Instantaneous temperature control method, system, device and storage medium for fuel cell

Abstract

The present invention relates to the field of fuel cell technology and discloses a method, system, device, and storage medium for instantaneous temperature control of a fuel cell. The method establishes a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell. The mechanism model includes a fuel cell stack, an exhaust combustion chamber, a heat exchanger, and corresponding temperature constraints. Dynamic load switching is performed within the mechanism model, and the optimal current switching time corresponding to the dynamic load switching is obtained by optimizing the optimal switching time. The method establishes a mechanism model for the SOFC system, simulates the instantaneous temperature of the system under load switching, and then proposes an optimal switching time optimization strategy and a two-step current switching strategy for system temperature failures under different switching conditions, thereby ensuring that the system maintains safe and efficient operation even in a dynamic switching state.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a method, system, device and storage medium for instantaneous temperature control of a solid oxide fuel cell. Background Art

[0002] The solid oxide fuel cell (SOFC) system is a highly coupled thermoelectric power generation system operating at high temperatures. The thermoelectric coupling is complex, and the high-temperature operating conditions (600-1000°C) place extremely high demands on SOFC materials. To ensure system safety, the temperature characteristics of the stack and the system are crucial. For the stack, the maximum operating temperature and temperature gradient must be limited to a certain operating range. If the internal stack temperature is too low, electrochemical reactions will not proceed. As the internal stack temperature increases, electrochemical reactions occur more readily, increasing power generation efficiency. However, excessively high internal stack temperatures or large temperature gradients can damage the stack and even cause the entire SOFC power generation system to shut down. Therefore, controlling the internal stack temperature and temperature gradient is crucial to system safety and affects stack output power. Excessive temperature differences at the stack inlet can easily cause stack deformation. The maximum temperature within the combustion chamber must maintain preheating capacity while remaining within the tolerances of the materials. Safe and controllable temperature is a prerequisite for stable and long-life operation of the entire SOFC system. However, due to the strong thermoelectric coupling characteristics and mechanism complexity of the SOFC system, the thermal safety control of the SOFC system has always been a research focus and difficulty in the SOFC field.

[0003] Currently, research on the thermal safety control of SOFC systems is diverse. However, due to the high experimental costs of SOFC systems, the difficulty of adding sensors within the stack, and poor system dynamic performance, current research still has many shortcomings. Most existing studies fail to fully consider the temperature constraints within the SOFC system. Existing studies generally analyze system performance through a single temperature constraint, rarely addressing comprehensive thermal safety constraints for the entire integrated system. Physically achievable quantitative analysis and control strategies are also lacking. Furthermore, most current control strategies fail to consider the transient temperature and power characteristics of the SOFC system under different load switching conditions. The transient temperature during load switching can cause system damage. Furthermore, system performance varies with different switching conditions, necessitating corresponding changes in control strategies. When loads are switched dynamically, traditional control schemes typically significantly reduce current switching speeds and shift operating parameters to suboptimal levels to ensure system temperature safety. This compromises system performance and power tracking time. Summary of the Invention

[0004] To address the above-mentioned technical problems, the present invention provides a model-based instantaneous temperature control method and system for solid oxide fuel cells, which can dynamically switch operating conditions for different SOFC systems. Through an optimal switching time optimization strategy and a two-step current switching strategy, the SOFC system can maintain safe and efficient operation even in a dynamic switching state.

[0005] In a first aspect, the present invention provides a method for controlling the instantaneous temperature of a fuel cell, the method comprising:

[0006] Establishing a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell, wherein the mechanism model includes a fuel cell stack, an exhaust gas combustion chamber, a heat exchanger, and temperature constraints corresponding to the model;

[0007] Dynamic load switching is performed in the mechanism model, and an optimal current switching time corresponding to the dynamic load switching is obtained by optimizing the optimal switching time, wherein the step of optimizing the optimal switching time includes:

[0008] According to the initial power and target power of the dynamic load switching, the current switching time, the switching time interval and the maximum switching time are set and input into the mechanism model;

[0009] performing dynamic load switching at the optimal operating point of the mechanism model according to the current switching time, and using the current switching time as the optimal current switching time if the current switching time meets a switching time condition, wherein the switching time condition includes that a corresponding system temperature during the dynamic load switching does not exceed the temperature constraint condition;

[0010] If the current switching time does not meet the switching time condition, the current switching time is added to the switching time interval to obtain a first current switching time. If the first current switching time is not greater than the maximum switching time, the switching time condition is used as an iteration condition, and the first current switching time is iteratively calculated to obtain a second current switching time, and the second current switching time is used as the optimal current switching time.

[0011] Furthermore, the step of establishing the mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell includes:

[0012] Based on the mechanism formulas of electrical characteristics, energy conservation and mass conservation, a mechanism model of solid oxide fuel cells is established;

[0013] The following formula is used to express the electrical characteristics of the stack in the mechanism model:

[0014]

[0015] The following formula is used to express the energy conservation of the battery stack:

[0016]

[0017]

[0018] The energy conservation of the exhaust combustion chamber in the mechanism model is expressed by the following formula:

[0019]

[0020] The following formula is used to express the mass conservation of the tail gas combustion chamber:

[0021]

[0022] The following formula is used to express the energy conservation of the heat exchanger in the mechanism model:

[0023]

[0024]

[0025] The following formula is used to express the mass conservation of the heat exchanger:

[0026]

[0027]

[0028] In the formula, the subscript stack represents the battery stack, the subscript afterburner represents the exhaust combustion chamber, the subscripts in and out represent input and output respectively, the superscripts hot and cold represent heat energy and cold energy respectively, the subscript cell represents the battery cell, n represents the number of battery cells, U represents voltage, P represents pressure, F represents Faraday's constant, K represents universal gas constant, T represents temperature, V represents volume, C represents specific heat capacity, ρ represents density, represents flow rate, h represents thermal enthalpy, R represents molar reaction rate, A represents area, △T represents the change in temperature, Indicates energy value, E 0 represents Nernst voltage, D represents current density, H2O represents water, H2 represents hydrogen, and i = [H20, H2, CH4, CO2, CO, N2, O2].

[0029] Furthermore, the temperature constraints of the mechanism model include constraints corresponding to the maximum temperature of the stack, the maximum temperature gradient of the stack, the temperature difference of the gas at the stack inlet, and the combustion chamber temperature;

[0030] The following formula is used to express the constraint condition of the maximum temperature of the stack:

[0031] Max.T PEN (K) = max{T stack (j)},j={1,2,...,J}

[0032] 873K≤Max.T PEN ≤1173K

[0033] The following formula is used to express the constraint condition of the maximum temperature gradient of the stack:

[0034] Max.|ΔT PEN |(K)=max|T stack (j+1)-T stack (j)|,

[0035] j={1,2,…,J-1}

[0036] Max.|ΔT PEN |≤8K / cm

[0037] The following formula is used to express the constraint condition of the gas temperature difference at the fuel cell inlet:

[0038]

[0039] ΔT inlet ≤200K

[0040] The following formula is used to express the constraints of the combustion chamber temperature:

[0041] 873K≤T B ≤1273K

[0042] In the formula, K represents the unit of temperature, T stack (j) represents the temperature of the jth node of the single-chip battery, J represents the total number of nodes divided during the single-chip battery modeling process, T inlet,air Indicates the stack inlet air temperature, Indicates the hydrogen temperature at the stack inlet.

[0043] Furthermore, if the first current switching time is greater than the maximum switching time, the optimal intermediate power corresponding to the dynamic load switching is obtained through two-step current switching, wherein the two-step current switching step includes:

[0044] According to the initial power and the target power, an initial intermediate power and a power switching interval are set and then input into the mechanism model;

[0045] performing the optimal switching time optimization for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power, respectively, to obtain the system temperature and power following time corresponding to the initial intermediate power;

[0046] adding the initial intermediate power to the power switching interval to obtain a first intermediate power, and iteratively calculating the first intermediate power according to an iteration condition to obtain a second intermediate power and the corresponding system temperature and the power following time, wherein the iteration condition is that the first intermediate power is less than the target power;

[0047] An optimal intermediate power is selected from the initial intermediate power and the second intermediate power according to the system temperature and the power following time.

[0048] Furthermore, the step of performing the optimal switching time optimization for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power, respectively, to obtain the system temperature and power following time corresponding to the initial intermediate power includes:

[0049] The switching stage from the initial power to the initial intermediate power is regarded as a high-power stage, and the switching stage from the initial intermediate power to the target power is regarded as a low-power stage. The optimal switching time is optimized for the high-power stage and the low-power stage respectively, to obtain the optimal current switching time for the high-power stage and the optimal current switching time for the low-power stage;

[0050] During the optimal current switching time in the high power stage and the optimal current switching time in the low power stage, dynamic load switching is performed at the optimal working point of the mechanism model to obtain the system temperature corresponding to the initial intermediate power and the power following time.

[0051] Furthermore, the step of selecting an optimal intermediate power from the initial intermediate power and the second intermediate power according to the system temperature and the power following time includes:

[0052] taking the initial intermediate power and the second intermediate power as third intermediate powers, comparing power following times corresponding to the third intermediate powers, and taking the third intermediate power with the shortest power following time as the optimal intermediate power;

[0053] If there are multiple power follow-up times with the same shortest time, the corresponding system temperatures are compared with the temperature constraint condition, and the third intermediate power corresponding to the system temperature farthest from the temperature constraint condition is used as the optimal intermediate power.

[0054] In a second aspect, the present invention provides a transient temperature control system for a fuel cell, the system comprising:

[0055] A mechanism model building module, for building a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell, wherein the mechanism model includes a fuel cell stack, an exhaust gas combustion chamber, a heat exchanger, and temperature constraints corresponding to the model;

[0056] An optimal switching time optimization module is used to perform dynamic load switching in the mechanism model and obtain an optimal current switching time corresponding to the dynamic load switching by optimizing the optimal switching time;

[0057] The optimal switching time optimization module includes a time parameter initialization module and a switching time optimization module;

[0058] The time parameter initialization module is used to set the current switching time, the switching time interval and the maximum switching time according to the initial power and the target power of the dynamic load switching and input them into the mechanism model;

[0059] The switching time optimization module is used to perform dynamic load switching at the optimal operating point of the mechanism model according to the current switching time. If the current switching time meets the switching time condition, the current switching time is used as the optimal current switching time. The switching time condition includes that the corresponding system temperature does not exceed the temperature constraint condition when the dynamic load switching is performed; if the current switching time does not meet the switching time condition, the current switching time is added to the switching time interval to obtain a first current switching time. If the first current switching time is not greater than the maximum switching time, the switching time condition is used as an iteration condition, the first current switching time is iteratively calculated to obtain a second current switching time, and the second current switching time is used as the optimal current switching time.

[0060] Furthermore, the system further comprises:

[0061] a two-step current switching module, configured to obtain an optimal intermediate power corresponding to the dynamic load switching by two-step current switching if the first current switching time is greater than the maximum switching time;

[0062] The two-step current switching module also includes a power parameter initialization module and an intermediate power optimization module;

[0063] The power parameter initialization module is used to set the initial intermediate power and the power switching interval according to the initial power and the target power and input them into the mechanism model;

[0064] The intermediate power optimization module is used to optimize the optimal switching time for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power, respectively, to obtain the system temperature and the power following time corresponding to the initial intermediate power; add the initial intermediate power to the power switching interval to obtain a first intermediate power, iteratively calculate the first intermediate power according to an iteration condition, to obtain a second intermediate power and the corresponding system temperature and power following time, wherein the iteration condition is that the first intermediate power is less than the target power; and select the optimal intermediate power from the initial intermediate power and the second intermediate power according to the system temperature and the power following time.

[0065] In a third aspect, an embodiment of the present invention further provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0066] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0067] The present invention provides a method, system, computer device, and storage medium for instantaneous temperature control of a fuel cell. This method fully considers the various switching conditions of a SOFC system and, based on the fundamental laws of dynamic instantaneous temperature, proposes an optimal switching time optimization strategy and a two-step current switching strategy for system temperature failures under different switching conditions. This strategy ensures safe and efficient system operation even under dynamic switching conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 1 is a flow chart of a method for controlling the instantaneous temperature of a fuel cell provided by an embodiment of the present invention;

[0069] Figure 2 is a schematic structural diagram of a mechanism model of a fuel cell provided by an embodiment of the present invention;

[0070] Figure 3 yes Figure 1 Flow chart of the optimal switching time search;

[0071] Figure 4 1 is a schematic diagram of a process of double-step current switching provided by an embodiment of the present invention;

[0072] Figure 5 1 is a schematic structural diagram of a transient temperature control system for a fuel cell provided by an embodiment of the present invention;

[0073] Figure 6 1 is a diagram showing the internal structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0074] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0075] See also Figure 1 A method for controlling the instantaneous temperature of a fuel cell according to a first embodiment of the present invention includes steps S10 to S20:

[0076] Step S10 , establishing a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell, wherein the mechanism model includes a fuel cell stack, an exhaust gas combustion chamber, a heat exchanger, and temperature constraints corresponding to the model.

[0077] The present invention is a model-based method for instantaneous temperature control of a solid oxide fuel cell (SOFC). Therefore, it is necessary to build a model of the SOFC system. In the embodiments of the present invention, a model of a 5kW SOFC system is preferably built under MATLAB / SIMULINK conditions to facilitate the description of the process of the present method.

[0078] First, models of each subcomponent are constructed based on the formulas of conservation of energy, conservation of mass, conservation of mole fraction, and mechanisms such as thermal radiation, heat conduction, and heat exchange. The subcomponents of the system model in this embodiment include the fuel cell stack, exhaust gas combustion chamber, and heat exchanger. Of course, a reformer can also be added to establish the model. The model in this embodiment is only a preferred embodiment.

[0079] After building the models of each sub-component, the sub-component models are assembled to form the mechanism model of the entire SOFC system. The model structure is as follows: Figure 2 As shown, the mechanism model is built with heat exchanger 1, fuel cell stack 2 and tail gas combustion chamber 3 as main sub-components. Mass flow meter 4, blower 5, splitter 6 and mixer 7 are also provided on the pipelines connecting the sub-components to provide fuel and air for the mechanism model from different pipeline inlets. The specific working process can be referred to Figure 2 The mechanism model will not be described in detail here.

[0080] according to Figure 2 The mechanism model shown in the figure, the mechanism formulas of each sub-component model are expressed using the following formulas:

[0081] The following formula is used to express the electrical characteristics of the battery stack:

[0082]

[0083] The following formula is used to express the energy conservation of the battery stack:

[0084]

[0085]

[0086] The energy conservation of the exhaust combustion chamber is expressed by the following formula:

[0087]

[0088] The following formula is used to express the mass conservation of the exhaust combustion chamber:

[0089]

[0090] The following formula is used to express the energy conservation of the heat exchanger:

[0091]

[0092]

[0093] The following formula is used to express the mass conservation of the heat exchanger:

[0094]

[0095]

[0096] In the formula, the subscript stack represents the battery stack, the subscript afterburner represents the exhaust combustion chamber, the subscripts in and out represent input and output respectively, the superscripts hot and cold represent heat energy and cold energy respectively, the subscript cell represents the battery cell, n represents the number of battery cells, U represents voltage, P represents pressure, F represents Faraday's constant, K represents universal gas constant, T represents temperature, V represents volume, C represents specific heat capacity, ρ represents density, represents flow rate, h represents thermal enthalpy, R represents molar reaction rate, A represents area, △T represents the change in temperature, Indicates energy value, E 0 represents Nernst voltage, D represents current density, H2O represents water, H2 represents hydrogen, and i = [H20, H2, CH4, CO2, CO, N2, O2].

[0097] For the SOFC system, the operating temperature has a great impact on its performance. If the temperature of the stack is too low, the SOFC electrochemical reaction will not proceed. If the temperature is too high, the stack will be damaged. If the maximum temperature gradient of the stack is too high or the temperature difference of the gas at the stack inlet is too large, the stack will be deformed or even damaged. If the combustion chamber temperature is too low, the heat exchanger will not be able to preheat the gas effectively. If the combustion chamber temperature is too high, the combustion chamber will be damaged. Therefore, from the perspective of thermal safety at the SOFC system level, the operating temperature environment of the SOFC stack and the combustion chamber, the temperature difference of the gas at the stack inlet, the temperature gradient within the stack, etc. play a key role in the safety and life of the SOFC system. To this end, we have given the calculation formulas for each temperature and the corresponding temperature constraints for the established mechanism model.

[0098] The following formula is used to express the constraint condition of the maximum temperature of the stack:

[0099] Max.T PEN (K) = max{T stack (j)},j={1,2,…,J}

[0100] 873K≤Max.T PEN ≤1173K

[0101] The following formula is used to express the constraint condition of the maximum temperature gradient of the stack:

[0102] Max.|ΔT PEN |(K)=max|T stack (j+1)-T stack (j)|,

[0103] j={1,2,…,J-1}

[0104] Max.|ΔT PEN |≤8K / cm

[0105] The following formula is used to express the constraint of the gas temperature difference at the stack inlet:

[0106]

[0107] ΔT inlet ≤200K

[0108] The following formula is used to express the constraints of the combustion chamber temperature:

[0109] 873K≤T B ≤1273K

[0110] In the formula, K represents the unit of temperature, T stack(j) represents the temperature of the jth node of the single-chip battery, J represents the total number of nodes divided during the single-chip battery modeling process, T inlet,air Indicates the stack inlet air temperature, Indicates the hydrogen temperature at the stack inlet.

[0111] When SOFC standalone power generation systems perform external load tracking, temperature safety is a key factor in ensuring safe operation. However, during load switching, the temperature may exceed the limit, leading to system failure. Therefore, a reasonable control strategy must be designed to effectively control the operating temperature.

[0112] After the SOFC mechanism model is built, in order to simulate the transient temperature fault during dynamic load switching, it is assumed that the load is controlled to step down at the 50,000th second of the system model operation. Since transient temperature faults generally occur in the load step-down stage rather than the load step-up stage, this embodiment gives priority to the load step-down situation. Specifically: the stack current I s The operating parameters are calculated according to the linear equation I s Switching between different loads is performed in the form of (t)=at+b, where t is the time interval for current switching (unit: s), a and b are unknown parameters determined by the current switching time and the initial and target current values; the remaining operating parameters are switched between the optimal operating points in a step-by-step manner. The optimal operating point refers to the operating parameter that maximizes the system's electrical efficiency within the temperature safety constraints and can be obtained by looking up the table.

[0113] There are two main causes of temperature overshoot during dynamic load switching: one is too rapid current switching when the load power decreases, and the other is too large a current switching amplitude when the load power decreases. To avoid temperature overshoot while enabling the system to switch between optimal operating points as quickly as possible, embodiments of the present invention propose an optimal switching time optimization strategy and a two-step current switching strategy.

[0114] See also Figure 3 The schematic diagram of the optimal switching time optimization process is shown. Since the current switching time affects the SOFC stack temperature gradient and the combustion chamber temperature, the shorter the current switching time, the smaller the maximum positive overshoot of the SOFC stack temperature gradient and the larger the positive overshoot of the combustion chamber temperature. Therefore, to keep the SOFC system temperature within the safety constraint range, the current switching time value must be appropriate, neither too large nor too small. To this end, the embodiment of the present invention adopts an optimal switching time optimization strategy to keep the system temperature within the safety range while achieving fast power tracking without affecting system performance.

[0115] Step S20 , performing dynamic load switching in the mechanism model, and optimizing the optimal switching time to obtain the optimal current switching time corresponding to the dynamic load switching.

[0116] First, according to the initial power and target power of dynamic load switching, the current switching time t is set. c And the switching time interval dt, and initialize it to a specific value (unit is s). In fact, t c The initial value of and dt can take any value greater than 0, but taking into account the efficiency of finding the optimal switching time of the SOFC system, at the same time, in order to avoid the optimal switching time of the SOFC system found to be too different from the actual value, or to avoid the optimal switching time of the SOFC system not being found, t c The initial value of and the value of dt should not be too large or too small. According to the actual switching experience, the present invention sets the SOFC system current switching time t c The initial value of and the time interval dt are both set to 5s. It should be noted that the specific values ​​in this embodiment are only preferred and not limiting. Other values ​​can also be set according to actual conditions, and will not be described in detail here or subsequently.

[0117] Step S201 : setting a current switching time, a switching time interval, and a maximum switching time according to the initial power and the target power of the dynamic load switching and inputting them into the mechanism model.

[0118] Step S202: Dynamic load switching is performed at the optimal operating point of the mechanism model according to the current switching time. If the current switching time meets the switching time condition, the current switching time is used as the optimal current switching time. The switching time condition includes that the corresponding system temperature does not exceed the temperature constraint condition when the dynamic load switching is performed.

[0119] At the initial current switching time, the system load is switched according to the optimal working point, and the system load is recorded at the current switching time t c The SOFC system temperature at that time is measured. The system temperature here refers to the temperature parameters that have a greater impact on system safety when the mechanism model is established. The collected system temperature is compared with the temperature constraint conditions of the mechanism model to determine whether the system temperature exceeds the temperature constraint conditions. If the temperature constraint conditions are met, the current switching time is output as the optimal current switching time, and the corresponding power following time is output at the same time. The power following time refers to the time when the actual output power of the SOFC system reaches the target power from the initial power when the output power is switched.

[0120] Step S203: If the current switching time does not meet the switching time condition, the current switching time is added to the switching time interval to obtain a first current switching time. If the first current switching time is not greater than the maximum switching time, the switching time condition is used as an iteration condition, and the first current switching time is iteratively calculated to obtain a second current switching time, and the second current switching time is used as the optimal current switching time.

[0121] If the corresponding system temperature does not meet the temperature constraint, it means that the current switching time is not optimal. Therefore, it is necessary to adjust the current switching time interval dt and the maximum switching time t according to the previously set switching time interval dt and the maximum switching time t d Current switching time t c Perform iterative calculation, that is, t c =t c +dt, and t c <t d , the maximum switching time t in this embodiment d It is set based on working experience. In a 5kW SOFC system, t d Set to 25s.

[0122] The first current switching time t after iteration c The above-mentioned steps of searching for the optimal switching time are performed again until a second current switching time that satisfies the temperature constraint is found. The iteration is then terminated and the second current switching time is output as the optimal current switching time.

[0123] The above-mentioned optimal switching current optimization strategy can make the system temperature within a safe range and achieve fast power following without affecting the system performance. However, in actual situations, under the same current switching time, the larger the power switching range, the greater the positive overshoot of the maximum temperature gradient of the SOFC stack, the combustion chamber temperature and the SOFC stack inlet gas temperature difference. When the switching range is too large, it may not be possible to directly switch from the initial power to the target power with optimal performance within the temperature constraint no matter how the current switching time is adjusted. In order to solve this problem, the present invention also proposes a two-step current switching strategy, that is, to find the optimal intermediate power through the two-step current switching strategy, and to control the power switching process in stages, so that the output power of the SOFC system switches from the initial power to the target power as smoothly and quickly as possible. For the specific steps, please refer to Figure 4 The flow chart of the two-step current switching strategy is shown in Figure 1:

[0124] Step S30: If the first current switching time is greater than the maximum switching time, an optimal intermediate power corresponding to the dynamic load switching is obtained through double-step current switching.

[0125] The core idea of ​​the two-step current switching strategy is to find an intermediate power. Since this embodiment considers the situation of load step decrease, the power switching process between the initial power, intermediate power and target power can be divided into a high-power stage and a low-power stage. When the high-power stage of the SOFC system ends, the control of the low-power stage of the SOFC system can be started immediately. The operations of the two stages are both carried out between the optimal operating points.

[0126] In other words, the two-step current switching strategy is essentially an optimization strategy for intermediate powers. The difference from the optimal switching time optimization strategy is that, since this strategy targets situations with a large power switching range, there may be multiple intermediate powers that meet system safety requirements. However, in order to find the optimal intermediate power, we no longer follow the optimal switching time optimization strategy, which stops iteration when the time meeting the conditions is found. Instead, we iterate all intermediate powers and make judgments on each intermediate power. Specifically,

[0127] Step S301: According to the initial power and the target power, an initial intermediate power and a power switching interval are set and then input into the mechanism model.

[0128] In step S302, the optimal switching time is optimized for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power, respectively, to obtain the system temperature and power following time corresponding to the initial intermediate power.

[0129] First, the intermediate power P imd Initialize with the power switching interval dP, assuming the initial power is P0 and the target power P des , then P imd Initialized to (P0+1), dP is set to 1kW, and then the optimal switching time is optimized for the high power stage and the low power stage respectively, and the current switching time in the high power stage and the current switching time in the low power stage are obtained. Since the output power of the SOFC system is near the intermediate power at the end of the high power stage, but the SOFC system temperature has not reached the steady-state temperature corresponding to the intermediate power at this time, the optimal switching time of the SOFC system in the low power stage still needs to be re-searched according to the optimal switching time optimization strategy.

[0130] According to the obtained optimal current switching time in the high power stage and the optimal current switching time in the low power stage, dynamic load switching is performed at the optimal working point, and the intermediate power of the system is recorded as P imd The SOFC system temperature at Figure 4 The output temperature shown in , the specific steps are:

[0131] In step S3021, the switching stage from the initial power to the initial intermediate power is taken as the high power stage, and the switching stage from the initial intermediate power to the target power is taken as the low power stage. The optimal switching time is optimized for the high power stage and the low power stage respectively to obtain the optimal current switching time for the high power stage and the optimal current switching time for the low power stage.

[0132] Step S3022, performing dynamic load switching at the optimal operating point of the mechanism model at the optimal current switching time in the high power stage and the optimal current switching time in the low power stage, respectively, to obtain the system temperature corresponding to the initial intermediate power and the power following time.

[0133] Step S303: Add the initial intermediate power to the power switching interval to obtain a first intermediate power; perform iterative calculation on the first intermediate power according to an iteration condition to obtain a second intermediate power and the corresponding system temperature and the power following time; the iteration condition is that the first intermediate power is less than the target power.

[0134] Step S304 : Select an optimal intermediate power from the initial intermediate power and the second intermediate power according to the system temperature and the power following time.

[0135] Secondly, for the intermediate power P imd Perform iterative calculation, that is, judge P imd Is it less than P des If so, let P imd =P imd +dP, and then continue to search for the optimal switching time according to the above steps until P imd Not less than P des , that is, find all P imd .

[0136] Finally, from all P imd In order to achieve faster power following, the optimal intermediate power is selected. Therefore, in this embodiment, the optimal value is selected with priority to the P with shorter power following time. imd As the optimal intermediate power, if the power follows the same time, then the P with better thermal safety is selected next. imd , better thermal safety refers to the temperature value that is farther away from the temperature constraint conditions set by the mechanism model. The optimal intermediate power P imd , and the corresponding high-power stage current switching time, low-power stage current switching time and power following time are output, thereby completing the entire process of the two-step current optimization strategy, where the steps for determining the optimal intermediate power are:

[0137] Step S3041: The initial intermediate power and the second intermediate power are used as the third intermediate power, and the power following times corresponding to the third intermediate powers are compared, and the third intermediate power with the shortest power following time is used as the optimal intermediate power.

[0138] Step S3042: If there are multiple power follow-up times with the same shortest time, the corresponding system temperature is compared with the temperature constraint condition, and the third intermediate power corresponding to the system temperature farthest from the temperature constraint condition is used as the optimal intermediate power.

[0139] This embodiment provides a method for instantaneous temperature control of a solid oxide fuel cell. Compared with traditional methods, which have incomplete thermal characteristic constraints and lack research on instantaneous thermal safety under dynamic load switching, the present invention establishes a mechanism model for the SOFC system, simulates instantaneous temperature faults through the model, and designs a controller for temperature faults to ensure safe and efficient operation of the system.

[0140] See also Figure 5 Based on the same inventive concept, a second embodiment of the present invention provides an instantaneous temperature control system for a fuel cell, comprising:

[0141] A mechanism model building module 10 is used to build a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell, wherein the mechanism model includes a fuel cell stack, an exhaust gas combustion chamber, a heat exchanger, and temperature constraints corresponding to the model;

[0142] An optimal switching time optimization module 20 is used to perform dynamic load switching in the mechanism model and obtain an optimal current switching time corresponding to the dynamic load switching by optimizing the optimal switching time;

[0143] The optimal switching time optimization module 20 includes a time parameter initialization module 201 and a switching time optimization module 202;

[0144] The time parameter initialization module 201 is used to set the current switching time, the switching time interval and the maximum switching time according to the initial power and the target power of the dynamic load switching and input them into the mechanism model;

[0145] The switching time optimization module 202 is used to perform dynamic load switching at the optimal operating point of the mechanism model according to the current switching time. If the current switching time meets the switching time condition, the current switching time is used as the optimal current switching time. The switching time condition includes that the corresponding system temperature does not exceed the temperature constraint condition when the dynamic load switching is performed; if the current switching time does not meet the switching time condition, the current switching time is added to the switching time interval to obtain a first current switching time. If the first current switching time is not greater than the maximum switching time, the switching time condition is used as an iteration condition, and the first current switching time is iteratively calculated to obtain a second current switching time, and the second current switching time is used as the optimal current switching time.

[0146] Furthermore, the system further comprises:

[0147] a two-step current switching module 30 for obtaining an optimal intermediate power corresponding to the dynamic load switching by two-step current switching if the first current switching time is greater than the maximum switching time;

[0148] The two-step current switching module 30 further includes a power parameter initialization module 301 and an intermediate power optimization module 302;

[0149] The power parameter initialization module 302 is used to set the initial intermediate power and the power switching interval according to the initial power and the target power and input them into the mechanism model;

[0150] The intermediate power optimization module 302 is used to optimize the optimal switching time for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power, respectively, to obtain the system temperature and the power following time corresponding to the initial intermediate power; add the initial intermediate power to the power switching interval to obtain a first intermediate power, iteratively calculate the first intermediate power according to an iteration condition, to obtain a second intermediate power and the corresponding system temperature and power following time, wherein the iteration condition is that the first intermediate power is less than the target power; and select the optimal intermediate power from the initial intermediate power and the second intermediate power according to the system temperature and the power following time.

[0151] The technical features and technical effects of the instantaneous temperature control system for a fuel cell proposed in an embodiment of the present invention are the same as those of the method proposed in an embodiment of the present invention and are not described in detail here. Each module in the instantaneous temperature control system for a solid oxide fuel cell can be implemented in whole or in part by software, hardware, or a combination thereof. Each of the above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in the form of software in a computer device so that the processor can call and execute the operations corresponding to each of the above modules.

[0152] See also Figure 6 , an internal structure diagram of a computer device in one embodiment, the computer device can specifically be a terminal or a server. The computer device includes a processor, a memory, a network interface, a display and an input device connected via a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a method for instantaneous temperature control of a fuel cell is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0153] It can be understood by those skilled in the art that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computing device may include more or fewer components than those shown in the figure, or combine certain components, or have the same component arrangement.

[0154] In addition, an embodiment of the present invention further provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0155] In addition, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, and the computer program implements the steps of the above method when executed by a processor.

[0156] In summary, the instantaneous temperature control method, system, device, and storage medium for a fuel cell proposed in an embodiment of the present invention establishes a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell. The mechanism model includes the fuel cell stack, the exhaust combustion chamber, the heat exchanger, and the temperature constraints corresponding to the model. Dynamic load switching is performed in the mechanism model, and the optimal current switching time corresponding to the dynamic load switching is obtained by optimizing the optimal switching time. This method establishes a mechanism model for the SOFC system, simulates the instantaneous temperature of the system under load switching through the model, and then proposes an optimal switching time optimization strategy and a two-step current switching strategy for system temperature failures under different switching conditions, so that the system can maintain safe and efficient operation even in a dynamic switching state.

[0157] Each embodiment in this specification is described in a progressive manner, and the same or similar parts of each embodiment can be directly referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. It should be noted that the various technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0158] The above-described embodiments merely represent several preferred implementations of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be based on the scope of protection of the claims.

Claims

1. A method for controlling the instantaneous temperature of a fuel cell, characterized in that: include: Establishing a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell, wherein the mechanism model includes a fuel cell stack, an exhaust gas combustion chamber, a heat exchanger, and temperature constraints corresponding to the model; Dynamic load switching is performed in the mechanism model, and an optimal current switching time corresponding to the dynamic load switching is obtained by optimizing the optimal switching time, wherein the step of optimizing the optimal switching time includes: According to the initial power and target power of the dynamic load switching, the current switching time, the switching time interval and the maximum switching time are set and input into the mechanism model; performing dynamic load switching at the optimal operating point of the mechanism model according to the current switching time, and using the current switching time as the optimal current switching time if the current switching time meets a switching time condition, wherein the switching time condition includes that a corresponding system temperature during the dynamic load switching does not exceed the temperature constraint condition; If the current switching time does not meet the switching time condition, the current switching time is added to the switching time interval to obtain a first current switching time; if the first current switching time is not greater than the maximum switching time, the switching time condition is used as an iteration condition, the first current switching time is iteratively calculated to obtain a second current switching time, and the second current switching time is used as the optimal current switching time; The step of establishing the mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell comprises: Based on the mechanism formulas of electrical characteristics, energy conservation and mass conservation, a mechanism model of solid oxide fuel cells is established; The following formula is used to express the electrical characteristics of the stack in the mechanism model: The following formula is used to express the energy conservation of the battery stack: The energy conservation of the exhaust combustion chamber in the mechanism model is expressed by the following formula: The following formula is used to express the mass conservation of the tail gas combustion chamber: The following formula is used to express the energy conservation of the heat exchanger in the mechanism model: The following formula is used to express the mass conservation of the heat exchanger: In the formula, the subscript stack represents the battery stack, the subscript afterburner represents the exhaust combustion chamber, the subscripts in and out represent input and output respectively, the superscripts hot and cold represent heat energy and cold energy respectively, the subscript cell represents the battery cell, n represents the number of battery cells, U represents voltage, P represents pressure, F represents Faraday's constant, K represents universal gas constant, T represents temperature, V represents volume, C represents specific heat capacity, ρ represents density, represents flow rate, h represents thermal enthalpy, R represents molar reaction rate, A represents area, △T represents the change in temperature, Indicates energy value, E 0 represents Nernst voltage, D represents current density, H2O represents water, H2 represents hydrogen, and i = [H20, H2, CH4, CO2, CO, N2, O2]; The temperature constraints of the mechanism model include the constraints corresponding to the maximum temperature of the stack, the maximum temperature gradient of the stack, the temperature difference of the gas at the stack inlet, and the combustion chamber temperature respectively; The following formula is used to express the constraint condition of the maximum temperature of the stack: Max.T PEN (K)=max{T stack (j)},j={1,2,…,J} 873K≤Max.T PEN ≤1173K The following formula is used to express the constraint condition of the maximum temperature gradient of the stack: Max.|ΔT PEN |(K)=max|T stack (j+1)-T stack (j)|, j={1,2,…,J-1} Max.|ΔT PEN |≤8K / cm The following formula is used to express the constraint condition of the gas temperature difference at the fuel cell inlet: ΔT inlet ≤200K The following formula is used to express the constraints of the combustion chamber temperature: 873K≤T B ≤1273K In the formula, K represents the unit of temperature, T stack (j) represents the temperature of the jth node of the single-chip battery, J represents the total number of nodes divided during the single-chip battery modeling process, T inlet,air Indicates the stack inlet air temperature, Indicates the hydrogen temperature at the stack inlet.

2. The instantaneous temperature control method of a fuel cell according to claim 1, characterized in that: If the first current switching time is greater than the maximum switching time, the optimal intermediate power corresponding to the dynamic load switching is obtained by performing two-step current switching, wherein the two-step current switching step includes: According to the initial power and the target power, an initial intermediate power and a power switching interval are set and then input into the mechanism model; performing the optimal switching time optimization for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power, respectively, to obtain the system temperature and power following time corresponding to the initial intermediate power; adding the initial intermediate power to the power switching interval to obtain a first intermediate power, and iteratively calculating the first intermediate power according to an iteration condition to obtain a second intermediate power and the corresponding system temperature and the power following time, wherein the iteration condition is that the first intermediate power is less than the target power; An optimal intermediate power is selected from the initial intermediate power and the second intermediate power according to the system temperature and the power following time.

3. The instantaneous temperature control method of a fuel cell according to claim 2, characterized in that: The step of respectively optimizing the optimal switching time for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power to obtain the system temperature and power following time corresponding to the initial intermediate power includes: The switching stage from the initial power to the initial intermediate power is regarded as a high-power stage, and the switching stage from the initial intermediate power to the target power is regarded as a low-power stage. The optimal switching time is optimized for the high-power stage and the low-power stage respectively, to obtain the optimal current switching time for the high-power stage and the optimal current switching time for the low-power stage; During the optimal current switching time in the high power stage and the optimal current switching time in the low power stage, dynamic load switching is performed at the optimal working point of the mechanism model to obtain the system temperature corresponding to the initial intermediate power and the power following time.

4. The instantaneous temperature control method of a fuel cell according to claim 2, characterized in that: The step of selecting the optimal intermediate power from the initial intermediate power and the second intermediate power according to the system temperature and the power following time comprises: taking the initial intermediate power and the second intermediate power as third intermediate powers, comparing power following times corresponding to the third intermediate powers, and taking the third intermediate power with the shortest power following time as the optimal intermediate power; If there are multiple power follow-up times with the same shortest time, the corresponding system temperatures are compared with the temperature constraint condition, and the third intermediate power corresponding to the system temperature farthest from the temperature constraint condition is used as the optimal intermediate power.

5. A fuel cell instantaneous temperature control system, characterized in that: include: A mechanism model building module is used to establish a mechanism model of the solid oxide fuel cell based on the transfer mechanism of the solid oxide fuel cell. The mechanism model includes the fuel cell stack, the exhaust gas combustion chamber, the heat exchanger, and the temperature constraints corresponding to the model, including: Based on the mechanism formulas of electrical characteristics, energy conservation and mass conservation, a mechanism model of solid oxide fuel cells is established; The following formula is used to express the electrical characteristics of the stack in the mechanism model: The following formula is used to express the energy conservation of the battery stack: The energy conservation of the exhaust combustion chamber in the mechanism model is expressed by the following formula: The following formula is used to express the mass conservation of the tail gas combustion chamber: The following formula is used to express the energy conservation of the heat exchanger in the mechanism model: The following formula is used to express the mass conservation of the heat exchanger: In the formula, the subscript stack represents the battery stack, the subscript afterburner represents the exhaust combustion chamber, the subscripts in and out represent input and output respectively, the superscripts hot and cold represent heat energy and cold energy respectively, the subscript cell represents the battery cell, n represents the number of battery cells, U represents voltage, P represents pressure, F represents Faraday's constant, K represents universal gas constant, T represents temperature, V represents volume, C represents specific heat capacity, ρ represents density, represents flow rate, h represents thermal enthalpy, R represents molar reaction rate, A represents area, △T represents the change in temperature, Indicates energy value, E 0 represents Nernst voltage, D represents current density, H2O represents water, H2 represents hydrogen, and i = [H20, H2, CH4, CO2, CO, N2, O2]; The temperature constraints of the mechanism model include the constraints corresponding to the maximum temperature of the stack, the maximum temperature gradient of the stack, the temperature difference of the gas at the stack inlet, and the combustion chamber temperature respectively; The following formula is used to express the constraint condition of the maximum temperature of the stack: Max.T PEN (K)=max{T stack (j)},j={1,2,…,J} 873K≤Max.T PEN ≤1173K The following formula is used to express the constraint condition of the maximum temperature gradient of the stack: Max.|ΔT PEN |(K)=max|T stack (j+1)-T stack (j)|, j={1,2,…,J-1} Max.|ΔT PEN |≤8K / cm The following formula is used to express the constraint condition of the gas temperature difference at the fuel cell inlet: ΔT inlet ≤200K The following formula is used to express the constraints of the combustion chamber temperature: 873K≤T B ≤1273K In the formula, K represents the unit of temperature, T stack (j) represents the temperature of the jth node of the single-chip battery, J represents the total number of nodes divided during the single-chip battery modeling process, T inlet,air Indicates the stack inlet air temperature, Indicates the hydrogen temperature at the stack inlet; An optimal switching time optimization module is used to perform dynamic load switching in the mechanism model and obtain an optimal current switching time corresponding to the dynamic load switching by optimizing the optimal switching time; The optimal switching time optimization module includes a time parameter initialization module and a switching time optimization module; The time parameter initialization module is used to set the current switching time, the switching time interval and the maximum switching time according to the initial power and the target power of the dynamic load switching and input them into the mechanism model; The switching time optimization module is configured to perform dynamic load switching at the optimal operating point of the mechanism model according to the current switching time, and use the current switching time as the optimal current switching time if the current switching time meets a switching time condition, wherein the switching time condition includes that the corresponding system temperature during the dynamic load switching does not exceed the temperature constraint condition; If the current switching time does not meet the switching time condition, the current switching time is added to the switching time interval to obtain a first current switching time. If the first current switching time is not greater than the maximum switching time, the switching time condition is used as an iteration condition, and the first current switching time is iteratively calculated to obtain a second current switching time, and the second current switching time is used as the optimal current switching time.

6. The instantaneous temperature control system of a fuel cell according to claim 5, characterized in that: The system further comprises: a two-step current switching module, configured to obtain an optimal intermediate power corresponding to the dynamic load switching by two-step current switching if the first current switching time is greater than the maximum switching time; The two-step current switching module also includes a power parameter initialization module and an intermediate power optimization module; The power parameter initialization module is used to set the initial intermediate power and the power switching interval according to the initial power and the target power and input them into the mechanism model; The intermediate power optimization module is used to optimize the optimal switching time for the switching stage from the initial power to the initial intermediate power and the switching stage from the initial intermediate power to the target power, respectively, to obtain the system temperature and the power following time corresponding to the initial intermediate power; add the initial intermediate power to the power switching interval to obtain a first intermediate power, iteratively calculate the first intermediate power according to an iteration condition, to obtain a second intermediate power and the corresponding system temperature and power following time, wherein the iteration condition is that the first intermediate power is less than the target power; and select the optimal intermediate power from the initial intermediate power and the second intermediate power according to the system temperature and the power following time.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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