Isolation circuit for hydrogen production system and renewable energy hydrogen production system comprising same

Abstract

Provided in the present application are an isolation circuit for a hydrogen production system and a renewable energy hydrogen production system comprising same. The isolation circuit comprises at least one direct-current conversion module and at least one DC-AC converter. The direct-current conversion module comprises a single-output port and a multi-output port, the single output port of the direct-current conversion module being in coupled connection with the DC side of the DC-AC converter, the multi-output port of the direct-current conversion module being in coupled connection with a plurality of external unidirectional power flow units and / or bidirectional power flow units, and each unidirectional power flow unit at least comprising a hydrogen production unit. The AC end of each DC-AC converter is in series coupled connection with an external alternating-current power grid or a direct-current power grid. The present solution simultaneously satisfies application requirements of two coupling scenarios, effectively integrates various types of external units, and combines all components in systems into one, thus facilitating positioning of faults and repair while reducing costs. FIG. 1

Description

Isolation circuit for hydrogen production system and renewable energy hydrogen production system including the same

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 28, 2023, with application number 202311279554.5 and invention name “Isolation circuit for hydrogen production system and renewable energy hydrogen production system including the same”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of hydrogen preparation, and in particular to an isolation circuit for a hydrogen production system and a renewable energy hydrogen production system including the isolation circuit. Background Art

[0003] Current system designs for hydrogen production from renewable energy can be categorized as either AC-coupled or DC-coupled. Both approaches employ separate designs for different functional devices or units within the system, leaving the different devices and units largely unrelated in design. This approach not only leads to high system design costs but also makes system expansion difficult. If a system failure occurs, fault identification and repair are extremely difficult.

[0004] Summary of the Invention

[0005] The technical problem to be solved by this application is that in the existing renewable energy hydrogen production scheme, the high cost, difficulty in expansion and difficulty in fault repair are caused by the inability to design the system as a whole due to the independent design of different equipment or units. Therefore, an isolation circuit for a hydrogen production system and a renewable energy hydrogen production system including the same are provided.

[0006] In a first aspect, the technical solution of the present application provides an isolation circuit for a hydrogen production system, comprising:

[0007] At least one DC conversion module, wherein the DC conversion module includes a single output port and a multi-output port;

[0008] at least one DC-AC converter;

[0009] The single output port of the DC conversion module is coupled to the DC side of the DC-AC converter;

[0010] The multiple output ports of the DC conversion module are coupled to multiple external unidirectional power flow units and / or bidirectional power flow units, and the unidirectional power flow unit includes at least a hydrogen production unit;

[0011] The AC end of the DC-AC converter is coupled to an external AC grid or a DC grid in series.

[0012] In some embodiments of the isolation circuit for a hydrogen production system, the unidirectional power flow unit includes a hybrid hydrogen production unit and / or a new energy power generation unit; the hybrid hydrogen production unit includes two or more hydrogen production modules;

[0013] The bidirectional power flow unit includes an energy storage unit.

[0014] In some embodiments of the isolation circuit for a hydrogen production system, a plurality of the unidirectional power flow units are coupled in parallel to the multiple output ports.

[0015] In some solutions of the isolation circuit for the hydrogen production system, when the DC conversion module is connected to the hybrid hydrogen production unit or the new energy power generation unit, the DC conversion module is configured with an isolation unit.

[0016] In a second aspect, the technical solution of the present application provides a renewable energy hydrogen production system, comprising at least one isolation circuit for a hydrogen production system as described in the technical solution of the first aspect, and:

[0017] at least one renewable energy power generation unit, each of the renewable energy power generation units being coupled to an output port of the isolation circuit;

[0018] at least one energy storage unit, wherein the energy storage unit is coupled to an output port of the isolation circuit;

[0019] At least one hydrogen production unit is coupled to an output port of the isolation circuit.

[0020] In some embodiments of the renewable energy hydrogen production system, when the renewable energy power generation unit includes multiple units, the multiple renewable energy power generation units are coupled in parallel to the multiple output ports of the isolation circuit.

[0021] In some embodiments of the renewable energy hydrogen production system, when the renewable energy power generation unit comprises a plurality of units, the plurality of renewable energy power generation units are divided into a plurality of parallel coupling groups;

[0022] The renewable energy generation units in each parallel coupling group are coupled to a parallel coupling port in parallel; and the parallel coupling ports in a plurality of parallel coupling groups are coupled to a plurality of output ports of the isolation circuit in parallel.

[0023] In some embodiments of the renewable energy hydrogen production system, when the hydrogen production unit includes multiple units, the types of the hydrogen production units include at least two.

[0024] In some embodiments of the renewable energy hydrogen production system, the hydrogen production unit includes an alkaline hydrogen production module, a solid oxide hydrogen production module and a PEM hydrogen production module.

[0025] In a third aspect, the technical solution of the present application provides a control method for the renewable energy hydrogen production system described in any one of the above items, comprising:

[0026] Determine the system operating mode according to the type of the unidirectional power flow unit and / or bidirectional power flow unit external to the system;

[0027] If the system operating mode is a new energy infrastructure grid-connected mode: controlling the power path direction of the isolation circuit to achieve a unidirectional power flow direction from a single type of renewable energy power generation unit to the AC or DC bus unit;

[0028] If the system operating mode is the energy storage-based grid-connected charging / discharging mode: controlling the power path direction of the isolation circuit to achieve a bidirectional power flow direction from a single type of energy storage unit to the AC or DC bus;

[0029] If the system operating mode is the grid-connected basic hydrogen production mode: control the power path direction of the isolation circuit to realize the direction of power from the AC or DC bus to the single type of hydrogen production unit.

[0030] The control method of the renewable energy hydrogen production system described in some solutions further includes:

[0031] If the system operating mode is a new energy hybrid grid-connected mode: controlling the power path direction of the isolation circuit to achieve a unidirectional power flow direction from the multiple types of renewable energy power generation units to the AC or DC bus unit;

[0032] If the system operating mode is a hybrid energy storage grid-connected charging / discharging mode: controlling the power path direction of the isolation circuit to achieve a bidirectional power flow direction from the multi-type energy storage unit to the AC or DC bus unit;

[0033] If the system operating mode is a grid-connected hybrid hydrogen production mode: control the power path direction of the isolation circuit to realize the direction of power from the AC or DC bus to the multiple types of hydrogen production units.

[0034] The technical solution of this application has the following technical effects compared with the existing technology:

[0035] The present application provides an isolation circuit for a hydrogen production system and a renewable energy hydrogen production system including the same. The isolation circuit includes at least one DC conversion module and at least one DC-AC converter, wherein the DC conversion module includes a single output port and a multiple output port; the single output port of the DC conversion module is coupled to the DC side of the DC-AC converter; the multiple output ports of the DC conversion module are coupled to multiple external unidirectional power flow units and / or bidirectional power flow units, wherein the unidirectional power flow units include at least a hydrogen production unit; and the AC end of the DC-AC converter is coupled in series with an external AC grid or DC grid. Therefore, this solution has reserved a coupling port for the external AC grid or DC grid, and can be applied to both AC and DC coupling, meeting the application requirements of both coupling scenarios. In actual use, the entire system can be coupled by directly connecting the ports of the unidirectional power flow unit and / or the bidirectional power flow unit to the output port of the isolation circuit. The above-mentioned solution of the present application can effectively integrate various types of external units in a simple manner, integrating various components of the system into one, reducing costs while also facilitating fault location and repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, which will help to understand the objects and advantages of the present application.

[0037] FIG1 is a topological diagram of an isolation circuit for a hydrogen production system according to an embodiment of the present application;

[0038] FIG2 is a topological diagram of an isolation circuit for a hydrogen production system according to another embodiment of the present application;

[0039] FIG3 is a topological diagram of an isolation circuit for a hydrogen production system according to another embodiment of the present application;

[0040] FIG4 is a structural block diagram of a renewable energy hydrogen production system according to an embodiment of the present application;

[0041] FIG5 is a structural block diagram of a renewable energy hydrogen production system according to another embodiment of the present application;

[0042] FIG6 is a structural block diagram of a renewable energy hydrogen production system according to another specific example of the present application;

[0043] FIG7 is a topological diagram of a DC / DC converter according to an embodiment of the present application;

[0044] FIG8 is a schematic diagram of the topology of an AC / DC converter according to an embodiment of the present application;

[0045] FIG9 is a flow chart of a control method for a renewable energy hydrogen production system according to an embodiment of the present application. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0047] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0049] This embodiment provides an isolation circuit for a hydrogen production system, as shown in FIG1 to FIG3 , including:

[0050] At least one DC conversion module and at least one DC-AC converter; as shown in the dashed box in the figure, the DC conversion module is formed by combining multiple internal DC-AC converters and one internal AC-DC converter, and includes a single output port and a multiple output port. The single output port of the DC conversion module is coupled to the DC side of an external DC-AC converter; the multiple output ports of the DC conversion module are coupled to multiple external unidirectional power flow units and / or bidirectional power flow units, wherein the unidirectional power flow units include at least a hydrogen production unit; wherein the AC end of the external DC-AC converter is coupled in series with an external AC grid or DC grid.

[0051] In Figures 1 to 3, when the DC conversion module is externally connected to a renewable energy power generation unit or a hydrogen production unit, the DC conversion module can adopt a conversion module with a DC-DC function with an isolation function, that is, a combined structure including a DC-AC converter and an AC-DC converter is used. As shown in Figure 3, if the DC conversion module is externally connected to an energy storage unit, it can be directly connected to a DC-DC converter with a DC conversion function without adding an isolation function.

[0052] The isolation circuit provided in the above embodiment includes at least one DC conversion module and at least one DC-AC converter. The DC conversion module includes a single output port and a multi-output port. The single output port of the DC conversion module is coupled to the DC side of the DC-AC converter. The multi-output ports of the DC conversion module are coupled to multiple external unidirectional power flow units and / or bidirectional power flow units, each of which includes at least a hydrogen production unit. The AC end of the DC-AC converter is coupled in series with an external AC grid or DC grid. Therefore, this solution has reserved coupling ports for the external AC grid or DC grid, and can be used for both AC and DC coupling, meeting the application requirements of both coupling scenarios. In actual use, the entire system can be coupled by directly connecting the ports of the unidirectional power flow unit and / or the bidirectional power flow unit to the output port of the isolation circuit. The above-mentioned solution of the present application can effectively integrate various types of external units in a simple manner, integrating various components of the system into one, reducing costs while also facilitating fault location and repair.

[0053] In the above solution, the unidirectional power flow unit includes a hybrid hydrogen production unit and / or a new energy power generation unit; the hybrid hydrogen production unit includes two or more hydrogen production modules; and the bidirectional power flow unit includes an energy storage unit. In specific implementation, the number and type of unidirectional power flow units and bidirectional power flow units required can be configured based on the actual application scenario. Multiple unidirectional power flow units are coupled in parallel to the multiple output ports.

[0054] An embodiment of the present application also provides a renewable energy hydrogen production system, as shown in Figures 4 and 5, comprising at least one isolation circuit for a hydrogen production system according to any one of the above embodiments, and at least one renewable energy power generation unit, each of the renewable energy power generation units being coupled and connected to an output port of the isolation circuit; at least one energy storage unit, the energy storage unit being coupled and connected to an output port of the isolation circuit; and at least one hydrogen production unit, the hydrogen production unit being coupled and connected to an output port of the isolation circuit.

[0055] Through the above scheme, the isolation circuit can establish a hydrogen production system architecture that fully adapts to the volatility of renewable energy as needed by connecting different functional units. The renewable energy power generation unit is connected to the isolation circuit, and the isolation circuit is also connected to the hydrogen production unit and energy storage unit. With this system, when the energy generated by the renewable energy power generation unit fluctuates, the power-type hydrogen production unit can be directly used to adjust and compensate for short-term fluctuations based on the time scale of the fluctuation. For long-term fluctuations, the energy-type hydrogen production unit can be used to adjust and compensate. The power-type and energy-type energy storage units are used to compensate and optimize the self-regulation capabilities of the power-type and energy-type hydrogen production units, achieving the dual requirements of steady-state energy balance and dynamic power tracking in the hydrogen production application of the entire new energy power generation process.

[0056] As shown in Figures 4 and 5, the system architecture and topology of the renewable energy hydrogen production system mainly include four scalable layers:

[0057] (1) When the bottom submodule ISub Module is a multi-port high-frequency isolated DC-DC module, the multi-port side can couple and connect multiple renewable energy power generation units, energy storage units, and hydrogen production units, and its coupling connection method is to achieve i groups of multiple energy units in parallel through the above-mentioned isolation circuit with isolation function, where i can be expanded according to application requirements. Assuming that the number of renewable energy power generation units is u, the number of energy storage units is v, and the number of electrolyzers of the hydrogen production unit is w, then i satisfies the following formula: i = u + v + w, where u, v, and w can all be expanded according to requirements.

[0058] (2) The bottom submodule ISub Module is a multi-port unidirectional flow energy device of the same type. J groups of energy devices can be directly connected in parallel to meet scale requirements. The number j can be expanded according to application requirements.

[0059] (3) When the middle-level submodule (i.e., the external DC-AC converter is a non-isolated DC-AC module), the single-port DC end of the bottom-level submodule (ISubModule) is connected to the DC end of the DC-AC converter of the middle-level submodule (ISubModule). The AC end of the middle-level submodule (ISubModule) can be connected to the AC bus coupling end after connecting n groups in series (or connected to the DC bus coupling end based on the MMC connection method), where n can be expanded according to application requirements.

[0060] (4) The middle-level sub-modules are connected in series to form an upper-level cascade system. The upper-level cascade system can be implemented in either an AC connection structure or a DC connection structure. m groups of upper-level cascade systems can be connected in parallel via an AC bus or a DC bus to form an overall cascade architecture. The number m can be expanded according to application requirements.

[0061] Since four scalable levels are used to form a scalable architecture for renewable energy hydrogen production, the power allocation and optimization of different types of energy devices can be optimized, combined and calculated according to the following maximum power allocation boundaries.

[0062] The maximum power generation capacity of renewable energy power generation unit satisfies the formula

[0063] The maximum charging and discharging power range of the energy storage unit satisfies the formula

[0064] The maximum power demand of the hydrogen production unit meets the public notice

[0065] In the above formula, 3 refers to three phases, n is the number of series stages of the middle-level submodules, m is the number of parallel stages of the upper-level cascade system, px represents the power of the x-th new energy power generation unit, py represents the power of the y-th energy storage unit, and pz represents the power of the z-th hydrogen production unit.

[0066] Based on the above architecture, according to the type of unidirectional power flow units and / or bidirectional power flow units connected to the system, this solution proposes a two-level working mode optimization method, namely, a single combination mode and a hybrid combination mode. The difference is that the single combination mode mainly considers a single power flow path in a single direction, while the hybrid combination mode mainly considers a combination of two power flow paths in more than two directions.

[0067] (1) The specific definition of a single combination model is as follows:

[0068] 1.1 If the system operating mode is the new energy infrastructure grid-connected mode: control the power path direction of the isolation circuit to achieve a unidirectional power flow direction from a single type of renewable energy power generation unit to the AC or DC bus unit.

[0069] 1.2 If the system operating mode is the energy storage-based grid-connected charging / discharging mode: control the power path direction of the isolation circuit to achieve bidirectional power flow from a single type of energy storage unit to the AC or DC bus unit.

[0070] 1.3 If the system operating mode is the grid-connected basic hydrogen production mode: control the power path direction of the isolation circuit to realize the direction of power from the AC or DC bus to the single type of hydrogen production unit.

[0071] (2) The specific definition of the hybrid combination model is as follows:

[0072] 2.1 If the system operating mode is the new energy hybrid grid-connected mode Mrex: control the power Pmrex path direction of the isolation circuit to achieve a unidirectional power flow direction from the multi-type renewable energy power generation unit to the AC or DC bus unit.

[0073] 2.2 If the system operating mode is the energy storage hybrid grid-connected charging / discharging mode (Mesx1 / Mesx2): control the power (Pmesx1 / Pmesx2) path direction of the isolation circuit to achieve bidirectional power flow from multiple types of energy storage units to the AC or DC bus unit.

[0074] 2.3 If the system operating mode is the grid-connected hybrid hydrogen production mode Melx: control the power Pmelx path direction of the isolation circuit to realize the direction of power from the AC or DC bus to the multi-type hydrogen production unit.

[0075] The six combined modes above form the basic application modes of the architecture. By repeatedly stacking these six combined modes, comprehensive coverage of power flow control in all system scenarios can be achieved. Typical implementation combinations are shown in Table 1.

[0076] Table 1 System working mode combination example table

[0077] As shown in Table 1, depending on the operating mode, a green hydrogen index can be defined based on the renewable energy utilization rate during the hydrogen production process, which is used to determine the optimal principle for the hydrogen production process. The second and fourth mode combinations have the highest green hydrogen index and are the highest priority hydrogen production modes. The sixth and seventh mode combinations have high and very high green hydrogen indices, respectively, primarily determined by whether the energy storage power is sourced entirely from renewable energy. The third mode combination has a medium green hydrogen index, determined by whether the power supply from the grid is sourced from renewable energy. The green hydrogen index is low in the two scenarios of the first mode combination, primarily providing auxiliary support such as stability for the hydrogen production process.

[0078] This solution uses an extended design with multi-port high-frequency isolation, which allows simultaneous access to other types of energy units besides the hydrogen production unit electrolyzer, such as energy storage units and renewable energy power generation units. This allows for more direct coupling of renewable energy generation to the electrolyzer hydrogen production, while also enabling smoothing and stability control through energy storage. Furthermore, multi-port isolation also facilitates the integration of different hydrogen production units. For example, by simultaneously accessing an alkaline electrolyzer and a PEM electrolyzer, the complementary characteristics of the two hydrogen production devices can be fully utilized to establish a more cost-effective hybrid hydrogen production mode and control. Furthermore, the underlying submodule ISub Module can be expanded in parallel between similar energy devices with unidirectional flow, thus enabling the integration of large-capacity alkaline electrolyzers of different levels. For example, for alkaline electrolyzers with currents exceeding 10,000 amperes, the operating current of the underlying submodule ISub Module can be made more reasonable by properly selecting the j value, thereby optimizing the design of the underlying submodule ISub Module and improving the cost-effectiveness of the system.

[0079] Figures 6 to 8 are a specific embodiment of a hybrid hydrogen production system for an AC power grid. The isolation circuit shown in Figure 6 serves as the underlying submodule ISub Module, and the underlying submodule ISub Module is composed of an isolated DC-DC converter with a single-ended output. Its circuit topology is not limited to series resonance, phase-shifted full-bridge, LLC, etc. In the structure shown in Figure 6, the number of new energy power generation units is zero, the number of energy storage units is zero, and the number of hydrogen production units is 2. And because the hydrogen production unit belongs to a unidirectional flow type energy device, the architecture shown in Figure 6 can realize j groups of direct parallel connection to meet scale requirements. In specific implementation, in this embodiment, 150 modules (3 phases) and 60 modules of the alkaline hydrogen production module and the PEM hydrogen production module are respectively connected in parallel. Figure 7 shows an implementation method of each DC-DC converter in Figure 6, and Figure 8 shows an implementation method of the DC-AC converter in Figure 6 (the DC side is connected to the DC-DC converter, and the AC side is connected to the power grid via an inductor). A DC-AC converter connected to the bottom-level submodule ISub Module serves as a mid-level DC-AC module. The mid-level DC-AC module is an H-bridge circuit. The hydrogen production unit includes an alkaline hydrogen production unit (ALK) and a PEM hydrogen production unit. Assuming a grid voltage of 35 kV, an isolated DC / DC converter gain of 1, and a minimum operating voltage (Udc_min) of 500 V for the hydrogen production unit, the minimum number of cascaded mid-level submodules per phase is calculated to be N = 65.

[0080] Where Us is the rated voltage of the power grid; k v k is the correction coefficient under the condition of maximum fluctuation of grid voltage, which is 1.07; b k is the correction coefficient for the most severe voltage imbalance, which is 1.02; L It is the correction coefficient of the maximum voltage drop of the grid-connected reactance and is taken as 1.1.

[0081] To improve system reliability, a 5% redundancy design is considered, and the total number of Sub Modules per phase of the system is set to 70. Since the power of the alkaline electrolyzer is much higher than that of the PEM electrolyzer and is greater than the maximum power handling capacity of a single module, parallel connection can be performed at the output of the ISub Module. The specific number of parallel connections should be determined based on the power ratio of the alkaline electrolysis system to the PEM electrolysis system. Assuming that the power ratio of the alkaline hydrogen production system to the PEM hydrogen production system is 5:2, 50 ISub Module outputs in each phase should be connected in parallel to the alkaline hydrogen production system, and 20 ISub Module outputs should be connected in parallel to the PEM hydrogen production system. Since the phases of phases A, B, and C differ by 120°, parallel connection can further reduce the current ripple of the input electrolysis system.

[0082] Taking into account that the response speed of the PEM hydrogen production unit is much faster than that of the alkaline hydrogen production system, the power flowing into the alkaline system and the PEM hydrogen production system can be flexibly modulated by controlling the voltage on the AC side of the Sub Module, so as to quickly respond to and accurately track the dispatch instructions of the power grid, that is, by controlling the voltage gain ratio of the DC-DC in the bottom sub-module, the current distribution ratio and the current change rate of the DC-DC can be controlled to meet the dynamic needs of different hydrogen production units. The system architecture of the present application itself realizes high voltage by connecting different units in series, and does not require a step-down transformer, so it can be beneficial to improve the response speed. In addition, the cascade topology in this scheme can be regarded as multiple small power supplies (AC-DC+DC-DC) connected in parallel and then connected to the hydrogen production unit, because for the same converter topology, the smaller the power supply power, the smaller the inductance value required. Therefore, compared with a single large power supply, the dynamic characteristics of this scheme are good. In the scheme of the present application, multiple modules in the three phases A, B, and C are connected in parallel to naturally produce staggered parallel operation characteristics, which can further offset the ripple current, thereby reducing the required filter inductance value and improving the dynamic characteristics.

[0083] The present application also provides a control method for the renewable energy hydrogen production system described in any one of the above embodiments, as shown in FIG9 , including:

[0084] S100: Determine a system operating mode according to the type of a unidirectional power flow unit and / or a bidirectional power flow unit external to the system.

[0085] S211: If the system operating mode is the new energy basic grid-connected mode: control the power path direction of the isolation circuit to realize the unidirectional power flow direction from a single type of renewable energy power generation unit to the AC or DC bus.

[0086] S212: If the system operating mode is the energy storage-based grid-connected charging / discharging mode: control the power path direction of the isolation circuit to achieve a bidirectional power flow direction from a single-type energy storage unit to an AC or DC bus.

[0087] S213: If the system operating mode is the grid-connected basic hydrogen production mode: control the power path direction of the isolation circuit to realize the direction of power from the AC or DC bus to the single type of hydrogen production unit.

[0088] S221: If the system operating mode is a new energy hybrid grid-connected mode: control the power path direction of the isolation circuit to achieve a unidirectional power flow direction from multiple types of renewable energy power generation units to the AC or DC bus.

[0089] S222: If the system operating mode is the energy storage hybrid grid-connected charging / discharging mode: control the power path direction of the isolation circuit to achieve a bidirectional power flow direction from the multi-type energy storage unit to the AC or DC bus unit.

[0090] S223: If the system operating mode is a grid-connected hybrid hydrogen production mode: control the power path direction of the isolation circuit to realize the direction of power from the AC or DC bus to the multiple types of hydrogen production units.

[0091] Through the above-mentioned scheme of the present application, the scale of the renewable energy hydrogen production process can be guaranteed, and the AC coupling or DC coupling requirements in both grid-connected and off-grid modes can be met. The high-frequency isolation multi-port characteristics of the isolation circuit are utilized to optimize the energy flow paths and processes of different hydrogen production modes and renewable energy and energy storage. This cascaded large-scale renewable energy hydrogen production system control method based on high-frequency isolation multi-port modules can greatly improve the adaptability of the hydrogen production process to the volatility of renewable energy and the level of equipment utilization, further optimize the standardized combination and modular production of large-scale renewable energy hydrogen production structures, reduce system architecture and control customization, complexity and operation and maintenance costs, thereby improving system reliability, safety and economy.

[0092] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. An isolation circuit for a hydrogen production system, characterized in that: include: At least one DC conversion module, the DC conversion module comprising a single output port and a multi-output port; at least one DC-AC converter; The single output port of the DC conversion module is coupled and connected to the DC side of the DC-AC converter; The multiple output ports of the DC conversion module are coupled to multiple external unidirectional power flow units and / or bidirectional power flow units, and the unidirectional power flow unit at least includes a hydrogen production unit; The AC side of the DC-AC converter is coupled to an external AC grid or a DC grid in series.

2. The isolation circuit for a hydrogen production system according to claim 1, characterized in that: The unidirectional power flow unit includes a hybrid hydrogen production unit and / or a new energy power generation unit; the hybrid hydrogen production unit includes two or more hydrogen production modules; The bidirectional power flow unit includes an energy storage unit.

3. The isolation circuit for a hydrogen production system according to claim 2, characterized in that: A plurality of the unidirectional power flow units are coupled to the multiple output ports in parallel.

4. The isolation circuit for a hydrogen production system according to claim 2, characterized in that: When the DC conversion module is connected to the hybrid hydrogen production unit or the new energy power generation unit, the DC conversion module is configured with an isolation unit.

5. A renewable energy hydrogen production system, characterized in that: The invention comprises at least one isolation circuit for a hydrogen production system according to any one of claims 1 to 4, and: At least one renewable energy power generation unit, each of the renewable energy power generation units is coupled to an output port of the isolation circuit; At least one energy storage unit, the energy storage unit is coupled to an output port of the isolation circuit; At least one hydrogen production unit, the hydrogen production unit is coupled to an output port of the isolation circuit Close connection.

6. The renewable energy hydrogen production system according to claim 5, characterized in that: When the renewable energy generation unit comprises a plurality of units, the plurality of renewable energy generation units are coupled to the plurality of output ports of the isolation circuit in parallel.

7. The renewable energy hydrogen production system according to claim 5, characterized in that: When the renewable energy generation unit comprises a plurality of units, the plurality of renewable energy generation units are divided into a plurality of parallel coupling groups; The renewable energy generation units in each of the parallel coupling groups are coupled to the parallel coupling ports in a parallel manner; and the parallel coupling ports in a plurality of the parallel coupling groups are coupled to the plurality of output ports of the isolation circuit in a parallel manner.

8. The renewable energy hydrogen production system according to claim 5, characterized in that: When the hydrogen production unit includes a plurality of units, the types of the hydrogen production units include at least two.

9. The renewable energy hydrogen production system according to claim 8, characterized in that: The hydrogen production unit comprises an alkaline hydrogen production module, a solid oxide hydrogen production module and a PEM hydrogen production module.

10. A control method for a renewable energy hydrogen production system according to any one of claims 5 to 9, characterized in that: include: Determine the system operation mode according to the type of the unidirectional power flow unit and / or the bidirectional power flow unit external to the system; If the system operation mode is a new energy basic grid-connected mode: control the power path direction of the isolation circuit to achieve a unidirectional power flow direction of power from a single type of renewable energy generation unit to an AC or DC bus unit; If the system operation mode is the energy storage-based grid-connected charging / discharging mode: control the power path direction of the isolation circuit to achieve the direction of bidirectional power flow from a single type of energy storage unit to an AC or DC bus unit; If the system operating mode is a grid-connected basic hydrogen production mode: control the power path direction of the isolation circuit to realize the direction of power from the AC or DC bus to the single type of hydrogen production unit.

11. The control method of the renewable energy hydrogen production system according to claim 10, characterized in that: Also includes: If the system operation mode is a new energy hybrid grid-connected mode: control the power path direction of the isolation circuit to achieve the direction of unidirectional power flow from multiple types of renewable energy power generation units to the AC or DC bus unit; If the system operation mode is a hybrid energy storage grid-connected charging / discharging mode: control the power path direction of the isolation circuit to achieve a bidirectional power flow direction from multiple types of energy storage units to the AC or DC bus unit; If the system operation mode is a grid-connected hybrid hydrogen production mode: control the power path direction of the isolation circuit to realize the direction of power from the AC or DC bus to multiple types of hydrogen production units.

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