Water supply network optimization and transformation method based on hierarchical optimization

Abstract

The invention discloses a hierarchical optimization-based water supply network optimization transformation method. The method comprises the following steps of: finding out a node with the lowest free water head in a water supply network as a control point; finding a shortest distance path from the control point to the water plant as a main control path; searching a pipe diameter optimization scheme of the pipe section on the main control path by taking the condition that delta FNPV is greater than 0 as a target; if the control points change after the current optimized pipe diameter optimization scheme is executed, finding out all points lower than the free water heads of the original control points as candidate control points, finding out the shortest distance path from the candidate control points to the water plant as a candidate control path, and searching the pipe diameter optimization scheme of the pipe section on the candidate control path; and forming a combined transformation scheme together with the current optimized pipe diameter optimization scheme. On the basis of the pipe diameter optimization scheme of the replacement pipeline, a parallel pipeline optimization scheme is selected. And finally outputting a feasible pipe diameter optimization scheme list which comprises a replacement pipeline scheme and a parallel pipeline scheme. The method is high in efficiency, and the deficiency of human experience can be avoided.

Description

Technical Field

[0001] The present application relates to the field of urban water supply network reconstruction, and specifically to a water supply network optimization reconstruction method based on hierarchical optimization. Background Art

[0002] According to the present invention, as the growth rate of urbanization rate slows down, the incremental projects of urban water supply pipe network projects will also gradually decrease. The market shift from "incremental market" to "stock market" is the inevitable trend of industry development.

[0003] Most of the existing water supply networks in my country's cities have been in operation for many years, and some have even been in operation for more than 50 years. Due to factors such as unscientific design, inadequate operation and management, and poor operating environment, the system has high energy consumption and some pipelines are seriously corroded and scaled. Not only does the system operation have major safety hazards, it also has a great impact on people's lives and urban safety, and may even cause serious social impacts and economic property losses. Therefore, the reasonable renovation of the water supply network system is of great significance for reducing water supply network leakage, saving energy and reducing carbon emissions, reducing comprehensive operating costs, ensuring system safety, and improving service quality.

[0004] Due to the large scale and complex topological structure of the water supply network, most of the existing transformation methods rely on the experience of designers, usually providing a few transformation plans for comparison, such as replacing the pipeline to be transformed with a pipeline of the same diameter, or replacing it with a pipeline of a larger diameter after comprehensive consideration, etc., and the decision-making process is subjective. The existing method of optimizing and transforming the water supply network using intelligent algorithms is to establish an optimization model by setting objective functions and constraints to solve decision variables. The commonly used intelligent optimization algorithms include genetic algorithms, particle swarm algorithms, and ant colony algorithms, but they have their own shortcomings and it is difficult to obtain a stable optimal solution. With the increase in the scale of the water supply network, the feasible decision variables will grow exponentially, resulting in an increase in the complexity and amount of calculation of the optimization model. In addition, intelligent algorithms often start optimization with random solutions as the initial point, so there are problems such as large amount of calculation, long calculation time, low calculation efficiency, high data quality requirements, applicability to specific water supply networks, unstable results, easy to fall into local optimal solutions, and the diameter of the pipe obtained does not conform to the actual situation. There are certain limitations.

[0005] Through the above analysis, we can know that the current water supply network transformation methods have the following problems in actual implementation:

[0006] (1) Designers usually select renovation plans based on experience. The choice of pipe diameter is highly subjective. The rationality of the pipe diameter selection is not considered as a whole. There is a lack of scientific basis for quantitative evaluation. It is often difficult to ensure the economic optimality of the water supply network renovation plan, and there is often a lot of room for optimization.

[0007] (2) The optimization method using intelligent algorithms has a large amount of calculation, slow convergence speed, and unstable results, resulting in low optimization efficiency of the water supply network and difficulty in obtaining the optimal solution. Summary of the invention

[0008] The present application provides a water supply network optimization and transformation method based on hierarchical optimization, which is highly efficient and can avoid the shortcomings of human experience.

[0009] The technical solution provided by this application is:

[0010] In a first aspect, the present application provides a water supply network optimization and transformation method based on hierarchical optimization, comprising:

[0011] S1. Obtain the current water supply network topology map;

[0012] S2. Based on the current water supply network topology, the water supply network is adjusted and calibrated to find the node with the lowest free water head in the water supply network as the control point, which is recorded as control point A. The free water head of control point A is equal to the minimum free water head of the water supply network.

[0013] S3, find the shortest distance path from control point A to the water plant as the main control path;

[0014] S4, with the goal of the change in the financial net present value ΔFNPV of the total cost of the water supply network being greater than 0, searching for the pipe diameter optimization scheme of the pipe section on the main control path, and recording the feasible pipe diameter optimization scheme into the database; based on the ΔFNPV calculation result, if there is no optimization space for the water supply network, then go to step S6; based on the searched current preferred pipe diameter optimization scheme, the water supply network is again adjusted and calculated, and if it is necessary to further search for a combined transformation scheme, then go to step S5;

[0015] S5. Taking ΔFNPV greater than 0 as the goal, further search for combined transformation schemes and record feasible combined transformation schemes into the database; including:

[0016] Based on the result of the adjustment calculation of the water supply network again in step S4, find all points with lower free water head than the original control point A after the current preferred pipe diameter optimization scheme is executed as candidate control points, and arrange all candidate control points in order from low to high free water head, and record them as C 1 ,C 2 ,…,C m ,…,C M ; Where M is the number of candidate control points;

[0017] Starting from m=1, for each candidate control point, find the shortest distance path from the candidate control point to the water plant as the candidate control path, search for the pipe diameter optimization scheme of the pipe section on the candidate control path, and form a combined transformation scheme together with the current preferred pipe diameter optimization scheme, and record the feasible combined transformation scheme into the database;

[0018] S6. The database outputs a list of feasible pipe diameter optimization solutions.

[0019] In some possible implementations, in step S3 and step S5, the Floyd algorithm is used to find the shortest distance path from control point A and the candidate control point to the water plant.

[0020] In some possible implementations, in step S4, the FIRR, ΔFNPV and investment cost corresponding to the feasible pipe diameter optimization scheme are calculated, and the content of the feasible pipe diameter optimization scheme, the corresponding FIRR, ΔFNPV and investment cost are recorded in a database;

[0021] In step S5, the FIRR, ΔFNPV and investment cost corresponding to the feasible combined transformation scheme are calculated, and the content of the feasible combined transformation scheme, the corresponding FIRR, ΔFNPV and investment cost are recorded in the database.

[0022] In some possible implementations, step S4 includes:

[0023] S4.1. Determine a current alternative solution set, wherein each alternative solution in the current alternative solution set is: amplify the diameter of a pipe section on the main control path by one level;

[0024] S4.2, using ΔFNPV as the evaluation index, solve the ΔFNPV corresponding to each alternative in the current alternative set;

[0025] Assume that the jth alternative is to enlarge the diameter of pipe section j on the main control path by one level. The calculation formula of ΔFNPV corresponding to the jth alternative is as follows:

[0026] ΔFNPV C =[c(D j )-c(D j )']·l j

[0027]

[0028] ΔFNPV=ΔFNPV C +ΔFNPV O

[0029] Where, ΔFNPV Cis the present value of the investment cost for water supply network reconstruction, which is a negative value; c(D j )′ is the cost per unit length of pipe section j after the change in diameter, c(D j ) is the cost per unit length of the pipe section j before the change in diameter, l j is the length of pipe segment j; ΔFNPV O is the annual net present value of operating cost savings after the transformation of the water supply network, which is a positive value; FIRR is the internal rate of return of the enterprise; y is the operating life of the water supply network; γ is the density of water; Q is the total flow provided by the water pump station to the water supply network; ΔH j =H j -H' j H is the head loss that can be reduced by changing the pipe diameter of pipe section j after the jth alternative is implemented; j is the head loss of pipe section j before the diameter of pipe section j changes, H' j is the head loss of pipe section j after the pipe diameter of pipe section j changes; e is the electricity fee, η is the comprehensive energy conversion efficiency;

[0030] S4.3. Determine whether there is an alternative with a corresponding ΔFNPV greater than 0 in the current alternative set. If so, find the current preferred pipe diameter optimization scheme, which is the alternative with a corresponding ΔFNPV greater than 0 and the largest in the current alternative set. If the ΔFNPV corresponding to each alternative in the current alternative set is a negative value, indicating that there is no optimization space for the water supply network, go to step S6.

[0031] S4.4, based on the current preferred pipe diameter optimization scheme and considering the minimum free water head constraint of the water supply network, recalculate the water supply network adjustment, optimize the head of the water supply pump station of the water plant, and find the node with the lowest free water head in the water supply network after the current preferred pipe diameter optimization scheme is executed, that is, the control point;

[0032] S4.5, determine whether the control point has changed;

[0033] If the control point remains unchanged, the current preferred pipe diameter optimization scheme is feasible, and the current preferred pipe diameter optimization scheme is recorded in the database; return to step S4.1;

[0034] If the control point changes, go to step S4.6;

[0035] S4.6. Recalculate ΔFNPV for the current optimal pipe diameter optimization solution O , and the recalculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O Recalculate the ΔFNPV corresponding to the current preferred pipe diameter optimization solution; where ΔFNPV is recalculatedO The formula is as follows:

[0036]

[0037] Where ΔH=H A -H' A is the free water head that can be saved in the water supply network after the current optimal pipe diameter optimization scheme is implemented, H A The head of the water supply pump station of the water plant before the current optimal pipe diameter optimization scheme is implemented; H' A The head of the water supply pump station of the water plant after the current optimal pipe diameter optimization scheme is implemented;

[0038] S4.7. Determine whether the ΔFNPV corresponding to the recalculated current preferred pipe diameter optimization scheme is greater than 0. If it is greater than 0, it means that the current preferred pipe diameter optimization scheme is feasible. The current preferred pipe diameter optimization scheme is recorded in the database and go to step S6; otherwise, go to step S5.

[0039] In some possible implementations, in step S5, starting from m=1, for each candidate control point, the shortest distance path from the candidate control point to the water plant is found as the candidate control path, and the pipe diameter optimization scheme of the pipe section on the candidate control path is searched, and the combined transformation scheme is formed together with the current preferred pipe diameter optimization scheme, and the feasible combined transformation scheme is recorded in the database, including:

[0040] S5.1. Find candidate control points C m The shortest distance path to the water plant;

[0041] S5.2, determine a first set of individual projects, each of which is: m The diameter of a pipe section on the shortest distance path to the water plant is enlarged for primary treatment;

[0042] S5.3. Calculate the internal rate of return FIRR for each single project; keep the corresponding internal rate of return FIRR greater than the benchmark internal rate of return FIRR 基准 All individual projects;

[0043] S5.4. Arrange all the remaining individual projects in descending order according to their corresponding FIRR, and record them as C m1 ,C m2 ,…,C mL ; Where L is the number of individual projects retained; the head loss that can be reduced after the implementation of each individual project is recorded as h Cm1 ,h Cm2 ,…,h CmL ;

[0044] S5.5 Define the nth single project Cmn The free head characteristic array is (h mns ,h Cmn ), where n is 1, 2, …, L, h mns Indicates the starting point of the nth single project, and the calculation formula is:

[0045]

[0046] In the formula, h Cmn It indicates the head loss that can be reduced after the nth single project is implemented; h Cmi represents the head loss that can be reduced after the execution of the i-th single project; where h A is the maximum head loss that can be reduced after the current optimal pipe diameter optimization scheme is implemented, Represents the candidate control point C m The free head is insufficient. Candidate control point C before executing the current optimal pipe diameter optimization plan m Free water head - the maximum head loss that can be reduced after the current optimal pipe diameter optimization scheme is implemented - the minimum free water head of the water supply network |; It indicates the head loss that can be reduced after the execution of the previous single project of this single project;

[0047] S5.6 Calculation of C m1 ,C m2 ,…,C mL The end point of which is the nth single project C mn The end point h mne =h mns +h Cmn ; and for C m1 ,C m2 ,…,C mL The endpoints are arranged in ascending order to obtain the endpoint array H 1 ,H 2 ,…,H k ,…,H L ; Among them, H k represents the kth endpoint;

[0048] S5.7 Initialize k=1;

[0049] S5.8 Find all starting points < H k The single project of the second single project set is recorded as the second single project set, and the change in the financial net present value of the total cost of the water supply network corresponding to all the single projects in the second single project set after execution is calculated, which is recorded as ∑ΔFNPV k ;

[0050] S5.9 Determine ∑ΔFNPV k Is it greater than 0? If ∑ΔFNPVk >0, indicating that the second single project set is feasible, go to step S5.10; otherwise, determine whether k < L, if k < L, set k = k + 1, and go to step S5.8; if k = L, determine whether m < M, if m < M, set m = m + 1, go to step S5.1; if m = M, go to step S6;

[0051] S5.10 Determine H k Is it less than h A , if H k <h A , using the formula Calculate the ΔFNPV corresponding to the combined transformation plan O , and the calculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O , calculate the ΔFNPV corresponding to the combined transformation scheme; record the combined transformation scheme into the database, and go to step S4;

[0052] If H k ≥h A , using the formula Calculate the ΔFNPV corresponding to the combined transformation plan O , and the calculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O , calculate the ΔFNPV corresponding to the combined transformation scheme; record the combined transformation scheme into the database, and go to step S4.

[0053] In some possible implementations, the method further includes:

[0054] Based on the pipe diameter optimization solution obtained in steps S1-S5, i.e., the pipeline replacement solution, a parallel pipeline solution is selected taking into account pipeline laying factors. The parallel pipeline solution means that the newly laid pipeline and the existing pipeline jointly transport and distribute water;

[0055] Record parallel pipeline plans to the database.

[0056] In some possible implementations, step S6 includes: outputting all pipe diameter optimization solutions, including the content of the replacement pipeline solution and the parallel pipeline solution, and the corresponding FIRR, ΔFNPV and investment cost.

[0057] In a second aspect, the present application provides an electronic device, including: a memory and a processor;

[0058] The memory is used to store computer programs;

[0059] The processor is used to call the computer program to execute the method as described above.

[0060] In a third aspect, the present application provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed on an electronic device, the electronic device implements the method as described above.

[0061] In a fourth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed on an electronic device, the electronic device implements the method as described above.

[0062] The specific implementation methods of the second to fourth aspects of the present application can refer to the implementation methods of the first aspect, which will not be repeated here.

[0063] Beneficial effects:

[0064] Compared with the existing water supply network reconstruction design ideas, the main advantages of the method of the present invention are as follows:

[0065] (1) This application can systematically obtain the optimal solution for the combination of water supply network reconstruction plans without relying on the design experience of the designers, which is convenient for decision-making.

[0066] (2) This application is based on the calculation of the financial net present value of the total cost of the water supply network. It does not require multiple iterations of complex algorithms. Therefore, it does not have the problems of slow algorithm convergence, easy to fall into local optimal solutions, and poor result stability.

[0067] (3) This method can be applied to the optimization and renovation of various water supply networks. The method is highly operational and can quickly determine the diameters of the pipe sections to be renovated in the water supply network, thereby reducing the calculation time for optimizing the renovation of the water supply network and improving the calculation efficiency. At the same time, it takes into account the overall operating costs of the water supply network and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a flow chart of an embodiment of the present application. DETAILED DESCRIPTION

[0069] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0070] It should be noted that the terms such as "first" and "second" in the specification and claims of this application and the above-mentioned drawings are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply a specific relationship or order between these entities or operations. It should be understood that the words "first" and "second" do not limit the quantity and execution order, and the words "first" and "second" do not necessarily limit them to be different. It should be understood that the data used in this way can be interchangeable under appropriate circumstances.

[0071] The embodiment of the present application provides a water supply network optimization and transformation method based on hierarchical optimization, with the total financial net present value and internal rate of return of the water supply network as the target, by finding the shortest path and hierarchically optimizing the diameter of each pipe section of the water supply network until the optimal combination of all pipe sections is determined, the optimization and transformation scheme of the water supply network can be quickly determined, and the method can achieve fast convergence speed and avoid the shortcomings of human experience. A reliable water supply network transformation scheme can be obtained, which can maximize the water delivery efficiency, reduce energy consumption, and reduce the pump head.

[0072] The following will refer to Figure 1 Specific embodiments according to the present application are described.

[0073] The present application embodiment provides a water supply network optimization and transformation method based on hierarchical optimization, including:

[0074] S1. Obtain the current water supply network topology map;

[0075] In some embodiments, relevant information such as the topological structure, pipe length, pipe diameter, node elevation, etc. of the water supply network can be collected to draw a topological diagram of the current water supply network. Meanwhile, necessary simplifications are performed on the water supply network, including deletion and merging of pipelines, to obtain a final topological diagram of the current water supply network.

[0076] S2. Based on the current water supply network topology, the water supply network is adjusted and calibrated to find the node with the lowest free water head in the water supply network as the control point, which is recorded as control point A. The free water head of control point A is equal to the minimum free water head (minimum service water head) of the water supply network.

[0077] The water supply network is leveled and calculated, considering four situations: ① the highest daily maximum; ② when the most unfavorable pipe section fails; ③ when firefighting; ④ when the maximum transfer (when there is a water tower in the water supply network), and calibrated according to the actual operation conditions. After each adjustment of the pipe diameter of a certain pipe section, it is also necessary to re-level the water supply network, and each time it is necessary to ensure that the control point of the water supply network reaches the specified minimum service head. For example, according to the "Outdoor Water Supply Design Standard" GB 50013-2018, the minimum service head is considered to be 28m to meet the water pressure requirements of six floors, or according to relevant local regulations.

[0078] S3, find the shortest distance path from control point A to the water plant as the main control path;

[0079] In some embodiments, assuming that there is only one water plant in the water supply network, the shortest distance from each node of the water supply network to the water plant is calculated by using the Floyd algorithm for calculating the shortest distance, thereby obtaining the shortest distance path from control point A to the water plant as the main control path from control point A to the water plant.

[0080] Among them, the Floyd algorithm is a classic algorithm for solving graph theory problems to calculate the shortest path between two points. It is suitable for graphs with dense nodes. The specific steps are as follows:

[0081] 1) Start from any single-edge path. The distance between all two points is the weight of the edge. If there is no edge connecting two points, the weight is infinite.

[0082] 2) For each pair of vertices u and v, see if there is a vertex w (usually called an intermediate point) such that the path from u to w and then to v is shorter than the known path. If so, update the shortest path.

[0083] 3) Traverse until the end, at this time the data structure storing the graph has obtained the multi-source shortest path.

[0084] After finding the main control path, start searching for pipe diameter optimization solutions from the pipe segments on the main control path. Before searching, you can set the basic parameters of the water supply network, including pipe materials (such as ductile iron pipes), pipe diameter specifications in the standard commercial pipe diameter set, comprehensive pipe unit price (pipe unit length cost), friction coefficient, minimum economic flow rate of the pipeline, Financial Internal Rate of Return (FIRR), pipe network operating life, etc. In specific implementation, the data type can be further expanded according to actual needs.

[0085] S4, with the goal of the change in the financial net present value ΔFNPV of the total cost of the water supply network being greater than 0, searching for the pipe diameter optimization scheme of the pipe section on the main control path, and recording the feasible pipe diameter optimization scheme into the database; based on the ΔFNPV calculation result, if there is no optimization space for the water supply network, then go to step S6; based on the searched current preferred pipe diameter optimization scheme, the water supply network is again adjusted and calculated, and if it is necessary to further search for a combined transformation scheme, then go to step S5;

[0086] In the above steps, feasible pipe diameter optimization solutions can be recorded in sequence into the database.

[0087] In some embodiments, step S4 includes:

[0088] S4.1. Determine a current alternative solution set, wherein each alternative solution in the current alternative solution set is: amplify the diameter of a pipe section on the main control path by one level;

[0089] The method for enlarging the diameter of pipe section j on the main control path is: enlarging the diameter of pipe section j by one specification based on the original diameter according to the diameter specification in the standard commercial pipe diameter set, but the maximum diameter cannot exceed the maximum diameter D determined by the minimum economic flow rate. j，max , if the diameter of pipe section j exceeds D after enlarging one specification j，max , then adjust the diameter of the pipe section j to the closest standard commercial pipe diameter set that is less than or equal to D j，max Engineering pipe diameter:

[0090]

[0091] Where D j，max is the maximum pipe diameter of pipe section j determined by the minimum economic flow rate, Q j is the calculated flow rate of pipe segment j after water supply network adjustment (m 3 / s), v j，min It is the minimum economic flow rate of pipe section j, which is generally taken as 0.6m / s.

[0092] D j ≤D j，max , D j ∈D

[0093] Where D j is the diameter of pipe segment j, and D is the set of standard commercial pipe diameters;

[0094] Wherein, N is the number of pipe sections on the main control path.

[0095] S4.2, using ΔFNPV as the evaluation index, solve the ΔFNPV corresponding to each alternative in the current alternative set;

[0096] Assume that the jth alternative is to enlarge the diameter of pipe section j on the main control path by one level. The calculation formula of ΔFNPV corresponding to the jth alternative is as follows:

[0097] ΔFNPV C =[c(D j )-c(D j )′]·l j

[0098]

[0099] ΔFNPV=ΔFNPV C +ΔFNPV O

[0100] Where ΔFNPV is the change in the total financial net present value of the water supply network, in units of RMB, and ΔFNPV C is the change in the present value of the investment cost of water supply network reconstruction, in yuan, which is a negative value; c(D j )′ is the cost per unit length of pipe section j after the change in diameter, in yuan, c(D j ) is the cost per unit length of the pipe diameter of pipe section j before this change, in RMB, using the pipeline investment cost in the "Water Supply and Sewerage Design Manual (Volume 10) Technical Economics (Third Edition)", l j is the length of pipe segment j, in m; ΔFNPV O is the annual net present value of operating cost savings after the transformation of the water supply network, in yuan, a positive value; FIRR is the internal rate of return (%), which is determined by each enterprise; y is the operating life of the water supply network; γ is the density of water, 9800N / m 3 , Q is the total flow rate provided by the water supply pump station to the water supply network, m 3 / s; ΔH j =H j -H' j After the jth alternative is executed, the head loss that can be reduced by changing the pipe diameter of pipe section j is expressed in m (positive), H j is the head loss of pipe section j before the diameter of pipe section j changes, H' j is the head loss of pipe section j after the diameter of pipe section j changes; e is the electricity charge unit: yuan / kW·h; η is the comprehensive energy conversion efficiency (%).

[0101] It should be understood that increasing the pipe diameter by one level will incur corresponding investment costs for the transformation of the water supply network. However, because the pipe diameter is increased, the head loss will be reduced, thereby reducing the head (water supply pressure) of the water plant's water pump station, thereby saving the operating costs of the entire water supply network.

[0102] S4.3. Determine whether there is an alternative with a corresponding ΔFNPV greater than 0 in the current alternative set. If so, find the current preferred pipe diameter optimization scheme, which is the alternative with a corresponding ΔFNPV greater than 0 and the largest in the current alternative set. If the ΔFNPV corresponding to each alternative in the current alternative set is a negative value, indicating that there is no optimization space for the water supply network, go to step S6.

[0103] S4.4, based on the current preferred pipe diameter optimization scheme and considering the minimum free water head constraint of the water supply network, recalculate the water supply network adjustment, optimize the head of the water supply pump station of the water plant, and find the node with the lowest free water head in the water supply network after the current preferred pipe diameter optimization scheme is executed, that is, the control point;

[0104] S4.5, determine whether the control point has changed;

[0105] If the control point remains unchanged, the current preferred pipe diameter optimization scheme is feasible, and the current preferred pipe diameter optimization scheme is recorded in the database; return to step S4.1;

[0106] If the control point changes, go to step S4.6;

[0107] In this step, the content of the current preferred pipe diameter optimization solution and its corresponding ΔFNPV, FIRR and investment cost may be recorded in the database.

[0108] S4.6. Recalculate the annual net present value of operating cost savings after the water supply network transformation based on the current optimal pipe diameter optimization plan ΔFNPV O , and the recalculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O , recalculate the ΔFNPV corresponding to the current preferred pipe diameter optimization scheme; among them, recalculate the annual financial net present value of operating cost savings after the water supply network transformation ΔFNPV O The formula is as follows:

[0109]

[0110] Where ΔH=H A -H' A is the free water head that can be saved in the water supply network after the current optimal pipe diameter optimization scheme is implemented, H A The head of the water supply pump station of the water plant before the current optimal pipe diameter optimization scheme is implemented, m; H' A The head of the water supply pump station of the water plant after the current optimal pipe diameter optimization scheme is executed, m;

[0111] The head of the water supply pump station is obtained by recalculating the water supply network in step S4.4; after the current preferred pipe diameter optimization scheme is executed, the head of the water supply pump station can be lowered while ensuring that the minimum free head constraint of the water supply network is met.

[0112] S4.7. Determine whether the ΔFNPV corresponding to the recalculated current preferred pipe diameter optimization scheme is greater than 0. If it is greater than 0, it means that the current preferred pipe diameter optimization scheme is feasible. Record the current preferred pipe diameter optimization scheme into the database and go to step S6.

[0113] Otherwise, it does not mean that the current preferred pipe diameter optimization solution is completely ineffective, and the process goes to step S5;

[0114] In this step, the content of the current preferred pipe diameter optimization solution and its corresponding ΔFNPV, FIRR and investment cost may be recorded in the database.

[0115] S5. Taking ΔFNPV greater than 0 as the goal, further search for combined transformation schemes and record feasible combined transformation schemes into the database; including:

[0116] Based on the result of the adjustment calculation of the water supply network again in step S4, find all points with lower free water head than the original control point A after the current preferred pipe diameter optimization scheme is executed as candidate control points, and arrange all candidate control points in order from low to high free water head, and record them as C 1 ,C 2 ,…,C m ,…,C M ; Where M is the number of candidate control points;

[0117] Starting from m=1, for each candidate control point, find the shortest distance path from the candidate control point to the water plant as the candidate control path, search for the pipe diameter optimization scheme of the pipe section on the candidate control path, and form a combined transformation scheme together with the current preferred pipe diameter optimization scheme, and record the feasible combined transformation scheme into the database;

[0118] In some embodiments, step S5 includes:

[0119] S5.1. Find candidate control points C m The shortest distance path to the water plant;

[0120] In some embodiments, the Floyd algorithm can be used to find C m The shortest distance path to the water plant;

[0121] S5.2, determine a first set of individual projects, each of which is: m The diameter of a pipe section on the shortest distance path to the water plant is enlarged for primary treatment;

[0122] The method for enlarging the diameter of pipe section x is as follows: enlarging the diameter of pipe section x by one size according to the diameter specification in the standard commercial pipe diameter set, but the maximum diameter cannot exceed the maximum diameter D determined by the minimum economic flow rate. x，max , if the diameter of the pipe section x exceeds D after enlarging one specification x，max , then adjust the diameter of the pipe segment x to the closest standard commercial pipe diameter set that is less than or equal to D x，max Engineering pipe diameter;

[0123] S5.3. Calculate the internal rate of return FIRR for each single project; keep the corresponding internal rate of return FIRR greater than the benchmark internal rate of return FIRR 基准 All individual projects; among them, FIRR 基准 Determined by the enterprise, generally around 8%;

[0124] Among them, solving the internal rate of return FIRR of each single project is a well-known technology. If the initial investment cash flow and the income of each period are known, the internal rate of return FIRR of each single project can be solved by the FIRR function of Excel, which will not be elaborated here.

[0125] S5.4. Arrange all the remaining individual projects in descending order according to their corresponding FIRR, and record them as C m1 ,C m2 ,…,C mL ; Where L is the number of individual projects retained; the head loss that can be reduced after the implementation of each individual project is recorded as h Cm1 ,h Cm2 ,…,h CmL ;

[0126] S5.5 Define the nth single project C mn The free head characteristic array is (h mns ,h Cmn ), where n is 1, 2, …, L, h mns Indicates the starting point of the nth single project, and the calculation formula is:

[0127]

[0128] In the formula, h mns It indicates the head loss that can be reduced after the nth single project is implemented; h Cmi represents the head loss that can be reduced after the execution of the i-th single project; where h A is the maximum head loss that can be reduced after the current optimal pipe diameter optimization scheme is implemented, Represents the candidate control point C m The free head is insufficient. Candidate control point C before executing the current optimal pipe diameter optimization plan m Free water head - the maximum head loss that can be reduced after the current optimal pipe diameter optimization scheme is implemented - the minimum free water head of the water supply network |; It indicates the head loss that can be reduced after the execution of the previous single project of this single project;

[0129] In the above formula, the head loss that can be reduced after the execution of the previous single project of this single project only needs to be calculated when there is a previous single project for this single project.m1 If there is no previous single project, it is not necessary to calculate the head loss that can be reduced after the previous single project of this single project is implemented; for single project C mn , n≥2, its previous single project is C m1 ,C m2 ,…,C m(n-1) ; For example, C 11 The free head characteristic array is (h A -H C1 ,h C11 ), C 12 (h A -H C1 +h C11 ,h C12 ), C 21 (h A -H C2 ,h C21 );

[0130] S5.6 Calculation of C m1 ,C m2 ,…,C mL The end point of which is the nth single project C mn The end point h mne =h mns +h Cmn ; and for C m1 ,C m2 ,…,C mL The endpoints are arranged in ascending order to obtain the endpoint array H 1 ,H 2 ,…,H k ,…,H L ; Among them, H k represents the kth endpoint;

[0131] In the above steps, the starting point of a single project indicates the free water head that can be actually saved by the total renovation plan before the implementation of the single project, and the end point of a single project indicates the free water head that can be actually saved by the total renovation plan after adding the single project.

[0132] S5.7 Initialize k=1;

[0133] S5.8 Find all starting points < H k The single project of the second single project set is recorded as the second single project set, and the change in the financial net present value of the total cost of the water supply network corresponding to all the single projects in the second single project set after execution is calculated, which is recorded as ∑ΔFNPV k ;

[0134] S5.9 Determine ∑ΔFNPV k Is it greater than 0? If ∑ΔFNPVk >0, indicating that the second single project set is feasible, go to step S5.10; otherwise, determine whether k < L, if k < L, set k = k + 1, and go to step S5.8; if k = L, determine whether m < M, if m < M, set m = m + 1, go to step S5.1; if m = M, go to step S6;

[0135] S5.10 Determine H k Is it less than h A , if H k <h A , using the formula Calculate the ΔFNPV corresponding to the combined transformation plan O , and the calculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O , calculate the ΔFNPV corresponding to the combined transformation scheme; record the combined transformation scheme into the database, and go to step S4;

[0136] If H k ≥h A , using the formula Calculate the ΔFNPV corresponding to the combined transformation plan O , and the calculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O , calculate the ΔFNPV corresponding to the combined transformation scheme; record the combined transformation scheme into the database, and go to step S4;

[0137] In this step, the content of the combined transformation plan and its corresponding ΔFNPV, FIRR and investment cost can be recorded in the database.

[0138] In this step, if H k <h A , that is, the free water head that can be saved after the implementation of the combined transformation plan of the current preferred pipe diameter optimization plan and the second single project set is less than the maximum head loss that can be reduced after the implementation of the current preferred pipe diameter optimization plan, indicating that if the head of the water pump station is reduced by h A , candidate control point C m There will be insufficient free water head and it is not enough to fill it by executing the second single project set. That is, after the combined transformation plan is implemented, the point with the lowest free water head, that is, the control point, changes and the control point is converted to C m , while the main control path is switched to C m The shortest distance path from the corresponding candidate control point to the water plant; To ensure the minimum free water head, the free water head that can be effectively saved at this time is H k; So H k Substitute into the corresponding formula to calculate ΔFNPV O and ΔFNPV. If H k ≥h A , that is, the free water head that can be saved after the implementation of the combined transformation plan of the current preferred pipe diameter optimization plan and the second single project set is greater than or equal to the maximum head loss that can be reduced after the implementation of the current preferred pipe diameter optimization plan, indicating that if the head of the water delivery pump station is reduced by h A , candidate control point C m There will be insufficient free water head, but it can be filled by executing the second single project set. That is, after the transformation according to the combined transformation plan, the point with the lowest free water head, i.e. the control point, is still point A. To ensure the minimum free water head, the free water head that can be effectively saved at this time is h A , so h A Substitute into the corresponding formula to calculate ΔFNPV O and ΔFNPV.

[0139] S6. The database outputs a list of feasible pipe diameter optimization solutions.

[0140] Among them, the database outputs a list of feasible pipe diameter optimization solutions in the order of the searched decisions.

[0141] The pipe diameter optimization plan may include the content of the plan and its corresponding ΔFNPV, FIRR and investment cost.

[0142] The pipe diameter optimization solution obtained through the above steps S1-S5 is a solution for replacing the existing pipe with a new pipe with a larger pipe diameter, that is, a pipe replacement solution. The pipe replacement solution can be stored in a pipe replacement solution database.

[0143] In some implementations, the method of the present application may further include:

[0144] Based on the pipe diameter optimization scheme obtained in the above steps S1-S5, the parallel pipeline scheme is selected by considering pipeline laying factors (such as pipe position, traffic, etc.), wherein the parallel pipeline scheme refers to the newly laid pipeline and the existing pipeline jointly transporting and distributing water; the parallel pipeline scheme is recorded in the database.

[0145] In some embodiments, the FIRR and ΔFNPV corresponding to the parallel pipeline solution may be calculated, and the content, FIRR, ΔFNPV and investment cost corresponding to the parallel pipeline solution may be recorded in a database.

[0146] The parallel pipeline plans can be stored in a parallel pipeline plan database.

[0147] By properly selecting parallel pipeline solutions, a more economical solution can be obtained.

[0148] The diameter of the newly laid pipeline is calculated using the principle of equivalent pipe diameter. The so-called equivalent pipe diameter refers to the water delivery capacity of the new larger diameter replacement pipeline (large pipe) in step S6 - the water delivery capacity of the existing pipeline = the water delivery capacity of the newly laid pipeline (small pipe). The water delivery capacity of the newly laid pipeline is calculated; wherein the water delivery capacity is characterized by flow rate.

[0149] Based on the calculated water conveyance capacity of the newly laid pipeline, as well as the length and head loss of the corresponding pipe section, the specific resistance of the corresponding pipe section is calculated according to the following head loss formula;

[0150] h ij =α ij l ij q ij 1.852

[0151] In the above formula, l ij is the length of pipe segment j connected to node i; h ij is the head loss of pipe segment j connected to node j; α ij is the specific resistance of the pipe segment j connected to the node i; q ij is the water delivery capacity of pipe segment j connected to node i, i.e., flow rate.

[0152] Since the specific resistance of a pipe section is related to its diameter, refer to the "Water Supply and Drainage Design Manual (Volume 3) Urban Water Supply (Third Edition)" and its diameter can be deduced based on the specific resistance of the pipe section.

[0153] That is to say, according to the above-mentioned specific resistance α ij The diameter d of the pipe segment j connected to node i can be deduced ij ; will d ij Adjust to the engineering pipe diameter that is closest to and equal to or smaller than it in the standard commercial pipe diameter set.

[0154] Once the pipe diameter is determined, the FIRR and ΔFNPV corresponding to the parallel pipeline solution can be calculated.

[0155] Finally, all pipe diameter optimization schemes are output, including pipeline replacement schemes and parallel pipeline schemes, that is, the corresponding contents, FIRR, ΔFNPV and investment costs of the pipeline replacement schemes and parallel pipeline schemes.

[0156] Decision makers can determine the optimal solution for water supply network reconstruction based on the parameters and constraints of each solution (including the feasibility of project implementation, available investment budget, etc.).

[0157] The embodiment of the present application also provides an electronic device, including: a memory and a processor;

[0158] The memory is used to store computer programs;

[0159] The processor is used to call the computer program to execute the method as described above.

[0160] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed on an electronic device, the electronic device implements the method as described above.

[0161] An embodiment of the present application further provides a computer program product, including a computer program. When the computer program is executed on an electronic device, the electronic device implements the method as described above.

[0162] The embodiments of the present application also provide a system, an electronic device, a computer-readable storage medium, and a computer program product. The specific implementation methods can refer to the specific embodiments of the above methods and will not be repeated here.

[0163] Obviously, those skilled in the art should understand that the above-mentioned units or steps of the present application can be implemented by a general-purpose computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. In this way, the present application is not limited to any specific combination of hardware and software.

[0164] The above description of the embodiments of the present application is only a partial embodiment of the present application, which is used to enable professionals in the field to implement or use the content of the present application, and is not used to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A water supply network optimization and transformation method based on hierarchical optimization, It is characterized in that include: S1. Obtain the current water supply network topology map; S2. Based on the current water supply network topology, the water supply network is adjusted and calibrated to find the node with the lowest free water head in the water supply network as the control point, which is recorded as control point A. The free water head of control point A is equal to the minimum free water head of the water supply network. S3, find the shortest distance path from control point A to the water plant as the main control path; S4, with the goal of the change in the financial net present value ΔFNPV of the total cost of the water supply network being greater than 0, searching for the pipe diameter optimization scheme of the pipe section on the main control path, and recording the feasible pipe diameter optimization scheme into the database; based on the ΔFNPV calculation result, if there is no optimization space for the water supply network, then go to step S6; based on the searched current preferred pipe diameter optimization scheme, the water supply network is again adjusted and calculated, and if it is necessary to further search for a combined transformation scheme, then go to step S5; S5. Taking ΔFNPV greater than 0 as the goal, further search for combined transformation schemes and record feasible combined transformation schemes into the database; including: Based on the result of the adjustment calculation of the water supply network again in step S4, find all points with lower free water head than the original control point A after the current preferred pipe diameter optimization scheme is executed as candidate control points, and arrange all candidate control points in order from low to high free water head, and record them as C 1 ,C 2 ,…,C m ,…,C M ; Where M is the number of candidate control points; Starting from m=1, for each candidate control point, find the shortest distance path from the candidate control point to the water plant as the candidate control path, search for the pipe diameter optimization scheme of the pipe section on the candidate control path, and form a combined transformation scheme together with the current preferred pipe diameter optimization scheme, and record the feasible combined transformation scheme into the database; S6. The database outputs a list of feasible pipe diameter optimization solutions.

2. The method according to claim 1, It is characterized in that In step S3 and step S5, the Floyd algorithm is used to find the shortest distance path from control point A and the candidate control point to the water plant.

3. The method according to claim 1, It is characterized in that In the step S4, the FIRR, ΔFNPV and investment cost corresponding to the feasible pipe diameter optimization scheme are calculated, and the content of the feasible pipe diameter optimization scheme, the corresponding FIRR, ΔFNPV and investment cost are recorded in the database; In step S5, the FIRR, ΔFNPV and investment cost corresponding to the feasible combined transformation scheme are calculated, and the content of the feasible combined transformation scheme, the corresponding FIRR, ΔFNPV and investment cost are recorded in the database.

4. The method according to claim 1, It is characterized in that The step S4 comprises: S4.

1. Determine a current alternative solution set, wherein each alternative solution in the current alternative solution set is: enlarging the diameter of a pipe section on the main control path by one level; S4.2, using ΔFNPV as the evaluation index, solve the ΔFNPV corresponding to each alternative in the current alternative set; Assume that the jth alternative is to enlarge the diameter of pipe section j on the main control path by one level. The calculation formula of ΔFNPV corresponding to the jth alternative is as follows: ΔFNPV C =[c(D j )-c(D j )’]·l j ΔFNPV=ΔFNPV C +ΔFNPV O Where, ΔFNPV C is the present value of the investment cost for water supply network reconstruction, which is a negative value; c(D j )′ is the cost per unit length of pipe section j after the change in diameter, c(D j ) is the cost per unit length of pipe section j before the change in pipe diameter, l j is the length of pipe segment j; ΔFNPV O is the annual net present value of operating cost savings after the transformation of the water supply network, which is a positive value; FIRR is the internal rate of return of the enterprise; y is the operating life of the water supply network; γ is the density of water; Q is the total flow provided by the water pump station to the water supply network; ΔH j =H j -H' j H is the head loss that can be reduced by changing the pipe diameter of pipe section j after the jth alternative is implemented; j is the head loss of pipe section j before the diameter of pipe section j changes, H' j is the head loss of pipe section j after the diameter of pipe section j changes; e is the electricity fee, η is the comprehensive energy conversion efficiency; S4.

3. Determine whether there is an alternative with a corresponding ΔFNPV greater than 0 in the current alternative set. If so, find the current preferred pipe diameter optimization scheme, which is the alternative with a corresponding ΔFNPV greater than 0 and the largest in the current alternative set. If the ΔFNPV corresponding to each alternative in the current alternative set is a negative value, indicating that there is no optimization space for the water supply network, go to step S6. S4.4, based on the current preferred pipe diameter optimization scheme and considering the minimum free water head constraint of the water supply network, recalculate the water supply network adjustment, optimize the head of the water supply pump station of the water plant, and find the node with the lowest free water head in the water supply network after the current preferred pipe diameter optimization scheme is executed, that is, the control point; S4.5, determine whether the control point has changed; If the control point remains unchanged, the current preferred pipe diameter optimization scheme is feasible, and the current preferred pipe diameter optimization scheme is recorded in the database; return to step S4.1; If the control point changes, go to step S4.6; S4.

6. Recalculate ΔFNPV for the current optimal pipe diameter optimization solution O , and the recalculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O Recalculate the ΔFNPV corresponding to the current preferred pipe diameter optimization solution; where ΔFNPV is recalculated O The formula is as follows: Where ΔH=H A -H' A is the free water head that can be saved in the water supply network after the current optimal pipe diameter optimization scheme is implemented, H A The head of the water supply pump station of the water plant before the current optimal pipe diameter optimization scheme is implemented; H' A The head of the water supply pump station of the water plant after the current optimal pipe diameter optimization scheme is implemented; S4.

7. Determine whether the ΔFNPV corresponding to the recalculated current preferred pipe diameter optimization scheme is greater than 0. If it is greater than 0, it means that the current preferred pipe diameter optimization scheme is feasible. The current preferred pipe diameter optimization scheme is recorded in the database and go to step S6; otherwise, go to step S5.

5. The method according to claim 1, It is characterized in that In the step S5, Starting from m=1, for each candidate control point, find the shortest distance path from the candidate control point to the water plant as the candidate control path, search for the pipe diameter optimization scheme of the pipe section on the candidate control path, and form a combined transformation scheme together with the current preferred pipe diameter optimization scheme. Record the feasible combined transformation scheme into the database, including: S5.

1. Find candidate control points C m The shortest distance path to the water plant; S5.2, determine a first set of individual projects, each of which is: m The diameter of a pipe section on the shortest distance path to the water plant is enlarged for primary treatment; S5.

3. Calculate the internal rate of return FIRR for each single project; keep the corresponding internal rate of return FIRR greater than the benchmark internal rate of return FIRR 基准 All individual projects; S5.

4. Arrange all the remaining individual projects in descending order according to their corresponding FIRR, and record them as C m1 ,C m2 ,…,C mL ; Where L is the number of individual projects retained; the head loss that can be reduced after the implementation of each individual project is recorded as h Cm1 ,h Cm2 ,…,h CmL ; S5.5 Define the nth single project C mn The free head characteristic array is (h mns ,h Cmn ), where n is 1, 2, …, L, h mns Indicates the starting point of the nth single project, and the calculation formula is: In the formula, h Cmn It indicates the head loss that can be reduced after the nth single project is implemented; h Cmi represents the head loss that can be reduced after the execution of the i-th single project; where h A is the maximum head loss that can be reduced after the current optimal pipe diameter optimization scheme is implemented, Represents the candidate control point C m The free head is insufficient. =|Candidate control point C before the current optimal pipe diameter optimization scheme is executed m Free water head - the maximum head loss that can be reduced after the current optimal pipe diameter optimization scheme is implemented - the minimum free water head of the water supply network |; It indicates the head loss that can be reduced after the execution of the previous single project of this single project; S5.6 Calculation of C m1 ,C m2 ,…,C mL The end point of which is the nth single project C mn The end point h mne =h mns +h Cmn ; and for C m1 ,C m2 ,…,C mL The endpoints are arranged in ascending order to obtain the endpoint array H 1 ,H 2 ,…,H k ,…,H L ; Among them, H k represents the kth endpoint; S5.7 Initialize k=1; S5.8 Find all starting points < H k The single project of the second single project set is recorded as the second single project set, and the change in the financial net present value of the total cost of the water supply network corresponding to all the single projects in the second single project set after execution is calculated, which is recorded as ∑ΔFNPV k ; S5.9 Determine ∑ΔFNPV k Is it greater than 0? If ∑ΔFNPV k >0, indicating that the second single project set is feasible, go to step S5.10; otherwise, determine whether k < L, if k < L, set k = k + 1, and go to step S5.8; if k = L, determine whether m < M, if m < M, set m = m + 1, go to step S5.1; if m = M, go to step S6; S5.10 Determine H k Is it less than h A , if H k <h A , using the formula Calculate the ΔFNPV corresponding to the combined transformation plan O , and the calculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O , calculate the ΔFNPV corresponding to the combined transformation scheme; record the combined transformation scheme into the database, and go to step S4; If H k ≥h A , using the formula Calculate the ΔFNPV corresponding to the combined transformation plan O , and the calculated ΔFNPV O Substitute into the formula ΔFNPV = ΔFNPV C +ΔFNPV O , calculate the ΔFNPV corresponding to the combined transformation scheme; record the combined transformation scheme into the database, and go to step S4.

6. The method according to claim 1, It is characterized in that Also includes: Based on the pipe diameter optimization solution obtained in steps S1-S5, i.e., the pipeline replacement solution, a parallel pipeline solution is selected taking into account pipeline laying factors. The parallel pipeline solution means that the newly laid pipeline and the existing pipeline jointly transport and distribute water; Record parallel pipeline plans to the database.

7. The method according to claim 6, It is characterized in that Step S6 includes: outputting all pipe diameter optimization schemes, including the content of the replacement pipeline scheme and the parallel pipeline scheme, and the corresponding FIRR, ΔFNPV and investment cost.

8. An electronic device, It is characterized in that include: Memory and processor; The memory is used to store computer programs; The processor is configured to call the computer program to execute the method according to any one of claims 1 to 7.

9. A computer-readable storage medium, It is characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed on an electronic device, the electronic device implements the method according to any one of claims 1 to 7.

10. A computer program product comprising a computer program, It is characterized in that When the computer program is executed on an electronic device, the electronic device implements the method according to any one of claims 1 to 7.

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