Inertia self-adaptive optimization control method for electric propulsion of hydrogen fuel cell ship

Abstract

The invention provides an inertia adaptive optimization control method for electric propulsion of a hydrogen fuel cell ship, and the method comprises the steps: building an equivalent output model of each power source during the steady-state operation of the hydrogen fuel cell ship, taking the equivalent model as a mixed potential function, and analyzing a system signal stability criterion; inertial parameters and damping parameters required by the system based on the mixed potential function are obtained by inputting ship working conditions and hydrogen fuel cell working conditions; power output is realized by performing frequency division control on demanded power in the system; and an energy storage unit in the system is controlled by a virtual direct current machine, so that the inertia requirement of the system is realized, and the dynamic characteristic of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical fields of ship and marine engineering and new energy application, and specifically relates to an inertial adaptive optimization control method for a hydrogen fuel cell ship electric propulsion ship. Background Art

[0002] Hydrogen and hydrogen-based fuels are a good solution for carbon reduction and decarbonization in the shipping industry. With the maturity of fuel application technology and the improvement of supporting facilities, its application scope will gradually expand. Hydrogen-powered ships are usually used in shipping scenarios such as lakes, inland rivers, and offshore, mainly including passenger ships, ferries, inland cargo ships, tugboats and other types. The development of large hydrogen-powered ships such as offshore engineering ships, offshore roll-on / roll-off ships, and super yachts is the current trend, and submarines using hydrogen fuel cell power systems also have good prospects. However, the output characteristics of hydrogen fuel cells are soft and the dynamic performance is poor. When the ship's operating conditions fluctuate, it cannot effectively provide power support to the busbar. Therefore, it is necessary to connect it in parallel with the energy storage device, and use the rapid response of the energy storage device to solve the problem of violent fluctuations in the output characteristics of the proton exchange membrane fuel cell caused by power fluctuations. It can effectively extend the life of the proton exchange membrane fuel cell and save the cost of inspection and maintenance.

[0003] During the process of ship sailing and docking, the ship needs to adjust its attitude many times, and the ship power system needs to change its working conditions many times. When the ship is sailing normally, the ship's electric propulsion ship reflects the constant power load characteristics. When the ship's working conditions are switched, the constant power load is a negative impedance device for the source side, so the power fluctuation of the constant power load will affect the stability of the system. Summary of the invention

[0004] In order to suppress bus voltage fluctuations, it is considered to use supercapacitors to provide and absorb the transient power required by the system. However, there is no existing solution for reference for the selection of supercapacitor capacity. Therefore, the present invention uses a hybrid potential function method to quantitatively analyze the range of supercapacitor values ​​to ensure that the system can operate normally when the load fluctuates. The present invention also adopts a control strategy based on a virtual DC motor for the ship battery to ensure the stability of the bus voltage, while providing the system with necessary inertial support. And considering that fixed damping and inertia coefficients will cause bus voltage offset in steady state, inertial damping parameters are adaptively adjusted to adapt to the optimal control of the ship system in different situations. The control parameters are optimized through a hybrid potential function, and finally the stable operation of the hydrogen fuel cell ship is achieved. The present invention is aimed at the problem of inertial adaptive optimization design of hydrogen fuel cell ships, and a more effective control strategy is obtained through a judgment method based on a hybrid potential function, which is of great value for the long-term stable and reliable operation of ships.

[0005] The present invention establishes an equivalent output model of each power source when a hydrogen fuel cell ship is in steady-state operation, and uses the equivalent model as a mixed potential function to analyze the large signal stability criterion of the system, thereby obtaining the required inertia and damping parameters of the system based on the mixed potential function method. The power output is achieved by frequency-dividing the power demand in the system. Then, the inertia requirement of the system is achieved by using a virtual DC machine to control the energy storage unit in the system, thereby improving the dynamic characteristics of the system.

[0006] The technical solution specifically adopted by the present invention to solve the technical problem is:

[0007] An adaptive optimization control method for the inertia of a hydrogen fuel cell ship electric propulsion ship is disclosed. The method establishes an equivalent output model of each power source when the hydrogen fuel cell ship is in steady-state operation, uses the equivalent model as a mixed potential function to analyze the stability criterion of the system signal, and obtains the required inertia parameters and damping parameters of the system based on the mixed potential function by inputting the ship working condition and the hydrogen fuel cell working condition; realizes power output by performing frequency division control on the power demand in the system; and realizes the inertia demand of the system by adopting virtual DC machine control on the energy storage unit in the system, so as to improve the dynamic characteristics of the system.

[0008] Furthermore, the mixed potential function determines the stability based on equations (1), (2), (3), and (4):

[0009]

[0010] μ1=min(L -1 / 2 P ii L -1 / 2 ),μ2=min(C -1 / 2 P uu C -1 / 2 )(2)

[0011] μ1+μ2>0(3)

[0012]

[0013] In formula (1), L represents the diagonal matrix composed of inductors in the circuit, C represents the diagonal matrix composed of capacitors in the circuit, and P i represents a current derivative of the mixed potential function P, P u represents the secondary voltage derivative of the mixed potential function P, P * (i,u) represents the transformed form of the general mixed potential function P(i,u), where i and u in the mixed potential function P(i,u) represent the independent inductor current and capacitor voltage components in the system respectively;

[0014] P in formula (2) ii It means that the mixed potential function P is subjected to two current derivatives, Puu It means that the voltage partial derivative of the mixed potential function P is performed twice, μ1 represents the minimum eigenvalue of the diagonal matrix of the current potential, and μ2 represents the minimum eigenvalue of the diagonal matrix of the voltage potential;

[0015] In formula (4), x1~x n Represents the voltage and current components in the mixed potential function.

[0016] Furthermore, the hydrogen fuel cell ship model adopted includes a hydrogen fuel cell, two batteries, a super capacitor, and two permanent magnet synchronous motors, which together constitute an electric propulsion ship of a hydrogen fuel cell ship; when the ship operating conditions change, the working state of the propulsion device is required to change. First, the power that the ship power system needs to provide or absorb is determined, and the working state of the hydrogen fuel cell at this time is determined; the power fluctuation ΔP in the system is processed by frequency division, and the super capacitor responds to the high-frequency part of the power fluctuation, and the hydrogen fuel cell and the battery jointly respond to the medium and low-frequency part of ΔP; the ship state and the hydrogen fuel cell state are comprehensively considered, and the inertia and impedance parameters obtained by the mixed potential function of the system are controlled by the battery converter; the control strategy of the virtual DC machine is adopted, so that the battery provides the virtual inertia and virtual damping required in the system; the voltage and current double loop is adopted, and the mathematical model of the outer loop is the virtual inertia link corresponding to equations (5) and (6); in equation (5), u dcref is the voltage loop voltage reference value, u s is the output voltage value of the voltage loop, k ip is the current loop PI parameter proportional coefficient, k ii is the current loop PI integral coefficient, i oref is the current loop current reference, i o is the sampled inductor current; k in formula (6) vp is the voltage loop PI parameter proportional coefficient, k vi is the voltage loop PI integral coefficient, u dc is the voltage loop sampling capacitor voltage; divide the divided ΔP by ω n ΔT is obtained, corresponding to equation (7), and the relationship between inertia, damping and ΔT is obtained according to the mechanical swing equation (8) of the DC motor, where T mv is the virtual DC motor mechanical torque; T ev is the virtual DC motor electromagnetic torque; J vir is the virtual inertia coefficient; D vir is the virtual damping coefficient; ω rv is the virtual DC motor rotor angular frequency; ω n is the voltage angular frequency of the common coupling point of the virtual DC motor; then, according to the armature circuit equations (9) and (10) of the DC motor, the compensation value of the current loop is obtained to realize the damping inertia control of the battery; where: U and E ais the terminal voltage and induced electromotive force; R a and I vir is the armature resistance and armature current; C T is the torque coefficient; φ is the flux variable; ω is the DC motor speed:

[0017]

[0018] i oref =k vp (u dcref -u dc )+k vi ∫(u dcref -u dc )dt(6)

[0019]

[0020]

[0021] E a =C T φω(9)

[0022] E a =U+I vir R a (10).

[0023] Furthermore, different controls are used to improve the output external characteristics of each power source in the system, the inertia parameters of the hydrogen fuel cell system are obtained, and the selected control parameters are optimized according to the mixed potential function:

[0024] Monitor the ship's operating conditions and the operating conditions of hydrogen fuel cells. According to different operating conditions, conduct hybrid potential function modeling for the ship's electric propulsion system, conduct stability analysis on the hybrid potential function model, obtain the current stability margin of the system, and obtain the inertia and damping required by the system, providing specific inertia and damping for the next step of the inertia adaptive method.

[0025] The power fluctuation in the system is processed by frequency division; the supercapacitor responds to the high frequency part of the power fluctuation, the battery responds to the medium frequency part of the power fluctuation, and the hydrogen fuel cell responds to the low frequency part of the power fluctuation; through virtual inertia and virtual damping, through the control of the virtual DC machine, the power fluctuation, through the rotor swing equation of the DC motor and the armature loop equation of the DC motor, the current loop compensation current is obtained to realize the virtual inertia control of the system;

[0026] On the basis of voltage-current dual-loop control, virtual inertia control is added to the voltage loop to obtain compensated virtual current, which is injected into the inner current loop and modulated to obtain pulse width modulation. The generated high-frequency chopping signal is used to control the on and off of the power switch in the bidirectional DC-DC power converter.

[0027] Furthermore, the hydrogen fuel cell ship electric propulsion ship includes: a proton exchange membrane fuel cell power generation unit, a battery unit, a super capacitor unit, two ship DC electric propulsion units, a constant power load unit and a resistive load; the proton exchange membrane fuel cell power generation unit is connected to the DC bus through an isolated boost full-bridge converter; the battery unit and the super capacitor unit are connected to the DC bus through a bidirectional DC-DC converter, and the battery unit adopts a virtual DC machine control to provide the required inertia for the system.

[0028] Furthermore, the proton exchange membrane fuel cell power generation unit is composed of a PEMFC cell and a single-phase full-bridge boost power converter cascaded, and the output side of the single-phase full-bridge boost power converter is connected to the DC bus; the battery unit is composed of a battery and a bidirectional DC-DC power converter cascaded, and the output side of the bidirectional DC-DC power converter is connected to the bus; the supercapacitor unit is composed of a supercapacitor and a bidirectional DC-DC power converter cascaded, and the output side of the bidirectional DC-DC power converter is connected to the bus; the two ship DC propulsion power units each include a bidirectional inverter, a permanent magnet synchronous motor and a propeller, the bidirectional inverter is cascaded with the permanent magnet synchronous motor, the mechanical shaft of the permanent magnet synchronous motor is directly connected to the propeller shaft, and the input side of the bidirectional inverter is connected to the DC bus; the constant power load unit is composed of two forms: the first form is composed of a DC power converter and a DC load cascaded, and the second form is composed of an inverter and an AC load cascaded, and both forms of constant power load units are connected to the DC bus through the input side of the power converter; the resistance load unit is directly connected to the DC bus as a resistance load.

[0029] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the above-mentioned method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship are implemented.

[0030] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship.

[0031] Compared with the prior art, the present invention and its preferred solution can effectively optimize the volume weight of the power source under the premise of determining the power output load, and at the same time optimize the control strategy of the power source to improve the economy and stability of the hydrogen storage electric propulsion device.

[0032] (1) The present invention is based on a hybrid potential function method. The hybrid potential function is a fast and effective method for determining the stability margin boundary conditions and stability margin of a constant power load system. Compared with the general Lyapunov stability judgment method, the present invention utilizes the ship operating conditions and the operating status of the hydrogen fuel cell, and adopts the hybrid potential function method to obtain the specific values ​​of the virtual inertia and damping required by the system when the power fluctuates. When the ship operating conditions change and the operating status of the hydrogen fuel cell changes, the system can quickly provide the required inertia through the battery, reduce the bus voltage fluctuation when the load fluctuates, and improve the stability and reliability of the hydrogen fuel cell ship electric propulsion ship.

[0033] (2) The present invention is an adaptive inertia matching method. Compared with the traditional inertia control method with fixed parameters, the adaptive inertia parameters are more flexible. The range of each control parameter in the system is determined by the method of mixed potential function, and the stability margin of the system is determined. Compared with other large signal analysis methods, the mixed potential function has a natural advantage in the analysis of constant power loads. It can obtain the system stability margin faster, with less calculation and more process implementation. Thereby achieving large-scale stability of the system and providing guarantee for the safe operation of the system.

[0034] (3) The present invention is aimed at changes in ship operating conditions and hydrogen fuel cell operation conditions. Since ships need electric propulsion to adjust their attitude in real time during operation, the output power requirements of ship power systems are different. From the perspective of impedance, changes in load power will cause negative impedance in the system, causing voltage oscillations on the bus, which will harm hydrogen fuel cells and other marine equipment. The present invention adopts a virtual DC machine control strategy, which can effectively improve the inertia and damping levels in the system. When the load power fluctuates, the bus voltage fluctuations can be suppressed because the output port characteristics of the converter are equivalent to a DC motor. This is an active oscillation suppression method.

[0035] (4) The present invention is essentially a virtual inertia adaptive regulation technology, that is, the port output characteristics of the converter are changed through a control method, so that there is no need to add additional inertial equipment and no additional power loss is generated in the system. The transient stability problem of the system can be fundamentally solved. At the same time, the circuit structure and control strategy of this method do not change with the change of the operating conditions or the operating state of the hydrogen fuel cell, and it has the characteristics of flexibility, low consumption and high efficiency.

[0036] (5) The present invention adopts frequency division control for the power fluctuation in the system, with the supercapacitor responding to the high-frequency power fluctuation in the system, the battery responding to the medium-frequency power fluctuation in the system, and the hydrogen fuel cell responding to the low-frequency power fluctuation in the system. Since the output characteristics of the hydrogen fuel cell are soft and the dynamic performance is poor, when dealing with a sudden increase or decrease in load power, it cannot absorb the power in the system well, otherwise the performance of the proton exchange membrane will be seriously affected, thereby affecting the life of the hydrogen fuel cell, and posing a major threat to the safety and economy of the system. The present invention adopts three power sources, considering their different physical properties, and performs frequency division control on the power fluctuation, which can effectively reduce the output power fluctuation of the hydrogen fuel cell and ensure the safety and economy of the system.

[0037] (6) The present invention is designed for high-proportion hydrogen fuel cell electric propulsion ships with a large range of load power variations and high randomness. By optimizing the system through a mixed potential function, the system volume can be effectively reduced. At the same time, the stability and reliability of electric propulsion ships with hydrogen fuel cells as the main propulsion energy are improved, providing a technical basis for hydrogen fuel cells to replace diesel engines, which is of great significance for achieving my country's "dual carbon" goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0039] Figure 1 This is a structural diagram of a hydrogen fuel cell ship electric propulsion ship according to an embodiment of the present invention;

[0040] Figure 2 This is a control block diagram of a virtual DC machine according to an embodiment of the present invention;

[0041] Figure 3 This is a block diagram of the control principle of a hydrogen fuel cell ship electric propulsion ship according to an embodiment of the present invention;

[0042] Figure 4 This is an equivalent diagram of hybrid potential function analysis of a ship electric propulsion system according to an embodiment of the present invention;

[0043] Figure 5 This is a diagram of the virtual inertial control equivalent transformation structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows:

[0045] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0046] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. 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 "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0047] like Figure 1 As shown, it is a schematic diagram of the modular structure of a typical hydrogen fuel cell ship electric propulsion ship, which adopts a single bus DC power supply structure, including a proton exchange membrane fuel cell PEMFC power generation unit 1, a battery unit 2, a supercapacitor unit 3, a ship DC electric propulsion unit 4 and 5, a constant power load unit 6 and a resistance load 7. Among them, the PEMFC power generation unit 1 is composed of a PEMFC battery and a single-phase full-bridge boost power converter cascaded, and the output side of the single-phase full-bridge boost power converter is connected to the DC bus; the battery unit 2 is composed of a battery and a bidirectional DC-DC power converter cascaded, and the output side of the bidirectional DC-DC power converter is connected to the bus; the supercapacitor unit 3 is composed of a supercapacitor and a bidirectional DC-DC power converter cascaded, and the output side of the bidirectional DC-DC power converter is connected to the bus; the ship DC propulsion power units 4 and 5 each include a bidirectional inverter, a permanent magnet synchronous motor and a propeller, the bidirectional inverter is cascaded with the permanent magnet synchronous motor, the mechanical shaft of the permanent magnet synchronous motor is directly connected to the propeller shaft, and the input side of the bidirectional inverter is connected to the DC bus; the constant power load unit is composed of two forms: the first form is composed of a DC power converter and a DC load cascaded, and the second form is composed of an inverter and an AC load cascaded, and both forms of constant power load units are connected to the DC bus through the input side of the power converter; the resistance load unit is directly connected to the DC bus as a resistance load.

[0048] The proportion of ship DC electric propulsion units in the total ship load is high. There is a corresponding relationship between the ship operating conditions and the electric propulsion load characteristics. When the ship operating conditions are switched, the negative impedance characteristics presented by the sudden change of the load are likely to cause high-frequency instability of the ship's hydrogen storage DC electric propulsion ship; the working state of the hydrogen fuel cell is stable, and the operating state of the hydrogen storage unit is limited. Assume that there are m ship operating conditions and n hydrogen storage unit operating states. Model the different operating conditions of the system, obtain the system mixed potential function modeling, and conduct large signal stability margin analysis on the system.

[0049] To this end, an embodiment of the present invention provides a method for adaptively optimizing the inertia control of a hydrogen fuel cell ship electric propulsion ship, which is achieved by controlling a bidirectional DC-DC power converter, such as Figure 3 As shown, the following steps are included:

[0050] When the ship encounters different working conditions and needs to accelerate, decelerate, stop, reverse and other operations, the system requires the motor to provide different powers, which will cause bus voltage fluctuations. List m working conditions of hydrogen fuel cells and n working conditions of ships. Mathematically model the battery controller, using voltage and current dual-loop control, with the outer loop being a virtual inertia link. Analyze the equivalent model of each power source, use the mixed potential function to analyze the stability of the system, and obtain the inertia and damping required for the virtual inertial control of the system, such as Figure 4 , Figure 5 shown.

[0051] The stability of the mixed potential function is determined by equations (1), (2), (3) and (4).

[0052]

[0053] μ1=min(L -1 / 2 P ii L -1 / 2 ),μ2=min(C -1 / 2 P uu C -1 / 2 )(2)

[0054] μ1+μ2>0(3)

[0055]

[0056] In formula (1), L represents the diagonal matrix composed of inductors in the circuit, C represents the diagonal matrix composed of capacitors in the circuit, and P i represents a current derivative of the mixed potential function P, P u represents the secondary voltage derivative of the mixed potential function P, P * (i,u) represents the transformed form of the general mixed potential function P(i,u), where i and u in the mixed potential function P(i,u) represent the independent inductor current and capacitor voltage components in the system respectively;

[0057] P in formula (2) ii It means that the mixed potential function P is subjected to two current derivatives, P uu It means that the voltage partial derivative of the mixed potential function P is performed twice, μ1 represents the minimum eigenvalue of the diagonal matrix of the current potential, and μ2 represents the minimum eigenvalue of the diagonal matrix of the voltage potential;

[0058] In formula (4), x1~x n Represents the voltage and current components in the mixed potential function.

[0059] Establish a hydrogen fuel cell ship model and determine the converter topologies and control strategies used in the system;

[0060] The established hydrogen fuel cell ship model includes a hydrogen fuel cell, two batteries, a super capacitor, and two permanent magnet synchronous motors, which together form an electric propulsion ship of a hydrogen fuel cell ship. When the ship's operating conditions change, the working state of the propulsion device is required to change. First, the power that the ship's power system needs to provide or absorb is determined, and the working state of the hydrogen fuel cell at this time is determined. The power fluctuation ΔP in the system is processed by frequency division, and the super capacitor responds to the high-frequency part of the power fluctuation, and the hydrogen fuel cell and the battery jointly respond to the medium and low-frequency part of ΔP; the ship state and the hydrogen fuel cell state are comprehensively considered, and the inertia and impedance parameters obtained by the mixed potential function of the system are controlled by the battery converter; the control strategy of the virtual DC machine is adopted, so that the battery provides the virtual inertia and virtual damping required in the system; the voltage and current double loop is adopted, and the outer loop is the mathematical model of the virtual inertia link corresponding to equations (5) and (6); in equation (5), u dcref is the voltage loop voltage reference value, u s is the output voltage value of the voltage loop, k ip is the current loop PI parameter proportional coefficient, k ii is the current loop PI integral coefficient, i oref is the current loop current reference, i o is the sampled inductor current; k in formula (6) vp is the voltage loop PI parameter proportional coefficient, k vi is the voltage loop PI integral coefficient, u dc is the voltage loop sampling capacitor voltage; divide the divided ΔP by ω n ΔT is obtained, corresponding to equation (7), and the relationship between inertia, damping and ΔT is obtained according to the mechanical swing equation (8) of the DC motor, where T mv is the virtual DC motor mechanical torque; T ev is the virtual DC motor electromagnetic torque; J vir is the virtual inertia coefficient; D vir is the virtual damping coefficient; ω rv is the virtual DC motor rotor angular frequency; ω n is the voltage angular frequency of the common coupling point of the virtual DC motor; then, according to the armature circuit equations (9) and (10) of the DC motor, the compensation value of the current loop is obtained to realize the damping inertia control of the battery; where: U and E a is the terminal voltage and induced electromotive force; R a and I vir is the armature resistance and armature current; C T is the torque coefficient; φ is the flux variable; ω is the DC motor speed:

[0061]

[0062] i oref =kvp (u dcref -u dc )+k vi ∫(u dcref -u dc )dt(6)

[0063]

[0064] E a =C T φω(9)

[0065] E a =U+I vir R a (10)

[0066] Among them, inertia adaptive control is to obtain the equivalent inertia size of the system according to the ship operating conditions and the working state of the hydrogen fuel cell unit, and realize the adaptive adjustment of different inertia and impedance of the system under different working conditions by changing the inertia and impedance parameters of the external power loop.

[0067] The mixed potential function determination is to adjust the system parameters, and use the mixed potential function determination method to make the system work within the large signal stability margin. The mixed potential function determination equation of hydrogen fuel cell electric propulsion ship is listed. Due to the conservative problem of the mixed potential function and the difficulty in proving that the local minimum is the equilibrium point of the system, it is necessary to add a criterion on the basis of the original theory of the mixed potential function to ensure the correct use of the criterion.

[0068] Parameter optimization is to further optimize the system parameters based on the parameter range obtained by the mixed potential function, and adjust the parameters of the battery using the virtual synchronous machine control strategy to make the entire system have better performance.

[0069] Different controls are used to improve the output external characteristics of each power source of the system, and the inertia parameters of the hydrogen fuel cell system are obtained. The selected control parameters are optimized according to the mixed potential function method, including the following steps:

[0070] ① Monitor the ship operating conditions and hydrogen fuel cell operating conditions, and according to different operating conditions, conduct hybrid potential function modeling for the ship's electric propulsion ship, conduct stability analysis on the hybrid potential function model, obtain the current stability margin of the system, and obtain the inertia and damping required by the system, providing specific inertia and damping for the next step of the inertia adaptive method.

[0071] ② Perform frequency division processing on the power fluctuation in the system. The supercapacitor responds to the high frequency part of the power fluctuation, the battery responds to the medium frequency part of the power fluctuation, and the hydrogen fuel cell responds to the low frequency part of the power fluctuation. The virtual inertia, virtual damping and other parameters obtained in step ① are controlled by the virtual DC machine, and the current loop compensation current is obtained from the power fluctuation through the rotor swing equation of the DC motor and the armature loop equation of the DC motor to realize the virtual inertia control of the system.

[0072] ③ Modulation signal generation: On the basis of the general voltage and current dual-loop control, virtual inertia control is added to the voltage loop to obtain a compensated virtual current, which is injected into the inner loop current loop and modulated to obtain pulse width modulation. The generated high-frequency chopping signal is used to control the on and off of the power switch in the bidirectional DC-DC power converter. It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with general skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprising" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the described object changes, the relative position relationship may also change accordingly.

[0073] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

[0074] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of a hydrogen fuel cell ship electric propulsion ship inertial adaptive optimization control method under the inspiration of this patent. All equal changes and modifications made according to the scope of the patent application of the present invention should be covered by this patent.

Claims

1. A method for adaptive inertial optimization control of a hydrogen fuel cell ship electric propulsion ship, characterized in that: By establishing the equivalent output model of each power source during steady-state operation of hydrogen fuel cell ships, the equivalent model is used as a hybrid potential function to analyze the system signal stability criterion, and the required inertia parameters and damping parameters of the system based on the hybrid potential function are obtained by inputting the ship operating conditions and hydrogen fuel cell operating conditions; the power output is achieved by frequency-dividing the required power in the system; and the inertia requirement of the system is achieved by using virtual DC machine control for the energy storage unit in the system to improve the dynamic characteristics of the system.

2. The method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship according to claim 1 is characterized by: The mixed potential function determines the stability based on equations (1), (2), (3), and (4): μ1=min(L -1 / 2 P ii L -1 / 2 ),μ2=min(C -1 / 2 P uu C -1 / 2 )(2) μ1+μ2>0(3) In formula (1), L represents the diagonal matrix composed of inductors in the circuit, C represents the diagonal matrix composed of capacitors in the circuit, and P i represents a current derivative of the mixed potential function P, P u represents the secondary voltage derivative of the mixed potential function P, P * (i,u) represents the transformed form of the general mixed potential function P(i,u), where i and u in the mixed potential function P(i,u) represent the independent inductor current and capacitor voltage components in the system respectively; P in formula (2) ii It means that the mixed potential function P is subjected to two current derivatives, P uu It means that the voltage partial derivative of the mixed potential function P is performed twice, μ1 represents the minimum eigenvalue of the diagonal matrix of the current potential, and μ2 represents the minimum eigenvalue of the diagonal matrix of the voltage potential; In formula (4), x1~x n Represents the voltage and current components in the mixed potential function.

3. The method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship according to claim 2 is characterized by: The hydrogen fuel cell ship model adopted includes a hydrogen fuel cell, two batteries, a super capacitor, and two permanent magnet synchronous motors, which together form an electric propulsion ship of a hydrogen fuel cell ship. When the ship's operating conditions change, the working state of the propulsion device is required to change. First, the power that the ship's power system needs to provide or absorb is determined, and the working state of the hydrogen fuel cell at this time is determined. The power fluctuation ΔP in the system is processed by frequency division, and the super capacitor responds to the high-frequency part of the power fluctuation, and the hydrogen fuel cell and the battery jointly respond to the medium and low-frequency part of ΔP. The ship state and the hydrogen fuel cell state are comprehensively considered, and the inertia and impedance parameters obtained by the mixed potential function of the system are controlled by the battery converter. The control strategy of the virtual DC machine is adopted to enable the battery to provide the virtual inertia and virtual damping required in the system. The voltage and current double loop is adopted, and the mathematical model of the outer loop is the virtual inertia link corresponding to equations (5) and (6); in equation (5), u dcref is the voltage loop voltage reference value, u s is the output voltage value of the voltage loop, k ip is the current loop PI parameter proportional coefficient, k ii is the current loop PI integral coefficient, i oref is the current loop current reference, i o is the sampled inductor current; k in formula (6) vp is the voltage loop PI parameter proportional coefficient, k vi is the voltage loop PI integral coefficient, u dc is the voltage loop sampling capacitor voltage; divide the divided ΔP by ω n ΔT is obtained, corresponding to equation (7), and the relationship between inertia, damping and ΔT is obtained according to the mechanical swing equation (8) of the DC motor, where T mv is the virtual DC motor mechanical torque; T ev is the virtual DC motor electromagnetic torque; J vir is the virtual inertia coefficient; D vir is the virtual damping coefficient; ω rv is the virtual DC motor rotor angular frequency; ω n is the voltage angular frequency of the common coupling point of the virtual DC motor; then, according to the armature circuit equations (9) and (10) of the DC motor, the compensation value of the current loop is obtained to realize the damping inertia control of the battery; where: U and E a is the terminal voltage and induced electromotive force; R a and I vir is the armature resistance and armature current; C T is the torque coefficient; φ is the flux variable; ω is the DC motor speed: and oref =k vp (in dcref -in dc )+k vi ∫(in dcref -in dc )dt(6) HAVE BEEN a =C T φω(9) E a =U+I vir R a (10)。 4. The method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship according to claim 3 is characterized by: Different controls are used to improve the output characteristics of each power source in the system, and the inertia parameters of the hydrogen fuel cell system are obtained. The selected control parameters are optimized according to the mixed potential function: Monitor the ship's operating conditions and the operating conditions of hydrogen fuel cells. According to different operating conditions, conduct hybrid potential function modeling for the ship's electric propulsion system, conduct stability analysis on the hybrid potential function model, obtain the current stability margin of the system, and obtain the inertia and damping required by the system, providing specific inertia and damping for the next step of the inertia adaptive method. Perform frequency division on the power fluctuation in the system; The supercapacitor responds to the high-frequency part of the power fluctuation, the battery responds to the medium-frequency part of the power fluctuation, and the hydrogen fuel cell responds to the low-frequency part of the power fluctuation; through virtual inertia and virtual damping, through the control of the virtual DC machine, the power fluctuation, through the rotor swing equation of the DC motor and the armature loop equation of the DC motor, the current loop compensation current is obtained to realize the virtual inertia control of the system; On the basis of voltage-current dual-loop control, virtual inertia control is added to the voltage loop to obtain compensated virtual current, which is injected into the inner current loop and modulated to obtain pulse width modulation. The generated high-frequency chopping signal is used to control the on and off of the power switch in the bidirectional DC-DC power converter.

5. The method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship according to claim 1, characterized in that: The hydrogen fuel cell ship electric propulsion ship includes: a proton exchange membrane fuel cell power generation unit, a battery unit, a super capacitor unit, two ship DC power propulsion units, a constant power load unit and a resistive load; the proton exchange membrane fuel cell power generation unit is connected to the DC bus through an isolated boost full-bridge converter; the battery unit and the super capacitor unit are connected to the DC bus through a bidirectional DC-DC converter, and the battery unit adopts a virtual DC machine control to provide the required inertia for the system.

6. The method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship according to claim 5 is characterized by: The proton exchange membrane fuel cell power generation unit is composed of a PEMFC battery and a single-phase full-bridge boost power converter in cascade, and the output side of the single-phase full-bridge boost power converter is connected to the DC bus; the battery unit is composed of a battery and a bidirectional DC-DC power converter in cascade, and the output side of the bidirectional DC-DC power converter is connected to the bus; the supercapacitor unit is composed of a supercapacitor and a bidirectional DC-DC power converter in cascade, and the output side of the bidirectional DC-DC power converter is connected to the bus; the two ship DC propulsion power units each include a bidirectional inverter, a permanent magnet synchronous motor and a propeller, the bidirectional inverter is cascaded with the permanent magnet synchronous motor, the mechanical shaft of the permanent magnet synchronous motor is directly connected to the propeller shaft, and the input side of the bidirectional inverter is connected to the DC bus; the constant power load unit is composed of two forms: the first form is composed of a DC power converter and a DC load in cascade, and the second form is composed of an inverter and an AC load in cascade, and both forms of constant power load units are connected to the DC bus through the input side of the power converter; the resistance load unit is directly connected to the DC bus as a resistance load.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the inertial adaptive optimization control method for a hydrogen fuel cell ship electric propulsion ship as described in any one of claims 1 to 6 are implemented.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for inertial adaptive optimization control of a hydrogen fuel cell ship electric propulsion ship as described in any one of claims 1 to 6 are implemented.

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