A risk assessment and grading method and system for hydrogen-blended natural gas pipelines

Abstract

The present application relates to the field of energy safety technology, and provides a risk assessment and grading method and system for hydrogen-blended natural gas pipelines. The risk assessment and grading method for hydrogen-blended natural gas pipelines fully combines the interactive coupling between various risk factors during the operation of hydrogen-blended natural gas pipelines, comprehensively monitors the risk situation of hydrogen-blended natural gas pipelines, and realizes quantitative evaluation of risks during the operation of hydrogen-blended natural gas pipelines, making the risk assessment of hydrogen-blended natural gas pipelines more objective, no longer affected by human factors, and more accurate, which helps to accurately grasp the safety status of hydrogen-blended natural gas pipelines during operation, thereby implementing effective preventive control measures, minimizing possible damage and economic losses, and ensuring the safety of public life and property.

Description

Technical Field

[0001] The present application relates to the field of energy safety technology, and in particular to a risk assessment and grading method and system for hydrogen-blended natural gas pipelines. Background Art

[0002] As a clean energy, hydrogen energy is currently the main means of transporting hydrogen energy by using the existing natural gas pipeline network to achieve large-scale, long-distance, and low-cost hydrogen energy storage and transportation.

[0003] Although natural gas pipeline technology is mature, hydrogen-mixed natural gas pipelines and end-user equipment have brought new safety and technical problems. Hydrogen has low ignition energy and low self-ignition temperature. Once a pipeline leaks, it will cause the explosion of hydrogen-mixed natural gas, which will cause more serious consequences than the explosion of pure natural gas, significantly increasing the safety risks during its storage and use.

[0004] However, the current risk assessment of hydrogen-blended natural gas pipelines mostly relies on qualitative or semi-quantitative methods, and on indicator weights determined by expert scoring. These methods are highly subjective and lack consideration of the interactive coupling between risk factors, resulting in extremely inaccurate risk assessment grading for hydrogen-blended natural gas pipelines.

[0005] Therefore, there is an urgent need to provide a technical solution to the above-mentioned deficiencies in the prior art. Summary of the invention

[0006] The purpose of the present application is to provide a risk assessment and grading method and system for hydrogen-blended natural gas pipelines to solve or alleviate the problems existing in the above-mentioned prior art.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] The present application provides a risk assessment and grading method for hydrogen-blended natural gas pipelines, including:

[0009] Step S101: Determine the risk assessment index N of the hydrogen-blended natural gas pipeline according to the operational risk factors of the hydrogen-blended natural gas pipeline. i , to construct the risk assessment index system of the hydrogen-blended natural gas pipeline; wherein, i∈n, i and n are both positive integers, and n is the number of the risk assessment indicators;

[0010] Step S102: According to the risk assessment index N i The comprehensive weighted risk P between the n risk assessment indicators in the risk assessment indicator system ii and P ij , the calculation method is as follows:

[0011]

[0012] Where P ii is the risk assessment index N i The comprehensive weighted risk compared with itself, P ij is the risk assessment index N i The risk assessment index N j The comprehensive weighted risk of comparison; j∈n, j is a positive integer;

[0013] Based on the comprehensive weighted risk P ii and P ij , establish the risk assessment index N i The hierarchical comparison judgment matrix X is as follows:

[0014]

[0015] Based on the hierarchical comparison judgment matrix X, determine the risk assessment index N i The key target weight Z i , as shown below:

[0016]

[0017] Step S103: the risk assessment index N i The comprehensive weighted risk P ii Normalize and get the initial value D of iterative inference ii , and the iterative inference initial value D ii Substitute it into the fuzzy iterative reasoning model for cyclic reasoning until the error of two consecutive reasoning results is less than the preset error threshold, and obtain the target normalized final value I i , the calculation method is shown in the following formula;

[0018]

[0019] Where D ii (t) is the risk assessment data set B i The inference value at the tth iteration, t is a positive integer; P ij is the risk assessment index N i The risk assessment index N j Comparative comprehensive weighted risk.

[0020] Step S104: According to the key target weight Z i , the target normalized final value I i , the influence value function f of the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , determine the risk value R of the hydrogen-blended natural gas pipeline, as shown in the following formula.

[0021]

[0022] Where P 11 ,P 22 ,…,P nn are the elements on the main diagonal of the hierarchical comparison judgment matrix X; α and β are the risk weight influence coefficient and the risk weight prediction coefficient respectively, a is a random number between (0,1], β is a random number in [0,1), and α+β=1.

[0023] Preferably, in step S102, the risk assessment index N i The n risk assessment indicators in the risk assessment indicator system are compared in pairs, and the obtained n comparison results a i1 ,a i2 ,…,a ii , …a in Arrange in descending order to construct risk assessment data set B i ={b1,b2,…,b i , …b n}; where b1 is a i1 ,a i2 ,…,a ii , …a in The maximum value in b n for a i1 ,a i2 ,…,a ii , …a in The minimum value in ;

[0024] Based on the combined weighting method, according to the risk assessment data set B i ={b1,b2,…,b i , …b n}, calculate the risk assessment index N i The comprehensive weighted risk P of pairwise comparison ii and P ij , to establish a hierarchical comparison judgment matrix X;

[0025] Based on the hierarchical comparison judgment matrix X, determine the risk assessment index N i The key target weight Z i .

[0026] Preferably, in step S103, according to the formula:

[0027]

[0028] Determine the initial value D of the iterative reasoning ii Where, P ii is the risk assessment index N iThe combined weighted risk compared to itself.

[0029] Preferably, in step S104, according to the formula:

[0030]

[0031] Determine the influence value function f corresponding to the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i Where, P 11 ,P 22 ,…,P nn are the elements on the main diagonal of the grading comparison judgment matrix X; a is the risk weight influence coefficient, and a is a random number between (0,1].

[0032] Preferably, the method further includes: based on a preset risk assessment coefficient, risk grading the hydrogen-blended natural gas pipeline according to the risk value R of the hydrogen-blended natural gas pipeline.

[0033] The embodiment of the present application also provides a risk assessment and grading system for hydrogen-blended natural gas pipelines, including:

[0034] An evaluation system construction unit is configured to determine a risk evaluation index N of the hydrogen-blended natural gas pipeline according to the operational risk factors of the hydrogen-blended natural gas pipeline. i , to construct the risk assessment index system of the hydrogen-blended natural gas pipeline; wherein, i∈n, i and n are both positive integers, and n is the number of the risk assessment indicators;

[0035] A weight calculation unit is configured to calculate the risk based on the risk assessment index N i The comprehensive weighted risk P between the n risk assessment indicators in the risk assessment indicator system ii and P ij , establish the risk assessment index N i The hierarchical comparison judgment matrix X is used to determine the risk assessment index N i The key target weight Z i ; Among them, P ii is the risk assessment index N i The comprehensive weighted risk compared with itself, P ij is the risk assessment index N i The risk assessment index N j The comprehensive weighted risk of comparison; j∈n, j is a positive integer;

[0036] A loop reasoning unit configured to calculate the risk assessment index N i The comprehensive weighted risk P ii Normalize and get the initial value D of iterative inference ii; and the iterative reasoning initial value D ii Substitute it into the fuzzy iterative reasoning model for cyclic reasoning until the error of two consecutive reasoning results is less than the preset error threshold, and obtain the target normalized final value I i ;

[0037] The risk calculation unit is configured to calculate the risk of i , the target normalized final value I i , the influence value function f of the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , determine the risk value R of the hydrogen-blended natural gas pipeline.

[0038] Beneficial effects:

[0039] In the risk assessment and grading method for hydrogen-blended natural gas pipelines provided in the embodiment of the present application, first, the risk assessment index N of the hydrogen-blended natural gas pipeline is determined according to the operational risk factors of the hydrogen-blended natural gas pipeline. i , in order to construct the risk assessment index system of the hydrogen-blended natural gas pipeline; then, according to the risk assessment index N i The comprehensive weighted risk P between the risk assessment indicators in the risk assessment indicator system ii and P ij , establish the risk assessment index N i The hierarchical comparison judgment matrix X is used to determine the risk assessment index N i The key objective weights of the risk assessment index N i The comprehensive weighted risk P ii Normalize and get the initial value D of iterative inference ii , and iterate the inference initial value D ii Substitute it into the fuzzy iterative reasoning model for cyclic reasoning until the error of two consecutive reasoning results is less than the preset error threshold, and obtain the target normalized final value I i ; Finally, according to the key target weight Z i , target normalized final value I i , the influence value function f of the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , determine the risk value R of the hydrogen-blended natural gas pipeline.

[0040] In this way, the interactive coupling between various risk factors during the operation of hydrogen-blended natural gas pipelines is fully combined, the risk situation of hydrogen-blended natural gas pipelines is comprehensively monitored, and the quantitative evaluation of risks during the operation of hydrogen-blended natural gas pipelines is realized, making the risk assessment of hydrogen-blended natural gas pipelines more objective, no longer affected by human factors, and the risk assessment is more accurate, which helps to accurately grasp the safety status of hydrogen-blended natural gas pipelines during operation, thereby implementing effective preventive control measures, minimizing possible damage and economic losses, and ensuring the safety of public life and property. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. Among them:

[0042] Figure 1 A schematic diagram of a process for risk assessment and grading of a hydrogen-blended natural gas pipeline provided according to some embodiments of the present application;

[0043] Figure 2 A schematic diagram of a risk assessment index system for a hydrogen-blended natural gas pipeline provided according to some embodiments of the present application;

[0044] Figure 3 A schematic diagram of the structure of a risk assessment and grading system for a hydrogen-blended natural gas pipeline provided according to some embodiments of the present application. DETAILED DESCRIPTION

[0045] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as a part of an embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the embodiments of the present invention should belong to the scope of protection of the embodiments of the present invention.

[0046] When hydrogen-blended natural gas pipelines are in operation, the risk status is constantly changing due to the mutual coupling of various risk factors. Once the risk value is too high, it will lead to gas leakage, and the accumulated hydrogen-blended natural gas will mix with the surrounding air to form a large-scale flammable gas mixture. Once the gas mixture contacts the ignition source, it will explode and cause serious damage. Therefore, the prevention and control of the risks of hydrogen-blended natural gas pipelines is crucial. However, the current risk assessment and grading of hydrogen-blended natural gas pipelines basically relies on expert scoring, and the assessment and grading are carried out through qualitative or semi-quantitative methods, which is seriously insufficient in accurately predicting and quantifying risks.

[0047] Based on this, the embodiment of the present application provides a risk assessment and grading method for hydrogen-blended natural gas pipelines. In order to solve the problem that the risk assessment and grading process of hydrogen-blended natural gas pipelines is highly subjective and lacks qualitative or semi-quantitative evaluation of the interactive coupling between risk factors, the interactive coupling between various risk factors during the operation of the hydrogen-blended natural gas pipeline is combined, and the risk situation of the hydrogen-blended natural gas pipeline is comprehensively monitored to achieve quantitative evaluation of the risks during the operation of the hydrogen-blended natural gas pipeline, so that the risk assessment of the hydrogen-blended natural gas pipeline is more objective, no longer affected by human factors, and the risk assessment is more accurate.

[0048] like Figure 1 , Figure 2 As shown in the figure, the risk assessment classification method of hydrogen-blended natural gas pipeline includes:

[0049] Step S101: Determine the risk assessment index N of the hydrogen-blended natural gas pipeline according to the operational risk of the hydrogen-blended natural gas pipeline. i , in order to construct a risk assessment index system for hydrogen-blended natural gas pipelines.

[0050] Among them, i∈n, i and n are both positive integers, and n is the number of risk assessment indicators.

[0051] Through the data of hydrogen-blended natural gas pipeline operation, the operating risk factors of hydrogen-blended natural gas pipeline are analyzed, and the risk assessment indicators of hydrogen-blended natural gas pipeline are determined. Specifically, the risk assessment indicators of hydrogen-blended natural gas pipeline operation are divided from four aspects: pipeline body, environmental factors, personnel level, and safety management, including: pipe material, outer diameter, wall thickness, defects, and operating pressure of hydrogen-blended natural gas pipeline; hydrogen content in hydrogen-blended natural gas pipeline, soil acidity and alkalinity at the location of hydrogen-blended natural gas pipeline, atmospheric environment, technical level, safety awareness, working time, safety system, safety education, safety inspection and other n indicators (n is a positive integer) of hydrogen-blended natural gas pipeline operation unit, and these n risk assessment indicators are used as the indicator system for risk reasoning and evaluation of hydrogen-blended natural gas pipeline.

[0052] Step S102: Based on the risk assessment index N i The comprehensive weighted risk P between the n risk assessment indicators in the risk assessment indicator system ii and P ij , establish the risk assessment index N i The hierarchical comparison judgment matrix X is used to determine the risk assessment index N i The key target weight Z i .

[0053] Among them, P ii is the risk assessment index N i The comprehensive weighted risk compared with itself, P ij is the risk assessment index Ni and risk assessment index N j The comprehensive weighted risk for comparison; j∈n, j is a positive integer.

[0054] First, based on the risk assessment index system, a Bayesian network model containing n risk assessment indicators is constructed. The n risk assessment indicators are n nodes in the Bayesian network model. According to the historical risk data of the hydrogen-blended natural gas pipeline, the node risk probability of the n nodes (n risk assessment indicators) in the Bayesian network model when a risk accident occurs in the hydrogen-blended natural gas pipeline is determined by mathematical statistical methods. That is, the number of risk accidents caused by each risk assessment indicator in the hydrogen-blended natural gas pipeline is counted, and the ratio of the number of risk accidents caused by the hydrogen-blended natural gas pipeline in the historical risk data is calculated, which is the node risk probability of the corresponding risk assessment indicator. Among them, the node risk probability of the node represents the impact of the risk assessment indicator on the risk accident of the hydrogen-blended natural gas pipeline.

[0055] Based on the node risk probability, the risk assessment index N i Compare the n risk assessment indicators in the risk assessment indicator system two by two, including risk assessment indicator N i Comparison with itself and risk assessment index N i and risk assessment index N j By comparing the risk assessment indicators pairwise, the impact of different risk assessment indicators on hydrogen-blended natural gas pipelines is determined, and the risk level values ​​of different risk assessment indicators are determined according to the impact.

[0056] Specifically, the risk probability difference of the node risk probabilities of any two risk assessment indicators is calculated, and the risk assessment indicators are graded according to the risk probability difference. i and risk assessment index N j When the risk probability difference is in [0,0.2), determine the risk assessment index N i The risk level value is 0; when the risk assessment index N i and risk assessment index N j When the risk probability difference is in [0.2,0.4), determine the risk assessment index N i The risk level value is 2; when the risk assessment index N i and risk assessment index N j When the risk probability difference is in [0.4,0.6), determine the risk assessment index N i The risk level value is 4; when the risk assessment index N i and risk assessment index N j When the risk probability difference is in [0.6, 0.8), determine the risk assessment index N iThe risk level value is 6; when the risk assessment index N i and risk assessment index N j When the risk probability difference is between [0.8,1], determine the risk assessment index N i The risk level value is 8.

[0057] Then, the risk assessment index N i Compare n risk assessment indicators pairwise to obtain n comparison results (i.e. risk level values) a i1 ,a i2 ,…,a ii , …a in , where a ii is the risk assessment index N i The risk level value when compared with itself, a ij (i≠j) is the risk assessment index N i and risk assessment index N j The risk level value when comparing. i1 ,a i2 ,…,a ii , …a in Arrange in descending order to construct risk assessment data set B i ={b1,b2,…,b i , …b n}; b1 is a i1 ,a i2 ,…,a ii , …a in The maximum value in b n for a i1 ,a i2 ,…,a ii , …a in It should be noted that the comparison results of the same values ​​do not distinguish between the order of the two.

[0058] Next, based on the combined weighting method, according to the risk assessment data set B i ={b1,b2,…,b i , …b n}, calculate the risk assessment index N i The comprehensive weighted risk P of pairwise comparison ii and P ij Specifically, according to the formula:

[0059]

[0060] Determine the risk assessment index N i The comprehensive weighted risk P ii and P ij In the formula, b iis the risk assessment dataset B i The i-th element in b j is the risk assessment dataset B i Here, it should be noted that the risk assessment dataset B i The i-th element b in i and risk assessment index N i The risk level value when compared with itself does not correspond, that is, b i May be equal to a ii , or it may be equal to a i1 ,a i2 ,…,a ii , …a in Any other value in .

[0061] After determining the risk assessment index N i The comprehensive weighted risk P ii and P ij After that, the risk assessment index N i The multiple comprehensive weighted risks are expressed in a specific matrix form to construct a hierarchical comparison judgment matrix:

[0062]

[0063] Finally, according to the formula:

[0064]

[0065] Determine the risk assessment index N i The key target weight Z i , to characterize the risk assessment index N i importance.

[0066] Step S103: Risk assessment index N i The comprehensive weighted risk P ii Normalize and get the initial value D of iterative inference ii , and iterate the inference initial value D ii Substitute it into the fuzzy iterative reasoning model for cyclic reasoning until the error of two consecutive reasoning results is less than the preset error threshold, and obtain the target normalized final value I i .

[0067] Specifically, according to the formula:

[0068]

[0069] Determine the initial value D of iterative reasoning ii .

[0070] In this application, the fuzzy iterative reasoning model is:

[0071]

[0072] Where D i (t) is the risk assessment data set B i The inference value at the tth iteration, D ii (t+1) is the risk assessment data set B i The inference value at the t+1th iteration, where t is a positive integer.

[0073] The iterative inference initial value D ii As the initial value of the fuzzy iterative reasoning model, the calculation is repeated until the error between two consecutive reasoning results is less than 0.0001, and the last reasoning result is taken as the target normalized final value I i .Right now:

[0074]

[0075] That is to say, when the fuzzy iterative reasoning gradually tends to a stable value, the target normalized final value I is obtained. i .

[0076] Step S104: According to the key target weight Z i , target normalized final value I i , the influence value function f of the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , determine the risk value R of the hydrogen-blended natural gas pipeline.

[0077] Specifically, according to the formula:

[0078]

[0079] Determine the influence value function f corresponding to the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , f i The factor that affects the risk value R; where P 11 ,P 22 ,…,P nn are the elements on the main diagonal of the hierarchical comparison judgment matrix X; a is the risk weight influence coefficient, and a is a random number between (0,1].

[0080] Then, according to the formula:

[0081]

[0082] Determine the risk value R of the hydrogen-blended natural gas pipeline. Among them, Z i is the key target weight, I iis the target normalized terminal value, β is the risk weight prediction coefficient, β is a random number in [0,1), and α+β=1.

[0083] Finally, based on the preset risk assessment coefficient, the risk of hydrogen-blended natural gas pipelines is graded according to the risk value R of hydrogen-blended natural gas pipelines. Specifically, when R = [0.8, 1], the hydrogen-blended natural gas pipeline is defined as a first-level risk; when R = [0.6, 0.8), the hydrogen-blended natural gas pipeline is defined as a second-level risk; when R = [0.4, 0.6), the hydrogen-blended natural gas pipeline is defined as a third-level risk; when R = [0.2, 0.4), the hydrogen-blended natural gas pipeline is defined as a fourth-level risk; when R = [0, 0.2), the hydrogen-blended natural gas pipeline is defined as a fifth-level risk. Among them, when the hydrogen-blended natural gas pipeline is a first-level risk, the hydrogen-blended natural gas pipeline has the greatest safety risk hidden danger.

[0084] Therefore, in the risk assessment and grading of hydrogen-blended natural gas pipelines, the interactive coupling between various risk factors during the operation of hydrogen-blended natural gas pipelines is fully combined, the risk situation of hydrogen-blended natural gas pipelines is comprehensively monitored, and the quantitative evaluation of risks during the operation of hydrogen-blended natural gas pipelines is realized, making the risk assessment of hydrogen-blended natural gas pipelines more objective, no longer affected by human factors, and the risk assessment is more accurate, which helps to accurately grasp the safety status of hydrogen-blended natural gas pipelines during operation, thereby implementing effective preventive control measures, minimizing possible damage and economic losses, and ensuring the safety of public life and property.

[0085] The present application also provides a risk assessment and grading system for hydrogen-blended natural gas pipelines. Figure 3 As shown, including:

[0086] The evaluation system construction unit 301 is configured to determine the risk evaluation index N of the hydrogen-blended natural gas pipeline according to the operational risk factors of the hydrogen-blended natural gas pipeline. i , in order to construct a risk assessment index system for hydrogen-blended natural gas pipelines; where i∈n, i and n are both positive integers, and n is the number of risk assessment indicators;

[0087] The weight calculation unit 302 is configured to calculate the risk assessment index N i The comprehensive weighted risk P between the n risk assessment indicators in the risk assessment indicator system ii and P ij , establish the risk assessment index N i The hierarchical comparison judgment matrix X is used to determine the risk assessment index N i The key target weight Z i ; Among them, P ii is the risk assessment index N i The comprehensive weighted risk compared with itself, P ij is the risk assessment index Ni and risk assessment index N j The comprehensive weighted risk of comparison; j∈n, j is a positive integer;

[0088] The loop reasoning unit 303 is configured to calculate the risk assessment index N i The comprehensive weighted risk P ii Normalize and get the initial value D of iterative inference ii ; and iteratively infer the initial value D ii Substitute it into the fuzzy iterative reasoning model for cyclic reasoning until the error of two consecutive reasoning results is less than the preset error threshold, and obtain the target normalized final value I i ;

[0089] The risk calculation unit is configured to calculate the risk based on the key target weight Z i , target normalized final value I i , the influence value function f of the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , determine the risk value R of the hydrogen-blended natural gas pipeline.

[0090] The hydrogen-blended natural gas pipeline risk assessment and analysis system provided in the embodiment of the present application can implement the steps and processes of the hydrogen-blended natural gas pipeline risk assessment and analysis method of any of the above embodiments, and achieve the same technical effects, which will not be described one by one here.

[0091] In the description of the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0092] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A risk assessment and grading method for hydrogen-blended natural gas pipelines, characterized in that: include: Step S101: Determine the risk assessment index N of the hydrogen-blended natural gas pipeline according to the operational risk factors of the hydrogen-blended natural gas pipeline. i , in order to construct the risk assessment index system of the hydrogen-blended natural gas pipeline; wherein, i∈n, i and n are both positive integers, n is the number of the risk assessment indicators, the operation risk factors include the pipeline itself, environmental factors, personnel level, and safety management, and the risk assessment indicators include the pipe material, outer diameter, wall thickness, defects, operating pressure, hydrogen content in the hydrogen-blended natural gas pipeline, soil acidity and alkalinity at the location of the hydrogen-blended natural gas pipeline, atmospheric environment, technical level, safety awareness, working time, safety system, safety education, and safety inspection of the hydrogen-blended natural gas pipeline operation unit; Step S102: According to the risk assessment index N i The comprehensive weighted risk P between the n risk assessment indicators in the risk assessment indicator system ii and P ij , the calculation method is as follows: Where b i is the risk assessment dataset B i The i-th element in b j is the risk assessment dataset B i The jth element in P ii is the risk assessment index N i The comprehensive weighted risk compared with itself, P ij is the risk assessment index N i The risk assessment index N j The comprehensive weighted risk of comparison; j∈n, j is a positive integer; Based on the comprehensive weighted risk P ii and P ij , establish the risk assessment index N i The hierarchical comparison judgment matrix X is as follows: Based on the hierarchical comparison judgment matrix X, determine the risk assessment index N i The key target weight Z i , as shown below: Step S103: the risk assessment index N i The comprehensive weighted risk P ii Normalize and get the initial value D of iterative inference ii , and the iterative inference initial value D ii Substitute it into the fuzzy iterative reasoning model for cyclic reasoning until the error of two consecutive reasoning results is less than the preset error threshold, and obtain the target normalized final value I i , as shown below: Where D ii (t) is the risk assessment data set B i The inference value at the tth iteration, t is a positive integer; P ij is the risk assessment index N i The risk assessment index N j comparative composite weighted risk; Step S104: According to the key target weight Z i , the target normalized final value I i , the influence value function f of the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , determine the risk value R of the hydrogen-blended natural gas pipeline, as shown in the following formula: Where P 11 ,P 22 ,…,P nn are the elements on the main diagonal of the hierarchical comparison judgment matrix X; α and β are the risk weight influence coefficient and the risk weight prediction coefficient respectively, a is a random number between (0,1], β is a random number in [0,1), and α+β=1.

2. The risk assessment and grading method for hydrogen-blended natural gas pipeline according to claim 1 is characterized in that: In step S102, For the risk assessment index N i The n risk assessment indicators in the risk assessment indicator system are compared in pairs, and the obtained n comparison results a i1 ,a i2 ,…,a ii , …a in Arrange in descending order to construct risk assessment data set B i ={b1,b2,…,b i , …b n }; where b1 is a i1 ,a i2 ,…,a ii , …a in The maximum value in b n for a i1 ,a i2 ,…,a ii , …a in The minimum value in ; Based on the combined weighting method, according to the risk assessment data set B i ={b1,b2,...,b i , …b n }, calculate the risk assessment index N i The comprehensive weighted risk P of pairwise comparison ii and P ij , to establish a hierarchical comparison judgment matrix X; Based on the hierarchical comparison judgment matrix X, determine the risk assessment index N i The key target weight Z i .

3. The risk assessment and grading method for hydrogen-blended natural gas pipeline according to claim 1 is characterized in that: In step S103, according to the formula: Determine the initial value D of the iterative reasoning ii ; Where P ii is the risk assessment index N i The combined weighted risk compared to itself.

4. The risk assessment and grading method for hydrogen-blended natural gas pipeline according to claim 1 is characterized in that: In step S104, according to the formula: Determine the influence value function f corresponding to the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i ; Where P 11 ,P 22 ,…,P nn are the elements on the main diagonal of the grading comparison judgment matrix X; a is the risk weight influence coefficient, and a is a random number between (0,1].

5. The risk assessment and grading method for hydrogen-blended natural gas pipeline according to claim 1 is characterized in that: Also includes: Based on a preset risk assessment coefficient, the risk of the hydrogen-blended natural gas pipeline is graded according to the risk value R of the hydrogen-blended natural gas pipeline.

6. A risk assessment and grading system for hydrogen-blended natural gas pipelines, characterized in that: include: An evaluation system construction unit is configured to determine a risk evaluation index N of the hydrogen-blended natural gas pipeline according to the operational risk factors of the hydrogen-blended natural gas pipeline. i , in order to construct the risk assessment index system of the hydrogen-blended natural gas pipeline; wherein, i∈n, i and n are both positive integers, n is the number of the risk assessment indicators, the operation risk factors include the pipeline itself, environmental factors, personnel level, and safety management, and the risk assessment indicators include the pipe material, outer diameter, wall thickness, defects, operating pressure, hydrogen content in the hydrogen-blended natural gas pipeline, soil acidity and alkalinity at the location of the hydrogen-blended natural gas pipeline, atmospheric environment, technical level, safety awareness, working time, safety system, safety education, and safety inspection of the hydrogen-blended natural gas pipeline operation unit; A weight calculation unit is configured to calculate the risk based on the risk assessment index N i The comprehensive weighted risk P between the n risk assessment indicators in the risk assessment indicator system ii and P ij , the calculation method is as follows: Among them, b i is the risk assessment dataset B i The i-th element in b j is the risk assessment dataset B i The jth element in P ii is the risk assessment index N i The comprehensive weighted risk compared with itself, P ij is the risk assessment index N i The risk assessment index N j The comprehensive weighted risk of comparison; j∈n, j is a positive integer; Based on the comprehensive weighted risk P ii and P ij , establish the risk assessment index N i The hierarchical comparison judgment matrix X is as follows: Based on the hierarchical comparison judgment matrix X, determine the risk assessment index N i The key target weight Z i , as shown below: A loop reasoning unit configured to calculate the risk assessment index N i The comprehensive weighted risk P ii Normalize and get the initial value D of iterative inference ii ; and the iterative reasoning initial value D ii Substitute it into the fuzzy iterative reasoning model for cyclic reasoning until the error of two consecutive reasoning results is less than the preset error threshold, and obtain the target normalized final value I i , as shown below: Where D ii (t) is the risk assessment data set B i The inference value at the tth iteration, t is a positive integer; P ij is the risk assessment index N i The risk assessment index N j comparative composite weighted risk; The risk calculation unit is configured to calculate the risk of i , the target normalized final value I i , the influence value function f of the i-th element on the main diagonal of the hierarchical comparison judgment matrix X i , determine the risk value R of the hydrogen-blended natural gas pipeline, as shown in the following formula: Where P 11 ,P 22 ,…,P nn are the elements on the main diagonal of the hierarchical comparison judgment matrix X; α and β are the risk weight influence coefficient and the risk weight prediction coefficient respectively, a is a random number between (0,1], β is a random number in [0,1), and α+β=1.

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