Diagnostic method for electrolytic units, diagnostic method for electrolytic devices, diagnostic device for electrolytic units, operating system, and diagnostic program for electrolytic units.

Abstract

To provide a diagnostic method for an electrolytic unit that enables appropriate understanding of the deterioration state and operating status of the electrolytic unit. [Solution] In this embodiment, a diagnostic method is provided for an electrolytic unit in which an electrochemical reaction occurs using a supply material provided by power input. In the diagnostic method, the film resistance due to the film, the anode resistance due to the anode, and the cathode resistance due to the cathode are estimated for the electrolytic unit based on the measurement results of the impedance frequency characteristics. The diagnostic method determines the operating status and deterioration state of the electrolytic unit based on the time changes of the film resistance, anode resistance, and cathode resistance.

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for diagnosing an electrolysis unit, a method for diagnosing an electrolysis device, a diagnostic device for an electrolysis unit, an operation system, and a diagnostic program for an electrolysis unit.

Background Art

[0002] An electrolysis unit in which an electrochemical reaction using a supply material occurs by input of electric power is used in a state where the supply material is being supplied. For example, in an electrolysis unit (water electrolysis unit) to which water is supplied as a supply material, electrolysis of water occurs as an electrochemical reaction by input of electric power. Then, hydrogen or the like is generated as a product of the electrochemical reaction in the electrolysis unit, and the generated hydrogen or the like is recovered.

[0003] In the electrolysis unit as described above, when operation is continued, deterioration of materials or the like occurs and the deterioration progresses. Further, in a state where the electrolysis unit is being operated, operation abnormalities such as overheating, overcurrent, and insufficient supply of the supply material may occur in the electrolysis unit. Therefore, in a state where the electrolysis unit is being operated, for example, it is required to appropriately grasp the deterioration state and operation situation of the electrolysis unit, such as by appropriately grasping the occurrence of material deterioration and operation abnormalities.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem that this invention aims to solve is to provide a diagnostic method for an electrolytic unit, a diagnostic method for an electrolytic device, a diagnostic device for an electrolytic unit, an operating system, and a diagnostic program for an electrolytic unit that enable appropriate understanding of the deterioration state and operating status of the electrolytic unit. [Means for solving the problem]

[0006] In this embodiment, a diagnostic method is provided for an electrolytic unit in which an electrochemical reaction occurs using a supply material provided by power input. In the diagnostic method, the film resistance due to the film, the anode resistance due to the anode, and the cathode resistance due to the cathode are estimated for the electrolytic unit based on the measurement results of the impedance frequency characteristics. Based on the time changes of the film resistance, anode resistance, and cathode resistance, the diagnostic method determines the operating status and deterioration state of the electrolytic unit. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing an example of an operating system according to the first embodiment. [Figure 2] Figure 2 is a flowchart illustrating an example of the process for estimating the resistance component of an electrolytic unit, which is performed by a processing circuit or the like in the first embodiment. [Figure 3] Figure 3 is a schematic diagram showing an example of an equivalent circuit of an equivalent circuit model used to estimate multiple resistance components of an electrolytic unit in the first embodiment. [Figure 4] Figure 4 is a schematic diagram illustrating an example of a process for estimating multiple resistance components of an electrolytic unit, which is performed by a processing circuit or the like in the first embodiment. [Figure 5] Figure 5 is a flowchart illustrating an example of a determination process regarding the operating status and deterioration state of the electrolytic unit, which is performed by a processing circuit or the like in the first embodiment. [Figure 6]Figure 6 is a schematic diagram showing the verification results in the verification related to the first embodiment, etc. [Figure 7] Figure 7 is a flowchart that schematically shows an example of the determination process regarding the operating status and deterioration state of the electrolytic unit, which is performed by the processing circuit etc. in the first modified example. [Figure 8] Figure 8 is a flowchart illustrating an example of the processing related to the input of diagnostic current to the electrolytic unit, which is performed by the processing circuit and the like in the third modified example. [Figure 9] Figure 9 is a schematic diagram illustrating an example of the timing for inputting diagnostic current to the electrolytic unit in the third modified example. [Figure 10] Figure 10 is a schematic diagram showing the configuration of the electrolytic apparatus according to the fourth modified example. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the drawings. (First Embodiment) First, as an example of an embodiment, a first embodiment will be described. Figure 1 is a schematic diagram showing an example of an operating system 1 according to the first embodiment. As shown in Figure 1, the operating system 1 includes an electrolytic unit 2, and the electrolytic unit 2 is operated in the operating system 1. In the example in Figure 1, the electrolytic unit 2 is composed of an electrolytic block or electrolytic module in which a plurality of electrolytic cells 3 are electrically connected. The electrolytic unit 2 is formed with at least one of a series connection structure in which a plurality of electrolytic cells 3 are electrically connected in series, and a parallel connection structure in which a plurality of electrolytic cells 3 are electrically connected in parallel. In one example, the electrolytic unit 2 may be formed from a single electrolytic cell 3.

[0009] The electrolytic cell 3 constituting the electrolytic unit 2 comprises an anode and a cathode. In the electrolytic cell 3, a membrane such as an ion exchange membrane or an electrolyte membrane is interposed between the anode and the cathode. Furthermore, in the electrolytic cell 3, at least one of the anode and the cathode is equipped with a catalyst, and both the anode and the cathode may be equipped with a catalyst. In the electrolytic cell 3, as the catalyst for the cathode, for example, a metal or alloy containing any of the elements such as Pt, Ru, Rh, Pd, Au, Os, or Ir is used, and as the catalyst for the anode, for example, a metal, alloy, or oxide containing any of the elements such as Ir, Ru, Rh, Pd, Au, or Os is used.

[0010] The electrolytic unit 2 can be connected to the power grid 5, and when the electrolytic unit 2 is in operation, power is input to the electrolytic unit 2 from the power grid 5. Examples of the power grid 5 include power grids that supply power from generators that generate electricity using natural energy such as solar and wind power, and power grids that supply power from power plants.

[0011] The operating system 1 is equipped with a power conditioner 6 as a power adjustment unit. The power conditioner 6 converts power from the power grid 5 and inputs the converted power to the electrolytic unit 2 as operating power. In this process, the power conditioner 6 converts the AC power from the power grid 5 into DC power within a voltage range corresponding to the electrolytic unit 2 by AC / DC conversion and voltage transformation, and inputs the converted DC power to the electrolytic unit 2. Furthermore, in the operating system 1, the magnitude of the power input to the electrolytic unit 2 as operating power changes in accordance with the operating state of the power conditioner 6. As a result, the magnitude of the operating current (current) input to the electrolytic unit 2 and the magnitude of the voltage applied to the electrolytic unit 2 change in accordance with the operating state of the power conditioner 6, and the current and voltage of the electrolytic unit 2 are adjusted by the power conditioner 6.

[0012] Furthermore, a supply is provided to the electrolytic unit 2, and in the example shown in Figure 1, water is supplied to the electrolytic unit 2 as the supply. The electrolytic unit 2 then becomes a water electrolytic unit, and each of the electrolytic cells 3 that make up the electrolytic unit 2 becomes a water electrolytic cell. In the operation of the electrolytic unit 2, power is input to the electrolytic unit 2 while a supply is being provided to it. When power is input to the electrolytic unit 2 while a supply is being provided, an electrochemical reaction using the supply occurs in the electrolytic unit 2. In the example shown in Figure 1, when power is input to the electrolytic unit 2, the electrolysis of water occurs as an electrochemical reaction in each of the electrolytic cells 3 that make up the electrolytic unit 2.

[0013] When electrochemical reactions such as the electrolysis of water are occurring in the electrolytic unit 2 due to the input of power to the electrolytic unit 2, the anode of each electrolytic cell 3 constituting the electrolytic unit 2 has a relatively higher potential than the cathode. At this time, the potentials of the anode and cathode in each electrolytic cell 3 change in accordance with the materials constituting the electrodes and the operating conditions of the electrolytic unit 2. In each electrolytic cell 3, when the electrolysis of water is taking place, that is, when the electrolytic unit 2 is in operation, at least hydrogen ions and oxygen are generated at the anode. Then, in each electrolytic cell 3, the hydrogen ions generated at the anode move to the cathode side through the membrane, and hydrogen is generated at the cathode. In the electrolytic unit 2, the products of the electrochemical reaction are recovered, and in the example in Figure 1, hydrogen, which is a product of the electrolysis of water, is recovered.

[0014] The operation system 1 is provided with a current measurement circuit 7 and a voltage measurement circuit 8. The current measurement circuit 7 includes, for example, a current sensor, etc., and the voltage measurement circuit 8 includes, for example, a voltage sensor, etc. In a state where the operating power is input to the electrolysis unit 2, etc., the current measurement circuit 7 measures the current of the electrolysis unit 2, that is, the current input to the electrolysis unit 2. Also, in a state where the operating power is input to the electrolysis unit 2, etc., the voltage measurement circuit 8 measures the voltage of the electrolysis unit 2, that is, the voltage applied to the electrolysis unit 2.

[0015] Moreover, the operation system 1 includes a water tank 11, a supply pump 12, and a flow rate sensor 13. The water tank 11 stores water, which is the supply to the electrolysis unit 2. Then, when the supply pump 12 operates, the water in the water tank 11 is supplied to the electrolysis unit 2. Corresponding to the operating state of the supply pump 12, the supply state of water to the electrolysis unit 2, including the supply amount of water to the electrolysis unit 2, changes. Also, the flow rate sensor 13 detects the supply amount of water, which is the supply, to the electrolysis unit 2, for example, by detecting the flow rate of water from the supply pump 12 to the electrolysis unit 2.

[0016] Furthermore, the operation system 1 is provided with a temperature adjustment unit 15, a flow path 16, and a temperature sensor 17, and the temperature adjustment unit 15 includes a heat exchanger 18. A cooling fluid such as cooling water or cooling gas flows through the flow path 16. The temperature adjustment unit 15 adjusts the temperature of the electrolysis unit 2 by transferring heat between the cooling fluid flowing through the flow path 16 and the electrolysis unit 2 using the heat exchanger 18, etc. Corresponding to the operating state of the temperature adjustment unit 15 including the heat exchanger 18, the temperature of the electrolysis unit 2 changes. Also, the temperature sensor 17 detects the temperature of the electrolysis unit 2.

[0017] In this embodiment, the operating system 1 includes a diagnostic device 20 which acts as a processing unit. The diagnostic device 20 performs processing related to the diagnosis of the operating electrolytic unit 2. Therefore, in the operating system 1, the electrolytic unit 2 is the target of diagnosis by the diagnostic device 20. In the example shown in Figure 1, the diagnostic device 20 is composed of a computer such as a server and includes a processing circuit 21 and a storage medium 22.

[0018] The processing circuit 21 is composed of a processor or integrated circuit, and the processor or other components constituting the processing circuit 21 include any of the following: CPU (Central Processing Unit), ASIC (Application Specific Integrated Circuit), microcontroller, FPGA (Field Programmable Gate Array), and DSP (Digital Signal Processor). The processing circuit 21 may be composed of one processor or multiple processors. The storage medium 22 may be a main memory such as memory, or an auxiliary storage device. In the diagnostic device 20, only one storage medium 22 may be provided, or multiple storage mediums may be provided.

[0019] In the diagnostic device 20, the processing circuit 21 performs processing by executing programs stored in the storage medium 22. The storage medium 22 also stores data used for processing by the processing circuit 21. In one example, the program executed by the processing circuit 21 in the diagnostic device 20 may be stored on a computer (server) connected via a network such as the Internet, or on a server in a cloud environment. In this case, the processing circuit 21 downloads the program via the network.

[0020] In the example shown in Figure 1, a data management program 23 and a diagnostic program 25 are stored in the storage medium 22 as programs to be executed by the processing circuit 21. The processing circuit 21 writes data to the storage medium 22 and reads data from the storage medium 22 by executing the data management program 23. The diagnostic program 25 also includes a resistance estimation program 26 and a judgment program 27. In diagnosing the electrolytic unit 2, the processing circuit 21 performs the processing described later based on the diagnostic program 25.

[0021] In one example, the diagnostic device 20 is composed of multiple computers, such as multiple servers, and the processors of the multiple computers cooperate to perform the processing described later based on the diagnostic program 25. When the diagnostic device 20 is composed of multiple computers, the multiple computers that make up the diagnostic device 20 can communicate with each other wirelessly or via wired connections.

[0022] In another example, at least a portion of the diagnostic device 20 is configured from a cloud server in a cloud environment. The infrastructure of the cloud environment consists of virtual processors such as virtual CPUs and cloud memory. When at least a portion of the diagnostic device 20 is configured from a cloud server, at least a portion of the processing described later, based on the diagnostic program 25, is performed by the virtual processor. In addition, the program executed by the virtual processor, and the data used for processing by the virtual processor, are stored in cloud memory.

[0023] In one example, the diagnostic device 20 may be provided with a user interface. In this case, the user interface allows users of the operating system 1 to input various operations, including operations related to the operation and diagnosis of the electrolysis unit 2. For this reason, the user interface is provided with an operation section, such as buttons, a mouse, a touch panel, or a keyboard, which allows users to input operations. The user interface is also provided with a notification section that provides information related to the electrolysis unit 2. The notification section provides information through either a screen display or sound emission. The user interface may be provided separately from the computer and other components that make up the diagnostic device 20. Furthermore, the user interface is not necessarily required.

[0024] In the example shown in Figure 1, the processing circuit 21 of the diagnostic device 20 acquires the measurement results of the current of the electrolytic unit 2 from the current measurement circuit 7 and the measurement results of the voltage of the electrolytic unit 2 from the voltage measurement circuit 8. Based on the measurement results of the current and voltage of the electrolytic unit 2, the processing circuit 21 controls the operation of the power conditioner 6 and adjusts the magnitude of the operating power input to the electrolytic unit 2. As a result, the operating current input to the electrolytic unit 2 and the voltage applied to the electrolytic unit 2 are adjusted.

[0025] Furthermore, in the example shown in Figure 1, the processing circuit 21 acquires the detection result of the water supply amount from the flow sensor 13. Based on the detection result of the water supply amount to the electrolysis unit 2, the processing circuit 21 controls the operation of the supply pump 12 and adjusts the flow rate of water supplied to the electrolysis unit 2. The processing circuit 21 also acquires the detection result of the temperature of the electrolysis unit 2 from the temperature sensor 17. Based on the detection result of the temperature of the electrolysis unit 2, the processing circuit 21 controls the operation of the temperature control unit 15, including the heat exchanger 18, and adjusts the temperature of the electrolysis unit 2.

[0026] Furthermore, the operating system 1 is equipped with a diagnostic power supply circuit 28. During the diagnosis of the electrolytic unit 2, the power supply circuit 28 generates diagnostic power used for diagnosing the electrolytic unit 2, for example, by converting power from the power system 5 into diagnostic power. Then, during the diagnosis of the electrolytic unit 2, the processing circuit 21, etc., controls the operation of the power supply circuit 28 to input the diagnostic power to the electrolytic unit 2. When the diagnostic power is input to the electrolytic unit 2, a diagnostic current is input to the electrolytic unit 2. When operating power is input to the electrolytic unit 2, the diagnostic power from the power supply circuit 28 is input to the electrolytic unit 2, and the diagnostic current is superimposed on the operating current input to the electrolytic unit 2.

[0027] In this embodiment, the diagnostic program 25 is executed by the processing circuit 21, etc., so that the diagnostic process is repeatedly performed over time on the operating electrolytic unit 2. In one example, the diagnostic process is performed periodically on the electrolytic unit 2 that is to be diagnosed. In one diagnostic process for the electrolytic unit 2, the resistance estimation process of the electrolytic unit 2 is performed by executing the resistance estimation program 26 included in the diagnostic program 25.

[0028] Then, in a single diagnostic process for the electrolytic unit 2, after estimating the resistance component, the judgment program 27 included in the diagnostic program 25 is executed, and a judgment process is performed on the electrolytic unit 2 based on the estimated resistance component. In the judgment process for the electrolytic unit 2, the operating status and deterioration state of the electrolytic unit 2 are determined. As the diagnostic process described above is repeated over time, the resistance component estimation process and the judgment process regarding the operating status and deterioration state are repeated over time for the operating electrolytic unit 2.

[0029] Figure 2 is a flowchart schematically showing an example of the estimation process for the resistance component of the electrolytic unit 2, which is performed by the processing circuit 21, etc., in the first embodiment. The estimation process in the example in Figure 2 is performed in each of the diagnostic processes for the electrolytic unit 2 that are repeatedly performed over time, before executing the determination process regarding the operating status and deterioration state of the electrolytic unit 2, which will be described later. When the process in the example in Figure 2 is started, the processing circuit 21, etc., controls the drive of the power supply circuit 28, etc., to input a diagnostic current from the power supply circuit 28 to the electrolytic unit 2 (S101). The diagnostic current is a current signal corresponding to the measurement of the impedance of the electrolytic unit 2.

[0030] In one example, an alternating current (AC) with a periodically changing current value is input to the electrolytic unit 2 as a diagnostic current. In this case, the AC current is input to the electrolytic unit 2 in the form of a sine wave, triangular wave, or sawtooth wave. When an AC current is generated as a diagnostic current, the processing circuit 21, etc., adjusts the frequency of the AC current input to the electrolytic unit 2 by controlling the drive of the power supply circuit 28, etc. Then, the processing circuit 21, etc., inputs the AC current that becomes the diagnostic current to the electrolytic unit 2 in a state where the AC current changes over time to multiple frequencies. In another example, a pseudo-random pulse signal such as an M-sequence signal is input to the electrolytic unit 2 as a diagnostic current. In this case, the pseudo-random pulse signal input to the electrolytic unit 2 contains multiple types of pulses with different pulse widths relative to each other.

[0031] Then, with the diagnostic current input to the electrolytic unit 2, the processing circuit 21 etc. causes the current measurement circuit 7 to measure the current of the electrolytic unit 2 and the voltage measurement circuit 8 to measure the voltage of the electrolytic unit 2. The processing circuit 21 etc. then acquires time-series data showing the time changes (time history) of the current and voltage of the electrolytic unit 2 with the diagnostic current input to the electrolytic unit 2 (S102). The time changes of the current of the electrolytic unit 2 shown in the time-series data are generated based on the measurement results of the current measurement circuit 7, and the time changes of the voltage of the electrolytic unit 2 shown in the time-series data are generated based on the measurement results of the voltage measurement circuit 8.

[0032] In one example, while the operating current is being input to the electrolytic unit 2, that is, while an electrochemical reaction is occurring in the electrolytic unit 2 due to the input of operating power, a diagnostic current is input to the electrolytic unit 2. In this case, the diagnostic current corresponding to the impedance measurement is superimposed on the operating current that is input to the electrolytic unit 2 to generate the electrochemical reaction. Therefore, in parallel with the operation of the electrolytic unit 2, time-series data showing the time changes in the current and voltage of the electrolytic unit 2 while the diagnostic current is being input is measured.

[0033] Once the aforementioned time-series data (measurement data) is acquired, the processing circuit 21, etc., analyzes the acquired time-series data to measure the frequency characteristics of the impedance of the electrolytic unit 2 (S103). Note that once the time-series data is acquired, the input of the diagnostic current to the electrolytic unit 2 is stopped. In one example, in measuring the frequency characteristics of the impedance of the electrolytic unit 2, the time change of the current of the electrolytic unit 2 shown in the aforementioned time-series data, i.e., the current time-series data included in the time-series data, is Fourier transformed to generate current spectrum data showing the frequency characteristics of the current of the electrolytic unit 2. Then, the time change of the voltage of the electrolytic unit 2 shown in the aforementioned time-series data, i.e., the voltage time-series data included in the time-series data, is Fourier transformed to generate voltage spectrum data showing the frequency characteristics of the voltage of the electrolytic unit 2.

[0034] Then, calculations are performed using the current spectrum data and voltage spectrum data of the electrolytic unit 2 to calculate impedance spectrum data that shows the frequency characteristics of the impedance of the electrolytic unit 2. The impedance spectrum data of the electrolytic unit 2 is calculated, for example, by dividing the voltage spectrum data of the electrolytic unit 2 by the current spectrum data of the electrolytic unit 2. The impedance spectrum data of the electrolytic unit 2 shows the impedance of the electrolytic unit 2 at each of several frequencies.

[0035] A method for calculating the frequency characteristics of a battery's impedance using time-series data of current current and time-series data of voltage is shown in Patent Document 3 (Japanese Patent Application Publication No. 2014-126532). In the embodiments, the frequency characteristics of the impedance of the electrolytic unit 2 may be calculated in the same manner as the calculation of the frequency characteristics of the battery's impedance in Patent Document 3. In this case, the processing circuit 21 calculates the autocorrelation function of the current spectrum data of the electrolytic unit 2, and also calculates the cross-correlation function between the current spectrum data and voltage spectrum data of the electrolytic unit 2. Then, the processing circuit 21 calculates the frequency characteristics of the impedance of the electrolytic unit 2 using the calculated autocorrelation function and cross-correlation function.

[0036] In one example, an AC current is input to the electrolytic unit 2 at multiple frequencies as a diagnostic current, and the processing circuit 21 calculates the impedance of the electrolytic unit 2 for each of the multiple frequencies based on the current and voltage values ​​of the electrolytic unit 2 shown by time-series data (measurement data), etc. In this case, for example, the impedance of the electrolytic unit 2 is calculated by dividing the voltage value of the electrolytic unit 2 by the current value for each of the multiple frequencies. This allows the frequency characteristics of the impedance of the electrolytic unit 2, which show the impedance of the electrolytic unit 2 at each of the multiple frequencies, to be calculated.

[0037] When the frequency characteristics of the impedance of the electrolytic unit 2 are measured, the processing circuit 21, etc., estimates the film resistance Rm, anode resistance Ra, and cathode resistance Rc as resistance components of the electrolytic unit 2 based on the measurement results of the impedance frequency characteristics (S104). The film resistance Rm is the resistance component caused by the film of the electrolytic cell 3 that constitutes the electrolytic unit 2. The anode resistance Ra is the resistance component caused by the anode of the electrolytic cell 3 that constitutes the electrolytic unit 2, and is mainly the resistance component caused by the catalyst of the anode. The cathode resistance Rc is the resistance component caused by the cathode of the electrolytic cell 3 that constitutes the electrolytic unit 2, and is mainly the resistance component caused by the catalyst of the cathode.

[0038] The estimation of multiple resistance components of the electrolytic unit 2, namely the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2, is performed, for example, using measurement results of the frequency characteristics of the impedance of the electrolytic unit 2 and an equivalent circuit model of the electrolytic unit 2. The equivalent circuit model of the electrolytic unit 2 is stored in a storage medium 22, etc., and the equivalent circuit model shows the equivalent circuit of the electrolytic unit 2. In the equivalent circuit of the equivalent circuit model, circuit parameters (electrical characteristic parameters) including the resistance components to be estimated are set. Therefore, in the equivalent circuit, circuit parameters including film resistance Rm, anode resistance Ra, and cathode resistance Rc are set.

[0039] Figure 3 is a schematic diagram showing an example of an equivalent circuit of an equivalent circuit model used to estimate multiple resistance components of the electrolytic unit 2 in the first embodiment. In the example equivalent circuit of Figure 3, the film resistance Rm, anode resistance Ra, and cathode resistance Rc are set as circuit parameters. In addition, the capacitance Ca, which is a capacitive component originating from the anode, and the capacitance Cc, which is a capacitive component originating from the cathode, are also set as circuit parameters in the example equivalent circuit of Figure 3. Furthermore, the Warburg impedance Zw, which is the impedance in the diffusion process of ions such as hydrogen ions, is set as a circuit parameter. In the electrolytic unit 2, the resistance component of the Warburg impedance Zw becomes the diffusion resistance.

[0040] In the equivalent circuit model used to estimate the multiple resistance components of the electrolytic unit 2, the relationship between the circuit parameters set in the equivalent circuit and the impedance of the electrolytic unit 2 is shown, and for example, a relational formula for calculating the impedance of the electrolytic unit 2 using the circuit parameters and frequency is shown. In estimating the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2, the processing circuit 21, etc., performs fitting calculations using, for example, the relationship between the circuit parameters and impedance shown in the equivalent circuit model, and the measurement results of the frequency characteristics of the impedance of the electrolytic unit 2.

[0041] In fitting calculations using an equivalent circuit model, the circuit parameters set in the equivalent circuit containing the multiple resistance components to be estimated are used as variables, and calculations are performed to calculate the variable circuit parameters. Furthermore, in the fitting calculations, for each of the multiple frequencies in which impedance is measured, the values ​​of the variable circuit parameters are calculated so that the difference between the calculated impedance value calculated using the relationship shown in the equivalent circuit model and the measured impedance value is as small as possible. By calculating the circuit parameters through fitting calculations, the film resistance Rm, anode resistance Ra, and cathode resistance Rc are calculated as multiple resistance components for the electrolytic unit 2.

[0042] Figure 4 is a schematic diagram illustrating an example of the process for estimating multiple resistance components of the electrolytic unit 2, which is performed by the processing circuit 21, etc., in the first embodiment. In Figure 4, a graph is shown in which the horizontal axis represents the real component of impedance Zre and the vertical axis represents the imaginary component of impedance -Zim. Therefore, in Figure 4, the measurement results of the frequency characteristics of the impedance of the electrolytic unit 2 are shown as a complex impedance plot (Cole-Cole plot). In addition, in Figure 4, the measurement results of the frequency characteristics of the impedance of the electrolytic unit 2 are shown as a solid line.

[0043] As shown in Figure 4, in the complex impedance plot showing the measured frequency characteristics of the impedance of the electrolytic unit 2, a convex arc portion A is formed on the negative side of the imaginary component of the impedance. Arc portion A has a convex vertex T, and at the convex vertex T, the imaginary component of the impedance is a negative value. In addition, in the complex impedance plot, there is an intersection point D that intersects the horizontal axis, which is the axis of the real component, on the higher frequency side of the convex vertex T of arc portion A.

[0044] In the example shown in Figure 4, as described above, by performing fitting calculations using the equivalent circuit model, the value of the real component of the impedance at the intersection D of the complex impedance plot (a positive value) is calculated as the film resistance Rm of the electrolytic unit 2. Furthermore, in the complex impedance plot of the example shown in Figure 4, the impedance component on the lower frequency side relative to the arc portion A, i.e., the impedance component in region α, corresponds to the Warburg impedance.

[0045] As described above, by performing fitting calculations using the equivalent circuit model, the anode impedance and cathode impedance are separated from the complex impedance plot showing the measured frequency characteristics of the impedance of electrolytic unit 2. As a result, the arc portion A of the complex impedance plot is separated into the arc portion Aa representing the anode impedance and the arc portion Ac representing the cathode impedance. In Figure 4, the arc portion Aa representing the anode impedance is shown as a dashed line, and the arc portion Ac representing the cathode impedance is shown as a dashed line.

[0046] Furthermore, in the example shown in Figure 4, as described above, by performing fitting calculations using the equivalent circuit model, the diameter of the arc portion Aa of the anode impedance is calculated as the anode resistance Ra of the electrolytic unit 2, and the diameter of the arc portion Ac of the cathode impedance is calculated as the cathode resistance Rc of the electrolytic unit 2. Here, the arc portion Aa of the anode impedance is convex to the negative side of the imaginary component of the impedance, and at the vertex Ta of the convex shape of the arc portion Aa, the imaginary component of the impedance is a negative value. Similarly, the arc portion Ac of the cathode impedance is convex to the negative side of the imaginary component of the impedance, and at the vertex Tc of the convex shape of the arc portion Ac, the imaginary component of the impedance is a negative value.

[0047] Furthermore, a method for calculating the resistance component of a battery by performing fitting calculations using the measurement results of the frequency characteristics of the battery's impedance and the relationship between the circuit parameters (circuit constants) shown in the equivalent circuit model of the battery and the impedance, thereby calculating the values ​​of the circuit parameters set in the equivalent circuit model, is shown in Patent Document 4 (Japanese Patent Application Publication No. 2017-106889). In the embodiments, the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2 may be calculated in the same manner as the calculation of the resistance component of the battery in Patent Document 4.

[0048] Figure 5 is a flowchart illustrating an example of a determination process regarding the operating status and deterioration state of the electrolytic unit 2, performed by the processing circuit 21, etc., in the first embodiment. The determination process in the example in Figure 5 is performed in each of the diagnostic processes for the electrolytic unit 2 that are repeatedly performed over time, after the aforementioned estimation process for the resistance component of the electrolytic unit 2 has been executed. The determination process in the example in Figure 5 is performed based on the estimation results of the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2 in the resistance component estimation process.

[0049] When the processing of the example shown in Figure 5 is started, the processing circuit 21, etc., calculates the time change ratios γm, γa, and γc for the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2 as parameters related to time change (S111). Each of the time change ratios γm, γa, and γc, which are parameters related to time change, is calculated as a judgment parameter in the judgment process. Here, the time change ratio γm for film resistance Rm is calculated as the ratio of the estimated result of film resistance Rm in the real-time diagnostic process to the estimated result of film resistance Rm in the previous diagnostic process, and this ratio is calculated as the final value. If the film resistance Rm remains unchanged from the previous diagnostic process, the time change ratio γm is 1. If the film resistance Rm has increased from the previous diagnostic process, the time change ratio γm will be a value greater than 1, and if the film resistance Rm has decreased from the previous diagnostic process, the time change ratio γm will be a value less than 1.

[0050] Furthermore, the time-varying ratio γa of the anode resistance Ra is calculated as the ratio of the estimated anode resistance Ra from the real-time diagnostic process to the estimated anode resistance Ra from the previous diagnostic process. If the anode resistance Ra remains unchanged from the previous diagnostic process, the time-varying ratio γa is 1. If the anode resistance Ra has increased since the previous diagnostic process, the time-varying ratio γa will be greater than 1, and if the anode resistance Ra has decreased since the previous diagnostic process, the time-varying ratio γa will be less than 1.

[0051] Furthermore, the time-varying ratio γc of the cathode resistance Rc is calculated as the ratio of the estimated cathode resistance Rc in the real-time diagnostic process to the estimated cathode resistance Rc in the previous diagnostic process. If the cathode resistance Rc remains unchanged since the previous diagnostic process, the time-varying ratio γc is 1. If the cathode resistance Rc has increased since the previous diagnostic process, the time-varying ratio γc will be greater than 1, and if the cathode resistance Rc has decreased since the previous diagnostic process, the time-varying ratio γc will be less than 1.

[0052] In one example, in the calculation of the time-varying multipliers γm, γa, and γc in S111, the processing circuit 21, etc., uses the calculated values ​​of the time-varying multipliers from each of the most recent reference count Nref (Nref is a natural number greater than or equal to 2), including the real-time diagnostic processing, as provisional values ​​to calculate the final value of the time-varying multiplier. In this case, the processing circuit 21, etc., calculates the final value of each of the time-varying multipliers γm, γa, and γc, which are the judgment parameters, for example, by using the average or median value of the calculated values ​​from the most recent reference count Nref diagnostic processing.

[0053] In the same manner as in any of the examples described above, once the final values ​​of the time-varying ratios γm, γa, and γc are calculated, the processing circuit 21, etc., uses the calculated time-varying ratios γm, γa, and γc as judgment parameters to perform the processing from S112 onward. In the example processing shown in Figure 5, a reference range is set for each of the time-varying ratios γm, γa, and γc. The reference range for each of the time-varying ratios γm, γa, and γc includes the value when the corresponding resistance value of the resistance component remains unchanged over time, i.e., 1.

[0054] Therefore, the reference range for the time-varying ratio γm includes the value when the film resistance Rm remains unchanged over time. That is, the reference range for the time-varying ratio γm, where the value is between the lower limit γmlow and the upper limit γmup, includes a value of 1. Similarly, the reference range for the time-varying ratio γa includes the value when the anode resistance Ra remains unchanged over time. That is, the reference range for the time-varying ratio γa, where the value is between the lower limit γalow and the upper limit γaup, includes a value of 1. Furthermore, the reference range for the time-varying ratio γc includes the value when the cathode resistance Rc remains unchanged over time. That is, the reference range for the time-varying ratio γc, where the value is between the lower limit γclow and the upper limit γcup, includes a value of 1.

[0055] In one example, the range ±Δγm with a median of 1 becomes the reference range for the time-varying factor γm. Then, the range ±Δγa with a median of 1 becomes the reference range for the time-varying factor γa, and the range ±Δγc with a median of 1 becomes the reference range for the time-varying factor γc. In this case, the values ​​1-Δγm and 1+Δγm become the lower limit γmlow and upper limit γmup of the reference range for the time-varying factor γm, respectively. Then, the values ​​1-Δγa and 1+Δγa become the lower limit γalow and upper limit γaup of the reference range for the time-varying factor γa, respectively, and the values ​​1-Δγc and 1+Δγc become the lower limit γclow and upper limit γcup of the reference range for the time-varying factor γc, respectively.

[0056] In the example processing shown in Figure 5, the final values ​​of the time-varying ratios γm, γa, and γc are calculated as judgment parameters. The processing circuit 21 then compares the calculation results from the S111 process with the reference range set as described above for each of the time-varying ratios γm, γa, and γc. That is, the processing circuit 21 compares the calculation results of the judgment parameters, which are parameters related to time variation, for each of the film resistance Rm, anode resistance Ra, and cathode resistance Rc with the reference range. The processing circuit 21 then determines whether at least one of the time-varying ratios γa and γc is below the reference range (S112). At this time, the processing circuit 21 determines whether the time-varying ratio γa of the anode resistance Ra is smaller than the lower limit γalow of the reference range, and whether the time-varying ratio γc of the cathode resistance Rc is smaller than the lower limit γclow of the reference range.

[0057] If at least one of the time-varying ratios γa and γc is below the reference range (S112-Yes), that is, if at least one of the time-varying ratios γa and γc is smaller than the lower limit of the reference range (γalow; γclow), the processing circuit 21, etc., determines whether the time-varying ratio γm is below the reference range (S113). In this case, the processing circuit 21, etc., determines whether the time-varying ratio γm of the film resistance Rm is smaller than the lower limit of the reference range γmlow.

[0058] If the time-varying ratio γm is below the reference range (S113-Yes), that is, if the time-varying ratio γm is less than the lower limit γmlow of the reference range, the processing circuit 21, etc., determines that overheating is occurring in the electrolytic unit 2 (S114). On the other hand, if the time-varying ratio γm is not below the reference range (S113-No), that is, if the time-varying ratio γm is greater than or equal to the lower limit γmlow of the reference range, the processing circuit 21, etc., determines that overcurrent is occurring in the electrolytic unit 2 (S115).

[0059] In the example shown in Figure 5, by performing the steps in the order of S112, S113, and S114, the processing circuit 21 determines that overheating has occurred in the electrolytic unit 2 based on the fact that the time variation ratio (γa;γc) of at least one of the anode resistance Ra and cathode resistance Rc is below the reference range, and the time variation ratio γm of the film resistance Rm is below the reference range. Then, by performing the steps in the order of S112, S113, and S115, the processing circuit 21 determines that overcurrent has occurred in the electrolytic unit 2 based on the fact that the time variation ratio (γa;γc) of at least one of the anode resistance Ra and cathode resistance Rc is below the reference range, and the time variation ratio γm of the film resistance Rm is not below the reference range. Therefore, the determination in S112 determines whether at least one of overheating and overcurrent has occurred in the electrolytic unit 2. Then, the determination in S113 determines whether overheating or overcurrent has occurred in the electrolytic unit 2.

[0060] In the example processing shown in Figure 5, thresholds γmth, γath, and γcth are set for the time-varying ratios γm, γa, and γc, which are the judgment parameters. For each of the time-varying ratios γm, γa, and γc, the thresholds (γmth; γath; γcth) are set higher than the reference range. Therefore, for the time-varying ratio γm of film resistance Rm, the threshold γmth is set higher than the upper limit of the reference range γmup. Similarly, for the time-varying ratio γa of anode resistance Ra, the threshold γath is set higher than the upper limit of the reference range γaup, and for the time-varying ratio γc of cathode resistance Rc, the threshold γcth is set higher than the upper limit of the reference range γcup.

[0061] In S112, if neither of the time-varying ratios γa nor γc are below the reference range (S112-No), the processing circuit 21, etc., determines whether one or more of the time-varying ratios γm, γa, and γc exceed the threshold (γmth; γath; γcth) (S116). At this time, the processing circuit 21, etc., compares the calculation results from the processing in S111 with the threshold (γmth; γa; γcth) for each of the time-varying ratios (γm; γa; γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc, and determines whether they are greater than the threshold (γmth; γath; γcth). In other words, the processing circuit 21, etc., determines whether the time-varying ratio γm exceeds the threshold γmth, whether the time-varying ratio γa exceeds the threshold γath, and whether the time-varying ratio γc exceeds the threshold γcth.

[0062] If one or more of the time-varying ratios γm, γa, and γc exceed the threshold (γmth; γath; γcth) (S116-Yes), the processing circuit 21, etc., determines that there is a shortage of water supply in the electrolytic unit 2 (S117). In the example in Figure 5, by performing the processing in the order of S112, S116, and S117, the processing circuit 21, etc., determines that there is a shortage of water (supply) in the electrolytic unit 2, at least based on the fact that one or more of the time-varying ratios (γm; γa; γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed the threshold. Therefore, if neither the time-varying ratios γa and γc are below the reference range in S112 (S112-No), that is, if neither overheating nor overcurrent occurs in the electrolytic unit 2, the determination in S116 determines whether there is a shortage of water supply in the electrolytic unit 2.

[0063] If any of the time-varying ratios γm, γa, and γc are below the threshold (γmth; γath; γcth) (S116-No), the processing circuit 21, etc., determines whether one or more of the time-varying ratios γm, γa, and γc exceed the reference range (S118). In this case, the processing circuit 21, etc., determines whether the time-varying ratios (γm; γa; γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc are greater than the upper limit of the reference range (γmup; γaup; γcup). That is, the processing circuit 21, etc., determines whether the time-varying ratio γm exceeds the upper limit of the reference range γmup, whether the time-varying ratio γa exceeds the upper limit of the reference range γaup, and whether the time-varying ratio γc exceeds the upper limit of the reference range γcup.

[0064] If one or more of the time-varying ratios γm, γa, and γc exceed the reference range (S118-Yes), that is, if one or more of the time-varying ratios γm, γa, and γc are greater than the upper limit of the reference range (γmup; γaup; γcup), the processing circuit 21, etc., determines that material degradation has occurred in the electrolytic unit 2 (S119). On the other hand, if none of the time-varying ratios γm, γa, and γc exceed the reference range (S118-No), that is, if none of the time-varying ratios γm, γa, and γc are greater than or equal to the upper limit of the reference range (γmup; γaup; γcup), the processing circuit 21, etc., determines that neither operational abnormalities nor material degradation have occurred in the electrolytic unit 2 (S120).

[0065] In the example shown in Figure 5, by performing the processes in the order of S112, S116, S118, and S119, the processing circuit 21, etc., determines that material degradation has occurred in the electrolytic unit 2, at least based on the fact that one or more time-varying ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed the reference range, and that all of the time-varying ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc are below the threshold. Therefore, if neither the time-varying ratios γa and γc are below the reference range in S112, that is, if neither overheating nor overcurrent occurs in the electrolytic unit 2, then the determination in S116 and S118 determines whether material degradation has occurred in the electrolytic unit 2.

[0066] By performing the processing shown in the example in Figure 5, the processing circuit 21, etc., compares the calculation results from the real-time diagnostic process with a reference range that includes the value when the resistance value remains unchanged over time, for the time change ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2, thereby determining the operating status and deterioration state of the electrolytic unit 2. Therefore, by performing the processing shown in the example in Figure 5, the processing circuit 21, etc., determines the operating status and deterioration state of the electrolytic unit 2 based on the time changes of the film resistance Rm, anode resistance Ra, and cathode resistance Rc.

[0067] In electrolytic unit 2, as the temperature rises, the resistive components, including the film resistance Rm, anode resistance Ra, and cathode resistance Rc, decrease according to Arrhenius's law. Therefore, when overheating occurs in electrolytic unit 2, the time-dependent ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc, respectively, tend to fall below the reference range compared to the state where overheating does not occur.

[0068] As the current increases, the catalytic activity of the anode and cathode catalysts in each of the electrolytic cells 3 increases according to the Butler-Volmer equation, causing the anode resistance Ra and cathode resistance Rc to decrease. On the other hand, the film resistance Rm is a resistive component that does not follow the Butler-Volmer equation, so even if the current increases, the film resistance Rm does not change or hardly changes. Therefore, when an overcurrent occurs in the electrolytic unit 2, the time-dependent ratios (γa;γc) of the anode resistance Ra and cathode resistance Rc, respectively, tend to fall below the reference range compared to the state without an overcurrent. Furthermore, even when an overcurrent occurs in the electrolytic unit 2, the time-dependent ratio γm of the film resistance Rm compared to the state without an overcurrent tends to be 1 or approximately 1, remaining within the reference range.

[0069] In this embodiment, it is determined whether the time variation ratios (γa;γc) of the anode resistance Ra and cathode resistance Rc are below a reference range. If the time variation ratio (γa;γc) of at least one of the anode resistance Ra and cathode resistance Rc is below the reference range, it is determined whether the time variation ratio γm of the film resistance Rm is below a reference range. If the time variation ratio γm of the film resistance Rm is below a reference range, it is determined that overheating has occurred in the electrolytic unit 2. If the time variation ratio γm of the film resistance Rm is not below a reference range, it is determined that overcurrent has occurred in the electrolytic unit 2. Because such determinations are made, the occurrence of overheating and overcurrent in the electrolytic unit 2 is appropriately determined and understood.

[0070] Furthermore, in electrolysis unit 2, when the supply amount of water decreases, the reaction rate of water electrolysis decreases, causing the resistive components, including the membrane resistance Rm, anode resistance Ra, and cathode resistance Rc, to increase rapidly in a short period of time. Therefore, when a water shortage occurs in electrolysis unit 2, the time-dependent ratios (γm;γa;γc) of the membrane resistance Rm, anode resistance Ra, and cathode resistance Rc, respectively, tend to exceed the threshold (γmth;γath;γcth) compared to a state where there is no water shortage.

[0071] Furthermore, in electrolytic unit 2, even if material degradation occurs, one or more of the resistive components, including film resistance Rm, anode resistance Ra, and cathode resistance Rc, tend to increase. However, when material degradation occurs, the resistive components tend to increase more slowly over time compared to when water supply is insufficient. In other words, when material degradation occurs, the rate of increase of resistive components over time tends to be lower compared to when water supply is insufficient. Therefore, even if material degradation occurs in electrolytic unit 2 and one or more of the film resistance Rm, anode resistance Ra, and cathode resistance Rc increase over time, the time-dependent change ratio of the increased resistive components (one or more corresponding γm, γa, γc) tends to exceed the standard range but remain below the threshold.

[0072] In this embodiment, if the time variation ratios (γa;γc) of either the anode resistance Ra or the cathode resistance Rc are not below the reference range, it is determined whether the time variation ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed a threshold (γmth;γath;γcth) set higher than the reference range. If one or more time variation ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed the threshold (γmth;γath;γcth), it is determined that a water (supply) shortage has occurred in the electrolysis unit 2. Because such a determination is made, the occurrence of a water supply shortage in the electrolysis unit 2 is appropriately determined and understood.

[0073] Furthermore, in this embodiment, if the time variation ratios (γa;γc) of both the anode resistance Ra and the cathode resistance Rc are not below the reference range, it is determined whether the time variation ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed the threshold (γmth;γath;γcth) and whether they exceed the reference range. If one or more time variation ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed the reference range, and all of the time variation ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc are below the threshold (γmth;γath;γcth), it is determined that material degradation has occurred in the electrolytic unit 2. Because such determination is made, the occurrence of material degradation in the electrolytic unit 2 is appropriately determined and understood.

[0074] As described above, in this embodiment, by performing the determination process shown in the example in Figure 5, the operating status and deterioration state of the electrolytic unit 2 are determined based on the time changes of the film resistance Rm, anode resistance Ra, and cathode resistance Rc. Then, the determination process based on the time changes of the resistance components makes it possible to appropriately grasp the occurrence of operational abnormalities in the electrolytic unit 2, such as overheating, overcurrent, and insufficient supply of materials. Furthermore, the determination process based on the time changes of the resistance components makes it possible to appropriately grasp the occurrence of material deterioration in the electrolytic unit 2. Therefore, in this embodiment, the deterioration state and operating status of the electrolytic unit 2 can be appropriately grasped by the determination process based on the time changes of the resistance components.

[0075] Furthermore, by detecting operational abnormalities in the electrolysis unit 2, users of the operating system 1 can identify, for example, components in the operating system 1 that may be malfunctioning. For instance, if it is determined that overheating is occurring in the electrolysis unit 2, it becomes possible to determine that the temperature sensor 17 may be malfunctioning. Similarly, if it is determined that overcurrent is occurring in the electrolysis unit 2, it becomes possible to determine that the current measurement circuit 7 (current sensor) may be malfunctioning. And if it is determined that there is a shortage of supplied material in the electrolysis unit 2, it becomes possible to determine that the supply pump 12 may be malfunctioning.

[0076] (Verification related to the first embodiment) Here, as a verification related to the first embodiment, the following verification was performed. In the verification, six electrolytic units β1 to β6, which are water electrolysis units, were evaluated. As electrolytic units β1 to β6, water electrolysis units were used in which at least one of the operating conditions and degradation conditions differed from each other.

[0077] In the verification, the film resistance Rm, anode resistance Ra, and cathode resistance Rc were estimated for each of the electrolytic units β1 to β6 at multiple time points. Then, for each of the electrolytic units β1 to β6, the time change ratios γm, γa, and γc were calculated as parameters related to the time change of film resistance Rm, anode resistance Ra, and cathode resistance Rc, respectively. The estimation of film resistance Rm, anode resistance Ra, and cathode resistance Rc, and the calculation of the time change ratios γm, γa, and γc were performed as described above in the first embodiment. Then, for each of the electrolytic units β1 to β6, the operating status and degradation state were determined using the calculated time change ratios γm, γa, and γc, in the same manner as the determination process in the example in Figure 5.

[0078] Figure 6 is a schematic diagram showing the verification results in the verification related to the first embodiment, etc. In Figure 6, the calculation results of the time change ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc, respectively, and the judgment results regarding the operating status and degradation state are shown in a table for each of the six electrolytic units β1 to β6. As shown in Figure 5, the time change ratio γm of the film resistance Rm was 1.001, 0.940, 0.992, 9.7, 2.01, and 1.87 for electrolytic units β1 to β6, respectively. The time evolution ratios γa for the anode resistance Ra were 1.002, 0.890, 0.780, 8.7, 1.007, and 1.81 for electrolytic units β1 to β6, respectively, while the time evolution ratios γc for the cathode resistance Rc were 0.999, 0.910, 0.810, 8.8, and 1.0041.003 for electrolytic units β1 to β6, respectively.

[0079] Furthermore, in determining the operational status and degradation state of each electrolytic unit β1 to β6, a reference range of 0.99 or more and 1.11 or less was set for each of the time change ratios γm, γa, and γc, and 3.0 was set as the threshold (γmth; γath; γcth). The same determination process as in the example in Figure 5 was performed for each of the electrolytic units β1 to β6. For electrolytic unit β1, the determinations were made in the order of S112-No, S116-No, and S118-No, and in S120, it was determined that neither operational abnormalities nor material degradation had occurred in electrolytic unit β1. For electrolytic unit β2, the determinations were made in the order of S112-Yes and S113-Yes, and in S114, it was determined that overheating had occurred in electrolytic unit β2. In electrolytic unit β2, in response to the occurrence of overheating, the time change ratios γm, γa, and γc, which are parameters related to the time change of the resistance component, showed the trend described above in the first embodiment.

[0080] For electrolytic unit β3, the determinations were made in the order of S112-Yes and S113-No, and in S115, it was determined that an overcurrent was occurring in electrolytic unit β3. In electrolytic unit β3, in response to the occurrence of the overcurrent, the time change ratios γm, γa, and γc, which are parameters related to the time change of the resistance component, showed the trend described above in the first embodiment. For electrolytic unit β4, the determinations were made in the order of S112-No and S116-Yes, and in S117, it was determined that a water supply shortage was occurring in electrolytic unit β4. In electrolytic unit β4, in response to the occurrence of a water supply shortage, the time change ratios γm, γa, and γc, which are parameters related to the time change of the resistance component, showed the trend described above in the first embodiment.

[0081] For electrolytic units β5 and β6, the following determinations were made in the order of S112-No, S116-Nos, and S118-Yes, and in S119, it was determined that material degradation had occurred in both electrolytic units β5 and β6. In both electrolytic units β5 and β6, the time-varying ratios γm, γa, and γc, which are parameters related to the time change of the resistance component, showed the trend described above in the first embodiment, corresponding to the material degradation. In electrolytic unit β5, only the time-varying ratio γm of the film resistance Rm exceeded the reference range and was below the threshold γmth, so it was determined that material degradation had occurred in the film of electrolytic unit β5. In electrolytic unit β6, both the time-varying ratio γm of the film resistance Rm and the time-varying ratio γa of the anode resistance Ra exceeded the reference range and were below the threshold (γmth; γath), so it was determined that material degradation had occurred in both the film and the anode of electrolytic unit β6.

[0082] (modified version) The following describes modifications of the embodiments described above. Figure 7 is a flowchart schematically showing an example of the determination process regarding the operating status and deterioration state of the electrolytic unit 2 performed by the processing circuit 21 etc. in the first modification. In the determination process of the example in Figure 7, the processes S111 to S115 are performed in the same manner as the determination process of the example in Figure 5 of the embodiments described above. However, in this modification, if in S112 neither the time change magnification γa nor γc is below the reference range (S112-No), the processing circuit 21 etc. determines whether one or more of the time change magnifications γm, γa, and γc are above the reference range (S121). If none of the time change magnifications γm, γa, and γc are above the reference range, that is, if none of the time change magnifications γm, γa, and γc are below the upper limit of the reference range (γmup; γaup; γcup) (S121-No), the processing circuit 21 etc. determines that neither an operating abnormality nor material deterioration has occurred in the electrolytic unit 2 (S120).

[0083] In the example processing shown in Figure 7, if one or more of the time-varying ratios γm, γa, and γc exceed the reference range (S121-Yes), the processing circuit 21, etc., determines whether the time-varying ratios (one or more of γm, γa, and γc) that exceed the reference range have exceeded the threshold (γmth; γath; γcth). Then, the processing circuit 21, etc., determines whether one or more of the time-varying ratios (one or more of γm, γa, and γc) that exceed the reference range have exceeded the threshold (γmth; γath; γcth) (S122). If one or more of the time-varying ratios (one or more of γm, γa, and γc) that exceed the reference range also have exceeded the threshold (γmth; γath; γcth) (S122-Yes), the processing circuit 21, etc., determines that there is a water supply shortage in the electrolysis unit 2 (S117). Furthermore, if any of the time-varying ratios (one or more of γm, γa, γc) that exceed the reference range are below the threshold (γmth; γath; γcth) (S122-No), the processing circuit 21, etc., determines that material degradation is occurring in the electrolytic unit 2 (S118).

[0084] In this modified example, as in the previously described embodiments including the example processing in Figure 5, if the time change ratios (γa;γc) of both the anode resistance Ra and the cathode resistance Rc are not below the reference range, it is determined whether the time change ratios (γm;γa;γc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed the threshold (γmth;γath;γcth) and the reference range. In this modified example, the operating status and deterioration state of the electrolytic unit 2 are determined based on the time changes of the film resistance Rm, anode resistance Ra, and cathode resistance Rc. Therefore, this modified example also produces the same functions and effects as the previously described embodiments. In other words, in this modified example, the determination process based on the time changes of the resistance components makes it possible to appropriately grasp the occurrence of operational abnormalities in the electrolytic unit 2, such as overheating, overcurrent, and insufficient supply of materials.

[0085] For each of the electrolytic units β1 to β6 shown in Figure 6, the same determination process as in the example in Figure 7 was performed. For electrolytic unit β1, the determinations were made in the order of S112-No and S121-No, and in S120, it was determined that neither operational abnormalities nor material degradation had occurred in electrolytic unit β1. For electrolytic units β2 and β3, the determinations were made in the same way as when the determination process in the example in Figure 5 was performed. For electrolytic unit β4, the determinations were made in the order of S112-No, S121-Yes and S122-Yes, and in S117, it was determined that there was a water supply shortage in electrolytic unit β4. For electrolytic units β5 and β6, the determinations were made in the order of S112-No, S121-Yes and S122-No, and it was determined that material degradation had occurred in electrolytic units β5 and β6.

[0086] In the second modification, the time-varying parameters εm, εa, and εc for the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2 are calculated as time-varying parameters, instead of the time-varying multipliers γm, γa, and γc, respectively. In this modification, each of the time-varying parameters εm, εa, and εc is calculated as a determination parameter in the determination process.

[0087] Here, the time change εm of the film resistance Rm is calculated as, for example, the increase or decrease in the film resistance Rm from the previous diagnostic process to the current real-time diagnostic process. In this case, for example, in the k-th diagnostic process, a subtraction value is calculated by subtracting the estimated film resistance Rm result from the estimated film resistance Rm result in the k-th diagnostic process. Then, the time change εm is calculated by dividing the calculated subtraction value by the estimated film resistance Rm result in the k-th diagnostic process. If the film resistance Rm remains unchanged from the previous diagnostic process, the time change εm is 0. If the film resistance Rm has increased from the previous diagnostic process, the time change εm will be a positive value (greater than 0), and if the film resistance Rm has decreased from the previous diagnostic process, the time change εm will be a negative value (less than 0).

[0088] The time-varying amount εa is defined in the same way as the time-varying amount εm, for example, by using the anode resistance Ra instead of the film resistance Rm. Similarly, the time-varying amount εc is defined in the same way as the time-varying amount εm, for example, by using the cathode resistance Rc instead of the film resistance Rm. In one example, when calculating the time-varying amounts εm, εa, and εc, the processing circuit 21, etc., uses the calculated values ​​of the time-varying amounts in each of the most recent reference count Nref (Nref is a natural number of 2 or more), including the real-time diagnostic processing, as provisional values ​​to calculate the final values ​​of the time-varying amounts. In this case, the processing circuit 21, etc., calculates the final value of each of the time-varying amounts εm, εa, and εc as, for example, the average or median value of the calculated values ​​in the most recent reference count Nref diagnostic processing.

[0089] In this modified example, a reference range is set for each of the time-varying quantities εm, εa, and εc. Each reference range for time-varying quantities εm, εa, and εc includes the value when the corresponding resistance value of the resistance component remains unchanged over time, i.e., 0. Therefore, the reference range for time-varying quantity εm includes the value when the film resistance Rm remains unchanged over time. That is, the reference range for time-varying quantity εm, which is greater than or equal to the lower limit εmlow and less than or equal to the upper limit εmup, includes the value 0. Similarly, the reference range for time-varying quantity εa, which is greater than or equal to the lower limit εalow and less than or equal to the upper limit εaup, includes the value 0, and the reference range for time-varying quantity εc, which is greater than or equal to the lower limit εclow and less than or equal to the upper limit εcup, includes the value 0. In one example, the range ±Δεm with a median of 0 becomes the reference range for the time change εm, the range ±Δεa with a median of 0 becomes the reference range for the time change εa, and the range ±Δεc with a median of 0 becomes the reference range for the time change εc.

[0090] Furthermore, in this modified example, thresholds εmth, εath, and εcth are set for the time-varying quantities εm, εa, and εc, respectively. For each of the time-varying quantities εm, εa, and εc, the thresholds (εmth; εath; εcth) are set higher than the reference range and greater than the upper limit of the reference range (εmup; εaup; εcup).

[0091] In this modified example, the processing circuit 21, etc., instead of the time-varying ratios γm, γa, and γc, compares the calculation results from the real-time diagnostic process with a reference range that includes the value when the resistance value does not change over time (i.e., 0) for each of the time-varying ratios (εm; εa; εc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc of the electrolytic unit 2, thereby determining the operating status and deterioration state of the electrolytic unit 2. Furthermore, in determining the operating status and deterioration state of the electrolytic unit 2, the processing circuit 21, etc., compares the calculation results from the real-time diagnostic process with thresholds (εmth; εath; εcth) that are set higher than the reference range for each of the time-varying ratios εm, εa, and εc. In determining the operating status and deterioration state of the electrolytic unit 2, the same processing as in any of the above-described examples is performed, for example, the same processing as S111~S120 in the example in Figure 5, or the same processing as S111~S115, S117, S119~S122 in the example in Figure 7.

[0092] As described above, the determination process is performed to determine whether the time variation amounts (εa;εc) of the anode resistance Ra and cathode resistance Rc are below the reference range. If the time variation amount (εa;εc) of at least one of the anode resistance Ra and cathode resistance Rc is below the reference range, it is determined whether the time variation amount εm of the film resistance Rm is below the reference range. If the time variation amount εm of the film resistance Rm is below the reference range, it is determined that overheating has occurred in the electrolytic unit 2. If the time variation amount εm of the film resistance Rm is not below the reference range, it is determined that overcurrent has occurred in the electrolytic unit 2. Therefore, in this modified example, as in the embodiments described above, the occurrence of overheating and overcurrent in the electrolytic unit 2 is appropriately determined and understood.

[0093] Furthermore, in this modified example, if the time variation amounts (εa;εc) of both the anode resistance Ra and the cathode resistance Rc are not below the reference range, it is determined whether the time variation amounts (εm;εa;εc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc, respectively, exceed a threshold (εmth;εath;εcth) set higher than the reference range. If one or more time variation amounts (εm;εa;εc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceed the threshold (εmth;εath;εcth), it is determined that a water (supply) shortage has occurred in the electrolysis unit 2. Therefore, in this modified example as in the embodiments described above, the occurrence of a water supply shortage in the electrolysis unit 2 is appropriately determined and understood.

[0094] Furthermore, in this modified example, if the time variation (εa;εc) of either the anode resistance Ra or the cathode resistance Rc is not below the reference range, it is determined whether the time variation (εm;εa;εc) of each of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceeds the threshold (εmth;εath;εcth) and whether it exceeds the reference range. If one or more time variation (εm;εa;εc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc exceeds the reference range, and all of the time variation (εm;εa;εc) of the film resistance Rm, anode resistance Ra, and cathode resistance Rc are below the threshold (εmth;εath;εcth), it is determined that material degradation has occurred in the electrolytic unit 2. Therefore, in this modified example as in the embodiments described above, the occurrence of material degradation in the electrolytic unit 2 is appropriately determined and understood.

[0095] As described above, in this modified example as well, the processing circuit 21, etc., determines the operating status and deterioration state of the electrolytic unit 2 based on the time changes of the film resistance Rm, anode resistance Ra, and cathode resistance Rc. The determination process based on the time changes of the resistance components makes it possible to appropriately grasp the occurrence of operational abnormalities in the electrolytic unit 2, such as overheating, overcurrent, and insufficient supply of materials. Furthermore, the determination process based on the time changes of the resistance components makes it possible to appropriately grasp the occurrence of material deterioration in the electrolytic unit 2. Therefore, in this modified example as well, the deterioration state and operating status of the electrolytic unit 2 can be appropriately grasped by the determination process based on the time changes of the resistance components.

[0096] Furthermore, the parameters related to the time evolution of the resistance component used as judgment parameters are not limited to the time evolution ratios γm, γa, γc or the time evolution amounts εm, εa, εc. In some modifications, parameters obtained by adding or subtracting a constant from each of the time evolution ratios γm, γa, γc or each of the time evolution amounts εm, εa, εc may be used as judgment parameters, or parameters obtained by multiplying each of the time evolution ratios γm, γa, γc or each of the time evolution amounts εm, εa, εc by a constant may be used. In other modifications, parameters obtained by normalizing each of the time evolution ratios γm, γa, γc or each of the time evolution amounts εm, εa, εc may be used as judgment parameters.

[0097] In one modified example, for the film resistance Rm, anode resistance Ra, and cathode resistance Rc, the sum or product of the time change ratio (γm;γa;γv) and the time change amount (εm;εa;εc) is used as the determination parameter. In another modified example, for the film resistance Rm, λm = γm / (γm + γa + γc) may be used as the determination parameter, for the anode resistance Ra, λa = γa / (γm + γa + γc) may be used as the determination parameter, and for the cathode resistance Rc, ξm = εm / (εm + εa + εc) may be used as the determination parameter, for the film resistance Rm, ξa = εa / (εm + εa + εc) may be used as the determination parameter, and for the anode resistance Ra, ξa = εa / (εm + εa + εγc) may be used as the determination parameter.

[0098] Regardless of which parameter is used as the determination parameter, a parameter related to the time change is calculated as the determination parameter for each of the film resistance Rm, anode resistance Ra, and cathode resistance Rc. In this case, for each of the film resistance Rm, anode resistance Ra, and cathode resistance Rc, one of the following is calculated as the determination parameter: the time change ratio (γm;γa;γc), a parameter corresponding to the time change ratio, the amount of change over time (εm;εa;εc), or a parameter corresponding to the amount of change over time. Then, using the determination parameters, the same determination as in the embodiments described above is performed, for example, the same determination process as in the example in Figure 5, or the same determination process as in the example in Figure 7.

[0099] Furthermore, in the third modification, the timing of inputting the diagnostic current to the electrolytic unit 2 is adjusted as follows when measuring the frequency characteristics of the impedance of the electrolytic unit 2. Figure 8 is a flowchart schematically showing an example of the processing related to inputting the diagnostic current to the electrolytic unit 2, which is performed by the processing circuit 21, etc., in the third modification. The processing in the example in Figure 8 is repeatedly performed over time when inputting the diagnostic current to the electrolytic unit 2 during the estimation process of the resistance component of the electrolytic unit 2. In addition, the processing in the example in Figure 8 is performed when the operating current is input to the electrolytic unit 2. For this reason, the processing in the example in Figure 8 is performed when the operating current input to the electrolytic unit 2 and the voltage applied to the electrolytic unit 2 are adjusted.

[0100] When the processing of the example shown in Figure 8 is started, the processing circuit 21, etc., obtains the voltage V of the electrolytic unit 2 in real time as a measurement result from the voltage measurement circuit 8 (S131). Then, the processing circuit 21, etc., determines whether the voltage V of the electrolytic unit 2 is within a specified voltage range (S132). In this modified example, a reference voltage Vref is set for the voltage V of the electrolytic unit 2 when the operating power (operating current) is input, and a specified voltage range including the reference voltage Vref is set. In this case, for example, the range of ±ΔV with the reference voltage Vref as the median value becomes the specified voltage range.

[0101] If the voltage V is within the specified voltage range (S132-Yes), the processing circuit 21, etc., controls the operation of the power supply circuit 28 to input a diagnostic current to the electrolytic unit 2 (S133). As a result, the diagnostic current is superimposed on the operating current input to the electrolytic unit 2. On the other hand, if the voltage V falls outside the specified voltage range (S132-No), the processing circuit 21, etc., controls the operation of the power supply circuit 28 to stop inputting the diagnostic current to the electrolytic unit 2 (S134).

[0102] In this modified example, the processing shown in Figure 8 involves superimposing a diagnostic current onto the operating current input to the electrolytic unit 2 when the voltage V of the electrolytic unit 2 is adjusted to a specified voltage range. Furthermore, in this modified example, the frequency characteristics of the impedance of the electrolytic unit 2 are measured using time-series data showing the time variation (time history) of the current and voltage of the electrolytic unit 2 while the diagnostic current is superimposed on the operating current. Therefore, the frequency characteristics of the impedance of the electrolytic unit 2 are measured while the diagnostic current is superimposed on the operating current.

[0103] Figure 9 is a schematic diagram illustrating an example of the timing for inputting a diagnostic current to the electrolytic unit 2 in the third modification. Figure 9 shows a graph with time on the horizontal axis and the voltage V of the electrolytic unit 2 on the vertical axis, illustrating an example of the time variation of the voltage V of the electrolytic unit 2. In the example in Figure 9, during period Y1, the voltage V of the electrolytic unit 2 falls within a specified voltage range, which is greater than or equal to the lower limit Vref-ΔV and less than or equal to the upper limit Vref+ΔV. Therefore, during period Y1, a diagnostic current is input to the electrolytic unit 2, and the diagnostic current is superimposed on the operating current input to the electrolytic unit 2.

[0104] Furthermore, in period Y2, which follows period Y1, the voltage V of the electrolytic unit 2 falls outside the specified voltage range. Therefore, in period Y2, the input of diagnostic current to the electrolytic unit 2 is stopped, and the diagnostic current is not superimposed on the operating current input to the electrolytic unit 2. Then, in period Y3, which follows period Y2, the voltage V of the electrolytic unit 2 returns to the specified voltage range. Therefore, in period Y3, the diagnostic current is input to the electrolytic unit 2, and the diagnostic current is superimposed on the operating current input to the electrolytic unit 2.

[0105] This modified version also produces the same functions and effects as the embodiments described above. Furthermore, in this modified version, since the diagnostic current is input as described above, even when the magnitude of the operating power fluctuates over time, the diagnostic current is appropriately input to the electrolytic unit 2 at the timing when the voltage V falls within the specified voltage range. Therefore, the frequency characteristics of the impedance of the electrolytic unit 2 can be appropriately measured in parallel with the operation of the electrolytic unit 2.

[0106] In the fourth modification, the electrolytic device 10 is equipped with a plurality of electrolytic units 2_1 to 2_M, and the operating status and deterioration state of each of the plurality of electrolytic units 2_1 to 2_M are determined in the same manner as in any of the embodiments described above. Figure 10 is a schematic diagram showing the configuration of the electrolytic device 10 according to the fourth modification. As shown in Figure 10, in this modification, M electrolytic units 2_1 to 2_M are provided in the electrolytic device 10, and each of the electrolytic units 2_1 to 2_M consists of an electrolytic block or electrolytic module to which a plurality of electrolytic cells 3 are electrically connected.

[0107] In this modified example, the processing circuit 21 estimates the film resistance Rm, anode resistance Ra, and cathode resistance Rc for each of the multiple electrolytic units 2_1 to 2_M of the electrolytic device 10 based on the measurement results of the impedance frequency characteristics. At this time, the processing circuit 21 estimates the resistance component for each of the multiple electrolytic units 2_1 to 2_M by performing a process similar to that in the example in Figure 2. Furthermore, in this modified example, the processing circuit 21 determines the operating status and degradation state for each of the multiple electrolytic units 2_1 to 2_M based on the time changes of the film resistance Rm, anode resistance Ra, and cathode resistance Rc. At this time, the determination is made in the same manner as in any of the embodiments described above, for example, by performing a process similar to that in the example in Figure 5, or a process similar to that in the example in Figure 7.

[0108] This modified version also produces the same functions and effects as the embodiments described above. Furthermore, in this modified version, the deterioration state and operating status of each of the multiple electrolytic units 2_1 to 2_M provided in the electrolytic device 10 can be appropriately grasped by a determination process based on the time change of the resistance component.

[0109] In the embodiments described above, a case in which a water electrolysis unit is used as the electrolysis unit 2 was explained, but the electrolysis unit 2 to be diagnosed is not limited to a water electrolysis unit. In one example, a carbon dioxide electrolysis unit is used as the electrolysis unit 2 to be diagnosed. In this case, the carbon dioxide electrolysis unit to be diagnosed is provided with one or more carbon dioxide electrolysis cells as one or more electrolysis cells 3.

[0110] In the carbon dioxide electrolytic cell that makes up the carbon dioxide electrolysis unit, water is supplied to the anode and carbon dioxide to the cathode as the feed material. When operating power is input to the carbon dioxide electrolysis unit, oxygen is produced from water at the anode and carbon monoxide is produced from carbon dioxide at the cathode. In this example, the electrolysis of water and carbon dioxide occurs as an electrochemical reaction in the operating electrolysis unit 2, which is the carbon dioxide electrolysis unit. The oxygen produced by the electrolysis of water and the carbon monoxide produced by the electrolysis of carbon dioxide are then recovered.

[0111] Even when electrolysis unit 2 is a carbon dioxide electrolysis unit, diagnosis is performed in the same manner as in any of the embodiments described above, and the operating status and deterioration state are determined. Therefore, even when electrolysis unit 2 is a carbon dioxide electrolysis unit, it becomes possible to appropriately detect the occurrence of operational abnormalities in electrolysis unit 2, including overheating, overcurrent, and insufficient supply of materials. Furthermore, even when electrolysis unit 2 is a carbon dioxide electrolysis unit, it becomes possible to appropriately detect the occurrence of material deterioration in electrolysis unit 2.

[0112] In at least one of the embodiments described above, the film resistance due to the film, the anode resistance due to the anode, and the cathode resistance due to the cathode are estimated for the electrolytic unit based on the measurement results of the impedance frequency characteristics. Then, the operating status and deterioration state of the electrolytic unit are determined based on the time changes of the film resistance, anode resistance, and cathode resistance. This makes it possible to provide an electrolytic unit diagnostic method, an electrolytic device diagnostic method, an electrolytic unit diagnostic device, an operating system, and an electrolytic unit diagnostic program that enable appropriate understanding of the deterioration state and operating status of the electrolytic unit.

[0113] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0114] 1...Operating system, 2...Electrolytic unit, 3...Electrolytic cell, 6...Power conditioner, 7...Current measurement circuit, 8...Voltage measurement circuit, 10...Electrolytic device, 12...Supply pump, 13...Flow sensor, 15...Temperature control unit, 17...Temperature sensor, 20...Diagnostic device, 21...Processing circuit, 22...Storage medium, 25...Diagnostic program, 28...Power supply circuit, Rm...Film resistance, Ra...Anode resistance, Rc...Cathode resistance, γm, γa, γc...Time change ratio, εm, εa, εc...Time change amount.

Claims

1. A diagnostic method for an electrolytic unit in which an electrochemical reaction occurs using a supply material provided by an electrical input, Regarding the aforementioned electrolytic unit, the film resistance due to the film, the anode resistance due to the anode, and the cathode resistance due to the cathode are estimated based on the measurement results of the impedance frequency characteristics. Based on the time changes of the film resistance, the anode resistance, and the cathode resistance, the operating status and deterioration state of the electrolytic unit are determined. A diagnostic method that includes the following.

2. In determining the operating status and deterioration state of the electrolytic unit, For each of the aforementioned film resistance, anode resistance, and cathode resistance, parameters related to time variation are calculated as determination parameters. For each of the aforementioned film resistance, anode resistance, and cathode resistance, the calculation result of the determination parameter is compared with a reference range that includes the value when the resistance value remains unchanged over time. The diagnostic method according to claim 1.

3. In determining the operating status and deterioration state of the electrolytic unit, Based on the fact that the determination parameter of at least one of the anode resistance and the cathode resistance is below the reference range, and the determination parameter of the film resistance is below the reference range, it is determined that overheating is occurring in the electrolytic unit. Based on the fact that the determination parameter of at least one of the anode resistor and the cathode resistor falls below the reference range, and the determination parameter of the film resistor does not fall below the reference range, it is determined that an overcurrent is occurring in the electrolytic unit. The diagnostic method according to claim 2.

4. In determining the operating status and deterioration state of the electrolytic unit, Determine whether the respective determination parameters of the anode resistor and the cathode resistor are below the reference range. If the determination parameter of at least one of the anode resistance and the cathode resistance is below the reference range, it is determined whether the determination parameter of the film resistance is below the reference range, and it is determined whether overheating or overcurrent is occurring in the electrolytic unit. The diagnostic method according to claim 3.

5. The diagnostic method of claim 2, wherein, in determining the operating status and deterioration state of the electrolytic unit, it is determined that a supply shortage of the supply material has occurred in the electrolytic unit, based at least on the fact that one or more of the determination parameters, the film resistance, the anode resistance, and the cathode resistance, exceed a threshold set higher than the reference range.

6. In determining the operating status and deterioration state of the electrolytic unit, Determine whether the respective determination parameters of the anode resistor and the cathode resistor are below the reference range. If none of the determination parameters for the anode resistance and the cathode resistance fall below the reference range, it is determined whether the determination parameters for the film resistance, the anode resistance, and the cathode resistance exceed the threshold, and it is determined whether a supply shortage of the supply material has occurred in the electrolytic unit. The diagnostic method according to claim 5.

7. The diagnostic method of claim 5, wherein, in determining the operating status and deterioration state of the electrolytic unit, it is determined that material deterioration has occurred in the electrolytic unit, based at least on the fact that one or more of the determination parameters of the film resistance, anode resistance, and cathode resistance exceed the reference range, and that any of the determination parameters of the film resistance, anode resistance, and cathode resistance are below the threshold.

8. In determining the operating status and deterioration state of the electrolytic unit, Determine whether the respective determination parameters of the anode resistor and the cathode resistor are below the reference range. If neither of the determination parameters for the anode resistance and the cathode resistance falls below the reference range, it is determined whether the determination parameters for the film resistance, anode resistance, and cathode resistance exceed the reference range and the threshold, and whether the degradation of the material has occurred in the electrolytic unit. The diagnostic method according to claim 7.

9. The diagnostic method of claim 2, wherein, in determining the operating status and deterioration state of the electrolytic unit, one of the following is calculated as the determination parameter for each of the film resistance, anode resistance, and cathode resistance: a time change ratio, a parameter corresponding to the time change ratio, a time change amount, and a parameter corresponding to the time change amount.

10. While the electrolytic unit is in operation, the voltage of the electrolytic unit is adjusted, In a state where the voltage of the electrolytic unit is adjusted to a specified voltage range, a diagnostic current is superimposed on the operating current input to the electrolytic unit. In a state where the diagnostic current is superimposed on the operating current, the frequency characteristics of the impedance of the electrolytic unit are measured, A diagnostic method according to any one of claims 1 to 9, further comprising the above.

11. A diagnostic method for an electrolytic apparatus comprising multiple electrolytic units, each of which generates an electrochemical reaction using a supply material provided by an electric power input, A diagnostic method comprising performing the diagnostic method according to any one of claims 1 to 9 on each of the plurality of electrolytic units, thereby determining the operating status and the deterioration state for each of the plurality of electrolytic units.

12. A diagnostic device for an electrolytic unit in which an electrochemical reaction occurs using a supply material provided by an electrical input, Based on the measurement results of the impedance frequency characteristics of the electrolytic unit, the film resistance due to the film, the anode resistance due to the anode, and the cathode resistance due to the cathode are estimated. Based on the time changes of the film resistance, anode resistance, and cathode resistance, the operating status and deterioration state of the electrolytic unit are determined. A diagnostic device equipped with a processor.

13. A diagnostic device according to claim 12, The electrolytic unit, in which the processor of the diagnostic device makes determinations regarding the operating status and the deterioration state, An operating system equipped with the following features.

14. The electrolytic unit comprises a plurality of electrolytic units, each of which generates an electrochemical reaction using a supply material provided by the input of power. The processor of the diagnostic device estimates the film resistance, anode resistance, and cathode resistance for each of the plurality of electrolytic units based on the measurement results of the frequency characteristics of the impedance, and determines the operating status and the degradation state for each of the plurality of electrolytic units based on the time changes of the film resistance, anode resistance, and cathode resistance. The operating system according to claim 13.

15. A diagnostic program for an electrolytic unit in which an electrochemical reaction occurs using a supply material provided by power input, and which is a computer Based on the measurement results of the impedance frequency characteristics of the electrolytic unit, the film resistance due to the film, the anode resistance due to the anode, and the cathode resistance due to the cathode are estimated. Based on the time changes of the film resistance, anode resistance, and cathode resistance, the operating status and deterioration state of the electrolytic unit are determined. Diagnostic program.

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