Heat energy management method and device of off-grid photovoltaic hydrogen production system and medium

Abstract

The invention relates to the technical field of hydrogen production, and particularly discloses a heat energy management method and device of an off-grid photovoltaic hydrogen production system and a medium. If the current working period is the night working period, determining the hydrogen reserve required by the phosphoric acid fuel cell; executing corresponding heat energy management operation based on the hydrogen reserve; if the current working period is the daytime working period, the working mode of the electrolytic cell is determined; under the condition that the working mode is a starting mode, the phosphoric acid fuel cell is controlled to execute quick starting operation for the electrolytic cell; and under the condition that the working mode is a normal operation mode, controlling the phosphoric acid fuel cell to execute low-power-consumption operation. The phosphoric acid fuel cell is used as a core energy supply part of combined heat and power, accurate regulation and control of heat energy are achieved by distinguishing day and night working time periods and adapting to the working mode of the electrolytic cell, and the problems that heat preservation is difficult to maintain at night, and the electrolytic cell is started slowly in daytime are solved.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology, specifically to a thermal energy management method, device, and medium for an off-grid photovoltaic hydrogen production system. Background Technology

[0002] Driven by the global energy transition and the "dual carbon" goal, green hydrogen, as a clean and efficient secondary energy carrier, has seen its large-scale production technology become a core focus of industry research. Among these technologies, off-grid photovoltaic hydrogen production systems have demonstrated significant application value in remote areas rich in wind and solar resources due to their ability to achieve local consumption of photovoltaic power and eliminate grid dependence. However, the operating efficiency and stability of this system have long been constrained by the intermittency and diurnal fluctuations of photovoltaic energy, as well as the imbalance in thermal energy utilization, becoming a key bottleneck for technology implementation.

[0003] The diurnal characteristics of photovoltaic energy lead to significant time-of-day differences in system operation: during the day, photovoltaic power drives electrolyzers to produce hydrogen, but the electrolyzers need to rapidly rise from a low temperature to their optimal operating temperature to achieve efficient hydrogen production; at night, photovoltaic power is interrupted, and the electrolyzers and related components need to be maintained at specific insulation temperatures to prevent performance degradation, while the hydrogen production workshop needs to ensure a basic operating environment. Current technologies have significant shortcomings in thermal management strategies to address these time-of-day differences: most systems lack precise time-of-day control logic, often relying on additional energy storage devices or auxiliary energy sources to maintain temperature at night, leading to increased energy consumption; during the day, the electrolyzers rely solely on photovoltaic power for heating, which is greatly affected by fluctuations in sunlight intensity, resulting in long start-up times and low efficiency. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems in the prior art, the present invention provides a thermal energy management method, device and medium for an off-grid photovoltaic hydrogen production system.

[0005] On one hand, the present invention provides a thermal energy management method for an off-grid photovoltaic hydrogen production system, the off-grid photovoltaic hydrogen production system including a phosphoric acid fuel cell, the method comprising: determining the current working period;

[0006] If the current working period is nighttime: determine the required hydrogen reserve for the phosphoric acid fuel cell;

[0007] Based on the hydrogen reserve, perform corresponding thermal energy management operations; if the current working period is daytime: determine the working mode of the electrolyzer; if the working mode is start-up mode, control the phosphoric acid fuel cell to perform a rapid start-up operation for the electrolyzer; if the working mode is normal operation mode, control the phosphoric acid fuel cell to perform a low-power operation operation.

[0008] Preferably, determining the required hydrogen reserve for the phosphoric acid fuel cell includes:

[0009] Determine the heat required for insulation of the off-grid photovoltaic hydrogen production system at night; determine the operating power required for the off-grid photovoltaic hydrogen production system to operate at night; and determine the required hydrogen reserve for the phosphoric acid fuel cell based on the operating power and the heat required for insulation.

[0010] Preferably, determining the required heat preservation heat for the off-grid photovoltaic hydrogen production system at night includes: obtaining the predicted nighttime temperature; determining the target heat preservation temperature for the off-grid photovoltaic hydrogen production system; identifying temperature instability factors and determining a safety margin based on the temperature instability factors; and determining the required heat preservation heat for nighttime based on the predicted nighttime temperature, the target heat preservation temperature, and the safety margin, wherein the heat preservation heat is characterized as follows: Where U represents the building's overall heat transfer coefficient, and A represents the building envelope area. Characterized by the indoor ambient temperature that needs to be maintained. Characterized by nighttime predicted temperature, Characterized as the target insulation temperature, Characterized by nighttime duration, The total mass of the alkaline solution in the electrolytic cell is represented by this. Characterized by the specific heat capacity of the alkaline solution. This is represented as a safety margin.

[0011] Preferably, determining the operating power required for the off-grid photovoltaic hydrogen production system to operate at night includes: determining the first nighttime operating power of the alkaline circulation pump in the off-grid photovoltaic hydrogen production system; determining the nighttime auxiliary equipment of the off-grid photovoltaic hydrogen production system; obtaining the second nighttime operating power of the nighttime auxiliary equipment; determining the total operating power based on the first nighttime operating power and the second nighttime operating power; and determining the operating power required for nighttime operation based on the total operating power.

[0012] Preferably, determining the required hydrogen reserve for the phosphoric acid fuel cell based on the operating electrical energy and the heat exchange heat includes: determining the thermal efficiency and electrical efficiency of the phosphoric acid fuel cell; determining the heat exchange efficiency of the off-grid photovoltaic hydrogen production system; determining the heat generation requirement of the phosphoric acid fuel cell based on the heat exchange heat, the thermal efficiency, and the heat exchange efficiency; determining the power generation requirement of the phosphoric acid fuel cell based on the operating electrical energy and the electrical efficiency; determining the input energy requirement of the phosphoric acid fuel cell based on the heat generation requirement and the power generation requirement; and determining the required hydrogen reserve for the phosphoric acid fuel cell based on the input energy requirement.

[0013] Preferably, determining the required hydrogen reserve for the phosphoric acid fuel cell based on the input energy demand includes: obtaining the higher calorific value of hydrogen, determining the hydrogen density output by the off-grid photovoltaic hydrogen production system; and determining the hydrogen reserve based on the input energy demand, the higher calorific value of hydrogen, and the hydrogen density, wherein the hydrogen reserve is characterized as follows: ,in, Characterized by the high calorific value of hydrogen, Characterized by hydrogen density, It is characterized as input energy demand.

[0014] Preferably, the off-grid photovoltaic hydrogen production system further includes a deoxygenation heater and a regeneration heater. Controlling the phosphoric acid fuel cell to perform a rapid start-up operation for the electrolyzer includes: determining whether the off-grid photovoltaic hydrogen production system contains residual hydrogen; if so, controlling the phosphoric acid fuel cell to perform heating and discharging operations based on the residual hydrogen; heating the alkaline solution to a target heating temperature, which is higher than a target holding temperature, based on the heating operation; and inputting electrical energy to the deoxygenation heater and the regeneration heater based on the discharging operation to perform the corresponding heating operation.

[0015] Preferably, the method further includes: predicting the total hydrogen production during the most recent daytime working period when the current working period is a daytime working period; determining whether the total hydrogen production is greater than or equal to the hydrogen reserve; if so, determining the hydrogen surplus based on the total hydrogen production and the hydrogen reserve, and performing a hydrogen sale operation based on the hydrogen surplus; otherwise, generating corresponding alarm information.

[0016] On the other hand, the present invention provides a thermal energy management device for an off-grid photovoltaic hydrogen production system, the off-grid photovoltaic hydrogen production system including a phosphoric acid fuel cell, the device including a time period determination module, a night management module, and a day management module; the time period determination module is used to determine the current working time period; the night management module is electrically connected to the time period determination module, and is used to determine the amount of hydrogen reserve required by the phosphoric acid fuel cell when the current working time period is a night working time period, and generate a thermal energy management operation command based on the hydrogen reserve amount; the day management module is electrically connected to the time period determination module, and is used to determine the working mode of the electrolyzer when the current working time period is a day working time period, generate a fast start command to control the phosphoric acid fuel cell to perform a fast start operation for the electrolyzer when the working mode is a start-up mode, and generate a low power consumption command to control the phosphoric acid fuel cell to perform a low power consumption operation when the working mode is a normal operating mode.

[0017] In addition, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the thermal energy management method of the off-grid photovoltaic hydrogen production system described in the embodiments of the present invention.

[0018] The present invention has at least the following technical effects through the technical solution provided by the present invention:

[0019] This invention uses a phosphoric acid fuel cell as the core power supply component for combined heat and power (CHP) capabilities. By differentiating between day and night working periods and adapting to the working mode of the electrolyzer, it achieves precise control of power supply throughout the day and night. This solves the problems of difficulty in maintaining heat preservation at night when there is no photovoltaic power and slow start-up of the electrolyzer during the day in the existing technology, ensuring stable and efficient operation of the system.

[0020] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0022] Figure 1 This is a schematic flowchart of a thermal energy management method for an off-grid photovoltaic hydrogen production system provided in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the thermal energy management device of an off-grid photovoltaic hydrogen production system provided in an embodiment of the present invention. Detailed Implementation

[0024] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0025] In this invention, the terms "system" and "network" are used interchangeably. "Multiple" refers to two or more; therefore, in this invention, "multiple" can also be understood as "at least two." "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this invention, terms such as "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or order.

[0026] The diurnal characteristics of photovoltaic energy lead to significant time-of-day differences in system operation: during the day, photovoltaic power drives electrolyzers to produce hydrogen, but the electrolyzers need to rapidly rise from a low temperature to their optimal operating temperature to achieve efficient hydrogen production; at night, photovoltaic power is interrupted, and the electrolyzers and related components need to be maintained at specific insulation temperatures to prevent performance degradation, while the hydrogen production workshop needs to ensure a basic operating environment. Current technologies have significant shortcomings in thermal management strategies to address these time-of-day differences: most systems lack precise time-of-day control logic, often relying on additional energy storage devices or auxiliary energy sources to maintain temperature at night, leading to increased energy consumption; during the day, the electrolyzers rely solely on photovoltaic power for heating, which is greatly affected by fluctuations in sunlight intensity, resulting in long start-up times and low efficiency.

[0027] For the reasons mentioned above, please refer to Figure 1 This invention provides a thermal energy management method for an off-grid photovoltaic hydrogen production system, the off-grid photovoltaic hydrogen production system including a phosphoric acid fuel cell. The method includes: determining the current working period; if the current working period is a nighttime working period: determining the required hydrogen reserve for the phosphoric acid fuel cell; performing a corresponding thermal energy management operation based on the hydrogen reserve; if the current working period is a daytime working period: determining the operating mode of the electrolyzer; if the operating mode is a start-up mode, controlling the phosphoric acid fuel cell to perform a rapid start-up operation for the electrolyzer; if the operating mode is a normal operating mode, controlling the phosphoric acid fuel cell to perform a low-power operation operation.

[0028] In one possible implementation, the thermal energy management method of this off-grid photovoltaic hydrogen production system uses a phosphoric acid fuel cell as the core power supply component. First, it determines the current working period: real-time light intensity is collected by a light sensor, and combined with a preset light threshold (e.g., light intensity below 50 W / m² for 10 minutes is considered nighttime) or a fixed time interval (e.g., 8:00 PM to 8:00 AM the next day is considered nighttime), it automatically determines whether the current working period is nighttime or daytime. If it is determined to be nighttime, the required hydrogen reserve for the phosphoric acid fuel cell is further determined: the amount of hydrogen reserve sufficient for nighttime power supply is estimated based on experience, and then thermal energy management operations are performed based on this hydrogen reserve. These operations include controlling the hydrogen storage device to supply hydrogen to the phosphoric acid fuel cell and distributing the heat and electricity generated by the phosphoric acid fuel cell from hydrogen consumption. If it is determined to be a daytime working period, first determine the working mode of the electrolyzer: distinguish the mode by monitoring the alkaline solution temperature (below the optimal working temperature is determined to be the start-up mode, and after reaching the standard is determined to be the normal operation mode); in the start-up mode, control the phosphoric acid fuel cell to operate at high power, and prioritize heating the alkaline solution and the key components corresponding to the system start-up; in the normal operation mode, control it to switch to low power operation to maintain the continuous operation of the phosphoric acid fuel cell.

[0029] The off-grid photovoltaic hydrogen production system thermal energy management method provided in this invention uses a phosphoric acid fuel cell as the core power supply component. Through precise control logic based on time periods and modes, it significantly optimizes the system's thermal energy management effect. On the one hand, during nighttime working hours, by determining the required hydrogen reserve for the phosphoric acid fuel cell and executing corresponding thermal energy management operations, it ensures that the thermal energy converted from hydrogen energy can accurately match the system's insulation requirements during nighttime operation. This avoids instability in the electrolyzer's operating environment due to insufficient thermal energy supply, or hydrogen waste due to excessive supply. On the other hand, it ensures that the electrical energy converted from hydrogen energy can accurately match the system's electrical energy requirements during nighttime operation, guaranteeing the stable operation of key components such as the alkali circulation pump and nighttime auxiliary equipment, without relying on the power grid. On the other hand, during daytime working hours, by first determining the working mode of the electrolyzer and then specifically controlling the operating status of the phosphoric acid fuel cell, a rapid start-up operation is performed in the start-up mode. This utilizes the efficient thermal energy output of the phosphoric acid fuel cell to accelerate the rise of the electrolyte in the electrolyzer from the overnight insulation temperature to the optimal operating temperature, shortening the system start-up time and avoiding the start-up delay caused by relying solely on photovoltaic power heating. This allows the phosphoric acid fuel cell to maintain continuous operation, fully adapting to the long start-up time of the phosphoric acid fuel cell, fundamentally avoiding the equipment lifespan degradation caused by frequent start-ups and shutdowns, while saving high restart energy consumption and restart time, always maintaining the equipment's rapid response capability, and providing reliable assurance for subsequent operating condition adjustments.

[0030] During the nighttime operation of off-grid photovoltaic hydrogen production systems, the system needs to simultaneously maintain the insulation requirements of the electrolyzer and hydrogen production workshop, as well as the power needs of the equipment operating at night. Phosphoric acid fuel cells possess the core characteristic of simultaneous power and heat supply, capable of consuming hydrogen while simultaneously outputting heat and electricity, making them a key component for meeting the combined energy supply needs at night. However, existing methods for determining the required hydrogen reserves for phosphoric acid fuel cells fail to fully utilize their combined heat and power (CHP) advantages, often considering only insulation requirements. This leads to a significant discrepancy between the required hydrogen reserves and actual demand: calculating hydrogen reserves solely based on insulation requirements can cause insufficient power supply, resulting in the shutdown of nighttime operating equipment (such as alkali circulation pumps and monitoring instruments), disrupting the system's basic operation. Therefore, a method for determining hydrogen reserves that combines insulation and power requirements is urgently needed to fully leverage the CHP characteristics of phosphoric acid fuel cells and ensure that nighttime energy supply meets both insulation and electricity needs.

[0031] In this embodiment of the invention, determining the required hydrogen reserve for the phosphoric acid fuel cell includes: determining the heat required for insulation of the off-grid photovoltaic hydrogen production system at night; determining the operating power required for the off-grid photovoltaic hydrogen production system to operate at night; and determining the required hydrogen reserve for the phosphoric acid fuel cell based on the operating power and the heat required for insulation.

[0032] In one possible implementation, the specific operation process is as follows: First, integrate historical meteorological data, real-time environmental monitoring information (such as current ambient temperature and humidity), and future weather forecasts, and use a preset temperature prediction model to predict the ambient temperature hourly at night, generating a complete nighttime temperature change curve to provide basic data for subsequent accurate calculation of heat preservation. Next, based on the predicted ambient temperature, combined with the target heat preservation temperature of the electrolyzer alkaline solution, the ambient temperature requirements of the hydrogen production workshop, and parameters such as the system's heat dissipation coefficient, estimate the heat preservation required for the off-grid photovoltaic hydrogen production system to operate at night, and determine the total thermal energy output of the phosphoric acid fuel cell. Subsequently, statistically analyze the rated power and actual operating power of equipment that needs to operate continuously at night (such as alkaline solution circulation pumps, hydrogen concentration detectors, control cabinets, etc.), and combine this with the duration of the nighttime working period to calculate the operating power required for the system's nighttime operation, and determine the total electrical energy output of the phosphoric acid fuel cell. Finally, based on the hydrogen energy consumption corresponding to the heat preservation and the hydrogen energy consumption corresponding to the operating power, and superimposed on the thermoelectric conversion efficiency loss of the phosphoric acid fuel cell, comprehensively determine the final hydrogen reserve to ensure that the reserve can fully cover the dual needs of heat and electricity at night.

[0033] This invention integrates the heat demand for insulation with the power demand for operation, fully adapting to the combined heat and power characteristics of phosphoric acid fuel cells. It effectively corrects the shortcomings of the crude estimation of hydrogen reserves in existing methods, avoiding the problems of insufficient power and equipment shutdown caused by considering only the insulation demand. It significantly improves the accuracy and reliability of nighttime power supply, while maximizing the energy utilization value of phosphoric acid fuel cells, providing key support for the stable operation of off-grid photovoltaic hydrogen production systems at night.

[0034] In calculating the nighttime insulation heat of off-grid photovoltaic hydrogen production systems, existing methods can initially ensure that the hydrogen reserve is compatible with the insulation requirements and reduce failures caused by insufficient temperature. However, there are still three key shortcomings: First, the calculation is based solely on the predicted ambient temperature and relies on empirical values ​​for estimation, completely ignoring the structural information of the hydrogen production workshop. The heat transfer coefficient of the workshop's enclosure structure directly determines the rate of heat loss, and the area of ​​the enclosure structure is related to the overall heat dissipation scale. Ignoring these parameters will lead to a disconnect between the heat calculation and the actual building insulation characteristics, failing to accurately reflect the heat consumption patterns of the workshop. Second, the differences in insulation requirements between the hydrogen production workshop and the electrolyzer are not distinguished, and both are treated with a uniform standard. The calculations are flawed. Firstly, the workshop only needs to maintain a basic ambient temperature and has a high tolerance for temperature fluctuations. Secondly, the electrolyzer requires the electrolyte to be stabilized within a specific range (temperature deviations can alter the properties of the alkali solution and reduce electrode activity). A uniform estimation can lead to a contradiction: either excessive insulation in the workshop wastes hydrogen energy, or insufficient insulation in the electrolyzer causes malfunctions. Thirdly, the calculations do not consider nighttime temperature fluctuations and unforeseen events, such as sudden drops in temperature in the early morning increasing heat consumption and strong winds exacerbating heat dissipation in the workshop. Existing methods lack safety mechanisms to address these risks, resulting in calculated insulation heat that fails to meet requirements in extreme scenarios, potentially leading to serious problems such as runaway electrolyte temperature in the electrolyzer and changes in the physical properties of the alkali solution. Therefore, there is an urgent need to develop a method for determining insulation heat that considers building structural parameters, individual insulation requirements, and risk mitigation, fundamentally improving the accuracy and reliability of the calculations.

[0035] In one possible implementation, firstly, key basic parameters are obtained, including the overall building heat transfer coefficient and total area of ​​the building envelope of the hydrogen production workshop, as well as the total mass and specific heat capacity of the electrolyte in the electrolyzer. Simultaneously, the preset indoor ambient temperature to be maintained in the hydrogen production workshop and the target insulation temperature to be maintained in the electrolyzer are clearly defined, laying the foundation for subsequent object-specific calculations. Next, the basic insulation heat of the hydrogen production workshop is calculated. Combining the predicted average nighttime ambient temperature and nighttime duration, building structural parameters, temperature differences, and the time dimension, the heat required to maintain the workshop temperature to the target ambient temperature is derived. This process fully considers the impact of the workshop structure on heat loss, ensuring that the calculation results match the actual building insulation characteristics. Then, the basic insulation heat of the electrolyte is calculated. Since the target insulation temperature of the electrolyte is higher than the indoor ambient temperature to be maintained in the workshop, the temperature difference between the two is used as the core. Combined with the mass and specific heat capacity of the electrolyte, the heat balance is considered to derive the additional heat required to maintain the electrolyte temperature, accurately meeting the specific insulation requirements of the electrolyte and avoiding confusion with the overall workshop insulation requirements. Finally, by analyzing historical nighttime ambient temperature fluctuation data and future weather warnings, if sudden events such as a sudden drop in temperature or strong winds are predicted, a safety margin coefficient is automatically introduced. The sum of the basic insulation heat of the workshop and the electrolytic cell is multiplied by this coefficient to obtain the final nighttime insulation heat, ensuring that the insulation needs can still be fully covered even in the event of a sudden event.

[0036] Specifically, the heat preservation capacity is characterized as follows:

[0037]

[0038] Where U represents the building's overall heat transfer coefficient, and A represents the building envelope area. Characterized by the indoor ambient temperature that needs to be maintained. Characterized by nighttime predicted temperature, Characterized as the target insulation temperature, Characterized by nighttime duration, The total mass of the alkaline solution in the electrolytic cell is represented by this. Characterized by the specific heat capacity of the alkaline solution. This is represented as a safety margin.

[0039] This invention incorporates the building structure parameters of the hydrogen production workshop, eliminating reliance on empirical values ​​for workshop insulation heat calculation. Instead, it deeply integrates with actual building characteristics, avoiding heat estimation deviations caused by structural differences. This ensures the workshop maintains a stable basic operating environment and reduces equipment failures due to abnormal ambient temperatures. The insulation heat calculation is tailored to both the workshop and the electrolyte, precisely matching their different temperature control requirements: first, ensuring sufficient insulation heat for the electrolyte to maintain its temperature at the target insulation temperature significantly shortens daytime system restart time, fundamentally reducing risks such as alkali leakage and hydrogen-oxygen gas crosstalk caused by electrolyte temperature fluctuations, and extending the electrolyzer's lifespan; then, distributing the remaining heat to workshop insulation, meeting the workshop's basic temperature requirements while avoiding energy waste, achieving synergistic optimization of insulation needs and energy-saving goals. The introduction of a safety margin coefficient enables the system to cope with nighttime environmental fluctuations and emergencies. Even in extreme scenarios, the insulation heat can meet actual needs, significantly improving the system's adaptability in cold regions with large diurnal temperature variations.

[0040] Furthermore, when calculating the operating power required for nighttime operation, focusing only on the power of core equipment such as the alkali circulation pump while ignoring the power consumption of auxiliary equipment such as the hydrogen detector and control cabinet cooling fan will result in an underestimation of the total power consumption. Therefore, there is an urgent need for a method to determine the nighttime operating power consumption of individual equipment to ensure that the power consumption calculation is comprehensive, accurate, and meets the actual operating needs of the equipment at night.

[0041] In this embodiment of the invention, determining the operating power required for the off-grid photovoltaic hydrogen production system to operate at night includes: determining the first nighttime operating power of the alkaline circulation pump in the off-grid photovoltaic hydrogen production system; determining the nighttime auxiliary equipment of the off-grid photovoltaic hydrogen production system; obtaining the second nighttime operating power of the nighttime auxiliary equipment; determining the total operating power based on the first nighttime operating power and the second nighttime operating power; and determining the operating power required for nighttime operation based on the total operating power.

[0042] In one possible implementation, firstly, the nighttime equipment is divided into alkaline solution circulation pumps and nighttime auxiliary equipment. For the alkaline solution circulation pumps, the operating frequency-power characteristic curve of the pumps is obtained, and the operating power of the pumps, i.e., the first operating power, is determined based on the nighttime insulation requirements. For the nighttime auxiliary equipment, a classification metering method is used to divide them into continuously operating equipment (such as hydrogen detectors and control cabinet cooling fans, which need to run continuously) and intermittently operating equipment. The average operating power of the continuously operating equipment is calculated using historical operating data, and the number of starts and the duration of each run of the intermittent equipment are predicted using a time-series control algorithm. The combined power of these components is then used to obtain the operating power of the nighttime auxiliary equipment, i.e., the second nighttime operating power. Finally, the first nighttime operating power and the second nighttime operating power are added together to obtain the total operating power. Based on the total operating power and the duration of the nighttime operation, the required operating energy for nighttime operation is determined.

[0043] Of course, in practical applications, a safety margin factor also needs to be introduced to accommodate fluctuations in operating power.

[0044] Specifically, the operating electrical energy is characterized as follows:

[0045]

[0046] in, This indicates the total operating power of the electrolyte circulation pump and auxiliary equipment at night. This represents the safety margin coefficient.

[0047] This invention, by separately determining and summarizing the operating power of the electrolyte circulation pump and nighttime auxiliary equipment, comprehensively covers the main sources of power consumption in the nighttime system, avoiding incomplete power consumption calculations due to omitted equipment and ensuring the comprehensiveness of the total operating power calculation. Furthermore, by introducing a safety margin coefficient, it effectively addresses additional power consumption caused by equipment power fluctuations or weather factors (sudden drops in temperature, late sunrise), providing ample assurance for nighttime power supply.

[0048] In actual thermal management operations, efficiency losses are unavoidable in both the phosphoric acid fuel cell and the heat exchange system. Directly converting insulation heat and operating electrical energy into hydrogen energy would result in a calculated hydrogen reserve quantity that doesn't match actual needs. For example, if the thermal efficiency of the phosphoric acid fuel cell falls short of expectations, the actual output heat energy will be lower than the calculated value; inefficient heat exchange systems will further cause heat loss. Simultaneously, existing methods lack a clear comparison logic between heat generation and power generation needs, making it difficult to determine the minimum hydrogen quantity required to meet both demands, easily leading to either excessive or insufficient reserves. Therefore, it is essential to optimize the hydrogen reserve determination method to address these shortcomings, combining efficiency parameters with demand comparisons to ensure reliable results.

[0049] In this embodiment of the invention, determining the required hydrogen reserve for the phosphoric acid fuel cell based on the operating electrical energy and the heat exchange heat includes: determining the thermal efficiency and electrical efficiency of the phosphoric acid fuel cell; determining the heat exchange efficiency of the off-grid photovoltaic hydrogen production system; determining the heat generation requirement of the phosphoric acid fuel cell based on the heat exchange heat, the thermal efficiency, and the heat exchange efficiency; determining the power generation requirement of the phosphoric acid fuel cell based on the operating electrical energy and the electrical efficiency; determining the input energy requirement of the phosphoric acid fuel cell based on the heat generation requirement and the power generation requirement; and determining the required hydrogen reserve for the phosphoric acid fuel cell based on the input energy requirement.

[0050] In one possible implementation, firstly, key efficiency parameters are determined, including the actual thermal efficiency and electrical efficiency of the phosphoric acid fuel cell, and the actual heat exchange efficiency of the heat exchange system. Secondly, the optimized insulation heat is divided by the product of the thermal efficiency and the heat exchange efficiency to obtain the hydrogen energy required to meet the insulation needs, i.e., the heating demand. The operating electrical energy is divided by the electrical efficiency to obtain the hydrogen energy required to meet the electricity demand, i.e., the power generation demand. Finally, the values ​​of the heating demand and the power generation demand are compared, and the maximum value of the two is selected as the input energy demand of the phosphoric acid fuel cell, ensuring that the stored hydrogen energy can simultaneously meet both insulation and electricity needs, avoiding energy shortages caused by a single demand.

[0051] This embodiment ensures that the energy parameter conversion matches the actual system state by introducing actual efficiency parameters, avoiding energy shortages caused by insufficient efficiency; the comparison between heat demand and power generation demand clarifies the minimum amount of hydrogen needed to meet both demands, reducing energy waste.

[0052] Furthermore, the input energy demand needs to be converted into hydrogen volume parameters. Without this conversion, it cannot be directly used for the actual storage operation of hydrogen storage devices, as these devices store and control hydrogen in units of volume, and energy parameters cannot be directly applied to practical operations. Additionally, the existing conversion logic does not consider the actual operating conditions of the hydrogen storage device, calculating volume only based on standard conditions. This leads to a mismatch between the conversion results and the actual hydrogen storage device, potentially resulting in wasted storage space or insufficient storage capacity. Therefore, it is essential to address these shortcomings by supplementing the energy-to-volume conversion method to ensure that the results accurately reflect the actual conditions of the hydrogen storage device.

[0053] In this embodiment of the invention, determining the required hydrogen reserve for the phosphoric acid fuel cell based on the input energy demand includes: obtaining the higher calorific value of hydrogen, determining the hydrogen density output by the off-grid photovoltaic hydrogen production system; and determining the hydrogen reserve based on the input energy demand, the higher calorific value of hydrogen, and the hydrogen density, wherein the hydrogen reserve is characterized as follows: ,in, Characterized by the high calorific value of hydrogen, Characterized by hydrogen density, It is characterized as input energy demand.

[0054] In one possible implementation, firstly, standard hydrogen physical properties are obtained, including the industry-standard hydrogen calorific value and hydrogen density under standard conditions, providing fundamental parameters for the energy-to-mass-to-volume conversion. Secondly, the hydrogen volume under standard conditions is calculated by dividing the input energy requirement by the product of the hydrogen calorific value and the standard density, yielding the hydrogen volume required under standard conditions. Finally, combined with the state-corrected volume of the hydrogen storage device, real-time pressure and temperature data of the device are read, and the ideal gas law is used to correct the standard volume to the actual volume under the current operating conditions. The resulting actual volume is the amount of hydrogen required for the phosphoric acid fuel cell, which can be directly used to control the hydrogen storage device to perform storage operations.

[0055] This invention effectively addresses the shortcomings of unapplicable input energy requirements and neglect of hydrogen storage conditions by constructing an energy-to-volume conversion logic and performing actual state correction. It realizes the conversion of hydrogen storage capacity from abstract energy parameters to specific volume parameters. The use of standard physical property parameters ensures the universality of the conversion logic; while the actual state correction ensures that the volume data conforms to the operating conditions of the hydrogen storage device, avoiding wasted storage space or insufficient storage capacity, and improving the safety and economy of hydrogen storage operations.

[0056] During the daytime working hours, off-grid photovoltaic hydrogen production systems need to switch from nighttime heat preservation mode to hydrogen production operation mode. However, in low-temperature environments such as northern winters, this switch faces significant challenges: after the nighttime working hours, although the alkali solution can maintain a certain temperature, it is far from reaching the optimal operating temperature of the electrolyzer, requiring additional heating to meet hydrogen production needs. Simultaneously, the deoxygenation heater and regeneration heater, as key equipment for hydrogen purification, will directly affect hydrogen purity and production efficiency if they cannot be heated to operating temperature in time. However, existing technologies often rely solely on photovoltaic power for alkali solution heating and equipment power supply during the daytime startup phase. Photovoltaic power is greatly affected by fluctuations in sunlight intensity and has limited heating efficiency, resulting in slow alkali solution heating, delayed equipment preheating, and prolonged system startup time. More importantly, existing solutions do not consider the residual hydrogen that may remain in the system overnight. If this hydrogen is not utilized, it not only wastes energy but also fails to leverage the core advantages of phosphoric acid fuel cell combined heat and power, further extending startup time and reducing hydrogen production efficiency during the startup phase. Therefore, there is an urgent need for a strategy to combine residual hydrogen during daytime working hours and utilize phosphoric acid fuel cells to achieve rapid system startup, ensuring that the alkaline solution, deoxygenation heater, and regeneration heater can reach working status simultaneously and quickly during the startup phase, thus laying the foundation for efficient hydrogen production during the day.

[0057] In one possible implementation, when the phosphoric acid fuel cell needs to perform a rapid start-up operation for the electrolyzer during daytime working hours, the system first determines whether the off-grid photovoltaic hydrogen production system contains residual hydrogen from the previous night. If residual hydrogen is present, it is used as an energy source to control the phosphoric acid fuel cell to simultaneously perform heating and discharging operations: During the heating operation, the high-temperature heat energy generated by the phosphoric acid fuel cell is used to exchange heat with the alkali circulation pipeline through a heat exchange unit, rapidly heating the alkali to the target heating temperature (this temperature is higher than the target insulation temperature at night and matches the optimal hydrogen production temperature requirement of the electrolyzer), ensuring that the alkali can quickly reach the hydrogen production operating conditions; During the discharging operation, the phosphoric acid fuel cell converts hydrogen energy into electrical energy, which is directly input into the deoxygenation heater and regeneration heater, driving the heating elements of both types of equipment to start up, causing their temperatures to rapidly rise to the operating threshold, meeting the temperature requirements for hydrogen purification.

[0058] This embodiment fully activates the cogeneration capability of the phosphoric acid fuel cell by prioritizing the use of residual hydrogen during the daytime startup phase. On one hand, it avoids the waste of residual hydrogen, improving energy efficiency; on the other hand, by directionally heating the alkali solution with heat and precisely supplying electricity to the purification equipment, it achieves simultaneous preheating of the alkali solution and key purification equipment, significantly shortening system startup time and effectively solving the problems of difficult and slow startup during the day in low-temperature environments. Simultaneously, this strategy does not rely on fluctuating photovoltaic power, improving stability during the startup phase and allowing the system to quickly transition to a highly efficient hydrogen production state during the day, balancing startup efficiency and hydrogen production reliability.

[0059] During daytime operating hours, off-grid photovoltaic hydrogen production systems not only need to complete the core hydrogen production operation but also need to consider hydrogen storage and subsequent utilization planning. At night, when there is no photovoltaic power generation, the system relies on the hydrogen stored during the day to maintain operation. Furthermore, if there is excess hydrogen production during the day, proper disposal of the surplus can improve the system's economic efficiency. However, existing technologies have significant shortcomings in hydrogen energy management during daytime operating hours: they lack advance prediction of total hydrogen production and have not established a response strategy matching the storage capacity. Specifically, if the total daytime hydrogen production cannot be predicted in advance, when the actual total production is greater than or equal to the hydrogen storage capacity required at night, the excess hydrogen energy is wasted due to unplanned disposal, resulting in missed economic benefits. When the total production is less than the hydrogen storage capacity, there is no advance warning, which may lead to insufficient power supply at night, causing equipment shutdowns or insulation failures. Therefore, there is an urgent need for a method to predict the total hydrogen production during daytime operating hours and execute corresponding operations based on the relationship between total production and storage capacity, thereby optimizing hydrogen energy management and balancing system power supply security and economic benefits.

[0060] In this embodiment of the invention, the method further includes: predicting the total hydrogen production during the most recent daytime working period when the current working period is a daytime working period; determining whether the total hydrogen production is greater than or equal to the hydrogen reserve; if so, determining the hydrogen surplus based on the total hydrogen production and the hydrogen reserve, and performing a hydrogen sale operation based on the hydrogen surplus; otherwise, generating corresponding alarm information.

[0061] In one possible implementation, when the current working period is determined to be a daytime working period, the total hydrogen production for the most recent daytime working period is first predicted using a preset model. Then, the predicted total hydrogen production is compared with the system's preset nighttime hydrogen reserve: if the total hydrogen production is greater than or equal to the hydrogen reserve, the hydrogen surplus is calculated based on the difference, and hydrogen sales operations are then planned and executed based on this surplus (such as connecting with external hydrogen energy demanders and planning delivery volume according to the surplus), realizing the resource utilization of excess hydrogen energy and improving economic benefits; if the total hydrogen production is less than the hydrogen reserve, corresponding alarm information is immediately generated (such as a pop-up notification on the system control cabinet or a warning signal sent to the operation and maintenance terminal), reminding relevant personnel to take timely countermeasures, such as adjusting the tilt angle of the photovoltaic panels to increase power generation, checking the electrolyzer's operating status to optimize hydrogen production efficiency, or supplementing hydrogen energy through external hydrogen replenishment equipment to ensure energy security during subsequent periods without photovoltaic power generation.

[0062] Specifically, the total hydrogen production during the most recent daytime working period is predicted using the following formula:

[0063]

[0064]

[0065] in, This represents the photovoltaic power generation during the most recent daytime working period, expressed in kWh. Photovoltaic power generation curve, unit: kW; The unit hydrogen production energy consumption of the electrolyzer is expressed in kWh / Nm³. 3 ; This represents the total hydrogen production for the most recent daytime working period, in m³. 3 .

[0066] This invention enables refined management of hydrogen energy by predicting the total hydrogen production during daytime working hours in advance and establishing a comparison and response mechanism with the reserve: when the total production is sufficient, timely disposal of the surplus hydrogen can significantly improve the economic benefits of the system and avoid the idle waste of hydrogen energy; when the total production is insufficient, early alarms can give maintenance personnel sufficient time to take remedial measures and ensure the safety of nighttime energy supply.

[0067] To better understand the thermal management method of the present invention, a detailed explanation is provided below in conjunction with a heat exchange system.

[0068] The off-grid photovoltaic hydrogen production system provided in this embodiment of the invention is equipped with a dedicated first heat exchange unit and a second heat exchange unit to achieve precise distribution and efficient utilization of heat energy, forming a heat exchange structure adapted to different heat demands: the first heat exchange unit focuses on electrolyte temperature control and is connected to the electrolyte circulation pipeline and the heat output end of the phosphoric acid fuel cell, respectively, and its core includes a first heat exchanger, a first heat exchange pump, and a first regulating valve; the second heat exchange unit focuses on maintaining the ambient temperature of the hydrogen production workshop and is connected to the first heat exchange unit and the heating pipeline of the hydrogen production workshop, and its core includes a second heat exchanger, a second heat exchange pump, and a second regulating valve. Specifically, the first heat exchanger has four ports. The first inlet is connected to the heat output end of the phosphoric acid fuel cell via a pipe (a first regulating valve is installed on the pipe to control the amount of high-temperature flue gas entering). The second inlet and second outlet are respectively connected to the electrolyte circulation pipe (a first heat exchange pump is installed on the pipe to increase the electrolyte circulation rate and enhance heat exchange). The second heat exchanger also has four ports. The third inlet is connected to the first outlet of the first heat exchanger via a pipe (a second regulating valve is installed on the pipe to control the amount of medium-grade flue gas entering after passing through the first heat exchange unit). The fourth inlet and fourth outlet are respectively connected to the heating pipe of the hydrogen production workshop (a second heat exchange pump is installed on the pipe to accelerate the flow of the heating medium to ensure uniform workshop temperature). Preferably, the heat exchangers of both heat exchange units adopt a shell-and-tube structure, balancing heat exchange efficiency and equipment stability. The regulating valve is an electric proportional valve, which can dynamically adjust the opening according to heat demand. The heat exchange pump is a variable frequency pump, which can adapt to the flow requirements under different operating conditions. The overall structure forms a stepped heat exchange logic where high-temperature flue gas is prioritized for supplying the electrolyte, and medium-temperature flue gas is then supplied to the workshop.

[0069] Furthermore, when the nighttime working period is determined, based on the established hydrogen reserve required by the phosphoric acid fuel cell, the hydrogen storage device is first controlled to supply hydrogen to the phosphoric acid fuel cell, driving its operation to generate high-temperature flue gas (the manifestation of heat generated by the phosphoric acid fuel cell); then the high-temperature flue gas is distributed: firstly, the opening of the first regulating valve is adjusted to 100%, the second regulating valve is kept closed, and simultaneously the first heat exchange pump is started and adjusted to its rated speed, so that all the high-temperature flue gas (around 180°C) enters the first heat exchanger, fully exchanging heat with the electrolyte, utilizing high-quality... The thermal energy is used to maintain the electrolyte temperature at the target insulation temperature, preventing the alkaline solution from deteriorating due to nighttime temperature drops. After the electrolyte temperature stabilizes, the opening of the first regulating valve is gradually reduced to 60%-70%, while the second regulating valve is opened to 30%-40%. The second heat exchange pump is started and adjusted to medium speed, allowing the medium-grade flue gas, which has been cooled to 100°C after heat exchange in the first heat exchanger, to enter the second heat exchanger and exchange heat with the workshop heating medium in the tube side. This maintains the temperature of the hydrogen production workshop at an indoor ambient temperature of 20-25°C, meeting the basic operating environment requirements of the equipment.

[0070] This embodiment utilizes stepped heat exchange and dynamic valve control in the first and second heat exchange units to prioritize the use of high-temperature flue gas generated by the phosphoric acid fuel cell for electrolyte insulation, and then uses medium-temperature flue gas for workshop heating. This ensures that the electrolyte remains stable at the target insulation temperature, reduces system start-up time during the day, and meets the basic ambient temperature requirements of the workshop. At the same time, with the precise control of electric proportional valves and variable frequency pumps, efficient distribution of heat energy is achieved at night, ensuring stable operation of the system during periods of no light, eliminating dependence on the power grid, and realizing off-grid hydrogen production.

[0071] Specifically, during daytime working hours and when the electrolyzer is in start-up mode, the remaining hydrogen in the system is used as an energy source to control the phosphoric acid fuel cell to operate at its rated power, generating high-temperature flue gas. At this time, the rapid start-up operation control logic focuses on rapidly heating the electrolyte: the first regulating valve is adjusted to 100% opening, the second regulating valve is completely closed, and the first heat exchange pump is adjusted to its highest speed, allowing all the high-temperature flue gas to enter the first heat exchanger for strong heat exchange with the electrolyte. Simultaneously, the temperature of the alkali solution is monitored in real time by the temperature sensor on the electrolyte circulation pipeline, causing the alkali solution temperature to rise from the target insulation temperature to the optimal operating temperature of the electrolyzer. While the temperature is rising due to heat exchange, the phosphoric acid fuel cell simultaneously outputs electrical energy, directly supplying the deoxygenation heater and the regeneration heater to drive the heating elements of both types of equipment to start. The electrical energy input intensity is controlled by temperature feedback, causing the temperature of the deoxygenation heater to rise rapidly to 200-220℃ and the temperature of the regeneration heater to rise rapidly to 180-200℃, reaching the working temperature requirements for hydrogen purification.

[0072] This embodiment relies on the directional energy supply of the first heat exchange unit and the combined heat and power capability of the phosphoric acid fuel cell. All the high-temperature flue gas is used to rapidly heat up the electrolyte, and the electrical energy is output simultaneously to preheat the deoxygenation and regeneration heaters, so as to achieve the simultaneous attainment of standards for the electrolyte and purification equipment, and significantly shorten the start-up time. Compared with the traditional start-up method that relies solely on photovoltaic power, it solves the problem of slow start-up in low-temperature environments, thereby improving the hydrogen production efficiency and economic benefits of the system.

[0073] More specifically, during the daytime working period and with the electrolyzer in normal operating mode, the low-power operation includes: controlling the phosphoric acid fuel cell to reduce its operating power to 30%-40% of its rated power, reducing hydrogen consumption while generating low-load high-temperature flue gas; at this time, the control logic of the low-power operation focuses on balancing energy saving and basic heat preservation, closing the first regulating valve; adjusting the opening of the second regulating valve to 10%-20% and the second heat exchange pump to low speed, introducing all the high-temperature flue gas into the workshop heating pipes to provide basic heat preservation for the hydrogen production workshop, maintaining the workshop temperature at 20-25℃, without consuming any additional energy; at the same time, the electrical energy output by the phosphoric acid fuel cell is only supplied to the core components of the system, such as the deoxygenation heater and the regeneration heater.

[0074] This embodiment controls the phosphoric acid fuel cell to maintain continuous low-power operation while simultaneously closing the first regulating valve and precisely controlling the second regulating valve, directing all the low-load flue gas generated to the workshop for insulation. This approach not only caters to the long start-up time of the phosphoric acid fuel cell, fundamentally avoiding equipment lifespan degradation and high restart energy consumption caused by frequent start-ups and shutdowns, but also maintains a suitable ambient temperature in the workshop without requiring additional energy consumption. Furthermore, its output power is precisely supplied to the core equipment of the purification unit, minimizing unnecessary hydrogen consumption while ensuring normal hydrogen production. This also reserves sufficient hydrogen reserves for nighttime insulation, further improving system operational stability and overall hydrogen utilization efficiency.

[0075] Please refer to Figure 2Based on the same inventive concept, this invention also provides a thermal energy management device for an off-grid photovoltaic hydrogen production system. The off-grid photovoltaic hydrogen production system includes a phosphoric acid fuel cell. The device includes a time period determination module, a nighttime management module, and a daytime management module. The time period determination module is used to determine the current working period. The nighttime management module is electrically connected to the time period determination module and is used to determine the required hydrogen reserve for the phosphoric acid fuel cell when the current working period is a nighttime working period, and generate a thermal energy management operation command based on the hydrogen reserve. The daytime management module is electrically connected to the time period determination module and is used to determine the operating mode of the electrolyzer when the current working period is a daytime working period. When the operating mode is a start-up mode, it generates a fast start command to control the phosphoric acid fuel cell to perform a fast start-up operation for the electrolyzer. When the operating mode is a normal operating mode, it generates a low-power command to control the phosphoric acid fuel cell to perform a low-power operation.

[0076] In addition, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the thermal energy management method of the off-grid photovoltaic hydrogen production system described in any of the above claims.

[0077] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0078] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not describe the various possible combinations separately.

[0079] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0080] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A thermal energy management method for an off-grid photovoltaic hydrogen production system, characterized in that, The off-grid photovoltaic hydrogen production system includes a phosphoric acid fuel cell, and the method includes: Determine the current work period; If the current work period is the night work period: Determine the required hydrogen reserve for the phosphoric acid fuel cell; Perform corresponding thermal energy management operations based on the hydrogen reserve; If the current work period is during daytime: Determine the operating mode of the electrolytic cell; When the operating mode is the start-up mode, the phosphoric acid fuel cell is controlled to perform a rapid start-up operation on the electrolyzer. When the operating mode is normal operation, the phosphoric acid fuel cell is controlled to perform low-power operation.

2. The method according to claim 1, characterized in that, Determining the required hydrogen reserve for the phosphoric acid fuel cell includes: Determine the required heat insulation for the off-grid photovoltaic hydrogen production system at night; Determine the operating power required for the off-grid photovoltaic hydrogen production system to operate at night; The required hydrogen reserve for the phosphoric acid fuel cell is determined based on the operating electrical energy and the heat preservation heat.

3. The method according to claim 2, characterized in that, Determining the required heat preservation for the off-grid photovoltaic hydrogen production system at night includes: Obtain the nighttime predicted temperature for that night; Determine the target insulation temperature for the off-grid photovoltaic hydrogen production system; Identify the factors that cause temperature instability, and determine a safety margin based on these factors. The required insulation heat for nighttime is determined based on the predicted nighttime temperature, the target insulation temperature, and the safety margin. The insulation heat is characterized as follows: ， Where U represents the building's overall heat transfer coefficient, and A represents the building envelope area. Characterized by the indoor ambient temperature that needs to be maintained. Characterized by nighttime predicted temperature, Characterized as the target insulation temperature, Characterized by nighttime duration, Characterized by the total mass of the alkaline solution in the electrolytic cell. Characterized by the specific heat capacity of the alkaline solution. This is represented as a safety margin.

4. The method according to claim 2, characterized in that, The determination of the operating power required for the off-grid photovoltaic hydrogen production system to operate at night includes: Determine the first nighttime operating power of the alkaline solution circulation pump in the off-grid photovoltaic hydrogen production system; Determine the nighttime auxiliary equipment for the off-grid photovoltaic hydrogen production system; Obtain the second nighttime operating power of the nighttime auxiliary equipment; The total operating power is determined based on the first nighttime operating power and the second nighttime operating power; The required operating power for nighttime operation is determined based on the total operating power.

5. The method according to claim 2, characterized in that, Determining the required hydrogen reserve for the phosphoric acid fuel cell based on the operating electrical energy and the insulation heat includes: Determine the thermal efficiency and electrical efficiency of the phosphoric acid fuel cell, and determine the heat exchange efficiency of the off-grid photovoltaic hydrogen production system; The heat demand of the phosphoric acid fuel cell is determined based on the heat preservation capacity, the thermal efficiency, and the heat exchange efficiency. The power generation requirements of the phosphoric acid fuel cell are determined based on the operating electrical energy and the electrical efficiency. The input energy requirement of the phosphoric acid fuel cell is determined based on the heat generation requirement and the power generation requirement. The required hydrogen reserve for the phosphoric acid fuel cell is determined based on the input energy demand.

6. The method according to claim 5, characterized in that, Determining the required hydrogen reserve for the phosphoric acid fuel cell based on the input energy demand includes: Obtain the high calorific value of hydrogen and determine the density of hydrogen output from the off-grid photovoltaic hydrogen production system; The hydrogen reserve is determined based on the input energy requirement, the higher calorific value of hydrogen, and the hydrogen density. The hydrogen reserve is characterized as follows: ， in, Characterized by the high calorific value of hydrogen, Characterized by hydrogen density, It is characterized as input energy demand.

7. The method according to claim 1, characterized in that, The off-grid photovoltaic hydrogen production system further includes a deoxygenation heater and a regeneration heater. Controlling the phosphoric acid fuel cell to perform a rapid start-up operation on the electrolyzer includes: Determine whether the off-grid photovoltaic hydrogen production system contains residual hydrogen; If so, the phosphoric acid fuel cell is controlled to perform heating and discharging operations based on the remaining hydrogen gas; Based on the heating operation, the alkaline solution is heated to a target heating temperature, which is higher than the target holding temperature; Electrical energy is input to the deoxygenation heater and the regeneration heater based on the discharge operation to perform the corresponding heating operation.

8. The method according to claim 1, characterized in that, The method further includes: Given that the current working period is a daytime working period, predict the total hydrogen production during the most recent daytime working period; Determine whether the total hydrogen production is greater than or equal to the hydrogen reserve. If so, determine the remaining hydrogen quantity based on the total hydrogen production and the hydrogen reserve, and perform a hydrogen sale operation based on the remaining hydrogen quantity; Otherwise, generate the corresponding alarm information.

9. A thermal energy management device for an off-grid photovoltaic hydrogen production system, characterized in that, The off-grid photovoltaic hydrogen production system includes a phosphoric acid fuel cell, and the device includes a time period determination module, a night management module, and a daytime management module. The time period determination module is used to determine the current working time period; The night management module is electrically connected to the time period determination module and is used to determine the amount of hydrogen required for the phosphoric acid fuel cell when the current working period is a night working period, and generate thermal energy management operation instructions based on the amount of hydrogen. The daytime management module is electrically connected to the time period determination module. When the current working period is a daytime working period, it determines the working mode of the electrolyzer. When the working mode is a start-up mode, it generates a fast start command to control the phosphoric acid fuel cell to perform a fast start operation for the electrolyzer. When the working mode is a normal operating mode, it generates a low power consumption command to control the phosphoric acid fuel cell to perform a low power consumption operation.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the thermal energy management method for the off-grid photovoltaic hydrogen production system according to any one of claims 1-8.

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