Hybrid hydrogen production system coupled with photovoltaic renewable energy and optimal configuration method

Abstract

The invention discloses a hybrid hydrogen production system coupled with photovoltaic renewable energy and an optimal configuration method, and relates to the technical field of new energy utilization and energy storage control, and the hybrid hydrogen production system comprises a photovoltaic power generation unit, an alkaline water electrolytic tank unit, a proton exchange membrane electrolytic tank unit, a hydrogen storage unit, a control unit and the like. Photovoltaic electric energy is directly supplied to the two types of electrolytic cell stacks through the direct current bus, a traditional DC-DC power converter is omitted, and loss in the energy transmission process is reduced; and through a dynamic electrolytic cell switching algorithm configured by the control unit, the input proportion and the number of operation units of the two stacks are changed and adjusted in real time, and the quick response capability and the long-term stability are both considered. The system can stably produce hydrogen under the condition of renewable energy fluctuation, can dynamically adapt to input power change, can realize maximum power point tracking control on the premise of not using extra power conversion equipment, and remarkably reduces initial investment cost and operation energy consumption while ensuring hydrogen production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy utilization and energy storage control, and particularly to a hybrid hydrogen production system coupled with photovoltaic renewable energy and an optimal configuration method thereof. Background Art

[0002] With the growing global demand for carbon emission control and clean energy transformation, electrolyzing water to produce green hydrogen based on renewable energy (such as solar energy and wind energy) has become an important path to achieve a low-carbon energy structure. However, renewable energy has obvious intermittency and volatility characteristics. In particular, the output of photovoltaic power is significantly affected by weather and time periods, which poses challenges to the stability and efficiency of the hydrogen production system.

[0003] Currently, the commonly used electrolytic water hydrogen production technologies mainly include alkaline electrolyzers (AE) and proton exchange membrane electrolyzers (PEM). Among them, the AE technology is mature, has low cost, and is suitable for continuous and stable operation, but it responds slowly to power fluctuations and is not suitable for frequent start-stop or rapid power regulation; while the PEM electrolyzer has good fast response ability and is suitable for tracking the volatility of renewable energy, but its manufacturing cost is high and the system investment is large. In existing systems, a single type of electrolyzer is mostly used, which is difficult to balance efficiency, flexibility and economy, and cannot meet the dual requirements of renewable energy hydrogen production for response speed and cost control.

[0004] On the other hand, unreasonable energy storage configuration also limits the system performance. The battery energy storage system (BESS) has the ability of fast charge and discharge and can be used for short-term power buffering, but its capacity is limited and it is difficult to cover long-term fluctuations; while the hydrogen energy storage system (HESS) is suitable for long-term energy storage but it is difficult to provide fast response support. Currently, the hydrogen production system generally lacks a cooperative control strategy for BESS and HESS, and fails to effectively realize the 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 cause energy loss, but also increase the system cost and control complexity. Especially in large-scale hydrogen production projects, the conversion efficiency and economic problems are particularly prominent.

[0006] In the grid-connected operation scenario, how to balance economy and environmental protection is also a key issue. The electricity price and the carbon intensity of the power grid change significantly over time. If hydrogen can be produced by taking electricity during low electricity price and low carbon periods, and the surplus electric energy can be sent to the grid or stored during high electricity price periods, the hydrogen production cost and carbon footprint can be further reduced. However, the existing system lacks a dynamic prediction and optimal scheduling mechanism, and it is difficult to flexibly respond to short-term fluctuations while ensuring the long-term hydrogen delivery target, and to achieve the synergy optimization of economic benefits and environmental benefits.

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

[0008] In view of the above problems, the present 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 under high-proportion green electricity utilization.

[0009] The present invention achieves the above object 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 electrolysis cell unit, a proton exchange membrane electrolysis cell 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 electrolysis cell unit and the proton exchange membrane electrolysis cell unit through a DC bus. The alkaline water electrolysis cell unit includes a number of alkaline electrolysis cells connected in series to form a first electrolysis cell stack, and the proton exchange membrane electrolysis cell unit includes a number of PEM electrolysis cells connected in series to form a second electrolysis cell stack. The first electrolysis cell stack and the second electrolysis cell stack are connected in parallel to the DC bus;

[0012] The hydrogen storage unit is connected to the hydrogen production outlets of the first electrolysis cell stack and the second electrolysis cell stack for collecting and storing the hydrogen generated by the alkaline water electrolysis cell unit and the proton exchange membrane electrolysis cell unit;

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

[0014] The expression of the dynamic electrolysis cell switching algorithm is:

[0015]

[0016] In the formula, N active (t) is the optimal number of electrolysis cells selected and put into operation at time t; N is the total number of all electrolysis cells; V e is the single cell voltage of the electrolysis cell, V mpp (t) is the photovoltaic maximum power point voltage; λ is the equalization weight factor, STA i 、STAj They are the state durations of the i-th and j-th electrolytic cell batteries respectively.

[0017] As a preferred embodiment of the present invention, the control unit includes an MPPT control module, which is used to track the maximum power point of the photovoltaic power generation unit in real time. When the photovoltaic output power rises, select and connect the electrolytic cell battery with the longest current idle time to operate; when the photovoltaic output power drops, select and disconnect the electrolytic cell battery with the longest current continuous operation time to stop operating, so that the total voltage of the first electrolytic cell stack and the second electrolytic cell stack matches the photovoltaic maximum power point voltage V mpp (t).

[0018] As 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 through a DC bus, without a DC-DC power converter in between; each electrolytic cell battery connected in series in each electrolytic cell stack is equipped with a controllable switch, which is used to cut in or cut out the corresponding alkaline electrolytic cell or PEM electrolytic cell under the command of the control unit, so as to change the number of effective series-connected 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 rated hydrogen production power ratio of the first electrolytic cell stack and the second electrolytic cell stack is set according to the fluctuation characteristics of the expected photovoltaic output, so that the first electrolytic cell stack undertakes the average base hydrogen production load, and the second electrolytic cell stack undertakes the transient peak hydrogen production load;

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

[0021] As a preferred embodiment of the present invention, the control unit includes a prediction and scheduling module, which is used to obtain information on renewable energy power generation capacity, electricity price, and grid carbon intensity within a future predetermined period, and formulate a target hydrogen production power plan curve based on the obtained information; the control unit optimizes and schedules the operation of the alkaline water electrolysis cell unit and the proton exchange membrane electrolysis cell 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, and at the same time minimizes the operating cost and carbon emissions synergistically within each preset sub-period;

[0022] The prediction and scheduling module is configured to dynamically adjust the hydrogen production load based on short-term climate prediction data, and optimize the working states of the alkaline water electrolysis cell unit and the proton exchange membrane electrolysis cell unit. The load distribution formula is:

[0023]

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

[0025] As a preferred solution of the present invention, the system further includes a battery energy storage unit, and the battery energy storage unit is connected to the DC bus through 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 demand of the electrolyzer cell, the control unit controls the battery energy storage unit to charge to store excess energy. When the photovoltaic power generation is insufficient, the control unit controls the battery energy storage unit to discharge to provide electrical energy to the DC bus, thereby suppressing the power fluctuation within a short time scale.

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

[0027] As a preferred solution of the present invention, the system further includes a grid interface unit, and the grid interface unit includes a bidirectional inverter for connecting the DC bus to an external AC grid; the control unit controls the operation mode of the bidirectional inverter according to a preset strategy, and 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 sets the bidirectional inverter to the grid-connected output mode and feeds the excess electrical energy back to the AC grid;

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

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

[0031] Data acquisition and prediction: Real-time monitoring of the photovoltaic power generation, DC bus voltage, operating state parameters of the first electrolyzer stack and the second electrolyzer stack, hydrogen storage, and the state of the battery energy storage unit; obtaining information on photovoltaic power output prediction, electricity price prediction, and grid carbon emission intensity prediction within a future predetermined period;

[0032] Hydrogen production plan formulation: Based on the above-mentioned photovoltaic power output prediction, electricity price prediction, and grid carbon emission intensity prediction information, combined with a predetermined hydrogen production target, optimize and calculate the target hydrogen production power plan curve for each sub-period within a predetermined period. The optimization calculation target 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 electrolytic cell batteries and the current value of the alkaline water electrolyzer unit and the proton exchange membrane electrolyzer unit put into operation; when the actual photovoltaic power is higher than the planned value, preferentially increase the input of the second electrolyzer stack to absorb the extra power. When the actual photovoltaic power is lower than the planned value, preferentially reduce 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 monitor the DC bus power difference. If the instantaneous photovoltaic power exceeds the current absorption capacity of the electrolyzer, control the battery energy storage unit to charge or send power 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, control the battery energy storage unit to discharge and supplement, and the insufficient part is purchased from the grid according to a preset strategy;

[0035] Real-time correction and rolling optimization: Periodically compare the actual operation data with the target hydrogen production plan. When the cumulative deviation exceeds the threshold, update the planned power curve in real time and correct the subsequent scheduling strategy to form a closed-loop scheduling optimization mechanism.

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

[0037] When the photovoltaic output power increases compared with the previous moment, select the PEM electrolytic cell battery with the longest idle time to be put into operation until the photovoltaic output matches the total load of the first electrolyzer stack and the second electrolyzer stack, or all PEM electrolytic cell batteries have been put into operation; if there is still surplus power, further increase the number of alkaline electrolytic cell batteries in the first electrolyzer stack or increase the operating current;

[0038] When the photovoltaic output power drops, the PEM electrolyzer cells with the longest current continuous operation time are preferentially turned off in sequence. If all PEM electrolyzer cells have been disconnected and the photovoltaic power still cannot be matched, the number of operating units of the alkaline electrolyzer cells in the first electrolyzer stack is further reduced.

[0039] When adjusting the operating state each time, record the state duration of all electrolyzer cells, and preferentially switch the electrolyzer cell with the longest single-state duration to achieve the rotation operation and rest of the electrolyzer cells.

[0040] The beneficial effects of the present invention are as follows: The photovoltaic electric energy is directly supplied to the two types of electrolyzer stacks through the DC bus, omitting the traditional DC-DC power converter, reducing the losses in the energy transmission process (usually 5% - 10%), while simplifying the system composition and control link, and effectively improving the overall light-hydrogen conversion efficiency; The alkaline water electrolyzer cell units form the first electrolyzer stack as the main hydrogen production force for bearing stable loads, and the proton exchange membrane electrolyzer cell units form the second electrolyzer stack as a flexible unit for quickly adjusting peak loads. Through the dynamic electrolyzer switching algorithm configured by the control unit, the input ratio and the number of operating units of the two stacks can be adjusted according to the real-time change of the photovoltaic output power, taking into account the fast response ability and long-term stability, and avoiding energy waste or system impact caused by photovoltaic fluctuations; The system can stably produce hydrogen under the condition of renewable energy fluctuations, can dynamically adapt to the change of input power, and can achieve the maximum power point tracking (MPPT) control without using additional power conversion equipment, significantly reducing the initial investment cost and operating energy consumption while ensuring the hydrogen production efficiency. The electrolyzer cells are designed as a series structure controlled by controllable switches, with modular scheduling capabilities, and can expand the number of operating units or adjust the stack composition ratio according to requirements to adapt to the load requirements of different-scale photovoltaic systems, providing a feasible engineering path for large-scale photovoltaic hydrogen production scenarios. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0042] Among them:

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

[0044] Figure 2 is the method flow chart of the present invention.

[0045] Reference numerals in the figure: 101, photovoltaic power generation unit; 102, DC bus; 103, alkaline water electrolysis cell unit; 104, proton exchange membrane electrolysis cell unit; 105, battery energy storage unit; 106, hydrogen storage unit; 107, control unit; 108, grid interface unit. Detailed implementation manners

[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 of the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0047] Embodiment 1: Overall system architecture and working mode

[0048] The hybrid hydrogen production system as a whole can be regarded as a microgrid or energy hub powered by renewable energy, which couples multiple energy components and energy storage devices. The system mainly includes the following parts:

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

[0050] Hybrid water electrolysis hydrogen production module: It is composed of two types of water electrolysis hydrogen production devices, namely an alkaline electrolyzer and a proton exchange membrane electrolyzer (PEM Electrolyzer). The alkaline electrolyzer technology is mature and the hydrogen production cost is relatively low, but the start-up and load change response are slow; the PEM electrolyzer has a rapid response and strong adaptability to changes, but the cost is high. Coupling the two to form a hybrid water electrolysis hydrogen production module can simultaneously utilize the advantages of the alkaline electrolyzer being suitable for constant large loads and the PEM electrolyzer for rapid adjustment, and achieve efficient utilization of the fluctuating photovoltaic power supply. Each of the two types of electrolyzers is formed by connecting a number of single electrolyzer cell units in series to form a stack to adapt to a certain DC bus voltage. The alkaline and PEM stacks can be connected in parallel to the same DC bus, and the control system distributes their respective input powers.

[0051] Electric energy buffer and energy storage module: It 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 balance and buffering, quickly responding to short-term fluctuations in photovoltaic power output, and smoothing the power curve; the hydrogen storage unit is used to store hydrogen generated by the electrolyzer (such as a high-pressure hydrogen storage tank or a metal hydride storage tank) to achieve long-term energy storage. Hydrogen can be output as a final product for industrial, transportation, etc. use, or can be converted into electric energy through the back-end fuel cell power generation unit to supply power to the power grid or load during the low valley period of renewable energy, realizing the "electricity-hydrogen-electricity" recycling. According to specific application requirements, the system can choose whether to include a fuel cell power generation device; in the scenario emphasizing hydrogen production products, the fuel cell can not be installed, and only the hydrogen output interface is retained.

[0052] Power electronics and interface module: It is used to manage the electric energy exchange between different components, including a DC bus and necessary switch / conversion devices. In the preferred solution, the photovoltaic array is directly connected to the DC bus as much as possible, and the electrolyzer stack is connected to the bus through an electronic switch matrix to achieve dynamic adjustment of the equivalent load. The battery unit is connected to the DC bus through a bidirectional DC / DC converter to control its charge and discharge power. The system can also be connected to the AC power grid through an inverter for purchasing electricity from the grid or selling electricity to the grid when needed (grid connection interface). When the system is connected to the external power grid, the inverter and corresponding control can ensure the safety of the bidirectional power flow between the system and the grid and the power quality of the electric energy.

[0053] Intelligent control and energy management module: This is the "brain" of the system, including several parts such as sensing, communication, and control algorithms. The control module monitors 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 consumption load demand, grid electricity price, and carbon emission factor in real time through sensors. Based on the collected data, the control system runs an optimization algorithm to determine the operating status and power distribution of each component in real time, such as adjusting the number of alkaline / PEM electrolyzer battery units turned on, the charge and discharge power of the battery, whether to draw power from the grid or feed power to the grid, etc. The control module is implemented by a high-speed industrial controller or an industrial computer, and multiple control strategies are built in, including rule-based control and artificial intelligence algorithms, to ensure the optimized operation of the system on different time scales.

[0054] Overall, the system structure tightly couples the power generation, power consumption, and energy storage links to achieve the integration of power generation-storage-usage: The electric power generated by renewable energy such as photovoltaic is preferentially used to drive water electrolysis for hydrogen production, which is converted into chemical energy storage through the hydrogen storage module; at the same time, the battery is used 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 exchanges energy with the power grid, so as to make the most of green electric energy and ensure the continuous and reliable hydrogen production process.

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

[0056] As Figure 1 shown, the hybrid hydrogen production system in this embodiment includes a photovoltaic power generation unit 101, an alkaline water electrolysis cell unit 103, a proton exchange membrane electrolysis cell 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 electrolysis cell unit 103 and the proton exchange membrane electrolysis cell unit 104 via the DC bus 102. The alkaline water electrolysis cell unit 103 includes a number of alkaline electrolysis cells connected in series to form a first electrolysis cell stack, and the proton exchange membrane electrolysis cell unit 104 includes a number of PEM electrolysis cells connected in series to form a second electrolysis cell stack. The first electrolysis cell stack and the second electrolysis cell stack are connected in parallel to the DC bus 102.

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

[0059] The control unit 107 is connected to the photovoltaic power generation unit 101, the alkaline water electrolysis cell unit 103, the proton exchange membrane electrolysis cell unit 104, and the hydrogen storage unit 106. The control unit 107 is configured with a dynamic electrolysis cell switching algorithm, which is used to control the number and operation mode of the electrolysis cells actually put into operation in the first electrolysis cell stack and the second electrolysis cell stack according to the real-time detected photovoltaic power generation power and the operation states of the first electrolysis cell stack and the second electrolysis cell stack, so as to optimize the power matching relationship between the photovoltaic power generation output and the electrolysis cell load;

[0060] The expression of the dynamic electrolysis cell switching algorithm is:

[0061]

[0062] In the formula, N active (t) is the optimal number of electrolysis cells selected and put into operation at time t; N is the total number of all electrolysis cells; V e is the single cell voltage of the electrolysis cell, V mpp (t) is the photovoltaic maximum power point voltage; λ is the balance weight factor, STA i 、STA j are the state durations of the i-th and j-th electrolysis cells respectively.

[0063] The control unit is connected to each power device through industrial Ethernet or fieldbus, and exchanges control signals with devices such as battery DC / DC, inverters, switch matrices, valves, etc. It coordinates the power distribution among photovoltaic, two types of electrolyzers, batteries, and the power grid according to the established control strategy. The core basis for control decisions is real-time power balance and optimization objectives, such as maximizing the utilization of green electricity, meeting the hydrogen production target, minimizing costs / emissions, etc. Inside the controller, there are fast closed-loop controls (such as voltage and current loop controls to ensure the safe operation of the electrolyzer) and upper-layer decision-making algorithms (such as optimization scheduling strategies to determine the operating modes of each device).

[0064] Further, the control unit 107 includes an MPPT control module. The MPPT control module is used to track the maximum power point of the photovoltaic power generation unit 101 in real time. When the photovoltaic output power rises, it selects and turns on the electrolyzer battery with the longest idle time currently to put it into operation; when the photovoltaic output power drops, it selects and disconnects the electrolyzer battery with the longest continuous operation time currently to withdraw it from operation, so that the total voltage of the first electrolyzer stack and the second electrolyzer stack matches the photovoltaic maximum power point voltage V mpp (t).

[0065] The two electrolyzer stacks are connected in parallel to the DC bus. Each stack is composed of several electrolyzer cells connected in series and is equipped with electronic switches, enabling it to be switched by unit granularity (connecting or disconnecting some units). In the case of direct photovoltaic connection without a DC / DC, these switches are used to adjust the stack terminal voltage to achieve MPPT; that is, by changing the number of series-connected units to change the total voltage of the stack. When the two electrolyzers are connected at the same time, they share the current provided by the photovoltaic, and the specific current distribution depends on their respective instantaneous equivalent impedances, coordinated by the controller. In addition, the control system can selectively temporarily turn off a certain type of electrolyzer (such as turning off some alkaline electrolyzers at extremely low light levels and only keeping the PEM running) to optimize efficiency.

[0066] Specifically, the output of the photovoltaic power generation unit 101 is directly connected to the first electrolyzer stack and the second electrolyzer stack through the DC bus 102, without a DC-DC power converter in the middle; the electrolyzer cell units connected in series in the first electrolyzer stack and the second electrolyzer stack are all connected with controllable switches, which are used to cut in or cut out the corresponding alkaline electrolyzer cells or PEM electrolyzer cells under the instruction of the control unit 107, thereby changing the number of effective series-connected electrolyzer cell units and the total voltage of the first electrolyzer stack or the second electrolyzer stack.

[0067] Photovoltaic modules are connected in series and parallel to form an array, and the output terminals are connected to the DC bus of the system. To match the voltage requirements of the downstream hydrogen production load, the open-circuit voltage and MPP voltage of the photovoltaic array are coordinated with the rated voltage of the electrolyzer stack during design. For example, if the voltage of a single electrolyzer cell is about 2V and several are connected in series to obtain a stack rated voltage of 100V, the MPP voltage of the photovoltaic array should be designed near this voltage. If the output voltage of the photovoltaic array is higher than the demand of the electrolyzer stack, the system can use a DC / DC buck converter; however, in the preferred embodiment of the present invention, by increasing the number of series-connected electrolyzer units and other means, direct matching can be achieved without additional DC / DC conversion. This direct connection architecture reduces one level of energy conversion and improves efficiency.

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

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

[0070] Preferably, the control unit 107 includes a prediction and scheduling module for obtaining information on the renewable energy generation capacity, electricity price, and grid carbon intensity within a future predetermined period, and formulating a target hydrogen production power plan curve based on the obtained information; the control unit 107 optimally schedules the operation of the alkaline water electrolysis cell unit 103 and the proton exchange membrane electrolysis cell 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, and at the same time, the operating cost and carbon emissions are minimized in each preset sub-period;

[0071] The prediction and scheduling module is configured to dynamically adjust the hydrogen production load based on short-term climate prediction data and optimize the working states of the alkaline water electrolysis cell unit 103 and the proton exchange membrane electrolysis cell unit 104. The load distribution formula is:

[0072]

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

[0074] Furthermore, the system further includes a battery energy storage unit 105, and the battery energy storage unit 105 is connected to the DC bus 102 through 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 demand of the electrolytic cell, the control unit 107 controls the battery energy storage unit 105 to charge to store the excess energy. When the photovoltaic power generation is insufficient, the control unit 107 controls the battery energy storage unit 105 to discharge to supply electrical energy to the DC bus 102, thereby suppressing the power fluctuations within a short time scale.

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

[0076] The system further includes a grid interface unit 108, and the grid interface unit 108 includes a bidirectional inverter for connecting the DC bus 102 to an external AC grid; the control unit 107 controls the operation mode of the bidirectional inverter according to a preset strategy. The preset strategy is specifically as follows:

[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 threshold, the control unit 107 sets the bidirectional inverter to the grid-connected output mode and feeds the excess electrical energy back to the AC grid;

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

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

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

[0081] In terms of control, the system is configured with a central controller, which includes a combination of a PLC and an industrial control computer to achieve high-speed real-time control and advanced optimization operations. Sensors collect data such as photovoltaic voltage, current, DC bus voltage, electrolyzer current, voltage, temperature, battery voltage, current, SOC, hydrogen storage tank pressure, grid voltage frequency, electricity price, and carbon emission factor, and send them to the real-time control module and the planning optimization module. The real-time control module executes in a cycle at a frequency of 100 Hz and is responsible for voltage and current closed-loop and logic control, such as maintaining the stability of the DC bus voltage, performing the switching of the electrolyzer unit, 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: according to the predicted curve of solar radiation, electricity price, and carbon intensity for the next day, as well as the hydrogen delivery task, it solves a 24-hour optimization problem to determine the desired hydrogen production power, charge and discharge plan, and grid purchase and sale plan for each hour. The optimization goal is to minimize "operating cost + carbon cost", and the constraints include ensuring that the cumulative hydrogen production reaches the demand by the end of the day, power / energy range limitations of each device, etc. The optimization result is 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 base power according to the optimized plan (for example, when the planned hydrogen power is 2 MW, the corresponding alkaline stack outputs about 1.5 MW, and the PEM outputs about 0.5 MW). Real-time control makes adjustments based on the deviation of the actual PV output: If the actual PV is higher than the planned value, the excess part is judged by the algorithm whether it is short-term fluctuation or trend increase. For short-term fluctuations, the battery is directly commanded to charge and absorb; for continuous higher PV levels, the real-time control triggers the unit switching algorithm to increase the number of operating units of the PEM electrolyzer, gradually increasing from the planned 0.5 MW, for example, increasing one PEM electrolysis unit per second (about 0.004 MW increment) until the PV power is balanced or the PEM reaches full rating. When the PEM reaches full rating of 2 MW and there is still surplus PV, the system checks the status of the alkaline electrolyzer: If it is not yet fully loaded and the operating time is stable enough, the current of the alkaline electrolyzer is increased to increase its hydrogen production power to absorb the remaining power. At the same time, an instruction may be issued to reduce the charging of the battery to allow more PV to be directly used for hydrogen production. On the contrary, when the actual PV output is lower than the planned value, the control strategy first reduces the PEM electrolyzer units (one unit is removed per second until the PEM stack drops to the required power); if it is still insufficient, the battery is discharged or power is purchased from the grid as appropriate to keep the alkaline electrolyzer in the safe operating area. Unless in the case of extremely low irradiance, the alkaline stack is generally not easily shut down, but its minimum output is maintained to avoid the long startup time and low efficiency after shutdown.

[0083] Operating like this, almost all of the PV energy during the whole day is utilized: It is preferentially converted into hydrogen energy and stored in the hydrogen storage unit 106, secondly stored in the battery, and finally sent to the grid when the battery is full and less hydrogen is needed. The hydrogen storage unit 106 continuously accumulates hydrogen and monitors the pressure. The controller ensures that the hydrogen storage pressure does not exceed the safety threshold and controls the pressure by adjusting the hydrogen production power or starting the standby storage tank. At the end of the day, if the cumulative hydrogen production exceeds the demand, the hydrogen production plan for the evening can be reduced; if it is lower than the demand and the hydrogen storage is insufficient, compensatory hydrogen production is carried out at night: The battery energy storage unit 105 has been fully charged in the evening and will be released at night, for example, supplying 0.3 MW to the PEM stack to operate for several hours to produce additional hydrogen to meet the standard. In addition, when the grid electricity price is low at night and the renewable proportion of the grid is high, the inverter 108 purchases cheap and low-carbon electricity from the grid to drive the alkaline electrolyzer to operate at low power to maintain continuity, while slightly increasing the total hydrogen production.

[0084] Safety and coordination: This embodiment particularly focuses on safety control during the coordination of alkaline and PEM. When the alkaline water electrolysis cell unit enters operation from the slow start mode, its temperature and pressure are controlled within the process-allowed range; the proton exchange membrane electrolysis cell unit 104 monitors the hydration state of its membrane layer temperature during frequent start-stop operations to ensure that it is not damaged due to overcooling or overheating. The controller sets priorities. When an abnormality occurs, such as too high a temperature of the alkaline stack, the controller will preferentially reduce the alkaline load, allocate more photovoltaic power to PEM or the battery, or even discard photovoltaic power until the temperature returns to normal; similarly, when the PEM is overheated, the input of its unit is reduced. The oxygen generated by both types of electrolyzers is discharged into the collection pipeline and purged with inert gas in case of accidents such as power outages to avoid safety hazards of hydrogen-oxygen mixing.

[0085] Embodiment 4: Optimization Configuration Method of a Hybrid Hydrogen Production System Coupled with Photovoltaic Renewable Energy

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

[0087] Data acquisition and prediction: Real-time monitor the photovoltaic power generation, DC bus voltage, operating state parameters of the first electrolyzer stack and the second electrolyzer stack, hydrogen storage, and the state of the battery energy storage unit; obtain information on photovoltaic power output prediction, electricity price prediction, and grid carbon emission intensity prediction within a future predetermined period;

[0088] Hydrogen production plan formulation: Based on the photovoltaic power output prediction, electricity price prediction, and grid carbon emission intensity prediction information, combined with a predetermined hydrogen production target, optimize and calculate the target hydrogen production power plan curve for each sub-period within the predetermined period. The optimization calculation target 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 electrolysis cell unit and the proton exchange membrane electrolysis cell unit put into operation; when the actual photovoltaic power is higher than the planned value, preferentially increase the input of the second electrolyzer stack to absorb the additional power, and when the actual photovoltaic power is lower than the planned value, preferentially reduce 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 monitor the DC bus power difference. If the instantaneous photovoltaic power exceeds the current absorption capacity of the electrolyzer, control the battery energy storage unit to charge or send power 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, control the battery energy storage unit to discharge and supplement, and purchase electricity from the grid for the insufficient part according to the preset strategy;

[0091] Real-time calibration and rolling optimization: Periodically compare the actual operating data with the target hydrogen production plan. When the cumulative deviation exceeds the threshold, update the planned power curve in real time and correct the subsequent scheduling strategy to form a closed-loop scheduling optimization mechanism.

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

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

[0094] When the photovoltaic output power decreases, preferentially turn off the PEM electrolyzer cell with the longest current continuous operation time in sequence. If all PEM electrolyzer cells have been disconnected and still cannot match the photovoltaic power, further reduce the number of operating units of the alkaline electrolyzer cells in the first electrolyzer stack.

[0095] When adjusting the operating state each time, record the state duration of all electrolyzer cells and preferentially switch the electrolyzer cell with the longest single-state duration to achieve the rotation operation and rest of the electrolyzer cells.

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

[0097] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented using software, it can be implemented in whole or in part in the form of a computer program product, and the computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions according to the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium.

[0098] In addition, each functional unit in various embodiments of the present application may be integrated into a processing module, may exist separately as individual physical units, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the above-mentioned integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium. The storage medium may be a read-only memory, a magnetic disk, an optical disc, or the like.

[0099] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of various changes or substitutions thereof, and these should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection 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 electrolysis cell unit, a proton exchange membrane electrolysis cell 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 electrolysis cell unit and the proton exchange membrane electrolysis cell unit via a DC bus. The alkaline water electrolysis cell unit includes a number of alkaline electrolysis cell batteries connected in series to form a first electrolysis cell stack, and the proton exchange membrane electrolysis cell unit includes a number of PEM electrolysis cell batteries connected in series to form a second electrolysis cell stack. The first electrolysis cell stack and the second electrolysis cell stack are connected in parallel to the DC bus; The hydrogen storage unit is connected to the hydrogen production outlets of the first electrolysis cell stack and the second electrolysis cell stack, and is used to collect and store the hydrogen generated by the alkaline water electrolysis cell unit and the proton exchange membrane electrolysis cell unit; The control unit is connected to the photovoltaic power generation unit, the alkaline water electrolysis cell unit, the proton exchange membrane electrolysis cell unit, and the hydrogen storage unit. The control unit is configured with a dynamic electrolysis cell switching algorithm, which is used to control the number and operation mode of the electrolysis cell batteries actually put into operation in the first electrolysis cell stack and the second electrolysis cell stack according to the real-time detected photovoltaic power generation power and the operating states of the first electrolysis cell stack and the second electrolysis cell stack, so as to optimize the power matching relationship between the photovoltaic power generation output and the electrolysis cell load; The expression of the dynamic electrolysis cell switching algorithm is: Where N active (t) is the number of optimal electrolytic cell batteries selected for operation at time t; N is the total number of all electrolytic cell batteries; V e is the single-cell voltage of the electrolytic cell battery, V mpp (t) is the photovoltaic maximum power point voltage; λ is the equalization weight factor, STA i 、STA j are the state durations of the i-th and j-th electrolytic cell batteries, respectively.

2. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 1, wherein: The control unit includes an MPPT control module, which is used to track the maximum power point of the photovoltaic power generation unit in real time. When the photovoltaic output power rises, select and connect the electrolytic cell with the longest idle time currently to put into operation; when the photovoltaic output power drops, select and disconnect the electrolytic cell with the longest continuous operation time currently to withdraw from operation, so that the total voltage of the first electrolytic cell stack and the second electrolytic cell stack matches the photovoltaic maximum power point voltage V mpp (t).

3. The hybrid hydrogen production system integrating photovoltaic renewable energy according to claim 1, characterized in that: The output of the photovoltaic power generation unit is directly connected to the first electrolysis cell stack and the second electrolysis cell stack through the DC bus, without a DC-DC power converter in the middle. Each electrolysis cell battery connected in series in each electrolysis cell stack is connected with a controllable switch, which is used to cut in or cut out the corresponding alkaline electrolysis cell battery or PEM electrolysis cell battery under the instruction of the control unit, so as to change the number of effective series-connected electrolysis cell batteries and the total voltage of the first electrolysis cell stack or the second electrolysis cell stack.

4. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 3, wherein: The rated hydrogen production power ratio of the first electrolysis cell stack to the second electrolysis cell stack is set according to the fluctuation characteristics of the expected photovoltaic output, so that the first electrolysis cell stack undertakes the average base hydrogen production load, and the second electrolysis cell stack undertakes the transient peak hydrogen production load; The rated power of the first electrolysis cell stack accounts for 60% - 80% of the total hydrogen production power, and the rated power of the second electrolysis cell stack accounts for 20% - 40% of the total hydrogen production power.

5. 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 obtain information on the renewable energy power generation capacity, electricity price, and grid carbon intensity within a future predetermined period, and formulate a target hydrogen production power plan curve based on the obtained information; the control unit optimizes the operation of the alkaline water electrolysis cell unit and the proton exchange membrane electrolysis cell unit according to the target hydrogen production power plan curve, so that the cumulative hydrogen production output reaches the target requirement at the end of the predetermined period, and at the same time minimizes the operating cost and carbon emissions synergistically within each preset sub-period; The prediction and scheduling module is configured to dynamically adjust the hydrogen production load based on short-term climate prediction data, optimize the working states of the alkaline water electrolysis cell unit and the proton exchange membrane electrolysis cell unit, and the load distribution formula is: In the formula, is the output flow rate of hydrogen, P PV (t) is the photovoltaic power generation, P elec (t) is the total power of the first electrolyzer stack and the second electrolyzer stack, η elec is the total efficiency of the first electrolyzer stack and the second electrolyzer stack, η PV is the photovoltaic system efficiency.

6. The hybrid hydrogen production system coupling photovoltaic renewable energy according to claim 1, characterized in that: The system further includes a battery energy storage unit, which is connected to the DC bus through 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 demand of the electrolytic cell, the control unit controls the battery energy storage unit to charge to store the excess energy. When the photovoltaic power generation is insufficient, the control unit controls the battery energy storage unit to discharge to supply electrical energy to the DC bus, thereby suppressing the power fluctuation within a short time scale.

7. The hybrid hydrogen production system integrating photovoltaic renewable energy according to claim 6, wherein: The control unit adopts a multi-agent collaborative control architecture, at least including multiple agents for the battery energy storage unit, the alkaline water electrolysis cell unit, and the proton exchange membrane electrolysis cell unit. Each agent online searches for its own optimal control strategy based on the deep reinforcement learning algorithm, and collaboratively realizes the comprehensive optimal control of the entire system.

8. The hybrid hydrogen production system coupled with photovoltaic renewable energy according to claim 1, characterized in that: The system further includes a grid interface unit, which includes 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 is specifically: 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 threshold, the control unit sets the bidirectional inverter to the grid-connected output mode and feeds the excess electrical energy back to the AC grid; When the photovoltaic power generation cannot meet the load demand of the hydrogen production system, the current grid electricity price is lower than the set economic power purchase threshold, and the carbon emission intensity of the power provided by the grid is lower than the set environmental protection critical value, the control unit controls the bidirectional inverter to purchase electrical energy from the grid for hydrogen production.

9. The optimization configuration method of the hybrid hydrogen production system coupled with photovoltaic renewable energy according to any one of claims 1-8, characterized in that, The method includes: Data acquisition and prediction: Real-time monitoring of the photovoltaic power generation, DC bus voltage, operating state parameters of the first electrolysis cell stack and the second electrolysis cell stack, hydrogen storage, and the state of the battery energy storage unit; obtaining the predicted photovoltaic output, electricity price prediction, and grid carbon emission intensity prediction information within a future predetermined period; Hydrogen production plan formulation: Based on the predicted photovoltaic output, electricity price prediction, and grid carbon emission intensity prediction information, combined with a predetermined hydrogen production target, optimize and calculate the target hydrogen production power plan curve for each sub-period within the predetermined period. The optimization calculation target 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 electrolytic cells and the current value of the alkaline water electrolysis cell unit and the proton exchange membrane electrolysis cell unit put into operation; when the actual photovoltaic power is higher than the planned value, preferentially increase the second electrolysis cell stack input to absorb the additional power. When the actual photovoltaic power is lower than the planned value, preferentially reduce the load of the second electrolysis cell stack and coordinate the first electrolysis cell stack to bear the average base hydrogen production load; Energy storage and grid regulation: Monitor the DC bus power difference in real time. If the instantaneous photovoltaic power exceeds the current consumption capacity of the electrolyzer, control the battery energy storage unit to charge or send power 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, control the battery energy storage unit to discharge and supplement, and purchase power from the grid for the insufficient part according to the preset strategy; Real-time correction and rolling optimization: Periodically compare the actual operation data with the target hydrogen production plan. When the cumulative deviation exceeds the threshold, update the planned power curve in real time and correct the subsequent scheduling strategy to form a closed-loop scheduling optimization mechanism.

10. The optimization configuration method according to claim 9, characterized in that: In the power distribution control, the following strategy is adopted to maximize the utilization of photovoltaic power and smooth the electrolyzer load: When the photovoltaic output power increases compared with the previous moment, select the PEM electrolyzer cell with the longest idle time to operate until the photovoltaic output matches the total load of the first electrolyzer stack and the second electrolyzer stack, or all PEM electrolyzer cells have been put into operation; if there is still surplus power, further increase the number of alkaline electrolyzer cells in operation in the first electrolyzer stack or increase the operating current; When the photovoltaic output power decreases, preferentially turn off the PEM electrolyzer cell with the longest current continuous operation time in sequence. If the photovoltaic power still cannot be matched after all PEM electrolyzer cells have been disconnected, further reduce the number of operating units of the alkaline electrolyzer cells in the first electrolyzer stack; When adjusting the operation state each time, record the state duration of all electrolyzer cells, and preferentially switch the electrolyzer cell with the longest single-state duration to realize the rotation operation and rest of the electrolyzer cells.

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