Island type micro-grid liquid hydrogen preparation system based on hydrogen energy storage

Abstract

The invention provides an island type micro-grid liquid hydrogen preparation system based on hydrogen energy storage. The island type micro-grid liquid hydrogen preparation system comprises a photovoltaic power generation module, a water electrolysis hydrogen production module, a liquid hydrogen preparation and energy storage module and a hydrogen storage and power generation module. The photovoltaic power generation module uses daytime solar energy to generate unstable electric energy; the electrolyzed water hydrogen production module utilizes electric energy to carry out an electrolyzed water preparation process of hydrogen; the liquid hydrogen preparation and energy storage module is used for preparing liquid hydrogen by virtue of a hydrogen liquefaction technology and storing the liquid hydrogen for subsequent outward transportation; the hydrogen storage and power generation module stores hydrogen, and meanwhile stable electric energy power generation is conducted through the hydrogen. According to the invention, the electric energy quality of the system power grid can be adjusted while full utilization of energy is ensured, so that the reliability of the system is improved.

Description

Technical Field

[0001] The present invention relates to the field of liquid hydrogen preparation systems, and in particular to an island-type microgrid liquid hydrogen preparation system based on hydrogen energy storage. Background Art

[0002] In recent years, with the rapid development of world industry, the demand for energy in various countries has increased dramatically. The non-renewable nature and uneven distribution of traditional fossil fuels will inevitably lead to energy shortages in various countries in the future. At present, the proportion of hydrogen energy in the energy structure is also showing an increasing trend year by year. The preparation, storage and transportation technology of hydrogen energy has gradually developed, which is an important means to solve the uneven distribution of resources and load centers. Among them, the land transportation method of hydrogen energy electric heavy trucks has the characteristics of lower one-time cost investment and flexible transportation routes compared with traditional pipeline transportation. After preliminary calculations, after using high-energy-density liquid hydrogen as a storage medium and reusing hydrogen energy as a power supply and cooling medium for the electric drive system of the vehicle, the loss of a single thousand-kilometer long-distance transportation is about 200kg of liquid hydrogen. In addition, after excluding the loss of liquid hydrogen and the cost of regular vehicle maintenance, the system has no additional costs and is extremely economical.

[0003] For the isolated microgrid liquid hydrogen production system, the electricity used by the system comes entirely from the photovoltaic power station. The main electricity demand includes: water electrolysis hydrogen production equipment, liquid hydrogen production equipment and domestic electricity. These three types of electricity demand have certain requirements for power quality. Taking water electrolysis hydrogen production equipment as an example, considering cost factors, hydrogen production equipment based on alkaline electrolyzers is usually used. The equipment requires a relatively stable power supply during operation, and even if it is shut down, electricity is required to maintain the temperature of the solution in the alkaline cell. Photovoltaic is an unstable energy source and has no output at night. Unstable power supply not only affects the life of hydrogen production equipment, but also fails to provide the electricity required for electrolyzer insulation at night. Summary of the invention

[0004] The purpose of the present invention is to provide an islanded microgrid liquid hydrogen preparation system based on hydrogen energy storage in response to the deficiencies in the above-mentioned background technology, so that the stored hydrogen can be used to generate electricity through fuel cells or hydrogen combustion engines to provide supplementary electric energy for regulating the quality of electric energy.

[0005] In order to achieve the above-mentioned purpose, the present invention provides an island-type microgrid liquid hydrogen preparation system based on hydrogen energy storage, comprising a photovoltaic power generation module, a water electrolysis hydrogen production module, a liquid hydrogen preparation and energy storage module, and a hydrogen storage and power generation module;

[0006] The photovoltaic power generation module uses daytime solar energy to generate unstable electric energy, and transmits it to the water electrolysis hydrogen production module, and is used for domestic electricity; the water electrolysis hydrogen production module uses electric energy to carry out a water electrolysis preparation process for hydrogen, and a part of the generated hydrogen is transmitted to the liquid hydrogen preparation and energy storage module, and the other part is transmitted to the hydrogen storage and power generation module; the liquid hydrogen preparation and energy storage module relies on hydrogen liquefaction technology to prepare liquid hydrogen and store it for subsequent external transportation, and the unliquefied hydrogen of the liquid hydrogen preparation and energy storage module is also transmitted to the hydrogen storage and power generation module; the hydrogen storage and power generation module stores hydrogen and generates stable electric energy through hydrogen at the same time, which is used to supplement the electric energy of the water electrolysis hydrogen production module and is used for domestic electricity.

[0007] Furthermore, the liquid hydrogen preparation and energy storage module includes a hydrogen buffer tank, a liquid nitrogen buffer tank, a cold head, and a liquid hydrogen storage tank; the hydrogen buffer tank is connected to the water electrolysis hydrogen production module and the hydrogen storage and power generation module, and is used to stabilize the pressure of the incoming hydrogen; the liquid nitrogen buffer tank is connected to the hydrogen buffer tank, and the liquid nitrogen buffer tank is filled with low-temperature liquid nitrogen, which is used to pre-cool the hydrogen; the cold head is connected to the liquid nitrogen buffer, and is used to cool the pre-cooled hydrogen to -247°C to reach the critical point of hydrogen phase change and liquefy the hydrogen into liquid hydrogen; the cold head is connected to the liquid hydrogen storage tank, and the liquid hydrogen flows into the liquid hydrogen storage tank for low-temperature storage.

[0008] Furthermore, the liquid hydrogen preparation and energy storage module also includes a liquefier and a vaporizer; the liquefier is arranged on the top of the liquid hydrogen storage tank and is connected, the vaporizer is connected to the liquefier, the hydrogen accumulated in the liquid hydrogen storage tank enters the liquefier to form a low-temperature gas-liquid mixed state, and then enters the vaporizer, the vaporizer is used to heat and reheat the gas-liquid mixed phase hydrogen to form room temperature hydrogen without liquid, and the vaporizer is simultaneously connected to the hydrogen storage and power generation module.

[0009] Furthermore, the liquid hydrogen storage tank is a Dewar flask.

[0010] Furthermore, the hydrogen storage and power generation module includes a medium- and low-pressure hydrogen storage tank and a hydrogen fuel cell. The medium- and low-pressure hydrogen storage tank is provided with two hydrogen inlets and one hydrogen outlet, which are respectively connected to the water electrolysis hydrogen production module and the vaporizer of the liquid hydrogen preparation and energy storage module. The hydrogen outlet of the medium- and low-pressure hydrogen storage tank is connected to the hydrogen fuel cell, and the hydrogen fuel cell generates electricity through hydrogen.

[0011] Furthermore, two groups of medium and low pressure hydrogen storage tanks are provided, and the hydrogen outlet of each group of medium and low pressure hydrogen storage tanks is connected to the hydrogen fuel cell. Both groups of medium and low pressure hydrogen storage tanks are provided with only one hydrogen inlet and are respectively connected to the water electrolysis hydrogen production module and the vaporizer of the liquid hydrogen preparation and energy storage module.

[0012] Furthermore, two groups of medium and low pressure hydrogen storage tanks are provided, and the hydrogen outlet of each group of medium and low pressure hydrogen storage tanks is connected to the hydrogen fuel cell. Both groups of medium and low pressure hydrogen storage tanks are provided with two hydrogen inlets and are connected to the water electrolysis hydrogen production module and the vaporizer of the liquid hydrogen preparation and energy storage module.

[0013] Furthermore, the photovoltaic power generation module and the water electrolysis hydrogen production module are operated at maximum power, and the hydrogen prepared by the water electrolysis hydrogen production module is preferentially transported to the liquid hydrogen preparation and energy storage module.

[0014] The above scheme of the present invention has the following beneficial effects:

[0015] The isolated microgrid liquid hydrogen preparation system based on hydrogen energy storage provided by the present invention can utilize natural energy to generate electricity and convert it into clean hydrogen energy through the arrangement of photovoltaic power generation modules, water electrolysis hydrogen production modules, liquid hydrogen preparation and energy storage modules, and hydrogen storage and power generation modules. At the same time, the hydrogen storage and power generation module can store and generate electricity for the redundant hydrogen generated by the water electrolysis hydrogen production module and the hydrogen regenerated by the liquid hydrogen preparation and energy storage module, thereby replenishing electric energy for the system. While ensuring full utilization of energy, the power quality of the system power grid can also be adjusted, thereby improving the reliability of the system.

[0016] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an overall schematic diagram of the present invention;

[0018] Figure 2 It is a schematic diagram of the liquid hydrogen preparation and energy storage module of the present invention;

[0019] Figure 3 Schematic diagram of the hydrogen storage and power generation module of the present invention.

[0020] [Description of Reference Numerals]

[0021] 10-photovoltaic power generation module; 20-water electrolysis hydrogen production module; 30-liquid hydrogen preparation and energy storage module; 31-hydrogen buffer tank; 32-liquid nitrogen buffer tank; 33-cold head; 34-liquid hydrogen storage tank; 35-liquefier; 36-vaporizer; 40-hydrogen storage and power generation module; 41-hydrogen fuel cell; 42-medium and low pressure hydrogen storage tanks. DETAILED DESCRIPTION

[0022] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0023] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0024] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure, and the illustrations only show the components related to the present disclosure rather than the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation may be changed at will, and the component layout type may also be more complicated. In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the aspects described can be practiced without these specific details.

[0025] like Figure 1As shown, an embodiment of the present invention provides an island-type microgrid liquid hydrogen preparation system based on hydrogen energy storage, including a photovoltaic power generation module 10, a water electrolysis hydrogen production module 20, a liquid hydrogen preparation and energy storage module 30, and a hydrogen storage and power generation module 40. Among them, the photovoltaic power generation module 10 uses daytime solar energy to generate unstable electric energy and transmits it to the water electrolysis hydrogen production module 20. The water electrolysis hydrogen production module 20 uses unstable electric energy to perform the water electrolysis preparation process of hydrogen, and a part (most of) the generated hydrogen is delivered to the liquid hydrogen preparation and energy storage module 30, and the other part (small part) is delivered to the hydrogen storage and power generation module 40. The liquid hydrogen preparation and energy storage module 30 relies on hydrogen liquefaction technology to prepare and store liquid hydrogen, and then transports the liquid hydrogen outward by means of liquid hydrogen transport trucks and the like. The hydrogen storage and power generation module 40 stores the hydrogen delivered by the water electrolysis hydrogen production module 20, and at the same time generates stable electric energy through hydrogen power generation equipment. This part of electric energy can be used to supplement the electric energy of the water electrolysis hydrogen production module 20, and can also be used for daily electricity. Of course, the electricity from the photovoltaic power generation module 10 can also be used for daily life. Therefore, this solution uses the photovoltaic power generation module 10 to supply unstable electricity to the entire system, and at the same time, the hydrogen storage and power generation module 40 provides stable supplementary electricity to adjust the power quality of the power grid of this system.

[0026] In this embodiment, the system is preferably arranged in an open area of ​​the wild Gobi. For the photovoltaic power generation module 10, the wild Gobi has strong light during the day, but the light intensity is unstable and uncontrollable. Among them, the photovoltaic power generation module 10 generates the most electricity when the light is strong at noon, and the power generation is zero when there is no light at night, so the electricity generated by the photovoltaic power generation module 10 is unstable. In this system, when the sunshine is large during the day, more electricity is generated, so the hydrogen production of the electrolysis water hydrogen production module 20 is larger, and the generated hydrogen can be stored in a hydrogen storage tank or prepared into liquid hydrogen for storage. In this embodiment, the liquid hydrogen preparation and energy storage module 30, and the hydrogen storage and power generation module 40 are specifically used to prepare and store liquid hydrogen, and hydrogen storage. Therefore, this system converts unstable electricity generated by photovoltaics into hydrogen energy for storage, and performs flexible power generation for the electricity demand of the family at different times, thereby meeting the family's electricity consumption while improving the quality of hydrogen production by electrolysis water. While the entire system realizes the island-type electricity demand, all clean energy is used, and liquid hydrogen can also be produced to generate economic benefits.

[0027] It should be noted that the photovoltaic power generation module 10 and the water electrolysis hydrogen production module 20 themselves adopt relatively common principles and equipment in the prior art, and their specific forms are not described in detail here. Those skilled in the art can make actual choices based on the prior art.

[0028] At the same time Figure 2As shown, the hydrogen prepared by the water electrolysis hydrogen production module 20 is transported to the liquid hydrogen preparation and energy storage module 30 through a thin hard tube, and first enters the hydrogen buffer tank 31, and the hydrogen pressure circulation in the pipeline is relatively large. The volume of the hydrogen buffer tank 31 is set to be relatively large, and it is mainly used to stabilize the pressure of the incoming hydrogen. After the hydrogen buffer tank 31 is depressurized, the hydrogen enters the liquid nitrogen buffer tank 32, and the liquid nitrogen buffer tank 32 mainly pre-cools the hydrogen. Among them, the liquid nitrogen buffer tank 32 is filled with -196°C liquid nitrogen, and the whole is in an extremely low temperature environment. Therefore, the external hydrogen is fully cooled by liquid nitrogen after entering, reaching -196°C. After the hydrogen comes out of the liquid nitrogen buffer tank 32, it is already in a low temperature state. After a section of hard tube wrapped by insulation cotton, it enters the cold head 33 (cold machine liquefier), and the -196°C hydrogen is cooled to -247°C again, reaching the critical point of hydrogen phase change, so that the hydrogen is liquefied into liquid hydrogen. In this hydrogen liquefaction process, equipment such as compressors, heat exchangers, cryogenic turbine expanders, normal-para hydrogen converters and throttle valves are also required, and the storage of liquid hydrogen requires the use of cryogenic liquid storage containers with good insulation properties, namely liquid hydrogen storage tanks 34.

[0029] Among them, liquid hydrogen naturally falls to the liquid hydrogen storage tank 34 by gravity. The liquid hydrogen storage tank 34 can maintain low-temperature storage for a long time and adopts vacuum insulation, which is mainly achieved by high vacuum in the interlayer space. The selection of the insulation structure of the liquid hydrogen storage tank 34 needs to consider many factors such as the storage tank volume, shape, evaporation rate, cost, etc., which is also the existing technology and will not be repeated here.

[0030] At the same time, in the entire process of the liquid hydrogen preparation and energy storage module 30, part of the hydrogen is not liquefied. Since the density of hydrogen is smaller than that of air, it will accumulate on the upper part of the liquid hydrogen storage tank 34. In this embodiment, a liquefier 35 is further arranged on the top of the liquid hydrogen storage tank 34, and the liquefier 35 is connected to the vaporizer 36 through a hard pipe. After the accumulated hydrogen enters the liquefier 35, it enters the vaporizer 36 through the hard pipe. At this time, the hydrogen is in a low-temperature gas-liquid mixed state. The vaporizer 36 heats and reheats the gas-liquid mixed phase hydrogen that is not completely liquefied to form room-temperature hydrogen without liquid, and then outputs the room-temperature hydrogen to the hydrogen storage and power generation module 40, thereby achieving full utilization of hydrogen, avoiding energy loss in the process of liquid hydrogen preparation, and further improving energy utilization.

[0031] It should be noted that the liquid hydrogen storage tank 34 in this embodiment can specifically adopt a Dewar flask, also known as a low-temperature thermos flask, for storing and supplying liquid products (such as liquid hydrogen, liquid nitrogen, liquid oxygen, liquid argon, etc.). The Dewar flask is provided with four switch valves, each of which is used to control the gas phase connection, liquid phase connection, exhaust connection and pressure circuit, etc. In addition, there are also a booster circuit, a liquid level gauge, a pressure gauge, a safety valve and a bursting disc lamp, etc. Since liquid hydrogen needs to be stored under deep cold conditions, it will vaporize at -247°C. When the liquid hydrogen Dewar flask is stored under normal conditions, even if the Dewar flask is insulated from the outside world, heat exchange will still occur with the environment, causing the internal temperature of the Dewar flask to slowly increase, and the stored liquid hydrogen is slowly converted into hydrogen, so that the pressure in the Dewar flask increases. When the pressure is too high, the Dewar flask will automatically release the pressure at intervals, and discharge the internal hydrogen (gas-liquid mixed phase) to the liquefier 35, and then perform the aforementioned process.

[0032] For the hydrogen storage and power generation module 40, since the system is set up in the wild Gobi, etc., the restrictions on conditions such as transportation and floor space are not considered, so a medium and low pressure hydrogen storage solution can be adopted to eliminate the technical problems caused by the "hydrogen embrittlement" phenomenon of the high-pressure hydrogen industry as much as possible. In addition, since the storage location is in the open suburbs, there is no particularly high requirement for the airtightness of the hydrogen storage container, so relatively cheap materials and structural forms can be used. At the same time, hydrogen can be used to generate electricity by means of fuel cells or combustion engines. The basic principle is the reverse reaction of water electrolysis, and hydrogen and oxygen are supplied to the cathode and anode respectively. After hydrogen diffuses outward through the cathode and reacts with the electrolyte, it releases electrons through the external load to reach the anode, thereby generating electricity. Specifically in this embodiment, power generation is achieved by a hydrogen fuel cell 41, and the hydrogen fuel cell 41 is mainly composed of a fuel cell stack and other parts of the fuel cell system (including multiple components such as an air compressor, a humidifier, a hydrogen circulation pump, and a hydrogen bottle). Among them, the fuel cell stack is the core part of the hydrogen fuel cell 41, including a catalyst, a proton exchange membrane, a gas diffusion layer, a bipolar plate, and various components such as a collector plate, a seal, and an end plate of other structural parts. It is worth mentioning that the hydrogen fuel cell 41 has the following advantages: no pollution, low noise, high efficiency, sufficient hydrogen production raw materials, etc.

[0033] Based on the above analysis, in this embodiment, the hydrogen storage and power generation module 40 adopts a medium and low pressure hydrogen storage tank 42 for storage. The two hydrogen inlets of the medium and low pressure hydrogen storage tank 42 are respectively connected to the water electrolysis hydrogen production module 20 and the vaporizer of the liquid hydrogen preparation and energy storage module 30, and the hydrogen outlet of the medium and low pressure hydrogen storage tank 42 is connected to the hydrogen fuel cell 41, and is also equipped with a plurality of switch valves for control. Based on the medium and low pressure storage method, the tank structure and pipeline can be set relatively simple. On the premise of arranging multiple medium and low pressure hydrogen storage tanks 42, the hydrogen flow branch can be switched by a multi-way valve or the like. Of course, even if the medium and low pressure hydrogen storage tank 42 has relatively low requirements for airtightness, it is still necessary to ensure that the sealing performance of the valve and the connection part is good to prevent hydrogen leakage as much as possible.

[0034] At the same time Figure 3 As shown, as a preferred embodiment, two groups of medium and low pressure hydrogen storage tanks 42 are provided in this embodiment, and the hydrogen outlets of each group of medium and low pressure hydrogen storage tanks 42 are connected to the hydrogen fuel cell 41. The two groups of medium and low pressure hydrogen storage tanks 42 can each be provided with only one hydrogen inlet connected to the water electrolysis hydrogen production module 20 and the vaporizer 36 of the liquid hydrogen preparation and energy storage module 30, respectively, or two hydrogen inlets can be provided and both are connected to the water electrolysis hydrogen production module 20 and the vaporizer of the liquid hydrogen preparation and energy storage module 30. Therefore, in the separately connected scheme, the two groups of medium and low pressure hydrogen storage tanks 42 can respectively collect the hydrogen delivered by the water electrolysis hydrogen production module 20 and the liquid hydrogen preparation and energy storage module 30, and then consider the amount of hydrogen delivered to the hydrogen fuel cell 41 based on the collection situation; in the fully connected scheme, the valve can be switched, and maintenance can be conveniently performed, thereby improving the redundancy of the system.

[0035] It should be noted that the power generated by the hydrogen storage and power generation module 40 through the hydrogen fuel cell 41 can be adaptively adjusted based on the photovoltaic power generation power, water electrolysis hydrogen production efficiency, and the capacity of each container in the system, and those skilled in the art can flexibly adjust based on the actual operation of the system. It should also be noted that the photovoltaic power generation module 10 and the water electrolysis hydrogen production module 20 are operated at maximum power to make the best use of light energy, equipment, and increase production. The hydrogen prepared is preferentially transported to the liquid hydrogen preparation and energy storage module 30 for liquid hydrogen preparation and timely transported by road, and redundant hydrogen and hydrogen produced in the liquid hydrogen storage tank 34 are prepared and then introduced into the medium and low pressure hydrogen storage tank 42 for storage and used for power generation. Compared with liquid storage, the gaseous storage method is a low-density, small-storage form, which is suitable for redundant hydrogen storage of this system.

[0036] Among them, the oxygen generated by electrolysis of water can be sent to other process modules, such as a sewage treatment module, to treat the sewage generated in the area where the system is located. Technical personnel in this field can also flexibly choose according to actual needs.

[0037] In this embodiment, the photovoltaic power generation module 10 may also be supplemented with or replaced by a wind power generation module, a hydropower generation module, etc., which all utilize natural energy to generate electricity and also have unstable characteristics.

[0038] In summary, the isolated microgrid liquid hydrogen preparation system based on hydrogen energy storage provided in this embodiment, through the arrangement of the photovoltaic power generation module 10, the water electrolysis hydrogen production module 20, the liquid hydrogen preparation and energy storage module 30 and the hydrogen storage and power generation module 40, can utilize natural energy to generate electricity and convert it into clean hydrogen energy. At the same time, the hydrogen storage and power generation module 40 can store and generate electricity for the redundant hydrogen generated by the water electrolysis hydrogen production module 20 and the hydrogen regenerated by the liquid hydrogen preparation and energy storage module 3, thereby replenishing electric energy for the system. While ensuring full utilization of energy, it can also adjust the power quality of the system power grid, thereby improving the reliability of the system.

[0039] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. An island-type microgrid liquid hydrogen production system based on hydrogen energy storage, characterized in that: It includes photovoltaic power generation module, water electrolysis hydrogen production module, liquid hydrogen preparation and energy storage module, and hydrogen storage and power generation module; The photovoltaic power generation module uses daytime solar energy to generate unstable electric energy, and transmits it to the water electrolysis hydrogen production module, and is used for domestic electricity; the water electrolysis hydrogen production module uses electric energy to carry out a water electrolysis preparation process for hydrogen, and a part of the generated hydrogen is transmitted to the liquid hydrogen preparation and energy storage module, and the other part is transmitted to the hydrogen storage and power generation module; the liquid hydrogen preparation and energy storage module relies on hydrogen liquefaction technology to prepare liquid hydrogen and store it for subsequent external transportation, and the unliquefied hydrogen of the liquid hydrogen preparation and energy storage module is also transmitted to the hydrogen storage and power generation module; the hydrogen storage and power generation module stores hydrogen and generates stable electric energy through hydrogen at the same time, which is used to supplement the electric energy of the water electrolysis hydrogen production module and is used for domestic electricity.

2. According to claim 1, an island-type microgrid liquid hydrogen production system based on hydrogen energy storage is characterized in that: The liquid hydrogen preparation and energy storage module includes a hydrogen buffer tank, a liquid nitrogen buffer tank, a cold head, and a liquid hydrogen storage tank; the hydrogen buffer tank is connected to the water electrolysis hydrogen production module and the hydrogen storage and power generation module, and is used to stabilize the pressure of the incoming hydrogen; the liquid nitrogen buffer tank is connected to the hydrogen buffer tank, and the liquid nitrogen buffer tank is filled with low-temperature liquid nitrogen, which is used to pre-cool the hydrogen; the cold head is connected to the liquid nitrogen buffer, and is used to cool the pre-cooled hydrogen to -247°C to reach the critical point of hydrogen phase change and liquefy the hydrogen into liquid hydrogen; the cold head is connected to the liquid hydrogen storage tank, and the liquid hydrogen flows into the liquid hydrogen storage tank for low-temperature storage.

3. The isolated microgrid liquid hydrogen production system based on hydrogen energy storage according to claim 2 is characterized in that: The liquid hydrogen preparation and energy storage module also includes a liquefier and a vaporizer; the liquefier is arranged on the top of the liquid hydrogen storage tank and is connected, the vaporizer is connected to the liquefier, the hydrogen accumulated in the liquid hydrogen storage tank enters the liquefier to form a low-temperature gas-liquid mixed state, and then enters the vaporizer, the vaporizer is used to heat and reheat the gas-liquid mixed phase hydrogen to form room-temperature hydrogen without liquid, and the vaporizer is simultaneously connected to the hydrogen storage and power generation module.

4. The isolated microgrid liquid hydrogen production system based on hydrogen energy storage according to claim 2 or 3, characterized in that: The liquid hydrogen storage tank is a Dewar flask.

5. The isolated microgrid liquid hydrogen production system based on hydrogen energy storage according to claim 3 is characterized in that: The hydrogen storage and power generation module includes a medium- and low-pressure hydrogen storage tank and a hydrogen fuel cell. The medium- and low-pressure hydrogen storage tank is provided with two hydrogen inlets and one hydrogen outlet, which are respectively connected to the water electrolysis hydrogen production module and the vaporizer of the liquid hydrogen preparation and energy storage module. The hydrogen outlet of the medium- and low-pressure hydrogen storage tank is connected to the hydrogen fuel cell, and the hydrogen fuel cell generates electricity through hydrogen.

6. The isolated microgrid liquid hydrogen production system based on hydrogen energy storage according to claim 5 is characterized in that: The medium and low pressure hydrogen storage tanks are provided in two groups, and the hydrogen outlet of each group of the medium and low pressure hydrogen storage tanks is connected to the hydrogen fuel cell. The two groups of the medium and low pressure hydrogen storage tanks are provided with only one hydrogen inlet and are respectively connected to the water electrolysis hydrogen production module and the vaporizer of the liquid hydrogen preparation and energy storage module.

7. The isolated microgrid liquid hydrogen production system based on hydrogen energy storage according to claim 5 is characterized in that: The medium and low pressure hydrogen storage tanks are provided in two groups, and the hydrogen outlet of each group of the medium and low pressure hydrogen storage tanks is connected to the hydrogen fuel cell. The two groups of the medium and low pressure hydrogen storage tanks are provided with two hydrogen inlets and are connected to the water electrolysis hydrogen production module and the vaporizer of the liquid hydrogen preparation and energy storage module.

8. An islanded microgrid liquid hydrogen production system based on hydrogen energy storage according to any one of claims 1 to 7, characterized in that: The photovoltaic power generation module and the water electrolysis hydrogen production module are operated at maximum power, and the hydrogen produced by the water electrolysis hydrogen production module is preferentially transported to the liquid hydrogen preparation and energy storage module.

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