Hybrid degree-based power coordination control method for hydrogen energy unmanned aerial vehicle hybrid power system

Abstract

The invention belongs to the technical field of hydrogen energy unmanned aerial vehicle hybrid power system operation control, discloses a hydrogen energy unmanned aerial vehicle hybrid power system power coordination control method based on the mixing degree, and effectively achieves reasonable distribution and flow optimization of energy power. By designing a mixing degree based on a linear function, the method can adaptively adjust the output ratio of a power battery to a fuel battery, and ensures that the system is properly discharged when the state of charge is too high and is properly charged when the state of charge is too low, so that the state of charge is prevented from exceeding the limit, and the stable operation of the system is maintained; therefore, continuous and reliable operation of the hybrid power system of the unmanned aerial vehicle is ensured; by monitoring the load power and the charge state of the power battery in real time, a power coordination control strategy of the hybrid power system of the unmanned aerial vehicle is designed, power distribution in the hybrid power system is automatically adjusted, and stable operation can be achieved under various working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of operation control of a hydrogen energy UAV hybrid power system, and in particular to a power coordination control method of a hydrogen energy UAV hybrid power system based on a hybrid degree. Background Art

[0002] Energy conservation and emission reduction have become the core research topics in the field of transportation, and the aviation industry is no exception. The contribution of the global aviation industry to greenhouse gas emissions cannot be ignored. The industry's carbon dioxide emissions account for 2.1% of the world's total emissions, while non-carbon dioxide greenhouse gas emissions account for as much as 4.9%. It is predicted that by 2050, the global aviation industry's carbon dioxide emissions are expected to be 2.7 times the current level. Faced with this challenge, the international aviation industry has set an ambitious goal of achieving zero growth in greenhouse gas emissions from 2020 and plans to reduce carbon dioxide emissions by 7.8 billion tons in the next 20 years. In this environment, governments and scientific research institutions are actively exploring clean energy solutions that can replace traditional fossil fuels. Solar energy and hydrogen energy, due to their huge resource potential, high energy conversion efficiency, environmental friendliness and zero emissions, have attracted widespread attention from around the world and become the focus of clean energy transformation.

[0003] With the advancement of clean energy technology, the design and application of electric aircraft have gradually become a reality. These aircraft use solar cells or hydrogen fuel cells as power systems, which not only reduces dependence on fossil fuels, but also improves energy efficiency. Compared with traditional drones, hydrogen-powered drones have obvious advantages in terms of operating efficiency, environmental impact, and endurance. As a branch of the electric-hydrogen microgrid, the hydrogen-powered drone hybrid system is crucial for its continuous and stable aerial operation capabilities. Therefore, it is particularly important to formulate an effective power coordination control strategy. "Alam M, Kumar K, Verma S, et al. Renewable sources based DC microgrid using hydrogen energy storage: Modelling and experimental analysis [J]. Sustainable Energy Technologies and Assessments, 2020, 42: 100840." and "Ipsakis D, Voutetakis S, Seferlis P, et al. Power management strategies for a stand-alone power system using renewable energy sources and hydrogen storage [J]. International Journal of Hydrogen Energy, 2009, 34: 7081-7095." By dividing the system operation mode, power coordination control based on the state machine was carried out with the goal of achieving system energy balance. However, there is still room for improvement in ensuring the continuity of system operation and the recovery of the energy storage charge state."Kyriakarakos G,Dounis AI,Arvanitis KG,et al.A fuzzy logic energy management system for polygeneration microgrids[J].Renewable Energy,2012,41:315-327.","Zhang F,Thanapalan K,Procter A,et al.Power management control foroff-grid solar hydrogen production and utilisation system[J].InternationalJournal of Hydrogen Energy,2013,38:4334-4341." and "Zhang Xue, Pei Wei, Mei Chunxiao,et al.Fuzzy power allocation strategy and coordination control method for isolated DC microgrid with electric / hydrogen composite energy storage system[J].High Voltage Technology,2022,48(03):958-968." A fuzzy logic controller was further proposed to achieve performance improvement by optimizing the power flow within the system without too many system state settings. However, the controller has complexity problems in fuzzy rule design.

[0004] In summary, the present invention takes the hydrogen energy UAV hybrid power system and its power electronic converter as the research object, and proposes a device-system hierarchical power coordination control scheme which is highly universal, simple in structure and easy to implement in engineering. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a hierarchical power coordination control method for a hydrogen energy UAV hybrid power system based on hybrid degree.

[0006] The technical solution adopted by the present invention is as follows: a hierarchical power coordination control method for a hydrogen energy UAV hybrid power system based on hybrid degree, comprising the following steps:

[0007] S1: Carry out equivalent mathematical modeling of power batteries and fuel cells and analyze the working characteristics of the equipment;

[0008] S2: Customize the control scheme and plan the operation mode for the power battery, fuel cell and its corresponding converter according to their operation characteristics;

[0009] S3: Coordinate the operation of the power battery, fuel cell and load at the hybrid system level; design the hybrid degree based on the linear function and adaptively adjust the output ratio of the power battery and fuel cell;

[0010] S4: By real-time monitoring of load power and the state of charge of the power battery, a power coordination control strategy for the hybrid power system of the UAV is designed to automatically adjust the power distribution within the hybrid power system to ensure stable operation under various working conditions.

[0011] The S2 is specifically as follows:

[0012] The core task of the fuel cell converter is to provide continuous main power for the hybrid system while ensuring that the hybrid system will not be overloaded; the fuel cell converter adopts a single-loop control strategy with constant current, and its reference current is expressed as:

[0013]

[0014] Among them, i ref_FC is the fuel cell converter reference current, P FC_ref is the fuel cell converter reference power, V FC is the fuel cell voltage;

[0015] The power battery is used to maintain the stability of the bus voltage. The power battery converter adopts a dual closed-loop control strategy based on the constant voltage mode. When the output voltage of the power battery converter exceeds the preset value, the power battery converter locks the output voltage to keep it stable, while allowing the output current to be adjusted according to the load changes. The main advantage of dual-loop control is its excellent voltage stability, which can meet the needs under different load conditions. The reference voltage of the power battery converter is expressed as:

[0016] V refESU =V nom +K P (V nom -V bus )+K I (V nom -V bus )-i dc_ESU R vESU (2)

[0017] Among them, V refESU is the reference voltage of the power battery converter, V nom is the nominal voltage, V bus is the bus voltage, K P is the ratio, K I is the integral coefficient, i dc_ESU is the output current of the power battery converter, R vESU is the droop coefficient.

[0018] The mixing degree formula based on the linear function is as follows:

[0019] H=a·SoC+b (3)

[0020] Among them, a and b are adjustable parameters, SoC is the battery state of charge, and this function is used to make the fuel cell output a specific multiple of the system demand power, and the remaining power is provided or absorbed by the power battery to achieve the purpose of restoring the state of charge. It can be seen that this scheme significantly reduces the switching frequency of the working state and realizes the recovery of the battery state of charge by adaptively adjusting the value of the hybrid degree H.

[0021] The specific process of S4 is as follows:

[0022] First, define the simplified system working state, which can be expressed as:

[0023] P FC _ref=min{max{H·Pdemand,P FC _min},P FC _max} (4)

[0024] P demand is the system required power, P FC_min is the minimum output power of the fuel cell, P FC_max is the maximum output power of the fuel cell;

[0025] The reference power of the fuel cell is linked to the battery state of charge. When the state of charge is lower than the preset target value, the H value is set greater than 1 to prompt the power battery to charge; when the state of charge is higher than the preset target value, the H value is set less than 1 to prompt the system to discharge; when the state of charge reaches the preset target value, the H value is set to 1, which means that the power required by the system is now completely provided by the fuel cell.

[0026] The preset target value is 50%.

[0027] In this solution, when the state of charge is set to 0.5, the value of H is set to 1; when the state of charge is set to 0.8, the value of H is set to 0.4. Based on these settings, it can be calculated that the slope a of the linear function is -2 and the intercept b is 2.

[0028] The present invention provides a power coordination control method for a hydrogen energy UAV hybrid power system based on hybrid degree. Taking the hydrogen energy UAV hybrid power system and its power electronic converter as the research object, a device-system hierarchical power coordination control scheme with high universality, simple structure and easy implementation in engineering is proposed. First, the core components such as fuel cells and power batteries are equivalently modeled. On this basis, the control strategy and working mode are customized for the interface converters of these devices. Furthermore, at the system level, a power coordination control method based on hybrid degree is designed to coordinate the operation of each component, aiming to achieve a reasonable distribution of energy power, ensure the stability of the bus voltage and the adaptive recovery of the state of charge. For the hydrogen energy UAV hybrid power system and its power electronic converter, the present invention proposes a hierarchical power coordination control scheme with high universality, simple structure and easy implementation in engineering.

[0029] The beneficial effects of the present invention are as follows: the present invention proposes a power coordination control method for a hydrogen energy UAV hybrid power system based on a degree of mixing, which effectively realizes the reasonable distribution of energy power and flow optimization. By designing a degree of mixing based on a linear function, the present method can adaptively adjust the output ratio of the power battery and the fuel cell, ensuring that the hybrid power system is properly discharged when the state of charge is too high, and properly charged when the state of charge is too low, thereby preventing the state of charge from exceeding the limit and maintaining the stable operation of the system. In summary, the present method has the characteristics of simple structure, strong universality and easy engineering implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a typical structural diagram of the hydrogen energy UAV hybrid power system adopted by the present invention;

[0031] Figure 2 It is a diagram of the hierarchical energy management control scheme proposed by the present invention;

[0032] Figure 3 The following are the simulation results of Case 1; (a) is the power simulation result diagram; (b) is the schematic diagram of the Soc simulation result; (c) is the voltage simulation result diagram;

[0033] Figure 4 These are the simulation result diagrams of Case 2; (a) is the power simulation result diagram; (b) is the schematic diagram of the Soc simulation result; (c) is the voltage simulation result diagram.

[0034] Figure 5 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0038] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0039] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0040] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0041] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0042] The typical structure of the hydrogen energy UAV hybrid power system is as follows: Figure 1 The figure shows the schematic diagram of the hybrid power system in the UAV simulation model. The system consists of the following key components: power battery, fuel cell, propeller load and other loads, each of which is equipped with a corresponding interface converter. During system operation, the fuel cell serves as the main energy supply source, while the power battery serves as an auxiliary energy source to adjust the instantaneous fluctuations of system power.

[0043] Figure 2 The proposed power coordination control scheme is shown, which aims to optimize the energy distribution within the regulation system.

[0044] A device-system hierarchical control architecture was constructed to customize control schemes and plan operation modes based on the operating characteristics of each device and subsystem at the device level to achieve preliminary energy distribution;

[0045] The scheme consists of a device layer and a system layer, forming a nested structure. At the device layer, the corresponding control scheme is customized according to the operating characteristics of the converters of each device interface in the hybrid power system. The system layer is responsible for coordinating the work of the converters on the source, storage and load sides, optimizing the power distribution within the system, and ensuring the stability and reliability of power flow.

[0046] A power coordination control method for a hydrogen energy UAV hybrid power system based on hybrid degree includes the following steps:

[0047] S1: Carry out equivalent mathematical modeling of power batteries and fuel cells and analyze the working characteristics of the equipment;

[0048] S2: Customizing respective control schemes and planning operation modes for power batteries, fuel cells and corresponding interface converters according to their operation characteristics;

[0049] S3: Coordinate the operation of power batteries, fuel cells and loads; design a hybrid degree based on a linear function to adaptively adjust the output ratio of power batteries and fuel cells;

[0050] S4: By real-time monitoring of load power and the state of charge of the power battery, the designed UAV hybrid power system power coordination control strategy automatically adjusts the power distribution within the system to ensure stable operation under various working conditions;

[0051] Steps S1, S2, S3, and S4 are performed sequentially;

[0052] The process of equivalent mathematical modeling of fuel cells and power batteries and analyzing working characteristics is as follows:

[0053] The output voltage of the fuel cell is affected by many factors. Its output voltage changes with the change of current. The expression of the fuel cell terminal voltage is as follows:

[0054] V FC =E oc -V act -V ohm -V con (1)

[0055] Where U FC is the output voltage of the battery stack, E oc is the open circuit voltage, V act is the activation overvoltage, V ohm is the ohmic overvoltage, V con is the concentration difference overvoltage. Considering factors such as ambient temperature and gas pressure, the expression can be further expressed as follows according to the semi-empirical formula:

[0056]

[0057] In the formula, K C is the rated voltage constant, E0 is the electromotive force of the stack under standard atmospheric pressure, z is the amount of electron transfer, F is the Faraday constant, T is the Kelvin temperature of the stack, R is the gas constant, P H2 With P O2 are the inlet pressures of hydrogen and oxygen respectively, N is the number of battery cells, A is the Tafel slope, i FC , i0 and i Lare the output current, exchange current and limit current of the battery stack respectively, τ is the time constant of dynamic response, R ohm is the ohmic internal resistance of the battery stack, and B is the concentration constant

[0058] i0 and A can be further expressed as:

[0059]

[0060] Where z is the charge transfer coefficient, k is the Boltzmann constant, h is the Planck constant, ΔG is the change in the Gibbs free energy of the system, and P O and P H represent the oxygen and hydrogen pressures respectively.

[0061] P O and P H It can be expressed as the following formula:

[0062]

[0063] Where x represents the hydrogen content in the fuel provided, y represents the oxygen content in the air, and U fH , U fO Indicates the utilization rate of hydrogen and oxygen, P fuel Indicates the pressure of the supplied fuel, P air Indicates the pressure of the supplied air.

[0064] Furthermore, U fH , U fO It can be expressed as:

[0065]

[0066] Among them, β c represents the constant coefficient, U fO represents oxygen utilization rate, V fuel Indicates the hydrogen flow rate, V air Indicates air flow rate.

[0067] The calculation of the output voltage of the battery in the power battery RINT model is shown in formula (6);

[0068]

[0069] Where: V bat is the output voltage of the lithium battery; E0 is the voltage constant; K is the polarization constant; Q is the battery capacity; it is the actual power, which is equivalent to the integral of the current over time; i * is the output current after filtering; A is the exponential voltage; B is the exponential capacity; R is the internal resistance of the battery.

[0070] Further: the process of customizing respective control schemes and planning operation modes for power batteries and fuel cells according to the operation characteristics of the interface converters corresponding to them is as follows:

[0071] Fuel cell converter control scheme and planned operation mode: The core task of the fuel cell converter is to provide continuous main power for the hybrid system while ensuring that the system will not be overloaded. To achieve this goal, the fuel cell converter adopts a constant current single-loop control strategy, and its reference current can be expressed as:

[0072]

[0073] Among them, i ref_FC , P FC_ref 、V FC They are fuel cell converter reference current, fuel cell converter reference power, and fuel cell voltage respectively.

[0074] Power battery converter control scheme and planned operation mode: The power battery is used to maintain the stability of the bus voltage. Therefore, the power battery converter adopts a dual closed-loop control strategy based on the constant voltage mode. When the output voltage exceeds the preset value, the converter will lock the output voltage to keep it stable, while allowing the output current to adjust according to the load changes. The main advantage of dual-loop control is its excellent voltage stability, which can meet the needs under different load conditions. The reference voltage of the power battery converter can be expressed as:

[0075] V refESU =V nom +K P (V nom -V bus )+K I (V nom -V bus )-i dc_ESU R vESU (8)

[0076] Among them, V refESU 、V nom 、V bus , K P , K I 、i dc_ESU , R vESU They are the power battery converter reference voltage, nominal voltage, bus voltage, proportion, integral coefficient, power battery converter output current and droop coefficient respectively.

[0077] System level control:

[0078] By real-time monitoring of load power and the state of charge of the power battery, the designed UAV hybrid power system power coordination control strategy automatically adjusts the power distribution within the system to ensure stable operation under various working conditions. The process is as follows:

[0079] First, define the simplified system working state, which can be expressed as:

[0080] P FC_ref =min{max{H·P demand ,P FC_min},P FC_max} (9)

[0081] It can be seen that the scheme significantly reduces the switching frequency of the working state and realizes the recovery of the battery state of charge by adaptively adjusting the value of the mixing degree H. Specifically, the scheme links the reference power of the fuel cell with the battery state of charge. When the state of charge is low, the H value is set to be greater than 1 to prompt the system to charge; on the contrary, when the state of charge is high, the H value is set to be less than 1 to prompt the system to discharge. In this way, the charging and discharging process of the battery is effectively controlled. Only when the state of charge reaches the preset target value, the H value is set to 1, which means that the power required by the system is completely provided by the fuel cell at this time.

[0082] The representation of the mixing degree H adopts the form of a linear function, which effectively simplifies the parameter adjustment process. When selecting the coefficients to be determined, it is only necessary to determine the preset value of the battery state of charge and its corresponding H value. In this scheme, when the state of charge is set to 0.5, the value of H is set to 1; when the state of charge is set to 0.8, the value of H is set to 0.4. Based on these settings, it can be calculated that the slope a of the linear function is -2 and the intercept b is 2.

[0083] In order to verify the effectiveness of the present invention, simulation verification was carried out through MATLAB / Simulink software. In this system, a load of 50kW during take-off, a load of 20kW during cruising and landing, and other loads on the UAV totaling 10kW were considered.

[0084] (1) First verify the performance of the solution when the state of charge is low (20%):

[0085] Figure 3The detailed visualization of the simulation results under low state of charge conditions is shown, covering key performance indicators such as fuel cell power, power battery power, required power, state of charge, and bus voltage. The simulation results show that the proposed energy management scheme can enable the fuel cell to output its set maximum power in the time period from 0s to 10s. In the time period from 10s to 60s, the power required by the system is between the upper and lower limits of the power set by the fuel cell. By dynamically adjusting the value of the mixing degree H, the scheme can charge the power battery while supplying power to the load, causing the power battery's state of charge to gradually recover to a level of about 0.5, ensuring that the battery's peak shaving and valley filling function is effectively exerted. In addition, the fluctuation range of the bus voltage is effectively controlled within 10V, which helps to maintain the stability and reliability of the entire system.

[0086] (2) Then verify the performance of the solution at a higher state of charge (90%):

[0087] Figure 4 The simulation results at a high state of charge are shown, involving key parameters such as fuel cell power, power battery power, required power, state of charge, and bus voltage. The simulation data reveals that at a high state of charge, the power battery has sufficient remaining power. In this case, the fuel cell and the power battery can jointly supply power to meet the power required by the load, while achieving controlled discharge of the battery. When the power battery state of charge rises to about 0.5, the discharge process will gradually terminate, and the fuel cell will independently assume the power supply task, which helps maintain the battery's peak-shaving and valley-filling capabilities. Overall, the simulation results show that the fluctuation of the bus voltage is effectively limited to less than 10V, which helps maintain the stability of the entire system.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hierarchical power coordination control method for a hydrogen energy UAV hybrid power system based on hybrid degree, characterized in that: The following steps are involved: S1: Carry out equivalent mathematical modeling of power batteries and fuel cells and analyze the working characteristics of the equipment; S2: Customize the control scheme and plan the operation mode for the power battery, fuel cell and its corresponding converter according to their operation characteristics; S3: Coordinate the operation of the power battery, fuel cell and load at the hybrid system level; design the hybrid degree based on the linear function and adaptively adjust the output ratio of the power battery and fuel cell; S4: By real-time monitoring of load power and the state of charge of the power battery, a power coordination control strategy for the hybrid power system of the UAV is designed to automatically adjust the power distribution within the hybrid power system to ensure stable operation under various working conditions.

2. According to claim 1, a method for hierarchical power coordination control of a hydrogen energy UAV hybrid power system based on hybrid degree, characterized in that: The S2 is specifically as follows: The core task of the fuel cell converter is to provide continuous main power for the hybrid system while ensuring that the hybrid system will not be overloaded; the fuel cell converter adopts a single-loop control strategy with constant current, and its reference current is expressed as: Among them, i ref_FC is the fuel cell converter reference current, P FC_ref is the fuel cell converter reference power, V FC is the fuel cell voltage; The power battery is used to maintain the stability of the bus voltage. The power battery converter adopts a dual closed-loop control strategy based on the constant voltage mode. When the output voltage of the power battery converter exceeds the preset value, the power battery converter locks the output voltage to keep it stable, while allowing the output current to be adjusted according to the change of the load. The reference voltage of the power battery converter is expressed as: V refESU =V nom +K P (V nom -V bus )+K I (V nom -V bus )-i dc_ESU R vESU (2) Among them, V refESU is the reference voltage of the power battery converter, V nom is the nominal voltage, V bus is the bus voltage, K P is the ratio, K I is the integral coefficient, i dc_ESU is the output current of the power battery converter, R vESU is the droop coefficient.

3. The hierarchical power coordination control method of a hydrogen energy UAV hybrid power system based on hybrid degree according to claim 1 or 2 is characterized in that: The mixing degree formula based on the linear function is as follows: H=a·SoC+b (3) Where a and b are adjustable parameters, SoC is the battery state of charge. This function is used to make the fuel cell output a specific multiple of the system demand power, and the remaining power is provided or absorbed by the power battery to achieve the purpose of restoring the state of charge.

4. According to claim 1, a method for hierarchical power coordination control of a hydrogen energy UAV hybrid power system based on hybrid degree, characterized in that: The specific process of S4 is as follows: First, define the simplified system working state, which can be expressed as: P FC_ref =min{max{H·P demand ,P FC_min },P FC_max } (4) P demand is the system required power, P FC_min is the minimum output power of the fuel cell, P FC_max is the maximum output power of the fuel cell; The reference power of the fuel cell is linked to the battery state of charge. When the state of charge is lower than the preset target value, the H value is set greater than 1 to prompt the power battery to charge; when the state of charge is higher than the preset target value, the H value is set less than 1 to prompt the system to discharge; when the state of charge reaches the preset target value, the H value is set to 1, which means that the power required by the system is now completely provided by the fuel cell.

5. The hierarchical power coordination control method for a hydrogen energy UAV hybrid power system based on hybrid degree according to claim 4 is characterized in that: The preset target value is 50%.

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