Hydrogen production system coupled with photovoltaic renewable energy and optimal configuration method

Abstract

The application discloses a kind of mixed hydrogen production systems and optimization configuration methods of coupling photovoltaic renewable energy, it is related to new energy utilization and energy storage control technical field, including photovoltaic power generation unit, alkaline water electrolytic cell unit, proton exchange membrane electrolytic cell unit, hydrogen storage unit, control unit etc..The present application directly supplies photovoltaic electric energy to two types of electrolytic cell stacks through DC bus, omits traditional DC-DC power converter, reduces the loss in energy transmission process;Through the dynamic electrolytic cell switching algorithm configured by the control unit, the input proportion and the number of running units of the two stacks are adjusted in real time, and the quick response capability and long-term stability are considered.System can produce hydrogen stably under the condition of renewable energy fluctuation, both dynamically adapt to input power change, and realize maximum power point tracking control without using additional power conversion equipment, while ensuring the hydrogen production efficiency, significantly reduce initial investment cost and operating energy consumption.

Description

Technical Field

[0001] This invention relates to the field of new energy utilization and energy storage control technology, and in particular to a hybrid hydrogen production system coupled with photovoltaic renewable energy and an optimized configuration method. Background Technology

[0002] With the growing global demand for carbon emission control and clean energy transition, the production of green hydrogen through water electrolysis based on renewable energy sources (such as solar and wind power) has become an important pathway to achieving a low-carbon energy structure. However, renewable energy sources are characterized by significant intermittency and volatility, especially photovoltaic power output, which is significantly affected by weather and time of day, posing challenges to the stability and efficiency of hydrogen production systems.

[0003] Currently, commonly used water electrolysis technologies for hydrogen production mainly include alkaline electrolyzers (AE) and proton exchange membrane electrolyzers (PEM). AE technology is mature, low-cost, and suitable for continuous and stable operation, but it has a slow response to power fluctuations and is unsuitable for frequent start-ups and shutdowns or rapid power adjustments. PEM electrolyzers, on the other hand, have excellent rapid response capabilities and are suitable for tracking the volatility of renewable energy sources, but their manufacturing costs are higher, resulting in larger system investments. Existing systems often use a single type of electrolyzer, making it difficult to balance efficiency, flexibility, and economy, and thus unable to meet the dual requirements of response speed and cost control in renewable energy hydrogen production.

[0004] On the other hand, inadequate energy storage configuration also limits system performance. Battery energy storage systems (BESS) offer rapid charge and discharge capabilities, making them suitable for short-term power buffering, but their limited capacity makes it difficult to cover long-term fluctuations. While hydrogen energy storage systems (HESS) are suitable for long-term energy storage, they struggle to provide rapid response support. Current hydrogen production systems generally lack coordinated control strategies for BESS and HESS, failing to effectively achieve complementary utilization of short-term regulation and long-term energy storage.

[0005] In addition, most photovoltaic-electrolyzer systems use DC-DC converters for photovoltaic voltage regulation and maximum power point tracking (MPPT). Although energy regulation can be achieved, the introduced power converters not only generate energy losses, but also increase system costs and control complexity. In particular, in large-scale hydrogen production projects, the conversion efficiency and economic issues are particularly prominent.

[0006] In grid-connected operation scenarios, balancing economic efficiency and environmental protection is equally crucial. Electricity prices and grid carbon intensity vary significantly over time. If hydrogen production can be achieved by drawing electricity during periods of low electricity prices and low carbon emissions, and then transmitting or storing surplus electricity during periods of high electricity prices, hydrogen production costs and carbon footprints can be further reduced. However, existing systems lack dynamic prediction and optimization scheduling mechanisms, making it difficult to flexibly respond to short-term fluctuations while ensuring long-term hydrogen delivery targets, thus failing to achieve optimal synergy between economic and environmental benefits.

[0007] Therefore, there is an urgent need for a hybrid hydrogen production system that couples photovoltaic renewable energy sources, has a reasonable system structure, efficient control strategy, and low operating costs and carbon emissions. Summary of the Invention

[0008] To address the above issues, this invention proposes a hybrid hydrogen production system coupled with photovoltaic renewable energy and its optimized configuration method to achieve a stable, efficient, and low-carbon hydrogen production process with a high proportion of green electricity utilization.

[0009] The present invention achieves the above objectives through the following technical solutions:

[0010] A hybrid hydrogen production system coupled with photovoltaic renewable energy includes a photovoltaic power generation unit, an alkaline water electrolyzer unit, a proton exchange membrane electrolyzer unit, a hydrogen storage unit, and a control unit;

[0011] The DC output of the photovoltaic power generation unit supplies power to the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit via the DC bus. The alkaline water electrolyzer unit includes a number of alkaline electrolyzer cells connected in series to form a first electrolyzer stack. The proton exchange membrane electrolyzer unit includes a number of PEM electrolyzer cells connected in series to form a second electrolyzer stack. The first electrolyzer stack and the second electrolyzer stack are connected in parallel to the DC bus.

[0012] The hydrogen storage unit is connected to the hydrogen production outlet of the first electrolyzer stack and the second electrolyzer stack, and is used to collect and store hydrogen produced by the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit.

[0013] The control unit is connected to the photovoltaic power generation unit, the alkaline water electrolyzer unit, the proton exchange membrane electrolyzer unit, and the hydrogen storage unit. The control unit is equipped with a dynamic electrolyzer switching algorithm, which is used to control the number and operating mode of the electrolyzer cells actually put into operation in the first electrolyzer stack and the second electrolyzer stack according to the real-time detected photovoltaic power generation and the operating status of the first electrolyzer stack and the second electrolyzer stack, so as to optimize the power matching relationship between photovoltaic power generation output and electrolyzer load.

[0014] The expression for the dynamic electrolyzer switching algorithm is:

[0015]

[0016] In the formula, N active (t) represents the optimal number of electrolytic cells selected for operation at time t; N represents the total number of cells in all electrolytic cells; V e V is the voltage of a single cell in an electrolytic cell. mpp (t) represents the photovoltaic maximum power point voltage; λ is the equilibrium weighting factor, STA i STAj These represent the state durations of the i-th and j-th electrolytic cells, respectively.

[0017] In a preferred embodiment of the present invention, the control unit includes an MPPT control module. The MPPT control module is used to track the maximum power point of the photovoltaic power generation unit in real time. When the photovoltaic output power increases, it selects and connects the electrolytic cell with the longest current idle time to put it into operation; when the photovoltaic output power decreases, it selects and disconnects the electrolytic cell with the longest current continuous operating time to exit operation, so that the total voltage of the first electrolytic cell stack and the second electrolytic cell stack is equal to the photovoltaic maximum power point voltage V. mpp (t) matching.

[0018] In a preferred embodiment of the present invention, the output of the photovoltaic power generation unit is directly connected to the first electrolytic cell stack and the second electrolytic cell stack via a DC bus, without any DC-DC power converter in between; each electrolytic cell battery connected in series in each electrolytic cell stack is connected to a controllable switch, which is used to switch in or out the corresponding alkaline electrolytic cell battery or PEM electrolytic cell battery under the command of the control unit, thereby changing the effective number of series electrolytic cell batteries and the total voltage of the first electrolytic cell stack or the second electrolytic cell stack.

[0019] As a preferred embodiment of the present invention, the ratio of the rated hydrogen production power of the first electrolyzer stack and the second electrolyzer stack is set according to the expected fluctuation characteristics of photovoltaic output, so that the first electrolyzer stack bears the average base hydrogen production load and the second electrolyzer stack bears the transient peak hydrogen production load.

[0020] The rated power of the first electrolyzer stack accounts for 60% to 80% of the total hydrogen production power, and the rated power of the second electrolyzer stack accounts for 20% to 40% of the total hydrogen production power.

[0021] In a preferred embodiment of the present invention, the control unit includes a prediction and scheduling module for acquiring information on renewable energy generation capacity, electricity price, and grid carbon intensity within a predetermined future period, and formulating a target hydrogen production power plan curve based on the acquired information; the control unit optimizes the operation of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit according to the target hydrogen production power plan curve, so that the cumulative hydrogen production reaches the target requirement at the end of the predetermined period, while minimizing operating costs and carbon emissions in each preset sub-period.

[0022] The prediction and scheduling module is configured to dynamically adjust the hydrogen production load based on short-term climate forecast data, and optimize the operating status of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit. The load allocation formula is as follows:

[0023]

[0024] In the formula, P is the output flow rate of hydrogen. PV (t) represents the photovoltaic power generation, P elec (t) represents the total power of the first and second electrolytic cell stacks, η elec η represents the total efficiency of the first and second electrolytic cell stacks. PV For photovoltaic system efficiency.

[0025] As a preferred embodiment of the present invention, the system further includes a battery energy storage unit, which is connected to the DC bus via a bidirectional DC / DC converter; the control unit is further configured to monitor the power balance of the DC bus, and when the photovoltaic power generation exceeds the hydrogen production power requirement of the electrolyzer battery, control the battery energy storage unit to charge to store excess energy, and when the photovoltaic power generation is insufficient, control the battery energy storage unit to discharge to provide power to the DC bus, thereby smoothing out power fluctuations in a short time scale.

[0026] As a preferred embodiment of the present invention, the control unit adopts a multi-agent cooperative control architecture, which includes at least multiple agents for the battery energy storage unit, the alkaline water electrolyzer unit, and the proton exchange membrane electrolyzer unit. Each agent searches for its own optimal control strategy online based on a deep reinforcement learning algorithm, and works together to achieve comprehensive optimization control of the entire system.

[0027] In a preferred embodiment of the present invention, the system further includes a grid interface unit, which comprises a bidirectional inverter for connecting the DC bus to an external AC grid; the control unit controls the operating mode of the bidirectional inverter according to a preset strategy, wherein the preset strategy is specifically:

[0028] When the photovoltaic power generation exceeds the total load demand of the current hydrogen production system and the current grid electricity price is higher than the set upper limit threshold, the control unit will set the bidirectional inverter to grid-connected output mode and feed the excess power back to the AC grid.

[0029] When the photovoltaic power generation capacity cannot meet the load demand of the hydrogen production system, and the current grid electricity price is lower than the set economic electricity purchase threshold, and the carbon emission intensity of the electricity provided by the grid is lower than the set environmental protection threshold, the control unit controls the bidirectional inverter to purchase electricity from the grid for hydrogen production.

[0030] An optimized configuration method for a hybrid hydrogen production system coupled with photovoltaic renewable energy, the method comprising:

[0031] Data acquisition and forecasting: Real-time monitoring of photovoltaic power generation, DC bus voltage, operating status parameters of the first and second electrolyzer stacks, hydrogen storage capacity, and battery energy storage unit status; acquisition of photovoltaic output forecasts, electricity price forecasts, and grid carbon emission intensity forecasts for the future predetermined period;

[0032] Hydrogen production plan formulation: Based on the photovoltaic output forecast, electricity price forecast and grid carbon emission intensity forecast information, combined with the predetermined hydrogen production target, optimize the calculation of the target hydrogen production power plan curve for each sub-period within the predetermined period. The optimization calculation objective is to minimize the operating cost and carbon emissions of the hydrogen production process, and constrain the cumulative hydrogen production to meet the target value.

[0033] Power distribution control: According to the target hydrogen production power plan curve, control the number of electrolyzer cells and current values ​​of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit that are put into operation; when the actual photovoltaic power is higher than the planned value, prioritize increasing the input of the second electrolyzer stack to absorb the extra power; when the actual photovoltaic power is lower than the planned value, prioritize reducing the load of the second electrolyzer stack and coordinate the first electrolyzer stack to bear the average base hydrogen production load;

[0034] Energy storage and grid regulation: Real-time monitoring of DC bus power difference. If the instantaneous photovoltaic power exceeds the current absorption capacity of the electrolyzer, the battery energy storage unit is controlled to charge or the power is sent to the grid through the bidirectional inverter in the grid interface unit. If the photovoltaic power is insufficient to meet the planned hydrogen production power, the battery energy storage unit is controlled to discharge to supplement the power. The insufficient part is purchased from the grid according to the preset strategy.

[0035] Real-time correction and rolling optimization: The actual operating data is periodically compared with the target hydrogen production plan. When the cumulative deviation exceeds the threshold, the planned power curve is updated in real time and the subsequent scheduling strategy is corrected, forming a closed-loop scheduling optimization mechanism.

[0036] As a preferred embodiment of the present invention, the power distribution control employs the following strategy to maximize the utilization of photovoltaic power and smooth the load on the electrolyzer:

[0037] When the photovoltaic output power increases relative to the previous moment, the PEM electrolyzer cell with the longest idle time is selected to be put into operation until the photovoltaic output matches the total load of the first and second electrolyzer stacks, or all PEM electrolyzer cells are put into operation; if there is still surplus power, the number of alkaline electrolyzer cells in the first electrolyzer stack is further increased or the operating current is increased.

[0038] When the photovoltaic output power decreases, the PEM electrolyzer cell with the longest continuous operating time is shut down first. If the photovoltaic power cannot be matched even after all PEM electrolyzer cells have been disconnected, the number of operating units of alkaline electrolyzer cells in the first electrolyzer stack is further reduced.

[0039] Each time the operating status is adjusted, the duration of the state of all electrolytic cells is recorded, and the electrolytic cell cell with the longest continuous single state time is switched first, so as to realize the rotation operation and rest of the electrolytic cells.

[0040] The beneficial effects of this invention are as follows: Photovoltaic power is directly supplied to two types of electrolyzer stacks via a DC bus, eliminating the need for traditional DC-DC power converters and reducing energy losses during transmission (typically 5%–10%). This simplifies system configuration and control links, effectively improving overall photovoltaic-hydrogen conversion efficiency. Alkaline water electrolyzer cells form the first electrolyzer stack, serving as the main hydrogen production unit for stable loads. Proton exchange membrane electrolyzer cells form the second electrolyzer stack, acting as a flexible unit for rapidly adjusting peak loads. Through a dynamic electrolyzer switching algorithm configured in the control unit, the input ratio and number of operating units of the two stacks can be adjusted according to real-time changes in photovoltaic output power, balancing rapid response and long-term stability, avoiding energy waste or system impact caused by photovoltaic fluctuations. The system can stably produce hydrogen under conditions of renewable energy fluctuations, dynamically adapting to changes in input power and achieving maximum power point tracking (MPPT) control without additional power conversion equipment. This significantly reduces initial investment costs and operating energy consumption while ensuring hydrogen production efficiency. The electrolyzer cells are designed as a series structure controlled by a controllable switch, with modular scheduling capabilities. The number of operating units can be expanded or the stack composition ratio can be adjusted according to needs, adapting to the load requirements of photovoltaic systems of different scales, and providing a feasible engineering path for large-scale photovoltaic hydrogen production scenarios. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] in:

[0043] Figure 1 This is a system structure diagram of the present invention;

[0044] Figure 2 This is a flowchart of the method of the present invention.

[0045] The diagram is labeled as follows: 101, Photovoltaic power generation unit; 102, DC bus; 103, Alkaline water electrolyzer unit; 104, Proton exchange membrane electrolyzer unit; 105, Battery energy storage unit; 106, Hydrogen storage unit; 107, Control unit; 108, Grid interface unit. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0047] Example 1: System Overall Architecture and Working Mode

[0048] This hybrid hydrogen production system can be viewed as a microgrid or energy hub powered by renewable energy, coupling multiple energy components and energy storage devices. The system includes the following main parts:

[0049] Renewable energy power generation module: Primarily composed of photovoltaic (PV) arrays, installed at selected sites to obtain solar power. Other renewable energy sources such as wind power can also be integrated as needed, but PV is the core energy source. The DC power output from the PV array is supplied to the subsequent hydrogen production unit in an optimized manner. In a preferred embodiment, the PV array is directly connected to the hydrogen production module, omitting the intermediate DC-DC converter and achieving efficient DC power supply.

[0050] Hybrid water electrolysis hydrogen production module: This module combines two types of water electrolysis hydrogen production devices: an alkaline electrolyzer (ALK Electrolyzer) and a proton exchange membrane electrolyzer (PEM Electrolyzer). Alkaline electrolyzers are technologically mature and have lower hydrogen production costs, but their start-up and load change response are slower. PEM electrolyzers, on the other hand, have a rapid response and strong adaptability, but are more expensive. Coupling these two types of electrolyzers to form a hybrid water electrolysis hydrogen production module allows for the simultaneous utilization of the advantages of alkaline electrolyzers (suitable for constant high loads) and PEM electrolyzers (rapid adjustment), achieving efficient utilization of fluctuating photovoltaic power. Each type of electrolyzer consists of several individual electrolyzer cells connected in series to form a stack, adapting to a specific DC bus voltage. The alkaline and PEM stacks can be connected in parallel to the same DC bus, with the control system distributing their respective input power.

[0051] Energy buffering and storage module: This includes a battery energy storage unit and a hydrogen storage unit. The battery energy storage unit (such as a lithium-ion battery pack) is mainly used for short-term power balancing and buffering, quickly responding to short-cycle fluctuations in photovoltaic output and smoothing the power curve. The hydrogen storage unit is used to store hydrogen produced by the electrolyzer (e.g., high-pressure hydrogen storage tanks or metal hydride storage tanks), achieving long-term energy storage. Hydrogen can be output as a final product for industrial and transportation use, or it can be converted into electricity by a downstream fuel cell power generation unit to supply power to the grid or load during periods of low renewable energy demand, achieving a "power-hydrogen-power" cycle. Depending on specific application requirements, the system can be selected to include a fuel cell power generation device; in scenarios where hydrogen production is prioritized, a fuel cell may not be installed, and only the hydrogen output interface may be retained.

[0052] Power electronics and interface modules: These manage power exchange between different components, including the DC bus and necessary switching / conversion devices. In a preferred embodiment, the photovoltaic array is directly connected to the DC bus whenever possible, and the electrolytic cell stack is connected to the bus via an electronic switching matrix to achieve dynamic adjustment of the equivalent load. Battery cells are connected to the DC bus via bidirectional DC / DC converters to control their charging and discharging power. The system can also be connected to the AC grid via an inverter for purchasing or selling electricity to the grid as needed (grid connection interface). When the system is connected to an external grid, the inverter and corresponding controls ensure the safety and power quality of bidirectional power flow between the system and the grid.

[0053] Intelligent Control and Energy Management Module: This is the brain of the system, comprising sensing, communication, and control algorithms. The control module monitors real-time information such as photovoltaic output power, solar irradiance, battery SOC (state of charge), electrolyzer stack status (voltage, current, temperature, etc.), hydrogen storage tank pressure, energy load demand, grid electricity price, and carbon emission factors through sensors. Based on the collected data, the control system runs optimization algorithms to determine the operating status and power allocation of each component in real time, such as adjusting the number of alkaline / PEM electrolyzer cells in operation, battery charging and discharging power, and whether to draw power from or feed power to the grid. The control module is implemented by a high-speed industrial controller or industrial PC, incorporating multiple control strategies, including rule-based control and artificial intelligence algorithms, to ensure optimized system operation at different time scales.

[0054] Overall, the system structure tightly couples the power generation, power consumption, and energy storage links to achieve integrated generation-storage-use: the electricity generated by renewable energy sources such as photovoltaics is used first to drive the electrolysis of water to produce hydrogen, which is then converted into chemical energy for storage through the hydrogen storage module; at the same time, the battery serves as an auxiliary buffer to ensure the transient balance of power supply and demand and the stable operation of the hydrogen production load; when necessary, the system interacts with the grid to exchange energy, thereby maximizing the use of green electricity and ensuring the continuous and reliable hydrogen production process.

[0055] Example 2: Hybrid Hydrogen Production System Coupled with Photovoltaic Renewable Energy

[0056] like Figure 1 As shown, the hybrid hydrogen production system in this embodiment includes a photovoltaic power generation unit 101, an alkaline water electrolyzer unit 103, a proton exchange membrane electrolyzer unit 104, a hydrogen storage unit 106, and a control unit 107.

[0057] The DC output of the photovoltaic power generation unit 101 supplies power to the alkaline water electrolyzer unit 103 and the proton exchange membrane electrolyzer unit 104 via the DC bus 102. The alkaline water electrolyzer unit 103 includes several alkaline electrolyzer cells connected in series to form a first electrolyzer stack. The proton exchange membrane electrolyzer unit 104 includes several PEM electrolyzer cells connected in series to form a second electrolyzer stack. The first electrolyzer stack and the second electrolyzer stack are connected in parallel to the DC bus 102.

[0058] The hydrogen storage unit 106 is connected to the hydrogen production outlet of the first electrolyzer stack and the second electrolyzer stack, and is used to collect and store the hydrogen produced by the alkaline water electrolyzer unit 103 and the proton exchange membrane electrolyzer unit 104.

[0059] The control unit 107 is connected to the photovoltaic power generation unit 101, the alkaline water electrolyzer unit 103, the proton exchange membrane electrolyzer unit 104, and the hydrogen storage unit 106. The control unit 107 is equipped with a dynamic electrolyzer switching algorithm, which controls the number and operating mode of the electrolyzer cells actually in operation in the first and second electrolyzer stacks based on the real-time detected photovoltaic power generation and the operating status of the first and second electrolyzer stacks, in order to optimize the power matching relationship between the photovoltaic power generation output and the electrolyzer load.

[0060] The expression for the dynamic electrolyzer switching algorithm is:

[0061]

[0062] In the formula, N active (t) represents the optimal number of electrolytic cells selected for operation at time t; N represents the total number of cells in all electrolytic cells; V e V is the voltage of a single cell in an electrolytic cell. mpp (t) represents the photovoltaic maximum power point voltage; λ is the equilibrium weighting factor, STA i STA j These represent the state durations of the i-th and j-th electrolytic cells, respectively.

[0063] The control unit connects to various power devices, such as battery DC / DC converters, inverters, switch matrices, and valves, via industrial Ethernet or fieldbus to exchange control signals. It coordinates power distribution among photovoltaic cells, two types of electrolyzers, batteries, and the power grid according to a predetermined control strategy. The core basis for control decisions is real-time power balance and optimization objectives, such as maximizing green electricity utilization, meeting hydrogen production targets, and minimizing costs / emissions. The controller internally includes fast closed-loop control (such as voltage and current loop control to ensure safe operation of the electrolyzers) and higher-level decision algorithms (such as optimized scheduling strategies to determine the operating modes of each device).

[0064] Furthermore, the control unit 107 includes an MPPT control module, which tracks the maximum power point of the photovoltaic power generation unit 101 in real time. When the photovoltaic output power increases, the module selects and connects the electrolytic cell that has been idle for the longest time to start operation; when the photovoltaic output power decreases, the module selects and disconnects the electrolytic cell that has been continuously running for the longest time to stop operation, so that the total voltage of the first electrolytic cell stack and the second electrolytic cell stack is equal to the photovoltaic maximum power point voltage V. mpp (t) matching.

[0065] Two types of electrolyzers are stacked in parallel to the DC bus. Each stack consists of several electrolyzer cells connected in series and is equipped with electronic switches that allow for unit-level switching (connecting or disconnecting some cells). In the case of direct photovoltaic connection without DC / DC, these switches are used to regulate the stack terminal voltage to achieve MPPT; that is, changing the total voltage of the stack by changing the number of series cells. When both types of electrolyzers are connected simultaneously, they share the current provided by the photovoltaic system, and the specific current distribution depends on their respective instantaneous equivalent impedances, coordinated by the controller. In addition, the control system can selectively and temporarily shut down a certain type of electrolyzer (e.g., shutting down some alkaline electrolyzers when illumination is extremely low, leaving only PEM operation) to optimize efficiency.

[0066] Specifically, the output of the photovoltaic power generation unit 101 is directly connected to the first electrolytic cell stack and the second electrolytic cell stack via the DC bus 102, without any DC-DC power converter in between. The electrolytic cell battery units connected in series in the first electrolytic cell stack and the second electrolytic cell stack are all connected to controllable switches, which are used to switch in or out the corresponding alkaline electrolytic cell battery or PEM electrolytic cell battery under the command of the control unit 107, thereby changing the effective number of series electrolytic cell battery units and the total voltage of the first electrolytic cell stack or the second electrolytic cell stack.

[0067] Photovoltaic modules are connected in series and parallel to form an array, with their output connected to the system's DC bus. To match the voltage requirements of the downstream hydrogen production load, the open-circuit voltage and MPP voltage of the photovoltaic array are designed to be coordinated with the rated voltage of the electrolyzer stack. For example, if the voltage of a single electrolyzer unit is approximately 2V, and several are connected in series to obtain a stack rated voltage of 100V, then the MPP voltage of the photovoltaic array should be designed to be near this voltage. If the output voltage of the photovoltaic array is higher than the requirements of the electrolyzer stack, a DC / DC step-down converter can be used in the system; however, in the preferred embodiment of this invention, by increasing the number of electrolyzer units connected in series, direct matching can be achieved without additional DC / DC conversion. This direct-connect architecture reduces one stage of energy conversion and improves efficiency.

[0068] The ratio of the rated hydrogen production power of the first electrolyzer stack and the second electrolyzer stack is set according to the expected fluctuation characteristics of photovoltaic output, so that the first electrolyzer stack bears the average base hydrogen production load and the second electrolyzer stack bears the transient peak hydrogen production load.

[0069] The rated power of the first electrolyzer stack accounts for approximately 60% to 80% of the total hydrogen production power, and the rated power of the second electrolyzer stack accounts for approximately 20% to 40% of the total hydrogen production power.

[0070] Preferably, the control unit 107 includes a prediction and scheduling module for acquiring information on renewable energy generation capacity, electricity price, and grid carbon intensity within a predetermined future period, and formulating a target hydrogen production power plan curve based on the acquired information; the control unit 107 optimizes the operation of the alkaline water electrolyzer unit 103 and the proton exchange membrane electrolyzer unit 104 according to the target hydrogen production power plan curve, so that the cumulative hydrogen production reaches the target requirement at the end of the predetermined period, while minimizing operating costs and carbon emissions in each preset sub-period.

[0071] The forecasting and scheduling module is configured to dynamically adjust the hydrogen production load based on short-term climate forecast data, and optimize the operating status of the alkaline water electrolyzer unit 103 and the proton exchange membrane electrolyzer unit 104. The load allocation formula is as follows:

[0072]

[0073] In the formula, P is the output flow rate of hydrogen. PV (t) represents the photovoltaic power generation, P elec (t) represents the total power of the first and second electrolytic cell stacks, η elec η represents the total efficiency of the first and second electrolytic cell stacks. PV For photovoltaic system efficiency.

[0074] Furthermore, the system also includes a battery energy storage unit 105, which is connected to the DC bus 102 via a bidirectional DC / DC converter. The control unit 107 is further configured to monitor the power balance of the DC bus 102. When the photovoltaic power generation exceeds the hydrogen production power requirement of the electrolyzer battery, the control unit 105 is charged to store the excess energy. When the photovoltaic power generation is insufficient, the control unit 105 is discharged to provide power to the DC bus 102, thereby smoothing out power fluctuations in a short timescale.

[0075] The control unit 107 adopts a multi-agent cooperative control architecture, which includes at least multiple agents for the battery energy storage unit 105, the alkaline water electrolyzer unit 103, and the proton exchange membrane electrolyzer unit 104. Each agent searches for its own optimal control strategy online based on a deep reinforcement learning algorithm, and works together to achieve comprehensive optimization control of the entire system.

[0076] The system also includes a grid interface unit 108, which contains a bidirectional inverter for connecting the DC bus 102 to the external AC grid; the control unit 107 controls the operating mode of the bidirectional inverter according to a preset strategy, the preset strategy being:

[0077] When the photovoltaic power generation exceeds the total load demand of the current hydrogen production system and the current grid electricity price is higher than the set upper limit threshold, the control unit 107 sets the bidirectional inverter to grid-connected output mode and feeds the excess power back to the AC grid.

[0078] When the photovoltaic power generation cannot meet the load demand of the hydrogen production system, and the current grid electricity price is lower than the set economic electricity purchase threshold, and the carbon emission intensity of the electricity provided by the grid is lower than the set environmental protection threshold, the control unit 107 controls the bidirectional inverter to purchase electricity from the grid for hydrogen production.

[0079] Example 3: A specific example of a hybrid hydrogen production system

[0080] In this embodiment, the photovoltaic power generation unit 101 has a rated peak power of 5MW, an open-circuit voltage of approximately 1000V, and an MPP voltage of approximately 800V. The first electrolyzer stack consists of 400 individual alkaline electrolyzers connected in series, with a rated hydrogen production power of 3MW (corresponding to a current of approximately 3.75kA and a stack voltage of 800V); the second electrolyzer stack consists of 200 individual PEM electrolyzers connected in series, with a rated hydrogen production power of 2MW (corresponding to a current of approximately 2.5kA and a stack voltage of 800V). Through design, both types of electrolyzer stacks can operate at full load on an 800V DC bus. The anodes and cathodes of each stack are connected to the hydrogen storage unit 106 and the oxygen emission / recovery device via pipelines, with the hydrogen entering a high-pressure hydrogen storage tank for storage. The battery energy storage unit 105 uses a 1MWh, 1MW lithium battery pack, connected to the DC bus 102 via a bidirectional DC / DC converter. The system is connected to the external power grid via a 2MW bidirectional inverter.

[0081] In terms of control, the system is equipped with a central controller, which combines a PLC and an industrial computer to achieve high-speed real-time control and advanced optimization calculations. Sensors collect data such as photovoltaic voltage and current, DC bus voltage, electrolyzer current, voltage, and temperature, battery voltage, current, and SOC, hydrogen storage tank pressure, grid voltage frequency, electricity price, and carbon emission factor, and send this data to the real-time control module and the planning optimization module. The real-time control module executes cyclically at a frequency of 100Hz, responsible for voltage and current closed-loop and logic control, such as maintaining DC bus voltage stability, switching electrolyzer units, and setting the power of the battery converter. The planning optimization module performs a day-ahead calculation once a day and updates the plan every hour: based on the next day's solar radiation forecast curve, electricity price and carbon intensity forecast curves, and hydrogen delivery tasks, it solves a 24-hour optimization problem to determine the expected hourly hydrogen production power, charging and discharging plan, and grid purchase and sale plan. The optimization objective is to minimize "operating costs + carbon costs," with constraints including ensuring that the cumulative hydrogen production reaches demand by the end of the day and power / energy range limitations for each device. The optimization results are provided to the real-time control module for reference in the form of a planned curve.

[0082] Operating Mode: During the day, the controller maintains the first electrolyzer stack at a certain baseline power according to the optimized plan (e.g., when the planned hydrogen power is 2MW, the alkaline stack outputs approximately 1.5MW, and the PEM approximately 0.5MW). Real-time control adjusts based on deviations from actual photovoltaic output: if the actual photovoltaic output is higher than the planned value, the algorithm determines whether the excess is a short-term fluctuation or a trend of increase. For short-term fluctuations, the battery is directly charged to absorb the excess power; for sustained higher photovoltaic levels, the real-time control triggers a unit switching algorithm to increase the number of PEM electrolyzer operating units, gradually increasing from the planned 0.5MW, for example, adding one PEM electrolysis unit per second (approximately 0.004MW increment), until the photovoltaic power is balanced or the PEM reaches its full rated capacity. When the PEM reaches its full rated capacity of 2MW and there is still surplus photovoltaic power, the system checks the status of the alkaline electrolyzer: if it is not yet fully loaded and its operating time is stable enough, the alkaline electrolyzer current is increased to raise its hydrogen production power to absorb the remaining power. Simultaneously, a command may be issued to reduce battery charging so that more photovoltaic power can be directly used for hydrogen production. Conversely, when the actual output of the photovoltaic system is lower than the planned value, the control strategy first reduces the number of PEM electrolyzer units (cutting off one unit per second until the PEM stack drops to the required power); if this is still insufficient, the system will supplement the output by discharging batteries or purchasing electricity from the grid, as needed, to keep the alkaline electrolyzers in a safe operating range. Unless encountering extremely low irradiance conditions, the alkaline stack is generally not easily shut down, but rather its minimum output is maintained to avoid long restart times and low efficiency after shutdown.

[0083] Operating in this manner, almost all photovoltaic energy is utilized throughout the day: it is preferentially converted into hydrogen and stored in hydrogen storage unit 106, then stored in batteries, and finally fed into the grid when the batteries are full and less hydrogen is needed. Hydrogen storage unit 106 continuously accumulates hydrogen and monitors the pressure. The controller ensures that the hydrogen storage pressure does not exceed a safe threshold, controlling the pressure by adjusting the hydrogen production power or activating backup storage tanks. At the end of the day, if the cumulative hydrogen production exceeds demand, the evening hydrogen production plan can be reduced; if it is below demand and hydrogen storage is insufficient, compensatory hydrogen production is performed at night: battery storage unit 105, which has partially charged in the evening, will release its charge at night, for example, to power the PEM stack for several hours to produce additional hydrogen to meet targets. Furthermore, during off-peak hours at night when electricity prices are low and the grid's renewable energy ratio is high, inverter 108 purchases cheap, low-carbon electricity from the grid to drive the alkaline electrolyzer at low power to maintain continuity, while slightly increasing total hydrogen production.

[0084] Safety and Synergy: This embodiment pays special attention to safety control when alkaline and PEM are used in synergy. When the alkaline water electrolyzer unit enters operation from slow start mode, its temperature and pressure are controlled within the allowable process range. The proton exchange membrane electrolyzer unit 104 monitors its membrane temperature and hydration status during frequent start-ups and shutdowns to ensure it is not damaged by overcooling or overheating. The controller is prioritized; when an anomaly occurs, such as excessively high alkaline stack temperature, the controller will prioritize reducing the alkaline load, allocating more photovoltaic power to the PEM or cells, or even discarding photovoltaic power, until the temperature returns to normal. Similarly, when the PEM overheats, its unit operation is reduced. Oxygen generated by both types of electrolyzers is discharged into a collection pipeline. In the event of a power outage or other accident, it is purged with inert gas to avoid the safety hazard of hydrogen-oxygen mixing.

[0085] Example 4: Optimization configuration method of a hybrid hydrogen production system coupled with photovoltaic renewable energy

[0086] like Figure 2 As shown, the method in this embodiment includes the following:

[0087] Data acquisition and forecasting: Real-time monitoring of photovoltaic power generation, DC bus voltage, operating status parameters of the first and second electrolyzer stacks, hydrogen storage capacity, and battery energy storage unit status; acquisition of photovoltaic output forecasts, electricity price forecasts, and grid carbon emission intensity forecasts for the future predetermined period;

[0088] Hydrogen production plan formulation: Based on photovoltaic power output forecast, electricity price forecast and grid carbon emission intensity forecast information, combined with the predetermined hydrogen production target, optimize the calculation of the target hydrogen production power plan curve for each sub-period within the predetermined period. The optimization calculation objective is to minimize the operating cost and carbon emissions of the hydrogen production process, and constrain the cumulative hydrogen production to meet the target value.

[0089] Power distribution control: According to the target hydrogen production power plan curve, control the number of electrolyzer cells and current values ​​of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit in operation; when the actual photovoltaic power is higher than the planned value, prioritize increasing the input of the second electrolyzer stack to absorb the extra power; when the actual photovoltaic power is lower than the planned value, prioritize reducing the load of the second electrolyzer stack and coordinate the first electrolyzer stack to bear the average base hydrogen production load;

[0090] Energy storage and grid regulation: Real-time monitoring of DC bus power difference. If the instantaneous photovoltaic power exceeds the current absorption capacity of the electrolyzer, the battery energy storage unit is controlled to charge or the power is sent to the grid through the bidirectional inverter in the grid interface unit. If the photovoltaic power is insufficient to meet the planned hydrogen production power, the battery energy storage unit is controlled to discharge to supplement the power. The insufficient part is purchased from the grid according to the preset strategy.

[0091] Real-time correction and rolling optimization: The actual operating data is periodically compared with the target hydrogen production plan. When the cumulative deviation exceeds the threshold, the planned power curve is updated in real time and the subsequent scheduling strategy is corrected, forming a closed-loop scheduling optimization mechanism.

[0092] In power distribution control, the following strategies are adopted to maximize the utilization of photovoltaic power and smooth the load on the electrolyzer:

[0093] When the photovoltaic output power increases relative to the previous moment, the PEM electrolyzer cell with the longest idle time is selected to be put into operation until the photovoltaic output matches the total load of the first and second electrolyzer stacks, or all PEM electrolyzer cells are put into operation; if there is still surplus power, the number of alkaline electrolyzer cells in the first electrolyzer stack is further increased or the operating current is increased.

[0094] When the photovoltaic output power decreases, the PEM electrolyzer cell with the longest continuous operating time is shut down first. If the photovoltaic power cannot be matched even after all PEM electrolyzer cells have been disconnected, the number of operating units of alkaline electrolyzer cells in the first electrolyzer stack is further reduced.

[0095] Each time the operating status is adjusted, the duration of the state of all electrolytic cells is recorded, and the electrolytic cell cell with the longest continuous single state time is switched first, so as to realize the rotation operation and rest of the electrolytic cells.

[0096] In summary, this invention not only solves the technical problems of insufficient responsiveness or excessive cost of traditional single electrolyzer hydrogen production, but also provides a low-loss, highly flexible, and intelligent hybrid hydrogen production system architecture, which significantly improves the efficiency, economy, and engineering adaptability of photovoltaic hydrogen production, and has important industrial application value and promotion prospects.

[0097] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any other combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product, which includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions according to this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another.

[0098] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. This storage medium can be a read-only memory, a disk, or an optical disk, etc.

[0099] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hybrid hydrogen production system coupled with photovoltaic renewable energy, comprising a photovoltaic power generation unit, an alkaline water electrolyzer unit, a proton exchange membrane electrolyzer unit, a hydrogen storage unit, and a control unit, characterized in that: The DC output of the photovoltaic power generation unit supplies power to the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit via the DC bus. The alkaline water electrolyzer unit includes a number of alkaline electrolyzer cells connected in series to form a first electrolyzer stack. The proton exchange membrane electrolyzer unit includes a number of PEM electrolyzer cells connected in series to form a second electrolyzer stack. The first electrolyzer stack and the second electrolyzer stack are connected in parallel to the DC bus. The output of the photovoltaic power generation unit is directly connected to the first electrolytic cell stack and the second electrolytic cell stack via a DC bus, without any DC-DC power converter in between; each electrolytic cell battery connected in series in each electrolytic cell stack is connected to a controllable switch, which is used to switch in or out the corresponding alkaline electrolytic cell battery or PEM electrolytic cell battery under the command of the control unit, thereby changing the effective number of series electrolytic cell batteries and the total voltage of the first electrolytic cell stack or the second electrolytic cell stack. The hydrogen storage unit is connected to the hydrogen production outlet of the first electrolyzer stack and the second electrolyzer stack, and is used to collect and store hydrogen produced by the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit. The control unit is connected to the photovoltaic power generation unit, the alkaline water electrolyzer unit, the proton exchange membrane electrolyzer unit, and the hydrogen storage unit. The control unit is equipped with a dynamic electrolyzer switching algorithm, which is used to control the number and operating mode of the electrolyzer cells actually put into operation in the first electrolyzer stack and the second electrolyzer stack according to the real-time detected photovoltaic power generation and the operating status of the first electrolyzer stack and the second electrolyzer stack, so as to optimize the power matching relationship between photovoltaic power generation output and electrolyzer load. The expression for the dynamic electrolyzer switching algorithm is: In the formula, N active (t) represents the optimal number of electrolytic cells selected for operation at time t; N represents the total number of cells in all electrolytic cells; V e V is the voltage of a single cell in an electrolytic cell. mpp (t) represents the photovoltaic maximum power point voltage; λ is the equilibrium weighting factor, STA i STA j These represent the state durations of the i-th and j-th electrolytic cells, respectively. The system further includes a grid interface unit, which contains a bidirectional inverter for connecting the DC bus to an external AC grid; the control unit controls the operating mode of the bidirectional inverter according to a preset strategy, the preset strategy being: When the photovoltaic power generation exceeds the total load demand of the current hydrogen production system and the current grid electricity price is higher than the set upper limit threshold, the control unit will set the bidirectional inverter to grid-connected output mode and feed the excess power back to the AC grid. When the photovoltaic power generation capacity cannot meet the load demand of the hydrogen production system, and the current grid electricity price is lower than the set economic electricity purchase threshold, and the carbon emission intensity of the electricity provided by the grid is lower than the set environmental protection threshold, the control unit controls the bidirectional inverter to purchase electricity from the grid for hydrogen production.

2. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 1, characterized in that: The control unit includes an MPPT control module, which tracks the maximum power point of the photovoltaic power generation unit in real time. When the photovoltaic output power increases, the module selects and connects the electrolytic cell that has been idle for the longest time to start operation; when the photovoltaic output power decreases, the module selects and disconnects the electrolytic cell that has been running continuously for the longest time to stop operation, so that the total voltage of the first electrolytic cell stack and the second electrolytic cell stack is equal to the photovoltaic maximum power point voltage V. mpp (t) matching.

3. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 1, characterized in that: The ratio of the rated hydrogen production power of the first electrolyzer stack to the second electrolyzer stack is set according to the expected fluctuation characteristics of photovoltaic output, so that the first electrolyzer stack bears the average base hydrogen production load and the second electrolyzer stack bears the transient peak hydrogen production load. The rated power of the first electrolyzer stack accounts for 60% to 80% of the total hydrogen production power, and the rated power of the second electrolyzer stack accounts for 20% to 40% of the total hydrogen production power.

4. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 1, characterized in that: The control unit includes a prediction and scheduling module, which is used to acquire information on renewable energy generation capacity, electricity price, and grid carbon intensity within a predetermined period, and formulate a target hydrogen production power plan curve based on the acquired information; the control unit optimizes the operation of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit according to the target hydrogen production power plan curve, so that the cumulative hydrogen production reaches the target requirement at the end of the predetermined period, while minimizing operating costs and carbon emissions in each preset sub-period. The prediction and scheduling module is configured to dynamically adjust the hydrogen production load based on short-term climate forecast data, and optimize the operating status of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit. The load allocation formula is as follows: In the formula, P is the output flow rate of hydrogen. PV (t) represents the photovoltaic power generation, P elec (t) represents the total power of the first and second electrolytic cell stacks, η elec η represents the total efficiency of the first and second electrolytic cell stacks. PV For photovoltaic system efficiency.

5. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 1, characterized in that: The system also includes a battery energy storage unit connected to the DC bus via a bidirectional DC / DC converter. The control unit is further configured to monitor the power balance of the DC bus. When the photovoltaic power generation exceeds the hydrogen production power requirement of the electrolyzer battery, the control unit is charged to store the excess energy. When the photovoltaic power generation is insufficient, the control unit is discharged to provide power to the DC bus, thereby smoothing out power fluctuations in a short timescale.

6. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 5, characterized in that: The control unit adopts a multi-agent cooperative control architecture, which includes at least multiple agents for the battery energy storage unit, alkaline water electrolyzer unit, and proton exchange membrane electrolyzer unit. Each agent searches for its own optimal control strategy online based on a deep reinforcement learning algorithm, and works together to achieve comprehensive optimization control of the entire system.

7. The optimized configuration method for a hybrid hydrogen production system coupled with photovoltaic renewable energy as described in any one of claims 1-6, characterized in that, The method includes: Data acquisition and forecasting: Real-time monitoring of photovoltaic power generation, DC bus voltage, operating status parameters of the first and second electrolyzer stacks, hydrogen storage capacity, and battery energy storage unit status; acquisition of photovoltaic output forecasts, electricity price forecasts, and grid carbon emission intensity forecasts for the future predetermined period; Hydrogen production plan formulation: Based on the photovoltaic output forecast, electricity price forecast and grid carbon emission intensity forecast information, combined with the predetermined hydrogen production target, optimize the calculation of the target hydrogen production power plan curve for each sub-period within the predetermined period. The optimization calculation objective is to minimize the operating cost and carbon emissions of the hydrogen production process, and constrain the cumulative hydrogen production to meet the target value. Power distribution control: According to the target hydrogen production power plan curve, control the number of electrolyzer cells and current values ​​of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit that are put into operation; when the actual photovoltaic power is higher than the planned value, prioritize increasing the input of the second electrolyzer stack to absorb the extra power; when the actual photovoltaic power is lower than the planned value, prioritize reducing the load of the second electrolyzer stack and coordinate the first electrolyzer stack to bear the average base hydrogen production load; Energy storage and grid regulation: Real-time monitoring of DC bus power difference. If the instantaneous photovoltaic power exceeds the current absorption capacity of the electrolyzer, the battery energy storage unit is controlled to charge or the power is sent to the grid through the bidirectional inverter in the grid interface unit. If the photovoltaic power is insufficient to meet the planned hydrogen production power, the battery energy storage unit is controlled to discharge to supplement the power. The insufficient part is purchased from the grid according to the preset strategy. Real-time correction and rolling optimization: The actual operating data is periodically compared with the target hydrogen production plan. When the cumulative deviation exceeds the threshold, the planned power curve is updated in real time and the subsequent scheduling strategy is corrected, forming a closed-loop scheduling optimization mechanism.

8. The optimized configuration method according to claim 7, characterized in that: In the power distribution control, the following strategy is adopted to maximize the utilization of photovoltaic power and smooth the load of the electrolyzer: When the photovoltaic output power increases relative to the previous moment, the PEM electrolyzer cell with the longest idle time is selected to be put into operation until the photovoltaic output matches the total load of the first and second electrolyzer stacks, or all PEM electrolyzer cells are put into operation; if there is still surplus power, the number of alkaline electrolyzer cells in the first electrolyzer stack is further increased or the operating current is increased. When the photovoltaic output power decreases, the PEM electrolyzer cell with the longest continuous operating time is shut down first. If the photovoltaic power cannot be matched even after all PEM electrolyzer cells have been disconnected, the number of operating units of alkaline electrolyzer cells in the first electrolyzer stack is further reduced. Each time the operating status is adjusted, the duration of the state of all electrolytic cells is recorded, and the electrolytic cell cell with the longest continuous single state time is switched first, so as to realize the rotation operation and rest of the electrolytic cells.

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