A method and system for ammonia engine fuel supply system maintenance decision based on D-S evidence theory

Abstract

The application provides a kind of ammonia engine fuel supply system maintenance decision method and system based on D-S evidence theory, comprising: according to the maintenance complexity of equipment in ammonia engine fuel supply system, establish maintenance recommendation framework;Maintenance recommendation framework includes single maintenance recommendation and composite maintenance recommendation;According to the fault damage degree of equipment, system state prediction value and running time, establish decision evidence set;According to maintenance recommendation framework and decision evidence set, establish maintenance decision basic probability distribution matrix;D-S evidence theory is used to make decision level fusion to the normalized maintenance decision basic probability distribution matrix, obtain the comprehensive probability value of ammonia engine fuel supply system maintenance recommendation;Based on the selection of preset decision rule to comprehensive probability value, obtain the maintenance decision result of ammonia engine fuel supply system equipment.The maintenance decision method proposed in the application can provide comprehensive and effective maintenance recommendations for ammonia engine fuel supply system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power mechanical equipment maintenance decision, and particularly relates to an ammonia engine fuel supply system maintenance decision method and system based on D-S evidence theory. BACKGROUND

[0002] The use of ammonia engines can significantly reduce greenhouse gas emissions and has high power output, and plays an important role in promoting carbon neutralization. Therefore, the research on ammonia engines has strategic significance in realizing environmental benefits. Among them, the ammonia engine fuel supply system is a key system for providing fuel to the ammonia engine, and its reliable operation is a basic prerequisite for the normal operation of the ammonia engine. Therefore, it is of great significance to implement timely and accurate maintenance activities on the ammonia engine fuel supply system.

[0003] Maintenance decision refers to providing scientific maintenance suggestions according to monitoring data and state prediction information of a system or equipment in its maintenance activities. A reasonable maintenance decision method can effectively guide the maintenance work of the system or equipment, guide the selection of the best maintenance time, and is an important auxiliary means to improve the operation safety and stability thereof. In practical applications, the maintenance decision directly affects the development effect of the ammonia engine fuel supply system maintenance activities and is related to the working state thereof. In addition, various information needs to be comprehensively referred to in the maintenance decision process, and the uncertainty factors in the information should also be considered in the decision-making. The above situations are all keys of the maintenance decision. Therefore, it is of great importance to research a comprehensive and effective maintenance decision method to provide accurate auxiliary maintenance suggestions for the ammonia engine fuel supply system, which is crucial for reducing the failure rate of the ammonia engine fuel supply system and improving the operation safety and economy of the ammonia engine.

[0004] The prior art is a method for designing maintenance decision of an aero-engine based on failure probability prediction, comprising the following steps: obtaining historical operation data of the aero-engine collected by multiple sensors; extracting and screening degradation features based on the historical operation data of the aero-engine collected by the multiple sensors; predicting failure probabilities in different time windows in the future through single-step iteration based on the screened degradation features; and determining the best time for predictive maintenance by online evaluating maintenance cost based on the failure probability prediction results. The method can realize maintenance decision of the aero-engine, and can maximize the system life and reduce the maintenance cost. However, the method only formulates the maintenance strategy of the aero-engine according to the failure probability, and cannot comprehensively reflect the actual operation state, so that the maintenance decision process is oversimplified, it is difficult to make targeted maintenance decision of the aero-engine, and finally the accuracy and objectivity of the decision result are affected. When the structure of the maintenance object is complex, a single decision evidence cannot comprehensively represent the state, which will enhance the uncertainty of the decision process and finally affect the scientificity of the decision result. Therefore, it is urgent to research a maintenance decision method capable of combining multiple decision evidences and fully considering the uncertainty thereof, to provide reliable maintenance suggestions for the aero-engine fuel supply system. SUMMARY

[0005] To solve the problem of providing maintenance suggestions for the amino engine fuel supply system under multiple decision evidences, the present application provides a D-S evidence theory-based maintenance decision method and system for the amin engine fuel supply system, which uses the equipment failure hazard degree, system state prediction value and operation time of the amin engine fuel supply system as a decision evidence set, and sets a composite maintenance suggestion to fully consider the uncertainty contained in the decision evidence, to provide auxiliary decision support for maintenance personnel.

[0006] To achieve the above object, the present application provides the following solutions.

[0007] A D-S evidence theory-based maintenance decision method for the amin engine fuel supply system, comprising the following steps:

[0008] According to the maintenance complexity of the equipment in the amin engine fuel supply system, a maintenance suggestion framework is established, wherein the maintenance suggestion framework comprises a single maintenance suggestion and a composite maintenance suggestion;

[0009] According to the failure hazard degree, system state prediction value and operation time of the equipment in the amin engine fuel supply system, a decision evidence set is established;

[0010] According to the maintenance suggestion framework and the decision evidence set, a maintenance decision basic probability distribution matrix is established;

[0011] The maintenance decision basic probability assignment matrix is normalized, and D-S evidence theory is used to perform decision level fusion on the normalized maintenance decision basic probability assignment matrix to obtain a comprehensive probability value of the ammonia engine fuel supply system maintenance suggestion.

[0012] The comprehensive probability value is selected based on a preset decision rule to obtain a maintenance decision result of the ammonia engine fuel supply system equipment.

[0013] Preferably, the method for establishing the maintenance decision basic probability assignment matrix comprises:

[0014] According to the membership function between the single maintenance suggestion and the decision evidence set, the basic probability assignment of the single maintenance suggestion corresponding to each decision evidence is obtained.

[0015] Based on the basic probability assignment of the single maintenance suggestion, the basic probability assignment of the compound maintenance suggestion corresponding to each decision evidence is obtained.

[0016] Based on the basic probability assignment of the single maintenance suggestion and the basic probability assignment of the compound maintenance suggestion, the maintenance decision basic probability assignment matrix is obtained.

[0017] Preferably, the method for obtaining the comprehensive probability value of the ammonia engine fuel supply system maintenance suggestion comprises:

[0018] According to the basic probability assignment of the maintenance suggestion corresponding to different decision evidences, a conflict factor for measuring the contradiction degree between the decision evidences is obtained.

[0019] Based on the conflict factor and the basic probability assignment of the maintenance suggestion corresponding to different decision evidences, the comprehensive probability value of the ammonia engine fuel supply system maintenance suggestion is obtained.

[0020] Preferably, the preset decision rule comprises:

[0021] If the maximum comprehensive probability value corresponds to the compound maintenance suggestion, the maintenance decision of the ammonia engine fuel supply system is delayed;

[0022] If the maximum comprehensive probability value corresponds to the single maintenance suggestion, the single maintenance suggestion is taken as the final decision result of the ammonia engine fuel supply system.

[0023] The application also provides an ammonia engine fuel supply system maintenance decision system based on D-S evidence theory, which is used to implement the maintenance decision method and comprises:

[0024] A maintenance suggestion framework construction module is configured to establish a maintenance suggestion framework according to the maintenance complexity of the equipment in the ammonia engine fuel supply system; wherein the maintenance suggestion framework comprises single maintenance suggestions and compound maintenance suggestions.

[0025] a decision evidence set construction module, configured to construct a decision evidence set according to a fault damage degree of equipment in the ammonia engine fuel supply system, a system state prediction value, and a running time length;

[0026] a basic probability assignment module, configured to construct a maintenance decision basic probability assignment matrix according to the maintenance suggestion framework and the decision evidence set;

[0027] a comprehensive probability value calculation module, configured to normalize the maintenance decision basic probability assignment matrix, and perform decision level fusion on the normalized maintenance decision basic probability assignment matrix by using a D-S evidence theory to obtain a comprehensive probability value of the ammonia engine fuel supply system maintenance suggestion;

[0028] a maintenance decision result acquisition module, configured to select the comprehensive probability value based on a preset decision rule to obtain a maintenance decision result of the ammonia engine fuel supply system equipment.

[0029] Preferably, the basic probability assignment module comprises:

[0030] a single maintenance suggestion basic probability assignment unit, configured to obtain a basic probability assignment of a single maintenance suggestion corresponding to each decision evidence according to a membership function between the single maintenance suggestion and the decision evidence set;

[0031] a compound maintenance suggestion basic probability assignment unit, configured to obtain a basic probability assignment of a compound maintenance suggestion corresponding to each decision evidence based on the basic probability assignment of the single maintenance suggestion;

[0032] a basic probability assignment matrix acquisition unit, configured to obtain the maintenance decision basic probability assignment matrix based on the basic probability assignment of the single maintenance suggestion and the basic probability assignment of the compound maintenance suggestion.

[0033] Preferably, the comprehensive probability value calculation module comprises:

[0034] a conflict factor calculation unit, configured to obtain a conflict factor used to measure a contradiction degree between decision evidences according to the basic probability assignments of the maintenance suggestions corresponding to different decision evidences;

[0035] a comprehensive probability value calculation unit, configured to obtain the comprehensive probability value of the ammonia engine fuel supply system maintenance suggestion based on the conflict factor and the basic probability assignments of the maintenance suggestions corresponding to different decision evidences.

[0036] Preferably, the preset decision rule in the maintenance decision result acquisition module comprises:

[0037] if the maximum comprehensive probability value corresponds to a compound maintenance suggestion, postponing the maintenance decision of the ammonia engine fuel supply system;

[0038] If the maximum comprehensive probability value corresponds to a single repair suggestion, the single repair suggestion is taken as the final decision result of the ammonia engine fuel supply system.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The ammonia engine fuel supply system repair decision method based on D-S evidence theory provided by the present application combines equipment failure hazard degree, state prediction value and running time length three kinds of decision evidences to provide reliable repair suggestions for the ammonia engine fuel supply system, avoiding the problem of inaccurate and lack of objectivity of decision results when using single decision evidence for repair decision. In addition, the present application uses the membership function method to set the basic probability distribution of the decision evidence to make the distribution result more objective, and by setting single repair suggestion and composite repair suggestion, the uncertainty in the decision process of the ammonia engine fuel supply system is reflected, thereby comprehensively improving the accuracy and pertinence of the repair decision result. The repair decision result of the present application can assist the maintenance personnel to implement repair activities on the ammonia engine fuel supply system, and ensure the operation safety of the ammonia engine fuel supply system. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the present application, the following briefly introduces the drawings needed to be used in the embodiments. Obviously, the drawings described in the following embodiments are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 The flow chart of the ammonia engine fuel supply system repair decision method based on D-S evidence theory of the present application embodiment;

[0043] Figure 2 The repair decision execution flow chart of the present application embodiment;

[0044] Figure 3 The membership function diagram of the present application embodiment. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0046] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0047] Embodiment one

[0048] As Figure 1 , Figure 2 shown, a D-S evidence theory-based ammonia engine fuel supply system maintenance decision-making method, comprising the following steps:

[0049] S1: According to the maintenance complexity of the equipment in the ammonia engine fuel supply system, a maintenance recommendation framework A={a1, a2,…,a j} is established; the maintenance recommendation framework A of the ammonia engine fuel supply system includes j-1 single maintenance recommendations (a1, a2,…,a j-1 ) and a single composite maintenance recommendation a j . The composite maintenance recommendation is composed of all single maintenance recommendations, representing the uncertainty when making decisions on the ammonia engine fuel supply system.

[0050] S2: According to the fault hazard degree m1 of the equipment in the ammonia engine fuel supply system, the system state prediction value m2 and the running time m3, a decision evidence set M={m1, m2,…,m i} is established, which is used to guide the maintenance decision of the equipment in the ammonia engine fuel supply system.

[0051] S3: According to the maintenance recommendation framework and the decision evidence set, a maintenance decision basic probability distribution matrix is established;

[0052] Further embodiments are that the method for establishing the maintenance decision basic probability distribution matrix comprises:

[0053] S31: According to the membership function between the single maintenance recommendation and the decision evidence set, the basic probability distribution of each single maintenance recommendation corresponding to each decision evidence is obtained; specifically, the basic probability distribution m i (a j-1 ) of the single maintenance recommendation is realized by establishing the membership function between m i and a j-1 . The function quantifies the correlation between the maintenance recommendation a j-1 and the decision evidence m i , and further reflects the support degree of the i-th decision evidence for the j-1-th maintenance recommendation, and the specific form is:

[0054] m i (a j-1 )=f(m i ,a j-1 ),

[0055] Wherein, f is the membership function.

[0056] S32: Based on the basic probability distribution of single repair suggestion, the basic probability distribution of composite repair suggestion corresponding to each decision evidence is obtained, and the calculation formula is as follows:

[0057] m i (a j )=1-max(m i (a j-1 )),

[0058] Wherein, m i (a j ) represents the basic probability distribution of composite repair suggestion corresponding to each decision evidence, and m i (a j-1 ) represents the basic probability distribution of single repair suggestion corresponding to each decision evidence.

[0059] S33: Based on the basic probability distribution of single repair suggestion and the basic probability distribution of composite repair suggestion, the basic probability distribution matrix of repair decision is obtained.

[0060] Specifically, the relationship between repair suggestion a j and decision evidence m i is obtained according to S31, and the basic probability distribution m i (a j ) of each decision evidence corresponding to repair suggestion is obtained according to S32 and S33, and the basic probability distribution matrix P=(m i (a j )) i×j of repair decision of ammonia engine fuel supply system equipment is established, and the specific form is:

[0061]

[0062] S4: The basic probability distribution matrix of repair decision is normalized, and the normalized repair decision basic probability distribution matrix is fused at decision level by using D-S evidence theory, so as to obtain the comprehensive probability value of ammonia engine fuel supply system repair suggestion.

[0063] In this embodiment, the basic probability distribution matrix P is normalized to ensure that the sum of m i (a j ) under each decision evidence is 1. The basic probability distribution normalization formula is:

[0064]

[0065] Wherein, m i (a j )' represents the normalized result, and n is the number of repair suggestions. In order to describe simply, the basic probability distribution in the following content is the normalized result and is uniformly represented as mi (a j ) form.

[0066] Further embodiments are directed to a method for obtaining a comprehensive probability value of a maintenance suggestion for an ammonia engine fuel supply system, comprising:

[0067] According to basic probability distribution of maintenance suggestions corresponding to different decision evidences, a conflict factor between decision evidences is obtained; specifically, in the D-S evidence theory, the conflict factor k is used to measure the degree of contradiction between decision evidences, and the parameter can affect the final combination result, and the calculation formula is:

[0068]

[0069] Wherein, m z (a zj ) and m q (a qj ) represent the basic probability distribution of maintenance suggestions corresponding to two different decision evidences when making maintenance decisions for the ammonia engine fuel supply system, a zj and a qj are maintenance suggestions when the decision evidence is m z , m q .

[0070] Based on the conflict factor and the basic probability distribution of maintenance suggestions corresponding to different decision evidences, a comprehensive probability value of the maintenance suggestion for the ammonia engine fuel supply system is obtained. Specifically, the combination formula of the basic probability distribution of two different decision evidences is as follows:

[0071]

[0072] Wherein, represents the comprehensive probability value of the maintenance suggestion a z after the combination of the decision evidences m q and m j .

[0073] S5: Based on the preset decision rule, the comprehensive probability value is selected to obtain the maintenance decision result of the ammonia engine fuel supply system equipment.

[0074] Further embodiments are directed to a method for obtaining a comprehensive probability value of a maintenance suggestion for an ammonia engine fuel supply system, comprising:

[0075] If the maximum comprehensive probability value corresponds to a complex maintenance suggestion, the maintenance decision for the ammonia engine fuel supply system is delayed;

[0076] If the maximum comprehensive probability value corresponds to a single maintenance suggestion, the single maintenance suggestion is taken as the final decision result of the ammonia engine fuel supply system.

[0077] In another aspect, the present application also provides an ammonia engine fuel supply system maintenance decision system based on D-S evidence theory, for implementing the maintenance decision method, comprising:

[0078] a maintenance recommendation framework modeling module, configured to establish a maintenance recommendation framework according to the maintenance complexity of the equipment in the ammonia engine fuel supply system; wherein the maintenance recommendation framework comprises a single maintenance recommendation and a composite maintenance recommendation;

[0079] a decision evidence set modeling module, configured to establish a decision evidence set according to the fault damage degree of the equipment in the ammonia engine fuel supply system, the system state prediction value and the running time;

[0080] a basic probability assignment module, configured to establish a maintenance decision basic probability assignment matrix according to the maintenance recommendation framework and the decision evidence set;

[0081] a comprehensive probability value calculation module, configured to normalize the maintenance decision basic probability assignment matrix, and perform decision level fusion on the normalized maintenance decision basic probability assignment matrix using D-S evidence theory to obtain a comprehensive probability value of the ammonia engine fuel supply system maintenance recommendation;

[0082] a maintenance decision result acquisition module, configured to select the comprehensive probability value based on a preset decision rule to obtain a maintenance decision result of the equipment in the ammonia engine fuel supply system.

[0083] Further embodiments are that the basic probability assignment module comprises:

[0084] a single maintenance recommendation basic probability assignment unit, configured to obtain a basic probability assignment of each decision evidence corresponding to the single maintenance recommendation according to a membership function between the single maintenance recommendation and the decision evidence set;

[0085] a composite maintenance recommendation basic probability assignment unit, configured to obtain a basic probability assignment of each decision evidence corresponding to the composite maintenance recommendation based on the basic probability assignment of the single maintenance recommendation;

[0086] a basic probability assignment matrix acquisition unit, configured to obtain the maintenance decision basic probability assignment matrix based on the basic probability assignment of the single maintenance recommendation and the basic probability assignment of the composite maintenance recommendation.

[0087] Further embodiments are that the comprehensive probability value calculation module comprises:

[0088] a conflict factor calculation unit, configured to obtain a conflict factor for measuring the contradiction degree between the decision evidences according to the basic probability assignments of the maintenance recommendations corresponding to different decision evidences;

[0089] The comprehensive probability value calculation unit is configured to obtain a comprehensive probability value of the maintenance suggestion for the ammonia engine fuel supply system based on the conflict factor and the basic probability distribution of the different decision evidences corresponding to the maintenance suggestion.

[0090] Further, the preset decision rule in the maintenance decision result acquisition module comprises:

[0091] If the maximum comprehensive probability value corresponds to the compound maintenance suggestion, the maintenance decision for the ammonia engine fuel supply system is delayed;

[0092] If the maximum comprehensive probability value corresponds to the single maintenance suggestion, the single maintenance suggestion is taken as the final decision result of the ammonia engine fuel supply system.

[0093] Embodiment Two

[0094] The embodiment discloses a maintenance decision method for a high-pressure fuel pump of an ammonia engine fuel supply system based on D-S evidence theory, as shown in Figure 2 The embodiment is implemented according to the following steps:

[0095] Step 1: A maintenance suggestion framework A = {a1, a2, a3, a4} is established according to the complexity of the maintenance of the high-pressure fuel pump in the ammonia engine fuel supply system, which includes single maintenance suggestions a1, a2, and a3 for the high-pressure fuel pump and a compound maintenance suggestion a4 = (a1, a2, a3). Wherein, a1, a2, and a3 respectively represent strengthened monitoring, cleaning of the pump body, and replacement of the pump body, and a4 represents that a1, a2, or a3 can be used as a maintenance suggestion, that is, the decision result of the high-pressure fuel pump according to the current decision evidence has great uncertainty.

[0096] Step 2: A decision evidence set M = {m1, m2, m3} is defined, wherein m1, m2, and m3 are respectively a state prediction value of the ammonia engine fuel supply system, a fault hazard degree m2 of the high-pressure fuel pump, and an operation time m3 of the high-pressure fuel pump.

[0097] Step 3: According to the relationship between the maintenance suggestions a j and the decision evidences m j , a basic probability distribution m i (a j ) corresponding to the maintenance suggestion of each decision evidence of the high-pressure fuel pump is set, and the specific steps are as follows:

[0098] (1) First, the membership functions between m i and a1, a2, and a3 are respectively established to set the basic probability distribution m i (a p ) of the single maintenance suggestion. The function quantifies the single maintenance suggestion (a1, a2, a3) of the high-pressure fuel pump and the decision evidence mi The degree of correlation between them, the membership function established is as follows:

[0099]

[0100] Among them, c determines m i (a p ) reaches its peak value m i The size of m i (a p ) width, k represents m i (a p ) growth rate, x is the center point. The membership function established according to the above formula is as follows Figure 3 As shown;

[0101] (2) Allocate m based on the basic probability of the single maintenance suggestion obtained i (a p ) Obtain the basic probability distribution m of the composite maintenance recommendation for the high-pressure fuel pump i (a4), the calculation formula is:

[0102] m i (a4)=1-max(m i (a p ))p=1,2,3

[0103] Among them, m i (a p ) represents the basic probability distribution of each decision evidence corresponding to the maintenance suggestion a1, a2 or a3, m i (a4) represents the basic probability distribution of each decision evidence corresponding to the a4 maintenance suggestion;

[0104] (3) According to the results obtained in steps (2) and (3), the basic probability distribution matrix P of the high-pressure fuel pump maintenance decision is established. i (a j )) 3×4 , the specific form is:

[0105]

[0106] Step 4: Normalize the basic probability distribution matrix P in step 3 to ensure that m under each decision evidence i (a j ) is 1, and the normalization formula is:

[0107]

[0108] Among them, m i (a j)' represents the normalized result. For the sake of simplicity, the basic probability distribution in the following content defaults to the normalized result and is uniformly expressed as m i (a j ) in the form of .

[0109] Step 5: Combine the P in step 4 using DS evidence theory to achieve decision-level fusion, and finally obtain the comprehensive probability value m(a j ), the specific steps are:

[0110] (1) First, the conflict factor k between the decision evidence is calculated. This parameter is directly related to the final maintenance recommendation for the high-pressure fuel pump. Its calculation formula is:

[0111]

[0112] Among them, m z (a zj ) and m q (a qj ) are the basic probability distributions of two different decision evidences, a zj and a qj Then they are respectively the decision evidence m z and m q Repair suggestions below;

[0113] (2) The basic probability distribution of the high-pressure fuel pump decision evidence is combined, and the combination formula is as follows:

[0114]

[0115] in, Representative decision evidence m z and m q Repair suggestions after assembly j Since there are three decision evidences, it is necessary to first combine m1(a j ) and m2(a j ) and then the result of the combination is combined with m3(a j ) is combined to obtain the comprehensive probability distribution m(a j ), the specific formula is:

[0116]

[0117] Step 6: Select the comprehensive probability value of the decision evidence using the decision rule. If maintenance suggestion a4 has the highest comprehensive probability value, postpone the decision on the high-pressure fuel pump. If the maintenance suggestion with the highest comprehensive probability value is a1, a2, or a3, then output it as the final maintenance suggestion for the high-pressure fuel pump.

[0118] The above-described embodiments are merely intended to describe the preferred modes of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements to the present application made by those skilled in the art are intended to fall within the scope of the present application defined by the claims.

Claims

1. A maintenance decision-making method for an ammonia engine fuel supply system based on DS evidence theory, characterized in that: The following steps are involved: Establish a maintenance recommendation framework based on the maintenance complexity of the equipment in the ammonia engine fuel supply system; the maintenance recommendation framework includes single maintenance recommendations and complex maintenance recommendations; Establish a decision-making evidence set based on the failure hazard level of the equipment in the ammonia engine fuel supply system, the system state prediction value, and the operating time; Establishing a maintenance decision basic probability distribution matrix based on the maintenance suggestion framework and the decision evidence set; The maintenance decision basic probability distribution matrix is ​​normalized, and the normalized maintenance decision basic probability distribution matrix is ​​fused at the decision level using the DS evidence theory to obtain a comprehensive probability value of the maintenance recommendation for the ammonia engine fuel supply system; Selecting the comprehensive probability value based on a preset decision rule to obtain a maintenance decision result for the ammonia engine fuel supply system equipment; The methods for establishing the basic probability distribution matrix for maintenance decision-making include: Obtaining a basic probability distribution of the single maintenance suggestion corresponding to each decision evidence according to a membership function between the single maintenance suggestion and the decision evidence set; Based on the basic probability distribution of a single maintenance suggestion, the basic probability distribution of the composite maintenance suggestion corresponding to each decision evidence is obtained; Obtaining the maintenance decision basic probability distribution matrix based on the basic probability distribution of the single maintenance suggestion and the basic probability distribution of the composite maintenance suggestion; The method for obtaining a comprehensive probability value for maintenance recommendations for the ammonia engine fuel supply system includes: According to the basic probability distribution of maintenance suggestions corresponding to different decision evidences, a conflict factor is obtained to measure the degree of contradiction between decision evidences. Obtaining a comprehensive probability value of a maintenance suggestion for the ammonia engine fuel supply system based on the conflict factors and the basic probability distribution of maintenance suggestions corresponding to different decision evidences; The preset decision rules include: If the maximum comprehensive probability value corresponds to a composite maintenance recommendation, the maintenance decision on the ammonia engine fuel supply system is postponed; If the maximum comprehensive probability value corresponds to a single maintenance suggestion, the single maintenance suggestion is used as the final decision result of the ammonia engine fuel supply system.

2. A maintenance decision system for an ammonia engine fuel supply system based on DS evidence theory, used to implement the maintenance decision method according to claim 1, characterized in that: include: A maintenance suggestion framework building module is used to establish a maintenance suggestion framework based on the maintenance complexity of the equipment in the ammonia engine fuel supply system; wherein the maintenance suggestion framework includes single maintenance suggestions and composite maintenance suggestions; A decision evidence set building module is used to build a decision evidence set based on the degree of failure hazard of equipment in the ammonia engine fuel supply system, the system state prediction value, and the operating time; A basic probability allocation module, configured to establish a basic probability allocation matrix for maintenance decision-making based on the maintenance suggestion framework and the decision evidence set; a comprehensive probability value calculation module, configured to normalize the maintenance decision basic probability distribution matrix and perform decision-level fusion on the normalized maintenance decision basic probability distribution matrix using DS evidence theory to obtain a comprehensive probability value for maintenance recommendations for the ammonia engine fuel supply system; The maintenance decision result acquisition module is used to select the comprehensive probability value based on a preset decision rule to obtain a maintenance decision result of the ammonia engine fuel supply system equipment.

3. The ammonia engine fuel supply system maintenance decision system based on DS evidence theory according to claim 2 is characterized in that: The basic probability allocation module includes: A single maintenance suggestion basic probability allocation unit is used to obtain a basic probability allocation of the single maintenance suggestion corresponding to each decision evidence according to a membership function between the single maintenance suggestion and the decision evidence set; A composite maintenance suggestion basic probability allocation unit is used to obtain a basic probability allocation of the composite maintenance suggestion corresponding to each decision evidence based on the basic probability allocation of a single maintenance suggestion; The basic probability distribution matrix acquisition unit is configured to obtain the maintenance decision basic probability distribution matrix based on the basic probability distribution of the single maintenance suggestion and the basic probability distribution of the composite maintenance suggestion.

4. The ammonia engine fuel supply system maintenance decision system based on DS evidence theory according to claim 2 is characterized in that: The comprehensive probability value calculation module includes: A conflict factor calculation unit is used to obtain a conflict factor to measure the degree of contradiction between decision evidences based on the basic probability distribution of maintenance suggestions corresponding to different decision evidences; The comprehensive probability value calculation unit is used to obtain a comprehensive probability value of the maintenance suggestion for the ammonia engine fuel supply system based on the conflict factor and the basic probability distribution of the maintenance suggestions corresponding to different decision evidences.

5. The ammonia engine fuel supply system maintenance decision system based on DS evidence theory according to claim 2 is characterized in that: The preset decision rules in the maintenance decision result acquisition module include: If the maximum comprehensive probability value corresponds to a composite maintenance recommendation, the maintenance decision on the ammonia engine fuel supply system is postponed; If the maximum comprehensive probability value corresponds to a single maintenance suggestion, the single maintenance suggestion is used as the final decision result of the ammonia engine fuel supply system.

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