A wind power hydrogen production system based on seabed energy storage hydrogen storage and a control method thereof

Abstract

The application discloses a kind of wind power hydrogen production systems and control method of hydrogen storage based on seabed, which comprises: offshore wind power hydrogen production unit, including floating wind power platform, converter and electrolytic cell of electrolytic hydrogen production unit;Seabed hydrogen storage unit, including first rigid non-standard pressure vessel, which is divided into first condition water cavity and hydrogen storage cavity, hydrogen storage cavity is connected with electrolytic cell or hydrogen equipment;Seabed compressed air energy storage device, including second rigid non-standard pressure vessel, compressor and turbine, second rigid non-standard pressure vessel is divided into second condition water cavity and air cavity by piston mechanism arranged in it;Flexible water storage bag is connected with first condition water cavity and second condition water cavity respectively by flexible riser.The application can eliminate hydrogen embrittlement risk, smooth wind power fluctuation, so that system energy balance, ensure stable work of electrolytic cell, improve hydrogen production efficiency, reduce equipment investment cost, prolong equipment life, reduce system complexity and maintenance cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of offshore wind power hydrogen production and energy storage systems in the field of new energy, and particularly relates to a wind power hydrogen production system based on seabed energy storage and hydrogen storage and a control method thereof. BACKGROUND

[0002] With the increasing demand for clean energy worldwide, offshore wind power, as a large-scale and sustainable clean energy, has great development potential. The combination of offshore wind power and water electrolysis hydrogen production technology to produce "green hydrogen" has become one of the important directions to realize energy transformation.

[0003] However, the current offshore wind power hydrogen production and hydrogen storage technology still faces many challenges. Offshore wind power is intermittent and volatile, which directly affects the stability of electrolytic hydrogen production; at the same time, hydrogen storage faces high energy consumption for high-pressure compression, serious equipment corrosion and other problems. The traditional floating energy storage scheme is limited by platform space and has safety hazards, especially the risk of hydrogen leakage is more prominent in the offshore environment, and there are many problems when applied to offshore scenarios. High-pressure gaseous hydrogen storage requires a large amount of energy to compress hydrogen, and the hydrogen storage equipment is bulky and occupies offshore platform space; cryogenic liquid hydrogen storage requires complex refrigeration equipment to maintain a low-temperature environment, which is high in energy consumption and difficult to ensure safety. Solid-state hydrogen storage needs to use solid-state hydrogen storage materials to absorb and release hydrogen, which is restricted by material conditions. In addition, the offshore environment is complex, and the corrosion and biofouling problems of seawater pose a serious challenge to the durability of energy storage equipment. How to utilize the characteristics of offshore resources to achieve efficient, stable and low-cost operation of the wind power hydrogen production system and promote the development of offshore wind power hydrogen production industry has become a technical problem to be solved. SUMMARY

[0004] The purpose of the present application is to solve the problems of large energy fluctuation, high hydrogen storage energy consumption and easy corrosion of equipment in the process of offshore wind power hydrogen production in the prior art, and to provide a wind power hydrogen production system based on seabed energy storage and hydrogen storage and a control method thereof. The present application realizes efficient and stable operation of the hydrogen production system by utilizing the characteristics of offshore resources, thereby reducing the cost.

[0005] The purpose of the present application is achieved by the following technical scheme: the first aspect of the embodiment of the present application provides a wind power hydrogen production system based on seabed energy storage and hydrogen storage, comprising:

[0006] The offshore wind power hydrogen production unit comprises a floating wind power platform, a converter and an electrolytic hydrogen production unit, the electrolytic hydrogen production unit comprises an electrolytic cell, the floating wind power platform converts wind energy into electric energy output, the electric energy is converted into direct current for the operation of the electrolytic cell through the converter, and the electrolytic cell uses direct current to electrolyze water to produce hydrogen;

[0007] The seabed hydrogen storage unit comprises a first rigid non-standard pressure container, the inside of the first rigid non-standard pressure container is divided into a first condition water cavity and a hydrogen storage cavity with a flexible membrane, and the hydrogen storage cavity is connected with an electrolytic cell or a hydrogen equipment through a flexible riser;

[0008] The seabed compressed air energy storage device comprises a second rigid non-standard pressure container, a compressor and a turbine, the inside of the second rigid non-standard pressure container is divided into a second condition water cavity and an air cavity through a piston mechanism arranged therein, the compressor and the turbine are connected with the electrolytic hydrogen production unit through a flexible riser, air is compressed by the compressor and then delivered to the air cavity, and the compressed air drives the turbine to release energy when the compressed air is released, so that the circulation of the condition water is realized.

[0009] The flexible water storage bag is connected with the first condition water cavity and the second condition water cavity through flexible risers respectively.

[0010] Further, the installation depth of the seabed hydrogen storage unit depends on the hydrogen storage required pressure, the hydrogen storage required pressure directly matches the water depth static pressure, the static water pressure is used for self-balancing instead of mechanical compression, and the installation depth of the seabed hydrogen storage unit is determined by the following formula:

[0011]

[0012]

[0013] In the formula, represents the installation depth of the seabed hydrogen storage unit under seawater, represents the water depth static pressure, represents the water density, represents the gravitational acceleration, represents the hydrogen storage required pressure, represents the atmospheric pressure.

[0014] Further, the working state of the seabed compressed air energy storage device comprises an energy storage state and an energy release state, the seabed compressed air energy storage device exchanges energy with the offshore wind power hydrogen production unit through a riser soft cable according to power demand, and the control law is:

[0015]

[0016] In the formula, represents the pulse duty cycle of the connection between the seabed compressed air energy storage device and the direct current bus converter; represents a PI controller of a circuit, and s represents a Laplace operator, represents a proportional coefficient of the PI controller, represents an integral coefficient of the PI controller; represents an output power reference value, represents an energy storage output power.

[0017] Further, the calculation formula of the output power reference value is:

[0018]

[0019] In the formula, represents the total power of the offshore wind power generation unit, represents the power consumption of the electrolytic hydrogen production load.

[0020] Further, the calculation formula of the energy storage output power is:

[0021]

[0022] In the formula, represents the compression power of the compressor, represents the energy release power of the turbine.

[0023] Further, the compression power of the compressor is calculated by the following formula:

[0024]

[0025]

[0026] In the formula, is the specific heat capacity, is the gas constant, is the gas mass flow during air compression, is the outlet temperature of the compressor, is the inlet temperature of the compressor, is the compression ratio, is the adiabatic index, is the charging efficiency;

[0027] The energy release power of the turbine is calculated by the following formula:

[0028]

[0029]

[0030] In the formula, is the gas mass flow during release of compressed air, is the inlet temperature of the turbine, is the outlet temperature of the turbine, is the expansion ratio, is the discharging efficiency.

[0031] Further, the first rigid non-standard pressure container and the second rigid non-standard pressure container are both installed with pressure sensors for real-time detection of the internal pressure of the submarine hydrogen storage unit and the submarine compressed air energy storage device.

[0032] The first rigid non-standard pressure container is provided with a safety valve, and the second rigid non-standard pressure container is provided with a compressed air valve.

[0033] The pressure sensor installed on the first rigid non-standard pressure container communicates with the safety valve to ensure safe operation of the submarine hydrogen storage unit, and the pressure sensor installed on the second rigid non-standard pressure container communicates with the compressor to control the action of the compressor according to the pressure detection data.

[0034] Further, the flexible film is made of reinforced fluororubber and polyamide fabric laminated film;

[0035] The flexible water storage bag is made of aramid fiber or PVC composite film material.

[0036] The second aspect of the embodiment of the application provides a control method of the submarine energy storage hydrogen-based wind power hydrogen production system.

[0037] The power generation power of the offshore wind power hydrogen production unit and the electrolytic hydrogen production load consumption power of the electrolytic cell are monitored in real time to determine the current energy demand, wherein the energy demand refers to the system power surplus or deficiency; hydrogen is generated by the offshore wind power hydrogen production unit and is filled into the hydrogen storage cavity of the submarine hydrogen storage unit; the internal pressure of the submarine hydrogen storage unit and the submarine compressed air energy storage device is detected in real time to obtain a pressure detection value; the submarine compressed air energy storage device is controlled according to the current energy demand and the pressure detection value to balance the system energy, stabilize the wind power generation power, and ensure stable operation of the electrolytic cell.

[0038] Further, the submarine compressed air energy storage device is controlled according to the current energy demand and the pressure detection value, specifically including:

[0039] When the system power is surplus, the submarine compressed air energy storage device drives the compressor by using the surplus power of the offshore wind power hydrogen production unit to control the action of the compressor according to the pressure detection value, compresses the air to a high pressure state, injects the compressed air into the air cavity, and extrudes the condition water in the second condition water cavity to be discharged from the second rigid non-standard pressure container to the flexible water storage bag;

[0040] When the system power is deficient, the compressed air valve is opened, the submarine compressed air energy storage device releases the compressed air, the turbine is started to release energy, and the condition water in the flexible water storage bag automatically flows back to the second condition water cavity under the driving of the pressure difference.

[0041] The beneficial effects of the present application are that the submarine hydrogen storage unit in the present application realizes self-balancing of hydrogen storage by using submarine hydrostatic pressure, and mechanical compression energy consumption is saved; the submarine compressed air energy storage device can smooth wind power fluctuations, ensure stable operation of the electrolytic cell in the electrolytic hydrogen production unit, and improve hydrogen production efficiency; the submarine hydrogen storage unit and the submarine compressed air energy storage device use a rigid non-standard pressure vessel built by reinforced concrete structure as their corresponding hydrogen storage and energy storage containers, and there is no metal pressure-bearing component, which can effectively eliminate the risk of hydrogen embrittlement, the reinforced concrete and flexible film material in it are corrosion-resistant and suitable for offshore environment, which can effectively prolong the service life of the equipment; the submarine hydrogen storage unit and the submarine compressed air energy storage device share a flexible water storage bag, reducing the equipment investment cost; the seawater natural heat sink simplifies the heat management system, and there is no need for high-pressure compression and additional cooling equipment, reducing the operation cost, system complexity and maintenance cost; the units in the system work cooperatively to realize efficient storage and utilization of energy and dynamic balance; the whole system makes full use of renewable energy, conforms to the green energy development trend, has significant economic and environmental benefits, is suitable for large-scale offshore wind power hydrogen production scenarios, and is conducive to promoting the development of offshore wind power hydrogen production industry. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a structural schematic diagram of the wind power hydrogen production system based on submarine energy storage and hydrogen storage of the present application;

[0043] Figure 2 is a control method schematic diagram of the wind power hydrogen production system based on submarine energy storage and hydrogen storage of the present application. DETAILED DESCRIPTION

[0044] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, unless otherwise indicated, like numbers in the attached drawings refer to the same or similar elements. The embodiments described in the following exemplary embodiments are not meant to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims.

[0045] The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the present application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0046] It should be understood that, although the terms first, second, third, etc. can be used herein to describe various information, the information should not be limited to these terms. These terms are only used to distinguish one category of information from another category of information. For example, a first information can also be termed a second information, and, similarly, a second information can also be termed a first information without departing from the scope of the present application. The word "if' as used herein can be interpreted as meaning "when" or "upon" or "in response to determining" depending on the context.

[0047] The present application will now be described in detail with reference to the drawings. The features described in the following examples and embodiments can be combined with each other insofar as they do not conflict.

[0048] Reference is made to Figure 1The wind power hydrogen production system based on seabed energy storage hydrogen storage of the application comprises a sea surface offshore wind power hydrogen production unit and a seabed hydrogen storage unit, a seabed compressed air energy storage device and a flexible water storage bag under seawater. The offshore wind power hydrogen production unit comprises a floating wind power platform, a converter and an electrolytic hydrogen production unit. The floating wind power platform converts wind energy into electric energy output. The electric energy is converted into direct current suitable for the operation of the electrolytic cell in the electrolytic hydrogen production unit through the converter. The electrolytic cell uses direct current to electrolyze water to produce hydrogen. The seabed hydrogen storage unit comprises a first rigid non-standard pressure container. The interior of the first rigid non-standard pressure container is divided into a first condition water cavity and a hydrogen storage cavity with a flexible membrane. The first condition water cavity of the first rigid non-standard pressure container is used to contain condition water. The hydrogen storage cavity of the first rigid non-standard pressure container is used to store hydrogen produced by the offshore wind power hydrogen production unit. The hydrogen storage cavity of the first rigid non-standard pressure container is connected with the electrolytic cell or hydrogen equipment in the electrolytic hydrogen production unit through a flexible riser to realize hydrogen charging and discharging. The first condition water cavity of the first rigid non-standard pressure container is connected with the flexible water storage bag through a flexible riser. The seabed compressed air energy storage device comprises a second rigid non-standard pressure container, a compressor and a turbine. The interior of the second rigid non-standard pressure container is provided with a piston mechanism. The interior of the second rigid non-standard pressure container is divided into a second condition water cavity and an air cavity through the piston mechanism. The second condition water cavity of the second rigid non-standard pressure container is used to contain condition water. The air cavity of the second rigid non-standard pressure container is used to store compressed air. The setting of the piston mechanism makes the condition water in the second condition water cavity below the piston mechanism easy to be pumped in and out. In the seabed compressed air energy storage device, the second rigid non-standard pressure container is used as a gas storage tank. During the gas charging process of the gas storage tank, the compressor and the turbine are connected with the electrolytic hydrogen production unit through a flexible riser. The sea air of the electrolytic hydrogen production unit is injected into the seabed compressed air energy storage device through the flexible riser. The compressor delivers the compressed air to the air cavity of the second rigid non-standard pressure container, and then stores the compressed air in the air cavity of the second rigid non-standard pressure container. The condition water is pumped out of the second condition water cavity of the second rigid non-standard pressure container and then enters the flexible water storage bag. During the compressed air release process, the turbine can be driven to release energy. The condition water is driven by the pressure difference and rushes into the second condition water cavity of the second rigid non-standard pressure container from the flexible water storage bag, and is provided with a pump to control water circulation. During the energy storage and release process, the seabed compressed air energy storage device performs the gas charging and discharging actions according to the control instructions. The first condition water cavity of the seabed hydrogen storage unit and the second condition water cavity of the seabed compressed air energy storage device are connected with the flexible water storage bag through flexible risers. The two share the flexible water storage bag. The interior of the flexible water storage bag stores condition water and is isolated from the surrounding seawater. In this way, the condition water can flow.

[0049] Further, the installation depth of the seabed hydrogen storage unit depends on the hydrogen storage required pressure. The hydrogen storage required pressure directly matches the water depth static pressure. The static water pressure is used for self-balancing instead of mechanical compression. The installation depth of the seabed hydrogen storage unit is determined by the following formula:

[0050]

[0051]

[0052] wherein, represents the installation depth of the seabed hydrogen storage unit under seawater, represents the hydrostatic pressure, represents the water density, represents the gravity acceleration, represents the required pressure of hydrogen storage, represents the atmospheric pressure.

[0053] As Figure 1 indicated, the hydrogen generated by the offshore wind power hydrogen production unit is filled into the hydrogen storage cavity of the seabed hydrogen storage unit, or the amount of hydrogen in the hydrogen storage cavity changes when the useful hydrogen equipment is working, at this time, the membrane body of the flexible membrane attached to the hydrogen storage cavity will also be deformed, extruding the condition water in the first condition water cavity outside the flexible membrane, and pushing it to flow into the flexible water storage bag. When the hydrogen storage cavity reaches the limit pressure, the mechanical safety valve is triggered to release pressure, preventing the first rigid non-standard pressure vessel from overpressure explosion. Seawater as a natural heat sink, indirectly cools the seabed hydrogen storage unit through the container wall of the first rigid non-standard pressure vessel, without the need for additional cooling equipment, simplifying thermal management.

[0054] Further, the working state of the seabed compressed air energy storage device includes energy storage state and energy release state, and the seabed compressed air energy storage device exchanges energy with the offshore wind power hydrogen production unit through the riser soft cable according to the power demand, as Figure 2 indicated, the control law is:

[0055]

[0056] wherein, represents the pulse duty cycle connected between the seabed compressed air energy storage device and the DC bus converter; represents the PI controller of the circuit, and s represents the Laplace operator, represents the proportional coefficient of the PI controller, represents the integral coefficient of the PI controller; represents the output power reference value, represents the energy storage output power.

[0057] Further, the calculation formula of the output power reference value is:

[0058]

[0059] wherein, represents the total power of the offshore wind power hydrogen production unit, represents the power consumption of the electrolytic hydrogen production load.

[0060] Further, the calculation formula of the energy storage output power is:

[0061]

[0062] In the formula, represents the compression power of the compressor, represents the energy release power of the turbine.

[0063] It should be noted that, in the absence of energy storage, the offshore wind power hydrogen production unit must be highly dynamic or need to cut a large amount of wind power through the system of hydrogen production by electrolyzing water. With the help of energy storage, frequent on-off operation of the electrolytic cell can be avoided, thereby prolonging the service life of the electrolytic cell.

[0064] Further, the compression power of the compressor is calculated by the following formula:

[0065]

[0066]

[0067] In the formula, is the specific heat capacity, is the gas constant, is the gas mass flow when the air is compressed, is the outlet temperature of the compressor, is the inlet temperature of the compressor, is the compression ratio, is the adiabatic index, is the charging efficiency.

[0068] Further, the energy release power of the turbine is calculated by the following formula:

[0069]

[0070]

[0071] In the formula, is the gas mass flow when the compressed air is released, is the inlet temperature of the turbine, is the outlet temperature of the turbine, is the expansion ratio, is the discharging efficiency.

[0072] Further, the first rigid non-standard pressure container and the second rigid non-standard pressure container are both provided with pressure sensors for real-time detection of the internal pressure of the container of the seabed hydrogen storage unit and the seabed compressed air energy storage device, and the system is communicated and cooperated. The first rigid non-standard pressure container is provided with a safety valve, and the second rigid non-standard pressure container is provided with a compressed air valve. The pressure sensor installed on the first rigid non-standard pressure container is communicated with the safety valve (i.e. a mechanical safety valve) to ensure the safe operation of the seabed hydrogen storage unit; the pressure sensor installed on the second rigid non-standard pressure container is communicated with the compressor to control the operation of the compressor according to the pressure detection data.

[0073] Further, the first rigid non-standard pressure container and the second rigid non-standard pressure container are both built with reinforced concrete structure. Since hydrogen is an industrial product that needs to be guaranteed in output and purity, a flexible film needs to be added in the first rigid non-standard pressure container, i.e. a hydrogen cavity for storing hydrogen is additionally provided with a flexible film, and the flexible film of the hydrogen storage cavity is made of reinforced fluororubber and polyamide fabric laminated film, which can prevent hydrogen permeation and seawater corrosion. In addition, since there is no metal pressure-bearing component, and the reinforced concrete shell has high compressive strength, the flexible film is uniformly subjected to internal pressure, which can avoid the hydrogen embrittlement problem of metal containers and completely eliminate the risk of hydrogen embrittlement.

[0074] Further, the flexible water storage bag is made of aramid fiber or PVC composite film material, which has the advantages of pressure resistance, corrosion resistance, flexibility and biological fouling protection. The flexible water storage bag stores condition water inside and isolates it from the surrounding seawater, which can effectively avoid the problems of corrosion and biological fouling accompanied by seawater. The seabed hydrogen storage unit and the seabed compressed air energy storage device share one flexible water storage bag, which can effectively reduce the equipment investment cost.

[0075] It is worth mentioning that the embodiment of the present application also provides a control method of the above-mentioned wind power hydrogen production system based on seabed energy storage and hydrogen storage. The control method specifically comprises: real-time monitoring of the power generation power of the offshore wind power hydrogen production unit and the electrolytic hydrogen production load consumption power of the electrolytic cell, determining the current energy demand, wherein the energy demand refers to the system power surplus or shortage; generating hydrogen by the offshore wind power hydrogen production unit and charging it into the hydrogen storage cavity of the seabed hydrogen storage unit; real-time detection of the internal pressure of the container of the seabed hydrogen storage unit and the seabed compressed air energy storage device to obtain the pressure detection value; controlling the seabed compressed air energy storage device according to the current energy demand and the pressure detection value to balance the system energy, smooth the fluctuation of the wind power generation power and ensure the stable operation of the electrolytic cell. The seabed compressed air energy storage device can interact with the whole power system, maintain energy balance, and can be used to smooth the fluctuation of wind power output, which is beneficial to ensure the stable operation of the offshore wind power hydrogen production unit.

[0076] Further, the submarine compressed air energy storage device is controlled according to the current energy demand and the pressure detection value, and specifically includes: when the system power is surplus, that is, the power generation power of the offshore wind power hydrogen production unit is greater than the power consumption of the electrolytic hydrogen production load of the electrolytic cell , the submarine compressed air energy storage device drives the compressor by using the surplus power of the offshore wind power hydrogen production unit, so as to control the action of the compressor according to the pressure detection value, compress the air to a high-pressure state, inject the compressed air into the air cavity of the second rigid non-standard pressure container, generate a large pressure difference energy storage, and extrude the condition water in the second condition water cavity from the second rigid non-standard pressure container to the flexible water storage bag, so that the compressed air and the condition water are separated by the piston mechanism, and the constant pressure is maintained by using the seawater static pressure. When the system power is insufficient, that is, the power generation power of the offshore wind power hydrogen production unit is less than the power consumption of the electrolytic hydrogen production load of the electrolytic cell , the compressed air valve is opened, the submarine compressed air energy storage device releases the compressed air, the compressed air flows to the offshore platform where the electrolytic hydrogen production unit is located along the flexible riser, the high-pressure air drives the offshore wind power hydrogen production unit to generate power, outputs the electric energy, and starts the turbine to release energy, after the air is released, the condition water in the flexible water storage bag automatically flows back to the second condition water cavity of the second rigid non-standard pressure container under the driving of the pressure difference, so as to maintain the constant pressure in the second rigid non-standard pressure container.

[0077] In summary, the submarine hydrogen storage unit and the submarine compressed air energy storage device are used for energy storage and hydrogen storage in the submarine, the submarine energy storage and hydrogen storage and the offshore wind power hydrogen production are cooperatively designed, the efficient storage and utilization of energy are realized, the problem that the energy storage and hydrogen storage of the offshore wind power hydrogen production unit are affected by the complex offshore environment is solved, and the present application has remarkable economic benefits and environmental benefits, and is suitable for large-scale offshore wind power hydrogen production scenes.

[0078] The above examples are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A wind power-to-hydrogen system based on seabed hydrogen storage, characterized in that, include: The offshore wind power hydrogen production unit includes a floating wind power platform, a converter, and an electrolysis hydrogen production unit. The electrolysis hydrogen production unit includes an electrolyzer. The floating wind power platform converts wind energy into electrical energy for output. The converter converts the electrical energy into direct current for the operation of the electrolyzer. The electrolyzer uses the direct current to electrolyze water to produce hydrogen. The subsea hydrogen storage unit includes a first rigid non-standard pressure vessel. The interior of the first rigid non-standard pressure vessel is divided into a first condition water chamber and a hydrogen storage chamber with a flexible membrane attached. The hydrogen storage chamber is connected to an electrolyzer or hydrogen-using equipment through a flexible riser. The subsea compressed air energy storage device includes a second rigid non-standard pressure vessel, a compressor, and a turbine. The second rigid non-standard pressure vessel divides its interior into a second conditional water chamber and an air chamber through a piston mechanism. The compressor and the turbine are connected to an electrolytic hydrogen production unit through a flexible riser. The compressor compresses the air and delivers it to the air chamber. When the compressed air is released, it drives the turbine to release energy, thereby realizing the circulation of conditional water. The flexible water storage bladder is connected to the first condition water chamber and the second condition water chamber respectively through a flexible riser.

2. The wind power-to-hydrogen system based on subsea hydrogen storage as described in claim 1, characterized in that, The installation depth of the subsea hydrogen storage unit depends on the required hydrogen storage pressure, which is directly matched to the hydrostatic pressure of the water depth. By using the self-balancing of hydrostatic pressure to replace mechanical compression, the installation depth of the subsea hydrogen storage unit can be determined using the following formula: ； ； In the formula, This indicates the installation depth of the subsea hydrogen storage unit in seawater. Indicates water depth and hydrostatic pressure. This indicates the density of water. Represents gravitational acceleration. This indicates the required pressure for hydrogen storage. It represents atmospheric pressure.

3. The wind power-to-hydrogen system based on subsea hydrogen storage as described in claim 1, characterized in that, The subsea compressed air energy storage device operates in two states: energy storage and energy release. Based on power demand, the subsea compressed air energy storage device exchanges energy with the offshore wind power hydrogen production unit via a riser cable. Its control law is as follows: ； In the formula, This indicates the pulse duty cycle connecting the subsea compressed air energy storage device and the DC bus converter. This represents a PI controller for the circuit, where 's' represents the Laplace operator. This represents the proportional gain of the PI controller. This represents the integral coefficient of the PI controller; This indicates the output power reference value. This indicates the output power of the energy storage system.

4. The wind power-to-hydrogen system based on subsea hydrogen storage as described in claim 3, characterized in that, The formula for calculating the output power reference value is: ； In the formula, This indicates the total wind power generation capacity of the offshore wind-powered hydrogen production unit. This indicates the power consumption of the hydrogen production load during electrolysis.

5. The wind power-to-hydrogen system based on subsea hydrogen storage as described in claim 3, characterized in that, The formula for calculating the energy storage output power is as follows: ； In the formula, This indicates the compressor's compression power. This indicates the power output of the turbine.

6. The wind power-to-hydrogen system based on subsea hydrogen storage as described in claim 5, characterized in that, The compression power of the compressor is calculated using the following formula: ； ； In the formula, For specific heat capacity, The gas constant is This refers to the gas mass flow rate during air compression. This refers to the compressor's outlet temperature. This refers to the compressor's inlet temperature. The compression ratio is... The adiabatic index, For charging efficiency; The power output of the turbine is calculated using the following formula: ； ； In the formula, This refers to the mass flow rate of the gas released during compressed air discharge. The turbine inlet temperature, The turbine outlet temperature. The expansion ratio, This refers to the discharge efficiency.

7. The wind power-to-hydrogen system based on subsea hydrogen storage as described in claim 1, characterized in that, Both the first rigid non-standard pressure vessel and the second rigid non-standard pressure vessel are equipped with pressure sensors to detect the internal pressure of the subsea hydrogen storage unit and the subsea compressed air energy storage device in real time. The first rigid non-standard pressure vessel is equipped with a safety valve, and the second rigid non-standard pressure vessel is equipped with a compressed air valve; The pressure sensor installed on the first rigid non-standard pressure vessel communicates with the safety valve to ensure the safe operation of the subsea hydrogen storage unit; the pressure sensor installed on the second rigid non-standard pressure vessel communicates with the compressor to control the compressor operation based on pressure detection data.

8. The wind power-to-hydrogen system based on subsea hydrogen storage as described in claim 1, characterized in that, The flexible membrane is made of reinforced fluororubber and polyamide fabric laminate; The flexible water storage bladder is made of aramid fiber or PVC composite film.

9. A control method for a wind power hydrogen production system based on subsea hydrogen storage, as described in any one of claims 1-8, characterized in that, Specifically, it includes: The system monitors the power generation of the offshore wind power hydrogen production unit and the power consumption of the electrolysis hydrogen production load in real time to determine the current energy demand, which refers to the system's power surplus or deficit. Hydrogen is generated by the offshore wind power hydrogen production unit and filled into the hydrogen storage chamber of the subsea hydrogen storage unit. The internal pressure of the containers in the subsea hydrogen storage unit and the subsea compressed air energy storage device is monitored in real time to obtain pressure detection values. Based on the current energy demand and pressure detection values, the subsea compressed air energy storage device is controlled to maintain system energy balance, smooth fluctuations in wind power generation, and ensure stable operation of the electrolyzer.

10. The control method according to claim 9, characterized in that, The control of the subsea compressed air energy storage device based on current energy demand and pressure detection values ​​specifically includes: When the system has surplus power, the subsea compressed air energy storage device uses the surplus power of the offshore wind power hydrogen production unit to drive the compressor. The compressor is controlled according to the pressure detection value to compress the air to a high pressure state. The compressed air is injected into the air chamber and squeezes the condition water in the second condition water chamber to be discharged from the second rigid non-standard pressure vessel to the flexible water storage bladder. When the system power is insufficient, the compressed air valve is opened, the subsea compressed air energy storage device releases compressed air, starts the turbine to release energy, and the condition water in the flexible water storage bladder automatically flows back to the second condition water chamber under the drive of the pressure difference.

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