A method for determining maintenance and repair time of a natural gas pipeline network unit

Abstract

The embodiment of the specification provides a natural gas pipeline unit maintenance and repair time determination method, relates to the technical field of natural gas pipeline transportation safety, and comprises the following steps: determining corresponding unit maintenance and repair costs according to allowable maintenance and repair times of each natural gas pipeline unit; determining corresponding system gas shortage loss costs according to system gas shortage amounts caused by each natural gas pipeline unit under non-steady-state working conditions after the natural gas pipeline unit fails; determining a natural gas pipeline gas supply reliability according to operation reliabilities of each natural gas pipeline unit; taking minimization of the unit maintenance and repair costs and the system gas shortage loss costs as a target, taking the gas supply reliability being not lower than a target reliability as a constraint, and constructing an optimization model; and determining optimal maintenance and repair times of each natural gas pipeline unit according to the optimization model.

Description

TECHNICAL FIELD

[0001] Embodiments of the present specification relate to the technical field of natural gas pipeline transportation safety, and in particular to a method for determining maintenance and repair time of a natural gas pipeline network unit. BACKGROUND

[0002] A natural gas pipeline network system is composed of pipelines, compressor stations, valves and other units. In complex working conditions and long-term operation, random failures may occur in each unit. Such failures not only easily induce safety accidents, but also cause gas supply interruption to downstream users, resulting in serious consequences. Therefore, how to quickly develop a repair plan that takes into account system gas supply reliability and optimizes resource costs after equipment failure has become a key challenge in the safe and efficient operation of the pipeline network.

[0003] Currently, preventive maintenance of units such as pipelines and compressor stations has been widely studied. However, the development of maintenance and repair plans after failure still mainly relies on manual experience and simple rules, such as "repair first, process first" or "nearest dispatch". Traditional maintenance and repair plans usually require gas supply to be restored within 72 hours, and lack quantitative evaluation of system gas supply reliability and resource loss control, with the following obvious defects: ignoring the importance of the location of the failed unit in the pipeline network topology, unable to distinguish between the large-scale gas stop caused by key node failure and the local impact of non-key branch failure; when multiple units fail simultaneously, it is difficult to evaluate the additive effect of different repair sequences on the gas supply recovery process; the cost control mechanism is relatively extensive, and the maintenance and repair resource scheduling cannot form a deep linkage with the comprehensive resource loss caused by failure; there is a lack of accurate modeling of the dynamic correlation between "maintenance and repair time-gas supply reliability-resource loss", and the improvement effect of different repair plans on system gas supply reliability and its optimization potential for total cost cannot be quantified.

[0004] Although there are methods in existing research that simulate the impact of unit failure on system gas supply capacity and determine the maximum allowed maintenance time of the unit based on the minimum allowed gas supply reliability, such methods fail to consider multiple factors such as maintenance and repair resource constraints and pipeline network operating conditions, resulting in poor accuracy of the determined maintenance time, limited applicability in actual engineering, and greatly restricted engineering application value. SUMMARY

[0005] The purpose of the embodiments of the present specification is to provide a method for determining the maintenance and repair time of a natural gas pipeline network unit to overcome the problem of poor accuracy of the maintenance time in existing methods, limited applicability in actual engineering, and greatly restricted engineering application value.

[0006] To solve the above technical problems, the specific technical solutions of the embodiments of the present specification are as follows:

[0007] In one aspect, the embodiments of the present specification provide a method for determining maintenance and repair time of a natural gas pipeline network unit, comprising:

[0008] determining unit maintenance and repair cost of each natural gas pipeline network unit according to allowable maintenance and repair time of each natural gas pipeline network unit;

[0009] determining system gas shortage loss cost of each natural gas pipeline network unit according to system gas shortage amount caused by each natural gas pipeline network unit under non-steady state condition after failure of each natural gas pipeline network unit;

[0010] determining gas supply reliability of the natural gas pipeline network according to operation reliability of each natural gas pipeline network unit;

[0011] building an optimization model with the objective of minimizing the unit maintenance and repair cost and the system gas shortage loss cost and the constraint of the gas supply reliability being not lower than target reliability;

[0012] determining optimal maintenance and repair time of each natural gas pipeline network unit according to the optimization model.

[0013] In another aspect, the embodiments of the present specification provide a device for determining maintenance and repair time of a natural gas pipeline network unit, comprising:

[0014] a first determining module configured to determine unit maintenance and repair cost of each natural gas pipeline network unit according to allowable maintenance and repair time of each natural gas pipeline network unit;

[0015] a second determining module configured to determine system gas shortage loss cost of each natural gas pipeline network unit according to system gas shortage amount caused by each natural gas pipeline network unit under non-steady state condition after failure of each natural gas pipeline network unit;

[0016] a third determining module configured to determine gas supply reliability of the natural gas pipeline network according to operation reliability of each natural gas pipeline network unit;

[0017] a building module configured to build an optimization model with the objective of minimizing the unit maintenance and repair cost and the system gas shortage loss cost and the constraint of the gas supply reliability being not lower than target reliability;

[0018] a fourth determining module configured to determine optimal maintenance and repair time of each natural gas pipeline network unit according to the optimization model.

[0019] In still another aspect, a computer device is provided, a memory is configured to store a computer program, and a processor is configured to execute the computer program to implement the method for determining maintenance and repair time of a natural gas pipeline network unit.

[0020] In still another aspect, the embodiments of the present specification further provide a computer readable storage medium storing a computer program, and the computer program is executed by a processor to implement the method according to any one of the above embodiments.

[0021] In still another aspect, the embodiments of the present specification also provide a computer program product, which, when executed by a processor of a computer device, executes the instructions of any one of the above-mentioned methods.

[0022] As can be seen from the technical solutions provided by the embodiments of the present specification, the embodiments of the present specification can determine the corresponding unit maintenance and repair costs according to the allowed maintenance and repair time of each natural gas pipeline network unit, determine the corresponding system gas shortage loss costs according to the system gas shortage caused by the failure of each natural gas pipeline network unit under non-steady state conditions, determine the gas supply reliability of the natural gas pipeline network according to the operation reliability of each natural gas pipeline network unit, construct an optimization model with the objective of minimizing the unit maintenance and repair costs and the system gas shortage loss costs and with the constraint that the gas supply reliability is not lower than a target reliability, and determine the optimal maintenance and repair time of each natural gas pipeline network unit according to the optimization model. Compared with the prior art, the embodiments of the present specification can quantify the maintenance and repair costs of each unit, the system gas shortage loss caused by the failure of each unit, and the specific influence of each unit on the system reliability, and analyze all the units globally in a unified optimization model. The embodiments of the present specification fundamentally overcome the problems of unreasonable resource allocation and suboptimal decision-making that may be caused by simple rules such as repair first and dispatching nearby. Therefore, the embodiments of the present specification can develop a comprehensive maintenance plan that truly meets the optimal interests of the entire pipeline network system. In addition, by accurately quantifying the parameters such as maintenance and repair costs, gas shortage loss costs, and gas supply reliability, the embodiments of the present specification establish a decision-making system based on data driving and model simulation. This computable and comparable quantitative analysis method significantly reduces the uncertainty and subjective randomness in the decision-making process, ensuring that the decision-making conclusion has higher objectivity and credibility. The final output is the optimal maintenance and repair time customized for each pipeline network unit. Since this result is obtained through multi-objective optimization calculation, it naturally meets the dual requirements of resource cost control and system safety guarantee, ensuring that each maintenance time instruction reflects the global optimal consideration of the system, and has significant engineering application value. Finally, by taking the minimization of the total cost as the optimization objective and taking the gas supply reliability not being lower than a target value as a hard constraint, the embodiments of the present specification effectively balance the relationship between resource cost and safety: the embodiments of the present specification avoid blind repair without considering resource costs, and prevent short-sighted behavior of sacrificing safety for the sake of saving resource costs, and finally realize the maintenance decision-making of optimal resource cost under the premise of ensuring gas supply safety. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced as follows.

[0024] Figure 1 is a structural composition schematic diagram of a natural gas pipeline network unit optimal maintenance and repair time determination device provided by the embodiments of the present specification;

[0025] Figure 2 is a flow chart of a natural gas pipeline network unit maintenance and repair time determination method provided by an embodiment of the present specification;

[0026] Figure 3 is a schematic diagram of the overall logic flow of a natural gas pipeline network unit maintenance and repair time determination method provided by an embodiment of the present specification;

[0027] Figure 4 is a schematic diagram of the topology of a certain natural gas pipeline network system provided by an embodiment of the present specification;

[0028] Figure 5 is a schematic diagram of the structure of a natural gas pipeline network unit maintenance and repair time determination device provided by an embodiment of the present specification;

[0029] Figure 6 is a schematic diagram of the structure of a computer device provided by an embodiment of the present specification. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present specification will be described clearly and completely below with reference to the drawings in the embodiments of the present specification. Obviously, the described embodiments are only some of the embodiments of the present specification, not all. Based on the embodiments in the present specification, all other embodiments obtained by those of ordinary skill in the art without creative labor should fall within the scope of protection of the present specification.

[0031] It should be noted that the terms "first", "second", etc. in the present specification and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present specification described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, device, product or equipment that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0032] In some embodiments, the natural gas pipeline network can include at least one gas source unit, a plurality of pipe segment units, at least one compressor station unit, a plurality of distribution station units, and a plurality of valve chamber units.

[0033] The gas source unit can serve as the gas source point of the system, responsible for injecting natural gas into the pipeline network, and is the starting point and fundamental guarantee of the entire gas transmission system.

[0034] The pipe section unit can be used as a transport backbone, connected by pipelines to form a physical channel for natural gas transmission in the system, responsible for transporting natural gas from upstream to downstream.

[0035] The compressor station unit can be used as a power core, arranged between the pipe section units, for boosting the pressure of the natural gas in transport to compensate for the pressure loss generated by its flow in the pipeline, ensuring that the natural gas can overcome the resistance and be transported to a further distance.

[0036] The distribution station unit can be used as a user interface, connected to a designated pipe section unit, responsible for taking out (distribution) natural gas from the main pipe network as needed and delivering it to downstream end users, which is the final link to realize the value of pipe network gas supply.

[0037] The valve chamber unit can be used as a pipe network controller, arranged along the pipe section units, and the internal valves can be used to turn on or off or adjust the natural gas flow in the pipeline. In the maintenance and repair condition, by closing a specific valve chamber unit, the failed pipe section can be quickly isolated, so as to control the gas supply interruption range to the minimum and ensure the safety of maintenance work.

[0038] These functionally different units can be connected by topology to form an organic whole: the gas from the gas source unit is transported through the pipe section unit, powered by the compressor station unit, distributed to users through the distribution station unit, and controlled and fault-isolated by the valve chamber unit, to jointly complete the continuous, stable and safe supply of natural gas.

[0039] Referring to Figure 1 The embodiment of the present specification provides a natural gas pipe network unit optimal maintenance and repair time determination device, which comprises:

[0040] The unit maintenance and repair time interval determination module is used to determine the allowed maintenance and repair time interval of each unit of the natural gas pipe network after failure according to the natural gas pipe network maintenance and repair resource distribution and related operation and maintenance management regulations.

[0041] The natural gas pipe network steady-state hydraulic simulation module is used to establish a physical simulation model of the natural gas pipe network according to the topological structure information and design parameters of the natural gas pipe network, and to simulate the steady-state hydraulic simulation of the natural gas pipe network according to the typical operation condition of the natural gas pipe network, to determine the initial state of the non-steady-state condition simulation.

[0042] The system gas shortage amount calculation module is used to simulate the non-steady-state hydraulic simulation of the natural gas pipe network after the failure of each unit, calculate the system gas shortage amount of the pipe network after the failure of each unit, and construct a functional expression of the unit maintenance and repair time and the system gas shortage amount.

[0043] The system gas shortage amount loss cost calculation module is used to construct a loss cost calculation model of the system gas shortage amount according to the user gas contract.

[0044] Unit reliability calculation model: used to represent the dynamic transition process of unit state according to Markov chain, establish a dynamic calculation model of unit reliability, and construct a correlation model of unit reliability and maintenance time.

[0045] Unit maintenance cost calculation module: according to the historical maintenance data of natural gas pipeline network, a function expression of unit maintenance time and maintenance cost is constructed.

[0046] System gas supply reliability calculation module: used to construct a natural gas pipeline network system gas supply reliability calculation model according to the system gas supply satisfaction in the evaluation period.

[0047] Optimization model construction module: used to construct a target function with minimum total cost according to the unit maintenance cost and system gas loss cost; construct a system gas supply reliability constraint condition according to the target reliability of system gas supply; and construct a unit maintenance time constraint according to the unit operation and maintenance time interval.

[0048] Optimization model solving module: used to solve the optimization model to obtain the optimal maintenance time of each unit of the natural gas pipeline network.

[0049] The embodiment of the present specification provides a natural gas pipeline network unit maintenance time determination method, Figure 2 is a flowchart of a natural gas pipeline network unit maintenance time determination method provided by the embodiment of the present specification, Figure 3 is a schematic diagram of the overall logic flow of a natural gas pipeline network unit maintenance time determination method provided by the embodiment of the present specification, and in specific implementation, the following steps are included:

[0050] S101: according to the allowed maintenance time of each natural gas pipeline network unit, determine the corresponding unit maintenance cost.

[0051] In some embodiments, according to the maintenance resource distribution data and maintenance resource allocation constraint data of the natural gas pipeline network, the allowed maintenance time of each natural gas pipeline network unit after failure is determined.

[0052] In some embodiments, the maintenance resource distribution data can include the configuration of maintenance personnel, equipment, spare parts and other resources in different geographic locations. In the area with abundant resources, shorter maintenance response time can be achieved.

[0053] In some embodiments, the unit maintenance and repair cost can include manual operation resource cost, equipment resource cost, and performance loss cost. The manual operation resource cost can include the technical labor resource consumption of the maintenance team with specific skills and qualifications, the scale, composition, and operation time of the maintenance team. The equipment resource cost can include the cost of the special mechanical equipment and technical tools (such as welding equipment, hoisting equipment, and detection instruments) used in the maintenance process. The material and performance loss cost can include the performance life loss of the pipe network unit caused by the specific process used to achieve the goal of rapid repair. For example, the emergency welding process can affect the long-term corrosion resistance of the pipeline, resulting in a technical reduction in the remaining service life.

[0054] In some embodiments, the maintenance and repair resource allocation constraint can represent the rules and restrictions followed by resource allocation when multiple units may need maintenance at the same time, including priority division and resource mutual use.

[0055] Based on the above data and constraints, a feasible allowed maintenance and repair time interval can be calculated for each unit, which represents the shortest to longest time required to complete the maintenance and repair of the unit under existing resource conditions. By converting resource distribution and constraints into specific time intervals, the originally fuzzy experience judgment is replaced by quantifiable and calculable time parameters, providing accurate input for subsequent global optimization.

[0056] In some embodiments, the step S101 can specifically include calculating the unit maintenance and repair cost of each natural gas pipeline network unit using a unit loss model according to the allowed maintenance and repair time of the natural gas pipeline network unit. The unit loss model is used to represent the mapping relationship between the maintenance and repair time and the maintenance and repair cost of the natural gas pipeline network unit.

[0057] In some embodiments, the unit loss model can be a pre-established mathematical function or data mapping relationship, with maintenance and repair time as input and corresponding maintenance and repair cost as output. The model can quantify the trade-off between time and cost. That is, the shorter the repair time, the more emergency resources (such as urgent spare parts, additional manpower, and special equipment) need to be invested, resulting in higher cost; conversely, using regular maintenance, the time is longer, but the cost is lower. By introducing the unit loss model to dynamically associate maintenance time and cost, the drawbacks of traditional extensive cost management are overcome. This makes it possible to clearly foresee the resource cost of different maintenance strategies.

[0058] In some embodiments, for any one of the allowed maintenance and repair time, the unit maintenance and repair cost can be the total cost of direct resources required to complete the maintenance task at the given maintenance and repair time, which can include human resources, equipment rental resources, material resources, and urgent resources generated to compress time, etc.

[0059] In some embodiments, for each natural gas pipeline network unit, any one of the allowed maintenance and repair time determined can be input into the corresponding unit loss model. The model can calculate the estimated resource cost of completing this maintenance, i.e., the unit maintenance and repair cost, through internal mapping rules.

[0060] All unit maintenance and repair cost estimates are based on realistic resource constraints and verified models, so that the final optimal maintenance and repair scheme is not only theoretically optimal, but also highly executable in actual engineering.

[0061] S102: According to the system gas shortage caused by the failure of each natural gas pipeline network unit under non-steady state conditions, the corresponding system gas shortage loss cost is determined.

[0062] In some embodiments, the above step S102 can specifically include: establishing a natural gas pipeline network physical simulation model according to natural gas pipeline network topology structure data and design parameter data; performing steady-state simulation of the natural gas pipeline network based on the physical simulation model; using the physical simulation model to perform non-steady-state simulation of the natural gas pipeline network after failure of each natural gas pipeline network unit based on the steady-state simulation results; determining the system gas shortage of the natural gas pipeline network within the corresponding allowed maintenance and repair time for each natural gas pipeline network unit after failure of the natural gas pipeline network; calculating the system gas shortage loss cost using a system loss model according to the corresponding system gas shortage of each natural gas pipeline network unit; the system loss model represents the mapping relationship between the system gas shortage of the natural gas pipeline network and the loss cost.

[0063] In some embodiments, the natural gas pipeline network topology structure data can include the connection relationship between each unit, such as how the pipeline unit is connected to the station unit.

[0064] In some embodiments, the natural gas pipeline network design parameter data can include pipe diameter, pipe length, design pressure, compressor performance curve, etc.

[0065] In some embodiments, the system gas shortage loss cost can include technical resource cost of alternative energy scheduling, technical operation resource cost of maintaining stability of the pipe network system, and technical performance loss cost of user end production equipment and process. Among them, the technical resource cost of alternative energy scheduling can be that when the main pipe network gas supply is interrupted, the technical means of higher cost must be started to produce or transport alternative gas sources to ensure continuous supply of core users. The technical resource cost of alternative energy scheduling can include peak shaving gas source starting cost and pipe network gas source allocation cost. The peak shaving gas source starting cost can be a large amount of energy resources such as electric energy and heat energy consumed in the process of starting the underground gas storage to produce gas, starting the LNG emergency peak shaving station to gasify and export, etc. The pipe network gas source allocation cost can be the additional start-stop and pressure boosting operation of the remote compressor set caused by the air force allocation from other pipe network trunk lines, the increased electric energy consumption and equipment wear and tear. The technical operation resource cost of maintaining stability of the pipe network system can be that local failure causes sudden change of hydraulic working condition of the whole network, and additional technical intervention measures need to be taken to maintain the system from being paralyzed, which can include pipe network dynamic control cost and system re-stabilization energy consumption. The pipe network dynamic control cost can be that the control system needs to execute more frequent adjustment instructions to respond to the dramatic fluctuation of flow and pressure, resulting in the surge of action times of the actuator such as pressure regulating valve and control valve, and the equipment wear and tear and stability risk. The system re-stabilization energy consumption can be that after the working condition disturbance, the system needs to consume additional compressor power and other energy resources to reach a new stable state. The technical performance loss cost of user end production equipment and process can be the technical damage and additional resource consumption caused by the gas supply interruption to the production device of the downstream user (especially industrial user), which can include production process interruption cost and product and raw material loss cost. The production process interruption cost can be that the industrial kiln, heating furnace and other high-temperature equipment are urgently shut down, the lining is damaged by thermal shock, the service life is reduced, and the production line needs to be restarted to consume several times of energy resources required for normal maintenance. The product and raw material loss cost can be that the production process interruption causes the scrap of work-in-process (such as the reaction material solidification in the pipeline in the chemical industry), resulting in the loss of physical materials.

[0066] Based on the above data, a physical simulation model for simulating the flow of natural gas in the pipe network can be established, which is the basis for all subsequent hydraulic simulation.

[0067] The hydraulic state of the pipe network when reaching equilibrium under the typical working condition of normal operation of all units can be simulated, including pressure and flow distribution. The steady-state simulation results obtained can provide a physically real and consistent initial state for subsequent unsteady-state simulation, ensuring that the failure simulation starts from a correct baseline working condition.

[0068] In some embodiments, for each unit, after its failure, a non-steady-state simulation can be performed based on the aforementioned steady-state initial conditions using the physical simulation model to calculate the dynamic changes in the pipeline network pressure and flow rate throughout the allowable maintenance repair time.

[0069] Through the non-steady-state simulation, the system gas shortage caused by the failure of the unit can be determined. In some embodiments, the system gas shortage can be the cumulative difference between the total natural gas demand of downstream users and the actual maximum gas supply capacity of the pipeline network system during the maintenance repair period. By accurately calculating the system-level gas shortage caused by the failure of a specific unit through high-fidelity physical simulation (steady-state → non-steady-state) and quantifying it as a resource cost using the loss model, the drawbacks of relying on rough estimates for resource loss assessment in traditional methods are overcome. By simulating the consequences of the failure of each unit separately, the criticality of different units in the pipeline network topology can be accurately assessed, which helps to clearly identify which unit failures will cause catastrophic resource losses, thereby prioritizing protection during resource allocation and achieving an upgrade from uniform management to precise differentiated control.

[0070] In some embodiments, the system loss model can be a model that quantifies gas supply interruptions as resource costs. It establishes a mapping relationship between system gas shortage and system gas shortage loss costs.

[0071] In some embodiments, the system gas shortage loss cost can include the production resource loss caused to downstream users due to gas supply interruptions.

[0072] The system gas shortage corresponding to each unit obtained can be input into the system loss model, and the estimated system gas shortage loss cost caused by the failure of the unit can be calculated.

[0073] By quantifying the resource loss cost results of different unit failures, early risk identification and weak link analysis can be achieved, providing data support for preventive maintenance, thereby achieving proactive safety and cost control.

[0074] S103: Determine the gas supply reliability of the natural gas pipeline network according to the operation reliability of each natural gas pipeline network unit.

[0075] In some embodiments, the step S103 can specifically include: obtaining failure rate data and repair rate data of each natural gas pipeline network unit; calculating running state probability of each natural gas pipeline network unit at each time in the current evaluation period according to the failure rate data and the repair rate data; fusing the running state probability of each natural gas pipeline network unit at each time in the current evaluation period to obtain running reliability of the natural gas pipeline network unit in the current evaluation period; obtaining total gas demand of the natural gas pipeline network in the current evaluation period; and determining gas supply reliability of the natural gas pipeline network in the current evaluation period according to the running reliability of each natural gas pipeline network unit and the total gas demand of the natural gas pipeline network.

[0076] In some embodiments, the failure rate data can be a probability of failure of the natural gas pipeline network unit in a unit time, which can represent inherent reliability of the unit. The failure rate data can be obtained based on historical operation and maintenance statistical data analysis.

[0077] In some embodiments, the repair rate data can be a probability of repair of the failed unit in a unit time, and the reciprocal of the repair rate data is the average repair time, which can reflect repair efficiency.

[0078] In some embodiments, the evaluation period can be a preset continuous time window, which is used to systematically evaluate and quantify the influence of repair and rescue decisions on long-term gas supply reliability of the natural gas pipeline network. The evaluation period can be a preset management time scale, for example, 30 days, 90 days or a quarter, which represents a complete operation evaluation or planning period. The evaluation period can be a unified evaluation benchmark, and the reliability calculation of all units and the gas supply reliability evaluation of the system as a whole are performed in the same period, which ensures comparability between different decision schemes.

[0079] In some embodiments, based on the failure rate data and the repair rate data, a random process model can be used to calculate a probability that each unit is in a normal running state at each time in the current evaluation period. The running state probability can be a dynamic function varying with time, which is used to describe availability of the unit at any time in the evaluation period.

[0080] By fusing the running state probability of the unit at each time in the entire current evaluation period, a comprehensive reliability index, i.e., the running reliability of the unit, can be obtained. The running reliability can be a scalar value between 0 and 1, which represents a macroscopic reliability degree of the unit in maintaining normal running in the evaluation period. By calculating the state probability in the entire evaluation period and taking the repair time as a variable affecting the reliability of the unit, the reliability evaluation result can reflect long-term effects of repair strategies, which provides a quantitative basis for pursuing a balance between short-term repair resource cost and long-term running reliability.

[0081] In some embodiments, the total gas demand can be the total amount of natural gas demand of all downstream users of the natural gas pipeline network within the current evaluation period.

[0082] In some embodiments, the ability of the system to meet the total gas demand can be evaluated by integrating the operation reliability of all units and considering the topological structure and hydraulic constraints of the pipeline network, so as to calculate the gas supply reliability of the natural gas pipeline network. The index can quantify the probability or ability level of the natural gas pipeline network system to fully meet the total demand of the users within the evaluation period.

[0083] By establishing a complete calculation chain of unit failure rate / repair rate→unit operation reliability→system gas supply reliability, the probability of failure at the equipment level is converted into the gas supply guarantee capability index at the system level, overcoming the problem of overly rough system reliability evaluation in traditional methods.

[0084] S104: An optimization model is constructed with the objective of minimizing the unit maintenance and repair costs and the system gas shortage loss costs, and with the constraint that the gas supply reliability is not lower than the target reliability.

[0085] In some embodiments, the step S104 can specifically include: determining the total loss cost of the natural gas pipeline network according to the unit maintenance and repair costs and the system gas shortage loss costs; determining the maintenance and repair time interval of each natural gas pipeline unit; and constructing an optimization model with the objective of minimizing the total loss cost of the natural gas pipeline network and with the constraints that the gas supply reliability is not lower than the target reliability and the maintenance and repair time interval of each natural gas pipeline unit.

[0086] In some embodiments, the total loss cost can be the sum of the unit maintenance and repair cost (the resource cost directly invested in repairing the failed unit) and the system gas shortage loss cost (the indirect resource loss caused by the interruption of gas supply).

[0087] In some embodiments, the gas supply reliability constraint can be constructed by requiring the gas supply reliability to be not lower than the preset target reliability. The target reliability can be the minimum reliability threshold set by the pipeline network operator according to the gas supply safety standard and the user agreement, serving as the rigid boundary of the optimization solution, to ensure that any solution cannot sacrifice safety at the cost.

[0088] In some embodiments, the maintenance and repair time interval constraint can be constructed by requiring the maintenance and repair time of each unit to be within the corresponding maintenance and repair time interval. The interval defines the feasible range of maintenance time consumption, the lower limit of which can be determined by technical feasibility, and the upper limit of which can be specified by operational pressure, constituting the search space of the decision variable.

[0089] In some embodiments, the above elements can be integrated to establish the mathematical optimization model as shown below:

[0090] ;

[0091] In the formula, from top to bottom are: finding the optimal maintenance time set, minimizing the unit maintenance cost and system gas loss cost, the gas supply reliability not being lower than the target reliability, and the maintenance time interval of each natural gas pipeline network unit.

[0092] The optimization model abstracts the maintenance decision as a mathematical problem of finding the extreme point of the objective function under given constraints. By creating a decision framework that can handle resource cost and reliability at the same time, the optimal solution can be found while ensuring that the safety indicator of gas supply reliability meets the standard, fundamentally solving the problem of mutual separation of resource cost and reliability in traditional methods. By unifying maintenance cost, interruption loss, reliability requirements, and other multi-dimensional factors in a mathematical model, the optimization model can systematically and quantitatively evaluate the comprehensive effect of different maintenance strategies. This upgrades the decision-making from relying on scattered experience and qualitative judgment to scientific decision-making based on comprehensive data analysis and accurate calculation, significantly improving the systematicness and global optimality of the decision-making. Since the model strictly follows the maintenance time interval determined by the actual resources and working conditions and the target reliability determined by the safety standard, the optimal maintenance time scheme obtained by solving the model is not only mathematically optimal but also highly executable and safe in engineering practice, effectively avoiding decisions that are theoretically optimal but practically unworkable or risky.

[0093] S105: According to the optimization model, determine the optimal maintenance time for each natural gas pipeline network unit.

[0094] In some embodiments, the above step S105 can specifically include: according to the optimization model, determining the optimal maintenance time for each natural gas pipeline network unit.

[0095] A mathematical optimization algorithm (such as a nonlinear programming algorithm, a heuristic algorithm, etc.) can be used to solve the model. This process is automatically performed by a computing device, which iteratively calculates the decision variable values that minimize the objective function value, i.e., the optimal maintenance time for each natural gas pipeline network unit, under the premise of meeting all constraints. The optimal maintenance time can be a specific, quantitative maintenance time recommendation value calculated for each natural gas pipeline network unit. This time value is a balanced solution that is mathematically optimal and feasible in engineering after considering maintenance resource cost, gas supply interruption loss, and system reliability requirements.

[0096] By automatically solving mathematical optimization algorithms, precise optimal time solutions are output, completely abandoning the traditional decision-making model that relies on manual experience estimation, significantly improving the scientific nature and objectivity of the decision. The output optimal maintenance and repair time does not simply pursue the lowest cost or the fastest speed, but rather achieves the optimal global resource cost under the premise of strictly meeting the system's gas supply safety baseline (reliability constraints). This ensures that the final solution will neither waste resources due to excessive conservatism nor cause safety risks due to blindly pursuing speed.

[0097] In some embodiments, the construction of the unit loss model in step S101 above includes:

[0098] Construct the element loss model for the following pipeline element:

[0099] ;

[0100] in, For the first Unit maintenance and emergency repair costs for each pipeline unit; For the first Basic maintenance cost of a single piping unit; For the first Time penalty coefficient for each pipeline unit; For the first Cost attenuation rate coefficient for each pipeline unit; For the first Allowable maintenance and repair time for each pipeline unit.

[0101] Construct the unit loss model for the following compressor station unit:

[0102] ;

[0103] in, For the first The unit maintenance and repair cost of each compressor station unit; For the first Basic maintenance cost of a single compressor station unit; For the first Fixed additional costs for each compressor station unit; For the first Time compression penalty factor for each compressor station unit; For the first Permissible maintenance and repair time for each compressor station unit; For the first The shortest possible maintenance and repair time for each compressor station unit; This is a unit of time compression.

[0104] The above two formulas strictly define the mapping relationship between maintenance time and maintenance cost through mathematical functions, and convert the originally fuzzy and experience-based decision basis into precise and calculable quantitative indicators. Further, both formulas show that the maintenance cost is a function of the maintenance time, and thus the resource cost of any maintenance time scheme can be accurately predicted. The maintenance operations of pipeline and compressor station units have essential differences in technical complexity and resource investment mode, so a unified cost model is not used, but targeted modeling is performed, which greatly improves the accuracy and engineering applicability of the model. For pipeline units: an exponential decay model is used. This model vividly depicts the characteristics of pipeline maintenance: as the maintenance time is extended, the cost does not decrease linearly, but decreases rapidly and then gradually approaches a minimum cost. This reflects the fact that the cost of emergency resources required for extreme compression time is huge, while the cost of regular rhythm maintenance is relatively fixed. For compressor station units: an exponential model is used. This model accurately describes the stepwise resource investment characteristics of large and complex equipment maintenance. When the maintenance time is compressed by a fixed time compression unit (such as a work shift), an additional rush resource needs to be invested, and the cost increases by a step. This perfectly simulates the cost changes brought about by increasing shifts, investing more teams for parallel work, and other realistic rush strategies. These two highly engineered cost models ensure that the maintenance cost term in the subsequent objective function is real and reliable. If the cost model is distorted, the entire optimization result will lose its engineering guidance significance.

[0105] In some embodiments, the system loss model construction in step S102 includes:

[0106] The following system loss model is constructed:

[0107] ;

[0108] In the formula, is the resource loss due to the amount of system gas shortage; is the amount of system gas shortage; is the average resource income of natural gas; is the resource cost of natural gas production.

[0109] The amount of system gas shortage is a technical parameter obtained through physical hydraulic simulation, which represents the degree of interruption of the gas supply function of the pipeline network system. The above formula converts the physical function loss (amount of gas shortage) into equivalent technical resource loss through This coefficient, here, can be interpreted as the effective energy value carried by a unit of natural gas, can be interpreted as the physical resource investment to produce a unit of energy. Therefore, the loss The actual quantity is the waste of energy resources and the loss of expected output energy caused by the interruption of system function, which is a purely technical efficiency evaluation based on the physical energy view.

[0110] In the optimization model, the system loss and the unit maintenance cost jointly constitute the total cost objective. This makes the algorithm pursue high gas supply reliability while also considering the low efficiency of energy resource utilization caused by system failure. The formula ensures that the optimization process balances between technical resource investment (maintenance cost) and technical resource loss / waste (gas shortage loss), thereby achieving the maximization of comprehensive utilization efficiency of technical resources in the system while ensuring system safety (reliability).

[0111] In current natural gas pipeline network maintenance optimization research, the upper and lower limit constraints of unit reliability are key technical elements for balancing the feasibility, cost-effectiveness, and system objectives. Existing research mainly determines unit reliability constraints through the following methods: 1) Physical limit-based analysis method, which obtains the failure time distribution of materials or units through physical experiments or high-fidelity numerical simulations, and then determines the reliability boundary according to the physical performance limit. 2) Statistical method based on historical data, relying on the reliability database of similar units, combining expert experience and field operation data, and deducing the reliability constraint range of specific units through similarity analysis. 3) Constraint method based on economic cost, which sets a cost threshold to deduce the reliability constraint boundary by establishing a reliability-cost correlation curve. However, these traditional methods face significant limitations in the special system of natural gas pipeline networks. Due to the characteristics of wide spatial span, long service period, and strong heterogeneity of units in natural gas pipeline networks, physical limit analysis based on material property parameters or strength simulation is difficult to guide the determination of actual unit reliability constraints. At the same time, due to the current situation of late start of industry reliability management and insufficient data accumulation, the statistical method based on historical data and the economic cost constraint method also lack implementation basis. More importantly, as a typical repairable system, the maintenance strategy of natural gas pipeline networks directly affects the state transition process of the system, and thus has a dynamic impact on the system's gas supply capacity. Traditional static analysis methods only calculate reliability based on fixed failure rates, without fully considering the comprehensive influence of system dynamic maintenance characteristics and evaluation period, resulting in results that are difficult to support the optimization needs of current maintenance strategies.

[0112] To solve the above problems, in some embodiments, a state transition probability matrix is established according to the unit failure rate and maintenance rate, the reliability of the unit is evaluated in combination with the time dimension, and the allowed maintenance time interval is determined according to engineering practice to determine the unit reliability limit constraint.

[0113] In some embodiments, the outage process of the pipeline unit and the compressor station unit is a stochastic process, which belongs to a typical Markov process. The current operating state of each unit is only related to the operating state of the previous stage, and is not related to the operating state before. The Markov chain accurately describes the dynamic transition process of the unit state by defining the state space and the transition probability matrix. The expression of the probability distribution of the unit state is:

[0114]

[0115] wherein, is the transition rate matrix. is a vector composed of the probabilities of the unit being in various states at time t. At any time, the sum of the probabilities of the unit being in various states is 1, i.e.:

[0116]

[0117] The first-order ordinary differential linear equation set of the probability distribution of the unit state is:

[0118]

[0119] wherein, represents the state transition rate of the unit being in state i at time t and in state j (j≠i) at time t+Δt. The expression is:

[0120]

[0121] Assuming that the unit in the system only has two states of normal and failure, the ordinary differential linear equation set of the state transition of the pipeline unit and the compressor station unit is respectively:

[0122]

[0123]

[0124] wherein, is the probability of the first pipeline unit being in normal operation at time t; is the probability of the first pipeline unit being in failure state at time t; is the length of the first pipeline unit, in units of km; is the failure rate of the first pipeline unit, in units of 1 / (km·h); is the repair rate of the first pipeline unit, in units of 1 / h, which is expressed as: is the probability of the first​​​​​​​​​ Each compressor station unit is in The probability of normal operation at any given time; For the first Each compressor station unit is in The probability of being in a constantly failing state; For the first Failure rate of each compressor station unit, in units of 1 / h; For the first Maintenance rate of each compressor station unit, in units of 1 / h.

[0125] Based on this, in some embodiments, step S103 above, which calculates the probability of the operating state of each natural gas pipeline unit at each moment within the current evaluation period based on the failure rate data and maintenance rate data, includes:

[0126] When the unit is in normal operation at the initial moment, the probability of the operating state of each pipeline unit at each moment in the current evaluation period is calculated using the following formula based on the failure rate data and maintenance rate data:

[0127] ;

[0128] In the formula, For the first Each pipe section unit The probability of normal operation at any given time; For the first Each pipe section unit The probability of being in a constantly failing state; For the first The length of each pipe segment unit, in km; For the first Failure rate of a single pipe section unit, unit: 1 / (km·h); For the first The maintenance rate of each pipe section unit, in units of 1 / h, is expressed as: ;

[0129] When the unit is in normal operation at the initial moment, the probability of the operating state of each compressor station unit at each moment in the current evaluation period is calculated using the following formula, based on the failure rate data and maintenance rate data:

[0130] ;

[0131] In the formula, For the first Each compressor station unit is in The probability of normal operation at any given time; For the first Each compressor station unit is in The probability of being in a constantly failing state; Failure rate of the nth compressor station unit, unit: 1 / h; Failure rate of the nth compressor station unit, unit: 1 / h; Maintenance rate of the nth compressor station unit, unit: 1 / h. Maintenance rate of the nth compressor station unit, unit: 1 / h.

[0132] The traditional method often uses an average, static reliability value, which cannot reflect the dynamic changes of the system within the maintenance period. By solving the state transition equation, the accurate probability of the unit being in normal or failure state at any time within the evaluation period can be calculated. This provides rich time resolution for evaluating the real-time changes of system reliability during maintenance.

[0133] Based on the different failure mechanisms of pipelines and compressor stations, targeted modeling is carried out, which improves the physical accuracy and prediction accuracy of the model. For pipeline units: the failure rate is proportional to the length of the pipe section. This accurately describes the physical nature of pipeline failure: the longer the pipeline, the greater the probability of defects or external interference, and the overall failure risk also increases linearly. For compressor station units: as complex station equipment, their failure is usually directly related to the running time, and has nothing to do with the length. Therefore, the model directly uses its inherent failure rate, which is more in line with the failure law of compressor units composed of rotating equipment.

[0134] By establishing a quantitative bridge between maintenance time and unit reliability, key inputs are provided for collaborative optimization. The maintenance rate is defined as the inverse of the maintenance time. This shows that the selected maintenance time directly affects the maintenance rate, directly changes the state transition probability in the Markov model, and ultimately determines the operational reliability of the unit within the entire evaluation period. This enables the resource cost decision of the maintenance strategy to be linked and weighed with the reliability consequences.

[0135] In some embodiments, the step S103 of fusing the operation state probability of each natural gas pipeline network unit at each time within the current evaluation period to obtain the operation reliability of the natural gas pipeline network unit in the current evaluation period comprises:

[0136] The operation reliability of each pipeline unit in the current evaluation period is fused by using the following formula:

[0137] ;

[0138] In the formula, Probability of the nth pipe section unit being in normal operation at time t; Probability of the nth pipe section unit being in normal operation at time t; Operation reliability of the nth pipeline unit in the current evaluation period; Operation reliability of the nth pipeline unit in the current evaluation period; Operation reliability of the nth pipeline unit in the current evaluation period; Operation reliability of the nth pipeline unit in the current evaluation period; The length of each pipe segment unit, in km; For the first Failure rate of a single pipe section unit, unit: 1 / (km·h); For the first Maintenance rate of each pipe section unit, unit: 1 / h; This represents the duration of the current evaluation period.

[0139] The operational reliability of each compressor station unit in the current evaluation period is obtained by fusing the operational state probabilities of each unit at each moment within the current evaluation period using the following formula:

[0140] ;

[0141] In the formula, For the first The operational reliability of each compressor station unit during the current evaluation period; For the first Each compressor station unit is in The probability of normal operation at any given time; For the first Failure rate of each compressor station unit, in units of 1 / h; For the first Maintenance rate of each compressor station unit, in units of 1 / h; This represents the duration of the current evaluation period.

[0142] The state probabilities output by Markov models are complex curves that change over time, making them unsuitable for direct use in system-level evaluation and optimization comparisons. However, by integrating and averaging over the entire evaluation period, dynamic information can be condensed into a single scalar value with clear statistical significance—the average operational reliability. This greatly simplifies the complexity of subsequent system reliability aggregation and optimization models, providing clear and intuitive quantitative input for management decisions.

[0143] The operational reliability defined by the above formula is essentially the expected value of the percentage of time a unit is in normal operating condition during the evaluation period. It can accurately reflect the long-term operational health of a unit under a given maintenance strategy, ensuring that the reliability assessment results of different units and different maintenance schemes are based on a unified and fair benchmark.

[0144] As mentioned earlier, maintenance time affects the maintenance rate, which in turn affects the state probability. The above formula ultimately maps to the reliability of the natural gas pipeline network unit within the evaluation period, laying the foundation for subsequently constructing system-level gas supply reliability constraints. Therefore, the above formula can ensure that any adjustment to maintenance time has a precise quantification of its long-term reliability consequences, which are then fed back into the optimization model.

[0145] In some embodiments, determining the gas supply reliability of the natural gas pipeline network in the current evaluation period based on the operational reliability of each natural gas pipeline unit and the total gas demand of the natural gas pipeline network in step S103 above includes:

[0146] Based on the operational reliability of each natural gas pipeline unit and the total gas demand of the natural gas pipeline network, the gas supply reliability of the natural gas pipeline network in the current evaluation period is determined using the following formula:

[0147] ;

[0148] In the formula, The reliability of gas supply from the natural gas pipeline network during the current evaluation period; For the first The operational reliability of each unit during the current evaluation period; This represents the total number of natural gas pipeline network units. This represents the system gas shortage of the natural gas pipeline network within the allowable maintenance and repair time corresponding to the first natural gas pipeline network unit. This represents the total gas demand of the natural gas pipeline network during the current evaluation period. This represents the duration of the current evaluation period.

[0149] Traditional methods rely solely on the simple summation of reliability of units in a topological logic series, neglecting the differences in the actual impact of different unit failures on system function. The formula above correlates the reliability of each unit with the resulting gas shortage in the system. This means that the contribution weight of a unit's reliability to the overall system is proportional to the functional criticality of that unit within the pipeline network. The greater the gas shortage caused by a unit failure, the higher its contribution weight to the overall system reliability.

[0150] The model described above can automatically identify weak links and critical resources in the system. Even if two units have the same operational reliability, the unit that causes a larger gas shortage after failure will have a more significant negative impact on system reliability. This provides crucial insight for operation and maintenance strategies: when resources are limited, priority should be given to ensuring the repair and maintenance of critical units that have a greater impact on the system's gas supply reliability, thereby maximizing the benefits of safety investments.

[0151] The system's gas shortage volume is also the basis for calculating the system's gas shortage loss cost. The above formula inherently unifies the two optimization dimensions of reliability and resource cost. In the optimization model, the failure of a single unit affects the system in two ways: firstly, it reduces the system's gas supply reliability through the above formula, potentially reaching the bottom line of reliability constraints; secondly, it increases the system's gas shortage loss cost through the loss model, directly increasing the total cost objective function value. This consistency ensures that the optimization algorithm can reasonably balance the dual impact of maintenance plans on reliability constraints and resource cost objectives within the same logical framework.

[0152] In some embodiments, the determination of the gas supply reliability of the natural gas pipeline network in the current evaluation period in step S103 above further comprises:

[0153] The gas supply reliability of the natural gas pipeline network in the current evaluation period is determined by the following formula:

[0154] ;

[0155] In the formula, is the gas supply reliability of the natural gas pipeline network in the current evaluation period; is the length of the current evaluation period; is the probability of normal operation (no unit failure occurs); is the actual gas supply amount of the system in normal operation; is the occurrence probability of the cth failure scenario; is the actual gas supply amount of the system in the cth failure scenario; is the total number of gas consumption nodes; is the demand amount of the kth gas consumption node on the jth day.

[0156] When a unit failure occurs in the system, the pipeline network system will transition from normal operation state to failure operation state. Through the aforementioned gas supply reliability calculation model, the internal relationship between the unit operation state and the system gas supply capacity can be effectively quantified, so as to clearly specify the specific requirements for the reliability of each unit under the given system gas supply reliability target.

[0157] Based on the gas supply reliability determined by the model, the gas supply capacity of the natural gas pipeline network system can be quantitatively evaluated without considering the resource constraint conditions. At the same time, through the mature natural gas demand prediction method system, the influence of supply and demand uncertainty on the system gas supply reliability can be effectively reduced. At present, a relatively complete technical solution has been formed in this field and the prediction accuracy is continuously improving. Under the support of the perfect management system of the pipeline network system, the system gas supply capacity in normal operation state can fully meet the user demand.

[0158] The operation state of the pipeline network is jointly determined by the coupling of the operation states of each unit in the system. According to historical failure data statistics, the probability of simultaneous failure of two or more units in the system is less than 10 -6 . Considering that in the complex scenario of multiple unit failures, the system gas supply capacity is affected by the coupling of multiple failed units, it is difficult to effectively distinguish and compare the differences in the influence of different failed units on the system.

[0159] In some embodiments, a typical working condition of single unit failure can be considered, this simplified process guarantees the engineering applicability while meeting the failure statistical rules in actual operation, and can more clearly reflect the differentiated influence of different unit failures on the system gas supply reliability. The simplified model can be used for:

[0160] ;

[0161] ;

[0162] In the formula, is the gas shortage of the system on the jth day after the ith unit failure, and is the difference between the system demand and the actual supply; is the system demand on the jth day.

[0163] As can be seen from the technical solutions provided by the embodiments of the present specification, the system gas supply reliability can be established as a performance index for measuring the safety and functional integrity of the pipe network. This index is defined as the ratio of the actual gas supply amount of the pipe network to the total demand amount within a set evaluation period, directly reflecting the ability level of the pipe network system to complete its core gas supply function. In the optimization model, the system gas supply reliability is not lower than the preset target reliability as a rigid constraint condition, thereby ensuring that all maintenance repair schemes are based on the premise of meeting the system safety standard, and the bottom line safety of the pipe network operation is guaranteed from the decision-making mechanism.

[0164] As a repairable system, the unit repair time is a key parameter for connecting the field maintenance repair operation and the long-term operation safety of the system, and is also a decision variable closely related to the specific process implementation. The embodiments of the present specification model the dynamic transition between the normal and failure states of the unit by using the Markov process, according to which the average operation reliability of the unit within the entire evaluation period under a specific repair time can be accurately calculated, thereby establishing a quantitative relationship between the repair time (decision variable) and the unit reliability (state variable). Further, the influence of each unit failure on the actual gas supply capacity of the system is analyzed through hydraulic simulation, and the reliability of all units is integrated, and finally a complete mapping model from the unit repair time to the system gas supply reliability is established.

[0165] In addition, in the embodiments of the present specification, the unit maintenance repair cost and the system gas shortage loss cost are used as tools for quantifying the consequences of unit failure and the resource input of the repair process, aiming to effectively connect the optimization model with the resource consumption concept in actual engineering. Such cost model based on historical data fitting can provide a unified quantitative dimension (i.e., total resource cost) for the optimization algorithm, which can be compared between different repair schemes, thereby converging the complex multi-objective decision-making problem of safety, time and resources into a solvable single-objective optimization problem. The significance mainly lies in the mechanism construction of the optimization process, rather than simply pursuing the economic target.

[0166] One specific embodiment of the present specification is provided below:

[0167] Figure 4 The following is a topological structure diagram of a natural gas pipeline network system, which includes one gas source, ten pipeline sections, one compressor station, nine distribution stations, and nine valve chambers. The overall demand of users is 820 x 10 4 Nm 3 / d. Table 1 is the basic information of the pipeline network. Table 2 is the system overall gas shortage after the failure of each unit, with the unit being 10 4 Nm 3 .

[0168] Table 1

[0169]

[0170] Table 2

[0171]

[0172] According to historical data, a unit maintenance and repair time cost function is fitted, and each parameter is shown in Table 3.

[0173] Table 3

[0174]

[0175] The evaluation period of the pipeline network system is set to 30 days, the gas supply target reliability is 0.99, the optimization model is solved, and the calculation results are shown in Table 4.

[0176] Table 4

[0177]

[0178] Based on the above-mentioned natural gas pipeline network unit maintenance and repair time determination method, the present specification also proposes an embodiment of a natural gas pipeline network unit maintenance and repair time determination device. As shown in Figure 5 The natural gas pipeline network unit maintenance and repair time determination device 500 can specifically include the following modules:

[0179] The first determination module 501 is configured to determine the unit maintenance and repair cost of each natural gas pipeline network unit according to the allowed maintenance and repair time of each natural gas pipeline network unit;

[0180] The second determination module 502 is configured to determine the system gas shortage loss cost caused by the system gas shortage after the failure of each natural gas pipeline network unit under non-steady state conditions;

[0181] The third determination module 503 is configured to determine the gas supply reliability of the natural gas pipeline network according to the operation reliability of each natural gas pipeline network unit;

[0182] The construction module 504 is configured to construct an optimization model, with the objective of minimizing the unit maintenance cost and the system gas loss cost, and with the constraint of the gas supply reliability being not lower than a target reliability.

[0183] The fourth determination module 505 is configured to determine the optimal maintenance time of each natural gas pipeline network unit according to the optimization model.

[0184] In some embodiments, the first determination module 501 can be specifically configured to:

[0185] According to the maintenance resource distribution data and the maintenance resource allocation constraint data of the natural gas pipeline network, the allowed maintenance time of each natural gas pipeline network unit after failure is determined.

[0186] In some embodiments, the first determination module 501 can be specifically configured to:

[0187] According to the allowed maintenance time of each natural gas pipeline network unit, the unit maintenance cost of the natural gas pipeline network unit is calculated using a unit loss model, which is configured to represent the mapping relationship between the maintenance time and the maintenance cost of the natural gas pipeline network unit.

[0188] In some embodiments, the natural gas pipeline network unit includes a plurality of pipeline units and at least one compressor station unit.

[0189] Based on this, the first determination module 501 can be specifically configured to:

[0190] The unit loss model of the pipeline unit is constructed as follows:

[0191] ;

[0192] wherein, is the unit maintenance cost of the i th pipeline unit; is the basic maintenance cost of the i th pipeline unit; is the time penalty coefficient of the i th pipeline unit; is the cost decay rate coefficient of the i th pipeline unit; is the allowed maintenance time of the i th pipeline unit. The unit loss model of the compressor station unit is constructed as follows: ;

[0193] wherein,

[0194] ;

[0195] wherein, is the unit maintenance cost of the i th compressor station unit; ​​​unit repair cost of the i-th compressor station unit; basic repair cost of the i-th compressor station unit; basic repair cost of the i-th compressor station unit; fixed additional cost of the i-th compressor station unit; fixed additional cost of the i-th compressor station unit; time compression penalty factor of the i-th compressor station unit; time compression penalty factor of the i-th compressor station unit; allowed repair time of the i-th compressor station unit; allowed repair time of the i-th compressor station unit; shortest achievable repair time of the i-th compressor station unit; shortest achievable repair time of the i-th compressor station unit; time compression unit.

[0196] In some embodiments, the second determining module 502 can be specifically configured to:

[0197] establish a physical simulation model of the natural gas pipeline network according to the natural gas pipeline network topology data and the design parameter data;

[0198] perform steady-state simulation of the natural gas pipeline network based on the physical simulation model;

[0199] perform non-steady-state simulation of the natural gas pipeline network after failure of each natural gas pipeline network unit using the physical simulation model based on the steady-state simulation result;

[0200] determine the system gas shortage of the natural gas pipeline network within the corresponding allowed repair time of each natural gas pipeline network unit according to the non-steady-state simulation result of the natural gas pipeline network after failure of the natural gas pipeline network unit;

[0201] calculate the system gas shortage loss cost using a system loss model according to the system gas shortage of each natural gas pipeline network unit; the system loss model represents a mapping relationship between the system gas shortage of the natural gas pipeline network and the loss cost.

[0202] In some embodiments, the third determining module 503 can be specifically configured to:

[0203] obtain failure rate data and repair rate data of each natural gas pipeline network unit;

[0204] calculate the running state probability of each natural gas pipeline network unit at each time in the current evaluation period according to the failure rate data and the repair rate data;

[0205] obtain the running reliability of each natural gas pipeline network unit in the current evaluation period by fusing the running state probability of the natural gas pipeline network unit at each time in the current evaluation period;

[0206] obtain the total gas demand of the natural gas pipeline network in the current evaluation period;

[0207] The gas supply reliability of the natural gas pipeline network in the current evaluation period is determined based on the operational reliability of each natural gas pipeline unit and the total gas demand of the natural gas pipeline network.

[0208] In some embodiments, the natural gas pipeline unit includes a plurality of pipeline units and at least one compressor station unit.

[0209] Based on this, the third determining module 503 mentioned above can also be used for:

[0210] Based on the failure rate data and maintenance rate data, the probability of the operating state of each pipeline unit at each moment within the current evaluation period is calculated using the following formula:

[0211] ;

[0212] In the formula, For the first Each pipe section unit The probability of normal operation at any given time; For the first Each pipe section unit The probability of being in a constantly failing state; For the first The length of each pipe segment unit, in km; For the first Failure rate of a single pipe section unit, unit: 1 / (km·h); For the first The maintenance rate of each pipe section unit, in units of 1 / h, is expressed as: ;

[0213] Based on the failure rate data and maintenance rate data, the probability of the operating state of each compressor station unit at each moment within the current evaluation period is calculated using the following formula:

[0214] ;

[0215] In the formula, For the first Each compressor station unit is in The probability of normal operation at any given time; For the first Each compressor station unit is in The probability of being in a constantly failing state; For the first Failure rate of each compressor station unit, in units of 1 / h; For the first Maintenance rate of each compressor station unit, in units of 1 / h.

[0216] In some embodiments, the natural gas pipeline unit includes a plurality of pipeline units and at least one compressor station unit.

[0217] The aforementioned third determining module 503 can also be used for:

[0218] The operational reliability of each pipeline unit in the current evaluation period is obtained by fusing the operational state probabilities of each pipeline unit at each moment within the current evaluation period using the following formula:

[0219] ;

[0220] In the formula, For the first Each pipe section unit The probability of normal operation at any given time; For the first The operational reliability of each pipeline unit during the current evaluation period; For the first The length of each pipe segment unit, in km; For the first Failure rate of a single pipe section unit, unit: 1 / (km·h); For the first Maintenance rate of each pipe section unit, unit: 1 / h; The duration of the current evaluation period;

[0221] The operational reliability of each compressor station unit in the current evaluation period is obtained by fusing the operational state probabilities of each unit at each moment within the current evaluation period using the following formula:

[0222] ;

[0223] In the formula, For the first The operational reliability of each compressor station unit during the current evaluation period; For the first Each compressor station unit is in The probability of normal operation at any given time; For the first Failure rate of each compressor station unit, in units of 1 / h; For the first Maintenance rate of each compressor station unit, unit: 1 / h; This represents the duration of the current evaluation period.

[0224] In some embodiments, the natural gas pipeline unit includes a plurality of pipeline units and at least one compressor station unit.

[0225] The aforementioned third determining module 503 can also be used for:

[0226] Based on the operational reliability of each natural gas pipeline unit and the total gas demand of the natural gas pipeline network, the gas supply reliability of the natural gas pipeline network in the current evaluation period is determined using the following formula:

[0227] ;

[0228] In the formula, The reliability of gas supply from the natural gas pipeline network during the current evaluation period; For the first The operational reliability of each unit during the current evaluation period; This represents the total number of natural gas pipeline network units. This represents the system gas shortage of the natural gas pipeline network within the allowable maintenance and repair time corresponding to the first natural gas pipeline network unit. This represents the total gas demand of the natural gas pipeline network during the current evaluation period. This represents the duration of the current evaluation period.

[0229] In some embodiments, the fourth determining module 505 described above can also be used for:

[0230] The total loss cost of the natural gas pipeline network is determined based on the unit maintenance and repair costs and the system gas shortage loss costs.

[0231] Determine the maintenance and emergency repair time range for each natural gas pipeline unit;

[0232] An optimization model is constructed with the goal of minimizing the total loss cost of the natural gas pipeline network, and with the constraints that the gas supply reliability is not lower than the target reliability and the maintenance and repair time interval of each natural gas pipeline network unit.

[0233] Compared with the prior art, the natural gas pipeline network unit maintenance time determination device provided by the embodiments of the present specification can quantify the maintenance cost of each unit, the system gas shortage loss caused by the failure of each unit, and the specific influence of each unit on the system reliability, and can globally and collaboratively analyze all units in a unified optimization model. The problems of unreasonable resource allocation and suboptimal decision-making caused by simple rules such as repair first or nearest dispatch can be fundamentally overcome, so that a comprehensive maintenance plan that truly meets the optimal interests of the entire pipeline network system can be developed. In addition, by accurately quantifying the parameters such as maintenance cost, gas shortage loss cost, and gas supply reliability, a decision-making system based on data driving and model simulation is established. This computable and comparable quantitative analysis method significantly reduces the uncertainty and subjective randomness in the decision-making process, ensuring that the decision-making conclusion has higher objectivity and credibility. The final output is the optimal maintenance time customized for each pipeline network unit. Since this result is obtained through multi-objective optimization calculation, it naturally combines the dual requirements of resource cost control and system safety guarantee, ensuring that each maintenance time instruction reflects the consideration of the global optimal system, and has significant engineering application value. Finally, by taking the minimization of the total cost as the optimization objective, and taking the gas supply reliability not less than the target value as a hard constraint, the relationship between resource cost and safety is effectively balanced: blind repair without considering resource cost is avoided, and short-sighted behavior of sacrificing safety to save resource cost is also prevented, so that the optimal maintenance decision of resource cost is realized on the premise of ensuring gas supply safety.

[0234] The embodiment of the present specification further provides a computer device for determining maintenance and repair time of a natural gas pipeline network unit, comprising a processor and a memory for storing executable instructions of the processor, and the processor, when implemented, can perform the following tasks according to the instructions: determining a unit maintenance and repair cost of each natural gas pipeline network unit according to the allowable maintenance and repair time of the unit; determining a system gas shortage loss cost caused by each natural gas pipeline network unit after failure under non-steady state conditions; determining a gas supply reliability of the natural gas pipeline network according to the operation reliability of each natural gas pipeline network unit; constructing an optimization model with the objective of minimizing the unit maintenance and repair cost and the system gas shortage loss cost and the constraint of the gas supply reliability being not lower than a target reliability; and determining an optimal maintenance and repair time of each natural gas pipeline network unit according to the optimization model.

[0235] In order to more accurately complete the above instructions, referring to Figure 6 The embodiment of the present specification further provides another specific computer device 600, wherein the computer device 600 comprises a network communication port 601, a processor 602 and a memory 603, and the above structures are connected through internal cables so that the structures can specifically interact with each other.

[0236] The processor 602 can be specifically used for: determining a unit maintenance and repair cost of each natural gas pipeline network unit according to the allowable maintenance and repair time of the unit; determining a system gas shortage loss cost caused by each natural gas pipeline network unit after failure under non-steady state conditions; determining a gas supply reliability of the natural gas pipeline network according to the operation reliability of each natural gas pipeline network unit; constructing an optimization model with the objective of minimizing the unit maintenance and repair cost and the system gas shortage loss cost and the constraint of the gas supply reliability being not lower than a target reliability; and determining an optimal maintenance and repair time of each natural gas pipeline network unit according to the optimization model.

[0237] The memory 603 can be specifically used for storing corresponding instruction programs.

[0238] In the embodiment, the network communication port 601 can be a virtual port bound with different communication protocols, so as to send or receive different data. For example, the network communication port can be a port responsible for web data communication, can also be a port responsible for FTP data communication, and can also be a port responsible for mail data communication. In addition, the network communication port can also be an entity communication interface or a communication chip. For example, it can be a wireless mobile network communication chip such as GSM, CDMA, etc.; it can also be a Wifi chip; and it can also be a Bluetooth chip.

[0239] In this embodiment, the processor 602 can be implemented in any suitable manner. For example, the processor can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers, etc. This specification is not limiting.

[0240] In this embodiment, the memory 603 includes volatile memory and non-volatile memory. The memory 603 can include multiple layers. In digital systems, anything that can store binary data can be a memory; in integrated circuits, a circuit with storage function but no physical form is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0241] This specification also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements... Figure 1 The method shown.

[0242] This specification also provides a computer program product, including at least one instruction or at least one program segment, wherein the at least one instruction or the at least one program segment is loaded and executed by a processor to achieve the following: Figure 1 The method shown.

[0243] It should be understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0244] It should also be understood that, in the embodiments of this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this specification generally indicates that the preceding and following related objects have an "or" relationship.

[0245] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, the methods can be tangibly embodied in a machine-readable storage medium having stored thereon instructions that can be used to program a computer to perform any of the methods. The software implementation can be initialized by loading and executing a set of instructions arranged to perform one of the methods into the computer's memory. Alternatively, hard-wired circuitry can be used in place of, or in combination with, software instructions. Thus, the

[0246] The present application is described in reference to the flowchart and / or block diagrams of the methods, apparatus (systems) and computer program products according to embodiments of the present application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks.

[0247] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks.

[0248] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational tasks to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide tasks that implement the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks. ​ one or more functions specified in one or more of the flowchart and / or block diagram block or blocks.

[0249] The specific embodiments described above have been disclosed by way of example and that, obviously, any modifications and / or alterations to the described embodiments are conceivable to the skilled in the art falls within the scope of the present application. Although the present application has been described in detail with reference to particular implementations, it is not intended to limit or restrict the application to the specific form or form of implementation described. For example, the application is not intended to be limited only to implementations in which the functions can be implemented in hardware and / or software. Rather, the application is meant to encompass a variety of implementations within the scope of the appended claims.

Claims

1. A method for determining the maintenance and repair time of a natural gas pipeline network unit, characterized by, The method comprises the following steps: determining the unit maintenance and repair cost of each natural gas pipeline network unit according to the allowable maintenance and repair time of each natural gas pipeline network unit; determining the system gas shortage loss cost of each natural gas pipeline network unit according to the system gas shortage amount caused by the failure of each natural gas pipeline network unit under non-steady state conditions; determining the gas supply reliability of the natural gas pipeline network according to the operation reliability of each natural gas pipeline network unit, comprising: obtaining the failure rate data and the maintenance rate data of each natural gas pipeline network unit; the natural gas pipeline network unit comprises a plurality of pipeline units and at least one compressor station unit; The failure rate data represent the probability of failure of a natural gas pipeline network unit in a unit of time, and the repair rate data is the inverse of the repair time, representing the probability of repair of a failed unit in a unit of time; according to the failure rate data and the repair rate data, the running state probability of each pipeline unit and compressor station unit at each moment in the current evaluation period is calculated: ; wherein, and are the probability of normal operation and the probability of failure of the first pipeline unit at moment, respectively; , and are the length, failure rate and repair rate of the first pipeline unit, respectively; and are the probability of normal operation and the probability of failure of the first compressor station unit at moment, respectively; and are the failure rate and repair rate of the first compressor station unit, respectively; the running state probability of each natural gas pipeline network unit at each moment in the current evaluation period is fused to obtain the running reliability of the natural gas pipeline network unit in the current evaluation period; the total gas demand of the natural gas pipeline network in the current evaluation period is obtained; according to the running reliability of each natural gas pipeline network unit and the total gas demand of the natural gas pipeline network, the gas supply reliability of the natural gas pipeline network in the current evaluation period is determined: ; wherein, is the gas supply reliability of the natural gas pipeline network in the current evaluation period; and are the running reliability of the first natural gas pipeline network unit and the system gas shortage of the natural gas pipeline network within the corresponding allowed repair time, respectively; is the total number of natural gas pipeline network units; is the total gas demand of the natural gas pipeline network in the current evaluation period; building an optimization model by taking the minimization of the unit maintenance and repair cost and the system gas shortage loss cost as the target and taking the gas supply reliability being not lower than the target reliability as the constraint; determining the optimal maintenance and repair time after the failure of each natural gas pipeline network unit according to the optimization model.

2. The method of claim 1, wherein, The method further comprises: determining the allowable maintenance and repair time after the failure of each natural gas pipeline network unit according to the maintenance and repair resource distribution data and the maintenance and repair resource allocation constraint data of the natural gas pipeline network.

3. The method of claim 1, wherein, The method of determining the unit maintenance and repair cost of each natural gas pipeline network unit according to the allowable maintenance and repair time of each natural gas pipeline network unit comprises: calculating the unit maintenance and repair cost of each natural gas pipeline network unit by using a unit loss model according to the allowable maintenance and repair time of each natural gas pipeline network unit; the unit loss model is used to represent the mapping relationship between the maintenance and repair time and the maintenance and repair cost of the natural gas pipeline network unit.

4. The method according to claim 3, wherein the construction of the unit loss model comprises: constructing the unit loss model of the pipeline unit as follows: ； in, For the first Unit maintenance and emergency repair costs for each pipeline unit; For the first Basic maintenance cost of a single piping unit; For the first Time penalty coefficient for each pipeline unit; For the first Cost attenuation rate coefficient for each pipeline unit; For the first Allowable maintenance and repair time for each pipeline unit; constructing the unit loss model of the compressor station unit as follows: ； wherein, is the unit repair cost for the nth compressor station unit; is the basic repair cost for the nth compressor station unit; is the fixed additional cost for the nth compressor station unit; is the time compression penalty factor for the nth compressor station unit; is the allowed repair time for the nth compressor station unit; is the shortest achievable repair time for the nth compressor station unit; is the time compression unit.​​​​​​ 5. The method of claim 1, wherein, The method of determining the system gas shortage loss cost of each natural gas pipeline network unit according to the system gas shortage amount caused by the failure of each natural gas pipeline network unit under non-steady state conditions comprises: establishing a physical simulation model of the natural gas pipeline network according to the topological structure data and the design parameter data of the natural gas pipeline network; performing steady state simulation of the natural gas pipeline network based on the physical simulation model; performing non-steady state simulation of the natural gas pipeline network after the failure of each natural gas pipeline network unit by using the physical simulation model based on the steady state simulation result; determining the system gas shortage amount of the natural gas pipeline network within the corresponding allowable maintenance and repair time of each natural gas pipeline network unit after the failure of the natural gas pipeline network unit according to the non-steady state simulation result of the natural gas pipeline network after the failure of each natural gas pipeline network unit; calculating the system gas shortage loss cost of each natural gas pipeline network unit by using a system loss model according to the corresponding system gas shortage amount of each natural gas pipeline network unit; the system loss model represents the mapping relationship between the system gas shortage amount and the loss cost of the natural gas pipeline network.

6. The method according to claim 1, wherein the method of fusing the operation state probability of each natural gas pipeline network unit at each time point in the current evaluation period to obtain the operation reliability of the natural gas pipeline network unit in the current evaluation period comprises: fusing the operation state probability of each pipeline unit at each time point in the current evaluation period by using the following formula to obtain the operation reliability of the pipeline unit in the current evaluation period: ； In the formula, is the probability of normal operation of the first pipe section unit at the time instant t; is the probability of normal operation of the first pipe section unit at the time instant t; is the operation reliability of the first pipe section unit in the current evaluation period; is the operation reliability of the first pipe section unit in the current evaluation period; is the length of the first pipe section unit, in units of km; is the length of the first pipe section unit, in units of km; is the failure rate of the first pipe section unit, in units of 1 / (km·h); is the failure rate of the first pipe section unit, in units of 1 / (km·h); is the maintenance rate of the first pipe section unit, in units of 1 / h; is the maintenance rate of the first pipe section unit, in units of 1 / h; is the time length of the current evaluation period;​ fusing the operation state probability of each compressor station unit at each time point in the current evaluation period by using the following formula to obtain the operation reliability of the compressor station unit in the current evaluation period: ； In the formula, For the first The operational reliability of each compressor station unit during the current evaluation period; For the first Each compressor station unit is in The probability of normal operation at any given time; For the first Failure rate of each compressor station unit, in units of 1 / h; For the first Maintenance rate of each compressor station unit, in units of 1 / h; This represents the duration of the current evaluation period.

7. The method of claim 1, wherein, The optimization model is constructed by taking minimization of the unit maintenance and repair cost and the system gas shortage loss cost as an objective and taking the gas supply reliability not being lower than the target reliability as a constraint, and includes: The total loss cost of the natural gas pipeline network is determined according to the unit maintenance and repair cost and the system gas shortage loss cost; The maintenance and repair time interval of each natural gas pipeline network unit is determined; The optimization model is constructed by taking minimization of the total loss cost of the natural gas pipeline network as an objective and taking the maintenance and repair time interval of each natural gas pipeline network unit and the gas supply reliability not being lower than the target reliability as constraints.

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