Electrolytic apparatus

Abstract

To produce gas efficiently when electrolysis is performed using variable power to produce gas.SOLUTION: An electrolytic apparatus 10 according to the present disclosure comprises a plurality of electrolytic baths 11-1 to 11-n containing a liquid that decomposes and produces a gas when an electric current is supplied, a plurality of rectifiers 12-1 to 12-n installed in each of the plurality of electrolytic baths 11-1 to 11-n and supplying a current to each of the plurality of electrolytic baths 11-1 to 11-n, and a control unit 16 that controls the distribution amount of the current supplied by the plurality of rectifiers 12-1 to 12-n to the plurality of electrolytic baths 11-1 to 11-n. The control unit 16 obtains a power command that directs the power to be supplied to the entire plurality of electrolytic baths 11-1 to 11-n, and controls the amount of current distribution so that the total amount of gas produced by the plurality of electrolytic baths 11-1 to 11-n is maximized based on the power command.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to electrolysis devices. [Background technology]

[0002] Conventionally, electrolysis devices that generate hydrogen and oxygen by electrolyzing water are known. Typically, the electrolysis device includes an electrolytic cell, and water is electrolyzed in the electrolytic cell. In large-scale electrolysis devices, a plurality of electrolytic cells are often operated simultaneously to generate a large amount of hydrogen.

[0003] For example, Patent Document 1 discloses a hydrogen production facility that includes a plurality of cell stacks (electrolyzers) and selects the number of cell stacks to be used so that the voltage and current acting on each cell stack are within a predetermined range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-126792 A Summary of the Invention [Problem to be solved by the invention]

[0005] Electrolyzing water using electricity generated by renewable energies such as solar and wind power can produce hydrogen while reducing carbon dioxide emissions.

[0006] Electricity generated by renewable energy sources fluctuates over time. When using such fluctuating electric power to perform electrolysis to produce gases such as hydrogen, it is desirable to produce the gases efficiently.

[0007] In view of the above circumstances, an object of the present disclosure is to provide an electrolysis device that enables efficient gas generation when gas is generated by electrolysis using variable power. [Means for solving the problem]

[0008] That is, the present invention is as follows. [1] a plurality of electrolytic cells containing a liquid that is decomposed to generate a gas by the application of an electric current; a plurality of rectifiers disposed in the plurality of electrolytic cells, respectively, for supplying current to the plurality of electrolytic cells; a control unit that controls distribution amounts of currents supplied from the plurality of rectifiers to the plurality of electrolytic cells; Equipped with The control unit is obtaining a power command indicative of power to be supplied to the plurality of electrolytic cells as a whole; an electrolysis device that controls the current distribution amount based on the power command so that the sum of the amounts of gas generated by the plurality of electrolytic cells is maximized. [2] In the electrolysis apparatus according to [1], The electrolysis device, wherein the power indicated by the power command is a power that varies over time. [3] In the electrolysis apparatus according to [1] or [2], The electrolysis device, wherein the power command indicates power that varies over time depending on an amount of power generated by renewable energy. [4] [1] to [3], wherein the electrolysis apparatus comprises: A memory unit that stores current-voltage characteristics for each temperature for each of the plurality of electrolytic cells; a plurality of temperature sensors installed in each of the plurality of electrolytic baths to detect temperatures of each of the plurality of electrolytic baths; Further equipped with The control unit reads out from the memory unit the current-voltage characteristics corresponding to the respective temperatures of the electrolytic cells detected by the temperature sensors, and controls the amount of current distribution based on the read current-voltage characteristics of the electrolytic cells. [5] [1] to [4], wherein the electrolysis apparatus comprises: the control unit controls the current distribution amount by solving a nonlinear programming problem based on the power command and the current-voltage characteristics of the multiple electrolytic cells so as to maximize the sum of the gas generation amounts. [6] [1] to [5], wherein the electrolysis apparatus comprises: The electrolysis apparatus, wherein the control unit solves the nonlinear programming problem using any one of a sequential quadratic programming method, a penalty function method, an augmented Lagrangian function method, and an interior point method. [7] [1] to [6], wherein the electrolysis apparatus comprises: Further comprising a plurality of voltage sensors each installed in each of the plurality of electrolytic baths to detect a voltage of each of the plurality of electrolytic baths; The control unit is calculating a sum of currents to be supplied to the electrolytic cells based on the voltages of the electrolytic cells detected by the voltage sensors and the power command; The electrolysis apparatus calculates the number of electrolytic cells to which current is supplied, out of the plurality of electrolytic cells, based on the sum of the currents and a lower limit of the allowable current value of the electrolytic cells. [8] [1] to [7], wherein the electrolysis apparatus comprises: A memory unit that stores current-voltage characteristics for each temperature for each of the plurality of electrolytic cells; a plurality of temperature sensors installed in each of the plurality of electrolytic baths to detect temperatures of each of the plurality of electrolytic baths; Further equipped with The control unit reads from the memory unit the current-voltage characteristics corresponding to the respective temperatures of the electrolytic cells detected by the temperature sensors, and selects which of the electrolytic cells to supply current to based on the read current-voltage characteristics of the electrolytic cells and the number of electrolytic cells to which current is to be supplied among the electrolytic cells. [9] [1] to [8], wherein the electrolysis apparatus comprises: Further comprising a plurality of voltage sensors each installed in each of the plurality of electrolytic baths to detect a voltage of each of the plurality of electrolytic baths; the control unit updates the current-voltage characteristics stored in the memory unit based on a difference between the voltage detected by the voltage sensor and an estimated value of the voltage of the electrolytic cell according to the amount of distributed current, the estimated value being calculated from the current-voltage characteristics read out from the memory unit.

[10] [1] to [9], wherein the electrolysis apparatus comprises: a plurality of current sensors installed in the plurality of electrolytic baths, each of which detects a current in the plurality of electrolytic baths; a plurality of voltage sensors installed in the plurality of electrolytic baths, each of which detects a voltage of the plurality of electrolytic baths; Further equipped with The control unit is calculating an actual value of a total sum of power usage of the plurality of electrolytic baths based on the currents of the plurality of electrolytic baths detected by the plurality of current sensors and the voltages of the plurality of electrolytic baths detected by the plurality of voltage sensors; an electrolysis device that controls the amount of current distribution based on a difference between the power command and the actual value so as to compensate for the difference.

[11] a plurality of electrolytic cells containing a liquid that is decomposed to generate a gas by the application of an electric current; a plurality of rectifiers disposed in the plurality of electrolytic cells, respectively, for supplying current to the plurality of electrolytic cells; a control unit that controls distribution amounts of currents supplied from the plurality of rectifiers to the plurality of electrolytic cells; Equipped with The control unit is obtaining a gas production command indicative of an amount of gas to be generated by the plurality of electrolytic cells in total; an electrolysis device that controls the amount of current distribution based on the gas production amount command so that a total amount of electric power used in the plurality of electrolytic cells is minimized. Effect of the Invention

[0009] According to the electrolysis device according to the present disclosure, when gas is generated by electrolysis using fluctuating power, gas can be generated efficiently. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic configuration diagram of an electrolysis device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the current-voltage characteristics of an electrolytic cell. [Diagram 3] 4 is a flowchart illustrating an example of an operation of the electrolysis device according to an embodiment. [Figure 4] FIG. 13 is a diagram showing an example of current-voltage characteristics when the number of electrolytic cells is two. [Diagram 5] FIG. 1 is a diagram showing an example of maximizing the amount of hydrogen production when the number of electrolytic cells is two. [Figure 6] 13 is a flowchart showing an example of an operation for selecting an electrolytic cell. [Figure 7] 10 is a flowchart showing an example of an operation for updating the current-voltage characteristics of an electrolytic cell. [Figure 8] FIG. 13 is a diagram showing a schematic diagram of updating the current-voltage characteristics of an electrolytic cell. [Figure 9] 11 is a conceptual diagram showing an operation of compensating for a difference between a power command and an actual value of power usage. FIG. [Figure 10] FIG. 13 is a schematic configuration diagram of an electrolysis device according to a modified example. [Figure 11] 10 is a flowchart showing an example of the operation of an electrolysis device according to a modified example. [Figure 12] FIG. 13 is a diagram showing an example of current-voltage characteristics when the number of electrolytic cells is two. [Figure 13] FIG. 13 is a diagram showing an example of minimizing the amount of power consumption when the number of electrolytic cells is two. [Figure 14] 10 is a conceptual diagram showing an operation of compensating for a difference between a gas production command and an actual value of the amount of gas produced. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0012] Fig. 1 is a schematic diagram of an electrolysis device 10 according to one embodiment. The configuration and functions of the electrolysis device 10 according to one embodiment will be described with reference to Fig. 1.

[0013] The electrolysis device 10 is a device capable of electrolyzing a liquid. The liquid electrolyzed by the electrolysis device 10 is a liquid that is decomposed to generate gas by being supplied with an electric current. The liquid may be, for example, water.

[0014] When the liquid is water, the electrolysis device 10 electrolyzes the water to generate hydrogen and oxygen as gas. The liquid electrolyzed by the electrolysis device 10 is not limited to water. The liquid may be, for example, salt water. In the following description of the embodiment, the case where the liquid is water will be taken as an example.

[0015] The electrolytic device 10 includes a plurality of electrolytic cells 11-1 to 11-n, a plurality of rectifiers 12-1 to 12-n, a plurality of current sensors 13-1 to 13-n, a plurality of voltage sensors 14-1 to 14-n, a plurality of voltage sensors 14-1 to 14-n, a plurality of temperature sensors 15-1 to 15-n, a control unit 16, and a memory unit 17.

[0016] In this embodiment, an example is shown in which the electrolysis device 10 includes n electrolytic cells 11-1 to 11-n, n rectifiers 12-1 to 12-n, n current sensors 13-1 to 13-n, n voltage sensors 14-1 to 14-n, and n temperature sensors 15-1 to 15-n. n may be any integer equal to or greater than 2.

[0017] When there is no particular need to distinguish between electrolytic cells 11-1 to 11-n, they may be referred to simply as "electrolytic cell 11." When there is no particular need to distinguish between rectifiers 12-1 to 12-n, they may be referred to simply as "rectifier 12." When there is no particular need to distinguish between current sensors 13-1 to 13-n, they may be referred to simply as "current sensor 13." When there is no particular need to distinguish between voltage sensors 14-1 to 14-n, they may be referred to simply as "voltage sensor 14." When there is no particular need to distinguish between temperature sensors 15-1 to 15-n, they may be referred to simply as "temperature sensor 15."

[0018] The electrolytic cell 11 contains a liquid to be electrolyzed. The liquid contained in the electrolytic cell 11 is a liquid that is decomposed to generate gas when a current is supplied thereto. The electrolytic cell 11 may be any electrolytic cell capable of electrolyzing a liquid. The liquid may be supplied to the electrolytic cell 11 by a pump or the like. In this embodiment, an example will be described in which the liquid is water.

[0019] The electrolytic cell 11 includes an anode and a cathode as electrodes. When a voltage is applied between the anode and cathode of the electrolytic cell 11 and a current flows through the water contained in the electrolytic cell 11, the water is electrolyzed to generate hydrogen and oxygen.

[0020] Hydrogen generated in the electrolytic cell 11 is sent to a hydrogen tank. Oxygen generated in the electrolytic cell 11 is sent to an oxygen tank. The hydrogen tank and the oxygen tank are not shown in Fig. 1.

[0021] Rectifiers 12-1 to 12-n are provided in electrolytic cells 11-1 to 11-n, respectively. Rectifiers 12-1 to 12-n are capable of supplying current to electrolytic cells 11-1 to 11-n, respectively.

[0022] The rectifiers 12-1 to 12-n are supplied with electric power from a power generation device 1 located outside the electrolysis device 10.

[0023] The power generating device 1 is a power generating device that generates power using renewable energy. The renewable energy may be, for example, solar power, wind power, hydroelectric power, geothermal power, etc. Since the power generating device 1 generates power using renewable energy, the power that the power generating device 1 supplies to the rectifiers 12-1 to 12-n varies over time.

[0024] The rectifier 12 is electrically connected to the anode and cathode of the electrolytic cell 11. The rectifier 12 converts the power supplied from the power generation device 1 into direct current and supplies a current between the anode and cathode of the electrolytic cell 11. The current supplied by the rectifier 12 flows through the water contained in the electrolytic cell 11.

[0025] The rectifier 12 can control the magnitude of the current supplied to the electrolytic cell 11 in response to a command from the control unit 16 .

[0026] Rectifier 12 may be of any configuration that is capable of controlling the amount of current it provides.

[0027] Current sensors 13-1 to 13-n are installed in electrolytic baths 11-1 to 11-n, respectively. Current sensors 13-1 to 13-n are capable of detecting the currents in electrolytic baths 11-1 to 11-n, respectively.

[0028] Here, the current of the electrolytic cell 11 means the current supplied to the electrolytic cell 11 by the rectifier 12 and flowing between the anode and cathode of the electrolytic cell 11 .

[0029] The current sensor 13 may be a current sensor of any configuration.

[0030] Current sensor 13 outputs the detected current value to control unit 16. Note that in Fig. 1, the connection between current sensor 13 and control unit 16 is omitted.

[0031] Voltage sensors 14-1 to 14-n are installed in electrolytic baths 11-1 to 11-n, respectively. Voltage sensors 14-1 to 14-n are capable of detecting the voltages of electrolytic baths 11-1 to 11-n, respectively.

[0032] Here, the voltage of the electrolytic cell 11 means the voltage between the anode and cathode of the electrolytic cell 11 .

[0033] Voltage sensor 14 may be a voltage sensor of any configuration.

[0034] Voltage sensor 14 outputs the detected voltage value to control unit 16. Note that the connection between voltage sensor 14 and control unit 16 is omitted in FIG.

[0035] Temperature sensors 15-1 to 15-n are provided in electrolytic baths 11-1 to 11-n, respectively. Temperature sensors 15-1 to 15-n are capable of detecting the temperatures of electrolytic baths 11-1 to 11-n, respectively.

[0036] Temperature sensor 15 may be a temperature sensor of any configuration.

[0037] Temperature sensor 15 outputs the detected temperature value to control unit 16. Note that in Fig. 1, the connection between temperature sensor 15 and control unit 16 is omitted.

[0038] The control unit 16 controls the entire electrolysis device 10 and each block of the electrolysis device 10. The control unit 16 includes at least one processor, at least one dedicated circuit, or a combination of these. The processor is a general-purpose processor such as a CPU (Central Processing Unit), or a dedicated processor specialized for a specific process. The dedicated circuit is, for example, a FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0039] The control unit 16 acquires a power command from outside the electrolysis device 10. The power command is a command that instructs the power to be supplied to all of the plurality of electrolytic cells 11-1 to 11-n.

[0040] The power command may be, for example, a command transmitted by a server of an organization that manages the power generation device 1. The power command may be a command that varies based on the amount of power generated by the power generation device 1. In other words, when the amount of power generated by the power generation device 1 is large, the power command instructs a large amount of power, and when the amount of power generated by the power generation device 1 is small, the power command instructs a small amount of power.

[0041] The amount of power generated by the power generation device 1 varies over time. Therefore, the power commanded by the power command varies over time. In addition, since the power generation device 1 generates power using renewable energy, the power commanded by the power command varies over time depending on the amount of power generated by renewable energy.

[0042] Based on the acquired power command, control unit 16 controls the distribution amount of current supplied by rectifiers 12-1 to 12-n to electrolytic cells 11-1 to 11-n so as to maximize the sum of the amounts of hydrogen generated (amount of gas generated) by electrolytic cells 11-1 to 11-n.

[0043] The operation of the control unit 16 will be described in detail later.

[0044] The storage unit 17 may be, for example, a semiconductor memory, a magnetic memory, an optical memory, or the like. The storage unit 17 may function as, for example, a main storage device, an auxiliary storage device, or a cache memory. The storage unit 17 stores any information used in the operation of the electrolysis device 10. For example, the storage unit 17 may store a system program, an application program, various information, and the like.

[0045] Memory unit 17 stores the current-voltage characteristics for each temperature for each of multiple electrolytic cells 11-1 to 11-n. The current-voltage characteristics of electrolytic cell 11 refer to the relationship between current and voltage when rectifier 12 supplies current to electrolytic cell 11 and the current flows through the water contained in electrolytic cell 11. The voltage at this time is the voltage between the anode and cathode of electrolytic cell 11.

[0046] The current-voltage characteristics of electrolytic cell 11 differ for each electrolytic cell 11. Therefore, memory unit 17 stores the current-voltage characteristics for each electrolytic cell 11. Furthermore, the current-voltage characteristics of electrolytic cell 11 depend on the temperature of electrolytic cell 11. Therefore, memory unit 17 stores the current-voltage characteristics for each temperature for each electrolytic cell 11.

[0047] The current-voltage characteristics of electrolytic cell 11 stored in memory unit 17 have been created by fitting an approximation equation based on the current and voltage that have been actually measured in advance.

[0048] Fig. 2 shows an example of the current-voltage characteristics of a certain electrolytic cell 11 stored in memory unit 17. In the example shown in Fig. 2, memory unit 17 stores current-voltage characteristics when the temperatures of electrolytic cell 11 are 30[°C], 50[°C], 60[°C], 70[°C], 80[°C], and 90[°C]. Note that the current-voltage characteristics shown in Fig. 2 are just an example, and memory unit 17 may store current-voltage characteristics at finer temperature intervals, or may store current-voltage characteristics at coarser temperature intervals.

[0049] The amount of hydrogen generated by the electrolytic cell 11 is proportional to the current of the electrolytic cell 11. The power consumption of the electrolytic cell 11 is the product of the current of the electrolytic cell 11 and the voltage of the electrolytic cell 11. Therefore, an electrolytic cell 11 with a lower voltage at the same current can be said to be an electrolytic cell 11 with better performance. This is because a lower voltage at the same current means that less power is consumed to generate the same amount of hydrogen.

[0050] The operation of the electrolysis device 10 will be described with reference to the flow chart shown in FIG.

[0051] Step S101: The control unit 16 acquires a power command from outside the electrolysis device 10. The power command is a command that instructs the power to be supplied to all of the electrolytic cells 11-1 to 11-n. The power instructed by the power command varies with time.

[0052] Step S102: The control unit 16 reads out the upper and lower limits of the allowable current value of the electrolytic cell 11 from the storage unit 17.

[0053] The upper limit of the allowable current value of electrolytic cell 11 is the upper limit of the current that can be passed by electrolytic cell 11. The lower limit of the allowable current value of electrolytic cell 11 is the lower limit of the current that can be passed by electrolytic cell 11. The upper and lower limits of the allowable current value of electrolytic cell 11 are stored in memory unit 17.

[0054] Step S103: Control unit 16 acquires the temperatures of electrolytic baths 11-1 to 11-n detected by temperature sensors 15-1 to 15-n from temperature sensors 15-1 to 15-n.

[0055] Step S104: Control unit 16 reads out from storage unit 17 the current-voltage characteristics of electrolytic baths 11-1 to 11-n, which correspond to the temperatures of electrolytic baths 11-1 to 11-n detected by temperature sensors 15-1 to 15-n.

[0056] For example, when the temperature of electrolytic bath 11-1 detected by temperature sensor 15-1 is 60[°C], control unit 16 reads out from memory unit 17 the current-voltage characteristics for a temperature of 60[°C] among the current-voltage characteristics of electrolytic bath 11-1 stored in memory unit 17. Control unit 16 similarly reads out the current-voltage characteristics for the other electrolytic baths 11-2 to 11-n.

[0057] Step S105: Control unit 16 calculates the current distribution amount that maximizes the total amount of hydrogen generated, based on the power command acquired in step S101 and the current-voltage characteristics of the multiple electrolytic cells 11-1 to 11-n read from memory unit 17 in step S104.

[0058] The method by which the control unit 16 calculates the current distribution amount that maximizes the total amount of hydrogen generation will be described in more detail below.

[0059] Power P of electrolytic cell 11-i iis expressed by the following formula (1): Here, electrolytic cell 11-i means the i-th electrolytic cell 11 among electrolytic cells 11-1 to 11-n. P i =E ci (I i , T i )I i (1) Here, I i is the current in the electrolytic cell 11-i. T i is the temperature of the electrolytic cell 11-i. E ci (I i , T i ) is the voltage of the electrolytic cell 11-i.

[0060] Voltage E of electrolytic cell 11-i ci (I i , T i ) is the current I i , temperature T i This is because the voltage E ci But the current I i , temperature T i Specifically, the control unit 16 controls the temperature T i The current-voltage characteristic for the current I i By reading the voltage corresponding to the voltage E ci can be read.

[0061] The amount of hydrogen generated by the electrolytic cell 11-i is F i is expressed as the following equation (2). F i =I i Alpha (2) Here, α is a coefficient.

[0062] Control unit 16 solves a nonlinear programming problem so as to maximize the sum of the amounts of hydrogen generated by electrolytic cells 11-1 to 11-n, and calculates the distribution amount of current to be supplied to electrolytic cells 11-1 to 11-n.

[0063] The objective function when the control unit 16 solves the nonlinear programming problem is expressed as in the following equation (3).

number

[0064] The constraint conditions when the control unit 16 solves the nonlinear programming problem are expressed as the following equations (4) and (5).

number

number

[0065] As described above, control unit 16 solves a nonlinear programming problem using equation (3) as an objective function and equations (4) and (5) as constraints to calculate the distribution amount of current to be supplied to electrolytic baths 11-1 to 11-n so as to maximize the sum of the amounts of hydrogen generated by electrolytic baths 11-1 to 11-n.

[0066] The control unit 16 may solve the nonlinear programming problem using, for example, any one of the sequential quadratic programming method, the penalty function method, the augmented Lagrangian function method, and the interior point method.

[0067] Step S106: Having calculated the distribution amount of current to be supplied to electrolytic baths 11-1 to 11-n, control unit 16 controls rectifiers 12-1 to 12-n so as to supply current to electrolytic baths 11-1 to 11-n at the calculated distribution amount of current.

[0068] <Example> 4 and 5, a specific example of a case where the control unit 16 solves a nonlinear programming problem will be described.

[0069] As a specific example, a case where the number of electrolytic cells 11 is two, that is, n = 2, will be described. Furthermore, the values ​​of various parameters are assumed to be as follows. α=1 P req =50[kW] u b =10 [kA] l b =1 [kA] T 1 =30[℃] T 2 =40[℃]

[0070] FIG. 4 is a graph showing the current-voltage characteristics of electrolytic cell 11-1 and electrolytic cell 11-2 when the various parameters are set to the above values.

[0071] The graph on the left side of Fig. 4 is a graph of the current-voltage characteristics of electrolytic cell 11-1 at 30[°C], and the graph on the right side of Fig. 4 is a graph of the current-voltage characteristics of electrolytic cell 11-2 at 40[°C].

[0072] The control unit 16 reads out the two current-voltage characteristics shown in FIG.

[0073] FIG. 5 is a table showing how the control unit 16 solves a nonlinear programming problem using the sequential quadratic programming method.

[0074] In Fig. 5, I1 and E1 respectively indicate the current and voltage of electrolytic cell 11-1. I2 and E2 respectively indicate the current and voltage of electrolytic cell 11-2. P1 and P2 respectively indicate the power of electrolytic cell 11-1 and the power of electrolytic cell 11-2. I1+I2 respectively indicates the sum of the current I1 of electrolytic cell 11-1 and the current I2 of electrolytic cell 11-2. P indicates the sum of the power P1 of electrolytic cell 11-1 and the power P2 of electrolytic cell 11-2.

[0075] When solving the nonlinear programming problem, the control unit 16 sets the following constraints. P=50[kW] 1 [kA] ≤ I1 ≤ 10 [kA] 1[kA]≦I2≦10[kA]

[0076] When solving a nonlinear programming problem, the control unit 16 sets the maximization of I1+I2 as an objective function.

[0077] 5, when I1=7 [kA] and I2=7.4 [kA], I1+I2 is maximum. Therefore, the control unit 16 controls the rectifiers 12-1 and 12-2 so that I1=7 [kA] and I2=7.4 [kA].

[0078] <Selection of electrolytic cell> The electrolysis device 10 may perform electrolysis by supplying current to only a selected number of electrolysis cells 11, rather than supplying current to all of the electrolysis cells 11-1 to 11-n. For example, when the number of electrolysis cells 11 is four, i.e., n=4, the electrolysis device 10 may perform electrolysis by supplying current to only three of the electrolysis cells 11.

[0079] The process of selecting an electrolytic cell 11 to supply a current will now be described with reference to the flow chart shown in FIG.

[0080] Step S201: The control unit 16 acquires a power command from outside the electrolysis device 10.

[0081] Step S202: Control unit 16 acquires the voltages of electrolytic cells 11-1 to 11-n detected by voltage sensors 14-1 to 14-n from voltage sensors 14-1 to 14-n.

[0082] Step S203: Control unit 16 determines the number of operating electrolytic baths 11. Control unit 16 determines that electrolytic baths 11 whose voltage detected by voltage sensor 14 is equal to or greater than a predetermined threshold are operating electrolytic baths 11. For example, if the number of electrolytic baths 11 whose voltage is equal to or greater than the predetermined threshold is three, control unit 16 determines that the number of operating electrolytic baths 11 is three.

[0083] Step S204: The control unit 16 calculates a filtered value of the voltage of the electrolytic cell 11 acquired from the voltage sensor 14. Here, the filtered value means a value obtained by passing the voltage of the electrolytic cell 11 through a low-pass filter. The control unit 16 may, for example, calculate the filtered value by passing the voltage of the electrolytic cell 11 acquired from the voltage sensor 14 through a digital filter. Alternatively, for example, the control unit 16 may obtain a filtered value by passing the voltage of the electrolytic cell 11 acquired from the voltage sensor 14 through an analog filter.

[0084] Step S205: Control unit 16 calculates the average value of the voltage of electrolytic cell 11 based on the filtered value of the voltage of electrolytic cell 11. For example, control unit 16 may calculate the average value of the voltage of electrolytic cell 11 based on the following formula (6).

number

[0085] Step S206: The control unit 16 calculates the sum of the currents to be supplied to the multiple electrolytic baths 11 that are in operation based on the average voltages of the electrolytic baths 11 calculated by the above formula (6) and the power command. For example, the control unit 16 calculates the sum I all (t) may be calculated.

number

[0086] Step S207: The control unit 16 reads out the lower limit of the allowable current value of the electrolytic cell 11 from the storage unit 17.

[0087] Step S208: The control unit 16 calculates the number of electrolytic baths 11 to which current will be supplied based on the total current calculated by the above formula (7) and the lower limit of the allowable current value of the electrolytic baths 11. For example, if the total current is 1.25 [kA] and the lower limit of the allowable current value of the electrolytic baths 11 is 1 [kA], the control unit 16 calculates that the number of electrolytic baths 11 to which current will be supplied is 1.

[0088] Step S209: Control unit 16 acquires the temperatures of electrolytic baths 11-1 to 11-n detected by temperature sensors 15-1 to 15-n from temperature sensors 15-1 to 15-n.

[0089] Step S210: Control unit 16 reads out from memory unit 17 the current-voltage characteristics of electrolytic baths 11-1 to 11-n that correspond to the temperatures of electrolytic baths 11-1 to 11-n detected by temperature sensors 15-1 to 15-n.

[0090] Step S211: Control unit 16 selects which of electrolytic cells 11-1 to 11-n to supply current to, based on the current-voltage characteristics of electrolytic cells 11-1 to 11-n read from memory unit 17 in step S210 and the number of electrolytic cells 11 to supply current calculated in step S208. Control unit 16 selects electrolytic cells 11 with smaller voltages when compared at the same current, the number of which corresponds to the number of electrolytic cells 11 to supply current calculated in step S208.

[0091] When the control unit 16 selects the electrolytic cell 11, it may execute the process of the flowchart shown in FIG.

[0092] <Update of current-voltage characteristics> 3 to control rectifiers 12-1 to 12-n so as to supply current to electrolytic baths 11-1 to 11-n at the calculated current distribution amounts, and may then update the current-voltage characteristics stored in memory unit 17 at predetermined intervals based on the voltage detected by voltage sensor 14. The current-voltage characteristics of electrolytic bath 11 change as electrolytic bath 11 deteriorates, but by updating the current-voltage characteristics stored in memory unit 17 at predetermined intervals, it is possible to correct changes in the current-voltage characteristics due to deterioration of electrolytic bath 11 as needed.

[0093] The process in which the electrolysis device 10 updates the current-voltage characteristics will be described with reference to the flowchart shown in FIG.

[0094] Step S301: When control unit 16 controls rectifiers 12-1 to 12-n, control unit 16 acquires the voltages of electrolytic cells 11-1 to 11-n detected by voltage sensors 14-1 to 14-n from voltage sensors 14-1 to 14-n.

[0095] Step S302: Control unit 16 calculates an estimate of the voltage of electrolytic cell 11 from the current-voltage characteristic read out from memory unit 17. At this time, control unit 16 calculates the estimate of the voltage of electrolytic cell 11 based on the distribution amount of current supplied to electrolytic cell 11 and the current-voltage characteristic.

[0096] Step S303: Control unit 16 calculates, for each electrolytic cell 11, the difference between the actual voltage value detected by voltage sensor 14 and the calculated estimated voltage value.

[0097] Step S304: The control unit 16 updates the current-voltage characteristics stored in the storage unit 17 based on the calculated difference.

[0098] FIG. 8 shows an example of how the current-voltage characteristics are updated.

[0099] The diagram on the left side of Fig. 8 is a diagram showing an example of the current-voltage characteristic before updating. Graph 101 shows the current-voltage characteristic before updating. Reference numeral 102 shows the estimated voltage value. Reference numeral 103 shows the actual measured voltage value. Reference numeral 104 shows the difference between the actual measured voltage value and the estimated voltage value.

[0100] The diagram on the right side of Fig. 8 shows an example of the current-voltage characteristic after updating. Graph 101 shows the current-voltage characteristic before updating. Reference numeral 103 shows the actual measured value of the voltage. Reference numeral 104 shows the difference between the actual measured value of the voltage and the estimated value of the voltage. Graph 105 shows the current-voltage characteristic after updating.

[0101] As shown in the diagram on the right side of FIG. 8, the control unit 16 may add the difference between the actual measured value of the voltage detected by the voltage sensor 14 and the calculated estimated value of the voltage to the current-voltage characteristics before the update, to obtain the updated current-voltage characteristics.

[0102] <Compensation for the difference between power command and actual value> After executing the process shown in the flowchart of Fig. 3, the electrolysis device 10 controls the rectifiers 12-1 to 12-n so as to supply current to the electrolytic baths 11-1 to 11-n at the calculated current distribution amount. In this case, the power value specified by the power command and the actual total sum of the power usage of the multiple electrolytic baths 11-1 to 11-n should essentially be the same value, but there are cases in which the power value specified by the power command and the actual total sum of the power usage do not match. In this case, the electrolysis device 10 may control the distribution amount of the current supplied to the electrolytic baths 11-1 to 11-n so as to compensate for the difference between the power value specified by the power command and the actual total sum of the power usage.

[0103] FIG. 9 is a conceptual diagram showing an operation of compensating for a difference between a power value instructed by a power command and an actual value of power usage.

[0104] When control unit 16 controls rectifiers 12-1 to 12-n to supply current to electrolytic cells 11-1 to 11-n at the calculated current distribution amount, rectifiers 12-1 to 12-n consume power. In addition, some power is consumed as disturbance by devices other than rectifiers 12-1 to 12-n.

[0105] The actual value of power consumption of the electrolysis apparatus 10 is the sum of the power consumed by the rectifiers 12-1 to 12-n and the power consumed as disturbance. The control unit 16 can calculate the power consumed by the rectifiers 12-1 to 12-n based on the current of each electrolytic cell 11 detected by the current sensor 13 and the voltage of each electrolytic cell 11 detected by the voltage sensor 14.

[0106] Control unit 16 may execute a process of performing PID (Proportional-Integral-Differential) control on the difference between the actual value of power usage and the power value instructed by the power command, and control rectifiers 12-1 to 12-n by adding the power value instructed by the power command and the PID controlled value as the power command in step S101 of Fig. 3. This allows control unit 16 to compensate only for the difference between the actual value of power usage and the power value instructed by the power command.

[0107] By executing such feedback processing, the control unit 16 can compensate for the difference between the power value instructed by the power command and the actual value of the total power usage.

[0108] As described above, the electrolytic device 10 according to this embodiment includes a plurality of electrolytic cells 11-1 to 11-n that contain a liquid that is decomposed to generate gas when supplied with a current, a plurality of rectifiers 12-1 to 12-n that are provided in the respective electrolytic cells 11-1 to 11-n and supply a current to each of the electrolytic cells 11-1 to 11-n, and a control unit 16 that controls the distribution amount of the current supplied by the rectifiers 12-1 to 12-n to the electrolytic cells 11-1 to 11-n. The control unit 16 obtains a power command that indicates the power to be supplied to all of the electrolytic cells 11-1 to 11-n, and controls the distribution amount of the current based on the obtained power command so as to maximize the sum of the amounts of gas generated by the electrolytic cells 11-1 to 11-n. As a result, when acquiring a power command that varies with time, the electrolysis device 10 according to this embodiment can control the distribution amount of current supplied from the multiple rectifiers 12-1 to 12-n to the multiple electrolytic cells 11-1 to 11-n so as to maximize the total amount of gas generated. Therefore, the electrolysis device 10 according to this embodiment can generate gas efficiently when performing electrolysis using fluctuating power to generate gas.

[0109] (Modification) Fig. 10 is a schematic diagram of an electrolysis device 10a according to a modified example. The electrolysis device 10a according to a modified example will be described with reference to Fig. 10.

[0110] The electrolysis device 10a includes a plurality of electrolytic cells 11-1 to 11-n, a plurality of rectifiers 12-1 to 12-n, a plurality of current sensors 13-1 to 13-n, a plurality of voltage sensors 14-1 to 14-n, a plurality of temperature sensors 15-1 to 15-n, a control unit 16a, and a memory unit 17.

[0111] The electrolysis device 10a according to the modified example differs from the electrolysis device 10 shown in Fig. 1 in that, instead of acquiring a power command, the electrolysis device 10a acquires a gas production amount command from outside the electrolysis device 10a. The gas production amount command is a command that indicates the amount of gas to be generated in total by the multiple electrolytic cells 11-1 to 11-n. When the liquid electrolyzed by the electrolysis device 10a according to the modified example is water, the amount of gas indicated by the gas production amount command is the amount of hydrogen.

[0112] The electrolysis apparatus 10a relating to the deformation amount also differs from the electrolysis apparatus 10 shown in FIG. 1 in that, when electrolyzing water based on the acquired gas production volume command, the electrolysis apparatus 10a controls the distribution amount of current supplied by the multiple rectifiers 12-1 to 12-n to the multiple electrolytic cells 11-1 to 11-n so as to minimize the sum of the power used in the multiple electrolytic cells 11-1 to 11-n.

[0113] Regarding the electrolysis device 10a according to the modified example, differences from the electrolysis device 10 shown in FIG. 1 will be mainly described, and descriptions of commonalities or similarities with the electrolysis device 10 shown in FIG. 1 will be omitted as appropriate.

[0114] The operation of the electrolysis device 10a according to the modified example will be described with reference to the flowchart shown in FIG.

[0115] Step S401: The control unit 16a acquires a gas production amount command from outside the electrolysis device 10a. The gas production amount commanded by the gas production amount command varies with time.

[0116] Step S402: The control unit 16a reads out the upper and lower limits of the allowable current value of the electrolytic cell 11 from the storage unit 17.

[0117] Step S403: Control unit 16a acquires the temperatures of electrolytic baths 11-1 to 11-n detected by temperature sensors 15-1 to 15-n from temperature sensors 15-1 to 15-n.

[0118] Step S404: Control unit 16a reads out from storage unit 17 the current-voltage characteristics of electrolytic baths 11-1 to 11-n that correspond to the temperatures of electrolytic baths 11-1 to 11-n detected by temperature sensors 15-1 to 15-n.

[0119] Step S405: Control unit 16a calculates the current distribution amount that minimizes the total amount of power used, based on the gas production volume command acquired in step S401 and the current-voltage characteristics of multiple electrolytic cells 11-1 to 11-n read from memory unit 17 in step S404.

[0120] A method for calculating the current distribution amount that minimizes the total amount of power used by the control unit 16a will be described in more detail below.

[0121] Control unit 16a solves a nonlinear programming problem so as to minimize the sum of the power used by electrolytic baths 11-1 to 11-n, and calculates the distribution amount of current to be supplied to electrolytic baths 11-1 to 11-n.

[0122] The objective function used by the control unit 16a to solve a nonlinear programming problem is expressed as in the following equation (8).

number

[0123] The constraint conditions when the control unit 16a solves the nonlinear programming problem are expressed as the following equations (9) and (10).

number

number

[0124] As described above, control unit 16a solves a nonlinear programming problem using equation (8) as the objective function and equations (9) and (10) as constraints so as to minimize the total power used by electrolytic baths 11-1 to 11-n, and calculates the distribution amount of current to be supplied to electrolytic baths 11-1 to 11-n.

[0125] The control unit 16a may solve the nonlinear programming problem using, for example, any one of the sequential quadratic programming method, the penalty function method, the augmented Lagrangian function method, and the interior point method.

[0126] Step S406: Having calculated the distribution amount of current to be supplied to electrolytic baths 11-1 to 11-n, control unit 16a controls rectifiers 12-1 to 12-n so as to supply current to electrolytic baths 11-1 to 11-n at the calculated distribution amount of current.

[0127] In this way, the electrolysis device 10a according to the modified example controls the rectifiers 12-1 to 12-n so as to minimize the total power consumed by the electrolytic cells 11-1 to 11-n, thereby enabling the electrolysis device 10a according to the modified example to efficiently produce hydrogen with low power consumption.

[0128] <Specific examples of modified examples> 12 and 13, a specific example of a case where the control unit 16a solves a nonlinear programming problem will be described.

[0129] As a specific example, a case where the number of electrolytic cells 11 is two, that is, n = 2, will be described. Furthermore, the values ​​of various parameters are assumed to be as follows. α=1 F req =12[kA] u b =10 [kA] l b =1 [kA] T 1 =30[℃] T 2 =40[℃]

[0130] FIG. 12 is a graph showing the current-voltage characteristics of electrolytic cell 11-1 and electrolytic cell 11-2 when the various parameters are set to the above values.

[0131] The graph on the left side of Fig. 12 is a graph of the current-voltage characteristics of electrolytic cell 11-1 at 30[°C], and the graph on the right side of Fig. 12 is a graph of the current-voltage characteristics of electrolytic cell 11-2 at 40[°C].

[0132] The control unit 16a reads out the two current-voltage characteristics shown in FIG.

[0133] FIG. 13 is a table showing how the control unit 16a solves a nonlinear programming problem using the sequential quadratic programming method.

[0134] In Fig. 13, I1 and E1 respectively indicate the current and voltage of electrolytic cell 11-1. I2 and E2 respectively indicate the current and voltage of electrolytic cell 11-2. P1 and P2 respectively indicate the power of electrolytic cell 11-1 and the power of electrolytic cell 11-2. I1+I2 respectively indicates the sum of the current I1 of electrolytic cell 11-1 and the current I2 of electrolytic cell 11-2. P indicates the sum of the power P1 of electrolytic cell 11-1 and the power P2 of electrolytic cell 11-2.

[0135] When solving a nonlinear programming problem, the control unit 16a sets the following constraints. I1+I2=12[kA] 1 [kA] ≤ I1 ≤ 10 [kA] 1[kA]≦I2≦10[kA]

[0136] When solving a nonlinear programming problem, the control unit 16a sets the minimization of P as an objective function.

[0137] 13, when I1=5 [kA] and I2=7 [kA], P is minimum. Therefore, the control unit 16a controls the rectifiers 12-1 and 12-2 so that I1=5 [kA] and I2=7 [kA].

[0138] <Compensation for the difference between the gas production volume command and the actual value in the modified example> After executing the process shown in the flowchart of Fig. 11, the electrolysis device 10a controls the rectifiers 12-1 to 12-n to supply current to the electrolytic cells 11-1 to 11-n at the calculated current distribution amount. In this case, the gas production amount specified by the gas production amount command should essentially be the same as the actual value of the gas production amount produced by the multiple electrolytic cells 11-1 to 11-n, but there are cases where the gas production amount specified by the gas production amount command does not match the actual value of the gas production amount. In this case, the electrolysis device 10a may control the distribution amount of current supplied to the electrolytic cells 11-1 to 11-n to compensate for the difference between the gas production amount specified by the gas production amount command and the actual value of the gas production amount.

[0139] FIG. 14 is a conceptual diagram showing an operation of compensating for the difference between the gas production amount instructed by the gas production amount command and the actual value of the gas production amount.

[0140] When control unit 16a controls rectifiers 12-1 to 12-n so as to supply current to electrolytic cells 11-1 to 11-n at the calculated current distribution amount, rectifiers 12-1 to 12-n produce gas.

[0141] The control unit 16a can obtain the performance values ​​of the amounts of gas produced by the rectifiers 12-1 to 12-n from a sensor capable of detecting the amount of gas produced.

[0142] The control unit 16a may execute PID control on the difference between the actual value of the gas production amount and the gas production amount instructed by the gas production amount command, and execute a process of controlling the rectifiers 12-1 to 12-n by adding the gas production amount instructed by the gas production amount command and the PID controlled value as the gas production amount command in step S401 of Fig. 11. This allows the control unit 16a to compensate only for the difference between the actual value of the gas production amount and the gas production amount instructed by the gas production amount command.

[0143] By executing such feedback processing, the control unit 16a can compensate for the difference between the gas production amount instructed by the gas production amount command and the actual value of the gas production amount.

[0144] Although the above-mentioned embodiment has been described as a representative example, it is obvious to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present disclosure. Therefore, the present invention should not be interpreted as being limited by the above-mentioned embodiment, and various modifications or changes are possible without departing from the scope of the claims.

[0145] For example, in the above embodiment, the electrolysis device 10 is supplied with power from the power generation device 1, but the electrolysis device 10 may be supplied with power from a commercial power system. [Explanation of symbols]

[0146] 1. Power generation equipment 10, 10a electrolyzer 11 Electrolytic cell 12 Rectifier 13 Current Sensor 14 Voltage Sensor 15 Temperature Sensor 16, 16a Control section 17 Memory section

Claims

1. a plurality of electrolytic cells containing a liquid that is decomposed to generate a gas by the application of an electric current; a plurality of rectifiers disposed in the plurality of electrolytic cells, respectively, for supplying current to the plurality of electrolytic cells; a control unit that controls distribution amounts of currents supplied from the plurality of rectifiers to the plurality of electrolytic cells; Equipped with The control unit is obtaining a power command indicative of power to be supplied to the entirety of the plurality of electrolytic cells; an electrolysis device that controls the current distribution amount based on the power command so that the sum of the amounts of gas generated by the plurality of electrolytic cells is maximized.

2. 2. The electrolysis apparatus according to claim 1, The electrolysis device, wherein the power indicated by the power command is a power that varies over time.

3. 2. The electrolysis apparatus according to claim 1, The electrolysis device, wherein the power command indicates power that varies over time depending on an amount of power generated by renewable energy.

4. 2. The electrolysis apparatus according to claim 1, A memory unit that stores current-voltage characteristics for each temperature for each of the plurality of electrolytic cells; a plurality of temperature sensors installed in each of the plurality of electrolytic baths to detect temperatures of each of the plurality of electrolytic baths; Further equipped with The control unit reads out from the memory unit the current-voltage characteristics corresponding to the temperatures of the electrolytic cells detected by the temperature sensors, and controls the amount of current distribution based on the read current-voltage characteristics of the electrolytic cells.

5. 5. The electrolysis apparatus according to claim 4, the control unit controls the current distribution amount by solving a nonlinear programming problem based on the power command and the current-voltage characteristics of the multiple electrolytic cells so as to maximize the sum of the gas generation amounts.

6. 6. The electrolysis apparatus according to claim 5, The electrolysis apparatus, wherein the control unit solves the nonlinear programming problem using any one of a sequential quadratic programming method, a penalty function method, an augmented Lagrangian function method, and an interior point method.

7. 2. The electrolysis apparatus according to claim 1, Further comprising a plurality of voltage sensors each installed in each of the plurality of electrolytic baths to detect a voltage of each of the plurality of electrolytic baths; The control unit is calculating a sum of currents to be supplied to the electrolytic cells based on the voltages of the electrolytic cells detected by the voltage sensors and the power command; The electrolysis apparatus calculates the number of electrolytic cells to which current is supplied, out of the plurality of electrolytic cells, based on the sum of the currents and a lower limit of the allowable current value of the electrolytic cells.

8. 8. The electrolysis device according to claim 7, A memory unit that stores current-voltage characteristics for each temperature for each of the plurality of electrolytic cells; a plurality of temperature sensors installed in each of the plurality of electrolytic baths to detect temperatures of each of the plurality of electrolytic baths; Further equipped with The control unit reads from the memory unit the current-voltage characteristics corresponding to the temperatures of each of the multiple electrolytic cells detected by the multiple temperature sensors, and selects which of the multiple electrolytic cells to supply current to based on the read current-voltage characteristics of the multiple electrolytic cells and the number of electrolytic cells to which current is to be supplied among the multiple electrolytic cells.

9. 5. The electrolysis apparatus according to claim 4, Further comprising a plurality of voltage sensors each installed in each of the plurality of electrolytic baths to detect a voltage of each of the plurality of electrolytic baths; The control unit updates the current-voltage characteristics stored in the memory unit based on a difference between the voltage detected by the voltage sensor and an estimated value of the voltage of the electrolytic cell according to the amount of distributed current, the estimated value being calculated from the current-voltage characteristics read from the memory unit.

10. 2. The electrolysis apparatus according to claim 1, a plurality of current sensors installed in the plurality of electrolytic baths, each of which detects a current in the plurality of electrolytic baths; a plurality of voltage sensors installed in the plurality of electrolytic baths, each of which detects a voltage of the plurality of electrolytic baths; Further equipped with The control unit is calculating an actual value of a total sum of power usage of the plurality of electrolytic baths based on the currents of the plurality of electrolytic baths detected by the plurality of current sensors and the voltages of the plurality of electrolytic baths detected by the plurality of voltage sensors; an electrolysis device that controls the amount of current distribution based on a difference between the power command and the actual value so as to compensate for the difference.

11. a plurality of electrolytic cells containing a liquid that is decomposed to generate a gas by the application of an electric current; a plurality of rectifiers disposed in the plurality of electrolytic cells, respectively, for supplying current to the plurality of electrolytic cells; a control unit that controls distribution amounts of currents supplied from the plurality of rectifiers to the plurality of electrolytic cells; Equipped with The control unit is obtaining a gas production command indicative of an amount of gas to be generated by the plurality of electrolytic cells in total; an electrolysis device that controls the amount of current distribution based on the gas production amount command so that a total amount of electric power used in the plurality of electrolytic cells is minimized.

Images