Sacrificial anode state monitoring and life prediction method for ship cathode protection

Abstract

The invention discloses a sacrificial anode state monitoring and service life prediction method for ship cathode protection, belongs to the technical field of sacrificial anode state monitoring and service life prediction, and solves the problems that the anode protection current generated by a sacrificial anode can be reduced to a pA level at the initial stage of corrosion, and the service life of the sacrificial anode cannot be predicted under the condition that strong interference exists in an actual environment. The performance of an existing sacrificial anode detection technology cannot meet the high-precision detection requirement, so that the requirement for predicting the service life of a sacrificial anode cannot be met, and the requirement for judging the early corrosion trend cannot be met. The method comprises the steps that a plurality of node monitoring detection boxes are used for detecting the anode potential of a sacrificial anode connected with a cathode, and protection current between the cathode and the sacrificial anode is detected in a multi-range mode and stored; and the monitoring substation is used for monitoring the state of the sacrificial anode and predicting the service life of the sacrificial anode based on the anode potential and the protection current detected by the plurality of node monitoring detection boxes. The method is used for sacrificial anode state monitoring and life prediction.

Description

Technical Field

[0001] The invention discloses a sacrificial anode state monitoring and life prediction method for ship cathode protection, which is used for sacrificial anode state monitoring and life prediction and belongs to the technical field of sacrificial anode state monitoring and life prediction. Background Art

[0002] Modern military communication systems usually use fast frequency modulation and spread spectrum to improve anti-interference capabilities. At this time, the transceiver operates at a wider frequency, such as 108M to 400M. In frequency hopping radio networking, the radio frequency interference caused by the close distance between transceivers will cause a significant deterioration in radio performance.

[0003] The sacrificial anode protection method is common in the cathodic protection of ships. CN202110858616.2 A sacrificial anode online monitoring and life prediction device for ship ballast tanks discloses that by collecting the current and potential at intervals for a long time, the line graph and line graph can be displayed on the display screen, so that personnel can understand the status of the sacrificial anode, and after calculation by the device, the remaining mass of the sacrificial anode and the remaining life of the sacrificial anode can be displayed on the display screen, providing guidance for personnel to monitor the working status of the sacrificial anode and replace the sacrificial anode in time. The device can achieve long-term monitoring and reduce the workload of personnel. By setting the power-off flag, the device can save the existing sacrificial anode data after an accidental power outage, and continue to monitor according to the original data after reconnection. It can cope with data collection suspension caused by unexpected factors such as power outages and freezes. The device is highly intelligent and reliable, which is very beneficial to the development of sacrificial anode technology for ship ballast tanks. However, there are the following technical problems:

[0004] In the early stages of corrosion, the anodic protection current generated by the sacrificial anode can be as low as pA level. In the presence of strong interference in actual environments (such as strong interference in ship applications), the performance of existing sacrificial anode detection technology cannot meet the requirements of high-precision detection, and thus cannot meet the needs of sacrificial anode life prediction and early corrosion trend determination. Summary of the invention

[0005] The purpose of the present invention is to provide a method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of ships, so as to solve the problem that in the early stage of corrosion, the anodic protection current generated by the sacrificial anode can be as low as pA level. In the presence of strong interference in the actual environment, the performance of the existing sacrificial anode detection technology cannot adapt to the high-precision detection requirements, and thus cannot meet the needs of sacrificial anode life prediction and the needs of early corrosion trend judgment.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship comprises the following steps:

[0008] The multiple node monitoring boxes are respectively used to detect the anode potential of the sacrificial anode connected to the cathode, and the protection current between the cathode and the sacrificial anode is detected and stored through multiple ranges;

[0009] The monitoring substation is used for the steps of monitoring the sacrificial anode status and predicting the life span based on the anode potential and protection current detected by multiple node monitoring boxes.

[0010] Furthermore, the node monitoring detection box includes a shell, a current detection module and a potential detection module arranged in the shell;

[0011] The current detection module includes a current sensor, a multi-range amplifier connected to the current sensor, an AD sampling circuit A connected to the output end of the multi-range amplifier, a filter circuit A connected to the output end of the AD sampling circuit A, a 32-bit single-chip computer A connected to the output end of the filter circuit A, a non-volatile memory A connected to the 32-bit single-chip computer A for storing a protection current output by the 32-bit single-chip computer A, and a 485 converter A connected to the 32-bit single-chip computer A for transmitting the protection current stored in the detected non-volatile memory A to a monitoring substation. The 32-bit single-chip computer A receives a query message from the monitoring substation, and determines whether the current signal output by any range of the multi-range amplifier is within the corresponding range, and controls the multi-range amplifier to select the corresponding range gain according to the judgment result. When sampling is required, the 32-bit single-chip computer A controls the power supply to supply power to the multi-range amplifier, the AD sampling circuit A, the non-volatile memory A and the 485 converter A.

[0012] The potential detection module includes an amplifier, an AD sampling circuit B connected to the output end of the amplifier, a filter circuit B connected to the output end of the AD sampling circuit B, a 32-bit single-chip microcomputer B connected to the output end of the filter circuit B, a non-volatile memory B connected to the 32-bit single-chip microcomputer B for storing the anode potential output by the 32-bit single-chip microcomputer B, and a 485 converter B connected to the 32-bit single-chip microcomputer B for transmitting the detected anode potential stored in the non-volatile memory B to the monitoring substation. When sampling is required, the 32-bit single-chip microcomputer B controls the power supply to the amplifier, the AD sampling circuit B, the non-volatile memory B and the 485 converter B.

[0013] Further, the multi-range amplifier includes at least one group of gain range circuits A for performing gain on the protection current of 10pA-25uA, and one group of gain range circuits B for performing gain on the protection current of 20uA-2mA;

[0014] and a switch for switching the gain of each range in the gain range circuit A and the gain range circuit B; or

[0015] The multi-range amplifier includes at least one group of gain range circuits A for gaining the protection current of 10pA-25uA, one group of gain range circuits B for gaining the protection current of 20uA-2mA, and one group of gain range circuits C for gaining the protection current of more than 2mA;

[0016] And a switch for switching the gain of each range in the gain range circuit A, the gain range circuit B and the gain range circuit C.

[0017] Further, the gain range circuit A includes two relay switches K3 and relay switch K2, and transimpedance amplifiers A and B respectively connected to the two relay switches K3 and K2 for performing gain on the protection current within the intervals of 10pA-16.66nA and 16nA-25uA;

[0018] When the gain range circuit B is one channel, it includes a relay switch K1, a sampling resistor connected to the relay switch K1, which converts the protection current of 20uA-2mA into a voltage, and an inverting amplifier C which amplifies the converted voltage; or

[0019] When the gain range circuit B is two-way, it includes a relay switch K1, a sampling resistor connected to the relay switch K1 and converting the protection current of 1mA-200mA into a voltage, an inverting amplifier C for amplifying the converted voltage, and an inverting amplifier D connected to the inverting amplifier C and gaining the voltage within the interval of 20uA-2mA;

[0020] The gain range circuit C includes a relay switch K4, a current sensor connected to the relay switch K4 and converting a current above 2 mA into a voltage, and an inverting amplifier E for amplifying the voltage converted by the current sensor.

[0021] Furthermore, the transimpedance amplifier uses an ultra-precision operational amplifier whose input bias current I bs and offset current I os are both at fA level.

[0022] Furthermore, the AD sampling circuit A adopts a 16-bit AD converter.

[0023] Furthermore, the 32-bit single-chip microcomputer A and the 32-bit single-chip microcomputer B have a system programming (ISP) function.

[0024] Furthermore, the housing is an IP65 protective housing, and a touch screen is provided on the housing;

[0025] The node monitoring and detection box adopts a Linux operating system;

[0026] The node monitoring and detection box also includes a failure model for warning of the impending failure of the sacrificial anode metal. That is, different margin values ​​are set according to different sacrificial anode metal materials and seawater conditions. The monitoring substation converts the data of the current detection module and the potential detection module into the consumption of the sacrificial anode. When the margin value calculated based on the total mass and consumption of the sacrificial anode is lower than the set value, it is fed back to the corresponding node monitoring and detection box for early warning.

[0027] Furthermore, the monitoring substation obtains the detected protection current and anode potential from each node monitoring box by querying via RS485;

[0028] A monitoring substation is configured with no more than 20 node monitoring boxes;

[0029] The monitoring substation uses polling to read the detected protection current and anode potential from each monitoring box or sets a sampling interval to read the detected protection current and anode potential.

[0030] Furthermore, the monitoring substation predicts the life of the sacrificial anode based on the detected anode potential and protection current. The prediction steps are:

[0031] First, determine whether the current anode potential has changed compared to the anode potential when the sacrificial anode is not corroded;

[0032] When the anode potential changes, it means that the sacrificial anode has corroded. The formula for state monitoring and life prediction of the sacrificial anode is:

[0033]

[0034] M 消耗 =KQ 消耗

[0035] M 余量 =MM 消耗

[0036] M 余量 With M 预警 Compare, M. 余量 ≤M 预警 Timely warning;

[0037] Among them, Q 消耗 It represents the charge consumed by the sacrificial anode, which is the integral of the protection current I over the time t. t0 and t1 represent the time t0 and t1 respectively. K represents the proportional constant. The electrochemical equivalent is different according to the sacrificial anode material. M 消耗 represents the mass consumed by the sacrificial anode, M represents the total mass of the sacrificial anode, M 余量 Represents the remaining mass of the sacrificial anode.

[0038] Compared with the prior art, the advantages of the present invention are:

[0039] 1. The present invention measures the protection current generated by the sacrificial anode through multiple ranges. In an actual environment with strong interference, it can measure the current as low as pA level at the initial stage of corrosion, which is suitable for the high-precision detection requirements of sacrificial anode detection technology performance, so as to accurately predict the life of the sacrificial anode, so as to facilitate the determination of the early corrosion trend. Under the detection of the invention at a level as low as several pA, its detection accuracy is still more than 4% better than the existing technology;

[0040] Second, the present invention is used for monitoring the real-time use status of sacrificial anodes, with high detection data accuracy, and has a built-in failure model based on the electrochemical parameters of sacrificial anodes of different materials, which can be used for early warning when the remaining amount of the sacrificial anode is lower than the set value;

[0041] 3. The transimpedance amplifier in the present invention uses an ultra-precision operational amplifier with input bias current Ibs and offset current Ios at fA level, which ensures that the test accuracy and current noise are sufficiently small. The AD sampling circuit A uses a 16-bit AD converter for digital filtering processing, so that the effective resolution of the protection current conversion reaches about 0.3mV, and the gain of the transimpedance amplifier is controlled according to the strength of the current signal, which can achieve a large dynamic range change;

[0042] 4. The circuit of the node monitoring and detection box in the present invention adopts a low-power design. Except for the 32-bit single-chip microcomputer A and the 32-bit single-chip microcomputer B circuits which are powered for a long time, the other circuits are usually in a standby state. When sampling is required, the 32-bit single-chip microcomputer A and the 32-bit single-chip microcomputer B will control the power supply to them, and complete the data sampling and local storage. When working, the power consumption of the whole circuit is about 10-15W. When on standby, only the 32-bit single-chip microcomputer A and the 32-bit single-chip microcomputer B are powered on, and the 32-bit single-chip microcomputer A and the 32-bit single-chip microcomputer B are in sleep mode, so the power consumption is about 10-15W. The circuit power consumption is very low, less than 1W, because the sampling time is relatively short. In the case of no communication with the monitoring substation, it only takes 10-100mS, and the sampling interval is generally longer. Taking 10S as an example, the maximum average power consumption is (15*0.1+1*9.9) / 10=1.14W. Therefore, in the case of very low circuit power consumption (circuit power consumption does not exceed 5W), there is no need to consider special heat dissipation measures. The circuit can be processed by potting and other processes to solve the corrosion problem in harsh environments and ensure the reliability of circuit operation.

[0043] 5. The present invention adopts AD sampling circuit A and AD sampling circuit B, and performs filtering through filtering circuit A and filtering circuit B, so as to deal with various types of interference that may be encountered in a targeted manner.

[0044] 6. The multi-range amplifier in the present invention is a tunable circuit with resistance to co-site interference. It has a wide frequency range and good out-of-band suppression capability. By replacing individual components, it can be applied to other application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a schematic diagram of the framework of the present invention;

[0047] Figure 2 It is a schematic diagram of the framework of the current detection module in the present invention;

[0048] Figure 3 Schematic diagram of the framework of the potential detection module in the present invention;

[0049] Figure 4 A circuit diagram of a multi-range amplifier including three ranges in the present invention;

[0050] Figure 5 A circuit diagram of a multi-range amplifier including four ranges in the present invention;

[0051] Figure 6 The circuit diagram of the multi-range amplifier including five ranges in the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0054] In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0055] In addition, the terms “first”, “second”, “third”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0056] In addition, the terms "horizontal", "vertical", "overhanging", etc. do not mean that the components must be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0057] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connection", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Example 1

[0059] In order to solve the problem that the anodic protection current generated by the sacrificial anode can be as low as pA level in the early stage of corrosion, the existing sacrificial anode detection technology performance cannot meet the high-precision detection requirements in the presence of strong interference in the actual environment, and thus cannot meet the needs of sacrificial anode life prediction and early corrosion trend determination. Figure 1 As shown, a sacrificial anode state monitoring and life prediction method for cathodic protection of ships is provided, comprising the following steps:

[0060] The steps of multiple node monitoring boxes being used to detect the anode potential of the sacrificial anode connected to the cathode, and detecting the protection current between the cathode and the sacrificial anode through multiple ranges and storing the detected current; the step of the monitoring substation being used to monitor the state of the sacrificial anode and predict the life of the sacrificial anode based on the anode potential and protection current detected by the multiple node monitoring boxes, wherein the monitoring substation obtains the detected protection current and anode potential from each node monitoring box by querying via RS485, the monitoring substation reads the detected protection current and anode potential from each monitoring box by polling or sets a sampling interval to read the detected protection current and anode potential, and one monitoring substation can be configured with up to 20 node monitoring boxes.

[0061] In practice, the anode potential of the sacrificial anode connected to the reference electrode is detected by a node monitoring box, and the protection current of the sacrificial anode is detected and stored through multiple ranges. The monitoring substation obtains the detected protection current and anode potential from each node monitoring box by querying through RS485. The monitoring substation reads the detected protection current and anode potential from each monitoring box by polling or sets a sampling interval to read the detected protection current and anode potential, and predicts the life of the sacrificial anode through the prediction model in the monitoring substation. This embodiment measures the protection current generated by the sacrificial anode through multiple ranges. In an actual environment with strong interference, it can measure the current as low as pA level in the early stage of corrosion, which is adapted to the high-precision detection requirements of the sacrificial anode detection technology performance, so that the life of the sacrificial anode can be accurately predicted, so as to facilitate the judgment of the early corrosion trend. Under the detection of the invention at a level as low as several pA, its detection accuracy is still more than 4% better than the prior art.

[0062] Example 2

[0063] On the basis of Example 1, the node monitoring detection box comprises a shell, a current detection module and a potential detection module arranged in the shell;

[0064] The current detection module includes a current sensor, a multi-range amplifier connected to the current sensor, an AD sampling circuit A connected to the output end of the multi-range amplifier, a filter circuit A connected to the output end of the AD sampling circuit A, a 32-bit single-chip microcomputer A connected to the output end of the filter circuit A, a non-volatile memory A connected to the 32-bit single-chip microcomputer A for storing a protection current output by the 32-bit single-chip microcomputer A, and a 485 converter A connected to the 32-bit single-chip microcomputer A for transmitting the protection current stored in the detected non-volatile memory A to a monitoring substation. The 32-bit single-chip microcomputer A receives a query message from the monitoring substation, and determines whether the current signal output by any range of the multi-range amplifier is within the corresponding range, and controls the multi-range amplifier to select the corresponding range gain according to the judgment result. When sampling is required, the 32-bit single-chip microcomputer A controls the power supply to supply power to the multi-range amplifier, the AD sampling circuit A, the non-volatile memory A and the 485 converter A to achieve low power consumption power supply;

[0065] The potential detection module includes an amplifier, an AD sampling circuit B connected to the output end of the amplifier, a filter circuit B connected to the output end of the AD sampling circuit B, a 32-bit single-chip microcomputer B connected to the output end of the filter circuit B, a non-volatile memory B connected to the 32-bit single-chip microcomputer B for storing the anode potential output by the 32-bit single-chip microcomputer B, and a 485 converter B connected to the 32-bit single-chip microcomputer B for transmitting the detected anode potential stored in the non-volatile memory B to the monitoring substation. When sampling is required, the 32-bit single-chip microcomputer B controls the power supply to the amplifier, the AD sampling circuit B, the non-volatile memory B and the 485 converter B to achieve low power supply.

[0066] The 32-bit single-chip microcomputer A and the 32-bit single-chip microcomputer B have a system programming (ISP) function. Of course, the single-chip microcomputer may also use a single-chip microcomputer of other bits.

[0067] The shell of each node monitoring and detection box is an IP65 protective shell. The shell has been treated with anti-corrosion and anti-rust, and can adapt to harsh operating environments. A touch screen is provided on the shell. The node monitoring and detection box adopts a Linux operating system, and the built-in sacrificial anode failure model can select different model parameters according to different sacrificial anode materials and seawater conditions.

[0068] In practice, when performing protection current detection, if the protection current does not exceed 200mA, at this time, the protection current directly passes through any range in the multi-range amplifier (that is, any range can be selected at any time), and the 32-bit single-chip microcomputer A detects whether the protection current is within the detection range of the corresponding range. If not, the range circuit is closed, and the 32-bit single-chip microcomputer A controls the multi-range amplifier to select the corresponding range for current detection. Otherwise, the protection current is detected in this range, amplified by the multi-range amplifier, and then processed by the AD sampling circuit A and the filter circuit A in turn. The result of the filtering process is controlled by the 32-bit single-chip microcomputer A to be stored in the non-volatile memory A, and the 32-bit single-chip microcomputer A then transmits the protection current stored in the non-volatile memory A to the monitoring substation through the 485 converter A; if the protection current exceeds 200mA, at this time, it needs to be processed by a current sensor (such as a Hall sensor) before entering the multi-range amplifier.

[0069] In practice, when the anode potential is detected, the anode potential passes through the amplifier and then is processed by the AD sampling circuit B and the filter circuit B in sequence. The current after filtering is controlled by the 32-bit microcontroller B and stored in the non-volatile memory B. The 32-bit microcontroller B then transmits the anode potential stored in the non-volatile memory B to the monitoring substation through the 485 converter B.

[0070] The circuit of the node monitoring box adopts a low-power design. Except for the 32-bit MCU A and 32-bit MCU B circuits, which are powered for a long time, other circuits are usually in standby mode. When sampling is required, the 32-bit MCU A and 32-bit MCU B will control the power supply and complete data sampling and local storage. The power consumption of the entire circuit is about 10-15W when working. When on standby, only the 32-bit MCU A and 32-bit MCU B are powered, and the 32-bit MCU A and 32-bit MCU B are in sleep mode. The power consumption of the circuit is very low, less than 1W. Because the sampling time is relatively short, it only takes 10-100mS without communicating with the monitoring substation. The sampling interval is generally longer, taking 10S as an example, the maximum average power consumption is (15*0.1+1*9.9) / 10=1.14W. Therefore, in the case of very low power consumption of the circuit, there is no need to consider special heat dissipation measures. The circuit can be processed by potting and other processes to solve the corrosion problem in harsh environments and ensure the reliability of circuit operation.

[0071] Example 3

[0072] On the basis of Example 2, the multi-range amplifier includes at least one group of gain range circuits A for gaining the protection current of 10pA-25uA, and one group of gain range circuits B for gaining the protection current of 20uA-2mA;

[0073] and a switch for switching the gain of each range in the gain range circuit A and the gain range circuit B; or

[0074] The multi-range amplifier includes at least one group of gain range circuits A for gaining the protection current of 10pA-25uA, one group of gain range circuits B for gaining the protection current of 20uA-2mA, and one group of gain range circuits C for gaining the protection current of more than 2mA;

[0075] And a switch for switching the gain of each range in the gain range circuit A, the gain range circuit B and the gain range circuit C.

[0076] like Figure 4 As shown, the gain range circuit A in the multi-range amplifier includes two relay switches K3 and relay switch K2, and transimpedance amplifiers A and B respectively connected to the two relay switches K3 and K2 for performing gain on the current (protection current) within the intervals of 10pA-100nA and 50nA-100uA;

[0077] When the gain range circuit B is one channel, it includes a relay switch K1, a sampling resistor connected to the relay switch K1, which converts the current of 50uA-200mA into a voltage, and an inverting amplifier C which amplifies the converted voltage;

[0078] like Figure 4 As shown, the switch controls 3 routes.

[0079] or

[0080] like Figure 5 As shown, the gain range circuit A in the multi-range amplifier includes two relay switches K3 and relay switch K2, and a transimpedance amplifier A and a transimpedance amplifier B respectively connected to the two relay switches K3 and K2 for performing gain on the current within the intervals of 10pA-16.66nA and 16nA-25uA; when the gain range circuit B is two-way, it includes a relay switch K1, a sampling resistor connected to the relay switch K1 for converting the current of 1mA-200mA into a voltage and an inverting amplifier C for amplifying the converted voltage, and an inverting amplifier D connected to the inverting amplifier C for performing gain on the voltage within the interval of 20uA-2mA;

[0081] like Figure 5 As shown, the switching switch controls 4 channels, and the switching of two channels in the gain range circuit B is achieved by the switching switch.

[0082] like Figure 6 As shown, in Figure 5Based on the above, the gain range circuit C is added, and the gain range circuit C includes a relay switch K4, a current sensor connected to the relay switch K4 and converting a current above 2mA into a voltage, and an inverting amplifier E that amplifies the voltage converted by the current sensor.

[0083] like Figure 6 As shown, the switch controls 5 channels.

[0084] In practice, other gain ranges can also be set as needed.

[0085] In the embodiment, whether it is a sampling resistor or a current sensor, the current is converted into a voltage and then the voltage is amplified by gain. The multi-range amplifier outputs a voltage, which corresponds to the current to be measured, so as to obtain the protection current through the 32-bit single-chip microcomputer A. Taking the sampling resistor R as an example, the current to be measured is I, and the sampling resistor converts the protection current into a voltage U=I*R. The amplification factor of the multi-range amplifier is A, and the output voltage Uout=A*U. The 32-bit single-chip microcomputer A will calculate the corresponding protection current according to the output voltage Uout and the given program for calculating the protection current, and then cut the range according to the protection current; and in the detection, if the result after filtering is the protection current, it is directly controlled by the 32-bit single-chip microcomputer A and stored in the non-volatile memory A. If it is a voltage, it is directly converted by the 32-bit single-chip microcomputer A into the protection current and then stored in the non-volatile memory A.

[0086] The transimpedance amplifier uses an ultra-precision operational amplifier with input bias current Ibs and offset current Ios at the fA level. The single-chip computer determines the current current size according to the sampling value, and then controls relays K1, K2 and K3, and cooperates with KO to select the appropriate range. The AD sampling circuit A uses a 16-bit AD converter. The transimpedance amplifier uses an ultra-precision operational amplifier with input bias current Ibs and offset current Ios at the fA level, which ensures that the test accuracy and current noise are small enough. The AD sampling circuit A uses a 16-bit AD converter for digital filtering processing, so that the effective resolution of the protection current conversion reaches about 0.3mV, and the gain of the transimpedance amplifier is controlled according to the strength of the current signal, which can achieve a large dynamic range change.

[0087] In the actual use environment, there may be various interferences and noises, and it is necessary to filter the signal to remove interference and noise. If hardware circuit processing is used and analog filtering is performed after the analog signal is amplified, it is difficult to determine the filter form, order and other related parameters because the interference characteristics are not known in advance. There is a high risk of modifying the hardware circuit after it is put into use. In particular, for time-varying interference forms, a filtering processing method with time-varying parameters is also used to achieve the best effect. This case considers digital filtering of the signal after sampling to specifically deal with various types of interference that may be encountered.

[0088] The node monitoring and detection box in the present invention also includes a failure model for warning of the imminent failure of the sacrificial anode metal, that is, different margin values ​​are set according to different sacrificial anode metal materials and seawater conditions. The monitoring substation converts the data of the current detection module and the potential detection module into the consumption of the sacrificial anode. When the margin value calculated based on the total mass and consumption of the sacrificial anode is lower than the set value, it is fed back to the corresponding node monitoring and detection box for warning.

[0089] The monitoring substation predicts the life of the sacrificial anode based on the detected anode potential and protection current.

[0090] Dissimilar metals have different activities, so there is a potential difference between them when they come into contact. Ship protection uses this principle, connecting the active metal (i.e. sacrificial anode) with the hull metal (i.e. cathode). When corrosion occurs, the metal of the sacrificial anode is consumed and the metal of the cathode is protected, that is, the anode is sacrificed to protect the cathode. The sacrificial anode has different metal types and limited mass. In addition, its location and environment are different, and the corrosion rate varies. We need to know where the corrosion occurs and how much anode metal is consumed in order to carry out subsequent work.

[0091] In this case, the potential of the metal of the sacrificial anode is detected by detecting the protective current between the metal of the sacrificial anode and the metal of the cathode. When corrosion occurs, the potential on the anode will change significantly, and based on this change, it is known that corrosion has occurred (the hull is covered with polymer materials, corrosion occurs after the material is damaged, and the anode potential changes significantly). In addition, when corrosion occurs, a protective current will be formed between the anode and the cathode. By detecting the protective current I and integrating the protective current over time t, the charge Q consumed by the anode can be known. Q is converted into mass through a certain relationship, and the amount of metal consumed at the sacrificial anode can be known. A warning value is set, and a warning is issued when the metal residue of the sacrificial anode is lower than the warning value.

[0092] Before time t0, the polymer material on the hull surface is not damaged, corrosion has not occurred, there is a potential difference between the sacrificial anode and the cathode but no current (this potential is the anode potential mentioned above), at time t0, the polymer material is damaged, corrosion occurs, and the sacrificial anode potential will change significantly. According to this change, corrosion has occurred. At this time, there is current between the sacrificial anode and the cathode, and the state monitoring and life prediction of the sacrificial anode can be carried out. The prediction steps are:

[0093] First, determine whether the current anode potential has changed compared to the anode potential when the sacrificial anode is not corroded;

[0094] When the anode potential changes, it means that the sacrificial anode has corroded. The formula for state monitoring and life prediction of the sacrificial anode is:

[0095]

[0096] M 消耗 =KQ 消耗

[0097] M 余量 =MM 消耗

[0098] M 余量 With M 预警 Compare, M. 余量 ≤M 预警 Timely warning;

[0099] Among them, Q 消耗 It represents the charge consumed by the sacrificial anode, which is the integral of the protection current I over the time t. t0 and t1 represent the time t0 and t1 respectively. K represents the proportional constant. The electrochemical equivalent is different according to the sacrificial anode material. M 消耗 represents the mass consumed by the sacrificial anode, M represents the total mass of the sacrificial anode, M 余量 represents the residual mass of the sacrificial anode, and I(t) represents the function of the protection current I with respect to time t.

[0100] In the cathodic protection of ships, the metal of the sacrificial anode is consumed. The status monitoring of the sacrificial anode is to monitor how much metal of the sacrificial anode is consumed, and the predicted life is the surplus.

[0101] In summary, the present invention can monitor the state of sacrificial anode metal. In the cathodic protection of ships, the sacrificial anode metal is consumed. Anode state monitoring is to monitor how much anode metal is consumed and predict its lifespan. The amount of sacrificial anode metal consumed is characterized by current and potential.

Claims

1. A method for monitoring the state and predicting the life of sacrificial anodes for cathodic protection of ships, characterized in that: The steps include: The multiple node monitoring boxes are respectively used to detect the anode potential of the sacrificial anode connected to the cathode, and the protection current between the cathode and the sacrificial anode is detected and stored through multiple ranges; The monitoring substation is used for the steps of monitoring the sacrificial anode status and predicting the life span based on the anode potential and protection current detected by multiple node monitoring boxes.

2. The method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to claim 1, characterized in that: The node monitoring detection box includes a shell, a current detection module and a potential detection module arranged in the shell; The current detection module includes a current sensor, a multi-range amplifier connected to the current sensor, an AD sampling circuit A connected to the output end of the multi-range amplifier, a filter circuit A connected to the output end of the AD sampling circuit A, a 32-bit single-chip computer A connected to the output end of the filter circuit A, a non-volatile memory A connected to the 32-bit single-chip computer A for storing a protection current output by the 32-bit single-chip computer A, and a 485 converter A connected to the 32-bit single-chip computer A for transmitting the protection current stored in the detected non-volatile memory A to a monitoring substation. The 32-bit single-chip computer A receives a query message from the monitoring substation, and determines whether the current signal output by any range of the multi-range amplifier is within the corresponding range, and controls the multi-range amplifier to select the corresponding range gain according to the judgment result. When sampling is required, the 32-bit single-chip computer A controls the power supply to supply power to the multi-range amplifier, the AD sampling circuit A, the non-volatile memory A and the 485 converter A. The potential detection module includes an amplifier, an AD sampling circuit B connected to the output end of the amplifier, a filter circuit B connected to the output end of the AD sampling circuit B, a 32-bit single-chip microcomputer B connected to the output end of the filter circuit B, a non-volatile memory B connected to the 32-bit single-chip microcomputer B for storing the anode potential output by the 32-bit single-chip microcomputer B, and a 485 converter B connected to the 32-bit single-chip microcomputer B for transmitting the detected anode potential stored in the non-volatile memory B to the monitoring substation. When sampling is required, the 32-bit single-chip microcomputer B controls the power supply to the amplifier, the AD sampling circuit B, the non-volatile memory B and the 485 converter B.

3. The method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to claim 2, characterized in that: The multi-range amplifier includes at least one group of gain range circuits A for performing gain on the protection current of 10pA-25uA, and one group of gain range circuits B for performing gain on the protection current of 20uA-2mA; and a switch for switching the gain of each range in the gain range circuit A and the gain range circuit B; or The multi-range amplifier includes at least one group of gain range circuits A for gaining the protection current of 10pA-25uA, one group of gain range circuits B for gaining the protection current of 20uA-2mA, and one group of gain range circuits C for gaining the protection current of more than 2mA; And a switch for switching the gain of each range in the gain range circuit A, the gain range circuit B and the gain range circuit C.

4. The method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to claim 3, characterized in that: The gain range circuit A comprises two relay switches K3 and a relay switch K2, and a transimpedance amplifier A and a transimpedance amplifier B respectively connected to the two relay switches K3 and K2 for performing gain on the protection current within the intervals of 10pA-16.66nA and 16nA-25uA; When the gain range circuit B is one channel, it includes a relay switch K1, a sampling resistor connected to the relay switch K1, which converts the protection current of 20uA-2mA into a voltage, and an inverting amplifier C which amplifies the converted voltage; or When the gain range circuit B is two-way, it includes a relay switch K1, a sampling resistor connected to the relay switch K1 and converting the protection current of 1mA-200mA into a voltage, an inverting amplifier C for amplifying the converted voltage, and an inverting amplifier D connected to the inverting amplifier C and gaining the voltage within the interval of 20uA-2mA; The gain range circuit C includes a relay switch K4, a current sensor connected to the relay switch K4 and converting a current above 2 mA into a voltage, and an inverting amplifier E for amplifying the voltage converted by the current sensor.

5. The method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to claim 4, characterized in that: The transimpedance amplifier uses an ultra-precision operational amplifier whose input bias current Ibs and offset current Ios are both at the fA level.

6. The method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to claim 5, characterized in that: The AD sampling circuit A adopts a 16-bit AD converter.

7. The method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to claim 6, characterized in that: The 32-bit single-chip microcomputer A and the 32-bit single-chip microcomputer B have a system programming (ISP) function.

8. A method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to any one of claims 2 to 7, characterized in that: The housing is an IP65 protective housing, and a touch screen is provided on the housing; The node monitoring and detection box adopts the Linux operating system; The node monitoring and detection box also includes a failure model for warning of the impending failure of the sacrificial anode metal. That is, different margin values ​​are set according to different sacrificial anode metal materials and seawater conditions. The monitoring substation converts the data of the current detection module and the potential detection module into the consumption of the sacrificial anode. When the margin value calculated based on the total mass and consumption of the sacrificial anode is lower than the set value, it is fed back to the corresponding node monitoring and detection box for early warning.

9. A method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to any one of claims 1 to 7, characterized in that: The monitoring substation obtains the protection current and anode potential detected from each node monitoring box by querying via RS485; A monitoring substation is configured with no more than 20 node monitoring boxes; The monitoring substation uses polling to read the detected protection current and anode potential from each monitoring box or sets a sampling interval to read the detected protection current and anode potential.

10. A method for monitoring the state and predicting the life of a sacrificial anode for cathodic protection of a ship according to claims 1-7, characterized in that: The monitoring substation predicts the life of the sacrificial anode based on the detected anode potential and protection current. The prediction steps are as follows: First, determine whether the current anode potential has changed compared to the anode potential when the sacrificial anode is not corroded; When the anode potential changes, it means that the sacrificial anode has corroded. The formula for state monitoring and life prediction of the sacrificial anode is: M 消耗 Result 消耗 M 余量 =M-M 消耗 M 余量 With M 预警 Compare, M. 余量 ≤M 预警 Timely warning; Among them, Q 消耗 It represents the charge consumed by the sacrificial anode, which is the integral of the protection current I over the time t. t0 and t1 represent the time t0 and t1 respectively. K represents the proportional constant. The electrochemical equivalent is different according to the sacrificial anode material. M 消耗 represents the mass consumed by the sacrificial anode, M represents the total mass of the sacrificial anode, M 余量 Represents the remaining mass of the sacrificial anode.

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