Marine fuel cell system attenuation model considering influence of salt spray environment, and power control method and service life prediction method of marine fuel cell system attenuation model

Abstract

The invention discloses a marine fuel cell system attenuation model considering the influence of a salt mist environment, and a power control method and a service life prediction method thereof, and the model comprises the following three parts: a first part, an attenuation model considering the influence of the salt mist environment on the performance of a marine hydrogen fuel cell during use; the second part is a power control method based on the attenuation model; and the third part is a marine fuel cell system life prediction method based on historical operation data and the attenuation model. According to the invention, the attenuation model of the marine fuel cell system including the influence of the salt mist environment is established for the first time, and the power control method of the marine fuel cell system is provided based on the attenuation model, so that the power of the fuel cell system is accurately controlled; in addition, a life prediction method of the marine fuel cell system is provided based on the attenuation model and historical operation data, so that the life and residual life prediction of the fuel cell system becomes simple, convenient and effective.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen fuel cells, and in particular to an attenuation model that takes into account the influence of a salt spray environment on the performance of a marine hydrogen fuel cell during use, and a power control method based on the attenuation model, and also to a method for predicting the life of a marine fuel cell system based on historical operating data and the attenuation model. Background Art

[0002] Under the pressure of environmental protection and energy crisis, clean and green energy technologies are gaining more and more attention in the shipping industry. In 2023, the 80th session of the International Maritime Organization (IMO) Marine Environment Protection Committee (MEPC 80) further strengthened the requirements for ship carbon emissions, and the net zero emission target was brought forward by 50 years (from 2100 to 2050). Hydrogen fuel cell system is a very promising clean and green energy technology in the shipping industry, which helps the shipping industry to break away from the demand for traditional fossil energy and achieve the net zero emission target. At present, the research on marine fuel cell systems is on the rise, but there is a lack of research on the impact of marine fuel cell system attenuation or the lack of relevant effective control methods. Some existing attenuation models are mostly for vehicle conditions or working conditions, most of which only consider one or several of the working conditions such as low power, high power, variable load and start-stop as factors affecting the attenuation of the fuel cell system. Although these factors will affect the attenuation of the marine fuel cell system, an important feature of the marine conditions of the fuel cell system is the salt spray environment, and the salt spray environment has a significant impact on the attenuation of the marine fuel cell system, and is also a key factor in the attenuation of the marine fuel cell system. In addition, due to the long-term use of the marine fuel cell system, its attenuation will cause the performance to decline and the single-chip voltage to be lower than the initial state. If the target power is still adjusted or controlled according to the pre-set power control method, the actual output target power will inevitably be smaller, and it will not be able to effectively meet the power requirements of the actual navigation process of the ship. In response to the above problems, the patent of the present invention constructs an attenuation model of the marine fuel cell system considering the influence of the salt spray environment, and establishes a power control method and control system for the marine fuel cell system that meets the actual power requirements based on the attenuation model. In addition, a life prediction model and method for the marine fuel cell system are proposed in combination with the historical data of the operation of the marine fuel cell system. Based on the constructed attenuation model, the attenuation characteristics of the marine fuel cell system can be evaluated more reasonably and accurately, so that the power output of the marine fuel cell system can be accurately and reliably controlled, and the life of the marine fuel cell system can be effectively predicted. Summary of the invention

[0003] The present invention aims to overcome at least one defect of the above-mentioned prior art, and its main purpose is: (1) to establish a marine fuel cell system attenuation model considering the influence of salt spray environment, the attenuation model is composed of 5 key factors, and the single cell attenuation rate of each factor can be determined by experiment. Based on the characteristic information statistics of the operating conditions, the attenuation voltage of the single cell at the rated power point can be determined by the attenuation model. (2) A marine fuel cell system power control method based on the attenuation model is proposed. By calculating the attenuation voltage, the polarization curve and power density curve after attenuation can be inferred, or the table data of power density corresponding to current density; and then the current density or current that the attenuated fuel cell system should output under the target power demand can be determined, so that the air compressor speed and hydrogen supply can be adjusted to achieve accurate output of the marine fuel cell system. (3) Combine the historical operation data with the constructed attenuation model, fit it into a linear function related to the operation time and the attenuation degree of the single-chip voltage of the fuel cell system, and then take the rated power attenuation of 10% as the threshold, and then establish a prediction model for the life of the marine fuel cell system.

[0004] The present invention provides a marine fuel cell system attenuation model considering the influence of salt spray environment, comprising the following parts: Part 1: Traditional attenuation model, which considers the impact of four operating conditions, including low power, high power, variable load and start-stop, on the performance attenuation of the fuel cell, as expressed in Formula 1.

[0005] Part 2: The impact of salt spray environment on fuel cell attenuation, as expressed in Formula 2; Salt spray environment is a realistic condition faced by marine fuel cell systems. After the marine fuel cell system has been running in a salt spray environment for a long time, some salt substances containing Na will be deposited on the electrodes, causing the proton conductivity of the membrane electrode to decrease, and then causing the single-chip voltage of the stack to decrease, resulting in the attenuation of the marine fuel cell system.

[0006] Formula 1 is a traditional attenuation model. Most traditional attenuation models only consider one or several of the operating conditions such as low power, high power, variable load and start-stop. The attenuation model proposed in the present invention includes almost all the main influencing factors in the traditional model, and additionally considers the salt spray environment encountered in the actual operating conditions of the ship, and constructs a model for the degree to which the salt spray environment affects the attenuation of the fuel cell (as shown in Formula 2).

[0007] The sum of the first part (Formula 1) and the second part (Formula 2) is the attenuation model of the marine fuel cell system considering the influence of the salt spray environment proposed by the present invention, as described in Formula 3.

[0008] The models described in the first and second parts and the attenuation model of the marine fuel cell system considering the influence of the salt spray environment proposed in the present invention are as follows: Formula 1: ; Formula 2: ; Formula 3: .

[0009] Since the influence of various attenuation factors, especially the influence of salt spray on attenuation, can be fully considered, the attenuation model shown in Formula 3 can better predict the single-chip voltage attenuation value of the marine fuel cell system.

[0010] The models for the influence of low power, high power, variable load and start-stop conditions mentioned in Formula 1 on the attenuation degree of the fuel cell are shown in Formulas 4, 5, 6 and 7, as follows: Formula 4: ; Formula 5: ; Formula 6: ; Formula 7: .

[0011] The meanings of Formula 1, Formula 2, Formula 3, Formula 4, Formula 5, Formula 6 and Formula 7 are as follows: U in Formula 1 Tradition-degradation It represents the single-chip voltage attenuation value caused by the traditional attenuation model. Formula 2 is the effect of salt spray environment on attenuation, U Salt-mist Indicates the voltage attenuation value of a single chip caused by a salt spray environment, u Salt-mist Represents the single cell attenuation rate in salt spray environment, t Salt-mist Indicates the operating time in the salt spray environment. U in Formula 3 Degradation = represents the single-chip voltage attenuation value calculated by the attenuation model proposed in the present invention. Formula 4 is the effect of the start-stop condition on attenuation, U Start-stop Indicates the single chip voltage attenuation value caused by start-stop conditions, u Start-stop Indicates the single battery attenuation rate under start-stop conditions, n Start-stop Indicates the number of start-stop conditions. Formula 5 is the effect of low-power conditions on attenuation, U Low-power Indicates the single chip voltage attenuation value caused by low power conditions, u Low-power Indicates the decay rate of a single battery under low power conditions, t Low-power Indicates the running time of low power condition. Formula 6 is the influence of high power condition on attenuation, U High-power Indicates the single chip voltage attenuation value caused by high power conditions, u High-power Indicates the single battery attenuation rate under high power conditions, t High-power Indicates the running time of high power condition. Formula 7 is the influence of variable load condition on attenuation, U Transient-loading Indicates the single chip voltage attenuation value caused by variable load conditions, u Transient-loadingIndicates the decay rate of a single battery under variable load conditions, n Transient-loading Indicates the power change value under variable load conditions.

[0012] Furthermore, the present invention provides a method for controlling power of a marine fuel cell system based on an attenuation model, comprising the following steps: S1: Determine the corresponding relationship between the current density and power of the marine fuel cell after attenuation; S2: determining a corrected current density based on the target power demand; S3: Determine the parameters of the air compressor and the hydrogen supply device based on the corrected current density; S4: Determine whether the output power of the marine fuel cell system meets the demand and decide whether to take further action.

[0013] like Figure 1 The figure shows the polarization curve, power density curve, attenuated polarization curve and attenuated power density curve of a fuel cell system. The power density curve is calculated by formula 8 based on the polarization curve. Formula 9 adds the effective unit area A of the membrane electrode to formula 8. Area , the number of membrane electrodes n Cell (the number of single cells), the output power of the fuel cell system corresponding to the current density can be calculated according to Formula 9.

[0014] Note: Since the effective unit area of ​​the membrane electrode A Area It is generally an inherent property of the membrane electrode and is a fixed value. The number of membrane electrodes n Cell It is also a constant for fuel cell systems, and the current density multiplied by the effective unit area of ​​the membrane electrode is the current. Therefore, when current density is introduced later, its meaning is equivalent to current, that is, current density is equivalent to current. Similarly, when power density is introduced, its meaning is equivalent to power. As shown in Formula 8 and Formula 9, power and power density obey a fixed mathematical relationship.

[0015] The formula eight and formula nine described in step S1 are as follows: Formula 8: ; Formula 9: .

[0016] In the above formula 8, p Power-density is the power density, U is the single-chip voltage of the fuel cell, i Electriciy-density is the current density, and P in Formula 9 is the power.

[0017] Furthermore, in step S1, Figure 1 As shown, when the fuel cell system has no attenuation, it corresponds to 0.5A / cm 2The current density (i.e., point A in the figure), and its output power is P1; when the fuel cell continues to be used in practice, its performance degrades, corresponding to 0.5 A / cm 2 The output power at the current density becomes P2 (the intersection point of the auxiliary line and the power density curve after degradation). Obviously, P2 < P1, and the output power does not match the target required power. The traditional power control method is to continuously try to increase the current density. Such attempts are often uncertain and require multiple attempts to achieve a satisfactory result, often causing control hysteresis or delay, affecting the accuracy, stability, and reliability of the control system; at the same time, such attempts require frequent changes in the working state of the fuel cell system, further having an adverse impact on the life of the fuel cell system.

[0018] Furthermore, in the step S1, most of the existing marine fuel cell systems control the target power in the above manner, such as Figure 2 shown. The present invention fully considers the influence of the salt spray environment during the use of the ship. Based on the constructed attenuation model considering the salt spray influence (as shown in Formula III), the true power density curve or power output characteristics after attenuation of the marine fuel cell system can be fully considered. By calculating the attenuation voltage based on the attenuation model considering the influence of the salt spray environment, and then calculating the attenuation change rate based on the attenuation voltage at the rated power, specifically as shown in Formula X, where η is the attenuation change rate, U Degradation represents the single-cell voltage attenuation value of the attenuation model proposed by the present invention, and U Initial is the initial single-cell voltage under the rated power condition.

[0019] The Formula X in the step S1 is as follows: Formula X: .

[0020] From Formula VIII and Formula IX, the power after attenuation can be calculated based on the attenuation change rate, and further curve fitting or constructing new power table data (i.e., power table data corresponding to different current densities) for the power after attenuation; for the control strategy of the fuel cell system, usually the above corresponding relationship is expressed in the form of table data, which is convenient for the control process to search or interpolate based on this table.

[0021] Furthermore, in the step S2, based on the step S1, that is, after establishing the relationship between the power after attenuation and the current density, the corrected target current density can be calculated based on the target power and the curve fitting or table data of the power after attenuation.

[0022] Furthermore, in step S3, the air compressor speed is determined based on the corrected target current density, and the hydrogen supply pressure or hydrogen supply amount is determined based on the air compressor speed. This process completes the control of the hydrogen supply amount and air supply amount of the fuel cell system according to the corrected target current density, thereby achieving accurate output of the target power. Figure 1 As shown, the target current density is corrected from point A to point B (the current density / current is increased), so that the attenuated power point P3 matches the target power P1, that is, P3=P1.

[0023] Furthermore, in step S4, Figure 2 As shown, a conditional judgment is set. Once the power control method meets the power demand, the process ends; once it does not meet the demand, the current density is further adjusted. The corresponding air compressor speed is a function of the current density, and the hydrogen supply or pressure changes with the air compressor speed. In general, the current density and the air compressor speed have calibrated table data, while the air compressor speed and the air compressor outlet pressure are inherent properties of the air compressor, that is, there is a certain MAP (characteristic curve or characteristic relationship). The hydrogen supply pressure or hydrogen supply is output according to a fixed value with the air compressor outlet pressure, that is, the hydrogen supply pressure or hydrogen supply and the air compressor outlet pressure are a fixed mathematical quantity or numerical value.

[0024] Furthermore, the present invention provides a method for predicting the life of a marine fuel cell system based on a decay model and historical operation data, comprising the following steps: T1: Extract historical operation data into two variables: average working time and attenuation voltage; T2: Fit the average working time and attenuation voltage into a linear function and set the life threshold; T3: Calculate the life of the marine fuel cell system based on the fitted linear function and the life threshold.

[0025] Unlike the driving of cars, the navigation routes and operating conditions of ships are relatively stable within a certain period of time. That is, ships basically operate according to fixed routes and inherent operating conditions, and there are rarely major changes, which means that the attenuation of marine fuel cell systems can be fitted based on historical data.

[0026] Furthermore, in step T1, Figure 3 As shown, based on the historical operation data, the six variables in the attenuation model proposed by the present invention (the single battery attenuation rate in the attenuation model is a coefficient, which can be obtained by consulting literature or experiments, so the variable is n Start-stop ,t Low-power ,t High-power 、n Transient-loading ,t Salt-mist , U Degradation 6) are simplified to the average use time t, the single chip voltage attenuation value UDegradation two.

[0027] Furthermore, in step T2, the average usage time t and the single-chip voltage attenuation value U are established. Degradation From the equations 1, 2, 3, 4, 5, 6 and 7 related to the decay model proposed in the present invention, it can be inferred that the average usage time t and U Degradation It roughly obeys a linear function relationship, so the fitting function (linear function) shown in Formula 11 is constructed.

[0028] The formula 11 described in step T2 is as follows: Formula 11: .

[0029] In the above formula 11, a and b are coefficients of the fitting function, which are determined after fitting the historical operation data.

[0030] Furthermore, in step T2, the life of the fuel cell system is generally based on a 10% decay of the rated power, and the life threshold of the marine fuel cell system shown in Formula 12 is a 10% decay of the initial single-chip voltage under rated power conditions.

[0031] The formula twelve described in step T2 is as follows: Formula 12: .

[0032] U in Formula 12 Initial It indicates the initial single-chip voltage under rated power conditions. This value is calibrated at the factory and represents the factory performance of the fuel cell.

[0033] Furthermore, in step T3, formula 11 and formula 12 can be further simplified to formula 13. In formula 13, t max That is, the maximum service life of the marine fuel cell system calculated based on the existing historical data and the attenuation model, and the life of the marine fuel cell system inferred based on the existing historical data. max Subtract the average usage time t to get the remaining life of the marine fuel cell system.

[0034] The formula 13 described in step T3 is as follows: Formula 13: .

[0035] The present invention also protects a marine fuel cell system power control system based on an attenuation model, which can be used to execute a marine fuel cell system power control method based on an attenuation model proposed by the present invention. A marine fuel cell system power control method based on an attenuation model established by the present invention can output power quickly, stably and accurately according to the target power demand.

[0036] The present invention also protects a marine fuel cell system life prediction system based on a decay model and historical operation data, which can be used to execute a marine fuel cell system life prediction method based on a decay model and historical operation data proposed by the present invention. A marine fuel cell system life prediction method based on a decay model and historical operation data established by the present invention can conveniently and reliably evaluate the life and remaining life of a marine fuel cell system.

[0037] The hydrogen fuel cell system mentioned in the present invention may be of various types, including but not limited to proton exchange membrane fuel cells, other phosphoric acid fuel cells, molten carbonate fuel cells and solid oxide fuel cells.

[0038] The marine fuel cell system mentioned in the present invention is not limited to use on ships, but can be applied to any fuel cell system in a salt spray environment, such as a fuel cell system serving land equipment near a dock or coast. Therefore, based on the present invention, non-marine fuel cells, as long as they involve salt spray environment conditions or application scenarios, are within the protection scope of the present invention.

[0039] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention aims at the actual use conditions of the marine fuel cell system and establishes for the first time a mathematical model of the attenuation change of the marine fuel cell system under the salt spray environment, so as to quantitatively evaluate the influence of the salt spray environment on the attenuation characteristics of the fuel cell system.

[0040] (2) The present invention establishes a complete attenuation model for a marine fuel cell system, which includes five influencing factors, namely, salt spray environment, low power, high power, variable load, and start-stop, and can more accurately calculate the single-chip voltage attenuation value of a marine fuel cell system.

[0041] (3) Based on the constructed attenuation model of the marine fuel cell system, the present invention proposes a power control method for the marine fuel cell system, which can achieve fine control of the power of the fuel cell system, is beneficial to the accuracy, stability and reliability of power control, and is beneficial to reducing the adverse damage to the life of the fuel cell system caused by frequent load changes.

[0042] (4) The present invention combines the established marine fuel cell attenuation model with historical operating data to construct a fitting function between the average usage time and the single-chip voltage attenuation value, and then couples it with the life threshold of the marine fuel cell system to derive a marine fuel cell system life prediction model. Based on this model, the life and remaining life of the marine fuel cell system can be simply and reliably evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1Provide additional explanation for the power control principle of marine fuel cell systems.

[0044] Figure 2 This is a schematic diagram of the power control strategy and system principle of the marine fuel cell system.

[0045] Figure 3 This is a schematic diagram of the life prediction method and principle of marine fuel cell system. DETAILED DESCRIPTION

[0046] The drawings in the embodiments provide a more detailed description of the technical solutions in the embodiments of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0047] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), such directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0048] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0049] Example 1

[0050] This embodiment provides an attenuation model for a marine fuel cell system that takes into account the influence of a salt spray environment. The model includes a traditional attenuation model and a mathematical model of the attenuation change of a marine fuel cell system in a salt spray environment. The traditional attenuation model takes into account the influence of four influencing factors or operating conditions, such as low power, high power, variable load, and start-stop, on the attenuation of fuel cell performance. Formula 1 is used to describe the traditional attenuation model, Formula 2 is used to describe the attenuation caused by a salt spray environment, and Formula 3 is the attenuation model for a marine fuel cell system that takes into account the influence of a salt spray environment proposed in the present invention. The models for the influence of low power, high power, variable load, and start-stop conditions on the attenuation degree of the fuel cell are shown in Formulas 4, 5, 6, and 7, respectively.

[0051] Formula 1: .

[0052] Formula 2: .

[0053] Formula 3: .

[0054] Formula 4: .

[0055] Formula 5: .

[0056] Formula 6: .

[0057] Formula 7: .

[0058] U in Formula 1 Tradition-degradation Indicates the single-chip voltage attenuation value caused by the traditional attenuation model. In formula 2, U Salt-mist Indicates the voltage attenuation value of a single chip caused by a salt spray environment, u Salt-mist Represents the single cell attenuation rate in salt spray environment, t Salt-mist Indicates the operating time in the salt spray environment. U in Formula 3 Degradation represents the single-chip voltage attenuation value calculated by the attenuation model proposed in the present invention. In formula 4, U Start-stop Indicates the single chip voltage attenuation value caused by start-stop conditions, u Start-stop Indicates the single battery attenuation rate under start-stop conditions, n Start-stop Indicates the number of start-stop conditions. In Formula 5, U Low-power Indicates the single chip voltage attenuation value caused by low power conditions, u Low-power Indicates the decay rate of a single battery under low power conditions, t Low-power Indicates the running time of low power condition. In formula 6, U High-power Indicates the single chip voltage attenuation value caused by high power conditions, u High-power Indicates the single battery attenuation rate under high power conditions, tHigh-power Indicates the operating time of high power condition. In formula 7, U Transient-loading Indicates the single chip voltage attenuation value caused by variable load conditions, u Transient-loading Indicates the decay rate of a single battery under variable load conditions, n Transient-loading Indicates the power change value under variable load conditions.

[0059] The single cell decay rate (u Salt-mist 、u Start-stop 、u Low-power etc.) are coefficients, which can be obtained by consulting literature or experiments, and the variable is n Start-stop ,t Low-power ,t High-power 、n Transient-loading ,t Salt-mist , U Degradation Once the statistical information of the decay rate and variables of a single cell is obtained, it can be calculated using the above formula.

[0060] The value of the single battery attenuation rate is generally as follows: Salt-mist 10μV / h, u Start-stop 23.91μV / cycle, u Low-power 10.17μV / h, u High-power 11.74μV / h, u Transient-loading It is 0.0441μV / ΔkW.

[0061] The variables corresponding to the above single cell attenuation rate are evaluated under the following usage conditions: the marine fuel cell system works for 4 hours a day, starts and stops once, the load range is 400kW, the low-power operation time is 1.5 hours, the high-power operation time is 2.5 hours, and the operation time in the salt spray environment is 4 hours; the operation time range is 12 months, and there are 20 working days in each month. The statistical information of the relevant variables in the above formula is as follows: n Start-stop is 240cycle, n Transient-loading 48000kW, t Low-power is 360h, t High-power 600h, t Salt-mist It is 960h.

[0062] Substituting the above single cell decay rate and variable statistics into the above formula, U Start-stop 5738.4μV, U Transient-loading 2116.8μV, U Low-power 3661.2, U High-power The table is 7044μV, U Salt-mist is 9600μV. Finally, after summarizing, we can know that U DegradationIt is 28160.4μV, or 0.0281604V.

[0063] Example 2

[0064] This embodiment provides a power control method for a marine fuel cell system based on an attenuation model. The core is to determine the attenuation change rate of the monolithic voltage based on the established attenuation model, and then construct the power density characteristics or power characteristics of the attenuated marine fuel cell system based on the attenuation change rate, that is, the power density or power corresponding to different current densities. Usually in the control system, the power density characteristics or power characteristics are often expressed in the form of tabular data. Of course, curve fitting can also be performed. There is no essential difference between the two, both of which are to express the relationship between current density and power density or power. This embodiment only takes tabular data as an example for illustration. The calculation method of the attenuation change rate is shown in Formula 10. Formulas 8 and 9 are supplementary explanations for explaining the principle of this implementation case, so as to better understand the connection between current density and power density, the relationship between current density and power, etc.

[0065] Formula 8: .

[0066] Formula 9: .

[0067] Formula 10: .

[0068] Formula 8 p Power-density is the power density, U is the single-chip voltage of the fuel cell, i Electriciy-density is the current density. In formula 9, P is the power, A Area is the effective unit area of ​​the membrane electrode, n Cell is the number of membrane electrodes (the number of single cells). In formula 10, η is the attenuation change rate, U Degradation The single-chip voltage attenuation value of the attenuation model proposed by the present invention, U Initial is the initial single chip voltage at rated power condition.

[0069] In this embodiment, U Initial is 0.6V, U Degradation is 0.0281604 V (the result of implementation case 1), and according to formula 10, η is 5%.

[0070] In this embodiment, Figure 1 The solid line shown (no attenuation or factory state, referred to as "before attenuation") shows a current density of 0.343309 A / cm 2 When the single chip voltage is 0.7V, the current density is 0.596247A / cm 2When the single chip voltage is 0.6V, after the operation of the implementation case 1, the marine fuel cell system decays, such as Figure 1 The long dashed line (after decay) shows a current density of 0.343309 A / cm 2 When the single chip voltage becomes 0.665V, the current density is 0.596247A / cm 2 When the single-chip voltage becomes 0.57 V. By analogy, the corresponding table data of each current density and power density when no attenuation occurs can be established (this data generally characterizes the performance of the fuel cell system, represents the initial state of the fuel cell, and is usually called calibration data); the corresponding table data of each current density and power density after attenuation can also be established.

[0071] Further, through interpolation calculation, the current density can be obtained to be 0.5A / cm 2 The single chip voltage value and power density value before and after attenuation. Taking the commonly used linear interpolation method as an example, before attenuation, 0.5A / cm 2 The single chip voltage is 0.64V, and the power density is 0.32W / cm according to formula 8. 2 , and the power can be calculated according to Formula 9 as 64kW (the effective unit area of ​​the membrane electrode of this fuel cell system is 400cm 2 , the number of membrane electrodes n Cell is 500); after attenuation, 0.5A / cm 2 The single chip voltage is 0.61V, and the power density is 0.305W / cm according to formula 8. 2 , and the power can be calculated as 61kW according to Formula 9.

[0072] Obviously, if the current density or current before attenuation is used as the input of power control based on the target power of 64 kW, then after the fuel cell attenuates, its actual output power is only 61 kW, which cannot meet the power demand.

[0073] Furthermore, based on the target power of 64 kW, the corresponding table data of the attenuated fuel cell power characteristics or current density and power density can be interpolated to obtain the corrected current density or current corresponding to the attenuated power of 64 kW.

[0074] Furthermore, taking the above current density and single-chip voltage before and after attenuation as an example, when the power is 64kW, the corresponding power density is 0.32W / cm 2 By linear interpolation, it can be calculated that the corresponding input current of the fuel cell after attenuation should be 0.55A / cm 2That is, for a fuel cell after attenuation, to achieve a power output of 64kW, the input current must be increased from the inherent 0.5A / cm 2 , corrected to 0.55A / cm 2 .

[0075] Further, such as Figure 2 As shown, the air compressor speed and hydrogen supply device parameters are based on 0.55A / cm 2 The current density is adjusted. The related control and adjustment steps are common knowledge in this industry and will not be repeated here.

[0076] Furthermore, after achieving the above-mentioned power control, the output power is further analyzed and judged. If the requirements are met, the entire power control is terminated; if not, the power is adjusted according to conventional tentative methods. The corresponding control or adjustment methods are also common sense in the industry and will not be repeated here.

[0077] Example 3

[0078] This embodiment provides a method for predicting the life of a marine battery system based on a decay model and historical operating data. The method includes three main steps: Figure 3 As shown in the figure, firstly, the historical operation data is refined into two parameters, namely, the average working time and the attenuation voltage, that is, the multiple variables affecting the attenuation voltage are simplified into the average working time (as the independent variable), while the attenuation voltage is retained as the dependent variable; secondly, the average working time and the attenuation voltage are fitted with a linear function, and the corresponding life threshold is set; finally, based on the fitted linear function and the set life threshold, the expected life of the marine fuel cell system is calculated. Formula 11 is the linear function that needs to be fitted. In Formula 11, a and b are the coefficients of the fitting function, t is the average use time, and U is the life expectancy of the marine fuel cell system. Degradation Same as the above definition, all are single chip voltage attenuation values, which need to be counted and calculated based on historical data as in Example 1. Formula 12 is to calculate U based on the rated power attenuation of 10% as the life threshold Degradation When the maximum value of life decay is reached, U in Formula 12 Initial It represents the initial single chip voltage under rated power conditions. Formula 13 is derived from Formula 11 and Formula 12 and is used to determine U Degradation When the maximum value of life decay is reached, the corresponding maximum usage time t max How much should it be.

[0079] Formula 11: .

[0080] Formula 12: .

[0081] Formula 13: .

[0082] In this embodiment, referring to the calculation results of Example 1, that is, the average working time t is 960h, the single-chip voltage attenuation value U Degradation is 0.0281604V, U Initial is 0.6V; further, to simplify the calculation, select t as 0h, U Degradation 0V is used as the input point of the fitting function. In actual application, the input point in the historical data can be selected as much as possible for more reasonable fitting. According to the working point selected above, the coefficient a can be calculated to be 0.00002933375 and b is 0. Substituting the values ​​of a and b into formula 13, t max It should be 2045h, that is, the predicted life of the marine fuel cell system based on the attenuation model and historical operating data is 2045h, and its predicted remaining life is 1085h (predicted life 2045h minus average working time 960h).

[0083] The above embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit it. Although the present invention is described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention. Those skilled in the art may also make other changes within the spirit of the present invention and apply them to the design of the present invention, as long as they do not deviate from the technical effects of the present invention. These changes made according to the spirit of the present invention should be included in the scope of protection claimed by the present invention.

Claims

1. A marine fuel cell system attenuation model considering the influence of salt spray environment, characterized in that: It consists of the sum of the first and second parts, where: Part 1: Traditional attenuation model for the effects of low power, high power, variable load and start-stop on fuel cell performance attenuation; low power refers to power less than 25kW; high power refers to power greater than 50kW; Part II: Mathematical model for attenuation changes of marine fuel cell systems in salt spray environments; The first part is expressed by formula 1, and the second part is expressed by formula 2. The attenuation models involved in formula 1 are shown in formulas 4, 5, 6, and 7 respectively. The above formulas are as follows: Formula 1: ; Formula 2: ; Formula 3: ; Formula 4: ; Formula 5: ; Formula 6: ; Formula 7: ; Among them U Tradition-degradation Indicates the single chip voltage attenuation value caused by the traditional attenuation model; U Salt-mist Indicates the voltage attenuation value of a single chip caused by a salt spray environment, u Salt-mist Represents the single cell attenuation rate in salt spray environment, t Salt-mist Indicates the operating time in salt spray environment; U Degradation Represents the single-chip voltage attenuation value calculated by the attenuation model; U Start-stop Indicates the single chip voltage attenuation value caused by start-stop conditions, u Start-stop Represents the single battery attenuation rate under start-stop conditions, n Start-stop Indicates the number of start-stop conditions; U Low-power Indicates the single chip voltage attenuation value caused by low power conditions, u Low-power Indicates the decay rate of a single battery under low power conditions, t Low-power Indicates the running time of low power condition; U High-power Indicates the single chip voltage attenuation value caused by high power conditions, u High-power Indicates the single battery attenuation rate under high power conditions, t High-power Indicates the running time of high power condition; U Transient-loading Indicates the single chip voltage attenuation value caused by variable load conditions, u Transient-loading Indicates the decay rate of a single battery under variable load conditions, n Transient-loading Indicates the power change value under variable load conditions.

2. A method for controlling the power of a marine fuel cell system based on the marine fuel cell system attenuation model of claim 1, characterized in that: The following steps are involved: S1: Determine the corresponding relationship between the current density and the target power of the marine fuel cell after attenuation; S2: determining a corrected current density based on the target power demand; S3: Determine the parameters of the air compressor and the hydrogen supply device based on the corrected current density; S4: Determine whether the output power of the marine fuel cell system meets the demand and decide whether to take further actions; The data model of step S1 is as follows: Formula 8: ; Formula 9: ; Formula 10: ; where p Power-density is the power density, U is the single-chip voltage of the fuel cell, i Electriciy-density is the current density; P is the power, A Area is the effective unit area of ​​the membrane electrode, n Cell is the number of membrane electrodes; η is the attenuation change rate, U Degradation The single-chip voltage attenuation value of the attenuation model proposed by the present invention, U Initial is the initial single chip voltage at rated power condition.

3. The marine fuel cell system power control method according to claim 2, characterized in that: In step S1, the attenuation voltage is calculated by the attenuation model of the marine fuel cell system, and then the attenuation change rate of the rated power point is calculated by formula 10, and then the power characteristics of the fuel cell system after attenuation are determined by formulas 8 and 9, that is, the corresponding relationship between the current density and the power of the marine fuel cell after attenuation is determined.

4. The marine fuel cell system power control method according to claim 2, characterized in that: In step S2, based on the corresponding relationship between the current density of the marine fuel cell after attenuation and the target power in step S1, the corrected current density or current is interpolated, looked up in a table or calculated according to the target power.

5. The power control method of a marine fuel cell system based on an attenuation model according to claim 2, characterized in that: In step S4, the operation includes adjusting the current density, and adjusting the air compressor speed, hydrogen supply amount or hydrogen supply pressure parameters.

6. A method for predicting the life of a marine fuel cell system based on the marine fuel cell system power control method according to claim 2, characterized in that: The following steps are involved: T1: Extract historical operation data into two variables: average working time and attenuation voltage; T2: Fit the average working time and attenuation voltage into a linear function and set the life threshold; T3: Calculate the life of the marine fuel cell system based on the fitted linear function and life threshold; The data models in steps T1, T2 and T3 correspond to the following formulas respectively: Formula 11: ; Formula Twelve: ; Formula 13: ; Among them U Degradation is the single-chip voltage attenuation value of the attenuation model, a and b are the coefficients of the fitting function; U Initial is the initial single chip voltage under rated power conditions; t max It is the maximum usage time of the marine fuel cell system calculated based on the existing historical data and attenuation model, that is, the life of the marine fuel cell system.

7. The method for predicting the life of a marine fuel cell system according to claim 6, characterized in that: In step T2, the average working time and the attenuation voltage are fitted to a linear function as shown in formula 11, and the life threshold of the marine fuel cell system is set to a 10% attenuation of the initial single-chip voltage under rated power conditions.

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