A method for optimizing the layout of complex natural gas pipeline networks coupled with hydraulic conditions

Abstract

The present invention provides a method for optimizing the layout of a natural gas complex pipeline network coupled with hydraulic conditions, the method comprising the following steps: obtaining basic data of the natural gas pipeline network; constructing an objective function of an optimization model for the layout of a natural gas complex pipeline network coupled with hydraulic conditions; generating model constraints, and establishing an optimization model for the layout of a natural gas complex pipeline network in combination with the objective function; nonlinearly processing the optimization model for the layout of a natural gas complex pipeline network coupled with hydraulic conditions, and using an artemisinin optimization algorithm to solve the model to obtain an optimal layout plan for the complex pipeline network. Based on coupled hydraulics, the present invention comprehensively considers the two structures of star-shaped and star-branched structures, and proposes a method for optimizing the layout of a natural gas pipeline network, which can effectively realize the layout optimization, station capacity determination, and pipeline type configuration of a complex pipeline network, greatly reduce the construction cost of a natural gas pipeline network, and improve the feasibility and economy of the layout plan.

Description

Technical Field

[0001] The present invention relates to the field of complex natural gas pipeline network layout optimization, and in particular to a complex natural gas pipeline network layout optimization method coupled with hydraulic conditions. Background Art

[0002] Under the background of "dual carbon", China's natural gas consumption has grown rapidly and natural gas production has increased year by year. In the process of energy transformation under the "dual carbon" goal, "reducing coal, stabilizing oil, increasing gas and renewable energy" has become a consensus. Vigorously developing natural gas is an inevitable choice for establishing a clean, low-carbon, smart, efficient, economical and safe energy system. As an important part of the pipeline gas transmission system, the ground gathering and transmission pipeline network plays an important role in connecting the upstream gas source and the first station for external transmission from the mine.

[0003] The current research mainly considers discrete characteristics and conducts research on the optimization of the gathering and transportation pipeline network layout based on the hierarchical optimization strategy. The original layout optimization problem is divided into sub-problems such as well group division optimization, gas gathering station site optimization, gathering and transportation pipeline network connection mode optimization, and gathering and transportation pipeline network parameter optimization. The best solution to the original problem is obtained by coordinating the optimal solutions of each sub-problem. However, although the hierarchical optimization strategy considers the overall optimization of the pipeline network layout to some extent, it artificially cuts off the connection between the sub-problems of pipeline network topology layout optimization, making it difficult to effectively combine multiple sub-problems, resulting in the final solution not necessarily being the optimal solution. In addition, the hydraulic characteristics of the natural gas gathering and transportation pipeline network are necessary conditions to ensure the safety of subsequent operation and should also be considered, including nonlinear terms such as flow and pressure.

[0004] Therefore, it is urgent to comprehensively consider the optimization of pipeline network topology layout, site capacity optimization, pipe diameter parameter optimization and hydraulic characteristics, and propose an overall optimization model to effectively reduce the construction cost of the gathering and transportation pipeline network and improve its adaptability. Summary of the invention

[0005] The present invention provides a method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions, the method comprising:

[0006] S1: Obtain basic data of natural gas pipeline network;

[0007] S2: Construct the objective function of the optimization model for the layout of a complex natural gas pipeline network coupled with hydraulic conditions;

[0008] S3: Generate model constraints and establish a natural gas complex pipeline network layout optimization model based on the objective function;

[0009] S4: A nonlinear optimization model for the layout of a natural gas complex pipeline network coupled with hydraulic conditions is used to solve the model using the artemisinin optimization algorithm to obtain the optimal layout plan for the complex pipeline network.

[0010] Furthermore, the basic data in step S1 include geographic information parameters, type parameters, cost parameters, gas gathering station parameters and operation parameters;

[0011] The geographical location parameters include wellhead coordinates, gas production, number of wells, and well spacing;

[0012] The type parameters include gas gathering station type and quantity set, pipeline specification and quantity set;

[0013] The cost parameters include the construction cost of the central processing plant, the construction cost of different types of gas gathering stations, and the construction cost per unit distance of different pipeline specifications;

[0014] The gas gathering station parameters include the maximum processing capacity and number of connected wells of different gas gathering station types;

[0015] The operating parameters include the central processing plant inlet pressure, the maximum wellhead back pressure, the operating pressure range, and the pressure drop equation correlation coefficient.

[0016] Furthermore, the objective function described in step S2 is to minimize the total cost of the natural gas complex pipeline network, which is composed of the gas production pipeline cost, the gas gathering pipeline cost, the gas gathering station cost and the central processing plant cost, and the relationship is:

[0017] min F=F gep +F gcp +F s +F c

[0018] Where, F is the total cost of natural gas gathering and transportation pipeline network; F gep is the gas pipeline cost; F gcp is the gas gathering pipeline cost; F s is the cost of the gas gathering station; F c for the central treatment plant costs;

[0019] The gas production pipeline cost is the sum of the pipeline costs from the wellhead to the gas gathering station. The gas gathering station includes ordinary gas gathering stations and intermediate gas gathering stations. The relationship is:

[0020]

[0021] Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr i,j,d is the unit construction cost of laying a pipeline of specification d from wellhead i to gas gathering station j; L i,j Dl is the pipeline distance from wellhead i to gas gathering station j; i,k,d is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pri,k,d is the unit construction cost of laying a pipeline of specification d from wellhead i to intermediate gas gathering station k; L i,k is the pipeline distance from wellhead i to intermediate gas gathering station k;

[0022] The gas gathering pipeline cost is the sum of the pipeline costs connecting the gas gathering station to the gas gathering station or the central processing plant, and the relationship is:

[0023]

[0024] In the formula, Cl j,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the gas gathering station j and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; j,s,d is the unit construction cost of laying a pipeline of specification d from gas gathering station j to central processing plant s; L j,s is the pipeline distance from gas gathering station j to central processing plant s; Tl j,k,d Kl is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a specification d pipeline, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection. If the intermediate gas gathering station k and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr j,k,d is the unit construction cost of laying a pipeline with specification d from ordinary gas gathering station j to intermediate gas gathering station k; pr k,s,d is the unit construction cost of laying a pipeline of specification d from the intermediate gas gathering station k to the central processing plant s; L j,k is the pipeline distance from the common gas gathering station j to the intermediate gas gathering station k; L k,s is the pipeline distance from the intermediate gas gathering station k to the central processing plant s;

[0025] The gas gathering station cost is the sum of the costs of all types of gas gathering stations established, and the relationship is:

[0026]

[0027] In the formula, Sd j,t is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; pr t Kd is the construction cost of type t gas gathering station; k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0;

[0028] The central treatment plant cost is the sum of the costs of establishing the central treatment plant, and the relationship is:

[0029]

[0030] In the formula, Cd s is a binary variable for the location of the central treatment plant. If the central treatment plant is located in s, the value is 1, otherwise the value is 0; pr s The construction cost of the central treatment plant.

[0031] Furthermore, the constraints described in step S3 include pipeline network structure constraints, pipeline network flow constraints, gas gathering station well number constraints and pipeline network pressure constraints;

[0032] The pipe network structure constraints include constraints related to wellhead connection uniqueness, central processing plant quantity and site selection constraints, gas gathering station type and site selection constraints, star-shaped gas gathering pipeline connection relationship constraints, branch-shaped gas gathering pipeline connection relationship constraints, well-station affiliation constraints, and station-plant affiliation constraints;

[0033] The wellhead connection uniqueness constraint stipulates that any wellhead can only be connected to one gas gathering station by a pipeline of one specification, and the relationship is:

[0034]

[0035] The number and location constraints of the central processing plants stipulate that there is only one central processing plant in the natural gas gathering and transportation pipeline network, and the relationship is:

[0036]

[0037] The gas-gathering station type and site selection constraints stipulate that any gas-gathering station can only be a common gas-gathering station or an intermediate gas-gathering station, and at most only one type can be selected, and the relationship is:

[0038]

[0039] When the pipeline network topology is star-shaped, the star-shaped gas collection pipeline connection relationship constraint stipulates that the connection of the gas collection pipeline is a non-ring structure. Therefore, the number of gas collection pipelines should be equal to the sum of the number of various types of gas collection stations connected to the central processing plant. The relationship is:

[0040]

[0041] When the network topology is star-branched, the branch-shaped gas gathering pipeline connection constraint stipulates that the connection of the gas gathering pipeline is a non-ring structure. Therefore, the number of gas gathering pipelines should be equal to the sum of the number of gas gathering stations of various types established. The connection of the gas gathering pipeline is a branch structure. Therefore, the number of intermediate gas gathering stations should be greater than or equal to 1, and when an intermediate gas gathering station exists, there are at least two gas gathering pipelines. When an ordinary gas gathering station j exists, there is only one gas gathering pipeline, and the ordinary gas gathering station established at the same location as the central processing plant has only one specification of pipeline selected. The relationship is:

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048] The well station affiliation constraint stipulates that only when the ordinary gas gathering station j or the intermediate gas gathering station k exists, the wellhead i can be connected to the ordinary gas gathering station j or the intermediate gas gathering station k by a pipeline of specification d, that is, when the gas gathering station does not exist, the gas production pipeline must not exist, which means that the binary variable of the connection between the wellhead i and the ordinary gas gathering station j or the intermediate gas gathering station k by a pipeline of specification d must be less than or equal to the binary variables of the location and type of the gas gathering station, and the relationship is:

[0049]

[0050]

[0051] Similarly, only when a gas-gathering station exists can the gas-gathering station be connected to the gas-gathering station or central processing plant by a pipeline of specification d. That is, when the gas-gathering station does not exist, the gas-gathering pipeline must not exist. This means that the binary variable of the connection between the gas-gathering station and the gas-gathering station or central processing plant by a pipeline of specification d must be less than or equal to the binary variables of the location and type of the gas-gathering station. The relationship is:

[0052]

[0053]

[0054]

[0055]

[0056] When the central processing plant s exists, the ordinary gas gathering station j or the intermediate gas gathering station k can be connected to the central processing plant s by a pipeline with specification d, that is, when the central processing plant does not exist, the gas gathering pipeline must not exist, which means that the binary variable of the connection between the gas gathering station and the central processing plant by a pipeline with specification d must be less than or equal to the binary variable Cd for the location of the central processing plant. s , the relationship is:

[0057]

[0058]

[0059] The station-plant affiliation constraint mentioned above takes into account the discrete spatial characteristics of facility location. A central processing plant s can only be established here when a gas gathering station j exists. The relationship is:

[0060]

[0061] The pipeline network flow constraints include the gas gathering station and central processing plant node flow balance constraints, gas production pipeline and gas gathering pipeline flow balance constraints, gas production pipeline and gas gathering pipeline flow range constraints, gas gathering station capacity constraints;

[0062] The node flow balance constraint of the gas gathering station stipulates that the node flow of the gas gathering station is equal to the sum of the gas production of the wellheads belonging to the gas gathering station. When the pipeline network topology is star-shaped, the relationship is:

[0063]

[0064] In the formula, q i is the gas production of wellhead i; q j is the node flow of gas gathering station j;

[0065] When the pipe network topology is star-branched, the relationship is:

[0066]

[0067]

[0068]

[0069]

[0070] In the formula, q k is the node flow of the intermediate gas gathering station k; M is a sufficiently large number;

[0071] The central processing plant node flow balance constraint stipulates that the flow into the central processing plant is equal to the sum of all wellhead gas production, and the relationship is:

[0072]

[0073] In the formula, q s is the node flow of the central processing plant s;

[0074] The gas pipeline flow balance constraint stipulates that the gas pipeline flow is equal to the gas production of the wellhead connected to the gas pipeline, and the relationship is:

[0075]

[0076]

[0077] In the formula, Qi,j is the pipeline flow from wellhead i to gas gathering station j; Q i,k is the pipeline flow from wellhead i to intermediate gas gathering station k;

[0078] The gas gathering pipeline flow balance constraint stipulates that the gas gathering pipeline flow is equal to the node flow of the gas gathering station connected to the gas gathering pipeline. When the pipeline network topology is star-shaped, the relationship is:

[0079]

[0080] In the formula, Q j,s is the pipeline flow from gas gathering station j to central processing plant s;

[0081] When the pipe network topology is star-branched, the relationship is:

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] In the formula, Q j,k is the pipeline flow from ordinary gas gathering station j to intermediate gas gathering station k; Q k,s is the pipeline flow from the intermediate gas gathering station k to the central processing plant s;

[0089] The gas pipeline flow range constraint stipulates that the gas pipeline flow rate should meet the requirements of the economic flow range, that is, the gas pipeline flow rate should be within the flow allowable range of the selected specification d pipeline, and the relationship is:

[0090]

[0091]

[0092] In the formula, Q dmin is the lower limit of economic flow rate of pipeline with specification d; Q dmax is the upper limit of economic flow rate for pipeline with specification d;

[0093] The gas collection pipeline flow range constraint stipulates that the gas collection pipeline flow must be within the economic flow range allowed by the selected specification d pipeline, and the relationship is:

[0094]

[0095]

[0096]

[0097] The gas-gathering station capacity constraint stipulates that the node flow of any gas-gathering station must be less than or equal to the maximum processing capacity allowed by the selected type t gas-gathering station. When the pipeline network topology is star-shaped, the relationship is:

[0098]

[0099] In the formula, Q tmax The maximum processing capacity allowed for a type t gas gathering station;

[0100] When the pipe network topology is star-branched, the relationship is:

[0101]

[0102]

[0103] The gas gathering station well number constraint stipulates that the number of wellheads connected to any gas gathering station must be less than or equal to the maximum number of wellheads allowed to be connected to the type t gas gathering station, and the relationship is:

[0104]

[0105]

[0106] Where M tmax The maximum number of wellheads allowed to be connected to a type t gas gathering station;

[0107] The pipe network pressure constraints include the central processing plant inlet pressure constraints, operating pressure range constraints, and hydraulic pressure drop equations for gas production pipelines and gas gathering pipelines;

[0108] The central processing plant inlet pressure constraint stipulates that when optimizing the design of the ground gathering and transportation system, it is necessary to ensure that the pressure at the end of the gas gathering pipeline connected to the central processing plant meets the central processing plant inlet pressure requirement. The relationship is:

[0109]

[0110]

[0111] Where P ctmin is the minimum inlet pressure of the central treatment plant; P j,s is the terminal pressure of the gas gathering pipeline from gas gathering station j to central processing plant s; P k,s is the terminal pressure of the gas gathering pipeline from the intermediate gas gathering station k to the central processing plant s;

[0112] The operating pressure range constraint stipulates that the node pressure of each wellhead, gas gathering station and central processing plant should be limited to a safe range, neither exceeding the maximum operating pressure nor falling below the minimum operating pressure; the relationship is:

[0113]

[0114] Where P v is the pressure at node v; It is the minimum operating pressure of the gathering and transportation pipeline network; It is the maximum operating pressure of the gathering and transportation pipeline network;

[0115] The hydraulic pressure drop equation of the gas production pipeline is the hydraulic pressure drop equation of the gas production pipeline from the wellhead to the gas gathering station; the hydraulic pressure drop equation of the gas gathering pipeline is the hydraulic pressure drop equation of the gas gathering pipeline from the gas gathering station to the central processing plant; the relationship is:

[0116]

[0117]

[0118]

[0119]

[0120]

[0121] Where P i is the node pressure at wellhead i; P i,j is the pressure at the end of the gas pipeline from wellhead i to gas gathering station j; P j is the node pressure of gas gathering station j; is the pipe diameter coefficient, λ is the hydraulic friction coefficient of the pipeline; Z is the natural gas compression coefficient; Δ is the relative density of natural gas; T is the average temperature of natural gas; C is a constant, which is 0.0348 under standard conditions; R is the inner diameter corresponding to the pipeline specification d; P i,k is the pressure at the end of the gas pipeline from wellhead i to the intermediate gas gathering station k; P j,k is the pressure at the end of the gas gathering pipeline from the ordinary gas gathering station j to the intermediate gas gathering station k; P k is the node pressure of the intermediate gas gathering station k;

[0122] Furthermore, the natural gas complex pipeline network layout optimization model for coupling hydraulic conditions with nonlinear processing described in step S4 includes gas gathering pipeline flow balance constraints and nonlinear processing of hydraulic pressure drop equations;

[0123] The nonlinear processing of the gas gathering pipeline flow balance constraint adopts discrete variable linearization, and the processing expression is:

[0124]

[0125]

[0126]

[0127]

[0128] Where, CCl j,s Substitution for linearization of discrete variables; is the maximum flow rate of gas gathering station node j, m 3 / d;

[0129] The pipeline pressure drop equation uses piecewise linear approximation to eliminate nonlinear pressure and flow terms. The processing expression is:

[0130]

[0131]

[0132]

[0133]

[0134]

[0135] Where P Q is the approximate value of the square of the starting pressure; P Z is the approximate value of the square value of the pressure at the end of the gas pipeline from wellhead i to gas gathering station j; Q is the approximate value of the square value of the pipeline flow; M is the maximum value; is the minimum flow value of flow interval h in the piecewise linear approximation method, m 3 / d; is the maximum flow value of flow interval h in the piecewise linear approximation method, m 3 / d;Bq h is a binary variable for distinguishing flow intervals. If the flow rate of the gas pipeline from wellhead i to gas gathering station j is within interval h, then Bq h =1, otherwise Bq h =0; l h is the linear square value of the average flow rate in the flow interval h in the piecewise linear approximation.

[0136] Furthermore, the step of solving the model using the artemisinin optimization algorithm described in step S4 includes:

[0137] S401: Assume that the maximum number of iterations is T, the population size is N, and the dimension of the solution space is D. Use a random number sequence to generate the initial artemisinin population matrix. Each element in the matrix represents a feasible solution to the problem and will serve as a search agent for the algorithm to search in the solution space. The expression is:

[0138]

[0139] In the formula, A N,D is the initial artemisinin population matrix; U is the upper bound of the D-dimensional solution space; L is the lower bound of the D-dimensional solution space; R is a random number in the interval (0,1];

[0140] S402: Calculate the fitness of the artemisinin population according to the model objective function, and update the optimal artemisinin population position;

[0141] S403: Generate a random number r in the interval (0,1] 1 , calculate the artemisinin concentration index c and probability coefficient K, and implement a comprehensive elimination strategy. The formula is:

[0142]

[0143]

[0144]

[0145] In the formula, c is the concentration index; K is the probability coefficient; is the updated location of artemisinin population; is the current location of the artemisinin population; It is the optimal position of artemisinin population;

[0146] S404: Generate a random number r in the interval (0,1] 2 and a random number b in the interval (0,N] 1 、b 2 and b 3 , calculate the normalized fitness value F of the artemisinin population norm , if r 2 <F norm , then execute the local clearing strategy, otherwise skip this stage, the formula is:

[0147]

[0148]

[0149] In the formula, is the normalized value of artemisinin population fitness; F i is the fitness of artemisinin population; is the minimum fitness of the artemisinin population; is the maximum fitness of the artemisinin population;

[0150] S405: Generate a random number r in the interval (0,1] 3 , after implementing the post-consolidation strategy, the artemisinin population position update formula is:

[0151]

[0152] S403: Determine whether the algorithm termination condition is met. If so, exit the main loop and output the optimal layout plan for the natural gas complex pipeline network. If not, return to S402 and continue the loop.

[0153] Furthermore, the optimal layout plan of the pipeline network described in step S4 includes the total cost of the complex natural gas pipeline network; the coordinates of the gas gathering station and the central processing plant; the type, capacity and number of gas gathering stations; the connection relationship between the wellhead and the gas gathering station and the pipeline specifications; the connection relationship between the gas gathering station and the central processing plant and the pipeline specifications; and the pipeline node pressure.

[0154] This specification provides a method for optimizing the layout of a complex natural gas pipeline network with coupled hydraulic conditions. Based on coupled hydraulic conditions, this method comprehensively considers the common star-shaped and star-branch structures of complex natural gas pipeline networks, and proposes an optimization method for the layout of a complex natural gas pipeline network for the problems of pipeline network layout, station capacity determination and pipeline configuration. The optimization model established by solving the artemisinin algorithm with strong global search capability and excellent local optimal performance is used to obtain an optimization plan for the layout of a complex natural gas pipeline network that takes into account both economy and safety. The plan covers pipeline network layout, station capacity determination and pipeline configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0155] Figure 1 Flow chart of the present invention

[0156] Figure 2 Flowchart of solving the optimization model for the artemisinin optimization algorithm

[0157] Figure 3 The optimal layout plan for the star-shaped natural gas gathering and transportation pipeline network

[0158] Figure 4 The length and cost of pipelines at each level for the star-shaped layout

[0159] Figure 5 The optimal layout scheme for the star-branch natural gas gathering and transportation pipeline network

[0160] Figure 6 The length and cost of pipelines at each level for the star-branch layout scheme. DETAILED DESCRIPTION

[0161] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0162] like Figure 1 As shown, the present invention provides a method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions, comprising the following steps:

[0163] S1: Obtain basic data of natural gas pipeline network;

[0164] S2: Construct the objective function of the optimization model for the layout of a complex natural gas pipeline network coupled with hydraulic conditions;

[0165] S3: Generate model constraints and establish a natural gas complex pipeline network layout optimization model based on the objective function;

[0166] S4: A nonlinear optimization model for the layout of a natural gas complex pipeline network coupled with hydraulic conditions is used to solve the model using the artemisinin optimization algorithm to obtain the optimal layout plan for the complex pipeline network.

[0167] In one embodiment, the basic data in step S1 includes geographic information parameters, type parameters, cost parameters, gas gathering station parameters and operation parameters;

[0168] The geographical location parameters include wellhead coordinates, gas production, number of wells, and well spacing;

[0169] The type parameters include gas gathering station type and quantity set, pipeline specification and quantity set;

[0170] The cost parameters include the construction cost of the central processing plant, the construction cost of different types of gas gathering stations, and the construction cost per unit distance of different pipeline specifications;

[0171] The gas gathering station parameters include the maximum processing capacity and number of connected wells of different gas gathering station types;

[0172] The operating parameters include the central processing plant inlet pressure, the maximum wellhead back pressure, the operating pressure range, and the pressure drop equation correlation coefficient.

[0173] In one embodiment, the objective function described in step S2 is to minimize the total cost of the natural gas complex pipeline network, which is composed of the gas production pipeline cost, the gas gathering pipeline cost, the gas gathering station cost and the central processing plant cost, and the relationship is:

[0174] min F=F gep +F gcp +F s +F c (1)

[0175] Where, F is the total cost of natural gas gathering and transportation pipeline network; Fgep is the gas pipeline cost; F gcp is the gas gathering pipeline cost; F s is the cost of the gas gathering station; F c for the central treatment plant costs;

[0176] The gas production pipeline cost is the sum of the pipeline costs from the wellhead to the gas gathering station. The gas gathering station includes ordinary gas gathering stations and intermediate gas gathering stations. The relationship is:

[0177]

[0178] Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr i,j,d is the unit construction cost of laying a pipeline of specification d from wellhead i to gas gathering station j; L i,j Dl is the pipeline distance from wellhead i to gas gathering station j; i,k,d is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr i,k,d is the unit construction cost of laying a pipeline of specification d from wellhead i to intermediate gas gathering station k; L i,k is the pipeline distance from wellhead i to intermediate gas gathering station k;

[0179] The gas gathering pipeline cost is the sum of the pipeline costs connecting the gas gathering station to the gas gathering station or the central processing plant, and the relationship is:

[0180]

[0181] In the formula, Cl j,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the gas gathering station j and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; j,s,d is the unit construction cost of laying a pipeline of specification d from gas gathering station j to central processing plant s; L j,s is the pipeline distance from gas gathering station j to central processing plant s; Tl j,k,d Kl is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a specification d pipeline, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection. If the intermediate gas gathering station k and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr j,k,d is the unit construction cost of laying a pipeline with specification d from ordinary gas gathering station j to intermediate gas gathering station k; pr k,s,d is the unit construction cost of laying a pipeline of specification d from the intermediate gas gathering station k to the central processing plant s; L j,kis the pipeline distance from the common gas gathering station j to the intermediate gas gathering station k; L k,s is the pipeline distance from the intermediate gas gathering station k to the central processing plant s;

[0182] The gas gathering station cost is the sum of the costs of all types of gas gathering stations established, and the relationship is:

[0183]

[0184] In the formula, Sd j,t is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; pr t Kd is the construction cost of type t gas gathering station; k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0;

[0185] The central treatment plant cost is the sum of the costs of establishing the central treatment plant, and the relationship is:

[0186]

[0187] In the formula, Cd s is a binary variable for the location of the central treatment plant. If the central treatment plant is located in s, the value is 1, otherwise the value is 0; pr s The construction cost of the central treatment plant.

[0188] In one embodiment, the constraints described in step S3 include pipeline network structure constraints, pipeline network flow constraints, gas gathering station well number constraints, and pipeline network pressure constraints;

[0189] The pipe network structure constraints include constraints related to wellhead connection uniqueness, central processing plant quantity and site selection constraints, gas gathering station type and site selection constraints, star-shaped gas gathering pipeline connection relationship constraints, branch-shaped gas gathering pipeline connection relationship constraints, well-station affiliation constraints, and station-plant affiliation constraints;

[0190] The wellhead connection uniqueness constraint stipulates that any wellhead can only be connected to one gas gathering station by a pipeline of one specification, and the relationship is:

[0191]

[0192] The number and location constraints of the central processing plants stipulate that there is only one central processing plant in the natural gas gathering and transportation pipeline network, and the relationship is:

[0193]

[0194] The gas-gathering station type and site selection constraints stipulate that any gas-gathering station can only be a common gas-gathering station or an intermediate gas-gathering station, and at most only one type can be selected, and the relationship is:

[0195]

[0196] When the pipeline network topology is star-shaped, the star-shaped gas collection pipeline connection relationship constraint stipulates that the connection of the gas collection pipeline is a non-ring structure. Therefore, the number of gas collection pipelines should be equal to the sum of the number of various types of gas collection stations connected to the central processing plant. The relationship is:

[0197]

[0198] When the network topology is star-branched, the branch-shaped gas gathering pipeline connection constraint stipulates that the connection of the gas gathering pipeline is a non-ring structure. Therefore, the number of gas gathering pipelines should be equal to the sum of the number of gas gathering stations of various types established. The connection of the gas gathering pipeline is a branch structure. Therefore, the number of intermediate gas gathering stations should be greater than or equal to 1, and when an intermediate gas gathering station exists, there are at least two gas gathering pipelines. When an ordinary gas gathering station j exists, there is only one gas gathering pipeline, and the ordinary gas gathering station established at the same location as the central processing plant has only one specification of pipeline selected. The relationship is:

[0199]

[0200]

[0201]

[0202]

[0203]

[0204]

[0205] The well station affiliation constraint stipulates that only when the ordinary gas gathering station j or the intermediate gas gathering station k exists, the wellhead i can be connected to the ordinary gas gathering station j or the intermediate gas gathering station k by a pipeline of specification d, that is, when the gas gathering station does not exist, the gas production pipeline must not exist, which means that the binary variable of the connection between the wellhead i and the ordinary gas gathering station j or the intermediate gas gathering station k by a pipeline of specification d must be less than or equal to the binary variables of the location and type of the gas gathering station, and the relationship is:

[0206]

[0207]

[0208] Similarly, only when a gas-gathering station exists can the gas-gathering station be connected to the gas-gathering station or central processing plant by a pipeline of specification d. That is, when the gas-gathering station does not exist, the gas-gathering pipeline must not exist. This means that the binary variable of the connection between the gas-gathering station and the gas-gathering station or central processing plant by a pipeline of specification d must be less than or equal to the binary variables of the location and type of the gas-gathering station. The relationship is:

[0209]

[0210]

[0211]

[0212]

[0213] When the central processing plant s exists, the ordinary gas gathering station j or the intermediate gas gathering station k can be connected to the central processing plant s by a pipeline with specification d, that is, when the central processing plant does not exist, the gas gathering pipeline must not exist, which means that the binary variable of the connection between the gas gathering station and the central processing plant by a pipeline with specification d must be less than or equal to the binary variable Cd for the location of the central processing plant. s , the relationship is:

[0214]

[0215]

[0216] The station-plant affiliation constraint mentioned above takes into account the discrete spatial characteristics of facility location. A central processing plant s can only be established here when a gas gathering station j exists. The relationship is:

[0217]

[0218] The pipeline network flow constraints include the gas gathering station and central processing plant node flow balance constraints, gas production pipeline and gas gathering pipeline flow balance constraints, gas production pipeline and gas gathering pipeline flow range constraints, gas gathering station capacity constraints;

[0219] The node flow balance constraint of the gas gathering station stipulates that the node flow of the gas gathering station is equal to the sum of the gas production of the wellheads belonging to the gas gathering station. When the pipeline network topology is star-shaped, the relationship is:

[0220]

[0221] In the formula, q i is the gas production of wellhead i; q j is the node flow of gas gathering station j;

[0222] When the pipe network topology is star-branched, the relationship is:

[0223]

[0224]

[0225]

[0226]

[0227] In the formula, q k is the node flow of the intermediate gas gathering station k; M is a sufficiently large number;

[0228] The central processing plant node flow balance constraint stipulates that the flow into the central processing plant is equal to the sum of all wellhead gas production, and the relationship is:

[0229]

[0230] In the formula, q s is the node flow of the central processing plant s;

[0231] The gas pipeline flow balance constraint stipulates that the gas pipeline flow is equal to the gas production of the wellhead connected to the gas pipeline, and the relationship is:

[0232]

[0233]

[0234] In the formula, Q i,j is the pipeline flow from wellhead i to gas gathering station j; Q i,k is the pipeline flow from wellhead i to intermediate gas gathering station k;

[0235] The gas gathering pipeline flow balance constraint stipulates that the gas gathering pipeline flow is equal to the node flow of the gas gathering station connected to the gas gathering pipeline. When the pipeline network topology is star-shaped, the relationship is:

[0236]

[0237] In the formula, Q j,s is the pipeline flow from gas gathering station j to central processing plant s;

[0238] When the pipe network topology is star-branched, the relationship is:

[0239]

[0240]

[0241]

[0242]

[0243]

[0244]

[0245] In the formula, Q j,k is the pipeline flow from ordinary gas gathering station j to intermediate gas gathering station k; Q k,s is the pipeline flow from the intermediate gas gathering station k to the central processing plant s;

[0246] The gas pipeline flow range constraint stipulates that the gas pipeline flow rate should meet the requirements of the economic flow range, that is, the gas pipeline flow rate should be within the flow allowable range of the selected specification d pipeline, and the relationship is:

[0247]

[0248]

[0249] In the formula, Q dmin is the lower limit of economic flow rate of pipeline with specification d; Q dmax is the upper limit of economic flow rate for pipeline with specification d;

[0250] The gas collection pipeline flow range constraint stipulates that the gas collection pipeline flow must be within the economic flow range allowed by the selected specification d pipeline, and the relationship is:

[0251]

[0252]

[0253]

[0254] The gas-gathering station capacity constraint stipulates that the node flow of any gas-gathering station must be less than or equal to the maximum processing capacity allowed by the selected type t gas-gathering station. When the pipeline network topology is star-shaped, the relationship is:

[0255] In the formula, Q tmax The maximum processing capacity allowed for a type t gas gathering station;

[0256] When the pipe network topology is star-branched, the relationship is:

[0257]

[0258]

[0259] The gas gathering station well number constraint stipulates that the number of wellheads connected to any gas gathering station must be less than or equal to the maximum number of wellheads allowed to be connected to the type t gas gathering station, and the relationship is:

[0260]

[0261]

[0262] Where M tmax The maximum number of wellheads allowed to be connected to a type t gas gathering station;

[0263] The pipe network pressure constraints include the central processing plant inlet pressure constraints, operating pressure range constraints, and hydraulic pressure drop equations for gas production pipelines and gas gathering pipelines;

[0264] The central processing plant inlet pressure constraint stipulates that when optimizing the design of the ground gathering and transportation system, it is necessary to ensure that the pressure at the end of the gas gathering pipeline connected to the central processing plant meets the central processing plant inlet pressure requirement. The relationship is:

[0265]

[0266]

[0267] Where P ctmin is the minimum inlet pressure of the central treatment plant; P j,s is the terminal pressure of the gas gathering pipeline from gas gathering station j to central processing plant s; P k,s is the terminal pressure of the gas gathering pipeline from the intermediate gas gathering station k to the central processing plant s;

[0268] The operating pressure range constraint stipulates that the node pressure of each wellhead, gas gathering station and central processing plant should be limited to a safe range, neither exceeding the maximum operating pressure nor falling below the minimum operating pressure; the relationship is:

[0269]

[0270] Where P v is the pressure at node v; It is the minimum operating pressure of the gathering and transportation pipeline network; It is the maximum operating pressure of the gathering and transportation pipeline network;

[0271] The hydraulic pressure drop equation of the gas production pipeline is the hydraulic pressure drop equation of the gas production pipeline from the wellhead to the gas gathering station; the hydraulic pressure drop equation of the gas gathering pipeline is the hydraulic pressure drop equation of the gas gathering pipeline from the gas gathering station to the central processing plant; the relationship is:

[0272]

[0273]

[0274]

[0275]

[0276]

[0277] Where P i is the node pressure at wellhead i; P i,j is the pressure at the end of the gas pipeline from wellhead i to gas gathering station j; P j is the node pressure of gas gathering station j; is the pipe diameter coefficient, λ is the hydraulic friction coefficient of the pipeline; Z is the natural gas compression coefficient; Δ is the relative density of natural gas; T is the average temperature of natural gas; C is a constant, which is 0.0348 under standard conditions; R is the inner diameter corresponding to the pipeline specification d; P i,k is the pressure at the end of the gas pipeline from wellhead i to the intermediate gas gathering station k; P j,k is the pressure at the end of the gas gathering pipeline from the ordinary gas gathering station j to the intermediate gas gathering station k; P k is the node pressure of the intermediate gas gathering station k;

[0278] In one embodiment, the natural gas complex pipeline layout optimization model with nonlinear processing coupled hydraulic conditions described in step S4 includes gas gathering pipeline flow balance constraints and pipeline hydraulic pressure drop equation nonlinear processing;

[0279] The nonlinear processing of the gas gathering pipeline flow balance constraint adopts discrete variable linearization, and the processing expression is:

[0280]

[0281]

[0282]

[0283]

[0284] Where, CCl j,s Substitution for linearization of discrete variables; is the maximum flow rate of gas gathering station node j, m 3 / d;

[0285] The pipeline pressure drop equation uses piecewise linear approximation to eliminate nonlinear pressure and flow terms. The processing expression is:

[0286]

[0287]

[0288]

[0289]

[0290]

[0291] Where P Q is the approximate value of the square of the starting pressure; P Z is the approximate value of the square value of the pressure at the end of the gas pipeline from wellhead i to gas gathering station j; Q is the approximate value of the square value of the pipeline flow; M is the maximum value; is the minimum flow value of flow interval h in the piecewise linear approximation method, m 3 / d; is the maximum flow value of flow interval h in the piecewise linear approximation method, m 3 / d;Bq h is a binary variable for distinguishing flow intervals. If the flow rate of the gas pipeline from wellhead i to gas gathering station j is within interval h, then Bq h =1, otherwise Bq h =0; l h is the linear square value of the average flow rate in the flow interval h in the piecewise linear approximation.

[0292] In one embodiment, if Figure 2 As shown, the steps of solving the model using the artemisinin optimization algorithm described in step S4 include:

[0293] S401: Assume that the maximum number of iterations is T, the population size is N, and the dimension of the solution space is D. Use a random number sequence to generate the initial artemisinin population matrix. Each element in the matrix represents a feasible solution to the problem and will serve as a search agent for the algorithm to search in the solution space. The expression is:

[0294]

[0295] In the formula, A N,D is the initial artemisinin population matrix; U is the upper bound of the D-dimensional solution space; L is the lower bound of the D-dimensional solution space; R is a random number in the interval (0,1];

[0296] S402: Calculate the fitness of the artemisinin population according to the model objective function, and update the optimal artemisinin population position;

[0297] S403: Generate a random number r in the interval (0,1] 1 , calculate the artemisinin concentration index c and probability coefficient K, and implement a comprehensive elimination strategy. The formula is:

[0298]

[0299]

[0300]

[0301] In the formula, c is the concentration index; K is the probability coefficient; is the updated location of artemisinin population; is the current location of the artemisinin population; It is the optimal position of artemisinin population;

[0302] S404: Generate a random number r in the interval (0,1] 2 and a random number b in the interval (0,N] 1 、b 2 and b 3 , calculate the normalized fitness value F of the artemisinin population norm , if r 2 <F norm , then execute the local clearing strategy, otherwise skip this stage, the formula is:

[0303]

[0304]

[0305] In the formula, is the normalized value of artemisinin population fitness; F i is the fitness of artemisinin population; is the minimum fitness of the artemisinin population; is the maximum fitness of the artemisinin population;

[0306] S405: Generate a random number r in the interval (0,1] 3 , after implementing the post-consolidation strategy, the artemisinin population position update formula is:

[0307]

[0308] S403: Determine whether the algorithm termination condition is met. If so, exit the main loop and output the optimal layout plan for the natural gas complex pipeline network. If not, return to S402 and continue the loop.

[0309] In one embodiment, the optimal layout plan of the pipeline network described in step S4 includes the total cost of the complex natural gas pipeline network; the coordinates of the gas gathering station and the central processing plant; the type, capacity and number of gas gathering stations; the connection relationship between the wellhead and the gas gathering station and the pipeline specifications; the connection relationship between the gas gathering station and the central processing plant and the pipeline specifications; and the pipeline network node pressure.

[0310] To further illustrate this method, taking gas field blocks A and B as examples, the optimal layout of the pipeline network with two topological structures, star-shaped and star-branch, is analyzed respectively.

[0311] Block A: Star-shaped pipe network

[0312] The optimal layout of the star-shaped natural gas gathering and transportation pipeline network is as follows: Figure 3The optimization plan includes the construction of 4 gas gathering stations, 20 gas production pipelines and 4 gas gathering pipelines, including 1 type 1 gas gathering station, 1 type 2 gas gathering station, 2 type 3 gas gathering stations, 11 specification 1 pipelines, 9 specification 2 pipelines, 1 specification 3 pipeline, 1 specification 4 pipeline and 2 specification 5 pipelines; the central processing plant is located at 8 well sites.

[0313] The length and cost of pipelines at all levels are as follows: Figure 4 The total length of the gathering and transportation pipeline network is 14,083.56 m, of which the gas production pipeline accounts for a high proportion of 74.6%; the total cost is 371.95 million yuan, of which the pipeline cost is 6.9484 million yuan and the gas gathering station cost is 65 million yuan.

[0314] Block B: Star-branch pipe network

[0315] The optimal layout scheme of the star-shaped natural gas gathering and transportation pipeline network is as follows Figure 5 The optimization plan includes the construction of 5 gas gathering stations, 13 gas production pipelines and 4 gas gathering pipelines, including 3 type 1 gas gathering stations, 1 type 2 gas gathering station, 1 type 3 gas gathering station, 7 specification 1 pipelines, 6 specification 2 pipelines, 2 specification 3 pipelines and 2 specification 5 pipelines; the central processing plant is located at 16 well sites.

[0316] The length and cost of pipelines at all levels are as follows: Figure 6 The lengths of the gas production pipeline and the gas gathering pipeline are 16805.17m and 14144.02m respectively, and the pipe lengths are 9023.55m, 7781.62m, 6372.05m and 7771.97m respectively; the total cost of the pipeline network is 373.87 million yuan.

[0317] The above description is only an example of a specific implementation method in this specification and is not intended to limit the embodiments of this specification. For those skilled in the art, the embodiments of this specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of this specification should be included in the scope of the claims of the embodiments of this specification.

Claims

1. A method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions, characterized in that: The following steps are involved: S1: Obtaining basic data of the natural gas pipeline network; the basic data includes geographic information parameters, type parameters, cost parameters, gas gathering station parameters and operation parameters; S2: Constructing the objective function of the natural gas complex pipeline network layout optimization model coupled with hydraulic conditions; the objective function is to minimize the total cost of the natural gas complex pipeline network, which is composed of the gas production pipeline cost, the gas gathering pipeline cost, the gas gathering station cost and the central processing plant cost; S3: Generate model constraints and establish a natural gas complex pipeline network layout optimization model based on the objective function; The model constraints include pipeline network structure constraints, pipeline network flow constraints, gas gathering station well number constraints and pipeline network pressure constraints; The pipe network structure constraints include constraints related to wellhead connection uniqueness, central processing plant quantity and site selection constraints, gas gathering station type and site selection constraints, star-shaped gas gathering pipeline connection relationship constraints, branch-shaped gas gathering pipeline connection relationship constraints, well-station affiliation constraints, and station-plant affiliation constraints; The pipeline network flow constraints include the gas gathering station and central processing plant node flow balance constraints, gas production pipeline and gas gathering pipeline flow balance constraints, gas production pipeline and gas gathering pipeline flow range constraints, gas gathering station capacity constraints; The gas gathering station well number constraint stipulates that the number of wellheads connected to any gas gathering station must be less than or equal to the maximum number of wellheads allowed to be connected to this type of gas gathering station; The pipe network pressure constraints include the central processing plant inlet pressure constraints, operating pressure range constraints, and hydraulic pressure drop equations for gas production pipelines and gas gathering pipelines; S4: A natural gas complex pipeline network layout optimization model with nonlinear processing coupled hydraulic conditions, using the artemisinin optimization algorithm to solve the model and obtain the optimal layout plan for the complex pipeline network; The nonlinear processing coupled hydraulic condition natural gas complex pipeline layout optimization model includes gas gathering pipeline flow balance constraints and pipeline hydraulic pressure drop equation nonlinear processing; The nonlinear processing of the gas gathering pipeline flow balance constraint adopts discrete variable linearization, and the processing expression is: Where, CCl j,s is the replacement term for the linearization of discrete variables; Q j,s is the pipeline flow from gas gathering station j to central processing plant s; is the maximum flow rate of gas gathering station node j; q j is the node flow of gas gathering station j; Cl j,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the gas gathering station j and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; The pipeline pressure drop equation uses piecewise linear approximation to eliminate nonlinear pressure and flow terms. The processing expression is: Where P Q is the approximate value of the square of the starting pressure; P Z is the approximate value of the square value of the pressure at the end of the gas pipeline from wellhead i to gas gathering station j; Q is the approximate value of the square value of the pipeline flow; M is an infinite number; is the minimum flow value of flow interval h in the piecewise linear approximation method, m 3 / d; is the maximum flow value of flow interval h in the piecewise linear approximation method, m 3 / d;Bq h is a binary variable for distinguishing flow intervals. If the flow rate of the gas pipeline from wellhead i to gas gathering station j is within interval h, then Bq h =1, otherwise Bq h =0; is the linear square value of the average flow rate in the flow interval h in the piecewise linear approximation; Bl is the binary variable of the gas pipeline connection.

2. A method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions as claimed in claim 1, characterized in that: The geographical location parameters of step S1 include wellhead coordinates, gas production, number of wells, and well spacing; the type parameters include a set of gas gathering station types and quantities, and a set of pipeline specifications and quantities; the cost parameters include the construction cost of a central processing plant, the construction costs of different types of gas gathering stations, and the construction costs per unit distance of different pipeline specifications; the gas gathering station parameters include the maximum processing capacity and number of connected wells of different gas gathering station types; and the operating parameters include the inlet pressure of the central processing plant, the maximum wellhead back pressure, the operating pressure range, and the correlation coefficient of the pressure drop equation.

3. A method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions as claimed in claim 1, characterized in that: The objective function relational expression in step S2 is: min F=F gep +F gcp +F s +F c Where, F is the total cost of natural gas gathering and transportation pipeline network; F gep is the gas pipeline cost; F gcp is the gas gathering pipeline cost; F s is the cost of the gas gathering station; F c for the central treatment plant costs; The gas production pipeline cost is the sum of the pipeline construction costs from the wellhead to the gas gathering station. The gas gathering station includes ordinary gas gathering stations and intermediate gas gathering stations. The relationship is: Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr i,j,d is the unit construction cost of laying a pipeline of specification d from wellhead i to gas gathering station j; L i,j Dl is the pipeline distance from wellhead i to gas gathering station j; i,k,d is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr i,k,d is the unit construction cost of laying a pipeline of specification d from wellhead i to intermediate gas gathering station k; L i,k is the pipeline distance from wellhead i to intermediate gas gathering station k; The gas gathering pipeline cost is the sum of the pipeline costs connecting the gas gathering station to the gas gathering station or the central processing plant, and the relationship is: In the formula, Cl j,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the gas gathering station j and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; j,s,d is the unit construction cost of laying a pipeline of specification d from gas gathering station j to central processing plant s; L j,s is the pipeline distance from gas gathering station j to central processing plant s; Tl j,k,d Kl is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a specification d pipeline, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection. If the intermediate gas gathering station k and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; pr j,k,d is the unit construction cost of laying a pipeline of specification d from ordinary gas-gathering station j to intermediate gas-gathering station k; pr k,s,d is the unit construction cost of laying a pipeline of specification d from the intermediate gas gathering station k to the central processing plant s; L j,k is the pipeline distance from the common gas gathering station j to the intermediate gas gathering station k; L k,s is the pipeline distance from the intermediate gas gathering station k to the central processing plant s; The gas gathering station cost mentioned above is the sum of the construction costs of various types of gas gathering stations established, and the relationship is: In the formula, Sd j,t is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; pr t Kd is the construction cost of type t gas gathering station; k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0; The central treatment plant cost is the sum of the construction costs of the central treatment plant, and the relationship is: In the formula, Cd s is a binary variable for the location of the central treatment plant. If the central treatment plant is located in s, the value is 1, otherwise the value is 0; pr s The construction cost of the central treatment plant.

4. A method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions as claimed in claim 1, characterized in that: The wellhead connection uniqueness constraint described in step S3 stipulates that any wellhead can only be connected to one gas gathering station by a pipeline of one specification, and the relationship is: Where, Bl i,j,d Dl is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; i,k,d is a binary variable for gas pipeline connection, which takes the value of 1 if the wellhead i and the intermediate gas gathering station k are connected by a pipeline of specification d, otherwise it takes the value of 0; The number and location constraints of the central processing plants stipulate that there is only one central processing plant in the natural gas gathering and transportation pipeline network, and the relationship is: In the formula, Cd s is a binary variable for the location of the central treatment plant, with a value of 1 if the central treatment plant is located at s, otherwise it is 0; The gas-gathering station type and site selection constraints stipulate that any gas-gathering station can only be a common gas-gathering station or an intermediate gas-gathering station, and at most only one type can be selected, and the relationship is: In the formula, Sd j,t Kd is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0. k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0; When the pipeline network topology is star-shaped, the star-shaped gas collection pipeline connection relationship constraint stipulates that the connection of the gas collection pipeline is a non-ring structure. Therefore, the number of gas collection pipelines should be equal to the sum of the number of various types of gas collection stations connected to the central processing plant. The relationship is: In the formula, Cl j,s,d is a binary variable for gas gathering pipeline connection. If the gas gathering station j and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Sd j,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the gas-gathering station is located at j and is of type t, otherwise it is 0; When the network topology is star-branched, the branch-shaped gas gathering pipeline connection relationship constraint stipulates that the connection of the gas gathering pipeline is a non-ring structure, so the number of gas gathering pipelines should be equal to the sum of the number of each type of gas gathering stations established; when the connection of the gas gathering pipeline is a branch structure, the number of intermediate gas gathering stations should be greater than or equal to 1, and when the intermediate gas gathering station exists, at least two gas gathering pipelines exist; When a common gas-gathering station j exists, there is only one gas-gathering pipeline, and when the common gas-gathering station is built at the same location as the central processing plant, there is only one specification of pipeline selected; the relationship is: Where, Tl j,k,d Kl is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a specification d pipeline, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection. If the intermediate gas gathering station k and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Cl j,s,d is a binary variable for gas gathering pipeline connection. If the gas gathering station j and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Sd j,t Kd is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0. k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0; The well station affiliation constraint stipulates that only when the ordinary gas gathering station j or the intermediate gas gathering station k exists, the wellhead i can be connected to the ordinary gas gathering station j or the intermediate gas gathering station k by a pipeline of specification d, that is, when the gas gathering station does not exist, the gas production pipeline must not exist, which means that the binary variable of the connection between the wellhead i and the ordinary gas gathering station j or the intermediate gas gathering station k by a pipeline of specification d must be less than or equal to the binary variables of the location and type of the gas gathering station, and the relationship is: Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Sd j,t Dl is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; i,k,d Kd is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0; Similarly, only when a gas-gathering station exists can the gas-gathering station be connected to the gas-gathering station or central processing plant by a pipeline of specification d. That is, when the gas-gathering station does not exist, the gas-gathering pipeline must not exist. This means that the binary variable of the connection between the gas-gathering station and the gas-gathering station or central processing plant by a pipeline of specification d must be less than or equal to the binary variables of the location and type of the gas-gathering station. The relationship is: Where, Tl j,k,d Sd is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a pipeline of specification d, the value is 1, otherwise the value is 0; j,t is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; Cl j,s,d Kd is a binary variable for gas gathering pipeline connection. If the gas gathering station j and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; k,t Kl is a binary variable for the location and type of the gas-gathering station. If the intermediate gas-gathering station is located at k and is of type t, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the intermediate gas gathering station k and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; When the central processing plant s exists, the ordinary gas gathering station j or the intermediate gas gathering station k can be connected to the central processing plant s by a pipeline with specification d, that is, when the central processing plant does not exist, the gas gathering pipeline must not exist, which means that the binary variable of the connection between the gas gathering station and the central processing plant by a pipeline with specification d must be less than or equal to the binary variable Cd for the location of the central processing plant. s , the relationship is: In the formula, Cl j,s,d Cd is a binary variable for gas gathering pipeline connection. If the gas gathering station j and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; s Kl is a binary variable for the location of the central treatment plant. If the central treatment plant is located at s, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the intermediate gas gathering station k and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; The station-plant affiliation constraint mentioned above takes into account the discrete spatial characteristics of facility location. A central processing plant s can only be established here when a gas gathering station j exists. The relationship is: In the formula, Cd s is a binary variable for the location of the central treatment plant. If the central treatment plant is located at s, the value is 1, otherwise the value is 0; Sd j,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the gas-gathering station is located at j and is of type t, otherwise it is 0; The pipeline network flow constraints include the gas gathering station and central processing plant node flow balance constraints, gas production pipeline and gas gathering pipeline flow balance constraints, gas production pipeline and gas gathering pipeline flow range constraints, gas gathering station capacity constraints; The node flow balance constraint of the gas gathering station stipulates that the node flow of the gas gathering station is equal to the sum of the gas production of the wellheads belonging to the gas gathering station. When the pipeline network topology is star-shaped, the relationship is: Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; i is the gas production of wellhead i; q j is the node flow of gas gathering station j; When the pipe network topology is star-branched, the relationship is: In the formula, q i is the gas production of wellhead i; q j is the node flow of gas gathering station j; q k is the node flow of the intermediate gas gathering station k; M is an infinite number; Bl i,j,d Dl is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; i,k,d is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Sd j,t Kd is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0. k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0; The central processing plant node flow balance constraint stipulates that the flow into the central processing plant is equal to the sum of all wellhead gas production, and the relationship is: In the formula, Cd s is a binary variable for the location of the central treatment plant. If the central treatment plant is located in s, the value is 1, otherwise the value is 0; q i is the gas production of wellhead i; q s is the node flow of the central processing plant s; The gas pipeline flow balance constraint stipulates that the gas pipeline flow is equal to the gas production of the wellhead connected to the gas pipeline, and the relationship is: In the formula, Q i,j is the pipeline flow from wellhead i to gas gathering station j; q i is the gas production of wellhead i; Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Q i,k Dl is the pipeline flow from wellhead i to intermediate gas gathering station k; i,k,d is a binary variable for gas pipeline connection, which takes the value of 1 if the wellhead i and the intermediate gas gathering station k are connected by a pipeline of specification d, otherwise it takes the value of 0; The gas gathering pipeline flow balance constraint stipulates that the gas gathering pipeline flow is equal to the node flow of the gas gathering station connected to the gas gathering pipeline. When the pipeline network topology is star-shaped, the relationship is: In the formula, Q j,s is the pipeline flow from gas gathering station j to central processing plant s; q j is the node flow of gas gathering station j; Cl j,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the gas gathering station j and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; When the pipe network topology is star-branched, the relationship is: Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; i is the gas production of wellhead i; Q j,k is the pipeline flow from ordinary gas gathering station j to intermediate gas gathering station k; M is an infinite number; Tl j,k,d Q is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a pipeline of specification d, the value is 1, otherwise the value is 0; j,s is the pipeline flow from gas gathering station j to central processing plant s; Cl j,s,d Q is a binary variable for gas gathering pipeline connection. If the gas gathering station j and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; k,s Dl is the pipeline flow from the intermediate gas gathering station k to the central processing plant s; i,k,d Kl is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the intermediate gas gathering station k and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; The gas pipeline flow range constraint stipulates that the gas pipeline flow rate should meet the requirements of the economic flow range, that is, the gas pipeline flow rate should be within the flow allowable range of the selected specification d pipeline, and the relationship is: Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Q dmin is the lower limit of economic flow rate of pipeline with specification d; Q dmax is the upper limit of economic flow rate for pipeline with specification d; Dl i,k,d is a binary variable for gas pipeline connection, which takes the value of 1 if the wellhead i and the intermediate gas gathering station k are connected by a pipeline of specification d, otherwise it takes the value of 0; The gas collection pipeline flow range constraint stipulates that the gas collection pipeline flow must be within the economic flow range allowed by the selected specification d pipeline, and the relationship is: Where, Tl j,k,d Q is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a pipeline of specification d, the value is 1, otherwise the value is 0; dmin is the lower limit of economic flow rate of pipeline with specification d; Q dmax is the upper limit of economic flow rate for pipeline with specification d; Cl j,s,d Kl is a binary variable for gas gathering pipeline connection. If the gas gathering station j and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; k,s,d is a binary variable for gas gathering pipeline connection, which takes the value of 1 if the intermediate gas gathering station k and the central processing plant s are connected by a pipeline of specification d, otherwise it takes the value of 0; The gas-gathering station capacity constraint stipulates that the node flow of any gas-gathering station must be less than or equal to the maximum processing capacity allowed by the selected type t gas-gathering station. When the pipeline network topology is star-shaped, the relationship is: Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; i is the gas production of wellhead i; Sd j,t is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; Q tmax The maximum processing capacity allowed for a type t gas gathering station; When the pipe network topology is star-branched, the relationship is: In the formula, q j is the node flow of gas gathering station j; Sd j,t is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; k Kd is the node flow of the intermediate gas gathering station k; k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0; The gas gathering station well number constraint stipulates that the number of wellheads connected to any gas gathering station must be less than or equal to the maximum number of wellheads allowed to be connected to the type t gas gathering station, and the relationship is: Where, Bl i,j,d is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Sd j,t is a binary variable for the location and type of the gas-gathering station. If the gas-gathering station is located in j and is of type t, the value is 1, otherwise the value is 0; M tmax The maximum number of wellheads that can be connected to a gas gathering station of type t; Dl i,k,d Kd is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; k,t is a binary variable for the location and type of the gas-gathering station, with a value of 1 if the intermediate gas-gathering station is located at k and is of type t, otherwise it is 0; The pipe network pressure constraints include the central processing plant inlet pressure constraints, operating pressure range constraints, and hydraulic pressure drop equations for gas production pipelines and gas gathering pipelines; The central processing plant inlet pressure constraint stipulates that when optimizing the design of the ground gathering and transportation system, it is necessary to ensure that the pressure at the end of the gas gathering pipeline connected to the central processing plant meets the central processing plant inlet pressure requirement. The relationship is: Where P ctmin is the minimum inlet pressure of the central treatment plant; P j,s is the terminal pressure of the gas gathering pipeline from gas gathering station j to central processing plant s; P k,s is the terminal pressure of the gas gathering pipeline from the intermediate gas gathering station k to the central processing plant s; The operating pressure range constraint stipulates that the node pressure of each wellhead, gas gathering station and central processing plant should be limited to a safe range, neither exceeding the maximum operating pressure nor falling below the minimum operating pressure; the relationship is: Where P v is the pressure at node v; It is the minimum operating pressure of the gathering and transportation pipeline network; It is the maximum operating pressure of the gathering and transportation pipeline network; The hydraulic pressure drop equation of the gas production pipeline is the hydraulic pressure drop equation of the gas production pipeline from the wellhead to the gas gathering station; the hydraulic pressure drop equation of the gas gathering pipeline is the hydraulic pressure drop equation of the gas gathering pipeline from the gas gathering station to the central processing plant; the relationship is: Where P i is the node pressure at wellhead i; P i,j is the pressure at the end of the gas pipeline from wellhead i to gas gathering station j; P j is the node pressure of gas gathering station j; is the pipe diameter coefficient; λ is the pipeline hydraulic friction coefficient; Z is the natural gas compression coefficient; Δ is the relative density of natural gas; T is the average temperature of natural gas; C is a constant, which is 0.0348 under standard conditions; R is the inner diameter corresponding to the pipeline specification d; P i,k is the pressure at the end of the gas pipeline from wellhead i to the intermediate gas gathering station k; P j,k is the pressure at the end of the gas gathering pipeline from the ordinary gas gathering station j to the intermediate gas gathering station k; P k is the node pressure of the intermediate gas gathering station k; Bl i,j,d Dl is a binary variable for gas pipeline connection. If the wellhead i and the gas gathering station j are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; i,k,d is a binary variable for gas pipeline connection. If the wellhead i and the intermediate gas gathering station k are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Cl j,s,d is a binary variable for gas gathering pipeline connection. If the gas gathering station j and the central processing plant s are connected by a pipeline with specification d, the value is 1, otherwise the value is 0; Tl j,k,d Kl is a binary variable for gas gathering pipeline connection. If the ordinary gas gathering station j and the intermediate gas gathering station k are connected by a specification d pipeline, the value is 1, otherwise the value is 0; k,s,d It is a binary variable for gas gathering pipeline connection. If the intermediate gas gathering station k and the central processing plant s are connected by a pipeline of specification d, the value is 1, otherwise the value is 0.

5. The method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions according to claim 1, characterized in that: The steps of solving the model using the artemisinin optimization algorithm described in step S4 include: S401: Assume that the maximum number of iterations is T, the population size is N, and the dimension of the solution space is D. Use a random number sequence to generate the initial artemisinin population matrix. Each element in the matrix represents a feasible solution to the problem and will serve as a search agent for the algorithm to search in the solution space. The expression is: In the formula, A N,D is the initial artemisinin population matrix; U is the upper bound of the D-dimensional solution space; L is the lower bound of the D-dimensional solution space; R is a random number in the interval (0,1]; S402: Calculate the fitness of the artemisinin population according to the model objective function, and update the optimal artemisinin population position; S403: Generate a random number r1 in the interval (0,1], calculate the artemisinin concentration index c and probability coefficient K, and implement a comprehensive elimination strategy. The formula is: In the formula, c is the concentration index; K is the probability coefficient; is the updated location of artemisinin population; is the current location of the artemisinin population; It is the optimal position of artemisinin population; S404: Generate a random number r2 in the interval (0,1] and random numbers b1, b2 and b3 in the interval (0,N], and calculate the normalized fitness value F of the artemisinin population norm , if r2<F norm , then execute the local clearing strategy, otherwise skip this stage, the formula is: In the formula, is the normalized value of artemisinin population fitness; F i is the fitness of artemisinin population; is the minimum fitness of the artemisinin population; is the maximum fitness of the artemisinin population; is the updated location of artemisinin population; S405: Generate a random number r3 in the interval (0,1], execute the post-consolidation strategy, and the artemisinin population position update formula is: In the formula, is the updated location of artemisinin population; is the current location of the artemisinin population; It is the optimal position of artemisinin population; S403: Determine whether the algorithm termination condition is met. If so, exit the main loop and output the optimal layout plan for the natural gas complex pipeline network. If not, return to S402 and continue the loop.

6. A method for optimizing the layout of a complex natural gas pipeline network coupled with hydraulic conditions as claimed in claim 1, characterized in that: The optimal layout plan of the pipeline network described in step S4 includes the total cost of the complex natural gas pipeline network; the coordinates of the gas gathering station and the central processing plant; the type, capacity and number of gas gathering stations; the connection relationship between the wellhead and the gas gathering station and the pipeline specifications; the connection relationship between the gas gathering station and the central processing plant and the pipeline specifications; and the pipeline network node pressure.

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