System and method for cooperatively sensing leakage of hydrogen-blended natural gas pipeline based on dual physical fields

Abstract

The present invention discloses a system and method for sensing leakage of hydrogen-blended natural gas pipelines based on dual physical fields. The system includes a DTS monitoring subsystem, a DVS monitoring subsystem, and a data fusion analysis module; wherein the DTS monitoring subsystem is used to obtain the temperature change rate data of the target pipeline, the DVS monitoring subsystem is used to obtain the dynamic strain data of the target pipeline, and the data fusion analysis module is used to analyze and fuse the obtained temperature change rate data and dynamic strain data to obtain the target pipeline damage leakage data. The present invention monitors temperature through DTS and vibration through DVS, calculates the leakage probability by fusing the temperature change rate and dynamic strain at the edge, and determines whether a leakage event occurs according to a preset probability threshold, thereby accurately warning of hydrogen-induced damage leakage accidents in hydrogen pipelines and accurately locating them.

Description

Technical Field

[0001] The present invention relates to the technical field of automated monitoring of hydrogen energy storage and transportation safety, and more specifically to a system and method for sensing leakage of a hydrogen-blended natural gas pipeline based on dual physical fields synergistically. Background Art

[0002] Natural gas pipeline hydrogen blending transportation refers to a method of mixing a certain proportion of hydrogen with natural gas and then transporting it over long distances through existing natural gas pipelines. This technology can achieve large-scale, long-distance transportation of hydrogen energy at a relatively low cost, and is an important way to achieve green energy transformation.

[0003] However, the hydrogen environment will cause hydrogen damage to metal pipes. The mechanical properties such as strength, plasticity, and toughness at the welds and pipe defects will be destroyed. Hydrogen molecules penetrate into the internal defects of the metal and expand steadily. When the critical value is reached, the defects develop into unstable expansion. The cracks will expand to both sides in the direction perpendicular to the maximum principal stress, causing brittle fracture and ductile fracture of the pipeline, which in turn leads to safety risks of pipeline gas leakage.

[0004] At present, traditional hydrogen pipeline monitoring methods mainly include pressure detection and flow detection. Pressure detection mainly determines whether there is a leak by monitoring the change in pressure in the pipeline, but the detection sensitivity for small leaks or slow leaks is low, and it is impossible to effectively distinguish whether the pressure change is caused by fluctuations in normal operating conditions or leaks. Flow detection focuses on monitoring the flow changes of hydrogen, which is also difficult to accurately identify small leaks, and it is impossible to effectively monitor the changes in pipeline structure caused by hydrogen embrittlement. At the same time, both methods are difficult to accurately locate the leak point.

[0005] Therefore, with the gradual promotion of hydrogen energy and the large-scale conversion of existing natural gas pipelines to hydrogen pipelines, how to develop an automated method and system that can accurately and real-time monitor hydrogen-induced damage and leakage in hydrogen pipelines over long distances is an urgent problem that technicians in this field need to solve. Summary of the invention

[0006] In view of this, the present invention provides a system and method for sensing leakage of a hydrogen-blended natural gas pipeline based on dual physical fields, which is used to achieve comprehensive, accurate and real-time monitoring of the hydrogen-blended natural gas pipeline.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] On the one hand, the present invention discloses a system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields, comprising a DTS monitoring subsystem, a DVS monitoring subsystem and a data fusion analysis module; wherein the DTS monitoring subsystem is used to obtain temperature change rate data of a target pipeline, the DVS monitoring subsystem is used to obtain dynamic strain data of a target pipeline, and the data fusion analysis module is used to analyze and fuse the obtained temperature change rate data and dynamic strain data to obtain target pipeline damage and leakage data.

[0009] Preferably, the above system also includes a host computer for visually displaying the target pipeline damage and leakage data.

[0010] Preferably, the DTS monitoring subsystem comprises a pulse laser source, an optical fiber circulator, a DTS optical fiber, an optical amplifier, an optical filter, an optoelectronic converter, and a data acquisition module;

[0011] Wherein, the optical fiber circulator 1 and the DTS optical fiber are sequentially arranged along the pulse laser emission direction of the pulse laser source 1;

[0012] The DTS optical fiber is arranged on the surface of the target pipeline and is used to generate a scattered light signal;

[0013] After being transmitted by the optical fiber circulator 1, the scattered light signal passes through the optical amplifier 1, the optical filter 1, the photoelectric converter 1, and the data acquisition module 1 in sequence.

[0014] Preferably, the core of the DTS optical fiber is made of high-purity quartz material with a purity of not less than 99.99%, and the refractive index difference between the core and the DTS optical fiber cladding is controlled at 0.005.

[0015] Preferably, the DVS monitoring subsystem comprises a second pulse laser source, a second fiber circulator, a DVS fiber, a second optical amplifier, a second optical filter, a second photoelectric converter, and a second data acquisition module;

[0016] Wherein, the optical fiber circulator 1 and the DTS optical fiber are sequentially arranged along the pulse laser emission direction of the pulse laser source 2;

[0017] The DTS optical fiber is arranged on the surface of the target pipeline and is used to generate a scattered light signal;

[0018] After being transmitted by the second optical fiber circulator, the scattered light signal passes through the second optical amplifier, the second optical filter, the second photoelectric converter, and the second data acquisition module in sequence.

[0019] Preferably, the core material of the DVS optical fiber is quartz material doped with rare earth elements.

[0020] Preferably, the data fusion analysis module is used to analyze and fuse the acquired temperature change rate data and dynamic strain data to obtain target pipeline damage and leakage data, specifically including the following steps:

[0021] The temperature field change gradient and dynamic strain are integrated to obtain the probability value of pipeline leakage, and whether a leakage event occurs is judged based on the preset probability threshold. If the calculated leakage probability at a certain location at a certain time exceeds the probability threshold, an alarm is issued and the mileage of the leakage point location is pushed.

[0022] Another aspect of the present invention also discloses a method for sensing leakage of a hydrogen-blended natural gas pipeline based on dual physical fields, comprising the following steps:

[0023] S1. Use the DTS monitoring subsystem to obtain the temperature change rate data of the target pipeline;

[0024] S2. Using the DVS monitoring subsystem, obtain the dynamic strain data of the target pipeline;

[0025] S3. Fusing the temperature field change rate and dynamic strain monitoring value of the target pipeline to obtain the leakage probability value of the entire pipeline at the current moment;

[0026] S4. Determine whether a leakage event occurs based on the set probability threshold. If the leakage probability at a certain point along the entire pipeline exceeds the probability threshold, an alarm is issued and the location and mileage of the leakage point are pushed.

[0027] Furthermore, step S3 specifically includes the following steps:

[0028] S31. Obtaining a predicted temperature value according to the temperature time change rate of each monitoring point in the target pipeline;

[0029] S32. Obtaining a predicted dynamic strain value according to the dynamic strain of each monitoring point in the target pipeline;

[0030] S33. constructing a comprehensive prediction value by weighted summation according to the temperature time change rate and dynamic strain of each monitoring point in the target pipeline;

[0031] S34. Based on the obtained temperature prediction value, dynamic strain prediction value, and comprehensive prediction value, a final probability prediction value is obtained again through weighted summation.

[0032] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method and system for sensing leakage of hydrogen-blended natural gas pipeline based on dual physical fields, which has the following beneficial effects:

[0033] The present invention uses DTS to monitor temperature and DVS to monitor vibration, combined with data analysis algorithms, to accurately identify hydrogen-induced damage leakage events in hydrogen pipelines and accurately locate them. If the probability of pipeline leakage at a certain point at the current moment is greater than the preset probability threshold, it is determined that the leakage event has occurred and an alarm is issued and the leakage point is located. This can overcome the blind spots of point sensor monitoring, comprehensively and accurately grasp the pipeline safety situation, and avoid misjudgment and missed judgment.

[0034] The present invention can predict leakage accidents based on fusion probability, which helps operation and maintenance personnel to timely grasp the safety situation of pipeline operation, reasonably arrange maintenance resources, implement precise policies, improve maintenance efficiency and quality, and ensure safe and stable operation of the pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0036] Figure 1 A schematic diagram of the overall structure of a system for collaboratively sensing leakage of a hydrogen-blended natural gas pipeline based on dual physical fields provided in an embodiment of the present invention.

[0037] Figure 2 A flow chart of DTS and DVS collaboratively sensing a hydrogen-blended natural gas pipeline provided by an embodiment of the present invention.

[0038] Figure 3 A schematic diagram of DVS measuring vibration strain signals provided in an embodiment of the present invention.

[0039] Figure 4 A schematic diagram of a DTS temperature measurement time rate of change signal provided by an embodiment of the present invention.

[0040] Figure 5 A schematic diagram of leakage probability after fusion calculation provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The embodiment of the present invention discloses a system for sensing leakage of hydrogen-blended natural gas pipeline based on dual physical fields. Figure 1As shown, it includes, including, a DTS monitoring subsystem, a DVS monitoring subsystem and a data fusion analysis module; wherein, the DTS monitoring subsystem is used to obtain the temperature change rate data of the target pipeline, the DVS monitoring subsystem is used to obtain the dynamic strain data of the target pipeline, and the data fusion analysis module is used to analyze and fuse the acquired temperature change rate data and dynamic strain data to obtain the target pipeline damage and leakage data.

[0043] The DTS monitoring subsystem comprises a pulse laser source, an optical fiber circulator, a DTS optical fiber, an optical amplifier, an optical filter, a photoelectric converter, and a data acquisition module. The optical fiber circulator and the DTS optical fiber are sequentially arranged along the pulse laser emission direction of the pulse laser source. The DTS optical fiber is arranged on the surface of the target pipeline and is used to generate a scattered light signal. After being transmitted by the optical fiber circulator, the scattered light signal passes through the optical amplifier, the optical filter, the photoelectric converter, and the data acquisition module in sequence.

[0044] The DVS monitoring subsystem comprises a second pulse laser source, a second optical fiber circulator, a DVS optical fiber, a second optical amplifier, a second optical filter, a second photoelectric converter, and a second data acquisition module; wherein, along the pulse laser emission direction of the second pulse laser source, a first optical fiber circulator and a DTS optical fiber are sequentially arranged; the DTS optical fiber is arranged on the surface of the target pipeline and is used to generate a scattered light signal; after being transmitted by the second optical fiber circulator, the scattered light signal sequentially passes through the second optical amplifier, the second optical filter, the second photoelectric converter, and the second data acquisition module.

[0045] The pulsed laser source in the above system emits Laser wavelength It is set to λ (determined according to the absorption spectrum range of hydrogen molecules) and the laser energy to E (determined according to the characteristics of the hydrogen pipeline and the monitoring sensitivity requirements) to ensure that the laser interacts fully with the hydrogen molecules so that the optical signal can effectively carry the pipeline status information.

[0046] The DTS monitoring optical fiber core is made of high-purity quartz material with a purity of not less than 99.99%. The refractive index difference between the core and the cladding is controlled at about 0.005. The cladding material is based on quartz and a low-refractive index coating material is set on its outer surface. The coating thickness is about 50μm, the core diameter is 6μm, the attenuation coefficient is less than 0.2dB / km, and the temperature sensitivity is not less than 0.01% / ℃.

[0047] The core material of DVS monitoring optical fiber is quartz material doped with rare earth elements, and the cladding is made of polymer material with high elastic modulus. The thickness is about 20μm, the optical fiber photoelastic coefficient is in the range of 1×10-12 / Pa~3×10-12 / Pa, and the sensitivity to vibration is not less than 0.1dB / (m / s 2 ).

[0048] The DTS monitoring subsystem uses the DTS optical fiber for temperature monitoring based on the fiber Raman scattering and Brillouin scattering effects to measure the temperature time change rate of different monitoring points on the detection pipeline, while the DVS monitoring subsystem uses the phase generated carrier (PGC) demodulation algorithm to sense the pipeline vibration and obtain the dynamic strain of the pipeline.

[0049] The optical fiber sensing network includes DTS (distributed optical fiber temperature measurement system) monitoring optical fiber, DVS (distributed optical fiber vibration monitoring system) monitoring optical fiber and sensor integration. The DTS monitoring optical fiber core should be made of high-purity quartz material with a purity of not less than 99.99%, and the refractive index difference between the core and the cladding is controlled at about 0.005. The cladding material is also based on quartz, and a low-refractive index coating material (such as fluoropolymer coating) can be used on its outer surface, with a coating thickness of about 50μm. This coating can effectively reduce light scattering on the optical fiber surface, reduce light loss, and protect the optical fiber from chemical erosion by the external environment. The core diameter is 6μm to provide sufficient optical signal transmission channels and temperature-related optical effect space. The attenuation coefficient should be less than 0.2dB / km, and the temperature sensitivity should be not less than 0.01% / ℃. The DVS monitoring optical fiber core material is a quartz material doped with rare earth elements (such as erbium, ytterbium, etc.), which can effectively interact with external vibration signals to produce detectable optical signal changes. The cladding is made of polymer materials with high elastic modulus (such as polyimide) with a thickness of about 20 μm, which can effectively transmit external vibrations to the core and has good mechanical stability. The optical fiber should have a significant photoelastic effect, and the photoelastic coefficient (stress-refractive index variation coefficient) should be within a certain range (such as 1×10 -12 / Pa~3×10 -12 / Pa), and has good stability at different vibration frequencies and amplitudes, so as to accurately perceive vibration information by detecting changes in these parameters of the optical signal. The sensitivity of optical fiber to vibration should not be less than 0.1dB / (m / s 2 ), which can ensure that the optical fiber can effectively detect the tiny vibration changes of the pipeline caused by hydrogen embrittlement or other factors. The sensor integration includes DTS and DVS. DTS realizes temperature monitoring based on the Raman scattering and Brillouin scattering effects of optical fiber. According to the Raman scattering temperature measurement principle, the anti-Stokes intensity (I as ) and Stokes intensity (I s ) has the following relationship with temperature (T):

[0050]

[0051] Where: h is Planck's constant, Δv is Raman frequency shift, k is Boltzmann's constant, and C is a constant related to the optical fiber material.

[0052] DVS uses the phase generated carrier (PGC) demodulation algorithm to sense pipeline vibration. In the fiber optic vibration sensing system, the optical signal is phase modulated to load a high-frequency carrier signal. When the pipeline vibration causes the optical fiber phase to change, the PGC demodulation algorithm is used to demodulate the signal containing vibration information. This algorithm can effectively improve the detection sensitivity and signal-to-noise ratio of the signal, making the detection of weak vibration signals more accurate and reliable. Its sensitivity (S) is related to parameters such as vibration frequency (f) and amplitude (A). The specific sensitivity calculation formula is:

[0053] S=k1×f+k2×A

[0054] Among them, k1 and k2 are coefficients determined by the characteristics of optical fiber, which can accurately capture the vibration anomalies caused by changes in pipeline structure due to hydrogen embrittlement.

[0055] The optical signal processing unit is responsible for receiving and processing the optical signal sent back by the optical fiber sensor network. The unit includes an optical amplifier, an optical filter, and a photoelectric converter. The optical amplifier (such as an erbium-doped fiber amplifier with a gain coefficient of G = 20dB / m) is used to increase the strength of weak optical signals to meet the requirements of subsequent analysis and processing; the optical filter uses a high-performance Fabry-Perot filter to filter out environmental noise and other interfering optical signals. The center frequency of the filter is f c Set to 1550Hz, bandwidth B is 10Hz. Through this precise frequency screening, background light noise such as sunlight, radiation from surrounding equipment, and other optical signal interferences of non-related frequencies can be effectively blocked to ensure the purity of the optical signal entering the subsequent photoelectric conversion link. In the actual pipeline monitoring environment, after filtering, the signal-to-noise ratio of the signal can be increased by more than 20dB, which greatly improves the system's detection accuracy for changes in weak optical signals, making DTS's perception of subtle temperature fluctuations and DVS's perception of vibration anomalies more accurate and reliable; the photoelectric converter uses an avalanche photodiode (APD) with a quantum efficiency of up to 80% as a photoelectric converter to efficiently convert the optical signal after amplification and filtering into an electrical signal. The APD has an internal gain mechanism that can produce a larger electrical signal output at a lower optical power input, which is particularly important for the detection of weak optical signals.

[0056] The data fusion analysis module is used to analyze and fuse the acquired temperature change rate data and dynamic strain data to obtain the target pipeline damage and leakage data, which specifically includes the following steps:

[0057] The temperature field change gradient and dynamic strain are integrated to obtain the probability value of pipeline leakage, and whether a leakage event occurs is judged based on the preset probability threshold. If the calculated leakage probability at a certain location at a certain time exceeds the probability threshold, an alarm is issued and the mileage of the leakage point location is pushed.

[0058] The host computer is used to receive the data processed by the data acquisition and analysis fusion module, and visually display the temperature distribution, vibration and other information of the pipeline. When the leakage probability value of a certain point at the current moment exceeds the preset leakage probability threshold, the edge computing device immediately triggers an alarm and pushes an alarm notification containing detailed information such as the leakage location (determined by optical fiber positioning technology, based on the principle of optical time domain reflectometer OTDR to determine the distance between the leakage point and the monitoring end), type, severity (based on the temperature change rate, dynamic strain value and the degree to which the leakage probability value exceeds the preset threshold) to the maintenance personnel.

[0059] On the other hand, the present invention also discloses a method for sensing leakage of hydrogen-blended natural gas pipeline based on dual physical fields. The overall process is as follows: Figure 2 As shown, including:

[0060] S1. Use the DTS monitoring subsystem to obtain the temperature change rate data of the target pipeline;

[0061] S2. Using the DVS monitoring subsystem, obtain the dynamic strain data of the target pipeline;

[0062] S3. Fusing the temperature field change rate and dynamic strain monitoring value of the target pipeline to obtain the leakage probability value of the entire pipeline at the current moment;

[0063] S4. Determine whether a leakage event occurs based on the set probability threshold. If the leakage probability at a certain point along the entire pipeline exceeds the probability threshold, an alarm is issued and the location and mileage of the leakage point are pushed.

[0064] It should be noted that the execution order between steps S1 and S2 can be adjusted.

[0065] Each step of the method of the present invention is described in detail below.

[0066] According to the layout planning of pure hydrogen / hydrogen-doped pipelines and surrounding environmental conditions, the optical path is accurately aligned and the pulsed laser source is deployed using a professional optical adjustment frame and anti-vibration base to ensure the stability of the laser source in complex environments, so that the laser it emits can enter the optical fiber sensing network with minimal coupling loss.

[0067] During the DTS optical fiber laying, special pipeline cleaners are used to remove oil, rust and impurities to ensure that the surface roughness is less than 2.5μm. An appropriate amount of high temperature resistant and hydrogen corrosion resistant epoxy glue is evenly applied on the pipeline surface with a thickness of about 0.2-0.5mm. The DTS monitoring optical fiber is placed tightly against the pipeline wall and the optical fiber is initially fixed with glue. Subsequently, stainless steel U-shaped clamps are installed along the pipeline at intervals of 1m-2m. Bolts and nuts (specifications M4-M6, strength grade 8.8 or above) are tightened to a suitable torque (about 5-8N·m) to further stabilize the optical fiber and prevent it from displacement, loosening or damage due to long-term vibration, pressure fluctuations or temperature stress, ensuring reliable signal transmission.

[0068] DTS optical fiber is used in complex parts such as pipe elbows, tees and valves. Specially adapted arc and branching fixtures (made of polyetheretherketone PEEK or high-performance engineering plastics) are combined with flexible buffer pads (silicone rubber pads with a thickness of 1 to 2 mm) to ensure smooth transition of the optical fiber and uniform stress distribution, avoiding local stress concentration and degradation of optical fiber performance. During installation, glue is used for preliminary positioning, and then the fixture is installed for reinforcement to ensure the stability of optical fiber function in complex structures.

[0069] DVS optical fiber and DTS optical fiber are laid in parallel, maintaining a spacing of 10 to 15 mm. First, a thin layer of highly elastic and aging-resistant organic silicone water (thickness of about 0.1 to 0.3 mm) is applied to the surface of the pipeline. This glue has good flexibility and damping properties, which can buffer the impact of vibration on the optical fiber and improve the quality of vibration signal perception. The optical fiber is gently placed on the glue layer for positioning. Rubber-wrapped metal clips with elastic buffer structures (the metal core is made of aluminum alloy, the rubber outer layer is chloroprene rubber, and the thickness is 3 to 5 mm) are used for fixing every 1.5 to 2 meters. The metal clip provides basic fixing force, and the rubber layer absorbs vibration energy and isolates high-frequency vibration interference of the pipeline, ensuring that the optical fiber stably and sensitively monitors vibration signals, and effectively reduces signal distortion when the pipeline is subjected to external mechanical vibration (such as the vibration frequency of adjacent equipment is 50 to 200 Hz and the amplitude is 0.1 to 0.5 mm). The DVS optical fiber is combined with a curved metal back plate (made of stainless steel) and a flexible adhesive tape at the bend. The optical fiber is first fixed to the back plate with the adhesive tape, and then the back plate is properly tightened to the pipeline with screws to ensure that the optical fiber is stable and the vibration transmission characteristics are stable, maintaining monitoring accuracy and reliability.

[0070] Install the optical signal processing unit, data acquisition and fusion analysis module, and place the optical signal processing unit, data acquisition, analysis module and edge computing equipment in a monitoring room adjacent to the hydrogen pipeline. The room must have constant temperature, constant humidity, dustproof and good grounding conditions to ensure stable operation of the equipment. Use low-loss, high-shielding optical fiber cables and data transmission lines to connect the equipment according to standard wiring specifications to ensure low loss and high reliability of signal transmission.

[0071] The host computer is installed in a control center with network access capability, and is connected to the data acquisition and analysis module through optical fiber or high-speed network cable to achieve remote real-time monitoring and operation.

[0072] First, perform optical path calibration, and set the laser wavelength and energy according to the absorption spectrum characteristics of hydrogen molecules (strong absorption peaks within a specific wavelength range (such as 1500-1600nm)) and the parameters of the hydrogen pipeline (pipe diameter, material, transmission pressure, temperature range, etc.). Use a high-precision spectrum analyzer and optical power meter to monitor and calibrate laser parameters to ensure that the laser and hydrogen fully interact to produce an optical signal that carries accurate pipeline status information. Finely adjust the gain coefficient of the optical amplifier (initial setting is 20dB / m), monitor the output power changes by inputting standard optical signals of different powers, and calibrate to the precise value according to the gain curve to compensate for the fiber transmission loss and improve the signal strength.

[0073] For the Fabry-Perot filter, a tunable laser source is used to emit optical signals of different frequencies, and its center frequency (accurate to 1550Hz) and bandwidth (10Hz) are calibrated to filter out environmental noise (such as sunlight, electromagnetic interference, etc.) outside the noise frequency range to ensure that the pure optical signal enters the photoelectric conversion link. The bias voltage of the photoelectric converter is set and calibrated according to its quantum efficiency curve (80% quantum efficiency corresponds to the bias voltage value) to ensure that the weak optical signal is efficiently converted into an electrical signal and maintains a linear response characteristic, providing a stable and accurate electrical signal source for data acquisition.

[0074] According to the dynamic characteristics of pipeline operation (such as fluid flow frequency range 10 ~ 100Hz, pressure fluctuation period 1 ~ 10s, etc.) and monitoring accuracy requirements (temperature resolution 0.1℃, vibration resolution 0.05mV / (m / s 2 )), set the high-speed acquisition card sampling frequency (such as 1kHz), sampling accuracy (16 bits) and trigger mode (rising edge trigger, the threshold is dynamically set according to the noise floor and signal amplitude).

[0075] The specific process of step S3 is described in detail below:

[0076] According to the temperature time change rate of each monitoring point in the target pipeline, the temperature prediction value is obtained; this process can be achieved through the following function:

[0077]

[0078] Where, ΔT max is the maximum temperature-time change rate in the entire pipeline. is the average temperature time rate of change of the entire pipeline, ΔT i is the temperature time change rate of the ith monitoring point, is the average temperature time change rate in the i-th sliding window. The obtained temperature time change rate signal reference Figure 4 shown.

[0079] According to the dynamic strain of each monitoring point in the target pipeline, the predicted value of dynamic strain is obtained; this process can be achieved by the following function:

[0080]

[0081] Among them, ε max is the maximum dynamic strain in the entire pipeline. is the average dynamic strain of the entire pipeline, ε i is the dynamic strain of the ith monitoring point, is the average dynamic strain in the i-th sliding window. The obtained dynamic strain signal reference Figure 3 shown.

[0082] Then, according to the temperature time change rate and dynamic strain of each monitoring point in the target pipeline, a comprehensive prediction value is constructed by weighted summation; this process can be expressed as:

[0083]

[0084] Finally, based on the obtained temperature prediction value, dynamic strain prediction value, and comprehensive prediction value, the final probability prediction value is obtained through weighted summation again. This process can be expressed as:

[0085] P leak (i) = α1·f1(ΔT i )+α2·f2(ε i )+α3·f3(ΔT i , ε i )

[0086] Among them, i is the monitoring point number, is the temperature time change rate of the ith monitoring point, ε is the dynamic strain, α1, α2, α3 represent the weight values ​​of three different input prediction values ​​and satisfy α1+α2+α3=1. In a specific embodiment, the final probability prediction value is as follows Figure 5 shown.

[0087] The host computer monitoring system receives the fault diagnosis results of the data acquisition and analysis module in real time. When a fault is confirmed, it quickly triggers an alarm based on the fault type (hydrogen leakage or hydrogen embrittlement) and severity. The host computer intelligently matches and generates detailed handling suggestions from the built-in expert knowledge base (covering handling strategies and case experience bases for different fault types and degrees).

[0088] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0089] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields, characterized in that: It includes a DTS monitoring subsystem, a DVS monitoring subsystem and a data fusion analysis module; wherein the DTS monitoring subsystem is used to obtain the temperature change rate data of the target pipeline, the DVS monitoring subsystem is used to obtain the dynamic strain data of the target pipeline, and the data fusion analysis module is used to analyze and fuse the obtained temperature change rate data and dynamic strain data to obtain the target pipeline damage and leakage data.

2. According to claim 1, a system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields is characterized in that: It also includes a host computer for visually displaying the target pipeline damage and leakage data.

3. The system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields according to claim 1 is characterized in that: The DTS monitoring subsystem includes a pulse laser source, an optical fiber circulator, a DTS optical fiber, an optical amplifier, an optical filter, a photoelectric converter, and a data acquisition module; Wherein, the optical fiber circulator 1 and the DTS optical fiber are sequentially arranged along the pulse laser emission direction of the pulse laser source 1; The DTS optical fiber is arranged on the surface of the target pipeline and is used to generate a scattered light signal; After being transmitted by the optical fiber circulator 1, the scattered light signal passes through the optical amplifier 1, the optical filter 1, the photoelectric converter 1, and the data acquisition module 1 in sequence.

4. The system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields according to claim 3 is characterized in that: The core of the DTS optical fiber is made of high-purity quartz material with a purity of not less than 99.99%, and the refractive index difference between the core and the DTS optical fiber cladding is controlled at 0.

005.

5. The system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields according to claim 1 is characterized in that: The DVS monitoring subsystem includes a second pulse laser source, a second optical fiber circulator, a DVS optical fiber, a second optical amplifier, a second optical filter, a second photoelectric converter, and a second data acquisition module; Wherein, the optical fiber circulator 1 and the DTS optical fiber are sequentially arranged along the pulse laser emission direction of the pulse laser source 2; The DTS optical fiber is arranged on the surface of the target pipeline and is used to generate a scattered light signal; After being transmitted by the second optical fiber circulator, the scattered light signal passes through the second optical amplifier, the second optical filter, the second photoelectric converter, and the second data acquisition module in sequence.

6. The system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields according to claim 5 is characterized in that: The core material of the DVS optical fiber is quartz material doped with rare earth elements.

7. The system for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields according to claim 1 is characterized in that: The data fusion analysis module is used to analyze and fuse the acquired temperature change rate data and dynamic strain data to obtain target pipeline damage and leakage data, and specifically includes the following steps: The temperature field change gradient and dynamic strain are integrated to obtain the probability value of pipeline leakage, and whether a leakage event occurs is judged based on the preset probability threshold. If the calculated leakage probability at a certain location at a certain time exceeds the probability threshold, an alarm is issued and the mileage of the leakage point location is pushed.

8. A method for sensing leakage of hydrogen-blended natural gas pipeline based on dual physical fields, characterized in that: The following steps are involved: S1. Use the DTS monitoring subsystem to obtain the temperature change rate data of the target pipeline; S2. Using the DVS monitoring subsystem, obtain the dynamic strain data of the target pipeline; S3. Fusing the temperature field change rate and dynamic strain monitoring value of the target pipeline to obtain the leakage probability value of the entire pipeline at the current moment; S4. Determine whether a leakage event occurs based on the set probability threshold. If the leakage probability somewhere along the entire pipeline exceeds the probability threshold, an alarm is issued and the location and mileage of the leakage point are pushed.

9. The method for sensing hydrogen-blended natural gas pipeline leakage based on dual physical fields according to claim 8, characterized in that: Step S3 specifically includes the following steps: S31. Obtaining a predicted temperature value according to the temperature time change rate of each monitoring point in the target pipeline; S32. Obtaining a predicted dynamic strain value according to the dynamic strain of each monitoring point in the target pipeline; S33. constructing a comprehensive prediction value by weighted summation according to the temperature time change rate and dynamic strain of each monitoring point in the target pipeline; S34. Based on the obtained temperature prediction value, dynamic strain prediction value, and comprehensive prediction value, a final probability prediction value is obtained again through weighted summation.

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