A coordinated control method, device and system for an off-grid hydrogen synthesis ammonia system

Abstract

This disclosure relates to the field of industrial automation control technology, and in particular to a coordinated control method, apparatus, and system for an off-grid hydrogen production and ammonia synthesis system. The method includes: collecting system operation data of the off-grid hydrogen production and ammonia synthesis system, including energy storage state of charge (SOC), fan power limit, and hydrogen storage tank pressure; performing a first closed-loop adjustment based on the deviation between the SOC and a preset target SOC to obtain a total electrolysis target power; performing auxiliary adjustment of the fan power limit based on the SOC; performing a second closed-loop adjustment based on the deviation between the hydrogen storage tank pressure and a preset target pressure to obtain a synthesis ammonia target load; and outputting fan power limit commands, electrolysis power commands, and synthesis ammonia load commands. This disclosure uses the SOC and hydrogen storage tank pressure as dual core control variables to construct a dual-PI closed-loop decoupled control framework. Through coordinated adjustment of the entire source-storage-load chain, it significantly improves the system's operational stability and green energy consumption efficiency.

Description

Technical Field

[0001] This disclosure relates to the field of industrial automation control technology, and in particular to a coordinated control method, apparatus and system for an off-grid hydrogen production and ammonia synthesis system. Background Technology

[0002] Driven by the "dual carbon" goals, my country's installed capacity of renewable energy sources such as wind power and photovoltaics has continued to grow, making the issue of large-scale consumption increasingly prominent. Utilizing renewable energy sources like wind and solar to electrolyze water to produce hydrogen and further synthesize ammonia not only provides a high-value-added pathway for renewable energy consumption but also helps promote the electrification transformation of the traditional chemical industry. Ammonia is both an important basic chemical raw material and a potential green energy carrier, applicable to scenarios such as co-firing in thermal power plants and marine fuel. my country possesses a long coastline and abundant offshore wind power resources, with near-shore wind power typically exceeding 3,000 hours annually and offshore wind power exceeding 4,000 hours. If on-site ammonia synthesis from wind power can be achieved at sea, it can fully utilize high-quality offshore wind resources and leverage low-cost maritime transport to connect with domestic and international supply chains, demonstrating significant industrial development potential.

[0003] However, renewable energy-to-hydrogen and ammonia synthesis systems face a core contradiction: the upstream wind and solar power output exhibits significant fluctuations, while the downstream ammonia synthesis chemical process requires long-term, stable, and high-load operation; the dynamic characteristics of these two are difficult to directly match. In offshore scenarios, grid connection costs are high, making off-grid operation a more practical solution. In this case, the system needs to rely on electrochemical energy storage for grid connection and rapid regulation. Energy storage not only plays a conventional peak-shaving role but also provides grid support and energy support during periods of low wind power output. Changes in the energy storage's state of charge (SoC) are essentially a passive result of the continuous integration of source-load deviations. If relying entirely on energy storage to smooth out fluctuations, a large power and capacity configuration is required, leading to a significant increase in system investment.

[0004] Therefore, how to coordinate and regulate the loads of energy storage, electrolytic hydrogen production, hydrogen storage, and ammonia synthesis as an organic whole through system-level coordinated control, in order to reduce dependence on a single large-capacity energy storage system, has become a key technical problem that needs to be solved urgently for off-grid hydrogen production and ammonia synthesis systems. Summary of the Invention

[0005] In view of this, this disclosure proposes a coordinated control method, device and system for an off-grid hydrogen production and ammonia synthesis system.

[0006] According to one aspect of this disclosure, a coordinated control method for an off-grid hydrogen production and ammonia synthesis system is provided, the method comprising:

[0007] Collect system operation data of the off-grid hydrogen production and ammonia synthesis system, including energy storage state of charge, fan power limit, and hydrogen storage tank pressure;

[0008] Based on the deviation between the energy storage state of charge and the preset target state of charge, a first closed-loop adjustment is performed to obtain the total electrolysis target power.

[0009] The power limit of the wind turbine is adjusted auxiliaryly based on the energy storage state of charge.

[0010] Based on the deviation between the hydrogen storage tank pressure and the preset target pressure, a second closed-loop adjustment is performed to obtain the target load for ammonia synthesis.

[0011] Based on the total electrolysis target power, the adjusted fan power limit, and the ammonia synthesis target load, output the fan power limit command, the electrolysis power command, and the ammonia synthesis load command.

[0012] In one possible implementation, the system operating data further includes the energy storage charging and discharging power and the actual power of the electro-hydrogen production unit. The step of obtaining the total electrolysis target power by performing a first closed-loop adjustment based on the deviation between the energy storage state of charge and a preset target state of charge includes:

[0013] The deviation between the energy storage state of charge and the target state of charge is processed by dead zone and then input into the first proportional-integral controller.

[0014] Based on the output of the first proportional-integral controller and the energy storage charging and discharging power, an electrolysis power correction amount is generated;

[0015] The total electrolysis target power is generated based on the actual power of the electro-hydrogen production unit and the electrolysis power correction amount.

[0016] In another possible implementation, the auxiliary adjustment of the wind turbine power limit based on the energy storage state of charge includes:

[0017] When the energy storage state of charge is higher than the preset high charge threshold, the auxiliary proportional-integral controller is activated. The auxiliary proportional-integral controller takes the deviation between the energy storage state of charge and the target state of charge as input, and gradually reduces the wind turbine power limit according to the output of the auxiliary proportional-integral controller.

[0018] When the energy storage state of charge is lower than the preset high charge exit threshold, the auxiliary proportional-integral controller is deactivated, and the wind turbine power limit is gradually restored to the preset maximum power limit setting value.

[0019] In another possible implementation, the system operating data also includes the actual hydrogen compression inlet flow rate, and the second closed-loop adjustment based on the deviation between the hydrogen storage tank pressure and the preset target pressure to obtain the target ammonia synthesis load includes:

[0020] The deviation between the hydrogen storage tank pressure and the target pressure is processed by dead zone and then input into the second proportional-integral controller.

[0021] The basic ammonia synthesis load is calculated based on the actual hydrogen compression inlet flow rate.

[0022] The target ammonia load is generated based on the output of the second proportional-integral controller and the basic ammonia synthesis load.

[0023] In another possible implementation, the step of outputting the fan power limit command, the electrolysis power command, and the ammonia load command based on the total electrolysis target power, the adjusted fan power limit, and the ammonia synthesis target load includes:

[0024] Based on the energy storage state of charge and the hydrogen storage tank pressure, adjust the upper limit of the total electrolysis target power and / or set a protective flag, which is used to indicate whether to perform protective operations on the electro-hydrogen production unit and / or the ammonia synthesis unit in the off-grid hydrogen production and ammonia synthesis system.

[0025] Based on the total electrolysis target power, the adjusted fan power limit, the ammonia synthesis target load, the upper limit of the total electrolysis target power, and the protective flag, the fan power limit command, the electrolysis power command, and the ammonia synthesis load command are output.

[0026] In another possible implementation, the system operating data also includes the actual load of the ammonia synthesis unit, and the protective flags include a hydrogen production limitation flag, a low-pressure ammonia shutdown flag, and a low energy storage charge state shutdown flag. The adjustment of the upper limit of the total electrolysis target power and / or the setting of protective flags based on the energy storage charge state and the hydrogen storage tank pressure includes:

[0027] When the pressure of the hydrogen storage tank exceeds the preset high pressure threshold, the hydrogen production restriction flag is set to lock the hydrogen production restriction state, and the upper limit of the total electrolysis target power is adjusted according to the actual load of the ammonia synthesis unit. When the pressure of the hydrogen storage tank reaches the high pressure threshold and the ammonia synthesis unit is not running, the low energy storage charge state power outage flag is set to shut down the electro-hydrogen production unit. When the pressure of the hydrogen storage tank falls back to below the preset release threshold, the hydrogen production restriction flag is cleared to release the hydrogen production restriction state.

[0028] When the pressure of the hydrogen storage tank is lower than a preset low-pressure threshold, the low-pressure ammonia shutdown flag is set to shut down the ammonia synthesis unit. When the energy storage charge state is lower than a preset first low-charge threshold but higher than a preset second low-charge threshold, the low energy storage charge state power-off flag is set to shut down the electro-hydrogen production unit. When the energy storage charge state is lower than the second low-charge threshold, both the low energy storage charge state power-off flag and the low-pressure ammonia shutdown flag are set to shut down the electro-hydrogen production unit and the ammonia synthesis unit. The low-pressure ammonia shutdown flag is cleared to allow the ammonia synthesis unit to restart only when the energy storage charge state is higher than a preset ammonia synthesis start-up charge threshold and the hydrogen storage tank pressure is higher than a preset restart pressure threshold. The second low-charge threshold is less than the first low-charge threshold.

[0029] According to another aspect of this disclosure, a coordinated control device for an off-grid hydrogen production and ammonia synthesis system is provided, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above-described method.

[0030] According to another aspect of this disclosure, an off-grid hydrogen production and ammonia synthesis system is provided, comprising a wind power unit, an energy storage unit, an electro-hydrogen production unit, a hydrogen compression and storage unit, a nitrogen production unit, an ammonia synthesis unit, and a controller configured to perform the above-described method.

[0031] According to another aspect of this disclosure, a non-volatile computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the above-described method.

[0032] According to another aspect of this disclosure, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of the above-described method.

[0033] This disclosure constructs two independent yet coordinated continuous closed loops—a first closed loop and a second closed loop—by collecting system operation data and using the energy storage state of charge (SBC) and hydrogen storage tank pressure as feedback quantities for the electrical and hydrogen side balances, respectively. The first closed loop adjusts the total electrolysis target power in real time based on the deviation between the energy storage SBC and the target value, enabling the electrolysis hydrogen production process to actively track electrical power fluctuations. This frees the energy storage from being the sole object of rapid adjustment, effectively reducing the amplitude of energy storage charging and discharging and fluctuations in SBC, lowering the risks of overcharging, over-discharging, and high-frequency deep cycling, and extending the energy storage's lifespan. The second closed loop continuously adjusts the synthetic ammonia target load based on the deviation between the hydrogen storage tank pressure and the target value, maintaining the hydrogen storage pressure stably near the target value. This avoids large pressure fluctuations triggering high-pressure or low-pressure protection, while simultaneously achieving fine-grained continuous adjustment of the synthetic ammonia load rather than coarse-grained start-up and shutdown. Meanwhile, this disclosure also provides auxiliary adjustment for the wind turbine power limit, forming a clear adjustment sequence and division of responsibilities with the first and second closed loops. The three work together to maintain the supply and demand balance between the electric and hydrogen sides of the system, enabling the system to achieve stable power supply, stable hydrogen storage and continuous ammonia production even with a relatively small energy storage configuration, while taking into account system safety, operating economy and engineering feasibility.

[0034] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0035] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0036] Figure 1 A process flow diagram of an off-grid hydrogen production and ammonia synthesis system provided in an exemplary embodiment of this disclosure is shown.

[0037] Figure 2 A flowchart illustrating a coordinated control method for an off-grid hydrogen production and ammonia synthesis system provided in an exemplary embodiment of this disclosure is shown.

[0038] Figure 3 A flowchart of a coordinated control method for an off-grid hydrogen production and ammonia synthesis system provided by another exemplary embodiment of this disclosure is shown.

[0039] Figure 4 A schematic diagram illustrating simulation results provided by an exemplary embodiment of this disclosure is shown.

[0040] Figure 5 A schematic diagram of the operating curve of the system startup phase provided in an exemplary embodiment of this disclosure is shown.

[0041] Figure 6The diagram illustrates the operating curve of a synthetic ammonia system entering normal operation after initial startup, according to an exemplary embodiment of this disclosure.

[0042] Figure 7 This illustration shows a schematic diagram of the operating curves during a time window when the wind power output is relatively abundant, as provided in an exemplary embodiment of this disclosure.

[0043] Figure 8 A schematic diagram of the structure of a coordinated control device for an off-grid hydrogen production and ammonia synthesis system provided in an exemplary embodiment of this disclosure is shown.

[0044] Figure 9 This is a block diagram illustrating an apparatus according to an exemplary embodiment. Detailed Implementation

[0045] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0046] As used herein, the terms “comprising,” “including,” “having,” or variations thereof are open-ended and include one or more of the stated features, integrals, elements, steps, components, or functions, but do not exclude the presence or addition of one or more other features, integrals, elements, steps, components, functions, or groups thereof.

[0047] When an element is referred to as “connected,” “coupled,” “responding,” or a variation thereof relative to another element, it may be directly connected, coupled, or responding to another element, or there may be an intermediate element present.

[0048] Although the terms first, second, third, etc., may be used herein to describe various elements / operations, these elements / operations should not be limited by these terms. These terms are used only to distinguish one element / operation from another. Therefore, without departing from the teachings of this disclosure, a first element / operation in some embodiments may be referred to as a second element / operation in other embodiments.

[0049] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0050] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0051] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, data stored, data displayed, etc.) and signals involved in this application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant regions.

[0052] Off-grid hydrogen production and ammonia synthesis systems exhibit multi-timescale coupling characteristics in their control mechanisms. The randomness of wind power output causes continuous fluctuations in power output on the electricity side on a second-level timescale. Energy storage devices provide grid support and rapid power balancing. The hydrogen electrolysis stage itself has relatively fast power regulation capabilities, while the load adjustment and start-up / shutdown processes of the ammonia synthesis stage are limited by the characteristics of the chemical process, resulting in a significantly slower response speed. Meanwhile, energy storage and hydrogen storage devices provide capacity buffers on the electricity and hydrogen sides, respectively, creating conditions for supply and demand balancing at different timescales. Therefore, how to construct a coordinated control mechanism to address the differences in response speeds among the electricity, hydrogen, and ammonia stages, and how to achieve dynamic decoupling across multiple timescales through energy and hydrogen storage, are the core and critical issues in the control design of this type of system.

[0053] Current off-grid hydrogen production and ammonia synthesis control schemes suffer from at least the following shortcomings. First, they fail to establish independent and coordinated continuous closed loops around the electricity-side balance and hydrogen-side balance, lacking a system-level control framework for dynamic processes across multiple time scales. Second, they often treat energy storage as the primary or even sole object of rapid regulation, failing to fully utilize the active regulation capabilities of the electrolyzer to absorb source-load deviations. This leads to long-term deviations in the energy storage state of charge from the reasonable range, posing risks of overcharging, over-discharging, and high-frequency deep cycling. Third, they do not treat hydrogen storage pressure as an independent, continuous control variable, resulting in significant pressure fluctuations in the hydrogen storage tanks, easily triggering high-pressure or low-pressure protection, and limiting ammonia synthesis load to coarse-grained start-stop or inefficient regulation. Fourth, there is a lack of clear regulation sequence and division of responsibilities among wind turbine power limits, electrolysis load, and ammonia synthesis load, making it difficult to simultaneously meet multiple operational needs such as grid support, peak shaving, low-wind-crossing, and continuous ammonia production.

[0054] This disclosure provides a coordinated control method for an integrated system of wind power, energy storage, electrolytic hydrogen production, hydrogen storage, and ammonia synthesis applicable to off-grid scenarios. Particularly, it relates to a coordinated control method based on proportional-integral (PI) control of the energy storage state of charge and PI control of the hydrogen storage pressure. The purpose of this disclosure is to characterize the electrical balance using the energy storage state of charge and the hydrogen balance using the hydrogen storage pressure. Through the main PI loop of the energy storage state of charge, the hydrogen storage pressure PI loop, and the auxiliary PI loop for wind turbine power limiting under high charge conditions, unified coordination of wind turbine power limiting, electrolysis power, and ammonia synthesis load is achieved. To this end, this disclosure establishes independent but coordinated continuous closed loops around the balance of the electricity side and the hydrogen side, forming a multi-timescale control framework applicable to off-grid hydrogen production and ammonia synthesis systems. By constructing a control relationship of "hydrogen tracking electricity and ammonia tracking hydrogen," and by using two buffer links of electricity storage and hydrogen storage, dynamic decoupling between the electricity side and the chemical side is achieved. The active adjustment capability of the electrolyzer is used to absorb source-load deviation power as much as possible to minimize the fluctuation of energy storage SoC and reduce the burden of energy storage in grid support, peak shaving, and low-wind ride-through. Thus, stable power supply, stable hydrogen storage, continuous ammonia production, and effective improvement of wind power absorption rate are achieved with a smaller energy storage configuration.

[0055] This disclosure applies to a type of off-grid hydrogen production and ammonia synthesis system that primarily uses renewable energy sources and includes hydrogen production, storage, and ammonia synthesis stages. This system may include, but is not limited to, the following units: renewable energy power generation units, such as wind power units, photovoltaic power generation units, or combinations thereof; electrochemical energy storage units; electro-hydrogen production units, such as proton exchange membrane (PEM) electrolyzers, alkaline water electrolysis (ALK) electrolyzers, etc.; hydrogen purification, compression, and storage units; nitrogen production and supply units, such as pressure swing adsorption (PSA) nitrogen production and compression units; and ammonia synthesis units. The specific equipment types, capacity levels, connection methods, and layout locations of the above units can be adjusted according to the engineering scenario. Any system capable of coordinating electric power supply with buffering, hydrogen production, storage, and ammonia synthesis can adopt the control methods proposed in this disclosure.

[0056] Please refer to Figure 1This document illustrates a process flow diagram of an off-grid hydrogen production and ammonia synthesis system provided in an exemplary embodiment of this disclosure. The system includes a renewable energy power generation unit, an electrochemical energy storage unit, an electro-hydrogen production unit (including a power supply and purification device), a hydrogen compressor, a hydrogen storage tank, a PSA nitrogen production unit, a nitrogen compressor, a nitrogen buffer tank, an ammonia synthesis unit, and a liquid ammonia storage tank. The electricity generated by the renewable energy power generation unit is converted from AC to DC power; a portion is supplied to the electro-hydrogen production unit for water electrolysis to produce hydrogen, and the other portion powers other electrical loads in the system. The electrochemical energy storage unit is connected to the system busbar and is used to charge when there is surplus power and discharge when there is insufficient power, in order to maintain system power balance and voltage frequency stability. The hydrogen produced by the electro-hydrogen production unit is pressurized by the hydrogen compressor and then sent to the hydrogen storage tank for storage. The outlet of the hydrogen storage tank is connected to the ammonia synthesis unit, supplying hydrogen to it according to the ammonia synthesis load demand. The nitrogen produced by the PSA nitrogen production unit is pressurized by the nitrogen compressor and then sent to the nitrogen buffer tank, from which nitrogen is then stably supplied to the ammonia synthesis unit. Hydrogen and nitrogen react in the ammonia synthesis unit to produce liquid ammonia, which is then stored in a liquid ammonia storage tank. Through the coupling of the aforementioned power and material links, this system achieves a complete conversion from renewable energy to green ammonia.

[0057] This system, illustratively speaking, is a demonstration system for off-grid hydrogen production and ammonia synthesis with a capacity of thousands of tons. The renewable energy power generation unit consists of a wind turbine generator with a total load of approximately 3MW. The turbine is connected to a step-down transformer via a 35kV cable. The secondary side of the transformer is connected to a 400V busbar, and all system loads are connected to this 400V busbar. The electro-hydrogen production unit includes a 200Nm³ / h alkaline water electrolyzer and a 50Nm³ / h proton exchange membrane electrolyzer. The produced hydrogen is compressed to 15MPa by a hydrogen compressor and then stored in a high-pressure hydrogen storage tank. A regulating valve is installed at the outlet of the hydrogen storage tank to control the flow rate of hydrogen supplied to the ammonia synthesis unit. Part of the nitrogen produced by the PSA nitrogen production unit is used for system nitrogen purging, and the other part is used as feedstock for ammonia synthesis, being pressurized by a nitrogen compressor and then sent to the ammonia synthesis unit. The electrochemical energy storage unit is configured with 3000kW / 2000kWh. On the one hand, it provides voltage and frequency grid support and absorbs the power deviation caused by the inability of hydrogen production power to track wind power output. On the other hand, it provides energy support for the system during the low output phase of renewable energy.

[0058] Based on the above system structure, the control concept of this disclosure will be explained in general. This disclosure adopts a control architecture of "energy storage state-of-charge main PI loop + hydrogen storage pressure PI loop + high-charge state wind turbine power limiting auxiliary PI loop + threshold protection logic" to achieve coordinated regulation between the power side, hydrogen side, and source side. Among them, the energy storage SoC main closed loop serves as the first closed loop, which is used to correct the total electrolysis target power according to the SoC deviation under normal operating conditions to maintain the system power balance; the hydrogen storage pressure closed loop serves as the second closed loop, which is used to correct the synthetic ammonia target load or target hydrogen consumption flow rate according to the hydrogen storage pressure deviation to maintain the hydrogen supply and demand balance. When the SoC rises to the preset high-charge entry threshold, the wind turbine power limiting auxiliary PI loop is activated to gradually reduce the wind turbine power limit to suppress the source side input power; when the SoC falls back below the exit threshold, the auxiliary loop is deactivated, and the wind turbine power limit is gradually restored. In addition, under boundary conditions such as high voltage, low voltage, and low SoC, the system also introduces protection and stabilization logic such as threshold switching, integral limiting, dead zone, hysteresis, and speed limiting to avoid frequent start-stop, control oscillation, and integral saturation, and to ensure the stability and reliability of the control process.

[0059] From a time-scale perspective, the SoC main closed loop primarily handles the faster dynamics on the electrical side, while the hydrogen storage pressure closed loop primarily handles the slower dynamics on the hydrogen and chemical sides. The electrolysis hydrogen production stage rapidly adjusts the hydrogen production rate based on the SoC main closed loop results to track changes in electrical power; the ammonia synthesis stage adjusts the hydrogen consumption rate based on the hydrogen storage pressure closed loop results to track changes in hydrogen inventory. The energy storage device and hydrogen storage device act as buffer units on the electrical and hydrogen sides, respectively, separating rapid electrical power disturbances from slow chemical load disturbances at different time scales, achieving multi-time-scale decoupled control.

[0060] In this control method, the primary responsibility of the energy storage device is to provide source-load deviation power, maintain grid connection capability, and provide energy support during periods of low wind power output. Therefore, its SoC change reflects the remaining power deviation in the system that has not yet been absorbed by other actuators. Based on this, the electrolyzer, as an active actuator with rapid and continuous adjustment capabilities, is preferentially used to regulate the system's power absorption level to minimize the energy storage charging and discharging amplitude and SoC fluctuations. Only when the SoC continues to rise and exceeds the high-charge threshold is the wind turbine power-limiting auxiliary PI circuit further activated to suppress input power from the source side.

[0061] In summary, this method uses the energy storage SoC as a power balance characterization quantity to construct an energy storage PI controller, which outputs system power correction quantity to adjust the target power of the electrolyzer and, when necessary, triggers a power limiting command for the wind turbine. Using the pressure of the high-pressure hydrogen storage tank as a hydrogen-side supply and demand balance characterization quantity, a pressure PI controller is constructed to output the target load or target hydrogen consumption flow of the ammonia synthesis unit. Simultaneously, outside the dual PI closed loop, a start / stop state machine, upper and lower limit protection, integral limiting, dead zone, slope limiting, and start / stop hysteresis logic are set. The energy storage PI essentially controls the system's "electrolysis power absorption capacity," while the pressure PI controls the system's "ammonia synthesis hydrogen consumption capacity." These two control the electrical and hydrogen sides respectively, and are coordinated and coupled through the hydrogen storage tank, thereby supporting the stable operation of the off-grid system with a relatively small-scale electrochemical energy storage.

[0062] The above is the control concept of this disclosure. The following describes the coordinated control method of the off-grid hydrogen production and ammonia synthesis system provided by the embodiments of this disclosure using several exemplary models.

[0063] Please refer to Figure 2 This document illustrates a flowchart of a coordinated control method for an off-grid hydrogen production and ammonia synthesis system provided in an exemplary embodiment of this disclosure. This embodiment uses this method in the aforementioned system as an example for illustration. The method includes the following steps.

[0064] Step 201: Collect system operation data of the off-grid hydrogen production and ammonia synthesis system. The system operation data includes the energy storage state of charge, the limited power of the blower, and the pressure of the hydrogen storage tank.

[0065] System operation data refers to a set of quantifiable physical quantities that characterize the current real-time operating status of each unit in the off-grid hydrogen production and ammonia synthesis system, providing input for controller adjustment and decision-making. System operation data includes at least the energy storage state of charge, fan power limit, and hydrogen storage tank pressure.

[0066] The state of charge (SOC) of an energy storage device refers to the ratio of its current remaining usable energy to its rated usable energy, expressed as a percentage. It is a physical quantity that measures the current energy level of the energy storage device and can be obtained in real time through the Battery Management System (BMS).

[0067] The wind turbine power limit refers to the maximum allowable output power of the wind power generation unit, set by the wind turbine main control system or energy management system. Below this limit, the wind turbine converter executes maximum power point tracking or power dispatch commands. The wind turbine power limit value can be read in real time through the communication interface with the wind turbine main control system, or obtained from the wind turbine SCADA system via fieldbus or industrial Ethernet.

[0068] The pressure of a hydrogen storage tank refers to the real-time static pressure of the hydrogen medium inside the high-pressure hydrogen storage tank, measured in megapascals (MPa). This pressure can be collected in real time by a pressure transmitter installed on the hydrogen storage tank body or the outlet pipeline.

[0069] Data acquisition refers to the process of obtaining real-time operational data from various subsystems through sensors, transmitters, communication interfaces, or data buses. Data acquisition can be achieved through hard-wired analog sampling, or by reading data from the controllers or data acquisition systems of various subsystems via industrial communication protocols such as Modbus, CANopen, Profibus, and Ethernet / IP.

[0070] Step 202: Based on the deviation between the energy storage state of charge and the preset target state of charge, perform the first closed-loop adjustment to obtain the total electrolysis target power.

[0071] The target state of charge (SBC) refers to the control target value of the energy storage's SBC, which is a preset percentage setpoint. It is usually preset according to the optimal operating range, charging and discharging efficiency, and lifespan management requirements of the energy storage device, for example, set to 80%. This value can be set by the operator through the human-machine interface, or it can be adjusted online by the system's host computer according to the operating strategy.

[0072] Deviation refers to the difference between the actual value and the target value. In this step, the deviation is the difference between the energy storage state of charge and the target state of charge. When the deviation is positive, it indicates that the energy storage state of charge is higher than the target value, and the system is in a state of excess power; when the deviation is negative, it indicates that the energy storage state of charge is lower than the target value, and the system is in a state of power deficit.

[0073] The first closed-loop regulation refers to a feedback control process that uses the energy storage state of charge as the controlled variable, the total electrolysis target power as the operated variable, and the target state of charge as the setpoint. The first closed-loop regulation can be implemented in the following ways: One possible implementation is proportional-integral (PI) control: generating the regulation quantity based on the proportional and integral terms of the deviation, where the proportional term reflects the current deviation magnitude and the integral term eliminates steady-state error; another possible implementation is proportional-integral-derivative (PID) control: adding a derivative term to PI control to improve the response speed to rapid changes; another possible implementation is predictive control: predicting future deviation trends based on the system model and generating the regulation quantity in advance; yet another possible implementation is fuzzy control: mapping the deviation to the regulation quantity based on fuzzy rules, suitable for scenarios where it is difficult to establish an accurate mathematical model.

[0074] The input to the first closed-loop regulation is the deviation between the energy storage state of charge and the target state of charge, and the output is the adjustment amount used to correct the electrolysis power. The adjustment amount can be applied to the electrolysis power command itself, or it can be used as an increment or decrement of the current electrolysis power.

[0075] The total electrolysis target power refers to the total power target value that the entire electro-hydrogen production unit should achieve, which is equal to the sum of the power target values ​​of all online operating electrolyzers, and is expressed in kW or MW. The methods for determining the total electrolysis target power include, but are not limited to: adding a correction amount from the first closed-loop control output to the current actual total electrolysis power; directly outputting an absolute value from the first closed-loop controller as the total electrolysis target power; or determining it after being constrained by upper limits on electrolysis power (such as the maximum allowable power of the electrolysis equipment, the currently available power, etc.). The above methods can be flexibly selected or combined according to the actual system configuration and control requirements.

[0076] Step 203: Adjust the power limit of the wind turbine according to the energy storage state of charge.

[0077] Auxiliary regulation refers to additional control behavior relative to the first and second closed-loop regulation. Auxiliary regulation is activated only when the first closed-loop regulation cannot fully absorb excess power from the source side. It is used to suppress renewable energy input power from the source side to help maintain power balance on the power side. The control strength of auxiliary regulation is lower than that of the main closed-loop regulation; its role is to provide supplementary regulation when the main regulation capability is insufficient.

[0078] In this step, the wind turbine power limit is the regulated operating variable, and its value is dynamically adjusted according to the energy storage state of charge (SBC). Specifically, when the SBC remains high and exceeds a preset threshold, the maximum power injected into the system is limited by lowering the wind turbine power limit; when the SBC returns to the normal range, the wind turbine power limit is gradually restored to the maximum power limit setting. Auxiliary adjustment can be achieved in the following ways: One possible implementation is proportional-integral (PI) control: using the deviation (or its positive part) between the energy storage SBC and the target SBC as input to generate the adjustment amount for the wind turbine power limit; another possible implementation is proportional control: adjusting the wind turbine power limit only proportionally to the current deviation; another possible implementation is piecewise linear control: dividing the energy storage SBC into multiple intervals, each interval corresponding to a different wind turbine power limit adjustment range; yet another possible implementation is hysteresis control: setting entry and exit thresholds to prevent the wind turbine power limit from frequently operating near the threshold.

[0079] Step 204: Based on the deviation between the hydrogen storage tank pressure and the preset target pressure, a second closed-loop adjustment is performed to obtain the target load for ammonia synthesis.

[0080] The target pressure refers to the control target value of the hydrogen storage tank pressure. It is a preset pressure setpoint, usually set based on a combination of factors such as the design operating pressure of the hydrogen storage tank, the hydrogen supply pressure requirements of the downstream ammonia synthesis process, and the compressor outlet pressure. For example, it may be set to 15 MPa. This value can be preset by the operator or adjusted online according to the operating conditions of the ammonia synthesis process.

[0081] The second closed-loop regulation refers to a feedback control process that uses the hydrogen storage tank pressure as the controlled variable, the target ammonia load as the operating variable, and the target pressure as the setpoint. The second closed-loop regulation can be implemented in the following ways: One possible implementation is proportional-integral (PI) control: generating the ammonia load adjustment based on the proportional and integral of the hydrogen storage tank pressure deviation; another possible implementation is proportional-integral-derivative (PID) control: introducing a derivative term to improve dynamic response based on PI control; yet another possible implementation is feedforward-feedback composite control: introducing hydrogen yield or inlet flow rate as a feedforward signal based on pressure feedback to adjust the ammonia load in advance.

[0082] The input to the second closed-loop regulation is the deviation between the hydrogen storage tank pressure and the target pressure, and the output is the adjustment amount of the target load for ammonia synthesis. When the pressure deviation is positive (actual pressure is higher than the target pressure), the ammonia synthesis load is increased to consume excess hydrogen; when the pressure deviation is negative (actual pressure is lower than the target pressure), the ammonia synthesis load is decreased to reduce hydrogen consumption.

[0083] The target load for ammonia synthesis refers to the desired load setpoint for the ammonia synthesis unit, typically expressed as a percentage of ammonia production or the corresponding hydrogen consumption. Methods for determining the target load include, but are not limited to: adding a correction value from the second closed-loop control output to the current actual ammonia synthesis load; calculating the base load value based on the real-time hydrogen flow rate into the tank, then adding the correction value from the second closed-loop control output; or having the absolute value directly output by the second closed-loop controller as the target load. After determining the target load, constraints must be applied based on the minimum stable load, maximum allowable load, and load change rate limits of the ammonia synthesis unit to ensure that the generated load command meets the process safety requirements of the ammonia synthesis unit.

[0084] Step 205: Based on the total electrolysis target power, the adjusted fan power limit, and the ammonia synthesis target load, output the fan power limit command, the electrolysis power command, and the ammonia synthesis load command.

[0085] The electrolysis power command is generated based on the total electrolysis target power obtained after the first closed-loop adjustment in step 202. The controller converts this power value into a command format recognizable by the electro-hydrogen production unit and then sends it to the power controller of the electro-hydrogen production unit. The output method of the electrolysis power command depends on the control interface configuration of the electro-hydrogen production unit: for electrolyzers that support continuous power setting, the command is sent to the electrolyzer power supply or converter in analog or digital communication mode, and the power tracking is performed by the internal controller of the electrolyzer; for electrolyzers that only support stepped power adjustment, the command needs to be converted to the closest available step before being sent. When there are multiple electrolyzers in the system, the controller decomposes the total electrolysis target power into independent power commands for each electrolyzer, and the decomposition method is dynamically determined according to the operating status and adjustment capability of each electrolyzer. The format of the electrolysis power command can be in absolute value form, that is, the desired power value in kW or MW; or in relative value form, that is, the desired power value expressed as a percentage of rated power. Before sending an electrolysis power command, it is necessary to confirm that the electrolysis unit is in an operating state that allows it to receive power commands. If the state is not met, the electrolysis power command will remain at zero or maintain the current safe value.

[0086] The wind turbine power limiting command is generated based on the wind turbine power limiting value obtained after auxiliary adjustment in step 203. The controller encapsulates this value according to the communication protocol and command format agreed upon with the wind power generation unit, and then sends it to the wind turbine main control system or wind turbine converter. The wind turbine power limiting command can be in absolute form, i.e., the upper limit of active power in kW or MW; or in relative form, i.e., the upper limit expressed as a percentage of rated power. Before sending, the controller can perform a reasonableness check on the command based on the current operating status and available power of the wind turbine. When the current available power of the wind turbine is lower than the power limiting command value, the actual output of the wind turbine is determined by its maximum available power. At this time, the power limiting command does not actually have a constraint effect, but it is still issued as the upper limit value; when the current available power of the wind turbine is higher than the power limiting command value, the power limiting command is effective, and the wind turbine limits the output power below the command value by means of pitch or yaw.

[0087] The ammonia load command is generated based on the target ammonia load obtained after the second closed-loop regulation in step 204. The controller converts this load value into a command format recognizable by the ammonia unit and then sends it to the ammonia unit's control system. The ammonia load command is typically expressed as a load percentage or the corresponding hydrogen consumption flow rate; the specific format depends on the interface protocol of the ammonia unit's control system. When outputting the ammonia load command, the target ammonia load has already been constrained by minimum stable load constraints, maximum allowable load constraints, and load change rate limits. If the ammonia unit is currently in a state where it is not allowed to accept load commands, the ammonia load command remains at the current operating value or is executed according to the predetermined safety shutdown procedure.

[0088] Regarding communication output, the three control commands mentioned above can be sent to each actuator through one or more of the following methods: transmitting command values ​​to the actuator via analog output channels; sending start / stop or state switching commands via digital output channels; sending command values ​​in digital message form to the controllers of each subsystem via industrial fieldbus protocols or industrial Ethernet protocols; and issuing commands to each local control system via communication protocols such as OPC UA or MQTT. The communication protocol, data format, and transmission cycle of the three commands can be independently set according to the interface configuration of each actuator. The three commands can be issued synchronously within the same control cycle, or different issuance sequences can be used according to the response speed requirements of each actuator. The specific sequence is configured based on the communication response time of each actuator and the physical response characteristics of the actuator. Before each command is output, the controller confirms the normal status of the communication link with the corresponding actuator. If communication is interrupted or the actuator reports an abnormality, the controller will handle it according to the predetermined safety strategy to ensure system safety.

[0089] In summary, this disclosure constructs two independent yet coordinated continuous closed loops—a first closed loop and a second closed loop—by collecting system operation data and using the energy storage state of charge (SBC) and hydrogen storage tank pressure as feedback quantities for the electrical and hydrogen side balances, respectively. The first closed loop adjusts the total electrolysis target power in real time based on the deviation between the energy storage SBC and the target value, enabling the electrolysis hydrogen production process to actively track electrical power fluctuations. This frees the energy storage from being the sole object of rapid adjustment, effectively reducing the amplitude of energy storage charging and discharging and fluctuations in SBC, lowering the risks of overcharging, over-discharging, and high-frequency deep cycling, and extending the energy storage's lifespan. The second closed loop continuously adjusts the synthetic ammonia target load based on the deviation between the hydrogen storage tank pressure and the target value, maintaining the hydrogen storage pressure stably near the target value. This avoids large pressure fluctuations triggering high-pressure or low-pressure protection, while simultaneously achieving fine-grained continuous adjustment of the synthetic ammonia load rather than coarse-grained start-stop. Meanwhile, this disclosure also provides auxiliary adjustment for the wind turbine power limit, forming a clear adjustment sequence and division of responsibilities with the first and second closed loops. The three work together to maintain the supply and demand balance between the electric and hydrogen sides of the system, enabling the system to achieve stable power supply, stable hydrogen storage and continuous ammonia production even with a relatively small energy storage configuration, while taking into account system safety, operating economy and engineering feasibility.

[0090] Please refer to Figure 3 This document illustrates a flowchart of a coordinated control method for an off-grid hydrogen production and ammonia synthesis system provided in another exemplary embodiment of this disclosure. This embodiment uses this method in the aforementioned system as an example for illustration. The method includes the following steps.

[0091] Step 301: Collect system operation data of the off-grid hydrogen production and ammonia synthesis system. The system operation data includes energy storage state of charge, fan power limit, hydrogen storage tank pressure, energy storage charge and discharge power, actual power of the electro-hydrogen production unit, actual hydrogen compression and inlet flow rate, and actual load of the ammonia synthesis unit.

[0092] The controller collects real-time system operation data from the off-grid hydrogen production and ammonia synthesis system to obtain the current operating status of the system and provide input for subsequent control calculations. The collected data covers electrical and process quantities from multiple components, including the energy storage unit, wind power generation unit, electro-hydrogen production unit, hydrogen storage unit, and ammonia synthesis unit. Among them, the energy storage charging and discharging power is used to characterize the current positive and negative active power of the electrochemical energy storage device. A positive value indicates discharging, and a negative value indicates charging. The unit is kW or MW, which can be obtained through the power measurement module of the energy storage converter or the power calculation of the battery management system. The actual power of the electro-hydrogen production unit is the sum of the current actual power of all online operating electrolyzers, which can be read in real time through the power measurement module of each electrolyzer power supply or converter. The actual hydrogen compression inlet flow rate refers to the actual hydrogen flow rate sent into the hydrogen storage tank after being pressurized by the hydrogen compressor. The unit is Nm³ / h, which can be collected in real time by a mass flow meter or volume flow meter installed on the compressor outlet or hydrogen storage tank inlet pipe with temperature and pressure compensation. The actual load of the ammonia synthesis unit is used to characterize the current actual operating load of the ammonia synthesis unit. It is usually expressed as a percentage of the ammonia synthesis production or the corresponding actual hydrogen consumption flow rate, which can be read through the data interface of the ammonia synthesis unit control system.

[0093] As an illustration, the controller collects the following observations in real time: actual fan output. And fan power limit Energy storage state of charge and energy storage charging and discharging power Actual power of PEM electrolyzer Actual power of ALK electrolytic cell and their operating status , Hydrogen compressor inlet hydrogen flow rate Hydrogen storage tank pressure and hydrogen storage Actual load of the ammonia synthesis unit (based on hydrogen flow rate meter) and running status ; This indicates the discrete control time sequence number. In the above acquired signals, , , This is an optional parameter, and its acquisition can be selected based on system configuration and actual control requirements. The acquired data provides real-time status input for each adjustment step in this disclosure, ensuring that the controller can acquire complete system operation data within the same control cycle.

[0094] Step 302: The deviation between the energy storage state of charge and the target state of charge is processed by dead zone and then input into the first proportional-integral controller, and the electrolysis power correction amount is generated by combining the energy storage charging and discharging power.

[0095] The controller inputs the deviation between the energy storage state of charge and the target state of charge into the first proportional-integral controller after dead-zone processing; and generates an electrolysis power correction amount based on the output of the first proportional-integral controller and the energy storage charging and discharging power.

[0096] The first proportional-integral controller (PI controller) is a controller that takes the deviation between the energy storage state of charge (SBC) and the target SBC as input, and the electrolysis power correction as output, and operates according to proportional and integral control laws. Its proportional term is proportional to the current deviation and is used for rapid response; the integral term is proportional to the cumulative deviation and is used to eliminate steady-state error. The output of the PI controller is the sum of the proportional and integral terms, i.e., the calculation result of the PI controller itself. The electrolysis power correction is a correction value used to adjust the total power of the electro-hydrogen production unit. It is determined by subtracting the energy storage charging and discharging power from the output of the PI controller. When the energy storage is discharging, the energy storage charging and discharging power is positive, and the electrolysis power correction decreases accordingly, resulting in a downward adjustment of the electrolysis power. When the energy storage is charging, the energy storage charging and discharging power is negative, and the electrolysis power correction increases accordingly, resulting in an upward adjustment of the electrolysis power. This incorporates the real-time charging and discharging power of the energy storage into the adjustment of the electrolysis power. The electrolysis power correction can be positive or negative; a positive value indicates that the electrolysis power needs to be increased to absorb excess energy, while a negative value indicates that the electrolysis power needs to be reduced to alleviate the power shortage. Input refers to the action of transmitting the processed signal to the controller as the basis for calculation, which can be achieved through the controller's internal data bus or variable transmission. Generation refers to the process of calculating the output result based on the input data through the control algorithm. In this step, it is reflected in calculating the correction amount through the proportional-integral control law and superimposing the energy storage power onto the PI output in a feedforward manner.

[0097] In some embodiments, a SoC dead zone is set for the deviation between the energy storage state of charge and the target state of charge. When the absolute value of the deviation is less than or equal to a preset SoC dead zone threshold, the input of the first proportional-integral controller is treated as zero to avoid frequent adjustments by the controller when the energy storage state of charge fluctuates slightly near the target value.

[0098] Indicatively, the state of charge of energy storage With the target state of charge Deviation between Defined as:

[0099]

[0100] To reduce measurement noise and frequent controller actions caused by slight fluctuations, an explicit dead zone is set for the aforementioned deviation to obtain the effective deviation. :

[0101]

[0102] in, This is a preset SoC dead zone threshold. When the absolute value of the actual deviation is less than or equal to the SoC dead zone threshold, the controller input is zero, and no adjustment action is taken. When the absolute value of the deviation exceeds the SoC dead zone threshold, the controller input is the actual absolute value minus the SoC dead zone threshold, with the sign consistent with the actual deviation. This approach ensures that the controller does not act when the SoC deviates from the target value by a small amount, thus avoiding frequent adjustments.

[0103] Under normal operating conditions, the integral term of the main PI circuit of the electrolysis-side SoC for:

[0104]

[0105] in, This represents the saturation limiting function, used to restrict the integral term between preset upper and lower limits. The output of the main PI circuit of the electrolysis-side SoC is:

[0106]

[0107] in, This represents the proportional coefficient of the main PI circuit in the electrolysis-side SoC; This represents the integral coefficient of the main PI circuit of the electrolysis-side SoC; This represents the electrolysis power correction amount generated by the main PI circuit of the electrolysis-side SoC. The sum of the proportional and integral terms is the calculation result of the PI controller itself, and the electrolysis power correction amount is calculated by subtracting the energy storage charging and discharging power from this. When the energy storage discharges, If positive, the electrolysis power correction amount decreases accordingly; when the energy storage is being charged, A negative value results in a corresponding increase in the electrolysis power correction. This method superimposes the real-time charging and discharging power of the energy storage onto the PI output in a feedforward manner, enabling the adjustment of the electrolysis power to respond in advance to changes in the charging and discharging state of the energy storage. The electrolysis power correction can be positive or negative. A positive value indicates that the system has excess electrical power, requiring an increase in electrolysis power to absorb the excess energy; a negative value indicates that the system has insufficient electrical power, requiring a decrease in electrolysis power.

[0108] Step 303: Generate the total electrolysis target power based on the actual power of the electro-hydrogen production unit and the electrolysis power correction amount, and apply an upper limit constraint on the total electrolysis target power.

[0109] Generating the total electrolysis target power refers to the process of determining the total power target value that the electrolytic hydrogen production unit should achieve based on the current actual power of the electrolysis unit and the electrolysis power correction amount. The total electrolysis target power is determined by adding the electrolysis power correction amount to the current total actual electrolysis power, or it can be obtained by directly outputting the absolute value from the first proportional-integral controller and then processing it with constraints. Applying an upper limit constraint on the electrolysis power means limiting the total electrolysis target power to within the allowable maximum value range. This maximum value is determined comprehensively based on factors such as the rated power of the electrolysis equipment, the current available power, the equipment health status, and system protection requirements. The constraint application methods include clamping processing, where the upper limit value is used as the final value when the calculated value exceeds it, and rate limiting processing, where the rate of change of the target power is limited to the maximum allowable ramp rate of the electrolysis equipment. Applying this action ensures that the generated power command is within the physical operating limits of each electrolysis unit.

[0110] For illustrative purposes, assume the total actual electrolysis power is... The total electrolysis target power is generated according to the formula of "current total actual electrolysis power + electrolysis-side SoC correction amount":

[0111]

[0112] in, Indicates the first Total electrolysis target power at each control moment This represents a clamping function, used to restrict the evaluation result of an expression to between preset upper and lower limits. Indicates the first The upper limit of the electrolysis power allowed at each control moment is dynamically determined by the system based on factors such as the rated power of each electrolysis unit, the current available power, and system protection requirements. When the calculated value exceeds the upper limit, the upper limit value is used as the final value; when the calculated value is lower than zero, zero is used as the final value, thereby ensuring that the generated power command is within the physical operating limits of each electrolysis unit.

[0113] when When positive (e.g., SoC exceeds target value) When the system tends to increase the total electrolysis target power in order to reduce the SoC; when When the value is negative, the system tends to reduce the total electrolysis target power to allow the SoC to recover. Since energy storage devices in off-grid systems perform functions such as grid support, peak shaving, and low-wind-crossing support, changes in the energy storage SoC are a passive result of accumulated source-load deviations. Therefore, this disclosure uses the SoC deviation as a feedback signal to reduce the source-load deviation in reverse by adjusting the power absorbed by the electrolyzer, enabling the energy storage to bear as little long-term deviation power and energy fluctuation as possible, thus achieving active absorption of source-load deviations by the electrolyzer.

[0114] The aforementioned total electrolysis target power can be allocated among different types of electrolyzers, and this disclosure does not limit the allocation strategy. For example, power can be preferentially allocated to electrolysis equipment with slower dynamic response but suitable for stable operation to bear the base load. Once its load reaches a certain level, the remaining power can be allocated to electrolysis equipment with faster dynamic response to bear rapid adjustment. For instance, in a system containing both alkaline water electrolyzers and proton exchange membrane electrolyzers, power can be preferentially allocated to the alkaline water electrolyzer to bear the base load. Once its load reaches its upper limit, the remaining power can be allocated to the proton exchange membrane electrolyzer to bear rapid adjustment; the reverse is also possible. The allocation method can be flexibly determined based on the dynamic characteristics, minimum stable power, maximum power, and ramp rate of different electrolysis equipment. This is a preferred implementation of the dual closed-loop coordinated control of this disclosure at the equipment level, and not a limitation on the scope of application of this disclosure.

[0115] Step 304: When the energy storage state of charge is higher than the preset high charge entry threshold, the auxiliary proportional-integral controller is activated. The auxiliary proportional-integral controller takes the deviation between the energy storage state of charge and the target state of charge as input and gradually reduces the wind turbine power limit according to the output of the auxiliary proportional-integral controller. When the energy storage state of charge is lower than the preset high charge exit threshold, the auxiliary proportional-integral controller is deactivated and the wind turbine power limit is gradually restored to the preset maximum power limit setting value.

[0116] The auxiliary proportional-integral (PI) controller is a controller that takes the deviation (or its positive part) between the energy storage state of charge and the target state of charge as input, the wind turbine power limitation adjustment as output, and operates according to proportional and integral control laws. Its function is parallel to the first and second PPI controllers, specifically used to assist in adjusting the wind turbine power limitation. The wind turbine power limitation refers to the maximum allowable output power of the wind power generation unit, which is the object of adjustment in this step, and its value is dynamically adjusted based on the output of the auxiliary PPI controller. The preset maximum power limitation setting value refers to the maximum power limitation setting value that the wind turbine can output, that is, the maximum power limit that the wind turbine can achieve within its design allowable range, usually equal to the rated capacity of the wind turbine or the upper limit value set according to the system operation strategy.

[0117] Enabling refers to the process of starting the operation of a controller and connecting its output to the system control command chain. This is specifically implemented by initializing the controller's integral term to zero or a suitable current value before it begins operation, and by switching the controller's output from an invalid state to an active state. Reduction refers to gradually decreasing the wind turbine power limit value based on the output of the auxiliary proportional-integral controller, i.e., lowering the wind turbine's maximum power limit. Exit refers to switching the controller from an operating state to a non-operating state, including stopping the controller's integral operation, clearing its integral term, and disconnecting its output from the control command chain. Recovery refers to gradually increasing the wind turbine power limit value from its current value to the preset maximum power limit setting. Both reduction and recovery are executed gradually with preset step sizes or according to the output change rate of the auxiliary proportional-integral controller to avoid sudden changes in power commands impacting the system.

[0118] To avoid continuous reliance on electrolysis-side regulation under high SoC conditions, this disclosure further includes a wind turbine power limiting auxiliary PI circuit, which is used to actively suppress wind power input from the source side when the energy storage state of charge is consistently high.

[0119] The input to this auxiliary circuit is the fan auxiliary error under high SoC conditions. , defined as the positive part of the difference between the stored state of charge and the target state of charge:

[0120]

[0121] That is, the error term takes a positive value only when the energy storage state of charge is higher than the target value, and the controller starts to integrate; when the energy storage state of charge is lower than or equal to the target value, the error term is zero, and the controller does not produce any adjustment effect.

[0122] Its integral term for:

[0123]

[0124] The output of the fan power limiting auxiliary PI circuit can be written as:

[0125]

[0126] in, This represents the proportional coefficient of the auxiliary PI circuit for the power limiting of the wind turbine. This represents the integral coefficient of the auxiliary PI circuit for the power limiting of the wind turbine. This represents the equivalent correction amount used to reduce the power limit of the wind turbine.

[0127] The operating logic of this auxiliary circuit is as follows: when the energy storage is in a charged state... Higher than the preset high charge entry threshold When the fan power limiting auxiliary PI circuit is activated, the circuit adjusts according to the error. Continuous calculation of correction amount When the energy storage is in a state of charge Falling back to the high charge exit threshold When the following occurs, the auxiliary loop is deactivated and its integral term is cleared, and the controller stops adjusting. The high-charge entry threshold and high-charge exit threshold mentioned above are two different set values. The entry threshold is higher than the exit threshold, and the difference between the two constitutes the hysteresis interval to avoid frequent activation and deactivation of the controller when the energy storage state of charge fluctuates near the threshold.

[0128] During the operation of the auxiliary PI circuit for wind turbine power limiting, the wind turbine power limiting target is determined by the following formula:

[0129]

[0130] in, This indicates the maximum allowable power setting for the fan. When the power limit target value of the wind turbine is increased, the power input of the wind turbine decreases accordingly, thereby suppressing the wind power input; when When the power limit is reduced, the target value for the wind turbine power limit will increase accordingly.

[0131] When the auxiliary PI circuit for limiting wind turbine power is disengaged, the wind turbine power limit is no longer suppressed by the correction amount of the auxiliary circuit, but gradually recovers to the maximum power limit setting value according to the preset step size. The recovery process employs a gradual, incremental approach rather than a step-like recovery to avoid sudden changes in turbine output impacting the system's power balance. This auxiliary circuit only intervenes to regulate when the energy storage state of charge continuously exceeds the high-charge threshold; it does not participate in control under other operating conditions, thus ensuring that the turbine's output remains unaffected during normal operation.

[0132] Step 305: The deviation between the hydrogen storage tank pressure and the target pressure is processed by dead zone and then input into the second proportional-integral controller. Combined with the basic synthetic ammonia load calculated based on the actual hydrogen compression inlet flow rate, a synthetic ammonia target load is generated, and minimum stable load constraint, maximum load constraint, and rate of change constraint are applied to the synthetic ammonia target load.

[0133] The controller inputs the deviation between the hydrogen storage tank pressure and the target pressure into the second proportional-integral (PI) controller after dead-zone processing. Based on the actual hydrogen compression inlet flow rate, the baseline ammonia synthesis load is calculated. Based on the output of the second PI controller and the baseline ammonia synthesis load, the target ammonia synthesis load or target hydrogen consumption flow rate is generated, and minimum stable load constraints, maximum load constraints, and rate of change constraints are applied to the target ammonia synthesis load or target hydrogen consumption flow rate. The second PI controller is a controller that takes the deviation between the hydrogen storage tank pressure and the target pressure as input, the ammonia synthesis load correction as output, and operates according to proportional and integral control laws. The baseline ammonia synthesis load refers to the benchmark value of the ammonia synthesis load calculated based on the real-time hydrogen compression inlet flow rate according to stoichiometric relationships. Its physical meaning is the baseline load level at which the ammonia synthesis unit can operate stably under the current hydrogen production rate, which can be obtained by substituting the inlet hydrogen flow rate into the stoichiometric relationships of the ammonia synthesis reaction. The target ammonia synthesis load is determined by summing the baseline ammonia synthesis load and the ammonia synthesis load correction output by the second PI controller. Minimum stable load constraint refers to limiting the target load of ammonia synthesis to above the lowest load value that allows the ammonia synthesis unit to operate continuously and stably. Below this value, the ammonia synthesis reaction may fail to operate stably due to insufficient heat or material imbalance. Maximum load constraint refers to limiting the target load of ammonia synthesis to within the range of the maximum allowable load designed for the ammonia synthesis unit. Rate of change constraint refers to limiting the change in the target load of ammonia synthesis to within the preset maximum rate of change range in each control cycle, in order to avoid the impact of abrupt load changes on the ammonia synthesis process. Conversion refers to the calculation process of converting one physical quantity into another according to a defined correspondence. In this step, it is reflected in converting the hydrogen flow rate into the corresponding ammonia synthesis load value according to the stoichiometric relationship.

[0134] In some embodiments, a pressure dead zone is set for the deviation between the hydrogen storage tank pressure and the target pressure. When the absolute value of the deviation is less than or equal to a preset pressure dead zone threshold, the input of the second proportional-integral controller is set to zero to avoid frequent adjustments of the controller caused by pressure measurement noise or small fluctuations.

[0135] Indicative of the hydrogen storage tank pressure With target pressure Deviation between Defined as:

[0136]

[0137] To reduce pressure measurement noise and frequent controller actions caused by small fluctuations, a dead zone is set for the aforementioned deviation to obtain an effective pressure deviation. :

[0138]

[0139] in, This indicates the preset pressure dead zone threshold. The sign function is defined as follows: When the absolute value of the actual pressure deviation is less than or equal to the pressure dead zone threshold, the controller input is zero, and no adjustment action is generated; when the absolute value of the deviation exceeds the pressure dead zone threshold, the controller input is the value of the actual deviation minus the pressure dead zone threshold, and the sign is consistent with the actual deviation.

[0140] Error integral term for:

[0141]

[0142] in, This is a saturation limiting function used to limit the integral term between preset upper and lower limits to prevent integral saturation from causing a decrease in control performance. To control the cycle.

[0143] The pressure closed loop does not directly generate the absolute load, but first calculates the basic ammonia synthesis load based on the actual hydrogen compression inlet flow rate. Then, the pressure PI correction is added to obtain the target load for ammonia synthesis. :

[0144]

[0145] in, Indicates the pressure proportionality coefficient; This represents the pressure integral coefficient.

[0146] The basic ammonia synthesis load is proportional to the real-time hydrogen flow rate entering the tank, and the conversion relationship depends on the stoichiometry of the ammonia synthesis reaction and the rated design parameters of the system. This proportionality coefficient is defined as the conversion factor between the actual hydrogen flow rate entering the tank and the basic ammonia synthesis load, and its specific value is determined by the correspondence between the rated load of the ammonia synthesis unit and the corresponding rated hydrogen consumption flow rate. This coefficient can be pre-configured during controller initialization or adjusted and optimized online based on system operating data. In an illustrative embodiment, if the rated hydrogen consumption flow rate corresponding to a rated load of 100% for the ammonia synthesis unit is 2000 Nm³ / h, then the basic ammonia synthesis load conversion factor can be taken as 0.05%·h / Nm³, that is, every 100 Nm³ / h of actual hydrogen flow rate entering the tank corresponds to 5% of the basic ammonia synthesis load, but this value can be further optimized and adjusted according to the actual operating conditions of the system.

[0147] The pressure PI correction is an adjustment calculated by the pressure proportional-integral controller based on the hydrogen storage pressure deviation. It is used to maintain stable hydrogen storage pressure by adjusting the ammonia synthesis load when a deviation occurs between the actual hydrogen production and the ammonia synthesis load demand. If the hydrogen storage tank pressure is higher than the target pressure, then... If the pressure is positive, the controller increases the target load for ammonia synthesis to consume excess hydrogen; if the hydrogen storage tank pressure is lower than the target pressure, then... If the value is negative, the controller reduces the target load for ammonia synthesis to decrease hydrogen consumption.

[0148] After the target load for ammonia synthesis is determined, it is necessary to apply constraints based on the minimum stable load, maximum allowable load, and load change rate limits of the ammonia synthesis unit to ensure that the generated load command meets the process safety requirements of the ammonia synthesis unit. Specifically, the calculated value is first limited to between the minimum stable load and the maximum allowable load. Then, the rate of load change in adjacent control cycles is limited to ensure that the rate of change of the load command does not exceed the maximum allowable rate of change for the ammonia synthesis unit, thereby avoiding the impact of abrupt load changes on the ammonia synthesis process.

[0149] Step 306: Adjust the upper limit of the total electrolysis target power and / or set a protective flag based on the energy storage state of charge and hydrogen storage tank pressure. The protective flag is used to indicate whether to perform protective operations on the electro-hydrogen production unit and / or ammonia synthesis unit in the off-grid hydrogen production and ammonia synthesis system.

[0150] Protective indicators are control symbols used to indicate whether protective shutdown, startup, or power limiting operations should be performed on the electro-hydrogen production unit and / or the ammonia synthesis unit. Protective indicators include one or more of the following: hydrogen production limitation indicator, low-pressure ammonia shutdown indicator, and low energy storage charge state shutdown indicator. Each indicator corresponds to a different type of protective operation.

[0151] The hydrogen production restriction flag is a control flag used to indicate whether the system has entered a hydrogen production restriction state. When the hydrogen production restriction flag is set, it indicates that the system is in a high-pressure suppression state, and an upper limit needs to be applied to the total electrolysis target power. When the hydrogen production restriction flag is cleared, it indicates that the pressure of the hydrogen storage tank has returned to a safe range, and the hydrogen production restriction state is lifted.

[0152] The low-pressure ammonia shutdown indicator is a control flag used to indicate whether a protective shutdown of the ammonia synthesis unit should be performed. When the low-pressure ammonia shutdown indicator is set, it means that the hydrogen storage tank pressure is too low, and the ammonia synthesis unit needs to be shut down to prevent insufficient hydrogen supply from causing catalyst damage or abnormal reaction. When the low-pressure ammonia shutdown indicator is cleared, it means that the system has met the restart conditions and the ammonia synthesis unit can be restarted.

[0153] The low energy storage charge state power outage flag is a control flag used to indicate whether a protective shutdown of the electro-hydrogen production unit should be performed. When the low energy storage charge state power outage flag is set, it indicates that the energy storage charge state is too low, and the electro-hydrogen production unit needs to be shut down to ensure that the energy storage supplies power to the system's critical loads. When the low energy storage charge state power outage flag is cleared, it indicates that the energy storage charge state has returned to a safe operating range, and the electro-hydrogen production unit can be put back into operation.

[0154] Setting a flag means setting its status to an active state (logic "1" or "true"), indicating that the corresponding protection condition has been met and the appropriate protective operation needs to be performed. Clearing a flag means setting its status to an inactive state (logic "0" or "false"), indicating that the corresponding protection condition has been removed and normal operation can be resumed or a restart is allowed.

[0155] In some embodiments, when the hydrogen storage tank pressure exceeds a preset high-pressure threshold, the hydrogen production limitation flag is set to lock the hydrogen production limitation state, and the upper limit of the total electrolysis target power is adjusted according to the actual load of the ammonia synthesis unit. When the hydrogen storage tank pressure reaches the high-pressure threshold and the ammonia synthesis unit is not running, the low energy storage charge state power outage flag is set to shut down the electro-hydrogen production unit. When the hydrogen storage tank pressure falls below a preset release threshold, the hydrogen production limitation flag is cleared to release the hydrogen production limitation state. When the hydrogen storage tank pressure is below a preset low-pressure threshold, the low-pressure ammonia shutdown flag is set to shut down the ammonia synthesis unit. When the state of charge is lower than the preset first low charge threshold but higher than the preset second low charge threshold, the low energy storage charge state power outage flag is set to shut down the electro-hydrogen production unit. When the energy storage charge state is lower than the second low charge threshold, both the low energy storage charge state power outage flag and the low pressure ammonia shutdown flag are set to shut down the electro-hydrogen production unit and the ammonia synthesis unit. The low pressure ammonia shutdown flag is cleared only when the energy storage charge state is higher than the preset ammonia synthesis start-up charge threshold and the hydrogen storage tank pressure is higher than the preset restart pressure threshold, so as to allow the ammonia synthesis unit to restart. The second low charge threshold is less than the first low charge threshold.

[0156] The high-pressure threshold refers to the upper limit of the hydrogen storage tank pressure that triggers the high-pressure suppression state. When the hydrogen storage tank pressure exceeds this threshold, the system enters the high-pressure suppression state, sets the hydrogen production limit flag, and imposes an upper limit on the total electrolysis target power to prevent overpressure in the hydrogen storage tank. The release threshold refers to the lower limit of the hydrogen storage tank pressure that releases the high-pressure suppression state. When the hydrogen storage tank pressure falls below this threshold, the system releases the hydrogen production limit state, resets the hydrogen production limit flag, and restores the electrolysis power limit to its original setting. A hysteresis range exists between the release threshold and the high-pressure threshold to avoid frequent setting and resetting of the hydrogen production limit flag when the hydrogen storage tank pressure fluctuates near the high-pressure threshold. The low-pressure threshold refers to the lower limit of the hydrogen storage tank pressure that triggers the low-pressure holding state. When the hydrogen storage tank pressure is below this threshold, the system enters the low-pressure holding state, sets the low-pressure ammonia shutdown flag, and shuts down the ammonia synthesis unit to prevent insufficient hydrogen supply from damaging the ammonia synthesis catalyst or causing abnormal reactions. The first low-charge threshold refers to the upper limit of the energy storage state charge that triggers the low energy storage charge state charge holding state. When the energy storage state of charge (SBC) falls below this threshold, the system enters a low SBC protection state, setting the low SBC power outage flag and shutting down the electro-hydrogen production unit to reduce system load and prioritize power supply to critical loads. The second low SBC threshold is the lower limit of the SBC that triggers the extreme low SBC protection state; its value is less than the first low SBC threshold. When the SBC falls below this threshold, the system enters a minimum power consumption maintenance state, simultaneously setting the low SBC power outage flag and the low-pressure ammonia shutdown flag, shutting down the electro-hydrogen production unit and the ammonia synthesis unit to minimize system energy consumption and prevent over-discharge of energy storage that could lead to a complete system blackout. The ammonia synthesis start-up SBC threshold is the minimum SBC value required to allow the ammonia synthesis unit to restart. When the SBC is higher than this threshold and the hydrogen storage tank pressure is higher than the restart pressure threshold, the low-pressure ammonia shutdown flag is cleared, allowing the ammonia synthesis unit to restart. The restart pressure threshold is the minimum hydrogen storage tank pressure required to allow the ammonia synthesis unit to restart; its value is higher than the low-pressure threshold. When the hydrogen storage tank pressure exceeds the threshold and the state of charge (SBC) of the energy storage exceeds the ammonia synthesis start-up SBC threshold, the low-pressure ammonia shutdown flag is reset to zero, allowing the ammonia synthesis unit to restart. A hysteresis range exists between the restart pressure threshold and the low-pressure threshold to prevent frequent start-ups and shutdowns of the ammonia synthesis unit when the hydrogen storage tank pressure fluctuates near the low-pressure threshold. The hydrogen production limitation state refers to the system setting and maintaining the hydrogen production limitation flag when the hydrogen storage tank pressure exceeds the high-pressure threshold until the hydrogen storage tank pressure falls below the release threshold. The latching mechanism ensures that the hydrogen production limitation state remains effective once triggered, preventing frequent setting and resetting of the hydrogen production limitation flag due to brief fluctuations in the hydrogen storage tank pressure near the high-pressure threshold. In some embodiments, under the hydrogen production limitation state, adjusting the upper limit of the total electrolysis target power based on the actual load of the ammonia synthesis unit may include: the actual load of the ammonia synthesis unit is characterized by the actual hydrogen consumption flow rate, i.e., the actual hydrogen flow rate consumed by the ammonia synthesis unit under the current operating conditions, in Nm³ / h.There is a defined conversion relationship between the hydrogen production rate and electrolysis power of the hydrogen electrolysis unit, namely the unit power consumption coefficient for hydrogen production in the electrolyzer (unit: kWh / Nm³). Based on this conversion relationship, multiplying the actual hydrogen consumption flow rate of the ammonia synthesis unit by the unit power consumption coefficient for hydrogen production in the electrolyzer yields the equivalent electrolysis power value corresponding to the amount of hydrogen required to maintain the current ammonia synthesis load. Under hydrogen production restriction conditions, the upper limit of the total electrolysis target power is adjusted from the conventional electrolysis power upper limit to this equivalent electrolysis power value; that is, the final output value of the total electrolysis target power must not exceed this equivalent value. When the hydrogen production restriction condition is lifted, the upper limit returns to the conventional electrolysis power upper limit.

[0157] Through the above adjustments, the total electrolysis target power is always limited by the actual hydrogen consumption capacity of the downstream ammonia synthesis unit, ensuring that the electrolysis hydrogen production rate does not exceed the real-time hydrogen consumption rate of the downstream ammonia synthesis unit. This avoids the electrolysis system continuing to produce excessive hydrogen before the ammonia synthesis unit has reached its actual consumption capacity, which would cause the hydrogen storage tank pressure to rise continuously, thus ensuring the safe operation of the hydrogen storage system.

[0158] Optionally, in addition to the aforementioned conventional PI control states, the system also includes three boundary protection states: low SoC power-saving state, low voltage-saving state, and high voltage suppression state. The purpose of introducing these states is to divide the system operating range into a continuous control zone and a protection zone, thereby preventing control instability caused by continued reliance on continuous PI control under extreme operating conditions.

[0159] In low SoC power-saving mode, to avoid the system completely losing power due to the depletion of the energy storage SoC, further requirements are met under boundary conditions. Below the first low charge threshold And above the second low charge threshold season ;when Below the second lowest charge threshold At the same time, the electric hydrogen production unit and the ammonia synthesis unit will be shut down.

[0160] Under low-pressure holding conditions, the start-up and shutdown of the ammonia synthesis unit are constrained by the hydrogen storage pressure threshold. When the ammonia synthesis unit is already running, if the hydrogen storage pressure is lower than the low-pressure threshold... If the ammonia synthesis unit is not running, it will be shut down. When the ammonia synthesis unit is not running, it will be allowed to restart only when the SoC is higher than the ammonia synthesis start-up charge threshold and the hydrogen storage pressure is higher than the restart pressure threshold.

[0161] Under high-pressure suppression, this disclosure includes a hydrogen storage high-pressure latch-up mechanism for limiting hydrogen production. When the hydrogen storage pressure exceeds the high-pressure threshold, a hydrogen production limitation flag is activated. Under hydrogen production limitation, the controller applies an upper limit to the total electrolysis target power based on the actual absorption capacity of the ammonia synthesis unit. When the hydrogen storage pressure reaches the high-pressure threshold and the ammonia synthesis unit is not operating, the hydrogen production unit is preferably shut down directly, i.e., the hydrogen production unit is... When the hydrogen storage pressure falls below the release threshold, the hydrogen production restriction flag is lifted. If... Indicates the first The indicator of hydrogen production cuts at a given moment, If the high-pressure release threshold is represented, then the high-pressure hydrogen production limitation logic can be expressed as: when season ;when season .in, Used to determine whether a high-voltage suppression state has been entered. This mechanism is used to determine whether to exit the high-pressure suppression state. It prevents the electrolysis system from continuing to produce excessive hydrogen, leading to a sustained increase in hydrogen storage pressure, before the synthesized ammonia has reached a practical capacity for absorption.

[0162] Step 307: Output the fan power limit command, electrolysis power command, and ammonia synthesis load command.

[0163] In some embodiments, based on the total electrolysis target power, the adjusted fan power limit, the ammonia synthesis target load, the upper limit of the total electrolysis target power, and protective flags, the fan power limit command, the electrolysis power command, and the ammonia synthesis load command are output.

[0164] In this disclosure, the upper limit of the total electrolysis target power refers to the constraint value used to limit the total electrolysis target power before the electrolysis power command is generated. Its function is to ensure that the final issued electrolysis power command does not exceed the maximum value allowed by the system. It should be noted that this upper limit may be in different states under different operating conditions: When the hydrogen production restriction flag is not set (i.e., the hydrogen storage tank pressure is within the normal range), no upper limit constraint corresponding to the ammonia synthesis load is applied, and the upper limit of the total electrolysis target power remains at the conventional electrolysis power upper limit (e.g., the rated power of the electrolysis equipment, the currently available power, etc.). At this time, the upper limit value is the original value without adjustment. When the hydrogen production restriction flag is set (i.e., the hydrogen storage tank pressure exceeds the high-pressure threshold), the system enters the hydrogen production restriction state, and the upper limit of the total electrolysis target power is adjusted (i.e., reduced) to the equivalent electrolysis power value corresponding to the actual load of the ammonia synthesis unit. At this time, the upper limit value is the adjusted value. Regardless of the situation described above, in the step of outputting the electrolysis power command, the upper limit value determined at the current moment is used as the limiting basis. That is, the total electrolysis target power is compared with the upper limit value, and the smaller of the two is taken as the final electrolysis power command issued.

[0165] The wind turbine power limiting command is generated based on the adjusted wind turbine power limiting value. Specifically, the wind turbine power limiting value determined by the aforementioned auxiliary regulation serves as the upper limit of wind turbine output. This value is then encapsulated by the controller and sent to the wind turbine main control system or wind turbine converter. The electrolysis power command is generated based on the total electrolysis target power and its upper limit. The first closed-loop regulation first determines the total electrolysis target power, then limits it based on the upper limit before sending the final power value to the power controller of the electro-hydrogen unit. The ammonia synthesis load command is generated based on the ammonia synthesis target load and protective flags. The ammonia synthesis target load, determined by the second closed-loop regulation, is converted into a load setpoint recognizable by the ammonia synthesis unit after being enabled by various protective flags and sent to the ammonia synthesis unit's control system. When a protective flag indicates shutdown or power limiting, the output of the corresponding command is overridden or limited by the protection logic. When the protective flag is not triggered, the three commands are output normally according to the aforementioned adjustment results.

[0166] As an illustration, the control targets and safety thresholds can be set as follows: the target state of charge (SBC) for energy storage is set to 0.80, the high charge exit threshold is set to above 0.81, the high charge entry threshold is set to above 0.86, the first low charge threshold is set to below 0.60, and the second low charge threshold is set to below 0.30; the target pressure for the hydrogen storage tank is set to 15 MPa, the low pressure threshold is set to 12.5 MPa, the restart pressure threshold is set to 13.5 MPa, and the high pressure threshold is set to 16 MPa. A pressure dead zone of approximately 0.1 MPa is set in the pressure control to reduce frequent adjustments under small disturbances. In addition, based on the equipment characteristics, the following constraints are also set: the ammonia synthesis load is set with a minimum stable load and a maximum allowable load, and a load change rate limit is set; the electrolyzer power is set with minimum operating power, maximum operating power, and ramp rate limits, with the proton exchange membrane electrolyzer prioritizing rapid adjustment tasks, and the alkaline water electrolyzer mainly handling stable base load.

[0167] The method disclosed herein is executed cyclically according to a control cycle, with a typical embodiment having a control cycle of 1 second. First, signal acquisition is performed to obtain relevant operating signals from each stage of the process: wind turbine, energy storage, electrolysis, hydrogen storage, and ammonia synthesis. Then, a closed-loop control of the energy storage state of charge (SOC) and electrolysis power is executed. The SOC deviation is calculated, and after dead-zone processing, the electrolysis power correction is generated by the main proportional-integral loop of the SOC on the electrolysis side. Based on the actual total electrolysis power and this correction, the total electrolysis target power is generated. Next, a control loop of the energy storage SOC and wind turbine power limit is executed. When the SOC reaches the high-charge entry threshold, the auxiliary proportional-integral loop for wind turbine power limit is activated to generate the wind turbine power limit target. When the SOC falls back to the exit threshold, the auxiliary loop is deactivated, and the wind turbine power limit is gradually restored. Simultaneously, a closed-loop control system for hydrogen storage pressure and ammonia synthesis load is executed. The hydrogen storage pressure deviation is calculated, and a correction for the ammonia synthesis load is generated using the proportional-integral (PI) loop of the hydrogen storage pressure. Based on the baseline ammonia synthesis load and the PI correction, the target ammonia synthesis load is generated, and the start / stop of ammonia synthesis is determined by combining the energy storage state of charge and pressure threshold. Then, state judgment and protection logic are executed, implementing hydrogen production limitation, shutdown, and protection actions under boundary conditions such as high pressure, low pressure, and low energy storage state of charge. Finally, commands are output, including fan power limitation, electrolysis power, and ammonia synthesis load commands, completing all operations for the current control cycle and entering the next cycle.

[0168] To verify the effectiveness of the coordinated control algorithm proposed in this disclosure, simulation tests were conducted using simulated second-level wind turbine output curves, with a total simulation time of approximately 650 hours. This example simulates the system startup and operation process under fluctuating wind power output conditions. A schematic diagram of the simulation results is shown below. Figure 4 As shown.

[0169] Figure 4The table, from top to bottom, shows: the curves of wind turbine power limit versus actual wind turbine power, energy storage power versus hydrogen production power and auxiliary power, hydrogen production flow rate versus ammonia synthesis hydrogen consumption flow rate, and energy storage state of charge versus hydrogen storage tank pressure. Simulation results show that the proposed operation control strategy can automatically coordinate hydrogen production power and ammonia synthesis load under fluctuating wind power output conditions, achieving an overall control effect of "hydrogen following wind, ammonia following hydrogen." Hydrogen production tracks wind power output changes at a relatively fast adjustment rate, while ammonia synthesis tracks hydrogen production changes at a relatively slow adjustment rate, thus maintaining the energy storage state of charge and hydrogen storage tank pressure within a controllable range. Specifically, the energy storage performs peak-shaving functions, with its state of charge fluctuating between preset upper and lower limits (approximately 30% to 86%); the hydrogen storage tank pressure initially rises from atmospheric pressure to a working pressure of 15 MPa, then fluctuates around 15 MPa, with a fluctuation range of approximately 12.5 MPa to 16 MPa, also remaining within preset upper and lower limits. The above results show that the proposed control strategy can effectively control the energy storage state of charge and tank pressure within a given safe range, avoiding overcharging or over-discharging, and ensuring the safe operation of the system while fully leveraging the buffering effects of energy storage and hydrogen storage.

[0170] Next, we will conduct an in-depth analysis of several typical operational phases of the system.

[0171] Figure 5 A schematic diagram of the operating curve during the system startup phase provided by an exemplary embodiment of this disclosure is shown. The initial simulation conditions are set as follows: the initial state of charge of the battery storage is 50%, and the initial pressure of the hydrogen storage tank is approximately 2 MPa (this is only an example; the same strategy applies to the case where the initial pressure of the hydrogen storage tank is atmospheric pressure of 0.1 MPa).

[0172] The operational characteristics of this stage are analyzed as follows:

[0173] (1) After the battery state of charge (SOC) rapidly increased from 50% to around 80%, it began to fluctuate slightly around 80%. Only in the period between approximately the 6th and 8th hour did the SOC of the energy storage experience a significant drop due to the lower wind power output, falling to a minimum of approximately 70%, which is the preset SOC threshold for electrolyzer shutdown. Because the electrolyzer load adjustment rate is relatively fast, it can effectively track changes in wind power output, thereby maintaining the overall stability of the SOC of the energy storage.

[0174] (2) The upper limit of the wind turbine power limit is set at 1800kW, which is slightly higher than the total system load, resulting in an overcharging trend in the energy storage state of charge. When the energy storage state of charge exceeds 86%, the wind turbine power limit control loop is triggered, the power limit value is reduced, and the energy storage state of charge is pulled back to 80%. When the energy storage state of charge drops below 81%, the control loop is deactivated, and the wind turbine power limit value gradually recovers to 1800kW at the set rate. This process causes the wind turbine power limit value to exhibit a downward periodic sawtooth fluctuation, while the energy storage state of charge also fluctuates within a small range, typically in the hours 0 to 4, 8 to 11, 20 to 24, and 25 to 29.

[0175] (3) The energy storage charging and discharging power exhibits high-frequency fluctuations, mainly because it plays a role in maintaining the instantaneous power balance of the system. In order to avoid long-term unidirectional charging and discharging of energy storage, the strategy proposed in this disclosure uses the real-time power of energy storage superimposed with the state of charge correction term to adjust the target value of hydrogen production power, thereby controlling the energy storage power near zero and making the state of charge fluctuate around 80% of the target value, as shown in the typical range from the 15th to the 20th hour.

[0176] (4) In the initial stage, the ammonia synthesis unit has not yet started up, there is no downstream hydrogen load, and the hydrogen storage tank is in a state of continuous pressurization. Ammonia synthesis begins to start up when the hydrogen storage tank pressure reaches the minimum pressure required for ammonia synthesis startup (13.5 MPa in this example, around the 30th hour). However, since the ammonia synthesis startup process takes a long time (10 hours in this example), the hydrogen storage tank pressure continues to rise during the startup period. Around the 34th hour, the hydrogen storage tank pressure reaches the preset high-pressure threshold of 16 MPa, but at this time the ammonia synthesis has not yet finished starting up and there is no hydrogen consumption. To avoid overpressure of the storage tank, the high-pressure production limitation logic in this strategy is triggered, shutting down hydrogen production. At this time, because the system electrical load is low, the fan power limitation control loop is also triggered, and the fan power limitation value is reduced to the level that only supplies the auxiliary system electrical load, as shown in the typical range from the 34th to the 41st hour.

[0177] (5) By the 41st hour, the ammonia synthesis was completed and the pressure of the hydrogen storage tank began to drop. The high-pressure production restriction logic was lifted, hydrogen production was restarted, and the power limit value of the blower gradually returned to the normal level.

[0178] Figure 6 The diagram illustrates the operating curve of a synthetic ammonia system entering normal operation after initial startup, according to an exemplary embodiment of this disclosure.

[0179] In terms of operational characteristics, the ammonia synthesis plant completed its startup and entered normal operation between the 41st and 69th hours. During this period, the hydrogen production load generally tracked the changes in wind power output at a relatively fast rate, while the ammonia synthesis load tracked the changes in hydrogen production flow rate at a slower rate, demonstrating the multi-timescale coordinated control characteristics of "hydrogen following wind and ammonia following hydrogen."

[0180] Between hours 49 and 55, the system experienced a brief period of low wind power output. During this phase, the energy storage state of charge continued to decline, triggering the hydrogen production shutdown threshold, and the hydrogen production unit was shut down. However, the ammonia synthesis unit continued to operate at minimum load and was not shut down. This demonstrates that this control strategy can utilize the buffering effect of energy storage to maintain the continuous operation of ammonia synthesis during short-term fluctuations in wind power output, avoiding the impact of frequent start-ups and shutdowns on the chemical process.

[0181] From hour 65 to hour 84, the system experienced a prolonged period of low wind power output, with wind power essentially at zero. The energy storage state of charge continuously decreased, reaching a preset second low charge threshold of 30%. To prevent excessive discharge of the energy storage leading to system power failure, the control strategy shut down the ammonia synthesis unit to reduce system energy consumption, thereby assisting the system in navigating this low-output phase. This demonstrates that the control strategy proposed in this disclosure can effectively address the intermittency of wind power, automatically planning the start-up and shutdown timing of the ammonia synthesis unit based on the remaining energy storage capacity. It is foreseeable that by increasing the system's energy storage capacity configuration, the system can cope with even longer periods of low wind power output.

[0182] Around the 71st hour, wind power output briefly recovered. The control strategy prioritized utilizing wind power to raise the energy storage's state of charge from 30% to approximately 80%. As the state of charge returned to the normal threshold, the hydrogen production unit restarted. However, wind power output quickly dropped to near zero again, and the hydrogen production unit shut down again after a brief period of operation, until wind power output finally recovered after the 85th hour. Subsequently, ammonia synthesis entered the startup process, completing startup by the 95th hour.

[0183] The above analysis shows that the control strategy proposed in this disclosure can fully consider the flexibility constraints of hydrogen production and ammonia synthesis at different time scales, and achieve the coordinated control objective of hydrogen tracking electricity and ammonia tracking hydrogen. At the same time, the strategy can give full play to the peak-shaving role of energy storage batteries, effectively avoid frequent shutdowns of ammonia synthesis under frequent fluctuations in wind power output, and enable ammonia synthesis to operate in a relatively stable manner within its acceptable load fluctuation range.

[0184] During the aforementioned time window, wind power output was generally low, resulting in ammonia synthesis primarily operating under low load conditions, with a cumulative operating time of less than 30 hours. In contrast, Figure 7 A schematic diagram of the operating curves during a period of relatively abundant wind power output, provided by an exemplary embodiment of this disclosure, is shown. From hour 485 to hour 565, wind power output is abundant, and ammonia synthesis operates continuously for approximately 80 hours. It can be observed that during this period, the system also employs a hydrogen-following-electricity, ammonia-following-hydrogen operating mode, and is able to effectively maintain the energy storage state of charge and hydrogen storage tank pressure within a small range around a given value. This verifies the adaptability of the proposed control strategy to different typical operating scenarios under off-grid conditions.

[0185] This disclosure addresses the core issue of mismatch between rapid fluctuations in front-end power supply and the stable operation requirements of back-end chemical plants in off-grid renewable energy hydrogen production and ammonia synthesis systems. It proposes a coordinated control method based on a dual closed-loop system of energy storage state of charge (SOC) and hydrogen storage pressure. This method uses SOC to characterize the energy balance on the electricity side and hydrogen storage pressure to characterize the supply and demand balance on the hydrogen side. By constructing a main proportional-integral loop (PIL) for the electricity side and a proportional-integral loop for the hydrogen storage pressure on the hydrogen side, it achieves multi-timescale coordinated control of hydrogen tracking electricity and ammonia tracking hydrogen. Simultaneously, a wind turbine power-limiting auxiliary regulation branch is introduced under high SOC conditions, combined with boundary protection logic for high voltage, low voltage, and low SOC, ensuring system stability under normal operation, surplus output, and constrained operating conditions. The fundamental principle lies in fully leveraging the rapid and continuously adjustable active regulation capability of the electrolyzer, prioritizing its role in absorbing power deviations from the source load, thereby reducing the pressure on the energy storage device from long-term fluctuations. Simultaneously, the hydrogen storage component decouples the dynamics of the electricity side from those of the ammonia synthesis side, achieving stable power supply, stable hydrogen storage, and continuous ammonia production with a relatively small energy storage configuration. By adopting the method disclosed herein, the fluctuation range of energy storage SoC can be effectively reduced, large deviations in hydrogen storage pressure can be suppressed, frequent start-ups and shutdowns of ammonia synthesis units can be reduced, and the wind power absorption rate and green ammonia production can be improved, taking into account safety, economy, and engineering feasibility. This method is not only applicable to offshore wind power off-grid hydrogen production and ammonia synthesis systems, but can also be extended to other wind-solar-hydrogen-chemical coupling scenarios, showing good prospects for industrial application.

[0186] In summary, this disclosure uses the energy storage state of charge (SOC) and hydrogen storage pressure as two parallel core control variables, constructing a first proportional-integral (PI) closed loop and a second PIO closed loop, respectively. Under normal operating conditions, the main PIO loop of the SOC directly corrects the total electrolysis target power and introduces the energy storage charging and discharging power as feedforward compensation to improve the system's response sensitivity to source-load deviations. When the SOC rises to a preset high-charge entry threshold, the fan power limiting auxiliary PIO loop is activated to suppress source-side power injection; when the SOC falls back to the exit threshold, this auxiliary loop exits and gradually restores the fan power limiting. The second PIO closed loop calculates the basic ammonia synthesis load based on the real-time compressed hydrogen flow rate into the tank and superimposes the pressure correction to form the ammonia synthesis target load, achieving fine adjustment of the hydrogen supply and demand balance. This disclosure also uses a high-pressure latching hydrogen production limiting mechanism to dynamically link the electrolysis hydrogen production capacity with the actual downstream ammonia synthesis capacity, avoiding hydrogen storage pressure exceeding limits. Simultaneously, the combination of dual-loop continuous control and a threshold protection state machine achieves a unified approach to flexible adjustment and safe start-up and shutdown. The dual-loop design fully considers the different response rates of the electricity, hydrogen, and ammonia stages, establishing multi-timescale control relationships. This enables "hydrogen tracking electricity" in the hydrogen electrolysis stage and "ammonia tracking hydrogen" in the ammonia synthesis stage. Furthermore, energy storage and hydrogen storage devices act as buffers to achieve dynamic decoupling of the system. In this system, energy storage simultaneously undertakes grid construction, peak shaving, and low-wind-crossing support functions. Its state of charge (SOC) changes are essentially a passive result of accumulated source-load deviations. This disclosure utilizes the active adjustment capability of the electrolyzer to perform feedforward absorption and feedback correction of source-load deviations, thereby minimizing SOC fluctuations and reducing the burden on energy storage.

[0187] The following are device embodiments of the present disclosure. For parts not described in detail in the device embodiments, please refer to the technical details disclosed in the above method embodiments.

[0188] Please refer to Figure 8 This illustration shows a schematic diagram of a coordinated control device for an off-grid hydrogen production and ammonia synthesis system provided in an exemplary embodiment of this disclosure. The device can be implemented, in whole or in part, through software, hardware, or a combination of both, as a computing device. The device includes: a data acquisition module 810, a first closed-loop regulation module 820, an auxiliary regulation module 830, a second closed-loop regulation module 840, and an output module 850.

[0189] The data acquisition module 810 is used to collect system operation data of the off-grid hydrogen production and ammonia synthesis system. The system operation data includes the energy storage state of charge, the limited power of the blower, and the pressure of the hydrogen storage tank.

[0190] The first closed-loop regulation module 820 is used to perform first closed-loop regulation based on the deviation between the energy storage state of charge and the preset target state of charge to obtain the total electrolysis target power.

[0191] The auxiliary adjustment module 830 is used to assist in adjusting the power limit of the wind turbine according to the energy storage state of charge.

[0192] The second closed-loop regulation module 840 is used to perform second closed-loop regulation based on the deviation between the hydrogen storage tank pressure and the preset target pressure to obtain the target load for ammonia synthesis.

[0193] The output module 850 is used to output fan power limit command, electrolysis power command and ammonia load command based on the total electrolysis target power, the adjusted fan power limit and the ammonia synthesis target load.

[0194] In one possible implementation, the system operating data also includes the energy storage charging and discharging power and the actual power of the electro-hydrogen production unit. The first closed-loop regulation module 820 is also used for:

[0195] The deviation between the energy storage state of charge and the target state of charge is processed by dead zone and then input into the first proportional-integral controller.

[0196] Based on the output of the first proportional-integral controller and the energy storage charging and discharging power, an electrolysis power correction amount is generated;

[0197] The total electrolysis target power is generated based on the actual power of the electro-hydrogen production unit and the correction amount of the electrolysis power.

[0198] In another possible implementation, the auxiliary adjustment module 830 is also used for:

[0199] When the energy storage state of charge is higher than the preset high charge threshold, the auxiliary proportional-integral controller is activated. The auxiliary proportional-integral controller takes the deviation between the energy storage state of charge and the target state of charge as input, and gradually reduces the wind turbine power limit based on the output of the auxiliary proportional-integral controller.

[0200] When the energy storage state of charge is lower than the preset high charge exit threshold, the auxiliary proportional-integral controller is deactivated, and the wind turbine power limit is gradually restored to the preset maximum power limit setting value.

[0201] In another possible implementation, the system operating data also includes the actual hydrogen compression inlet flow rate, and the second closed-loop control module 840 is also used for:

[0202] The deviation between the hydrogen storage tank pressure and the target pressure is processed through a dead zone and then input into the second proportional-integral controller.

[0203] The basic ammonia synthesis load is calculated based on the actual hydrogen compression inlet flow rate.

[0204] The target ammonia load is generated based on the output of the second proportional-integral controller and the basic ammonia synthesis load.

[0205] In another possible implementation, the output module 850 is also used for:

[0206] Based on the energy storage state of charge, hydrogen storage tank pressure, and total electrolysis target power, the revised upper limit of electrolysis power and protective flags are determined. The protective flags are used to indicate whether to perform protective shutdown or start-up operations on the electro-hydrogen production unit and / or the ammonia synthesis unit in the off-grid hydrogen production and ammonia synthesis system.

[0207] Based on the total electrolysis target power, the adjusted fan power limit, the ammonia synthesis target load, the corrected upper limit of electrolysis power, and the protective flags, output the fan power limit command, the electrolysis power command, and the ammonia synthesis load command.

[0208] In another possible implementation, the system operating data also includes the actual load of the ammonia synthesis unit, and the output module 850 is also used for:

[0209] When the pressure of the hydrogen storage tank exceeds the preset high pressure threshold, the hydrogen production restriction state is locked, and the total electrolysis target power is capped according to the actual load of the ammonia synthesis unit. When the pressure of the hydrogen storage tank reaches the high pressure threshold and the ammonia synthesis unit is not running, the hydrogen production unit is shut down. When the pressure of the hydrogen storage tank falls back to below the preset release threshold, the hydrogen production restriction state is lifted.

[0210] The ammonia synthesis unit is shut down when the pressure of the hydrogen storage tank is lower than the preset low pressure threshold. The electro-hydrogen production unit is shut down when the energy storage state of charge is lower than the preset first low charge threshold but higher than the preset second low charge threshold. The electro-hydrogen production unit and the ammonia synthesis unit are shut down when the energy storage state of charge is lower than the second low charge threshold. The ammonia synthesis unit is allowed to restart only when the energy storage state of charge is higher than the preset ammonia synthesis start-up charge threshold and the hydrogen storage tank pressure is higher than the preset restart pressure threshold. The second low charge threshold is lower than the first low charge threshold.

[0211] It should be noted that the above embodiments only illustrate the division of the above functional modules when implementing the device. In actual applications, the above functions can be assigned to different functional modules according to actual needs, that is, the content structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0212] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0213] In some embodiments, the functions or modules of the apparatus provided in this disclosure can be used to perform the methods described in the above method embodiments. The specific implementation can be referred to the description of the above method embodiments, and for the sake of brevity, it will not be repeated here.

[0214] According to another aspect of this disclosure, a coordinated control device for an off-grid hydrogen production and ammonia synthesis system is provided, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above-described method.

[0215] According to another aspect of this disclosure, a non-volatile computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the above-described method.

[0216] According to another aspect of this disclosure, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of the above-described method.

[0217] Figure 9 This is a block diagram illustrating an apparatus 1900 according to an exemplary embodiment. The apparatus 1900 is used to perform the aforementioned coordination control method. (Refer to...) Figure 9 The apparatus 1900 includes a processing component 1922, which further includes one or more processors, and memory resources represented by memory 1932 for storing instructions, such as application programs, that can be executed by the processing component 1922. The application programs stored in memory 1932 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 1922 is configured to execute instructions to perform the methods described above.

[0218] Device 1900 may also include a power supply component 1926 configured to perform power management of device 1900, a wired or wireless network interface 1950 configured to connect device 1900 to a network, and an input / output interface 1958 (I / O interface). Device 1900 can operate on an operating system stored in memory 1932, such as Windows Server™, MacOS X™, Unix™, Linux™, FreeBSD™, or similar.

[0219] In an exemplary embodiment, a non-volatile computer-readable storage medium is also provided, such as a memory 1932 including computer program instructions that can be executed by a processing component 1922 of the device 1900 to perform the above-described method.

[0220] Computer-readable storage media can be tangible devices capable of holding and storing programs / instructions used by instruction execution devices. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0221] The computer program (or computer-readable program instructions) described herein can be downloaded from a computer-readable storage medium to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage medium in the respective computing / processing device.

[0222] The computer program (or computer program instructions) used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing state information from the computer-readable program instructions to implement various aspects of this disclosure.

[0223] Various aspects of this disclosure are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0224] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart and / or block diagram.

[0225] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0226] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0227] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A coordinated control method for an off-grid hydrogen production and ammonia synthesis system, characterized in that, The method includes: Collect system operation data of the off-grid hydrogen production and ammonia synthesis system, including energy storage state of charge, fan power limit, and hydrogen storage tank pressure; Based on the deviation between the energy storage state of charge and the preset target state of charge, a first closed-loop adjustment is performed to obtain the total electrolysis target power. The power limit of the wind turbine is adjusted auxiliaryly based on the energy storage state of charge. Based on the deviation between the hydrogen storage tank pressure and the preset target pressure, a second closed-loop adjustment is performed to obtain the target load for ammonia synthesis. Based on the total electrolysis target power, the adjusted fan power limit, and the ammonia synthesis target load, output the fan power limit command, the electrolysis power command, and the ammonia synthesis load command.

2. The method according to claim 1, characterized in that, The system operating data also includes the energy storage charging and discharging power and the actual power of the electro-hydrogen production unit. The process of obtaining the total electrolysis target power by performing a first closed-loop adjustment based on the deviation between the energy storage state of charge and the preset target state of charge includes: The deviation between the energy storage state of charge and the target state of charge is processed by dead zone and then input into the first proportional-integral controller. Based on the output of the first proportional-integral controller and the energy storage charging and discharging power, an electrolysis power correction amount is generated; The total electrolysis target power is generated based on the actual power of the electro-hydrogen production unit and the electrolysis power correction amount.

3. The method according to claim 1 or 2, characterized in that, The auxiliary adjustment of the wind turbine power limit based on the energy storage state of charge includes: When the energy storage state of charge is higher than the preset high charge threshold, the auxiliary proportional-integral controller is activated. The auxiliary proportional-integral controller takes the deviation between the energy storage state of charge and the target state of charge as input, and gradually reduces the wind turbine power limit according to the output of the auxiliary proportional-integral controller. When the energy storage state of charge is lower than the preset high charge exit threshold, the auxiliary proportional-integral controller is deactivated, and the wind turbine power limit is gradually restored to the preset maximum power limit setting value.

4. The method according to any one of claims 1 to 3, characterized in that, The system operating data also includes the actual hydrogen compression inlet flow rate. The second closed-loop adjustment, based on the deviation between the hydrogen storage tank pressure and the preset target pressure, to obtain the target ammonia synthesis load includes: The deviation between the hydrogen storage tank pressure and the target pressure is processed by dead zone and then input into the second proportional-integral controller. The basic ammonia synthesis load is calculated based on the actual hydrogen compression inlet flow rate. The target ammonia load is generated based on the output of the second proportional-integral controller and the basic ammonia synthesis load.

5. The method according to any one of claims 1 to 4, characterized in that, The step of outputting fan power limiting commands, electrolysis power commands, and ammonia load commands based on the total electrolysis target power, the adjusted fan power limit, and the ammonia synthesis target load includes: Based on the energy storage state of charge and the hydrogen storage tank pressure, adjust the upper limit of the total electrolysis target power and / or set a protective flag, which is used to indicate whether to perform protective operations on the electro-hydrogen production unit and / or the ammonia synthesis unit in the off-grid hydrogen production and ammonia synthesis system. Based on the total electrolysis target power, the adjusted fan power limit, the ammonia synthesis target load, the upper limit of the total electrolysis target power, and the protective flag, the fan power limit command, the electrolysis power command, and the ammonia synthesis load command are output.

6. The method according to claim 5, characterized in that, The system operation data also includes the actual load of the ammonia synthesis unit. The protective indicators include a hydrogen production limitation indicator, a low-pressure ammonia shutdown indicator, and a low energy storage charge state power outage indicator. Adjusting the upper limit of the total electrolysis target power and / or setting protective indicators based on the energy storage charge state and the hydrogen storage tank pressure includes: When the pressure of the hydrogen storage tank exceeds the preset high pressure threshold, the hydrogen production restriction flag is set to lock the hydrogen production restriction state, and the upper limit of the total electrolysis target power is adjusted according to the actual load of the ammonia synthesis unit. When the pressure of the hydrogen storage tank reaches the high pressure threshold and the ammonia synthesis unit is not running, the low energy storage charge state power outage flag is set to shut down the electro-hydrogen production unit. When the pressure of the hydrogen storage tank falls back to below the preset release threshold, the hydrogen production restriction flag is cleared to release the hydrogen production restriction state. When the pressure of the hydrogen storage tank is lower than a preset low-pressure threshold, the low-pressure ammonia shutdown flag is set to shut down the ammonia synthesis unit. When the energy storage charge state is lower than a preset first low-charge threshold but higher than a preset second low-charge threshold, the low energy storage charge state power-off flag is set to shut down the electro-hydrogen production unit. When the energy storage charge state is lower than the second low-charge threshold, both the low energy storage charge state power-off flag and the low-pressure ammonia shutdown flag are set to shut down the electro-hydrogen production unit and the ammonia synthesis unit. The low-pressure ammonia shutdown flag is cleared to allow the ammonia synthesis unit to restart only when the energy storage charge state is higher than a preset ammonia synthesis start-up charge threshold and the hydrogen storage tank pressure is higher than a preset restart pressure threshold. The second low-charge threshold is less than the first low-charge threshold.

7. A coordinated control device for an off-grid hydrogen production and ammonia synthesis system, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 6.

8. An off-grid hydrogen production and ammonia synthesis system, comprising a wind power unit, an energy storage unit, an electro-hydrogen production unit, a hydrogen compression and storage unit, a nitrogen production unit, an ammonia synthesis unit, and a controller, characterized in that, The controller is configured to perform the method according to any one of claims 1 to 6.

9. A non-volatile computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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