AEM water electrolysis membrane electrode failure diagnosis method

Abstract

The invention discloses an AEM water electrolysis membrane electrode failure diagnosis method. The method comprises the following steps: inputting carrier waves with different alternating-current amplitudes when the AEM water electrolysis membrane electrode is in normal operation, carrying out carrier wave analysis, determining the magnitude of the alternating-current amplitudes, and obtaining a standard spectrogram of electrochemical alternating-current impedance and total harmonic distortion in a normal state; the method comprises the following steps: monitoring the operation of an AEM water electrolysis membrane electrode, entering a diagnosis mode after performance change, inputting a carrier wave, carrying out an electrochemical AC impedance test and a total harmonic distortion test at the same time, and carrying out Fourier transform processing on an output electrochemical AC impedance signal to obtain an electrochemical AC impedance spectrum; processing the output harmonic signal to obtain a total harmonic distortion spectrum; and comparing the total harmonic distortion spectrum with the standard spectrogram obtained in the step 1 by combining the electrochemical alternating current impedance spectrum, and identifying the failure type of the AEM water electrolysis membrane electrode. The method can effectively diagnose the failure mode of temperature change, electrolyte metering change and cathode and anode pressure change of the AEM water electrolysis membrane electrode.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical system diagnosis, and specifically relates to a method for diagnosing the failure of an AEM water electrolysis membrane electrode. Background Art

[0002] Like other mainstream water electrolysis technologies, the AEM water electrolysis technology will also fail during long-term operation, and the reasons for its failure are diverse. Therefore, for the application of the AEM water electrolysis hydrogen production system, a failure diagnosis for the hydrogen production system is urgently needed.

[0003] Currently, the main work on the failure diagnosis of electrochemical systems is in the fields of fuel cells and PEM water electrolysis, where development started earlier. Industrial production devices are equipped with sensors for various parameters. However, the change in the monitored readings of the sensors cannot identify specific failure modes. Therefore, linear diagnostic technologies such as electrochemical impedance spectroscopy (EIS) and the combination of various models have developed rapidly.

[0004] Chinese Patent CN110676488A discloses an online proton exchange membrane fuel cell fault diagnosis method based on low-frequency impedance and electrochemical impedance spectroscopy. The measured low-frequency impedance is compared online with the low-frequency impedance fault threshold, and a fault diagnosis algorithm based on fuzzy logic is used to classify and diagnose the electrochemical impedance spectroscopy, which can better distinguish membrane drying, flooding, and air starvation. However, this method may not be accurate for AEM water electrolysis.

[0005] Chinese Patent CN117457949A discloses a fuel cell water fault diagnosis method and system based on electrochemical impedance spectroscopy, belonging to the field of fuel cell fault diagnosis. By measuring the electrochemical impedance spectroscopy curves of fuel cells in different water content states, curve feature points with high correlation to water content and local change features are extracted. The relationship between the curve features and the water fault state of the fuel cell stack is established through methods such as fuzzy C-means clustering. At the same time, corresponding classification strategies are formulated for the sensitive differences in the wet and dry states of the curve features, and the detection and classification of the water state can be realized through the local EIS curve features, but the applicability is insufficient and it only targets one type of fault.

[0006] Chinese Patent CN109726452A discloses an online proton exchange membrane fuel cell fault diagnosis method based on impedance spectroscopy. First, an electrochemical equivalent circuit model of the proton exchange membrane fuel cell is established, the electrochemical impedance spectroscopy of the proton exchange membrane fuel cell is measured, the parameters in the electrochemical equivalent circuit model are solved by fitting the electrochemical impedance spectroscopy, and then some of these parameters are selected as classification features, and a fault diagnosis algorithm based on a binary tree support vector machine is used to classify the proton exchange membrane fuel cell, and faults such as membrane drying, flooding, and air starvation that are likely to occur inside the proton exchange membrane fuel cell are diagnosed.

[0007] Chinese Patent CN118311346A discloses a multi-fault diagnosis method for proton exchange membrane (PEM) electrolyzers based on the characteristics of cell voltage changes. First, based on the existing interleaved voltage measurement topology, this diagnosis method combines a weighted modified variance algorithm to effectively detect and distinguish between cell faults and voltage sensor faults in the electrolyzer. Second, using the correlation between voltages of multiple cells, an improved correlation coefficient algorithm is adopted to diagnose faults such as short circuits and water shortages.

[0008] In summary, whether the methods of EIS and modeling analysis are effective for AEM water electrolysis still needs to be verified. Therefore, a diagnosis method applied to AEM water electrolysis is required.

[0009] Currently, the main reasons for the failure of AEM membrane electrodes during operation are as follows: 1. Temperature change: Temperature change has a great impact on the performance of both the catalyst itself and the membrane itself. When the temperature is too low, the performance is insufficient, and when the temperature is too high, it will affect the durability of the membrane, etc. During actual production operation, there will be problems of local overheating or overcooling in the electrolyzer, and the temperature sensor cannot accurately identify them.

[0010] 2. Electrolyte metering change (membrane dryness): During the operation of the electrolyzer, the metering of the electrolyte (inlet liquid volume) also has a great impact on the normal operation and performance of the electrolyzer. When the electrolyte inlet rate is too high, although it will not cause failure due to the drying of the diaphragm in the electrolyzer, it will cause waste of raw materials and an increase in overall energy consumption, and the performance will also decline, thus increasing production costs; while when the electrolyte inlet rate is too low, it will lead to a situation where the electrolyte is insufficient and the diaphragm dries out during operation at a certain current density. If this situation runs for a long time, the diaphragm will be damaged, and then production will stop.

[0011] 3. Pressure fluctuation: When local cathode or anode pressure loss occurs during the operation of the electrolyzer, not only will the operating performance change, but also the mechanical pressure on the components will increase, which will affect the life of the components. In severe cases, local diaphragm rupture will directly cause the device to stop. Summary of the Invention

[0012] The present invention proposes a method for diagnosing the failure of AEM water electrolysis membrane electrodes. By performing electrochemical impedance spectroscopy and total harmonic distortion tests on AEM water electrolysis membrane electrodes in the failure mode, it can effectively identify the change trend of electrochemical impedance, the change law of total harmonic distortion, and the characteristic frequency range of total harmonic distortion in different failure modes within the frequency domain range of 100KHz - 100mHz, so as to effectively diagnose several common failure modes such as temperature change, electrolyte metering change, and cathode and anode pressure change of AEM water electrolysis membrane electrodes.

[0013] To this end, the present invention adopts the following technical solution: A method for diagnosing the failure of an AEM water electrolysis membrane electrode, which includes: Step 1, when the AEM water electrolysis membrane electrode is operating normally, input carriers with different AC amplitudes, perform carrier analysis, determine the magnitude of the AC amplitude, and obtain the standard spectrograms of electrochemical AC impedance and total harmonic distortion in the normal state; Step 2, monitor the operation of the AEM water electrolysis membrane electrode. After a performance change occurs, enter the diagnostic mode, input a carrier, and perform total harmonic distortion testing (THD) while performing electrochemical AC impedance testing (EIS); Step 3, perform Fourier transform processing on the output electrochemical AC impedance signal to obtain an electrochemical AC impedance spectrum, and process the output harmonic signal to obtain a total harmonic distortion spectrum; Step 4, according to the total harmonic distortion spectrum, combined with the electrochemical AC impedance spectrum, compare with the standard spectrograms obtained in Step 1 to identify the failure type of the AEM water electrolysis membrane electrode.

[0014] Compared with the existing linear diagnostic technology, the total harmonic distortion diagnostic technology (THDA) can capture the non-linear changes in the initial stage of a fault, locate the characteristic frequency bands of specific faults, realize fast, accurate, and directional diagnostic analysis of electrolyzer equipment, greatly improve the equipment safety. Moreover, during EIS testing, THD testing can be carried out simultaneously. By combining the analysis of EIS and THD, different fault modes during AEM water electrolysis operation can be well identified, which is convenient for on-site operation and maintenance personnel to carry out maintenance and ensure the safety of AEM water electrolysis equipment.

[0015] Further, in Step 1, the determined magnitude of the AC amplitude is at least 25% of the DC current magnitude. A larger AC amplitude is used to reduce the influence of system noise and amplify the THD value.

[0016] Further, in Step 2, determining whether a performance change has occurred mainly involves comparing the difference between the current density obtained from the test at the same potential and the current density during normal operation.

[0017] Further, in Step 1 and Step 2, the input carrier is a sine carrier.

[0018] Further, in Step 2, the two tests carried out simultaneously after entering the diagnostic mode are carried out in the constant current mode.

[0019] Further, in Step 2, the frequency domain range of the electrochemical AC impedance test and the total harmonic distortion test is 100 kHz - 100 mHz, testing from high frequency to low frequency. Selecting a relatively wide frequency domain interval of 100 kHz - 100 mHz is to better distinguish the characteristic THD value migration ranges of different failure modes.

[0020] Further, in step three, the method for processing the output harmonic signal is as follows: The harmonic signal is the absolute response (Yn) of the 2nd - 10th harmonics normalized to the fundamental frequency. The processing uses the calculation method of taking the square root of the algebraic sum of squares of the 2nd - 10th harmonics to obtain the THD value at each frequency, that is .

[0021] Further, in step four, the method for identifying the failure types of the AEM water electrolysis membrane electrode is as follows: When anode voltage loss occurs, the performance degrades, the ohmic impedance increases, and the total harmonic distortion value increases in the frequency domain range of 100 Hz - 100 mHz; when cathode voltage loss occurs, the performance degrades, the ohmic impedance increases, and the total harmonic distortion value decreases in the frequency domain range of 100 Hz - 100 mHz; when the electrolyte metering of the membrane electrode decreases, i.e., the liquid inlet rate decreases, the ohmic impedance decreases, and the total harmonic distortion value increases with the decrease of the liquid inlet rate in the frequency domain range of 631 Hz - 100 mHz; when the temperature of the membrane electrode suddenly rises, the ohmic impedance decreases, and the total harmonic distortion value increases in the frequency domain range of 2510 Hz - 100 mHz.

[0022] Compared with the prior art, the technical effects of the present invention are as follows: By performing electrochemical impedance spectroscopy and total harmonic distortion tests on the AEM water electrolysis membrane electrode in the failure mode, the present invention can effectively identify the change trend of electrochemical impedance, the change law of total harmonic distortion, and the characteristic frequency range of total harmonic distortion under different failure modes in the frequency domain range of 100 KHz - 100 mHz, so as to effectively diagnose common failure modes such as temperature change, electrolyte metering change, and anode and cathode pressure change of the AEM water electrolysis membrane electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 is a flowchart of a method for diagnosing the failure of an AEM water electrolysis membrane electrode of the present invention; Figure 2 is an LSV diagram of the AEM water electrolysis anode under different pressures in the specific embodiment of the present invention; Figure 3 is an EIS diagram of the AEM water electrolysis anode under different pressures in the specific embodiment of the present invention; Figure 4 is a THD diagram of the AEM water electrolysis anode under different pressures in the specific embodiment of the present invention; Figure 5 is the LSV diagram of the AEM water electrolysis cathode under different pressures in the specific embodiment of the present invention; Figure 6 is the EIS diagram of the AEM water electrolysis cathode under different pressures in the specific embodiment of the present invention; Figure 7 is the THD diagram of the AEM water electrolysis cathode under different pressures in the specific embodiment of the present invention; Figure 8 is the EIS diagram of the AEM water electrolysis membrane electrode under 500 mA / cm² DC current and different AC amplitudes in the specific embodiment of the present invention; Figure 9 is the THD diagram of the AEM water electrolysis membrane electrode under 500 mA / cm² DC current and different AC amplitudes in the specific embodiment of the present invention; Figure 10 is the LSV diagram of the AEM water electrolysis membrane electrode under different cathode pressures in the specific embodiment of the present invention; Figure 11 is the EIS diagram of the AEM water electrolysis membrane electrode under different cathode pressures in the specific embodiment of the present invention; Figure 12 is the THD diagram of the AEM water electrolysis membrane electrode under different cathode pressures in the specific embodiment of the present invention; Figure 13 is the LSV diagram of the AEM water electrolysis membrane electrode under different electrolyte metering (inlet flow rate) conditions in the specific embodiment of the present invention; Figure 14 is the EIS diagram of the AEM water electrolysis membrane electrode under different electrolyte metering (inlet flow rate) conditions in the specific embodiment of the present invention; Figure 15 is the THD diagram of the AEM water electrolysis membrane electrode under different electrolyte metering (inlet flow rate) conditions in the specific embodiment of the present invention; Figure 16 is the LSV diagram of the AEM water electrolysis membrane electrode under different temperature conditions in the specific embodiment of the present invention; Figure 17 is the EIS diagram of the AEM water electrolysis membrane electrode under different temperature conditions in the specific embodiment of the present invention; Figure 18 is the THD diagram of the AEM water electrolysis membrane electrode under different temperature conditions in the specific embodiment of the present invention; In the figure, Z' and Z'' respectively represent the real part (resistance component) and the imaginary part (capacitance or inductance component) of the impedance; AC represents the AC amplitude. Specific Embodiment

[0025] The present invention will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments. The present invention includes, but is not limited to, the following embodiments.

[0026] The electrolytes used in this embodiment are all 1 mol / L KOH solutions, with the anodic liquid inlet.

[0027] This embodiment provides a method for diagnosing the failure of an AEM water electrolysis membrane electrode. As Figure 1 shown, the steps are as follows: Step 1: When the AEM water electrolysis membrane electrode is operating normally, input carriers with different AC amplitudes, perform carrier analysis, determine the magnitude of the AC amplitude, and obtain the standard spectrograms of electrochemical AC impedance and total harmonic distortion in the normal state. Step 2: Monitor the operation of the AEM water electrolysis membrane electrode. After a performance change occurs, enter the diagnostic mode, input a carrier, and perform an electrochemical AC impedance test (EIS) while performing a total harmonic distortion test (THD). Step 3: Perform Fourier transform processing on the output electrochemical AC impedance signal to obtain an electrochemical AC impedance spectrum, and process the output harmonic signal to obtain a total harmonic distortion spectrum. Step 4: According to the total harmonic distortion spectrum, in combination with the electrochemical AC impedance spectrum, compare with the standard spectrogram obtained in Step 1 to identify the failure type of the AEM water electrolysis membrane electrode.

[0028] Specifically, in Step 1, the determined magnitude of the AC amplitude is 25% of the DC current magnitude.

[0029] Specifically, in Step 2, determining whether a performance change has occurred mainly involves comparing the difference between the current density measured at the same potential and the current density during normal operation.

[0030] Specifically, in Steps 1 and 2, the input carrier is a sine carrier; in Step 2, the two tests performed simultaneously after entering the diagnostic mode are carried out in the constant current mode; the frequency domain ranges of the electrochemical AC impedance test and the total harmonic distortion test are 100 kHz - 100 mHz, testing from high frequency to low frequency.

[0031] Specifically, the data processing in Step 3 is as follows: The harmonic signal is the absolute response (Yn) of the 2nd - 10th harmonics normalized to the fundamental frequency. The processing uses the calculation method of taking the square root of the algebraic sum of squares of the 2nd - 10th harmonics to obtain the THD value at each frequency, that is .

[0032] Specifically, in step four, the method for identifying the failure types of the AEM water electrolysis membrane electrode is as follows: when anode pressure loss occurs, the performance degrades, the ohmic impedance increases, and the total harmonic distortion value increases in the frequency domain range of 100 Hz - 100 mHz; when cathode pressure loss occurs, the performance degrades, the ohmic impedance increases, and the total harmonic distortion value decreases in the frequency domain range of 100 Hz - 100 mHz; when the electrolyte metering of the membrane electrode decreases, i.e., the liquid inlet rate decreases, the ohmic impedance decreases, and the total harmonic distortion value increases with the decrease of the liquid inlet rate in the frequency domain range of 631 Hz - 100 mHz; when the temperature of the membrane electrode suddenly rises, the ohmic impedance decreases, and the total harmonic distortion value increases in the frequency domain range of 2510 Hz - 100 mHz.

[0033] The formation process of the above AEM water electrolysis membrane electrode failure diagnosis method will be described in detail below.

[0034] According to Figure 1 the process, first, the performance of the AEM water electrolyzer is monitored during operation. In this embodiment, the performance change when the failure is monitored is simulated by the change of LSV (linear voltammetry). When the AEM water electrolyzer operates normally, carriers with different AC amplitudes are input, the selection of the test amplitude is carried out, and the standard spectrograms of EIS and THD during normal operation are obtained; the experimental results of EIS and THD spectra are measured simultaneously by an electrochemical workstation with a harmonic analysis module; generally speaking, the experimental result of THD consists of two parts, THD and noise N, that is, THD + N; therefore, the selection of the AC amplitude during the measurement process is crucial; the THD result increases by an order of magnitude with the increase of the AC amplitude; while the noise signal will decrease with the increase of the amplitude; the opposite change trend of the noise and THD values with the amplitude makes it possible to clarify the effective frequency range of the THD spectrum through amplitude optimization; on the other hand, although the THD intensity increases significantly and the noise signal decreases significantly with the increase of the amplitude, the frequency response analysis should also consider the actual situation of the electrode process and minimize the influence of the disturbance signal on the electrode process during the test. Therefore, the principle for selecting the amplitude in its experimental study is: select the minimum amplitude at which the THD changes significantly in the frequency domain range sensitive to the electro-chemical reaction kinetics; when the performance changes, enter the diagnostic mode, that is, input the carrier, and carry out the next test of electrochemical impedance and total harmonic distortion. The harmonic test result and the EIS test result can be obtained simultaneously after the EIS test. The measured data are processed to obtain the change law of EIS, find out the characteristic frequency domain change range of THD, and compare it with the obtained standard spectrogram to identify and diagnose the specific failure type.

[0035] To verify the feasibility of applying the total harmonic distortion technology to AEM water electrolysis, first, the simulation test of anode and cathode pressure loss in AEM water electrolysis is carried out, that is, a three-electrode system is adopted, and the anode and cathode are respectively tested under different pressure conditions. The test process is the same as Figure 1After each experimental condition stabilizes, conduct the tests. Each test is conducted three times. The settings for EIS and THD tests are the same as in Step 2 of the present invention, and draw spectrograms with error bars.

[0036] According to Figure 2 and Figure 5 the test results, the performance of both the anode and cathode will decline when the pressure drops; Figure 3 and Figure 6 It can be seen from the Nyquist plots of EIS of Figure 4 and Figure 7 that when the pressure drops, the ohmic impedance of both the anode and cathode increases; while in the THD spectrograms of Figure 4 and Figure 7 it can be found that in the frequency range of 100 Hz - 100 mHz, the changing trends of the THD of the anode and cathode are opposite when the pressure drops. When the pressure drops, the THD of the anode increases significantly in this frequency range, while the THD of the cathode decreases significantly in this frequency range. The opposite changing trends of the THD of the anode and cathode in the same frequency range can be used as the basis for diagnosing which specific part of the anode and cathode fails due to pressure loss by combining the total harmonic distortion technology and the electrochemical impedance spectroscopy technology, proving the feasibility of applying the total harmonic distortion technology in AEM water electrolysis.

[0037] Combined with the magnitude of the current density selected during the current AEM water electrolysis catalyst stability test, select 500 mA / cm² of direct current as the test operating point for the examples. The EIS test results under different amplitude conditions are as shown in Figure 8 and the THD test results are as shown in Figure 9 ; it can be seen that the amplitude has almost no influence on the EIS results, but has a great influence on the THD spectrograms. From the THD spectrograms, as the amplitude increases to 500 mA, that is, 125 mA / cm², the THD value has basically excluded the influence of noise in the medium and low frequencies. Therefore, select an amplitude of 125 mA / cm², which is 25% of the magnitude of the direct current. To ensure data unity, subsequent AEM water electrolysis membrane electrode tests are carried out according to this result.

[0038] The first failure mode created is the influence of pressure fluctuations; during the operation of the membrane electrode, since the anode is the liquid inlet side, the pressure is blocked on the cathode side, and hydrogen is selected as the pressure-blocking gas. After the pressure condition stabilizes, conduct three tests.

[0039] As shown in Figure 10 , as the pressure drops, the performance of the membrane electrode declines; it can be seen from Figure 11 that the ohmic impedance increases as the pressure drops, corresponding to the LSV results; it can be seen from Figure 12It can be seen from the THD spectrogram that the THD value decreases from 100 Hz to 100 mHz as the pressure decreases, which corresponds to the test results of the pressure fluctuation diagnosis of the single anode and cathode electrodes above, proving the correctness of the test results of the single anode and cathode, and also indicating that the specific frequency domain range of this failure mode is 100 Hz - 100 mHz, and the change trend is to decrease as the pressure decreases.

[0040] The second failure mode created is the dry burning of the diaphragm, i.e., the influence of electrolyte metering; the data acquisition method is to use a high-pressure constant-current pump to control different electrolyte inlet flow rates to achieve different metering, and a portable heating table is used to keep the membrane electrode at a constant temperature; three tests are carried out after stabilizing under each electrolyte flow rate condition, and the test parameter settings are the same as above.

[0041] As Figure 13 shown, as the inlet rate decreases from 2 mL / min to 0.1 mL / min, the performance of the membrane electrode improves. Although the performance is the best at the minimum inlet rate, after the experiment under this condition is completed, when the membrane electrode is disassembled, it is found that the edge of the AEM has cracked and the mechanical strength has decreased greatly, and it cannot be used continuously. It can be seen from Figure 14 the EIS diagram that as the inlet rate decreases, the impedance decreases; the THD spectrogram also has a characteristic frequency domain range of change with the change of the inlet rate. It can be seen from Figure 15 that as the inlet volume decreases, the THD increases from 631 Hz to 100 mHz. From this, it can be found that the characteristic frequency domain range of the failure caused by metering is 631 Hz - 100 mHz, and the THD value becomes larger when the diaphragm dry burns.

[0042] The third failure mode created is the influence of temperature change. Different temperature conditions are controlled, and LSV, EIS, and THD tests are carried out after stabilizing under each temperature condition. The test parameter settings are the same as in step two of the present invention; three tests are carried out after the temperature stabilizes.

[0043] As Figure 16 shown, when the temperature rises, the performance of the AEM water electrolysis membrane electrode improves significantly. It can be seen from Figure 17 the test results that as the temperature rises, the ohmic impedance decreases significantly, and it can be seen from Figure 18 that when the temperature rises, the THD value of the membrane electrode increases significantly from 2510 Hz to 100 mHz. The characteristic frequency domain range of the failure caused by temperature is 2510 Hz - 100 mHz, and the THD increases in this frequency domain range when the temperature rises.

[0044] The test results of these several failure modes are summarized in Table 1. When the cathode of the membrane electrode loses pressure, the performance decreases, the impedance increases, and the THD decreases in the range of 100 Hz - 100 mHz. When the anode loses pressure, the performance decreases and the impedance increases, and the THD value increases in the range of 100 Hz - 100 mHz. When the temperature rises and the diaphragm dries out, that is, when the electrolyte metering decreases, the performance improves and the impedance also decreases. At this time, it is impossible to distinguish solely based on EIS. By combining with the THD spectrogram, it can be seen that these two failure modes have different characteristic frequency domain intervals. When the temperature rises, the THD value increases significantly in the range of 2510 Hz - 100 mHz, and when the diaphragm dries out by burning, the THD increases in the range of 631 Hz - 100 mHz. That is, the characteristic frequency domain interval for temperature change is 2510 Hz - 631 Hz, the characteristic frequency domain interval for metering change is 631 Hz - 100 Hz, and the characteristic frequency domain interval for pressure change is 100 Hz - 100 mHz. Therefore, by combining the EIS diagram and the THD diagram and finding the change trend in the characteristic frequency domain interval on the THD diagram, these several failure modes can be effectively distinguished.

[0045] Table 1 Summary of changes in LSV, EIS, and THD of AEM water electrolysis membrane electrode under four failure modes

[0046] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable ordinary technical personnel in the field to understand the content of the present invention and implement it accordingly. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for diagnosing failure of an AEM water electrolysis membrane electrode, characterized in that: include: Step 1: When the AEM water electrolysis membrane electrode is operating normally, carrier waves with different AC amplitudes are input to perform carrier analysis, determine the AC amplitude, and obtain standard spectra of electrochemical AC impedance and total harmonic distortion under normal conditions; Step 2: monitor the operation of the AEM water electrolysis membrane electrode, enter the diagnostic mode after performance changes occur, input the carrier, perform electrochemical AC impedance test and total harmonic distortion test at the same time; Step 3, Fourier transform the output electrochemical AC impedance signal to obtain an electrochemical AC impedance spectrum, and process the output harmonic signal to obtain a total harmonic distortion spectrum; Step 4: Based on the total harmonic distortion spectrum, combined with the electrochemical impedance spectrum, and compared with the standard spectrum obtained in step 1, the failure type of the AEM water electrolysis membrane electrode is identified.

2. A method for diagnosing failure of an AEM water electrolysis membrane electrode according to claim 1, characterized in that: In step 1, the AC current amplitude is determined to be at least 25% of the DC current amplitude.

3. The AEM water electrolysis membrane electrode failure diagnosis method according to claim 1, characterized in that: In step 2, whether performance changes occur is mainly determined by comparing the difference between the current density obtained by testing at the same potential and the current density during normal operation.

4. A method for diagnosing failure of an AEM water electrolysis membrane electrode according to claim 1, characterized in that: In step 1 and step 2, the input carrier is a sinusoidal carrier.

5. The AEM water electrolysis membrane electrode failure diagnosis method according to claim 1, characterized in that: In step 2, the two tests performed simultaneously after entering the diagnostic mode are performed in the constant current mode.

6. A method for diagnosing failure of an AEM water electrolysis membrane electrode according to claim 1, characterized in that: In step 2, the frequency domain range of the electrochemical AC impedance test and the total harmonic distortion test is 100kHz-100mHz, from high frequency to low frequency.

7. The AEM water electrolysis membrane electrode failure diagnosis method according to claim 1, characterized in that: In step 4, the method for identifying the type of AEM water electrolysis membrane electrode failure is: when anode pressure loss occurs, performance decreases, ohmic impedance increases, and total harmonic distortion value increases in the frequency domain range of 100Hz-100mHz.

8. The AEM water electrolysis membrane electrode failure diagnosis method according to claim 1, characterized in that: In step 4, the method for identifying the failure type of the AEM water electrolysis membrane electrode is as follows: when cathode pressure loss occurs, performance decreases, ohmic impedance increases, and total harmonic distortion value decreases in the frequency domain range of 100Hz-100mHz.

9. The AEM water electrolysis membrane electrode failure diagnosis method according to claim 1, characterized in that: In step 4, the method for identifying the type of failure of the AEM water electrolysis membrane electrode is as follows: when the membrane electrode electrolyte metering decreases, that is, the liquid inlet rate decreases, the ohmic impedance decreases, and the total harmonic distortion value increases in the frequency range of 631Hz-100mHz as the liquid inlet rate decreases.

10. The AEM water electrolysis membrane electrode failure diagnosis method according to claim 1, characterized in that: In step 4, the method for identifying the type of AEM water electrolysis membrane electrode failure is: when the membrane electrode temperature suddenly rises, the ohmic impedance decreases and the total harmonic distortion value increases in the frequency range of 2510Hz-100mHz.

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