Hydrogen production system

Abstract

To provide a hydrogen production system capable of preventing non-green hydrogen from being mixed with green hydrogen in a tank while avoiding the stop of an electrolytic cell even when generated power is insufficient and a storage battery is not charged.SOLUTION: The hydrogen production system includes a power conditioner configured to convert DC power generated by a solar panel into AC power, a storage battery device, a hydrogen production device including a rectifier configured to rectify the AC power to obtain DC power and an electrolyzer configured to generate hydrogen by electrolysis using the DC power from the rectifier, a green hydrogen tank, a non-green hydrogen tank, and a control device. The control device is configured to, when a total of supply power from the power conditioner and the storage battery device to the rectifier is smaller than first reference power that can avoid deterioration of the electrolytic cell, further supply system power to the rectifier to control the supply power to the rectifier to the first reference power, and store hydrogen generated in the electrolytic cell in the non-green hydrogen tank.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a hydrogen production system, and in particular to one that produces hydrogen (hereinafter referred to as "green hydrogen") by electrolysis using electricity generated by solar panels. [Background technology]

[0002] This type of hydrogen production system is disclosed, for example, in Patent Documents 1 and 2 listed below. In the system disclosed in Patent Document 1, electricity generated by solar panels is supplied to an electrolyzer (water electrolysis section), and green hydrogen produced by electrolysis is stored in a tank. In addition, surplus electricity not consumed by the electrolyzer is stored in a storage battery (secondary battery), and when the electricity generated by the solar panels is insufficient (including when electricity cannot be generated), electricity discharged from the storage battery is supplied to the electrolyzer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-57388 [Patent Document 2] Japanese Patent Application Publication No. 2019-170097 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the power generated by the solar panels is insufficient and the storage battery is not charged (i.e., the storage battery cannot discharge), the power supplied to the electrolyzer will be reduced. If the power supplied to the electrolyzer is low, there is a risk that the electrolyzer's lifespan will be shortened. In order to avoid shortening the electrolyzer's lifespan, the electrolyzer must be temporarily shut down. Since it takes several hours or more to start up an electrolyzer that has been shut down, part of the sunshine hours overlap with the start-up of the electrolyzer, resulting in a substantial shortening of the hydrogen production time. Here, it is possible to supply grid power to the electrolyzer, but in this case, non-green hydrogen produced using grid power will be mixed with the green hydrogen in the tank, making it impossible to sell the hydrogen stored in the tank as green hydrogen.

[0005] Therefore, the present disclosure aims to provide a hydrogen production system that can prevent non-green hydrogen from being mixed with green hydrogen in the tank while avoiding the electrolyzer from shutting down even when the solar panels are not generating enough power and the storage battery is not charged. [Means for solving the problem]

[0006] A first aspect of the present disclosure relates to a hydrogen production system. The hydrogen production system includes a power conditioner that converts DC power generated by solar panels into AC power and outputs it, a storage battery device having a storage battery and a power conversion device, a hydrogen production device having a rectifier that rectifies AC power to obtain DC power and an electrolyzer that produces hydrogen by electrolysis using the DC power supplied from the rectifier, a green hydrogen tank that stores green hydrogen produced in the electrolyzer, a non-green hydrogen tank that stores non-green hydrogen produced in the electrolyzer, and a control device. The power conversion device of the storage battery device can convert AC power output from the power conditioner into DC power to charge the storage battery, and can convert DC power charged in the storage battery into AC power to discharge it. The control device is configured to supply grid power to the rectifier and control the power supplied to the rectifier to the first reference power when the total power supplied from the power conditioner and the storage battery device to the rectifier is smaller than a first reference power that can avoid deterioration of the electrolyzer, and to store hydrogen produced in the electrolyzer in a tank for non-green hydrogen.

[0007] The second aspect has the following characteristics in addition to those of the first aspect: When the power supplied from the power conditioner to the rectifier is greater than a second reference power at which the hydrogen production efficiency of the hydrogen production device is maximized, the control device is configured to control the power supplied from the power conditioner to the rectifier to the second reference power, charge the storage battery with the surplus power, and store hydrogen produced in the electrolyzer in the green hydrogen tank.

[0008] The third aspect has the following feature in addition to the second aspect: when the sum of the power supplied from the power conditioner and the storage battery device to the rectifier is greater than a first reference power, the control device is configured to control the power supplied to the rectifier to be equal to or greater than the first reference power and equal to or less than a second reference power, and to store hydrogen produced in the electrolyzer in the green hydrogen tank.

[0009] A fourth aspect has the same features as the third aspect, but further includes the following: the control device is configured to change the power supplied to the rectifier within a range of a first reference power or more and a second reference power or less, according to the amount of remaining power in the storage battery.

[0010] A fifth aspect has the following feature in addition to any one of the first to fourth aspects: The hydrogen production system includes a first valve installed in a first pipe that guides hydrogen produced in the electrolyzer to a green hydrogen tank, and a second valve installed in a second pipe that guides hydrogen produced in the electrolyzer to a non-green hydrogen tank. The control device is configured to control the opening and closing of the first valve and the second valve to switch the storage destination of the hydrogen produced in the electrolyzer between the green hydrogen tank and the non-green hydrogen tank. [Effects of the Invention]

[0011] According to the present disclosure, when the total power supplied to the rectifier from the power conditioner and the storage battery device is less than a first reference power, grid power is supplied to the rectifier and the power supplied to the rectifier is controlled to the first reference power. Therefore, even if the power generated by the solar panels is insufficient and the storage battery is not charged, there is no need to stop the electrolyzer to avoid deterioration of the electrolyzer. Therefore, when the power generated by the solar panels is restored, there is no need to start up the electrolyzer, and green hydrogen can be produced immediately. Moreover, because non-green hydrogen produced using grid power is stored in a non-green hydrogen tank, non-green hydrogen is not mixed with the green hydrogen stored in the green hydrogen tank. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a configuration example of a hydrogen production system according to an embodiment. [Figure 2] 1 is a graph showing the relationship between the power input to the hydrogen production device and the hydrogen generation efficiency. [Figure 3] 3 is a flowchart illustrating the flow of hydrogen production by the hydrogen production system. [Figure 4] 3 is a flowchart illustrating a hydrogen production process performed by the hydrogen production system. [Figure 5] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control device of the hydrogen production system. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a hydrogen production system according to an embodiment will be described with reference to the drawings, taking as an example a case where the system is applied to a factory. Common or corresponding elements in the various drawings will be assigned the same reference numerals, and descriptions thereof will be simplified or omitted.

[0014] Fig. 1 is a schematic diagram showing an example of the configuration of a hydrogen production system according to an embodiment. As shown in Fig. 1, the hydrogen production system 1 includes a solar power generation system 2, a hydrogen production system 3, a storage battery system 4, a grid power receiving facility 5, a factory load 6, and a control device 7. The solar power generation system 2, the hydrogen production system 3, the storage battery system 4, the grid power receiving facility 5, and the factory load 6 are connected to an in-house AC system 9 so that power can be exchanged. Unless otherwise specified, power refers to active power.

[0015] The solar power generation system 2 includes a solar panel 21 and a power conditioner (hereinafter also referred to as "PCS") 22. The solar panel 21 generates DC power from sunlight. The solar panel 21 may be, for example, a silicon-based, compound-based, organic-based, or quantum dot-based solar panel. These are well known, and therefore will not be described in detail here. The PCS 22 may be, for example, a self-commutated converter. The PCS 22 converts DC power output from the solar panel 21 into AC power. The output power Ppv output from the PCS 22 is supplied to at least one selected from the rectifier 31 of the hydrogen production system 3, the storage battery system 4, and the factory load 6. Unless otherwise specified, the PCS 22 performs operation control, such as maximum output power control, during operation to maximize the output power Ppv output from the solar panel 21 to the on-site AC grid 9.

[0016] The hydrogen production device 3 includes a rectifier 31 and an electrolytic cell 32. The rectifier 31 may be supplied with the output power Ppv output from the PCS 22, the AC-side discharge power discharged from the storage battery device 4, or AC power (grid power) received from a commercial power system (not shown) supplied by a power company or the like via a grid power receiving facility 5. The rectifier 31 may be configured, for example, as a self-commutated converter, a thyristor rectifier, or a combination of these with a chopper. The rectifier 31 converts the supplied AC power into desired DC power and supplies it to the electrolytic cell 32. Although not shown, the electrolytic cell 32 may be a known cell having a pair of electrodes and a solid polymer membrane arranged therein, and therefore a detailed description thereof will be omitted here. The structure of the electrolytic cell 32 is not particularly limited as long as it can generate hydrogen by electrolyzing water using DC power. The hydrogen produced in the electrolytic cell 32 is introduced into a pipe 33. The pipe 33 branches into two pipes 33a and 33b downstream. The first pipe 33a is connected to a green hydrogen tank 34 that stores green hydrogen, and the second pipe 33b is connected to a non-green hydrogen tank 35 that stores non-green hydrogen (gray hydrogen produced using grid power). A first valve 36a is provided in the first pipe 33a, and a second valve 36b is provided in the second pipe 33b. The open / close states of these valves 36a and 36b are switched depending on the power supplied to the rectifier 31. This switches the storage destination of the hydrogen generated in the electrolyzer 32 between the tank 34 and the tank 35. Note that a pressurizing pump may be provided between the pipe 33, the first valve 36a, and the green hydrogen tank 34, or between the second valve 33b and the non-green hydrogen tank 35.

[0017] The storage battery equipment 4 includes, for example, a secondary battery body 41 capable of repeatedly charging and discharging, and a power conversion device 42 capable of converting AC power supplied via the station AC system 9 into DC power to charge the secondary battery body 41, discharging the DC power charged in the secondary battery body 41, converting the discharged DC power into AC power, and supplying the converted AC power to the station AC system 9. The secondary battery body 41 is an example of a storage battery. An example of the secondary battery body 41 is a lithium-ion secondary battery. The secondary battery body 41 and the power conversion device 42 are well known, and therefore detailed description thereof will be omitted here. The power conversion device 42 controls the charging / discharging of the secondary battery body 41 and monitors the remaining energy SOC.

[0018] The system power receiving equipment 5 is equipment that receives AC power from a commercial power system (not shown) supplied by an electric power company, etc. The factory load 6 is equipment that consumes power in the factory.

[0019] The control device 7 is connected to a host computer 8 via a network. The host computer 8 performs overall control of the operation of the factory. The operation of the factory includes the production of green hydrogen by the hydrogen production device 3. The control device 7 receives hydrogen production commands from the host computer 8 and performs overall control of the hydrogen production system 1 by controlling the PCS 22, rectifier 31, electrolyzer 32, first valve 36a, second valve 36b, storage battery device 4, grid power receiving equipment 5, etc.

[0020] The control device 7 receives a signal corresponding to the output power Ppv of the PCS 22 from the PCS 22. The control device 7 outputs an operation / stop signal to the PCS 22, as well as a maximum output power control command, a power control command, and a power control command value during power control. During power control, the PCS 22 controls the output power Ppv to follow the power control signal. The control device 7 acquires electrolytic cell information, such as the concentration and temperature of the electrolytic solution, from the electrolytic cell 32. The control device 7 issues an input power command, an output power command, an output current command, or an output voltage command to the rectifier 31. Once the concentration and temperature of the electrolytic solution in the electrolytic cell 32 are determined, the impedance is uniquely determined, even if it is current-dependent. Furthermore, once the output current is determined, the loss of the rectifier 31 is uniquely determined. Therefore, the command issued by the control device 7 to the rectifier 31 may be an input power command, an output power command, an output current command, or an output voltage command. The rectifier 31 operates to follow the command issued by the control device 7.

[0021] The control device 7 acquires information about the SOC and temperature of the secondary battery 41 via the power converter 42. The control device 7 provides the power converter 42 with an AC power command on the AC side, a DC power command on the secondary battery 41 side, a DC current command, or a DC voltage command. Once the SOC and temperature of the secondary battery 41 are determined, its impedance is uniquely determined even if it depends on the DC current. Furthermore, once the DC current is determined, the loss of the power converter 42 is uniquely determined. Therefore, the command provided by the control device 7 to the power converter 42 may be an AC power command, a DC power command, a DC current command, or a DC voltage command. The power converter 42 operates to follow the command provided by the control device 7. The power command and current command have polarity, and the charge / discharge of the secondary battery 41 is determined by the polarity. Furthermore, in the case of a DC voltage command, the charge / discharge of the secondary battery 41 is determined by the magnitude relationship between the release voltage value of the secondary battery 41 and the DC voltage command value.

[0022] The control device 7 issues opening and closing commands to the valves 33a and 33b, respectively. The valves 33a and 33b perform opening and closing operations based on the opening and closing commands issued by the control device 7. Furthermore, if the pressurizing pump is provided, the control device 7 issues a necessary operation command to the pressurizing pump.

[0023] Next, the basic operation of the hydrogen production system 1 will be described. When power is generated by the solar panel 21, the generated DC power is converted to AC power by the PCS 22. The output power Ppv output from the PCS 22 is supplied to the rectifier 31 via the local AC system 9, and the output power Ppv is monitored by the control device 7. The control device 7 outputs command values, such as a power command value, to the rectifier 31 to control it so that AC power equivalent to the output power Ppv supplied from the PCS 22 to the local AC system 9 is used as the AC input current for the rectifier 31, and the rectified DC power is supplied to the electrolyzer 32. The electrolyzer 32 generates green hydrogen by electrolysis using the DC power output from the rectifier 31. The control device 7 controls the second valve 36b to close and the first valve 36a to open, and the generated green hydrogen is stored in the green hydrogen tank 34.

[0024] Here, the relationship between the power supplied to the rectifier 31 of the hydrogen production device 3 and the hydrogen generation efficiency is shown in FIG. 2. FIG. 2 is a graph showing the relationship between the power supplied to the hydrogen production device 3 and the hydrogen generation efficiency. As shown in FIG. 2, as the power supplied increases, the hydrogen generation efficiency also increases until the power supply reaches the reference power P2. At the reference power P2, the hydrogen generation efficiency reaches a maximum value Mmax. When the power supply exceeds the reference power P2, the hydrogen generation efficiency decreases as the power supply increases. Therefore, when the power supply exceeds the reference power P2, the excess power is surplus, so it is preferable to supply the excess power to the storage battery device 4 for charging. Furthermore, when the storage battery device 4 is fully charged, it is preferable to supply the excess power to the factory load 6. Note that the horizontal axis in FIG. 2 represents the power supplied to the hydrogen production device 3, and the power supplied to the electrolyzer 32 is the value obtained by subtracting the conversion loss of the rectifier 31 from the value on the horizontal axis.

[0025] The conversion loss of the rectifier 31 can be calculated in advance as a function of the output current and output voltage of the rectifier 31. Therefore, by calculating the input DC power of the electrolytic cell 32 and the hydrogen generation efficiency through tests, simulations, or the like, the relationship shown in FIG. 2 can be easily calculated. That is, in the relationship between the input DC power of the electrolytic cell 32 and the hydrogen generation efficiency, the relationship shown in FIG. 2 can be obtained by adding the loss of the rectifier 31 to the input DC power of the electrolytic cell 32. The relationship shown in FIG. 2 may vary depending on the concentration and temperature of the electrolyte in the electrolytic cell 32, but this variation can be calculated in advance through tests, simulations, or the like. By calculating in advance the patterns shown in FIG. 2 for at least nine combinations of the upper, middle, and lower limits of the electrolyte concentration and the upper, middle, and lower limits of the electrolyte temperature in the actual operating range, the control device 7 may interpolate the values ​​of the patterns calculated in advance for other combinations of the electrolyte concentration and temperature to calculate the relationship shown in FIG. 2 for the required combination of the electrolyte concentration and temperature.

[0026] However, there may be cases where the power generated by the solar panel 21 is insufficient due to sunset, weather, etc. In this case, if the power supplied to the rectifier 31 becomes smaller than the reference power P1 shown in Fig. 2, this may result in a shortened life of the electrolytic cell 32.

[0027] Therefore, when the storage battery equipment 4 is dischargeable, the power discharged from the storage battery equipment 4 is supplied to the rectifier 31, and the power supply P0 from the rectifier 31 to the electrolytic cell 32 is controlled to be within a range of a reference power P1 or more and a reference power P2 or less. The supply power P0 may be a fixed value, or may be varied in steps or continuously according to the remaining energy (state of charge) SOC of the storage battery equipment 4. By controlling the supply power P0 to be larger as the remaining energy SOC increases, hydrogen can be generated with high hydrogen generation efficiency. Furthermore, by controlling the supply power P0 to be smaller as the remaining energy SOC decreases, green hydrogen can be generated while minimizing the amount of discharge from the storage battery equipment 4, and further, shortening the lifespan of the electrolytic cell 32 can be reliably prevented. The generated green hydrogen is stored in the green hydrogen tank 34.

[0028] Furthermore, if the storage battery equipment 4 is not charged, i.e., if the storage battery equipment 4 cannot be discharged, green hydrogen cannot be produced. In this case, the power supplied from the rectifier 31 to the electrolyzer 32 is controlled to the reference power P1 by adding the grid power Pco received by the grid power receiving equipment 5 to the output power Ppv of the PCS 22. That is, the shortfall obtained by subtracting the output power Ppv from the reference power P1 is compensated for by the grid power Pco. As a result, green hydrogen cannot be produced, but since the reference power P1 is supplied to the electrolyzer 32, stopping of the electrolyzer 32 can be avoided. In this case, the control device 7 controls the first valve 36a to close and the second valve 36b to open, so that non-green hydrogen (gray hydrogen) produced by the hydrogen production device 3 is stored in the non-green hydrogen tank 35. This prevents non-green hydrogen from mixing with the green hydrogen stored in the green hydrogen tank 34.

[0029] 3 and 4 are flowcharts for explaining the process of hydrogen production by the hydrogen production system 1. In step S1 of FIG. 3, the control device 7 determines whether or not a hydrogen production command has been received from the host computer 8. If it is determined that a hydrogen production command has not been received (NO), the process proceeds to step S2. In step S2, the control device 7 determines whether or not the PCS 22 is operable. For example, if the DC voltage of the solar panel 21 is equal to or greater than a predetermined value, the control device 7 determines that the PCS 22 is operable. If it is determined that the PCS 22 is inoperable (NO), the control device 7 temporarily ends this routine. On the other hand, if it is determined that the PCS 22 is operable (YES), the process proceeds to step S3.

[0030] In step S3, it is determined whether the storage battery device 4 is chargeable. The control device 7 obtains information on the SOC of the secondary battery body 41 from the power storage value device 4, and can determine that the storage battery device 4 is chargeable if the SOC is equal to or lower than a predetermined value. If it is determined that the storage battery device 4 is chargeable (YES), the process proceeds to step S4. In step S4, the control device 7 supplies the output power Ppv output from the PCS 22 to the power conversion device 42 to charge the secondary battery body 41. Thereafter, the process temporarily ends. On the other hand, if it is determined in step S3 that the SOC exceeds the predetermined value, that is, if it is determined that the secondary battery body 41 is fully charged and the storage battery device 4 cannot be further charged (NO), the process proceeds to step S5. In step S5, the control device 7 supplies the output power Ppv output from the PCS 22 to the factory load 6. Specifically, the secondary battery body 41 is placed in a state where it is neither charged nor discharged, and the rectifier 31 stops converting AC power to DC power. If reverse power flow to the commercial power system is not permitted, the PCS 22 may be configured to perform AC power output control instead of maximum output power control so that the output power of the PCS 22 does not exceed the active AC power consumed by the factory load 6. After that, this routine is temporarily terminated.

[0031] If it is determined in step S1 above that a hydrogen production command has been received (YES), the process proceeds to step S6. In step S6, the control device 7 determines whether the output power Ppv output from the PCS 22 is greater than the reference power P2. The reference power P2 is the supply power at which the hydrogen generation efficiency of the hydrogen production device 3 reaches its maximum value Mmax (see FIG. 2). In step S6, it is determined whether the output power Ppv from the PCS 22, i.e., the power generated by the solar panel 21, is in excess of the reference power P2. If it is determined that the output power Ppv from the PCS 22 is greater than the reference power P2 (YES), the process proceeds to step S7. In step S7, the control device 7 controls the rectifier 31 of the hydrogen production device 3, providing an input power command value to the rectifier 31 so that the input power of the hydrogen production device 3 becomes the reference power P2, thereby producing green hydrogen, and controlling the charging power command so that the surplus power exceeding the reference power P2 is supplied to the storage battery device 4, thereby charging the secondary battery main body 41. Then, proceed to step S8.

[0032] In step S8, green hydrogen is produced by the hydrogen production device 3, so the control device 7 outputs a valve operation command to open the first valve 36a and close the second valve 36b. As a result, the first valve 36a is opened and the second valve 36b is closed, and green hydrogen is stored in the green hydrogen tank 34. After that, this routine is temporarily terminated.

[0033] If the control device 7 determines in step S6 above that the output power Ppv is equal to or less than the reference power P2 (NO), the process proceeds to step S9. In step S9, the control device 7 determines whether the output power Ppv is greater than the reference power P1. The reference power P1 is smaller than the reference power P2 and is a supply power that can prevent deterioration of the electrolyzer 32 (see FIG. 2). If the control device 7 determines that the output power Ppv is greater than the reference power P1 (YES), the process proceeds to step S10. In step S10, the control device 7 provides a power command value to the rectifier 31 so that the input power and output power Ppv of the hydrogen production device 3 are equal, causing the hydrogen production device 3 to generate hydrogen with power equal to the output power Ppv. In this case, the hydrogen produced by the hydrogen production device 3 is also green hydrogen, so the process proceeds to step S8 above, where the green hydrogen is stored in the green hydrogen tank 34. On the other hand, if the control device 7 determines in step S9 that the output power Ppv is equal to or less than the reference power P1 (NO), the process proceeds to step S11.

[0034] In step S11, the control device 7 determines whether the storage battery equipment 4 is dischargeable, i.e., whether the storage battery equipment 4 is charged at a predetermined level of SOC. If it is determined that the storage battery equipment 4 is charged at a predetermined level of SOC and is dischargeable (YES), the process proceeds to step S12. In step S12, the control device 7 calculates the discharge power Ped from the storage battery equipment 4. The discharge power Ped is found by subtracting the output power Ppv of the PCS 22 from the power P0. That is, the discharge power Ped is calculated so that the sum of the output power Ppv and the discharge power Ped equals the power P0. Then, the process proceeds to step S13. In step S13, the control device 7 outputs the discharge power Ped to the power conversion device 42 as an AC power command, and further outputs the power P0 to the rectifier 31 as an input power command. As a result, the hydrogen production device 3 produces hydrogen in a state where the input power value equals the power P0. In this case, the hydrogen produced by the hydrogen production device 3 is green hydrogen, so the process proceeds to step S8, where the hydrogen is stored in the green hydrogen tank 34. Here, the power P0 is within a range of P1 to P2, as shown in FIG. 2, and may be a fixed value, or may be varied in steps or continuously depending on the remaining energy (state of charge) SOC of the battery storage device 4. The power P0 can be varied so that the larger the remaining energy SOC, the larger the power P0, and vice versa. Alternatively, the control device 7 may obtain weather, weather forecast, date and time information, etc. from the host computer 8, predict the future output power Ppv from the solar power generation device 2, and determine the power P0 that will produce the largest amount of green hydrogen, taking into account the remaining energy SOC.

[0035] On the other hand, if it is determined in step S11 that the storage battery equipment 4 is not capable of discharging (NO), that is, if it is determined that the storage battery equipment 4 is not being charged, the process proceeds to step S14. In step S14, the control device 7 outputs a green hydrogen production disable signal to the host computer 8. Then, the process proceeds to step S15. In step S15, the control device 7 sets the input current command of the rectifier 31 to the reference power P1. The reference power P1 is obtained by adding the output power Ppv of the PCS 22 and the grid power Pco. That is, the shortfall obtained by subtracting the output power Ppv from the reference power P1 is compensated for by the grid power Pco. As a result, the reference power P1 is supplied to the electrolytic cell 32, and therefore, it is possible to avoid stopping the electrolytic cell 32. Then, the process proceeds to step S16. In step S16, since the hydrogen produced by the hydrogen production device 3 is non-green hydrogen (gray hydrogen), the control device 7 controls the opening and closing commands to the valves 33a and 33b, respectively, to close the first valve 36a and open the second valve 36b. As a result, non-green hydrogen is stored in the non-green hydrogen tank 35. After that, this routine is temporarily terminated.

[0036] Thereafter, when the power generated by the solar panel 21 increases and the output power Ppv of the PCS 22 becomes greater than the reference power P2 (or P1), the determination in step S6 or step S9 of the above routine is YES, and the production of green hydrogen is resumed without supplying power from the grid to the hydrogen production device 3. At this time, the electrolyzer 32 is not stopped, so there is no need to start up the electrolyzer 32 over several hours as in the conventional case, and green hydrogen can be produced by the electrolyzer 32 immediately.

[0037] The specific structure of the control device 7 is not limited, and may be as follows, for example. FIG. 5 is a diagram showing an example of the hardware configuration of the control device 7. Each function of the control device 7 can be realized by the processing circuit shown in FIG. 5. This processing circuit may be dedicated hardware 71. This processing circuit may include a processor 72 and a memory 73. This processing circuit may be partially formed as dedicated hardware 71 and further include a processor 72 and a memory 73. In the example of FIG. 5, a portion of the processing circuit is formed as dedicated hardware 71, and the processing circuit also includes a processor 72 and a memory 73. At least a portion of the processing circuit may be at least one dedicated hardware 71. In this case, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. The processing circuit may include at least one processor 72 and at least one memory 73. In this case, each function of the control device 7 is realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 73. The processor 72 realizes each function of the control device 7 by reading and executing programs stored in the memory 73. The processor 72 is also called a CPU (Central Processing Unit), central processing unit, processing device, arithmetic unit, microprocessor, microcomputer, or DSP. The memory 73 corresponds to, for example, non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, or EEPROM. In this way, the processing circuit can realize each function of the control device 7 by hardware, software, firmware, or a combination of these.

[0038] As described above, in this embodiment, when the total power supplied from the PCS 22 and the storage battery equipment 4 to the rectifier 31 is smaller than the reference power P1, the grid power received by the grid power receiving equipment 5 is supplied to the rectifier 31, and the power supplied to the rectifier 31 is controlled to the reference power P1. Therefore, even when the power generated by the solar panel 21 is insufficient and the storage battery equipment 4 is not charged (i.e., the storage battery equipment 4 cannot discharge), there is no need to stop the electrolyzer 32 to avoid deterioration of the electrolyzer 32. Therefore, when the power generated by the solar panel 21 is restored, it is not necessary to start up the electrolyzer 32 over several hours, and green hydrogen can be produced by the electrolyzer 32 immediately. Moreover, because the non-green hydrogen produced using grid power is stored in the non-green hydrogen tank 35, the non-green hydrogen is not mixed with the green hydrogen stored in the green hydrogen tank 34.

[0039] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments and can be implemented in various modifications without departing from the spirit of the present disclosure. In the above embodiments, the application to a factory has been described as an example, but the present disclosure can also be applied to a business establishment. In this case, the factory load 6 is the load within the business establishment. [Explanation of symbols]

[0040] 1...hydrogen production system, 2...solar power generation equipment, 21...solar panel, 22...power conditioner (PCS), 3...hydrogen production equipment, 31...rectifier, 32...electrolyzer, 33...piping, 33a...first piping, 33b...second piping, 34...tank for green hydrogen, 35...tank for non-green hydrogen, 36a...first valve, 36b...second valve, 4...storage battery equipment, 41...secondary battery body (storage battery), 42...power conversion equipment, 5...system power receiving equipment, 6...factory load, 7...control device, processing circuit, 71...dedicated hardware, 72...processor, 73...memory, 8...host computer, 9...in-plant AC system, P1...reference power (first reference power), P2...reference power (second reference power)

Claims

1. A power conditioner that converts DC power generated by solar panels into AC power and outputs it; A storage battery device having a storage battery and a power conversion device, wherein the power conversion device is capable of converting AC power output from the power conditioner into DC power to charge the storage battery, and is capable of converting the DC power charged in the storage battery into AC power to discharge the DC power; a hydrogen production device having a rectifier that rectifies AC power to obtain DC power, and an electrolyzer that generates hydrogen by electrolysis using the DC power supplied from the rectifier; a green hydrogen tank for storing the green hydrogen produced in the electrolyzer; a non-green hydrogen tank for storing the non-green hydrogen produced in the electrolyzer; a control device; Equipped with The control device is configured to, when the total power supplied from the power conditioner and the storage battery device to the rectifier is smaller than a first reference power that can avoid deterioration of the electrolytic cell, further supply grid power to the rectifier to control the power supplied to the rectifier to the first reference power, and to store hydrogen produced in the electrolytic cell in the non-green hydrogen tank.

2. 2. The hydrogen production system according to claim 1, The control device is configured to control the power supplied from the power conditioner to the rectifier to the second reference power when the power supplied from the power conditioner to the rectifier is greater than a second reference power at which the hydrogen generation efficiency of the hydrogen production device is maximized, charge the storage battery with surplus power, and store hydrogen produced in the electrolyzer in the green hydrogen tank.

3. 3. The hydrogen production system according to claim 2, The control device is configured to control the power supplied to the rectifier to be greater than the first reference power and less than the second reference power when the total power supplied from the power conditioner and the storage battery device to the rectifier is greater than the first reference power, and to store hydrogen produced in the electrolyzer in the green hydrogen tank.

4. The hydrogen production system according to claim 3, The control device is configured to change the power supplied to the rectifier within a range of the first reference power or more and the second reference power or less depending on the amount of remaining power in the storage battery.

5. The hydrogen production system according to any one of claims 1 to 4, a first valve disposed in a first pipe that guides hydrogen generated in the electrolyzer to the green hydrogen tank; a second valve installed in a second pipe that guides the hydrogen produced in the electrolyzer to the non-green hydrogen tank; The control device is a hydrogen production system configured to switch the storage destination of hydrogen produced in the electrolyzer between the green hydrogen tank and the non-green hydrogen tank by controlling the opening and closing of the first valve and the second valve.

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