Electrolysis device, method for controlling electrolysis device, and control program for electrolysis device

Abstract

Provided are: an electrolysis device for reducing a circulating current through a grounding wire; a method for controlling the electrolysis device; and a control program for the electrolysis device. This electrolysis device (1) includes an electrolysis cell (100) having a plurality of rectifiers (20) and a plurality of cell stacks (10) having a common positive electrode, wherein the respective positive electrodes of the cell stacks (10) are connected to respective positive electrodes of the rectifiers (20) installed in parallel, respective negative electrodes of the cell stacks (10) are connected to respective negative electrodes of the rectifiers (20), and a balance cable (80) for connecting the negative electrode of at least one of the cell stacks (10) and the negative electrode of at least one of the other cell stacks (10) is provided.

Description

Electrolytic device, electrolytic device control method, and electrolytic device control program

[0001] The present disclosure relates to an electrolysis device, a control method for an electrolysis device, and a control program for an electrolysis device.

[0002] In recent years, there has been a growing movement towards energy transition in order to achieve carbon neutrality. One of the measures for energy transition is the use of hydrogen gas turbines. Hydrogen production and storage technologies are being investigated for the use of hydrogen gas turbines.

[0003] Patent Document 1 discloses a technique for electrically connecting negative conductive members to each other in an SOEC that generates hydrogen using the electrolysis reaction of water to prevent an increase in the minimum potential difference. Patent Document 2 discloses a technique for an electrolytic treatment line for a metal strip in which a roll that comes into contact with the metal strip outside an electrolytic cell is grounded and a rectifier is controlled to reduce the current between the grounded roll and the ground part.

[0004] JP 2019-57407 A JP 2001-26900 A

[0005] However, in the invention of Patent Document 1, multiple cell stacks are connected in series, and no consideration is given to a configuration in which multiple cell stacks are connected in parallel. In the invention of Patent Document 1, grounding is performed at an intermediate point, and no consideration is given to circulating current via a grounding wire. In the invention of Patent Document 2, although the electrolytic current is adjusted to reduce the earth current, no consideration is given to the generation of circulating current via a grounding wire.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide an electrolysis device that reduces circulating current through a grounding wire, a control method for an electrolysis device, and a control program for an electrolysis device.

[0007] In order to solve the above problems, the electrolysis apparatus, the control method for the electrolysis apparatus, and the control program for the electrolysis apparatus of the present disclosure employ the following means: The electrolysis apparatus of the present disclosure is an electrolysis apparatus including a plurality of rectifiers and an electrolytic cell having a plurality of cell stacks with a common positive electrode, wherein the positive electrode of each of the cell stacks is connected to the positive electrode of each of the rectifiers installed in parallel, the negative electrode of each of the cell stacks is connected to the negative electrode of each of the rectifiers, and a balance cable is provided connecting the negative electrode of at least one of the cell stacks to the negative electrode of at least one of the other cell stacks.

[0008] The control method for an electrolysis device disclosed herein is a control method executed by a computer for an electrolysis device having a plurality of rectifiers and a plurality of cell stacks with a common positive electrode, the positive electrode of each of the cell stacks being connected to the positive electrode of each of the rectifiers installed in parallel, the negative electrode of each of the cell stacks being connected to the negative electrode of each of the rectifiers, balance cables connecting the negative electrode of at least one of the cell stacks to the negative electrode of at least one of the other cell stacks, and current sensors measuring current in the balance cables, and the control method controls the output current value of each of the rectifiers based on the current value measured by the current sensors.

[0009] The control program for the electrolysis device of the present disclosure causes a computer to execute the above-described control method.

[0010] According to the present disclosure, it is possible to reduce circulating currents that flow through the ground, reduce signal noise caused by circulating currents, and reduce costs by not using bus ducts, which are made of expensive materials.

[0011] Fig. 1 is a diagram illustrating a conventional electrolysis device; Fig. 2 is a diagram illustrating an electrolysis device according to some embodiments of the present disclosure; Fig. 3 is a diagram illustrating an example of a hardware configuration of a control device according to some embodiments of the present disclosure; Fig. 4 is a diagram illustrating an example of the function of a control device according to some embodiments of the present disclosure; Fig. 5 is a diagram illustrating a control flow of a control device according to some embodiments of the present disclosure.

[0012] An embodiment of an electrolysis apparatus, a control method for an electrolysis apparatus, and a control program for an electrolysis apparatus according to the present disclosure will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a conventional electrolysis apparatus. As illustrated in FIG. 1, the electrolysis apparatus 1 includes an electrolytic cell 100 and rectifiers 20a and 20b. A plurality of rectifiers 20a and 20b are installed in parallel. The electrolytic cell 100 includes cell stacks 10a and 10b. The electrolysis apparatus 1 according to the present disclosure is, for example, a water electrolysis apparatus. The plurality of cell stacks 10a and 10b in the electrolytic cell 100 are an assembly of a plurality of electrolysis cells (not shown). The cell stack 10 is formed, for example, by arranging a plurality of electrolysis cells in one direction. The cell stacks 10 share a common positive electrode (anode, + electrode). In this embodiment, the positive electrodes of the cell stacks 10 are shared in the center of the electrolytic cell 100, and the negative electrodes (cathode, - electrode) of the cell stacks 10 are provided at both ends of the electrolytic cell 100. The electrolytic cell 100 performs, for example, alkaline water electrolysis, and generates hydrogen by electrolyzing water contained in the electrolytic water when a DC voltage is applied from the rectifier 20 .

[0013] The negative electrode of the cell stack 10a is connected to the negative electrode of the rectifier 20a, and the negative electrode of the cell stack 10b is connected to the negative electrode of the rectifier 20b. Each rectifier 20 has a plurality of conversion circuits (units) inside.

[0014] A ground wire 30a is provided on the negative electrode side of the cell stack 10a. A ground wire 30b is provided on the negative electrode side of the cell stack 10b. In the following description, when distinguishing between the cell stacks 10, rectifiers 20, and ground wires 30, either "a" or "b" is added to the end of the name, and when not distinguishing between the cell stacks 10, rectifiers 20, and ground wires 30, the "a" or "b" is omitted.

[0015] When AC power is input to the rectifier 20 from the outside, the AC power is converted to DC power by the rectifier 20, and a DC voltage is applied from the positive electrode of the rectifier 20 to the positive electrode of the cell stack 10 in the electrolytic cell 100. The applied DC power is used for electrolysis of water in the electrolytic cell 100.

[0016] Current flows from the negative electrode of the cell stack 10 to the negative electrode of the rectifier 20. The negative electrodes of the cell stack 10 are each connected to a ground wire 30. The electrolytic cell 100 is heavy and expands and contracts, making it difficult to completely insulate it. For this reason, the ground wire 30 is an essential component.

[0017] If there is a performance difference between the cell stacks 10, for example, if cell stack 10a has better performance than cell stack 10b, a larger current will flow through cell stack 10a than through cell stack 10b. The performance difference occurs due to, for example, the degree of deterioration or an initial performance error. If a larger current flows through cell stack 10a than through cell stack 10b, a potential difference occurs between ground wire 30a and ground wire 30b, causing a circulating current to flow from ground wire 30a to ground wire 30b.

[0018] Furthermore, there is a possibility that a circulating current will flow via various paths through which current flows, such as pipes connected to the electrolytic cell 100 and the building in which the electrolysis device 1 is installed.

[0019] For example, if an unexpected circulating current flows to the ground, there is a possibility of electric shock if a person touches that part. The current flowing to the ground may cause fluctuations in the potential of the grounding grid. The instrumentation cables used in the electrolysis device 1 are grounded, but fluctuations in the potential of the grounding grid may be transmitted as noise to the signals of the instrumentation cables. If noise is transmitted to the control signals, the reliability of the entire system will be reduced.

[0020] One possible solution to this problem is to combine the current circuits at the rectifier 20 end. However, when combining the current circuits at the rectifier 20 end, the required allowable current becomes twice as much as when the current circuits are not combined. In this case, a bus duct capable of handling the increased current is required, which increases costs.

[0021] In this embodiment, a balance cable 80, which is less expensive than a bus duct, is used to connect the negative electrode of the cell stack 10a and the negative electrode of the cell stack 10b.

[0022] Figure 2 is a diagram showing an electrolysis device according to some embodiments of the present disclosure. Description of components in Figure 2 that are common to Figure 1 will be omitted. As shown in Figure 2, the electrolysis device 1 includes an electrolytic cell 100, rectifiers 20a and 20b, and a control device 50. A plurality of rectifiers 20a and 20b are installed in parallel. The electrolytic cell 100 includes cell stacks 10a and 10b.

[0023] The negative electrode (-) of the cell stack 10a is connected to the negative electrode of the rectifier 20a, and the negative electrode of the cell stack 10b is connected to the negative electrode of the rectifier 20b.

[0024] A ground wire 30a is provided on the negative electrode side of the cell stack 10a. A ground wire 30b is provided on the negative electrode side of the cell stack 10b. The negative electrode of the cell stack 10a and the negative electrode of the cell stack 10b are connected by a balance cable 80. The balance cable 80 may be provided with an ammeter 90.

[0025] For example, if cell stack 10a has better performance than cell stack 10b, a larger current will flow through cell stack 10a than through cell stack 10b. At this time, a potential difference will occur between the negative electrode side of cell stack 10a and the negative electrode side of cell stack 10b, but the current will flow through balance cable 80.

[0026] The balanced cable 80 is selected to have a lower resistance than the resistance between the ground wires 30a and 30b, so that current flows through the balanced cable 80 rather than between the ground wires 30. This makes it difficult for a potential difference to occur between the ground wires 30a and 30b, thereby reducing the circulating current that flows from the ground wire 30a to the ground wire 30b.

[0027] For example, in this embodiment, two 325 sq (square) jumper cables are used as the balance cable 80. In this case, when the electrolysis device 1 is in a 100% operating state, a current of about 100 to 300 A flows through the balance cable 80.

[0028] The control device 50 is connected to the rectifier 20 and the ammeter 90 and controls the electrolysis device 1 .

[0029] 3 is a diagram illustrating an example of a hardware configuration of a control device according to some embodiments of the present disclosure. As shown in FIG. 3 , the control device (Controller) 50 is a computer system including, for example, a CPU (Central Processing Unit: Processor) 1100, a secondary storage device (ROM, Secondary storage: Memory) 1200, a main storage device (RAM, Main Memory) 1300, a hard disk drive (HDD) 1400 as a large-capacity storage device, and a communication unit 1500 for connecting to a network or the like. A solid-state drive (SSD) may also be used as the large-capacity storage device. These units are connected via a bus 1800.

[0030] The CPU 1100 controls the entire control device 50 using, for example, an operating system (OS) stored in a secondary storage device 1200 connected via a bus 1800, and executes various processes by executing various programs stored in the secondary storage device 1200. One or more CPUs 1100 may be provided, and they may cooperate with each other to realize processes.

[0031] The main memory device 1300 is composed of writable memory such as cache memory or RAM (Random Access Memory), and is used as a working area for reading programs executed by the CPU 1100 and writing data processed by the programs.

[0032] The secondary storage device 1200 is a non-transitory computer-readable storage medium. The secondary storage device 1200 is, for example, a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, or a semiconductor memory. Examples of the secondary storage device 1200 include a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), and a flash memory. The secondary storage device 1200 stores, for example, an OS for controlling the entire information processing device, such as Windows (registered trademark), iOS (registered trademark), or Android (registered trademark), a BIOS (Basic Input / Output System), various device drivers for operating peripheral devices, various application software, and various data and files. The secondary storage device 1200 stores programs for implementing various processes and various data required for implementing various processes. A plurality of secondary storage devices 1200 may be provided, and the above-mentioned programs and data may be stored separately in each secondary storage device 1200.

[0033] The control device 50 may include an input unit such as a keyboard or a mouse, a display unit such as a liquid crystal display device for displaying data, etc. The control device 50 may also include a notification unit such as a speaker that includes the display unit and outputs a lamp, sound, especially an alarm sound.

[0034] 4 is a diagram illustrating an example of the functions of a control device according to some embodiments of the present disclosure. As shown in FIG. 4, the control device 50 includes an acquisition unit 51, a determination unit 52, and an output unit 53.

[0035] A series of processes for realizing the functions of the control device 50 is stored in the form of a program in the secondary storage device 1200 (see FIG. 2), for example. The CPU (processor) 1100 (see FIG. 2) reads this program into the main storage device 1300 (see FIG. 2) and executes information processing and arithmetic processing to realize various functions. The program may be pre-installed in the secondary storage device 1200, provided in a state stored in another non-transitory computer-readable storage medium, or distributed via wired or wireless communication means. Examples of non-transitory computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0036] The acquisition unit 51 shown in FIG. 4 acquires the value of the current flowing through the balanced cable 80 measured by the ammeter 90 .

[0037] The determination unit 52 determines whether or not to set the output current value of each rectifier 20 based on the current value of the balance cable 80 acquired by the acquisition unit 51. The determination unit 52 also determines the deterioration state of the cell stack 10 of the electrolytic cell 100 based on the current value of the balance cable 80.

[0038] The output unit 53 outputs an output current value or a stop signal to each rectifier 20 based on the determination by the determination unit 52. The output unit 53 also outputs the deterioration state of the cell stack 10 to an output device.

[0039] 5 is a diagram showing a control flow of a control device according to some embodiments of the present disclosure. In step S101 of FIG. 5, the acquisition unit 51 of the control device 50 acquires the value of the current flowing through the balanced cable 80 from the ammeter 90. The direction of the current flow can also be determined from the acquired current value of the balanced cable 80. The acquisition unit 51 acquires the output current value of each rectifier 20.

[0040] Next, in step S102, the determination unit 52 determines whether the current value of the balanced cable 80 is greater than a first threshold value. If it is determined that the current value of the balanced cable 80 is greater than the first threshold value (YES in S102), the process proceeds to step S109. If it is determined that the current value of the balanced cable 80 is equal to or less than the first threshold value (NO in S102), the process proceeds to step S103. Here, the first threshold value is a current value set to protect the balanced cable 80, and is set to, for example, the allowable current value of the balanced cable 80.

[0041] If it is determined that the current value of the balance cable 80 is greater than the first threshold value, it can be said that a large amount of current is flowing through the balance cable 80 and the difference in current between the cell stack 10a and the cell stack 10b is large, and therefore the output unit 53 outputs a stop signal to each rectifier 20 (S109).

[0042] For example, if a short circuit occurs in the cell stack 10a in the electrolytic cell 100, the resistance component decreases significantly and the current flowing to the cell stack 10a increases sharply. At this time, a circulating current flows from the cell stack 10a side to the cell stack 10b side in the balance cable 80. If this circulating current exceeds a predetermined threshold, each rectifier 20 is stopped to protect the electrolysis device 1.

[0043] For example, assume that the current values ​​of the rectifiers 20a and 20b are each 6400 A. If the resistance of each cell stack 10 is the same, the current ratio between the cell stack 10a and the cell stack 10b is 1:1. That is, a current of 6400 A flows through each cell stack.

[0044] If cell stack 10a is short-circuited and its resistance value is halved, current will flow more easily through cell stack 10a, and the current ratio between cell stack 10a and cell stack 10b will be 2:1. That is, the current value of cell stack 10a will be approximately 8533 A, and the current value of cell stack 10b will be approximately 4267 A.

[0045] Therefore, a circulating current of approximately 2133 A flows through the balance cable 80 from the cell stack 10a side to the cell stack 10b side. If the first threshold is the allowable current value of the balance cable 80, and if the balance cable 80 is, for example, a two-strand CV cable of 325 sq., the first threshold is 1450 A. Because the current value of the balance cable 80 exceeds the first threshold, each rectifier 20 is stopped to protect the balance cable 80.

[0046] On the other hand, if it is determined that the current value of the balanced cable 80 is equal to or less than the first threshold value, the process proceeds to step S103, where the control device 50 calculates an unbalanced current value by adding up the output current value differences, which are the differences in the output current values ​​of the rectifiers 20. For example, if the current value of the rectifier 20a is 100 A and the current value of the rectifier 20b is 80 A, the unbalanced current value is 20.

[0047] Next, in step S104, the determination unit 52 determines whether the unbalance current value is greater than the second threshold value. If it is determined that the unbalance current value is greater than the second threshold value (YES in S104), the process proceeds to step S109. If it is determined that the unbalance current value is equal to or less than the second threshold value (NO in S104), the process proceeds to step S105. Here, the second threshold value is set to, for example, 10 to 30% of the rated current, or even 15% of the rated current.

[0048] Next, the determination unit 52 determines whether the current value of the balanced cable 80 is equal to or less than a third threshold value (step S105). If it is determined that the current value of the balanced cable 80 is equal to or less than the third threshold value (YES in S105), the process returns to step S101. If it is determined that the current value of the balanced cable 80 is greater than the third threshold value (NO in S105), the process proceeds to step S106. Here, the third threshold value is set to, for example, 0 or a value close to 0.

[0049] If it is determined that the current value of the balance cable 80 is greater than the third threshold value, the determination unit 52 determines the deterioration of the cell stack 10 based on the current value and the unbalanced current value of the balance cable 80 (S106).

[0050] For example, if the performance of cell stack 10a becomes lower than that of cell stack 10b due to degradation or the like, the resistance component increases and the current flowing to cell stack 10a decreases. At this time, a circulating current flows from cell stack 10b to cell stack 10a in balance cable 80. If this circulating current occurs, it can be determined that degradation of cell stack 10 has occurred.

[0051] For example, assume that the current values ​​of the rectifiers 20a and 20b are each 6400 A. If the resistance of each cell stack 10 is the same, the current ratio between the cell stack 10a and the cell stack 10b is 1:1. That is, a current of 6400 A flows through each cell stack.

[0052] If cell stack 10a deteriorates and its resistance value increases by 10%, it becomes difficult for current to flow through cell stack 10a, and the current ratio between cell stack 10a and cell stack 10b becomes 100:110. In other words, the current value of cell stack 10a is approximately 6095 A, and the current value of cell stack 10b is approximately 6705 A.

[0053] Therefore, a circulating current of approximately 305 A flows through the balance cable 80 from the cell stack 10b side to the cell stack 10a side. The ammeter 90 measures the current value of the balance cable 80, making it possible to calculate the current ratio of each cell stack 10. From the current ratio of each cell stack 10 and the predicted current value of each cell stack 10, it is possible to determine whether deterioration of the cell stack 10a is progressing. Similarly, if an unbalanced current value is occurring, particularly if the value is large, it can be determined that an imbalance has occurred in the current flowing between the cell stacks 10a and 10b, that is, deterioration of the cell stacks 10 is progressing.

[0054] The output unit 53 outputs the result of the deterioration determination of the cell stack 10 in step S106 (S110).

[0055] Next, in step S107, the control device 50 calculates the current ratio of each cell stack 10 from the current value of the balance cable 80 measured by the ammeter 90, calculates the current value of each cell stack 10 from the current ratio, and calculates the output current value of each rectifier 20 that matches the current value of each cell stack 10. In the above example, the output current value of the rectifier 20a corresponding to cell stack 10a is calculated to be 6095 A, and the output current value of the rectifier 20b corresponding to cell stack 10b is calculated to be 6705 A.

[0056] Next, in step S108, the control device 50 sets the output current value calculated in step S107 for each rectifier 20. Setting the output current value of the rectifier 20 in accordance with the state of the cell stack 10 makes it possible to reduce the circulating current flowing through the balance cables 80. Reducing the circulating current flowing through the balance cables 80 makes it possible to reduce the capacity of the balance cables 80, further reducing costs.

[0057] In most cases, multiple cells short out at once in the cell stack 10, but there are also cases where a single or a small number of cells short out. A short in a single or a small number of cells is the same as a deterioration of the cell stack 10, and therefore can be dealt with by carrying out the control of steps S105 to S108.

[0058] <Additional Notes> The electrolysis device, the control method for the electrolysis device, and the control program for the electrolysis device described in the above-described embodiments can be understood, for example, as follows.

[0059] The electrolysis device (1) of a first aspect of the present disclosure is an electrolysis device including a plurality of rectifiers (20) and an electrolytic cell (100) having a plurality of cell stacks (10) with a common positive electrode, wherein the positive electrode of each of the cell stacks is connected to the positive electrode of each of the rectifiers, the plurality of rectifiers being installed in parallel, and the negative electrode of each of the cell stacks is connected to the negative electrode of each of the rectifiers, respectively, and the electrolysis device is provided with a balance cable (80) connecting at least one negative electrode of the cell stack to at least one negative electrode of another of the cell stacks.

[0060] Since the circulating current in the electrolytic cell flows through the balanced cable, it reduces the circulating current that flows through the ground. It can also reduce circulating current that may occur through pipes, buildings, etc. other than the electrolytic cell's grounding wire. When current flows to the ground, there is a possibility that the potential of the grounding mesh will fluctuate, which may result in signal noise, but this can reduce signal noise caused by circulating current that flows through the ground. Furthermore, by using balanced cables, costs can be reduced by not using bus ducts, which are expensive materials.

[0061] The electrolysis apparatus of the second aspect of the present disclosure is the same as that of the first aspect, but further includes a current sensor (90) that measures the current in the balance cable and a control device (50) that controls the output current value of each of the rectifiers based on the current value measured by the current sensor. By using a balance cable, a current sensor (90) with a diameter corresponding to the cable diameter can be used, thereby reducing costs.

[0062] The output current value of the rectifier is set from the current value flowing through the balance cable attached to the negative side of the cell stack, so no special configuration is required, which helps keep costs down.

[0063] In the electrolytic device of the third aspect of the present disclosure, in the second aspect, the control device may determine the state of deterioration of the cell stack of the electrolytic cell based on at least one of the current value measured by the current sensor or the unbalanced current value obtained by adding up the differences in the output current values ​​of the rectifiers.

[0064] When a cell stack deteriorates, its resistance becomes higher than before deterioration, making it more difficult for current to flow. Therefore, while the current ratio between one cell stack and another would be the same if the deterioration state were the same, the current ratio on the deteriorated side decreases. When the current ratio on one side decreases, current flows toward the deteriorated side in the balance cable installed on the negative side of the cell stack. By measuring the current value of the balance cable, it is possible to determine which cell stack has deteriorated.

[0065] The electrolysis device of a fourth aspect of the present disclosure may be the third aspect, wherein the control device controls the output current value of each of the rectifiers based on a state of deterioration of each of the cell stacks of the electrolytic cell.

[0066] The output current value of each rectifier is controlled according to the state of deterioration of the cell stack, so that a current of a value appropriate for the deterioration flows, thereby reducing the current flowing through the balance cable.

[0067] In the electrolytic device of a fifth aspect of the present disclosure, in any one of the second to fourth aspects, the control device may stop the rectifier when the current value measured by the current sensor exceeds a predetermined threshold.

[0068] For example, if a cell stack shorts out, the current ratio on the shorted side increases significantly. When one current ratio increases, current flows from the shorted side of the balance cable installed on the negative side of the cell stack. By detecting that the current value of the balance cable exceeds a predetermined threshold, a short circuit in the cell stack can be detected, and the rectifier can be stopped to protect the electrolysis device.

[0069] A sixth aspect of the present disclosure provides a control method for an electrolytic device, the control method being executed by a computer for an electrolytic device having a plurality of rectifiers and a plurality of cell stacks with a common positive electrode, the positive electrode of each of the cell stacks being connected to a respective positive electrode of the rectifiers, the plurality of rectifiers being installed in parallel, the negative electrode of each of the cell stacks being connected to a respective negative electrode of the rectifiers, balance cables connecting the negative electrode of at least one of the cell stacks to at least one negative electrode of another of the cell stacks, and current sensors measuring current in the balance cables, the control method controlling the output current value of each of the rectifiers based on the current value measured by the current sensors.

[0070] A control program for an electrolysis device according to a seventh aspect of the present disclosure causes a computer to execute the control method according to the sixth aspect.

[0071] In the above-described embodiment, two cell stacks 10 and two rectifiers 20 have been described, but there may be a plurality of cell stacks 10 and rectifiers 20 other than two. The number of cell stacks 10 and the number of rectifiers 20 may differ.

[0072] REFERENCE SIGNS LIST 1 Electrolysis device 10, 10a, 10b Cell stack 20, 20a, 20b Rectifier 30 Ground wire 50 Control device 51 Acquisition unit 52 Determination unit 53 Output unit 80 Balance cable 90 Ammeter 100 Electrolytic cell 1100 CPU 1200 Secondary storage device 1300 Main storage device 1500 Communication unit 1800 Bus

Claims

1. An electrolysis device including an electrolytic cell having a plurality of rectifiers and a plurality of cell stacks with a common positive electrode, wherein the positive electrode of each of the cell stacks is connected to the positive electrode of each of the rectifiers, a plurality of which are installed in parallel, and the negative electrode of each of the cell stacks is connected to the negative electrode of each of the rectifiers, and the electrolysis device is provided with a balance cable connecting the negative electrode of at least one of the cell stacks to the negative electrode of at least one of the other cell stacks.

2. The electrolysis device according to claim 1, further comprising: a current sensor for measuring the current in the balance cable; and a control device for controlling the output current value of each of the rectifiers based on the current value measured by the current sensor.

3. The electrolysis device according to claim 2, wherein the control device determines the state of deterioration of the cell stack of each of the electrolytic cells based on at least one of the current values ​​measured by the current sensors and the unbalanced current value obtained by adding up the differences in the output current values ​​of each of the rectifiers.

4. The electrolysis device according to claim 3, wherein the control device controls the output current value of each of the rectifiers based on the state of deterioration of each of the cell stacks of the electrolysis cell.

5. The electrolysis device according to claim 2, wherein the control device stops the rectifier when the current value measured by the current sensor exceeds a predetermined threshold value.

6. A control method executed by a computer for an electrolysis device having: a plurality of rectifiers; a plurality of cell stacks with a common positive electrode, the positive electrode of each of the cell stacks being connected to the positive electrode of each of the rectifiers installed in parallel, and the negative electrode of each of the cell stacks being connected to the negative electrode of each of the rectifiers; balance cables connecting the negative electrode of at least one of the cell stacks to the negative electrode of at least one of the other cell stacks; and a current sensor measuring the current of the balance cables, the control method for an electrolysis device comprising: controlling the output current value of each of the rectifiers based on the current value measured by the current sensor.

7. A control program for an electrolytic device for causing a computer to execute the control method for an electrolytic device according to claim 6.

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