A method for assessing the resilience of a gas network considering random leakage and recovery mechanisms

Abstract

The present application belongs to the technical field of pipe network safety analysis, and discloses a gas pipe network resilience evaluation method considering random leakage and recovery mechanism, comprising the following steps: obtaining a static parameter set of the gas pipe network, and constructing a benchmark topological-hydraulic model; running the benchmark topological-hydraulic model to obtain normal working condition data of the gas pipe network; introducing a random leakage mechanism into the benchmark topological-hydraulic model, and randomly generating leakage data to simulate random leakage events; updating the benchmark topological-hydraulic model based on the leakage data to form a leakage working condition model, and running the leakage working condition model to obtain leakage working condition data; performing recovery operations based on the leakage working condition model, updating the leakage working condition model to simulate the recovery process, and running the dynamically updated model to obtain recovery process data; effectively solving the problems of insufficient leakage case data and limited dynamic simulation capability in the prior art, which leads to insufficient accuracy of gas pipe network resilience evaluation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pipe network safety analysis, and particularly relates to a gas pipe network resilience evaluation method considering random leakage and recovery mechanism. BACKGROUND

[0002] As an important municipal infrastructure, the safe and stable operation of urban gas pipe network is directly related to the urban energy supply guarantee and social public safety; with the acceleration of urbanization process in China, the scale of gas pipe network continues to expand, and the pipe network system is increasingly complex; in the long-term operation process, the pipe network is affected by factors such as material aging, corrosion, third-party construction damage and extreme weather, and the leakage risk is significantly increased; although actual leakage accidents occur from time to time, due to the fact that the accident data collection is not systematic and the record is incomplete, high-quality case data available for modeling analysis is still scarce. The existing evaluation method adopts simplified assumptions and static analysis, and it is difficult to accurately simulate the dynamic process of leakage diffusion and the time sequence characteristics of system recovery; the conventional simulation tool has obvious shortcomings in simulating the dynamic changes of pipe network topology, the leakage repair process and the like, resulting in limitations in the cognition of the resilience characteristics of the pipe network; this condition restricts the accuracy of the pipe network safety evaluation, and it is difficult to provide effective support for the optimal design and emergency repair decision of the pipe network; therefore, in the prior art, there are problems of insufficient leakage case data and limited dynamic simulation capability, resulting in insufficient accuracy of the gas pipe network resilience evaluation. SUMMARY

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a gas pipe network resilience evaluation method considering random leakage and recovery mechanism, which solves the problem of insufficient leakage case data and limited dynamic simulation capability in the prior art, resulting in insufficient accuracy of the gas pipe network resilience evaluation.

[0004] The purpose of the present application can be achieved by the following technical solutions:

[0005] A gas pipe network resilience evaluation method considering random leakage and recovery mechanism, comprising the following steps:

[0006] Obtain a set of static parameters of the gas pipe network, and construct a benchmark topological-hydraulic model;

[0007] Run the benchmark topological-hydraulic model to obtain normal operating condition data of the gas pipe network;

[0008] Introduce a random leakage mechanism into the benchmark topological-hydraulic model, and randomly generate leakage data to simulate random leakage events;

[0009] Update the benchmark topological-hydraulic model based on the leakage data to form a leakage operating condition model, and run the leakage operating condition model to obtain leakage operating condition data;

[0010] Performing a recovery operation based on the leakage condition model, updating the leakage condition model to simulate the recovery process, and running the dynamically updated model to obtain recovery process data;

[0011] Calculating the gas pipeline network resilience based on the normal condition data, the leakage condition data, and the recovery process data.

[0012] The static parameter set includes structural parameters, operation and maintenance state parameters, emergency resource parameters, and operation boundary conditions;

[0013] The structural parameters include the outlet type, pipe length, pipe diameter, pipe wall thickness, and material of all pipe segments;

[0014] The operation and maintenance state parameters include the service age of the pipe segment and the daily maintenance record;

[0015] The emergency resource parameters include the location of the repair station;

[0016] The operation boundary conditions include the gas source pressure, flow size, and demand flow of the gas end.

[0017] Constructing a reference topology-hydraulic model, specifically including the following steps:

[0018] Presetting the pipe diameter difference threshold between adjacent pipe segments and the service age difference threshold between adjacent pipe segments;

[0019] Initializing the connection points between pipe segments as candidate nodes;

[0020] For each candidate node, if the pipe diameter difference between the adjacent two pipe segments is greater than the pipe diameter difference threshold, or the service age difference is greater than the service age difference threshold, the candidate node is determined as a network node;

[0021] If the outlet of the pipe segment is the inlet of the gas end or connects a pressure regulating station, the candidate node corresponding to the outlet of the pipe segment is determined as a network node;

[0022] The adjacent two pipe segments corresponding to the candidate nodes that are not determined as network nodes are simplified and combined into one continuous pipe segment;

[0023] Based on the connection relationship between the finally determined network nodes and pipe segments, a simplified topology structure of the gas pipeline network is established;

[0024] Based on the simplified topology structure, the structural parameters, and the operation boundary conditions, the model units are configured and the initial parameters are set to complete the reference topology-hydraulic model.

[0025] Running the reference topology-hydraulic model to obtain the normal condition data of the gas pipeline network, specifically including the following steps:

[0026] According to the reference topology-hydraulic model, an association matrix A of pipe segments-nodes is constructed, and the elements in the association matrix A are A ​a ij Determined according to the following rules:

[0027]

[0028] Among them, elements a ij For the correlation matrix A The Middle i Line number j The elements of the column are used to represent network nodes. i With pipe section j Relationship;

[0029] The network node stress equation is established based on the correlation matrix A, as follows:

[0030]

[0031] in, q A vector representing the quality traffic of network nodes. A T yes A transpose, P surface Fig. The vector of network node stress; C represents the admittance matrix;

[0032] The formula for calculating the admittance matrix C is as follows:

[0033]

[0034] in, Q This refers to the mass flow rate of the pipe section. d This refers to the inner diameter of the pipe. λ This is the hydraulic resistance coefficient;

[0035] Mass flow rate of pipe section Q The calculation formula is as follows:

[0036]

[0037] in, P 1 、P 2 These are the pressures at the beginning and end of the pipe section, respectively. R G It is the gas constant; T Indicates the absolute temperature of a gas; L This indicates the length of the pipe section; z is the compressibility coefficient.

[0038] The mass flow rate of each pipe section and the pressure data of the corresponding network nodes are calculated sequentially to serve as the normal operating data of the gas pipeline network.

[0039] In the benchmark topology-hydraulic model, a random leakage mechanism is introduced, and random leakage data is generated, including the following steps:

[0040] Based on the service age of the pipe segment and the daily maintenance records, a corresponding leakage failure rate is set for each pipe segment;

[0041] In each time step of the simulation calculation, a random number uniformly distributed in the interval [0, 1] is generated for each pipe segment;

[0042] The random number corresponding to the pipe segment is compared with the leakage failure value. When the random number is less than the threshold value, it is determined that the pipe segment has a leakage;

[0043] When it is determined that the pipe segment has a leakage, random leakage data is generated, including:

[0044] Leakage location L 0 , wherein, L 0 ∈(0, L );

[0045] Leakage aperture D 0 , wherein, D 0 ∈(0, d ).

[0046] Based on the leakage data, the benchmark topology-hydraulic model is updated to form a leakage working condition model, and the leakage working condition model is run to obtain leakage working condition data, including the following steps:

[0047] Based on the leakage location, a virtual leakage node is set as a network node, and the pipe segment determined to have a leakage is divided into a front segment and a rear segment, the length of the front segment is L 0 , and the length of the rear segment is ;

[0048] According to the generated leakage location and leakage aperture, a virtual leakage pipe segment is added to the pipe segment determined to have a leakage;

[0049] The length of the virtual leakage pipe segment is equal to the wall thickness of the pipe segment determined to have a leakage;

[0050] The diameter of the virtual leakage pipe segment is equal to the generated leakage aperture D 0 ;

[0051] The terminal pressure of the virtual leakage pipe segment is set to standard atmospheric pressure;

[0052] Based on the newly added virtual leakage node and virtual leakage pipe segment, the topology structure of the benchmark topology-hydraulic model is updated to form leakage working condition data, including:

[0053] Update pipe segment-node association matrix A Add rows and columns corresponding to the virtual leak nodes;

[0054] Reconfigure the length parameters of the segmented pipe section;

[0055] Set the operational boundary conditions for the virtual leaking pipe segment;

[0056] Run the updated leakage condition model to calculate the pressure of each network node, the mass flow rate of the pipeline segment and the actual flow rate at the gas consumption end under the leakage condition, and obtain the leakage condition data.

[0057] Among them, the actual flow rate at the gas consumption end q act The calculation formula is as follows:

[0058]

[0059] In the formula, Q rep It is the gas demand flow rate at the user end; P sev It is the service pressure of the gas pipeline network; P min It is the lowest pressure in the gas pipeline network.

[0060] The recovery operation is performed based on the leakage condition model. The leakage condition model is updated to simulate the recovery process, and the dynamically updated model is run to obtain recovery process data. The specific steps include:

[0061] The two ends of the pipe segment identified as leaking are sealed, the pipe segment identified as leaking and the virtual leaking pipe segment are isolated, and the topology and operating status of the leak condition model are updated accordingly.

[0062] Based on the location of the emergency repair station, the time for allocating emergency repair resources is calculated using the following formula:

[0063]

[0064] in, t i This indicates the time allocating resources for emergency repairs of the gas pipeline network; L i The location of the emergency repair station is... i The shortest path distance to each leak point; V Indicates the average resource allocation rate;

[0065] A preset diameter ratio threshold is set, and the diameter ratio of the leaking orifice diameter to the diameter of the pipe section identified as leaking is calculated. Based on the relationship between the diameter ratio and the diameter ratio threshold, different preset maintenance times are selected for simulation.

[0066] After the simulation of the repair is completed, the plugging of both ends of the leaking pipe section is removed, the virtual leaking pipe section is deleted, and the model topology and operating state are updated again;

[0067] During the entire recovery process, the dynamically updated model is run according to the simulation step length, the mass flow of each network node and each pipe section is calculated and recorded as a sequence data changing with time, and the recorded sequence data is taken as the recovery process data.

[0068] The preset diameter ratio threshold is 0.2;

[0069] When the diameter ratio is less than 0.2, the preset repair time is a normal distribution with a mean of 6 hours and a variance of 3 hours;

[0070] When the diameter ratio is greater than or equal to 0.2, the preset repair time is a normal distribution with a mean of 12 hours and a variance of 6 hours.

[0071] Based on the normal working condition data, the leakage working condition data and the recovery process data, the gas pipe network resilience is calculated, specifically including the following steps:

[0072] The gas supply performance of the gas pipe network in the simulation duration is calculated, and the specific calculation formula is as follows:

[0073]

[0074] Wherein, P(t) is the gas supply performance of the gas pipe network; i is the total number of gas demand points in the gas pipe network; is the actual gas supply flow of the gas demand node in the gas pipe network j ; is the demand flow of the gas demand node in the gas pipe network j ; t is the simulation duration;

[0075] Based on the gas pipe network supply resilience evaluation function, the gas pipe network supply resilience R is calculated, and the specific calculation formula is as follows:

[0076]

[0077] Wherein, P(t) is the actual performance curve, corresponding to a random process; TP(t) is the target performance curve; S 1 and S 2 are the areas surrounded by the actual performance curve and the target performance curve, respectively; t 0 is the random leakage occurrence time; t 1To restore the end time of the process.

[0078] Advantages of the present application:

[0079] The present application overcomes the limitations of the prior art by constructing a gas pipeline network resilience evaluation method considering random leakage and dynamic recovery mechanism. By introducing a random leakage generation mechanism based on service age and maintenance records, and integrating repair resource scheduling and repair timing simulation, the whole process dynamic simulation of the pipeline network system from leakage occurrence to complete recovery is realized. This method significantly improves the accuracy and reliability of resilience evaluation, and provides scientific basis and practical support for the safety design, operation optimization and emergency decision of gas pipeline network. BRIEF DESCRIPTION OF DRAWINGS

[0080] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0081] Fig. 1 is a schematic diagram of the whole process of the gas pipeline network resilience evaluation method of the present application;

[0082] Fig. 2 is a schematic diagram of the connection relationship of each unit in the model unit of the present application;

[0083] Fig. 3 is a schematic diagram of the pipeline network topology in the embodiment of the present application;

[0084] Fig. 4 is a schematic diagram of the process of pipeline network leakage repair in the embodiment of the present application;

[0085] Fig. 5 is the resilience change situation when the pipeline network segment in the embodiment of the present application occurs random leakage. DETAILED DESCRIPTION

[0086] 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 part of the embodiments of the present application, not all the 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.

[0087] As shown in Figs. 1 to 5 , a gas pipeline network resilience evaluation method considering random leakage and recovery mechanism includes the following steps:

[0088] Obtaining a static parameter set of the gas pipe network, and constructing a benchmark topological-hydraulic model;

[0089] Running the benchmark topological-hydraulic model to obtain normal working condition data of the gas pipe network;

[0090] Introducing a random leakage mechanism into the benchmark topological-hydraulic model to randomly generate leakage data to simulate random leakage events;

[0091] Updating the benchmark topological-hydraulic model based on the leakage data to form a leakage working condition model, and running the leakage working condition model to obtain leakage working condition data;

[0092] Performing a recovery operation based on the leakage working condition model, updating the leakage working condition model to simulate a recovery process, and running the dynamically updated model to obtain recovery process data;

[0093] Calculating the resilience of the gas pipe network based on the normal working condition data, the leakage working condition data, and the recovery process data.

[0094] The static parameter set includes structural parameters, operation and maintenance state parameters, emergency resource parameters, and operating boundary conditions;

[0095] The structural parameters include the outlet type, pipe length, pipe diameter, pipe wall thickness, and material of all pipe sections;

[0096] The operation and maintenance state parameters include the service age and routine maintenance records of the pipe sections;

[0097] The emergency resource parameters include the locations of repair stations;

[0098] The operating boundary conditions include the gas source pressure, flow size, and required flow at the gas consumption end.

[0099] Constructing the benchmark topological-hydraulic model, specifically including the following steps:

[0100] Predefining a pipe diameter difference threshold between adjacent pipe sections, and a service age difference threshold between adjacent pipe sections;

[0101] Initializing the connection points between pipe sections as candidate nodes;

[0102] For each candidate node, if the pipe diameter difference between the adjacent two pipe sections is greater than the pipe diameter difference threshold, or the service age difference is greater than the service age difference threshold, the candidate node is determined as a network node;

[0103] If the outlet of a pipe section is the inlet of a gas consumption end or is connected to a pressure regulating station, the candidate node corresponding to the outlet of the pipe section is determined as a network node;

[0104] The adjacent two pipe sections corresponding to the candidate nodes that are not determined as network nodes are simplified and combined into one continuous pipe section;

[0105] Based on the final determined connection relationship of network nodes and pipe sections, a simplified topology structure of the gas pipe network is established;

[0106] Based on the simplified topology structure, the structure parameters and the operation boundary conditions, model units are configured and initial parameters are set to build a completed reference topology-hydraulic model;

[0107] Preferably, the model units include a pressure unit for simulating a gas source node, a transmission unit for simulating hydraulic characteristics of a pipe section, and a load unit for simulating user gas demand;

[0108] Preferably, the model units further include a flow dynamic detection unit, a pressure dynamic detection unit and a leakage judgment unit; wherein the flow dynamic detection unit is used to simulate a flow meter; the pressure dynamic detection unit is used to simulate a pressure gauge; and the leakage judgment unit is used to generate random leakage; the connection relationship of the units in the model units is as shown in Fig. 2 ;

[0109] Preferably, the pressure unit is a pressure tank unit, which is realized by a pressure tank element in the simulation software, and the initial parameters thereof are set according to the gas source pressure value in the operation boundary conditions;

[0110] Preferably, the transmission unit is a fluid dynamic transmission unit, which is realized by a pipe element or a fluid dynamic transmission element, and the initial parameters thereof are set according to the structure parameters in the static parameter set, including pipe length, pipe diameter and hydraulic resistance coefficient determined according to pipe material and wall thickness;

[0111] Preferably, the load unit is a flow control unit, which is realized by a flow control valve element or a constant flow outlet element, and the initial parameters thereof are set according to the demand flow of the gas end in the operation boundary conditions.

[0112] The reference topology-hydraulic model is run to obtain normal working condition data of the gas pipe network, including the following steps:

[0113] According to the reference topology-hydraulic model, an association matrix of pipe sections and nodes is constructed A , wherein an element A in the association matrix a ij is determined according to the following rules:

[0114]

[0115] wherein the element a ij is an element in the A th row and the i th column of the association matrix j , and is used to represent the relationship between a network node i and a pipe section j ;

[0116] The network node pressure solving equation is established based on the correlation matrix A, and the specific process is as follows:

[0117]

[0118] Wherein, q represents the vector of network node mass flow, A T is the transpose of A P represents the vector of network node pressure; C represents the admittance matrix; Fig. The calculation formula of the admittance matrix C is as follows:

[0119]

[0120]

[0121] Wherein, Q is the mass flow of the pipe section; d is the inner diameter of the pipeline; λ is the hydraulic resistance coefficient;

[0122] The calculation formula of the mass flow of the pipe section Q is as follows:

[0123]

[0124] Wherein, P 1 、P 2 are the pressures at the starting point and the ending point of the pipe section respectively; R G is the gas constant; T represents the absolute temperature of the gas; L represents the length of the pipe section; z is the compression coefficient;

[0125] The mass flow of each pipe section and the corresponding network node pressure data are calculated in sequence, which are the normal working condition data of the gas pipeline network.

[0126] A random leakage mechanism is introduced into the reference topology-hydraulic model, and random leakage data is generated, including the following steps:

[0127] Based on the service age of the pipe section and the daily maintenance record, a corresponding leakage failure rate is set for each pipe section;

[0128] In each time step of the simulation calculation, a random number uniformly distributed in the interval [0, 1] is generated for each pipe section;

[0129] The random number corresponding to the pipe section is compared with the leakage failure value, and when the random number is less than the threshold value, it is determined that the pipe section has a leakage; ​​

[0130] When it is determined that a pipe section leaks, randomly generate leakage data, including:

[0131] Leakage position L 0 , wherein, L 0 ∈(0, L );

[0132] Leakage aperture D 0 , wherein, D 0 ∈(0, d ).

[0133] Update the reference topological-hydraulic model based on the leakage data to form a leakage working condition model, and run the leakage working condition model to obtain leakage working condition data, specifically including the following steps:

[0134] Set a virtual leakage node as a network node based on the leakage position, and divide the pipe section determined to leak into a front section and a rear section, the length of the front section being L 0 , and the length of the rear section being ;

[0135] Add a virtual leakage pipe section on the pipe section determined to leak according to the generated leakage position and leakage aperture;

[0136] The pipe length of the virtual leakage pipe section is equal to the pipe wall thickness of the pipe section determined to leak;

[0137] The pipe diameter of the virtual leakage pipe section is equal to the generated leakage aperture D 0 ;

[0138] The terminal pressure of the virtual leakage pipe section is set to standard atmospheric pressure;

[0139] Update the topological structure of the reference topological-hydraulic model based on the added virtual leakage node and virtual leakage pipe section to form leakage working condition data, including:

[0140] Update the pipe section-node association matrix A , and add rows and columns corresponding to the virtual leakage node;

[0141] Reconfigure the length parameters of the divided pipe sections;

[0142] Set the operating boundary conditions of the virtual leakage pipe section;

[0143] Run the updated leakage working condition model to calculate the pressure, mass flow data of each network node and the actual flow of the gas consumption end under the leakage working condition, and obtain the leakage working condition data;

[0144] Among them, the actual flow rate at the gas consumption end q act The calculation formula is as follows:

[0145]

[0146] In the formula, Q rep It is the gas demand flow rate at the user end; P sev It is the service pressure of the gas pipeline network; P min It is the lowest pressure in the gas pipeline network.

[0147] The recovery operation is performed based on the leakage condition model. The leakage condition model is updated to simulate the recovery process, and the dynamically updated model is run to obtain recovery process data. The specific steps include:

[0148] The two ends of the pipe segment identified as leaking are sealed, the pipe segment identified as leaking and the virtual leaking pipe segment are isolated, and the topology and operating status of the leak condition model are updated accordingly.

[0149] Based on the location of the emergency repair station, the time for allocating emergency repair resources is calculated using the following formula:

[0150]

[0151] in, t i This indicates the time allocating resources for emergency repairs of the gas pipeline network; L i The location of the emergency repair station is... i The shortest path distance to each leak point; V Indicates the average resource allocation rate;

[0152] A preset diameter ratio threshold is set, and the diameter ratio of the leaking orifice diameter to the diameter of the pipe section identified as leaking is calculated. Based on the relationship between the diameter ratio and the diameter ratio threshold, different preset maintenance times are selected for simulation.

[0153] After the simulated maintenance is completed, the seals at both ends of the leaking pipe section are removed, the virtual leaking pipe section is deleted, and the model topology and operating status are updated again.

[0154] Throughout the recovery process, the dynamically updated model is run according to the simulation step size, and the sequence data of the mass flow rate of each network node and each pipe segment changing over time are calculated and recorded. The recorded sequence data is used as the recovery process data.

[0155] The preset diameter ratio threshold is 0.2;

[0156] When the diameter ratio is less than 0.2, the preset maintenance time follows a normal distribution with a mean of 6 hours and a variance of 3 hours.

[0157] When the diameter ratio is greater than or equal to 0.2, the preset repair time is subject to a normal distribution with a mean of 12 hours and a variance of 6 hours;

[0158] The setting of the diameter ratio threshold in the present application is mainly based on the conventional classification standard of gas pipe network leakage in existing academic research, that is, the ratio of leakage hole diameter to pipe diameter is less than 0.2, which belongs to small hole leakage, and greater than or equal to 0.2 and less than 0.6, which belongs to pipe segment leakage; Since the probability of complete rupture of the pipe segment (i.e. the diameter ratio is greater than or equal to 0.6) in practice is extremely low, the present method takes 0.2 as the boundary between small hole leakage and general pipe segment leakage, and then matches different repair time parameters for different leakage types; and the normal distribution is used to simulate the repair time, which is more reasonable to simulate the repair time when there is no local actual repair efficiency data.

[0159] The gas pipe network resilience is calculated based on normal operating data, leakage operating data and recovery process data, specifically including the following steps:

[0160] The gas pipe network supply performance in the simulation duration is calculated, and the specific calculation formula is as follows:

[0161]

[0162] Wherein, P(t) is the gas pipe network supply performance; i is the total number of gas demand points in the gas pipe network; is the actual supply flow of the gas demand node j in the gas pipe network; is the demand flow of the gas demand node j in the gas pipe network; t is the simulation duration;

[0163] Based on the gas pipe network supply resilience evaluation function, the gas pipe network supply resilience R is calculated, and the specific calculation formula is as follows:

[0164]

[0165] Wherein, P(t) is the actual performance curve, corresponding to a random process; TP(t) is the target performance curve; S 1 and S 2 are the areas enclosed by the actual performance curve and the target performance curve, respectively; t 0 is the random leakage occurrence time; t 1 is the recovery process end time.

[0166] The gas pipe network system used in this embodiment includes 6 physical nodes and 7 pipe segments, and has a ring-branch mixed characteristic in the topological structure, and the specific topological connection relationship is as shown in Fig. 3

[0167] The gas pipe network structure information in this embodiment is shown in Table 1, and the gas consumption of the gas pipe network is shown in Table 2, wherein the network node 1 is a constant pressure gas source, and the pressure is 3000 Pa;

[0168] Table 1: Gas pipe network structure information table

[0169]

[0170] Table 2: Gas consumption table of gas pipe network

[0171]

[0172] As shown in Fig. 4 , this embodiment shows the process of repairing the gas pipe network leakage, which specifically includes four stages:

[0173] In stage 1, the pipe network maintains the original connection state, the pipe segment 2-3 is normally connected, and the system is in a steady state operation condition; the topological structure of this stage provides a reference for the subsequent repair process;

[0174] Stage 2 constructs a leakage path model by introducing virtual leakage nodes 7 and 8, wherein node 7 is the leakage starting point and node 8 is the leakage termination point; this modeling method accurately simulates the actual leakage condition;

[0175] Stage 3 implements isolation measures to disconnect the original connection of pipe segment 2-3, and realizes the isolation of the leakage pipe segment;

[0176] Stage 4 restores the original connection of pipe segment 2-3 after completing the pipe segment repair, and removes the temporary virtual leakage nodes 7 and 8; this stage verifies the repair effect through pressure monitoring to ensure that the system returns to normal operation;

[0177] The topological evolution of the entire repair process clearly shows the dynamic process from leakage occurrence to complete repair, and the connection relationship change of each stage provides an important basis for evaluating the resilience of the pipe network;

[0178] As shown in Fig. 5 , when the pipe segment 1 of the pipe network has a random leakage, the resilience changes, and the figure shows that the system resilience does not change significantly in the initial stage of pipe segment 1 leakage; after implementing the pipe segment isolation measures, the system resilience presents a rapid decline characteristic due to the interruption of gas supply to part of the demand nodes; after the leakage is repaired and the original connection is restored, the system resilience immediately rises to the level before the leakage.

[0179] ​In the description of the specification, the description of the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate way in one or more embodiments or examples.

[0180] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A method for assessing the resilience of gas pipeline networks considering random leakage and recovery mechanisms, characterized in that, Includes the following steps: Obtain the static parameter set of the gas pipeline network and construct a baseline topology-hydraulic model; Run the baseline topology-hydraulic model to obtain normal operating data of the gas pipeline network; A random leakage mechanism is introduced into the baseline topology-hydraulic model to randomly generate leakage data to simulate random leakage events; The baseline topology-hydraulic model is updated based on the leakage data to form a leakage condition model, and the leakage condition model is run to obtain leakage condition data. The recovery operation is performed based on the leakage condition model. The leakage condition model is updated to simulate the recovery process. The dynamically updated model is run to obtain the recovery process data. The resilience of the gas pipeline network is calculated based on normal operating condition data, leakage operating condition data, and recovery process data. Constructing a baseline topology-hydraulic model includes the following steps: Preset the threshold for the difference in pipe diameter between adjacent pipe sections, and preset the threshold for the difference in service age between adjacent pipe sections; Initialize the connection points between pipe segments as candidate nodes; For each candidate node, if the difference in pipe diameter between two adjacent pipe segments is greater than the pipe diameter difference threshold, or the difference in service years is greater than the service age difference threshold, then the candidate node is determined as a network node. If the outlet of the pipeline segment is the gas inlet or connected to a pressure regulating station, the candidate node corresponding to the outlet of the pipeline segment will be determined as a network node. The two adjacent pipe segments corresponding to candidate nodes that are not determined as network nodes are simplified and merged into a continuous pipe segment. Based on the final determined connection relationships between network nodes and pipe segments, a simplified topology of the gas pipeline network is established. Based on simplified topology, structural parameters, and operational boundary conditions, model elements are configured and initial parameters are set to construct the baseline topology-hydraulic model. Running the baseline topology-hydraulic model to obtain normal operating data of the gas pipeline network includes the following steps: Based on the baseline topology-hydraulic model, construct the pipe segment-node correlation matrix A. A Middle elements a ij Determined according to the following rules: Among them, elements a ij For the correlation matrix A The Middle i Line number j The elements of the column are used to represent network nodes. i With pipe section j Relationship; The network node stress equation is established based on the correlation matrix A, as follows: in, q A vector representing the quality traffic of network nodes. A T yes A transpose, P surface Show The vector of network node stress; C represents the admittance matrix; The formula for calculating the admittance matrix C is as follows: in, Q This refers to the mass flow rate of the pipe section. d This refers to the inner diameter of the pipe. λ This is the hydraulic resistance coefficient; Mass flow rate of pipe section Q The calculation formula is as follows: in, P 1 、P 2 These are the pressures at the beginning and end of the pipe section, respectively. R G It is the gas constant; T Indicates the absolute temperature of a gas; L This indicates the length of the pipe section; z is the compressibility coefficient. The mass flow rate of each pipe section and the pressure data of the corresponding network nodes are calculated sequentially to serve as the normal operating data of the gas pipeline network. A random leakage mechanism is introduced into the baseline topology-hydraulic model to randomly generate leakage data, specifically including the following steps: Based on the service life of the pipe section and daily maintenance records, a corresponding leakage failure rate is set for each pipe section; Within each time step of the simulation calculation, a random number uniformly distributed in the interval [0, 1] is generated for each pipe segment; The random number corresponding to the pipe section is compared with the leakage fault value. When the random number is less than the threshold, it is determined that the pipe section has leaked. When a leak is detected in a pipe section, leak data is randomly generated, including: Leakage location L 0 ,in, L 0 ∈ (0, L ); Leakage orifice diameter D 0 ,in, D 0 ∈ (0, d ); The resilience of a gas pipeline network is calculated based on normal operating condition data, leakage operating condition data, and recovery process data, specifically including the following steps: The specific calculation formula for calculating the gas supply performance of the gas pipeline network during the simulation period is as follows: in, P(t) It refers to the gas supply performance of the gas pipeline network; i It represents the total number of gas demand points in the gas pipeline network; It is a gas demand node in the gas pipeline network. j Actual gas supply flow rate; It is a gas demand node in the gas pipeline network. j Demand traffic; t It is the simulated duration; Calculate the gas pipeline supply resilience based on the gas pipeline supply resilience evaluation function. R The specific calculation formula is as follows: in, P(t) The actual performance curve corresponds to a stochastic process; TP(t) For the target performance curve; S 1 and S 2 These represent the areas enclosed by the actual performance curve and the target performance curve, respectively. t 0 The time of random leakage; t 1 This is the end time of the recovery process.

2. The gas pipeline network resilience assessment method considering random leakage and recovery mechanisms according to claim 1, characterized in that, The static parameter set includes structural parameters, operation and maintenance status parameters, emergency resource parameters, and operational boundary conditions; Structural parameters include the outlet type, pipe length, pipe diameter, pipe wall thickness, and material of all pipe sections; Operation and maintenance status parameters include the service life of the pipeline segment and daily maintenance records; Emergency resource parameters include the location of the repair station; Operating boundary conditions include gas source pressure, flow rate, and gas demand flow rate at the user end.

3. The gas pipeline network resilience assessment method considering random leakage and recovery mechanisms according to claim 1, characterized in that, The baseline topology-hydraulic model is updated based on leakage data to form a leakage condition model, and the leakage condition model is run to obtain leakage condition data. The specific steps include: A virtual leak node is set up as a network node based on the leak location, and the pipe segment identified as leaking is divided into a front segment and a rear segment, with the length of the front segment being [length missing]. L 0 The length of the latter part is ; Based on the generated leak location and leak orifice diameter, add a virtual leak segment to the pipe segment where a leak is determined; The length of the virtual leaking pipe section is equal to the wall thickness of the pipe section where the leak is determined. The diameter of the virtual leak segment is equal to the diameter of the generated leak orifice. D 0 ; The terminal pressure of the virtual leak section is set to standard atmospheric pressure; Based on the newly added virtual leak nodes and virtual leak pipe segments, the topology of the baseline topology-hydraulic model is updated to generate leak condition data, including: Update pipe segment-node association matrix A Add rows and columns corresponding to the virtual leak nodes; Reconfigure the length parameters of the divided pipe segments; Set the operational boundary conditions for the virtual leaking pipe segment; Run the updated leakage condition model to calculate the pressure of each network node, the mass flow rate of the pipeline segment and the actual flow rate at the gas consumption end under the leakage condition, and obtain the leakage condition data. Among them, the actual flow rate at the gas consumption end q act The calculation formula is as follows: In the formula, Q rep It is the gas demand flow rate at the user end; P sev It is the service pressure of the gas pipeline network; P min It is the lowest pressure in the gas pipeline network.

4. The gas pipeline network resilience assessment method considering random leakage and recovery mechanisms according to claim 3, characterized in that, The recovery operation is performed based on the leakage condition model. The leakage condition model is updated to simulate the recovery process, and the dynamically updated model is run to obtain recovery process data. The specific steps include: The two ends of the pipe segment identified as leaking are sealed, the pipe segment identified as leaking and the virtual leaking pipe segment are isolated, and the topology and operating status of the leak condition model are updated accordingly. Based on the location of the emergency repair station, the time for allocating emergency repair resources is calculated using the following formula: in, t i This indicates the time allocating resources for emergency repairs of the gas pipeline network; L i The location of the emergency repair station is... i The shortest path distance to each leak point; V Indicates the average resource allocation speed; A preset diameter ratio threshold is set, and the diameter ratio of the leaking orifice diameter to the diameter of the pipe section identified as leaking is calculated. Based on the relationship between the diameter ratio and the diameter ratio threshold, different preset maintenance times are selected for simulation. After the simulated maintenance is completed, the seals at both ends of the leaking pipe section are removed, the virtual leaking pipe section is deleted, and the model topology and operating status are updated again. Throughout the recovery process, the dynamically updated model is run according to the simulation step size, and the sequence data of the mass flow rate of each network node and each pipe segment changing over time is calculated and recorded. The recorded sequence data is used as the recovery process data.

5. The gas pipeline network resilience assessment method considering random leakage and recovery mechanisms according to claim 4, characterized in that, The preset diameter ratio threshold is 0.2; When the diameter ratio is less than 0.2, the preset maintenance time follows a normal distribution with a mean of 6 hours and a variance of 3 hours. When the diameter ratio is greater than or equal to 0.2, the preset maintenance time follows a normal distribution with a mean of 12 hours and a variance of 6 hours.

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