A multi-module fuel cell collaborative power generation system and control method thereof

Abstract

The present invention discloses a multi-module fuel cell cooperative power generation system and a control method thereof, wherein the system includes a main controller, a chemical energy storage battery and a plurality of fuel cells; the control method includes: before each fuel cell is started, calculating the performance decay rate of each fuel cell at each working point; determining the charging and discharging requirements of the chemical energy storage battery according to the SOC value of the chemical energy storage battery; calculating and judging the number of fuel cells to be started according to the required power, based on the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of the optimal working point of each fuel cell; sorting the performance decay rate of the optimal working point of each fuel cell, and giving priority to starting the fuel cell with a lower performance decay rate of the optimal working point; calculating the working point combination of each fuel cell and the corresponding relationship between each working point and each fuel cell in the working point combination, and allocating the working point in the working point combination to the corresponding fuel cell. The present invention can realize the cooperative power generation of multi-module fuel cells.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell technology, and in particular to a multi-module fuel cell collaborative power generation system and a control method thereof. Background Art

[0002] At present, the power generation capacity of a single high-power hydrogen fuel cell power generation module (hereinafter referred to as fuel cell) is generally in the hundreds of kilowatts level. For application scenarios with high-power power generation needs, such as hydrogen energy storage, it is obviously unable to meet the power generation needs of the application scenarios, and multiple fuel cells are required to generate electricity in coordination. For the coordinated power generation of multiple fuel cells, some research results have provided their own system design and control methods, but most of them optimize the overall output efficiency of the system, and do not pay much attention to the impact of changes in the operating conditions of the fuel cell during operation on its service life and hydrogen utilization. Most of the above research results require that the output power of the fuel cell follow the external demand power. In this case, if the external demand power fluctuates frequently, it will cause the operating conditions of the fuel cell to change frequently, thereby accelerating the attenuation of the fuel cell life.

[0003] In addition, most of the current fuel cells do not have the ability to self-start, and are generally used in conjunction with chemical energy storage batteries (such as lithium batteries) of a certain capacity. There are currently few research results at home and abroad on the control method of multiple fuel cells cooperating with chemical energy storage batteries to generate electricity. In the case of multiple fuel cells cooperating with chemical energy storage batteries to generate electricity, in response to external power demand fluctuations, increasing the proportion of chemical energy storage battery power supply can reduce fuel cell operating conditions and increase fuel cell service life, but it may increase the cost of the system's chemical energy storage batteries, and there is energy loss in the charging and discharging process of chemical energy storage batteries, which will reduce the overall power generation efficiency of the system.

[0004] Fuel cells themselves have the ability to output continuous power, but currently the operating parameters of fuel cells are mostly determined by their output current density. Working under a certain series of output current densities is not only beneficial for designers to determine the operating parameters of their fuel cells at various output current densities and conduct experimental tests, but also reduces the frequency of adjusting the fuel cell output power, increases the stability of the fuel cell power generation process, and is beneficial to improving the service life of the fuel cell.

[0005] Theoretically, the performance (lifespan) decay of a fuel cell stack or membrane is holistic and consistent, that is, the same fuel cell will decay synchronously at each output current density point (hereinafter referred to as the working point), and there will almost never be a situation where some working points have little performance decay and some working points have great performance decay. However, the operating parameters of the fuel cell at each working point may be different, which will lead to differences in the state of the stack and its membrane when the fuel cell is running. This difference will affect the performance of the stack, and ultimately manifests itself as differences in the degree of fuel cell performance decay at each working point. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a multi-module fuel cell cooperative power generation system and its control method, which is based on a fuel cell with a series of fixed working points, by monitoring the performance decay rate of each fuel cell (which can be different models) at its various working points, and combining the SOC value of the chemical energy storage battery to control the fuel cell cooperative power generation. While ensuring the high overall efficiency of the system, the present invention also improves the service life of each fuel cell and the system as a whole, and the control method is flexible in application and simple to implement. In addition, the present invention has a low demand for the capacity of the chemical energy storage battery and will not significantly increase the system cost, which is very valuable for practical application.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A multi-module fuel cell coordinated power generation control method, comprising:

[0009] Before each fuel cell is started, the performance decay rate of each fuel cell at each working point is calculated;

[0010] Determine the charging and discharging requirements of the chemical energy storage battery according to the SOC value of the chemical energy storage battery;

[0011] According to the required power, based on the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of each fuel cell at the optimal working point, calculate and determine the number of fuel cells that need to be started;

[0012] The performance decay rates of the optimal working points of each fuel cell are sorted, and the fuel cell with the lower performance decay rate at the optimal working point is started first;

[0013] The working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell are calculated, and the working points in the working point combination are allocated to the corresponding fuel cells.

[0014] Furthermore, the calculation of the performance attenuation rate of each fuel cell at each operating point includes:

[0015] Before each fuel cell is put into operation, the initial average voltage and net output power of the stack of each fuel cell at a series of operating points are collected, that is, the average voltage and net output power of the stack of each fuel cell at a series of operating points are collected. 1 , I 2 ,…,I N The average cell voltage V(t0) at 1， V(t0)2,…,V(t0) N and the net output power is P(t0) 1， P(t0)2,…,P(t0) N , where N is the number of fuel cell operating points;

[0016] After the fuel cell is put into operation and actually generates electricity, the current average cell voltage V(t) of each fuel cell at a series of operating points is collected. 1， V(t)2,…,V(t) N ;

[0017] According to the average voltage value of the fuel cell stack at each operating point when each fuel cell last operated, update the performance decay rate σ(t) of each fuel cell at each operating point. n =(V(t0) n -V(t) n ) / V(t0) n , where n = 1, 2,…, N.

[0018] Further, the determining of the charge and discharge requirements of the chemical energy storage battery based on the SOC value of the chemical energy storage battery includes:

[0019] According to the SOC value of the chemical energy storage battery, the charge and discharge demand of the chemical energy storage battery is judged based on the dual hysteresis interval, and the dual hysteresis interval includes a discharge prohibition threshold, a hysteresis point threshold and a charge prohibition threshold; when the chemical energy storage battery charge and discharge demand BMS_Charge=1, it means that charging is required; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, it means that charging is prohibited; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, it means that charging and discharging are possible.

[0020] Furthermore, the method of calculating and determining the number of fuel cells to be started based on the required power, the charging and discharging requirements of the chemical energy storage battery and the relationship between the required power and the net output power of the optimal working point of each fuel cell, includes:

[0021] Calculate the sum of the net output power of each fuel cell at the optimal working point under different current startup numbers:

[0022]

[0023] In the formula, is the current performance decay rate of each fuel cell at the optimal operating point, In particular, the initial net output power of each fuel cell at the optimal operating point, and satisfying j=1,2,…,M, M is the total number of fuel cells in the system;

[0024] Determine the number of fuel cells that need to be started. At this time, the following situations exist:

[0025] a) If Then start all fuel cells;

[0026] b) If When the chemical energy storage battery charge and discharge demand BMS_Charge=1, start one fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, do not start the fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, start one fuel cell or do not start the fuel cell;

[0027] c) If it is not the case a) and b), then there must be a value k such that Established; when the chemical energy storage battery charge and discharge demand BMS_Charge = 1, start k+1 fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = -1, start k fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = 0, start k+1 or k fuel cells, where k = 1, 2, …, M-1.

[0028] Furthermore, the calculating of the working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell, and allocating the working point in the working point combination to the corresponding fuel cell includes:

[0029] If the number of fuel cells started is less than M, each started fuel cell is directly set to operate at its optimal working point;

[0030] When all fuel cells are started, if the load power is greater than or equal to the sum of the maximum output power of all fuel cells, that is, Then all fuel cells work at their highest output power working point; if the load power is less than the sum of the maximum output powers of all fuel cells, then there must be an operating point x such that the following equation holds true:

[0031]

[0032] Wherein, a=0,1,…,M-1; x=1,2,…,N-1;

[0033] When the chemical energy storage battery charge and discharge demand BMS_Charge = 1, the target scheduling working point combination is:

[0034]

[0035] When the chemical energy storage battery charge and discharge demand BMS_Charge=-1, the target scheduling working point combination is:

[0036]

[0037] When the chemical energy storage battery charge and discharge demand BMS_Charge=0, the target scheduling working point combination selects the target scheduling working point combination of BMS_Charge=0 or BMS_Charge=1;

[0038] Calculate the operating point I of each fuel cell x+1 and I x The relative net output power loss is:

[0039]

[0040] In the formula, and Respectively represent the fuel cells at the working point I x+1 and I x Performance decay rate, i = 1, 2, ..., M;

[0041] Set the working point I x+1 Prioritize the allocation to the fuel cell with the lowest relative net output power loss among all unallocated fuel cell modules, and set the operating point I x to the remaining fuel cells.

[0042] A multi-module fuel cell collaborative power generation system includes a main controller, a chemical energy storage battery and a plurality of fuel cells. The main controller controls the chemical energy storage battery and the fuel cells through communication. The fuel cells are connected to the chemical energy storage battery through a DC combiner. The main controller includes:

[0043] The performance decay rate calculation module is configured to calculate the performance decay rate of each fuel cell at each operating point before each fuel cell is started;

[0044] A charge and discharge demand determination module is configured to determine the charge and discharge demand of the chemical energy storage battery according to the SOC value of the chemical energy storage battery;

[0045] The fuel cell startup quantity determination module is configured to calculate and determine the number of fuel cells that need to be started based on the required power, the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of the optimal working point of each fuel cell;

[0046] A fuel cell startup priority judgment module is configured to sort the optimal working point performance decay rates of each fuel cell, and a fuel cell with a lower optimal working point performance decay rate is started first;

[0047] The fuel cell startup execution module is configured to calculate the working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell, and allocate the working point in the working point combination to the corresponding fuel cell.

[0048] Furthermore, in the performance decay rate calculation module, the performance decay rate of each fuel cell at each operating point is calculated, including:

[0049] Before each fuel cell is put into operation, the initial average voltage and net output power of the stack of each fuel cell at a series of operating points are collected, that is, the average voltage and net output power of the stack of each fuel cell at a series of operating points are collected. 1 , I 2 ,…,I N The average cell voltage V(t0) at 1， V(t0)2,…,V(t0) N and the net output power is P(t0) 1， P(t0)2,…,P(t0) N , where N is the number of fuel cell operating points;

[0050] After the fuel cell is put into operation and actually generates electricity, the current average cell voltage V(t) of each fuel cell at a series of operating points is collected. 1， V(t)2,…,V(t) N ;

[0051] According to the average voltage value of the fuel cell stack at each operating point when each fuel cell last operated, update the performance decay rate σ(t) of each fuel cell at each operating point. n =(V(t0) n -V(t) n ) / V(t0) n , where n = 1, 2,…, N.

[0052] Furthermore, in the charging and discharging demand judgment module, determining the charging and discharging demand of the chemical energy storage battery based on the SOC value of the chemical energy storage battery includes:

[0053] According to the SOC value of the chemical energy storage battery, the charge and discharge demand of the chemical energy storage battery is judged based on the dual hysteresis interval, and the dual hysteresis interval includes a discharge prohibition threshold, a hysteresis point threshold and a charge prohibition threshold; when the chemical energy storage battery charge and discharge demand BMS_Charge=1, it means that charging is required; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, it means that charging is prohibited; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, it means that charging and discharging are possible.

[0054] Furthermore, in the fuel cell startup quantity determination module, the number of fuel cells to be started is calculated and determined according to the required power, based on the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of the optimal working point of each fuel cell, including:

[0055] Calculate the sum of the net output power of each fuel cell at the optimal working point under different current startup numbers:

[0056]

[0057] In the formula, is the current performance decay rate of each fuel cell at the optimal operating point, In particular, the initial net output power of each fuel cell at the optimal operating point, and satisfying j=1,2,…,M, M is the total number of fuel cells in the system;

[0058] Determine the number of fuel cells that need to be started. At this time, the following situations exist:

[0059] a) If Then start all fuel cells;

[0060] b) If When the chemical energy storage battery charge and discharge demand BMS_Charge=1, start one fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, do not start the fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, start one fuel cell or do not start the fuel cell;

[0061] c) If it is not the case a) and b), then there must be a value k such that Established; when the chemical energy storage battery charge and discharge demand BMS_Charge = 1, start k+1 fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = -1, start k fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = 0, start k+1 or k fuel cells, where k = 1, 2, …, M-1.

[0062] Furthermore, in the fuel cell startup execution module, the working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell are calculated, and the working point in the working point combination is allocated to the corresponding fuel cell, including:

[0063] If the number of fuel cells started is less than M, each started fuel cell is directly set to operate at its optimal working point;

[0064] When all fuel cells are started, if the load power is greater than or equal to the sum of the maximum output power of all fuel cells, that is, Then all fuel cells work at their highest output power working point; if the load power is less than the sum of the maximum output powers of all fuel cells, then there must be an operating point x such that the following equation holds true:

[0065]

[0066] Wherein, a=0,1,…,M-1; x=1,2,…,N-1;

[0067] When the chemical energy storage battery charge and discharge demand BMS_Charge = 1, the target scheduling working point combination is:

[0068]

[0069] When the chemical energy storage battery charge and discharge demand BMS_Charge=-1, the target scheduling working point combination is:

[0070]

[0071] When the chemical energy storage battery charge and discharge demand BMS_Charge=0, the target scheduling working point combination selects the target scheduling working point combination of BMS_Charge=0 or BMS_Charge=1;

[0072] Calculate the operating point I of each fuel cell x+1 and I x The relative net output power loss is:

[0073]

[0074] In the formula, and Respectively represent the fuel cells at the working point I x+1 and I x Performance decay rate, i = 1, 2, ..., M;

[0075] Set the working point I x+1 Prioritize the allocation to the fuel cell with the lowest relative net output power loss among all unallocated fuel cell modules, and set the operating point Ix to the remaining fuel cells.

[0076] The beneficial effects of the present invention are:

[0077] 1. The present invention calculates the performance decay rate of each fuel cell at each operating point in real time and the SOC value of the chemical energy storage battery. First, it sorts the fuel cells according to the relationship between the required power and the net output of each fuel cell at its optimal operating point and the performance decay rate of each fuel cell at its optimal operating point, and combines the SOC value of the chemical energy storage battery to determine the number of fuel cells to be started and their start-up priority. Secondly, for the started fuel cells, the target operating point combination of each fuel cell is determined based on the idea of ​​average distribution. Relative average distribution allows each fuel cell to operate at the optimal operating point or a low-power operating point after the optimal operating point as much as possible, ensuring the highest net output efficiency of a single fuel cell. Finally, the relative loss low priority allocation method is used to determine the corresponding relationship between the operating points in the target operating point combination and each fuel cell, that is, to allocate the operating points in the target operating point combination to each fuel cell.

[0078] 2. The present invention has a system efficiency similar to that of the "coordinated allocation" method in Chinese patent CN108539231B, and can also make the life decay rate of each fuel cell gradually approach, achieving an effect similar to improving the consistency of multi-stack system life in Chinese patent CN111274713B. The relatively stable operating state of a single fuel cell improves the service life of a single fuel cell to a certain extent, and the consistency of the life of each fuel cell also extends the overall service life of multiple fuel cell collaborative power generation systems. During the steady-state operation of the system, the power automatically consumed or supplemented by the chemical energy storage battery is relatively small, and the maximum steady-state power is only the net output power difference between the two working points of the fuel cell, which will not significantly increase the cost of the chemical energy storage battery.

[0079] 3. The present invention provides a relatively low loss priority allocation method. If based on Figure 4 The number of fuel cells and their performance decay rates at various operating points are input (the bold columns in the figure indicate the optimal operating point columns). Figure 5 It can be seen that compared with the high / low power operating point loss priority allocation method, the relative loss priority allocation method of the present invention makes the system net output power loss lower and has higher efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 It is a schematic diagram of a multi-module fuel cell cooperative power generation system according to Example 1 of the present invention.

[0081] Figure 2 This is a reference flow chart for collecting the average voltage of the fuel cell stack at each operating point in Example 2 of the present invention.

[0082] Figure 3 This is a logic diagram for determining the charge and discharge demand of a chemical energy storage battery in Example 2 of the present invention.

[0083] Figure 4 This is a performance attenuation rate parameter table for simulating five fuel cells at their five operating points in Example 2 of the present invention.

[0084] Figure 5 This is a comparison diagram of the net output power loss of different working point allocation methods in Example 2 of the present invention. DETAILED DESCRIPTION

[0085] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods 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, rather than all the 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.

[0086] Example 1

[0087] like Figure 1 As shown, this embodiment provides a multi-module fuel cell collaborative power generation system, including a main controller, multiple fuel cell power generation modules (hereinafter referred to as fuel cells), a DC bus cabinet / row, a chemical energy storage battery and an energy storage inverter, wherein the main controller controls the fuel cell power generation modules, the chemical energy storage battery and the energy storage inverter through communication.

[0088] In this embodiment, the fuel cell needs to have a series of fixed working points, and an optimal working point is determined in this series of fixed working points. The optimal working point can be the working point with the highest efficiency of the fuel cell, or the working point determined by the fuel cell designer in combination with various factors, such as the service life of the system. The determined optimal working point must satisfy that the net power generation efficiency of the fuel cell gradually decreases after the optimal working point, that is, the optimal working point is at the peak of the fuel cell efficiency curve and its right end. The relationship curve between the net output power of the fuel cell and its efficiency can be found in Chinese patent CN108539231B Figure 3 Since the fuel cell may have high potential corrosion in the range where its net output efficiency increases, the above requirements for determining the optimal operating point of the fuel cell are basically in line with general actual conditions.

[0089] In addition, the fuel cell should also include the function of collecting the average voltage of the stack and communicating with the main controller; the chemical energy storage battery must have a battery management system that can calculate its SOC value in real time and have the function of communicating with the main controller; the functional requirements of the energy storage inverter (such as grid connection and off-grid connection) are consistent with the system design goals, and have the function of communicating with the main controller. For the user's required power, the main controller determines the start and stop and working point of the fuel cell based on the required power, the SOC value of the energy storage battery and the performance attenuation of each fuel cell at a series of fixed working points in its design. For a small part of the power that is inconsistent with the user's final fuel cell power generation, the chemical energy storage battery configured by the system automatically absorbs or supplements it, and finally achieves a balance between the required power and the system power generation, and the system operates normally.

[0090] Example 2

[0091] This embodiment is based on embodiment 1:

[0092] This embodiment provides a multi-module fuel cell coordinated power generation control method, including:

[0093] Before each fuel cell is started, the performance decay rate of each fuel cell at each working point is calculated;

[0094] Determine the charging and discharging requirements of the chemical energy storage battery according to the SOC value of the chemical energy storage battery;

[0095] According to the required power, based on the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of each fuel cell at the optimal working point, calculate and determine the number of fuel cells that need to be started;

[0096] The performance decay rates of the optimal working points of each fuel cell are sorted, and the fuel cell with the lower performance decay rate at the optimal working point is started first;

[0097] The working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell are calculated, and the working points in the working point combination are allocated to the corresponding fuel cells.

[0098] The method of this embodiment is based on a series of fixed working point fuel cells. The average node voltage of each working point stack collected by each fuel cell is used to calculate the performance decay rate of each current working point, and this is used as an important basis for starting and stopping each fuel cell and setting each fuel cell working point. For a small part of the power that is inconsistent with the required power of the final fuel cell, the chemical energy storage battery configured by the system automatically consumes or supplements it.

[0099] Preferably, calculating the performance decay rate of each fuel cell at each operating point includes:

[0100] Before each fuel cell is put into operation, the initial average voltage and net output power of the stack of each fuel cell at a series of operating points are collected, that is, the average voltage and net output power of the stack of each fuel cell at a series of operating points are collected. 1 , I 2 ,…,I N The average cell voltage V(t0) at 1， V(t0)2,…,V(t0) N and the net output power is P(t0) 1， P(t0)2,…,P(t0) N , where N is the number of fuel cell operating points; if the same type of fuel cell is used in the project, the same initial stack average voltage and net output power can be used;

[0101] After the fuel cell is put into operation and actually generates electricity, the current average cell voltage V(t) of each fuel cell at a series of operating points is collected. 1， V(t)2,…,V(t) N When collecting the average node voltage of the battery stack at the same working point, the collection time point must be kept consistent with the collection time of the initial average node voltage of the battery stack. The average node voltage collection process of the battery stack can be referred to Figure 2 ;

[0102] According to the average voltage value of the fuel cell stack at each operating point when each fuel cell last operated, update the performance decay rate σ(t) of each fuel cell at each operating point. n =(V(t0) n -V(t) n ) / V(t0) n , where n = 1, 2,…, N.

[0103] In this embodiment, according to the SOC value of the chemical energy storage battery, it is determined whether the chemical energy storage battery needs to be charged (BMS_Charge=1), whether charging is prohibited (BMS_Charge=-1), or whether it can be charged and discharged (BMS_Charge=0). Preferably, in order to reduce the impact of the change in the SOC value of the chemical energy storage battery on the stable operation of the fuel cell, a double hysteresis interval can be used in the judgment. The relationship between the double hysteresis interval of the chemical energy storage battery charge and discharge demand (BMS_Charge) and the SOC value of the chemical energy storage battery is as follows: Figure 3 As shown in the figure, the discharge prohibition threshold, hysteresis point threshold and charge prohibition threshold are determined by the implementer of the patent of the present invention according to needs.

[0104] Preferably, according to the required power, based on the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of each fuel cell at the optimal working point, the number of fuel cells to be started is calculated and determined, including:

[0105] Calculate the sum of the net output power of each fuel cell at the optimal working point under different current startup numbers:

[0106]

[0107] In the formula, is the current performance decay rate of each fuel cell at the optimal operating point, In particular, the initial net output power of each fuel cell at the optimal operating point, and satisfying (Those with lower performance decay rates will be started first); j = 1, 2, ..., M, where M is the total number of fuel cells in the system;

[0108] Determine the number of fuel cells that need to be started. At this time, the following situations exist:

[0109] a) If Then start all fuel cells;

[0110] b) If When the chemical energy storage battery charge and discharge demand BMS_Charge=1, start one fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, do not start the fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, start one fuel cell or do not start the fuel cell;

[0111] c) If it is not the case a) and b), then there must be a value k such that Established; when the chemical energy storage battery charge and discharge demand BMS_Charge = 1 or 0, start k+1 fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = -1, start k fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = 0, start k+1 or k fuel cells, where k = 1, 2, …, M-1.

[0112] Preferably, calculating the working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell, and allocating the working point in the working point combination to the corresponding fuel cell includes:

[0113] If the number of fuel cells started is less than M, each started fuel cell is directly set to operate at its optimal working point;

[0114] When all fuel cells are started, if the load power is greater than or equal to the sum of the maximum output power of all fuel cells, that is, Then all fuel cells work at their highest output power working point; if the load power is less than the sum of the maximum output powers of all fuel cells, then there must be an operating point x such that the following equation holds true:

[0115]

[0116] Wherein, a=0,1,…,M-1; x=1,2,…,N-1;

[0117] When the chemical energy storage battery charge and discharge demand BMS_Charge = 1, the target scheduling working point combination is:

[0118]

[0119] When the chemical energy storage battery charge and discharge demand BMS_Charge=-1, the target scheduling working point combination is:

[0120]

[0121] When the chemical energy storage battery charge and discharge demand BMS_Charge=0, the target scheduling working point combination selects the target scheduling working point combination of BMS_Charge=0 or BMS_Charge=1;

[0122] Calculate the operating point I of each fuel cell x+1 and I x The relative net output power loss is:

[0123]

[0124] In the formula, and Respectively represent the fuel cells at the working point I x+1 and I x Performance decay rate, i = 1, 2, ..., M;

[0125] Based on this, this embodiment provides a relatively low loss priority allocation method, which allocates the working point I x+1 Prioritize the allocation to the fuel cell with the lowest relative net output power loss among all unallocated fuel cell modules, and set the operating point I x to the remaining fuel cells.

[0126] If based on Figure 4 The number of fuel cells and their performance decay rates at various operating points are input (the bold columns in the figure indicate the optimal operating point columns). Figure 5 It can be seen that compared with the existing high / low power working point loss priority allocation method, the relative loss priority allocation method of this embodiment makes the system net output power loss lower and has higher efficiency.

[0127] It should be noted that the high power working point loss low priority allocation method, that is, for each fuel cell working point I x+1 The performance attenuation rate is sorted, and the working point I x+1Assigned to the fuel cell with the lowest performance decay rate among all unassigned fuel cell modules, and set the operating point I x Assigned to all remaining unassigned fuel cells, corresponding to Figure 5 HP Operation Point First curve in the middle; low power operation point loss low priority allocation method, that is, for each fuel cell operation point I x The performance attenuation rate is sorted, and the working point I x Assigned to the fuel cell with the lowest performance decay rate among all unassigned fuel cell modules, and set the operating point I x+1 Assigned to all remaining unassigned fuel cells, corresponding to Figure 5 LP Operation PointFirst curve in the figure.

[0128] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present 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 the present application.

Claims

1. A multi-module fuel cell coordinated power generation control method, characterized in that: include: Before each fuel cell is started, the performance decay rate of each fuel cell at each working point is calculated; Determine the charging and discharging requirements of the chemical energy storage battery according to the SOC value of the chemical energy storage battery; According to the required power, based on the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of each fuel cell at the optimal working point, calculate and determine the number of fuel cells that need to be started; The performance decay rates of the optimal working points of each fuel cell are sorted, and the fuel cell with the lower performance decay rate at the optimal working point is started first; The working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell are calculated, and the working points in the working point combination are allocated to the corresponding fuel cells.

2. A multi-module fuel cell coordinated power generation control method according to claim 1, characterized in that: The calculating the performance decay rate of each fuel cell at each operating point includes: Before each fuel cell is put into operation, the initial average voltage and net output power of the stack of each fuel cell at a series of operating points are collected, that is, the average voltage and net output power of the stack of each fuel cell at a series of operating points are collected. 1 , I 2 ,…,I N The average cell voltage V(t0) at 1， V(t0)2,…,V(t0) N And the net output power is P(t0) 1， P(t0)2,…,P(t0) N , where N is the number of fuel cell operating points; After the fuel cell is put into operation and actually generates electricity, the current average cell voltage V(t) of each fuel cell at a series of operating points is collected. 1， V(t)2,…,V(t) N ; According to the average voltage value of the fuel cell stack at each operating point when each fuel cell last operated, update the performance decay rate σ(t) of each fuel cell at each operating point. n =(V(t0) n -V(t) n ) / V(t0) n , where n = 1, 2,…, N.

3. A multi-module fuel cell coordinated power generation control method according to claim 2, characterized in that: The step of determining the charge and discharge requirements of the chemical energy storage battery based on the SOC value of the chemical energy storage battery includes: According to the SOC value of the chemical energy storage battery, the charge and discharge demand of the chemical energy storage battery is judged based on the dual hysteresis interval, and the dual hysteresis interval includes a discharge prohibition threshold, a hysteresis point threshold and a charge prohibition threshold; when the chemical energy storage battery charge and discharge demand BMS_Charge=1, it means that charging is required; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, it means that charging is prohibited; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, it means that charging and discharging are possible.

4. A multi-module fuel cell coordinated power generation control method according to claim 3, characterized in that: The method of calculating and determining the number of fuel cells to be started based on the required power, the charging and discharging requirements of the chemical energy storage battery and the relationship between the required power and the net output power of each fuel cell at the optimal working point, includes: Calculate the sum of the net output power of each fuel cell at the optimal working point under different current startup numbers: In the formula, is the current performance decay rate of each fuel cell at the optimal operating point, In particular, the initial net output power of each fuel cell at the optimal operating point, and satisfying j=1,2,…,M, M is the total number of fuel cells in the system; Determine the number of fuel cells that need to be started. At this time, the following situations exist: a) If Then start all fuel cells; b) If When the chemical energy storage battery charge and discharge demand BMS_Charge=1, start one fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, do not start the fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, start one fuel cell or do not start the fuel cell; c) If it is not the case a) and b), then there must be a value k such that Established; when the chemical energy storage battery charge and discharge demand BMS_Charge = 1, start k+1 fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = -1, start k fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = 0, start k+1 or k fuel cells, where k = 1, 2, …, M-1.

5. A multi-module fuel cell coordinated power generation control method according to claim 4, characterized in that: The calculating the working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell, and allocating the working point in the working point combination to the corresponding fuel cell, includes: If the number of fuel cells started is less than M, each started fuel cell is directly set to operate at its optimal working point; When all fuel cells are started, if the load power is greater than or equal to the sum of the maximum output power of all fuel cells, that is, Then all fuel cells work at their highest output power working point; if the load power is less than the sum of the maximum output power of all fuel cells, then in this case there must be an operating point x such that the following equation holds true: Wherein, a=0,1,…,M-1; x=1,2,…,N-1; When the chemical energy storage battery charge and discharge demand BMS_Charge = 1, the target scheduling working point combination is: When the chemical energy storage battery charge and discharge demand BMS_Charge=-1, the target scheduling working point combination is: When the chemical energy storage battery charge and discharge demand BMS_Charge=0, the target scheduling working point combination selects the target scheduling working point combination of BMS_Charge=0 or BMS_Charge=1; Calculate the operating point I of each fuel cell x+1 and I x The relative net output power loss is: In the formula, and Respectively represent the fuel cells at the working point I x+1 and I x Performance decay rate, i = 1, 2, ..., M; Set the working point I x+1 Prioritize the allocation to the fuel cell with the lowest relative net output power loss among all unallocated fuel cell modules, and set the operating point I x to the remaining fuel cells.

6. A multi-module fuel cell collaborative power generation system, characterized in that: It includes a main controller, a chemical energy storage battery and a plurality of fuel cells. The main controller controls the chemical energy storage battery and the fuel cells through communication. The fuel cells are connected to the chemical energy storage battery through a DC combiner cabinet. The main controller includes: The performance decay rate calculation module is configured to calculate the performance decay rate of each fuel cell at each operating point before each fuel cell is started; A charge and discharge demand determination module is configured to determine the charge and discharge demand of the chemical energy storage battery according to the SOC value of the chemical energy storage battery; The fuel cell startup quantity determination module is configured to calculate and determine the number of fuel cells that need to be started based on the required power, the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of the optimal working point of each fuel cell; A fuel cell startup priority judgment module is configured to sort the optimal working point performance decay rates of each fuel cell, and a fuel cell with a lower optimal working point performance decay rate is started first; The fuel cell startup execution module is configured to calculate the working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell, and allocate the working point in the working point combination to the corresponding fuel cell.

7. A multi-module fuel cell coordinated power generation system according to claim 6, characterized in that: In the performance decay rate calculation module, the performance decay rate of each fuel cell at each operating point is calculated, including: Before each fuel cell is put into operation, the initial average voltage and net output power of the stack of each fuel cell at a series of operating points are collected, that is, the average voltage and net output power of the stack of each fuel cell at a series of operating points are collected. 1 , I 2 ,…,I N The average cell voltage V(t0) at 1， V(t0)2,…,V(t0) N And the net output power is P(t0) 1， P(t0)2,…,P(t0) N , where N is the number of fuel cell operating points; After the fuel cell is put into operation and actually generates electricity, the current average cell voltage V(t) of each fuel cell at a series of operating points is collected. 1， V(t)2,…,V(t) N ; According to the average voltage value of the fuel cell stack at each operating point when each fuel cell last operated, update the performance decay rate σ(t) of each fuel cell at each operating point. n =(V(t0) n -V(t) n ) / V(t0) n , where n = 1, 2,…, N.

8. A multi-module fuel cell coordinated power generation system according to claim 7, characterized in that: In the charging and discharging demand judgment module, the charging and discharging demand of the chemical energy storage battery is determined based on the SOC value of the chemical energy storage battery, including: According to the SOC value of the chemical energy storage battery, the charge and discharge demand of the chemical energy storage battery is judged based on the dual hysteresis interval, and the dual hysteresis interval includes a discharge prohibition threshold, a hysteresis point threshold and a charge prohibition threshold; when the chemical energy storage battery charge and discharge demand BMS_Charge=1, it means that charging is required; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, it means that charging is prohibited; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, it means that charging and discharging are possible.

9. A multi-module fuel cell coordinated power generation system according to claim 8, characterized in that: In the fuel cell startup quantity judgment module, the number of fuel cells to be started is calculated and judged according to the required power, based on the charging and discharging requirements of the chemical energy storage battery and its relationship with the net output power of the optimal working point of each fuel cell, including: Calculate the sum of the net output power of each fuel cell at the optimal working point under different current startup numbers: In the formula, is the current performance decay rate of each fuel cell at the optimal operating point, P i op (t0) is the initial net output power of each fuel cell at the optimal operating point, and satisfies j=1,2,…,M, M is the total number of fuel cells in the system; Determine the number of fuel cells that need to be started. At this time, the following situations exist: a) If Then start all fuel cells; b) If 0 <P req (t)≤P1 op (t), when the chemical energy storage battery charge and discharge demand BMS_Charge=1, start one fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=-1, do not start the fuel cell; when the chemical energy storage battery charge and discharge demand BMS_Charge=0, start one fuel cell or do not start the fuel cell; c) If it is not the case a) and b), then there must be a value k such that Established; when the chemical energy storage battery charge and discharge demand BMS_Charge = 1, start k+1 fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = -1, start k fuel cells; when the chemical energy storage battery charge and discharge demand BMS_Charge = 0, start k+1 or k fuel cells, where k = 1, 2, …, M-1.

10. A multi-module fuel cell coordinated power generation system according to claim 9, characterized in that: In the fuel cell startup execution module, the working point combination of each fuel cell and the corresponding relationship between each working point in the working point combination and each fuel cell are calculated, and the working point in the working point combination is allocated to the corresponding fuel cell, including: If the number of fuel cells started is less than M, each started fuel cell is directly set to operate at its optimal working point; When all fuel cells are started, if the load power is greater than or equal to the sum of the maximum output power of all fuel cells, that is, Then all fuel cells work at their highest output power working point; if the load power is less than the sum of the maximum output power of all fuel cells, then in this case there must be an operating point x such that the following equation holds true: Wherein, a=0,1,…,M-1; x=1,2,…,N-1; When the chemical energy storage battery charge and discharge demand BMS_Charge = 1, the target scheduling working point combination is: When the chemical energy storage battery charge and discharge demand BMS_Charge=-1, the target scheduling working point combination is: When the chemical energy storage battery charge and discharge demand BMS_Charge=0, the target scheduling working point combination selects the target scheduling working point combination of BMS_Charge=0 or BMS_Charge=1; Calculate the operating point I of each fuel cell x+1 and I x The relative net output power loss is: In the formula, and Respectively represent the fuel cells at the working point I x+1 and I x Performance decay rate, i = 1, 2, ..., M; Set the working point I x+1 Prioritize the allocation to the fuel cell with the lowest relative net output power loss among all unallocated fuel cell modules, and set the operating point I x to the remaining fuel cells.

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