Direct current off-grid hydrogen production system, control method and device thereof, and medium

Abstract

The present application relates to the technical field of hydrogen production, and specifically provides a direct-current off-grid hydrogen production system, a control method, equipment and a medium, aiming to effectively consume fluctuating power generated by renewable energy to produce hydrogen.The system provided by the present application comprises renewable energy power generation equipment, energy storage equipment and water electrolysis hydrogen production equipment connected to a direct-current bus through respective equipment direct-current ports.The renewable energy power generation equipment comprises a renewable energy power generation device and a plurality of first DC / DC modules, the energy storage equipment comprises an energy storage device and a plurality of second DC / DC modules, and the water electrolysis hydrogen production equipment comprises a water electrolysis hydrogen production device and a plurality of third DC / DC modules.The water electrolysis hydrogen production device comprises an alkaline water electrolysis hydrogen production device and a proton exchange membrane water electrolysis hydrogen production device.The alkaline water electrolysis hydrogen production device is configured to consume low-frequency pulsating power to produce hydrogen, and the proton exchange membrane water electrolysis hydrogen production device is configured to consume high-frequency pulsating power to produce hydrogen.Through the above system, fluctuating power can be effectively consumed to produce hydrogen.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology, specifically to a DC off-grid hydrogen production system based on renewable energy, and its control method, equipment, and medium. Background Technology

[0002] Since the beginning of the 21st century, the world has faced increasingly severe energy security and environmental protection challenges. Renewable energy sources such as wind and solar power have become an important component of energy strategies and the core of energy transition. To store and convert unstable renewable energy sources such as wind and solar power, it is now common practice to generate electricity from renewable energy sources and then use that electricity to produce hydrogen, thereby achieving renewable energy storage and conversion.

[0003] Existing large-scale hydrogen production systems are often grid-connected, and fluctuations in renewable energy generation after grid connection can affect the security and stability of the power grid. Although off-grid DC hydrogen production systems can now be used, existing off-grid DC hydrogen production systems cannot efficiently absorb the fluctuating electricity generated by renewable energy sources. Furthermore, they require a large number of energy storage devices to release electricity when renewable energy generation is insufficient, thereby supporting the voltage of the DC bus and enabling the off-grid DC hydrogen production system to operate normally.

[0004] Accordingly, a new solution is needed in this field to address the aforementioned problems. Summary of the Invention

[0005] In order to overcome the above-mentioned defects, this invention is proposed to solve or at least partially solve the technical problem of the inability to effectively utilize the electricity generated by renewable energy power generation equipment for water electrolysis to produce hydrogen.

[0006] In a first aspect, a DC off-grid hydrogen production system based on renewable energy is provided, the system comprising renewable energy power generation equipment, energy storage equipment and water electrolysis hydrogen production equipment, which are respectively connected to a DC bus through their respective equipment DC ports;

[0007] The renewable energy power generation equipment includes a renewable energy power generation device and multiple first DC / DC modules. The renewable energy power generation device is connected in parallel with the first DC side of each first DC / DC module, and the second DC side of each first DC / DC module is connected in series to form the equipment DC port of the renewable energy power generation equipment.

[0008] The energy storage device includes an energy storage unit and multiple second DC / DC modules. The energy storage unit is connected in parallel with the first DC side of each second DC / DC module, and the second DC sides of each second DC / DC module are connected in series to form the device DC port of the energy storage device.

[0009] The water electrolysis hydrogen production equipment includes a water electrolysis hydrogen production unit and multiple third DC / DC modules. The water electrolysis hydrogen production unit is connected in parallel with the first DC side of each third DC / DC module, and the second DC side of each third DC / DC module is connected in series to form the DC port of the water electrolysis hydrogen production equipment.

[0010] The water electrolysis hydrogen production device includes an alkaline water electrolysis hydrogen production device and a proton exchange membrane water electrolysis hydrogen production device. The alkaline water electrolysis hydrogen production device is configured to absorb the low-frequency pulsating power on the DC bus for water electrolysis hydrogen production, while the proton exchange membrane water electrolysis hydrogen production device is configured to absorb the high-frequency pulsating power on the DC bus for water electrolysis hydrogen production.

[0011] In one technical solution of the above-mentioned DC off-grid hydrogen production system based on renewable energy, the renewable energy power generation device includes a first power generation module and a second power generation module;

[0012] The first power generation module is connected in parallel with the first DC side of a portion of the first DC / DC modules, and the second DC side of a portion of the first DC / DC modules is connected in series to form the first equipment DC port of the renewable energy power generation equipment.

[0013] The second power generation module is connected in parallel with the first DC side of another part of the first DC / DC module, and the second DC side of the other part of the first DC / DC module is connected in series to form the second equipment DC port of the renewable energy power generation equipment.

[0014] The first power generation module is configured to output power in MPPT mode;

[0015] The second power generation module is configured to output power based on the fluctuating voltage on the DC bus, so as to provide voltage support for the DC bus.

[0016] In one technical solution of the above-mentioned off-grid DC hydrogen production system based on renewable energy, the alkaline water electrolysis hydrogen production device is connected in parallel with the first DC side of a portion of the second DC / DC module, and the proton exchange membrane water electrolysis hydrogen production device is connected in parallel with the first DC side of another portion of the second DC / DC module.

[0017] In one technical solution of the aforementioned DC off-grid hydrogen production system based on renewable energy, the renewable energy power generation equipment includes at least photovoltaic-based renewable energy power generation equipment and wind power-based renewable energy power generation equipment.

[0018] In a second aspect, a control method is provided for the DC off-grid hydrogen production system based on renewable energy as described in the first aspect, the control method comprising:

[0019] For each control cycle, the total power generation of the renewable energy power generation device, the first cutoff frequency of the first low-pass filter, and the second cutoff frequency of the second low-pass filter are obtained within the current control cycle, with the second cutoff frequency being higher than the first cutoff frequency.

[0020] A first low-pass filter is used, and the total power generated is filtered according to a first cutoff frequency to obtain a first low-frequency power.

[0021] The first low-frequency power is removed from the total power generated to obtain the first residual power for the current control cycle.

[0022] A second low-pass filter is used, and the first remaining power is filtered according to the second cutoff frequency to obtain the second low-frequency power;

[0023] The first low-frequency power is allocated as low-frequency pulsating power to the alkaline water electrolysis hydrogen production device, and the second low-frequency power is allocated as high-frequency pulsating power to the proton exchange membrane water electrolysis hydrogen production device. The alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device are controlled to perform water electrolysis hydrogen production according to the low-frequency pulsating power and the high-frequency pulsating power, respectively.

[0024] In one technical solution of the control method for the aforementioned DC off-grid hydrogen production system based on renewable energy, after the step of "using a second low-pass filter and filtering the first residual power according to a second cutoff frequency to obtain a second low-frequency power", the control method further includes:

[0025] The second residual power is obtained by removing the first low-frequency power and the second low-frequency power from the total power generated.

[0026] The second surplus power is allocated to the energy storage device for energy storage.

[0027] In one technical solution of the control method for the aforementioned off-grid hydrogen production system based on renewable energy, the method further includes obtaining the first cutoff frequency and the second cutoff frequency within the current control cycle through the following methods:

[0028] Step S1: Obtain the sum of the first low-frequency power and the second low-frequency power from the previous control cycle;

[0029] Step S2: Obtain the difference between the total power generated by the renewable energy power generation devices and the sum of the power generation devices in the current control cycle, and determine whether the difference is less than the maximum power that the energy storage device is allowed to release;

[0030] If so, then according to the optimal cutoff periods corresponding to the first low-pass filter and the second low-pass filter, the cutoff periods of the first low-pass filter and the second low-pass filter in the current control period are set respectively.

[0031] If not, obtain the cutoff period of the first low-pass filter and the second low-pass filter in the previous control cycle, adjust the cutoff period, and set the cutoff period of the first low-pass filter and the second low-pass filter in the current control cycle according to the adjusted cutoff period.

[0032] Step S3: Based on the cutoff periods of the first low-pass filter and the second low-pass filter in the current control cycle, obtain the first cutoff frequency and the second cutoff frequency in the current control cycle, respectively.

[0033] The optimal cutoff periods for the first low-pass filter and the second low-pass filter are the cutoff periods that enable the alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device to achieve the optimal hydrogen production efficiency, respectively.

[0034] In one technical solution of the control method for the aforementioned off-grid hydrogen production system based on renewable energy, the step of "adjusting the cutoff period and setting the cutoff periods of the first low-pass filter and the second low-pass filter respectively within the current control period according to the adjusted cutoff period" specifically includes:

[0035] The cutoff period of the target filter in the previous control cycle is increased by a preset value. The target filter is either the first low-pass filter or the second low-pass filter.

[0036] Determine whether the cutoff period after increasing the preset value is less than the preset maximum cutoff period;

[0037] If so, then based on the cutoff period after increasing the preset value, set the cutoff period of the target filter within the current control period;

[0038] If not, then set the cutoff period of the target filter within the current control period according to the maximum cutoff period corresponding to the target filter;

[0039] The maximum cutoff periods corresponding to the first low-pass filter and the second low-pass filter are respectively the maximum cutoff periods within the allowable range of hydrogen production efficiency of the alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device.

[0040] In a third aspect, a computer device is provided, comprising a processor and a storage device, the storage device being adapted to store a plurality of program codes, the program codes being adapted to be loaded and executed by the processor to perform the control method for a renewable energy-based DC off-grid hydrogen production system as described in any of the above-described technical solutions.

[0041] In a fourth aspect, a computer-readable storage medium is provided, wherein a plurality of program codes are stored therein, the program codes being adapted to be loaded and run by a processor to perform the control method for a renewable energy-based DC off-grid hydrogen production system as described in any of the above-described technical solutions.

[0042] The above-described technical solutions of the present invention have at least one or more of the following beneficial effects:

[0043] In the technical solution of the DC off-grid hydrogen production system of the present invention, by configuring renewable energy power generation equipment, energy storage equipment and water electrolysis hydrogen production equipment in the DC off-grid hydrogen production system, the voltage of the renewable energy power generation equipment is regulated by the DC / DC module after generating electricity, thereby reducing the loss of electricity in transmission. When the renewable energy power generation equipment generates electricity, the low-frequency pulsating power is absorbed by the alkaline water electrolysis hydrogen production device and the high-frequency pulsating power on the DC bus is absorbed by the proton exchange membrane water electrolysis hydrogen production device, thereby realizing the absorption of pulsating power on the DC bus.

[0044] In the technical solution of the control method for the DC off-grid hydrogen production system of the present invention, a first low-pass filter is used to filter the total power generation to obtain the first low-frequency power with the lowest frequency. The first low-frequency power is then removed from the total power generation to obtain the first surplus power. A second low-pass filter is then used to filter the first surplus power to obtain the second low-frequency power. Since the alkaline water electrolysis hydrogen production device has a slow dynamic response speed, the first low-frequency power can be allocated to the alkaline water electrolysis hydrogen production device. However, the proton exchange membrane electrolysis water production device can adapt to higher frequency power, so the second low-frequency power can be allocated to the proton exchange membrane electrolysis water production device. By rationally allocating the first surplus power and the second low-frequency power to different hydrogen production devices, effective absorption of pulsating power is achieved. Attached Figure Description

[0045] The disclosure of this invention will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention, wherein:

[0046] Figure 1 This is a schematic diagram of the main structure of a DC off-grid hydrogen production system based on renewable energy according to an embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the control flow of a first DC / DC module according to an embodiment of the present invention;

[0048] Figure 3This is a schematic diagram of the main structure of another DC off-grid hydrogen production system based on renewable energy according to an embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram of the main structure of another DC off-grid hydrogen production system based on renewable energy according to an embodiment of the present invention;

[0050] Figure 5 This is a schematic diagram of another DC / DC module control flow according to an embodiment of the present invention;

[0051] Figure 6 This is a schematic flowchart of the main steps of a control method for a DC off-grid hydrogen production system based on renewable energy, according to an embodiment of the present invention.

[0052] Figure 7 This is a schematic flowchart of the main steps of a method for obtaining the first and second cutoff frequencies according to an embodiment of the present invention. Detailed Implementation

[0053] Some embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] In the description of this invention, "module" and "processor" can include hardware, software, or a combination of both. A module can include hardware circuitry, various suitable sensors, communication ports, and memory, and may also include software components, such as program code, or a combination of software and hardware. A processor can be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and / or signal processing capabilities. The processor can be implemented in software, in hardware, or a combination of both. Non-transitory computer-readable storage media includes any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The terms "at least one A or B" or "at least one of A and B" have a similar meaning to "A and / or B" and can include only A, only B, or A and B.

[0055] The terminology involved in this invention will be explained below.

[0056] MTTP mode refers to Maximum Power Point Tracking mode. Renewable energy power generation equipment operates at its highest efficiency when operating in MTTP mode. Taking photovoltaic power generation as an example, the MPPT controller can detect the voltage generated by the solar panel in real time and track the highest voltage and current value (VI), enabling the system to output electrical energy at maximum power.

[0057] Alkaline water electrolysis hydrogen production devices typically use KOH or NaOH aqueous solutions as electrolytes and asbestos as a diaphragm. Under the action of direct current, water is electrolyzed to produce hydrogen and oxygen. It should be noted that alkaline electrolysis hydrogen production devices are difficult to shut down or start up quickly, and the hydrogen production rate is difficult to adjust rapidly. This is because it is necessary to maintain a constant pressure balance on both the anode and cathode sides of the electrolysis cell to prevent hydrogen and oxygen gases from mixing through the porous asbestos membrane and causing an explosion. Therefore, alkaline electrolyzers are difficult to use with renewable energy sources that have rapidly fluctuating characteristics.

[0058] Compared with alkaline water electrolysis hydrogen production equipment, proton exchange membrane water electrolysis hydrogen production equipment has higher overall efficiency, faster dynamic response speed, and can adapt to the fluctuations of renewable energy power generation.

[0059] First, please refer to the appendix. Figure 1 , Figure 1 This is a schematic diagram of the main structure of a renewable energy-based DC off-grid hydrogen production system according to an embodiment of the present invention. Figure 1 As shown, the system in this embodiment of the invention includes a renewable energy power generation device, an energy storage device, and a water electrolysis hydrogen production device, each connected to a DC bus via its respective device DC port;

[0060] The renewable energy power generation equipment includes a renewable energy power generation device and multiple first DC / DC modules. The renewable energy power generation device is connected in parallel with the first DC side of each first DC / DC module, and the second DC side of each first DC / DC module is connected in series to form the equipment DC port of the renewable energy power generation equipment.

[0061] Renewable energy power generation devices refer to equipment that generates electricity using renewable energy sources, such as photovoltaic solar panels, wind turbines, and tidal turbines. It should be noted that when the electricity generated by the renewable energy power generation device is alternating current (AC), an AC / DC module is needed to convert it to direct current (DC) before it can be connected in parallel with the first DC side of the first DC / DC module. AC / DC modules are commonly used in this field, and this invention does not limit the structure of the AC / DC module used. A DC / DC module can convert a fixed DC voltage into a variable DC voltage. Since the DC / DC module has limited ability to regulate DC voltage, those skilled in the art can connect multiple DC / DC modules in series according to actual needs to regulate the voltage generated by the renewable energy power generation device to the desired value.

[0062] The method for voltage regulation using the first DC / DC module is described below. (See appendix.) Figure 2 , Figure 2 This is a schematic diagram of the control structure of a first DC / DC module according to an embodiment of the present invention.

[0063] First, the desired output current of the renewable energy power generation device is obtained through the controller. Compared with the actual current value I sd ,according to with I sd The difference between the desired output current and the actual current value is obtained and input into a PI regulator. This difference is then modulated using a PWM modulator to regulate the output voltage of the renewable energy power generation device. The desired output current of the renewable energy power generation device is... This can be obtained through an MPPT controller, which tracks and adjusts the voltage and current emitted by renewable energy generation devices to enable them to output electrical energy at maximum power.

[0064] The energy storage device includes an energy storage unit and multiple second DC / DC modules. The energy storage unit is connected in parallel with the first DC side of each second DC / DC module, and the second DC side of each second DC / DC module is connected in series to form the device DC port of the energy storage device.

[0065] The water electrolysis hydrogen production equipment includes a water electrolysis hydrogen production unit and multiple third DC / DC modules. The water electrolysis hydrogen production unit is connected in parallel with the first DC side of each third DC / DC module, and the second DC side of each third DC / DC module is connected in series to form the DC port of the water electrolysis hydrogen production equipment.

[0066] To reduce power loss during transmission, it is often necessary to increase the voltage on the DC bus. However, the operating voltage of a water electrolysis hydrogen production device is often lower than the DC bus voltage. Therefore, a DC / DC module is needed to reduce the DC bus voltage until it meets the operating voltage requirements of the water electrolysis hydrogen production device. Using a DC / DC module to reduce the DC voltage is a common method in this field and will not be elaborated upon here.

[0067] The water electrolysis hydrogen production device includes an alkaline water electrolysis hydrogen production device and a proton exchange membrane water electrolysis hydrogen production device. The alkaline water electrolysis hydrogen production device is configured to absorb the low-frequency pulsating power on the DC bus for water electrolysis hydrogen production, while the proton exchange membrane water electrolysis hydrogen production device is configured to absorb the high-frequency pulsating power on the DC bus for water electrolysis hydrogen production.

[0068] Since alkaline electrolyzers are difficult to use with renewable energy sources that have rapid fluctuations, while proton exchange membrane electrolysis water production devices have a faster dynamic response speed and can adapt to the fluctuations in renewable energy power generation compared to alkaline electrolysis water production devices, alkaline electrolysis water production devices can be used to absorb low-frequency pulsating power on the DC bus, while proton exchange membrane electrolysis water production devices can absorb high-frequency pulsating power on the DC bus.

[0069] After representing the water electrolysis hydrogen production unit using alkaline water electrolysis hydrogen production unit and proton exchange membrane water electrolysis hydrogen production unit, the main structure of the renewable energy-based DC off-grid hydrogen production system is as follows: Figure 3 As shown.

[0070] After generating electricity, the renewable energy power generation device adjusts the voltage by configuring a DC / DC module, which reduces the loss of power during transmission. When the power on the DC bus fluctuates, the low-frequency pulsating power is absorbed by using an alkaline water electrolysis hydrogen production device, and the high-frequency pulsating power on the DC bus is absorbed by using a proton exchange membrane water electrolysis hydrogen production device, thus realizing the absorption of pulsating power on the DC bus.

[0071] When renewable energy generation is insufficient, energy storage devices are needed to support the DC bus voltage and ensure the normal operation of the water electrolysis hydrogen production unit. These energy storage devices must be controlled to discharge when renewable energy generation is insufficient to support the DC bus voltage. To reduce the cost of configuring energy storage devices, some renewable energy generation equipment can be used to support the DC bus voltage.

[0072] In one embodiment of the present invention, the renewable energy power generation device includes a first power generation module and a second power generation module;

[0073] The first power generation module is connected in parallel with the first DC side of a portion of the first DC / DC modules, and the second DC side of a portion of the first DC / DC modules is connected in series to form the first equipment DC port of the renewable energy power generation equipment.

[0074] The first and second power generation modules can be obtained by splitting the renewable energy power generation device. As an example, the renewable energy power generation device includes a photovoltaic-based renewable energy power generation device with a power output of 15 kW and a total of 300 first DC / DC modules. This 15 kW renewable energy power generation device can be split into a 10 kW first power generation module and a 5 kW second power generation module. The first power generation module is connected to 200 DC / DC modules, and the second power generation module is connected to 100 DC / DC modules.

[0075] The second power generation module is connected in parallel with the first DC side of another part of the first DC / DC module, and the second DC side of the other part of the first DC / DC module is connected in series to form the second equipment DC port of the renewable energy power generation equipment.

[0076] It should be noted that the actual power generation of the first power generation module and the second power generation module, as well as the number of first DC / DC modules connected to the first power generation module and the second power generation module, can be set according to actual needs. This embodiment of the invention does not specifically limit the above values.

[0077] The first power generation module is configured to output power in MPPT mode.

[0078] The first power generation module can be determined based on the type of renewable energy power generation device. For example, if the first power generation module is a photovoltaic-based renewable energy power generation device, then an MPPT controller can be used to detect the power generation voltage of the solar panel in real time to achieve power output in MPPT mode. If the first power generation module is a wind power-based renewable energy power generation device, then an MPPT controller can be used to control the wind turbine speed to achieve power output in MPPT mode.

[0079] The second power generation module is configured to output power based on the fluctuating voltage on the DC bus, so as to provide voltage support for the DC bus.

[0080] By dividing the renewable energy power generation device into a first power generation module and a second power generation module, and controlling the output power of the second power generation module when there are voltage fluctuations on the DC bus, the voltage fluctuations on the DC bus are reduced, ultimately ensuring the stable operation of the water electrolysis hydrogen production device. Furthermore, using the second power generation module to output power when there are voltage fluctuations on the DC bus can also reduce the capacity configuration of energy storage equipment, thereby lowering the cost of the renewable energy DC off-grid hydrogen production system.

[0081] Since the voltage generated by photovoltaic renewable energy power generation equipment is relatively stable, it is possible to use the electrical energy generated by photovoltaic renewable energy power generation equipment to support the voltage of the DC bus.

[0082] See the appendix below. Figure 4 In a preferred embodiment of the present invention, the renewable energy power generation device includes a photovoltaic-based renewable energy power generation device and a wind power generation device. In this embodiment, only the photovoltaic-based renewable energy power generation device is split up. A portion of the photovoltaic-based renewable energy power generation device and the wind power generation device together form a first power generation module, and another portion of the photovoltaic-based renewable energy power generation device forms a second power generation module.

[0083] When the renewable energy power generation equipment generates insufficient power and the voltage on the DC bus is lower than the preset voltage threshold, the power generation of the second power generation module can be used to support the voltage of the DC bus.

[0084] The following describes a method for voltage regulation using a DC / DC module to support the voltage of the DC bus. (See appendix.) Figure 5 , Figure 5 This is a schematic diagram of the control structure of a DC / DC module according to an embodiment of the present invention.

[0085] The desired output voltage to the DC / DC module With the actual voltage value V dc Then, the difference between the actual voltage value and the expected voltage value can be obtained. This difference is then input into the first PI regulator to obtain the expected current value. The expected value of the current Compared with the actual current value I sd By inputting a second PI regulator and then using a PWM modulator for modulation, the output voltage of the DC / DC module can be adjusted to the desired voltage.

[0086] In one embodiment of the present invention, the alkaline water electrolysis hydrogen production device is connected in parallel with the first DC side of a portion of the second DC / DC module, and the proton exchange membrane water electrolysis hydrogen production device is connected in parallel with the first DC side of another portion of the second DC / DC module.

[0087] In one embodiment of the present invention, the renewable energy power generation equipment includes at least photovoltaic-based renewable energy power generation equipment and wind power-based renewable energy power generation equipment.

[0088] The following describes an embodiment of the control method for a DC off-grid hydrogen production system based on renewable energy provided by the present invention.

[0089] See appendix Figure 6 , Figure 6This is a schematic flowchart illustrating the main steps of a control method for a renewable energy-based DC off-grid hydrogen production system according to an embodiment of the present invention. Figure 6 As shown, the control method of the DC off-grid hydrogen production system based on renewable energy in this embodiment of the invention mainly includes the following steps S101 to S105.

[0090] Step S101: For each control cycle, obtain the total power generation of the renewable energy power generation device, the first cutoff frequency of the first low-pass filter, and the second cutoff frequency of the second low-pass filter within the current control cycle, wherein the second cutoff frequency is higher than the first cutoff frequency.

[0091] The power output of renewable energy generation devices is constantly changing, therefore the DC off-grid hydrogen production system needs to be adjusted according to a control cycle. The duration of each control cycle can be set by those skilled in the art according to actual needs; this embodiment of the invention does not limit the duration of the control cycle. The total power output of the renewable energy generation device can be obtained through actual measurement. The cutoff frequency is a parameter value of the filter. When the frequency is below the cutoff frequency, the low-pass filter can pass through; when the frequency is above the cutoff frequency, the low-pass filter cannot pass through. Different low-pass filters have different cutoff frequencies.

[0092] Step S102: Use a first low-pass filter and filter the total generated power according to the first cutoff frequency to obtain the first low-frequency power.

[0093] The total generated power is input into the first low-pass filter, and the power passing through the first low-pass filter is the first low-frequency power. The low-pass filter is a commonly used component in this field, and this embodiment of the invention does not limit the structure of the low-pass filter.

[0094] Step S103: Remove the first low-frequency power from the total power generated to obtain the first residual power for the current control cycle.

[0095] The first remaining power in the current control cycle refers to the high-frequency power that cannot pass through the first low-pass filter.

[0096] Step S104: Use a second low-pass filter and filter the first remaining power according to the second cutoff frequency to obtain the second low-frequency power of the current control cycle.

[0097] The second low-frequency power of the current control cycle is higher than the first low-frequency power but lower than the second cutoff frequency.

[0098] Step S105: The first low-frequency power is allocated as low-frequency pulsating power to the alkaline water electrolysis hydrogen production device, and the second low-frequency power is allocated as high-frequency pulsating power to the proton exchange membrane water electrolysis hydrogen production device. The alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device are controlled to perform water electrolysis hydrogen production according to the low-frequency pulsating power and the high-frequency pulsating power, respectively.

[0099] Since the second low-frequency power of the current control cycle is higher than the first low-frequency power, and the alkaline water electrolysis hydrogen production device is difficult to coordinate with renewable energy with rapid fluctuation characteristics, while the proton exchange membrane water electrolysis hydrogen production device has a faster dynamic response speed and can adapt to the fluctuation of renewable energy power generation compared with the alkaline water electrolysis hydrogen production device, the first low-frequency power can be allocated as low-frequency pulsating power to the alkaline water electrolysis hydrogen production device, and the second low-frequency power can be allocated as high-frequency pulsating power to the proton exchange membrane water electrolysis hydrogen production device.

[0100] Based on the methods described in steps S101 to S105 above, the first low-frequency power with the lowest frequency is obtained by filtering the total power generation using a first low-pass filter. The first low-frequency power is then removed from the total power generation to obtain the first surplus power. A second low-pass filter is then used to filter the first surplus power to obtain the second low-frequency power. Since the alkaline water electrolysis hydrogen production device has a slow dynamic response, the first low-frequency power can be allocated to it. However, the proton exchange membrane electrolysis hydrogen production device can adapt to higher frequency power, so the second low-frequency power can be allocated to it. By rationally allocating the first surplus power and the second low-frequency power to different hydrogen production devices, effective absorption of pulsating power is achieved.

[0101] The following provides further explanation of steps S101 and S104.

[0102] I. Explanation of step S101.

[0103] See appendix Figure 7 , Figure 7 This is a schematic flowchart illustrating the main steps of a method for obtaining a first cutoff frequency and a second cutoff frequency according to an embodiment of the present invention. The control method for a renewable energy-based DC off-grid hydrogen production system in this embodiment further includes obtaining the first cutoff frequency and the second cutoff frequency within the current control cycle through the following step S20:

[0104] Step S201: Obtain the sum of the first low-frequency power and the second low-frequency power of the previous control cycle.

[0105] Step S202: Obtain the difference between the total power generated by the renewable energy power generation devices and the sum of the power generation devices in the current control cycle, and determine whether the difference is less than the maximum power that the energy storage device is allowed to release. If yes, proceed to step S203; otherwise, proceed to step S204.

[0106] The difference between the total power generated by renewable energy power generation devices and the sum of the power generation devices during the current control period indicates that the total power generated by renewable energy power generation devices is lower than the power value required by the water electrolysis hydrogen production device. If the difference is less than the maximum power that the energy storage device is allowed to release, then this part of the power value can be released through the energy storage device.

[0107] Step S203: Based on the optimal cutoff periods corresponding to the first low-pass filter and the second low-pass filter, set the cutoff periods of the first low-pass filter and the second low-pass filter respectively within the current control period;

[0108] Since the difference is less than the maximum power allowed to be released by the energy storage device, this portion of the power can be released through the energy storage device. Therefore, the renewable energy power generation device can operate at its optimal power. By obtaining the first cutoff frequency and the second cutoff frequency according to the optimal cutoff periods corresponding to the first and second low-pass filters, the filtered power can meet the optimal power of the renewable energy power generation device. The optimal cutoff periods corresponding to the first and second low-pass filters can be obtained according to the actual situation of the water electrolysis hydrogen production device, and are not limited in this embodiment of the invention.

[0109] Step S204: Obtain the cutoff periods of the first low-pass filter and the second low-pass filter in the previous control cycle, adjust the cutoff periods, and set the cutoff periods of the first low-pass filter and the second low-pass filter in the current control cycle according to the adjusted cutoff periods.

[0110] Since the difference is greater than the maximum power that the energy storage device can release, this part of the power cannot be released through the energy storage device. Therefore, it is necessary to adjust the cutoff frequency of the low-pass filter by adjusting the cutoff period of the low-pass filter in the current control cycle, thereby adjusting the power of the water electrolysis hydrogen production device.

[0111] Step S205: Based on the cutoff periods of the first low-pass filter and the second low-pass filter within the current control period, obtain the first cutoff frequency and the second cutoff frequency within the current control period, respectively; wherein, the optimal cutoff periods corresponding to the first low-pass filter and the second low-pass filter are the cutoff periods that enable the hydrogen production efficiency of the alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device to reach the optimal level.

[0112] The cutoff frequencies of the first and second low-pass filters are calculated using the following formula based on their cutoff periods:

[0113]

[0114] Where P1 represents the cutoff frequency of the first filter, P2 represents the cutoff frequency of the second filter, Tf1 is the cutoff period of the first filter, and Tf2 is the cutoff period of the second filter.

[0115] Based on the methods described in steps S201 to S205 above, it is first determined whether the maximum power released by the energy storage device can support the electrolysis hydrogen production device to operate at maximum power. If it can, the optimal cutoff period of the first low-pass filter and the second low-pass filter is used as the cutoff period in the current control cycle, thereby enabling the electrolysis hydrogen production device to operate at maximum power and ensuring the efficiency of water electrolysis hydrogen production. If the maximum power released by the energy storage device cannot support the electrolysis hydrogen production device to operate at maximum power, the cutoff periods of the first low-pass filter and the second low-pass filter in the previous control cycle are adjusted to appropriately reduce the hydrogen production efficiency of the water electrolysis hydrogen production device, thereby ensuring the stable operation of the DC off-grid hydrogen production system.

[0116] In one embodiment of the first embodiment of the present invention, the step of “adjusting the cutoff period and setting the cutoff periods of the first low-pass filter and the second low-pass filter respectively in the current control period according to the adjusted cutoff period (the aforementioned step S204)” specifically includes the following steps 11 to 14:

[0117] Step 11: Increase the cutoff period of the target filter by a preset value in the previous control cycle. The target filter is either the first low-pass filter or the second low-pass filter.

[0118] The preset value can be set according to actual needs. The preset value added by the first low-pass filter can be the same as or different from the preset value added by the second low-pass filter. The longer the cutoff period, the lower the hydrogen production efficiency of the water electrolysis hydrogen production device.

[0119] Step 12: Determine whether the cutoff period after increasing the preset value is less than the preset maximum cutoff period. If yes, proceed to step 13; otherwise, proceed to step 14.

[0120] The preset maximum cutoff period can be determined based on the actual conditions of alkaline water electrolysis hydrogen production devices and proton exchange membrane water electrolysis hydrogen production devices. This invention does not limit the method for obtaining the preset maximum cutoff period or the specific value of the preset maximum cutoff period. It should be noted that the preset maximum cutoff periods for different types of water electrolysis hydrogen production devices can be the same or different.

[0121] Step 13: Based on the cutoff period after adding the preset value, set the cutoff period of the target filter within the current control period.

[0122] Step 14: Based on the maximum cutoff period corresponding to the target filter, set the cutoff period of the target filter within the current control cycle. The maximum cutoff periods corresponding to the first low-pass filter and the second low-pass filter are respectively the maximum cutoff periods within the allowable range of hydrogen production efficiency of the alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device.

[0123] Since the cutoff period after increasing the preset value is greater than the preset maximum cutoff period, the alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device cannot operate normally under this cutoff period. Therefore, the maximum cutoff period corresponding to the target filter is set as the cutoff period of the target filter within the current control period.

[0124] Based on the methods in steps S11 to S14 above, the cutoff periods of the first low-pass filter and the second low-pass filter are adjusted within the current control cycle. Within the maximum cutoff period allowed by the hydrogen production efficiency of the water electrolysis hydrogen production device, the cutoff periods of the first low-pass filter and the second low-pass filter are adjusted within the current control cycle, thereby reducing the hydrogen production efficiency of the water electrolysis hydrogen production device to smooth out the fluctuations in the total power generation of the renewable energy power generation device.

[0125] II. Further explanation of step S104.

[0126] To avoid wasting unusable electrical energy, it can be stored in energy storage devices.

[0127] In one embodiment of the present invention, after the step of "using a second low-pass filter and filtering the first residual power according to a second cutoff frequency to obtain a second low-frequency power (as described in step S104 above)", the control method further includes:

[0128] The second residual power is obtained by removing the first low-frequency power and the second low-frequency power from the total power generated.

[0129] The second surplus power is allocated to the energy storage device for energy storage.

[0130] By storing the electrical energy that cannot be consumed by the water electrolysis hydrogen production equipment in an energy storage device, energy waste is reduced.

[0131] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of the present invention.

[0132] Those skilled in the art will understand that all or part of the processes in the method of the above embodiment of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0133] Furthermore, the present invention also provides a computer device.

[0134] In an embodiment of a computer device according to the present invention, the computer device includes a processor and a storage device. The storage device may be configured to store a program for executing a control method of a renewable energy-based DC off-grid hydrogen production system according to the above-described method embodiments. The processor may be configured to execute the program in the storage device, which includes, but is not limited to, a program for executing a control method of a renewable energy-based DC off-grid hydrogen production system according to the above-described method embodiments. For ease of explanation, only the parts related to the embodiments of the present invention are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of the present invention. The computer device may be a control device device comprising various electronic devices.

[0135] Furthermore, the present invention also provides a computer-readable storage medium.

[0136] In one embodiment of the present invention, the computer-readable storage medium can be configured to store a program for executing a control method of a renewable energy-based DC off-grid hydrogen production system according to the above-described method embodiments. This program can be loaded and run by a processor to implement the aforementioned control method for a renewable energy-based DC off-grid hydrogen production system. For ease of explanation, only the parts related to the embodiments of the present invention are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of the present invention. The computer-readable storage medium can be a storage device comprising various electronic devices. Optionally, in the embodiments of the present invention, the computer-readable storage medium is a non-transitory computer-readable storage medium.

[0137] The technical solution of the present invention has been described above with reference to one embodiment shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions resulting from such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A control method for a DC off-grid hydrogen production system based on renewable energy, characterized in that, The system includes renewable energy power generation equipment, energy storage equipment, and water electrolysis hydrogen production equipment, each connected to a DC bus via its own DC port. The renewable energy power generation equipment includes a renewable energy power generation unit and multiple first DC / DC modules. Each renewable energy power generation unit is connected in parallel with the first DC side of each first DC / DC module, and the second DC sides of each first DC / DC module are connected in series to form the DC port of the renewable energy power generation equipment. The energy storage equipment includes an energy storage device and multiple second DC / DC modules. The energy storage device is connected in parallel with the first DC side of each second DC / DC module, and the second DC sides of each second DC / DC module are connected in series to form the DC port of the renewable energy power generation equipment. The device comprises a DC port for the energy storage device; the water electrolysis hydrogen production device includes a water electrolysis hydrogen production unit and multiple third DC / DC modules, wherein the water electrolysis hydrogen production unit is connected in parallel with the first DC side of each third DC / DC module, and the second DC side of each third DC / DC module is connected in series to form the device DC port for the water electrolysis hydrogen production device; wherein the water electrolysis hydrogen production unit includes an alkaline water electrolysis hydrogen production unit and a proton exchange membrane water electrolysis hydrogen production unit, wherein the alkaline water electrolysis hydrogen production unit is configured to absorb the low-frequency pulsating power on the DC bus for water electrolysis hydrogen production, and the proton exchange membrane water electrolysis hydrogen production unit is configured to absorb the high-frequency pulsating power on the DC bus for water electrolysis hydrogen production; The control method includes: For each control cycle, the total power generation of the renewable energy power generation device, the first cutoff frequency of the first low-pass filter, and the second cutoff frequency of the second low-pass filter are obtained within the current control cycle, wherein the second cutoff frequency is higher than the first cutoff frequency. A first low-pass filter is used, and the total generated power is filtered according to the first cutoff frequency to obtain a first low-frequency power. The first low-frequency power is removed from the total power generated to obtain the first remaining power for the current control cycle; A second low-pass filter is used, and the first remaining power is filtered according to the second cutoff frequency to obtain the second low-frequency power; The first low-frequency power is allocated as the low-frequency pulsating power to the alkaline water electrolysis hydrogen production device, and the second low-frequency power is allocated as the high-frequency pulsating power to the proton exchange membrane water electrolysis hydrogen production device. The alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device are controlled to perform water electrolysis hydrogen production according to the low-frequency pulsating power and the high-frequency pulsating power, respectively.

2. The control method for a DC off-grid hydrogen production system based on renewable energy according to claim 1, characterized in that, After the step of "using a second low-pass filter and filtering the first residual power according to the second cutoff frequency to obtain the second low-frequency power", the control method further includes: The first low-frequency power and the second low-frequency power are removed from the total power generated to obtain the second residual power; The second remaining power is allocated to the energy storage device for energy storage.

3. The control method for a DC off-grid hydrogen production system based on renewable energy according to claim 1, characterized in that, The method further includes obtaining the first cutoff frequency and the second cutoff frequency within the current control cycle through the following methods: Step S1: Obtain the sum of the first low-frequency power and the second low-frequency power from the previous control cycle; Step S2: Obtain the difference between the total power generated by the renewable energy power generation device and the sum within the current control cycle, and determine whether the difference is less than the maximum power that the energy storage device is allowed to release; If so, then according to the optimal cutoff periods corresponding to the first low-pass filter and the second low-pass filter, the cutoff periods of the first low-pass filter and the second low-pass filter in the current control period are set respectively. If not, obtain the cutoff period of the first low-pass filter and the second low-pass filter in the previous control cycle, adjust the cutoff period, and set the cutoff period of the first low-pass filter and the second low-pass filter in the current control cycle according to the adjusted cutoff period. Step S3: Based on the cutoff periods of the first low-pass filter and the second low-pass filter in the current control cycle, obtain the first cutoff frequency and the second cutoff frequency in the current control cycle, respectively. The optimal cutoff periods for the first low-pass filter and the second low-pass filter are the cutoff periods that enable the alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device to achieve the optimal hydrogen production efficiency, respectively.

4. The control method for a DC off-grid hydrogen production system based on renewable energy according to claim 3, characterized in that, The steps of "adjusting the cutoff period and setting the cutoff periods of the first low-pass filter and the second low-pass filter respectively within the current control period according to the adjusted cutoff period" specifically include: The cutoff period of the target filter in the previous control cycle is increased by a preset value, wherein the target filter is a first low-pass filter or a second low-pass filter. Determine whether the cutoff period after increasing the preset value is less than the preset maximum cutoff period; If so, then based on the cutoff period after increasing the preset value, set the cutoff period of the target filter within the current control period; If not, then set the cutoff period of the target filter within the current control period according to the maximum cutoff period corresponding to the target filter; The maximum cutoff periods corresponding to the first low-pass filter and the second low-pass filter are respectively the maximum cutoff periods within the allowable range of hydrogen production efficiency of the alkaline water electrolysis hydrogen production device and the proton exchange membrane water electrolysis hydrogen production device.

5. The control method for a DC off-grid hydrogen production system based on renewable energy according to claim 1, characterized in that, The renewable energy power generation device includes a first power generation module and a second power generation module; The first power generation module is connected in parallel with the first DC side of a portion of the first DC / DC modules, and the second DC sides of the portion of the first DC / DC modules are connected in series to form the first device DC port of the renewable energy power generation equipment. The second power generation module is connected in parallel with the first DC side of another part of the first DC / DC module, and the second DC side of the other part of the first DC / DC module is connected in series to form the second device DC port of the renewable energy power generation equipment; The first power generation module is configured to output power in MPPT mode; The second power generation module is configured to output power based on the fluctuating voltage on the DC bus, so as to provide voltage support for the DC bus.

6. The control method for a DC off-grid hydrogen production system based on renewable energy according to claim 1, characterized in that, The alkaline water electrolysis hydrogen production device is connected in parallel with the first DC side of a portion of the second DC / DC module, and the proton exchange membrane water electrolysis hydrogen production device is connected in parallel with the first DC side of another portion of the second DC / DC module.

7. The control method for a DC off-grid hydrogen production system based on renewable energy according to claim 1, characterized in that, The renewable energy power generation equipment includes at least photovoltaic-based renewable energy power generation equipment and wind power-based renewable energy power generation equipment.

8. A computer device comprising a processor and a storage device, said storage device being adapted to store a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by the processor to perform the control method of the DC off-grid hydrogen production system based on renewable energy as described in any one of claims 1 to 7.

9. A computer-readable storage medium storing a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by a processor to perform the control method for a DC off-grid hydrogen production system based on renewable energy, as described in any one of claims 1 to 7.

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