Water electrolysis system, method for controlling a water electrolysis system, and computer program

Abstract

To provide a technique capable of suppressing degradation in reaction efficiency of a water electrolysis tank even when the water electrolysis tank is deteriorated, in a water electrolysis system.SOLUTION: A water electrolysis system comprises: a current acquisition unit for acquiring a current value of current flowing in a water electrolysis tank; a voltage acquisition unit for acquiring a voltage value of the water electrolysis tank in synchronization with the current acquisition unit; a temperature acquisition unit for acquiring a temperature value of the water electrolysis tank in synchronization with the current acquisition unit; a performance map that is any of a voltage map with respect to the current and temperature, and a current map with respect to voltage and the temperature; and a performance map update unit for updating the performance map, based on the current value acquired by the current acquisition unit, the voltage value acquired by the voltage acquisition unit, and the temperature value acquired by the temperature acquisition unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a water electrolysis system.

Background Art

[0002] Conventionally, a water electrolysis system having a water electrolysis cell that generates hydrogen and oxygen by electrolyzing water is known. In the electrolysis reaction of water at room temperature, heat is generated during the generation of hydrogen, so the temperature of the water electrolysis cell changes with the electrolysis reaction. Also, the reaction efficiency of water electrolysis is higher as the temperature is higher, but there is a characteristic that if the temperature is too high, the deterioration rate of the water electrolysis cell increases. In order to achieve high efficiency and high durability in water electrolysis, techniques for controlling the temperature of the water electrolysis cell have been proposed (see, for example, Patent Documents 1 to 3).

[0003] Patent Document 1 discloses a technique for suppressing a decrease in reaction efficiency at startup by reducing the current density at startup of a water electrolysis device compared to the rated operation, and when the temperature becomes constant, operating at the current density for rated operation set in advance for each temperature.

[0004] Patent Document 2 discloses a technique for improving the reaction efficiency of a water electrolysis device by monitoring the temperature of the water discharge part of the water electrolysis device, and when the specified temperature is exceeded, monitoring and controlling the supply water temperature while cooling the water supplied to the water electrolysis device.

[0005] Patent Document 3 discloses a technique for constructing a detailed physical model of water electrolysis (described by equations that capture all phenomena based on physical laws), using it to predict the future, and performing optimal control.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0007] [Non-Patent Document 1] Parametric Optimization and Control for a Smart Proton Exchange Membrane Water Electrolysis (PEMWE) System, Journal of Process Control, Vol.91, p. 37-49, 2020. [Overview of the project] [Problems that the invention aims to solve]

[0008] Water electrolytic cells gradually deteriorate with use. As the water electrolytic cell deteriorates, the reaction efficiency changes, and the amount of heat generated during the reaction also changes. However, the technology described in the above-mentioned patent document does not take into account the deterioration of the water electrolytic cell, so there is a risk that the desired reaction efficiency may not be obtained as the water electrolytic cell deteriorates with use.

[0009] Furthermore, the aforementioned non-patent literature attempts to improve operations by using predictive control based on physical models. However, determining the numerous physical parameters within the model requires fundamental experiments. It is not practical to conduct fundamental experiments every time degradation occurs during daily operation.

[0010] This invention was made to solve the above-mentioned problems, and aims to provide a technology that can suppress the decrease in the reaction efficiency of a water electrolysis cell even when the water electrolysis cell deteriorates in a water electrolysis system. [Means for solving the problem]

[0011] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in the following forms.

[0012] (1) According to one embodiment of the present invention, a water electrolysis system is provided. This water electrolysis system comprises a water electrolysis cell that generates hydrogen by electrolyzing water, and includes a current acquisition unit that acquires the current value of the current flowing through the water electrolysis cell, a voltage acquisition unit that acquires the voltage value of the water electrolysis cell in synchronization with the current acquisition unit, a temperature acquisition unit that acquires the temperature value of the water electrolysis cell in synchronization with the current acquisition unit, a performance map which is either a voltage map for current and temperature, or a current map for voltage and temperature, and a performance map update unit that updates the performance map based on the current value acquired by the current acquisition unit, the voltage value acquired by the voltage acquisition unit, and the temperature value acquired by the temperature acquisition unit. The update unit uses the acquired current value, acquired voltage value, and acquired temperature value to determine a reference current value, a reference voltage value, and a reference temperature value, respectively. If the performance map is a voltage map, the update unit stores the reference voltage value in the voltage map, updates the voltage values ​​stored in the first voltage map region where the current is less than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value to a voltage value less than or equal to the reference voltage value, updates the voltage values ​​stored in the second voltage map region where the current is greater than or equal to the reference current value and the temperature is less than or equal to the reference temperature value to a voltage value greater than or equal to the reference voltage value, and if the performance map is a current map, the update unit stores the reference current value in the current map, and updates the reference Voltage Less than or equal to the value Voltage , and the aforementioned reference temperature value below The current value stored in the first current map region for temperature is updated to a current value less than or equal to the reference current value, and the voltage is greater than or equal to the reference voltage value, and the reference temperature value is updated to a current value less than or equal to the reference voltage value. That's all. A performance map update process is performed to update the current value stored in the second current map region for temperature to a current value equal to or greater than the reference current value.

[0013] Water electrolysis exhibits the characteristic that, at the same current, higher temperatures result in higher efficiency (lower voltage), while at the same temperature, lower currents result in higher efficiency. Therefore, this configuration makes it possible to modify the entire map from a single acquired data point without any theoretical inconsistencies. Furthermore, this configuration allows for real-time updating (generation) of the performance map. As a result, predictive control that reflects the current state of the water electrolysis cell and detection of degradation trends become possible. Consequently, even if the water electrolysis cell deteriorates, the decrease in the reaction efficiency of the water electrolysis cell can be suppressed.

[0014] (2) In the water electrolysis system of the above form, the performance map update unit may, in the performance map update process, store in the first voltage map region the smaller of the voltage value before update and the reference voltage value if the performance map is the voltage map, and store in the second voltage map region the larger of the voltage value before update and the reference voltage value if the performance map is the current map, and store in the first current map region the smaller of the current value before update and the reference current value, and store in the second current map region the larger of the current value before update and the reference current value. In this way, the performance map can be updated easily. As a result, the processing time can be shortened.

[0015] (3) A water electrolysis system of the above form, further comprising an acquired value storage map, wherein in the performance map update process, if the performance map is the voltage map, the acquired value storage map is configured to store a predetermined number of voltage values ​​as an array for one set of current value and temperature value combinations, and if the performance map is the current map, one set of voltage values ​​and The performance map update unit is configured to store a predetermined number of current values ​​as an array for each combination of temperature values. If the performance map is a voltage map, the unit stores the acquired voltage values ​​in the acquired value storage map. When the number of stored voltage values ​​reaches a predetermined number, it determines the median of the stored voltage values ​​as the reference voltage value and stores it in the voltage map, after which it empties the array. If the performance map is a current map, the unit stores the acquired current values ​​in the acquired value storage map. When the number of stored current values ​​reaches a predetermined number, it determines the median of the stored current values ​​as the reference current value and stores it in the current map, after which it empties the array. This reduces the influence of noise-like values.

[0016] (4) In the water electrolysis system of the above form, in the acquired value storage map, the third storage map area corresponding to the third performance map area which is used infrequently in the performance map may have a maximum number of stored items in the array that is less than that of the remaining area. In this way, the performance map can be updated with fewer data items in the areas that are used infrequently. As a result, a performance map that more accurately reflects the state of the water electrolysis cell can be generated.

[0017] (5) In the water electrolysis system of the above form, if the performance map update unit stores the reference voltage value or the reference current value in the third performance map region of the performance map during the performance map update process, it is not necessary to change the remaining voltage value or current value. When the map is updated with a small number of data points, noise is more likely to be reflected. With this form, when the reference value (reference current value or reference voltage value) is updated with a small number of data points, the remaining voltage value or current value is not changed, thus reducing the influence of noise.

[0018] (6) The water electrolysis system of the above form, wherein when the performance map updating unit is in the case where the performance map is the voltage map and the absolute value of the current gradient of the acquired current value is greater than a predetermined current threshold value, the performance map updating unit does not use it for the performance map updating process; and when the performance map is the current map and the absolute value of the voltage gradient of the acquired voltage value is greater than a predetermined voltage threshold value, the performance map updating unit may not use it for the performance map updating process. In water electrolysis, when the current is rapidly changed, a capacitor-like movement occurs at the electrode, where electricity is temporarily stored or discharged. This value is a so-called noise that is significantly different from the original steady performance of water electrolysis. In this form, since a limit is provided for the current gradient, noise can be removed, and a performance map that more accurately reflects the state of the water electrolysis cell can be generated.

[0019] (7) The water electrolysis system of the above form, wherein the performance map updating unit may perform spatial averaging processing on the performance map after performing the performance map updating process. By doing so, the discontinuous boundary of the map can be relaxed. As a result, smooth control of the water electrolysis device can be realized.

[0020] Note that the present invention can be realized in various forms. For example, it can be realized in the form of a control method for a water electrolysis system, a computer program for causing a computer to execute the control of the water electrolysis system, a server device for distributing the computer program, a non-temporary storage medium storing the computer program, and the like.

Brief Description of Drawings

[0021] [Figure 1] It is an explanatory diagram showing the schematic configuration of the water electrolysis system of the first embodiment. [Figure 2] It is an explanatory diagram conceptually showing the control of the water electrolysis device. [Figure 3] It is an explanatory diagram of the voltage map. [Figure 4] It is a flowchart showing the control flow of the water electrolysis system. [Figure 5]This is a diagram illustrating the performance map update process. [Figure 6] This is a diagram illustrating the performance map update process. [Figure 7] This is a diagram illustrating the performance map update process. [Figure 8] This is an explanatory diagram conceptually showing the configuration of the control unit of the second embodiment. [Figure 9] This is a flowchart showing the control flow of the water electrolysis system according to the second embodiment. [Figure 10] This is an explanatory diagram showing an example of steps S23 to S24 in the performance map update process. [Figure 11] This is a conceptual diagram illustrating the method for updating the voltage map in the third embodiment. [Figure 12] This is a conceptual diagram illustrating the method for updating the current map in the fourth embodiment. [Modes for carrying out the invention]

[0022] <First Embodiment> Figure 1 is an explanatory diagram showing the schematic configuration of a water electrolysis system 100 according to the first embodiment. The water electrolysis system 100 comprises a water electrolysis device 10, a current acquisition unit 22, a voltage acquisition unit 24, a temperature acquisition unit 26, a control unit 30, a water tank 42, a gas-liquid separator 44, a dewaterer 46, and a hydrogen tank 48.

[0023] In this embodiment of the water electrolysis system 100, hydrogen is produced in the water electrolysis device 10 by electrolyzing water to satisfy the commands from the command unit 70. The command unit 70 issues a command to the control unit 30 to produce, for example, 10 kWh of hydrogen in one hour. The command unit 70 monitors the amount of power generated by the power supply 50 and the power requirements of the power load to determine the commands for the water electrolysis system 100. In this specification, the electrolysis of water is also referred to as "water electrolysis".

[0024] As shown in the figure, the water electrolysis system 100 performs water electrolysis using electricity supplied from a power source 50. The power source 50 is a so-called renewable energy-derived power source (hereinafter also referred to as a "renewable energy source") that supplies electricity generated by solar power generation. In other embodiments, renewable energy sources such as hydropower, wind power, wave power, biomass, and geothermal energy may be used as the power source 50, or grid power may be used. The electricity supplied from the power source 50 is divided into a power load 60 and the water electrolysis device 10.

[0025] The hydrogen produced in the water electrolysis device 10 flows into the gas-liquid separator 44 along with the water that was not electrolyzed. In the gas-liquid separator 44, the water is separated, and the hydrogen is further dewatered in the dewaterer 46 and stored in the hydrogen tank 48. The water separated in the gas-liquid separator 44 is sent to the water tank 42 and supplied back to the water electrolysis device 10 for electrolysis. Meanwhile, the oxygen produced in the water electrolysis device 10 flows into the water tank 42 along with the water that was not electrolyzed. The oxygen is separated in the water tank and discharged to the outside, and the water that was not electrolyzed is supplied back to the water electrolysis device 10. In the water electrolysis system 100 of this embodiment, electrolysis is performed on pure water with a high purity and few impurities in order to efficiently produce hydrogen and oxygen with high purity, but the purity of the water to be electrolyzed is not limited to this.

[0026] The water electrolysis apparatus 10 includes a water electrolysis cell 12, a pump 14 for supplying water from a water tank 42 to the water electrolysis cell 12, a temperature controller 16 for adjusting the temperature of the water supplied to the water electrolysis cell 12, and a DC / DC converter 18 for controlling the current supplied to the water electrolysis cell 12.

[0027] The water electrolytic cell 12 is a PEM (Polymer Electrolyte Membrane) type water electrolytic cell and has a membrane electrode assembly (hereinafter referred to as "MEA"). The MEA has an electrolyte membrane that can pass hydrogen ions and water, and on both sides of the membrane, an oxygen electrode (anode) that generates oxygen from oxygen ions produced by the electrolysis of water and a hydrogen electrode (cathode) that generates hydrogen from hydrogen ions are joined. The oxygen electrode has oxygen electrode side channels formed, such as grooves or pores in a porous material, and the hydrogen electrode has hydrogen electrode side channels formed, such as grooves or pores in a porous material, similar to the oxygen electrode side channels. In this embodiment, power is supplied to the water electrolytic cell 12 via a DC / DC converter 18. In Figure 1, the water electrolytic cell 12 is shown as Although a single water electrolysis cell is shown, a water electrolysis stack consisting of multiple water electrolysis cells stacked in series is preferred. Note that the water electrolysis cell is not limited to a PEM type water electrolysis cell; other types of water electrolysis cells, such as alkaline water electrolysis cells, can also be used.

[0028] In the water electrolytic cell 12, hydrogen (H2) and oxygen (O2) are produced by the following reaction. (Anode) H2O → 2H + +1 / 2O2+2e - (Cathode) 2H + +2e - →H2 In water electrolysis, the efficiency η is expressed by the following equation (1). η = 1.48 × Nc / E … (1) Here, Nc is the number of cells in the water electrolysis cell 12, E is the voltage of the water electrolysis cell 12, and 1.48[V] represents the thermal neutral voltage. The efficiency calculated based on the voltage in equation (1) is equivalent to the ratio of the higher heating value of the generated hydrogen to the input energy. Therefore, the efficiency of water electrolysis can be calculated simply by measuring the voltage.

[0029] Water electrolysis at room temperature generates heat during hydrogen production. Therefore, the temperature of the water electrolytic cell 12 changes depending on the amount of hydrogen produced. The reaction efficiency of the water electrolytic cell 12 depends on the temperature and current (more precisely, the current density [A / cm²] relative to the cell area). 2This varies depending on the conditions. Furthermore, as the water electrolysis cell 12 is operated, deterioration of the water electrolysis cell 12 occurs, such as the dissolution of the electrolyte membrane and metal contamination of the electrodes, and the condition of the electrode surface also changes, so the conditions under which the efficiency is best change. In the water electrolysis system 100 of this embodiment, as will be described later, control is performed to achieve highly efficient operation according to the operation of the water electrolysis cell 12.

[0030] The pump 14 supplies water from the water tank 42 to the water electrolytic cell 12 according to instructions from the control unit 30. The temperature controller 16 adjusts the temperature of the water supplied by the pump 14 according to instructions from the control unit 30.

[0031] The DC / DC converter 18 is connected to the power supply 50 and converts the power supplied from the power supply 50 into a current according to the instructions from the control unit 30 and supplies it to the water electrolytic cell 12.

[0032] The control unit 30 is a computer comprising ROM, RAM, and a CPU. The control unit 30 controls the entire water electrolysis system 100, including the performance map update process described later.

[0033] Figure 2 is a conceptual diagram illustrating the control of the water electrolysis device 10 by the control unit 30. As shown in the figure, the control unit 30 includes a performance map update unit 32 and a simulation model 34. In this embodiment, the control unit 30 commands the water electrolysis device 10 to provide current (hereinafter also referred to as current command), so the simulation model 34 includes a voltage map 36 as a performance map. In the control unit 30, the CPU executes a computer program pre-stored in ROM by loading it into RAM, thereby realizing functions such as the performance map update unit 32.

[0034] The command unit 70 issues a command to the control unit 30, for example, to produce 10 kWh of hydrogen per hour. The control unit 30 uses the simulation model 34 to determine the operating pattern that consumes the least power (is the most efficient) while satisfying the command from the command unit 70, and operates the water electrolyzer 12 using this operating pattern. Specifically, the control unit 30 controls the DC / DC converter 18 to supply the current determined using the simulation, and controls the pump 14 and temperature controller 16 to supply an amount of water suitable for producing hydrogen that satisfies the command from the command unit 70 at the temperature determined using the simulation.

[0035] Figure 3 is an explanatory diagram of the voltage map 36. In this embodiment, the voltage map 36 is a voltage map with respect to current and temperature, with current I on the x-axis and temperature T on the y-axis. As will be described later, in this embodiment, the performance map update unit 32 updates the voltage map 36 according to the state (current, temperature, voltage) of the water electrolytic cell 12 during operation. Figure 3 shows the results of repeated updates. As shown in the figure, in the voltage map 36, low current, high Voltage decreases with increasing temperature. That is, the lower right of the voltage map 36 indicates higher voltage, and the upper left indicates lower voltage. Alternatively, the voltage map 36 may be represented as a map where current is converted to current density and voltage to cell voltage.

[0036] The performance map update unit 32 updates the performance map (voltage map 36) based on the current value acquired by the current acquisition unit 22, the voltage value acquired by the voltage acquisition unit 24, and the temperature value acquired by the temperature acquisition unit 26. The current acquisition unit 22 is a current sensor that measures the current value of the current flowing through the water electrolytic cell 12 and transmits it to the control unit 30. The voltage acquisition unit 24 is a voltage sensor that measures the voltage value of the voltage applied to the water electrolytic cell 12 and transmits it to the control unit 30. The temperature acquisition unit 26 is a temperature sensor that measures the temperature of the water electrolytic cell 12 and transmits it to the control unit 30. In this embodiment, the water temperature at the anode outlet is measured as the temperature of the water electrolytic cell 12. Other methods may be used to measure the temperature of the water electrolytic cell 12, such as measuring the wall temperature of the water electrolytic cell.

[0037] Figure 4 is a flowchart showing the control flow of the water electrolysis system 100. The control of the water electrolysis system 100 includes a performance map update process. As described above, in this embodiment, the control unit 30 commands the water electrolysis device 10 to supply current.

[0038] When the control unit 30 receives a hydrogen generation command from the command unit 70, it uses the simulation model as described above to determine the most efficient operating pattern and sends an output command including the current value and the amount of water supplied to the water electrolysis device 10 (step S12).

[0039] The water electrolysis device 10 operates upon receiving an output command from the control unit 30 (step S14). Specifically, the DC / DC converter 18 converts the current to the current value commanded by the control unit 30 and supplies it to the water electrolysis cell 12, while the pump 14 and temperature controller 16 supply water at the temperature and flow rate commanded by the control unit 30 to the water electrolysis cell 12. While the water electrolysis device 10 is operating, the current acquisition unit 22, voltage acquisition unit 24, and temperature acquisition unit 26 acquire the current value of the current flowing through the water electrolysis cell 12, the voltage value of the voltage applied to the water electrolysis cell 12, and the temperature value of the water electrolysis cell 12, respectively, every second and transmit them to the control unit 30. The current value, voltage value, and temperature value acquired by the current acquisition unit 22, voltage acquisition unit 24, and temperature acquisition unit 26, respectively, are also called "acquired values." The frequency of acquiring the acquired values ​​is not limited to this embodiment and can be arbitrarily set to every 2 seconds, every 5 seconds, every 0.5 seconds, etc.

[0040] The performance map update unit 32 updates the voltage map 36 using the received acquired values ​​(step 16). Step S16 in this embodiment is also called the performance map update process. Once the voltage map 36 is updated, the process returns to step S12, and the control unit 30 uses a simulation model with the updated voltage map 36 to determine the operating pattern and transmits an output command to the water electrolyzer 10.

[0041] In this embodiment, current, voltage, and temperature values ​​are acquired every second, and the voltage map 36 is updated each time, and the operating pattern of the water electrolyzer 10 is re-determined. That is, steps S12 to S16 are repeatedly executed every second.

[0042] Figures 5 to 7 are explanatory diagrams of the performance map update process in this embodiment. As shown in the figures, the voltage map 36 is a map with a current range of 0A to 100A in 1A increments and a temperature range of 25°C to 42°C in 1°C increments. Figure 5(A) is a conceptual diagram of the performance map update process. The performance map update unit 32 uses the current value received from the current acquisition unit 22 as a reference voltage. The voltage value received from the current value and voltage acquisition unit 24 is used as the reference voltage value, and the temperature value received from the temperature acquisition unit 26 is used as the reference temperature value, and the reference voltage value is stored in the voltage map 36. In other words, the performance map update unit 32 uses the acquired current value, acquired voltage value, and acquired temperature value to determine the reference current value, reference voltage value, and reference temperature value, respectively. Then, the performance map update unit 32 updates the voltage values ​​stored in the first voltage map area A1 in the voltage map 36 where the current is less than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value to voltage values ​​less than or equal to the reference voltage value, and updates the voltage values ​​stored in the second voltage map area A2 where the current is greater than or equal to the reference current value and the temperature is less than or equal to the reference temperature value to voltage values ​​greater than or equal to the reference voltage value.

[0043] Figure 5(A) illustrates how the performance map is updated when a measurement value of 40V is obtained at 35°C and 60A. The performance map update unit 32 stores 60A as the reference current value, 35°C as the reference temperature value, and 40V as the reference voltage value in the voltage map 36. In Figure 5(A), the area where the reference voltage value (40V) is stored is enclosed in a thick border. The first voltage map region A1, where the current is less than or equal to the reference current value (60A) and the temperature is greater than or equal to the reference temperature value (35°C), is shown with horizontal hatching. In this example, the performance map update unit 32 updates the voltage value in the first voltage map region A1 to less than or equal to the reference voltage value (40V). On the other hand, the voltage value stored in the second voltage map region A2, where the current is greater than or equal to the reference current value (60A) and the temperature is greater than or equal to the reference temperature value (35°C), is updated to a voltage value greater than or equal to the reference voltage value (40V). In Figure 5(A), the second voltage map region A2 is shown with upward-sloping hatching. Specifically, the performance map update unit 32 stores the smaller of the voltage value before the update and the reference voltage value for the first voltage map region, and stores the larger of the voltage value before the update and the reference voltage value for the second voltage map region. The performance map update unit 32 does not change the voltage values ​​in regions other than the first voltage map region A1 and the second voltage map region A2.

[0044] Figure 5(B) shows the initial values ​​of the voltage map 36. In the example shown in Figure 5(B), the voltage value is set to 30V in all regions of the voltage map 36. Note that in Figure 5(B), only some voltage values ​​are shown for ease of viewing.

[0045] In the following explanation, the acquired current value will also be denoted as In, the acquired temperature value as Tn, and the acquired voltage value as Vn. Here, n is a non-negative integer, with the startup of the water electrolysis device 10 being set to 0 seconds, and representing the elapsed time. In addition, the current value on the horizontal axis of the voltage map 36 will be denoted as I, the temperature value on the vertical axis as T, and the voltage value of the voltage map 36 before the update as Vp.

[0046] Figure 6(A) shows the updated voltage map 36 for n=1. When the performance map update unit 32 receives I1=60, T1=35, and V1=40, it stores 40V as the reference voltage value = V1 in the I=60, T=35 of the voltage map 36. In the first voltage map region A1, the voltage value Vp before the update is 30V and the reference voltage value is 40V, and since the voltage value Vp before the update is smaller, the voltage value in the first voltage map region A1 is not changed.

[0047] On the other hand, in the second voltage map region A2, the voltage value Vp before the update is 30V, and the reference voltage value is 40V. Since the reference voltage value is larger, the voltage value in the second voltage map region A2 is changed to the reference voltage value of 40V. The remaining region is not changed and remains at 30V.

[0048] Figure 6(B) shows the updated voltage map 36 for n=2. When the performance map update unit 32 receives I2=59, T2=34, and V2=50, it stores 50V as the reference voltage value = V2 in I=59 and T=34. The first voltage map region A1 and the second voltage map region A2 for n=2 are different from those for n=1. The first voltage map region A1 for n=2 is the map region for currents of 59A or less and temperatures of 34℃ or higher, and the second voltage map region A2 is the map region for currents of 59A or more and temperatures of 34℃ or lower. In the first voltage map region A1, the voltage value Vp before update is 30V, the reference voltage value is 50V, and the voltage value Vp before update is Since the difference is small, the voltage value in the first voltage map region A1 is not changed.

[0049] On the other hand, in the second voltage map region A2, the voltage values ​​Vp before the update are 30V and 40V, and the reference voltage value is 50V. Since the reference voltage value is larger, the voltage values ​​in the second voltage map region A2 are changed to the reference voltage value of 50V. The remaining region is not changed, so as shown in the figure, 30V and 40V exist.

[0050] Figure 7(A) shows the updated voltage map 36 for n=3. When the performance map update unit 32 receives I3=61, T3=36, and V3=55, it stores 55V in I=61 and T=36, using V3 as the reference voltage value. The first voltage map region A1 and the second voltage map region A2 for n=3 are different from those for n=2. The first voltage map region A1 for n=3 is the map region for currents of 61A or less and temperatures of 36°C or higher, and the second voltage map region A2 is the map region for currents of 51A or more and temperatures of 36°C or lower. In the first voltage map region A1, the voltage value Vp before the update is 30V and the reference voltage value is 55V. Since the voltage value Vp before the update is smaller, the performance map update unit 32 does not change the voltage value in the first voltage map region A1.

[0051] On the other hand, in the second voltage map region A2, the voltage values ​​Vp before the update are 30V, 40V, and 50V, and the reference voltage value is 55V. Since the reference voltage value is larger, the voltage values ​​in the second voltage map region A2 are changed to the reference voltage value of 55V. The remaining region is not changed, so 30V, 40V, and 50V remain.

[0052] Figure 7(B) shows the updated voltage map 36 for n=4. When the performance map update unit 32 receives I4=59, T4=35, and V4=28, it stores 28V in I=59 and T=35, using V4 as the reference voltage value. The first voltage map region A1 and the second voltage map region A2 for n=4 are different from those for n=3. The first voltage map region A1 for n=4 is the map region for currents of 59A or less and temperatures of 35°C or higher, and the second voltage map region A2 is the map region for currents of 59A or more and temperatures of 35°C or lower. In the first voltage map region A1, the voltage value Vp before the update is 30V and the reference voltage value is 28V. Since the reference voltage value is smaller, the voltage value in the first voltage map region A1 is changed to 28V.

[0053] On the other hand, in the second voltage map region A2, the pre-update voltage values ​​Vp are 40V, 50V, and 55V, and the reference voltage value is 28V. Since the pre-update voltage values ​​Vp are larger, the voltage values ​​in the second voltage map region A2 are not changed. The remaining region is not changed, so as shown in the figure, 30V and 55V exist.

[0054] Thus, each time the performance map update unit 32 receives acquired values ​​from the current acquisition unit 22, the voltage acquisition unit 24, and the temperature acquisition unit 26, it updates the voltage map 36. As the updates are repeated, as shown in Figure 3, the voltage becomes higher towards the lower right and lower towards the upper left of the voltage map 36.

[0055] The program that implements the processing described in this embodiment is stored in the control unit 30 via a communication network and a communication interface from the program provider. Alternatively, the program that implements the processing described in the above embodiment may be stored in a commercially available and distributed portable storage medium. In this case, the portable storage medium may be set in an external or built-in reader, and the program may be read and executed by the control unit 30. Various types of storage media can be used as portable storage media, such as CD-ROMs, DVD-ROMs, flexible disks, optical disks, magneto-optical disks, IC cards, and USB memory devices. The program stored in such a storage medium is read by the reader.

[0056] As described above, according to the water electrolysis system 100 of this embodiment, the performance map update unit 32 sequentially updates the voltage map 36 using operational data (current value, temperature value, and voltage value) received from the operating water electrolysis device 10, so that the current status can be reflected in the voltage map 36 in real time from the daily operational data.

[0057] The control unit 30 then uses a simulation model including a voltage map 36 to determine the operating pattern that satisfies the commands from the command unit 70 while minimizing power consumption (maximizing efficiency), and operates the water electrolysis apparatus 10 using this operating pattern. Since the voltage map 36 reflects the current status in real time from daily operation data, the control unit 30 can make highly accurate temperature predictions and operate the water electrolysis apparatus 10 with a highly efficient and durable operating pattern.

[0058] The performance map update unit 32 uses the acquired data from one point (current value, temperature value, and voltage value) to set a first voltage map region A1 with a higher temperature and lower current than the acquisition point, and a second voltage map region A2 with a lower temperature and higher current than the acquisition point. The first voltage map region A1 is corrected to be below the reference voltage, and the second voltage map region A2 is corrected to be above the reference voltage. Water electrolysis has the characteristic that, for the same current, higher temperatures result in higher efficiency (lower voltage), and for the same temperature, lower current results in higher efficiency (lower voltage). Therefore, by performing the performance map update process in this embodiment, it becomes possible to correct the entire voltage map 36 from a single acquired data point without any theoretical inconsistencies.

[0059] As a comparative example of this embodiment, we consider a case where, when updating the performance map from the actual operating results of the water electrolysis device, only one acquired data point is updated. For example, in a situation where the water electrolysis device 10 is deteriorating, if it is frequently operated at high temperature and high current, data from that region will be collected, and a voltage map 36 will be generated that appears to show deterioration only in that region. In that case, since the control unit 30 uses the voltage map 36 to determine the operating pattern, it will operate in a way that avoids using the region that appears to be deteriorating. As a result, the efficiency predicted by the control unit 30 may not be achieved. In contrast, as described above, the performance map update unit 32 of this embodiment can correct the entire voltage map 36 from a single acquired data point without any theoretical inconsistencies, so that the control unit 30 can operate the water electrolysis device 10 with high efficiency.

[0060] Furthermore, the aforementioned non-patent literature describes a detailed physical model (describes all phenomena using equations based on physical laws) for a water electrolysis device, and uses it to predict the future and perform optimal control. The detailed model contains numerous fitting parameters (e.g., electrical resistance of the polymer membrane, anode / cathode reaction rate constants, activation energy, etc.). Since water electrolysis cells gradually deteriorate, it is necessary to identify the precise values ​​of these parameters by conducting basic experiments in order to capture the situation and update the model. However, in practical applications, it is difficult to conduct basic experiments every time deterioration occurs. In contrast, this embodiment quickly constructs a map from measured data, thus ensuring real-time performance and being superior to the technology described in the non-patent literature in terms of computational load.

[0061] <Second Embodiment> Figure 8 is a conceptual diagram illustrating the configuration of the control unit 30A of the second embodiment. Figure 9 is a flowchart showing the control flow of the water electrolysis system of the second embodiment. The control of the water electrolysis system includes a performance map update process. The water electrolysis system of the second embodiment differs from the first embodiment in that the control unit 30A has an acquired value storage map and the performance map update process is different. The same components and steps as in the first embodiment are denoted by the same reference numerals and refer to the preceding description.

[0062] As shown in Figure 8, the control unit 30 A The performance map update unit 32A has an acquired value storage map 38. The acquired value storage map 38 is configured to store a predetermined number of voltage values ​​as an array for a given combination of current and temperature values.

[0063] As shown in Figure 9, the control unit 30A transmits an output command to the water electrolysis device 10, similar to the first embodiment (step S12). The water electrolysis device 10 receives the output command from the control unit 30A and operates, and the current acquisition unit 22, voltage acquisition unit 24, and temperature acquisition unit 26 acquire the current value of the current flowing through the water electrolysis cell 12, the voltage value of the voltage applied to the water electrolysis cell 12, and the temperature value of the water electrolysis cell 12, respectively, every second and transmit them to the control unit 30 (step S14).

[0064] The performance map update unit 32A discards the acquired current value (step S26) and returns to step S12 if the absolute value of the current gradient of the acquired current value is greater than a predetermined current threshold ki (NO in step S21). In other words, the performance map update unit 32A does not use the acquired current value in the performance map update process, and therefore the performance map is not updated. Here, the current gradient is the amount of change from the current value at the previous acquisition time, and the absolute value of the current gradient is shown as |dI / ds| in Figure 9. The predetermined current threshold ki can be set arbitrarily. For example, the current threshold ki may be set to 5% of the rated current per second. If the rated current is 100A, the current threshold ki = 5A / s.

[0065] The performance map update unit 32A checks if the absolute value of the current gradient of the acquired current value is less than or equal to a predetermined current threshold ki (in step S21) YES ), obtained Voltage The value is stored in the corresponding array (also called array A) of the acquired value storage map 38 (step S22).

[0066] Array A Voltage If the number of values ​​to be stored is less than the maximum number of values ​​to be stored (NO in step S23), return to step S12. Voltage When the number of stored values ​​reaches the maximum number of stored values ​​(YES in step S23), the performance map update unit 32A determines the median value of the multiple voltage values ​​stored in array A as the reference voltage value, stores it in the voltage map 36, and then clears array A (step S24).

[0067] The performance map update unit 32A updates the voltage map 36 using the stored reference voltage values ​​(step 16). Subsequently, the performance map update unit 32A performs spatial averaging on the entire updated voltage map 36 (step S25). For spatial averaging, known methods can be used, for example, by adopting the average value of a 3x3 grid as the value of the central grid. It may be an average of 9 cells (3x3) or an average of 25 cells (5x5). Map boundaries (for example, a map area with a temperature of 25°C, an area with a current of 0A, etc.) may use the values ​​without processing, or they may use the values ​​of nearby points after spatial processing.

[0068] Then, returning to step S12, the control unit 30A uses a simulation model with a spatially averaged voltage map 36 to determine the operating pattern and transmits an output command to the water electrolyzer 10.

[0069] Figure 10 is an explanatory diagram showing an example of steps S23 to S24 in the performance map update process. In Figure 10, an example of an acquired value storage map is shown, corresponding to the current and temperature usage range, with 1A and 1℃ intervals forming one section in the range of 0A-100A and 25℃-42℃. In the example shown in Figure 10, the acquired value storage map 38 is configured to store up to 7 voltage values ​​for each section. Here, the array 39 of the section with a current of 61A and a temperature of 35℃ is shown as array A. When the acquired current value is 59.5A to 60.5A and the acquired temperature value is 34.5℃ to 35.5℃, the acquired voltage values ​​are stored in the array 39 of the section with a current of 61A and a temperature of 35℃. When 7 voltage values ​​are stored in array 39, the performance map update unit 32A calculates the median value En= 40V is determined as the reference voltage value and stored in the voltage map 36 shown on the right side of Figure 10. Then, the performance map update unit 32A updates the voltage map 36 using the stored reference value and then applies spatial averaging to the entire voltage map 36.

[0070] In this embodiment, current, voltage, and temperature values ​​are acquired every second, but the voltage map is updated when the maximum number of voltage values ​​are stored in any array of the acquired value storage map 38.

[0071] As explained above, in the water electrolysis system 100 of this embodiment, data where the current gradient exceeds a certain level is removed. In water electrolysis, if the current is changed rapidly, a capacitor-like movement occurs at the electrodes, where energy is temporarily stored and discharged. This value differs significantly from the steady-state performance of water electrolysis and is what is known as noise. In this embodiment, by setting a limit on the current gradient, noise can be removed and a voltage map 36 that more accurately reflects the state of the water electrolysis cell 12 can be generated.

[0072] In this embodiment, the performance map update unit 32A stores the acquired data in the acquired value storage map 38. When the maximum number of voltage values ​​are stored in an array of arbitrary sections, the median value of the voltage values ​​stored in the array is passed to the corresponding section of the voltage map 36. This reduces the influence of noisy values. This process makes it possible to generate a voltage map 36 that more accurately reflects the state of the water electrolytic cell 12. In addition, in this embodiment, the update frequency of the voltage map 36 can be reduced, thereby suppressing the processing load on the computer.

[0073] Furthermore, in this embodiment, the performance map update unit 32A performs spatial (regional) averaging on the entire updated voltage map 36, which can mitigate discontinuous boundaries in the map. As a result, smooth control of the water electrolysis device 10 can be achieved.

[0074] <Third Embodiment> Figure 11 is a conceptual diagram illustrating the method for updating the voltage map in the third embodiment. In the acquired value storage map 38A of the third embodiment, the third storage map area A13, which corresponds to the third performance map area A3 in the voltage map 36 (which is a performance map) and has a low operating frequency, has fewer stored values ​​in array 39A than the remaining areas. In the example shown in Figure 11, in the acquired value storage map 38A, the maximum number of stored values ​​in array 39A of the third storage map area A13 is 3, while the maximum number of stored values ​​in arrays of the other areas is 7.

[0075] In actual operation of the water electrolysis device 10, only a portion of the voltage map 36 may be used, and there may be areas that are used infrequently. In such cases, if a data acquisition storage map with the same maximum number of stored data arrays across the entire map is used, data updates in the infrequently used areas may be slow. For example, as shown in the second embodiment, if the entire map has arrays with a maximum number of stored data of 7, and there are areas that are used infrequently, it may take time to acquire 7 data points, and the state of the water electrolysis cell 12 may have changed (deterioration may have progressed) between the first data point acquired and the seventh data point acquired. Therefore, in this embodiment, areas that are used infrequently are classified in advance as the third storage map area A13, and the maximum number of stored data points in that area is reduced compared to the maximum number of stored data points in other areas (here, set to 7). As a result, the map can be updated with fewer data points in areas that are used infrequently.

[0076] On the other hand, updating the map with a small amount of data means that noise is more easily reflected. If noise is reflected in the map and the performance map update process described in the first embodiment is performed based on that data, the entire voltage map 36 will be affected. It is possible that the system may be affected by noise. Therefore, when a reference voltage value is stored in the third performance map area A3 of the voltage map 36, which corresponds to the third storage map area A13 in the acquired value storage map 38A where the maximum number of stored values ​​has been reduced, the voltage values ​​other than the stored voltage value are not changed. In this way, the effect of noise can be reduced. As for the spatial averaging process (step S25) described in the second embodiment, it may be performed because the impact is small.

[0077] <Fourth Embodiment> Figure 12 is a conceptual diagram illustrating the method for updating the current map in the water electrolysis system 100 of the fourth embodiment. In the water electrolysis system 100 of this embodiment, the control unit controls the water electrolysis device 10 using the voltage value as a command value. Therefore, the control unit has a current map 36A that shows the current in relation to voltage and temperature as a performance map. Components identical to those in the first and second embodiments are denoted by the same reference numerals and refer to the preceding description.

[0078] As in the first and second embodiments, when a current is commanded, the voltage is uniquely determined according to the temperature, etc. On the other hand, as in this embodiment, when a voltage is commanded, the current value is uniquely determined. The current map 36A has voltage E on the x-axis and temperature T on the y-axis. The current map 36A is a map with a voltage range of 36.0V to 50.0V in 0.1V increments and a temperature range of 25℃ to 42℃ in 1℃ increments. For example, if a measurement value of 60A is obtained at a voltage of 40V and a temperature of 35℃, 35℃ is used as the reference temperature value, 40V as the reference voltage value, and 60A as the reference current value, and these are stored in the current map 36A. Reference voltage value below Voltage and reference temperature value The following temperaturesThe current values ​​stored in the first current map region A11 are updated to current values ​​less than or equal to the reference voltage value, and the current values ​​stored in the second current map region A12, where the voltage is greater than or equal to the reference voltage value and the temperature is greater than or equal to the reference temperature value, are updated to current values ​​greater than or equal to the reference current value. In the example shown in Figure 12, the first current map region A11 is set to 60A or less, and the second current map region A12 is set to 60A or more. In Figure 12, the first current map region A11 is shown with horizontal hatching, and the second current map region A12 is shown with upward-sloping hatching.

[0079] As described above, water electrolysis is characterized by higher efficiency (lower voltage) at higher temperatures for the same current, and lower efficiency (lower voltage) at lower temperatures. Therefore, by performing the performance map update process of this embodiment, it is possible to correct the entire current map 36A from a single acquired data point without any theoretical inconsistencies.

[0080] Furthermore, when updating the current map 36A, noise processing may be applied, such as setting limits on the voltage gradient or using a map for storing acquired values, as shown in the second and third embodiments. Applying noise processing can result in a more accurate map. In addition, the current map 36A may be a map in which the current is converted to current density and the voltage to cell voltage.

[0081] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0082] • In the above embodiment, an example was shown in which measuring sensors are used as the current acquisition unit 22, the voltage acquisition unit 24, and the temperature acquisition unit 26, but the system is not limited to this. For example, when a command value is used as the current value or the voltage value, the control unit 30 functions as the current acquisition unit 22 or the voltage acquisition unit 24. However, in reality, the command and the measured value do not always match, so it is preferable to use the measured value.

[0083] In the second embodiment described above, steps S21 and S26 may be omitted. Furthermore, step S25 may also be omitted.

[0084] In the first embodiment described above, step S25 of the second embodiment may be performed after step S16. Alternatively, in the first embodiment described above, step S21 of the second embodiment may be performed before step S16. Doing so can reduce the influence of noise and improve the accuracy of the voltage map.

[0085] The method for updating the performance map is not limited to the above embodiment. For example, when updating the voltage map, a positive gradient coefficient may be applied to the high current and low temperature side (second voltage map region A2) from the data acquisition point (gradually increasing), and a negative gradient coefficient may be applied to the low current and high temperature side (first voltage map region A1) (gradually decreasing voltage). The gradient coefficient can be arbitrarily set to a linear function, quadratic function, cubic function, etc.

[0086] In each of the above embodiments, some of the configurations implemented by hardware may be replaced with software, and conversely, some of the configurations implemented by software may be replaced with hardware. Furthermore, if some or all of the functions of this disclosure are implemented by software, that software (computer program) may be provided in the form of being stored on a computer-readable recording medium. "Computer-readable recording medium" is not limited to portable recording media such as flexible disks and CD-ROMs, but also includes various internal storage devices within a computer such as RAM and ROM, and external storage devices fixed to a computer such as hard disks. In other words, "computer-readable recording medium" has a broad meaning that includes any recording medium on which data packets can be fixed rather than temporary.

[0087] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0088] 10...Water electrolysis device 12...Water electrolyzer 14…Pump 16…Temperature controller 18…DC / DC converter 22…Current acquisition section 24...Voltage acquisition unit 26...Temperature acquisition section 30, 30A... Control Unit 32, 32A... Performance map update section 34…Simulation Model 36…Voltage Map 36A…Current Map 38, 38A... Map for storing acquired values 39, 39A…array 42...Water tank 44…Gas-liquid separator 46...Dehydrator 48…Hydrogen tank 50…Power supply 60…Power load 70…Command department 100...Water electrolysis system A1...First voltage map region A11...First current map region A12...Second current map region A13...Third storage map area A2...Second voltage map region A3...Third performance map area

Claims

1. A water electrolysis system comprising a water electrolysis cell that generates hydrogen by electrolyzing water, A current acquisition unit that acquires the current value of the current flowing through the water electrolysis cell, A voltage acquisition unit that acquires the voltage value of the water electrolytic cell in synchronization with the current acquisition unit, A temperature acquisition unit that acquires the temperature value of the water electrolytic cell in synchronization with the current acquisition unit, A performance map which is either a voltage map against current and temperature, or a current map against voltage and temperature, A performance map update unit updates the performance map based on the current value obtained by the current acquisition unit, the voltage value obtained by the voltage acquisition unit, and the temperature value obtained by the temperature acquisition unit. Equipped with, The performance map update unit, Using the acquired current value, the acquired voltage value, and the acquired temperature value, a reference current value, a reference voltage value, and a reference temperature value are determined, respectively. If the performance map is the voltage map, the reference voltage value is stored in the voltage map, the voltage values ​​stored in the first voltage map region where the current is less than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value are updated to voltage values ​​less than or equal to the reference voltage value, and the voltage values ​​stored in the second voltage map region where the current is greater than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value are updated to voltage values ​​greater than or equal to the reference voltage value. If the performance map is the current map, the performance map update process is performed by storing the reference current value in the current map, updating the current values ​​stored in the first current map region where the voltage is less than or equal to the reference voltage value and the temperature is less than or equal to the reference temperature value to current values ​​less than or equal to the reference current value, and updating the current values ​​stored in the second current map region where the voltage is greater than or equal to the reference voltage value and the temperature is greater than or equal to the reference temperature value to current values ​​greater than or equal to the reference current value. Water electrolysis system.

2. A water electrolysis system according to claim 1, The performance map update unit, In the aforementioned performance map update process, If the performance map is the voltage map, the first voltage map region stores the smaller of the voltage value before the update and the reference voltage value, and the second voltage map region stores the larger of the voltage value before the update and the reference voltage value. If the performance map is the current map, the first current map region stores the smaller of the current value before the update and the reference current value, and the second current map region stores the larger of the current value before the update and the reference current value. Water electrolysis system.

3. A water electrolysis system according to claim 1 or claim 2, Furthermore, it includes a map for storing acquired values, The aforementioned map for storing acquired values ​​is: In the aforementioned performance map update process, If the performance map is the voltage map, it is configured to store a predetermined number of voltage values ​​as an array for each pair of current and temperature values. If the performance map is the current map, it is configured to store a predetermined number of current values ​​as an array for a given combination of voltage and temperature values. The performance map update unit, If the performance map is the voltage map, the acquired voltage values ​​are stored in the acquired value storage map, and when the number of stored voltage values ​​reaches a predetermined number, the median of the multiple stored voltage values ​​is determined as the reference voltage value and stored in the voltage map, and then the array is emptied. If the performance map is the current map, the acquired current values ​​are stored in the acquired value storage map, and when the number of stored current values ​​reaches a predetermined number, the median of the multiple stored current values ​​is determined as the reference current value and stored in the current map, and then the array is emptied. Water electrolysis system.

4. A water electrolysis system according to claim 3, In the aforementioned map for storing acquired values, The third storage map region corresponding to the third performance map region with low operating frequency in the performance map is such that the maximum number of stored items in the array is less than the remaining region. Water electrolysis system.

5. A water electrolysis system according to claim 4, The performance map update unit, In the aforementioned performance map update process, If the reference voltage value or reference current value is stored in the third performance map region of the performance map, the remaining voltage value or current value will not be changed. Water electrolysis system.

6. A water electrolysis system according to any one of claims 1 to 5, The performance map update unit, If the performance map is the voltage map, and the absolute value of the current gradient of the acquired current value is greater than a predetermined current threshold, it will not be used in the performance map update process. If the performance map is the current map, and the absolute value of the voltage gradient of the acquired voltage value is greater than a predetermined voltage threshold, then it is not used in the performance map update process. Water electrolysis system.

7. A water electrolysis system according to any one of claims 1 to 6, The performance map update unit, After performing the performance map update process, spatial averaging is applied to the performance map. Water electrolysis system.

8. A control method for a water electrolysis system equipped with a water electrolysis cell that generates hydrogen by electrolyzing water, The aforementioned water electrolysis system is A current acquisition unit that acquires the current value of the current flowing through the water electrolysis cell, A voltage acquisition unit that acquires the voltage value of the water electrolytic cell in synchronization with the current acquisition unit, A temperature acquisition unit that acquires the temperature value of the water electrolytic cell in synchronization with the current acquisition unit, A performance map which is either a voltage map against current and temperature, or a current map against voltage and temperature, Equipped with, The control method for the water electrolysis system is as follows: Using the acquired current value, the acquired voltage value, and the acquired temperature value, a reference current value, a reference voltage value, and a reference temperature value are determined, respectively. If the performance map is the voltage map, the reference voltage value is stored in the voltage map, the voltage values ​​stored in the first voltage map region where the current is less than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value are updated to voltage values ​​less than or equal to the reference voltage value, and the voltage values ​​stored in the second voltage map region where the current is greater than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value are updated to voltage values ​​greater than or equal to the reference voltage value. If the performance map is the current map, the performance map update process is performed by storing the reference current value in the current map, updating the current values ​​stored in the first current map region where the voltage is less than or equal to the reference voltage value and the temperature is less than or equal to the reference temperature value to current values ​​less than or equal to the reference current value, and updating the current values ​​stored in the second current map region where the voltage is greater than or equal to the reference voltage value and the temperature is greater than or equal to the reference temperature value to current values ​​greater than or equal to the reference current value. A method for controlling a water electrolysis system.

9. A computer program for controlling a water electrolysis system equipped with a water electrolysis cell that generates hydrogen by electrolyzing water, The aforementioned water electrolysis system is A current acquisition unit that acquires the current value of the current flowing through the water electrolysis cell, A voltage acquisition unit that acquires the voltage value of the water electrolytic cell in synchronization with the current acquisition unit, A temperature acquisition unit that acquires the temperature value of the water electrolytic cell in synchronization with the current acquisition unit, A performance map which is either a voltage map against current and temperature, or a current map against voltage and temperature, Equipped with, The control program for the water electrolysis system is: A function to determine a reference current value, a reference voltage value, and a reference temperature value, respectively, using the acquired current value, the acquired voltage value, and the acquired temperature value. If the performance map is the voltage map, the function includes storing the reference voltage value in the voltage map, updating the voltage values ​​stored in the first voltage map region where the current is less than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value to voltage values ​​less than or equal to the reference voltage value, and updating the voltage values ​​stored in the second voltage map region where the current is greater than or equal to the reference current value and the temperature is greater than or equal to the reference temperature value to voltage values ​​greater than or equal to the reference voltage value. If the performance map is the current map, the function includes storing the reference current value in the current map, updating the current values ​​stored in the first current map region where the voltage is less than or equal to the reference voltage value and the temperature is less than or equal to the reference temperature value to current values ​​less than or equal to the reference current value, and updating the current values ​​stored in the second current map region where the voltage is greater than or equal to the reference voltage value and the temperature is greater than or equal to the reference temperature value to current values ​​greater than or equal to the reference current value. A computer program that enables a computer to realize something.

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