Off-grid new energy hydrogen production system

Abstract

The invention discloses an off-grid new energy hydrogen production system, which belongs to the technical field of new energy power generation hydrogen production, and comprises a new energy unit, a new energy end current converter, a direct current line, a hydrogen production end current converter and a hydrogen production unit. The new energy unit outputs alternating current electric energy, and AC / DC conversion is achieved through the new energy end current converter. The direct current line is connected between the new energy end current converter and the hydrogen production end current converter; and the hydrogen production end converter performs DC / AC conversion and is connected to the hydrogen production unit. Under the condition that the new energy power generation equipment is not connected to an alternating current power grid, the hydrogen can be prepared by using the electric energy generated by the new energy power generation equipment, the on-site consumption application of the new energy electric energy is realized, and the stable operation of the new energy hydrogen production system is ensured. Particularly, the output power of the hydrogen production unit is adjusted by adjusting the voltage of the alternating current side of a hydrogen production end converter, and the direct current voltage of the hydrogen production system is stable.

Description

Technical Field

[0001] The present application belongs to the technical field of renewable energy power generation and hydrogen production, and specifically relates to an off-grid renewable energy hydrogen production system. Background Art

[0002] For off-grid new energy hydrogen production systems, since they are separated from the public power grid, they will face certain power balance and system stability issues. Therefore, the system needs to ensure the voltage stability of the entire off-grid system while maintaining the safe and stable operation of the hydrogen production unit. Summary of the invention

[0003] Purpose of the invention: This application develops an off-grid new energy hydrogen production system, which can realize the production of hydrogen by using the electric energy generated by the new energy power generation equipment without being connected to the AC power grid, realize the on-site consumption of new energy electric energy, and ensure the stable operation of the new energy hydrogen production system.

[0004] Technical solution: The embodiment of the present application provides an off-grid new energy hydrogen production system, including:

[0005] New energy unit, new energy end converter, DC line, hydrogen production end converter and hydrogen production unit, including:

[0006] The new energy unit outputs AC power, and the AC / DC conversion is realized through the new energy end converter;

[0007] The DC line is connected between the new energy end converter and the hydrogen production end converter;

[0008] The hydrogen production end converter performs DC / AC conversion and is connected to the hydrogen production unit.

[0009] In some embodiments, the new energy unit includes but is not limited to wind power generation equipment and photovoltaic power generation equipment.

[0010] In some embodiments, the new energy end converter adopts a diode converter.

[0011] In some embodiments, the diode inverter comprises a diode-based three-phase bridge circuit, a transformer and a switch, and the diode inverter is configured to be equipped with an AC filter and / or a reactor.

[0012] In some embodiments, the new energy end converter adopts a voltage source converter.

[0013] In some embodiments, the hydrogen production end converter adopts a voltage source converter.

[0014] In some embodiments, the voltage source converter includes a modular multilevel converter, a transformer and a switch, which can realize AC / DC conversion and DC / AC conversion.

[0015] In some embodiments, the modular multi-level converter includes six bridge arms, each bridge arm includes a plurality of cascaded sub-modules and a series reactor, wherein the cascaded sub-modules adopt a half-bridge structure or a full-bridge structure.

[0016] In some embodiments, the output power of the hydrogen production unit is positively correlated with the voltage on the AC side of the converter at the hydrogen production end.

[0017] In some embodiments, the hydrogen production end converter is configured to adjust the voltage on the AC side of the hydrogen production end converter to adjust the output power of the hydrogen production unit and stabilize the DC voltage of the DC line.

[0018] Beneficial effect: Compared with the prior art, the off-grid new energy hydrogen production system provided in the embodiment of the present application can utilize the electric energy generated by the new energy power generation system to realize electrolytic hydrogen production, and can maintain the stability of the DC voltage of the hydrogen production system, thereby realizing the stable consumption of new energy. Specifically, the output power of the hydrogen production unit is adjusted by adjusting the voltage on the AC side of the converter at the hydrogen production end, thereby achieving the stability of the DC voltage of the hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a schematic diagram of the structure of an off-grid new energy hydrogen production system provided in an embodiment of the present application;

[0021] Figure 2 It is a schematic diagram of the structure of a diode converter provided in an embodiment of the present application;

[0022] Figure 3 is a schematic diagram of another diode converter structure provided in an embodiment of the present application;

[0023] Figure 4 It is a schematic diagram of the structure of a voltage source converter provided in an embodiment of the present application;

[0024] Figure 5 It is a structural schematic diagram of a case where the cascaded submodule in the voltage source converter provided in an embodiment of the present application is a full-bridge structure;

[0025] Figure 6 It is a structural schematic diagram of a case where the cascaded submodule in the voltage source converter provided in an embodiment of the present application is a half-bridge structure;

[0026] Figure 7 is an example block diagram of a DC voltage control method provided in an embodiment of the present application;

[0027] Figure 8 This is a schematic diagram of a hydrogen production unit provided in an embodiment of the present application.

[0028] Figure numerals: 1. New energy unit; 2. Converter at the new energy end; 3. DC line; 4. Converter at the hydrogen production end; 5. Hydrogen production unit; 6. Three-phase bridge circuit based on diode; 7. Transformer; 8. First switch; 9. Reactor; 10. AC filter; 11. Modular multilevel converter; 12. Second switch. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features.

[0031] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention.

[0032] Hydrogen production from electrolysis of new energy is one of the important ways to solve the problem of new energy consumption. The use of new energy electrolysis hydrogen production technology can cope with the uncontrollability and intermittency of new energy power output and other problems, which is conducive to the local consumption of new energy. It has great application prospects for realizing large-scale development of new energy and efficient utilization of new energy in multiple ways.

[0033] See also Figures 1 to 7 As shown, an embodiment of the present application provides an off-grid new energy hydrogen production system, including a new energy unit 1, a new energy end converter 2, a DC line 3, a hydrogen production end converter 4, and a hydrogen production unit 5.

[0034] In the embodiment of the present application, the new energy unit 1 outputs AC power. The new energy unit 1 generally uses renewable energy to generate electricity. These renewable energy sources include solar energy, wind energy, hydropower, geothermal energy, etc.

[0035] In some embodiments, the new energy unit 1 includes but is not limited to new energy power generation equipment such as wind power generation equipment, photovoltaic power generation equipment, hydropower generation equipment, tidal power generation equipment, etc. In the embodiment of the present application, the new energy end converter 2 is connected to the new energy unit 1, and the new energy end converter 2 converts the AC power output by the new energy unit 1 into AC / DC, and then inputs it into the DC line 3.

[0036] In some embodiments, the new energy end converter 2 may adopt a diode converter, which is used to convert alternating current into direct current.

[0037] It should be further explained that the diode converter includes a diode-based three-phase bridge circuit 6, a transformer 7, a first switch 8 and a second switch 12, and can be equipped with devices including but not limited to an AC filter 10 and a reactor 9. The diode-based three-phase bridge circuit 6 is a commonly used circuit topology, which consists of four diodes and is usually used for AC / DC conversion. The transformer 7 can realize functions such as power conversion, insulation isolation and voltage regulation. The first switch 8 and the second switch 12 are switching devices for cutting off or connecting circuits. The AC filter 10 is used to remove harmonic components in the AC voltage and AC current. The reactor 9 is used to suppress DC voltage ripple.

[0038] In one possible implementation, Figure 2 As shown, the diode converter includes a first switch 8, an AC filter 10, a transformer 7, a diode-based three-phase bridge circuit 6, a reactor 9, and a second switch 12, which are connected in sequence.

[0039] In one possible implementation, Figure 3As shown, the diode converter includes a first switch 8, an AC filter 10, and a transformer 7 connected in sequence. The transformer 7 is a three-winding transformer. The two output ends of the three-winding transformer are respectively connected to a diode-based three-phase bridge circuit 6, and the two diode-based three-phase bridge circuits 6 are connected in series; the output ends of the two diode-based three-phase bridge circuits 6 are connected in sequence with a reactor 9 and a second switch 12.

[0040] In some embodiments, the new energy end converter 2 may adopt a voltage source converter. To further explain, the voltage source converter includes a modular multilevel converter 11, a transformer 7, a first switch 8, a second switch 12 and other equipment to achieve AC / DC conversion.

[0041] In one possible implementation, Figure 4 As shown, the voltage source converter includes a first switch 8, a transformer 7, a modular multilevel converter 11, and a second switch 12 connected in sequence to achieve AC / DC conversion.

[0042] In some embodiments, the modular multilevel converter 11 includes six bridge arms, each bridge arm is composed of a plurality of cascaded submodules and a series inductor. The cascaded submodules may adopt, but are not limited to, a half-bridge structure (such as Figure 6 as shown) or full bridge structure (as shown Figure 5 shown).

[0043] In the embodiment of the present application, the DC line 3 is connected between the new energy end converter 2 and the hydrogen production end converter 4. The DC line 3 transmits the DC power converted by the new energy end converter 2 to the hydrogen production end converter 4. In the embodiment of the present application, the hydrogen production end converter 4 performs DC / AC conversion on the DC power input by the DC line 3.

[0044] In some embodiments, the hydrogen production end converter 4 may adopt a voltage source converter. To further explain, the voltage source converter includes a modular multilevel converter 11, a transformer 7, a first switch 8, a second switch 12 and other equipment to achieve DC / AC conversion.

[0045] In one possible implementation, Figure 4 As shown, the voltage source converter includes a first switch 8, a transformer 7, a modular multilevel converter 11, and a second switch 12 which are connected in sequence to achieve DC / AC conversion.

[0046] In some embodiments, the hydrogen production end converter 4 adopts a DC voltage control method, and the hydrogen production end converter 4 is configured to adjust the AC side voltage of the hydrogen production end converter 4 to adjust the output power of the hydrogen production unit 5 and stabilize the DC voltage of the DC line 3.

[0047] In one possible implementation, Figure 7 As shown, the difference between the DC voltage command value and the actual DC voltage value is input into a PI controller, and the AC voltage command value is output after being processed by the PI controller, thereby adjusting the AC side voltage of the hydrogen production end converter 4 to achieve the adjustment of the output power of the hydrogen production unit 5.

[0048] In some embodiments, Figure 8 As shown, the hydrogen production unit 5 includes a first transformer, a first diode-based three-phase bridge circuit, a first reactor and an electrolytic cell. Through this structure, hydrogen production by electrolysis is achieved.

[0049] like Figure 8 As shown, the voltage U at the input end of the first transformer s1 That is, the AC side voltage of the aforementioned hydrogen production end converter 4, the first transformer output voltage U s2 =kU s1 , where k is the first transformer ratio. The AC and DC voltages of the first diode-based three-phase bridge circuit have a relationship U dc =1.35U s2 -x, where U dc is the DC voltage across the electrolytic cell, and x is a variable positively correlated with the load current. Therefore, it can be seen that the DC voltage U across the electrolytic cell dc and the AC side voltage U of the aforementioned hydrogen production end converter 4 s1 The hydrogen production power of the electrolyzer is positively correlated with the DC voltage U at both ends. dc Therefore, the output power of the hydrogen production unit 5 is positively correlated with the AC side voltage of the hydrogen production end converter 4.

[0050] In summary, the off-grid new energy hydrogen production system provided in the embodiment of the present application can utilize the electric energy generated by the new energy power generation system to realize electrolysis hydrogen production, and can maintain the DC voltage of the hydrogen production system stable, thereby realizing the stable consumption of new energy.

[0051] The present application has introduced in detail an off-grid new energy hydrogen production system provided by the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An off-grid new energy hydrogen production system, characterized in that: include: A new energy unit (1), a new energy end converter (2), a DC line (3), a hydrogen production end converter (4) and a hydrogen production unit (5), wherein: The new energy unit (1) outputs alternating current electric energy, and the AC / DC conversion is realized through the new energy end converter (2); The DC line (3) is connected between the new energy end converter (2) and the hydrogen production end converter (4); The hydrogen production end converter (4) performs DC / AC conversion and is connected to the hydrogen production unit (5).

2. An off-grid new energy hydrogen production system as claimed in claim 1, characterized in that: The new energy unit (1) includes but is not limited to wind power generation equipment and photovoltaic power generation equipment.

3. An off-grid new energy hydrogen production system as claimed in claim 1, characterized in that: The new energy end converter (2) adopts a diode converter.

4. An off-grid new energy hydrogen production system as claimed in claim 3, characterized in that: The diode converter comprises a three-phase bridge circuit (6) based on diodes, a transformer (7) and a knife switch (8), and the diode converter is configured to be equipped with an AC filter (10) and / or a reactor (9).

5. The off-grid new energy hydrogen production system according to claim 1, characterized in that: The new energy end converter (2) adopts a voltage source converter.

6. The off-grid new energy hydrogen production system according to claim 1, characterized in that: The hydrogen production end converter (4) adopts a voltage source converter.

7. An off-grid new energy hydrogen production system as claimed in claim 5 or 6, characterized in that: The voltage source converter comprises a modular multi-level converter (11), a transformer (7) and a switch (8), and can realize AC / DC conversion and DC / AC conversion.

8. An off-grid new energy hydrogen production system as claimed in claim 7, characterized in that: The modular multi-level converter (11) comprises six bridge arms, each bridge arm comprises a plurality of cascaded sub-modules and a series reactor (9), wherein the cascaded sub-modules adopt a half-bridge structure or a full-bridge structure.

9. The off-grid new energy hydrogen production system according to claim 1, characterized in that: The output power of the hydrogen production unit (5) is positively correlated with the voltage on the AC side of the hydrogen production end converter (4).

10. The off-grid new energy hydrogen production system according to claim 1, characterized in that: The hydrogen production end converter (4) is configured to adjust the voltage on the AC side of the hydrogen production end converter (4) to adjust the output power of the hydrogen production unit (5) and stabilize the DC voltage of the DC line (3).

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