Photovoltaic water electrolysis hydrogen production system and operation method

Abstract

The photovoltaic water electrolysis hydrogen production system comprises a photovoltaic power generation device (1), the output end of the photovoltaic power generation device (1) is connected with a photovoltaic controller (2), the output end of the photovoltaic controller (2) is connected with a first electrolysis power source (5) and a second electrolysis power source (6) in parallel, the first electrolysis power source (5) and the second electrolysis power source (6) are each provided with a sensor, and a first DC-DC converter (3) is connected to the first electrolysis power source (5) in parallel; the second DC-DC converter (4) is connected between the photovoltaic controller (2) and the second electrolytic power supply (5) in parallel and then connected with the super capacitor (8), the first electrolytic power supply (5) is connected with the first electrolytic cell (9), a first switch (11) is arranged between the first electrolytic power supply (5) and the first electrolytic cell (9), the second electrolytic power supply (6) is connected with at least one second electrolytic cell (10), and a second switch (12) is arranged between the second electrolytic cell (10) and the second electrolytic cell (10). The combined electrolytic cell ensures the hydrogen production amount, improves the photovoltaic utilization efficiency and improves the flexibility of the system.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic water electrolysis hydrogen production, and in particular to a photovoltaic water electrolysis hydrogen production system and an operation method. Background Art

[0002] The output power of photovoltaic systems is greatly affected by the intensity of sunlight, ambient temperature, weather conditions, etc., so power electronic devices are usually required to implement maximum power point tracking (MPPT) to optimize power output. Although photovoltaic power generation has matured in many applications, it is challenging to use it directly for stable loads (such as electrolyzers) due to its intermittent and unstable nature. The core of the photovoltaic hydrogen production system is the control system, whose main function is to coordinate the operation of the photovoltaic array, electrolyzer, and energy storage equipment to ensure that the system operates efficiently and stably. Currently, most photovoltaic hydrogen production control systems reconstruct the electrolyzer array according to the photovoltaic output power size to maximize the photovoltaic utilization efficiency and electrolytic hydrogen production efficiency. The current photovoltaic hydrogen production system needs to improve the durability of the electrolyzer and energy storage equipment, and at the same time improve the control system to minimize the frequent start and stop of the electrolyzer and energy storage equipment. Complex power conversion and control strategies are required to ensure that the power of the photovoltaic array matches that of the electrolyzer. The addition of power converters and control algorithms will increase the system complexity and cost. Although energy storage systems (such as batteries or supercapacitors) can be used to smooth the volatility of photovoltaic power generation, the cost of large-scale energy storage is high, and there will be additional losses during energy conversion and storage. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a photovoltaic water electrolysis hydrogen production system and an operation method.

[0004] The objective of the present invention is achieved through the following technical solutions: In a first aspect, the present invention discloses a photovoltaic water electrolysis hydrogen production system, comprising a photovoltaic power generation device, wherein the output end of the photovoltaic power generation device is connected to a photovoltaic controller, the output end of the photovoltaic controller is connected in parallel to a first electrolysis power supply and a second electrolysis power supply, the first electrolysis power supply and the second electrolysis power supply are provided with a sensor for detecting an input voltage, a first DC-DC converter is connected in parallel to the first electrolysis power supply, and a second DC-DC converter is connected in parallel between the photovoltaic controller and the second electrolysis power supply, the first DC-DC converter and the second DC-DC converter are bidirectional DC-DC converters, the first DC-DC converter is connected to a battery energy storage module, the second DC-DC converter is connected to a supercapacitor, the first electrolysis power supply is connected to a first electrolytic cell, a first switch is provided between the first electrolysis power supply and the first electrolytic cell, for realizing energy flow between the first electrolysis power supply and the first electrolytic cell, the second electrolysis power supply is connected to at least one second electrolytic cell, when the number of the second electrolytic cells is multiple, each second electrolytic cell is connected in parallel, and a second switch is provided between the second electrolysis power supply and the second electrolytic cell, for realizing energy flow between the second electrolysis power supply and the second electrolytic cell.

[0005] Based on the first aspect, the photovoltaic controller is a Boost circuit.

[0006] Based on the first aspect, the first electrolytic cell is a high-power electrolytic cell, and the second electrolytic cell is a low-power electrolytic cell.

[0007] In a second aspect, the present invention discloses an operation method for the photovoltaic water electrolysis hydrogen production system described above, comprising the following steps: S1. After sunrise, the photovoltaic power generation device starts to generate output power. At this time, the first switch and the second switch are in the disconnected state. The first electrolytic cell and the second electrolytic cell are both set with a first preset threshold power and a second preset threshold power. The sensor of the first electrolytic power source detects whether the first input power reaches the first preset threshold power of the first electrolytic cell. The first input power is the power input from the photovoltaic power generation device to the first electrolytic cell. If it reaches the first preset threshold power, the first switch is closed to start the first electrolytic cell. If it does not reach the first preset threshold power, the photovoltaic power generation device first charges the supercapacitor until the first input power reaches the first preset threshold power of the first electrolytic cell, then stops charging the supercapacitor, closes the first switch, and starts the first electrolytic cell. S2, if the sensor of the first electrolytic power source detects that the first input power reaches the second preset threshold power of the first electrolytic cell, the first input power is stabilized, and then the sensor of the second electrolytic power source detects whether the second input power reaches the first preset threshold power of the second electrolytic cell, the second input power being the remaining output power of the photovoltaic power generation device after the first input power is stabilized, and if it is reached, the second switch is closed to start the second electrolytic cell; if it is not reached, the supercapacitor is charged first until the second input power reaches the first preset threshold power of the second electrolytic cell, then the supercapacitor is stopped from being charged, and the second switch is closed to start the second electrolytic cell; S3. When the second input power is greater than the second preset threshold power of the second electrolytic cell, the second input power is stabilized, and the third input power is input into the supercapacitor for charging, wherein the third input power is the remaining output power of the photovoltaic power generation device after the first input power and the second input power are stabilized, and if the supercapacitor is fully charged, the photovoltaic power generation device inputs the fourth input power into the battery energy storage module for charging, wherein the fourth input power is the remaining output power of the photovoltaic power generation device after the first input power and the second input power are stabilized and the supercapacitor is fully charged; S4. If the output power of the photovoltaic power generation device fluctuates, the load is reduced starting from the second electrolytic cell; S5. When the solar radiation begins to decrease, the load is reduced from the second electrolytic cell. When the second input power of the second electrolytic cell decreases to below the second preset threshold power, the supercapacitor starts to discharge to maintain the second electrolytic cell in operation between the first state and the second state until the power of the supercapacitor is exhausted. If the second input power is insufficient to maintain the second electrolytic cell operating at the first preset threshold power, the second electrolytic cell is shut down. S6. If the first input power is greater than the second preset threshold power of the first electrolyzer at this time, the remaining output power of the photovoltaic power generation device is used to charge the supercapacitor; when the first input power is lower than the second preset threshold power of the first electrolyzer, the battery energy storage module starts to discharge to maintain the first electrolyzer at the second preset threshold power and continue to operate until the battery energy storage module is exhausted. If the first input power is insufficient to maintain the first electrolyzer at the first preset threshold power, the first electrolyzer shuts down.

[0008] Based on the second aspect, in the step S4: if the first electrolyzer and the second electrolyzer are operating between the first preset threshold power and the second preset threshold power, the output power of the photovoltaic power generation device suddenly decreases, so that the first input power is less than the first preset threshold power of the first electrolyzer, and the second input power is less than the first preset threshold power of the second electrolyzer, and if the supercapacitor has power at this time, the supercapacitor directly intervenes to maintain the first electrolyzer and the second electrolyzer operating at the first preset threshold power; If both the first electrolyzer and the second electrolyzer are operating at the second preset threshold power and the battery energy storage module is in a charging state, the output power of the photovoltaic power generation device suddenly decreases. At this time, if the second electrolyzer is operating between the first preset threshold power and the second preset threshold power, the supercapacitor discharges to maintain the charging voltage of the battery energy storage module; if the second input power is below the first preset threshold power of the second electrolyzer, the supercapacitor discharges the second electrolyzer to maintain the second electrolyzer operating at the first preset threshold power.

[0009] The beneficial effects of the present invention are: 1) The present invention starts the electrolyzer when the photovoltaic output is sufficient, and starts the electrolyzer to charge the supercapacitor when it is insufficient, thereby ensuring the utilization rate of photovoltaics, avoiding low-power operation of the electrolyzer, extending the service life of the electrolyzer and improving the gas production quality.

[0010] 2) The present invention fully considers the advantages and disadvantages of supercapacitors and battery energy storage modules. Supercapacitors are used to resist the impact of photovoltaic fluctuations on the power supply of the electrolyzer and the charging of the battery energy storage module because they can be charged and discharged frequently and have high discharge efficiency. The battery energy storage module only supplies power to the electrolyzer when the photovoltaic power decreases in the evening, which increases the total hydrogen production of the system, and the number of charge and discharge times is small, which prolongs the service life of the battery energy storage module.

[0011] 3) The electrolyzer array of the present invention adopts the form of a combination of high-power electrolyzers and low-power electrolyzers, which improves the flexibility of the system while ensuring the hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic structural diagram of a photovoltaic water electrolysis hydrogen production system according to an embodiment of the present invention; Figure 2 A schematic flow chart of the steps of an operation method of a photovoltaic water electrolysis hydrogen production system according to an embodiment of the present invention; In the figure, 1-photovoltaic power generation device, 2-photovoltaic controller, 3-first DC-DC converter, 4-second DC-DC converter, 5-first electrolysis power supply, 6-second electrolysis power supply, 7-battery energy storage module, 8-supercapacitor, 9-first electrolytic cell, 10-second electrolytic cell, 11-first switch, 12-second switch. DETAILED DESCRIPTION

[0013] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0014] The present invention discloses a photovoltaic water electrolysis hydrogen production system, the structural schematic diagram of which is shown in Figure 1 As shown, it includes a photovoltaic power generation device 1, the output end of the photovoltaic power generation device 1 is connected to a photovoltaic controller 2, the output end of the photovoltaic controller 2 is connected in parallel to a first electrolysis power source 5 and a second electrolysis power source 6, the first electrolysis power source 5 and the second electrolysis power source 6 are provided with sensors for detecting input voltage, a first DC-DC converter 3 is connected in parallel to the first electrolysis power source 5, a second DC-DC converter 4 is connected in parallel between the photovoltaic controller 2 and the second electrolysis power source 6, the first DC-DC converter 3 and the second DC-DC converter 4 are bidirectional DC-DC converters, the first DC-DC converter 3 and the battery storage The energy module 7 is connected, the second DC-DC converter 4 is connected to the supercapacitor 8, the first electrolysis power supply 5 is connected to the first electrolytic cell 9, a first switch 11 is provided between the first electrolysis power supply 5 and the first electrolytic cell 9, and is used to realize the energy flow between the first electrolysis power supply 5 and the first electrolytic cell 9, the second electrolysis power supply 6 is connected to at least one second electrolytic cell 10, when the number of the second electrolytic cells 10 is multiple, each second electrolytic cell 10 is connected in parallel with each other, and a second switch 12 is provided between the second electrolysis power supply 6 and the second electrolytic cell 10, and is used to realize the energy flow between the second electrolysis power supply 6 and the second electrolytic cell 10.

[0015] Specifically, the photovoltaic controller 2 is a Boost circuit. The first electrolyzer 9 is a high-power electrolyzer, which is the main hydrogen production device, and the second electrolyzer 10 is a low-power electrolyzer, which is a secondary hydrogen production device, mainly used to cope with photovoltaic fluctuations and system dynamic regulation. The supercapacitor 8 is used to power the electrolyzer when photovoltaic fluctuations cause it to be lower than the minimum operating power or the battery energy storage module charging power is insufficient; the specific capacity configuration of the system, such as the power selection of the electrolyzer and the number of the second electrolyzer 10, is determined by the actual working environment.

[0016] The present invention also discloses an operation method for the photovoltaic water electrolysis hydrogen production system described above, and the schematic flow chart of the steps is as follows: Figure 2 As shown, the following steps are included: S1. After sunrise, the photovoltaic power generation device 1 starts to generate output power. At this time, the first switch 11 and the second switch 12 are in the off state. The first electrolyzer 9 and the second electrolyzer 10 are both set with a first preset threshold power and a second preset threshold power. The first preset threshold power is the minimum working power, which refers to the minimum power at which the electrolyzer can produce hydrogen and maintain operation. The second preset threshold power is the optimal working power, which refers to the working power when the electrolysis efficiency of the electrolyzer is the highest. The first preset threshold power and the second preset threshold power are parameters of the electrolyzer set according to the actual working environment and are not limited to a specific range. The sensor of the first electrolysis power source 5 detects whether the first input power reaches the first preset threshold power of the first electrolyzer 9. The first input power is the power input from the photovoltaic power generation device 1 to the first electrolyzer 9. If it reaches the first preset threshold power, the first switch 11 is closed to turn on the first electrolyzer 9; if it does not reach the first preset threshold power, the photovoltaic power generation device 1 first charges the supercapacitor 8 until the first input power reaches the first preset threshold power of the first electrolyzer 9, then stops charging the supercapacitor 8, closes the first switch 11, and turns on the first electrolyzer 9; S2, if the sensor of the first electrolytic power source 5 detects that the first input power reaches the second preset threshold power of the first electrolytic cell 9, the first input power is stabilized, and then the sensor of the second electrolytic power source 6 detects whether the second input power reaches the first preset threshold power of the second electrolytic cell 10, the second input power is the remaining output power of the photovoltaic power generation device 1 after the first input power is stabilized, if it is reached, the second switch 12 is closed to start the second electrolytic cell 10; if it is not reached, the supercapacitor 8 is charged first until the second input power reaches the first preset threshold power of the second electrolytic cell 10, then the supercapacitor 8 is stopped from being charged, and the second switch 12 is closed to start the second electrolytic cell 10; S3, when the second input power is greater than the second preset threshold power of the second electrolytic cell 10, the second input power is stabilized, and the third input power is input to the supercapacitor 8 for charging, the third input power being the remaining output power of the photovoltaic power generation device 1 after the first input power and the second input power are stabilized, and if the supercapacitor 8 reaches a fully charged state, the photovoltaic power generation device 1 inputs a fourth input power to the battery energy storage module 7 for charging, the fourth input power being the remaining output power of the photovoltaic power generation device 1 after the first input power and the second input power are stabilized and the supercapacitor 8 is fully charged; S4. If the output power of the photovoltaic power generation device 1 fluctuates, the load is first reduced from the second electrolytic cell 10; S5. When the solar radiation begins to decrease, the load is reduced from the second electrolytic cell 10. When the second input power of the second electrolytic cell 10 decreases to below the second preset threshold power, the supercapacitor 8 starts to discharge to maintain the second electrolytic cell 10 in the operation between the first state and the second state until the power of the supercapacitor 8 is exhausted. If the second input power is not enough to maintain the second electrolytic cell 10 in the operation at the first preset threshold power, the second electrolytic cell 10 is shut down. S6. If the first input power is greater than the second preset threshold power of the first electrolytic cell 9 at this time, the remaining output power of the photovoltaic power generation device 1 is used to charge the supercapacitor 8; when the first input power is lower than the second preset threshold power of the first electrolytic cell 9, the battery energy storage module 7 starts to discharge to maintain the first electrolytic cell 9 at the second preset threshold power and continue to operate until the battery energy storage module 7 is exhausted. If the first input power is insufficient to maintain the first electrolytic cell 9 at the first preset threshold power, the first electrolytic cell 9 shuts down.

[0017] Specifically, in step S4: when the first electrolytic cell 9 and the second electrolytic cell 10 are operating between the first preset threshold power and the second preset threshold power, the output power of the photovoltaic power generation device 1 is suddenly reduced, so that the first input power is less than the first preset threshold power of the first electrolytic cell 9, and the second input power is less than the first preset threshold power of the second electrolytic cell 10. At this time, if the supercapacitor 8 has power, the supercapacitor 8 directly intervenes to maintain the first electrolytic cell 9 and the second electrolytic cell 10 operating at the first preset threshold power; If the first electrolytic cell 9 and the second electrolytic cell 10 are both operating at the second preset threshold power and the battery energy storage module 7 is in a charging state, the output power of the photovoltaic power generation device 1 suddenly decreases. At this time, if the second electrolytic cell 10 operates between the first preset threshold power and the second preset threshold power, the supercapacitor 8 discharges to maintain the charging voltage of the battery energy storage module 7; if the second input power is below the first preset threshold power of the second electrolytic cell 10, the supercapacitor 8 discharges the second electrolytic cell 10 to maintain the second electrolytic cell 10 operating at the first preset threshold power.

[0018] The present invention proposes a photovoltaic water electrolysis hydrogen production system and operation method, which can flexibly cope with photovoltaic fluctuations. The system adopts an array of electrolyzers with different power sizes, a mixed energy storage system of supercapacitors 8 and battery energy storage modules 7. The electrolyzer array adopts a combination of a high-power first electrolyzer 9 and a low-power second electrolyzer 10, which not only ensures the hydrogen production, but also improves the flexibility of the system. The photovoltaic utilization efficiency is improved, and a supercapacitor 8 is used to cope with power fluctuations, and a battery energy storage module 7 is used to ensure the operation strategy of the first electrolyzer 9 to supply power steadily. When the system is loaded and unloaded, a control method of step-by-step loading and step-by-step unloading is adopted to improve the utilization efficiency of photovoltaics. The electrolyzer is guaranteed to be in a working state to the greatest extent and the photovoltaic hydrogen production is maximized.

[0019] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A photovoltaic water electrolysis hydrogen production system, characterized in that: The invention comprises a photovoltaic power generation device (1), wherein the output end of the photovoltaic power generation device (1) is connected to a photovoltaic controller (2), the output end of the photovoltaic controller (2) is connected in parallel to a first electrolysis power source (5) and a second electrolysis power source (6), the first electrolysis power source (5) and the second electrolysis power source (6) are provided with sensors for detecting input voltage, a first DC-DC converter (3) is connected in parallel to the first electrolysis power source (5), a second DC-DC converter (4) is connected in parallel between the photovoltaic controller (2) and the second electrolysis power source (6), the first DC-DC converter (3) and the second DC-DC converter (4) are bidirectional DC-DC converters, and the first DC-DC converter (3) and the battery energy storage module (7) are connected in parallel to each other. ), the second DC-DC converter (4) is connected to the supercapacitor (8), the first electrolysis power source (5) is connected to the first electrolysis cell (9), a first switch (11) is provided between the first electrolysis power source (5) and the first electrolysis cell (9) for realizing energy flow between the first electrolysis power source (5) and the first electrolysis cell (9), the second electrolysis power source (6) is connected to at least one second electrolysis cell (10), when there are multiple second electrolysis cells (10), the second electrolysis cells (10) are connected in parallel, and a second switch (12) is provided between the second electrolysis power source (6) and the second electrolysis cell (10) for realizing energy flow between the second electrolysis power source (6) and the second electrolysis cell (10).

2. A photovoltaic water electrolysis hydrogen production system according to claim 1, characterized in that: The photovoltaic controller (2) is a Boost circuit.

3. A photovoltaic water electrolysis hydrogen production system according to claim 1, characterized in that: The first electrolytic cell (9) is a high-power electrolytic cell, and the second electrolytic cell (10) is a low-power electrolytic cell.

4. An operating method for the photovoltaic water electrolysis hydrogen production system according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. After sunrise, the photovoltaic power generation device (1) starts to generate output power. At this time, the first switch (11) and the second switch (12) are in an open state. The first electrolytic cell (9) and the second electrolytic cell (10) are both set to a first preset threshold power and a second preset threshold power. The sensor of the first electrolytic power source (5) detects whether the first input power reaches the first preset threshold power of the first electrolytic cell (9). The first input power is the power input from the photovoltaic power generation device (1) to the first electrolytic cell (9). If the first input power reaches the first preset threshold power of the first electrolytic cell (9), the first switch (11) is closed to turn on the first electrolytic cell (9). If the first input power reaches the first preset threshold power of the first electrolytic cell (9), the photovoltaic power generation device (1) first charges the supercapacitor (8) until the first input power reaches the first preset threshold power of the first electrolytic cell (9). Then, the supercapacitor (8) is stopped from being charged, the first switch (11) is closed, and the first electrolytic cell (9) is turned on. S2, if the sensor of the first electrolytic power source (5) detects that the first input power reaches the second preset threshold power of the first electrolytic cell (9), the first input power is stabilized, and then the sensor of the second electrolytic power source (6) detects whether the second input power reaches the first preset threshold power of the second electrolytic cell (10), wherein the second input power is the remaining output power of the photovoltaic power generation device (1) after the first input power is stabilized, and if it is reached, the second switch (12) is closed to start the second electrolytic cell (10); if it is not reached, the supercapacitor (8) is charged first until the second input power reaches the first preset threshold power of the second electrolytic cell (10), then the supercapacitor (8) is stopped from being charged, and the second switch (12) is closed to start the second electrolytic cell (10); S3, when the second input power is greater than the second preset threshold power of the second electrolytic cell (10), the second input power is stabilized, and a third input power is input into the supercapacitor (8) for charging, wherein the third input power is the remaining output power of the photovoltaic power generation device (1) after the first input power and the second input power are stabilized, and if the supercapacitor (8) reaches a fully charged state, the photovoltaic power generation device (1) inputs a fourth input power into the battery energy storage module (7) for charging, wherein the fourth input power is the remaining output power of the photovoltaic power generation device (1) after the first input power and the second input power are stabilized and the supercapacitor (8) is fully charged; S4. If the output power of the photovoltaic power generation device (1) fluctuates, the load is first reduced from the second electrolytic cell (10); S5. When the solar radiation begins to decrease, the load is reduced from the second electrolytic cell (10). When the second input power of the second electrolytic cell (10) decreases to below the second preset threshold power, the supercapacitor (8) starts to discharge to maintain the second electrolytic cell (10) in operation between the first state and the second state until the power of the supercapacitor (8) is exhausted. If the second input power is insufficient to maintain the second electrolytic cell (10) in operation at the first preset threshold power, the second electrolytic cell (10) is shut down. S6. If the first input power is greater than the second preset threshold power of the first electrolytic cell (9) at this time, the remaining output power of the photovoltaic power generation device (1) is used to charge the supercapacitor (8); when the first input power is lower than the second preset threshold power of the first electrolytic cell (9), the battery energy storage module (7) starts to discharge to maintain the first electrolytic cell (9) at the second preset threshold power and continues to operate until the power of the battery energy storage module (7) is exhausted; if the first input power is insufficient to maintain the first electrolytic cell (9) operating at the first preset threshold power, the first electrolytic cell (9) is shut down.

5. An operating method according to claim 4, characterized in that: In the step S4: when the first electrolytic cell (9) and the second electrolytic cell (10) are operating between the first preset threshold power and the second preset threshold power, the output power of the photovoltaic power generation device (1) is suddenly reduced, so that the first input power is less than the first preset threshold power of the first electrolytic cell (9), and the second input power is less than the first preset threshold power of the second electrolytic cell (10). At this time, if the supercapacitor (8) has power, the supercapacitor (8) directly intervenes to maintain the first electrolytic cell (9) and the second electrolytic cell (10) operating at the first preset threshold power; If both the first electrolytic cell (9) and the second electrolytic cell (10) are operated at the second preset threshold power, and the battery energy storage module (7) is in a charging state, the output power of the photovoltaic power generation device (1) suddenly decreases. At this time, if the second electrolytic cell (10) is operated between the first preset threshold power and the second preset threshold power, the supercapacitor (8) discharges to maintain the charging voltage of the battery energy storage module (7); if the second input power is below the first preset threshold power of the second electrolytic cell (10), the supercapacitor (8) discharges the second electrolytic cell (10) to maintain the second electrolytic cell (10) operating at the first preset threshold power.

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