A photovoltaic DC coupled hydrogen production system and control method thereof

Abstract

The present invention relates to the field of hydrogen production technology, and in particular to a photovoltaic direct current coupled hydrogen production system and a control method thereof. By setting up an energy storage battery array, the system can adjust the electric energy generated by the photovoltaic array through a photovoltaic direct current power supply to charge the energy storage battery array, rather than directly supplying it to an alkaline water electrolyzer, thereby reducing the impact of the output fluctuation of the photovoltaic array on the hydrogen production end; by setting up a battery management system and a power energy management system, the battery management system can be used to detect the battery charge state of the energy storage battery array, and the power energy management system can be used to adjust the total amount of electric energy delivered by the energy storage battery array to the alkaline water electrolyzer according to the battery charge state detected by the battery management system, thereby balancing the output fluctuation of the photovoltaic power generation end due to weather changes under the premise of stabilizing the system power output. In summary, the above technical scheme can reduce the feedback time required for system adjustment and the time required to execute control commands.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production, and in particular to a photovoltaic direct current coupled hydrogen production system and a control method thereof. Background Art

[0002] Hydrogen energy has the advantages of diverse sources, clean and low carbon, and rich application scenarios, and is a very promising energy form in the future. Photovoltaic water electrolysis hydrogen production has the advantages of high purity, pollution-free products, and simple preparation process. It has great advantages and development space in the green production of hydrogen energy.

[0003] At present, some large-scale photovoltaic water electrolysis hydrogen production projects in China have entered the engineering implementation stage, but the photovoltaic direct current grid (DC-DC) water electrolysis hydrogen production system is still in the research stage. The difficulty in building a photovoltaic direct current grid (DC-DC) water electrolysis hydrogen production system lies in balancing the output fluctuations of the photovoltaic power generation end caused by weather changes under the premise of stabilizing the system power output.

[0004] Therefore, there is an urgent need to provide a photovoltaic DC coupled hydrogen production system and a control method thereof to solve the above technical problems. Summary of the invention

[0005] The present invention provides a photovoltaic direct current coupled hydrogen production system and a control method thereof, which can balance the output fluctuation of the photovoltaic power generation end caused by weather changes under the premise of stabilizing the system power output.

[0006] In a first aspect, an embodiment of the present invention provides a photovoltaic DC-coupled hydrogen production system, comprising a photovoltaic array, a photovoltaic DC power supply, an energy storage battery array, a hydrogen production DC power supply and an alkaline water electrolyzer connected in sequence, and also comprising a large power grid, a photovoltaic maximum power point tracking system, a battery management system and a power energy management system, wherein the output end of the photovoltaic DC power supply is also connected to the large power grid, the photovoltaic DC power supply is also connected to the photovoltaic maximum power point tracking system, the energy storage battery array, the battery management system and the power energy management system are connected in sequence, and the power energy management system is connected to the hydrogen production DC power supply;

[0007] The photovoltaic array is used to convert incident light energy into direct current power and charge the energy storage battery array after being regulated by the photovoltaic direct current power supply;

[0008] The photovoltaic maximum power point tracking system is used to ensure that the output power of the photovoltaic array is maintained at the maximum power point by adjusting the voltage, and to maximize the charging power supplied to the energy storage battery array;

[0009] The battery management system is used to detect the battery charge state of the energy storage battery array;

[0010] The power energy management system is used to adjust the total amount of electric energy delivered by the energy storage battery array to the alkaline water electrolyzer according to the battery charge state detected by the battery management system.

[0011] In a second aspect, an embodiment of the present invention provides a photovoltaic direct current coupled hydrogen production method, comprising:

[0012] The photovoltaic array is used to convert incident light energy into direct current power and then charges the energy storage battery array after being regulated by the photovoltaic direct current power supply;

[0013] The photovoltaic maximum power point tracking system is used to ensure that the output power of the photovoltaic array is maintained at the maximum power point by adjusting the voltage, and the charging power supplied to the energy storage battery array is maximized;

[0014] Utilizing the battery management system to detect the battery charge state of the energy storage battery array;

[0015] The power energy management system is used to adjust the total amount of electric energy delivered to the alkaline water electrolyzer by the energy storage battery array according to the battery charge state detected by the battery management system.

[0016] It can be seen from the above scheme that the photovoltaic DC coupled hydrogen production system provided by the present invention provides a stable power supply for the alkaline water electrolyzer through the energy storage battery array and the power energy management system; by setting the energy storage battery array, the electric energy generated by the photovoltaic array can be regulated by the photovoltaic DC power supply to charge the energy storage battery array, rather than directly supplied to the alkaline water electrolyzer, so that the impact of the output fluctuation of the photovoltaic array on the hydrogen production end can be reduced, and at the same time, the large power grid is also connected in parallel with the energy storage battery array to provide partial voltage support and the function of surplus power access to the grid; the energy storage battery array provides electric energy to the hydrogen production end when there is a surplus of electric energy storage, and can control the amount of electricity delivered to the alkaline water electrolyzer by adjusting the hydrogen production DC power supply; by setting the battery management system and the power energy management system, the battery management system can be used to detect the battery charge state of the energy storage battery array, and the power energy management system can be used to adjust the total amount of electric energy delivered to the alkaline water electrolyzer by the energy storage battery array according to the battery charge state detected by the battery management system, so that the output fluctuation of the photovoltaic power generation end caused by weather changes can be balanced under the premise of stabilizing the system power output. In summary, the above technical solution can reduce the feedback time required for system regulation and the time required to execute control commands, and because the control loop is mainly built around the energy storage battery array, the load level of the entire control system can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of a photovoltaic DC-coupled hydrogen production system provided in an embodiment of the present invention;

[0019] Figure 2 A basic control logic diagram of a battery management system provided by an embodiment of the present invention;

[0020] Figure 3 A basic control logic diagram of a power energy management system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] As mentioned above, in the related art, the photovoltaic output power is usually adjusted by a control algorithm (such as maximum power point tracking MPPT), but the adjustment range is limited. Moreover, in the case of a lag in the system adjustment time, the architecture constructed in this way may cause the water electrolysis hydrogen production system to become unstable when the photovoltaic power generation power fluctuates greatly. For the water electrolysis hydrogen production system, an excessively large system power change rate will lead to unstable hydrogen production and an imbalance in the hydrogen-oxygen ratio, resulting in a decrease in hydrogen quality and causing safety hazards. Therefore, it is particularly important to improve the stability of the photovoltaic DC grid-type water electrolysis hydrogen production system.

[0023] In order to solve this technical problem, Figure 1 As shown, one embodiment of the present invention provides a photovoltaic DC coupled hydrogen production system, comprising a photovoltaic array, a photovoltaic DC power supply, an energy storage battery array, a hydrogen production DC power supply and an alkaline water electrolyzer connected in sequence, and also comprising a large power grid, a photovoltaic maximum power point tracking system, a battery management system and a power energy management system, wherein the output end of the photovoltaic DC power supply is also connected to the large power grid, the photovoltaic DC power supply is also connected to the photovoltaic maximum power point tracking system, the energy storage battery array, the battery management system and the power energy management system are connected in sequence, and the power energy management system is connected to the hydrogen production DC power supply;

[0024] The photovoltaic array is used to convert incident light energy into DC power and charge the energy storage battery array after being regulated by the photovoltaic DC power supply;

[0025] The photovoltaic maximum power point tracking system is used to ensure that the output power of the photovoltaic array is maintained at the maximum power point by adjusting the voltage and maximizing the charging energy supplied to the energy storage battery array;

[0026] The battery management system is used to detect the battery charge status of the energy storage battery array;

[0027] The power energy management system is used to adjust the total amount of electric energy delivered to the alkaline water electrolyzer by the energy storage battery array according to the battery charge state detected by the battery management system.

[0028] In this embodiment, a stable power supply is provided for the alkaline water electrolyzer through an energy storage battery array and a power energy management system; by setting up an energy storage battery array, the electric energy generated by the photovoltaic array can be regulated by a photovoltaic DC power supply to charge the energy storage battery array, rather than directly supplied to the alkaline water electrolyzer, so that the impact of the output fluctuation of the photovoltaic array on the hydrogen production end can be reduced, and at the same time, the large power grid is also connected in parallel with the energy storage battery array to provide partial voltage support and the function of surplus power access to the grid; the energy storage battery array provides electric energy to the hydrogen production end when there is a surplus of electric energy storage, and can control the amount of electricity delivered to the alkaline water electrolyzer by adjusting the hydrogen production DC power supply; by setting up a battery management system and a power energy management system, the battery management system can be used to detect the battery charge state of the energy storage battery array, and the power energy management system can be used to adjust the total amount of electric energy delivered to the alkaline water electrolyzer by the energy storage battery array according to the battery charge state detected by the battery management system, so that the output fluctuation of the photovoltaic power generation end caused by weather changes can be balanced under the premise of stabilizing the system power output. In summary, the above technical solution can reduce the feedback time required for system regulation and the time required to execute control commands, and because the control loop is mainly built around the energy storage battery array, the load level of the entire control system can be reduced.

[0029] In one embodiment of the present invention, the photovoltaic DC power supply and the hydrogen production DC power supply both include one or more groups of DC conversion units.

[0030] In one embodiment of the present invention, when there are multiple groups of photovoltaic DC power supplies, each group of photovoltaic DC power supplies is connected to the photovoltaic maximum power point tracking system through a communication line.

[0031] In one embodiment of the present invention, when there are multiple groups of hydrogen-producing DC power supplies, each group of hydrogen-producing DC power supplies is connected to the power energy management system via a communication line.

[0032] In one embodiment of the present invention, the energy storage battery array includes one or more battery groups. The energy storage battery array is composed of multiple energy storage battery groups connected in parallel and in series, and performs signal interaction with the battery management system (BMS) of the device-level manager. When the system is running, different battery groups are charged and discharged in stages.

[0033] In one embodiment of the present invention, when there are multiple groups of energy storage battery arrays, each group of energy storage battery arrays is connected to the battery management system via a communication line.

[0034] In one embodiment of the present invention, the alkaline water electrolysis cells are in one or more groups.

[0035] With a hydrogen production capacity of 1000Nm 3 Taking the alkaline water electrolyzer power supply of 100 MW / h as an example, after preliminary calculation, the system provided by the embodiment of the present invention has the following product characteristics: photovoltaic array efficiency (23.77%), DC power supply efficiency (98.7%), energy storage component maximum efficiency (97%), alkaline water electrolyzer efficiency (78%), system power factor (≥0.94), and system efficiency (95.74%).

[0036] In addition, an embodiment of the present invention further provides a control method of the system mentioned in the above embodiment, including:

[0037] The photovoltaic array is used to convert the incident light energy into DC power and then charges the energy storage battery array after being regulated by the photovoltaic DC power supply;

[0038] The photovoltaic maximum power point tracking system is used to ensure that the output power of the photovoltaic array is maintained at the maximum power point by adjusting the voltage, and to maximize the charging energy supplied to the energy storage battery array;

[0039] Using a battery management system to detect the battery charge state of the energy storage battery array;

[0040] The power energy management system is used to adjust the total amount of electric energy delivered to the alkaline water electrolyzer by the energy storage battery array according to the battery charge state detected by the battery management system.

[0041] It can be understood that the method embodiment and system embodiment provided by the present invention are based on the same inventive concept and have the same beneficial effects, and the beneficial effects of the method embodiment will not be elaborated herein.

[0042] like Figure 2 As shown, in one embodiment of the present invention, the method further includes:

[0043] Use the battery management system to perform the following operations:

[0044] Determine the current input electrical parameters of the energy storage battery array; wherein the electrical parameters include at least one of power, current and voltage;

[0045] Determine whether the input power of the energy storage battery array is less than the maximum charge capacity of the energy storage battery; if so, charge the energy storage battery array; if not, connect the remaining power to the grid;

[0046] Control the actual output electrical parameters of the energy storage battery array under the corresponding working state.

[0047] In the photovoltaic DC coupled hydrogen production system, the photovoltaic array absorbs sunlight and outputs DC power; the system starts up after receiving a power-on command. After starting up, the system controller will control the working state of each system power supply component; for example, the system controller sends an output electrical parameter command to the hydrogen production power supply, so that the hydrogen production power supply controller performs corresponding actions according to the output electrical parameter command.

[0048] like Figure 3 As shown, in one embodiment of the present invention, the method further includes:

[0049] Use the power energy management system to perform the following operations:

[0050] Receiving output electrical parameter instructions;

[0051] Determine the current input electrical parameters of the hydrogen production DC power supply;

[0052] Determine the current output electrical parameters of the hydrogen production DC power supply;

[0053] Determine whether the hydrogen production DC power supply is greater than or equal to the current minimum remaining power of the energy storage battery array; if so, control the hydrogen production DC power supply to supply power to the alkaline water electrolyzer; if not, control the hydrogen production DC power supply not to supply power to the alkaline water electrolyzer;

[0054] Control the actual output electrical parameters of the hydrogen production DC power supply train under the corresponding working state.

[0055] In this photovoltaic DC-coupled hydrogen production system, according to the state of charge (SOC) of the energy storage battery array, when the current photovoltaic array output power is less than the maximum storage capacity of the energy storage battery array, the energy storage battery array is charged, otherwise the power is transmitted to the large power grid. The power supply energy management system (EMS) is the upper-level management system of the battery management system (BMS). According to the power required by the hydrogen production end (alkaline water electrolyzer), the system supplies power to the alkaline water electrolyzer when there is sufficient remaining power in the energy storage battery array, and can adjust the hydrogen production DC power supply to make a certain amount of load change according to the battery pack charge feedback from the battery management system.

[0056] It should be noted that, in the present invention, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0057] Finally, it should be noted that the above is only a preferred embodiment of the present invention, which is only used to illustrate the technical solution of the present invention, and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A control method for a photovoltaic DC-coupled hydrogen production system, characterized in that: The system includes a photovoltaic array, a photovoltaic DC power supply, an energy storage battery array, a hydrogen production DC power supply and an alkaline water electrolyzer connected in sequence, and also includes a large power grid, a photovoltaic maximum power point tracking system, a battery management system and a power energy management system. The output end of the photovoltaic DC power supply is also connected to the large power grid, the photovoltaic DC power supply is also connected to the photovoltaic maximum power point tracking system, the energy storage battery array, the battery management system and the power energy management system are connected in sequence, and the power energy management system is connected to the hydrogen production DC power supply; The method comprises: The photovoltaic array is used to convert incident light energy into direct current power and then charges the energy storage battery array after being regulated by the photovoltaic direct current power supply; The photovoltaic maximum power point tracking system is used to ensure that the output power of the photovoltaic array is maintained at the maximum power point by adjusting the voltage, and the charging power supplied to the energy storage battery array is maximized; Utilizing the battery management system to detect the battery charge state of the energy storage battery array; Using the power energy management system to adjust the total amount of electric energy delivered to the alkaline water electrolyzer by the energy storage battery array according to the battery charge state detected by the battery management system; Also includes: The battery management system is used to perform the following operations: Determine the current input electrical parameters of the energy storage battery array; wherein the electrical parameters include at least one of current and voltage; Determine whether the input power of the energy storage battery array is less than the maximum charge capacity of the energy storage battery; if so, charge the energy storage battery array; if not, connect the remaining power to the grid; Controlling the actual output electrical parameters of the energy storage battery array in a corresponding working state; Also includes: The power energy management system is used to perform the following operations: Receiving output electrical parameter instructions; Determining current input electrical parameters of the hydrogen production DC power supply; Determining current output electrical parameters of the hydrogen production DC power supply; Determine whether the hydrogen production DC power supply is greater than or equal to the current minimum remaining power of the energy storage battery array; if so, control the hydrogen production DC power supply to supply power to the alkaline water electrolyzer; if not, control the hydrogen production DC power supply not to supply power to the alkaline water electrolyzer; Control the actual output electrical parameters of the hydrogen production DC power supply train in a corresponding working state.

2. The method according to claim 1, characterized in that The photovoltaic DC power supply and the hydrogen production DC power supply both include one or more groups of DC conversion units.

3. The method according to claim 2, characterized in that When there are multiple groups of photovoltaic direct current power sources, each group of photovoltaic direct current power sources is connected to the photovoltaic maximum power point tracking system via a communication line.

4. The method according to claim 2, characterized in that: When there are multiple groups of hydrogen-producing DC power supplies, each group of the hydrogen-producing DC power supplies is connected to the power energy management system via a communication line.

5. The method according to claim 1, characterized in that: The energy storage battery array includes one or more battery groups.

6. The method according to claim 5, characterized in that When there are multiple groups of energy storage battery arrays, each group of energy storage battery arrays is connected to the battery management system via a communication line.

7. The method according to claim 1, characterized in that The alkaline water electrolyzers are in one or more groups.

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