Combined optimization method and equipment for construction and reconstruction of power distribution network frame in constructed area based on mixed integer programming, and storage medium

Abstract

The invention discloses a combined optimization method and equipment for construction and transformation of a built-up area power distribution network frame based on mixed integer programming and a storage medium. The method comprises the following steps: step 1, constructing a combined optimization solving framework for construction and transformation of the built-up area power distribution network frame; 2, calculating the upper and lower bounds of the number of outgoing lines of the newly-built line; 3, dividing a power supply range of a newly-built line by taking spatial distance characteristics and a load out-of-limit improvement effect into consideration in the comprehensive built area; and step 4, solving based on the objective function of the new line planning and original line reconstruction joint optimization model and the constraint condition of the objective function, thereby obtaining a new line planning and original line reconstruction joint optimization scheme. An apparatus and storage medium for implementing a method process. According to the method, the power supply range of the newly-built line can be accurately divided, and the optimal line layout of safe operation of each line can be met.

Description

Technical Field

[0001] The present invention relates to the field of distribution line planning methods, and in particular to a method, device and storage medium for joint optimization of construction and transformation of distribution network frames in built-up areas based on mixed integer programming. Background Art

[0002] With the rapid growth of terminal energy electrification, the scale and number of loads are increasing rapidly, and the distribution of loads in distribution networks is also becoming uneven. This can lead to problems such as capacity overruns. To effectively support the carrying and access of large-scale loads, it is necessary to develop a practical joint optimization method for the construction and transformation of distribution networks in built-up areas.

[0003] At present, domestic and foreign scholars mainly focus on new construction areas in line planning research, and conduct line planning for the long-term vision year. Some researchers have proposed a grid-based planning approach, defined the power supply grid and power supply units, and proposed a "bottom-up" planning principle. Based on this, some researchers have proposed a "block chain" networking form, and carried out the division of power supply blocks and automatic wiring within the blocks. In summary, existing research is mainly based on the concept of grid-based planning, and conducts wiring planning for the long-term vision year. However, only studying the grid planning problem for the long-term vision year is difficult to effectively respond to the source and load development needs of the distribution network. It is urgent to propose a method for wiring in built-up areas and adjusting the power supply range of lines.

[0004] Current research on automated routing technologies for existing distribution networks provides some insights for planning and upgrading them. However, most approaches abstract line layout and source-load distribution into a standard topology, ignoring geographic features such as buildings, streets, and obstacles. This makes it difficult to ensure the rationality of planning schemes in practical engineering. Research is still needed to determine how to balance economic efficiency and safety, fully considering actual geographic information and source-load distribution characteristics, and automatically route lines in built-up areas.

[0005] Currently, most researchers studying automated wiring solutions restrict the routing structure to radial or mesh configurations, formulating the problem as a graph theory problem, including minimum spanning trees, multiple traveling salesmen, and capacity-constrained vehicle routing. These researchers employ heuristic or meta-heuristic methods, such as ant colony algorithms, mileage-saving algorithms, genetic algorithms, and simulated annealing algorithms, to solve the problem. This often results in suboptimal solutions, and the quality of the solutions is difficult to assess. Mathematical optimization methods offer rigorous theoretical solutions, essentially using a "branch and bound" approach to converge the problem. These methods are the most precise algorithms for solving graph theory problems. Research is needed to develop appropriate mathematical optimization methods to develop high-quality distribution network construction and renovation plans for large-scale engineering projects in built-up areas.

[0006] Therefore, how to propose a joint optimization method for the construction and transformation of distribution network in built-up areas that takes into account the temporal and spatial distribution characteristics of loads and the operating relationship of each medium-voltage feeder to ensure the safe and stable operation of the distribution network is an urgent problem to be solved by technical personnel in this field. Summary of the Invention

[0007] To address the shortcomings and deficiencies of existing technologies, this paper proposes a method, device, and storage medium for joint optimization of distribution network construction and renovation in built-up areas based on mixed integer programming. Given the numerous planning objectives and large dimensionality of decision variables in built-up areas, and considering the dynamic adjustment of load attribution and load characteristic matching, this paper proposes a joint optimization model for new line planning and existing line renovation, along with a solution method based on mixed integer programming, to achieve precise demarcation of the power supply range of new lines and optimal line layout that ensures the safe operation of each line.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The joint optimization method for construction and transformation of distribution network in built areas based on mixed integer programming is as follows:

[0010] Step 1: Obtain existing grid and line parameters, loads, and geographic data in the built-up area, and build a joint optimization solution framework for the construction and transformation of the distribution network in the built-up area;

[0011] Step 2: Calculate the lower limit of the number of outgoing lines of the new line based on the power balance results of the substation in the built area, and calculate the upper limit of the number of outgoing lines of the new line based on the source-load distribution characteristics within the power supply range of the substation in the built area;

[0012] Step 3: Consider the spatial distance characteristics and load overload improvement effects of the built-up area, divide the power supply range of the new line, and form several feeder sub-blocks and their combinations;

[0013] Step 4: Based on the upper and lower bounds of the number of outgoing lines of the new line obtained in step 2, and the power supply range of the new line determined in step 3, establish the objective function and constraints of the objective function of the joint optimization model of new line planning and existing line transformation, and solve the objective function under the solution framework constructed in step 1, thereby obtaining the joint optimization plan of new line planning and existing line transformation.

[0014] Furthermore, the process of step 1 is as follows:

[0015] By traversing the interval of the number of newly built lines, the generation process of the number of newly built lines is decoupled from other processes.

[0016] Determine the power supply range of each new line based on the number of new lines to be selected;

[0017] Based on the power supply range division results of new lines taking into account the spatial distribution of sources and loads, the optimal new line layout planning scheme under the corresponding scheme is generated; based on the scheme of each group of new line layouts, the optimal grid transformation scheme under the corresponding scheme is generated; by comparing the number of new lines in each group and the total cost of automatic distribution network wiring under the corresponding power supply range division scheme, the scheme with the lowest new line planning and existing line transformation costs is selected.

[0018] Furthermore, in step 2, the lower bound of the number of new lines is as follows:

[0019]

[0020] Where W max L is the maximum value of the sum of the time sequence characteristics of all loads within the power supply range of the substation. max is the maximum transmission capacity of the line, cosφ is the power factor, m is the number of new lines required within the power supply range of the substation, I is the number of existing medium-voltage lines within the power supply range of the substation, and [] is the rounding-down symbol.

[0021] Furthermore, in step 2, with the constraint that the combined load rate of all medium-voltage lines does not exceed 50%, as many unconnected sources and load points as possible are connected to the grid. Based on the adjusted scale and distribution of unconnected sources and loads, the upper bound of the number of new lines to be built is calculated as shown in the following formula:

[0022] minQ out

[0023]

[0024] φ q,j ≤X q,j

[0025]

[0026] Where Q out Indicates the number of newly added load points that are not connected to the grid, φ q,j A 0-1 variable used to indicate whether the newly added load point q is incorporated into the power supply range of line j; φ q,j =1 indicates that the newly added load point q is incorporated into the power supply range of line j; Q is the total number of newly added load points; P j,t P represents the sum of the original load point powers of the line at time t; q,t is the power of the newly added load point q at time t; X q,j Represents the adjacent relationship between the newly added load point q and line j.

[0027] Furthermore, the process of step 3 is as follows:

[0028] 3.1) Assign each newly added load point to the power supply range of each existing line with the shortest European distance, calculate the load factor of each line at this time, and evaluate the over-limit situation of each existing line;

[0029] 3.2) Divide the substation's overall power supply range into U local power supply areas, using two lines that do not cross the limit as boundaries;

[0030] 3.3) Sequentially locate the construction locations of each new line in the local power supply area with the highest ratio of load characteristic peak to total line capacity, and determine the number of new lines required for each local power supply area;

[0031] 3.4) Analyze each local power supply area and sequentially calculate the extent to which the construction of new lines within each feeder sub-block combination block within the local power supply area can reduce the load peak of the over-limit lines on both sides. Determine the number of new lines required in each feeder sub-block combination block within each local power supply area;

[0032] 3.5) Use the centerline method to divide the load range supplied by each new line in each feeder sub-block;

[0033] 3.6) For the overall power supply range of the substation, combine the new line supply plans obtained in these U local power supply areas to form a plan for all new lines to supply the load;

[0034] 3.7) After obtaining all feasible new line power supply range plans for a single substation, under the same load rate upper bound, requiring the sum of all radial lines in the area to be an even number and limiting the sum of the total number of lines in the three substations to be an even number, through permutations and combinations, obtain the power supply range plans for new lines for multiple substations.

[0035] Furthermore, in step 4, the objective function of the joint optimization model for new line planning and existing line reconstruction is as follows:

[0036] minZ=Z1+Z2+Z3+Z4

[0037]

[0038]

[0039] Where: Z is the total cost of line planning; Z1 is the total cost of the trunk line and branch line when planning a new line; γ is the equal annual value coefficient; x he,k Indicates whether a trunk line is built between nodes h and e in the kth feeder sub-block combination block; y he,k Indicates whether a branch line is constructed between nodes h and e in the kth feeder sub-block combination block; r0 represents the discount rate; a is the planned depreciation year; Φ k ,Ωk 、A k are the sets of street nodes, access nodes, and load nodes within the kth feeder sub-block combination block; α and β are the construction costs of the trunk line and branch line per unit length, respectively; l he,k is the line length between nodes h and e in the kth feeder sub-block combination block. Z2 is the total cost of the branch line required to add the new load point to the medium voltage line; Z3 is the total cost of the branch line required to adjust the original load point, and Z4 is the total cost of the tie line transformation; l q,j The length of the branch line required to add the new load q to the medium voltage line j; φ i,j is the decision variable indicating whether the original load i is assigned to the medium voltage line j. i,j =1, otherwise φ i,j =0;l i,j is the length of the branch line required to build when the original load i belongs to the medium voltage line j. It is worth noting that if the load i initially belongs to the line j, then set l i,j = 0, indicating that there is no additional cost after it is attributed to line j; δ m,n Indicates the connection between the terminal nodes of line m and line n, that is, whether the tie line is built, δ m,n =1 indicates the construction of the tie line between line m and line n; l m,n is the minimum distance along the street between the end nodes of route m and route n.

[0040] Furthermore, in step 4, the constraints include line radial constraints, connectivity constraints, line capacity constraints, new load point topology constraints, existing load point topology constraints, and tie line topology constraints.

[0041] An electronic device includes a processor and a memory. When program instructions in the memory are read and run by the processor, the above-mentioned joint optimization method for construction and transformation of a built-up area distribution network based on mixed integer programming is executed.

[0042] A storage medium stores program instructions. When the program instructions in the storage medium are read and run, the above-mentioned joint optimization method for construction and transformation of built-up area distribution network based on mixed integer programming is executed.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) The method for dividing the power supply range of a newly built line designed in the present invention can fully consider the impact of load attribution adjustment on the reduction of the load rate level of the over-limit line, and realize the accurate division of the power supply range of the newly built line.

[0045] (2) The collaborative optimization model and solution method for planning and renovating new lines and existing lines designed in this invention can fully consider geographic information, existing grid layout and source-load distribution characteristics to achieve the optimal line layout that meets the safe operation of each line. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a flowchart of the integrated optimization framework for transformation and wiring proposed in the present invention.

[0047] Figure 2 Schematic diagram of a feeder sub-block and a feeder sub-block combination block in a case of applying the present invention.

[0048] Figure 3 This is the geographic information and line layout diagram of the example before transformation in the case of applying the present invention.

[0049] Figure 4 This is a schematic diagram of the line planning and transformation results and power supply range under the optimal solution after transformation in the case of applying the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the accompanying drawings and examples.

[0051] like Figure 1 As shown, this embodiment discloses a joint optimization method for the construction and transformation of the built-up area distribution network based on mixed integer programming. In the method, a joint optimization solution framework for the construction and transformation of the built-up area distribution network is first established, and the upper and lower bounds of the number of new line outlets are calculated (the first optimization problem), as well as the power supply range of the new line is divided (the second optimization problem). Finally, a joint optimization model for the planning of new lines and the transformation of existing lines is constructed and solved (the third optimization problem). The specific process is as follows:

[0052] Step 1: Obtain existing grid and line parameters, loads, and geographic data in the built-up area, and build a joint optimization solution framework for the construction and transformation of the distribution network in the built-up area.

[0053] In this embodiment, the solution framework constructed decouples the two problems of dividing the power supply range of new lines and the joint optimization of new line planning and existing line transformation. It splits the solution of complex problems into the combined solution of multiple optimization problems. The optimal new line planning and existing line transformation results are obtained through continuous iteration of the three optimization problems of calculating the number of new line outlets, dividing the power supply range of new lines, and planning new lines and optimizing the layout of existing line transformation. The solution framework construction process is as follows:

[0054] 1.1) Generate a set of candidate routes for new construction.

[0055] In order to achieve the overall optimal planning solution, it is necessary to decouple each link. Considering that the number of new routes is a discrete countable integer, this embodiment decouples the new route number set generation link from other links by traversing the new route number interval.

[0056] 1.2) Division of power supply range for new lines.

[0057] Based on the number of new lines to be selected, this embodiment determines the power supply range of each new line for subsequent new line layout planning. This can reduce the calculation scale when planning the new line layout and reduce the cost of line construction during planning.

[0058] 1.3) Layout planning of new lines and renovation of existing lines.

[0059] This embodiment generates an optimal layout plan for new lines based on the power supply range division results of the new lines, taking into account the spatial distribution of sources and loads. Based on the power supply range division and layout planning results of the new lines, the existing grid is modified. Firstly, branch lines are cut and modified to adjust the source and load allocation to ensure safe operation of the lines under load factor constraints. Secondly, interconnection lines are modified to meet the construction requirements of "closed-loop design, open-loop operation" and connect the lines.

[0060] Based on each set of new line layout options, the optimal grid reconstruction plan is generated for that specific scenario. The total cost of automatic distribution network wiring under each set of new lines and their corresponding power supply range division schemes is compared, and the plan with the lowest cost for both new line planning and existing line reconstruction is selected.

[0061] Step 2: Calculate the upper and lower bounds of the number of lines for the new line.

[0062] Before dividing the power supply range of the subsequent new lines, this embodiment first generates a set of candidate new lines based on the temporal and spatial characteristics of the load within the power supply range of the substation for subsequent calculations.

[0063] (A) Calculate the lower limit of the number of outgoing lines for new lines based on the power balance results of the substations in the built area, as shown in the following formula:

[0064]

[0065] Where W max L is the maximum value of the sum of the time sequence characteristics of all loads within the power supply range of the substation. max is the maximum transmission capacity of the line, cosφ is the power factor, m is the number of new lines required within the substation's power supply range, and I is the number of existing medium-voltage lines within the substation's power supply range. [] denotes the rounding symbol.

[0066] (B) Calculate the upper limit of the number of outgoing lines of the new line based on the source and load distribution characteristics within the power supply range of the substation in the built area. The process is as follows:

[0067] B1) With the combined load rate of all medium-voltage lines not exceeding 50%, as many unconnected source load points as possible are connected to the grid, as shown in the formula:

[0068] minQ out

[0069]

[0070] φ q,j ≤X q,j

[0071]

[0072] Where Q out Indicates the number of newly added load points that are not connected to the grid, φ q,j A 0-1 variable used to indicate whether the newly added load point q is incorporated into the power supply range of line j; φ q,j =1 indicates that the newly added load point q is incorporated into the power supply range of line j; Q is the total number of newly added load points; P j,t P represents the sum of the original load point powers of the line at time t; q,t is the power of the newly added load point q at time t; X q,j Represents the adjacent relationship between the newly added load point q and line j.

[0073] B2) Based on the adjusted scale and distribution of unconnected sources and loads, the upper limit of the number of new lines to be built is calculated as shown in the following formula:

[0074]

[0075]

[0076] Where Y q,k Indicates whether the newly added load point q is within the region k. If the load point q is within the region k, then Y q,k =1;W k,max is the maximum value of the sum of the timing characteristics of all non-grid-connected loads in the kth region; K is the total number of regions.

[0077] Step 3: Consider the spatial distance characteristics and load overload improvement effects of the built-up area, divide the power supply range of the new line, and form the following Figure 2 The process of several feeder sub-blocks and their combinations is as follows:

[0078] 3.1) Assign each newly added load point to the power supply range of each existing line with the shortest European distance, calculate the load factor of each line at this time, and evaluate the over-limit situation of each existing line;

[0079] 3.2) Divide the substation's overall power supply range into U local power supply areas, using two lines that do not cross the limit as boundaries;

[0080] 3.3) Sequentially locate the construction locations of each new line in the local power supply area with the highest ratio of load characteristic peak to total line capacity, and determine the number of new lines required for each local power supply area;

[0081] 3.4) Analyze each local power supply area and sequentially calculate the extent to which the construction of new lines within each feeder sub-block combination block within the local power supply area can reduce the load peak of the over-limit lines on both sides. Determine the number of new lines required in each feeder sub-block combination block within each local power supply area;

[0082] 3.5) Use the centerline method to divide the load range supplied by each new line in each feeder sub-block;

[0083] 3.6) For the overall power supply range of the substation, combine the new line supply plans obtained in these U local power supply areas to form a plan for all new lines to supply the load;

[0084] 3.7) After obtaining all feasible new line power supply range plans for a single substation, under the same upper load rate limit, since the distribution network lines must follow the principle of "closed-loop design, open-loop operation", the sum of all radial lines in the area must be an even number, and the sum of the total number of lines in the three substations must be an even number. Through permutations and combinations, the power supply range plans for the new lines of multiple substations are obtained.

[0085] Step 4: Based on the upper and lower bounds of the number of outgoing lines of the new line obtained in step 2, and the power supply range of the new line determined in step 3, establish the objective function and constraints of the objective function of the joint optimization model of new line planning and existing line transformation, and solve the objective function under the solution framework constructed in step 1, thereby obtaining the joint optimization plan of new line planning and existing line transformation.

[0086] In this embodiment, the nodes in the planning area are divided into road nodes, load nodes, and load access location nodes. Based on the network topology description method, the 0-1 variable x he,k and y he,k This algorithm describes whether trunk and branch lines are needed around each feeder sub-block. Using mixed integer programming, it develops a joint optimization model for planning new lines and renovating existing lines, solving the problem of optimizing the layout of distribution grids over large areas. This model can be solved using the commercial CPLEX solver.

[0087] The objective function of the joint optimization model for new line planning and existing line reconstruction established in this embodiment is shown in the following formula:

[0088] minZ=Z1+Z2+Z3+Z4

[0089]

[0090] Where: Z is the total cost of line planning; Z1 is the total cost of the trunk line and branch line when planning a new line; γ is the equal annual value coefficient; x he,k Indicates whether a trunk line is built between nodes h and e in the kth feeder sub-block combination block; y he,k Indicates whether a branch line is constructed between nodes h and e in the kth feeder sub-block combination block; r0 represents the discount rate; a is the planned depreciation year; Φ k ,Ω k 、A k are the sets of street nodes, access nodes, and load nodes within the kth feeder sub-block combination block; α and β are the construction costs of the trunk line and branch line per unit length, respectively; l he,k is the line length between nodes h and e in the kth feeder sub-block combination block. Z2 is the total cost of the branch line required to add the new load point to the medium voltage line; Z3 is the total cost of the branch line required to adjust the original load point, and Z4 is the total cost of the tie line transformation; l q,j The length of the branch line required to add the new load q to the medium voltage line j; φ i,j is the decision variable indicating whether the original load i is assigned to the medium voltage line j. i,j =1, otherwise φ i,j =0;l i,j is the length of the branch line required to build when the original load i belongs to the medium voltage line j. It is worth noting that if the load i initially belongs to the line j, then set l i,j = 0, indicating that there is no additional cost after it is attributed to line j; δ m,n Indicates the connection between the terminal nodes of line m and line n, that is, whether the tie line is built, δ m,n =1 indicates the construction of the tie line between line m and line n; l m,n is the minimum distance along the street between the end nodes of route m and route n.

[0091] In this embodiment, the constraints of the objective function include line radial constraints, connectivity constraints, line capacity constraints, new load point topology constraints, existing load point topology constraints, and tie line topology constraints. Specific descriptions are as follows:

[0092] a) Line radial constraint.

[0093] During the distribution network planning process, the emergence of a ring structure should be avoided, that is, each load point has only one upper point to supply power to it, as shown in the following formula:

[0094]

[0095] In the formula is the number of all load points in the kth feeder sub-block.

[0096] b) Connectivity constraints.

[0097] In the distribution network, the lines should be connected, and the following constraints apply to all nodes:

[0098]

[0099] Where: b he 、b eh is an auxiliary variable. If node h is the parent node of e, then b he =1, otherwise 0, if node e is the parent node of h, then b eh =1, otherwise 0; E is the set of all lines; A D is a set of power nodes. The above constraint indicates that the power node has no parent node.

[0100] If the line is not connected to the power node, the above spanning tree constraint is incomplete. The connectivity between lines and between lines and loads is described by virtual power flow, as shown in the following formula:

[0101]

[0102] Where: F he is the virtual power flow demand from node h to node e; F eh is the virtual power flow demand from node e to node h; D h is the virtual load demand of node h; N (h) is the set of all nodes connected to node h; M is a relatively large number

[0103] c) Line capacity constraint is shown in the following formula:

[0104]

[0105] Where, P i,t is the power of the original load point i at time t.

[0106] d) The new load point topology constraint is shown in the following formula:

[0107]

[0108] φ q,j ≤X q,j

[0109] Among them, the first item means that the newly added load point q can only be supplied by one medium-voltage line; the second item means that the newly added load point q can only be assigned to two adjacent lines based on the principle of non-crossing power supply.

[0110] e) The original load point topology constraint is shown in the following formula:

[0111]

[0112] φ i,j ≤X i,j

[0113] Among them, the first item means that the original load point i can only be supplied by one medium voltage line; the second item means that the original load point i can only be assigned to two adjacent lines based on the principle of non-cross power supply. i,j is the connection relationship variable, connected is 1, and disconnected is 0.

[0114] f) Tie line topology constraints are shown in the following formula:

[0115]

[0116] δ m,n ≤H m,n

[0117] Where H m,n is the adjacent relationship between line m and line n, H m,n =1 means that line m is adjacent to line n, and vice versa. The first term means that a line can only be connected to another medium voltage line; the second term means that only adjacent lines can be connected.

[0118] This embodiment also discloses an electronic device, including a processor and a memory. When the program instructions in the memory are read and executed by the processor, steps 1 to 4 of the above-mentioned joint optimization method for construction and transformation of built-up regional distribution network based on mixed integer programming are executed.

[0119] This embodiment also discloses a storage medium storing program instructions. When the program instructions in the storage medium are read and executed, steps 1 to 4 of the above-mentioned method for joint optimization of construction and transformation of distribution network in a built-up area based on mixed integer programming are executed.

[0120] The following case is based on the topology Figure 3 The built-up area distribution network shown in FIG is used as an example for explanation. Figure 3It includes 18 existing load points, each with a load scale of 0.3MW, and 14 new source-load grid-connected points, each with a load scale of 0.2MW, and a photovoltaic scale of 0.1MW.

[0121] The combined optimization method for construction and transformation of the built-up area distribution network based on mixed integer programming described in this embodiment is applied to Figure 3 The optimal planning and transformation cost of the built-up area distribution network under different outgoing line numbers is shown in Table 1:

[0122] Table 1 Optimal planning and transformation scheme under different number of outgoing lines

[0123]

[0124] Table 1 shows that in Plan 1, when the number of new substation lines is too small (only one), the requirement for full grid connection of distributed PV cannot be met, resulting in a no-solution scenario. Comparing Plans 2-6, it can be seen that when the number of new substation lines is two, the optimal combination of existing grid reconstruction and new line layout is achieved, effectively resolving the problem of poor economic efficiency caused by relying solely on new grid investment to accommodate distributed PV.

[0125] Figure 4 Display the line planning and transformation results and power supply range diagram under the optimal solution after transformation, Figure 4 It can be seen that all distribution networks are distributed along the streets in a radial pattern, and a "closed-loop design, open-loop operation" planning scheme is formed through connecting lines, which effectively supports the orderly planning and design of the distribution network.

[0126] The respective sequence numbers in the above-described embodiments are merely for description and do not represent the assembly or sequential order of the various components during use. Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the application can adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0127] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0128] The above descriptions are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A joint optimization method for construction and transformation of distribution network in built areas based on mixed integer programming, characterized by: The process is as follows: Step 1: Obtain existing grid and line parameters, loads, and geographic data in the built-up area, and build a joint optimization solution framework for the construction and transformation of the distribution network in the built-up area; Step 2: Calculate the lower limit of the number of outgoing lines of the new line based on the power balance results of the substation in the built area, and calculate the upper limit of the number of outgoing lines of the new line based on the source-load distribution characteristics within the power supply range of the substation in the built area; Step 3: Consider the spatial distance characteristics and load overload improvement effects of the built-up area, divide the power supply range of the new line, and form several feeder sub-blocks and their combinations; Step 4: Based on the upper and lower bounds of the number of outgoing lines of the new line obtained in step 2, and the power supply range of the new line determined in step 3, establish the objective function and constraints of the objective function of the joint optimization model of new line planning and existing line transformation, and solve the objective function under the solution framework constructed in step 1, thereby obtaining the joint optimization plan of new line planning and existing line transformation.

2. The method for joint optimization of construction and transformation of distribution network in built areas based on mixed integer programming according to claim 1 is characterized in that: Step 1 process is as follows: By traversing the interval of the number of newly built lines, the generation process of the number of newly built lines is decoupled from other processes. Determine the power supply range of each new line based on the number of new lines to be selected; Based on the power supply range division results of the new line considering the spatial distribution of sources and loads, the optimal layout planning scheme of the new line under the corresponding scheme is generated; Based on each set of new line layout plans, generate the optimal grid reconstruction plan under the corresponding plan; Compare the total cost of automatic distribution network wiring under the number of new lines in each group and the corresponding power supply range division scheme, and select the scheme with the lowest cost of new line planning and existing line transformation.

3. The method for joint optimization of construction and transformation of distribution network in built areas based on mixed integer programming according to claim 1, characterized in that: In step 2, the lower limit of the number of new line exits is as follows: Where W max L is the maximum value of the sum of the time sequence characteristics of all loads within the power supply range of the substation. max is the maximum transmission capacity of the line, cosφ is the power factor, m is the number of new lines required within the power supply range of the substation, I is the number of existing medium-voltage lines within the power supply range of the substation, and [] is the rounding-down symbol.

4. The method for joint optimization of construction and transformation of distribution network in built areas based on mixed integer programming according to claim 1, characterized in that: In step 2, with the constraint that the combined load rate of all medium-voltage lines does not exceed 50%, as many unconnected sources and load points as possible are connected to the grid. Based on the adjusted scale and distribution of unconnected sources and loads, the upper bound of the number of new lines to be built is calculated as shown in the following formula: minQ out f q,j ≤X q,j Where Q out Indicates the number of newly added load points that are not connected to the grid, φ q,j A 0-1 variable used to indicate whether the newly added load point q is incorporated into the power supply range of line j; φ q,j =1 means that the newly added load point q is incorporated into the power supply range of line j; Q is the total number of newly added load points; P j,t P represents the sum of the original load point powers of the line at time t; q,t is the power of the newly added load point q at time t; X q,j Represents the adjacent relationship between the newly added load point q and line j.

5. The method for joint optimization of construction and transformation of distribution network in built areas based on mixed integer programming according to claim 1, characterized in that: Step 3 process is as follows: 3.1) Assign each newly added load point to the power supply range of each existing line with the shortest European distance, calculate the load factor of each line at this time, and evaluate the over-limit situation of each existing line; 3.2) Divide the substation's overall power supply range into U local power supply areas, using two lines that do not cross the limit as boundaries; 3.3) Sequentially locate the construction locations of each new line in the local power supply area with the highest ratio of load characteristic peak to total line capacity, and determine the number of new lines required for each local power supply area; 3.4) Analyze each local power supply area and sequentially calculate the extent to which the construction of new lines within each feeder sub-block combination block within the local power supply area can reduce the load peak of the over-limit lines on both sides. Determine the number of new lines required in each feeder sub-block combination block within each local power supply area; 3.5) Use the centerline method to divide the load range supplied by each new line in each feeder sub-block; 3.6) For the overall power supply range of the substation, combine the new line supply plans obtained in these U local power supply areas to form a plan for all new lines to supply the load; 3.7) After obtaining all feasible new line power supply range plans for a single substation, under the same load rate upper bound, requiring the sum of all radial lines in the area to be an even number and limiting the sum of the total number of lines in the three substations to be an even number, through permutations and combinations, obtain the power supply range plans for new lines for multiple substations.

6. The method for joint optimization of construction and transformation of distribution network in built areas based on mixed integer programming according to claim 1, characterized in that: In step 4, the objective function of the joint optimization model for new line planning and existing line reconstruction is as follows: minZ=Z1+Z2+Z3+Z4 Where: Z is the total cost of line planning; Z1 is the total cost of the trunk line and branch line when planning a new line; γ is the equal annual value coefficient; x he,k Indicates whether a trunk line is built between nodes h and e in the kth feeder sub-block combination block; y he,k Indicates whether a branch line is constructed between nodes h and e in the kth feeder sub-block combination block; r0 represents the discount rate; a is the planned depreciation year; Φ k ,Ω k 、A k are the sets of street nodes, access nodes, and load nodes within the kth feeder sub-block combination block; α and β are the construction costs of the trunk line and branch line per unit length, respectively; l he,k is the line length between nodes h and e in the kth feeder sub-block combination block. Z2 is the total cost of the branch line required to add the new load point to the medium voltage line; Z3 is the total cost of the branch line required to adjust the original load point, and Z4 is the total cost of the tie line transformation; l q,j The length of the branch line required to add the new load q to the medium voltage line j; φ i,j is the decision variable indicating whether the original load i is assigned to the medium voltage line j. i,j =1, otherwise φ i,j =0;l i,j is the length of the branch line required to build when the original load i belongs to the medium voltage line j. It is worth noting that if the load i initially belongs to the line j, then set l i,j = 0, indicating that there is no additional cost after it is attributed to line j; δ m,n Indicates the connection between the terminal nodes of line m and line n, that is, whether the tie line is built, δ m,n =1 indicates the construction of the tie line between line m and line n; l m,n is the minimum distance along the street between the end nodes of route m and route n.

7. The method for joint optimization of construction and transformation of distribution network in built areas based on mixed integer programming according to claim 1, characterized in that: In step 4, the constraints include line radial constraints, connectivity constraints, line capacity constraints, new load point topology constraints, existing load point topology constraints, and tie line topology constraints.

8. An electronic device comprising a processor and a memory, characterized in that: When the program instructions in the memory are read and executed by the processor, the method for joint optimization of construction and transformation of distribution network in a built-up area based on mixed integer programming as described in any one of claims 1 to 7 is executed.

9. A storage medium storing program instructions, characterized in that: When the program instructions in the storage medium are read and executed, the method for joint optimization of construction and transformation of distribution network in a built-up area based on mixed integer programming as described in any one of claims 1 to 7 is executed.

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