Methods, systems, electronic equipment, and media for monitoring and assessing the degree of corrosion in pipelines.

Abstract

This invention discloses a method, system, electronic equipment, and medium for monitoring and evaluating the degree of corrosion in pipelines. It relates to the technical field of monitoring and evaluating the degree of pipeline corrosion, particularly the technical field of monitoring and evaluating the impact of ultra-high voltage direct current (UHVDC) transmission systems on the corrosion of pipeline outer walls. This invention addresses the problem in existing technologies that cannot monitor the thinning of affected pipeline walls throughout their entire lifecycle, thus hindering the evaluation of the degree of pipeline outer wall corrosion and the effectiveness of drainage facilities. The invention includes: conducting pipe-to-ground potential detection along the entire pipeline; determining the distribution of cathodic and anodic zones along the entire pipeline; identifying the section of the pipeline most severely affected by external corrosion; calculating the outflowing current density; calculating the annual corrosion rate of the pipe wall; and evaluating the degree of influence of DC stray current on the pipeline. Based on the annual corrosion rate of the pipe wall, this invention can quantify the impact of UHVDC stray current on the pipeline, thereby simultaneously achieving the evaluation of the degree of pipeline outer wall corrosion and the effectiveness of drainage facilities.

Description

Technical Field

[0001] This invention relates to the field of monitoring and assessment technology for the degree of corrosion of pipelines, particularly to the field of monitoring and assessment technology for the impact of ultra-high voltage direct current transmission systems on the corrosion of pipeline outer walls, and more specifically to methods, systems, electronic equipment and media for monitoring and assessment of the degree of corrosion of pipelines. Background Technology

[0002] Pipeline external wall corrosion is one of the common leading risk factors for pipelines. For a long time, pipeline cathodic protection systems have been an important means to avoid pipeline external corrosion failure. Conducting effectiveness tests on pipeline cathodic protection systems and timely monitoring whether pipelines are in an effective protection state are important aspects of pipeline corrosion protection work. With the continuous increase in construction, the impact of ultra-high voltage power transmission systems on buried steel gas pipelines is becoming increasingly serious. Under normal operating conditions, ultra-high voltage power transmission systems use two power lines to achieve bipolar operation. When a fault occurs or the line is under maintenance, it uses the ground as a conductor and operates in a single-stage manner. A huge current flows into the soil through the grounding electrode. If there is a buried steel pipeline near the grounding electrode, some of the current may enter the pipeline through the damage point of the pipeline anti-corrosion layer. After flowing forward along the pipeline for a certain distance, it flows out of the pipeline from the damage point of the pipeline anti-corrosion layer, causing severe external corrosion at the current outflow location. The discharge of the grounding electrode of ultra-high voltage DC transmission has four major characteristics: "unpredictable occurrence time, large single discharge amount, short single duration, and many occurrences per year".

[0003] Currently, there are two main methods for monitoring the impact of stray currents in ultra-high voltage direct current (UHVDC): potential monitoring and test piece current density monitoring. According to current national standards, the potential monitoring method evaluates the impact of stray currents based on the fluctuation range of the pipe-to-ground potential; the more severe the fluctuation, the greater the impact. This method is a relative evaluation method, suitable for qualitative comparisons, but it cannot quantify the specific impact. The test piece current density monitoring method connects a metal test piece to the pipe wall at a fixed location (usually a pipe test stake) and monitors the outflow current density of the test piece. The test piece current density is considered to characterize the outflow current density of the pipe. This method can quantify the impact of stray currents, but it has limitations: first, due to the limited number of test piece connection points, this method can only test the current density at individual points within the entire pipe section; second, the test piece connection point is generally at the pipe potential test stake, which is often also the installation location of drainage facilities. This location is actually the best protected location in the entire pipe section; therefore, it is difficult to use the monitoring results at this point to characterize the most severe corrosion level of the entire pipe section.

[0004] In summary, existing monitoring methods for the impact of stray currents in UHVDC transmission have several drawbacks. They cannot monitor the reduction in pipe wall thickness throughout the entire process, thus failing to assess whether the corrosion level of pipes severely affected by UHVDC transmission is within acceptable limits, and also failing to assess whether the existing stray current drainage facilities for pipes severely affected by UHVDC transmission have met technical requirements. Summary of the Invention

[0005] The purpose of this invention is to address the problems in existing methods for monitoring and evaluating the impact of stray currents in ultra-high voltage direct current (UHVDC) transmission. These methods cannot monitor the thinning of the affected pipeline wall throughout its entire lifecycle, thus failing to assess whether the corrosion level of the pipeline's outer wall, severely affected by UHVDC transmission, is within acceptable limits, and also failing to evaluate whether the existing stray current drainage facilities for pipelines severely affected by UHVDC transmission have met technical requirements. This invention provides a method, system, electronic equipment, and medium for monitoring and evaluating the degree of pipeline corrosion, enabling the evaluation of the degree of corrosion on the pipeline's outer wall and the effectiveness of drainage facilities.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0007] Firstly, a method for monitoring and assessing the degree of corrosion in pipelines includes the following steps:

[0008] S1: Conduct pipe-to-ground potential detection along the entire pipeline to determine the changes in pipe-to-ground potential along the entire pipeline;

[0009] During the pipeline-to-ground potential detection, pipeline-to-ground potential data monitoring instruments are installed at test piles along the entire pipeline to monitor the changes in pipeline-to-ground potential during single-stage operation of the UHVDC transmission system.

[0010] S2: Determine the distribution of the cathode and anode areas along the entire pipeline based on the changes in pipeline-to-ground potential;

[0011] In determining the distribution of cathode and anode regions along the entire pipeline, the pipe-to-ground potential at all points is divided into negative and positive offsets. Pipe sections with negative offsets are cathode regions, and those with positive offsets are anode regions.

[0012] S3: Determine the section of the pipeline most severely affected by external corrosion based on the distribution of the cathode and anode regions;

[0013] In identifying the most severely affected section of the pipeline due to external corrosion, the cathode region is the section where stray DC current flows in, and the anode region is the section where stray DC current flows out. The section where stray DC current flows out is the area where the pipeline is severely corroded. The greater the positive offset of the pipe-to-ground potential, the greater the outflow current density and the faster the pipeline corrosion rate. This section is the most severely affected section of the pipeline due to external corrosion.

[0014] S4: Calculate the current density flowing out of the section most severely affected by external corrosion of the pipeline;

[0015] The calculation of the outflowing current density includes the following steps:

[0016] S41: Determine the total damaged area of ​​the anti-corrosion layer in the target section;

[0017] Determining the total damaged area of ​​the anti-corrosion coating in the target section includes the following steps:

[0018] For the most severely corroded pipe section, the AC potential gradient method was used to locate the damage points of the anti-corrosion coating throughout the entire pipe section;

[0019] A random inspection of some anti-corrosion coating damage points was conducted, and pipeline excavation was carried out. The average area of ​​anti-corrosion coating damage at all excavation points was determined as the typical value of the anti-corrosion coating damage area for that pipe section. The total anti-corrosion coating damage area S of the pipe section was obtained by producting the typical value with the number of damage points. 破损 .

[0020] S42: Calculate the total current flowing out from the point of damage to the anti-corrosion coating;

[0021] Calculate the total current flowing out from the point of corrosion protection failure, and record the current magnitude at monitoring point A as I. A The current at monitoring point B is I. B ;

[0022] If the current directions at monitoring points A and B are opposite, then the total current I flowing out from the point of corrosion damage will be... 总 For: I 总 =I A +I B ;

[0023] If the current directions at monitoring points A and B are in the same direction, then the total current I flowing out from the point of corrosion damage will be... 总 For: I 总 =I A -I B ;

[0024] The current I of all existing drainage facilities within the pipe section 排 Perform synchronous monitoring;

[0025] The outflow current density i in the most severely corroded section 流出 for:

[0026] i 流出 =(I 总 -I 排 ) / S 破损 .

[0027] S5: Calculate the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion based on current density;

[0028] In calculating the annual corrosion rate of the pipe wall, according to Faraday's law, the relationship between metal loss mass and current density is as follows:

[0029] W = KIT, where W is the mass of metal lost (kg); K is the electrochemical equivalent; I is the current (A); and T is the time.

[0030] Transforming the above formula, we get: c 腐蚀 =Ki 流出 T / ρ

[0031] Among them, c 腐蚀 The unit of measurement is: T = wall thinning during a single discharge, in mm; T = duration of a single discharge, in min; i = current density, in A / mm². 2 ρ represents the density of the pipe material, in kg / mm³. 3 ;

[0032] The annual pipe wall thinning amount for each discharge throughout the year is recorded and summed to obtain the annual pipe wall corrosion rate C. 腐蚀 .

[0033] S6: Evaluate the degree of influence of DC stray current on the pipeline based on the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion.

[0034] Secondly, a monitoring and assessment system for the degree of corrosion of pipelines includes:

[0035] The detection module is used to detect the pipe-to-ground potential along the entire pipeline and determine the changes in pipe-to-ground potential along the entire pipeline.

[0036] The cathode and anode distribution determination module is used to determine the distribution of cathode and anode regions along the entire pipeline based on changes in pipeline-to-ground potential.

[0037] The module for determining the most severely affected corrosion section is used to identify the most severely affected external corrosion section of the pipeline based on the distribution of the cathodic and anodic regions.

[0038] The current density calculation module is used to calculate the current density flowing out of the section of the pipe most severely affected by external corrosion.

[0039] The annual corrosion rate calculation module is used to calculate the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion based on the current density.

[0040] The evaluation module is used to evaluate the degree of influence of DC stray current on the pipeline based on the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion.

[0041] Thirdly, an electronic device includes a storage device and one or more processors;

[0042] Storage device for storing one or more programs;

[0043] When one or more programs are executed by one or more processors, the one or more processors implement the method for monitoring and evaluating the degree of corrosion of pipelines as described in the embodiments.

[0044] Fourthly, a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for monitoring and evaluating the degree of corrosion of a pipeline as described in the embodiments.

[0045] The beneficial effects of this invention are as follows:

[0046] By performing potential detection on the pipeline, the distribution of cathode and anodic regions of the pipeline can be determined based on the detected potential. The section of the pipeline most severely affected by corrosion can then be identified based on the distribution of cathode and anodic regions. The current density of the section most severely affected by corrosion can then be calculated, and the annual corrosion rate of the pipe wall can be calculated based on the current density. Based on the annual corrosion rate of the pipe wall, the degree of influence of UHVDC stray current on the pipeline can be quantified. Thus, it is possible to simultaneously evaluate the degree of corrosion on the outer wall of the pipeline and the effectiveness of the drainage facilities. Attached Figure Description

[0047] Figure 1 This is a flowchart of the pipeline corrosion monitoring and evaluation method of the present invention;

[0048] Figure 2 This is a framework diagram of the pipeline corrosion monitoring and evaluation system of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0050] Example 1

[0051] like Figure 1 As shown in the figure, this embodiment provides a method for monitoring and evaluating the degree of corrosion of pipelines, including the following steps:

[0052] S1: Conduct pipe-to-ground potential detection along the entire pipeline to determine the changes in pipe-to-ground potential along the entire pipeline;

[0053] By installing pipe-to-ground potential data monitoring instruments at test piles along the entire pipeline, the changes in pipe-to-ground potential along the entire pipeline are monitored when the UHVDC transmission system is operating at a single level, i.e., when the grounding electrode discharges.

[0054] S2: Determine the distribution of the cathode and anode areas along the entire pipeline based on the changes in pipeline-to-ground potential;

[0055] By comparing the pipe-to-ground potential at each discharge point with the pipe-to-ground potential under normal conditions, the pipe-to-ground potential at all points is divided into negative offset and positive offset. The pipe segment with negative offset is the cathode region, and the pipe segment with positive offset is the anode region.

[0056] S3: Determine the section of the pipeline most severely affected by external corrosion based on the distribution of the cathode and anode regions;

[0057] The cathode region is the section where stray DC current flows in, and the anode region is the section where stray DC current flows out. The section where stray DC current flows out is the area where the pipeline is severely corroded. The greater the positive deviation of the pipe-to-ground potential, the greater the outflow current density and the faster the pipeline corrosion rate. This is the section most severely affected by external corrosion of the pipeline.

[0058] S4: Calculate the current density flowing out of the section most severely affected by external corrosion of the pipeline, including the following steps:

[0059] S41: Determine the total damaged area of ​​the anti-corrosion layer in the target section;

[0060] Determining the total damaged area of ​​the anti-corrosion coating in the target section includes the following steps:

[0061] Under normal conditions, i.e. when the UHVDC grounding electrode is not discharged, the AC voltage gradient method (ACVG) is used to find the damage points of the anti-corrosion layer of the entire pipe section for the most severely corroded pipe section.

[0062] Based on practical experience, select an appropriate proportion, randomly inspect some anti-corrosion coating damage points, and excavate the pipeline. Determine the average area of ​​anti-corrosion coating damage at all excavation points as the typical value of the anti-corrosion coating damage area for that pipe section. The total anti-corrosion coating damage area S of the pipe section is obtained by multiplying the typical value by the number of damage points. 破损 In addition, the total damaged area of ​​the anti-corrosion layer in the target section can also be determined by detecting the anti-corrosion layer in a non-excavation manner.

[0063] S42: Calculate the total current flowing out from the point of damage to the anti-corrosion coating;

[0064] A loop-type DC current monitor is installed at the beginning and end of the target pipe section. This monitor can simultaneously record the magnitude and direction of the current in the pipe at both monitoring points. If the current at monitoring point A is I... A The current at monitoring point B is I. B ;

[0065] When the current directions at monitoring points A and B are opposite (i.e., the current flows from both ends to the middle), the total current I flowing out from the point of corrosion damage is... 总 For: I总 =I A +I B ;

[0066] If the current directions at monitoring points A and B are in the same direction (e.g., current flows in from point A and out from point B), the total current I flowing out from the point of corrosion damage will be... 总 For: I 总 =I A -I B ;

[0067] At the same time, the current I of all existing drainage facilities within the pipe section is... 排 Perform synchronous monitoring;

[0068] The outflow current density i in the most severely corroded section of the pipeline 流出 for:

[0069] i 流出 =(I 总 -I 排 ) / S 破损 .

[0070] S5: Calculate the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion based on current density;

[0071] According to Faraday's law, the relationship between the metal loss mass and the current density is as follows:

[0072] W = KIT

[0073] Where W is the mass of metal loss in kg; K is the electrochemical equivalent, which for iron is 1.731 × 10⁻⁶. -5 kg / A-min; I is current, in A; T is time;

[0074] Transforming the above formula, we get: c 腐蚀 =Ki 流出 T / ρ

[0075] Among them, c 腐蚀 The unit of measurement is: T = wall thinning during a single discharge, in mm; T = duration of a single discharge, in min; i = current density, in A / mm². 2 ρ represents the density of the pipe material, in kg / mm³. 3 ;

[0076] If a year is used as the monitoring period, the amount of pipe wall thinning during each discharge throughout the year is recorded and accumulated to obtain the annual pipe wall corrosion rate C. 腐蚀 .

[0077] S6: Evaluate the degree of influence of DC stray current on the pipeline based on the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion.

[0078] By comparing the calculated annual corrosion rate of the pipe wall with the maximum annual corrosion rate specified in the external corrosion protection requirements, it can be evaluated whether the current pipeline corrosion rate is within an acceptable range.

[0079] Calculate the total discharge current I of the drainage facilities in the target pipe section. 排 Total outflow current I in the pipe section 总 The percentage of the pipeline drainage system is compared with the percentage expected by the pipeline management unit to evaluate the effectiveness of the pipeline drainage system.

[0080] This method involves detecting the potential of the pipeline, determining the distribution of the cathode and anode regions based on the detected potential, identifying the section of the pipeline most severely affected by corrosion based on the distribution of the cathode and anode regions, calculating the current density of the most severely affected section, and then calculating the annual corrosion rate of the pipe wall based on the current density. Based on the annual corrosion rate of the pipe wall, the impact of UHVDC stray currents on the pipeline can be quantified, thereby enabling the simultaneous evaluation of the degree of corrosion on the outer wall of the pipeline and the effectiveness of the drainage facilities.

[0081] Example 2

[0082] like Figure 2 As shown, this embodiment provides a monitoring and assessment system for the degree of corrosion of pipelines, including:

[0083] The detection module is used to detect the pipe-to-ground potential along the entire pipeline and determine the changes in pipe-to-ground potential. Specifically, the pipe-to-ground potential data monitoring instrument is installed at the test piles along the entire pipeline to monitor the changes in pipe-to-ground potential along the entire pipeline when the UHVDC transmission system is operating in a single-stage mode, i.e., when the grounding electrode discharges.

[0084] The cathode and anode distribution determination module is used to determine the distribution of cathode and anode regions along the entire pipeline based on the pipeline-to-ground potential changes. Specifically, the pipeline-to-ground potential at all points is divided into negative offset and positive offset. Pipe sections with negative offset are cathode regions, and those with positive offset are anode regions.

[0085] The module for determining the most severely affected section of corrosion is used to identify the most severely affected section of external corrosion of the pipeline based on the distribution of the cathode and anode areas. Specifically, the cathode area is the section where DC stray current flows in, and the anode area is the section where DC stray current flows out. The section where DC stray current flows out is the area where the pipeline is severely corroded. The greater the positive offset of the pipe-to-ground potential, the greater the outflow current density and the faster the pipeline corrosion rate, which is the most severely affected section of external corrosion of the pipeline.

[0086] The current density calculation module is used to calculate the current density flowing out of the section of the pipe most severely affected by external corrosion.

[0087] The aforementioned current density calculation module includes a total damaged area calculation unit and a total current calculation unit;

[0088] The aforementioned total damaged area calculation unit is used to determine the total damaged area of ​​the anti-corrosion layer in the target section. Under normal conditions, i.e., when the UHVDC grounding electrode is not discharging, the total damaged area calculation unit is used to locate the damaged points of the anti-corrosion layer in the most severely corroded pipe section using the AC voltage gradient method (ACVG). A portion of the damaged anti-corrosion layer points are randomly selected for inspection, and pipeline excavation is conducted. The average value of the damaged area of ​​the anti-corrosion layer at all excavated points is determined as the typical value of the damaged area of ​​the anti-corrosion layer in that pipe section. The total damaged area S of the anti-corrosion layer in the pipe section is obtained by multiplying the typical value by the number of damaged points. 破损 .

[0089] The aforementioned total current calculation unit is used to calculate the total current flowing out from the point of damage to the anti-corrosion coating.

[0090] The annual corrosion rate calculation module is used to calculate the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion based on the current density. Specifically, a ring-type DC current monitor is installed at the beginning and end positions of the target pipe section. This monitor can simultaneously record the magnitude and direction of the current in the pipe at the two monitoring points. If the current magnitude at monitoring point A is I... A The current at monitoring point B is I. B ;

[0091] If the current directions at monitoring points A and B are opposite, then the total current I flowing out from the point of corrosion damage will be... 总 For: I 总 =I A +I B If the current directions at monitoring points A and B are in the same direction, then the total current I flowing out from the point of corrosion damage will be... 总 For: I 总 =I A -I B ;

[0092] The current I of all existing drainage facilities within the pipe section 排 Simultaneous monitoring was conducted; the outflow current density i in the most severely corroded section was measured. 流出 For: i 流出 =(I 总 -I 排 ) / S 破损 .

[0093] The annual corrosion rate calculation unit is used to calculate the pipe wall thickness loss. According to Faraday's law, the relationship between metal loss mass and current density is as follows:

[0094] W = KIT

[0095] Where W is the mass of metal loss in kg; K is the electrochemical equivalent, which for iron is 1.731 × 10⁻⁶.-5 kg / A-min; I is current, in A; T is time;

[0096] Transforming the above formula, we get: c 腐蚀 =Ki 流出 T / ρ

[0097] Among them, c 腐蚀 The unit of measurement is: T = wall thinning during a single discharge, in mm; T = duration of a single discharge, in min; i = current density, in A / mm². 2 ρ represents the density of the pipe material, in kg / mm³. 3 ;

[0098] The annual pipe wall thinning amount for each discharge throughout the year is recorded and summed to obtain the annual pipe wall corrosion rate C. 腐蚀 .

[0099] The evaluation module is used to evaluate the degree of influence of DC stray current on the pipeline based on the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion. Specifically, by comparing the calculated annual corrosion rate of the pipe wall with the maximum annual corrosion rate specified in the external corrosion protection requirements, it can be evaluated whether the current pipeline corrosion rate is within an acceptable range.

[0100] Calculate the total discharge current I of the drainage facilities in the target pipe section. 排 Total outflow current I in the pipe section 总 The percentage of the pipeline drainage system is compared with the percentage expected by the pipeline management unit to evaluate the effectiveness of the pipeline drainage system.

[0101] This device no longer uses individual monitoring points as the basis for evaluation. Instead, after determining the most severely affected section, it uses the entire pipe section as the object of monitoring and evaluation. It also considers the protective effects of drainage facilities. Based on quantifying the degree of UHVDC stray impact, it can quantify the degree of UHVDC stray impact on the pipeline according to the annual corrosion rate of the pipe wall. Thus, it can simultaneously evaluate the degree of corrosion on the outer wall of the pipeline and the effectiveness of drainage facilities.

[0102] Example 3

[0103] An electronic device, comprising a storage device and one or more processors;

[0104] Storage device for storing one or more programs;

[0105] When one or more programs are executed by one or more processors, the one or more processors implement a method for monitoring and evaluating the degree of corrosion of pipelines as described in Example 1.

[0106] This electronic device no longer uses individual monitoring points as the basis for evaluation. Instead, after determining the most severely affected section, it uses the entire pipe section as the object of monitoring and evaluation. It also considers the protective effects of drainage facilities. Based on quantifying the degree of UHVDC stray impact, it can quantify the degree of UHVDC stray impact on the pipeline according to the annual corrosion rate of the pipe wall. Thus, it can simultaneously evaluate the degree of corrosion on the outer wall of the pipeline and the effectiveness of the drainage facilities.

[0107] Example 4

[0108] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for monitoring and evaluating the degree of corrosion of a pipeline as described in Example 1.

[0109] Instead of using individual monitoring points as the basis for evaluation, this method uses the entire pipe section as the object of monitoring and evaluation after determining the most severely affected section. It also considers the protective effects of drainage facilities. Based on quantifying the degree of UHVDC stray impact, the impact of UHVDC stray on the pipeline can be quantified according to the annual corrosion rate of the pipe wall. Thus, it is possible to simultaneously evaluate the degree of corrosion on the outer wall of the pipeline and the effectiveness of the drainage facilities.

Claims

1. A method for monitoring and evaluating the degree of corrosion of pipelines, characterized in that: Includes the following steps: Conduct pipe-to-ground potential detection along the entire pipeline to determine the changes in pipe-to-ground potential along the entire pipeline; The distribution of the cathode and anode areas along the entire pipeline is determined based on the changes in pipe-to-ground potential. Specifically, the pipe-to-ground potential at all points is divided into negative offset and positive offset. Pipe sections with negative offset are cathode areas, and those with positive offset are anode areas. The section most severely affected by external corrosion of the pipeline is determined based on the distribution of the cathode and anode areas. The cathode area is the section where DC stray current flows in, and the anode area is the section where DC stray current flows out. The section where DC stray current flows out is the area where the pipeline is severely corroded. The greater the positive offset of the pipe-to-ground potential, the greater the outflow current density and the faster the pipeline corrosion rate. The corresponding pipe section is the section most severely affected by external corrosion of the pipeline. Calculate the current density flowing out of the section of the pipeline most severely affected by external corrosion; The annual corrosion rate of the pipe wall in the section most severely affected by external corrosion is calculated based on the current density. The degree of influence of DC stray current on the pipeline is evaluated based on the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion. The calculation of the current density flowing out of the section most severely affected by external corrosion of the pipeline includes the following steps: Determine the total damaged area of ​​the anti-corrosion layer in the target section; Calculate the total current flowing out from the point of damage to the anti-corrosion coating; Determining the total damaged area of ​​the anti-corrosion layer in the target section includes the following steps: For the most severely corroded pipe section, the AC potential gradient method was used to locate the damage points of the anti-corrosion coating throughout the entire pipe section; By randomly inspecting some damaged points in the anti-corrosion coating, the average area of ​​all damaged anti-corrosion coatings on the pipeline was determined as the typical value of the damaged area of ​​the anti-corrosion coating for that pipeline section. The total damaged area of ​​the anti-corrosion coating for the pipeline section was obtained by productting the typical value with the number of damaged points. ; To calculate the total current flowing out from the point of corrosion damage, monitoring point A is set at the beginning of the target pipe section and monitoring point B is set at the end. The current at monitoring point A is simultaneously recorded using a DC current monitor in the pipe. The current magnitude at monitoring point B is : If the current directions at monitoring points A and B are opposite, then the total current flowing out from the point of corrosion damage will be... for: ; If the current directions at monitoring points A and B are in the same direction, then the total current flowing out from the point of corrosion damage will be... for: ; Current of all existing drainage facilities within the pipe section Perform synchronous monitoring; Outflow current density of the most severely corroded section for: ； In calculating the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion based on current density, according to Faraday's law, the relationship between metal loss mass and current density is as follows: Where W is the mass of metal loss in kg; K is the electrochemical equivalent; I is the current in A; and T is the time. Transforming the above formula, we get: in, The unit of measurement is: T = (thinnings in mm) / (thinnings in min) where T is the duration of a single discharge; and i is the current density. ρ represents the density of the pipe material, in units of... ; The annual pipe wall thinning amount for each discharge throughout the year is recorded and summed to obtain the annual pipe wall corrosion rate. .

2. The method for monitoring and evaluating the degree of corrosion of a pipeline according to claim 1, characterized in that: To determine the changes in pipeline-to-ground potential, pipe-to-ground potential monitoring is conducted along the entire pipeline. This is achieved by installing pipe-to-ground potential data monitoring instruments at test piles along the entire pipeline to monitor the changes in pipeline-to-ground potential during single-stage operation of the DC transmission system.

3. A monitoring and assessment system for the degree of corrosion of pipelines, used to perform the monitoring and assessment method according to claim 1 or 2, characterized in that: include The detection module is used to detect the pipe-to-ground potential along the entire pipeline and determine the changes in pipe-to-ground potential along the entire pipeline. The cathode and anode distribution determination module is used to determine the distribution of cathode and anode regions along the entire pipeline based on the pipeline-to-ground potential changes. Specifically, the pipeline-to-ground potential at all points is divided into negative offset and positive offset. Pipe sections with negative offset are cathode regions, and those with positive offset are anode regions. The module for determining the most severely affected section of corrosion is used to determine the most severely affected section of external corrosion of the pipeline based on the distribution of the cathode area and the anode area. The cathode area is the section where DC stray current flows in, and the anode area is the section where DC stray current flows out. The section where DC stray current flows out is the area where the pipeline is severely corroded. The greater the positive offset of the pipe-to-ground potential, the greater the outflow current density and the faster the pipeline corrosion rate. The corresponding pipe section is the most severely affected section of external corrosion of the pipeline. The current density calculation module is used to calculate the current density flowing out of the section of the pipe most severely affected by external corrosion. The annual corrosion rate calculation module is used to calculate the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion based on the current density. The evaluation module is used to evaluate the degree of influence of DC stray current on the pipeline based on the annual corrosion rate of the pipe wall in the section most severely affected by external corrosion.

4. The pipeline corrosion monitoring and assessment system according to claim 3, characterized in that: The current density calculation module includes a total damaged area calculation unit and a total current calculation unit; The total damaged area calculation unit is used to determine the total damaged area of ​​the anti-corrosion layer in the target section. The total current calculation unit is used to calculate the total current flowing out from the point of damage to the anti-corrosion layer.

5. An electronic device, characterized in that: Includes a storage device and one or more processors; Storage device for storing one or more programs; When one or more programs are executed by one or more processors, the one or more processors implement the method for monitoring and evaluating the degree of corrosion of pipelines as described in any one of claims 1 to 2.

6. A computer-readable storage medium storing a computer program thereon, characterized in that: When the computer program is executed by the processor, it implements the method for monitoring and evaluating the degree of corrosion of the pipeline as described in any one of claims 1 to 2.

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