Water electrolysis system and method for operating water electrolysis system

Abstract

To provide a water electrolysis system capable of delivering adjustment forces only by itself and a method for operating the water electrolysis system.SOLUTION: A water electrolysis system gives grid power to a plurality of water electrolysis stacks via a rectifier, generates a hydrogen gas and an oxygen gas as a product gas from water, and adjusts power consumption according to an adjustment force delivery command. When it accepts an adjustment force delivery command within an agreement time zone in which adjustment force delivery is agreed, the water electrolysis system can control a supply water amount to an electrolysis stack, an electrolysis stack temperature, and a pressure according to the electric energy obtained by adding the power consumption of the adjustment force to be delivered to the power consumption of the electrolysis stack.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water electrolysis system in which power consumption is changed in response to requirements of an electric power supply and demand adjustment market, and a method for operating the water electrolysis system. [Background technology]

[0002] Compared to fossil fuels, hydrogen is a clean energy source that does not emit carbon dioxide when burned. For this reason, hydrogen has been attracting attention as one of the clean energies for global warming countermeasures, and technological development regarding the production, transportation, and use of hydrogen is being promoted. Water electrolysis systems are known as one method of hydrogen production. In this context, the present application relates to an apparatus for large-scale hydrogen production by electrolysis of water using renewable energy, etc., and a control method thereof.

[0003] CO 2 Free hydrogen needs to be produced from energy sources such as renewable energy and nuclear power. Renewable energy sources such as wind and solar power have large fluctuations in output over time, and as their generating capacity increases, an adjustment capability is needed to adjust the balance between power supply and demand. Meanwhile, water electrolysis systems that produce hydrogen are consumers, but their power consumption can be adjusted, and the amount of power they consume is large. For this reason, it has been proposed to adjust the power consumption of water electrolysis systems and use this as an adjustment capability.

[0004] Patent Document 1 describes that in the event of demand response, the optimal operation of the hydrogen production equipment and the storage batteries and hydrogen storage facilities can level out fluctuations in the supply and demand balance caused by fluctuations in renewable energy output and provide adjustment power to the power grid.

[0005] Patent Document 2 states that because the production and storage of hydrogen, charging of storage batteries, and power generation by fuel cells are used in combination, if an error occurs between the predicted value of surplus electricity used as the basis for formulating the electricity transmission plan and the actual value, the error can be easily reduced.

[0006] Therefore, Patent Documents 1 and 2 claim that fluctuations in the supply and demand balance caused by fluctuations in the output of renewable energy can be leveled out by changing the output of the hydrogen production equipment and charging and discharging the storage battery, thereby providing adjustment power to the power grid. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-170097 A [Patent Document 2] JP 2020-54085 A Summary of the Invention [Problem to be solved by the invention]

[0008] In Patent Documents 1 and 2, the response of the output control of the hydrogen production equipment is slower than that of a storage battery, making it difficult to operate stably, and there is an issue that a large proportion of the adjustment power control needs to be handled by the storage battery.

[0009] Therefore, the present invention aims to provide a water electrolysis system and a method for operating a water electrolysis system that are capable of providing adjustment power using only the water electrolysis system, by controlling the amount of water supply and the water electrolysis stack temperature and pressure according to the hydrogen production volume necessary for providing the agreed-upon adjustment power, rather than controlling the amount of water supply and the water electrolysis stack temperature and pressure optimally according to the hydrogen production volume, during the time period when adjustment power agreed upon in the adjustment power market is provided, and by quickly responding to a request for the provision of adjustment power by changing the output of the water electrolysis device. [Means for solving the problem]

[0010] In view of the above, the present invention provides a "water electrolysis system that provides system power to a plurality of water electrolysis stacks via a rectifier to generate hydrogen gas and oxygen gas as product gases from water, and adjusts power consumption in response to a command to provide adjustment power, characterized in that, when a command to provide adjustment power is received within an agreement time period for which the provision of adjustment power is agreed upon, the water electrolysis system is capable of controlling the amount of water supplied to the water electrolysis stacks, the temperature and the pressure of the water electrolysis stacks in response to an amount of power obtained by adding the amount of power of the adjustment power to be provided to the amount of power consumed by the water electrolysis stacks."

[0011] The present invention provides a "water electrolysis system operation method for generating hydrogen gas and oxygen gas as product gases from water by providing system power to a plurality of water electrolysis stacks via a rectifier, and adjusting power consumption in response to a command to provide adjustment power, characterized in that when a command to provide adjustment power is received within an agreement time period in which the provision of adjustment power is agreed upon, the method is capable of controlling the amount of water supplied to the water electrolysis stacks, the temperature and the pressure of the water electrolysis stacks in accordance with the amount of power obtained by adding the amount of power of the adjustment power to be provided to the amount of power consumed by the water electrolysis stacks, and setting the amount of adjustment power that can be provided such that the sum of the bid price for adjustment power when adjustment power is provided and the hydrogen sales price after the provision of adjustment power is greater than the hydrogen sales price when adjustment power is not provided." Effect of the Invention

[0012] According to the present invention, the temperature and pressure of the water electrolysis stack can be stably controlled in response to the provision of adjustment power, which is one method of stabilizing the grid. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a water electrolysis system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example of the internal block configuration of a system control unit of the water electrolysis system according to the embodiment of the present invention. [Diagram 3] An explanatory diagram of operational control for providing upward adjustment capacity. [Figure 4] An explanatory diagram of operational control for providing downward adjustment capacity. [Diagram 5] An explanatory diagram of operational control for providing upward adjustment capacity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. In addition, in each drawing, common or similar components are given the same reference numerals, and duplicated explanations thereof will be omitted.

[0015] Before describing the embodiments of the present invention, prerequisites for a water electrolysis system will be summarized below.

[0016] First, the water electrolysis stack used in the water electrolysis system may be of an alkaline type, a solid polymer type, an anion exchange membrane type, etc. The present invention is applicable to any type of electrolytic cell, but a solid polymer type with excellent output response will be shown as an example.

[0017] In a typical water electrolysis stack, the energy conversion efficiency from electricity to hydrogen is about 70-90%, and the remainder becomes heat, which heats the components of the water electrolysis stack and the water flowing inside. For this reason, the temperature increases from the upstream to the downstream of the water flow path, and a temperature distribution occurs in the water electrolysis stack. The higher the temperature of the electrolysis cell of the water electrolysis stack, the lower the resistance becomes, but when the temperature exceeds the heat resistance temperature, the electrolyte membrane and electrode catalyst constituting the electrolysis cell deteriorate and the resistance increases, the electrolyte membrane separating hydrogen and oxygen is thinned and the amount of hydrogen and oxygen permeated increases, holes are formed in the electrolyte membrane, and an electrical short circuit occurs. In addition, when the volume ratio of the generated gas to the water, which is the raw material for the reaction, is high in the flow path of the electrolysis cell, the resistance increases due to insufficient water supply to the electrodes, and the current concentrates in the area with a low volume ratio of gas. Such current concentration leads to a local temperature rise, which causes deterioration and failure. Therefore, it is important to suppress the occurrence of temperature differences and high gas volume ratio areas in the electrolysis cell.

[0018] Most of the heat generated in the water electrolysis stack is carried out by the supplied water to the outside of the water electrolysis stack, and the temperature difference generated in the water flow direction inside the water electrolysis stack is proportional to the amount of heat generated in the electrolytic cell and inversely proportional to the water flow rate. In addition, the amount of gas generated is proportional to the current, and the higher the current value, the higher the gas volume ratio at the flow outlet. Therefore, in order to suppress the temperature difference and high gas volume ratio region in the electrolysis cell, it is important to supply enough water according to the current and output of the water electrolysis stack and at the same time to manage the temperature at an appropriate level for hydrogen production. EXAMPLES

[0019] Hereinafter, with reference to FIG. 1, a configuration example of a water electrolysis system 100 according to an embodiment of the present invention will be described.

[0020] As shown in FIG. 1, a water electrolysis system 100 according to an embodiment of the present invention includes a water tank 13, a plurality of water electrolysis units 20 (20a...20n), a hydrogen gas tank 61, an oxygen gas tank 62, a system control unit 80, and a data communication unit 90.

[0021] The water electrolysis system 100 performs hydrogen production operation by adjusting the voltage from the grid power 73, providing an insulating transformer 71 that insulates the water electrolysis unit 20 from the grid side, a rectifier 70 that converts AC power to DC power, and supplying DC power from the rectifier 70 to the water electrolysis stack 23 through a DC cable 72. In the example shown in Fig. 1, a power supply line from the rectifier 70 is connected to the water electrolysis unit 20a and the water electrolysis unit 20n, but the multiple water electrolysis units 20 are connected in series and parallel so that a general large-scale DC power supply can be used. There is no particular limit to the number of series and parallel connections.

[0022] Details will be described later, but the main functions of each part in FIG. 1 are as follows. First, the water tank 13 is a storage unit for water to be supplied to the water electrolysis unit 20. The water electrolysis unit 20 is a component that electrolyzes water to produce hydrogen gas and oxygen gas. The hydrogen gas tank 61 is a storage unit for the hydrogen gas produced in the water electrolysis unit 20. The oxygen gas tank 62 is a storage unit for the oxygen gas produced in the water electrolysis unit 20. The system control unit 80 is a component that controls the operation of each part of the system. The data communication unit 90 is a component that transmits and receives data to and from the outside. The functions of each part will be described in detail below.

[0023] A water tank 13, which is a storage unit for water supplied to the water electrolysis units 20, is connected to each water electrolysis unit 20 via water piping 10. In the water electrolysis system 100, water in the water tank 13 is pressurized by a water pump 11, cooled by a large cooler 12, and then taken into the oxygen electrode side of the water electrolysis unit 20. In the example shown in Fig. 1, the water electrolysis system 100 is configured to supply water only to the oxygen electrode side. However, the water electrolysis system 100 may be configured to supply water to both the hydrogen electrode side and the oxygen electrode side.

[0024] 1, the water electrolysis unit 20 internally includes a water flow rate control valve 21 and a compact cooler 22. The water electrolysis unit 20 also includes a water electrolysis stack 23 that electrolyzes water to generate hydrogen gas and oxygen gas.

[0025] The water electrolysis unit 20, which electrolyzes water to generate hydrogen gas and oxygen gas, is composed of components on the hydrogen system 30 side and components on the oxygen system 40 side. The components on the hydrogen system 30 side include a separation tank 31, a pressure regulating valve 32, and a water discharge valve 33.

[0026] The separation tank 31 is a component that separates water and hydrogen gas. The pressure regulating valve 32 is a valve for sending hydrogen gas from the water electrolysis unit 20 to the hydrogen gas tank 61 via the hydrogen gas pipe 51 by adjusting its opening. The pressure regulating valve 32 has a function of adjusting the internal pressure of the water electrolysis stack 23 to a predetermined pressure by adjusting its opening. The water discharge valve 33 is a valve that drains the water separated in the separation tank 31 to the outside. The water discharge valve 33 has a function of adjusting the internal pressure of the water electrolysis stack 23 to a predetermined pressure by adjusting its opening.

[0027] The water electrolysis unit 20 also has a separation tank 41, a pressure regulating valve 42, and a water discharge valve 43 as components on the oxygen system 40 side related to oxygen. The separation tank 41 is a component that separates water and oxygen gas. The pressure regulating valve 42 is a valve for sending oxygen gas from the water electrolysis unit 20 to the oxygen gas tank 62 via the oxygen gas pipe 52 by adjusting its opening. The pressure regulating valve 42 has a function of adjusting the internal pressure of the water electrolysis stack 23 to a predetermined pressure by adjusting its opening. The water discharge valve 43 is a valve that drains the water separated in the separation tank 41 to the outside of the water electrolysis stack 23. The water discharge valve 43 has a function of adjusting the internal pressure of the water electrolysis stack 23 to a predetermined pressure by adjusting its opening.

[0028] In such a water electrolysis system 100, the water separated in the separation tank 31 and the separation tank 41 is adjusted to a predetermined pressure by the water discharge valve 33 and the water discharge valve 43, recovered in the water tank 13, and then supplied again to the water electrolysis stack 23 via the water pump 11.

[0029] The water electrolysis system 100 then supplies the hydrogen gas G1 stored in the hydrogen gas tank 61 to the outside by opening the pressure regulating valve 63. At this time, the water electrolysis system 100 adjusts the pressure of the hydrogen gas G1 to a predetermined pressure by adjusting the aperture of the pressure regulating valve 63 to a predetermined aperture.

[0030] Furthermore, the water electrolysis system 100 supplies the oxygen gas G2 stored in the oxygen gas tank 62 to the outside by opening the pressure regulating valve 64. At this time, the water electrolysis system 100 adjusts the pressure of the oxygen gas G2 to a predetermined pressure by adjusting the aperture of the pressure regulating valve 64 to a predetermined aperture.

[0031] 2 is an internal block diagram of the system control unit 80. The configuration of the system control unit 80 will be described below with reference to FIG.

[0032] 2, a system control unit 80 configured using a computer includes a calculation unit 81 and a storage unit 82. The calculation unit 81 includes an operation control unit 81a, a value setting unit 81b, and a regulation power determination unit 81c.

[0033] The operation control unit 81a is a component that controls the hydrogen production operation of the water electrolysis system 100. The value setting unit 81b is a component that sets various parameters. The adjustment capacity determination unit 81c is a component that determines the amount of power to be provided as adjustment capacity.

[0034] The storage unit 82 also stores reference information 82a and a control program Pr. The reference information 82a is information that is referenced when performing a hydrogen production operation, when setting various parameters, and the like. The control program Pr is a program that causes the calculation unit 81 to function as an operation control unit 81a, a value setting unit 81b, and an adjustment power determination unit 81c. The control program Pr is stored in a storage medium 99, and is installed in the system control unit 80 from the storage medium 85 directly or indirectly.

[0035] Data measured in the water electrolysis system 100, such as the water electrolysis stack voltage, the water electrolysis cell voltage, and the temperature, pressure, flow rate, and current of each part of the apparatus, are managed by a system control unit 80. The system control unit 80 controls the DC power using the rectifier 70 based on the operation command, and calculates the operation amount required for stable operation of the water electrolysis stack 23 based on the data and reference information 82a (FIG. 2) pre-registered in a storage unit 82 (FIG. 2). The system control unit 80 then transmits control signals to each device of the water electrolysis system 100, such as the valves, pumps, and coolers, to control each device.

[0036] Next, we will explain the method for controlling the water electrolysis system when supplying adjustment reserve, but before that, we will explain the underlying concept of adjustment reserve supply. First, in the electricity supply and demand adjustment market, adjustment reserve transactions are agreed upon through advance bidding. For example, with tertiary adjustment reserve, the amount of adjustment reserve that can be supplied is sometimes agreed upon through bidding the day before the actual supply and demand section, or the ΔkW that can be used for adjustment in the target week (Saturday to Friday) is sometimes agreed upon through bidding the week before. In either case, the response time (the time from when a command is given to supply), duration, available supply amount, and increase / decrease category are determined for adjustment reserve transactions before the actual supply and demand section.

[0037] The increase category is a category in which adjustment capacity is provided to deal with the occurrence of a shortage imbalance in the power supply area. The decrease category is a category in which adjustment capacity is provided to deal with the occurrence of a surplus imbalance in the power supply area.

[0038] Although the water electrolysis system is usually operated under conditions that provide the best hydrogen production cost and efficiency, it is necessary to vary the power consumption of the water electrolysis system 100 within the response time in order to provide adjustment power within the contracted response time. At this time, the temperature change caused by the change in the amount of heat generated by the water electrolysis stack 23, which is caused by changing the power consumption of the water electrolysis system 100 within the response time, is difficult to control because of its slow time response.

[0039] A control method for stably operating the water electrolysis system 100 when adjusting capacity is provided will be described below with reference to Figures 3 to 5. Note that the horizontal axis in Figures 3 to 5 indicates a 24-hour period on the day in the actual supply and demand section, and the vertical axis indicates the relationship between the power consumption and the amount of equipment operation that is changed in response to a supply command given in the contract time period.

[0040] 3 is an explanatory diagram of operation control for providing upward adjustment power in a 20 MW water electrolysis system 100. If the system control unit 80 receives a command to provide adjustment power from the adjustment power market operator while the water electrolysis stack 23 is producing hydrogen with a power consumption of 20 MW during a time period when the agreed upon 5 MW adjustment power is provided, the system control unit 80 changes the output (equipment operation amount) of the rectifier 70 from 20 MW to 15 MW, sets the power consumption of the water electrolysis stack 23 to 15 MW, and provides the agreed upon 5 MW upward adjustment power.

[0041] Thereafter, the system control unit 80 calculates operation amounts required for stable operation of the water electrolysis stack 23 based on the reference information 82a registered in advance in the memory unit 82, and transmits control signals to each device of the water electrolysis system 100, such as the valves, pumps, and coolers, to control each device.

[0042] Furthermore, after the time period for providing the agreed-upon 5 MW adjustment power ends, the system control unit 80 calculates the output of the rectifier 70 from the hydrogen demand and stored amount using a value setting unit 81 b so that hydrogen demand can be covered. The system control unit 80 calculates the operation amount required for stable operation of the water electrolysis stack 23 based on reference information 82 a registered in advance in the memory unit 82, and sends control signals to each device of the water electrolysis system 100, such as the valves, pumps, coolers, etc., to control each device.

[0043] The idea in Figure 3 is that the equipment is operated only after a supply command is issued during the contract time period, and the contracted 5 MW of upward adjustment power is supplied, while exploring and responding to the stable operation of the water electrolysis stack 23 under the new operating conditions. This idea can be said to be a reactive type of processing in the case of a long-term contract time period.

[0044] Figure 4 is also an explanatory diagram of operational control for supplying downward adjustment power in the 20 MW water electrolysis system 100. This example is for a long-term contract time period, as in Figure 3, but the idea is to transition to stable operation of the water electrolysis stack 23 in a new operating state before the contract time period begins (i.e., before a supply command is issued).

[0045] Specifically, in FIG. 4 , before the time period when the agreed adjustment power of 5 MW is provided, when the water electrolysis stack 23 is producing hydrogen with a power consumption of 20 MW, the system control unit 80 changes the output of the rectifier 70 from 20 MW to 15 MW, and each device of the water electrolysis system 100, such as the valves, pumps, and coolers, is controlled under the condition that the water electrolysis stack 23 is producing hydrogen with a power consumption of 20 MW.

[0046] When the system control unit 80 receives a command to provide adjustment power from the adjustment power market operator, the system control unit 80 changes the output of the rectifier 70 from 15 MW to 20 MW, sets the power consumption of the water electrolysis stack 23 to 20 MW, and provides the agreed downward adjustment power of 5 MW.

[0047] Thereafter, the system control unit 80 calculates operation amounts required for stable operation of the water electrolysis stack 23 based on the reference information 82a registered in advance in the memory unit 82, and transmits control signals to each device of the water electrolysis system 100, such as the valves, pumps, and coolers, to control each device.

[0048] Furthermore, after the time period for providing the agreed-upon 5 MW adjustment power ends, the system control unit 80 calculates the output of the rectifier 70 from the hydrogen demand and stored amount using a value setting unit 81 b so that hydrogen demand can be covered. The system control unit 80 calculates the operation amount required for stable operation of the water electrolysis stack 23 based on reference information 82 a registered in advance in the memory unit 82, and sends control signals to each device of the water electrolysis system 100, such as the valves, pumps, coolers, etc., to control each device.

[0049] In contrast, Figure 5 assumes a case where the settlement time period is short, and shows an example in which in such a state, rather than searching for a new stable state in response to a supply command (rather than performing equipment operations for the search), it is more efficient and stable to maintain the previous state in the event of a crisis.

[0050] Specifically, in FIG. 5 , as another operational control for providing upward adjustment power in a 20 MW water electrolysis system 100, when the water electrolysis stack 23 is producing hydrogen with a power consumption of 20 MW during a time period in which the agreed upon adjustment power of 5 MW is provided, if the system control unit 80 receives a command to provide adjustment power from the adjustment power market operator, the system control unit 80 changes the output of the rectifier 70 from 20 MW to 15 MW, sets the power consumption of the water electrolysis stack 23 to 15 MW, and provides the agreed upon adjustment power of 5 MW.

[0051] When the time period for providing the agreed adjustment power is within two hours, the system control unit 80 calculates the operation amount required for stable operation of the water electrolysis stack 23, such as the valves, pumps, coolers, etc. of the water electrolysis system 100, based on information when the water electrolysis stack 23 was producing hydrogen with a power consumption of 20 MW, and the system control unit 80 sends control signals to each device of the water electrolysis system 100, such as the valves, pumps, coolers, etc., to control each device.

[0052] Furthermore, after the time period for providing the agreed-upon 5 MW adjustment power ends, the system control unit 80 calculates the output of the rectifier 70 from the hydrogen demand and stored amount using a value setting unit 81 b so that hydrogen demand can be covered. The system control unit 80 calculates the operation amount required for stable operation of the water electrolysis stack 23 based on reference information 82 a registered in advance in the memory unit 82, and sends control signals to each device of the water electrolysis system 100, such as the valves, pumps, coolers, etc., to control each device.

[0053] As described above, the water electrolysis system 100 according to this embodiment can reduce changes in the temperature and pressure of the water electrolysis stack 23 caused by providing adjustment power to the adjustment power market, and can stably control the water electrolysis system 100.

[0054] The present invention is not limited to the above-described embodiment, and includes various modified examples. For example, the above-described embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to having all of the configurations described. In addition, it is possible to replace a part of the configuration of the embodiment with another configuration, and it is also possible to add another configuration to the configuration of the embodiment. In addition, it is possible to add, delete, or replace a part of each configuration with another configuration. [Explanation of symbols]

[0055] 10: Water piping 11: Water supply, pump 12: Large cooler 13: Water tank 20,23a,23n: Water electrolysis section 21: Water flow control valve 22: Small cooler 23: Water electrolysis stack 30: Hydrogen system 31: Separation tank 32: Pressure regulating valve 33: Water discharge valve 40: Oxygen system 41: Separation tank 42: Pressure regulating valve 43: Water drain valve 51: Hydrogen gas piping 52: Oxygen gas piping 61: Hydrogen gas tank 62: Oxygen gas tank 63: Pressure regulating valve 64: Pressure regulating valve 70: Rectifier 71: Isolation transformer 72: DC cable 73: Grid power 80: System control section 81: Arithmetic section 81a: Operation control unit 81b: Value setting section 81c:Adjustment force judgment section 82: Storage section 82a: References 85:Storage medium 90: Data Communications Department 100: Water electrolysis system G1: Hydrogen gas G2: Oxygen gas W1:Water Pr: Control program

Claims

1. A water electrolysis system that supplies grid power to a plurality of water electrolysis stacks via a rectifier to generate hydrogen gas and oxygen gas as generated gases from water, and adjusts power consumption in response to a supply command of adjustment power, A water electrolysis system capable of controlling the amount of water supplied to the water electrolysis stack, the temperature of the water electrolysis stack, and the pressure in response to an amount of electric power obtained by adding the amount of electric power of the adjustment power to be provided to the amount of electric power consumed by the water electrolysis stack, when a command to provide adjustment power is received within an agreed time period for the provision of adjustment power.

2. The water electrolysis system according to claim 1, A water electrolysis system comprising: a water electrolysis stack that controls an amount of water supplied to the water electrolysis stack, a temperature of the water electrolysis stack, and a pressure in accordance with an optimal amount of power consumption of the water electrolysis stack during a period when no command to supply adjustment power has been received.

3. The water electrolysis system according to claim 1, A water electrolysis system characterized in that, before an agreed time period for the provision of adjustment capacity, the amount of water supplied to the water electrolysis stack, the temperature of the water electrolysis stack, and the pressure are controlled in accordance with an amount of power obtained by adding the amount of power of the adjustment capacity to the amount of power consumed by the water electrolysis stack, and when a command to provide adjustment capacity is received thereafter, the amount of power consumed by the water electrolysis stack is increased by an amount equal to the agreed amount of power to be provided.

4. The water electrolysis system according to claim 1, a water electrolysis system characterized in that, when a command to provide adjustment power is received during a time period in which an agreed-upon adjustment power is provided, the amount of power consumed by the water electrolysis stack is reduced by an amount equal to the agreed-upon amount of power to be provided, and then, if the time period in which the adjustment power is provided is short, the amount of water supplied to the water electrolysis stack, the temperature and the pressure of the water electrolysis stack are controlled in accordance with the amount of power consumed before the power consumption of the water electrolysis stack is changed.

5. The water electrolysis system according to claim 4, a water electrolysis system characterized in that, when a command to provide adjustment power is received during a time period in which an agreed-upon adjustment power is provided, the amount of power consumed by the water electrolysis stack is reduced by an amount equal to the agreed-upon amount of power to be provided, and then, if the time period in which the adjustment power is provided is within two hours, the amount of water supplied to the water electrolysis stack, the temperature and the pressure of the water electrolysis stack are controlled in accordance with the amount of power consumed before the power consumption of the water electrolysis stack was changed.

6. A water electrolysis system operation method comprising: supplying grid power to a plurality of water electrolysis stacks via a rectifier to generate hydrogen gas and oxygen gas as product gases from water; and adjusting power consumption in response to a supply command of adjustment power, When a command to provide adjustment power is received within a contract time period for which the provision of adjustment power is contracted, the amount of water supplied to the water electrolysis stack, the temperature of the water electrolysis stack, and the pressure can be controlled according to the amount of power obtained by adding the amount of power of the adjustment power to be provided to the amount of power consumed by the water electrolysis stack, A water electrolysis system operation method comprising: setting an available amount of adjustment power so that the sum of the adjustment power bid price when adjustment power is provided and the hydrogen sales price after the adjustment power is provided is greater than the hydrogen sales price when adjustment power is not provided.

7. The water electrolysis system operating method according to claim 6, A water electrolysis system operation method comprising: monitoring a hydrogen storage amount and setting an adjustable output amount so that the hydrogen supply amount of the water electrolysis system can meet hydrogen demand.

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