Sensor fault diagnosis method and device, electronic equipment and storage medium

Abstract

The application relates to the technical field of fault diagnosis, and provides a sensor fault diagnosis method and device, electronic equipment and a storage medium, the method comprising the following steps: determining a target concentration of internal filling liquid of a sensor at a t moment; determining a residual concentration of the internal filling liquid based on an initial concentration of the internal filling liquid and the target concentration; acquiring an impedance value of the internal filling liquid, so as to determine a concentration measurement value of the internal filling liquid based on correlation information between the internal filling liquid concentration and the impedance and the impedance value; and determining fault information of the sensor based on the residual concentration of the internal filling liquid and the concentration measurement value. According to the impedance calibration method, the estimation of the internal filling liquid concentration is realized in combination with theoretical calculation, the difference comparison interval between the measurement value and the theoretical calculation value of the internal filling liquid concentration is established, the fault diagnosis of the sensor is realized, the fault diagnosis cost is saved, and the fault diagnosis accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of fault diagnosis technology, and in particular to a sensor fault diagnosis method, apparatus, electronic device, and storage medium. Background Technology

[0002] Currently, sensor fault diagnosis mainly employs two methods: one is the hardware redundancy method, which uses several redundant sensors to measure the same parameter and generate residuals containing important fault information. Sensor faults can be detected by comparing these residuals with a threshold. The other is the analytical redundancy method, including model-based, knowledge-based, and data-driven diagnostic methods. However, these fault diagnosis methods have the following drawbacks:

[0003] (1) Hardware redundancy methods require the use of multiple sensors, which leads to complex structures and increases the weight and cost of the system.

[0004] (2) The analytical redundancy method requires a large amount of data support or prior models. Model-based diagnostic methods require highly accurate models, but it is difficult to establish accurate mathematical models for sensors in nonlinear systems. Knowledge-based sensor diagnostic methods require a large amount of historical measurement data. In sensor fault diagnosis systems, the reasoning knowledge in the diagnostic process is mostly represented in the form of If-Then rules. The online diagnostic process infers the working status based on observed data facts. However, this method can only diagnose based on existing rules and cannot identify and further explain new faults. Data-driven methods all require the extraction of fault features during the processing. Inappropriate fault feature extraction will have a great impact on detection.

[0005] Therefore, how to diagnose sensor faults is a problem that urgently needs to be solved. Summary of the Invention

[0006] This invention provides a sensor fault diagnosis method, apparatus, electronic device, and storage medium to solve the sensor fault diagnosis problem. By employing an impedance calibration method combined with theoretical calculations, the internal filling liquid concentration is estimated. By establishing a comparison range between the measured value and the theoretically calculated value of the internal filling liquid concentration, sensor fault diagnosis is achieved, saving fault diagnosis costs and improving the accuracy of fault diagnosis.

[0007] This invention provides a sensor fault diagnosis method, comprising:

[0008] Determine the target concentration of the sensor's internal filling fluid at time t;

[0009] Based on the initial concentration of the filling fluid and the target concentration, the remaining concentration of the filling fluid is determined;

[0010] The impedance value of the filling fluid is obtained, and the concentration measurement value of the filling fluid is determined based on the correlation information between the filling fluid concentration and the impedance value.

[0011] Based on the remaining concentration of the internal filling fluid and the measured concentration value, the fault information of the sensor is determined.

[0012] In one embodiment, determining the sensor's fault information based on the remaining concentration of the internal filling fluid and the measured concentration value includes:

[0013] Determine the difference between the remaining concentration of the internal filling fluid and the measured concentration value;

[0014] If the difference is greater than the first threshold, then the sensor is determined to be faulty;

[0015] Determine the interval measurement difference of the internal filling fluid concentration to determine the fault level of the sensor based on the interval measurement difference.

[0016] In one embodiment, determining the fault level of the sensor based on the interval measurement difference includes:

[0017] If the difference in the interval measurement is greater than the second threshold, then the fault level of the sensor is determined to be Level 1;

[0018] If the difference in the interval measurement is greater than the third threshold and less than the second threshold, then the fault level of the sensor is determined to be level two.

[0019] If the difference in the interval measurement is greater than the fourth threshold and less than the third threshold, then the fault level of the sensor is determined to be level three.

[0020] In one embodiment, determining the target concentration of the sensor's internal filling fluid at time t includes:

[0021] Determine the total number of electrons in the reaction system corresponding to the internal filling liquid;

[0022] Based on the total number of electrons, the initial concentration, the initial volume of the internal filling fluid, the molar mass of water, and the density of water, the target concentration of the internal filling fluid of the sensor at time t is determined.

[0023] The formula for calculating the target concentration of the sensor's internal filling fluid at time t is as follows:

[0024]

[0025] Where N represents the total number of electrons in the reaction system, e represents the elementary charge, and I t C represents the current value at time t. aC represents the initial concentration. b V represents the target concentration of the filling fluid at time t. a The initial volume of the filling fluid is represented by M, the molar mass of water is represented by ρ, and the density of water is represented by ρ.

[0026] In one embodiment, after determining the remaining concentration of the internal filling fluid based on the initial concentration and the target concentration, the method further includes:

[0027] Determine the reaction rate of the internal filling fluid;

[0028] The remaining lifespan of the sensor is determined based on the reaction rate of the internal filling fluid, the remaining concentration, and the initial concentration.

[0029] The formula for calculating the remaining service life of the sensor is as follows:

[0030]

[0031] Where L represents the remaining lifespan of the sensor, and C y C represents the remaining concentration of the internal filling fluid. a k represents the initial concentration. v The expression represents the reaction rate, Co represents the dissolved oxygen concentration, K represents the pre-exponential factor, e1 represents a constant, R represents the molar gas constant, T represents the reaction temperature, and ΔG represents the activation energy. Δk Indicates the fault response rate. Δχ represents the difference between interval measurements, and Δχ represents the first threshold.

[0032] In one embodiment, the target temperature is determined by the following steps:

[0033] Obtain the temperature value from the sensor;

[0034] Based on the temperature value, the correlation information between the internal filling fluid concentration and the impedance is obtained.

[0035] In one embodiment, the method further includes:

[0036] Determine the sum of the difference and the measurement error;

[0037] If the sum is greater than the tolerance deviation value and less than the first threshold, the sensor is calibrated based on the difference.

[0038] The present invention also provides a sensor fault diagnosis device, comprising: a circuit switching switch, a current and voltage measurement module, and an impedance measurement module;

[0039] The circuit switching switch is used to control the on / off state of the current and voltage acquisition module and the impedance measurement module;

[0040] The current and voltage measurement module is used to measure the current value corresponding to dissolved oxygen in the internal filling fluid;

[0041] The impedance measurement module is used to measure the impedance value of the internal filling fluid.

[0042] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the sensor fault diagnosis method as described above.

[0043] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the sensor fault diagnosis method as described above.

[0044] The present invention provides a sensor fault diagnosis method, apparatus, electronic device, and storage medium. The method involves determining the target concentration of the sensor's internal filling fluid at time t; determining the remaining concentration of the internal filling fluid based on its initial concentration and the target concentration; acquiring the impedance value of the internal filling fluid; determining a measured concentration value of the internal filling fluid based on the correlation information between the internal filling fluid concentration and impedance, and the impedance value; and determining sensor fault information based on the remaining concentration of the internal filling fluid and the measured concentration value. This invention uses an impedance calibration method combined with theoretical calculations to estimate the internal filling fluid concentration. By establishing a comparison range between the measured and theoretically calculated concentration values, it achieves sensor fault diagnosis, saving fault diagnosis costs and improving the accuracy of fault diagnosis. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is one of the flowcharts of the sensor fault diagnosis method provided by the present invention;

[0047] Figure 2 This is the second flowchart of the sensor fault diagnosis method provided by the present invention;

[0048] Figure 3 This is a schematic diagram of the sensor fault diagnosis device provided by the present invention;

[0049] Figure 4This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0051] The following is combined Figures 1-4 The present invention describes a sensor fault diagnosis method, apparatus, electronic device, and storage medium.

[0052] Specifically, the present invention provides a sensor fault diagnosis method, referring to... Figure 1 , Figure 1 This is one of the flowcharts of the sensor fault diagnosis method provided by the present invention.

[0053] The sensor fault diagnosis method provided in this embodiment of the invention includes:

[0054] Step 100: Determine the target concentration of the sensor's internal filling fluid at time t;

[0055] It should be noted that the embodiments of the present invention are mainly applied to dissolved oxygen sensors, wherein a dissolved oxygen sensor is a sensing device used to measure the amount of oxygen dissolved in water.

[0056] The embodiments of the present invention do not require a large amount of data modeling for sensor fault diagnosis and lifespan prediction. Instead, they directly use the measurement signals as a basis and combine theoretical calculations to achieve fault diagnosis, self-calibration, and lifespan prediction of the dissolved oxygen sensor's internal filling.

[0057] It should be further explained that, according to Faraday's law, the magnitude of the current is proportional to the number of electrons. The number of electrons per unit time can be calculated from the relationship between circuit current, voltage and charge. By integrating the current over a period of time, the total number of electrons flowing through the circuit during that period can be obtained.

[0058] As can be seen from the principles of chemical reaction, based on the principle of chemical reaction equilibrium, there is a relationship between the number of electrons transferred and the number of molecules transformed or ions generated. Through chemical reaction equations, the relationship between the number of electrons and the number of molecules or ions transformed and generated can be established, thereby obtaining the number of reactants or products participating in the reaction.

[0059] The internal filling fluid mainly provides ions for the dissolved oxygen electrode reaction. Given the initial concentration of the internal filling fluid, it is also necessary to determine the target concentration of the internal filling fluid at time t in order to deduce the concentration of the remaining ions in the internal filling fluid.

[0060] To determine the target concentration of the sensor's internal filling fluid at time t, specifically, determine the total number of electrons in the reaction system corresponding to the internal filling fluid, and then, based on the total number of electrons, the initial concentration, the initial volume of the internal filling fluid, the molar mass of water, and the density of water, determine the target concentration of the sensor's internal filling fluid at time t.

[0061] The formula for calculating the target concentration of the sensor's internal filling fluid at time t is as follows:

[0062]

[0063] Where N represents the total number of electrons in the reaction system, e represents the elementary charge, and I t C represents the current value at time t. a C represents the initial concentration. b V represents the target concentration of the filling fluid at time t. a The initial volume of the filling fluid is represented by M, the molar mass of water is represented by ρ, and the density of water is represented by ρ.

[0064] It should be further noted that the sensor fault diagnosis device is equipped with a current and voltage measurement module. This module can measure the current value corresponding to dissolved oxygen in the filling fluid. For example, it can measure the current value of dissolved oxygen in the filling fluid at time t, i.e., I0. t .

[0065] This invention provides an embodiment of the invention that integrates time and current to obtain the total number of electrons in the reaction system. Then, based on the total number of electrons, the initial concentration, the initial volume of the filling liquid, and other information, the target concentration of the filling liquid at time t is determined. This improves the accuracy of determining the filling liquid and, consequently, the accuracy of sensor fault diagnosis.

[0066] Step 200: Determine the remaining concentration of the internal filling fluid based on the initial concentration and the target concentration;

[0067] After determining the target concentration of the filling fluid at time t, the remaining concentration of the filling fluid is determined based on the initial concentration and the target concentration.

[0068] The remaining concentration of the internal filling fluid is related to the extent of the chemical reaction. During the chemical reaction, the number of electrons consumed is equal to the number of chloride ions consumed, and the reaction consumes water molecules. Based on this, the remaining concentration of the internal filling fluid can be derived from the current value, as shown in the following formula:

[0069]

[0070] Where N represents the total number of electrons in the reaction system, e represents the elementary charge, and I t C represents the current value at time t.y C represents the remaining concentration of the internal filling fluid. a C represents the initial concentration. b V represents the target concentration of the filling fluid at time t. a The initial volume of the filling fluid is represented by M, the molar mass of water is represented by ρ, and the density of water is represented by ρ.

[0071] Step 300: Obtain the impedance value of the filling fluid, and determine the concentration measurement value of the filling fluid based on the correlation information between the filling fluid concentration and impedance and the impedance value.

[0072] It should be noted that before determining the measured value of the internal filling fluid concentration, it is necessary to calibrate the relationship curve between the internal filling fluid concentration and the impedance, that is, to determine the correlation information between the internal filling fluid concentration and the impedance.

[0073] For example, the reaction equation of a polarographic dissolved oxygen sensor shows that the reaction consumes chloride ions and water. Based on the reaction equation, the impedance corresponding to different concentrations and volumes is measured to establish the residual concentration C of the internal filling liquid. y The curve showing the relationship between impedance Z and Z: Z∝C y .

[0074] The reaction equation is shown below:

[0075] O2+H2O+4Ag+4KCl→4AgCl+4KOH;

[0076] In this context, O2 represents oxygen, H2O represents water, Ag represents silver, KCl represents potassium chloride, AgCl represents silver chloride, and KOH represents potassium hydroxide.

[0077] It should be further noted that the sensor fault diagnosis device is equipped with an impedance measurement module, which can measure the impedance value of the internal filling fluid. The impedance value of the internal filling fluid measured by the impedance measurement module is obtained, and then, based on the correlation information between the internal filling fluid concentration and impedance, as well as the measured impedance value, the concentration of the internal filling fluid is determined.

[0078] For example, refer to Table 1, which shows the correlation between the filling fluid concentration and impedance.

[0079] Table 1

[0080] Internal filling fluid concentration impedance 20mg / L AΩ 30mg / L BΩ 40mg / L CΩ 50mg / L DΩ 60mg / L EΩ

[0081] As shown in Table 1, assuming the measured impedance value is BΩ, the measured concentration of the filling fluid can be determined to be 30 mg / L.

[0082] Step 400: Based on the remaining concentration of the internal filling fluid and the concentration measurement value, determine the fault information of the sensor.

[0083] After determining the remaining concentration and measured value of the internal filling fluid, the sensor's fault information is determined based on these two values. This fault information includes the fault type and fault level. For example, the difference between the remaining concentration and the measured value of the internal filling fluid is determined, different difference comparison intervals are established, and the sensor's fault level is determined based on these intervals.

[0084] This invention determines the change in the internal filling fluid of the sensor based on the AC impedance characteristics of the internal filling fluid. The loss of internal filling fluid will lead to changes in the volume of internal filling fluid and the concentration of ions in the solution. By establishing a quantitative relationship curve between the concentration of internal filling fluid and impedance, the ion concentration can be obtained when the internal filling fluid impedance is measured, i.e., the concentration measurement value. Then, the detection calculation result (i.e., the concentration measurement value) is compared with the theoretical calculation value (the remaining concentration of internal filling fluid) to determine whether the electrolyte has been lost and the severity of the loss, so as to determine the fault information of the sensor.

[0085] The sensor fault diagnosis method provided in this invention determines the target concentration of the sensor's internal filling fluid at time t; determines the remaining concentration of the internal filling fluid based on the initial and target concentrations; obtains the impedance value of the internal filling fluid at the target temperature, and determines the measured concentration value of the internal filling fluid based on the correlation information between the internal filling fluid concentration and impedance, as well as the impedance value; and determines the sensor's fault information based on the remaining concentration and the measured concentration value. This invention employs an impedance calibration method combined with theoretical calculations to estimate the internal filling fluid concentration, and establishes a comparison range between the measured and theoretically calculated concentration values ​​to achieve sensor fault diagnosis, saving fault diagnosis costs and improving the accuracy of fault diagnosis.

[0086] Based on the above embodiments, determining the sensor's fault information based on the remaining concentration of the internal filling fluid and the measured concentration value includes: determining the difference between the remaining concentration of the internal filling fluid and the measured concentration value; if the difference is greater than a first threshold, determining that the sensor has malfunctioned; and determining the interval measurement difference of the internal filling fluid concentration to determine the sensor's fault level based on the interval measurement difference.

[0087] It should be noted that under normal operating conditions, the concentration of the internal filling fluid is related to the extent of the reaction. When the sensor's dissolution film is damaged or the sensor housing is broken, the internal filling fluid will be lost. The extent of electrolyte loss varies depending on the degree of damage. In severe cases, the electrolyte will leak out rapidly, and the solution impedance will suddenly increase or decrease. In less severe cases, the internal filling fluid impedance will show a rapid increase or decrease over a period of time. Based on this, by comparing the difference between the theoretically calculated and measured values ​​of the internal filling fluid, the electrolyte loss can be qualitatively analyzed.

[0088] The difference between the remaining concentration of the internal filling fluid and the measured concentration value is determined. If the difference is greater than a first threshold, it indicates that the sensor has failed. Then, the interval measurement difference of the internal filling fluid concentration is determined to determine the fault level of the sensor based on the interval measurement difference.

[0089] The interval measurement difference refers to the average of multiple concentration measurements of the filling fluid, resulting in multiple concentration values. The difference between any two concentration measurements is then determined, and finally, the average of these differences is used as the interval measurement difference. For example, assuming three interval measurements of the filling fluid concentration are performed, yielding three concentration values ​​β1, β2, and β3, then the interval measurement difference is... The calculation formula is:

[0090]

[0091] If the interval measurement difference is greater than the second threshold, the sensor is determined to be at level one; if the interval measurement difference is greater than the third threshold but less than the second threshold, the sensor is determined to be at level two; if the interval measurement difference is greater than the fourth threshold but less than the third threshold, the sensor is determined to be at level three.

[0092] The order of magnitude between the thresholds is: second threshold > third threshold > fourth threshold; the order of magnitude between the levels is: first level > second level > third level. The higher the level, the more serious the fault, that is, the more serious the loss of internal filling fluid.

[0093] For example, let α represent the remaining concentration of the filling fluid (i.e., the theoretical calculated value), β represent the measured concentration value, Δχ represent the first threshold, Δq represent the second threshold, Δy represent the third threshold, and Δz represent the fourth threshold.

[0094] Under normal circumstances, the absolute value of the difference between the theoretically calculated value α of the internal filling fluid and the measured value β is less than Δχ. If this condition is not met, the sensor is determined to be faulty, and then three interval measurements are performed, with the difference measured at intervals. If the difference is greater than Δq, the fault is determined to be that the internal filling fluid has been completely lost; if the difference between interval measurements is greater than Δy and less than Δq, the fault is determined to be a serious loss fault; if the difference between interval measurements is greater than Δz and less than Δy, the fault is determined to be a slow loss fault.

[0095] Refer to Table 2, which contains various fault information and judgment conditions for the sensor.

[0096] Table 2

[0097]

[0098] This invention enables sensor fault diagnosis by establishing a comparison range between the measured value and the theoretically calculated value of the internal filling fluid concentration, thereby saving fault diagnosis costs and improving the accuracy of fault diagnosis.

[0099] Based on the above embodiments, after determining the remaining concentration of the internal filling fluid based on the initial concentration and the target concentration, the method further includes: determining the reaction rate of the internal filling fluid; and determining the remaining service life of the sensor based on the reaction rate of the internal filling fluid, the remaining concentration, and the initial concentration.

[0100] It should be noted that the embodiments of the present invention are used to estimate the remaining service life of the sensor. Based on a joint analysis of the theoretically calculated value and the actual measured value of the internal filling fluid concentration, assuming no electrolyte loss fault, the remaining ion concentration of the internal filling fluid is used to establish a relationship between the remaining ion concentration and the remaining service life, thereby predicting the remaining service life of both the internal filling fluid and the sensor. Specifically, the remaining service life of the internal filling fluid corresponds to the remaining service life of the sensor; that is, a short remaining service life of the internal filling fluid indicates a short remaining service life of the sensor, and vice versa.

[0101] The reaction rate of the internal filling fluid is determined, and then the remaining lifespan of the sensor is determined based on the reaction rate, the remaining concentration, and the initial concentration. For example, under normal operating conditions, the remaining lifespan of the internal filling fluid is related to the extent of the reaction; lifespan estimation under fault conditions needs to be based on the fault type.

[0102] The formula for calculating the remaining lifespan of the sensor is as follows:

[0103]

[0104] Where L represents the remaining lifespan of the sensor, and C y C represents the remaining concentration of the internal filling fluid. a k represents the initial concentration. v The expression represents the reaction rate, Co represents the dissolved oxygen concentration, K represents the pre-exponential factor, e1 represents a constant, R represents the molar gas constant, T represents the reaction temperature, and ΔG represents the activation energy. Δk Indicates the fault response rate. Δχ represents the difference between interval measurements, and Δχ represents the first threshold.

[0105] It should be noted that a smaller L indicates a shorter lifetime; the reaction rate k v The factors affecting dissolved oxygen concentration (Co), reaction temperature (T), and failure reaction rate (K) are also considered. Δk Related to; fault response rate K ΔkIt depends on the fault level; under normal circumstances, Therefore K Δk K is 1, in the case of a fault. Δk for The ratio formula with Δχ.

[0106] Based on the reaction rate, remaining concentration, and initial concentration of the internal filling fluid, this invention determines the remaining service life of the sensor. Based on this, the remaining service life of the internal filling fluid and the sensor is estimated, providing a reference guide for timely replacement of the dissolved oxygen internal filling fluid and improving the safety of sensor use.

[0107] Based on the above embodiments, the target temperature is determined by the following steps: obtaining the temperature value of the sensor; and based on the temperature value, obtaining the correlation information between the internal filling fluid concentration and the impedance.

[0108] It should be noted that, since chemical reactions occur in systems controlled by charge transfer and diffusion mixing, the Faraday impedance exhibits an inverse exponential relationship with temperature, as indicated by the Arrhenius equation.

[0109]

[0110] Where Z represents impedance, K represents the pre-exponential factor of the chemical reaction, e1 represents a constant, R represents the molar gas constant, T represents the reaction temperature, and ΔG represents the activation energy.

[0111] Therefore, a temperature compensation curve needs to be constructed. The temperature compensation method involves measuring the impedance and solution concentration at different temperatures to establish a relationship curve between the internal filling liquid concentration and impedance at multiple temperatures. Based on the sensor's own temperature measurement unit, a suitable relationship curve is selected for the corresponding temperature, thereby achieving temperature compensation. It is understandable that since temperature affects the impedance measurement of the internal filling liquid, temperature calibration is necessary to reduce impedance measurement errors.

[0112] The sensor's temperature value is acquired, and then, based on this temperature value, the correlation information between the filling fluid concentration and impedance is obtained; that is, the correlation information between the filling fluid concentration and impedance corresponding to that temperature value is obtained. For example, relationship curves are established at different temperatures (such as 10℃, 20℃, 30℃, and 35℃), i.e., relationship curves between filling fluid concentration and impedance. Then, the closest temperature curve parameter is selected for compensation calibration. For example, when the measurement temperature is 25℃, the relationship curve parameter for 25℃ is selected, i.e., the relationship curve parameter for the filling fluid concentration and impedance corresponding to 25℃ is selected; when the measurement temperature is 29℃, the relationship curve parameter for 30℃ is selected, i.e., the relationship curve parameter for the filling fluid concentration and impedance corresponding to 30℃ is selected.

[0113] This invention reduces impedance measurement errors and improves the accuracy of impedance measurement by performing temperature compensation, thereby improving the accuracy of sensor fault diagnosis.

[0114] Based on the above embodiments, the method further includes: determining the sum of the difference and the measurement error; if the sum is greater than the tolerance deviation value and less than the first threshold, then calibrating the sensor based on the difference.

[0115] It should be noted that during fault diagnosis, self-compensation calibration can be performed to address signal drift caused by electrode scaling. Because the sensor's own electrodes are used, AgCl will accumulate on the electrode surface during long-term dissolved oxygen measurements, causing signal drift in both dissolved oxygen and AC impedance measurements. By periodically compensating for this drift using theoretical calculations and actual measurements, signal drift caused by electrode scaling can be effectively eliminated, achieving self-calibration.

[0116] Determine the sum of the difference and the measurement error. If the sum is greater than the tolerance deviation value but less than the first threshold, then calibrate the sensor based on the difference. For example, under normal conditions, the sensor is self-calibrated every two weeks (which can be determined based on requirements). Based on the difference between the calculated value α and the measured value β, considering the measurement error Δζ, the theoretical tolerance deviation value is Δγ. If Δγ < |α-β+Δξ| < Δχ, then the sensor electrode scaling error is calibrated and compensated based on the theoretically calculated value, that is, the calculated value α-β is used as the calibration compensation parameter.

[0117] This invention, through its electrode scaling compensation function, effectively reduces the significant error caused by electrode scaling drift and improves the accuracy of sensor fault diagnosis.

[0118] refer to Figure 2 , Figure 2 This is the second flowchart of the sensor fault diagnosis method provided by the present invention.

[0119] This invention proposes a method for self-diagnosis, self-calibration, and lifetime prediction of dissolved oxygen sensors filled with liquid, comprising the following steps:

[0120] Step 1: Calibrate the relationship curve between the internal filling fluid concentration and the impedance.

[0121] The reaction equation of the polarographic dissolved oxygen sensor shows that the reaction consumes chloride ions and water. Based on the reaction equation, the impedance corresponding to different concentrations and volumes is measured to establish the residual concentration C of the internal filling liquid. y The curve showing the relationship between impedance Z and Z: Z∝C y .

[0122] The reaction equation is shown below:

[0123] O2+H2O+4Ag+4KCl→4AgCl+4KOH;

[0124] In this context, O2 represents oxygen, H2O represents water, Ag represents silver, KCl represents potassium chloride, AgCl represents silver chloride, and KOH represents potassium hydroxide.

[0125] Step 2: Temperature compensation.

[0126] Since chemical reactions occur in systems controlled by charge transfer and diffusion mixing, the Faraday impedance, according to the Arrhenius equation, has an inverse exponential relationship with temperature:

[0127]

[0128] Where Z represents impedance, K represents the pre-exponential factor of the chemical reaction, e1 represents a constant, R represents the molar gas constant, T represents the reaction temperature, and ΔG represents the activation energy.

[0129] Therefore, it is necessary to construct a temperature compensation curve. The temperature compensation method is as follows: by measuring the impedance and solution concentration values ​​at different temperatures, the relationship between solution concentration and impedance at multiple temperatures is established. Based on the temperature measurement unit of the sensor itself, a more suitable temperature curve is selected at the corresponding temperature, thereby achieving temperature compensation.

[0130] Step 3: Calculate the remaining concentration of the filling fluid.

[0131] The remaining concentration of the filling fluid is related to the extent of the chemical reaction. As shown in the chemical reaction equation, the number of electrons consumed is equal to the number of chloride ions consumed. The reaction consumes water molecules. The remaining concentration of the filling fluid can be derived from the current value, and the calculation formula is as follows:

[0132]

[0133] Where N represents the total number of electrons in the reaction system, e represents the elementary charge, and I t C represents the current value at time t. y C represents the remaining concentration of the filling fluid. a C represents the initial concentration. b V represents the target concentration of the filling fluid at time t. a The initial volume of the filling fluid is represented by M, the molar mass of water is represented by ρ, and the density of water is represented by ρ.

[0134] Step 4: Diagnosing internal filling fluid loss.

[0135] Under normal operating conditions, the concentration of the internal filling fluid is related to the extent of the reaction. When the sensor's dissolution film is damaged or the sensor housing is broken, the internal filling fluid will leak out. The extent of electrolyte loss varies depending on the degree of damage. Severe damage results in rapid electrolyte loss, causing a sudden increase or decrease in solution impedance. Less severe damage leads to a rapid increase or decrease in internal filling fluid impedance over a period of time. Therefore, by comparing the theoretical calculations and measured values ​​of the internal filling fluid, the extent of electrolyte loss can be qualitatively analyzed.

[0136] Under normal circumstances, the absolute value of the difference between the theoretically calculated value α of the internal filling fluid and the measured value β is less than Δχ. If this condition is not met, the sensor is determined to be faulty, and then three interval measurements are performed, with the difference measured at intervals. If the difference is greater than Δq, the fault is determined to be that the internal filling fluid has been completely lost; if the difference between interval measurements is greater than Δy and less than Δq, the fault is determined to be a serious loss fault; if the difference between interval measurements is greater than Δz and less than Δy, the fault is determined to be a slow loss fault.

[0137] Step 5: Calibrate compensation.

[0138] Under normal conditions, the sensor is self-calibrated every two weeks (which can be determined based on demand). Based on the difference between the calculated value α and the measured value β, and considering the measurement error Δζ, the theoretical tolerance deviation is Δγ. If Δγ < |α-β+Δζ| < Δχ, then the sensor electrode scaling error is calibrated and compensated according to the theoretical calculation value, that is, the calculated value α-β is used as the calibration compensation parameter.

[0139] Step 6: Estimate the remaining life of the internal filling fluid.

[0140] Under normal operating conditions, the remaining service life of the internal filling fluid is related to the extent of the reaction. The service life estimate under fault conditions needs to be based on the fault type.

[0141] The formula for calculating the remaining lifespan of the sensor is as follows:

[0142]

[0143] Where L represents the remaining lifespan of the sensor, and C y C represents the remaining concentration of the internal filling fluid. a k represents the initial concentration. v The expression represents the reaction rate, Co represents the dissolved oxygen concentration, K represents the pre-exponential factor, e1 represents a constant, R represents the molar gas constant, T represents the reaction temperature, and ΔG represents the activation energy. Δk Indicates the fault response rate. Δχ represents the difference between interval measurements, and Δχ represents the first threshold.

[0144] Based on measurement signals and combined with theoretical calculations, this invention enables fault diagnosis, self-calibration, and lifespan prediction for dissolved oxygen sensors, offering the following advantages:

[0145] (1) The impedance calibration method is adopted, combined with theoretical calculation to solve the estimation of the internal filling fluid concentration, and the internal filling fluid loss fault is diagnosed and graded by establishing a difference comparison interval.

[0146] (2) Based on the original electrode structure, impedance measurement can be achieved without adding other impedance measurement units or modifying the sensor sensing elements.

[0147] (3) It has temperature compensation and electrode scaling compensation functions, which effectively reduces the error caused by temperature and electrode scaling drift.

[0148] (4) To estimate the remaining lifespan of the internal filling fluid, providing a reference guide for timely replacement of dissolved oxygen internal filling fluid.

[0149] Based on the above embodiments, this invention also proposes a sensor fault diagnosis device, which is applied to the above embodiments. The device includes: a circuit switching switch 9, a current and voltage measurement module 10, and an impedance measurement module 12.

[0150] The circuit switching switch 9 is used to control the on / off state of the current and voltage acquisition module and the impedance measurement module;

[0151] The current and voltage measurement module 10 is used to measure the current value corresponding to dissolved oxygen in the internal filling fluid;

[0152] The impedance measurement module 12 is used to measure the impedance value of the internal filling fluid.

[0153] It should be noted that the embodiments of the present invention achieve AC impedance measurement of the solution by directly applying a small AC potential to the polarographic dissolved oxygen electrode, which can effectively prevent electrode polarization and avoid hardware redundancy caused by adding other impedance measurement electrodes or sensors.

[0154] Furthermore, the embodiments of the present invention employ a multiplexed self-switching signal acquisition system, that is, multiplexing the power supply and signal acquisition circuits. The multiplexing switching is controlled by a microprocessor. Based on the sensor's working time, the microprocessor controls the converter to automatically switch between the dissolved oxygen DC signal measurement circuit and the AC signal diagnostic circuit.

[0155] like Figure 3 As shown, the sensor fault diagnosis device includes a probe housing 1, a silver wire 2, an internal filling liquid 3, a platinum wire 4, an environmental solution 5, an environmental solution boundary 6, a dissolved oxygen permeable membrane 7, a temperature detection module 8, a circuit switching switch 9, a current and voltage measurement module 10, a microprocessor 11, an impedance measurement module 12, and a power supply 13.

[0156] It should be noted that the internal filling liquid 3 can be KCl internal filling liquid or KCl / KOH internal filling liquid; the platinum wire 4 can be replaced by gold wire; the dissolved oxygen permeable membrane 7 includes, but is not limited to, polyethylene membrane, polytetrafluoroethylene membrane, polytetrafluoroethylene propylene membrane, polydimethylsilicone rubber membrane and polytetrafluoroethylene / silicone composite membrane; the current and voltage measurement module 10 includes analog-to-digital conversion function.

[0157] like Figure 3 As shown, this embodiment of the invention employs a two-electrode polarographic dissolved oxygen sensor probe, which incorporates a temperature detection module 8. The signal acquisition circuit, based on the current and voltage measurement module 10, adds a circuit switching switch 9 and an impedance measurement module 12. In this embodiment, the electrode serves as both the reaction electrode for dissolved oxygen detection and the support electrode for solution impedance detection; this electrode reuse function is achieved through the circuit switching switch 9.

[0158] The microprocessor 11 controls the circuit switching switch 9 to select between the current and voltage measurement module 10 and the impedance measurement module 12. When the circuit is switched to the current and voltage measurement module 10, electrodes 2 and 4 measure the dissolved oxygen current to obtain the dissolved oxygen value; when the circuit is switched to the impedance measurement module 12, electrodes detect the impedance of the internal filling liquid 3 to obtain the internal filling liquid concentration value.

[0159] Understandably, after the dissolved oxygen current is measured by the current and voltage measurement module 10, the microprocessor 11 can determine the total number of electrons in the reaction system based on the current. Then, based on the total number of electrons, the initial concentration, the initial volume of the filling liquid, the molar mass of water, and the density of water, the target concentration of the filling liquid at time t is determined. Finally, the remaining concentration of the filling liquid can be determined based on the target concentration and the initial concentration.

[0160] After the impedance measurement module 12 measures the impedance value of the filling fluid, the microprocessor 11 determines the measured concentration value of the filling fluid based on the correlation information between the filling fluid concentration and the impedance and the measured impedance value.

[0161] Finally, the microprocessor 11 determines the sensor's fault information based on the remaining concentration of the internal filling fluid and the concentration measurement.

[0162] The sensor fault diagnosis device provided in this embodiment of the invention estimates the internal filling liquid concentration by using an impedance calibration method combined with theoretical calculation, and realizes sensor fault diagnosis by establishing a comparison range between the measured value and the theoretically calculated value of the internal filling liquid concentration. This saves fault diagnosis costs and improves the accuracy of fault diagnosis.

[0163] Figure 4An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 4 As shown, the electronic device may include: a processor 410, a communication interface 420, a memory 430, and a communication bus 440, wherein the processor 410, the communication interface 420, and the memory 430 communicate with each other via the communication bus 440. The processor 410 can call logical instructions in the memory 430 to execute a sensor fault diagnosis method, which includes:

[0164] Determine the target concentration of the sensor's internal filling fluid at time t;

[0165] Based on the initial concentration of the filling fluid and the target concentration, the remaining concentration of the filling fluid is determined;

[0166] The impedance value of the filling fluid is obtained, and the concentration measurement value of the filling fluid is determined based on the correlation information between the filling fluid concentration and the impedance value.

[0167] Based on the remaining concentration of the internal filling fluid and the measured concentration value, the fault information of the sensor is determined.

[0168] Furthermore, the logical instructions in the aforementioned memory 440 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0169] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the sensor fault diagnosis method provided by the methods described above, the method comprising:

[0170] Determine the target concentration of the sensor's internal filling fluid at time t;

[0171] Based on the initial concentration of the filling fluid and the target concentration, the remaining concentration of the filling fluid is determined;

[0172] The impedance value of the filling fluid is obtained, and the concentration measurement value of the filling fluid is determined based on the correlation information between the filling fluid concentration and the impedance value.

[0173] Based on the remaining concentration of the internal filling fluid and the measured concentration value, the fault information of the sensor is determined.

[0174] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0175] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0176] Finally, it should be noted that 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sensor fault diagnosis method, characterized in that, include: Determine the target concentration of the sensor's internal filling fluid at time t; Based on the initial concentration of the filling fluid and the target concentration, the remaining concentration of the filling fluid is determined; The impedance value of the filling fluid is obtained, and the concentration measurement value of the filling fluid is determined based on the correlation information between the filling fluid concentration and the impedance value. Based on the remaining concentration of the internal filling fluid and the concentration measurement value, the fault information of the sensor is determined; Determining the target concentration of the sensor's internal filling fluid at time t includes: Determine the total number of electrons in the reaction system corresponding to the internal filling liquid; Based on the total number of electrons, the initial concentration, the initial volume of the internal filling fluid, the molar mass of water, and the density of water, the target concentration of the internal filling fluid of the sensor at time t is determined. The formula for calculating the target concentration of the sensor's internal filling fluid at time t is as follows: Where N represents the total number of electrons in the reaction system, e represents the elementary charge, and I t C represents the current value at time t. a C represents the initial concentration. b V represents the target concentration of the filling fluid at time t. a The initial volume of the filling fluid is represented by M, the molar mass of water is represented by ρ, and the density of water is represented by ρ.

2. The sensor fault diagnosis method according to claim 1, characterized in that, The process of determining the sensor's fault information based on the remaining concentration of the internal filling fluid and the measured concentration value includes: Determine the difference between the remaining concentration of the internal filling fluid and the measured concentration value; If the difference is greater than the first threshold, then the sensor is determined to be faulty; Determine the interval measurement difference of the internal filling fluid concentration to determine the fault level of the sensor based on the interval measurement difference.

3. The sensor fault diagnosis method according to claim 2, characterized in that, Determining the fault level of the sensor based on the interval measurement difference includes: If the difference in the interval measurement is greater than the second threshold, then the fault level of the sensor is determined to be Level 1; If the difference in the interval measurement is greater than the third threshold and less than the second threshold, then the fault level of the sensor is determined to be level two. If the difference in the interval measurement is greater than the fourth threshold and less than the third threshold, then the fault level of the sensor is determined to be level three.

4. The sensor fault diagnosis method according to claim 1, characterized in that, After determining the remaining concentration of the internal filling fluid based on the initial concentration and the target concentration, the method further includes: Determine the reaction rate of the internal filling fluid; The remaining lifespan of the sensor is determined based on the reaction rate of the internal filling fluid, the remaining concentration, and the initial concentration. The formula for calculating the remaining service life of the sensor is as follows: Where L represents the remaining lifespan of the sensor, and C y C represents the remaining concentration of the internal filling fluid. a k represents the initial concentration. v The expression represents the reaction rate, Co represents the dissolved oxygen concentration, K represents the pre-exponential factor, e1 represents a constant, R represents the molar gas constant, T represents the reaction temperature, and ΔG represents the activation energy. Δk Indicates the fault response rate. Δχ represents the difference between interval measurements, and Δχ represents the first threshold.

5. The sensor fault diagnosis method according to claim 1, characterized in that, Before determining the measured concentration of the internal filling fluid based on the correlation information between the filling fluid concentration and impedance, and the impedance value, the method further includes: Obtain the temperature value from the sensor; Based on the temperature value, the correlation information between the internal filling fluid concentration and the impedance is obtained.

6. The sensor fault diagnosis method according to claim 2, characterized in that, The method further includes: Determine the sum of the difference and the measurement error; If the sum is greater than the tolerance deviation value and less than the first threshold, the sensor is calibrated based on the difference.

7. A sensor fault diagnosis device, characterized in that, The sensor fault diagnosis method applied to any one of claims 1 to 6 includes: a circuit switching switch, a current and voltage measurement module, and an impedance measurement module; The circuit switching switch is used to control the on / off state of the current and voltage acquisition module and the impedance measurement module; The current and voltage measurement module is used to measure the current value corresponding to dissolved oxygen in the internal filling fluid; The impedance measurement module is used to measure the impedance value of the internal filling fluid.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the sensor fault diagnosis method as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the sensor fault diagnosis method as described in any one of claims 1 to 6.

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