Fuel cell system disturbance variable load control method and system

Abstract

The invention relates to the technical field of fuel cells, and discloses a fuel cell system disturbance variable load control method and system.The method comprises the steps that the average output power P and the total operation time T of a fuel cell system in one-time operation are calculated, and the average output power P and the total operation time T are calculated in combination with a preset strategy and an electric pile polarization characteristic curve; calculating m current set values higher than the average output power P and corresponding output voltages and operation time thereof, and calculating n-m current set values lower than the average output power P and corresponding output voltages and operation time thereof; the preset strategy comprises the steps of controlling the total output energy of the fuel cell system to be unchanged under the current points of all stages, and controlling the SOC electric quantity of the storage battery to be unchanged, namely charging and discharging are balanced. The membrane electrode can be prevented from being attenuated, and the system efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a method and system for controlling disturbance load changes in a fuel cell system. Background Art

[0002] Currently, fuel cell systems (such as proton exchange membrane hydrogen fuel cell systems) and commercial vehicle systems often encounter performance degradation or flooding (low voltage, instability) after a period of constant current operation (or idling), affecting power generation efficiency and system stability. This problem is particularly noticeable under power generation (constant current, long-term operation) conditions.

[0003] Typically, performance degradation is allowed (if there are no stability issues) which means accepting a drop in efficiency, or intervention measures such as purging (high stoichiometric ratio) are used to restore fuel cell system performance. However, this common approach has several drawbacks:

[0004] (1) Interference can only be performed periodically, and most of the time, interference measures can only be triggered when the system performance degrades to a certain level;

[0005] (2) The membrane electrode of the fuel cell system decays quickly;

[0006] (3) Batteries (such as lithium batteries) are not easy to balance (overcharge or over-discharge);

[0007] (4) Long-term constant current operation is prone to flooding and performance degradation;

[0008] (5) High hydrogen consumption (increased operating costs). Summary of the Invention

[0009] In order to solve the above problems, the present invention proposes a method and system for controlling disturbance load of a fuel cell system, which can prevent membrane electrode attenuation and improve system efficiency.

[0010] The technical solution adopted in the present invention is as follows:

[0011] A method for controlling disturbance-variable loads of a fuel cell system comprises: calculating the average output power P and the total operating time T of the fuel cell system in one operation; based on the average output power P and the total operating time T, in combination with a preset strategy and a stack polarization characteristic curve, calculating m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times, and calculating nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times; the preset strategy comprises: controlling the total output energy of the fuel cell system to remain unchanged at each current point, and controlling the battery SOC to remain unchanged, that is, maintaining charge and discharge balance.

[0012] Furthermore, the calculating of m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times includes:

[0013] Calculate m current setting values ​​higher than the average output power P: I1, I2, ..., I m ;

[0014] Calculate the output voltage corresponding to the current setting value: U1, U2, ..., U m ;

[0015] Calculate the operating time corresponding to the current setting value: t1, t2, ..., t m .

[0016] Furthermore, the calculating of nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times includes:

[0017] Calculate nm current setting values ​​below the average output power P: I m+1 ,I m+2 ,...,I n ;

[0018] Calculate the output voltage corresponding to the current setting value: U m+1 ,U m+2 ,...,U n ;

[0019] Calculate the running time corresponding to the current setting value: t m+1 ,t m+2 ,...,t n .

[0020] Furthermore, controlling the total output energy of the fuel cell system to remain unchanged at each current point and controlling the SOC of the battery to remain unchanged, i.e., charge and discharge balance, includes:

[0021] The average value of the power at each current point is controlled to be equal to the average output power P:

[0022]

[0023] Control the charging and discharging of the battery to maintain balance:

[0024]

[0025] Among them, I battery is the battery current, which is positive during charging and negative during discharging;

[0026] Based on the actual power scheduling requirements, the battery charging and discharging strategy is set at each current point in each stage.

[0027] Furthermore, when the power at the operating current point is higher than the average power of the fuel cell system, the fuel cell system is controlled to charge the battery; when the power at the operating current point is lower than the average power of the fuel cell system, the battery is controlled to discharge.

[0028] A fuel cell system disturbance load control system, comprising:

[0029] A first processor is configured to calculate an average output power P and a total operation time T of the fuel cell system in one operation;

[0030] The second processor is configured to calculate m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times, and calculate nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times based on the average output power P and the total operating time T, in combination with a preset strategy and a stack polarization characteristic curve; the preset strategy includes: controlling the total output energy of the fuel cell system to remain unchanged at the current point in each stage, and controlling the battery SOC to remain unchanged, that is, the charge and discharge balance.

[0031] Furthermore, in the second processor, calculating m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times includes:

[0032] Calculate m current setting values ​​higher than the average output power P: I1, I2, ..., I m ;

[0033] Calculate the output voltage corresponding to the current setting value: U1, U2, ..., U m ;

[0034] Calculate the operating time corresponding to the current setting value: t1, t2, ..., t m .

[0035] Furthermore, in the second processor, calculating nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times includes:

[0036] Calculate nm current setting values ​​below the average output power P: I m+1 ,I m+2 ,...,I n ;

[0037] Calculate the output voltage corresponding to the current setting value: U m+1 ,U m+2 ,...,U n ;

[0038] Calculate the running time corresponding to the current setting value: t m+1 ,tm+2 ,...,t n .

[0039] Furthermore, the second processor controls the total output energy of the fuel cell system to remain unchanged at each current point, and controls the SOC of the battery to remain unchanged, that is, to maintain charge and discharge balance, including:

[0040] The average value of the power at each current point is controlled to be equal to the average output power P:

[0041]

[0042] Control the charging and discharging of the battery to maintain balance:

[0043]

[0044] Among them, I battery is the battery current, which is positive during charging and negative during discharging;

[0045] Based on the actual power scheduling requirements, the battery charging and discharging strategy is set at each current point in each stage.

[0046] Furthermore, in the second processor, when the power at the operating current point is higher than the average power of the fuel cell system, the fuel cell system is controlled to charge the battery; when the power at the operating current point is lower than the average power of the fuel cell system, the battery is controlled to discharge.

[0047] The beneficial effects of the present invention are:

[0048] 1) Delaying the degradation of the membrane electrode of the fuel cell system, thereby extending the service life of the fuel cell system;

[0049] 2) Make the battery charge and discharge balanced, neither overcharge nor over discharge;

[0050] 3) By first increasing the load and then decreasing the load, the liquid water in the catalyst layer and the gas diffusion layer is discharged, which reduces the mass transfer loss and improves the performance;

[0051] 4) The hydrogen consumption is the lowest when the fuel cell system outputs the same electrical energy, which improves the power generation efficiency and reduces the operating cost of the fuel cell system engine vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flow chart of the disturbance variable load control method for the fuel cell system according to Example 1 of the present invention.

[0053] Figure 2 This is a schematic diagram of the principle of the fuel cell system disturbance variable load control method according to Example 1 of the present invention.

[0054] Figure 3This is a graph showing the changes in voltage, current and power during constant current operation.

[0055] Figure 4 This is a diagram of battery charging current changes in disturbance variable load control.

[0056] Figure 5 This is the principle diagram of the battery balancing control method under disturbance and variable load.

[0057] Figure 6 This is a comparison chart between the variable load control method and the constant current operation condition under the same total output power. DETAILED DESCRIPTION

[0058] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0059] Example 1

[0060] like Figure 1 As shown, this embodiment provides a disturbance variable load control method for a fuel cell system, including: calculating the average output power P and the total operating time T of the fuel cell system in one operation, combining the preset strategy and the polarization characteristic curve of the stack, calculating m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times, and calculating nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times; wherein the preset strategy includes: controlling the total output energy of the fuel cell system to remain unchanged at the current point in each stage, and controlling the battery SOC to remain unchanged, that is, the charge and discharge balance.

[0061] It should be noted that based on the above disturbance load control method, the following goals can be achieved:

[0062] (1) Prevent membrane electrode degradation in fuel cell systems;

[0063] (2) By generating more heat at an operating point with a higher current density than that of constant current operation to evaporate the liquid water in the catalyst layer, the fuel cell power generation efficiency is improved by enhancing mass transfer;

[0064] (3) The stack achieves the highest power generation efficiency and the lowest hydrogen consumption in this operation, which is less than the hydrogen consumption in constant current operation, that is:

[0065] Preferably, calculating m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times includes:

[0066] Calculate m current setting values ​​higher than the average output power P: I1, I2, ..., I m ;

[0067] Calculate the output voltage corresponding to the current setting value: U1, U2, ..., U m ;

[0068] Calculate the operating time corresponding to the current setting value: t1, t2, ..., t m .

[0069] Preferably, calculating nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times includes:

[0070] Calculate nm current setting values ​​below the average output power P: I m+1 ,I m+2 ,...,I n ;

[0071] Calculate the output voltage corresponding to the current setting value: U m+1 ,U m+2 ,...,U n ;

[0072] Calculate the running time corresponding to the current setting value: t m+1 ,t m+2 ,...,t n .

[0073] Preferably, controlling the total output energy of the fuel cell system to remain unchanged at each current point and controlling the SOC of the battery to remain unchanged, i.e., charge and discharge balance, includes:

[0074] like Figures 2 to 4 As shown in Figure 1, the average power value at each current point in each stage is equal to the average output power P, that is, the total integral (sum) of the power over time at each current point is consistent with the product of the overall average power and the overall operating time of the fuel cell system (P*T):

[0075]

[0076] At the same time, the battery charging and discharging are controlled to maintain a balance:

[0077]

[0078] Among them, I battery is the battery current, which is positive during charging and negative during discharging;

[0079] Based on the actual power scheduling requirements, set the battery charging and discharging strategy at each current point: I 1,battery,t 1,battery ;I 2,battery ,t 2,battery ...I n,battery ,t n,battery .

[0080] Preferably, when the power at the operating current point is higher than the average power of the fuel cell system, the fuel cell system is controlled to charge the battery; when the power at the operating current point is lower than the average power of the fuel cell system, the battery is controlled to discharge (part of the energy comes from the battery to supplement the power demand of the entire vehicle).

[0081] like Figure 5 As shown, relative to the average electrical density of 1.5A / cm 2 In the constant current working condition, through the variable load control method of this embodiment, the power generation in the variable load condition is higher than the fuel cell system demand during 0-19.5 minutes, and the lithium battery is charged; and the power generation is lower than the fuel cell system demand during 20-39 minutes, and the lithium battery is discharged. This satisfies the balance between battery charging and discharging, i.e.

[0082] like Figure 6 As shown, the total operating time of the two operating conditions is T. When the total output power of the fuel cell is the same, That is, the power generation of the variable load control method of this embodiment is lower than the power generation of the constant current operation, that is, the hydrogen consumption of the variable load control method of this embodiment is lower than that of the constant current operation.

[0083] Example 2

[0084] This embodiment provides a fuel cell system disturbance load control system, including:

[0085] A first processor is configured to calculate an average output power P and a total operation time T of the fuel cell system in one operation;

[0086] The second processor is configured to calculate m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times, and calculate nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times based on the average output power P and the total operating time T, in combination with a preset strategy and the polarization characteristic curve of the fuel cell stack; the preset strategy includes: controlling the total output energy of the fuel cell system to remain unchanged at the current point in each stage, and controlling the battery SOC to remain unchanged, that is, the charge and discharge balance.

[0087] Preferably, in the second processor, calculating m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times includes:

[0088] Calculate m current setting values ​​higher than the average output power P: I1, I2, ..., I m ;

[0089] Calculate the output voltage corresponding to the current setting value: U1, U2, ..., U m ;

[0090] Calculate the operating time corresponding to the current setting value: t1, t2, ..., t m .

[0091] Preferably, in the second processor, calculating nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times includes:

[0092] Calculate nm current setting values ​​below the average output power P: I m+1 ,I m+2 ,...,I n ;

[0093] Calculate the output voltage corresponding to the current setting value: U m+1 ,U m+2 ,...,U n ;

[0094] Calculate the running time corresponding to the current setting value: t m+1 ,t m+2 ,...,t n .

[0095] Preferably, the second processor controls the total output energy of the fuel cell system to remain unchanged at each current point, and controls the SOC of the battery to remain unchanged, that is, to maintain charge and discharge balance, including:

[0096] The average value of the power at each current point is controlled to be equal to the average output power P:

[0097]

[0098] Control the charging and discharging of the battery to maintain balance:

[0099]

[0100] Among them, I battery is the battery current, which is positive during charging and negative during discharging;

[0101] Based on the actual power scheduling requirements, the battery charging and discharging strategy is set at each current point in each stage.

[0102] Preferably, in the second processor, when the power at the operating current point is higher than the average power of the fuel cell system, the fuel cell system is controlled to charge the battery; when the power at the operating current point is lower than the average power of the fuel cell system, the battery is controlled to discharge.

[0103] Example 3

[0104] This embodiment is based on embodiment 1:

[0105] This embodiment provides a computer device including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a method for controlling a fuel cell system with a disturbance and variable load according to embodiment 1. The computer program may be in source code form, object code form, an executable file, or some intermediate form.

[0106] Example 4

[0107] This embodiment is based on embodiment 1:

[0108] This embodiment provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a fuel cell system disturbance variable load control method of embodiment 1. The computer program may be in source code form, object code form, executable file, or some intermediate form, etc. The storage medium includes: any entity or device capable of carrying computer program code, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content contained in the storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the storage medium does not include electric carrier signals and telecommunication signals.

[0109] It should be noted that, for the aforementioned method embodiments, for ease of description, they are expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited to the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by this application. In addition, the terms "first", "second", "third", etc. are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

Claims

1. A method for controlling disturbance load of a fuel cell system, characterized in that: include: Calculate the average output power P and total operating time T of the fuel cell system in one operation; Based on the average output power P and the total operating time T, combined with the preset strategy and the stack polarization characteristic curve, calculate m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times, and calculate nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times; The preset strategy includes: controlling the total output energy of the fuel cell system to remain unchanged at each current point, and controlling the SOC of the battery to remain unchanged, that is, the charge and discharge balance.

2. A fuel cell system disturbance load control method according to claim 1, characterized in that: The calculating of m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times includes: Calculate m current setting values ​​higher than the average output power P: I1, I2, ..., I m ; Calculate the output voltage corresponding to the current setting value: U1, U2, ..., U m ; Calculate the operating time corresponding to the current setting value: t1, t2, ..., t m .

3. A fuel cell system disturbance load control method according to claim 2, characterized in that: The calculating of nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times includes: Calculate nm current setting values ​​below the average output power P: I m+1 ,I m+2 ,...,I n ; Calculate the output voltage corresponding to the current setting value: U m+1 ,U m+2 ,...,U n ; Calculate the running time corresponding to the current setting value: t m+1 ,t m+2 ,...,t n .

4. A fuel cell system disturbance load control method according to claim 3, characterized in that: The control of the total output energy of the fuel cell system to remain unchanged at each current point and the control of the battery SOC to remain unchanged, i.e., charge and discharge balance, includes: The average value of the power at each current point is controlled to be equal to the average output power P: Control the charging and discharging of the battery to maintain balance: ∫0 T I batteey ·dt=0 Among them, I battery is the battery current, which is positive during charging and negative during discharging; Based on the actual power scheduling requirements, the battery charging and discharging strategy is set at each current point in each stage.

5. A fuel cell system disturbance load control method according to claim 1, characterized in that: When the power at the operating current point is higher than the average power of the fuel cell system, the fuel cell system is controlled to charge the battery; when the power at the operating current point is lower than the average power of the fuel cell system, the battery is controlled to discharge.

6. A fuel cell system disturbance load control system, characterized in that: include: A first processor is configured to calculate an average output power P and a total operation time T of the fuel cell system in one operation; The second processor is configured to calculate m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times, and calculate nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times based on the average output power P and the total operating time T, in combination with a preset strategy and a stack polarization characteristic curve; the preset strategy includes: controlling the total output energy of the fuel cell system to remain unchanged at the current point in each stage, and controlling the battery SOC to remain unchanged, that is, the charge and discharge balance.

7. A fuel cell system disturbance load control system according to claim 6, characterized in that: In the second processor, calculating m current setting values ​​higher than the average output power P and their corresponding output voltages and operating times includes: Calculate m current setting values ​​higher than the average output power P: I1, I2, ..., I m ; Calculate the output voltage corresponding to the current setting value: U1, U2, ..., U m ; Calculate the operating time corresponding to the current setting value: t1, t2, ..., t m .

8. A fuel cell system disturbance load control system according to claim 7, characterized in that: In the second processor, calculating nm current setting values ​​lower than the average output power P and their corresponding output voltages and operating times includes: Calculate nm current setting values ​​below the average output power P: I m+1 ,I m+2 ,...,I n ; Calculate the output voltage corresponding to the current setting value: U m+1 ,U m+2 ,...,U n ; Calculate the running time corresponding to the current setting value: t m+1 ,t m+2 ,...,t n .

9. A fuel cell system disturbance load control system according to claim 8, characterized in that: The second processor controls the total output energy of the fuel cell system to remain unchanged at each current point, and controls the SOC of the battery to remain unchanged, that is, to achieve charge and discharge balance, including: The average value of the power at each current point is controlled to be equal to the average output power P: Control the charging and discharging of the battery to maintain balance: ∫0 T I battery ·dt=0 Among them, I battery is the battery current, which is positive during charging and negative during discharging; Based on the actual power scheduling requirements, the battery charging and discharging strategy is set at each current point in each stage.

10. A fuel cell system disturbance load control system according to claim 6, characterized in that: In the second processor, when the power at the operating current point is higher than the average power of the fuel cell system, the fuel cell system is controlled to charge the battery; when the power at the operating current point is lower than the average power of the fuel cell system, the battery is controlled to discharge.

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