A hydrogen storage coordinated control method and device considering the durability of a multi-stack fuel cell system

Abstract

The present invention discloses a hydrogen storage coordination control method and device that considers the durability of a multi-stack fuel cell system, and belongs to the field of multi-stack fuel cell system operation control technology. The method of the present invention realizes transient power balance and steady-state energy complementarity between fuel cells and batteries by introducing battery charge state recovery control and stack power real-time distribution strategy, suppresses system DC bus voltage fluctuations, and improves the overall performance of the multi-stack fuel cell system. The device includes: a single / bidirectional DC / DC converter unit, a power coordination control unit, and a power distribution unit. The device of the present invention takes into account the different powers borne by each fuel cell stack due to different aging degrees, and can be applied to a DC microgrid with multiple stacks in parallel. The device has a simple structure, high economy, and accurate power distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-stack fuel cell system operation control, and in particular, to a hydrogen storage coordination control method and device that takes into account the durability of the multi-stack fuel cell system. Background Art

[0002] Fuel cells are being studied and developed as a viable clean energy solution. Among them, proton exchange membrane fuel cells (PEMFC) have become a potential application hotspot due to their high efficiency, compact structure, good dynamic operation efficiency and low performance decay rate. They have been tested and commercially explored in automobiles and ships. Due to the limitations of technology and materials, single-stack high-power fuel cells have disadvantages such as high cost, rapid degradation of the stack, and inability to operate for a long time. The literature "A review of multi-stack and modular fuel cell systems: Interests, application areas and on-going research activities" proposes that when multi-stack fuel cell systems are put into operation in a coordinated manner, their system power level and overall efficiency can be greatly improved; therefore, multi-stack fuel cell systems (MFCS) are currently used. MFCS consists of multiple low-power FC systems instead of a high-power FC system, which allows MFCS to not only meet the problem of high power demand, but also makes the replacement of the stack more convenient, avoids the lack of durability of the stack, and enhances the stability of the system.

[0003] At present, the research on MFCS mainly focuses on optimizing a certain indicator in the system (such as efficiency, hydrogen consumption, etc.), and all of them are experimentally verified under the assumption that the fuel cell performance does not degrade and the fuel cell performance is exactly the same. In fact, when the fuel cell is operated for a long time, its performance will degrade significantly with the operating time. Related studies have shown that under actual working conditions, when the fuel cell is operated for a long time under conditions such as variable load, start-stop, idling and high load, its service life and performance will be significantly affected. Among them, the most influential are frequent variable load and start-stop conditions, accounting for 56.5% and 33% respectively. Therefore, it is an urgent problem to adopt an effective control strategy to suppress the aggravation of the aging of the stack and ensure the maximum long-term stable operation of the fuel cell.

[0004] In addition, for the stability of the fuel cell system, the battery SOC needs to be maintained in a normal range, and as the system continues to operate, the battery SOC will shift. Therefore, the present invention proposes a hydrogen storage coordination control method and device that considers the durability of a multi-stack fuel cell system to achieve coordinated operation of hydrogen storage in multiple fuel cell stacks. Summary of the invention

[0005] In view of the technical problems existing in the above-mentioned prior art, a hydrogen storage coordination control method and device taking into account the durability of a multi-stack fuel cell system are provided.

[0006] The technical means adopted by the present invention are as follows:

[0007] A hydrogen storage coordinated control method considering the durability of a multi-stack fuel cell system is applied to a DC / DC converter output controller and includes the following steps:

[0008] Step 1: Introduce the battery state of charge recovery control structure; by transmitting the battery state of charge and line information detected by the sensor to the controller, the reference power of the fuel cell is restored. P ref Designing to restore the battery state of charge of the battery;

[0009] Step 2: Introduce the power differential term of the battery , which is the dynamic adjustment power of the battery state of charge, and obtains the reference power expression of the fuel cell;

[0010] Step 3: Determine the size of the fuel cell output power; when the fuel cell output power is greater than the maximum power limit, control the battery to release electrical energy to relieve the pressure of fuel cell overload and maintain system power balance; when the fuel cell output power reaches the minimum power limit, control the battery to absorb electrical energy to increase the output power to maintain power balance;

[0011] Step 4: The rate of change of battery state of charge d SOC / d t Adjust the output power of the battery P B , by setting different battery output reference power P B_ref , dynamically change the reference value of the battery state of charge SOC ref value, causing the battery to discharge or absorb power.

[0012] Furthermore, in step 1, the fuel cell is operated according to a reference power P ref The expression of output power is:

[0013] ; (1)

[0014] in, P fc Indicates the base power value, that is, the load that the fuel cell should bear; P SOC Indicates the load that the fuel cell needs to bear in order to adjust the state of charge of the battery; P SOC include: and ;in, Indicates the regulated power of the battery state of charge, Represents the power differential term of the battery;

[0015] The battery state of charge regulates the power The expression is:

[0016] ; (2)

[0017] in, and Respectively represent the proportional and integral coefficients of the PI controller; Respectively represent the reference value and actual value of the battery state of charge; represents the Laplace operator.

[0018] Furthermore, in step 2, the power differential term of the battery is introduced As the dynamic adjustment power of the battery state of charge, the power differential term of the battery The expression is:

[0019] ; (3)

[0020] in, represents the power differential coefficient, Indicates the output power of the battery, and its relationship with the battery charge state is:

[0021] ; (4)

[0022] in, Indicates the initial state of charge; Indicates the output current of the battery; Indicates the rated output current of the battery; Indicates the rated capacity of the battery in ampere-hours; Indicates the rated capacity of the battery in watt-hours; Indicates the rated power of the battery; represents the output voltage of the battery, then:

[0023] ; (5)

[0024] in, K c =( U B I B_rate C B_rate ) / P B_rate ,when U B When is a constant, K c is a constant; then, the reference power expression of the fuel cell is:

[0025] ; (6)

[0026] In the formula, .

[0027] Furthermore, the battery outputs a reference power P B_ref The expression is:

[0028] ; (7)

[0029] in, P load Indicates load power; P fc_max and P fc_min Respectively represent the maximum and minimum output power allowed for fuel cell operation; P fc_High and P fc_Low Respectively represent the upper and lower limits of the output power of the fuel cell;

[0030] Find:

[0031] ; (8)

[0032] in, P B_ref Indicates the reference power of lithium battery. SOC 0 represents the initial SOC of the lithium battery. SOC ref Indicates the SOC reference value of lithium battery.

[0033] Furthermore, in the step 1, in order to restore the control structure, the problem of inconsistent fuel cell performance caused by long-term operation is considered, and a power adaptive allocation strategy based on the degree of degradation is introduced, and the degree of fuel cell degradation is characterized by the internal resistance increase rate and the exchange membrane degradation rate;

[0034] Fuel cells have special output characteristics of polarization, and the output voltage is expressed as:

[0035] ; (9)

[0036] in, E OC represents the open circuit voltage of the fuel cell; U FC-ref Indicates the output reference voltage of the battery stack, E loss It represents the potential loss required to overcome the reaction resistance, expressed as a quadratic function of the current; Indicates current fitting E loss The fitting coefficients in the process; represents the fuel cell output current;

[0037] Comprehensively consider the internal resistance increase rate and exchange membrane degradation rate to measure the fuel cell output power performance; load power increment And output power allocation ratio K (t) expression:

[0038] ; (10)

[0039] ; (11)

[0040] in, express t The power demand increment of the load at that moment, and They represent the output power increments of the two fuel cells respectively; S FC1 and S FC2 Represents the exchange membrane area of ​​the actual fuel cell, characterizing the ability of the fuel cell to output current; and The expression is:

[0041] ; (12)

[0042] ;(13).

[0043] Furthermore, the expression of the internal resistance increase rate is:

[0044] ; (14)

[0045] in, λ R-rate(t) expresst The internal resistance increase rate of the fuel cell at each moment; express t The ohmic internal resistance detected externally at all times; R int-ref(t) To represent the internal resistance at the same output current according to the reference polarization curve; express t The fuel cell outputs current at all times.

[0046] Furthermore, the exchange membrane degradation rate is expressed as:

[0047] ; (15)

[0048] in, λ S-rate(t) express t The degradation rate of the fuel cell exchange membrane at the moment, P real(t) express t The actual output power of the fuel cell is obtained by detecting the output voltage and current of the fuel cell at all times. P ref(t) Represents the output power at the same output current according to the reference polarization curve.

[0049] Furthermore, an adaptive power allocation strategy considering the performance difference of the fuel cell stack is used to adaptively allocate the reference power Pref of the fuel cell to the two fuel cells according to the performance difference of the fuel cell stack; the two fuel cells adopt a PI dual closed-loop constant power control structure based on SOC recovery control, and respectively transmit power to the DC bus in one direction through a Boost DC / DC converter according to the allocation strategy; the battery adopts a voltage and current PI dual closed-loop control, and absorbs power from the DC bus or transmits power to the DC bus through a bidirectional DC / DC converter.

[0050] The present invention also includes a hydrogen storage coordination control device based on the durability of a multi-stack fuel cell system, comprising: a first converter, a second converter, a third converter, a power coordination controller and a power distributor;

[0051] The battery is connected to the DC bus through the first converter, and the fuel cell is connected to the DC bus through the second converter and the third converter; the first converter, the second converter and the third converter receive the PWM signal generated by the controller, and the output is the on-off of the DC / DC field effect tube;

[0052] The input signal of the power coordination controller is the output power of the battery, the output voltage of the battery, the output current of the battery and the value of the battery state of charge of the battery; the output of the power coordination controller is the reference value of the output power of the fuel cell;

[0053] The input signal of the power distributor is the output signal of the power coordination controller, namely, the fuel cell output power reference value; the output of the power distributor is the power reference value that each of the two fuel cells should bear.

[0054] Compared with the prior art, the present invention has the following advantages:

[0055] The hydrogen storage coordination control method and device proposed in the present invention, which takes into account the durability of the multi-stack fuel cell system, respectively transmits power to the DC bus in one direction according to the allocation strategy through the Boost type DC / DC converter and restores the battery SOC to ensure the stable operation of the system; the battery adopts voltage and current PI double closed-loop control, and absorbs power from the DC bus or transmits power to the DC bus through the bidirectional DC / DC converter. Ultimately, transient power balance and steady-state energy complementarity between the fuel cell and the battery are achieved, the system DC bus voltage fluctuation is suppressed, and the overall performance of the multi-stack fuel cell system is improved, thereby improving the economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0057] Figure 1 1 is the structure diagram of the multi-stack fuel cell system used in the present invention. Among them, 1 is the first converter; 2 is the second converter; 3 is the third converter; 4 is the power coordination controller; 5 is the power distributor; 6 is the DC microgrid; 7 is the battery; 8 is the No. 1 stack; 9 is the No. 2 stack; 10 is PWM; 11 is P-SOC; 12 is the voltage and current dual loop; A is SOC ; B is U B , ; C is P B ; E is ; F is .

[0058] Figure 2 This is a diagram for realizing the coordinated control method of hydrogen storage of the present invention. 1 is a battery; 2 is a dual closed-loop control I based on P-SOC; 3 is the distribution coefficient of the No. 1 stack; 4 is the distribution coefficient of the No. 2 stack; 5 is a power distribution algorithm; 6 is a dual closed-loop control II based on P-SOC; 7 is the No. 1 stack; 8 is the No. 2 stack; and 9 is PI control.

[0059] Figure 3Schematic diagram of fuel cell output power when the initial load is set to 20kW, 20kW and 10kW are added at 1s and 3s respectively, and 26kW load is removed at 5s; wherein 1 represents the traditional method, and 2 represents the method of the present application.

[0060] Figure 4 The schematic diagram of battery output power is shown in Figure 1. The initial load is set to 20kW, 20kW and 10kW are added at 1s and 3s respectively, and 26kW load is removed at 5s. 1 represents the traditional method, and 2 represents the method of the present application.

[0061] Figure 5 The SOC recovery simulation diagram is shown when the initial load is set to 20kW, 20kW and 10kW are added at 1s and 3s respectively, and 26kW load is removed at 5s; wherein 1 represents the traditional method, and 2 represents the method of the present application.

[0062] Figure 6 A real-time power distribution diagram is shown when the initial load is set to 40kW, 20kW and 10kW are added at 1s and 3s respectively, and 26kW load is removed at 5s; wherein 1 represents the traditional method, and 2 represents the method of the present application.

[0063] Figure 7 A schematic diagram of traditional current distribution when the initial load is set to 40kW, 20kW and 10kW are added at 1s and 3s respectively, and 26kW load is removed at 5s; wherein 1 represents the traditional method, and 2 represents the method of the present application.

[0064] Figure 8 This is a load power diagram.

[0065] Fig. 9 This is a schematic diagram of battery output power.

[0066] Fig.10 Schematic diagram of fuel cell output power.

[0067] Fig.11 Schematic diagram of battery state of charge change waveform. DETAILED DESCRIPTION

[0068] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0069] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0070] like Figure 1 As shown, the present invention provides a hydrogen storage coordination control device based on the durability of a multi-stack fuel cell system, including: a first converter, a second converter, a third converter, a power coordination controller and a power distributor.

[0071] The battery is connected to the DC bus through the first converter, and the fuel cell is connected to the DC bus through the second converter and the third converter; the first converter, the second converter and the third converter receive the PWM signal generated by the controller, and the output is the on-off of the DC / DC field effect tube.

[0072] The input signals of the power coordination controller are the output power, output voltage, output current and state of charge of the battery; the output of the power coordination controller is the reference value of the fuel cell output power.

[0073] The input signal of the power distributor is the output signal of the power coordination controller, namely, the fuel cell output power reference value; the output of the power distributor is the power reference value that each of the two fuel cells should bear.

[0074] like Figure 2 As shown, the present invention also provides a hydrogen storage coordination control method considering the durability of a multi-stack fuel cell system, which is applied to a DC / DC converter output controller and includes the following steps:

[0075] Step 1: Introduce the battery state of charge recovery control structure; by transmitting the battery state of charge and line information detected by the sensor to the controller, the reference power of the fuel cell is restored. P ref Designed to restore the battery state of charge of the battery.

[0076] Step 2: Introduce the power differential term of the battery , which is the dynamic adjustment power of the battery state of charge, and the reference power expression of the fuel cell is obtained.

[0077] Step 3: Determine the size of the fuel cell output power; when the fuel cell output power is greater than the maximum power limit, control the battery to release electrical energy to relieve the pressure of fuel cell overload and maintain system power balance; when the fuel cell output power reaches the minimum power limit, control the battery to absorb electrical energy and increase the output power to maintain power balance.

[0078] Step 4: Use the rate of change of battery state of charge d SOC / d t Adjust the output power of the battery P B , by setting different battery output reference power P B_ref , dynamically change the reference value of the battery state of charge SOC ref value, causing the battery to discharge or absorb power.

[0079] Preferably, in step 1, the fuel cell is powered according to a reference power P ref The expression of output power is:

[0080] ; (1)

[0081] in, P fc Indicates the base power value, that is, the load that the fuel cell should bear; P SOC Indicates the load that the fuel cell needs to bear in order to adjust the state of charge of the battery; P SOC include: and ;in Indicates the regulated power of the battery state of charge, Represents the power differential term of the battery;

[0082] The battery state of charge regulates the power The expression is:

[0083] ; (2)

[0084] in, and Respectively represent the proportional and integral coefficients of the PI controller; Respectively represent the reference value and actual value of the battery state of charge; represents the Laplace operator.

[0085] As a preferred embodiment, in step 2, the power differential term of the battery is introduced As the dynamic adjustment power of the battery state of charge, the power differential term of the battery The expression is:

[0086] ; (3)

[0087] in, represents the power differential coefficient, Indicates the output power of the battery, and its relationship with the battery charge state is:

[0088] ; (4)

[0089] in, Indicates the initial state of charge; Indicates the output current of the battery; Indicates the rated output current of the battery; Indicates the rated capacity of the battery in ampere-hours; Indicates the rated capacity of the battery in watt-hours; Indicates the rated power of the battery; represents the output voltage of the battery, then:

[0090] ; (5)

[0091] in, K c =( U B I B_rate C B_rate ) / P B_rate ,when U B When is a constant, K c is a constant; then, the reference power expression of the fuel cell is:

[0092] ; (6)

[0093] In the formula, .

[0094] As a preferred embodiment, in this application, the battery outputs a reference power P B_ref The expression is:

[0095] ; (7)

[0096] in,P load Indicates load power; P fc_max and P fc_min Respectively represent the maximum and minimum output power allowed for fuel cell operation; P fc_High and P fc_Low Respectively represent the upper and lower limits of the output power of the fuel cell;

[0097] Find:

[0098] ; (8)

[0099] in, P B_ref Indicates the reference power of lithium battery. SOC 0 represents the initial SOC of the lithium battery. SOC ref Indicates the SOC reference value of lithium battery.

[0100] Preferably, in the present application, in step 1, in order to restore the control structure, a power adaptive allocation strategy based on the degree of degradation is introduced to characterize the degree of fuel cell degradation by the internal resistance increase rate and the exchange membrane degradation rate, taking into account the problem of inconsistency in the fuel cell stack performance caused by long-term operation.

[0101] Fuel cells have special output characteristics of polarization, and the output voltage is expressed as:

[0102] ; (9)

[0103] in, E OC Represents the open circuit voltage of the fuel cell; U FC-ref Indicates the output reference voltage of the battery stack, E loss It represents the potential loss required to overcome the reaction resistance, expressed as a quadratic function of the current; Indicates current fitting E loss The fitting coefficients in the process; Represents the fuel cell output current.

[0104] Comprehensively consider the internal resistance increase rate and exchange membrane degradation rate to measure the fuel cell output power performance; load power increment And output power allocation ratio K (t) expression:

[0105] ; (10)

[0106] ; (11)

[0107] in, express t The power demand increment of the load at that moment, and They represent the output power increments of the two fuel cells respectively; S FC1 and S FC2 Represents the exchange membrane area of ​​the actual fuel cell, characterizing the ability of the fuel cell to output current; and The expression is:

[0108] ; (12)

[0109] ; (13).

[0110] As a preferred embodiment, the expression of the internal resistance increase rate is:

[0111] ; (14)

[0112] in, λ R-rate(t) express t The internal resistance increase rate of the fuel cell at each moment; express t The ohmic internal resistance detected externally at all times; R int-ref(t) To represent the internal resistance at the same output current according to the reference polarization curve; express t The fuel cell outputs current at all times. The greater the internal resistance increase rate, the faster the fuel cell performance decays. The smaller the internal resistance increase rate and the closer it is to 100%, the slower the fuel cell performance decays. When the increase rate is equal to 100%, it means that the fuel cell is in the optimal performance state.

[0113] As a preferred embodiment, general studies have shown that the larger the exchange membrane area, the more reactants are exposed, the greater the current density, and the greater the ability to output power under the same conditions. The exchange membrane degradation rate is expressed as:

[0114] ; (15)

[0115] in, λ S-rate(t) express t The degradation rate of the fuel cell exchange membrane at the moment, P real(t) express tThe actual output power of the fuel cell is obtained by detecting the output voltage and current of the fuel cell at all times. P ref(t) It indicates the output power under the same output current according to the reference polarization curve. The larger the exchange membrane degradation rate, the faster the performance of the fuel cell decays. The smaller the exchange membrane degradation rate is and the closer it is to 0%, the slower the fuel cell performance decays. A degradation rate of 0% indicates that the fuel cell is in the optimal performance state.

[0116] In order to verify the effectiveness of the present invention, simulation verification is carried out using MATLAB / Simulink software. Figure 3-Figure 5 The fuel cell automatically realizes the simulation diagram of battery SOC recovery. It can be seen from the figure that after the introduction of SOC recovery control, the output power of the fuel cell in steady state is consistent with that before the introduction, indicating that the control of the present invention does not affect the steady-state output power of the fuel cell; however, when the load suddenly changes, there will be a certain amount of overshoot in the fuel cell output, and the overshoot part is the process of the fuel cell charging or discharging the battery. The overshoot part of the battery is the process of charging and discharging to restore the SOC. After each load mutation, the battery can quickly restore the SOC to ensure that the battery pack charge state is in the normal range.

[0117] Combination Figure 6 As can be seen from Figure 7, unlike traditional current equalization control, the method of the present invention takes into account the different performance of each fuel cell and distributes the power increment differently. When overloaded, the fuel cell with better performance bears a larger power increment, and the fuel cell with poorer performance bears a smaller power increment; when lightly loaded, although the power borne by the two is different, the difference is not large, and both operate within their respective higher efficiency ranges.

[0118] Figure 8-Figure 11 This is a simulation diagram of the proposed control method under pulsating load. It can be seen that every time the pulsating load increases, the battery responds first to output power, and then the fuel cell starts to change to supplement the power shortage; every time the pulsating load decreases, the battery responds first to absorb the surplus power, and then the fuel cell starts to change to reduce the output power. Power distribution and SOC recovery can also be achieved normally, further verifying the feasibility of the proposed control strategy in ship applications.

[0119] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments. In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments. In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways.

[0120] 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 hydrogen storage coordination control method considering the durability of a multi-stack fuel cell system, applied to a DC / DC converter output controller, characterized in that: The following steps are involved: Step 1: Introduce the battery state of charge recovery control structure; by transmitting the battery state of charge and line information detected by the sensor to the controller, the reference power of the fuel cell is restored. P ref Design to restore the battery charge state of the battery; in step 1, the fuel cell is based on the reference power P ref The expression of output power is: ；(1) in, P fc Indicates the base power value, that is, the load that the fuel cell should bear; P SOC Indicates the load that the fuel cell needs to bear in order to adjust the state of charge of the battery; P SOC include: and ;in, Indicates the regulated power of the battery state of charge, Represents the power differential term of the battery; The battery state of charge regulates the power The expression is: ；(2) in, and Respectively represent the proportional and integral coefficients of the PI controller; Respectively represent the reference value and actual value of the battery state of charge; represents the Laplace operator; Step 2: Introduce the power differential term of the battery , which is the dynamic adjustment power of the battery state of charge, to obtain the reference power expression of the fuel cell; in step 2, the power differential term of the battery is introduced As the dynamic adjustment power of the battery state of charge, the power differential term of the battery The expression is: ；(3) in, represents the power differential coefficient, Indicates the output power of the battery, and its relationship with the battery charge state is: ；(4) in, Indicates the initial state of charge; Indicates the output current of the battery; Indicates the rated output current of the battery; Indicates the rated capacity of the battery in ampere-hours; Indicates the rated capacity of the battery in watt-hours; Indicates the rated power of the battery; represents the output voltage of the battery, then: ；(5) in, K c =( U B I B_rate C B_rate ) / P B_rate ,when U B When is a constant, K c is a constant; then, the reference power expression of the fuel cell is: ；(6) in, ; The battery output reference power P B_ref The expression is: ；(7) in, P load Indicates load power; P fc_max and P fc_min Respectively represent the maximum and minimum output power allowed for fuel cell operation; P fc_High and P fc_Low Respectively represent the upper and lower limits of the output power of the fuel cell; Find: ；(8) in, P B_ref Indicates the reference power of lithium battery. SOC 0 represents the initial SOC of the lithium battery. SOC ref Indicates the SOC reference value of lithium battery; Step 3: Determine the size of the fuel cell output power; when the fuel cell output power is greater than the maximum power limit, control the battery to release electrical energy to relieve the pressure of fuel cell overload and maintain system power balance; when the fuel cell output power reaches the minimum power limit, control the battery to absorb electrical energy to increase the output power to maintain power balance; Step 4: Use the rate of change of battery state of charge d SOC / d t Adjust the output power of the battery P B , by setting different battery output reference power P B_ref , dynamically change the reference value of the battery state of charge SOC ref value, causing the battery to discharge or absorb power.

2. A hydrogen storage coordinated control method considering the durability of a multi-stack fuel cell system according to claim 1, characterized in that: In the step 1, in order to restore the control structure, the problem of inconsistent fuel cell performance caused by long-term operation is considered, and a power adaptive allocation strategy based on the degree of degradation is introduced, and the degree of fuel cell degradation is characterized by the internal resistance increase rate and the exchange membrane degradation rate; Fuel cells have special output characteristics of polarization, and the output voltage is expressed as: ； (9) in, E OC Represents the open circuit voltage of the fuel cell; U FC-ref Indicates the output reference voltage of the battery stack, E loss It is the potential loss required to overcome the reaction resistance, expressed as a quadratic function of the current, Indicates current fitting E loss The fitting coefficients in the process; Represents the fuel cell output current; Comprehensively consider the internal resistance increase rate and exchange membrane degradation rate to measure the fuel cell output power performance; load power increment And output power allocation ratio K (t) expression: ；(10) ；(11) in, express t The power demand increment of the load at that moment, and They represent the output power increments of the two fuel cells respectively; S FC1 and S FC2 Represents the exchange membrane area of ​​the actual fuel cell, characterizing the ability of the fuel cell to output current; and The expression is: ； (12) ； (13)。 3. The hydrogen storage coordinated control method considering the durability of a multi-stack fuel cell system according to claim 2, characterized in that: The expression of the internal resistance increase rate is: ；(14) in, λ R-rate(t) express t The internal resistance increase rate of the fuel cell at each moment; R int-real(t) express t The ohmic internal resistance detected externally at all times; R int-ref(t) It represents the internal resistance at the same output current according to the reference polarization curve; express t The fuel cell outputs current at all times.

4. The hydrogen storage coordinated control method considering the durability of a multi-stack fuel cell system according to claim 2, characterized in that: The exchange membrane degradation rate is expressed as: ；(15) in, λ S-rate(t) express t The degradation rate of the fuel cell exchange membrane at the moment, P real(t) express t The actual output power of the fuel cell is obtained by detecting the output voltage and current of the fuel cell at all times. P ref(t) Represents the output power at the same output current according to the reference polarization curve.

5. According to claim 1, a hydrogen storage coordinated control method considering the durability of a multi-stack fuel cell system is characterized in that: An adaptive power allocation strategy considering the performance differences of the fuel cell stack is used to adjust the reference power of the fuel cell. P ref The power is adaptively allocated to the two fuel cells according to the performance difference of the fuel cell stack; the two fuel cells adopt a PI dual closed-loop constant power control structure based on SOC recovery control, and respectively transmit power to the DC bus in one direction through a Boost DC / DC converter according to the allocation strategy; the battery adopts a voltage and current PI dual closed-loop control, and absorbs power from the DC bus or transmits power to the DC bus through a bidirectional DC / DC converter.

6. A hydrogen storage coordination control device considering the durability of a multi-stack fuel cell system, applying the method described in any one of claims 1 to 5, characterized in that: include: A first converter (1), a second converter (2), a third converter (3), a power coordination controller (4) and a power distributor (5); The storage battery is connected to the DC bus through a first converter (1), and the fuel cell is connected to the DC bus through a second converter (2) and a third converter (3); the first converter (1), the second converter (2) and the third converter (3) receive a PWM signal generated by a controller, and the output is the on / off switching of a DC / DC field effect tube; The input signals of the power coordination controller (4) are the output power of the battery, the output voltage of the battery, the output current of the battery and the value of the battery state of charge of the battery; the output of the power coordination controller (4) is the reference value of the output power of the fuel cell; The input signal of the power distributor (5) is the output signal of the power coordination controller (4), namely, the fuel cell output power reference value; the output of the power distributor (5) is the power reference value that each of the two fuel cells should bear.

Images