Multi-target isolating valve position optimization method

Abstract

The invention provides a multi-target isolating valve position optimization method, which comprises the following steps of: performing hydraulic classification on a pipe network pipeline by utilizing a pipeline hydraulic classification evaluation index, and dividing a water conveying pipeline and a water distribution pipeline; valves are installed at the two ends of the water conveying pipeline according to engineering rules; determining the position of a valve for the water distribution pipeline by adopting a stochastic optimization method so as to install the valve, which comprises the following steps of: establishing a multi-objective optimization model, and optimizing the layout of the valve on the water distribution pipeline in the pipe network by taking the number of the valves around an isolation sub-region as a constraint condition of the multi-objective optimization model; a Pareto solution set optimized by the multi-target optimization model is obtained, the Pareto solution set comprises a plurality of valve layout schemes, hydraulic evaluation is conducted on each valve layout scheme, and a final valve placement scheme is determined through multi-standard decision. The responsiveness of the water supply network to pipe explosion accidents is improved, and the influence of pipe explosion isolation is reduced to the minimum.

Description

Technical Field

[0001] The present invention relates to the technical field of water supply network isolation valve installation management, and in particular to a multi-objective isolation valve position optimization method. Background Art

[0002] When a sudden failure occurs in the water supply network, closing the isolation valve in the faulty area is the primary task. Therefore, based on this task, it is particularly important to determine the location of the isolation valve. Reasonable determination of the isolation valve location can not only achieve the isolation task as quickly as possible, but also minimize the negative impact of the failure on the pipeline network. Traditional isolation valve optimization mostly optimizes the isolation valve layout with the goal of maximizing reliability under a single pipeline failure, but this layout is obviously unable to adapt to the scenario of multiple pipeline failures caused by earthquakes. In addition, the traditional isolation valve layout often relies on engineering experience, and the distribution of some isolation valves is unreasonable, resulting in a large number of isolation valves in the accident isolation sub-area, a long time-consuming valve closing operation, a large isolation and water outage range, and serious impact on the hydraulic performance of the pipeline network. Therefore, how to optimize the layout of valves, improve the response capability of the water supply network to pipe burst accidents, and minimize the impact of pipe burst isolation is a technical problem that needs to be solved at present. Summary of the invention

[0003] The object of the present invention is to solve at least one of the technical drawbacks.

[0004] To this end, the purpose of the present invention is to propose a multi-objective isolation valve position optimization method to solve the problems mentioned in the background technology and overcome the shortcomings of the prior art.

[0005] In order to achieve the above object, an embodiment of the present invention provides a multi-objective isolation valve position optimization method, comprising the following steps:

[0006] Step S1, hydraulically classify the pipelines of the pipeline network using the pipeline hydraulic classification evaluation index, and divide them into water transmission pipelines and water distribution pipelines, including: weighting each hydraulic classification evaluation index, calculating the weight of each hydraulic classification evaluation index, and weighting each hydraulic classification evaluation index to calculate the importance of each pipeline; then use the box plot method to determine the outlier in the data, the pipeline corresponding to the outlier is the water transmission pipeline, and the remaining pipelines are water distribution pipelines;

[0007] Step S2, installing valves at both ends of the water pipeline according to engineering rules;

[0008] Step S3, using a random optimization method to determine the valve position for the water distribution pipeline to install the valve, including: establishing a multi-objective optimization model, the multi-objective optimization model including: a reliability model, a toughness evaluation model and a valve cost model, using the reliability model, the toughness evaluation model and the valve cost model as objective functions, using the number of valves around the isolation sub-area as a constraint condition of the multi-objective optimization model, and optimizing the valve layout on the water distribution pipeline in the pipe network;

[0009] Step S4, obtaining the Pareto solution set after the multi-objective optimization model is optimized, the Pareto solution set includes multiple valve layout schemes, performing hydraulic evaluation of reliability and toughness and economic evaluation of valve cost on each valve layout scheme, and determining the final valve placement scheme through multi-standard decision-making, including: normalizing the objective functions corresponding to the reliability model, the toughness evaluation model and the valve cost model respectively and setting different weight coefficients, finally calculating the values ​​of each valve layout scheme, and selecting the scheme with the lowest value as the final valve layout scheme.

[0010] Preferably, in any of the above schemes, in step S1, the pipeline hydraulic classification evaluation indicators include: isolation importance PSI, contribution rate of the pipeline to its downstream pipeline, water hammer effect of flow velocity change and edge betweenness centrality.

[0011] Preferably, in any of the above schemes, in step S1, the weights of each hydraulic classification evaluation index are calculated as follows:

[0012]

[0013] Among them, W AHP is the indicator weight determined by the hierarchical analysis method, W 熵值法 It is the indicator weight determined by the entropy weight method.

[0014] Preferably, any of the above schemes further comprises the following steps before step S1:

[0015] Step S0, constructing an isolation valve-isolation sub-area dual graph, including:

[0016] (1) Find the water-using nodes near the actual valve, add virtual nodes at the corresponding water-using nodes in the pipe network model, add short pipes between the water-using nodes and the virtual nodes to represent the isolation valves, and the pipe properties are the same as the original pipes; and simulate the open state of the isolation valve under normal working conditions or the closed isolation state under fault conditions by setting the short pipes to open or close; the short pipe set is the candidate isolation valve set;

[0017] (2) constructing a pipe network adjacency matrix, wherein the pipe network adjacency matrix includes isolation valves;

[0018] (3) deleting the isolation valve from the pipe network adjacency matrix and identifying the connected subgraph, which is the corresponding isolation sub-area;

[0019] (4) For the added isolation valve, search the connected subgraphs where its two end nodes are located. If they are in two different connected subgraphs, the valve is a real isolation valve; if the two end nodes are in the same connected subgraph, the isolation valve is a redundant valve and is deleted from the candidate isolation valve set;

[0020] (5) The isolation sub-areas are set as points of the isolation sub-area-valve graph, and the isolation valves between the isolation sub-areas are set as edges of the isolation sub-area-valve graph, thereby establishing the isolation sub-area-valve graph.

[0021] Preferably, any of the above solutions sets the redundant valve to an open state during subsequent hydraulic analysis.

[0022] Preferably, the reliability model is:

[0023]

[0024] Among them, Rel loss is the total water shortage of users in all regions during the quarantine period; ij is the failure probability of the jth pipeline in the ith region; T ij is the maintenance time required for the jth pipeline in the ith area; m is the number of pipelines in the ith area; n is the number of all isolated sub-areas; Q i is the water shortage of users in the i-th area caused by the isolation of the area; Q i ' is the water shortage of users in other accidentally isolated areas caused by the isolation of the i-th area.

[0025] Preferably, the toughness evaluation model is:

[0026]

[0027] Among them, Re loss is the amount of water lost due to resilience; K is the number of fault scenarios; u is the number of isolated sub-areas with faults in a fault scenario; T ki-repair T is the time required to repair the faulty pipeline in the i-th fault area in the k-th fault scenario; ki-replace The time required to replace the faulty pipeline in the i-th fault area for the k-th fault scenario; Q ki is the water demand of the node in the i-th fault area under the k-th fault scenario; Q′ ki is the amount of water that is cut off at other nodes due to the maintenance of the i-th fault area in the k-th fault scenario.

[0028] Preferably, any of the above solutions is that the valve cost model is:

[0029] C j =0.017d j 2 +2.08d j +78.21

[0030] Among them, d j is the diameter of pipe j; C j is the cost of installing an isolation valve on pipeline j.

[0031] Preferably, in any of the above schemes, in step S3, the constraint condition in the multi-objective optimization model is that the maximum number of isolation valves in the isolation sub-area does not exceed a preset threshold, wherein the preset threshold is set according to the pipeline network to optimize the valve layout.

[0032] Preferably, in any of the above schemes, after obtaining the Pareto solution set, in step S4, the representative value F of each scheme is calculated by multi-criteria decision making, and the scheme with the lowest value is selected as the final valve arrangement scheme, including:

[0033] F=w1Rel loss +w2Re loss +w3C j

[0034] Among them, w1 is the weight of reliability loss water; w2 is the weight of toughness loss water; w3 is the weight of valve cost. Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) Using pipeline hydraulic classification indicators, the pipelines are hydraulically classified to determine the main water supply pipelines and distribution pipelines. The valves of the water supply pipelines are arranged according to engineering rules. Valves are installed at both ends of each water supply pipeline. The valve layout of the distribution pipeline is optimized using a multi-objective optimization model.

[0036] (2) A multi-objective optimization model of reliability, resilience and cost is established, an isolation valve optimization strategy based on coupled optimization of engineering rules and random search is proposed, and the optimal isolation valve layout is determined using multi-criteria decision analysis.

[0037] (3) The valve placement strategy based on engineering experience and random optimization is comprehensively considered. At the same time, when optimizing the valve position, the reliability and toughness of the pipeline network are taken into consideration. This method is applicable to both single-pipe burst scenarios and scenarios where multiple pipes burst at the same time, providing a good reference for optimizing the layout of isolation valves in water supply networks.

[0038] (4) Improve the water supply network's ability to respond to pipe burst accidents and minimize the impact of pipe burst isolation.

[0039] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0041] Figure 1 is a flow chart of a multi-objective isolation valve position optimization method according to an embodiment of the present invention;

[0042] Figure 2 is a schematic diagram of a multi-objective isolation valve position optimization method according to an embodiment of the present invention;

[0043] Figure 3a A water supply network diagram according to an embodiment of the present invention;

[0044] Figure 3b is an isolation valve-isolation sub-area dual graph according to an embodiment of the present invention;

[0045] Figure 4 A pipe network diagram according to an embodiment of the present invention;

[0046] Figure 5 2 is a diagram of pipe network valve placement according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0048] The multi-objective isolation valve position optimization method provided by the present invention is an isolation valve layout optimization method based on the coupling of engineering rules and random search.

[0049] like Figure 1 and Figure 2 As shown, the multi-objective isolation valve position optimization method of the embodiment of the present invention includes the following steps:

[0050] Step S0, constructing an isolation valve-isolation sub-area dual graph, and constructing an SV graph includes:

[0051] (1) First, find the water-using nodes near the actual valve, add virtual nodes at the corresponding water-using nodes in the pipe network model, and add a short pipe between the water-using nodes and the virtual nodes to represent the isolation valve. The pipe properties are the same as the original pipe. By setting the short pipe to open or close, the isolation valve is simulated in the open state under normal working conditions or the closed isolation state under fault conditions. Figure 3a As shown, the short pipe assembly is a candidate isolation valve assembly.

[0052] (2) Construct a pipeline network adjacency matrix, where the pipeline network adjacency matrix includes isolation valves.

[0053] (3) The isolation valve is deleted from the pipe network adjacency matrix, and a series of connected subgraphs are identified through the breadth-first search algorithm, which are the corresponding isolation sub-areas.

[0054] (4) For the added isolation valve, search the connected subgraphs where its two end nodes are located. If they are in two different connected subgraphs, the valve is a real isolation valve; if the two end nodes are in the same connected subgraph, the isolation valve is a redundant valve and is deleted from the candidate isolation valve set. Because the closure of the redundant valve will not isolate the faulty pipeline, it can be set to the open state in the subsequent hydraulic analysis, such as Figure 3a Middle isolation valve V11.

[0055] (5) The isolation sub-areas are set as points of the isolation sub-area-valve graph, and the isolation valves between the isolation sub-areas are set as edges of the isolation sub-area-valve graph, thereby establishing the isolation sub-area-valve graph, such as Figure 3b shown.

[0056] Then, steps S1 to S4 are executed to analyze the importance of pipelines from the hydraulic and topological aspects, and the water delivery pipelines and water distribution pipelines in the pipeline network are determined according to the pipeline importance classification. For water delivery pipelines, valves are installed at both ends of each pipeline according to engineering rules. For water distribution pipelines, a random optimization strategy is adopted, with reliability, toughness, and cost as the objective function and the number of valves around the isolation sub-area as the constraint condition to optimize the valve layout. Finally, based on the optimization results, the final valve placement plan is determined using multi-criteria decision making.

[0057] The execution process of step S1 to step S4 is described in detail below.

[0058] Step S1, using the pipeline hydraulic classification evaluation index to hydraulically classify the pipeline network pipelines, and divide them into water transmission pipelines and water distribution pipelines, including: weighting each hydraulic classification evaluation index, calculating the weight of each hydraulic classification evaluation index, weighting each hydraulic classification evaluation index to calculate the importance of each pipeline, and then using the box plot method to determine the outliers in the data, the pipeline corresponding to the outlier is the water transmission pipeline, and the remaining pipelines are water distribution pipelines.

[0059] Among them, the box plot method is used to determine the outliers in the data. Specifically, according to the importance of all pipelines, the upper and lower quartiles and interquartile range of the data are calculated, and an upper and lower limit is determined according to the size of the interquartile range. Data points exceeding the upper or lower limit are marked as outliers.

[0060] In an embodiment of the present invention, pipeline hydraulic classification evaluation indicators include: isolation importance PSI, contribution rate of pipeline to its downstream pipeline, water hammer effect of flow velocity variation and edge betweenness centrality.

[0061] The hydraulic classification evaluation indicators of each pipeline are explained below.

[0062] 1) PSI: Assuming that each pipe has an isolation valve installed at both ends, calculate the impact of isolating a single pipe on the water consumption of the entire network. The specific calculation is as follows:

[0063] PSI=Q req -Q single,avl (1)

[0064] In the formula, Q req is the normal water consumption of the pipe network; Q single,avl The amount of water used in the network when isolating the pipeline.

[0065] 2) The contribution rate of a pipeline to its downstream pipeline (pipeline flow contribution rate): Through hydraulic simulation, the flow contribution rate of the pipeline to its downstream pipeline is obtained, that is, the proportion of water flowing out of the pipeline in the downstream pipelines is counted.

[0066]

[0067] Among them, w i D is the ratio of the amount of water received by the downstream node i to the demand of the node; i is the node water demand of the i-th node.

[0068] 3) Water hammer effect of flow rate change: Use hydraulic simulation to simulate the flow rate of the pipeline, find the moments when the difference between the two flow rates is the largest, and calculate the flow rate change ratio to reflect the severity of the water hammer effect.

[0069]

[0070] Where V i is the flow velocity at the i-th moment, V i+1 is the flow velocity at the i+1th moment.

[0071] 4) Edge betweenness centrality: The calculation of edge betweenness centrality usually involves the consideration of weight factors. The pipeline is set as the edge and the node is the point. The water transmission potential and the minimum unit pressure loss are used as the edge weights respectively. The edge betweenness centrality under two different weights is calculated. The specific calculation is as follows:

[0072]

[0073] In the formula, s, t are nodes, N is the number of nodes, and w l is the weight of edge l, σ s,t (l) is the number of pipelines l in the shortest path between nodes s and t, σ s,t is the number of shortest paths between nodes s and t.

[0074] The minimum unit pressure loss is calculated using the Darcy-Weber formula. There is a relationship between the flow rate of water flowing through a pipe and the shape, smoothness, length and head (pressure drop) of the pipe cross section. When water flows through a pipe, it will flow in the direction of reduced pressure, minimizing the total energy loss of the entire system. The specific calculation is as follows:

[0075]

[0076] Where λ is the resistance coefficient along the way; v is the average flow velocity of the water section (m / s); D is the inner diameter of the pipe (mm); g is the acceleration due to gravity (m / s 2 ).

[0077] Pipeline water transfer potential (SC): mainly considers the flow capacity of the pipeline, and the specific calculation is as follows:

[0078]

[0079] Where, C is the Hezen-William coefficient; D is the inner diameter of the pipe (mm); and L is the pipe length (m).

[0080] The combined weighting method combining the analytic hierarchy process and the entropy weight method is used to weight each hydraulic index. The weight calculation of each index is as follows:

[0081]

[0082] Among them, W AHP is the indicator weight determined by the hierarchical analysis method, W 熵值法 It is the indicator weight determined by the entropy weight method.

[0083] After weighted calculation of each indicator, the outliers in the data are determined using the box plot, and the pipeline corresponding to the outlier is the important pipeline.

[0084] Step S2, installing valves at both ends of the water pipeline according to engineering rules.

[0085] Step S3, using a random optimization method to determine the valve position of the water distribution pipeline to install the valve, including: establishing a multi-objective optimization model.

[0086] Specifically, a multi-objective optimization model of reliability, toughness and cost is established, and the valve arrangement on the water distribution pipes in the network is optimized using the multi-objective optimization algorithm using the optimization model.

[0087] In an embodiment of the present invention, the multi-objective optimization model includes: a reliability model, a toughness evaluation model and a valve cost model. The reliability model, the toughness evaluation model and the valve cost model are used as objective functions, and the number of valves around the isolation sub-area is used as a constraint condition of the multi-objective optimization model to optimize the valve layout on the water distribution pipes in the pipeline network.

[0088] The reliability model, toughness evaluation model and valve cost model are explained below respectively.

[0089] 1) The reliability model is:

[0090]

[0091] Among them, Rel loss is the total water shortage of users during the isolation period in all areas (m 3 );p ij is the failure probability of the jth pipeline in the ith region; T ij is the maintenance time (h) required for the jth pipeline in the ith area; m is the number of pipelines in the ith area; n is the number of all isolated sub-areas; Q i is the water shortage of users in the i-th area caused by the isolation of the area; Q i ' is the water shortage of users in other accidentally isolated areas caused by the isolation of the i-th area.

[0092] The probability of pipeline failure is as follows:

[0093]

[0094] β l =r l L l (9)

[0095] In the formula, β l is the expected number of failures per year for pipeline l; l is the length of the pipeline (m).

[0096] r l is the expected number of failures per unit length of pipeline per year. The expected number of failures per unit length of pipeline per year function is as follows:

[0097]

[0098] Where D l is the inner diameter of the pipe.

[0099] The maintenance and replacement time of pipelines are as follows:

[0100] T repair =0.223·D i 0.577 (11)

[0101] T replace =0.156·D i 0.719 (12)

[0102] Where, T repair T is the time required for pipeline repair (h); replace The time required to replace the pipeline (h); D i is the pipe diameter (mm).

[0103] 2) Toughness evaluation model is:

[0104]

[0105] Among them, Re loss is the toughness loss water (m 3 ); K is the number of fault scenarios; u is the number of isolated sub-areas with faults in a fault scenario; T ki-repair T is the time (h) required to repair the faulty pipeline in the i-th fault area in the k-th fault scenario; ki-replace The time required to replace the faulty pipeline in the i-th fault area for the k-th fault scenario (h); Q ki is the water demand of the node in the i-th fault area under the k-th fault scenario (m3 / h); Q ki ′ is the amount of water that is cut off at other nodes due to the maintenance of the i-th fault area in the k-th fault scenario (m 3 / h).

[0106] 3) Valve cost model is:

[0107] C j =0.017d j 2 +2.08d j +78.21 (15)

[0108] Among them, d j is the diameter of pipe j (mm); C j is the cost of installing an isolation valve on pipeline j.

[0109] In an embodiment of the present invention, the constraint condition in the multi-objective optimization model is that the maximum number of isolation valves in the isolation sub-area does not exceed a preset threshold. The preset threshold is set according to the pipeline network to optimize the valve layout. For example, the threshold for a large pipeline network can be set to 8. When optimizing the isolation valve layout of the pipeline network using the optimization model, in order to reduce the optimization time, a topological method is used to identify the accidental isolation sub-area in the pipeline network.

[0110] Step S4, obtaining the Pareto solution set (i.e., Pareto frontier result) after the optimization of the multi-objective optimization model, the Pareto solution set includes multiple valve layout schemes, and hydraulic evaluation of reliability and toughness and economic evaluation of valve cost are performed on each valve layout scheme, and the final valve placement scheme is determined through multi-standard decision-making, including: normalizing the objective functions corresponding to the reliability model, toughness evaluation model and valve cost model and setting different weight coefficients respectively, and finally calculating the values ​​of each valve layout scheme, and selecting the scheme with the lowest value as the final valve layout scheme.

[0111] In this step, when the Pareto solution set is obtained after the optimization, it is necessary to conduct a hydraulic evaluation on the scheme. The preliminarily selected scheme is hydraulically evaluated using hydraulic simulation, and the final valve placement scheme is determined through multi-criteria decision-making. The three objective functions are normalized and different weight coefficients are set as needed. The weight coefficients are determined according to specific needs. Finally, the values ​​of each scheme are calculated, and the scheme with the lowest value is selected as the final valve placement scheme.

[0112] Specifically, after obtaining the Pareto solution set, the representative value F of each solution is calculated using multi-criteria decision making, and the solution with the lowest value is selected as the final valve arrangement solution, including:

[0113] F=w1Rel loss +w2Re loss +w3C j (16)

[0114] Among them, w1 is the weight of reliability loss water, which is determined by actual demand; w2 is the weight of toughness loss water, which is determined by actual demand; w3 is the weight of valve cost, which is determined by actual demand.

[0115] The multi-objective isolation valve position optimization method provided by the present invention is applied to Figure 4 In the pipeline network, there are 2 water sources, 349 nodes, and 509 pipes. Figure 5 This is the optimized isolation valve layout diagram.

[0116] The multi-objective isolation valve position optimization method provided by the present invention proposes pipeline hydraulic classification indicators, divides the pipeline network into main water supply pipelines and water distribution pipelines, and for water supply pipelines, valves are installed at both ends of the pipeline based on engineering rules; for water distribution pipelines, an optimization method is used to determine the valve position; a multi-objective optimization model based on pipeline reliability, toughness and cost is established, and the valves on the water distribution pipeline are optimized using a multi-objective optimization algorithm, and finally the valve layout is determined using a multi-standard decision-making method.

[0117] Compared with the prior art, the present invention has the following beneficial effects:

[0118] (1) Using pipeline hydraulic classification indicators, the pipelines are hydraulically classified to determine the main water supply pipelines and distribution pipelines. The valves of the water supply pipelines are arranged according to engineering rules. Valves are installed at both ends of each water supply pipeline. The valve layout of the distribution pipeline is optimized using a multi-objective optimization model.

[0119] (2) A multi-objective optimization model of reliability, resilience and cost is established, an isolation valve optimization strategy based on coupled optimization of engineering rules and random search is proposed, and the optimal isolation valve layout is determined using multi-criteria decision analysis.

[0120] (3) The valve placement strategy based on engineering experience and random optimization is comprehensively considered. At the same time, when optimizing the valve position, the reliability and toughness of the pipeline network are taken into consideration. This method is applicable to both single-pipe burst scenarios and scenarios where multiple pipes burst at the same time, providing a good reference for optimizing the layout of isolation valves in water supply networks.

[0121] (4) Improve the water supply network's ability to respond to pipe burst accidents and minimize the impact of pipe burst isolation.

[0122] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0123] It is not difficult for those skilled in the art to understand that the present invention includes any combination of the invention content and specific implementation methods of the above specification and the various parts shown in the drawings. Due to the limited space and to make the specification concise, the various schemes composed of these combinations are not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0124] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-objective isolation valve position optimization method, characterized in that: The steps include: Step S1, hydraulically classify the pipelines of the pipeline network using the pipeline hydraulic classification evaluation index, and divide them into water transmission pipelines and water distribution pipelines, including: weighting each hydraulic classification evaluation index, calculating the weight of each hydraulic classification evaluation index, and weighting each hydraulic classification evaluation index to calculate the importance of each pipeline; using the box plot method to determine the outlier in the data, the pipeline corresponding to the outlier is the water transmission pipeline, and the remaining pipelines are water distribution pipelines; Step S2, installing valves at both ends of the water pipeline according to engineering rules; Step S3, using a random optimization method to determine the valve position for the water distribution pipeline to install the valve, including: establishing a multi-objective optimization model, the multi-objective optimization model including: a reliability model, a toughness evaluation model and a valve cost model, using the reliability model, the toughness evaluation model and the valve cost model as objective functions, using the number of valves around the isolation sub-area as a constraint condition of the multi-objective optimization model, and optimizing the valve layout on the water distribution pipeline in the pipe network; Step S4, obtaining the Pareto solution set after the multi-objective optimization model is optimized, the Pareto solution set includes multiple valve layout schemes, performing hydraulic evaluation of reliability and toughness and economic evaluation of valve cost on each valve layout scheme, and determining the final valve placement scheme through multi-standard decision-making, including: normalizing the objective functions corresponding to the reliability model, the toughness evaluation model and the valve cost model respectively and setting different weight coefficients, finally calculating the values ​​of each valve layout scheme, and selecting the scheme with the lowest value as the final valve layout scheme.

2. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: In the step S1, the pipeline hydraulic classification evaluation indicators include: isolation importance PSI, contribution rate of the pipeline to its downstream pipeline, water hammer effect of flow velocity change and edge betweenness centrality.

3. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: In step S1, the weights of each hydraulic classification evaluation index are calculated as follows: Among them, W AHP is the indicator weight determined by the hierarchical analysis method, W 熵值法 It is the indicator weight determined by the entropy weight method.

4. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: Before step S1, the method further includes the following steps: Step S0, constructing an isolation valve-isolation sub-area dual graph, including: (1) Find the water-using nodes near the actual valve, add virtual nodes at the corresponding water-using nodes in the pipe network model, add short pipes between the water-using nodes and the virtual nodes to represent the isolation valves, and the pipe properties are the same as the original pipes; and simulate the open state of the isolation valve under normal working conditions or the closed isolation state under fault conditions by setting the short pipes to open or close; the short pipe set is the candidate isolation valve set; (2) constructing a pipe network adjacency matrix, wherein the pipe network adjacency matrix includes isolation valves; (3) deleting the isolation valve from the pipe network adjacency matrix and identifying the connected subgraph, which is the corresponding isolation sub-area; (4) For the added isolation valve, search the connected subgraphs where its two end nodes are located. If they are in two different connected subgraphs, the valve is a real isolation valve; if the two end nodes are in the same connected subgraph, the isolation valve is a redundant valve and is deleted from the candidate isolation valve set; (5) The isolation sub-areas are set as points of the isolation sub-area-valve graph, and the isolation valves between the isolation sub-areas are set as edges of the isolation sub-area-valve graph, thereby establishing the isolation sub-area-valve graph.

5. The multi-objective isolation valve position optimization method according to claim 4, characterized in that: The redundant valve is set to the open state during the subsequent hydraulic analysis.

6. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: The reliability model is: Among them, Rel loss is the total water shortage of users in all regions during the quarantine period; ij is the failure probability of the jth pipeline in the ith region; T ij is the maintenance time required for the jth pipeline in the ith area; m is the number of pipelines in the ith area; n is the number of all isolated sub-areas; Q i is the water shortage of users in the i-th area caused by the isolation of the area; Q′ i is the water shortage of users in other accidentally isolated areas caused by the isolation of the i-th area.

7. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: The toughness evaluation model is: Among them, Re loss is the amount of water lost due to resilience; K is the number of fault scenarios; u is the number of isolated sub-areas with faults in a fault scenario; T ki-repair T is the time required to repair the faulty pipeline in the i-th fault area in the k-th fault scenario; ki-replace The time required to replace the faulty pipeline in the i-th fault area for the k-th fault scenario; Q ki is the water demand of the node in the i-th fault area under the k-th fault scenario; Q ki ′ is the amount of water that is cut off at other nodes due to the maintenance of the i-th fault area in the k-th fault scenario.

8. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: The valve cost model is: C j =0.017d j 2 +2.08d j +78.21 Among them, d j is the diameter of pipe j; C j is the cost of installing an isolation valve on pipeline j.

9. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: In step S3, the constraint condition in the multi-objective optimization model is that the maximum number of isolation valves in the isolation sub-area does not exceed a preset threshold, wherein the preset threshold is set according to the pipeline network to optimize the valve layout.

10. The multi-objective isolation valve position optimization method according to claim 1, characterized in that: In step S4, after obtaining the Pareto solution set, the representative value F of each solution is calculated using multi-criteria decision making, and the solution with the lowest value is selected as the final valve arrangement solution, including: F=w1Rel loss +w2Re loss +w3C j Among them, w1 is the weight of reliability loss water; w2 is the weight of toughness loss water; w3 is the weight of valve cost.

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