CN117704295A - Natural gas pipeline leakage detection system and method based on optical fiber sensing - Google Patents

Abstract

The invention discloses a natural gas pipeline leakage detection system and method based on optical fiber sensing, and relates to the technical field of pipeline leakage detection. When the detection system is started in initial operation, sampling points are started at intervals, so that the energy consumption of the detection system is effectively reduced, and when a certain sampling point detects that a pipeline has leakage, the adjacent sampling points of the sampling points are started for auxiliary detection so as to avoid no detection, thereby improving the accuracy of the detection system.

Description

Natural gas pipeline leakage detection system and method based on optical fiber sensing

Technical Field

The invention relates to the technical field of pipeline leakage detection, in particular to a natural gas pipeline leakage detection system and method based on optical fiber sensing.

Background

Natural gas is an important energy resource and is widely used in the fields of heating, power generation, industrial production, household gas and the like, however, the leakage of a natural gas pipeline system can cause environmental pollution, casualties and property loss, so that the safe operation of the pipeline is important;

the optical fiber sensing technology is a highly sensitive monitoring technology for detecting the change of the surrounding environment based on the propagation characteristic of light, and in the natural gas pipeline leakage detection, an optical fiber can be arranged around or in a pipeline, and the sign of gas leakage in the pipeline is detected by monitoring the change of an optical signal.

The prior art has the following defects:

in the conventional detection system, a plurality of detection points are usually arranged on a natural gas pipeline, and optical fiber sensors are arranged inside and outside each detection point for leakage detection, however, in daily use, if the optical fiber sensors of all the detection points are opened, energy waste is caused, the detection cost is increased, and if the number of the detection points is too small, the detection accuracy is possibly reduced;

therefore, the invention provides the natural gas pipeline leakage detection system and the natural gas pipeline leakage detection method based on optical fiber sensing, which can intelligently adjust the use quantity of detection points and the opening and closing of the optical fiber sensors, ensure the detection accuracy and simultaneously avoid energy waste.

Disclosure of Invention

The invention aims to provide a natural gas pipeline leakage detection system and method based on optical fiber sensing, which are used for solving the defects in the background technology.

In order to achieve the above object, the present invention provides the following technical solutions: the natural gas pipeline leakage detection system based on optical fiber sensing comprises an acquisition module, an initial control module, an optical fiber detection module, an acquisition module, an analysis module and an automatic control module;

the acquisition module is used for: the device comprises a sampling module, an optical fiber detection module, a sampling module and a control module, wherein the sampling module is used for acquiring the number of sampling points arranged on a pipeline and numbering a plurality of sampling points;

an initial control module: controlling the interval start detection of sampling points based on the number and the number information of the sampling points arranged on the pipeline;

and the optical fiber detection module: acquiring optical fiber data related to pipeline leakage when the pipeline transmits natural gas;

and the acquisition module is used for: the optical fiber detection module is arranged nearby and used for acquiring a plurality of data related to the pipeline leakage;

and an analysis module: comprehensively analyzing the optical fiber data and a plurality of data, and judging whether the pipeline has a leakage problem or not;

and the automatic control module is used for: when a certain sampling point judges that the pipeline has leakage problem, the sampling points adjacent to the sampling point are started to detect, and whether the detection has misjudgment phenomenon is judged.

Preferably, the optical fiber detection module acquires optical fiber data related to pipeline leakage when the natural gas is transmitted by a pipeline, wherein the optical fiber data comprises a pipeline strain phase index;

the acquisition module is arranged near the optical fiber detection module and is used for acquiring a plurality of data related to pipeline leakage, wherein the plurality of data comprise pipeline pressure fluctuation amplitude values and natural gas flow velocity fluctuation amplitude values.

Preferably, the analysis module comprehensively calculates the pipeline strain phase index, the pipeline pressure fluctuation amplitude and the natural gas flow velocity fluctuation amplitude to obtain the leakage coefficient xl _s The expression is:

in the method, in the process of the invention,the pipeline strain phase index, gy is the pipeline pressure fluctuation amplitude, gl is the natural gas flow velocity fluctuation amplitude, and alpha, beta and gamma are the pipeline strain phase index and the pipeline pressure fluctuation amplitude respectivelyThe value and the proportionality coefficient of the natural gas flow fluctuation amplitude are all larger than 0.

Preferably, the analysis module obtains a leakage coefficient xl _s After that, the leakage coefficient xl _s Comparing with a preset leakage threshold value, if the leakage coefficient xl _s Judging that the pipeline has no leakage problem when the leakage threshold value is less than the leakage threshold value;

if the leakage coefficient xl _s And (5) judging that the pipeline has leakage problems if the leakage threshold value is not less than the leakage threshold value.

Preferably, when a certain sampling point judges that a pipeline has a leakage problem, the automatic control module starts the sampling points adjacent to the sampling point to detect, judges whether the detection has a misjudgment phenomenon, and comprises the following steps:

if the leakage coefficient xl at adjacent sampling points _s If the leakage threshold value is less than the leakage threshold value, continuing to open other sampling points close to the detected leakage sampling point, and if the leakage coefficient xl at the other sampling points is less than the leakage threshold value _s If the leakage threshold value is less than the leakage threshold value, judging that the detection has a misjudgment phenomenon, if the leakage coefficient xl at any sampling point which is continuously opened is not less than the leakage threshold value _s Judging that the detection has no misjudgment phenomenon if the leakage threshold value is not equal to or greater than the leakage threshold value;

if the leakage coefficient xl at adjacent sampling points _s And if the leakage threshold value is not less than or equal to, judging that the detection has no misjudgment phenomenon.

Preferably, the calculation expression of the strain phase index of the pipeline is:

in the method, in the process of the invention,for the strain phase index of the pipe, < > is->Is the wavelength of the fiber optic sensor light and L is the location of the strain scattering event on the pipe.

Preferably, the calculation formula of the pipeline pressure fluctuation amplitude is as follows:

gy＝|V _{actual practice is that of} -V _{Target object} |；

Where gy is the amplitude of the pipeline pressure fluctuation, V _{Actual practice is that of} Representing the actual measured line pressure, V _{Target object} Indicating the desired or set target line pressure.

Preferably, the calculation formula of the fluctuation amplitude of the natural gas flow velocity is as follows:

gl＝|P _{actual practice is that of} -P _{Target object} |；

Wherein gl is the fluctuation amplitude of natural gas flow velocity, P _{Actual practice is that of} Representing the actual measured natural gas flow rate, P _{Target object} Indicating an expected or set target natural gas flow rate.

The invention also provides a natural gas pipeline leakage detection method based on optical fiber sensing, which comprises the following steps:

s1: the method comprises the steps that an acquisition end acquires the number of sampling points arranged on a pipeline and numbers a plurality of sampling points, and sensing equipment and optical fiber detection equipment are arranged at each sampling point;

s2: controlling the interval start detection of sampling points based on the number and the number information of the sampling points arranged on the pipeline;

s3: when natural gas is transmitted through a pipeline, optical fiber detection equipment acquires optical fiber data related to pipeline leakage;

s4: the sensing equipment is arranged near the optical fiber detection module and is used for acquiring a plurality of data related to the pipeline leakage;

s5: comprehensively analyzing the optical fiber data and a plurality of data, and judging whether the pipeline has a leakage problem or not;

s6: when a certain sampling point judges that the pipeline has leakage problem, the sampling points adjacent to the sampling point are started to detect, and whether the detection has misjudgment phenomenon is judged.

In the technical scheme, the invention has the technical effects and advantages that:

1. the invention is used for acquiring the number of sampling points arranged on a pipeline through the acquisition module and numbering a plurality of sampling points, the initial control module controls the sampling point to be opened and detected at intervals based on the number of the sampling points arranged on the pipeline and the numbering information, the analysis module comprehensively analyzes optical fiber data and a plurality of data and then judges whether the pipeline has a leakage problem, and when judging that the pipeline has the leakage problem at a certain sampling point, the automatic control module opens the sampling points adjacent to the sampling point for detection. When the detection system is started in initial operation, sampling points are started at intervals, so that the energy consumption of the detection system is effectively reduced, and when a certain sampling point detects that a pipeline has leakage, the adjacent sampling points of the sampling points are started for auxiliary detection so as to avoid no detection, thereby improving the accuracy of the detection system.

Drawings

In order to more clearly illustrate the embodiments of the present application 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 described in the present invention, and other drawings may be obtained according to these drawings for a person having ordinary skill in the art.

FIG. 1 is a block diagram of a system according to the present invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1: referring to fig. 1, the natural gas pipeline leakage detection system based on optical fiber sensing in this embodiment includes an acquisition module, an initial control module, an optical fiber detection module, an acquisition module, an analysis module and an automatic control module;

the acquisition module is used for: the method is used for acquiring the number of sampling points arranged on the pipeline and numbering a plurality of sampling points, each sampling point is provided with an acquisition module and an optical fiber detection module, and the number of the sampling points and the numbering information are sent to an automatic control module, and comprises the following steps:

installing an acquisition module and an optical fiber detection module:

the acquisition module and the optical fiber detection module are arranged on the pipeline, so that the acquisition module and the optical fiber detection module are ensured to be connected correctly and can work normally. These modules may be used to monitor the condition of the pipe, temperature, pressure, humidity or other parameters that need to be detected.

Determining the number of sampling points:

the number of sampling points set on the pipe is determined using a suitable method. This may be determined based on the length, diameter, internal environment of the pipe, or detection requirements.

Each sample point is assigned a unique number:

each sample point is assigned a unique number or character number. It is ensured that these numbers are sufficiently unique to be identified in subsequent data processing. Software or hardware tools may be used to record and manage these numbers.

The sampling point information is sent to an automatic control module:

and a data transmission module is arranged on each sampling point and is responsible for transmitting the serial number information of the sampling point and the information of the related acquisition module and the related optical fiber detection module to an automatic control module. This may be accomplished by wireless communication, wired communication, or other suitable means of communication.

Data transmission protocol:

the data format and protocol of the sample point information transmission is determined. In general, a data structure needs to be defined, which includes fields such as a sampling point number, acquisition module information, and fiber detection module information. Ensuring that the automatic control module is able to parse and process these data.

The automatic control module receives and processes the data:

a program for receiving and processing the sampling point information is set in the automatic control module. The program should be responsible for parsing the received information, associating numbers with the corresponding acquisition modules and fiber optic detection modules, and storing such information for subsequent pipeline monitoring and management.

Testing and maintenance:

after installation and configuration is complete, the system is tested to ensure that the sample point information is properly transmitted and processed. And (5) regularly carrying out system maintenance to ensure the normal operation of all sampling points and related equipment.

An initial control module: based on the number of sampling points and the number information set on the pipeline, control the sampling point interval on-detection (for example, after the first sampling point is started, the second sampling point is not started, and the third sampling point is started, so that the method comprises the following steps of:

receiving sampling point information:

the automatic control module should receive the number of sampling points and the number information transmitted from the acquisition module. This information will be used to determine which sampling points need to be detected on for a particular period of time.

Defining a detection interval:

a detection interval between each sampling point is determined, and when to begin detection. This may be defined based on time, event triggers, or other conditions. For example, the detection time interval of each sampling point may be set to 10 minutes, and detection is started at the start-up timing.

Programming control logic:

control logic is written in the initial control module to determine which sampling points should be turned on for detection during the current time period based on the number information of the sampling points. This may be accomplished through the use of conditional statements, loops, or other programming structures.

And (3) opening detection:

when the initial control module determines that a certain sampling point needs to be started for detection, a detection starting instruction is sent to the corresponding acquisition module and the optical fiber detection module. This will activate the relevant device to start data acquisition and leak detection.

Timing control:

a timer or other time control mechanism is used to ensure that the detection of the current sample point is turned off after each detection time interval has ended and the detection of the next sample point is turned on for the next time period.

Data recording and processing:

during the detection process, the automatic control module should monitor and record the collected data for subsequent analysis and reporting. Such data may include pipeline conditions, leak conditions, or other relevant parameters.

And (3) loop execution:

and continuing to circularly execute the control logic until all sampling points are detected or stopping detection according to the requirement.

Exception handling:

an exception handling mechanism is implemented in the control module to cope with possible faults or error conditions, ensuring the reliability and stability of the system.

Maintenance and monitoring:

the initial control module is maintained and monitored regularly to ensure its normal operation. Any fault or abnormal condition is handled in time to reduce system downtime.

And the optical fiber detection module: when natural gas is transmitted through a pipeline, acquiring optical fiber data related to pipeline leakage, and sending the optical fiber data to an analysis module;

and the acquisition module is used for: the optical fiber detection module is arranged near the optical fiber detection module and is used for acquiring a plurality of items of data related to the pipeline leakage and sending the plurality of items of data to the analysis module;

and an analysis module: after comprehensively analyzing the optical fiber data and the multiple data, judging whether the pipeline has a leakage problem or not, and sending a judging result to an automatic control module;

and the automatic control module is used for: when judging that a pipeline has a leakage problem at a certain sampling point, starting the adjacent sampling points of the sampling points to detect (if the sampling point has only one adjacent sampling point, starting one adjacent sampling point, if the sampling point has two adjacent sampling points, starting the two adjacent sampling points), judging whether the detection has a misjudgment phenomenon, and sending a warning signal to a management center when confirming that the pipeline has the leakage phenomenon, wherein the method comprises the following steps:

detecting the state of a pipeline:

the fiber optic detection module and the acquisition module at each sampling point continuously monitor the condition of the pipeline. When an abnormal signal is detected at a certain sampling point, which indicates that a leakage problem may exist, further processing will be triggered.

Determining adjacent sampling points:

according to the structure and layout information of the pipeline, the automatic control module determines which sampling points are adjacent sampling points of the current sampling point. In general, there may be one or two adjacent sampling points, depending on the manner in which the pipes are connected.

Starting detection of adjacent sampling points:

when detecting that a certain sampling point has a leakage problem, the automatic control module should send an instruction to start an adjacent sampling point for detection. This may be achieved by sending a signal or instruction to the control module of the adjacent sampling point.

Detecting and confirming leakage:

and after the detection is started at the adjacent sampling points, monitoring and recording corresponding data. The automatic control module needs to analyze these data to confirm whether a leakage phenomenon exists. This can be achieved by comparing the changes and features of the data to ensure that the leak condition is accurately confirmed.

Sending an alarm signal:

if the automatic control module confirms that the pipeline has leakage phenomenon, the automatic control module sends an alarm signal to the management center. This may be accomplished by network communication or other suitable means of communication. The alert signal should include information about the location, severity and possible impact of the leak.

Misjudgment detection:

before sending the warning signal, the automatic control module can perform erroneous judgment detection. This may be accomplished by further data analysis and verification to ensure that the determination of leakage is accurate and not false positives due to system noise or other interference.

Emergency measures:

after sending the warning signal, the automatic control module may trigger corresponding emergency measures, such as closing valves, notifying maintenance personnel or activating an emergency discharge system, to minimize the effects of leakage.

Logging and reporting:

all event data and alert signals are recorded and reports are generated for subsequent analysis and review. This helps to improve the performance and reliability of the pipeline monitoring system.

According to the method, the acquisition module is used for acquiring the number of the sampling points arranged on the pipeline and numbering the sampling points, the initial control module controls the sampling point interval to open detection based on the number and the numbering information of the sampling points arranged on the pipeline, the analysis module comprehensively analyzes the optical fiber data and the multiple data and then judges whether the pipeline has a leakage problem, and when judging that the pipeline has the leakage problem at a certain sampling point, the automatic control module opens the sampling points adjacent to the sampling points to detect. When the detection system is started in initial operation, sampling points are started at intervals, so that the energy consumption of the detection system is effectively reduced, and when a certain sampling point detects that a pipeline has leakage, the adjacent sampling points of the sampling points are started for auxiliary detection so as to avoid no detection, thereby improving the accuracy of the detection system.

Example 2: when the optical fiber detection module transmits natural gas through a pipeline, optical fiber data related to pipeline leakage are acquired, the optical fiber data comprise pipeline strain phase indexes, and the calculation expression is as follows:

in the method, in the process of the invention,for the strain phase index of the pipe, < > is->Is the wavelength of the fiber optic sensor light, L is the location of the strain scattering event on the pipe;

the greater the phase index of the strain in the pipe, the greater the strain in the pipe surface, and in a distributed optical fiber sensor, the strain in the pipe surface is detected by measuring the phase change of the optical signal, which is a common method, when the pipe is strained or deformed, the light wave in the optical fiber will undergo a phase change, and this phase change is usually related to the strength and position of the strain, and in general, the greater the value of the phase change means the greater the strain at the position monitored by the optical fiber sensor, which can be used to detect the strain condition of the pipe surface, and may indicate that there is a problem in the pipe, such as that the pipe is affected by external force or leakage;

the acquisition module is arranged near the optical fiber detection module and is used for acquiring a plurality of data related to pipeline leakage, wherein the plurality of data comprise pipeline pressure fluctuation amplitude values and natural gas flow velocity fluctuation amplitude values;

the calculation formula of the pipeline pressure fluctuation amplitude is as follows:

gy＝|V _{actual practice is that of} -V _{Target object} |；

Where gy is the amplitude of the pipeline pressure fluctuation, V _{Actual practice is that of} Representing the actual measured line pressure, V _{Target object} Indicating a desired or set target line pressure;

the greater the magnitude of the pipeline pressure fluctuation, the more:

abnormal pressure fluctuations: large amplitude pressure deviations may indicate abnormal pressure fluctuations in the piping system, which may be caused by valve operation in the piping system, equipment failure, or external factors;

leakage or damage: the increased pressure deviation of the piping system may also be caused by leakage or damage to the piping system, which may cause the pressure inside the piping to decrease, thereby causing deviation;

pressure control problem: an increase in pressure deviation of the piping system may indicate that there is a pressure control problem, which may be caused by a malfunction or improper adjustment of the pressure regulating device;

abnormal operation: an operating abnormality of the piping system may lead to an increase in pressure deviation, which may include valve operating errors, pipe overload or overheating, etc.

The calculation formula of the fluctuation amplitude of the natural gas flow velocity is as follows:

gl＝|P _{actual practice is that of} -P _{Target object} |；

Wherein gl is the fluctuation amplitude of natural gas flow velocity, P _{Actual practice is that of} Representing the actual measured natural gas flow rate, P _{Target object} Indicating an expected or set target natural gas flow rate;

abnormal flow rate: a larger flow rate deviation value may indicate that there is a significant anomaly in the natural gas flow rate in the pipeline compared to the target flow rate within the normal operating range, which may be due to a blockage inside the pipeline, increased resistance, equipment failure, or other reasons;

pipeline leakage: an increase in natural gas flow rate deviation in the tubing may also be an indication of leakage, which may result in an abnormal increase in flow rate, as part of the natural gas escapes through the leak points, thereby reducing the flow rate;

flow rate control problem: a large flow rate deviation may indicate that there is a problem with flow rate control of the piping system, which may be due to improper valve operation, control system failure, or human error, etc.;

poor pipeline condition: problems such as damage, blockage or corrosion inside the pipeline can lead to large flow rate deviations, which can affect the flow of natural gas in the pipeline, thereby causing flow rate anomalies.

The analysis module comprehensively analyzes the optical fiber data and the multiple data and then judges whether the pipeline has a leakage problem or not;

the analysis module comprehensively calculates the strain phase index of the pipeline, the fluctuation amplitude of the pipeline pressure and the fluctuation amplitude of the natural gas flow velocity to obtain the leakage coefficient xl _s The expression is:

in the method, in the process of the invention,the pipeline strain phase index, gy is the pipeline pressure fluctuation amplitude, gl is the natural gas flow velocity fluctuation amplitude, and alpha, beta and gamma are the pipeline strain phase index and the pipeline pressure fluctuation amplitude respectivelyThe ratio coefficient of the natural gas flow fluctuation amplitude, and alpha, beta and gamma are all larger than 0;

the analysis module obtains the leakage coefficient xl _s After that, the leakage coefficient xl _s Comparing with a preset leakage threshold value, if the leakage coefficient xl _s Judging that the pipeline has no leakage problem when the leakage threshold value is less than the leakage threshold value;

if the leakage coefficient xl _s And (5) judging that the pipeline has leakage problems if the leakage threshold value is not less than the leakage threshold value.

When judging that a pipeline has leakage problem at a certain sampling point, the automatic control module starts the sampling points adjacent to the sampling point to detect, judges whether misjudgment exists in detection, and specifically comprises the following steps:

if the leakage coefficient xl at adjacent sampling points _s If the leakage threshold value is less than the leakage threshold value, continuing to open other sampling points close to the detected leakage sampling point, and if the leakage coefficient xl at the other sampling points is less than the leakage threshold value _s If the leakage threshold value is less than the leakage threshold value, judging that the detection has a misjudgment phenomenon, if the leakage coefficient xl at any sampling point which is continuously opened is not less than the leakage threshold value _s Judging that the detection has no misjudgment phenomenon if the leakage threshold value is not equal to or greater than the leakage threshold value;

if the leakage coefficient xl at adjacent sampling points _s And if the leakage threshold value is not less than or equal to, judging that the detection has no misjudgment phenomenon.

Example 3: referring to fig. 1, the method for detecting leakage of a natural gas pipeline based on optical fiber sensing according to the present embodiment includes the following steps:

the acquisition end acquires the number of sampling points arranged on a pipeline and numbers the sampling points, sensing equipment and optical fiber detection equipment are arranged at each sampling point, based on the number and the number information of the sampling points arranged on the pipeline, the sampling points are controlled to be opened at intervals for detection (for example, after a first sampling point is opened, a second sampling point is not opened, and a third sampling point is opened, so that the detection is pushed), when the pipeline transmits natural gas, the optical fiber detection equipment acquires optical fiber data related to pipeline leakage, the sensing equipment is arranged near an optical fiber detection module and is used for acquiring multiple data related to the pipeline leakage, judging whether the pipeline has leakage problems after comprehensively analyzing the optical fiber data and the multiple data, and when judging that the pipeline has leakage problems at a certain sampling point, starting the sampling points adjacent to the sampling points for detection (if the sampling points have only one adjacent sampling point, then starting one adjacent sampling point, and if the sampling points have two adjacent sampling points, then starting the two adjacent sampling points) judging whether the detection has false judgment phenomenon.

The above formulas are all formulas with dimensions removed and numerical values calculated, the formulas are formulas with a large amount of data collected for software simulation to obtain the latest real situation, and preset parameters in the formulas are set by those skilled in the art according to the actual situation.

In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended only to assist in the explanation of the invention. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise form disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best understand and utilize the invention. The invention is limited only by the claims and the full scope and equivalents thereof.

Claims (9)

1. Natural gas line leak detection system based on optical fiber sensing, its characterized in that: the system comprises an acquisition module, an initial control module, an optical fiber detection module, an acquisition module, an analysis module and an automatic control module;

the acquisition module is used for: the device comprises a sampling module, an optical fiber detection module, a sampling module and a control module, wherein the sampling module is used for acquiring the number of sampling points arranged on a pipeline and numbering a plurality of sampling points;

an initial control module: controlling the interval start detection of sampling points based on the number and the number information of the sampling points arranged on the pipeline;

and the optical fiber detection module: acquiring optical fiber data related to pipeline leakage when the pipeline transmits natural gas;

and the acquisition module is used for: the optical fiber detection module is arranged nearby and used for acquiring a plurality of data related to the pipeline leakage;

and an analysis module: comprehensively analyzing the optical fiber data and a plurality of data, and judging whether the pipeline has a leakage problem or not;

and the automatic control module is used for: when a certain sampling point judges that the pipeline has leakage problem, the sampling points adjacent to the sampling point are started to detect, and whether the detection has misjudgment phenomenon is judged.

2. The fiber optic sensing based natural gas pipeline leak detection system of claim 1, wherein: when the optical fiber detection module transmits natural gas through a pipeline, optical fiber data related to pipeline leakage are obtained, wherein the optical fiber data comprise pipeline strain phase indexes;

the acquisition module is arranged near the optical fiber detection module and is used for acquiring a plurality of data related to pipeline leakage, wherein the plurality of data comprise pipeline pressure fluctuation amplitude values and natural gas flow velocity fluctuation amplitude values.

3. The fiber optic sensing based natural gas pipeline leak detection system of claim 2, wherein: the analysis module comprehensively calculates the pipeline strain phase index, the pipeline pressure fluctuation amplitude and the natural gas flow velocity fluctuation amplitude to obtain a leakage coefficient xl _s The expression is:

in the method, in the process of the invention,the pipeline strain phase index, gy is pipeline pressure fluctuation amplitude, gl is natural gas flow velocity fluctuation amplitude, alpha, beta and gamma are respectively proportional coefficients of the pipeline strain phase index, the pipeline pressure fluctuation amplitude and the natural gas flow velocity fluctuation amplitude, and alpha, beta and gamma are all larger than 0.

4. A natural gas pipeline leak detection system based on fiber optic sensing as defined in claim 3, wherein: the analysis module obtains a leakage coefficient xl _s After that, the leakage coefficient xl _s Comparing with a preset leakage threshold value, if the leakage coefficient xl _s Judging that the pipeline has no leakage problem when the leakage threshold value is less than the leakage threshold value;

if the leakage coefficient xl _s And (5) judging that the pipeline has leakage problems if the leakage threshold value is not less than the leakage threshold value.

5. The fiber optic sensing based natural gas pipeline leak detection system of claim 4, wherein: when judging that a pipeline has leakage problem at a certain sampling point, the automatic control module starts the sampling points adjacent to the sampling point to detect, judges whether the detection has misjudgment phenomenon or not, and comprises the following steps:

if the leakage coefficient xl at adjacent sampling points _s If the leakage threshold value is less than the leakage threshold value, continuing to open other sampling points close to the detected leakage sampling point, and if the leakage coefficient xl at the other sampling points is less than the leakage threshold value _s If the leakage threshold value is less than the leakage threshold value, judging that the detection has a misjudgment phenomenon, if the leakage coefficient xl at any sampling point which is continuously opened is not less than the leakage threshold value _s Judging that the detection has no misjudgment phenomenon if the leakage threshold value is not equal to or greater than the leakage threshold value;

if the leakage coefficient xl at adjacent sampling points _s And if the leakage threshold value is not less than or equal to, judging that the detection has no misjudgment phenomenon.

6. The fiber optic sensing based natural gas pipeline leak detection system of claim 5, wherein: the calculation expression of the strain phase index of the pipeline is as follows:

in the method, in the process of the invention,for the strain phase index of the pipe, < > is->Is the wavelength of the fiber optic sensor light and L is the location of the strain scattering event on the pipe.

7. The fiber optic sensing based natural gas pipeline leak detection system of claim 6, wherein: the calculation formula of the pipeline pressure fluctuation amplitude is as follows:

gy＝|V _{actual practice is that of} -V _{Target object} |；

Where gy is the amplitude of the pipeline pressure fluctuation, V _{Actual practice is that of} Representing the actual measured line pressure, V _{Target object} Indicating the desired or set target line pressure.

8. The fiber optic sensing based natural gas pipeline leak detection system of claim 7, wherein: the calculation formula of the fluctuation amplitude of the natural gas flow velocity is as follows:

gl＝|P _{actual practice is that of} -P _{Target object} |；

Wherein gl is the fluctuation amplitude of natural gas flow velocity, P _{Actual practice is that of} Representing the actual measured natural gas flow rate, P _{Target object} Indicating an expected or set target natural gas flow rate.

9. A natural gas pipeline leakage detection method based on optical fiber sensing, which is realized by the detection system of any one of claims 1-8, and is characterized in that: the detection method comprises the following steps:

s1: the method comprises the steps that an acquisition end acquires the number of sampling points arranged on a pipeline and numbers a plurality of sampling points, and sensing equipment and optical fiber detection equipment are arranged at each sampling point;

s2: controlling the interval start detection of sampling points based on the number and the number information of the sampling points arranged on the pipeline;

s3: when natural gas is transmitted through a pipeline, optical fiber detection equipment acquires optical fiber data related to pipeline leakage;

s4: the sensing equipment is arranged near the optical fiber detection module and is used for acquiring a plurality of data related to the pipeline leakage;

s5: comprehensively analyzing the optical fiber data and a plurality of data, and judging whether the pipeline has a leakage problem or not;

s6: when a certain sampling point judges that the pipeline has leakage problem, the sampling points adjacent to the sampling point are started to detect, and whether the detection has misjudgment phenomenon is judged.