Power generation system

Abstract

The present invention provides a power generation system that can stably produce hydrogen using renewable energy and reduce the battery capacity required for stable hydrogen production. [Solution] The power generation system 10 sets the power generated by the renewable energy power generation equipment 30 as a target power to be supplied to the r-SOC system 14, which is power obtained by smoothing the power generated by the power generation equipment 30. If the power generated by the power generation equipment 30 is greater than the target power, the system supplies power equal to the target power from the power generated by the power generation equipment 30 to the r-SOC system 14 and charges the battery 15 with any surplus power. If the power generated by the power generation equipment 30 is less than the target power, the system supplies all the power generated by the power generation equipment 30 to the r-SOC system 14 and supplies the battery 15 with any power deficit relative to the target power to the r-SOC system 14.

Description

[Technical Field]

[0001] This disclosure relates to a power generation system. [Background technology]

[0002] As disclosed in Patent Documents 1 to 3, systems for producing hydrogen using electricity generated from renewable energy sources have been proposed. Specifically, Patent Document 1 discloses a system comprising a power generation means for generating and storing electricity from renewable energy sources, and a water electrolysis means for producing hydrogen by electrolyzing water using the electricity obtained from the power generation means. Patent Document 2 discloses a system comprising a renewable energy power generation facility and a power utilization device, which calculates the power consumption of the power utilization device, supplies the calculated power consumption to the power utilization device, and supplies the surplus to an external power grid. Patent Document 3 discloses a system comprising a water splitting cell that produces hydrogen by electrolyzing water using surplus electricity supplied from a renewable energy power generation facility, and a SOEC that produces hydrogen by electrolyzing steam, which supplies stable power from the surplus electricity to the SOEC and unstable power to the water electrolysis cell.

[0003] However, there is a challenge in that it is difficult to stably produce hydrogen because the amount of electricity generated from renewable energy is unstable (it fluctuates greatly over time). In the system disclosed in Patent Document 1, the capacity of the storage battery is set to be within the range of 106-126% of the rated power generation of renewable energy, the power required for electrolysis of water is set to be within the range of 5-30% of the rated power generation, and if the power generated falls below the required power, the deficit is supplemented by the storage battery. With such a configuration, hydrogen production can be continued even if the power generated decreases. However, with such a configuration, a large-capacity storage battery is required, leading to a larger system and increased costs.

[0004] According to the system disclosed in Patent Document 2, while power can be stably supplied to the external power grid, the power supplied to the water electrolysis device becomes unstable. Therefore, it is difficult to stably produce hydrogen using the system disclosed in Patent Document 2.

[0005] According to the system disclosed in Patent Document 3, by supplying stable power from the surplus electricity to the SOEC, fluctuations in the load on the SOEC are prevented, while unstable power is supplied to a water electrolysis cell that is highly resistant to load fluctuations, thereby enabling hydrogen production in the water electrolysis cell. However, the hydrogen production efficiency of the water electrolysis cell is lower than that of the SOEC. Therefore, compared to a configuration in which all surplus electricity is supplied to the SOEC to produce hydrogen, the hydrogen production efficiency is lower. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-69688 [Patent Document 2] Patent No. 6297522 [Patent Document 3] Japanese Patent Publication No. 2019-173082 [Overview of the Initiative]

[0007] This disclosure aims to solve the problems described above. Specifically, one of the objectives of this disclosure is to provide a power generation system that can stably produce hydrogen using renewable energy and that can reduce the capacity of the battery required for stable hydrogen production (i.e., it can miniaturize the battery in the system).

[0008] To solve the above problems, the power generation system described in this disclosure is A reversible SOC system including an electrochemical cell stack that can operate in operating modes including a first mode capable of generating hydrogen by electrolyzing water, and a second mode capable of generating electricity by reacting hydrogen and oxygen, A storage battery capable of charging electricity generated by a power generation facility that generates electricity using renewable energy and electricity generated by the reversible SOC system, and capable of supplying the charged electricity to the reversible SOC system, A hydrogen storage unit capable of storing hydrogen generated by the reversible SOC system and supplying the stored hydrogen to the reversible SOC system, The system includes a control unit capable of controlling the exchange of power between the power generation equipment, the reversible SOC system, and the storage battery.

[0009] Furthermore, the reversible SOC system operates in the first mode when the power generated by the power generation equipment is above a threshold and the amount of charge stored in the battery is above a threshold, generating hydrogen by electrolyzing water using the power supplied from the power generation equipment, or the power supplied from the power generation equipment and the battery, and storing it in the hydrogen storage unit; and operates in the second mode when the power generated by the power generation equipment is below a threshold and the amount of charge stored in the battery is below a threshold, generating power using the hydrogen stored in the hydrogen storage unit. The control unit smooths the power generated by the power generation equipment while the power generated by the power generation equipment is above a threshold value, sets the smoothed power as the target power to be supplied to the reversible SOC system, and if the power generated by the power generation equipment is greater than the target power, supplies the target power from the power generated by the power generation equipment to the reversible SOC system and charges the battery with the remaining power, and if the power generated by the power generation equipment is less than the target power, supplies all of the power generated by the power generation equipment to the reversible SOC system and supplies the difference between the target power and the power generated by the power generation equipment from the battery to the reversible SOC system.

[0010] The power generation system described herein enables the stable production of hydrogen using renewable energy and reduces the required battery capacity for stable hydrogen production. Specifically, when the power generated by the power generation equipment is greater than the target power, power equal to the target power is supplied to the reversible SOC system from the power generated by the power generation equipment, and the remaining power is charged to the battery. On the other hand, when the power generated by the power generation equipment is less than the target power, all of the power generated by the power generation equipment is supplied to the reversible SOC system, and the difference between the target power and the power generated by the power generation equipment is supplied from the battery to the reversible SOC system. As a result, the reversible SOC system is supplied with the target power, which is the smoothed power, and can stably produce hydrogen in the reversible SOC system. Furthermore, the power supplied from the battery to the reversible SOC system only needs to be the difference between the target power (smoothed power) and the power generated by the power generation equipment. Therefore, the required battery capacity for hydrogen production can be reduced. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing the configuration of a power generation system according to an embodiment of the present invention. [Figure 2]This is a schematic diagram showing the operation of a power generation system according to an embodiment of the present invention. [Figure 3A] This is a schematic diagram illustrating the operation of the power generation system according to this embodiment. [Figure 3B] This is a schematic diagram illustrating the operation of the power generation system according to this embodiment. [Figure 4] This flowchart shows the processes performed by the power conditioner for the power generation system of the power generation system according to this embodiment. [Modes for carrying out the invention]

[0012] Figure 1 is a schematic diagram showing the configuration of a power generation system 10 according to an embodiment of the present invention. As shown in Figure 1, the power generation system 10 includes a hydrogen supply source 11, a water supply source 12, an air / oxygen supply source 13, a reversible SOC system 14, a storage battery 15, and a power conditioner 16 for the power generation system. In the following description, the "reversible SOC system" may be referred to as the "r-SOC system," and the "power conditioner for the power generation system" may be referred to as the "system power conditioner."

[0013] The power generation system 10 is configured to produce hydrogen using electricity generated by an external power generation facility 30 that uses renewable energy. Furthermore, the power generation system 10 is configured to generate electricity using the produced hydrogen and supply the generated electricity to an external load 40. In this embodiment, the power generation facility 30 that uses renewable energy is a solar power generation facility. The solar power generation facility is equipped with solar power generation panels that generate electricity when irradiated with light (sunlight). Note that the configuration of the solar power generation facility is not limited, and conventionally known configurations can be applied. Also, if the power generation system 10 is configured to be used in conjunction with a grid power source, the power generation system 10 is connected to the distribution board of the facility (building, etc.) to which the power generation system 10 is applied, and can supply power to the external load 40 (electrical equipment, etc., installed in the facility) via the distribution board and power lines distributed to the facility.

[0014] The hydrogen supply source 11 is equipment (or device) capable of storing hydrogen. For example, the hydrogen supply source 11 may be a tank capable of storing hydrogen. The hydrogen supply source 11 is connected to the r-SOC system 14 and is configured to store hydrogen produced in the r-SOC system 14, as well as to supply the stored hydrogen to the r-SOC system 14.

[0015] The water supply source 12 is equipment (or device) capable of storing water (pure water). For example, a water storage tank can be used as the water supply source 12. The water supply source 12 is connected to the r-SOC system 14 and is configured to store water (pure water) generated by the operation of the r-SOC system 14, and to supply the stored water to the r-SOC system 14. The water supply source 12 may also be configured to generate pure water from water supplied from an external source and to store the generated pure water.

[0016] The air / oxygen supply source 13 is equipment (or device) capable of storing oxygen. The air / oxygen supply source 13 includes a tank capable of storing oxygen and an intake device for taking in outside air. The air / oxygen supply source 13 is connected to the r-SOC system 14 and is configured to store oxygen generated by the operation of the r-SOC system 14, as well as to supply air or oxygen to the r-SOC system 14. The air / oxygen supply source 13 may also be configured to separate oxygen from the outside air and store the separated oxygen.

[0017] The r-SOC system 14 comprises a hot module 21, a hydrogen supply unit 22, a water supply unit 23, an air / oxygen supply unit 24, a cell power adjustment unit 25, and a control unit 26. The hot module 21 comprises a heating unit 211, an electrochemical cell stack 212 formed by stacking multiple electrochemical cells, and an insulated container 213 that houses the heating unit 211 and the electrochemical cell stack 212.

[0018] The electrochemical cells constituting the electrochemical cell stack 212 of the hot module 21 comprise a fuel electrode, a solid electrolyte layer, and an air electrode, which are stacked to form the electrochemical cell. In this embodiment, a reversible solid oxide fuel cell-steam electrolysis cell is used for the electrochemical cell. The reversible solid oxide fuel cell-steam electrolysis cell can generate hydrogen by electrolyzing water (steam), and can generate electricity by reacting hydrogen with oxygen. The specific configuration of the reversible solid oxide fuel cell-steam electrolysis cell is not particularly limited, and conventionally known reversible solid oxide fuel cell-steam electrolysis cells are used.

[0019] The hydrogen supply unit 22 is configured to supply hydrogen from the hydrogen supply source 11 to the heating unit 211 of the hot module 21. The water supply unit 23 is configured to supply water from the water supply source 12 to the heating unit 211 of the hot module 21. The air / oxygen supply unit 24 is configured to supply air or an oxygen-containing gas from the air / oxygen supply source 13 to the air electrode of each electrochemical cell in the electrochemical cell stack 212 of the hot module 21.

[0020] The heating unit 211 of the hot module 21 is configured to generate steam by heating water supplied from the water supply source 12 via the water supply unit 23. The heating unit 211 is also configured to mix the generated steam with hydrogen supplied from the hydrogen supply source 11 via the hydrogen supply unit 22, and to supply the mixture of hydrogen and steam to the fuel electrode of each electrochemical cell in the electrochemical cell stack 212.

[0021] The cell power adjustment unit 25 is configured to adjust the power generated in the electrochemical cell stack 212 and output it to the outside of the r-SOC system 14 when the electrochemical cell stack 212 is generating electricity. Furthermore, when hydrogen is being generated in the electrochemical cell stack 212, the cell power adjustment unit 25 is configured to use power supplied from outside the r-SOC system 14 (power generation equipment 30) to supply an electrolytic current (a current for electrolyzing hydrogen) to each electrochemical cell in the electrochemical cell stack 212.

[0022] The control unit 26 is configured to control each of the aforementioned parts of the r-SOC system 14. The control unit 26 includes a computer comprising a CPU, ROM, RAM, and an I / F (interface). The computer's ROM pre-stores computer programs for controlling each of the aforementioned parts of the r-SOC system 14. Furthermore, the computer of the control unit 26 is connected to the computer of the system power conditioner 16, which will be described later, via the I / F, enabling the transmission and reception of information (signals).

[0023] The battery 15 is electrically connected to the r-SOC system 14. The battery 15 is configured to be able to charge the power generated by the r-SOC system 14, and to supply the charged power to the r-SOC system 14. However, in this embodiment, the battery 15 is not directly connected to the external load 40 and does not supply power to the external load 40. The specific configuration of the battery 15 is not particularly limited, and conventionally known configurations can be applied. The capacity of the battery 15 is determined by the rated power (kW) of the power generation equipment 30 and the smoothing period P described later. L Product of (h) ((Rated power of power generation equipment 30 (kW)) × (Smoothing period P) L (h))) is preferably less than or equal to (h). The rated power is the power generated when the power generation equipment 30 is operating at its rated capacity.

[0024] The system power conditioner 16 is an example of a control device of the present invention. The system power conditioner 16 is electrically connected to the r-SOC system 14, the power generation equipment 30, and the external load 40. The system power conditioner 16 is configured to adjust the power generated in the power generation equipment 30 into a form suitable for use in the r-SOC system 14 and supply it to the r-SOC system 14. The system power conditioner 16 is also configured to adjust the power generated in the r-SOC 14 into a form suitable for consumption by the external load 40 and to send (output) the adjusted power to the outside. In the following description, the power generated in the power generation equipment 30 may be referred to as "external power generation".

[0025] In addition, the system power conditioner 16 may be configured to control the power generation equipment 30. Specifically, the system power conditioner 16 searches for the maximum output point, which is the combination of voltage and current that maximizes the amount of power generated by the power generation equipment 30 (solar power generation panels), and controls the power generation equipment 30 so that the amount of power generated is maintained. Furthermore, the system power conditioner 16 may be equipped with a grid connection protection function.

[0026] The system power conditioner 16 includes a computer comprising a CPU, ROM, RAM, and an interface. The ROM of this computer pre-stores a computer program for controlling the power generation system 10. The computer of the system power conditioner 16 is connected to the computer of the control unit 26 of the r-SOC system 14 via an interface, enabling the transmission and reception of information (signals). The CPU of this computer reads the program from the ROM, loads it into the RAM, and executes the computer program. This enables the operation of the power generation system 10, as described later.

[0027] Next, the basic operation of the power generation system 10 will be described. The power generation system 10 has two operating modes: a first mode (hydrogen production mode) and a second mode (fuel cell mode), and operation in either of these two modes can be selected. The first mode is the operating mode in which hydrogen is produced in the r-SOC system 14. The second mode is the operating mode in which electricity is generated in the r-SOC system 14.

[0028] First mode (hydrogen production mode) The first mode is an operating mode in which hydrogen is produced by electrolyzing water (steam) mainly using externally generated power. The control unit 26 of the r-SOC system 14 heats the electrochemical cell stack 212 to a predetermined temperature and flows an electrolytic current through each electrochemical cell in the electrochemical cell stack 212. This electrolytic current mainly uses externally generated power. The control unit 26 of the r-SOC system 14 also controls the water supply unit 23 to supply water to the heating unit 211 and controls the hydrogen supply unit 22 to supply hydrogen to the heating unit 211. The water supplied from the water supply unit 23 is heated in the heating unit 211 and turns into steam. The mixture of steam generated in the heating unit 211 and hydrogen supplied from the hydrogen supply unit 22 is supplied to the fuel electrode of each electrochemical cell in the electrochemical cell stack 212. Meanwhile, the control unit 26 supplies air from the air / oxygen supply source 13 to the air electrode of each electrochemical cell in the electrochemical cell stack 212 via the air / oxygen supply unit 24.

[0029] As a result, the reaction shown in equation (1) below proceeds at the fuel electrode of each electrochemical cell in the electrochemical cell stack 212. H2O + 2e - →H2+O 2- ...Formula (1)

[0030] Furthermore, oxide ions (O) generated at the fuel electrode of each electrochemical cell in the electrochemical cell stack 212 2- ) moves to the air electrode through the electrolyte layer, and the reaction shown in equation (2) below proceeds at the air electrode. O 2- →(1 / 2)O2+2e - ...Formula (2)

[0031] Thus, in the first mode, hydrogen is generated at the fuel electrode of each electrochemical cell in the electrochemical cell stack 212, and oxygen is generated at the air electrode. The hydrogen generated at the fuel electrode is fed to the hydrogen supply source 11 and stored. The oxygen generated at the air electrode is fed to the air / oxygen supply source 13 and stored.

[0032] Second mode (fuel cell mode) The second mode is an operation mode in which power generation is performed by reacting hydrogen and oxygen in each electrochemical cell of the electrochemical cell stack 212. The control unit 26 of the r-SOC system 14 heats the electrochemical cell stack 212 to a predetermined temperature. Also, the control unit 26 of the r-SOC system 14 controls the water supply unit 23 to supply water from the water supply source 12 to the heating unit 211, and controls the hydrogen supply unit 22 to supply hydrogen to the heating unit 211. The water supplied from the water supply source 12 is heated in the heating unit 211 to become steam. The mixture of steam generated in the heating unit 211 and hydrogen supplied from the hydrogen supply source 11 is supplied to the fuel electrode of each electrochemical cell of the electrochemical cell stack 212. On the other hand, the control unit 26 controls the air / oxygen supply unit 24 to supply a gas containing oxygen from the air / oxygen supply source 13 to the air electrode of each electrochemical cell of the electrochemical cell stack 212.

[0033] Thereby, the reaction shown in the following formula (3) proceeds at the fuel electrode of each electrochemical cell of the electrochemical cell stack 212. H2+O 2- →H2O+2e - …Formula (3)

[0034] Also, the reaction shown in the following formula (4) proceeds at the air electrode of each electrochemical cell of the electrochemical cell stack 212. (1 / 2)O2+2e - →O 2- …Formula (4)

[0035] And the oxide ion (O 2-As the gas moves through the electrolyte layer, electricity is generated in each electrochemical cell of the electrochemical cell stack 212, and water (water vapor) is produced. The gas emitted from the fuel electrode contains unreacted hydrogen and water vapor. The gas emitted from the fuel electrode is separated into unreacted hydrogen and water obtained by condensing water vapor. The unreacted hydrogen is supplied to the hydrogen supply source 11 for storage, and the water (pure water) produced by condensation is supplied to the water supply source 12 for storage. The gas emitted from the air electrode contains unreacted oxygen. The unreacted oxygen is supplied to the air / oxygen supply source 13 for storage.

[0036] The generated electricity is supplied to the system power conditioner 16. The electricity supplied to the system power conditioner 16 is then adjusted to a form suitable for consumption by the external load 40 and output externally from the system power conditioner 16 (i.e., from the power generation system 10). In the second mode, the generated electricity is not supplied to the battery 15. That is, in the second mode, the electricity generated by the r-SOC system 14 is not used to charge the battery 15. However, the remaining amount of stored energy in the battery 15 is determined by the energy storage threshold C described later. S If the value is less than the value, the power generated by the r-SOC system 14 may also be used to charge the battery 15 in the second mode.

[0037] Thus, the r-SOC system 14 can selectively operate in the first mode and the second mode. The control unit 26 can switch between the first mode and the second mode of operation in response to signals (commands) transmitted from the system power conditioner 16.

[0038] Next, the specific operation of the power generation system 10 will be explained. The system power conditioner 16 continuously monitors (measures) the amount of power supplied from the power generation equipment 30. Then, the system power conditioner 16 smooths the power according to the amount of external power generation power (power supplied from the power generation equipment 30). For example, the system power conditioner 16 will say, "at the current time t N A predetermined finite period P ending at " LThe moving average of power over a certain period is continuously calculated. Hereafter, this finite period will be referred to as the "smoothing period P". L It is sometimes written that the system power conditioner 16 has a predetermined power threshold E that is set in advance for the smoothed power (moving average of power). S The system continuously performs a check to determine whether the condition is above or below the stated value.

[0039] The aforementioned smoothing period P L The length is not particularly limited, but a length of a few minutes (3-5 minutes), for example, is applicable. S The power value is greater than 0 and is the power that enables hydrogen production by the r-SOC system 14. S " is preferably the minimum power that can produce hydrogen in the r-SOC system 14. The smoothed power is the power threshold E S If the above is true, then the current time t N Smoothing period P with end date L Within this context, it means that the externally generated power was generally greater than or equal to the power required to produce hydrogen in the r-SOC system 14. And in this case, at present time t N For a period of time thereafter, it is expected that the externally generated power will be greater than the power available to produce hydrogen in the r-SOC system 14.

[0040] Furthermore, the system power conditioner 16 acquires (or measures) the remaining amount of stored energy in the battery 15 (the amount of power that can be supplied to the r-SOC system 14), and the acquired remaining amount sets a predetermined energy threshold C S The process of determining whether the value is above or below is performed continuously. Energy storage threshold C S "The r-SOC system 14 performs the smoothing period P L This is the amount of electricity required to produce hydrogen over a period of the same length as the battery. Therefore, the remaining amount of charge in the battery 15 is the charge threshold C. S If the above conditions are met, the r-SOC system 14 will operate using only the power supplied from the battery 15 during the smoothing period P, even if no power is supplied from the power generation equipment 30 (even if the external power generation is 0). L Hydrogen can be produced over a period of the same length.

[0041] The smoothed power is the power threshold E S If the above conditions are met, the remaining amount of stored energy in the battery 15 is equal to the energy storage threshold C. S If at least one of the above conditions is met, the system power conditioner 16 transmits a signal to the control unit 26 of the r-SOC system 14 instructing it to operate in the first mode. On the other hand, if the smoothed power is at a predetermined power threshold E S It is less than the storage threshold C, and the remaining amount of stored energy in the battery 15 is less than the storage threshold C. S If the value is less than the specified value, the system power conditioner 16 sends a signal to the control unit 26 of the r-SOC system 14 instructing it to operate in the second mode. When the control unit 26 of the r-SOC system 14 receives a signal instructing it to operate in the first mode, if it is already operating in the first mode at the time of reception, it continues to operate in the first mode, or if it is already operating in the second mode at the time of reception, it switches to operating in the first mode. Similarly, when the control unit 26 of the r-SOC system 14 receives a signal instructing it to operate in the second mode, if it is already operating in the second mode at the time of reception, it continues to operate in the second mode, or if it is already operating in the first mode at the time of reception, it switches to operating in the second mode.

[0042] Figure 2 is a schematic diagram showing the relationship between external power generation, remaining energy storage, and switching of operating modes. External power generation fluctuates according to weather conditions, and the remaining energy storage fluctuates according to the operating status of the power generation equipment 30 and the r-SOC system 14, so it may become unstable (fluctuate over time). However, in Figure 2, fluctuations in external power generation and the remaining energy storage of the battery 15 in response to changes in weather conditions are not taken into consideration.

[0043] As shown in Figure 2, when there is no sunlight (or little sunlight) at night, the external power generation is 0 or close to 0. Then, with the arrival of dawn, the external power generation increases, and the external power generation reaches the power threshold E SWhen this happens, the system power conditioner 16 sends a signal to the control unit 26 of the r-SOC system 14 instructing it to operate in the first mode. As a result, the operating mode of the r-SOC system 14 switches from the second mode to the first mode. At time t1 in the figure, the external power generation power reaches the power threshold E S This is the point at which the system switches from the second mode to the first mode. Also, in the first mode, the battery 15 may be charged (described later), so the remaining charge increases. At time t2, the remaining charge reaches the charge threshold C. S This indicates the point at which the power exceeds the power threshold E. S When the remaining amount of stored energy in battery 15 falls below the storage threshold C (at time t3), and the remaining amount of stored energy in battery 15 falls below the storage threshold C. S When the value falls below a certain level (at time t4), the system power conditioner 16 sends a signal to the control unit 26 of the r-SOC system 14 instructing it to operate in the second mode. As a result, the operating mode of the r-SOC system 14 switches from the first mode to the second mode.

[0044] The electricity generated by the renewable energy power generation facility 30 may be unstable (the power may fluctuate over time). For example, if the renewable energy source is solar power, the amount of electricity generated by the power generation facility 30 may fluctuate depending on weather conditions. For this reason, in a configuration that uses electricity generated by the renewable energy power generation facility 30 to produce hydrogen, stable hydrogen production may not be possible. In addition, electrochemical cells equipped with a solid electrolyte layer, such as a reversible solid oxide fuel cell-steam electrolysis cell, have low tolerance to load fluctuations, so it is preferable to stabilize the electrolysis current (reduce rapid fluctuations in the field current) when operating in first mode.

[0045] Therefore, while the r-SOC system 14 is in the first operating mode, the system power conditioner 16 primarily uses externally generated power as the electrolytic current supplied to each electrochemical cell in the electrochemical cell stack 212, and uses the power from the storage battery 15 to smooth the electrolytic current. This stabilizes the electrolytic current (prevents or suppresses sudden fluctuations in the field current). By stabilizing the electrolytic current, hydrogen can be produced stably.

[0046] The specific operation of the power generation system 10 is as follows. Figures 3A and 3B are schematic diagrams illustrating the specific operation of the power generation system 10, and the external power generation E O This graph shows an example of the fluctuation. The system power conditioner 16 controls the target power E, which is the target value of the power supplied from the power generation equipment 30 to the r-SOC system 14. T The calculation of and external power generation E N (E O The target power E calculated by ) T Is it above, or is it target power E? T Is it above or above, or is it the target power E? T The check to see if it is less than will be performed continuously. N " is currently N This indicates the externally generated power in the area, and is described as "E O " is currently N This shows the external power generation at each point in time within the period including the target power E. T External power generation E O A moving average is applied. More specifically, the system power conditioner 16 calculates "the current time t N A point in time t that is earlier than L Starting from the present time t N A predetermined finite period P ending on L External power generation E at each point in time within O The "average value" at the current time t N Target power E at the point immediately following T Set to this "predetermined finite period P". L " is the aforementioned energy storage threshold C S The "smoothing period P" used in the calculation L The same period as "[ ]" is fine.

[0047] As shown in Figure 3A, the current time t N External power generation E N Target power E T In the above case, regardless of the remaining charge of the battery 15, the target power E can be achieved by using externally generated power. T Power equal to t is supplied to the r-SOC system 14. And at the present time t N External power generation E N Target power E T If it is above, the target power E will be selected from the externally generated power. T If power equal to E is supplied to the r-SOC system 14, the surplus power (external power generation E) will be used. N and target power E T A difference occurs. The system power conditioner 16 then supplies the surplus power to the battery 15 (charges the battery 15). Note that the power generated by the power generation equipment 30 is the target power E. T If equal to E, the system power conditioner 16 will control the external power generation E. N all of (i.e., target power E T A power equal to this is supplied to the r-SOC system 14.

[0048] On the other hand, as shown in Figure 3B, the current time t N External power generation E N Target power E T If it is less than the storage threshold C, the remaining amount of energy stored in battery 15 is less than the storage threshold C. S If the above conditions are met, the system power conditioner 16 will use external power generation E N All of this is supplied to the r-SOC system 14. Furthermore, the system power conditioner 16 supplies the target power E T and external power generation E N The system power conditioner 16 supplies power equal to the difference between this and the target power E (hereinafter sometimes referred to as "power deficit") from the battery 15 to the r-SOC system 14. In other words, the power deficit is compensated for by the power charged in the battery 15. As a result, the system power conditioner 16 can achieve the target power E T This power is supplied to the r-SOC system 14.

[0049] However, external power generation E N Target power ET is less than, and when the remaining power storage amount of the storage battery 15 is less than the power storage threshold C S even if the insufficient power is supplemented with the power of the storage battery 15, there may be a case where the power equal to the target power E T cannot be supplied to the r-SOC system 14. Therefore, in this case, the system power conditioner 16 transmits a signal instructing operation in the second mode to the control unit 26 of the r-SOC system 14. For this reason, in this case, the r-SOC system 14 is operated in the second mode.

[0050] According to such an operation, while the r-SOC system 14 is operating in the first mode, the power equal to the target power E T is always supplied to the r-SOC system 14. Therefore, stabilization of the electrolysis current can be achieved. Therefore, hydrogen can be stably produced. In addition, a rapid fluctuation in the load applied to each electrochemical cell of the electrochemical cell stack 212 of the r-SOC system 14 is prevented or suppressed.

[0051] Further, according to such an operation, the capacity of the storage battery 15 can be reduced. As described above, in the power generation system 10 according to the present embodiment, while the r-SOC system 14 is operating in the first mode, the smoothed power becomes less than the power threshold E S and when the remaining power storage amount of the storage battery 15 becomes less than the power storage threshold C S the operation mode switches to the second mode. For this reason, the capacity of the storage battery 15 may be the capacity that can operate the r-SOC system 14 in the first mode for a period of the same length as the "smoothing period P L . For example, in the configuration where "even when the power generation facility 30 is not generating power, the operation in the first mode is continued (not switched to the operation in the second mode) by the power of the storage battery 15", a large-capacity storage battery 15 is required to continue the operation in the first mode. Also, in the configuration where "the power supplied to the r-SOC system 14 is a fixed value (constant value) and the shortage is supplemented with the power of the storage battery 15", the capacity of the storage battery 15 is determined according to the maximum value of the power generated by the power generation facility 30.

[0052] In contrast, in the present embodiment, since the capacity of the storage battery 15 may be as described above, the size of the storage battery 15 applied to the power generation system 10 can be reduced. Therefore, the size of the power generation system 10 can be reduced.

[0053] Also, even if the smoothed power is less than the power threshold E S and the remaining charge amount of the storage battery 15 is equal to or greater than the charge threshold C S the r-SOC system 14 operates in the first mode. Therefore, compared with a configuration in which the operation in the second mode is immediately executed when the smoothed power is less than the power threshold E S the operation time in the first mode can be lengthened. Therefore, the tolerance to fluctuations in weather conditions can be increased.

[0054] Next, the processing executed by the computer of the system power conditioner 16 will be described. FIG. 4 is a flowchart showing the processing executed by the computer of the system power conditioner 16. A computer program for executing this processing is stored in advance in the ROM of the computer of the system power conditioner 16. The CPU of the computer of the system power conditioner 16 reads out this computer program and repeatedly executes it continuously at a predetermined short cycle. Thereby, the operation of the power generation system 10 described above is realized. In the following description, the computer of the system power conditioner 16 may be simply abbreviated as the computer.

[0055] In step S 101, the computer determines whether the external power generation power E N at the current time t N is less than the power threshold E S or equal to or greater than the power threshold E S If the computer determines that the external power generation power E N is less than the power threshold E S the process proceeds to step S102, and if the external power generation power E N is equal to or greater than the power threshold E S the process proceeds to step S103.

[0056] In step S102, the computer determines that the remaining amount of charge in the battery 15 is equal to the charge threshold C. S Is the storage threshold C above or above? S Determine if it is less than the storage threshold C. The computer determines if the remaining amount of energy in the battery 15 is less than the storage threshold C. S If the above is true, proceed to step S103, and the remaining energy storage amount is the energy storage threshold C. S If the value is less than the specified value, proceed to step S109.

[0057] In step S103, the computer sends a signal to the control unit 26 of the r-SOC system 14 instructing it to operate the r-SOC system 14 in first mode. The computer then proceeds to step S104. Upon receiving this signal, the control unit 26 of the r-SOC system 14 operates the r-SOC system 14 in first mode. If the r-SOC system 14 is already operating in first mode, the control unit 26 continues to operate it in first mode.

[0058] In step S104, the computer determines the target power E T This is set. Specifically, the computer will use external power generation E O Moving average (smoothing period P) L External power generation E O The average of the calculations is used to determine the target power E. T The computer then sets the value to S105.

[0059] In step S105, the computer receives external power E N Target power E T Is it above, or is it the target power E? T Equivalent to, or target power E T Determine if it is less than E. The computer calculates the external power generation E. N Target power E T If it is greater than, proceed to step S106, and the external power generation E N Target power E T If it is equal to the above, proceed to step S107, and the external power generation EN Target power E T If it is less than, proceed to step S108.

[0060] In step S106, the computer receives external power E N A portion of the target power E T The computer supplies power equal to E to the r-SOC system 14. The computer also sends a signal to the control unit 26 of the r-SOC system 14 instructing it to charge the battery 15 with the surplus power. The computer then terminates the series of processes. Upon receiving this signal, the control unit 26 of the r-SOC system 14 charges the battery 15 with the surplus power. The control unit 26 of the r-SOC system 14 receives power from the power generation equipment 30 (external power generation E) N Part of the target power E T Hydrogen is produced using an electrolytic current (equal to the power of the computer). Then the computer terminates the series of processes.

[0061] In step S107, the computer receives external power E N All of this is supplied to the r-SOC system 14. The control unit 26 of the r-SOC system 14 controls the externally generated power E N All of (Target power E T Hydrogen is produced using an electrolytic current (equal to the power of the computer). Then the computer terminates the series of processes.

[0062] In step S108, the computer receives external power E N All of this is supplied to the r-SOC system 14. The computer also supplies any insufficient power to the r-SOC system 14 from the battery 15. The control unit 26 of the r-SOC system 14 controls the externally generated power E N The total power supplied from all of the batteries and the battery 15 (Target power E) T Hydrogen is produced using an electrolytic current (equal to the power of ). Then, the computer terminates the series of processes.

[0063] In step S109, the computer sends a signal to the control unit 26 of the r-SOC system 14 instructing it to operate in second mode. The computer then terminates the series of processes. Upon receiving this signal, the control unit 26 of the r-SOC system 14 operates the r-SOC system 14 in second mode. If the control unit 26 is already operating the r-SOC system 14 in second mode, it continues to operate in second mode.

[0064] This process achieves the behavior described above.

[0065] Although embodiments of the present invention have been described above, the technical scope of the present invention should not be limited to the above embodiments. The present invention is modifiable without departing from its spirit, and such modifications are also included within the technical scope of the present invention.

[0066] For example, the above embodiment shows a configuration in which the system power conditioner 16 controls the power generation equipment 30, but the present invention is not limited to such a configuration. The power generation equipment 30 may include a power conditioner, and this power conditioner may have a function to adjust the power generated by the power generation equipment 30 and a grid connection protection function. In this case, the system power conditioner 16 of the power generation system 10 is electrically connected to the power conditioner of the power generation equipment 30. The system power conditioner 16 of the power generation system 10 is configured to receive power from the power conditioner of the power generation equipment 30 and to send the power generated in the r-SOC system 14 to the outside via the power conditioner of the power generation equipment 30. Therefore, in this case, the system power conditioner 16 does not need to have a function to adjust the power generated by the power generation equipment 30 and a grid connection protection function.

[0067] Furthermore, in the above embodiment, the power generated by the power generation equipment 30 is the power threshold E S Is it above or above the power threshold E? SThe configuration shown determines the switching of the operating mode depending on whether it is less than a certain value, but the configuration is not limited to this. For example, the power generation equipment 30 may consume power for its own operation. Also, the power generation equipment 30 may be configured to supply power to an external load 40 directly or via the system power conditioner 16. In these cases, only a portion, not all, of the power generated by the power generation equipment 30 is supplied to the power generation system 10. Therefore, the maximum value of the power generated by the power generation equipment 30 that can be supplied to the power generation system 10 is the power threshold E. S Is it above or above the power threshold E? S Whether it is less than or equal to the power threshold or power threshold E S The configuration may determine whether to switch the operating mode depending on whether it is less than a certain value. In other words, the "external power generation" in the above description may not be "power generated by the power generation equipment 30" at each point in time, but rather "the maximum amount of power that can be supplied from the power generation equipment 30 to the power generation system 10" at each point in time.

[0068] Furthermore, although the above embodiment showed a system power controller 16 as an example of the control device of the present invention, the present invention is not limited to such a configuration. For example, the control unit 26 of the r-SOC system 14 may be an example of the control device of the present invention.

[0069] Furthermore, although the above embodiment showed a method using a moving average for smoothing power, power smoothing is not limited to the method using a moving average, and various known smoothing methods can be applied. In this case, the smoothing period P L This is set appropriately depending on the method of power smoothing. For example, a first-order lag filter may be used as a method of power smoothing. In this case, the smoothing period P L The time constant of the first-order lag filter is applied.

[0070] Furthermore, in this embodiment, the power generation system 10 is shown to be equipped with a water supply source 12 and an air / oxygen supply source 13, with the water supply source 12 capable of storing water (pure water) and the air / oxygen supply source 13 capable of storing oxygen, but the system is not limited to such configurations. The power generation system 10 does not have to be configured to store water and oxygen. In this case, the water separated from the gas (a mixture of hydrogen and water vapor) discharged from the fuel electrode may be discharged to the outside of the power generation system 10. In addition, the oxygen generated at the air electrode during operation in the first mode, and the unreacted oxygen discharged from the air electrode during operation in the second mode, may be released into the atmosphere.

[0071] Furthermore, this disclosure may include the following aspects:

[0072] [1] A reversible SOC system including an electrochemical cell stack that can operate in operating modes including a first mode capable of generating hydrogen by electrolyzing water, and a second mode capable of generating electricity by reacting hydrogen and oxygen, A storage battery capable of charging electricity generated by a power generation facility that generates electricity using renewable energy and electricity generated by the reversible SOC system, and capable of supplying the charged electricity to the reversible SOC system, A hydrogen storage unit capable of storing hydrogen generated by the reversible SOC system and supplying the stored hydrogen to the reversible SOC system, A control unit capable of controlling the transfer of power between the power generation equipment, the reversible SOC system, and the storage battery, Equipped with, The reversible SOC system operates in the first mode when the power generated by the power generation equipment is above a threshold and the amount of charge in the battery is above a threshold, generating hydrogen by electrolyzing water using the power supplied from the power generation equipment, or the power supplied from the power generation equipment and the battery, and storing it in the hydrogen storage unit; and operates in the second mode when the power generated by the power generation equipment is below a threshold and the amount of charge in the battery is below a threshold, generating power using the hydrogen stored in the hydrogen storage unit. The control unit smooths the power generated by the power generation equipment while the power generated by the power generation equipment is above a threshold, sets the smoothed power as the target power to be supplied to the reversible SOC system, supplies the target power from the power generated by the power generation equipment to the reversible SOC system and charges the battery with the remaining power, and supplies all of the power generated by the power generation equipment to the reversible SOC system and the difference between the target power and the power generated by the power generation equipment from the battery to the reversible SOC system. Power generation system.

[0073] [2] The power generation system described in [1] above, The capacity of the storage battery is less than or equal to the amount of energy expressed as the product of the rated power of the power generation equipment and the smoothing period. Power generation system. [Explanation of Symbols]

[0074] 10...Power generation system, 14...Reversible SOC system (r-SOC system), 15...Storage battery, 16...Power conditioner for power generation system (system power conditioner), 30...Power generation equipment

Claims

1. A reversible SOC system including an electrochemical cell stack that can operate in operating modes including a first mode capable of generating hydrogen by electrolyzing water, and a second mode capable of generating electricity by reacting hydrogen and oxygen, A storage battery capable of charging electricity generated by a power generation facility that generates electricity using renewable energy and electricity generated by the reversible SOC system, and capable of supplying the charged electricity to the reversible SOC system, A hydrogen storage unit capable of storing hydrogen generated by the reversible SOC system and supplying the stored hydrogen to the reversible SOC system, A control unit capable of controlling the transfer of power between the power generation equipment, the reversible SOC system, and the storage battery, Equipped with, The reversible SOC system operates in the first mode when the power generated by the power generation equipment is above a threshold and the amount of charge in the battery is above a threshold, generating hydrogen by electrolyzing water using the power supplied from the power generation equipment, or the power supplied from the power generation equipment and the battery, and storing it in the hydrogen storage unit; and operates in the second mode when the power generated by the power generation equipment is below a threshold and the amount of charge in the battery is below a threshold, generating power using the hydrogen stored in the hydrogen storage unit. The control unit smooths the power generated by the power generation equipment while the power generated by the power generation equipment is above a threshold, sets the smoothed power as the target power to be supplied to the reversible SOC system, supplies the target power from the power generated by the power generation equipment to the reversible SOC system and charges the battery with the remaining power, and supplies all of the power generated by the power generation equipment to the reversible SOC system and supplies the difference between the target power and the power generated by the power generation equipment from the battery to the reversible SOC system. Power generation system.

2. A power generation system according to claim 1, The capacity of the storage battery is less than or equal to the amount of energy expressed as the product of the rated power of the power generation equipment and the smoothing period. Power generation system.

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