Alternating-current off-grid hydrogen production system
By designing the AC energy storage subsystem and DC energy storage subsystem in the AC off-grid hydrogen production system, the coordination and balance problem between the energy storage system supporting AC bus voltage and balancing new energy output and hydrogen production load is achieved. Improve system stability and efficiency.
Patent Information
- Application Number
- CN202411470433.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-02-18
AI Technical Summary
In AC off-grid hydrogen production systems, the energy storage system needs to take into account both supporting AC bus voltage and balancing the unstable output of new energy and relatively stable hydrogen production loads, resulting in difficulty in coordinating the source and load balance control.
An AC off-grid hydrogen production system including an AC energy storage subsystem and a DC energy storage subsystem were designed. The AC energy storage subsystem provides voltage support for the AC bus, and the DC energy storage subsystem balances the output of the new energy electronics system and the power of the hydrogen-making electrolytic cell.
It realizes the flexibly controlling the source and load coordination balance of the entire system while ensuring the stability of the AC bus voltage, improving the stability and efficiency of the system.
Smart Images
Figure CN119482602A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of green electricity hydrogen production, and specifically relates to an AC off-grid hydrogen production system. Background Art
[0002] With the continuous development of green electricity hydrogen production technology, the application of water electrolysis hydrogen production based on wind power and photovoltaic off-grid power generation has become a hot spot in hydrogen production technology. However, the current mainstream solution for large-scale new energy hydrogen production is still AC grid-connected. In the AC grid-connected hydrogen production solution, wind power and photovoltaics transmit new energy power to the power grid in the form of AC power generation, and the hydrogen production system operates as a load of the power grid. The hydrogen production electrolyzer operates at a constant power, and the power grid supplements the power when the new energy power is sufficient, and the remaining power is sent to the power grid when the new energy power is excess.
[0003] The traditional AC grid-connected hydrogen production solution has a high electricity cost because its hydrogen production load needs to be powered by the grid, which results in low economic efficiency of hydrogen production. In addition, the hydrogen produced in this way is not truly green hydrogen, which limits the application of the produced hydrogen. Therefore, AC off-grid hydrogen production technology based on energy storage support has emerged.
[0004] At present, AC off-grid hydrogen production technology based on energy storage support is still in the stage of research, exploration and demonstration application. In the AC off-grid hydrogen production scheme, the hydrogen production system is no longer connected to the grid, but supports the AC bus voltage through the energy storage system. The energy storage system takes into account the role of new energy output and the power balance between hydrogen production loads; wind power and photovoltaic power are connected to the AC bus in the form of AC power generation, and the hydrogen production power source is drawn from the AC bus and provides a wide range of working power for the electrolyzer after two-level topology changes. Compared with the AC grid-connected hydrogen production scheme, this scheme not only does not need to be connected to the grid, but also eliminates the cumbersome new energy grid approval process, and all the electricity used for hydrogen production is green electricity, and the hydrogen produced is 100% green hydrogen.
[0005] However, in the AC off-grid hydrogen production solution, new energy hydrogen storage systems such as wind and solar power rely on the isolated operation of the energy storage system. The energy storage system must not only support the AC bus voltage, but also balance the unstable output of new energy and the relatively stable load of hydrogen production, making source-load coordination control difficult. Summary of the invention
[0006] The purpose of the present invention is to provide an AC off-grid hydrogen production system to solve the problem of difficulty in source-load coordination and balance control of the entire AC off-grid hydrogen production system in the prior art, because the energy storage system needs to take into account both supporting the AC bus voltage and balancing the unstable output of new energy and the relatively stable load of hydrogen production.
[0007] In order to achieve the above-mentioned purpose, the present invention provides a new AC off-grid hydrogen production system, which includes an AC energy storage subsystem connected to an AC bus connected to a hydrogen production power source to provide voltage support for the AC bus; the hydrogen production power source is used to access an AC bus powered by a new energy power generation subsystem to obtain power for a hydrogen production unit, including an AC / DC converter connected to the AC bus and a DC / DC converter connected to the hydrogen production unit in series; the hydrogen production system also includes a DC energy storage subsystem connected in parallel between the AC / DC converter and the DC / DC converter of the hydrogen production power source to balance the output of the new energy power generation subsystem and the power of the hydrogen production unit; The AC energy storage subsystem includes a DC / AC energy storage converter and a first energy storage unit; The DC energy storage subsystem includes a DC / DC energy storage converter and a second energy storage unit.
[0008] Beneficial effects: The present invention provides a new AC off-grid hydrogen production system; the AC energy storage subsystem, DC energy storage subsystem and hydrogen production subsystem (i.e., hydrogen production power supply and hydrogen production unit) in the system work together; specifically, the AC energy storage subsystem provides a stable support voltage for the AC bus; at the same time, the new energy power generation subsystem outputs electric energy to the bus, the hydrogen production power supply draws electricity from the AC bus, and the hydrogen production unit operates as a load, so that off-grid hydrogen production can be achieved completely through the power of new energy power generation. In addition, if the output power of the new energy power generation subsystem does not meet the constant power of the hydrogen production electrolyzer in the hydrogen production unit, the DC energy storage subsystem draws electricity from its energy storage unit to compensate for the remaining power; if the output power of the new energy power generation subsystem exceeds the constant power of the hydrogen production electrolyzer in the hydrogen production unit, the DC energy storage subsystem stores the remaining power through the energy storage unit; that is, the DC energy storage subsystem balances the source-load power. In summary, in this system, the AC energy storage subsystem is responsible for supporting the bus voltage, and the DC energy storage subsystem is responsible for balancing the source-load power, so as to achieve the effect of flexibly controlling the source-load coordinated balance of the entire AC off-grid hydrogen production system while ensuring a stable supporting voltage for the AC bus.
[0009] Furthermore, the DC energy storage subsystem is also used to continue to supply power to the hydrogen production unit when the AC energy storage subsystem stops supplying power to the hydrogen production unit due to a fault, so that the hydrogen production unit continues to operate or is safely shut down.
[0010] Furthermore, the operating mode of the AC / DC converter of the hydrogen production power supply includes a voltage source mode; the DC / AC of the hydrogen production power supply is used to switch to the voltage source mode when the AC energy storage subsystem fails to provide voltage support for the AC bus.
[0011] Furthermore, the new energy power generation subsystem includes at least one of a photovoltaic power generation unit and a wind power generation unit.
[0012] Furthermore, the photovoltaic power generation unit includes a photovoltaic inverter and a photovoltaic panel; the wind power generation unit includes a wind power converter and a wind turbine.
[0013] Furthermore, the hydrogen production unit is an electrolyzer. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 This is a connection example diagram of an AC off-grid hydrogen production system in an embodiment of the AC off-grid hydrogen production system of the present invention. DETAILED DESCRIPTION
[0015] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.
[0016] AC off-grid hydrogen production system implementation example This embodiment provides an AC off-grid hydrogen production system, in which an AC energy storage subsystem provides voltage support for the AC bus of the hydrogen production system; a new energy power generation subsystem provides new energy output for the hydrogen production subsystem; and taking into account the unstable output characteristics of new energy output, a DC energy storage subsystem is used to compensate or absorb the unstable output of the new energy power generation subsystem to ensure that the electrolyzer in the hydrogen production subsystem operates normally at a constant power, that is, the source and load power are balanced through the DC energy storage subsystem to achieve the effect of "load follows source".
[0017] The AC off-grid hydrogen production system of this embodiment specifically includes: an AC energy storage subsystem connected to the AC bus connected to the hydrogen production power supply to provide voltage support for the AC bus; wherein the hydrogen production power supply is used to connect to the AC bus powered by the new energy power generation subsystem to obtain power for the hydrogen production unit, and the hydrogen production power supply includes an AC / DC converter connected to the AC bus and a DC / DC converter connected to the hydrogen production unit in series; the hydrogen production system also includes a DC energy storage subsystem connected in parallel between the AC / DC converter and the DC / DC converter of the hydrogen production power supply to balance the output of the new energy power generation subsystem and the power of the hydrogen production unit; The AC energy storage subsystem includes a DC / AC energy storage converter and a first energy storage unit; The DC energy storage subsystem includes a DC / DC energy storage converter and a second energy storage unit.
[0018] In this embodiment, the hydrogen production unit is an electrolyzer.
[0019] Specifically, Figure 1 As shown in the figure, the AC off-grid hydrogen production system mainly includes the following four subsystems: 1) AC energy storage subsystem: This subsystem is connected to the AC bus to which the hydrogen production power source is connected. In this embodiment, this subsystem includes a DC / AC energy storage converter and an energy storage battery (i.e., a first energy storage unit). In other embodiments, the first energy storage unit may also be other energy storage devices with charging and discharging capabilities. The function of this subsystem is to provide sufficient voltage support for the AC bus.
[0020] 2) Hydrogen production subsystem; this subsystem includes a hydrogen production power supply and an electrolyzer (i.e., a hydrogen production unit); the hydrogen production power supply includes an AC / DC converter and a DC / DC converter; the AC / DC converter is connected to the AC bus through a controllable switch; the DC / DC converter is connected between the AC / DC converter and the electrolyzer; the hydrogen production power supply draws power from the AC bus, and provides a wide range of working power for the electrolyzer through two-stage topology changes of AC / DC and DC / DC.
[0021] 3) New energy power generation subsystem; this subsystem is connected in parallel to the AC busbar, and its function is to provide new energy output power for the hydrogen production subsystem, that is, to generate electricity through new energy and send the generated electricity to the AC busbar for use by the hydrogen production subsystem. In this embodiment, the new energy power generation subsystem includes at least one of a photovoltaic power generation unit and a wind power generation unit ( Figure 1 That is, an example of a case where the new energy power generation subsystem includes both a photovoltaic power generation unit and a wind power generation unit); the photovoltaic power generation unit includes a photovoltaic inverter and a photovoltaic panel; the wind power generation unit includes a wind power converter and a wind turbine; in other embodiments, only one of the photovoltaic power generation unit or the wind power generation unit may be used, or other new energy power generation units may be added.
[0022] 4) DC energy storage subsystem; this subsystem is connected in parallel between the AC / DC converter and the DC / DC converter of the hydrogen production power source. In this embodiment, the subsystem includes a DC / DC energy storage converter and an energy storage battery (i.e., the second energy storage unit); in other embodiments, the second energy storage unit may also be other energy storage devices with charging and discharging capabilities. The main function of this subsystem is to balance the output of the new energy power generation subsystem with the power of the hydrogen production unit, that is, when the output power of the new energy power generation subsystem does not meet the constant power of the hydrogen production electrolyzer in the hydrogen production unit, the DC energy storage subsystem takes power from the energy storage battery to compensate for the remaining power; when the output power of the new energy power generation subsystem exceeds the power of the hydrogen production electrolyzer in the hydrogen production unit, the DC energy storage subsystem stores the remaining power through the energy storage unit.
[0023] In this embodiment, the DC energy storage subsystem is also used to continue to supply power to the hydrogen production unit when the AC energy storage subsystem stops supplying power to the hydrogen production unit due to a fault, so that the hydrogen production unit continues to operate or shuts down safely.
[0024] Specifically, in addition to balancing the output of the new energy power generation subsystem and the power of the hydrogen production unit, the above-mentioned DC energy storage subsystem can also continue to supply power to the electrolyzer (i.e., the hydrogen production unit) when the AC energy storage subsystem stops supplying power to the electrolyzer (i.e., the hydrogen production unit) due to a fault, so that the electrolyzer will not be in a dangerous situation of emergency shutdown due to sudden power outage. That is, when the AC energy storage subsystem loses power due to a fault, the DC energy storage subsystem immediately supplies power to the electrolyzer to provide buffer time for it to shut down safely; or when it is necessary to ensure the operation of the electrolyzer, the DC energy storage subsystem supplies power to the electrolyzer to maintain its normal operation for a period of time.
[0025] In this embodiment, the operating mode of the AC / DC converter of the hydrogen production power supply includes a voltage source mode; the DC / AC of the hydrogen production power supply is used to switch to the voltage source mode when the AC energy storage subsystem fails to provide voltage support for the AC bus.
[0026] Specifically, since the AC energy storage subsystem needs to support the AC bus voltage, when the AC energy storage subsystem fails, other subsystems connected to the AC bus (such as the new energy power generation subsystem and the hydrogen production subsystem) will collapse due to the loss of voltage support, thereby affecting their safety. Therefore, the operating mode of the AC / DC converter of the hydrogen production power supply in this embodiment includes a voltage source mode. When the AC energy storage subsystem fails, the AC / DC converter of the hydrogen production power supply can be switched to the voltage source mode to support the AC bus voltage and maintain the normal and stable operation of other subsystems connected to the AC bus. Figure 1 As shown, the new energy generation subsystem in this embodiment includes a photovoltaic power generation unit and a wind power generation unit connected in parallel to the AC bus, that is, wind power and photovoltaic power are connected to the AC bus in an AC power generation mode; the photovoltaic power generation unit is composed of a series-connected AC / DC photovoltaic inverter and a photovoltaic panel PV, and the wind power generation unit is composed of a series-connected AC / DC-DC / AC wind power converter and a wind turbine. In other embodiments, the new energy output can also be provided by new energy sources other than wind power and photovoltaic power, such as hydropower and microbial power generation.
[0027] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, but do not constitute a limitation to the present invention.
Claims
1. An AC off-grid hydrogen production system, characterized in that: The hydrogen production system includes an AC energy storage subsystem connected to an AC bus connected to a hydrogen production power source to provide voltage support for the AC bus; the hydrogen production power source is used to connect to an AC bus powered by a new energy power generation subsystem to obtain power for a hydrogen production unit, including an AC / DC converter connected to the AC bus and a DC / DC converter connected to the hydrogen production unit in series; the hydrogen production system also includes a DC energy storage subsystem connected in parallel between the AC / DC converter and the DC / DC converter of the hydrogen production power source to balance the output of the new energy power generation subsystem and the power of the hydrogen production unit; The AC energy storage subsystem includes a DC / AC energy storage converter and a first energy storage unit; The DC energy storage subsystem includes a DC / DC energy storage converter and a second energy storage unit.
2. The AC off-grid hydrogen production system according to claim 1, characterized in that: The DC energy storage subsystem is also used to continue to supply power to the hydrogen production unit when the AC energy storage subsystem stops supplying power to the hydrogen production unit due to a fault, so that the hydrogen production unit continues to operate or is safely shut down.
3. The AC off-grid hydrogen production system according to claim 1 or 2, characterized in that: The operating mode of the AC / DC converter of the hydrogen production power supply includes a voltage source mode; the DC / AC of the hydrogen production power supply is used to switch to the voltage source mode when the AC energy storage subsystem fails to provide voltage support for the AC bus.
4. The AC off-grid hydrogen production system according to claim 1 or 2, characterized in that: The new energy power generation subsystem includes at least one of a photovoltaic power generation unit and a wind power generation unit.
5. The AC off-grid hydrogen production system according to claim 4, characterized in that: The photovoltaic power generation unit includes a photovoltaic inverter and a photovoltaic battery panel; the wind power generation unit includes a wind power converter and a wind turbine.
6. The AC off-grid hydrogen production system according to claim 1 or 2, characterized in that: The hydrogen production unit is an electrolyzer.