
in the process of obtaining a secondary peak scattering intensity curve through a combination algorithm, carrying out double-peak lorentz fitting on the abnormal section according to a PSO algorithm to obtain fitting parameter approximate values comprising primary and secondary peak scattering intensities and Brillouin frequency shift;
based on an LM algorithm, carrying out iterative solution on the fitting parameter approximation value to obtain a bimodal Lorentz fitting parameter;
and carrying out double-peak Lorentz fitting on the abnormal section based on the double-peak Lorentz fitting parameters to obtain a secondary-peak scattering intensity curve.
6. An enhancement method for spatial resolution of a BOTDA device in accordance with claim 5, wherein:
and in the process of positioning the abnormal optical fiber section, carrying out edge analysis on the secondary peak scattering intensity curve to obtain the optical fiber length corresponding to the falling edge of the secondary peak scattering intensity curve, and positioning the abnormal optical fiber section.
7. The enhancement method for spatial resolution of a BOTDA device of claim 6, wherein:
in the process of improving the spatial resolution of BOTDA equipment, when abnormal deviation does not exist in the Brillouin scattering gain spectrum of the whole optical fiber, demodulating the Brillouin frequency shift to obtain temperature or strain information of the whole optical fiber, and obtaining the relation between the Brillouin frequency shift and the temperature and strain;
based on the relation, demodulating according to the corrected single-peak fitting frequency shift result of the abnormal optical fiber segment to obtain the information of the abnormal optical fiber segment.
8. An enhancement system for the spatial resolution of a BOTDA device, comprising:
the data acquisition module is used for carrying out optical fiber full-section detection on the BOTDA equipment through unimodal lorentz fitting and collecting the Brillouin scattering gain spectrum and Brillouin frequency shift information of the whole optical fiber;
the data screening module is used for acquiring the Brillouin scattering gain spectrum with abnormal offset;
the positioning module is used for acquiring an abnormal section based on the Brillouin scattering gain spectrum with abnormal offset, carrying out double-peak Lorentz fitting on the abnormal section through a combined algorithm of a PSO algorithm and an LM algorithm, acquiring a secondary peak scattering intensity curve and positioning the abnormal optical fiber section;
the correction module is used for correcting a unimodal fitting frequency shift result of the abnormal optical fiber section by acquiring the secondary peak Brillouin frequency shift of the abnormal optical fiber section, demodulating information of the abnormal optical fiber section according to the relation between the Brillouin frequency shift and the temperature and the strain, and enhancing the spatial resolution of the BOTDA equipment.
9. An enhancement system for the spatial resolution of a BOTDA device as in claim 8, wherein:
the data acquisition module is also used for carrying out unimodal lorentz fitting through an LM algorithm.
10. An enhancement system for the spatial resolution of a BOTDA device as in claim 9, wherein:
the positioning module is further configured to perform edge analysis on the secondary peak scattering intensity curve to obtain an optical fiber length corresponding to a falling edge of the secondary peak scattering intensity curve, and position the abnormal optical fiber section.
CN202310457282.7A 2023-04-24 2023-04-24 Enhancement method and system for BOTDA equipment spatial resolution Pending CN116399378A (en)

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