Test System and Method for Multi-Source Stray Current Interference Coupling in Buried Pipelines

Abstract

This invention discloses a multi-source stray current interference coupling test system and method for buried pipelines. The system includes 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. It integrates multi-source interference, full-size pipeline, intelligent protection, and real-time monitoring into a comprehensive system, combining static DC, dynamic DC, and AC interference into a single system. This solves the problem that existing technologies cannot realistically simulate the superposition of multi-source stray currents. It can simulate comprehensive tests of static DC, dynamic DC, AC stray currents, and coupling interference from corrosion layer defects, enabling online monitoring of pipe-to-ground potential, current distribution, and corrosion rate. This improves the timeliness and accuracy of test data and allows for collaborative work and data linkage analysis of multiple modules, providing strong evidence for optimizing protection strategies and improving the corrosion protection effect of buried pipelines.

Description

Technical Field

[0001] This invention relates to the field of corrosion protection technology for buried pipelines, and in particular to a multi-source stray current interference coupling test system and test method for buried pipelines. Background Technology

[0002] Stray currents generated by power facilities and electrified tracks are increasingly interfering with buried metal pipelines. This stray current interference accelerates pipeline corrosion, posing a serious threat to the safe operation of pipelines. A dual protection method combining cathodic protection and coating is a common corrosion protection approach for buried pipelines. When the coating is defective or damaged, coupled with stray current interference, the pipeline's potential is highly likely to deviate from the cathodic protection potential, thus triggering corrosion.

[0003] Stray current corrosion is a complex corrosion process that varies over time under the coupled effects of multiple factors, characterized by intense corrosion and concentration in localized areas. Stray current detection is primarily achieved by measuring pipe-to-ground potential and current. The traditional test piece method is a direct and effective detection method, and both field testing and indoor simulation experiments are mainly based on this principle. However, this test can only reflect localized stray current interference in the pipeline at the test piece's location, and cannot reflect the overall situation. This leads to limitations in current testing methods, failing to accurately reflect the stray current interference at different locations in the pipeline. When dealing with stray current interference, the most important thing is to simulate the interference under actual service conditions. Small-scale laboratory experimental devices can only conduct simple simulation studies, which differ significantly from the actual operating environment and real conditions of pipelines in the field, and cannot truly achieve realistic and effective interference simulation.

[0004] Existing simulation systems have many limitations. Most can only simulate single types of interference sources and cannot realistically reproduce the complex interference environment of multi-source coupling in actual engineering, making systematic research on stray current interference mechanisms extremely difficult. In terms of protection technologies, the methods are relatively limited. Existing cathodic protection and electrical drainage technologies are insufficient to cope with complex, diverse, and intertwined stray current interference. Furthermore, most devices used to monitor stray currents employ offline detection methods, making it difficult to achieve real-time synchronous acquisition and dynamic optimization of multiple parameters. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a multi-source stray current interference coupling test system and method for buried pipelines, which can simulate the comprehensive test of static DC, dynamic DC, AC stray currents and corrosion layer defect coupling interference, realize 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.

[0006] On one hand, embodiments of the present invention provide a multi-source stray current interference coupling test system for buried pipelines, comprising:

[0007] The test pipeline module includes a sample pipe and a simulated plot. The sample pipe is pre-designed with anti-corrosion layer defects, including corrosion thinning zones, artificial damage zones, and coating peeling zones. The sample pipe is buried in the simulated plot, which includes lateritic soil, red soil, red soil, and yellow soil layers.

[0008] 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;

[0009] The cathodic protection module includes a potentiostat and an auxiliary anode ground bed. The potentiostat monitors the potential of the sample tube in real time through a reference electrode and automatically adjusts the output current by comparing it with a preset value. The auxiliary anode ground bed transmits the protective current to the surface of the sample tube through the anode to reduce the surface cathodic potential of the sample tube.

[0010] The multi-dimensional monitoring module includes an ER corrosion probe, an optical fiber current sensor, an electronic plate array, and a distributed humidity sensor. The monitoring data from the ER corrosion probe, the optical fiber current sensor, the electronic plate array, and the distributed humidity sensor are transmitted in real time through a wireless communication unit.

[0011] The intelligent protection module includes a solid-state decoupler and an adjustable drainage ground bed. The solid-state decoupler is installed at the connection point between the sample tube and the adjustable drainage ground bed.

[0012] The data analysis module is used to perform multi-dimensional data fusion on pipe-to-soil potential, corrosion rate, current distribution, and soil parameters.

[0013] The embodiments of the present invention have at least the following beneficial effects:

[0014] The buried pipeline multi-source stray current interference coupling test system provided by this invention includes 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 integrated system combines multi-source interference, full-size pipeline, intelligent protection, and real-time monitoring, integrating static DC, dynamic DC, and AC interference into a single system, thus solving the problem that existing technologies cannot realistically simulate the superposition of multi-source stray currents. The experimental pipeline module uses full-size pipelines and typical soil simulations, combined with typical soil environments, overcoming the limitations of small-scale laboratory models and improving the engineering reference value of experimental results, thus possessing high practicality. The stray current simulation module integrates static DC, dynamic DC, and AC interference sources, enabling realistic simulation of complex working conditions with multiple superimposed sources. The cathodic protection module's potentiostat monitors the potential of the sample tube in real time through a reference electrode and automatically adjusts the output current by comparing it with a preset value, assisting the anode ground bed in transferring the protective current to the surface of the sample tube through the anode to reduce the surface cathodic potential of the sample tube. The multi-dimensional real-time monitoring module can synchronously acquire data in real time. The intelligent protection module can dynamically adjust the drainage efficiency, which is superior to traditional offline methods. The data linkage analysis module realizes real-time acquisition and intelligent analysis of multiple parameters, providing a reliable basis for protection optimization under complex working conditions through high-precision data analysis. Through hardware integration and intelligent control, high-precision sensors and data linkage technology, the drainage equipment and intelligent algorithms are dynamically adjusted to achieve 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 improving the corrosion protection effect of buried pipelines.

[0015] According to some embodiments of the present invention, the sample tube includes at least one 90-degree bend and two 45-degree bends, and the length of the sample tube is ≥90 meters and the burial depth is 1.5-2.5 meters.

[0016] According to some embodiments of the present invention, an isolation permeable membrane with an ion permeability of <10 is provided between the lateritic soil layer and the red soil layer. -6 The thickness of the lateritic soil layer was 0.5-1.2 meters, and the thickness of the red soil layer was 0.8-1.5 meters, used to simulate the effect of seasonal wet-dry cycles on soil conductivity.

[0017] 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 <1%, the output voltage of the dynamic DC interference source is ±30V and the ripple coefficient is <5%, the output voltage of the AC interference source is 50V, the current density is >100A / m² and the adjustable frequency is 10-100Hz, the output waveform of the dynamic DC interference source is a square wave, a triangular 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.

[0018] According to 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 axial direction of the sample tube and an integrated temperature compensation unit, and the current measurement accuracy of the fiber optic current sensor is ≤0.2mA.

[0019] On the other hand, embodiments of the present invention provide a method for testing the multi-source stray current interference coupling of buried pipelines, including:

[0020] Excavate pipe trenches and foundation pits, and fill them with lateritic red soil, red soil, yellow soil and yellow soil in a layered structure. Lay an isolation and permeability membrane between the lateritic red soil layer and the red soil layer.

[0021] Pre-determine corrosion layer defects on the sample tube, install the sample tube, and embed a multi-dimensional monitoring module;

[0022] Perform single-device calibration to ensure that the ER probe accuracy verification error is ≤0.5% and the output fluctuation rate of the interference source is <1%;

[0023] Multi-source linkage test was conducted, and the amplitude and phase of static DC, dynamic DC and AC interference sources were adjusted synchronously to simulate multi-band coupling interference, so that the synchronization error was less than 3%.

[0024] Under single or coupled interference conditions, the intelligent protection module dynamically optimizes the drainage efficiency through a fuzzy PID algorithm, dynamically adjusts the protection potential through the cathodic protection module, and collects real-time data on pipe-to-ground potential, corrosion rate, current distribution, and soil temperature and humidity.

[0025] Wavelet transform algorithm is used to eliminate data noise, and neural network model is used to predict corrosion trend and evaluate protection effect.

[0026] According to some embodiments of the present invention, the dynamic adjustment of the protection potential via the cathodic protection module includes:

[0027] When a transient shift in the pipe-to-ground potential exceeding 50mV is detected, the intelligent protection module automatically switches to emergency mode.

[0028] The reverse compensation current is released through the adjustable drainage ground bed, and the potential is restored to the safe threshold within 5 seconds.

[0029] According to some embodiments of the present invention, the step of dynamically adjusting the protection potential through the cathodic protection module further includes:

[0030] A dynamic potential prediction method based on a convolutional neural network model is adopted, combined with real-time feedback data of multi-source interference, to adaptively adjust the protection potential.

[0031] According to some embodiments of the present invention, the intelligent protection module dynamically optimizes drainage efficiency through a fuzzy PID algorithm, including:

[0032] The control parameters of the fuzzy PID algorithm are dynamically adjusted based on real-time corrosion rate data.

[0033] The drainage efficiency was optimized to achieve a pipe-to-ground potential fluctuation range of ≤ ±20mV.

[0034] According to some embodiments of the present invention, the method of combining a neural network model to predict corrosion trends and evaluate the protective effect includes:

[0035] Training is conducted using historical data from pipeline corrosion tests. Input parameters include pipe-to-ground potential, soil resistivity, and interference source intensity. The output is a dynamic protection potential threshold with an error range of ≤±10mV.

[0036] The multi-source stray current interference coupling test method for buried pipelines according to embodiments of the present invention has at least the following beneficial effects:

[0037] The multi-source stray current interference coupling test system for buried pipelines is suitable for corrosion detection experiments on buried pipelines in actual outdoor soil under stray current interference, helping to deeply study the impact of stray currents on the cathodic protection system of buried pipelines. It employs 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, AC stray currents, and coupling interference from corrosion layer defects, reproducing current interference under complex operating conditions and allowing for in-depth research on the impact of different stray current superpositions on pipeline corrosion. Integrating high-precision monitoring equipment and intelligent protection modules, it achieves online monitoring of pipe-to-ground potential, current distribution, and corrosion rate, thereby improving the timeliness and accuracy of data, providing strong evidence for optimizing protection strategies, and enabling collaborative work and data linkage analysis of multiple modules, providing a reliable experimental platform for verifying pipeline corrosion protection technologies.

[0038] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0039] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0040] Figure 1 This is a block diagram of the buried pipeline multi-source stray current interference coupling test system according to an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the sample tube pre-set defects and the soil distribution of the simulated plot in the buried pipeline multi-source stray current interference coupling test system of this invention;

[0042] Figure 3A sample pipe material diagram of the buried pipeline multi-source stray current interference coupling test system according to an embodiment of the present invention;

[0043] Figure 4 This is a list of pre-defined defects in the sample tubes of the buried pipeline multi-source stray current interference coupling test system according to an embodiment of the present invention.

[0044] Figure 5 This is a flowchart of the multi-source stray current interference coupling test method for buried pipelines according to an embodiment of the present invention;

[0045] Figure 6 This is a schematic diagram illustrating the influence of DC input on AC input in the multi-source stray current interference coupling test method for buried pipelines according to an embodiment of the present invention.

[0046] Figure 7 This is a schematic diagram illustrating the effect of AC input on DC in the multi-source stray current interference coupling test method for buried pipelines according to an embodiment of the present invention.

[0047] Figure 8 The diagram shows the de-energized potential of the cathodic protection module in the test method for multi-source stray current interference coupling of buried pipelines according to an embodiment of the present invention. Detailed Implementation

[0048] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0049] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0050] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the stated number, and "above," "below," "within," etc. are understood to include the stated number. If "first," "second," etc. are used in the description, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of the indicated technical features.

[0051] In the description of this invention, unless otherwise explicitly defined, the terms "setting", "installing", "connecting" and "linking" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0052] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Please refer to Figures 1 to 4 This 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 ground plot. The sample pipe has pre-set corrosion layer defects, including corrosion thinning zones, artificial damage zones, and coating peeling zones. The sample pipe is buried in the simulated ground plot, which includes lateritic soil, red soil, red soil, and yellow soil layers. The stray current simulation module includes static DC interference sources, dynamic DC interference sources, and AC interference sources, which are used to simulate superimposed current interference. The cathodic protection module includes a potentiostat and an auxiliary anode bed. The potentiostat 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 protective current to the surface of the sample pipe through the anode to reduce the surface cathodic potential of the sample pipe. The multi-dimensional monitoring module includes an ER corrosion probe, a fiber optic current sensor, an electronic plate array, and a distributed humidity sensor. Monitoring data from these components are 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 tube and the adjustable drainage bed. The data analysis module performs multi-dimensional data fusion on pipe-to-soil potential, corrosion rate, current distribution, and soil parameters.

[0054] This buried pipeline multi-source stray current interference coupling test system integrates multi-source interference, full-size pipeline, intelligent protection, and real-time monitoring into a comprehensive system. It integrates static DC, dynamic DC, and AC interference into a single system, solving the problem that existing technologies cannot realistically simulate the superposition of multi-source stray currents. The test pipeline module uses a full-size pipeline and typical soil simulation, combined with typical soil environments, overcoming the limitations of small-scale laboratory models and improving the engineering reference value of experimental results, thus possessing high practicality. The stray current simulation module integrates static DC, dynamic DC, and AC interference sources, enabling realistic simulation of complex working conditions involving multi-source superposition. The cathodic protection module's potentiostat monitors the potential of the sample tube in real time through a reference electrode and automatically adjusts the output current by comparing it with a preset value. This assists the anode bed in transferring the protective current to the surface of the sample tube through the anode, thereby reducing the surface cathodic potential of the sample tube. The multi-dimensional real-time monitoring module can synchronously acquire data in real time. The intelligent protection module can dynamically adjust drainage efficiency, superior to traditional offline methods. The data linkage analysis module achieves real-time acquisition and intelligent analysis of multiple parameters, providing a reliable basis for protection optimization under complex working conditions through high-precision data analysis. By integrating hardware and intelligent control, using high-precision sensors and data linkage technology, and dynamically adjusting drainage equipment and intelligent algorithms, online monitoring of pipe-to-ground potential, current distribution and corrosion rate can be achieved, improving the timeliness and accuracy of test data, providing a strong basis for optimizing protection strategies and improving the corrosion protection effect of buried pipelines.

[0055] Please see Figure 2 and Figure 3 The sample tube shall include at least one 90-degree bend and two 45-degree bends, and the length of the sample tube shall be ≥90 meters and the burial depth shall be 1.5-2.5 meters.

[0056] Please see Figure 2 An insulating permeable membrane is installed between the lateritic red soil layer and the red soil layer, with an ion permeability of <10. -6 The thickness of the lateritic soil layer was 0.5-1.2 meters, and the thickness of the red soil layer was 0.8-1.5 meters, used to simulate the effect of seasonal wet-dry cycles on soil conductivity.

[0057] In some embodiments of the present invention, the output current of the static DC interference source is 1000-3000A and the fluctuation rate is <1%, the output voltage of the dynamic DC interference source is ±30V and the ripple coefficient is <5%, the output voltage of the AC interference source is 50V, the current density is >100A / m² and the adjustable frequency is 10-100Hz, the output waveform of the dynamic DC interference source is a square wave, a triangular 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.

[0058] 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 sample tube axis and an integrated temperature compensation unit. The current measurement accuracy of the fiber optic current sensor is ≤0.2mA.

[0059] Please see Figure 5 This embodiment also provides a method for conducting tests based on the above-mentioned buried pipeline multi-source stray current interference coupling test system, mainly including steps S101~S106:

[0060] S101. Excavate pipe trenches and foundation pits, and fill them with lateritic red soil, red soil, yellow soil and yellow soil in a layered structure. Lay an isolation permeable membrane between the lateritic red soil layer and the red soil layer.

[0061] S102. Pre-determine the anti-corrosion layer defects on the sample tube, install the sample tube, and embed a multi-dimensional monitoring module.

[0062] S103. Perform single-device calibration to ensure that the ER probe accuracy verification error is ≤0.5% and the output fluctuation rate of the interference source is <1%.

[0063] S104. Conduct multi-source linkage test, synchronously adjust the amplitude and phase of static DC, dynamic DC and AC interference sources, simulate multi-band coupling interference, so that the synchronization error is <3%.

[0064] S105. Under single or coupled interference conditions, 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 data on pipe-to-ground potential, corrosion rate, current distribution, and soil temperature and humidity in real time.

[0065] S106. Wavelet transform algorithm is used to eliminate data noise, combined with neural network model to predict corrosion trend, evaluate protection effect, and generate multi-dimensional protection strategy report.

[0066] The dynamic adjustment of the protection potential via the cathodic protection module in step S105 above includes:

[0067] When a transient shift in the pipe-to-ground potential exceeding 50mV is detected, the intelligent protection module automatically switches to emergency mode.

[0068] The reverse compensation current is released through the adjustable drainage ground bed, and the potential is restored to the safe threshold within 5 seconds.

[0069] The above-mentioned step S105, which involves dynamically adjusting the protection potential via the cathodic protection module, further includes:

[0070] A dynamic potential prediction method based on a convolutional neural network model is adopted, combined with real-time feedback data of multi-source interference, to adaptively adjust the protection potential.

[0071] Based on the potential shift 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 a PID algorithm.

[0072] Among them, a potential dynamic prediction method based on a convolutional neural network model is adopted. Convolutional neural networks (CNNs) are good at processing spatially correlated data and are suitable for extracting spatial features of pipeline potential distribution. The model complexity is reduced and the real-time performance is improved by local perception and weight sharing.

[0073] (1) Input data and output data

[0074] Input data:

[0075] Pipe-to-ground potential distribution (collection points every 0.5 meters along the pipeline axis);

[0076] Multi-source interference parameters (static DC current, dynamic DC waveform / frequency, AC voltage / frequency);

[0077] Environmental parameters (soil resistivity, temperature and humidity, location and size of defects in the anti-corrosion layer).

[0078] Output data:

[0079] Predicted pipe-to-ground potential (time series) within the next 5 seconds;

[0080] Locating high-corrosion-risk areas (probability heatmap).

[0081] (2) Model training and data preparation

[0082] Dataset Construction:

[0083] Historical experimental data: including records of potential, current, and corrosion rate under different interference conditions;

[0084] Field measured data: Multi-source interference and potential response data collected from actual pipeline operation and maintenance;

[0085] Synthetic data: Extreme working conditions (such as multi-band interference superposition) are simulated through finite element simulation.

[0086] (3) Training process

[0087] Data preprocessing: normalization, time series alignment, noise filtering (wavelet transform);

[0088] Network structure: It adopts 3 convolutional layers (extracting spatial features) + LSTM layer (capturing temporal dependencies) + fully connected layer (outputting predicted values);

[0089] Loss function: Mean squared error (MSE) combined with corrosion risk weighting factor, prioritizing the optimization of prediction accuracy for highly corroded areas.

[0090] The integration of real-time feedback data from multi-source interference includes:

[0091] (1) Data source and acquisition mechanism

[0092] Interference source parameters:

[0093] Static DC: Current value (1000-3000A), fluctuation rate;

[0094] Dynamic DC: Waveform type (square wave / triangle wave / sine wave), amplitude (±30V), frequency (0.1-10Hz);

[0095] AC interference: voltage (50V), frequency (10-100Hz), phase difference (relative to dynamic DC).

[0096] Data collection frequency:

[0097] High-frequency sampling: tube-to-ground potential (100Hz), current density (50Hz);

[0098] Low-frequency updates: soil parameters (1Hz), interference source configuration (event triggered).

[0099] (2) Data fusion and input processing

[0100] Feature engineering:

[0101] Spatial encoding: Maps the axial position of the pipe to a two-dimensional grid, and fills the potential value with pixel intensity;

[0102] Time window sliding: Construct a temporal-spatial joint input matrix with a window length of 5 seconds and a step size of 1 second.

[0103] Real-time feedback mechanism:

[0104] Data buffer: Caches data from the last 10 seconds to ensure continuous model input;

[0105] Anomaly detection: When the output fluctuation of the interference source exceeds the threshold (e.g., static DC fluctuation rate > 1%), model recalibration is triggered.

[0106] The intelligent protection module in step S105 above dynamically optimizes drainage efficiency using a fuzzy PID algorithm, including:

[0107] The control parameters of the fuzzy PID algorithm are dynamically adjusted based on real-time corrosion rate data.

[0108] The drainage efficiency was optimized to achieve a pipe-to-ground potential fluctuation range of ≤ ±20mV.

[0109] The step S106 above, which combines a neural network model to predict corrosion trends and evaluate the protective effect, includes:

[0110] Training is conducted using historical data from pipeline corrosion tests. Input parameters include pipe-to-ground potential, soil resistivity, and interference source intensity. The output is a dynamic protection potential threshold with an error range of ≤±10mV.

[0111] The neural network corrosion trend prediction model includes:

[0112] (1) Multimodal input data fusion, the input data includes current / potential spatial distribution (180 measuring points), ER corrosion rate matrix, soil parameters (resistivity / pH / temperature, etc.).

[0113] (2) A hybrid neural network architecture is adopted, and the core modules include:

[0114] The spatial transformer takes a pipe potential / current distribution grid (18×10 matrix) as input and outputs a spatial feature vector (128-dimensional).

[0115] 1D-CNN erosion feature extraction: 3 convolutional layers (kernel=5,3,3) → max pooling → fully connected;

[0116] Temporal environment modeling, Bi-LSTM units (64 hidden layers) capture long-term dependencies.

[0117] (3) Multi-task learning output, the output items include instantaneous corrosion rate, high-risk area and remaining lifetime.

[0118] (4) Training strategies

[0119] Transfer learning: The pre-trained model is based on 100,000 sets of accelerated corrosion data from the laboratory;

[0120] Online learning: Model parameters are updated incrementally every 24 hours.

[0121] The detailed steps of the multi-source stray current interference coupling test method for buried pipelines in this embodiment are as follows:

[0122] 1. Earthwork construction

[0123] Precise measurements and layout are conducted based on the design drawings. Pipe trenches, anode laying pits, and test pile pits are excavated using manual excavation or mechanical equipment. The trench excavation depth is 1.5-2.5 meters, and the width is determined according to the sample pipe specifications to ensure compliance with pipeline laying and subsequent maintenance requirements. The sample pipes are full-size pipes from DN200 to DN1200, with a length ≥90 meters. The simulated site is backfilled with typical regional soil layers, including lateritic red soil, red soil, and yellow soil, with each layer at least 0.5 meters thick to simulate the differences in electrochemical characteristics of the actual buried environment.

[0124] Please see Figure 2 and Figure 3The sample pipe uses 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 pipe contains 6 straight pipes with a diameter of φ914×17.5×12000mm, 1 90-degree elbow, and 2 45-degree elbows. The material is API 5L X70.

[0125] 2. Equipment installation

[0126] (1) Indoor equipment: Assemble an ultra-high voltage DC grounding electrode discharge simulation device, an AC transmission line simulation device and a subway stray current interference simulation device, connect a programmable power supply, DC power supply accuracy ±1%, AC power supply harmonic distortion rate <3%, and complete electrical circuit verification.

[0127] (2) Outdoor equipment: Please refer to Figure 2 and Figure 4 The pre-defect sample pipes are laid smoothly in the pipe trench. The defect types include corrosion thinning and damage to the anti-corrosion layer, and at least two points are set for each type of defect. Intelligent test piles (spacing ≤ 30 meters), ER corrosion probes and electronic hangers are installed simultaneously to ensure that the monitoring points cover the entire pipe section.

[0128] 3. Line connection

[0129] A copper core cable with a cross-sectional area ≥16mm² is used to connect the anode ground bed and the cathodic protection module, with a grounding resistance ≤1Ω. The test pile and the in-pipe current monitoring device are connected via shielded twisted-pair cable to avoid electromagnetic interference. A fiber optic communication network is deployed to enable real-time transmission of monitoring data to the data center.

[0130] 4. System debugging and verification

[0131] (1) Single device commissioning

[0132] After the equipment installation was completed, the functions of each device were tested one by one. For the stray current loading simulation system, the ultra-high voltage DC grounding electrode discharge simulation device, the AC transmission line simulation device, and the subway stray current interference simulation device were debugged separately to check whether their output static DC current, AC current, and dynamic DC voltage met the set parameters, and to verify the accuracy and stability of the simulated current and voltage. During the debugging of the tube current monitoring, a standard current source was used to calibrate the tube current monitoring device to ensure that the resolution reached 1mA / 10μV and the measurement error was ≤1%.

[0133] Stray current simulation devices: 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 output ±30V dynamic DC, ripple coefficient <5%.

[0134] Monitoring equipment calibration: The in-tube current monitoring device is calibrated using a standard current source to ensure a resolution of 1mA / 10μV and a linearity error of ≤1%;

[0135] The ER corrosion probe and electronic pad were calibrated using standard corrosion test pieces. The ER corrosion probe has a resolution of 0.001 μm and a repeatability error of <2%.

[0136] (2) Linkage debugging

[0137] After individual devices are debugged, integrated debugging is carried out. The stability of the system is tested when DC and AC interferences are superimposed. By adjusting the output parameters of each simulation device, the operating status of each part of the system is observed to ensure that the data synchronization error is less than 5%. The focus is on studying the effects of DC to AC, AC to DC, and both changing simultaneously on parameters such as pipeline corrosion and cathodic protection potential.

[0138] Multi-source interference superposition test: static DC (2000A), dynamic DC (+20V) and AC (50V) interference are applied sequentially, and the tube-to-ground potential synchronization is monitored, for example, time deviation <1ms and amplitude error <5%.

[0139] Intelligent system response test: When the pipe ground potential deviates from the set value (-1.2V CSE) ±50mV, the cathode protection module completes the adjustment within 5 seconds; the intelligent solid-state decoupler switches the drainage mode within 0.2 seconds, and the drainage current dynamic range is 0~50A.

[0140] Test system stability when DC and AC interferences are superimposed, ensuring data synchronization error is <5%. Debugging includes: the impact of DC on AC, the impact of AC on DC, and simultaneous changes in DC and AC.

[0141] Please see Figure 6 By fixing the AC input and changing the DC input, the effect of DC output on AC was tested. The AC voltage was set to a fixed output of 10.5V, and the DC current was increased sequentially from 10.5V, 15.5V, 20.5V, 25.5V, and 30.5V. The AC and DC voltage outputs were measured sequentially at the test point using a multimeter. 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. Based on the test data, it is evident that changing the DC input has almost no effect on the AC.

[0142] Please see Figure 7By fixing the DC input and changing the AC input, the effect of AC output on DC was tested. The DC voltage was set to a fixed output of 10.5V, and the AC current was increased sequentially from 15.5V, 20.5V, 25.5V, 30.5V, and 35.5V. The AC and DC voltage outputs were measured sequentially at the test point using a multimeter. 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. Based on the test data, it is evident that changing the AC input interferes with both the DC and AC outputs to some extent.

[0143] Please see Figure 8 The cathodic protection system provides cathodic protection to pipelines by externally applying a controlled current. Different output settings can be used to test the required output potential for the pipeline to reach its minimum protection potential. If the output voltage is 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, to ensure the pipeline's off-state potential meets -850mVcse, the potentiostat of the cathodic protection system needs to output at least 5V.

[0144] 5. Experimental Testing and Data Analysis

[0145] (1) Operating conditions

[0146] Based on actual research needs, different operating conditions are flexibly set. The parameters of the multi-source stray current interference coupling simulation system are adjusted to simulate static DC, dynamic DC, and AC stray current interferences of different intensities and frequencies. Combining the prefabricated pipe body and anti-corrosion layer defects in the test pipeline module, the impact of stray current interference on pipeline corrosion under different defect types and severity is studied. For example, sample pipe locations with typical defects such as corrosion thinning and anti-corrosion layer damage are selected, and stray current interference under different operating conditions is applied to observe changes in parameters such as pipe-to-ground potential and corrosion rate.

[0147] Single interference condition: Static DC (1500A), dynamic DC (±15V) or AC (30V) interference were applied for 24 hours respectively, and the corrosion rate and potential distribution were recorded.

[0148] Coupled interference condition: Simultaneously apply static DC (2000A) + dynamic DC (±25V) + AC (40V) to simulate an extreme stray current environment.

[0149] (2) Data acquisition and processing

[0150] During the experimental testing, a multi-dimensional monitoring module was used to collect various data in real time. The collected data was processed by a 24-bit high-precision AD converter and time-synchronized signal processing technology before being transmitted to the data analysis module for analysis. Statistical analysis was performed on the data, variation curves were plotted, the interrelationships between various parameters were studied, and the impact of stray current interference on pipeline corrosion and cathodic protection systems was summarized.

[0151] Parameters such as pipe-to-soil potential, corrosion current, and soil resistivity are collected through a multi-dimensional monitoring module, with a sampling frequency ≥1Hz. After 24-bit AD conversion, wavelet transform is used to eliminate noise, and multi-source data synchronous analysis is achieved through timestamp alignment.

[0152] (3) Performance verification

[0153] Protection effectiveness assessment: Compared with the case where the intelligent protection module is not enabled, the pipe-to-ground potential fluctuation range is reduced from ±300mV to ±50mV.

[0154] Corrosion inhibition rate calculation: According to ER probe data, the corrosion rate under dynamic DC interference decreased from 0.25 mm / a to 0.05 mm / a, with an inhibition rate of 80%.

[0155] 6. System maintenance and optimization

[0156] A multi-dimensional monitoring module is used to monitor the equipment's operating status in all aspects in real time. In addition to collecting cathodic protection data, corrosion data, and stray current interference data, it also monitors the operating parameters of various key equipment. For example, it monitors the power output stability and equipment temperature of the ultra-high voltage DC grounding electrode discharge simulation device, AC transmission line simulation device, and subway stray current interference simulation device; it monitors the operating current and voltage of the cathodic protection module, as well as the communication status of each intelligent terminal; and it monitors the operating status and drainage current changes of the intelligent solid-state decoupler and adjustable drainage ground bed in the intelligent protection module.

[0157] A device operation status assessment model is established to evaluate the device's operating status in real time based on collected data. Reasonable thresholds are set, and the system automatically issues an early warning signal when device operating parameters exceed these thresholds. For example, if the operating current of the cathodic protection module increases or decreases abnormally, it may indicate a problem with the cathodic protection effect; the system will immediately issue an alarm to prompt personnel to check and handle the issue promptly. Through continuous monitoring and evaluation of the device's operating status, potential faults can be identified in advance, ensuring the stable operation of the testing system.

[0158] Monthly checks on the insulation performance of the intelligent solid-state decoupler, with an insulation resistance ≥10MΩ; quarterly calibration of monitoring equipment to ensure data accuracy; training of an AI model (neural network model) based on historical data to optimize the cathodic protection potential setting.

[0159] The multi-source stray current interference coupling test system for buried pipelines is suitable for corrosion detection experiments on buried pipelines in actual outdoor soil under stray current interference, helping to deeply study the impact of stray currents on the cathodic protection system of buried pipelines. It employs 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, AC stray currents, and coupling interference from corrosion layer defects, reproducing current interference under complex operating conditions and allowing for in-depth research on the impact of different stray current superpositions on pipeline corrosion. Integrating high-precision monitoring equipment and intelligent protection modules, it achieves online monitoring of pipe-to-ground potential, current distribution, and corrosion rate, thereby improving the timeliness and accuracy of data, providing strong evidence for optimizing protection strategies, and enabling collaborative work and data linkage analysis of multiple modules, providing a reliable experimental platform for verifying pipeline corrosion protection technologies.

[0160] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made 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, The buried pipeline multi-source stray current interference coupling test system comprises 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 comprises a sample pipe and a simulated land mass, the sample pipe is provided with a corrosion protection layer defect, the corrosion protection layer defect comprises a corrosion thinning area, an artificial damage area and a coating peeling area, the sample pipe is buried in the simulated land mass, and the simulated land mass comprises a lateritic soil layer, an acric soil layer, a red soil layer and a yellow soil layer. The stray current simulation module comprises a static direct current interference source, a dynamic direct current interference source and an alternating current interference source, the static direct current interference source, the dynamic direct current interference source and the alternating current interference source are used for simulating superimposed current interference, the output current of the static direct current interference source is 1000-3000 A and the fluctuation rate is less than 1%, the output voltage of the dynamic direct current interference source is ±30 V and the ripple coefficient is less than 5%, the output voltage of the alternating current interference source is 50 V, the current density is greater than 100 A / m², and the adjustable frequency is 10-100 Hz, the output waveform of the dynamic direct current interference source is a square wave, a triangular wave or a sine wave, the switching frequency is 0.1-10 Hz, and the phase difference with the alternating current interference source can be adjusted in real time. The cathodic protection module comprises a constant potential instrument and an auxiliary anode bed, the constant potential instrument monitors the potential of the sample pipe in real time through a reference electrode, and automatically adjusts the output current compared with a preset value, and the auxiliary anode bed transmits the protection current to the surface of the sample pipe through the anode to reduce the cathode potential of the surface of the sample pipe. The multi-dimensional monitoring module comprises an ER corrosion probe, an optical fiber current sensor, an electronic coupon array and a distributed humidity sensor, and the monitoring data of the ER corrosion probe, the optical fiber current sensor, the electronic coupon array and the distributed humidity sensor is transmitted in real time through a wireless communication unit. The intelligent protection module comprises a solid-state decoupler and an adjustable drainage bed, and the solid-state decoupler is installed at the connection point of the sample pipe and the adjustable drainage bed. The data analysis module is used for multi-dimensional data fusion of pipe ground potential, corrosion rate, current distribution and soil parameters, adopts a wavelet transform algorithm to eliminate data noise, combines a neural network model to predict a corrosion trend, and outputs a dynamic protection potential threshold.

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

3. The buried pipeline multi-source stray current interference coupling test system according to claim 2, characterized in that, The separation permeable membrane is arranged between the lateritic layer and the latosolic layer, and the ion permeation rate is <10 -6 cm / s, the thickness of the lateritic layer is 0.5-1.2 meters, and the thickness of the latosolic layer is 0.8-1.5 meters, which is used for simulating the influence of seasonal wet-dry alternation on soil conductivity.

4. The buried pipeline multi-source stray current interference coupling test system according to claim 1, characterized in that, The optical fiber current sensor is a distributed optical fiber grating array, one monitoring node is arranged every 0.5 meters along the axial direction of the sample pipe, and a temperature compensation unit is integrated, and the current measurement accuracy of the optical fiber current sensor is less than or equal to 0.2 mA.

5. A method for testing multi-source interference coupling of a buried pipeline, characterized in that, The buried pipeline multi-source stray current interference coupling test system comprises: Excavate a pipeline trench and a foundation pit, fill lateritic soil, acric soil, red soil and yellow soil according to a layered structure, and lay a separation permeation film between the lateritic soil layer and the acric soil layer; Pre-set a corrosion protection layer defect on the sample pipe, install the sample pipe, and bury the multi-dimensional monitoring module; The buried pipeline multi-source stray current interference coupling test system comprises: Single device calibration is performed to make the ER probe accuracy verification error ≤0.5% and the interference source output fluctuation rate <1%; Multi-source linkage test is performed, the amplitudes and phases of the static DC interference source, the dynamic DC interference source and the AC interference source are synchronously adjusted, multi-frequency band coupling interference is simulated, and the synchronization error is <3%, the output current of the static DC interference source is 1000-3000A and the fluctuation rate is <1%, the output voltage of the dynamic DC interference source is ±30V and the ripple coefficient is <5%, the output voltage of the AC interference source is 50V, the current density is >100A / m², and the adjustable frequency is 10-100Hz, the output waveform of the dynamic DC interference source is square wave, triangular wave or sine wave, the switching frequency is 0.1-10Hz, and the phase difference with the AC interference source can be adjusted in real time; Single or coupled interference working conditions are set, 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 the pipe ground potential, corrosion rate, current distribution and soil temperature and humidity data in real time; Wavelet transform algorithm is used to eliminate data noise, neural network model is combined to predict corrosion trend, protection effect is evaluated, and dynamic protection potential threshold is output.

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

7. The method according to claim 6, wherein The dynamic adjustment of the protection potential by the cathodic protection module further comprises: A potential dynamic prediction method based on a convolutional neural network model is used, combined with real-time feedback data of multiple sources, to perform adaptive adjustment of the protection potential.

8. The buried pipeline multi-source stray current interference coupling test method according to claim 5, characterized in that, The intelligent protection module dynamically optimizes the drainage efficiency through the fuzzy PID algorithm, comprising: The control parameters of the fuzzy PID algorithm are dynamically adjusted through real-time corrosion rate data; The drainage efficiency is optimized to make the pipe ground potential fluctuation range ≤±20mV.

9. The buried pipeline multi-source stray current interference coupling test method according to claim 5, characterized in that, The neural network model is combined to predict the corrosion trend and evaluate the protection effect, comprising: Through training of historical data of pipeline corrosion test, the input parameters include pipe ground potential, soil resistivity and interference source strength, and the output is dynamic protection potential threshold, with an error range of ≤±10mV.

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