Constant potential instrument output adjusting method under stray current interference

Abstract

The application discloses a kind of stray current interference under constant potential instrument output adjustment method, steps include: setting target pipe section, setting monitoring point, closing constant potential instrument, calculating average inflow and outflow current density, performing test measurement, obtaining relationship curve, obtaining acceptable preset current range, performing preset current adjustment.In the embodiment of the application, the curve of the off-power potential and the negative protection current is obtained, and the superposition theorem is used to obtain the test piece current density of the negative protection standard range boundary, which is superimposed with the inflow or outflow current during interference to obtain the off-power potential during interference. The preset current of the constant potential instrument in the negative protection standard range is obtained by using the obtained off-power potential and the preset current curve, and finally the constant potential instrument operates according to the obtained preset current. The pipeline can maintain negative protection standard under interference, and the whole process does not need manual setting, the requirement for personnel is low, and the negative protection effect of the pipeline can reach the best state.

Description

Technical Field

[0001] This invention belongs to the field of cathodic protection and corrosion prevention technology, and particularly relates to a method for adjusting the output of a potentiostat under stray current interference. Background Technology

[0002] Forced current cathodic protection is one of the main methods for corrosion protection of buried pipelines, and the potentiostat is the core equipment of the forced current cathodic protection system. The potentiostat has constant potential (constant on-current potential), constant current, and constant voltage working modes, and the new type of potentiostat also adds a constant off-current potential working mode.

[0003] When the dynamic DC interference is not too large, although the large fluctuation of the energized potential on the pipeline makes it impossible for the potentiostat to operate in constant energized potential mode, the constant potentiostat can still operate in constant de-energized potential mode because the fluctuation of the de-energized potential on the pipeline is small.

[0004] However, for pipelines with significant dynamic DC stray current interference, the constant potential on the pipeline fluctuates greatly, and the constant potential on the pipeline also fluctuates greatly. The constant potential meter cannot operate in either the constant on-state potential mode or the constant off-state potential mode. In this case, the constant current mode will be selected. In the constant current mode, the constant potential meter will continuously output the cathodic protection current according to the preset current value to provide cathodic protection for the pipeline.

[0005] There are many sources of interference along the pipeline. AC interference sources, represented by AC high-voltage power transmission systems, and DC interference sources, represented by subways, can cause AC and DC interference to the pipeline. Especially in economically developed areas, pipelines often experience mixed AC and DC interference.

[0006] Because the cathodic protection criteria for pipelines differ under DC and AC interference, and the current selection of potentiostat operating parameters is mostly based on experience and actual site conditions, the preset current parameters of the potentiostat in constant current mode are manually set by the technician. There is a lack of quantitative analysis methods for preset current parameters, and manual analysis often fails to achieve the best results. Furthermore, manual analysis requires comprehensive analysis of pipeline distribution, soil environment, AC and DC interference, drainage facilities, etc., which places high demands on the technical personnel's skills. Summary of the Invention

[0007] To address the shortcomings of related technologies, this invention provides a method for adjusting the output of a potentiostat under stray current interference, thereby solving the problems of poor cathodic protection effect and high personnel requirements caused by the manual setting of the preset current setting of the potentiostat under stray current interference.

[0008] This invention provides a method for adjusting the output of a potentiostat under stray current interference, the steps of which are as follows:

[0009] S10: Take a section of the pipe connected to the target potentiostat as the target pipe section;

[0010] S20: Select N monitoring points on the target pipe section, where N is a positive integer;

[0011] S30: Adjustment begins;

[0012] S40: Shut down all potentiostats connected to the pipeline; in case of DC interference, simultaneously monitor the monitoring points. ~ The test piece was measured multiple times for its first DC current density;

[0013] S50: Monitoring points ~ The first DC current density corresponding to the inflow current of the test piece is set as the first inflow current density. and the first inflow current density Set to a positive value; set the monitoring point ~ The first DC current density corresponding to the outflow current of the test piece is set as the first outflow current density. and the first outflow current density Set to a negative value;

[0014] S60: Calculate the monitoring points separately ~ The corresponding first inflow current density The average value of the monitoring points is obtained. ~ First average inflow current density ~ ; Calculate the monitoring points respectively ~ The corresponding first outflow current density The average value of the monitoring points is obtained. ~ First average outflow current density ~ ;

[0015] S70: In the absence of DC interference, the target potentiostat operates in constant off-voltage mode and sets multiple preset off-voltages. Simultaneously, the target potentiostat measures the monitoring points while operating at each preset off-voltage. ~ The test DC current density and test power-off potential of the set test piece are measured, and the current output current of the target potentiostat is obtained.

[0016] S80: Monitoring points ~ The test DC current density and the test power-off potential are fitted to obtain the monitoring point. ~ The power outage potential-cathode current density curve; monitoring points ~ The power-off potential and the corresponding output current are fitted to obtain the monitoring point. ~ The power-off potential-output current curve;

[0017] S90: Obtain monitoring points ~ Acceptable low-level preset current ~ And acceptable high preset current ~ ;

[0018] S100: Acceptable low-level preset current ~ The maximum value in the range is used as the acceptable lower limit preset current. Acceptable high-level preset current ~ The minimum value in the set range is used as the acceptable upper limit preset current. ;

[0019] S110: If the upper limit preset current is acceptable Current greater than the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the upper limit preset current. With acceptable lower limit preset current Between; if the upper limit preset current is acceptable Equal to the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the upper limit preset current. Or acceptable lower limit preset current ;

[0020] Among them, the acquisition of monitoring points ~ Acceptable low-level preset current ~ The specific steps are as follows:

[0021] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary low-level simulated current density at a power-off potential of -0.85V ~ The initial low-level simulated current density will be used. ~ Each is compared with the corresponding first average outflow current density ~ Subtraction yields an acceptable low-bit analog current density. ~ Acceptable low analog current density ~ Through monitoring points ~ The power-off potential-cathode current density curve yields an acceptable low-level simulated power-off potential. ~ Acceptable low-level simulated power failure potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Acceptable low-level preset current ~ ;

[0022] Acquire monitoring points ~ Acceptable high-level preset current ~ The specific steps are as follows:

[0023] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary high-level simulated current density at a power-off potential of -1.2V ~ The initial high-level simulated current density will be used to simulate the current density. ~ Each with the corresponding first average inflow current density ~ Subtraction yields an acceptable high-level analog current density. ~ Acceptable high analog current density ~ Through monitoring points ~ The power outage potential-cathode current density curve yields an acceptable high-level simulated power outage potential. ~ Acceptable high-level simulated power failure potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Acceptable high-level preset current ~ .

[0024] In some embodiments, steps S41 to S44 are further included between step S30 and step S90;

[0025] S41: Turn off all potentiostats connected to the pipeline. Use the period of DC interference as the test period, and divide the test period into M equal window periods (M is a positive integer). Measure the monitoring points within each window period. ~ The second DC current density of the test piece;

[0026] S42: Set the second DC current density corresponding to the current flowing into the test piece to the second current flowing into density. and the second inflow current density Set to a positive value; set the second DC current density corresponding to the outflow current of the test piece to the second outflow current density. and the second outflow current density Set to a negative value;

[0027] S43: Calculate all second inflow current densities within the same window period. The average value is used to obtain the window period. ~ Second average inflow current density ~ ; Calculate the total second outflow current density within the same time window. The average value is used to obtain the window period. ~ Second average outflow current density ~ ;

[0028] S44: The second average inflow current density ~ The maximum value in is set as the maximum inflow DC current density. The second average outflow current density ~ The maximum value in is set as the maximum outflow DC current density. ...

[0029] In some embodiments, step S90 further involves acquiring monitoring points. ~ Ideal low-level preset current ~ and ideal high-level preset current ~ ;

[0030] In step S100, the ideal low-order preset current is further... ~ The maximum value in is used as the ideal lower limit preset current. Ideal high-level preset current ~ The minimum value in the range is used as the ideal upper limit preset current. ;

[0031] Step S110 is replaced with: If the ideal upper limit preset current is... Current greater than the ideal lower limit preset current Then adjust the output current of the target potentiostat to the ideal upper limit preset current. With the ideal lower limit preset current Between; if the ideal upper limit preset current equal to the ideal lower limit preset current Then adjust the output current of the target potentiostat to the ideal upper limit preset current. Or ideal lower limit preset current If the ideal upper limit preset current Less than the ideal lower limit preset current And it can accept the upper limit preset current. ≥ Ideal lower limit preset current ≥ Acceptable lower limit preset current Then adjust the output current of the target potentiostat to the ideal lower limit preset current. If the ideal upper limit preset current Less than the ideal lower limit preset current Acceptable upper limit preset current ≥ Acceptable lower limit preset current And the ideal lower limit preset current Current greater than the acceptable upper limit preset Or less than the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the acceptable upper limit preset current. ;

[0032] Among them, the acquisition of monitoring points ~ Ideal low-level preset current ~ The specific steps are as follows:

[0033] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary low-level simulated current density at a power-off potential of -0.85V ~ The initial low-level simulated current density will be used. ~ Both are related to the maximum outflow DC current density Subtraction yields the ideal low-side analog current density. ~ ; to simulate ideal low-order current density ~ Through monitoring points ~ The power-off potential-cathode current density curve is used to obtain the ideal low-level simulated power-off potential. ~ The ideal low-level simulated power outage potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Ideal low-level preset current ~ ;

[0034] Acquire monitoring points ~ Ideal high-level preset current ~ The specific steps are as follows:

[0035] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary high-level simulated current density at a power-off potential of -1.2V ~ The initial high-level simulated current density will be used to simulate the current density. ~ Both are related to the maximum inflow DC current density Subtraction yields the ideal high-level analog current density. ~ ; to simulate ideal high-level current density ~ Through monitoring points ~ The power-off potential-cathode current density curve is used to obtain the ideal high-level simulated power-off potential. ~ The ideal high-level simulated power outage potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Ideal high-level preset current ~ .

[0036] In some embodiments, steps S51 to S53 are further included between step S30 and step S90;

[0037] S51: Close all potentiostats connected to the pipeline and simultaneously monitor the points. ~ The AC current density of the test piece was measured multiple times.

[0038] S52: Calculate the monitoring points separately ~ The average value of the alternating current density is obtained. ~ ;

[0039] S53: If the average AC current density of the monitoring point is greater than or equal to the AC interference threshold, then in step S90, the preliminary low-level simulated current density of the corresponding monitoring point at the power-off potential of -0.85V is replaced with the preliminary low-level simulated current density of the corresponding monitoring point at the power-off potential of -0.9V; and the preliminary high-level simulated current density of the corresponding monitoring point at the power-off potential of -1.2V is replaced with the preliminary high-level simulated current density of the corresponding monitoring point at the power-off potential of -1.15V.

[0040] In some embodiments, prior to step S30, the pipeline maintains an electrical connection with a plurality of drainage devices disposed along its route, which drain water from the pipeline.

[0041] In some embodiments, in step S110, if the upper limit preset current is acceptable... Less than the acceptable lower limit preset current If so, a drainage device is added along the pipeline. After the added drainage device drains the pipeline, the process returns to step S30.

[0042] In some embodiments, the monitoring points include a first monitoring point, a second monitoring point, a third monitoring point, a fourth monitoring point, a fifth monitoring point, a sixth monitoring point, a seventh monitoring point, and an eighth monitoring point;

[0043] The first monitoring point is located at the beginning of the target pipe section; the second monitoring point is located at the end of the target pipe section; the third monitoring point is located at the midpoint between the target potentiostat and the beginning of the target pipe section; the fourth monitoring point is located at the midpoint between the target potentiostat and the end of the target pipe section; the fifth monitoring point is the position where the power-off potential on the target pipe section is most positive when the cathodic protection is normal; the sixth monitoring point is the position where the power-off potential on the target pipe section is most negative when the cathodic protection is normal; the seventh monitoring point is the position where the target pipe section is most affected by DC interference; and the eighth monitoring point is the position where the target pipe section is most affected by AC interference.

[0044] In some embodiments, the monitoring points further include a ninth monitoring point, a tenth monitoring point, an eleventh monitoring point, and a twelfth monitoring point;

[0045] The ninth and tenth monitoring points are located on either side of the seventh monitoring point, and the eleventh and twelfth monitoring points are located on either side of the eighth monitoring point.

[0046] In some embodiments, the starting point of the target pipe segment is located at the midpoint between the target potentiostat and its upstream adjacent potentiostat, and the ending point of the target pipe segment is located at the midpoint between the target potentiostat and its downstream adjacent potentiostat.

[0047] In some embodiments, in step S70, the preset power-off potential is located within a set potential range, the set potential range being between -0.85V and -1.2V, and the preset power-off potential includes -0.85V, -0.9V, -1.15V, and -1.2V.

[0048] Based on the above technical solution, in this embodiment of the invention, by obtaining the curve of the power-off potential and the cathodic protection current, and using the superposition theorem that the current flowing through the test piece is the sum of the interference current and the cathodic protection current, the test piece current density at the boundary of the cathodic protection compliance range is obtained. Then, it is superimposed with the inflow or outflow current during interference to obtain the power-off potential during interference. Then, using the obtained curve of the power-off potential and the preset current, the preset current of the potentiostat within the cathodic protection compliance range is obtained. Finally, the potentiostat is made to operate according to the obtained preset current, so that the pipeline can maintain cathodic protection compliance under interference. The whole process does not require manual setting, has low personnel requirements, and can make the cathodic protection effect of the pipeline reach the best state. It solves the problems of poor cathodic protection effect and high personnel requirements caused by the manual setting of the preset current of the potentiostat under stray current interference. Detailed Implementation

[0049] The technical solutions in 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 a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0050] In the description of this invention, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship 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 limitations on this invention.

[0051] The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] In an illustrative embodiment of the potentiostat output adjustment method under stray current interference of the present invention, the method includes the following steps:

[0054] S10: Select one potentiostat as the target potentiostat from among the various potentiostats electrically connected along the pipeline, and select a section of the pipeline as the target pipe section. The target pipe section is electrically connected to the target potentiostat.

[0055] S20: Select N monitoring points on the target pipe section, where N is a positive integer. Each monitoring point has a test piece buried on one side of it, and the test pieces are electrically connected to the corresponding monitoring point.

[0056] S30: Adjustment begins.

[0057] S40: Shut down all potentiostats connected to the pipeline. In the event of DC stray current interference, synchronously measure the monitoring points. ~ The test piece is configured with a first DC current density, and multiple first DC current densities are measured at each monitoring point. Depending on the DC interference source, the timing of stray DC current generation from each source follows a pattern. Taking a subway as an example, the subway's operating hours are the periods when stray DC current interference occurs, while the subway's shutdown hours are the periods when no stray DC current interference occurs. Therefore, when measuring the first DC current density along a pipeline with a subway line, the subway's operating hours are selected for measurement. The first DC current density is the current flowing through the test piece during DC interference divided by the area of ​​the test piece.

[0058] S50: Monitoring points ~ The first DC current density corresponding to the inflow current of the test piece is set as the first inflow current density. and the first inflow current density Set to a positive value; set the monitoring point ~ The first DC current density corresponding to the outflow current of the test piece is set as the first outflow current density. and the first outflow current density Set to a negative value. Based on whether the test piece is experiencing an inflow or outflow of current, set the monitoring point... ~ All first DC current densities are classified: inflow currents are designated as first inflow current densities and assigned positive values, while outflow currents are designated as first outflow current densities and assigned negative values. When measuring the current flowing through the test piece, the direction of the current can be determined using an ammeter, indicating whether the current flowing through the test piece is flowing into or out of it.

[0059] S60: Calculate the monitoring points separately ~ The corresponding first inflow current density The average value of the monitoring points is obtained. ~ First average inflow current density ~ That is, for each monitoring point, the sum of all the first inflow current densities corresponding to that monitoring point is divided by their magnitude to obtain the first average inflow current density of that monitoring point. Finally, the first average inflow current density corresponding to all monitoring points is obtained; the calculations for each monitoring point are performed separately. ~ The corresponding first outflow current density The average value of the monitoring points is obtained. ~ First average outflow current density ~ That is, for each monitoring point, the sum of all the first outflow current densities corresponding to that monitoring point is divided by its quantity to obtain the first average outflow current density of that monitoring point, and finally the first average outflow current density corresponding to all monitoring points is obtained.

[0060] S70: In the absence of DC interference, the target potentiostat operates in constant off-voltage mode, while other potentiostats along the pipeline remain off. Multiple preset off-voltages are set for the target potentiostat. Simultaneously, monitoring points are measured while the target potentiostat operates at each preset off-voltage. ~ The test DC current density and off-voltage of the set test piece are measured, and the current output current of the target potentiostat is obtained. More specifically, when there is no DC stray current interference, only the target potentiostat operates in constant off-voltage mode along the pipeline. The target potentiostat operates at the first preset off-voltage until the off-voltage at the connection point on the pipeline with the target potentiostat reaches the preset off-voltage and stabilizes for a period of time, allowing the pipeline to be sufficiently polarized. Then, the monitoring points are measured simultaneously. ~ The test DC current density and test power-off potential of the test piece are set, and the current output current of the target potentiostat is obtained at the same time.

[0061] S80: Monitoring points ~ The test DC current density and the power-off potential are fitted to obtain the monitoring points. ~ The power-off potential-cathode current density curve reflects the relationship between the power-off potential and the DC current density at each monitoring point when there is no DC interference. ~ The power-off potential and the corresponding output current are fitted to obtain the monitoring point. ~ The power-off potential-output current curve reflects the relationship between the power-off potential and the output current of the target potentiostat at each monitoring point when there is no DC interference.

[0062] S90: Obtain monitoring points ~ Acceptable low-level preset current ~ And acceptable high preset current ~ .

[0063] Acquire monitoring points ~ Acceptable low-level preset current ~ The specific steps are as follows:

[0064] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary low-level simulated current density at a power-off potential of -0.85V ~ The initial low-level simulated current density will be used to simulate the current density. ~ Each is compared with the corresponding first average outflow current density ~ Subtraction yields an acceptable low-bit analog current density. ~ Acceptable low analog current density ~ Through monitoring points ~ The power-off potential-cathode current density curve yields an acceptable low-level simulated power-off potential. ~ Acceptable low-level simulated power failure potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Acceptable low-level preset current ~ .

[0065] Acquire monitoring points ~ Acceptable high-level preset current ~ The specific steps are as follows:

[0066] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary high-level simulated current density at a power-off potential of -1.2V ~ The initial high-level simulated current density will be used to simulate the current density. ~ Each with the corresponding first average inflow current density ~ Subtraction yields an acceptable high-level analog current density. ~ Acceptable high analog current density ~ Through monitoring points ~ The power-off potential-cathode current density curve yields an acceptable high-level simulated power-off potential. ~ Acceptable high-level simulated power failure potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Acceptable high-level preset current ~ .

[0067] When obtaining the acceptable low-level and acceptable high-level preset currents, the relationship between the power-off potential and DC current density at each monitoring point is first utilized. Specifically, the power-off potential-cathode current density curve for each monitoring point is used to obtain the DC current density at both ends of the cathode protection compliance range. Then, using the superposition principle, the calculated DC current density is superimposed with the average inflow or outflow DC current density to estimate the DC current density on the test piece at each monitoring point when DC interference occurs and the power-off potential is at both ends of the compliance range. Again, the relationship between the power-off potential and DC current density at each monitoring point is used to convert the estimated DC current density from the superposition of values ​​at each monitoring point into a power-off potential. Finally, the relationship between the power-off potential at each monitoring point and the output current of the target potentiostat is used to convert all power-off potentials into output current, thereby estimating the output current required by the potentiostat for each monitoring point to reach the boundary of the compliance potential range when DC interference occurs.

[0068] S100: Acceptable low-level preset current ~ The maximum value in the range is used as the acceptable lower limit preset current. Acceptable high-level preset current ~ The minimum value in the set range is used as the acceptable upper limit preset current. .

[0069] S110: Judge the two boundaries of the target potentiostat preset current obtained in step S100 to determine the acceptable current range. If the upper limit of the preset current is acceptable... Current greater than the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the upper limit preset current. With acceptable lower limit preset current Between, that is, the output current of the target potentiostat adopts and Any value between these ranges allows the de-energization potential at various points along the target pipeline to achieve optimal cathodic protection under DC interference. If the upper limit preset current is acceptable... Equal to the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the upper limit preset current. Or acceptable lower limit preset current When the two boundaries of the output current are the same, the target potentiostat uses that boundary value as the output current, ensuring that the de-energized potential at each point in the target pipeline reaches the optimal cathodic protection state under DC interference. Acceptable upper limit preset current. Greater than or equal to the acceptable lower limit preset current If the acceptable current range is not empty, the preset current of the target potentiostat can be selected within the acceptable current range.

[0070] In the above illustrative embodiment, the potentiostat output adjustment method under stray current interference obtains the curves of the power-off potential and the cathode protection current, as well as the curves of the power-off potential and the output current when no DC stray current interference occurs, in steps S40 to S80, thereby determining the relationship between the DC current density, power-off potential, and target potentiostat output current at each monitoring point; furthermore, the outflow or outflow of the test piece current at the monitoring point when DC stray current interference occurs, and the power-off potential and DC current density of the test piece at the monitoring point when no DC stray current interference occurs, are compared using the superposition theorem. By superimposing and estimating the target potentiostat output current when the power-off potential of each monitoring point reaches the compliant potential range during DC stray current interference, the preset current of the potentiostat within the cathodic protection compliant range is finally obtained. The potentiostat operates according to the obtained preset current, which can maintain the pipeline in the best cathodic protection state under DC interference. The whole process does not require manual setting, has low personnel requirements, and can achieve the best cathodic protection effect for the pipeline. It solves the problems of poor cathodic protection effect and high personnel requirements caused by manual setting of the preset current of the potentiostat under stray current interference.

[0071] In some embodiments, steps S41 to S44 are further included between steps S30 and S90;

[0072] S41: Turn off all potentiostats connected to the pipeline. Use the period of DC interference as the test period, and divide the test period into M equal window periods (M is a positive integer). Measure the monitoring points within each window period. ~ The second DC current density of the test piece.

[0073] S42: Set the second DC current density corresponding to the current flowing into the test piece to the second current flowing into density. and the second inflow current density Set to a positive value; set the second DC current density corresponding to the outflow current of the test piece to the second outflow current density. and the second outflow current density Set to a negative value.

[0074] S43: Calculate all second inflow current densities within the same window period. The average value is used to obtain the window period. ~ Second average inflow current density ~ ; Calculate the total second outflow current density within the same time window. The average value is used to obtain the window period. ~ Second average outflow current density ~ .

[0075] S44: The second average inflow current density ~ The maximum value in is set as the maximum inflow DC current density. The second average outflow current density ~ The maximum value in is set as the maximum outflow DC current density. .

[0076] In steps S41 to S44, the period during which DC stray current interference occurs is divided into multiple time windows of equal duration. The average DC current density flowing in or out of each time window is measured sequentially, and the maximum inflow and outflow current densities are selected. This eliminates the impact of a sudden and significant increase in DC stray current interference on the acquisition of the average inflow and outflow current densities. A larger value for M results in a smaller time window, which better eliminates the impact of a significant increase in DC interference on the acquisition of inflow and outflow current densities. However, if M is too large, a larger interference peak will be obtained, which will affect the range of the final value selected by the potentiostat. Therefore, the value of M should be reasonably selected based on the actual pipeline conditions. When acquiring the second DC current density in each time window, the DC current density of the test piece at a certain moment in the current time window can be used; alternatively, the DC current density of the test piece at multiple moments in the current time window can be acquired, and the average of the DC current densities can be used as the second DC current density, increasing the number of measurements and improving the accuracy of the data. Steps S41 to S44 can be performed simultaneously with steps S40 to S80, before step S40, or after step S80.

[0077] In some embodiments, in step S90, monitoring points are further acquired. ~ Ideal low-level preset current ~ and ideal high-level preset current ~ .

[0078] Acquire monitoring points ~ Ideal low-level preset current ~ The specific steps are as follows:

[0079] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary low-level simulated current density at a power-off potential of -0.85V ~ The initial low-level simulated current density will be used to simulate the current density. ~ Both are related to the maximum outflow DC current density Subtraction yields the ideal low-side analog current density. ~ ; to simulate ideal low-order current density ~ Through monitoring points ~ The power-off potential-cathode current density curve is used to obtain the ideal low-level simulated power-off potential. ~ The ideal low-level simulated power outage potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Ideal low-level preset current ~ ;

[0080] Acquire monitoring points ~ Ideal high-level preset current ~ The specific steps are as follows:

[0081] According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary high-level simulated current density at a power-off potential of -1.2V ~ The initial high-level simulated current density will be used to simulate the current density. ~ Both are related to the maximum inflow DC current density Subtraction yields the ideal high-level analog current density. ~ ; to simulate ideal high-level current density ~ Through monitoring points ~ The power-off potential-cathode current density curve is used to obtain the ideal high-level simulated power-off potential. ~ The ideal high-level simulated power outage potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Ideal high-level preset current ~ .

[0082] In the same way as obtaining the acceptable low-level preset current and the acceptable high-level preset current, the ideal low-level preset current and the ideal high-level preset current are obtained. That is, the output current required by the target potentiostat to make the power-off potential reach the boundary of the standard potential range when DC interference occurs and the measurement is performed according to the time window is slid. The obtained preset current eliminates the influence caused by the significant increase in DC interference and is more accurate.

[0083] In step S100, the ideal low-order preset current is further... ~ The maximum value in is used as the ideal lower limit preset current. Ideal high-level preset current ~ The minimum value in the range is used as the ideal upper limit preset current. .

[0084] Step S110 is replaced with: If the ideal upper limit preset current is... Current greater than the ideal lower limit preset Then adjust the output current of the target potentiostat to the ideal upper limit preset current. With ideal lower limit preset current Between; if the ideal upper limit preset current equal to the ideal lower limit preset current Then adjust the output current of the target potentiostat to the ideal upper limit preset current. Or ideal lower limit preset current If the ideal upper limit preset current Less than the ideal lower limit preset current And it can accept the upper limit preset current. ≥ Ideal lower limit preset current ≥ Acceptable lower limit preset current Then adjust the output current of the target potentiostat to the ideal lower limit preset current. If the ideal upper limit preset current Less than the ideal lower limit preset current Acceptable upper limit preset current ≥ Acceptable lower limit preset current And the ideal lower limit preset current Current greater than the acceptable upper limit preset Or less than the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the acceptable upper limit preset current. .

[0085] After eliminating the impact of a short-term surge in DC interference, the ideal current range is determined by the ideal lower limit preset current and the ideal upper limit preset current.

[0086] Ideal upper limit preset current Greater than or equal to the ideal lower limit preset current When the ideal current range is not empty, the target potentiostat prioritizes the selection of a preset current within the ideal current range for operation, so that the de-energized potential at each point of the target pipeline reaches the optimal cathodic protection state under DC interference.

[0087] Ideal upper limit preset current Less than the ideal lower limit preset current Acceptable upper limit preset current ≥ Acceptable lower limit preset current And the ideal lower limit preset current Current greater than the acceptable upper limit preset Or less than the acceptable lower limit preset current If the ideal current range is empty, but the acceptable current range is not empty, and the ideal lower limit preset current is within the acceptable current range, the target potentiostat will operate with the ideal lower limit preset current as the preset current. Under the condition of avoiding underprotection of the target pipeline, it will minimize overprotection, so that the power failure potential at each point of the target pipeline can reach the best cathodic protection state under DC interference.

[0088] Ideal upper limit preset current Less than the ideal lower limit preset current Acceptable upper limit preset current ≥ Acceptable lower limit preset current And the ideal lower limit preset current Current greater than the acceptable upper limit preset Or less than the acceptable lower limit preset current If the ideal current range is empty, but the acceptable current range is not empty, and the ideal lower limit preset current is not within the acceptable current range, the target potentiostat will operate with the ideal upper limit preset current as the preset current to minimize the underprotection of the target pipe section, so that the power failure potential at each point of the target pipeline can reach the best cathodic protection state under DC interference.

[0089] By using a time window to obtain the average current density, not only is the impact of short-term large changes in DC interference on the measurement results eliminated, but the ideal potential range can also be obtained. When selecting the preset current of the potentiostat, in the case that it is not possible to guarantee that the potential of the entire target pipe section meets the standard, under-protection is avoided and over-protection is reduced, or over-protection is reduced to the greatest extent possible, so as to achieve the best cathodic protection state under the current conditions.

[0090] In some embodiments, steps S51 to S53 are further included between steps S30 and S90.

[0091] S51: Close all potentiostats connected to the pipeline and simultaneously monitor the points. ~ The AC current density of the test piece was measured multiple times.

[0092] S52: Calculate the monitoring points separately ~ The average value of the alternating current density is obtained. ~ .

[0093] S53: If the average AC current density of the monitoring point is greater than or equal to the AC interference threshold, then in step S90, the preliminary low-level simulated current density of the corresponding monitoring point at the power-off potential of -0.85V is replaced with the preliminary low-level simulated current density of the corresponding monitoring point at the power-off potential of -0.9V. That is, for the monitoring points with an average AC current density greater than or equal to the AC interference threshold, the preliminary low-level simulated current density at the power-off potential of -0.9V is obtained. For the other monitoring points, the power-off potential is still obtained as -0. The initial low-level simulated current density at 85V is obtained. The initial high-level simulated current density at the corresponding monitoring point with a de-energization potential of -1.2V is replaced with the initial high-level simulated current density at the corresponding monitoring point with a de-energization potential of -1.15V. That is, for monitoring points with an average AC current density greater than or equal to the AC interference pre-set value, the initial high-level simulated current density at a de-energization potential of -1.15V is obtained. For other monitoring points, the initial high-level simulated current density at a de-energization potential of -1.2V is still obtained. Finally, the monitoring point... ~ Preliminary low-level simulated current density ~ and preliminary high-level simulated current density ~ .

[0094] In steps S51 to S53, the AC stray current interference is evaluated. If the average AC current density at the monitoring point is greater than the threshold, it indicates that not only DC interference but also AC interference significantly affects the cathodic protection status of the pipeline. Therefore, in the subsequent step S80, the compliant potential range is adjusted according to the impact of AC interference to obtain the DC current density at both ends of the cathodic protection compliance range of the monitoring point under superimposed AC interference. This allows for the acquisition of the subsequent acceptable low-level preset current and acceptable high-level preset current, and / or ideal low-level preset current and ideal high-level preset current. As a result, the selection of the final target potentiostat preset current takes into account the impact of AC interference on the compliant potential range, ensuring that the cut-off potential at each point of the target pipeline reaches the optimal cathodic protection status under DC interference.

[0095] Steps S51 to S53 can be performed simultaneously with steps S40 to S80, or before step S40, or after step S80.

[0096] In some embodiments, prior to step S30, the pipeline maintains an electrical connection with multiple drainage devices installed along its route, which drain current from the pipeline. That is, during data measurement, the existing drainage system of the pipeline remains connected, and the drainage system continues to drain current from the pipeline, reducing the impact of stray current on the current potential on the pipeline. This allows for the acquisition of a preset current that satisfies the optimal cathodic protection effect in subsequent data calculations.

[0097] In some embodiments, in step S110, if the upper limit preset current is acceptable... Less than the acceptable lower limit preset current If the acceptable current range is empty, it indicates that the interference intensity is too strong and exceeds the control capability of the potentiostat. Under the existing drainage conditions, the preset current cannot be obtained, and the existing drainage facilities are insufficient and need to be further increased. At this time, drainage devices are added along the pipeline to increase the number of drainage devices along the pipeline. The added drainage devices drain the pipeline, and after the drainage work is completed, return to step S30 to obtain the curve and the boundary of the acceptable current range again, so as to select the preset current according to the effect of drainage. This provides a solution for the control of the potentiostat when the interference intensity is too strong.

[0098] In some embodiments, the monitoring points include a first monitoring point, a second monitoring point, a third monitoring point, a fourth monitoring point, a fifth monitoring point, a sixth monitoring point, a seventh monitoring point, and an eighth monitoring point;

[0099] The first monitoring point is located at the beginning of the target pipe section; the second monitoring point is located at the end of the target pipe section; the third monitoring point is located at the midpoint between the target potentiostat and the beginning of the target pipe section; the fourth monitoring point is located at the midpoint between the target potentiostat and the end of the target pipe section; the fifth monitoring point is the position where the power-off potential on the target pipe section is most positive when the cathodic protection is normal; the sixth monitoring point is the position where the power-off potential on the target pipe section is most negative when the cathodic protection is normal; the seventh monitoring point is the position where the target pipe section is most affected by DC interference; and the eighth monitoring point is the position where the target pipe section is most affected by AC interference.

[0100] The first to eighth monitoring points can fully reflect the power-off potential and DC current at various points in the target pipe section, providing more accurate data for subsequent curve acquisition and preset current boundary calculation, and further enabling the preset current adjustment of the potentiostat to be more accurate.

[0101] In some embodiments, the monitoring points further include a ninth monitoring point, a tenth monitoring point, an eleventh monitoring point, and a twelfth monitoring point. The ninth and tenth monitoring points are located on either side of the seventh monitoring point, and the eleventh and twelfth monitoring points are located on either side of the eighth monitoring point.

[0102] Around the two points with the strongest AC interference and the two points with the strongest DC interference, two more points with relatively strong interference are selected respectively. This allows the data measured at the monitoring points to more accurately reflect the effects of AC interference and DC interference, providing a more accurate data basis for subsequent curve acquisition and preset current boundary calculation, and further enabling the preset current adjustment of the potentiostat to be more accurate.

[0103] In some embodiments, the starting point of the target pipe segment is located at the midpoint between the target potentiostat and its upstream adjacent potentiostat, and the ending point of the target pipe segment is located at the midpoint between the target potentiostat and its downstream adjacent potentiostat, so that the selected target pipe segment is the part that the target potentiostat can fully influence. The target potentiostat operates according to the adjusted preset current, which can adjust the pipeline to the optimal cathodic protection state to the maximum extent.

[0104] In some embodiments, in step S70, the preset power-off potential is located within a set potential range, which is between -0.85V and -1.2V. The preset power-off potential includes -0.85V, -0.9V, -1.15V, and -1.2V. The selection of the preset power-off potential is aimed at the compliant potential range that reflects the optimal cathodic protection state under DC interference and the compliant potential range that reflects the optimal cathodic protection state under AC interference, making the subsequently obtained curves and preset current range boundaries more accurate.

[0105] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for adjusting the output of a potentiostat under stray current interference, characterized in that, The steps are as follows: S10: Take a section of the pipe connected to the target potentiostat as the target pipe section; S20: Select N monitoring points on the target pipe section, where N is a positive integer; S30: Adjustment begins; S40: Shut down all potentiostats connected to the pipeline; in case of DC interference, simultaneously monitor the monitoring points. ~ The test piece was measured multiple times for its first DC current density; S50: Monitoring points ~ The first DC current density corresponding to the inflow current of the test piece is set as the first inflow current density. and the first inflow current density Set to a positive value; set the monitoring point ~ The first DC current density corresponding to the outflow current of the test piece is set as the first outflow current density. and the first outflow current density Set to a negative value; S60: Calculate the monitoring points separately ~ The corresponding first inflow current density The average value of the monitoring points is obtained. ~ First average inflow current density ~ ; Calculate the monitoring points respectively ~ The corresponding first outflow current density The average value of the monitoring points is obtained. ~ First average outflow current density ~ ; S70: In the absence of DC interference, the target potentiostat operates in constant off-voltage mode and sets multiple preset off-voltages. Simultaneously, the target potentiostat measures the monitoring points while operating at each preset off-voltage. ~ The test DC current density and test power-off potential of the set test piece are obtained, and the current output current of the target potentiostat is acquired. S80: Monitoring points ~ The test DC current density and the test power-off potential are fitted to obtain the monitoring point. ~ The power outage potential-cathode current density curve; monitoring points ~ The power-off potential and the corresponding output current are fitted to obtain the monitoring point. ~ The power-off potential-output current curve; S90: Obtain monitoring points ~ Acceptable low-level preset current ~ And acceptable high preset current ~ ; S100: Acceptable low-level preset current ~ The maximum value in the range is used as the acceptable lower limit preset current. Acceptable high-level preset current ~ The minimum value in the set range is used as the acceptable upper limit preset current. ; S110: If the upper limit preset current is acceptable Current greater than the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the upper limit preset current. With acceptable lower limit preset current Between; if the upper limit preset current is acceptable Equal to the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the upper limit preset current. Or acceptable lower limit preset current ; Among them, the acquisition of monitoring points ~ Acceptable low-level preset current ~ The specific steps are as follows: According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary low-level simulated current density at a power-off potential of -0.85V ~ The initial low-level simulated current density will be used. ~ Each is compared with the corresponding first average outflow current density ~ Subtraction yields an acceptable low-bit analog current density. ~ Acceptable low analog current density ~ Through monitoring points ~ The power-off potential-cathode current density curve yields an acceptable low-level simulated power-off potential. ~ Acceptable low-level simulated power failure potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Acceptable low-level preset current ~ ; Acquire monitoring points ~ Acceptable high-level preset current ~ The specific steps are as follows: According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary high-level simulated current density at a power-off potential of -1.2V ~ The initial high-level simulated current density will be used to simulate the current density. ~ Each with the corresponding first average inflow current density ~ Subtraction yields an acceptable high-level analog current density. ~ Acceptable high analog current density ~ Through monitoring points ~ The power outage potential-cathode current density curve yields an acceptable high-level simulated power outage potential. ~ Acceptable high-level simulated power failure potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Acceptable high-level preset current ~ .

2. The method for adjusting the output of a potentiostat under stray current interference according to claim 1, characterized in that, Between step S30 and step S90, steps S41 to S44 are further included; S41: Turn off all potentiostats connected to the pipeline. Use the period of DC interference as the test period, and divide the test period into M equal window periods (M is a positive integer). Measure the monitoring points within each window period. ~ The second DC current density of the test piece; S42: Set the second DC current density corresponding to the current flowing into the test piece to the second current flowing into density. and the second inflow current density Set to a positive value; set the second DC current density corresponding to the outflow current of the test piece to the second outflow current density. and the second outflow current density Set to a negative value; S43: Calculate all second inflow current densities within the same window period. The average value is used to obtain the window period. ~ Second average inflow current density ~ ; Calculate the total second outflow current density within the same time window. The average value is used to obtain the window period. ~ Second average outflow current density ~ ; S44: The second average inflow current density ~ The maximum value in is set as the maximum inflow DC current density. The second average outflow current density ~ The maximum value in is set as the maximum outflow DC current density. .

3. The method for adjusting the output of a potentiostat under stray current interference according to claim 2, characterized in that, In step S90, monitoring points are further obtained. ~ Ideal low-level preset current ~ and ideal high-level preset current ~ ; In step S100, the ideal low-order preset current is further... ~ The maximum value in is used as the ideal lower limit preset current. Ideal high-level preset current ~ The minimum value in the range is used as the ideal upper limit preset current. ; Step S110 is replaced with: If the ideal upper limit preset current is... Current greater than the ideal lower limit preset current Then adjust the output current of the target potentiostat to the ideal upper limit preset current. With the ideal lower limit preset current Between; if the ideal upper limit preset current equal to the ideal lower limit preset current Then adjust the output current of the target potentiostat to the ideal upper limit preset current. Or ideal lower limit preset current If the ideal upper limit preset current Less than the ideal lower limit preset current And it can accept the upper limit preset current. ≥ Ideal lower limit preset current ≥ Acceptable lower limit preset current Then adjust the output current of the target potentiostat to the ideal lower limit preset current. ; If the ideal upper limit preset current Less than the ideal lower limit preset current Acceptable upper limit preset current ≥ Acceptable lower limit preset current And the ideal lower limit preset current Current greater than the acceptable upper limit preset Or less than the acceptable lower limit preset current Then adjust the output current of the target potentiostat to the acceptable upper limit preset current. ; Among them, the acquisition of monitoring points ~ Ideal low-level preset current ~ The specific steps are as follows: According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary low-level simulated current density at a power-off potential of -0.85V ~ The initial low-level simulated current density will be used. ~ Both are related to the maximum outflow DC current density Subtraction yields the ideal low-side analog current density. ~ ; to simulate ideal low-order current density ~ Through monitoring points ~ The power-off potential-cathode current density curve is used to obtain the ideal low-level simulated power-off potential. ~ The ideal low-level simulated power outage potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Ideal low-level preset current ~ ; Acquire monitoring points ~ Ideal high-level preset current ~ The specific steps are as follows: According to monitoring points ~ The power-off potential-cathode current density curve is obtained from the monitoring point. ~ Preliminary high-level simulated current density at a power-off potential of -1.2V ~ The initial high-level simulated current density will be used to simulate the current density. ~ Both are related to the maximum inflow DC current density Subtraction yields the ideal high-level analog current density. ~ ; to simulate ideal high-level current density ~ Through monitoring points ~ The power-off potential-cathode current density curve is used to obtain the ideal high-level simulated power-off potential. ~ The ideal high-level simulated power outage potential ~ According to the monitoring points ~ The power-off potential-output current curve is used to obtain the monitoring point. ~ Ideal high-level preset current ~ .

4. The method for adjusting the output of a potentiostat under stray current interference according to any one of claims 1 to 3, characterized in that, Between step S30 and step S90, steps S51 to S53 are further included; S51: Close all potentiostats connected to the pipeline and simultaneously monitor the points. ~ The AC current density of the test piece was measured multiple times. S52: Calculate the monitoring points separately ~ The average value of the alternating current density is obtained. ~ ; S53: If the average AC current density of the monitoring point is greater than or equal to the AC interference threshold, then in step S90, the preliminary low-level simulated current density of the corresponding monitoring point at the power-off potential of -0.85V is replaced with the preliminary low-level simulated current density of the corresponding monitoring point at the power-off potential of -0.9V; and the preliminary high-level simulated current density of the corresponding monitoring point at the power-off potential of -1.2V is replaced with the preliminary high-level simulated current density of the corresponding monitoring point at the power-off potential of -1.15V.

5. The method for adjusting the output of a potentiostat under stray current interference according to any one of claims 1 to 3, characterized in that, Before step S30, the pipeline maintains an electrical connection with multiple drainage devices installed along its route, which drain water from the pipeline.

6. The method for adjusting the output of a potentiostat under stray current interference according to claim 5, characterized in that, In step S110, if the upper limit preset current is acceptable... Less than the acceptable lower limit preset current If so, a drainage device is added along the pipeline. After the added drainage device drains the pipeline, the process returns to step S30.

7. The method for adjusting the output of a potentiostat under stray current interference according to any one of claims 1 to 3, characterized in that, The monitoring points include the first monitoring point, the second monitoring point, the third monitoring point, the fourth monitoring point, the fifth monitoring point, the sixth monitoring point, the seventh monitoring point, and the eighth monitoring point; The first monitoring point is located at the beginning of the target pipe section; the second monitoring point is located at the end of the target pipe section; the third monitoring point is located at the midpoint between the target potentiostat and the beginning of the target pipe section; the fourth monitoring point is located at the midpoint between the target potentiostat and the end of the target pipe section; the fifth monitoring point is the position where the power-off potential on the target pipe section is most positive when the cathodic protection is normal; the sixth monitoring point is the position where the power-off potential on the target pipe section is most negative when the cathodic protection is normal; the seventh monitoring point is the position where the target pipe section is most affected by DC interference; and the eighth monitoring point is the position where the target pipe section is most affected by AC interference.

8. The method for adjusting the output of a potentiostat under stray current interference according to claim 7, characterized in that, The monitoring points further include the ninth monitoring point, the tenth monitoring point, the eleventh monitoring point, and the twelfth monitoring point; The ninth and tenth monitoring points are located on either side of the seventh monitoring point, and the eleventh and twelfth monitoring points are located on either side of the eighth monitoring point.

9. The method for adjusting the output of a potentiostat under stray current interference according to claim 7, characterized in that, The starting point of the target pipe segment is located at the midpoint between the target potentiostat and its upstream adjacent potentiostat, and the ending point of the target pipe segment is located at the midpoint between the target potentiostat and its downstream adjacent potentiostat.

10. The method for adjusting the output of a potentiostat under stray current interference according to claim 1, characterized in that, In step S70, the preset power-off potential is within a set potential range, which is between -0.85V and -1.2V. The preset power-off potential includes -0.85V, -0.9V, -1.15V, and -1.2V.

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