A multi-stack PEM water electrolysis hydrogen production system and control method

Abstract

The present invention discloses a multi-stack PEM water electrolysis hydrogen production system and a control method. The hydrogen production system includes an electrolytic hydrogen production device and a power supply device, the power supply device is configured to provide output power of varying magnitude, the electrolytic hydrogen production device includes a plurality of electrolyzer units, and the hydrogen production system includes an access and allocation device, the access and allocation device can connect a plurality of electrolyzer units in parallel and / or in series and connect the power supply device, the access and allocation device is configured to: select a plurality of electrolyzer units for series connection, obtain the best series connection mode in which the total power consumption of a plurality of electrolyzers in the series connection state is most matched with the output power of the power supply device; and in the best series connection mode, select one or more electrolyzer units for parallel connection, so that the total power consumption of the electrolyzer is further matched with the output power of the power supply device. The present invention can obtain a power distribution scheme with small power loss, and the power regulation is simple and rapid.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis hydrogen production, and in particular to a multi-stack PEM water electrolysis hydrogen production system and a control method. Background Art

[0002] Hydrogen energy is an ideal energy source as a clean, pollution-free, renewable and sustainable energy source. At present, the main source of hydrogen energy is industrial by-product hydrogen. With the adjustment and transformation of the energy structure, the amount of by-product hydrogen will gradually decrease. At present, solar energy, wind energy, biomass energy, hydropower and other abandoned power energy sources are gradually receiving attention. Converting these unstable energy sources into hydrogen energy that can be stored and transported through water electrolysis is a good energy conversion solution.

[0003] However, the use of these unstable energy sources for water electrolysis has the disadvantages of large fluctuations in conversion efficiency and low overall conversion efficiency. In order to solve this problem, the industry has developed a power optimization allocation scheme for dynamic power distribution. The existing power optimization allocation schemes include a chain allocation scheme, that is, each level of electrolytic cells is put into operation step by step, and the next level of electrolytic cells is started after the previous level of electrolytic cells reaches the rated input power, and so on. The chain allocation scheme can improve the conversion efficiency to a certain extent, but the allocation method is still relatively rough and there is still a large power loss. There are also existing technologies that use a variety of optimization algorithm models to obtain the optimal power allocation scheme, but there are problems such as complex models, large amount of calculation, long calculation time, and cumbersome optimization and adjustment process.

[0004] Based on this, it is necessary to propose a technical solution to overcome the shortcomings of the existing technology. Summary of the invention

[0005] In order to overcome the defects of the prior art, the present invention proposes a multi-stack PEM water electrolysis hydrogen production system and a control method, which can obtain a power distribution scheme with extremely small power loss, and the power distribution scheme is easy and quick to adjust.

[0006] The present invention is implemented through the following technical scheme: a multi-stack PEM water electrolysis hydrogen production system, comprising an electrolysis hydrogen production device and a power supply device for providing electrical energy to the electrolysis hydrogen production device, the power supply device being configured to provide output power of varying magnitude, wherein the electrolysis hydrogen production device comprises a plurality of electrolyzer units, and the multi-stack PEM water electrolysis hydrogen production system further comprises an access and allocation device, the access and allocation device being configured to be able to connect a plurality of the plurality of electrolyzer units in parallel and / or in series and connect the power supply device, wherein the access and allocation device is configured to: select a plurality of electrolyzer units for series connection, obtain an optimal series connection mode in which the total power consumption of the plurality of electrolyzers in the series connection state is most matched with the output power of the power supply device; and, in the optimal series connection mode, select one or more electrolyzer units for parallel connection, so that the total power consumption of the electrolyzer is further matched with the output power of the power supply device.

[0007] As a further improved technical solution of the present application, the power supply device is one or more of a photovoltaic power generation device, a wind power generation device, a hydropower generation device and a biomass power generation device.

[0008] As a further improved technical solution of the present application, the multi-stack PEM water electrolysis hydrogen production system also includes a statistical device, which is configured to count the distribution of the output power size of the power supply device within a preset time period, and the total number of electrolytic cell units included in the electrolytic hydrogen production device and the power level of each electrolytic cell unit are matched and set according to the distribution of the output power size of the power supply device counted by the statistical device.

[0009] As a further improved technical solution of the present application, the multi-stack PEM water electrolysis hydrogen production system also includes a power storage device connected to the power supply device, and the power storage device is configured to store unconsumed electric energy generated by the power supply device when the hydrogen electrolysis device is not working and / or the total power consumption of the hydrogen electrolysis device is less than that of the power supply device. The power storage device is connected to the hydrogen electrolysis device so as to be suitable for providing electric energy to the hydrogen electrolysis device together with the power supply device.

[0010] As a further improved technical solution of the present application, the multi-stack PEM water electrolysis hydrogen production system includes a hydrothermal management device, which is used to provide an electrolyte with a temperature suitable for the water electrolysis reaction to the electrolysis hydrogen production device.

[0011] As a further improved technical solution of the present application, at least some of the multiple electrolytic cell units can be connected to the system by the access and deployment device in a manner of switching between parallel and series.

[0012] As a further improved technical solution of the present application, the access and coordination device includes a double-throw switch, which has two contacts that can be switched online. The series and parallel modes of the electrolytic cell units are switched by switching the double-throw switch to contact different contacts.

[0013] The present invention is also implemented through the following technical solutions: a control method for a multi-stack PEM water electrolysis hydrogen production system, wherein the hydrogen production system includes an electrolysis hydrogen production device, a power supply device and an access and allocation device, the power supply device is configured to provide the electrolysis hydrogen production device with output power of varying magnitudes, the electrolysis hydrogen production device includes a plurality of electrolyzer units with different power levels, and the access and allocation device is configured to be able to connect a plurality of the plurality of electrolyzer units in parallel and / or in series and connect the power supply device; wherein the control method includes:

[0014] Selecting multiple electrolytic cell units of appropriate number and power level for series connection, and obtaining an optimal series connection mode that best matches the total power consumption of the multiple electrolytic cells in the series connection state with the output power of the power supply device;

[0015] In the optimal series connection mode, multiple electrolytic cell units of appropriate number and power level are selected for parallel connection, so that the total power consumption of the electrolytic cell is further matched with the output power of the power supply device.

[0016] As a further improved technical solution of the present application, within a preset time period, the number of times the electrolytic cell units are adjusted in parallel is greater than the number of times the electrolytic cell units are adjusted in series.

[0017] As a further improved technical solution of the present application, the control method includes: dividing a plurality of power intervals according to the output power of the power supply device;

[0018] The output power of the power supply device is detected, and when it is detected that the output power changes across the power interval twice in succession, the number of the electrolytic cell units connected in series is adjusted.

[0019] As a further improved technical solution of the present application, when it is detected that the output power changes from a low power range to a high power range for two consecutive times, the number of the electrolytic cell units connected in series is increased; when it is detected that the output power changes from a high power range to a low power range for two consecutive times, the number of the electrolytic cell units connected in series is reduced.

[0020] As a further improved technical solution of the present application, the control method includes dividing at least one power interval into a plurality of power sub-intervals according to the magnitude of the output power;

[0021] Detecting the output power of the power supply device, and when detecting that the output power of two consecutive times changes across the power sub-interval, adjusting the number of the electrolytic cell units connected in parallel;

[0022] Among them, when it is detected that the output power changes from a low-power sub-interval to a high-power sub-interval twice adjacently, the number of parallel-connected electrolytic cells is increased; when it is detected that the output power changes from a high-power sub-interval to a low-power sub-interval twice adjacently, the number of parallel-connected electrolytic cell units is reduced.

[0023] The multi-stack PEM water electrolysis hydrogen production system and control method provided by the present invention selects multiple electrolyzer units for series connection to obtain an optimal series connection mode in which the total power consumption of the multiple electrolyzers in the series connection state is most matched with the output power of the power supply device; and under the optimal series connection mode, one or more electrolyzer units are selected for parallel connection to further match the total power consumption of the electrolyzer with the output power of the power supply device; the power distribution scheme is simple and rapid to adjust, can quickly match the fluctuating power consumption supply, and has low power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a block diagram of an embodiment of a multi-stack PEM water electrolysis hydrogen production system of the present invention.

[0025] Figure 2 It is a connection diagram of an embodiment of a multi-stack PEM water electrolysis hydrogen production system of the present invention.

[0026] Figure 3 It is a curve diagram of output power variation and electrolytic cell unit adjustment of the multi-stack PEM water electrolysis hydrogen production system of the present invention.

[0027] Figure 4 It is a circuit diagram of a multi-stack PEM water electrolysis hydrogen production system of the present invention.

[0028] Figure 5 It is another circuit schematic diagram of the multi-stack PEM water electrolysis hydrogen production system of the present invention.

[0029] Figure 6 This is another circuit diagram of the multi-stack PEM water electrolysis hydrogen production system of the present invention.

[0030] The figures are marked as follows: 1-power supply device; 11-power storage device; 2-electrolysis hydrogen production device; 21-electrolyzer unit; 3-access and deployment device; 4-gas storage device; 5-water thermal management device. DETAILED DESCRIPTION

[0031] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0032] The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] See also Figures 1 to 3 As shown, the present application provides a multi-stack PEM water electrolysis hydrogen production system and a control method, which are suitable for application in fluctuating power output. An embodiment of the multi-stack PEM water electrolysis hydrogen production system includes an electrolysis hydrogen production device 2 and a power supply device 1 for providing electrical energy to the electrolysis hydrogen production device 2, wherein the power supply device 1 is configured to provide output power of varying magnitude, wherein the electrolysis hydrogen production device 2 includes a plurality of electrolyzer units 21, and the multi-stack PEM water electrolysis hydrogen production system further includes an access and adjustment device 3, wherein the access and adjustment device 3 is configured to be able to connect a plurality of the plurality of electrolyzer units 21 in parallel and / or in series and connect the power supply device 1. The access and adjustment device 3 is configured to: select a plurality of electrolyzer units 21 for series connection, and obtain the best series connection mode in which the total power consumption of the plurality of electrolyzers in the series connection state is most matched with the output power of the power supply device 1; and, in the best series connection mode, select one or more electrolyzer units 21 for parallel connection, so that the total power consumption of the electrolyzer is further matched with the output power of the power supply device 1.

[0034] In one embodiment, the power supply device 1 is one or more of a photovoltaic power generation device, a wind power generation device, a hydroelectric power generation device, and a biomass power generation device. The photovoltaic power generation device, the wind power generation device, the hydroelectric power generation device, and the biomass power generation device are energy forms with large power fluctuations, which are greatly affected by natural conditions such as weather, season, and region. They are often used as abandoned electricity and have low utilization rates. The hydrogen production system provided in the present application can be adapted to this type of energy and improve the utilization efficiency of this type of energy. In one embodiment, the power supply device 1 can also be connected to the grid electricity so that when the abandoned electricity cannot be used, it can work using the grid electricity provided by the power grid.

[0035] In this embodiment, the total number of electrolyzer units 21 included in the electrolytic hydrogen production device 2 and the power level of each electrolyzer unit 21 are matched and set according to the distribution of the output power size of the corresponding power supply device 1 to ensure the utilization rate of the electrolyzer unit 21. Taking photovoltaic energy as an example, if the hydrogen production system described in this application is configured in an area with relatively abundant photovoltaic energy, such as Tibet in my country, the number of electrolyzer units 21 can be relatively large, and the electrolyzer units 21 can be configured to have a relatively large rated power; if the hydrogen production system described in this application is configured in an area with relatively poor photovoltaic energy, such as Sichuan in my country, the number of electrolyzer units 21 can be relatively small, and the electrolyzer units 21 can be configured to have a relatively small rated power. That is, in this embodiment, the multi-stack PEM water electrolysis hydrogen production system also includes a statistical device, which is configured to count the distribution of the output power size of the power supply device 1 within a preset time period, and the total number of electrolytic cell units 21 included in the electrolytic hydrogen production device 2 and the power level of each electrolytic cell unit 21 are matched and set according to the distribution of the output power size of the power supply device 1 counted by the statistical device.

[0036] See also Figure 2 As shown, the multi-stack PEM water electrolysis hydrogen production system also includes a power storage device 11 connected to the power supply device 1, and the power storage device 11 is configured to store the unconsumed electric energy generated by the power supply device 1 when the electrolysis hydrogen production device 2 is not working and / or the total power consumption of the electrolysis hydrogen production device 2 is less than the power supply device 1. Further, the power storage device 11 is connected to the electrolysis hydrogen production device 2 so as to be suitable for providing electric energy to the electrolysis hydrogen production device 2 together with the power supply device 1. In one embodiment, the power supply device 1 supplies power to the electrolysis hydrogen production device 2 in a direct coupling manner, that is, the electric energy of the power supply device 1 is not converted or stored to reduce the energy loss during the conversion and storage process. The electric energy generated by the power supply device 1 is converted and stored only when the electrolysis hydrogen production device 2 is not working and / or the total power consumption of the electrolysis hydrogen production device 2 is less than the power supply device 1.

[0037] Please continue reading Figure 2 As shown, the multi-stack PEM water electrolysis hydrogen production system includes a water thermal management device 5, which is used to provide the electrolytic hydrogen production device 2 with an electrolyte having a temperature suitable for the water electrolysis reaction. In this embodiment, water and heat are supplied in the same way, and an excessive amount of water at an appropriate temperature is supplied to ensure the reaction temperature while satisfying the hydrogen production reaction. That is, in the process of hydrogen production by electrolysis in the PEM electrolyzer, water has two functions. One is to serve as a hydrogen production raw material for 2H 2 O=2H 2 +O 2The first is to conduct electrochemical reactions, and the second is to serve as a coolant supplied in a thermal management cycle to ensure that the electrochemical reaction is in a suitable temperature range. That is, in one embodiment of the present application, the water for the electrolysis reaction is not isolated from the water for heat transfer, and excess water is introduced directly into the PEM electrolyzer as both a reactant and a coolant, and its structure is simple. The gas generated by the reaction is stored in a gas storage device 4. The gas storage device 4 includes a high-pressure hydrogen storage tank for gaseous hydrogen storage, a metal hydrogen storage tank for solid hydrogen storage, and an oxygen storage tank for storing the generated oxygen.

[0038] See also Figures 4 to 6 As shown, in some embodiments, the access and allocation device 3 includes a plurality of switching switches, through which one or more electrolytic cell units 21 are connected or not connected to the system, and connected in series or in parallel. Figure 4 As shown, in one embodiment, each parallel branch is provided with a switch, such as K1, K2, K3, and the electrolytic cell unit 21 on the corresponding branch can be connected to the series branch in parallel by switching the switches K1, K2, K3 on and off. For this circuit, the electrolytic cell unit 21 on the parallel branch can only be connected to the system in parallel or not connected to the system, and cannot be multiplexed in parallel or series, so that the utilization rate of the electrolytic cell unit 21 is not high.

[0039] In another embodiment, if Figure 5 As shown, at least some of the multiple electrolytic cell units 21 can be connected to the system by the access and deployment device 3 in a manner of switching between parallel and series connection. Specifically, Figure 5 The three parallel branches are used as an example, and the switching switch includes switches K11, K21, K31 arranged on the main road, switches K13, K23, K33 arranged on the parallel branches, and bypass switches K12, K22, K32 arranged between the parallel branches and the main road. When parallel access is required, switches K11, K21, K31 and switches K13, K23, K33 are turned on, and bypass switches K12, K22, K32 are turned off; when series access is required, switches K11, K21, K31 and switches K13, K23, K33 are turned off, and bypass switches K12, K22, K32 are turned on; when access to the system is not required, switches K11, K21, K31 are turned on, and switches K13, K23, K33 and bypass switches K12, K22, K32 are turned off. It can be understood that if only one or two branches need to be connected, it is sufficient to control the corresponding switches to be on or off.

[0040] In another embodiment, if Figure 6As shown, the access and allocation device 3 includes a double-throw switch, which has two contacts that can be switched on. The double-throw switch switches different contacts to switch the series and parallel modes of the electrolytic cell unit 21. In this embodiment, switches K13, K23, and K33 are single-throw switches, and switches K11, K21, and K31 are double-throw switches. By setting a double-throw switch, the number of switches can be reduced, and the series and parallel switching can also be conveniently and quickly realized. In this embodiment, when connected in parallel, switches K13, K23, and K33 are turned on, and double-throw switches K11, K21, and K31 connect the contacts on the main road; when connected in series, switches K13, K23, and K33 are turned off, and double-throw switches K11, K21, and K31 connect the contacts on the bypass branch. In one embodiment, the access or removal of the series number and the parallel number can be realized by a relay, that is, the switch is a relay switch. Relay switches have the advantages of fast response speed and easy control. Preferably, the contacts on the main circuit of the double-throw switches K11, K21, and K31 are normally closed contacts, and the contacts on the bypass branch are normally open contacts, so as to be suitable for parallel adjustment frequency, reduce the action of the relay, and improve the circuit stability of the system.

[0041] The present application also provides a control method for a multi-stack PEM water electrolysis hydrogen production system, wherein the hydrogen production system comprises an electrolysis hydrogen production device 2, a power supply device 1 and an access and allocation device 3, wherein the power supply device 1 is configured to provide the electrolysis hydrogen production device 2 with output power of varying magnitudes, the electrolysis hydrogen production device 2 comprises a plurality of electrolyzer units 21 with different power levels, and the access and allocation device 3 is configured to be able to connect a plurality of the plurality of electrolyzer units 21 in parallel and / or in series and connect the power supply device 1; wherein the control method comprises:

[0042] Select multiple electrolytic cell units 21 of appropriate number and power level for series connection, and obtain the best series connection mode that best matches the total power consumption of the multiple electrolytic cells in the series connection state with the output power of the power supply device 1;

[0043] In the optimal series connection mode, multiple electrolytic cell units 21 of appropriate number and power level are selected for parallel connection, so that the total power consumption of the electrolytic cell is further matched with the output power of the power supply device 1.

[0044] The change in the number of electrolyzer units 21 connected in series has a relatively slow effect on the change in power consumption, making it difficult for the total power consumption of the electrolyzer to keep up with the change in the output power of the power supply device 1. Therefore, the number of series connections is adjusted first to achieve preliminary adjustment, so that the total power of the electrolyzers participating in the reaction is first close to the output power of the power supply device 1 as a whole. For more subtle power fluctuations, fast and precise adjustment is achieved by adjusting the number of parallel electrolyzer units 21, so that the total power of the electrolyzers participating in the reaction can be further matched with the output power change. This solution can reduce the number of series adjustments, reduce the impact on the series circuit, and the circuit reliability of the electrolytic hydrogen production device 2 is better.

[0045] See also Figure 3 As shown, within the preset time period t, the number of times the electrolytic cell units 21 are adjusted in parallel is greater than the number of times the electrolytic cell units 21 are adjusted in series. Figure 3 Taking the change of photovoltaic energy over time in a day as an example, for example, from morning to night, the output power change achieved by photovoltaic energy presents a change curve as shown in the figure, which first increases and then decreases. The change in the number of electrolytic cell units 21 connected to the multi-stack PEM water electrolysis hydrogen production system provided in the present application is shown by the series number change line and the parallel number change line in the figure.

[0046] Furthermore, the control method comprises: dividing the output power of the power supply device 1 into several power intervals, such as Figure 3 The two dotted lines L1 in the figure divide the three power intervals; the output power of the power supply device 1 is detected, and when it is detected that the output power changes across the power interval twice, the number of the series connection of the electrolytic cell units 21 is adjusted. That is, when the power change is large so that the current number of series connection of the electrolytic cell units 21 is not enough to match the output power, the number of series connection of the electrolytic cell units 21 is adjusted. Specifically, when it is detected that the output power changes from the low power interval to the high power interval twice, the number of series connection of the electrolytic cell units 21 is increased; when it is detected that the output power changes from the high power interval to the low power interval twice, the number of series connection of the electrolytic cell units 21 is reduced.

[0047] Furthermore, the control method includes dividing at least one power interval into a plurality of power sub-intervals according to the magnitude of the output power, such as Figure 3The four short dashed lines between the two dashed lines L1 in the figure divide the power interval between the two dashed lines L1 into five power sub-intervals; the output power of the power supply device 1 is detected, and when it is detected that the output power changes across the power sub-interval twice adjacently, the number of parallel electrolytic cell units 21 is adjusted; wherein, when it is detected that the output power changes from a small power sub-interval to a large power sub-interval twice adjacently, the number of parallel electrolytic cell units 21 is increased; when it is detected that the output power changes from a large power sub-interval to a small power sub-interval twice adjacently, the number of parallel electrolytic cell units 21 is reduced.

[0048] From the above description of specific embodiments, it can be seen that the multi-stack PEM water electrolysis hydrogen production system and control method provided by the present invention selects multiple electrolyzer units 21 for series connection to obtain the optimal series connection mode in which the total power consumption of the multiple electrolyzers in the series state is most matched with the output power of the power supply device; and in the optimal series connection mode, one or more electrolyzer units 21 are selected for parallel connection to further match the total power consumption of the electrolyzer with the output power of the power supply device; the power allocation scheme is simple and rapid to adjust, can quickly match the fluctuating power consumption supply, and has little power loss.

[0049] The present invention is described by several specific embodiments, and it should be understood by those skilled in the art that various changes and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to the present invention for specific situations or specific circumstances without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all implementation methods falling within the scope of the claims of the present invention.

Claims

1. A multi-stack PEM water electrolysis hydrogen production system, comprising an electrolysis hydrogen production device and a power supply device for providing electrical energy to the electrolysis hydrogen production device, wherein the power supply device is configured to provide output power of varying magnitudes, It is characterized in that The electrolysis hydrogen production device includes a plurality of electrolyzer units with different power levels, and the multi-stack PEM water electrolysis hydrogen production system also includes an access and allocation device, which is configured to connect a plurality of the plurality of electrolyzer units in parallel and / or series and connect them to the power supply device, wherein the access and allocation device is configured to: select a plurality of electrolyzer units for series connection to obtain an optimal series connection mode in which the total power consumption of the plurality of electrolyzers in the series state is most matched with the output power of the power supply device; and, in the optimal series connection mode, select one or more electrolyzer units for parallel connection to further match the total power consumption of the electrolyzer with the output power of the power supply device; wherein at least some of the plurality of electrolyzer units can be connected to the system by the access and allocation device in a manner of switching between parallel and series connection.

2. The multi-stack PEM water electrolysis hydrogen production system as claimed in claim 1, It is characterized in that The power supply device is one or more of a photovoltaic power generation device, a wind power generation device, a hydropower generation device and a biomass power generation device.

3. The multi-stack PEM water electrolysis hydrogen production system as claimed in claim 2, It is characterized in that The multi-stack PEM water electrolysis hydrogen production system also includes a statistical device, which is configured to count the distribution of the output power size of the power supply device within a preset time period. The total number of electrolytic cell units included in the electrolytic hydrogen production device and the power level of each electrolytic cell unit are matched and set according to the distribution of the output power size of the power supply device counted by the statistical device.

4. The multi-stack PEM water electrolysis hydrogen production system as claimed in claim 1, It is characterized in that The multi-stack PEM water electrolysis hydrogen production system also includes a power storage device connected to the power supply device, and the power storage device is configured to store unconsumed electric energy generated by the power supply device when the hydrogen electrolysis device is not working and / or the total power consumption of the hydrogen electrolysis device is less than that of the power supply device. The power storage device is connected to the hydrogen electrolysis device so as to be suitable for providing electric energy to the hydrogen electrolysis device together with the power supply device.

5. The multi-stack PEM water electrolysis hydrogen production system as claimed in claim 1, It is characterized in that The multi-stack PEM water electrolysis hydrogen production system includes a water thermal management device, which is used to provide an electrolyte with a temperature suitable for the water electrolysis reaction to the hydrogen production device.

6. The multi-stack PEM water electrolysis hydrogen production system as claimed in claim 1, It is characterized in that The access and adjustment device includes a double-throw switch having two contacts that can be switched on. The series and parallel modes of the electrolytic cell units are switched by switching the double-throw switch to contact different contacts.

7. A control method for a multi-stack PEM water electrolysis hydrogen production system, It is characterized in that The hydrogen production system comprises an electrolytic hydrogen production device, a power supply device and an access and allocation device, wherein the power supply device is configured to provide the electrolytic hydrogen production device with output power of varying magnitudes, the electrolytic hydrogen production device comprises a plurality of electrolytic cell units with different power levels, and the access and allocation device is configured to be able to connect a plurality of the plurality of electrolytic cell units in parallel and / or in series and connect the power supply device; wherein the control method comprises: Selecting multiple electrolytic cell units of appropriate number and power level for series connection, and obtaining an optimal series connection mode that best matches the total power consumption of the multiple electrolytic cells in the series connection state with the output power of the power supply device; In the optimal series connection mode, multiple electrolytic cell units of appropriate number and power level are selected for parallel connection, so that the total power consumption of the electrolytic cell is further matched with the output power of the power supply device; Among them, at least some of the multiple electrolytic cell units can be connected to the system by the access and deployment device in a manner of switching between parallel and series connection.

8. The control method of the multi-stack PEM water electrolysis hydrogen production system according to claim 7, It is characterized in that Within a preset time period, the number of times the electrolytic cell units are adjusted in parallel is greater than the number of times the electrolytic cell units are adjusted in series.

9. The control method of the multi-stack PEM water electrolysis hydrogen production system as claimed in claim 7, It is characterized in that The control method comprises: dividing a plurality of power intervals according to the output power of the power supply device; The output power of the power supply device is detected, and when it is detected that the output power changes across the power interval twice in succession, the number of the electrolytic cell units connected in series is adjusted.

10. The control method of the multi-stack PEM water electrolysis hydrogen production system according to claim 9, It is characterized in that When it is detected that the output power changes from a low power interval to a high power interval for two consecutive times, the number of the series-connected electrolytic cell units is increased; when it is detected that the output power changes from a high power interval to a low power interval for two consecutive times, the number of the series-connected electrolytic cell units is reduced.

11. The control method of the multi-stack PEM water electrolysis hydrogen production system according to claim 9, It is characterized in that The control method includes dividing at least one power interval into a plurality of power sub-intervals according to the magnitude of the output power; Detecting the output power of the power supply device, and when detecting that the output power of two consecutive times changes across the power sub-interval, adjusting the number of the electrolytic cell units connected in parallel; Among them, when it is detected that the output power changes from a low-power sub-interval to a high-power sub-interval twice adjacently, the number of parallel-connected electrolytic cell units is increased; when it is detected that the output power changes from a high-power sub-interval to a low-power sub-interval twice adjacently, the number of parallel-connected electrolytic cell units is reduced.

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