Fuel cell hybrid power supply system and interval efficiency regulation method thereof

Abstract

The application provides a fuel cell hybrid power supply system and an interval efficiency regulation method thereof, the system adopts a two-section constant feed regulation mode, two energy storage devices are arranged to store ammonia energy and hydrogen energy, and an interval efficiency regulation strategy is set, and the SOC health degree of the storage battery is considered according to the regulation strategy. Compared with the traditional real-time online feed regulation, the control mode and the regulation strategy of limiting the valve opening degree to reduce fuel consumption, the control mode can effectively reduce the real-time fluctuation of the feed quantity caused by external disturbance, thereby reducing the influence on the catalytic cracker and the influence of real-time regulation of multiple valves on the burner and the power generation device, and improving the robustness of the power generation system. At the same time, the regulation strategy can effectively improve the power generation efficiency of the overall system in the V-shaped output characteristic hybrid system, reduce the capacity and peak power of the power battery, reduce the demand and economic cost of ammonia.

Description

Technical Field

[0001] This invention relates to the field of power equipment technology, and in particular to a fuel cell hybrid power supply system and its interval efficiency control method. Background Technology

[0002] In practical engineering applications, loads often exhibit high frequency and large amplitude fluctuations, posing a challenge to power systems designed to meet these load characteristics. These systems need to possess features such as high load output power, a wide variable output power range, fast load response, easy fuel transport and storage, and simple control methods. Internal combustion engines are widely used due to their mature technology, rapid energy conversion, low cost, high output power, high waste heat quality, and abundant waste heat resources. Proton exchange membrane fuel cells have high application potential due to their high power generation efficiency and zero emissions. Furthermore, compared to hydrogen, ammonia is easier to store and transport, and its hydrogen production process does not generate carbon emissions, resulting in better environmental performance. Therefore, constructing a hybrid power generation system combining ammonia-hydrogen production, an internal combustion engine, and a fuel cell can effectively combine the advantages of these components and fully utilize their waste heat resources, thereby improving the overall performance of the hybrid power generation system.

[0003] As a traditional power source, the output efficiency of an internal combustion engine gradually increases with increasing output power; however, the efficiency of a proton exchange membrane fuel cell (PEMFC) gradually decreases with increasing output power. In a hybrid power generation system consisting of an ammonia-to-hydrogen production line, internal combustion engine, and fuel cell, the control parameters are generally adjusted by regulating the distribution ratio valve and the total amount of hydrogen entering the internal combustion engine and fuel cell. When the output power is low, the power output component of the hybrid power generation system is dominated by the PEMFC. As the output power increases, the output proportion of the fuel cell decreases, while the output proportion of the internal combustion engine increases. Since the output efficiency of the internal combustion engine is much lower than that of the fuel cell, the output efficiency of the hybrid power generation system decreases with increasing output power when the output power is low. When the output power is high, the output of the hybrid power generation system is dominated by the internal combustion engine. As the output power increases, the output power of the internal combustion engine increases, and the output characteristics of the hybrid power generation system become similar to those of the internal combustion engine, with the output efficiency increasing with increasing output power. Therefore, the output power and output efficiency characteristics of the hybrid power generation system exhibit a "V"-shaped characteristic curve relationship.

[0004] However, in real-world applications with frequent load fluctuations, traditional real-time online feed control strategies may lead to input instability in certain hybrid power generation systems equipped with hydrogen production modules and burners. This poses a significant challenge to the robustness of the hybrid power generation system in the event of uncontrollable disturbances or sudden failures. Furthermore, when the output power in real-world scenarios is high, simply limiting the opening of the distribution valve to reduce power output can easily cause the hybrid power generation system to operate in a lower output efficiency range, resulting in a decline in its performance. In addition, because the valve opening is limited, the maximum output power of the hybrid power generation system is also limited, which leads to an increase in the peak charging and discharging power of the battery under high-load operating conditions, thereby increasing battery costs. Summary of the Invention

[0005] This invention provides a fuel cell hybrid power supply system and its interval efficiency control method to solve the problems caused by the control strategy of the fuel cell hybrid power supply system in the prior art, which leads to unstable system input, low power generation efficiency, and increased peak charging and discharging power of the battery. This invention achieves stable system input, improves the power generation efficiency of the hybrid power generation system, and reduces the peak charging and discharging power of the battery while maintaining high efficiency.

[0006] This invention provides a fuel cell hybrid energy supply system, comprising:

[0007] Ammonia-hydrogen internal combustion engines and hydrogen fuel cells are used to generate and supply electrical energy.

[0008] A storage battery connected to an ammonia-hydrogen internal combustion engine and a hydrogen fuel cell, wherein the storage battery is used to store electrical energy and provide electrical energy;

[0009] An ammonia storage tank, wherein the ammonia storage tank contains liquid ammonia, the liquid ammonia providing energy to the fuel cell hybrid power supply system;

[0010] The first multi-stream heat exchanger is used to preheat the liquid ammonia and vaporize it into ammonia gas using the cylinder liner water of the ammonia-hydrogen internal combustion engine and the cooling water of the hydrogen fuel cell.

[0011] The second multi-stream heat exchanger is used to reheat the ammonia gas using the hydrogen-nitrogen mixture output from the catalytic cracker and the exhaust gas from the ammonia-hydrogen internal combustion engine.

[0012] A catalytic cracker is used to decompose the reheated ammonia gas into the hydrogen-nitrogen mixture.

[0013] A burner is used to provide heat for the catalytic cracking process of the catalytic cracker;

[0014] A separator is used to separate hydrogen from the hydrogen-nitrogen mixture output from the second multi-stream heat exchanger;

[0015] The output end of the first multi-stream heat exchanger is connected to a buffer tank, which is used to store the vaporized ammonia and to input the ammonia into the ammonia-hydrogen internal combustion engine and the second multi-stream heat exchanger through the first regulating distribution valve, so as to provide a constant flow of ammonia to the catalytic cracker.

[0016] The burner's input is connected to a hydrogen storage tank, which stores hydrogen separated from the hydrogen-nitrogen mixture. The hydrogen is then distributed to the burner and another branch via a second regulating valve, providing a constant flow of hydrogen to the burner and reducing variations in the valve's opening. Hydrogen from the other branch is fed into the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell via a third regulating valve, providing a constant total flow of hydrogen to both. The third regulating valve is used to distribute the hydrogen, thereby controlling the output power of the fuel cell hybrid power supply system.

[0017] According to a fuel cell hybrid power supply system provided by the present invention, a pressure reducing valve is further included, which is located between the first multi-stream heat exchanger and the buffer tank, and is used to reduce the pressure of the vaporized ammonia entering the buffer tank.

[0018] According to the present invention, a fuel cell hybrid power supply system further includes a water pump and an air-cooled heat exchanger. The water pump is used to extract the cylinder liner water and cooling water output from the first multi-stream heat exchanger and input them into the corresponding ammonia-hydrogen internal combustion engine and hydrogen fuel cell through the air-cooled heat exchanger, thereby providing power for the circulation loop of the cylinder liner water and cooling water.

[0019] The present invention also provides a range efficiency regulation method, applied to any of the above-described fuel cell hybrid power supply systems, comprising:

[0020] Based on the total amount of hydrogen entering the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell, determine the power-efficiency output characteristic diagram of the fuel cell hybrid energy supply system;

[0021] Based on the preset lower limit of the power generation efficiency of the fuel cell hybrid power supply system and the corresponding output power in the power-efficiency output characteristic diagram, the output power in the power-efficiency output characteristic diagram is divided into multiple intervals, including a first output power interval, a second output power interval, and a third output power interval. The value in the first output power interval is less than the value in the second output power interval, and the value in the second output power interval is less than the value in the third output power interval.

[0022] The first output power range and the third output power range are defined as the operating range of the fuel cell hybrid power supply system.

[0023] By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is located within the operating range under the total amount of hydrogen input.

[0024] According to a method for range efficiency control provided by the present invention, by adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is located within the operating range under the total hydrogen input, including:

[0025] The power of the load is compared with each range, and the target output power of the fuel cell hybrid power supply system is determined based on the comparison results. The target output power is located within the operating range.

[0026] By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is made equal to the target output power.

[0027] According to a method for interval efficiency control provided by the present invention, the power of the load is compared with each interval, and the target output power of the fuel cell hybrid power supply system is determined based on the comparison results, including:

[0028] When the power of the load falls within the operating range, the target output power is equal to the power of the load;

[0029] When the power of the load is greater than the maximum value in the third output power range, the target output power is equal to the maximum value;

[0030] When the power of the load is less than the minimum value in the first output power range, the target output power is equal to the minimum value;

[0031] When the power of the load is within the second output power range, the target output power is equal to the maximum value in the first output power range.

[0032] The interval efficiency control method provided by the present invention further includes:

[0033] Determine the difference between the power of the load and the target output power;

[0034] The battery does not operate when the power of the load is equal to the target output power;

[0035] When the power of the load is greater than the target output power, the difference in electrical energy is supplemented by the battery.

[0036] When the power of the load is less than the target output power, the excess electrical energy corresponding to the difference is stored in the battery.

[0037] The interval efficiency control method provided by the present invention further includes:

[0038] When the power of the load is greater than the target output power, the SOC of the battery is compared with a first preset threshold.

[0039] If the SOC of the battery is less than the first preset threshold, the preset lower limit of power generation efficiency is reduced, thereby increasing the range of the working range.

[0040] If the SOC of the battery is greater than or equal to the first preset threshold, then the battery will be used to replenish the electrical energy corresponding to the difference.

[0041] The interval efficiency control method provided by the present invention further includes:

[0042] When the power of the load is less than the target output power, the SOC of the battery is compared with a second preset threshold.

[0043] If the SOC of the battery is greater than the second preset threshold, the fuel cell hybrid power supply system stops working and the battery supplies power to the load.

[0044] If the SOC of the battery is less than or equal to the second preset threshold, the excess electrical energy corresponding to the difference is stored in the battery.

[0045] According to the interval efficiency control method provided by the present invention, the larger the total amount of hydrogen input, the larger the preset lower limit of power generation efficiency, and the larger the range of the working interval of the fuel cell hybrid power supply system.

[0046] This invention provides a fuel cell hybrid power supply system and its interval efficiency control method. The system utilizes a multi-stream heat exchanger to preheat and vaporize ammonia using cylinder liner water from the internal combustion engine and cooling water from the fuel cell. Simultaneously, it uses a hydrogen-nitrogen mixture and exhaust gas from the internal combustion engine to further preheat the ammonia. Finally, a hydrogen burner preheats the ammonia to a higher temperature before it enters the catalytic cracker. A two-stage constant feed control method is employed, with two energy storage devices storing ammonia and hydrogen energy. By setting the total amount of hydrogen entering the internal combustion engine and fuel cell to a constant value and adjusting the distribution valves, the system's output is controlled. Compared to traditional real-time feed control hybrid power generation systems, this method effectively improves the robustness and stability of the entire system, significantly increases the power generation efficiency of the hybrid power generation system, and reduces the peak charging and discharging power and energy storage capacity of the battery. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of the fuel cell hybrid energy supply system provided by the present invention;

[0049] Figure 2 This is an output characteristic diagram of the fuel cell hybrid energy supply system provided by the present invention;

[0050] Figure 3 This is a power-efficiency relationship diagram of the fuel cell hybrid power supply system provided by the present invention under a certain total hydrogen intake.

[0051] Figure 4 This is a flowchart illustrating the interval efficiency control method provided by the present invention;

[0052] Figure 5 This is a schematic diagram of interval division in the interval efficiency control method provided by the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0054] The following is combined Figure 1 A fuel cell hybrid energy supply system according to the present invention includes:

[0055] The ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18 are used to generate electrical energy and provide electrical energy for the entire system.

[0056] A storage battery 23 is connected to an ammonia-hydrogen internal combustion engine 17 and a hydrogen fuel cell 18. The storage battery 23 is used to store electrical energy and provide electrical energy.

[0057] Ammonia storage tank 1, wherein liquid ammonia is stored in ammonia storage tank 1, and the liquid ammonia provides energy for the fuel cell hybrid power supply system;

[0058] The first multi-stream heat exchanger 2 is used to preheat the liquid ammonia and vaporize it into ammonia gas using the cylinder liner water of the ammonia-hydrogen internal combustion engine 17 and the cooling water of the hydrogen fuel cell 18.

[0059] The second multi-stream heat exchanger 8 is used to reheat the ammonia gas using the hydrogen-nitrogen mixture output from the catalytic cracker 10 and the exhaust gas from the ammonia-hydrogen internal combustion engine.

[0060] Catalytic cracker 10 is used to decompose the reheated ammonia gas into the hydrogen-nitrogen mixture.

[0061] Burner 12 is used to provide heat for the catalytic cracking of the catalytic cracker 10;

[0062] Separator 15 is used to separate hydrogen from the hydrogen-nitrogen mixture output from the second multi-stream heat exchanger 8;

[0063] The output end of the first multi-stream heat exchanger 2 is connected to a buffer tank 5. The buffer tank 5 is used to store the vaporized ammonia and to input the ammonia into the ammonia-hydrogen internal combustion engine 17 and the second multi-stream heat exchanger 8 through the first regulating distribution valve 6, so as to provide a constant flow of ammonia to the catalytic cracker 10.

[0064] The input end of the burner 12 is connected to a hydrogen storage tank 13, which stores hydrogen separated from the hydrogen-nitrogen mixture and distributes the hydrogen to the burner 12 and another branch through a second regulating distribution valve 14, providing a constant flow of hydrogen to the burner 12 and reducing the opening variation of the second regulating distribution valve 14. The hydrogen from the other branch is input to the ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18 through a third regulating distribution valve 16, providing a constant total flow of hydrogen to the ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18. The third regulating distribution valve 16 is adjusted to distribute the hydrogen and control the output power of the fuel cell hybrid energy supply system.

[0065] In order to better utilize the waste heat resources of each component, reduce the mass of catalyst in the catalytic cracker, thereby reducing the cost of the entire system and improving the robustness of the entire system, the system and its control method were designed.

[0066] Ammonia is initially preheated and vaporized using cylinder liner water from the internal combustion engine and cooling water from the fuel cell via a multi-stream heat exchanger. Simultaneously, a hydrogen-nitrogen mixture and exhaust gas from the internal combustion engine further preheat the ammonia. Finally, a hydrogen burner preheats the ammonia to a higher temperature before it enters the catalytic cracker. A buffer tank and a hydrogen storage tank are installed before the first multi-stream heat exchanger and the burner, respectively. The buffer tank stores the vaporized ammonia and provides a constant flow of ammonia to the catalytic cracker, reducing the pressure of ammonia directly entering the internal combustion engine and heat exchanger, thus better matching the ammonia input with the system output requirements. The hydrogen storage tank stores the hydrogen after gas separation, maintaining a constant amount of hydrogen entering the burner branch. It also serves for system startup and reduces variations in the opening of the gas regulating valve on the hydrogen storage tank above the gas separator. By setting a constant total amount of hydrogen entering the internal combustion engine and fuel cell, and adjusting the distribution valve, the system's output is controlled.

[0067] The first regulating and distributing valve 6 is an ammonia regulating and distributing valve, which distributes ammonia gas so that one path leads to the internal combustion engine and the other to the catalytic converter. The internal combustion engine exhaust treatment device 9 is used to remove nitrogen oxides generated in the internal combustion engine exhaust. The catalytic converter 10 decomposes ammonia into hydrogen, providing fuel for the fuel cell, internal combustion engine, and burner. It also includes a heat exchange device for the internal combustion engine exhaust to recover some of the heat from the exhaust. The burner 12 provides heat to the catalytic converter to ensure the catalytic process proceeds smoothly. The second regulating and distributing valve 14 is a hydrogen inlet regulating and distributing valve for the hydrogen storage tank, which distributes some of the hydrogen required for combustion to the hydrogen storage tank, and then to the burner. The separator 15 separates nitrogen, reducing the amount of nitrogen distributed to the combustion and power units, thereby reducing nitrogen oxide production and improving the system's energy conversion efficiency. The third regulating and distributing valve 16 is a power unit hydrogen inlet distributing valve, which distributes hydrogen to the internal combustion engine and fuel cell. The ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18 are the main power units of the system. The current generated is integrated through the internal combustion engine output current converter 19 and the fuel cell output current converter 21, and then through the circuit merging device 20 to provide power to the heavy-duty equipment 24. When the power is insufficient or excessive, it is supplemented or absorbed by the battery 23 after passing through the battery current converter 22.

[0068] After the liquid ammonia is vaporized by heat exchange in the first multi-stream heat exchanger, it enters a buffer tank. Two pipelines exit the buffer tank, directly connecting to the internal combustion engine and the ammonia catalytic cracking unit, respectively. After catalytic cracking, the produced hydrogen is divided into two pipelines: one leads to a hydrogen storage tank and then to the burner, providing fuel for the burner; the other leads to the power unit. The pipeline to the power unit further branches into two: one leads to the internal combustion engine, providing fuel for the internal combustion engine; the other leads to the fuel cell, providing fuel for the fuel cell. The amount of ammonia fed into the internal combustion engine is proportional to the amount of hydrogen fed into the engine. The fuel required for burner reheating is supplied in real-time according to system demand.

[0069] like Figure 2 As shown in the test, it was found that under the same total hydrogen intake, as the hydrogen allocation ratio of the fuel cell increases, the system output power decreases, and one hydrogen allocation ratio corresponds to one system output power. With the increase of the allocation ratio, the output of the fuel cell in the hybrid power generation system increases, the output of the internal combustion engine decreases, and the total output of the hybrid system decreases. When the total hydrogen intake is large, within a certain range, as the allocation ratio increases, the output of the hybrid power generation system increases because the internal combustion engine may experience full load.

[0070] like Figure 3 As shown in the diagram, tests revealed that, under a constant total hydrogen intake, the output efficiency versus output power of the hybrid system exhibits a V-shaped curve. At lower output power, the hybrid power generation system's output is primarily driven by the fuel cell. As output power increases, the proportion of output from the more efficient fuel cell decreases, while the proportion from the internal combustion engine increases, leading to a decrease in the hybrid power generation system's output efficiency. Conversely, at higher output power, the hybrid power generation system's output is dominated by the internal combustion engine, and the internal combustion engine's output efficiency increases with increasing output power, consequently increasing the hybrid power generation system's output efficiency. Therefore, within a certain range, the hybrid system's output efficiency decreases with increasing output power; however, beyond this range, the output efficiency increases with increasing output power, resulting in a V-shaped curve for the hybrid system's output efficiency versus output power relationship.

[0071] This embodiment utilizes a multi-stream heat exchanger to preheat and vaporize ammonia using cylinder liner water from the internal combustion engine and cooling water from the fuel cell. Simultaneously, it further preheats the ammonia using a hydrogen-nitrogen mixture and exhaust gas from the internal combustion engine. Finally, a hydrogen burner preheats the ammonia to a higher temperature before it enters the catalytic cracker. A two-stage constant feed control method is employed, with two energy storage devices storing ammonia and hydrogen. By setting a constant total amount of hydrogen entering the internal combustion engine and fuel cell, and adjusting the distribution valves to allocate hydrogen, the system's output is controlled. Compared to traditional real-time feed control hybrid power generation systems, this approach effectively improves the robustness and stability of the entire system, significantly increases the power generation efficiency of the hybrid power generation system, and reduces the peak charging and discharging power and energy storage capacity of the battery.

[0072] Based on the above embodiments, this embodiment also includes a pressure reducing valve 3, which is located between the first multi-stream heat exchanger 2 and the buffer tank 5. The pressure reducing valve 3 is used to reduce the pressure of the vaporized ammonia entering the buffer tank 5, thereby ensuring the safety of the buffer tank.

[0073] Based on the above embodiments, this embodiment further includes a water pump and an air-cooled heat exchanger 11. The water pump draws the cylinder liner water and cooling water output from the first multi-stream heat exchanger 2 and inputs them through the air-cooled heat exchanger 11 to the corresponding ammonia-hydrogen internal combustion engine 17 and hydrogen fuel cell 18, providing power for the circulation loop of the cylinder liner water and cooling water and overcoming the pressure drop of the water during circulation. The air-cooled heat exchanger 11 is a heat exchange device used to reduce the excess temperature of the internal combustion engine cylinder liner water and fuel cell cooling water to a set temperature.

[0074] The water pumps include a cooling water pump 4 and a cylinder liner water pump 7. The cooling water pump 4 provides sufficient head for the fuel cell cooling water, ensuring that the water in the pipeline can circulate smoothly. The cylinder liner water pump 7 is for providing sufficient head for the internal combustion engine cylinder liner water, ensuring that the water in the pipeline can circulate smoothly.

[0075] like Figure 4 As shown, this embodiment provides a range efficiency control method, applied to the fuel cell hybrid power supply system in any of the above embodiments, including:

[0076] Based on the total amount of hydrogen entering the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell, determine the power-efficiency output characteristic diagram of the fuel cell hybrid energy supply system;

[0077] Based on the preset lower limit of the power generation efficiency of the fuel cell hybrid power supply system and the corresponding output power in the power-efficiency output characteristic diagram, the output power in the power-efficiency output characteristic diagram is divided into multiple intervals, including a first output power interval, a second output power interval, and a third output power interval. The value in the first output power interval is less than the value in the second output power interval, and the value in the second output power interval is less than the value in the third output power interval.

[0078] The first output power range and the third output power range are defined as the operating range of the fuel cell hybrid power supply system.

[0079] By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is located within the operating range under the total amount of hydrogen input.

[0080] like Figure 5 As shown, before the hybrid power generation system operates, a lower limit for its power generation efficiency is set. An iso-efficiency line corresponding to the set total hydrogen input is plotted on the power-efficiency output characteristic diagram, intersecting the output characteristic curve at point 1' where the power is lower and at point 2 where the power is higher. Simultaneously, the minimum output power point of the output characteristic is set to point 1, and the maximum output power point is set to point 2'. The hybrid power generation system achieves power output within a certain range based on the total hydrogen input by adjusting the hydrogen distribution ratio entering the fuel cell.

[0081] The first output power range is from point 1 to point 1', the second output power range is from point 1' to point 2, and the third output power range is from point 2 to point 2'. The first and third output power ranges serve as the operating ranges for the fuel cell hybrid power supply system. Power output within these operating ranges is achieved by adjusting the hydrogen distribution ratio entering the fuel cell.

[0082] This embodiment controls the total amount of hydrogen entering the internal combustion engine and fuel cell to a constant value. By adjusting the hydrogen distribution ratio entering the fuel cell, it achieves power output within a certain range under a constant hydrogen intake. Compared with the constant hydrogen intake control strategy with monotonic output characteristics, it can effectively improve the power generation efficiency of the hybrid power generation system, reduce the peak charging and discharging power of the battery and the required battery capacity, and reduce the total ammonia and ammonia storage tank capacity. It can effectively reduce the component cost of the hybrid power generation system and improve the overall efficiency of the hybrid power generation system.

[0083] Based on the above embodiments, this embodiment adjusts the hydrogen distribution ratio entering the hydrogen fuel cell so that the output power of the fuel cell hybrid power supply system is within the operating range under the total hydrogen intake, including:

[0084] The power of the load is compared with each range, and the target output power of the fuel cell hybrid power supply system is determined based on the comparison results. The target output power is located within the operating range.

[0085] By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is made equal to the target output power.

[0086] Based on the above embodiments, this embodiment compares the load power with each range, and determines the target output power of the fuel cell hybrid power supply system according to the comparison results, including:

[0087] When the power of the load falls within the operating range, the target output power is equal to the power of the load;

[0088] When the power of the load is greater than the maximum value in the third output power range, the target output power is equal to the maximum value;

[0089] When the power of the load is less than the minimum value in the first output power range, the target output power is equal to the minimum value;

[0090] When the power of the load is within the second output power range, the target output power is equal to the maximum value in the first output power range.

[0091] like Figure 5 As shown, when the load power is less than the output power corresponding to point 1, the system output is according to point 1, and the excess power is stored in the battery; when the load power is between point 1 and point 1', the system output power is equal to the load output power, and the battery does not work; when the load power is between point 1' and point 2, the system output power is according to point 1', and the battery supplements the insufficient power; when the load power is between point 2 and point 2', the system output power is equal to the load output power, and the battery does not work; when the load is greater than point 2', the system output power is according to point 2', and the battery supplements the insufficient power.

[0092] Based on the above embodiments, this embodiment also includes:

[0093] Determine the difference between the power of the load and the target output power;

[0094] The battery does not operate when the power of the load is equal to the target output power;

[0095] When the power of the load is greater than the target output power, the difference in electrical energy is supplemented by the battery.

[0096] When the power of the load is less than the target output power, the excess electrical energy corresponding to the difference is stored in the battery.

[0097] This embodiment addresses the problem of excessive battery charging and discharging power caused by limiting the opening of the distribution valve in a constant hydrogen intake control strategy, which leads to a decrease in the output power of the hybrid power generation system. A range-based efficiency control strategy effectively solves this problem. Within a certain efficiency range, the maximum output power of the hybrid power generation system remains constant, while the power difference below the efficiency range is kept small, thus ensuring that the peak charging and discharging power of the battery remains constant. This strategy also effectively reduces the total output of the hybrid power generation system, improves its operating efficiency, reduces ammonia consumption and thus reduces ammonia storage tank capacity, while simultaneously reducing battery capacity and residual charge after operation.

[0098] Based on the above embodiments, this embodiment also includes:

[0099] When the power of the load is greater than the target output power, the SOC (State of Charge) of the battery is compared with a first preset threshold.

[0100] If the SOC of the battery is less than the first preset threshold, the preset lower limit of power generation efficiency is reduced, thereby increasing the range of the working range.

[0101] If the SOC of the battery is greater than or equal to the first preset threshold, then the battery will be used to replenish the electrical energy corresponding to the difference.

[0102] Based on the above embodiments, this embodiment further includes:

[0103] When the power of the load is less than the target output power, the SOC of the battery is compared with a second preset threshold.

[0104] If the SOC of the battery is greater than the second preset threshold, the fuel cell hybrid power supply system stops working and the battery supplies power to the load.

[0105] If the SOC of the battery is less than or equal to the second preset threshold, the excess electrical energy corresponding to the difference is stored in the battery.

[0106] like Figure 4As shown, the interval efficiency control strategy proposed in this embodiment is as follows: before the hybrid power generation system starts working, a lower limit for the power generation efficiency of the hybrid power generation system is set, and a certain total amount of hydrogen input is set during operation. Based on the output characteristic diagram of this total amount of hydrogen input and the power output point corresponding to the lower limit of efficiency, the operating interval and operating state of the system are determined. The hybrid power generation system achieves power output within a certain range of this total amount of hydrogen input by adjusting the hydrogen distribution ratio entering the fuel cell.

[0107] When the load power falls within the operating range, the system output equals the load power, and the battery does not operate. When the load power exceeds the larger output range, the system outputs at the maximum output point. At this point, the battery's State of Charge (SOC) value is assessed: if the battery SOC is below a set threshold, the system's lower efficiency limit can be readjusted to increase the system's output range; if the battery SOC is not below the set threshold, the battery supplements the insufficient power. When the load power is less than the smaller output range, the battery's SOC value is assessed again: if the battery SOC exceeds the set threshold, the hybrid system stops operating, and only the battery outputs power; if the battery SOC does not exceed the set threshold, the system outputs at the minimum output power, and the battery stores excess power. When the load power is between the smaller and larger output ranges, the battery's SOC value is assessed again: if the battery SOC is below the set threshold, the system's lower efficiency limit is readjusted to increase the system's output range; if the battery SOC is not below the set threshold, the system outputs at the maximum output power of the smaller output range, and the battery supplements the insufficient power.

[0108] This embodiment establishes a range-based efficiency control strategy, which takes into account the battery's SOC health. Compared to traditional real-time online feed control and valve opening restriction to reduce fuel consumption, this control method effectively reduces the impact of external disturbances on feed rate fluctuations and their effect on the catalytic cracker, as well as the impact of real-time valve control on the burner and power generation unit, thus improving the robustness of the power generation system. Furthermore, the proposed control strategy effectively improves the overall system power generation efficiency in a hybrid system with "V"-shaped output characteristics, reduces the battery capacity and peak charge / discharge power, and decreases ammonia demand and economic costs.

[0109] Based on the above embodiments, in this embodiment, the larger the total amount of hydrogen introduced, the larger the preset lower limit of power generation efficiency, and the larger the range of the working range of the fuel cell hybrid power supply system.

[0110] By changing the total amount of hydrogen entering the internal combustion engine and fuel cell, the power output range and overall efficiency of the hybrid power generation system can be improved, thereby setting a higher efficiency lower limit and effectively reducing the capacity of the system's ammonia storage tank, as well as the capacity and peak power performance of the power battery.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell hybrid energy supply system, characterized in that, include: Ammonia-hydrogen internal combustion engines and hydrogen fuel cells are used to generate and supply electrical energy. A storage battery connected to an ammonia-hydrogen internal combustion engine and a hydrogen fuel cell, wherein the storage battery is used to store electrical energy and provide electrical energy; An ammonia storage tank, wherein the ammonia storage tank contains liquid ammonia, the liquid ammonia providing energy to the fuel cell hybrid power supply system; The first multi-stream heat exchanger is used to preheat the liquid ammonia and vaporize it into ammonia gas using the cylinder liner water of the ammonia-hydrogen internal combustion engine and the cooling water of the hydrogen fuel cell. The second multi-stream heat exchanger is used to reheat the ammonia gas using the hydrogen-nitrogen mixture output from the catalytic cracker and the exhaust gas from the ammonia-hydrogen internal combustion engine. A catalytic cracker is used to decompose the reheated ammonia gas into the hydrogen-nitrogen mixture. A burner is used to provide heat for the catalytic cracking process of the catalytic cracker; A separator is used to separate hydrogen from the hydrogen-nitrogen mixture output from the second multi-stream heat exchanger; The output end of the first multi-stream heat exchanger is connected to a buffer tank, which is used to store the vaporized ammonia and to input the ammonia into the ammonia-hydrogen internal combustion engine and the second multi-stream heat exchanger through the first regulating distribution valve, so as to provide a constant flow of ammonia to the catalytic cracker. The burner's input is connected to a hydrogen storage tank, which stores hydrogen separated from the hydrogen-nitrogen mixture. The hydrogen is then distributed to the burner and another branch via a second regulating valve, providing a constant flow of hydrogen to the burner and reducing variations in the valve's opening. Hydrogen from the other branch is fed into the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell via a third regulating valve, providing a constant total flow of hydrogen to both. The third regulating valve is used to distribute the hydrogen, thereby controlling the output power of the fuel cell hybrid power supply system.

2. The fuel cell hybrid energy supply system according to claim 1, characterized in that, It also includes a pressure reducing valve located between the first multi-stream heat exchanger and the buffer tank, the pressure reducing valve being used to reduce the pressure of the vaporized ammonia entering the buffer tank.

3. The fuel cell hybrid energy supply system according to claim 1, characterized in that, It also includes a water pump and an air-cooled heat exchanger. The water pump is used to extract the cylinder liner water and cooling water output from the first multi-stream heat exchanger and input them to the corresponding ammonia-hydrogen internal combustion engine and hydrogen fuel cell through the air-cooled heat exchanger, so as to provide power for the circulation loop of the cylinder liner water and cooling water.

4. A range efficiency control method, applied to the fuel cell hybrid power supply system according to any one of claims 1-3, characterized in that, include: Based on the total amount of hydrogen entering the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell, determine the power-efficiency output characteristic diagram of the fuel cell hybrid energy supply system; Based on the preset lower limit of the power generation efficiency of the fuel cell hybrid power supply system and the corresponding output power in the power-efficiency output characteristic diagram, the output power in the power-efficiency output characteristic diagram is divided into multiple intervals, including a first output power interval, a second output power interval, and a third output power interval. The value in the first output power interval is less than the value in the second output power interval, and the value in the second output power interval is less than the value in the third output power interval. The first output power range and the third output power range are defined as the operating range of the fuel cell hybrid power supply system. By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is located within the operating range under the total amount of hydrogen input.

5. The interval efficiency control method according to claim 4, characterized in that, By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is located within the operating range under the total hydrogen intake, including: The power of the load is compared with each range, and the target output power of the fuel cell hybrid power supply system is determined based on the comparison results. The target output power is located within the operating range. By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid power supply system is made equal to the target output power.

6. The interval efficiency control method according to claim 5, characterized in that, The load power is compared with each range, and the target output power of the fuel cell hybrid power supply system is determined based on the comparison results, including: When the power of the load falls within the operating range, the target output power is equal to the power of the load; When the power of the load is greater than the maximum value in the third output power range, the target output power is equal to the maximum value; When the power of the load is less than the minimum value in the first output power range, the target output power is equal to the minimum value; When the power of the load is within the second output power range, the target output power is equal to the maximum value in the first output power range.

7. The interval efficiency control method according to claim 6, characterized in that, Also includes: Determine the difference between the power of the load and the target output power; The battery does not operate when the power of the load is equal to the target output power; When the power of the load is greater than the target output power, the difference in electrical energy is supplemented by the battery. When the power of the load is less than the target output power, the excess electrical energy corresponding to the difference is stored in the battery.

8. The interval efficiency control method according to claim 7, characterized in that, Also includes: When the power of the load is greater than the target output power, the SOC of the battery is compared with a first preset threshold. If the SOC of the battery is less than the first preset threshold, the preset lower limit of power generation efficiency is reduced, thereby increasing the range of the working range. If the SOC of the battery is greater than or equal to the first preset threshold, then the battery will be used to replenish the electrical energy corresponding to the difference.

9. The interval efficiency control method according to claim 7, characterized in that, Also includes: When the power of the load is less than the target output power, the SOC of the battery is compared with a second preset threshold. If the SOC of the battery is greater than the second preset threshold, the fuel cell hybrid power supply system stops working and the battery supplies power to the load. If the SOC of the battery is less than or equal to the second preset threshold, the excess electrical energy corresponding to the difference is stored in the battery.

10. The interval efficiency control method according to claim 4, characterized in that, The greater the total amount of hydrogen introduced, the higher the preset lower limit of power generation efficiency, and the wider the operating range of the fuel cell hybrid power supply system.

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