Buried pipeline multi-source stray current interference coupling test system and test method

Abstract

The invention discloses a buried pipeline multi-source stray current interference coupling test system and test method. The system comprises a test pipeline module, a stray current simulation module, a cathode protection module, a multi-dimensional monitoring module, an intelligent protection module and a data analysis module. A comprehensive system integrating multi-source interference, a full-size pipeline, intelligent protection and real-time monitoring integrates static direct current interference, dynamic direct current interference and alternating current interference into the same system, and the problem that multi-source stray current superposition cannot be truly simulated in the prior art is solved. The comprehensive test of static direct current, dynamic direct current, alternating current stray current and anticorrosive coating defect coupling interference can be simulated, online monitoring of pipe-to-ground potential, current distribution and corrosion rate is realized, the timeliness and accuracy of test data are improved, cooperative work and data linkage analysis of multiple modules are realized, and the test efficiency is improved. A powerful basis is provided for optimizing a protection strategy, and the corrosion protection effect of the buried pipeline is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of buried pipeline corrosion protection, and in particular to a buried pipeline multi-source stray current interference coupling test system and test method. Background Art

[0002] Currently, stray currents generated by power facilities and electrified railroads are increasingly interfering with buried metal pipelines. This stray current interference accelerates pipeline corrosion, posing a serious threat to safe operation. A dual protection approach combining cathodic protection and coating is a common corrosion prevention method for buried pipelines. However, when coating defects or damage occur, combined with stray current interference, the pipe-to-ground potential can deviate from the cathodic protection potential, potentially inducing pipeline corrosion.

[0003] Stray current corrosion is a complex corrosion process that changes with time under the coupling of multiple factors. It is characterized by intense corrosion and concentration in local locations. In terms of stray current detection, it is mainly achieved by measuring the pipe-to-ground potential and current. The traditional test piece method is an intuitive and effective detection method. On-site detection and indoor simulation experiments are mainly based on the principle of the test piece method. However, this test can only reflect the local stray current interference of the pipeline at the buried location of the test piece, and cannot reflect the overall situation. As a result, the existing detection operation has certain limitations and cannot accurately reflect the situation of stray current interference at different locations of the pipeline. When there is stray current interference, the most important thing is to simulate the interference under the actual service environment. Only simple simulation studies can be carried out on small laboratory experimental devices, which are very different from the operating environment and actual conditions of the actual pipeline on site, and cannot truly achieve real and effective interference simulation. Existing simulation test systems have numerous limitations. Most can only simulate a single type of interference source and are unable to realistically replicate the complex interference environment of multiple sources coupled together in actual projects. This makes systematic research on the mechanisms of stray current interference difficult. Regarding protection technologies, existing methods are relatively limited. Existing cathodic protection and electrical drainage technologies are unable to cope with the complex and diverse, multi-source intertwined stray current interference. Furthermore, most equipment used to monitor stray currents uses offline detection, making it difficult to achieve real-time, simultaneous acquisition and dynamic optimization of multiple parameters. Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention proposes a system and method for testing the coupling interference of multiple stray currents in buried pipelines. This system can simulate a comprehensive test of static DC, dynamic DC, and AC stray currents, as well as the coupling interference of corrosion coating defects. This system enables online monitoring of pipe-to-ground potential, current distribution, and corrosion rate, improving the timeliness and accuracy of test data, providing a strong basis for optimizing protection strategies and enhancing the effectiveness of buried pipeline corrosion protection.

[0005] In one aspect, an embodiment of the present invention provides a buried pipeline multi-source stray current interference coupling test system, comprising: A test pipeline module, the test pipeline module comprising a sample pipe and a simulated plot, the sample pipe being preset with anti-corrosion coating defects, the anti-corrosion coating defects comprising a corrosion thinning area, an artificially damaged area, and a coating peeling area; the sample pipe being buried in the simulated plot, the simulated plot comprising a brick red soil layer, a red soil layer, a red soil layer, and a yellow soil layer; A stray current simulation module, comprising a static DC interference source, a dynamic DC interference source, and an AC interference source, wherein the static DC interference source, the dynamic DC interference source, and the AC interference source are used to simulate superimposed current interference; a cathodic protection module comprising a potentiostat and an auxiliary anode bed, wherein the potentiostat monitors the potential of the sample tube in real time via a reference electrode and automatically adjusts the output current by comparing it with a preset value, and the auxiliary anode bed transmits the protection current to the surface of the sample tube via the anode to reduce the surface cathode potential of the sample tube; A multi-dimensional monitoring module, comprising an ER corrosion probe, a fiber optic current sensor, an electronic coupon array, and a distributed humidity sensor, wherein monitoring data from the ER corrosion probe, the fiber optic current sensor, the electronic coupon array, and the distributed humidity sensor are transmitted in real time via a wireless communication unit; an intelligent protection module, the intelligent protection module comprising a solid-state decoupler and an adjustable drainage bed, the solid-state decoupler being mounted at a connection point between the sample tube and the adjustable drainage bed; The data analysis module is used to perform multi-dimensional data fusion on pipe-to-ground potential, corrosion rate, current distribution and soil parameters.

[0006] The embodiments of the present invention have at least the following beneficial effects: The present invention provides a multi-source stray current interference coupling test system for buried pipelines, comprising a test pipeline module, a stray current simulation module, a cathodic protection module, a multi-dimensional monitoring module, an intelligent protection module, and a data analysis module. This comprehensive system integrates multi-source interference, a full-scale pipeline, intelligent protection, and real-time monitoring. It integrates static DC, dynamic DC, and AC interference into a single system, resolving the inability of existing technologies to realistically simulate the superposition of multi-source stray currents. The test pipeline module utilizes a full-scale pipeline and typical soil simulation, combining this with a typical soil environment. This overcomes the limitations of small-scale laboratory models, enhances the engineering reference value of experimental results, and provides high practicality. The stray current simulation module integrates static DC, dynamic DC, and AC interference sources, enabling realistic simulation of complex operating conditions with multiple sources superimposed. The cathodic protection module's potentiostat monitors the potential of the sample pipe in real time using a reference electrode and automatically adjusts the output current by comparing it with a preset value. The auxiliary anode bed transmits the protection current through the anode to the sample pipe surface, reducing the surface cathode potential. The multi-dimensional real-time monitoring module enables simultaneous real-time data acquisition. The intelligent protection module dynamically adjusts drainage efficiency, outperforming traditional offline methods. The data linkage analysis module enables real-time acquisition and intelligent analysis of multiple parameters. Through high-precision data analysis, it provides a reliable basis for optimizing protection under complex operating conditions. Through hardware integration and intelligent control, high-precision sensors, and data linkage technology, dynamic adjustment of drainage equipment and intelligent algorithms enables online monitoring of pipe-to-ground potential, current distribution, and corrosion rate. This improves the timeliness and accuracy of test data, provides a strong basis for optimizing protection strategies, and enhances the effectiveness of buried pipeline corrosion protection.

[0007] According to some embodiments of the present invention, the sample pipe includes at least one 90-degree elbow and two 45-degree elbows, the length of the sample pipe is ≥90 meters and the burial depth is 1.5-2.5 meters.

[0008] According to some embodiments of the present invention, an isolation permeation membrane is provided between the brick red soil layer and the red soil layer, and the ion permeability is less than 10 -6 cm / s, the thickness of the brick red soil layer is 0.5-1.2 meters, and the thickness of the red soil layer is 0.8-1.5 meters, which are used to simulate the impact of seasonal dry-wet alternation on soil conductivity.

[0009] According to some embodiments of the present invention, the output current of the static DC interference source is 1000-3000A and the fluctuation rate is less than 1%, the output voltage of the dynamic DC interference source is ±30V and the ripple factor is less than 5%, the output voltage of the AC interference source is 50V, the current density is greater than 100A / m² and the adjustable frequency is 10-100Hz, the output waveform of the dynamic DC interference source is a square wave, a triangle wave or a sine wave, the switching frequency is 0.1-10Hz, and the phase difference with the AC interference source can be adjusted in real time.

[0010] According to some embodiments of the present invention, the fiber optic current sensor is a distributed fiber grating array, a monitoring node is arranged every 0.5 meters along the axis of the sample tube and an integrated temperature compensation unit is provided. The current measurement accuracy of the fiber optic current sensor is ≤0.2mA.

[0011] On the other hand, an embodiment of the present invention provides a method for testing multi-source stray current interference coupling in buried pipelines, comprising: Excavate trenches and foundation pits, fill with brick red soil, red soil, red soil and yellow soil in a layered structure, and lay an isolation permeable membrane between the brick red soil layer and the red soil layer; Preset anti-corrosion layer defects on the sample pipe, install the sample pipe, and bury the multi-dimensional monitoring module; Perform single device calibration to ensure that the ER probe accuracy verification error is ≤0.5% and the interference source output fluctuation rate is <1%; Conduct multi-source linkage testing, synchronously adjust the amplitude and phase of static DC, dynamic DC and AC interference sources, and simulate multi-band coupling interference to ensure synchronization error less than 3%; Set single or coupled interference working conditions. The intelligent protection module dynamically optimizes drainage efficiency through the fuzzy PID algorithm, dynamically adjusts the protection potential through the cathodic protection module, and collects pipe-to-ground potential, corrosion rate, current distribution, and soil temperature and humidity data in real time. The wavelet transform algorithm is used to eliminate data noise, and the neural network model is combined to predict corrosion trends and evaluate the protection effect.

[0012] According to some embodiments of the present invention, dynamically adjusting the protection potential by the cathodic protection module includes: When the instantaneous deviation of the pipe-to-ground potential is detected to be greater than 50mV, the intelligent protection module automatically switches to emergency mode; The reverse compensation current is released through the adjustable drainage bed and the potential is restored to the safety threshold within 5 seconds.

[0013] According to some embodiments of the present invention, dynamically adjusting the protection potential by the cathodic protection module further includes: A potential dynamic prediction method based on a convolutional neural network model is adopted to perform adaptive adjustment of the protection potential in combination with real-time feedback data from multi-source interference.

[0014] According to some embodiments of the present invention, the intelligent protection module dynamically optimizes drainage efficiency through a fuzzy PID algorithm, including: Dynamically adjust the control parameters of the fuzzy PID algorithm through real-time corrosion rate data; The drainage efficiency is optimized to a pipe-to-ground potential fluctuation range of ≤ ±20mV.

[0015] According to some embodiments of the present invention, the method of predicting corrosion trends and evaluating protection effects by combining a neural network model includes: Through training with historical data of pipeline corrosion tests, the input parameters include pipe-to-ground potential, soil resistivity and interference source intensity, and the output is a dynamic protection potential threshold with an error range of ≤±10mV.

[0016] The buried pipeline multi-source stray current interference coupling test method according to the embodiment of the present invention has at least the following beneficial effects: The buried pipeline multi-source stray current interference coupling test system is suitable for outdoor corrosion detection experiments on buried pipelines in actual soil subjected to stray current interference. It facilitates in-depth research on the impact of stray current interference on the cathodic protection system of buried pipelines. It uses direct and effective simulation monitoring methods to accurately reflect the impact of stray interference on the corrosion protection system. It can simulate comprehensive experiments involving static DC, dynamic DC, and AC stray currents, as well as coupling interference from corrosion coating defects. It can reproduce current interference under complex operating conditions and conduct in-depth research on the impact of the superposition of different stray currents on pipeline corrosion. It integrates high-precision monitoring equipment and intelligent protection modules to achieve online monitoring of pipe-to-ground potential, current distribution, and corrosion rate. This improves the timeliness and accuracy of data, providing a strong basis for optimizing protection strategies. It also enables multi-module collaboration and data linkage analysis, providing a reliable test platform for verifying pipeline corrosion protection technologies.

[0017] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 This is a module diagram of a buried pipeline multi-source stray current interference coupling test system according to an embodiment of the present invention; Figure 2 Schematic diagram of preset defects in a sample pipe and simulated soil distribution in a system for coupling testing multi-source stray current interference in buried pipelines according to an embodiment of the present invention; Figure 3 A diagram showing sample pipe materials for a buried pipeline multi-source stray current interference coupling test system according to an embodiment of the present invention; Figure 4 A preset defect list for a sample pipe of the buried pipeline multi-source stray current interference coupling test system according to an embodiment of the present invention; Figure 5 This is a flow chart of a method for testing multi-source stray current interference coupling in buried pipelines according to an embodiment of the present invention; Figure 6 A schematic diagram of the effect of DC input on AC in a multi-source stray current interference coupling test method for buried pipelines according to an embodiment of the present invention; Figure 7 A schematic diagram of the effect of AC input on DC in a buried pipeline multi-source stray current interference coupling test method according to an embodiment of the present invention; Figure 8 This is a power-off potential diagram of the debugging cathodic protection module of the buried pipeline multi-source stray current interference coupling test method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0020] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0021] In the description of the present invention, "several" means one or more, "multiple" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, and "above," "below," and "within" are understood to include the number itself. The use of terms such as "first" and "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0022] In the description of the present invention, unless otherwise clearly defined, words such as “set,” “install,” “connect,” and “connected” should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above words in the present invention based on the specific content of the technical solution.

[0023] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments.

[0024] Please refer to Figures 1 to 4This embodiment discloses a multi-source stray current interference coupling test system for buried pipelines, including a test pipeline module, a stray current simulation module, a cathodic protection module, a multi-dimensional monitoring module, an intelligent protection module and a data analysis module. The test pipeline module includes a sample pipe and a simulated plot. The sample pipe is preset with anti-corrosion layer defects, and the anti-corrosion layer defects include corrosion thinning areas, artificial damage areas and coating peeling areas; the sample pipe is buried in the simulated plot, and the simulated plot includes brick red soil layer, red soil layer, red soil layer and yellow soil layer. The stray current simulation module includes a static DC interference source, a dynamic DC interference source and an AC interference source. The static DC interference source, the dynamic DC interference source and the AC interference source are used to simulate superimposed current interference. The cathodic protection module includes a constant potential meter and an auxiliary anode bed. The constant potential meter monitors the potential of the sample pipe in real time through a reference electrode, and automatically adjusts the output current by comparing it with a preset value. The auxiliary anode bed transmits the protection current to the surface of the sample pipe through the anode to reduce the surface cathode potential of the sample pipe. The multi-dimensional monitoring module includes an ER corrosion probe, a fiber optic current sensor, an electronic coupon array, and a distributed humidity sensor. Monitoring data from these sensors is transmitted in real time via a wireless communication unit. The intelligent protection module includes a solid-state decoupler and an adjustable drainage bed. The solid-state decoupler is installed at the connection point between the sample pipe and the adjustable drainage bed. The data analysis module integrates multi-dimensional data on pipe-to-ground potential, corrosion rate, current distribution, and soil parameters.

[0025] This buried pipeline multi-source stray current interference coupling test system integrates multi-source interference, a full-scale pipeline, intelligent protection, and real-time monitoring. It integrates static DC, dynamic DC, and AC interference into a single system, resolving the inability of existing technologies to realistically simulate the superposition of multiple stray currents. The test pipeline module utilizes a full-scale pipeline and typical soil simulation, combining this with a typical soil environment. This overcomes the limitations of small-scale laboratory models, enhancing the engineering value of the experimental results and ensuring high practicality. The stray current simulation module integrates static DC, dynamic DC, and AC interference sources, enabling realistic simulation of complex conditions with multiple superpositions. The cathodic protection module's potentiostat monitors the potential of the sample pipe in real time using a reference electrode and automatically adjusts the output current by comparing it to a preset value. An auxiliary anode bed transmits the protection current through the anode to the sample pipe's surface, reducing the surface cathode potential. The multi-dimensional real-time monitoring module enables simultaneous data acquisition. The intelligent protection module dynamically adjusts drainage efficiency, outperforming traditional offline methods. The data linkage analysis module enables real-time acquisition and intelligent analysis of multiple parameters, providing a reliable basis for protection optimization under complex operating conditions through high-precision data analysis. Through hardware integration and intelligent control, high-precision sensors and data linkage technology, dynamic adjustment of drainage equipment and intelligent algorithms can achieve online monitoring of pipe-to-ground potential, current distribution and corrosion rate, improve the timeliness and accuracy of test data, provide a strong basis for optimizing protection strategies, and improve the corrosion protection effect of buried pipelines.

[0026] See Figure 2 and Figure 3 The sample pipe shall include at least one 90-degree elbow and two 45-degree elbows. The length of the sample pipe shall be ≥90 meters and the burial depth shall be 1.5-2.5 meters.

[0027] See Figure 2 An isolation membrane is set between the brick red soil layer and the red soil layer, and the ion permeability is less than 10 -6 cm / s, the thickness of the brick red soil layer is 0.5-1.2 meters, and the thickness of the red soil layer is 0.8-1.5 meters, which are used to simulate the impact of seasonal dry-wet alternation on soil conductivity.

[0028] In some embodiments of the present invention, the output current of the static DC interference source is 1000-3000A and the fluctuation rate is less than 1%, the output voltage of the dynamic DC interference source is ±30V and the ripple factor is less than 5%, the output voltage of the AC interference source is 50V, the current density is greater than 100A / m² and the adjustable frequency is 10-100Hz, the output waveform of the dynamic DC interference source is a square wave, a triangle wave or a sine wave, the switching frequency is 0.1-10Hz, and the phase difference with the AC interference source can be adjusted in real time.

[0029] In some embodiments of the present invention, the fiber optic current sensor is a distributed fiber grating array, with a monitoring node arranged every 0.5 meters along the axis of the sample pipe and an integrated temperature compensation unit. The current measurement accuracy of the fiber optic current sensor is ≤0.2mA.

[0030] See Figure 5 This embodiment also provides a method for conducting a test based on the buried pipeline multi-source stray current interference coupling test system, which mainly includes steps S101 to S106: S101. Excavate trenches and foundation pits, fill them with brick red soil, red soil, red soil and yellow soil in a layered structure, and lay an isolation and permeability membrane between the brick red soil layer and the red soil layer.

[0031] S102. Preset anti-corrosion layer defects on the sample pipe, install the sample pipe, and bury a multi-dimensional monitoring module.

[0032] S103. Perform single device calibration to ensure that the ER probe accuracy verification error is ≤0.5% and the interference source output fluctuation rate is <1%.

[0033] S104. Perform multi-source linkage testing, synchronously adjust the amplitude and phase of static DC, dynamic DC, and AC interference sources, and simulate multi-band coupled interference to ensure that the synchronization error is less than 3%.

[0034] S105. Set a single or coupled interference working condition. The intelligent protection module dynamically optimizes the drainage efficiency through the fuzzy PID algorithm, dynamically adjusts the protection potential through the cathodic protection module, and collects pipe-to-ground potential, corrosion rate, current distribution, and soil temperature and humidity data in real time.

[0035] S106. Use wavelet transform algorithm to eliminate data noise, combine with neural network model to predict corrosion trend, evaluate protection effect, and generate multi-dimensional protection strategy report.

[0036] The step S105 of dynamically adjusting the protection potential by the cathodic protection module includes: When the instantaneous deviation of the pipe-to-ground potential is detected to be greater than 50mV, the intelligent protection module automatically switches to emergency mode; The reverse compensation current is released through the adjustable drainage bed and the potential is restored to the safety threshold within 5 seconds.

[0037] The step S105 of dynamically adjusting the protection potential by the cathodic protection module further includes: A potential dynamic prediction method based on a convolutional neural network model is adopted to perform adaptive adjustment of the protection potential in combination with real-time feedback data from multi-source interference.

[0038] According to the potential deviation trend predicted by the convolutional neural network model, the cathodic protection current is adjusted in advance; combined with real-time potential monitoring, the output current is fine-tuned through the PID algorithm.

[0039] Among them, a potential dynamic prediction method based on a convolutional neural network model is adopted. Convolutional neural networks (CNN) are good at processing data with spatial correlation and are suitable for extracting spatial features of pipeline potential distribution. Local perception and weight sharing are used to reduce model complexity and improve real-time performance.

[0040] (1) Input data and output data Input data: Pipe-to-ground potential distribution (collection points every 0.5 meters along the pipeline axis); Multi-source interference parameters (static DC current, dynamic DC waveform / frequency, AC voltage / frequency); Environmental parameters (soil resistivity, temperature and humidity, location and size of anti-corrosion layer defects).

[0041] Output data: Predicted pipe-to-ground potential within the next 5 seconds (time series); Location of high corrosion risk areas (probabilistic heat map).

[0042] (2) Model training and data preparation Dataset construction: Historical experimental data: including records of potential, current, and corrosion rate under different interference conditions; Field measured data: multi-source interference and potential response data collected from actual pipeline operation and maintenance; Synthetic data: Simulate extreme operating conditions (such as the superposition of multi-band interference) through finite element simulation.

[0043] (3) Training process Data preprocessing: normalization, time series alignment, noise filtering (wavelet transform); Network structure: 3 convolutional layers (extracting spatial features) + LSTM layers (capturing temporal dependencies) + fully connected layers (outputting predicted values); Loss function: Mean squared error (MSE) combined with corrosion risk weight factor to prioritize the prediction accuracy of high corrosion areas.

[0044] The integration of real-time feedback data from multiple sources of interference includes: (1) Data source and collection mechanism Interference source parameters: Static DC: current value (1000-3000A), fluctuation rate; Dynamic DC: waveform type (square wave / triangle wave / sine wave), amplitude (±30V), frequency (0.1-10Hz); AC interference: voltage (50V), frequency (10-100Hz), phase difference (relative to dynamic DC).

[0045] Data collection frequency: High-frequency sampling: pipe-to-ground potential (100Hz), current density (50Hz); Low-frequency update: soil parameters (1Hz), interference source configuration (event trigger).

[0046] (2) Data fusion and input processing Feature Engineering: Spatial encoding: The pipeline axial position is mapped into a two-dimensional grid, and the potential value is filled as the pixel intensity; Time window sliding: Use a window length of 5 seconds and a step size of 1 second to construct a joint time-space input matrix.

[0047] Real-time feedback mechanism: Data buffer: caches the data of the last 10 seconds to ensure continuous model input; Anomaly detection: When the output fluctuation of the interference source exceeds the threshold (such as static DC fluctuation rate > 1%), the model recalibration is triggered.

[0048] The intelligent protection module in step S105 above dynamically optimizes drainage efficiency through a fuzzy PID algorithm, including: Dynamically adjust the control parameters of the fuzzy PID algorithm through real-time corrosion rate data; The drainage efficiency is optimized to a pipe-to-ground potential fluctuation range of ≤ ±20mV.

[0049] The above-mentioned step S106 combines the neural network model to predict the corrosion trend and evaluate the protection effect, including: Through training with historical data of pipeline corrosion tests, the input parameters include pipe-to-ground potential, soil resistivity and interference source intensity, and the output is a dynamic protection potential threshold with an error range of ≤±10mV.

[0050] The neural network corrosion trend prediction model includes: (1) Multimodal input data fusion, the input data includes current / potential spatial distribution (180 measurement points), ER corrosion rate matrix, soil parameters (resistivity / pH / temperature, etc.).

[0051] (2) Using a hybrid neural network architecture, the core modules include: Spatial transformer, whose input is the pipeline potential / current distribution grid (18×10 matrix) and output is the spatial feature vector (128 dimensions); 1D-CNN erosion feature extraction, 3-layer convolution (kernel=5,3,3) → max pooling → full connection; To model temporal environments, Bi-LSTM units (hidden layer 64) capture long-term dependencies.

[0052] (3) Multi-task learning output, the output items include instantaneous corrosion rate, high-risk area and remaining life.

[0053] (4) Training strategy Transfer learning: The pre-trained model is based on 100,000 sets of laboratory accelerated corrosion data; Online learning: Model parameters are incrementally updated every 24 hours.

[0054] The detailed steps of the buried pipeline multi-source stray current interference coupling test method of this embodiment are as follows: 1. Earthwork construction Precise measurements and layout are performed according to the design drawings. The trench, anode installation pit, and test pile foundation pit are excavated manually or mechanically. The trench depth is 1.5-2.5 meters, and the width is determined based on the specifications of the sample pipe to ensure it meets the requirements of pipeline laying and subsequent maintenance. The sample pipe is a full-size pipe ranging from DN200 to DN1200 and ≥90 meters in length. The simulated plot is backfilled in layers using typical regional soils, such as brick red soil, red soil, red soil, and yellow soil. Layers are at least 0.5 meters thick to simulate the electrochemical characteristics of actual buried environments.

[0055] See Figure 2 and Figure 3 The sample pipe uses a Ф914×17.5 steel pipe with prefabricated pipe body and anti-corrosion layer defects. The total length of the pipe body is 94.3 meters. The specifications and dimensions are similar to those of the natural gas pipeline network. The pipeline contains 6 straight pipes of φ914×17.5×12000mm, 1 90-degree elbow, and 2 45-degree elbows. The material is API 5L X70.

[0056] 2. Equipment installation (1) Indoor equipment: Assemble the ultra-high voltage DC grounding electrode discharge simulator, AC transmission line simulator and subway stray current interference simulator, connect a programmable power supply with a DC power supply accuracy of ±1% and an AC power supply harmonic distortion rate of <3%, and complete the electrical circuit verification.

[0057] (2) Outdoor equipment: see Figure 2 and Figure 4 , sample pipes with pre-defects are laid smoothly in the trench. Defect types include corrosion thinning and anti-corrosion coating damage, with at least two locations for each defect type. Simultaneously, intelligent test piles (spacing ≤ 30 meters), ER corrosion probes, and electronic coupons are installed to ensure monitoring points cover the entire pipe section.

[0058] 3. Line connection A copper-core cable with a cross-sectional area of 16 mm² or greater connects the anode bed to the cathodic protection module, with a grounding resistance of 1 Ω or less. The test pile and the in-pipe current monitoring device are connected via shielded twisted-pair cable to prevent electromagnetic interference. A fiber-optic communication network is deployed to enable real-time transmission of monitoring data to the data center.

[0059] 4. System debugging and verification (1) Single device debugging After the equipment was installed, the functionality of each device was tested individually. For the stray current loading simulation system, the ultra-high voltage DC ground electrode discharge simulator, AC transmission line simulator, and subway stray current interference simulator were debugged separately to check whether the static DC current, AC current, and dynamic DC voltage outputs met the set parameters, verifying the accuracy and stability of the simulated current and voltage. During the commissioning of the in-tube current monitoring system, a standard current source was used to calibrate the in-tube current monitoring device, ensuring a resolution of 1mA / 10μV and a measurement error of ≤1%.

[0060] Stray current simulation device: The ultra-high voltage DC grounding electrode discharge simulation device outputs 1000~3000A static DC with a current fluctuation rate of <1%; the AC transmission line simulation device outputs 50V / 100A·m -2 AC interference, frequency 50Hz±0.5%; subway stray current interference simulation device outputs ±30V dynamic DC, ripple factor <5%.

[0061] Calibration of monitoring equipment: Use a standard current source to calibrate the current monitoring device in the tube to ensure a resolution of 1mA / 10μV and a linear error of ≤1%; The ER corrosion probe and electronic coupon are calibrated with standard corrosion test pieces. The resolution of the ER corrosion probe reaches 0.001μm and the repeatability error is less than 2%.

[0062] (2) Linkage debugging After debugging individual devices, coordinated debugging was conducted. System stability was tested when DC and AC interference was superimposed. By adjusting the output parameters of each simulation device and observing the operating conditions of each system component, data synchronization errors were ensured to be less than 5%. The focus was on studying the effects of DC-to-AC, AC-to-DC, and simultaneous variations of both on pipeline corrosion, cathodic protection potential, and other parameters.

[0063] Multi-source interference superposition test: static DC (2000A), dynamic DC (+20V) and AC (50V) interference are loaded in sequence, and the synchronization of pipe-to-ground potential is monitored, for example, time deviation <1ms, amplitude error <5%.

[0064] Intelligent system response test: When the pipe-to-ground potential deviates from the set value (-1.2V CSE) by ±50mV, the cathodic protection module completes adjustment within 5 seconds; the intelligent solid-state decoupler switches to discharge mode within 0.2 seconds, with a dynamic range of discharge current of 0~50A.

[0065] Test system stability when DC and AC interference are superimposed, ensuring data synchronization error is less than 5%. Debugging includes: the impact of tributaries on AC, the impact of AC on DC, and simultaneous changes in DC and AC.

[0066] See Figure 6 By fixing the AC input and changing the DC input, we tested the effect of DC output on AC. The AC voltage was set to a fixed output of 10.5V, and the DC current was increased from 10.5V, 15.5V, 20.5V, 25.5V, and 30.5V. A multimeter was used to measure the AC and DC voltage outputs at the test station. The AC voltage outputs were 5.4V, 5.2V, 5.2V, 5.2V, and 5.2V, respectively, and the DC voltage outputs were 4.84V, 7.2V, 9.71V, 12.19V, and 14.64V, respectively. The test data shows that changing the DC input has almost no effect on the AC.

[0067] See Figure 7 By fixing the DC input and changing the AC input, we tested the effect of AC output on DC. The DC voltage was set to a fixed output of 10.5V, and the AC current increased from 15.5V, 20.5V, 25.5V, 30.5V, and 35.5V. A multimeter was used to measure the AC and DC voltage outputs at the test station. The AC voltage outputs were 5.1V, 11.07V, 13.69V, 16.475V, and 19.272V, respectively, and the DC voltage outputs were 8.3V, 5.89V, 6.41V, 7.16V, and 7.34V, respectively. The test data shows that changing the AC input interferes with both the DC and AC outputs to a certain extent.

[0068] See Figure 8 The cathodic protection system provides cathodic protection for pipelines using an external forced current. By setting different outputs, the required potential output for the pipeline to reach the minimum protection potential can be tested. For output voltages of 2V, 3V, 4V, and 5V, the on-state potentials are -0.864, -0.914, -0.971, and -1.103, respectively, and the off-state potentials are -0.732, -0.766, -0.804, and -0.862, respectively. Based on the measured data, the cathodic protection system's potentiostat must output at least 5V to meet the pipeline's off-state potential of -850mVcse.

[0069] 5. Experimental testing and data analysis (1) Working condition setting Flexible operating conditions can be set based on actual research needs. Adjust the parameters of the multi-source stray current interference coupling simulation system to simulate static DC, dynamic DC, and AC stray current interference of varying intensities and frequencies. Combined with prefabricated pipe and anti-corrosion coating defects in the test pipeline module, the effects of stray current interference on pipeline corrosion under different defect types and severities can be studied. For example, sample pipe locations with typical defects such as corrosion thinning and anti-corrosion coating damage can be selected, and stray current interference under different operating conditions can be applied to observe changes in parameters such as pipe-to-ground potential and corrosion rate.

[0070] Single interference condition: apply static DC (1500A), dynamic DC (±15V) or AC (30V) interference for 24 hours, and record the corrosion rate and potential distribution.

[0071] Coupled interference condition: Static DC (2000A) + dynamic DC (±25V) + AC (40V) are applied simultaneously to simulate an extreme stray current environment.

[0072] (2) Data collection and processing During the experimental testing, a multi-dimensional monitoring module collected various data in real time. After processing using a 24-bit high-precision A / D converter and time-synchronized signal processing technology, the data was transmitted to the data analysis module for analysis. Statistical analysis of the data was performed, and curves were plotted to investigate the relationships between various parameters and to analyze the effects of stray current interference on pipeline corrosion and cathodic protection systems.

[0073] A multi-dimensional monitoring module collects parameters such as pipe-to-ground potential, corrosion current, and soil resistivity at a sampling frequency of ≥1Hz. After 24-bit A / D conversion, the data is noise-removed using wavelet transform, and timestamp alignment enables simultaneous analysis of multi-source data.

[0074] (3) Performance verification Protection effect evaluation: Compared with when the intelligent protection module is not enabled, the pipe-to-ground potential fluctuation range is reduced from ±300mV to ±50mV.

[0075] Calculation of corrosion inhibition rate: According to the ER probe data, the corrosion rate under dynamic DC interference dropped from 0.25 mm / a to 0.05 mm / a, and the inhibition rate reached 80%.

[0076] 6. System maintenance and optimization Utilizing a multi-dimensional monitoring module, the operating status of the equipment is monitored in all directions and in real time. In addition to collecting cathodic protection data, corrosion data, and stray current interference data, the system also monitors the operating parameters of key equipment. For example, the system monitors the power output stability and equipment temperature of the ultra-high voltage DC grounding electrode discharge simulator, AC transmission line simulator, and subway stray current interference simulator; monitors the operating current and voltage of the cathodic protection module, as well as the communication status of each intelligent terminal; and monitors the operating status and drainage current changes of the intelligent solid-state decoupler and adjustable drainage bed in the intelligent protection module.

[0077] A device operating status assessment model was established to assess the device's operating status in real time based on collected data. Appropriate thresholds were set, and when operating parameters exceeded these thresholds, the system automatically issued a warning signal. For example, if the operating current of the cathodic protection module increased or decreased abnormally, this could indicate a problem with the cathodic protection's effectiveness. The system would immediately issue an alarm, prompting staff to conduct prompt inspections and address the issue. By continuously monitoring and assessing the device's operating status, potential faults could be identified in advance, ensuring the stable operation of the test system.

[0078] Check the insulation performance of the intelligent solid-state decoupler every month, and the insulation resistance must be ≥10MΩ; calibrate the monitoring equipment every quarter to ensure data accuracy; train the AI model (neural network model) based on historical data to optimize the cathodic protection potential setting value.

[0079] The buried pipeline multi-source stray current interference coupling test system is suitable for outdoor corrosion detection experiments on buried pipelines in actual soil subjected to stray current interference. It facilitates in-depth research on the impact of stray current interference on the cathodic protection system of buried pipelines. It uses direct and effective simulation monitoring methods to accurately reflect the impact of stray interference on the corrosion protection system. It can simulate comprehensive experiments involving static DC, dynamic DC, and AC stray currents, as well as coupling interference from corrosion coating defects. It can reproduce current interference under complex operating conditions and conduct in-depth research on the impact of the superposition of different stray currents on pipeline corrosion. It integrates high-precision monitoring equipment and intelligent protection modules to achieve online monitoring of pipe-to-ground potential, current distribution, and corrosion rate. This improves the timeliness and accuracy of data, providing a strong basis for optimizing protection strategies. It also enables multi-module collaboration and data linkage analysis, providing a reliable test platform for verifying pipeline corrosion protection technologies.

[0080] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the spirit of the present invention.

Claims

1. A buried pipeline multi-source stray current interference coupling test system, characterized in that: include: A test pipeline module, the test pipeline module comprising a sample pipe and a simulated plot, the sample pipe being preset with anti-corrosion coating defects, the anti-corrosion coating defects comprising a corrosion thinning area, an artificially damaged area, and a coating peeling area; the sample pipe being buried in the simulated plot, the simulated plot comprising a brick red soil layer, a red soil layer, a red soil layer, and a yellow soil layer; A stray current simulation module, comprising a static DC interference source, a dynamic DC interference source, and an AC interference source, wherein the static DC interference source, the dynamic DC interference source, and the AC interference source are used to simulate superimposed current interference; a cathodic protection module comprising a potentiostat and an auxiliary anode bed, wherein the potentiostat monitors the potential of the sample tube in real time via a reference electrode and automatically adjusts the output current by comparing it with a preset value, and the auxiliary anode bed transmits the protection current to the surface of the sample tube via the anode to reduce the surface cathode potential of the sample tube; A multi-dimensional monitoring module, comprising an ER corrosion probe, a fiber optic current sensor, an electronic coupon array, and a distributed humidity sensor, wherein monitoring data from the ER corrosion probe, the fiber optic current sensor, the electronic coupon array, and the distributed humidity sensor are transmitted in real time via a wireless communication unit; an intelligent protection module, the intelligent protection module comprising a solid-state decoupler and an adjustable drainage bed, the solid-state decoupler being mounted at a connection point between the sample tube and the adjustable drainage bed; The data analysis module is used to perform multi-dimensional data fusion on pipe-to-ground potential, corrosion rate, current distribution and soil parameters.

2. The buried pipeline multi-source stray current interference coupling test system according to claim 1 is characterized in that: The sample pipe includes at least one 90-degree elbow and two 45-degree elbows. The length of the sample pipe is ≥90 meters and the burial depth is 1.5-2.5 meters.

3. The buried pipeline multi-source stray current interference coupling test system according to claim 2 is characterized in that: An isolation permeation membrane is provided between the brick red soil layer and the red soil layer, and the ion permeability is less than 10 -6 cm / s, the thickness of the brick red soil layer is 0.5-1.2 meters, and the thickness of the red soil layer is 0.8-1.5 meters, which are used to simulate the impact of seasonal dry-wet alternation on soil conductivity.

4. The buried pipeline multi-source stray current interference coupling test system according to claim 1 is characterized in that: The output current of the static DC interference source is 1000-3000A and the fluctuation rate is less than 1%. The output voltage of the dynamic DC interference source is ±30V and the ripple factor is less than 5%. The output voltage of the AC interference source is 50V, the current density is greater than 100A / m² and the adjustable frequency is 10-100Hz. The output waveform of the dynamic DC interference source is a square wave, a triangle wave or a sine wave, the switching frequency is 0.1-10Hz, and the phase difference with the AC interference source can be adjusted in real time.

5. The buried pipeline multi-source stray current interference coupling test system according to claim 1 is characterized in that: The fiber optic current sensor is a distributed fiber grating array, with a monitoring node arranged every 0.5 meters along the axis of the sample pipe and an integrated temperature compensation unit. The current measurement accuracy of the fiber optic current sensor is ≤0.2mA.

6. A method for testing the interference coupling of multiple-source stray currents in buried pipelines, characterized in that: The buried pipeline multi-source stray current interference coupling test system according to any one of claims 1 to 5 comprises: Excavate trenches and foundation pits, fill with brick red soil, red soil, red soil and yellow soil in a layered structure, and lay an isolation permeable membrane between the brick red soil layer and the red soil layer; Preset anti-corrosion layer defects on the sample pipe, install the sample pipe, and bury the multi-dimensional monitoring module; Perform single device calibration to ensure that the ER probe accuracy verification error is ≤0.5% and the interference source output fluctuation rate is <1%; Conduct multi-source linkage testing, synchronously adjust the amplitude and phase of static DC, dynamic DC and AC interference sources, and simulate multi-band coupling interference to ensure synchronization error less than 3%; Set single or coupled interference working conditions. The intelligent protection module dynamically optimizes drainage efficiency through the fuzzy PID algorithm, dynamically adjusts the protection potential through the cathodic protection module, and collects pipe-to-ground potential, corrosion rate, current distribution, and soil temperature and humidity data in real time. The wavelet transform algorithm is used to eliminate data noise, and the neural network model is combined to predict corrosion trends and evaluate the protection effect.

7. The buried pipeline multi-source stray current interference coupling test method according to claim 6 is characterized in that: The method of dynamically adjusting the protection potential by the cathodic protection module includes: When the instantaneous deviation of the pipe-to-ground potential is detected to be greater than 50mV, the intelligent protection module automatically switches to emergency mode; The reverse compensation current is released through the adjustable drainage bed and the potential is restored to the safety threshold within 5 seconds.

8. The buried pipeline multi-source stray current interference coupling test method according to claim 7 is characterized in that: The dynamically adjusting the protection potential by the cathodic protection module further includes: A potential dynamic prediction method based on a convolutional neural network model is adopted to perform adaptive adjustment of the protection potential in combination with real-time feedback data from multi-source interference.

9. The buried pipeline multi-source stray current interference coupling test method according to claim 6, characterized in that: The intelligent protection module dynamically optimizes drainage efficiency through a fuzzy PID algorithm, including: Dynamically adjust the control parameters of the fuzzy PID algorithm through real-time corrosion rate data; The drainage efficiency is optimized to a pipe-to-ground potential fluctuation range of ≤ ±20mV.

10. The buried pipeline multi-source stray current interference coupling test method according to claim 6, characterized in that: The neural network model is used to predict corrosion trends and evaluate protection effects, including: Through training with historical data of pipeline corrosion tests, the input parameters include pipe-to-ground potential, soil resistivity and interference source intensity, and the output is a dynamic protection potential threshold with an error range of ≤±10mV.

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