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

Abstract

The invention provides a fuel cell hybrid power supply system and an interval efficiency regulation and control method thereof, the system adopts a two-stage constant feeding regulation and control mode, two energy storage devices are arranged to store ammonia energy and hydrogen energy, an interval efficiency regulation and control strategy is set, and the SOC health degree of a storage battery is considered according to the regulation and control strategy. Compared with a traditional control mode and control strategy of real-time online feeding regulation and control and limiting of the valve opening degree to reduce fuel consumption, the control mode can effectively reduce the influence of external disturbance on real-time fluctuation of the feeding amount and on the catalytic cracker and the influence of real-time regulation and control of multiple valves on a combustor and a power generation device; the robustness of the power generation system is improved; meanwhile, the provided regulation and control strategy can effectively improve the power generation efficiency of the whole system in the hybrid system with the V-shaped output characteristic, the capacity of a power battery and the charging and discharging peak power are reduced, and the demand quantity of ammonia and the economic cost are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power devices, and in particular to a fuel cell hybrid power supply system and an interval efficiency control method thereof. Background Art

[0002] In the actual application of engineering, loads will have high fluctuation frequency and large fluctuation amplitude in actual engineering scenarios. Therefore, there are certain challenges in the demand for power devices to solve the above load characteristics: the power device needs to have high load output power, a wide range of variable output power, fast load response speed, easy to carry, store and transport fuel, 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 power generation efficiency and pollution-free emissions and have high application potential. At the same time, compared with hydrogen, ammonia is easy to store and transport, and no carbon emissions are generated during the preparation of hydrogen, and it has good environmental performance. Therefore, by constructing an ammonia hydrogen-internal combustion engine-fuel cell hybrid power generation system, the advantages of the above components can be well coupled, and the waste heat resources of the components can be fully utilized, thereby improving the overall performance of the hybrid power generation system.

[0003] As a traditional power equipment, the output efficiency of the internal combustion engine gradually increases with the increase of output power; while the efficiency of the proton exchange membrane fuel cell gradually decreases with the increase of output power. In the ammonia hydrogen-internal combustion engine-fuel cell hybrid power generation system, the control parameters are generally to adjust the distribution ratio valve and the total amount of hydrogen input to the internal combustion engine and the fuel cell. When the output power is small, the power output component of the hybrid power generation system is mainly the proton exchange membrane fuel cell. As the output power increases, the output proportion of the fuel cell decreases, and 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, when the output power is small, the output efficiency of the hybrid power generation system decreases with the increase of output power; when the output power is large, the output of the hybrid power generation system is mainly 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 are close to the output characteristics of the internal combustion engine, and the output efficiency increases with the increase of output power. Therefore, the output power and output efficiency characteristics of the hybrid power generation system present a "V"-shaped characteristic curve relationship.

[0004] However, in the actual application environment with frequent load fluctuations, the traditional real-time online feeding control strategy may lead to unstable input of a specific hybrid power generation system equipped with a hydrogen production module and a burner. When encountering uncontrollable disturbances or sudden failures, it poses a major challenge to the robustness of the hybrid power generation system. When the output power is relatively large in the actual scenario, if only the opening degree of the distribution valve is restricted to reduce the power output, it is easy for the hybrid power generation system to operate in a lower output efficiency range, resulting in a decline in the working performance of the hybrid power generation system. In addition, due to the restricted opening degree of the valve, the maximum output power of the hybrid power generation system is also restricted, which will lead to an increase in the charge and discharge peak power of the battery under high load operating conditions, thus increasing the battery cost. Summary of the Invention

[0005] The present invention provides a fuel cell hybrid power supply system and an interval efficiency control method thereof, aiming to solve the problems in the prior art that the control strategy of the fuel cell hybrid energy supply system causes unstable system input, low power generation efficiency, and increased charge and discharge peak power of the battery, and to achieve stable system input, improve the power generation efficiency of the hybrid power generation system, and reduce the charge and discharge peak power of the storage battery while maintaining high efficiency.

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

[0007] An ammonia-hydrogen internal combustion engine and a hydrogen fuel cell, used for generating and providing electric energy;

[0008] A storage battery, connected to the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell, and the storage battery is used for storing and providing electric energy;

[0009] An ammonia storage tank, in which liquid ammonia is stored, and the liquid ammonia provides energy for the fuel cell hybrid energy supply system;

[0010] A first multi-stream heat exchanger, used for preliminarily preheating and gasifying the liquid ammonia into ammonia gas by using the jacket water of the ammonia-hydrogen internal combustion engine and the cooling water of the hydrogen fuel cell;

[0011] A second multi-stream heat exchanger, used for reheating the ammonia gas by using the hydrogen-nitrogen mixed gas output by the catalytic cracker and the tail gas of the ammonia-hydrogen internal combustion engine;

[0012] A catalytic cracker, used for decomposing the reheated ammonia gas into the hydrogen-nitrogen mixed gas;

[0013] A burner, used for providing heat for the catalysis of the catalytic cracker;

[0014] A separator, used for separating hydrogen from the hydrogen-nitrogen mixed gas output by 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 gasified ammonia and input the ammonia into the ammonia-hydrogen internal combustion engine and the second multi-stream heat exchanger through a first regulating and distributing valve to provide a constant flow of ammonia for the catalytic cracker;

[0016] The input end of the burner is connected to a hydrogen storage tank, which is used to store the hydrogen separated from the hydrogen-nitrogen mixture and distribute the hydrogen to the burner and another branch through a second regulating and distributing valve to provide a constant flow of hydrogen for the burner, reducing the opening change of the second regulating and distributing valve; The hydrogen in the other branch is input into the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell through a third regulating and distributing valve to provide a constant total flow of hydrogen for the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell, and the third regulating and distributing valve is adjusted to distribute the hydrogen to control the output power of the fuel cell hybrid energy supply system.

[0017] A fuel cell hybrid energy supply system according to the present invention further includes a pressure reducing valve located between the first multi-stream heat exchanger and the buffer tank, and the pressure reducing valve is used to reduce the pressure of the gasified ammonia entering the buffer tank.

[0018] A fuel cell hybrid energy supply system according to the present invention further includes a water pump and an air-cooled heat exchanger. The water pump is used to pump the jacket water and cooling water output by 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 to provide power for the circulation loop of the jacket water and cooling water.

[0019] The present invention also provides an interval efficiency regulation method applied to any one of the above fuel cell hybrid energy supply systems, including:

[0020] Determine the power-efficiency output characteristic diagram of the fuel cell hybrid energy supply system according to the total hydrogen intake of the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell;

[0021] According to the output power corresponding to the preset lower limit of the power generation efficiency of the fuel cell hybrid energy supply system in the power-efficiency output characteristic diagram, divide the output power in the power-efficiency output characteristic diagram 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] Take the first output power interval and the third output power interval as the working intervals of the fuel cell hybrid energy supply system;

[0023] By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid energy supply system under the total hydrogen intake is made to be within the operating range.

[0024] According to an interval efficiency regulation method provided by the present invention, by adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid energy supply system under the total hydrogen intake is made to be within the operating range, including:

[0025] Compare the power of the load with each interval, and determine the target output power of the fuel cell hybrid energy supply system according to the comparison result, and the target output power is within the operating range;

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

[0027] According to an interval efficiency regulation method provided by the present invention, comparing the power of the load with each interval, and determining the target output power of the fuel cell hybrid energy supply system according to the comparison result, includes:

[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 interval, 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 interval, the target output power is equal to the minimum value;

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

[0032] According to an interval efficiency regulation method provided by the present invention, it further includes:

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

[0034] When the power of the load is equal to the target output power, the storage battery does not work;

[0035] When the power of the load is greater than the target output power, make up the electric energy corresponding to the difference through the storage battery;

[0036] When the power of the load is less than the target output power, store the excess electric energy corresponding to the difference through the storage battery.

[0037] An interval efficiency regulation method provided by the present invention further includes:

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

[0039] If the SOC of the storage battery is less than the first preset threshold, lower the preset lower limit of the power generation efficiency and increase the range of the working interval;

[0040] If the SOC of the storage battery is greater than or equal to the first preset threshold, make up the electric energy corresponding to the difference through the storage battery.

[0041] An interval efficiency regulation method provided by the present invention further includes:

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

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

[0044] If the SOC of the storage battery is less than or equal to the second preset threshold, store the redundant electric energy corresponding to the difference through the storage battery.

[0045] For an interval efficiency regulation method provided by the present invention, the greater the total hydrogen intake, the greater the preset lower limit of the power generation efficiency, and the greater the range of the working interval of the fuel cell hybrid energy supply system.

[0046] A fuel cell hybrid power supply system and its interval efficiency regulation method provided by the present invention preliminarily preheat and gasify ammonia by using the cylinder jacket water of the internal combustion engine and the cooling water of the fuel cell through a multi-stream heat exchanger. At the same time, use the hydrogen-nitrogen mixture and the exhaust gas of the internal combustion engine to preheat ammonia again. Finally, use a hydrogen burner to preheat the ammonia gas to a relatively high temperature and then enter the catalytic cracker. At the same time, adopt a two-stage constant feeding regulation method, set two energy storage devices to store ammonia energy and hydrogen energy, and by setting the total amount of hydrogen entering the internal combustion engine and the fuel cell in the system to a constant value, adjust the distribution valve to distribute hydrogen, so as to realize the output control of the system. Compared with the traditional hybrid power generation system with real-time feeding regulation, it can effectively improve the robustness and stability of the whole system, effectively improve the power generation efficiency of the hybrid power generation system, and at the same time reduce the charging and discharging peak power and the storage capacity of the storage battery. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the attached drawings required for use in the description of the embodiments or the prior art. Obviously, the attached drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other attached drawings can also be obtained based on these attached drawings.

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

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

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

[0051] Figure 4 is a schematic flow diagram of an interval efficiency regulation method provided by the present invention;

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

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the attached drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0054] The following combines Figure 1 to describe a fuel cell hybrid power supply system of the present invention, including:

[0055] An ammonia-hydrogen internal combustion engine 17 and a hydrogen fuel cell 18, used to generate electric energy and provide electric energy for the entire system;

[0056] A storage battery 23, connected to the ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18. The storage battery 23 is used to store and provide electric energy;

[0057] An ammonia storage tank 1, in which liquid ammonia is stored. The liquid ammonia provides energy for the fuel cell hybrid power supply system;

[0058] A first multi-stream heat exchanger 2, used to utilize the jacket water of the ammonia-hydrogen internal combustion engine 17 and the cooling water of the hydrogen fuel cell 18 to preliminarily preheat the liquid ammonia and vaporize it into ammonia gas;

[0059] The second multi-stream heat exchanger 8 is used to re-preheat the ammonia gas by using the hydrogen-nitrogen mixed gas output by the catalytic cracker 10 and the tail gas of the ammonia-hydrogen internal combustion engine;

[0060] The catalytic cracker 10 is used to decompose the pre-reheated ammonia gas into the hydrogen-nitrogen mixed gas;

[0061] The burner 12 is used to provide heat for the catalysis of the catalytic cracker 10;

[0062] The separator 15 is used to separate hydrogen from the hydrogen-nitrogen mixed gas output by the second multi-stream heat exchanger 8;

[0063] The output end of the first multi-stream heat exchanger 2 is connected with a buffer tank 5. The buffer tank 5 is used to store the gasified ammonia gas and input the ammonia gas into the ammonia-hydrogen internal combustion engine 17 and the second multi-stream heat exchanger 8 through the first regulating and distributing valve 6 to provide ammonia gas with a constant flow rate for the catalytic cracker 10;

[0064] The input end of the burner 12 is connected with a hydrogen storage tank 13. The hydrogen storage tank 13 is used to store the hydrogen separated from the hydrogen-nitrogen mixed gas and distribute the hydrogen to the burner 12 and another branch through the second regulating and distributing valve 14 to provide the burner 12 with a constant flow rate of hydrogen and reduce the opening change of the second regulating and distributing valve 14; The hydrogen in the other branch is input into the ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18 through the third regulating and distributing valve 16 to provide a constant total flow rate of hydrogen for the ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18, and the third regulating and distributing valve 16 is adjusted to distribute the hydrogen to 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 the catalyst in the catalytic cracker, thereby reducing the cost of the whole system and improving the robustness of the whole system, this system and its control method are designed.

[0066] The ammonia is preliminarily preheated and vaporized by using the cylinder jacket water of the internal combustion engine and the cooling water of the fuel cell through a multi-stream heat exchanger. At the same time, the ammonia is reheated by using the hydrogen-nitrogen mixture gas and the exhaust gas of the internal combustion engine. Finally, the ammonia gas temperature is preheated to a relatively high temperature by using a hydrogen burner and then enters the catalytic cracker. At the same time, a buffer tank and a hydrogen storage tank are respectively arranged before the first multi-stream heat exchanger and the burner. The buffer tank is used to store the vaporized ammonia and provide a constant flow of ammonia for the catalytic cracker, reducing the pressure of the ammonia directly entering the internal combustion engine and the heat exchanger, and better matching the input of ammonia with the output demand of the system. The hydrogen storage tank is used to store the hydrogen gas after gas separation, which can maintain a constant value of the hydrogen gas entering the burner branch. At the same time, it can also be used for the startup of the system and to reduce the opening change of the hydrogen gas regulating valve of the hydrogen storage tank above the gas separator. By setting the total amount of hydrogen gas entering the internal combustion engine and the fuel cell in the system to a constant value and adjusting the distribution valve to distribute the hydrogen gas, the output control of the system is realized.

[0067] The first regulating and distributing valve 6 is an ammonia regulating and distributing valve, which distributes ammonia so that one path of the ammonia gas leads to the internal combustion engine and the other path leads to the catalytic cracker. The internal combustion engine exhaust gas treatment device 9 is used to remove the nitrogen oxides generated in the internal combustion engine exhaust gas. The catalytic cracker 10 is used to decompose ammonia gas into hydrogen gas to provide fuel for the fuel cell, the internal combustion engine and the burner. It also includes a device for exchanging heat with the internal combustion engine exhaust gas to recover part of the heat of the internal combustion engine exhaust gas. The burner 12 provides heat for the catalytic device to make the catalytic process proceed smoothly. The second regulating and distributing valve 14 is a hydrogen inlet regulating and distributing valve for the hydrogen storage tank, which is used to distribute part of the hydrogen gas required for combustion to the hydrogen storage tank and then to the burner. The separator 15 is used to separate nitrogen gas, reducing the nitrogen gas distributed to the combustion device and the power device, thereby reducing the generated nitrogen oxides and improving the energy conversion efficiency of the system. The third regulating and distributing valve 16 is a hydrogen inlet distributing regulating valve for the power device, which is used to distribute hydrogen gas to the internal combustion engine and the fuel cell. The ammonia-hydrogen internal combustion engine 17 and the hydrogen fuel cell 18 are the main power devices of the system. The generated current passes through the internal combustion engine output current converter 19 and the fuel cell output current converter 21 and then is integrated by the circuit combining device 20 to provide power for the heavy-duty equipment 24. When the power is insufficient or excessive, it enters the storage battery 23 through the battery current converter 22 for replenishment or absorption.

[0068] After the liquid ammonia is vaporized by heat exchange in the first multi-stream heat exchanger, it enters the buffer tank. There are two pipelines leading out of the buffer tank, which are directly connected to the internal combustion engine and the ammonia catalytic cracker respectively. After catalytic cracking, the prepared hydrogen is divided into two pipelines: one leads to the hydrogen storage tank and then to the burner to provide fuel for the burner; the other leads to the power device. The pipeline leading to the power device is further divided into two: one leads to the internal combustion engine to provide fuel for the internal combustion engine; and the other leads to the fuel cell to provide fuel for the fuel cell. The ammonia input amount into the internal combustion engine is input proportionally according to the hydrogen input amount of the internal combustion engine. The fuel required for the burner to supplement heat is input in real time according to the system demand.

[0069] As Figure 2 shown, through testing, it is found that under the condition of the same total hydrogen input amount, as the hydrogen input distribution ratio of the fuel cell increases, the output power of the system decreases, and one hydrogen input distribution ratio corresponds to the output power of one system. As the distribution ratio increases, 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 input amount is relatively large, within a certain range of the distribution ratio, as the distribution ratio increases, the output of the hybrid power generation system increases because the internal combustion engine will reach full load.

[0070] As Figure 3 shown, through testing, it is found that while maintaining a certain total hydrogen input amount, the relationship between the output efficiency - output power of the hybrid system shows a "V"-shaped curve. When the output power is relatively low, at this time the output of the hybrid power generation system is mainly from the fuel cell. As the output power increases, the output proportion of the fuel cell with a higher output efficiency decreases, and the output proportion of the internal combustion engine increases. At this time, the output efficiency of the hybrid power generation system decreases. When the output power is relatively large, the output of the hybrid power generation system is mainly from the internal combustion engine, and the output efficiency of the internal combustion engine increases with the increase of the output power, and the output efficiency of the hybrid power generation system also increases with the increase of the output power. Therefore, within a certain range, the output efficiency of the hybrid system decreases with the increase of the output power; and when the output power exceeds this range, the output efficiency increases with the increase of the output power, and the relationship between the output efficiency - output power of the hybrid system shows a "V"-shaped curve.

[0071] In this embodiment, a multi-stream heat exchanger is used to preliminarily preheat and vaporize ammonia with the cylinder jacket water of the internal combustion engine and the cooling water of the fuel cell. At the same time, the hydrogen-nitrogen mixture and the exhaust gas of the internal combustion engine are used to preheat ammonia again. Finally, a hydrogen burner is used to preheat the ammonia gas to a relatively high temperature and then enter the catalytic cracker. At the same time, a two-stage constant-feed control method is adopted, and two energy storage devices are set to store ammonia energy and hydrogen energy. By setting the total amount of hydrogen entering the internal combustion engine and the fuel cell in the system to a constant value and adjusting the distribution valve to distribute hydrogen, the output control of the system is realized. Compared with the traditional hybrid power generation system with real-time feed control, the robustness and stability of the whole system can be effectively improved, the power generation efficiency of the hybrid power generation system can be effectively improved, and at the same time, the charging and discharging peak power and storage capacity of the storage battery can be reduced.

[0072] Based on the above embodiment, a pressure reducing valve 3 is further included in this embodiment. The pressure reducing valve 3 is located between the first multi-stream heat exchanger 2 and the buffer tank 5, and the pressure reducing valve 3 is used to reduce the pressure of the vaporized ammonia entering the buffer tank 5, so as to ensure the safety of the buffer tank.

[0073] Based on the above embodiment, a water pump and an air-cooled heat exchanger 11 are further included in this embodiment. The water pump is used to pump the cylinder jacket water and the cooling water output by the first multi-stream heat exchanger 2, and then input them into the corresponding ammonia-hydrogen internal combustion engine 17 and hydrogen fuel cell 18 through the air-cooled heat exchanger 11, so as to provide power for the circulation loop of the cylinder jacket water and the cooling water and overcome the pressure drop during the water circulation. The air-cooled heat exchanger 11 is a heat exchange device used to reduce the excess temperature of the cylinder jacket water of the internal combustion engine and the cooling water of the fuel cell to the set temperature.

[0074] The water pump includes a cooling water pump 4 and a cylinder jacket water pump 7. The cooling water pump 4 provides enough lift for the fuel cell cooling water, so as to ensure that the water in the pipeline can complete the circulation smoothly. The cylinder jacket water pump 7 is used to provide enough lift for the cylinder jacket water of the internal combustion engine, so as to ensure that the water in the pipeline can complete the circulation smoothly.

[0075] As Figure 4 shown, this embodiment provides an interval efficiency control method, which is applied to the fuel cell hybrid energy supply system in any of the above embodiments, including:

[0076] According to the total hydrogen intake of 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] According to the output power corresponding to the preset lower limit of the power generation efficiency of the fuel cell hybrid energy supply system 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 interval and the third output power interval are used as the working intervals of the fuel cell hybrid energy supply system;

[0079] By adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid energy supply system under the total hydrogen intake is made to be within the working interval.

[0080] As Figure 5 shown, before the hybrid power generation system works, set the lower limit of the power generation efficiency of the hybrid power generation system, and draw an isoefficiency line of the lower limit efficiency on the power-efficiency output characteristic diagram corresponding to the set total hydrogen intake. It intersects at point 1' at a lower power and at point 2 at a higher power. At the same time, set the minimum output power point of the output characteristic as point 1 and the maximum output power point of the output characteristic as point 2'. The hybrid power generation system realizes power output within a certain range at this total hydrogen intake by adjusting the hydrogen distribution ratio entering the fuel cell.

[0081] The first output power interval is from point 1 to point 1', the second output power interval is from point 1' to point 2, and the third output power interval is from point 2 to point 2'. The first output power interval and the third output power interval are used as the working intervals of the fuel cell hybrid energy supply system. Power output within this working interval is realized by adjusting the hydrogen distribution ratio entering the fuel cell.

[0082] In this embodiment, by controlling the total hydrogen intake entering the internal combustion engine and the fuel cell to be a constant value, and by adjusting the hydrogen distribution ratio entering the fuel cell, power output within a certain range is realized under a constant hydrogen intake. Compared with the constant hydrogen intake regulation strategy with a monotonic output characteristic, it can effectively improve the power generation efficiency of the hybrid power generation system, reduce the charge and discharge peak power of the storage battery and the required battery capacity, and reduce the total ammonia amount and the ammonia storage tank capacity, and 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 embodiment, in this embodiment, by adjusting the hydrogen distribution ratio entering the hydrogen fuel cell, the output power of the fuel cell hybrid energy supply system under the total hydrogen intake is made to be within the working interval, including:

[0084] Compare the power of the load with each interval, and determine the target output power of the fuel cell hybrid energy supply system according to the comparison result. The target output power is within the working interval;

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

[0086] Based on the above embodiments, in this embodiment, comparing the power of the load with each interval and determining the target output power of the fuel cell hybrid energy supply system according to the comparison result includes:

[0087] When the power of the load falls within the working interval, 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 interval, 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 interval, the target output power is equal to the minimum value;

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

[0091] As Figure 5 shown, when the load power is less than the output power corresponding to point 1, the system output is output 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 at this time; when the load power is between point 1' and point 2, the system output power is output according to point 1', and the battery supplements the insufficient power at this time; 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 at this time; when the load is greater than point 2', the system output power is output according to point 2', and the battery supplements the insufficient power at this time.

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

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

[0094] When the power of the load is equal to the target output power, the battery does not work;

[0095] When the power of the load is greater than the target output power, make up the electric energy corresponding to the difference through the battery;

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

[0097] This embodiment aims to solve the problem in the constant hydrogen supply regulation strategy that restricting the opening degree of the distribution valve results in a decrease in the output power of the hybrid power generation system and ultimately leads to an excessive charge and discharge power of the storage battery. The interval efficiency regulation strategy can effectively solve this problem. That is, within a certain efficiency interval, the maximum output power of the hybrid power generation system remains unchanged, and the power difference below the efficiency interval can be kept within a small range, so that the peak charge and discharge power of the storage battery remains unchanged. This strategy can also effectively reduce the total output of the hybrid power generation system, improve the working efficiency of the hybrid power generation system, reduce the ammonia consumption and thus reduce the ammonia storage tank capacity, while reducing the capacity of the storage battery and the remaining power after the operation ends.

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

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

[0100] If the SOC of the storage battery is less than the first preset threshold, reduce the set lower limit of the preset power generation efficiency and increase the range of the working interval;

[0101] If the SOC of the storage battery is greater than or equal to the first preset threshold, make up the electric energy corresponding to the difference through the storage battery.

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

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

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

[0105] If the SOC of the storage battery is less than or equal to the second preset threshold, store the redundant electric energy corresponding to the difference through the storage battery.

[0106] Such as Figure 4As shown in the figure, the interval efficiency regulation strategy proposed in this embodiment is as follows: Before the hybrid power generation system operates, set the lower limit of the power generation efficiency of the hybrid power generation system, and set a certain total hydrogen intake during operation. According to the output characteristic diagram of the total hydrogen intake and the power output point corresponding to the lower limit of efficiency, determine the working interval and working state of the system. The hybrid power generation system realizes power output within a certain range at the total hydrogen intake by regulating the hydrogen distribution ratio entering the fuel cell.

[0107] When the load power falls within the working interval, the system output is equal to the load power, and the battery does not work at this time; when the load power is greater than the larger output interval, the system output is output according to the maximum output point. At this time, judge the SOC value of the battery: If the battery SOC is lower than the set threshold, the lower limit of the power generation efficiency set by the system can be modified again to increase the output range of the system; if the battery SOC is not lower than the set threshold, the battery supplements the insufficient power at this time; when the load power is less than the smaller output interval, judge the SOC value of the battery at this time: If the battery SOC exceeds the set threshold, the hybrid system stops working at this time, and only the battery outputs power; if the battery SOC does not exceed the set threshold, the system outputs power according to the minimum output power, and the battery stores the excess power; when the load power is between the smaller output interval and the larger output interval, judge the SOC value of the battery at this time: If the battery SOC is lower than the set threshold, the lower limit of the efficiency set by the system is modified again to increase the output range of the system; if the battery SOC is not lower than the set threshold, the system outputs power according to the maximum output power of the smaller output interval, and the battery supplements the insufficient power.

[0108] This embodiment sets an interval efficiency regulation strategy, which takes into account the SOC health of the battery according to the regulation strategy. Compared with the traditional real-time online feeding regulation and the control method and regulation strategy of restricting the valve opening to reduce fuel consumption, this control method can effectively reduce the real-time fluctuation of the feeding amount caused by external disturbances and thus the impact on the catalytic cracker, as well as the impact of real-time regulation of multiple valves on the burner and power generation device, improving the robustness of the power generation system; at the same time, the proposed regulation strategy can effectively improve the power generation efficiency of the overall system in a hybrid system with a "V"-type output characteristic, reduce the capacity of the power battery and the charge and discharge peak power, and reduce the demand for ammonia and economic costs.

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

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

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements 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 to generate and provide electrical energy; A battery connected to the ammonia hydrogen internal combustion engine and the hydrogen fuel cell, the battery being used to store and provide electrical energy; An ammonia storage tank, wherein liquid ammonia is stored in the ammonia storage tank, and the liquid ammonia provides energy for the fuel cell hybrid energy supply system; A first multi-stream heat exchanger is used to preheat the liquid ammonia and gasify it into ammonia gas by using the jacket water of the ammonia-hydrogen internal combustion engine and the cooling water of the hydrogen fuel cell; A second multi-stream heat exchanger, used for re-preheating the ammonia gas by using the hydrogen-nitrogen mixed gas output by the catalytic cracker and the tail gas of the ammonia-hydrogen internal combustion engine; A catalytic cracker, used for decomposing the preheated ammonia into the hydrogen-nitrogen mixed gas; A burner for providing heat for the catalysis of the catalytic cracker; a separator, used for separating hydrogen from the hydrogen-nitrogen mixed gas 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 gasified ammonia and input the ammonia into the ammonia-hydrogen internal combustion engine and the second multi-stream heat exchanger through a first regulating distribution valve to provide a constant flow of ammonia for the catalytic cracker; The input end of the burner is connected to a hydrogen storage tank, which is used to store hydrogen separated from the hydrogen-nitrogen mixed gas, and distribute the hydrogen to the burner and another branch through a second regulating distribution valve, so as to provide a constant flow of hydrogen to the burner and reduce the opening change of the second regulating distribution valve; the hydrogen from the other branch is input to the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell through a third regulating distribution valve, so as to provide a constant total flow of hydrogen to the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell, and the third regulating distribution valve is adjusted to distribute the hydrogen to control the output power of the fuel cell hybrid energy supply system.

2. The fuel cell hybrid energy supply system according to claim 1, characterized in that: It also includes a pressure reducing valve, which is located between the first multi-stream heat exchanger and the buffer tank, and is used to reduce the pressure of the gasified ammonia gas 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 jacket water and cooling water output by 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 to provide power for the circulation loop of the cylinder jacket water and cooling water.

4. A method for regulating interval efficiency, applied to the fuel cell hybrid energy supply system according to any one of claims 1 to 3, characterized in that: include: Determine the power-efficiency output characteristic diagram of the fuel cell hybrid energy supply system according to the total amount of hydrogen intake of the ammonia-hydrogen internal combustion engine and the hydrogen fuel cell; According to the output power corresponding to the preset lower limit of the power generation efficiency of the fuel cell hybrid energy supply system in the power-efficiency output characteristic diagram, the output power in the power-efficiency output characteristic diagram is divided into a plurality of intervals, the intervals comprising 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; Using the first output power interval and the third output power interval as the working intervals of the fuel cell hybrid energy supply system; By regulating the distribution ratio of hydrogen entering the hydrogen fuel cell, the output power of the fuel cell hybrid energy supply system under the total amount of hydrogen input is within the working range.

5. The interval efficiency control method according to claim 4, characterized in that: By adjusting the distribution ratio of hydrogen entering the hydrogen fuel cell, the output power of the fuel cell hybrid energy supply system under the total amount of hydrogen input is within the working range, including: Comparing the power of the load with each interval, and determining the target output power and of the fuel cell hybrid energy supply system according to the comparison result, wherein the target output power is within the working interval; By adjusting the distribution ratio of hydrogen entering the hydrogen fuel cell, the output power of the fuel cell hybrid energy supply system is made equal to the target output power.

6. The interval efficiency control method according to claim 5, characterized in that: Comparing the power of the load with each interval, and determining the target output power of the fuel cell hybrid energy supply system according to the comparison result, including: When the power of the load falls within the working range, the target output power is equal to the power of the load; When the power of the load is greater than a maximum value in the third output power interval, 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 interval, the target output power is equal to the minimum value; When the power of the load is in the second output power interval, the target output power is equal to the maximum value in the first output power interval.

7. The interval efficiency control method according to claim 6, characterized in that: Also includes: determining a difference between the power of the load and the target output power; When the power of the load is equal to the target output power, the battery does not work; When the power of the load is greater than the target output power, the electric energy corresponding to the difference is supplemented by the storage battery; When the power of the load is less than the target output power, the excess electric 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, comparing the SOC of the battery with a first preset threshold; If the SOC of the battery is less than the first preset threshold, lowering the preset lower limit of power generation efficiency and increasing the range of the working range; If the SOC of the battery is greater than or equal to the first preset threshold, the electric energy corresponding to the difference is supplemented by the battery.

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, comparing the SOC of the battery with a second preset threshold; If the SOC of the battery is greater than the second preset threshold, the fuel cell hybrid energy 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, excess electric energy corresponding to the difference is stored in the battery.

10. The interval efficiency control method according to claim 1, characterized in that: The greater the total amount of hydrogen intake, the greater the preset lower limit of power generation efficiency, and the greater the range of the working range of the fuel cell hybrid energy supply system.

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