Coordinated optimization control method based on voltage stability and multi-stack performance consistency

Abstract

The invention discloses a coordinated optimization control method based on voltage stability and multi-stack performance consistency, and the method comprises the steps: building a fuel cell voltage recession function through employing a quantitative weighted estimation method according to the influence of traction conditions of different scenes on the voltage recession of a fuel cell, and representing the recession rate of each fuel cell; according to the decline of each fuel cell, adopting an attenuation compensation distribution strategy to distribute the reference fluctuation power of each fuel cell converter in real time, and obtaining the actual output power of each fuel cell converter; based on a dynamic impedance simulation technology, the output power of each converter of a multi-stack fuel cell is coupled with a bus voltage, and the relationship between a droop coefficient and system stability is analyzed to realize autonomous balance of the system; based on the dynamic error correction principle, a multi-dimensional control regulator is adopted to control the system voltage deviation, the system bus voltage stability is ensured, the electric pile performance of the multi-pile fuel cell is kept consistent, the stable and long-life operation of the multi-pile fuel cell system under the complex working condition is met, the robustness is enhanced, and the service time is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a coordinated optimization control method based on voltage stability and multi-stack performance consistency. Background Art

[0002] In order to reduce the environmental pollution caused by the combustion of traditional fossil fuels, it is crucial to actively promote energy conservation and emission reduction actions and accelerate the transformation of clean energy. Hydrogen fuel cells, as a device that can convert hydrogen energy into electrical energy, have the advantages of being clean, pollution-free, and efficient. They have been widely used in aviation, ships, microgrids, rail transit vehicles and other fields. In addition, with the advancement of fuel cell technology and the growth of market demand, multi-stack fuel cell systems have emerged. They are composed of multiple single fuel cells in parallel and are more efficient, flexible, and reliable.

[0003] However, the introduction of multiple fuel cells has brought new challenges in control and management. When operating in a complex environment, the different operating conditions of each fuel cell stack will lead to differences in their performance. At the same time, the life of a multi-stack fuel cell system is determined by the fuel cells with poor service performance. Therefore, the different operating conditions of each fuel cell will lead to a decrease in the overall stability of the multi-stack fuel cell system, reducing the overall life of the system.

[0004] At present, most of the research on coordinated optimization control of multiple fuel cells focuses only on improving the efficiency of the fuel cell system or reducing hydrogen consumption, and regards the parameters of each stack as consistent. It does not reflect the optimization ability of the control strategy when the fuel cell performance declines, which is not conducive to the long-term operation of the overall system. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a coordinated optimization control method based on voltage stability and multi-stack performance consistency to solve the problem of inconsistent performance of each stack of multiple fuel cells, minimize the differences between each stack as much as possible, and ensure the stability of the system bus voltage while achieving the end of the service life of each stack of multiple fuel cells at the same time, thereby extending the overall service time of the system.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a coordinated optimization control method based on voltage stability and multi-stack performance consistency, comprising the steps of:

[0007] Step 1: According to the influence of different traction conditions on the fuel cell voltage decay, the fuel cell voltage decay function is established by using the quantitative weighted estimation method, and the actual decay rate of each stack voltage and the maximum allowable voltage decay rate are used to indirectly characterize the life decay rate D of each fuel cell. FC,i ;

[0008] Step 2: According to the degradation rate D of each fuel cell FC,i, using the attenuation compensation allocation strategy to allocate the reference fluctuating power ΔP of each fuel cell converter dc,i , and then the actual output power P of each fuel cell converter is obtained dc,i ;

[0009] Step 3: Based on the dynamic impedance simulation technology, the output power of each converter of multiple fuel cell stacks is coupled with the bus voltage, and the droop coefficient R of each stack is analyzed. droopi The stable relationship with the system realizes the autonomous balance of the system;

[0010] Step 4: Based on the principle of dynamic error correction, a multi-dimensional control regulator is used to control the system voltage deviation to ensure the stability of the system bus voltage.

[0011] Furthermore, the fuel cell voltage decay function in step 1 is:

[0012]

[0013] Among them, U d,i is the performance decay rate of the i-th fuel cell during operation; γ 1,i is the duration of the i-th fuel cell operating in the high power range, γ 2,i is the duration of the i-th fuel cell operating in the low power range, γ 3,i is the load variation duration of the i-th fuel cell, γ 4,i is the number of starts and stops of the i-th fuel cell; D 1,i is the stack aging rate of the i-th fuel cell when operating in the high power range, D 2,i is the stack aging rate of the i-th fuel cell when operating in the low power range, D 3,i is the stack aging rate of the i-th fuel cell when it is running under variable load conditions, D 4,i are respectively the stack aging rates of the i-th fuel cell during start-stop operation.

[0014] Furthermore, it is assumed that the high and low power limit values ​​of the fuel cell and the real-time output power are linearly related to the aging loss of the fuel cell, and only one start-stop, i.e., D 4,i =1, then the D 1,i , D 2,i , D 3,i It is expressed as:

[0015]

[0016] Among them, d high Indicates the aging attenuation rate of the battery stack per kilowatt at high power, d low Indicates the aging attenuation rate of the battery stack in units of kilowatt at low power, d loadIndicates the aging attenuation rate of the battery stack per kilowatt under normal power, P FCi_high represents the critical value of high power of the i-th fuel cell, P FCi_low represents the critical value of low power of the i-th fuel cell, P FCi_max represents the maximum output power of the i-th fuel cell, and P FCi_min Represent the minimum output power of the i-th fuel cell, P FCi (t+1) represents the instantaneous output power of the i-th fuel cell at time t+1, and P FCi (t) represent the instantaneous output power of the i-th fuel cell at time t, and t is the working time of the fuel cell.

[0017] Furthermore, the fuel cell life decay rate is obtained according to the voltage decay function:

[0018] D FC,i =1-ΔU d,i ΔU d,i_max ;

[0019] Among them, ΔU d,i_max is the maximum allowable voltage degradation rate of the fuel cell, which is 10% of the rated voltage of the fuel cell. FC,i The value range is 0 to 1, and D FC,i The smaller the value, the worse the performance of the fuel cell, and the closer it is to 1, the better the performance.

[0020] Furthermore, according to the degradation rate D of each fuel cell FC,i , using the attenuation compensation allocation strategy to allocate the reference fluctuating power ΔP of each fuel cell converter dc,i :

[0021] The assignment expression is:

[0022]

[0023] Among them, K ij represents the power fluctuation ratio between the ith converter and the jth converter, D FC,i With D FC,j Respectively represent the voltage decay degree of the i-th fuel cell and the j-th fuel cell, ΔP dc,i With ΔP dc,j They represent the output power fluctuation of the i-th converter and the j-th converter, ΔP load Indicates the load power change, P dc,i (t), P dc,i (t-1) represents the instantaneous power of the i-th converter at time t and time t-1, respectively, P dc,j (t), P dc,j(t-1) represents the instantaneous power of the j-th converter at time t and time t-1, respectively, P load (t), P load (t-1) represents the instantaneous power of the load at time t and time t-1 respectively.

[0024] Furthermore, each fuel cell converter outputs an actual power P dc,i The expression is:

[0025]

[0026] Among them, P dc,i (t) represents the output power of the i-th branch converter at time t, ΔP dc,i (t) represents the output power fluctuation of the i-th branch converter at time t.

[0027] Furthermore, in step 3, the dynamic impedance simulation technology realizes adaptive power distribution of each fuel cell by adding a virtual resistor. After adding the virtual resistor, the virtual resistance of each fuel cell is calculated by using the actual power output of each fuel cell converter using the droop curve of each fuel cell.

[0028] Furthermore, the droop curve expression is:

[0029]

[0030] Among them, V dc,1 With V dc,N is the output voltage of the 1st and Nth fuel cell converters, I dc,1 with I dc,N is the output current of the 1st and Nth fuel cell converters, R l,1 With R l,N is the line impedance of the first and Nth fuel cells, R droop1 With R droopN is the virtual impedance of the 1st and Nth fuel cell lines, V bus is the bus voltage.

[0031] Furthermore, the virtual impedance is obtained by using the droop curve and the actual output power of each fuel cell converter:

[0032]

[0033] in,

[0034]

[0035] Among them, V bus (t) is the bus voltage at time t, V dc,1 (t) and V dc,N(t) is the output voltage of the 1st and Nth fuel cell converters at time t, ψ1(t), ψ N (t),ψ i (t) are the mixed algebraic variables of the 1st, Nth, and i-th fuel cell converter loops at time t, R m (t) is the impedance algebraic variable at time t, R l,i(t) With R l,j(t) Respectively represent the line impedance of the i-th and j-th fuel cell converter loops at time t, R droopi(t) With R droopi(t) Respectively represent the virtual impedance of the i-th and j-th fuel cell converter loops at time t, R x1 (t), R xN (t), R xi (t) respectively represent the total line impedance of the 1st, Nth, and i-th fuel cell converter circuits at time t, R load is the load impedance.

[0036] Furthermore, in step 4, the multi-dimensional control regulator controls the deviation ΔV between the reference voltage and the actual voltage. ref,i , to ensure the stability of the system bus voltage; in addition, the multi-dimensional control regulator controls ΔV in three dimensions according to the dynamic error correction principle ref,i :

[0037]

[0038] Among them, K1, K2 and K3 represent the proportional, integral and differential gains respectively, e(t) is the error at time t, V dc,i * is the reference voltage of the i-th fuel cell converter; ΔV ref,i is the deviation between the reference voltage and the actual voltage of the ith fuel cell, and its fluctuation range should be less than 5% of the bus voltage; V bus is the bus voltage.

[0039] The beneficial effects of adopting this technical solution are:

[0040] The present invention discloses a coordinated optimization control method based on voltage stability and multi-stack performance consistency; firstly, according to the influence of traction conditions in different scenarios on fuel cell voltage decay, a fuel cell voltage decay function is established to indirectly characterize the decay rate of each fuel cell, and the reference fluctuating power of each fuel cell converter is allocated in real time according to the decay rate of each fuel cell, and then the actual output power of each fuel cell converter is obtained, thereby ensuring the consistency of fuel cell performance; secondly, using virtual resistance droop technology, the output power of each converter of multiple fuel cells is coupled with the bus voltage, and the system autonomous balance is achieved by analyzing the relationship between the droop coefficient and the system stability; then, the deviation between the reference voltage and the actual voltage is controlled by a proportional-integral-differential controller to ensure the stability of the system bus voltage and achieve safe and stable operation of the system; finally, under the action of this method, the performance of each stack of multiple fuel cells remains consistent, meeting the stable and long-life operation requirements of the multi-stack fuel cell system under complex conditions, enhancing the system robustness, and extending the overall service life of the system.

[0041] The present invention establishes a fuel cell voltage decay function according to the influence of traction conditions in different scenarios on the fuel cell to measure the fuel cell life decay rate, and has the advantages of high reliability and good feasibility.

[0042] The present invention adopts virtual droop technology control to realize adaptive control of the power of each fuel cell, and the fuel cells do not need to communicate with each other, thus realizing independent control.

[0043] The present invention adopts a proportional-integral-differential controller to control the fuel cell bus voltage in real time, thereby ensuring the stability of the system bus voltage and ensuring the safe and stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of a coordinated optimization control method based on voltage stability and multi-stack performance consistency of the present invention;

[0045] Figure 2 A topological structure diagram of a multi-stack fuel cell system after adding virtual resistance in an embodiment of the present invention;

[0046] Figure 3 It is a control block diagram of a coordinated optimization control method based on voltage stability and multi-stack performance consistency in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described below with reference to the accompanying drawings.

[0048] In this embodiment, see Figure 1 As shown, the present invention proposes a coordinated optimization control method based on voltage stability and multi-stack performance consistency, comprising the steps of:

[0049] Step 1: According to the influence of different traction conditions on the fuel cell voltage decay, the fuel cell voltage decay function is established by using the quantitative weighted estimation method, and the actual decay rate of each stack voltage and the maximum allowable voltage decay rate are used to indirectly characterize the life decay rate D of each fuel cell. FC,i ;

[0050] Step 2: According to the degradation rate D of each fuel cell FC,i , using the attenuation compensation allocation strategy to allocate the reference fluctuating power ΔP of each fuel cell converter dc,i , and then the actual output power P of each fuel cell converter is obtained dc,i ;

[0051] Step 3: Based on the dynamic impedance simulation technology, the output power of each converter of multiple fuel cell stacks is coupled with the bus voltage, and the droop coefficient R of each stack is analyzed. droopi The stable relationship with the system realizes the autonomous balance of the system;

[0052] Step 4: Based on the principle of dynamic error correction, a multi-dimensional control regulator is used to control the system voltage deviation to ensure the stability of the system bus voltage.

[0053] As an optimization solution of the above embodiment, the fuel cell voltage decay function described in step 1 is:

[0054]

[0055] Among them, U d,i is the performance decay rate of the i-th fuel cell during operation; γ 1,i is the duration of the i-th fuel cell operating in the high power range, γ 2,i is the duration of the i-th fuel cell operating in the low power range, γ 3,i is the load variation duration of the i-th fuel cell, γ 4,i is the number of starts and stops of the i-th fuel cell; D 1,i is the stack aging rate of the i-th fuel cell when operating in the high power range, D 2,i is the stack aging rate of the i-th fuel cell when operating in the low power range, D 3,i is the stack aging rate of the i-th fuel cell when it is running under variable load conditions, D 4,i are respectively the stack aging rates of the i-th fuel cell during start-stop operation.

[0056] Assume that the high and low power limit values ​​of the fuel cell and the real-time output power are linearly related to the fuel cell aging loss, and only consider one start and stop, i.e., D 4,i =1, then the D 1,i , D 2,i , D 3,i It is expressed as:

[0057]

[0058] Among them, d high Indicates the aging attenuation rate of the battery stack per kilowatt at high power, d low Indicates the aging attenuation rate of the battery stack in units of kilowatt at low power, d load Indicates the aging attenuation rate of the battery stack per kilowatt under normal power, P FCi_high represents the critical value of high power of the i-th fuel cell, P FCi_low represents the critical value of low power of the i-th fuel cell, P FCi_max represents the maximum output power of the i-th fuel cell, and P FCi_min Represent the minimum output power of the i-th fuel cell, P FCi (t+1) represents the instantaneous output power of the i-th fuel cell at time t+1, and P FCi (t) represent the instantaneous output power of the i-th fuel cell at time t, and t is the working time of the fuel cell.

[0059] As an optimization solution of the above embodiment, the fuel cell life decay rate is obtained according to the voltage decay function:

[0060] D FC,i =1-ΔU d,i / ΔU d,i_max ;

[0061] Among them, ΔU d,i_max is the maximum allowable voltage degradation rate of the fuel cell, which is 10% of the rated voltage of the fuel cell. FC,i The value range is 0 to 1, and D FC,i The smaller the value, the worse the performance of the fuel cell, and the closer it is to 1, the better the performance.

[0062] According to the degradation rate D of each fuel cell FC,i , using the attenuation compensation allocation strategy to allocate the reference fluctuating power ΔP of each fuel cell converter dc,i :

[0063] The assignment expression is:

[0064]

[0065] Among them, K ij represents the power fluctuation ratio between the ith converter and the jth converter, D FC,i With D FC,j Respectively represent the voltage decay degree of the i-th fuel cell and the j-th fuel cell, ΔP dc,i With ΔP dc,jThey represent the output power fluctuation of the i-th converter and the j-th converter, ΔP load Indicates the load power change, P dc,i (t), P dc,i (t-1) represents the instantaneous power of the i-th converter at time t and time t-1, respectively, P dc,j (t), P dc,j (t-1) represents the instantaneous power of the j-th converter at time t and time t-1, respectively, P load (t), P load (t-1) represents the instantaneous power of the load at time t and time t-1 respectively.

[0066] The actual power output P of each fuel cell converter is dc,i The expression is:

[0067]

[0068] Among them, P dc,i (t) represents the output power of the i-th branch converter at time t, ΔP dc,i (t) represents the output power fluctuation of the i-th branch converter at time t.

[0069] As an optimization solution of the above embodiment, Figure 2 As shown, in step 3, the dynamic impedance simulation technology realizes the adaptive power distribution of each fuel cell by adding a virtual resistor. After adding the virtual resistor, the actual power output of each fuel cell converter is used to calculate the virtual resistance of each fuel cell using the droop curve of each fuel cell.

[0070] The droop curve expression is:

[0071]

[0072] Among them, V dc,1 With V dc,N is the output voltage of the 1st and Nth fuel cell converters, I dc,1 with I dc,N is the output current of the 1st and Nth fuel cell converters, R l,1 With R l,N is the line impedance of the first and Nth fuel cells, R droop1 With R droopN is the virtual impedance of the 1st and Nth fuel cell lines, V bus is the bus voltage.

[0073] The virtual impedance is obtained by using the droop curve and the actual output power of each fuel cell converter:

[0074]

[0075] in,

[0076]

[0077] Among them, V bus (t) is the bus voltage at time t, V dc,1 (t) and V dc,N (t) is the output voltage of the 1st and Nth fuel cell converters at time t, ψ1(t), ψ N (t),ψ i (t) are the mixed algebraic variables of the 1st, Nth, and i-th fuel cell converter loops at time t, R m (t) is the impedance algebraic variable at time t, R l,i(t) With R l,j(t) Respectively represent the line impedance of the i-th and j-th fuel cell converter loops at time t, R droopi(t) With R droopi(t) Respectively represent the virtual impedance of the i-th and j-th fuel cell converter loops at time t, R x1 (t), R xN (t), R xi (t) respectively represent the total line impedance of the 1st, Nth, and i-th fuel cell converter circuits at time t, R load is the load impedance.

[0078] As an optimization solution of the above embodiment, adding the virtual resistor will cause the system bus voltage to decrease, and a multi-dimensional control regulator is used to control the deviation ΔV between the reference voltage and the actual voltage. ref,i , to ensure the stability of the system bus voltage; in addition, the multi-dimensional control regulator controls ΔV in three dimensions according to the dynamic error correction principle ref,i :

[0079]

[0080] Among them, K1, K2 and K3 represent the proportional, integral and differential gains respectively, e(t) is the error at time t, V dc,i * is the reference voltage of the i-th fuel cell converter; ΔV ref,i is the deviation between the reference voltage and the actual voltage of the ith fuel cell, and its fluctuation range should be less than 5% of the bus voltage; V bus is the bus voltage.

[0081] In this embodiment, the control method is adopted to ensure that the performance of multiple fuel cell stacks is consistent, the system bus voltage remains stable, and each stack can reasonably allocate power according to the degree of degradation, ultimately making the fuel cell stack with a larger degree of degradation have smaller power fluctuations; at the same time, the control method of step 3 and step 4 only requires the fuel cell reference power given in step 2, and then it can be achieved by measuring the local voltage and current, without the need for communication between the stacks.

[0082] Specifically, the control block diagram of the coordinated optimization control method based on voltage stability and multi-stack performance consistency is as follows: Figure 3 shown.

[0083] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A coordinated optimization control method based on voltage stability and multi-stack performance consistency, characterized in that: Includes steps: Step 1: According to the influence of different traction conditions on the fuel cell voltage decay, the fuel cell voltage decay function is established by using the quantitative weighted estimation method, and the actual decay rate of each stack voltage and the maximum allowable voltage decay rate are used to indirectly characterize the life decay rate D of each fuel cell. FC,i ; Step 2: According to the degradation rate D of each fuel cell FC,i , using the attenuation compensation allocation strategy to allocate the reference fluctuating power ΔP of each fuel cell converter dc,i , and then the actual output power P of each fuel cell converter is obtained dc,i ; Step 3: Based on the dynamic impedance simulation technology, the output power of each converter of multiple fuel cell stacks is coupled with the bus voltage, and the droop coefficient R of each stack is analyzed. droopi The stable relationship with the system realizes the autonomous balance of the system; Step 4: Based on the principle of dynamic error correction, a multi-dimensional control regulator is used to control the system voltage deviation to ensure the stability of the system bus voltage.

2. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 1 is characterized in that: The fuel cell voltage decay function described in step 1 is: Among them, U d,i is the performance decay rate of the i-th fuel cell during operation; γ 1,i is the duration of the i-th fuel cell operating in the high power range, γ 2,i is the duration of the i-th fuel cell operating in the low power range, γ 3,i is the load variation duration of the i-th fuel cell, γ 4,i is the number of starts and stops of the i-th fuel cell; D 1,i is the stack aging rate of the i-th fuel cell when operating in the high power range, D 2,i is the stack aging rate of the i-th fuel cell when operating in the low power range, D 3,i is the stack aging rate of the i-th fuel cell when it is running under variable load conditions, D 4,i are respectively the stack aging rates of the i-th fuel cell during start-stop operation.

3. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 2 is characterized in that: Assume that the high and low power limit values ​​of the fuel cell and the real-time output power are linearly related to the fuel cell aging loss, and only consider one start and stop, i.e., D 4,i =1, then the D 1,i , D 2,i , D 3,i It is expressed as: Among them, d high Indicates the aging attenuation rate of the battery stack per kilowatt at high power, d low Indicates the aging attenuation rate of the battery stack in units of kilowatt at low power, d load Indicates the aging attenuation rate of the battery stack per kilowatt under normal power, P FCi _ high represents the critical value of high power of the i-th fuel cell, P FCi_low represents the critical value of low power of the i-th fuel cell, P FCi_max represents the maximum output power of the i-th fuel cell, and P FCi_min Represent the minimum output power of the i-th fuel cell, P FCi (t+1) represents the instantaneous output power of the i-th fuel cell at time t+1, and P FCi (t) represent the instantaneous output power of the i-th fuel cell at time t, and t is the working time of the fuel cell.

4. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 2 is characterized in that: The fuel cell life decay rate is obtained based on the voltage decay function: D FC,i =1-ΔU d,i / D d,i_max ; Among them, ΔU d,i_max is the maximum allowable voltage degradation rate of the fuel cell, which is 10% of the rated voltage of the fuel cell. FC,i The value range is from 0 to 1, and D FC,i The smaller the value, the worse the performance of the fuel cell, and the closer it is to 1, the better the performance.

5. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 1 is characterized in that: According to the degradation rate D of each fuel cell FC,i , using the attenuation compensation allocation strategy to allocate the reference fluctuating power ΔP of each fuel cell converter dc,i : The assignment expression is: Among them, K ij represents the power fluctuation ratio of the ith converter to the jth converter, D FC,i With D FC,j Respectively represent the voltage decay degree of the i-th fuel cell and the j-th fuel cell, ΔP dc,i With ΔP dc,j They represent the output power fluctuation of the i-th converter and the j-th converter, ΔP load Indicates the load power change, P dc,i (t), P dc,i (t-1) represents the instantaneous power of the i-th converter at time t and time t-1, respectively, P dc,j (t), P dc,j (t-1) represents the instantaneous power of the jth converter at time t and time t-1, respectively, P load (t), P load (t-1) represents the instantaneous power of the load at time t and time t-1 respectively.

6. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 5 is characterized in that: The actual power output P of each fuel cell converter is dc,i The expression is: Among them, P dc,i (t) represents the output power of the i-th branch converter at time t, ΔP dc,i (t) represents the output power fluctuation of the i-th branch converter at time t.

7. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 1 is characterized in that: In step 3, the dynamic impedance simulation technology realizes the adaptive power distribution of each fuel cell by adding a virtual resistor. After adding the virtual resistor, the virtual resistance of each fuel cell is calculated by using the actual power output of each fuel cell converter using the droop curve of each fuel cell.

8. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 7 is characterized in that: The droop curve expression is: Among them, V dc,1 With V dc,N is the output voltage of the 1st and Nth fuel cell converters, I dc,1 with I dc,N is the output current of the 1st and Nth fuel cell converters, R l,1 With R l,N is the line impedance of the first and Nth fuel cells, R droop1 With R droopN is the virtual impedance of the 1st and Nth fuel cell lines, V bus is the bus voltage.

9. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 8 is characterized in that: The virtual impedance is obtained by using the droop curve and the actual output power of each fuel cell converter: in, Among them, V bus (t) is the bus voltage at time t, V dc,1 (t) and V dc,N (t) is the output voltage of the 1st and Nth fuel cell converters at time t, ψ1(t), ψ N (t),ψ i (t) are the mixed algebraic variables of the 1st, Nth, and i-th fuel cell converter loops at time t, R m (t) is the impedance algebraic variable at time t, R l,i(t) With R l,j(t) Respectively represent the line impedance of the i-th and j-th fuel cell converter loops at time t, R droopi(t) With R droopi(t) Respectively represent the virtual impedance of the i-th and j-th fuel cell converter loops at time t, R x1 (t), R xN (t), R xi (t) respectively represent the total line impedance of the 1st, Nth, and i-th fuel cell converter circuits at time t, R load is the load impedance.

10. The coordinated optimization control method based on voltage stability and multi-stack performance consistency according to claim 1 is characterized in that: In step 4, the multi-dimensional control regulator controls the deviation ΔV between the reference voltage and the actual voltage ref,i , to ensure the stability of the system bus voltage; in addition, the multi-dimensional control regulator controls ΔV in three dimensions according to the dynamic error correction principle ref,i : Among them, K1, K2 and K3 represent the proportional, integral and differential gains respectively, e(t) is the error at time t, V dc,i * is the reference voltage of the i-th fuel cell converter; ΔV ref,i is the deviation between the reference voltage and the actual voltage of the ith fuel cell, and its fluctuation range should be less than 5% of the bus voltage; V bus is the bus voltage.

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