CN113567775B - A fault diagnosis and analysis method for liquid hydrogen storage and supply system based on guidance words - Google Patents

Abstract

The invention relates to the technical field of fault diagnosis, in particular to a liquid hydrogen storage and supply system fault diagnosis analysis method based on guide words. The method comprises the following steps: determining a guide word range, a system state range and variables i, j and k, wherein initial values of i, j and k are all 1; then qualitatively analyzing whether the phenomenon of the description of the guide words exists under the normal working condition; then list all possible system faults F, select the system fault F _k Analysis of fault conditions F _k Whether a phenomenon of description of a guide word exists or not; if the phenomenon is different between the normal working condition and the fault condition, the guiding word M is saved _i System state N _j And system failure F _k . The invention can systematically carry out fault diagnosis of the liquid hydrogen storage and supply system, is beneficial to reducing the fault checking time, can effectively optimize the fault control strategy, and has beneficial effects on guiding fault simulation tests, optimizing design flow, saving manpower and time, reducing test cost and even improving the safety of the test process.

Description

A fault diagnosis and analysis method for liquid hydrogen storage and supply system based on guidance words

Technical field

The invention relates to the technical field of fault diagnosis, and in particular to a fault diagnosis and analysis method for a liquid hydrogen storage and supply system based on guide words.

Background technique

In recent years, hydrogen energy has received widespread attention and vigorous development as a green, efficient, and widely sourced clean energy. At present, research on hydrogen energy and related technologies is mainly aimed at vehicles. The storage temperature of liquid hydrogen under normal pressure can reach -253°C, which is far lower than the external ambient temperature. At present, the main hydrogen storage methods include high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, and metal hydride hydrogen storage. The density of liquid hydrogen under normal pressure is 70.85kg/m ³ , which is much higher than the density of hydrogen gas 0.089kg/m ³ (1atm, 0℃). Energy density is an important indicator to measure the quality of hydrogen storage methods. Under this indicator, liquid hydrogen storage has great advantages and therefore has broad application prospects.

The liquid hydrogen storage and supply system refers to a complete process system from the storage unit to the reaction unit, that is, before the fuel cell module. During actual design, low-temperature storage tanks, vaporizers, buffer tanks, valves, instruments and safety accessories are often required in the liquid hydrogen storage and supply system. Compared with other relatively mature application systems, the liquid hydrogen storage and supply system is a new process system that was formed late and needs further research. The system has many components, the process is complex, and the phenomenon is not obvious when there are faults. Fault identification is difficult. Difficult problems; in addition, there are also common difficulties such as lack of operating data and many process influencing factors. At present, there are still few fault diagnosis methods for liquid hydrogen storage and supply, and fault isolation is poor and optimal control strategies are lacking. Considering the characteristics of liquid hydrogen storage faults and the safety of hydrogen use, research on liquid hydrogen storage and supply fault diagnosis methods and analysis processes is urgently needed. carry out.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a fault diagnosis and analysis method for a liquid hydrogen storage and supply system based on guide words, which determines different guide words and system status, and studies different problems in the liquid hydrogen storage and supply system. fault mode, thereby enabling systematic fault diagnosis of the liquid hydrogen storage and supply system; the invention helps to reduce fault troubleshooting time, can effectively optimize fault control strategies, guide fault simulation tests, optimize design processes, save manpower and time, Reducing test costs and even improving the safety of the test process can have a beneficial impact.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A guidance word-based fault diagnosis and analysis method for liquid hydrogen storage and supply systems, which is characterized by including the following steps:

S1, determine the guide word range M = {M ₁ , M ₂ , ..., M _m }, the quantity is m; determine the system state range N = {N ₁ , N ₂ , ..., N _n }, the quantity is n; Determine the variables i, j, and k, and the initial values of i, j, and k are all 1;

S2, select the guide word _Mi ;

S3, select system state N _j ;

S4. Qualitatively analyze whether there is a phenomenon described by the guide word _Mi under normal working conditions;

S5, list all possible system failures of the current liquid hydrogen storage and supply system:

F={F ₁ , F ₂ ,..., F _f };

S6, select system fault F _k ;

S7, analyze whether the phenomenon described by the guide word _Mi exists in the current liquid hydrogen storage and supply system under system failure _Fk ;

S8, determine whether the phenomena produced by steps S4 and S7 are the same;

S9, if the phenomenon is the same in step S8, discard the current fault state and proceed directly to step S10; if the phenomenon is different, record the current fault state, save the guide word _Mi , system status _Nj and system fault _Fk , and then proceed to step S10. ;

S10, enter the inner fault loop steps:

If k<f, then after k+1, jump to step S6 to select the next system fault, and then execute subsequent steps in sequence; otherwise, go to step S11;

S11, enter the middle layer system state loop steps:

If j<n, then j+1 and k=1, jump to step S3 to select the next system state, and then execute subsequent steps in sequence; otherwise, go to step S12;

S12, enter the outer guide word cycle steps:

If i<m, then i+1 and j=k=1, then jump to step S2 to select the next guide word, and then execute subsequent steps in sequence; otherwise, go to step S13;

S13: Verify the fault status detected.

Preferably, in step S13, the verification method is through simulation and/or testing.

Preferably, the fault state is a quantitative description; the verification result in step S13 is used to correct the change pattern and quantified value of the fault state in step S7.

Preferably, the guide words are changes in system monitoring parameters.

Preferably, the system status is the working status of all valves in the pipeline.

The beneficial effects of the present invention are:

1). The present invention adopts an "onion structure" cycle process, which is divided from the inside out into an inner fault loop, an intermediate system status loop, and an outer guide word loop. After all loops are completed, they are further processed through simulation and/or testing. Verification methods are used to conduct further validity verification to improve the accuracy of its judgment. Using the analysis process of the present invention, a fault diagnosis method for the liquid hydrogen storage and supply system can be further obtained, which is helpful for system fault diagnosis and fault isolation, and optimizes fault control strategies. The invention can also be used to guide fault simulation tests, optimize design processes, save manpower and time, reduce test costs and improve the safety of the test process, and has a wide range of uses.

2). The present invention uses changes in monitoring parameters as guide words to highlight various phenomena in fault states, and determines the system status to limit working conditions to solve complex problems in the system process. It distinguishes different process processes and analyzes them one by one, and the effect is significant. .

3). The analysis process of the present invention can be used to guide the design of fault simulation tests. Through the tests, fault sample data can be further accumulated to identify system fault-prone components; even if the new process system lacks operating data, this method can still be used. Invent fault diagnosis analysis. Obviously, the analysis method in the present invention is not only applicable to liquid hydrogen storage and supply systems, but also to other new process systems.

4). During the fault diagnosis and analysis process, it is judged whether the phenomena under normal working conditions and fault conditions are the same, combined with the monitoring parameters and system status determined in the previous steps of the method. This plays a role in fault isolation to a certain extent and assists Determine where the fault occurs in the system and reduce troubleshooting time to further optimize fault control strategies.

5) Further verify the effectiveness of the fault state through tests and/or simulations to ensure the accuracy of fault state analysis. Furthermore, the results of experiments and/or simulations can even be used to quantitatively correct the phenomena caused by system failures, thus achieving continuous optimization. The present invention can also further form a fault simulation prototype to realize the advancement of theoretical methods into engineering applications.

Description of the drawings

Figure 1 is a work flow chart of the present invention;

Figure 2 is a process state diagram of a specific embodiment of the present invention.

The actual correspondence between each label and component name in the present invention is as follows:

a-Liquid hydrogen bottle b-Vaporizer c-Buffer tank d-Water bath reheater

Detailed ways

For ease of understanding, a process state diagram of a liquid hydrogen storage and supply system shown in Figure 2 is provided here, so that the specific structure and working method of the present invention will be further described below in conjunction with the embodiment and the work flow shown in Figure 1 :

In Figure 2, the liquid hydrogen storage and supply system connects the liquid hydrogen bottle a, the air-temperature vaporizer b, the buffer tank c, the water bath reheater d and other components through pipelines equipped with valves and instruments. The main monitoring parameters in this system are: liquid hydrogen bottle a level and pressure, buffer tank c pressure, hydrogen supply pressure and hydrogen supply temperature; the valves in this system mainly include: stop valve V1, stop valve V2, stop valve V3, supply Hydrogen valve V4, hydrogen exhaust valve V5, boosting valve V6, and pressure reducing valve V7; in addition, a safety valve and a one-way valve are also installed in the pipeline.

Here, combined with Figure 2, the system failure of "the safety valve cannot be opened normally" at the drain pipe of the liquid hydrogen bottle a is taken as an example for explanation;

The specific process is as follows:

S1: According to the system monitoring parameters, the guide words are M ₁ : high pressure of the liquid hydrogen bottle; M ₂ : abnormal rise in pressure of the liquid hydrogen bottle;...; the guide word range M={M ₁ , M ₂ ,..., M _m }. The status of the liquid hydrogen storage and supply system mainly considers the switch control of the solenoid valve. The system status mainly includes N ₁ : hydrogen supply valve closed, hydrogen discharge valve closed, boosting valve closed; N ₂ : hydrogen supply valve closed, hydrogen discharge valve closed, boost valve closed. The pressure valve is open;...; the system state range is N={N ₁ , N ₂ ,..., N _n }. Make sure that the initial values of variables i, j, and k are all 1.

S2: Select the guide word M _i =1, which is the high pressure of the liquid hydrogen bottle.

S3: Select the system state N _j =1, that is, the hydrogen supply valve is closed, the hydrogen exhaust valve is closed, and the boosting valve is closed.

S4: Under normal working conditions, the phenomenon is: the pressure of the liquid hydrogen bottle rises slowly, usually by 0.1MPa in several hours, which depends on the cold-keeping performance of the low-temperature liquid hydrogen bottle. When the pressure in the liquid hydrogen bottle is greater than the safety valve trip pressure P _Svs , the safety valve opens normally, reducing the pressure to below the safety valve trip pressure P _Svs , and the excessive pressure phenomenon described in the guide words will not occur.

S5: Possible faults include F ₁ : the safety valve cannot open normally; F ₂ : the cooling performance of the liquid hydrogen bottle is degraded; ...; the system fault range F = {F ₁ , F ₂ , ..., F _f }.

S6: Select system fault F _k =1, that is, the safety valve cannot open normally.

S7: System failure _F1 , that is, when the safety valve cannot be opened normally, the phenomenon is: after the pressure of the liquid hydrogen bottle exceeds the safety valve trip pressure P _Svs , the pressure in the bottle does not decrease, and the pressure still shows a gradual upward trend after several hours.

S8: Compare step S5 and step S7 to learn that the phenomena under normal working conditions and fault conditions are different;

S9: Save the guide word M ₁ , system status N ₁ and system fault F ₁ .

S10: At this time, the system fault type has not completed the cycle. For K+1, that is, the system fault _F2 is executed: the cooling performance of the liquid hydrogen bottle is degraded. Enter step S6, and execute steps S7, S8, S9, and S10 in sequence. Cycle. When all system fault types have been cycled, enter the next step.

S11: At this time, the system state has not completed the cycle, and the system state N ₂ is executed, that is, the system state in which the hydrogen supply valve is closed, the hydrogen exhaust valve is closed, and the boosting valve is open, and k=1 in the system failure at this time, enter step S3. And execute steps S4 to S11 in sequence, and then proceed to the next step when all system status cycles are completed.

S12: At this time, the guidance word has not completed the cycle, and enters the guidance word M ₂ , that is, the guidance word for the abnormal increase in the pressure of the liquid hydrogen bottle, and j=k=1 in the system status and system failure at this time, enter step S2, and follow Steps S2 to S12 are executed sequentially, and the loop is continued. When the introductory word loop is completed, the next step is entered.

S13: After all analysis of the guidance words and system status is completed, the fault state and even the effectiveness of the present invention can be further verified through simulation and/or testing, and the fault phenomenon described by the guidance words can be quantitatively corrected.

After the above analysis, it can be concluded that the safety valve trip pressure value P _Svs can be used as a criterion for judging whether a fault occurs, and this value can be used for fault diagnosis methods in fault simulation prototypes.

Of course, for those skilled in the art, the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is therefore intended that all claims falling within the claims All changes within the meaning and scope of equivalent elements are included in the present invention. Any reference signs in the claims shall not be construed as limiting the claim in question.

In addition, it should be understood that although this specification is described in terms of implementations, not each implementation only contains an independent technical solution. This description of the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole. , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

The technology, shape, and structural parts not described in detail in the present invention are all known technologies.

Claims (5)

1. A guidance word-based fault diagnosis and analysis method for liquid hydrogen storage and supply systems, which is characterized by including the following steps: S1, determine the guide word range M = {M ₁ , M ₂ , ..., M _m }, the quantity is m; determine the system state range N = {N ₁ , N ₂ , ..., N _n }, the quantity is n; Determine the variables i, j, and k, and the initial values of i, j, and k are all 1; S2, select the guide word _Mi ; S3, select system state N _j ; S4. Qualitatively analyze whether there is a phenomenon described by the guide word _Mi under normal working conditions; S5, list all possible system failures of the current liquid hydrogen storage and supply system: F={F ₁ , F ₂ ,..., F _f }; S6, select system fault F _k ; S7, analyze whether the phenomenon described by the guide word _Mi exists in the current liquid hydrogen storage and supply system under system failure _Fk ; S8, determine whether the phenomena produced by steps S4 and S7 are the same; S9, if the phenomenon is the same in step S8, discard the current fault state and proceed directly to step S10; if the phenomenon is different, record the current fault state, save the guide word _Mi , system status _Nj and system fault _Fk , and then proceed to step S10. ; S10, enter the inner fault loop steps: If k<f, then after k+1, jump to step S6 to select the next system fault, and then execute subsequent steps in sequence; otherwise, go to step S11; S11, enter the middle layer system state loop steps: If j<n, then j+1 and k=1, jump to step S3 to select the next system state, and then execute subsequent steps in sequence; otherwise, go to step S12; S12, enter the outer guide word cycle steps: If i<m, then i+1 and j=k=1, then jump to step S2 to select the next guide word, and then execute subsequent steps in sequence; otherwise, go to step S13; S13: Verify the fault status detected. 2. A guidance word-based fault diagnosis and analysis method for a liquid hydrogen storage and supply system according to claim 1, characterized in that: in step S13, the verification method is through simulation and/or testing. 3. A guidance word-based liquid hydrogen storage and supply system fault diagnosis and analysis method according to claim 1 or 2, characterized in that: the fault state is a quantitative description; the verification result of step S13 is used to correct step S7 Change patterns and quantified values of fault conditions. 4. A liquid hydrogen storage and supply system fault diagnosis and analysis method based on guide words according to claim 1 or 2, characterized in that: the guide words are changes in system monitoring parameters. 5. A guidance word-based fault diagnosis and analysis method for a liquid hydrogen storage and supply system according to claim 1 or 2, characterized in that: the system status is the working status of all valves in the pipeline.