Power distribution network grid division method and system considering static and dynamic indexes

Abstract

The invention provides a power distribution network grid division method and system considering static and dynamic indexes, and the method comprises the steps: firstly building a power distribution network grid division model which takes geographic information into consideration and takes the minimum investment and operation cost as a target, then solving the power distribution network grid division model, and obtaining a plurality of preliminary grid division schemes; and finally, based on the comprehensive evaluation indexes considering the static and dynamic indexes, evaluating each preliminary grid division scheme, and taking the preliminary grid division scheme with the maximum comprehensive evaluation index value as a final grid division scheme. The load reliability, interactivity and bearing capacity of the power distribution network can be improved, the equipment utilization rate and economical efficiency are improved, the overall efficiency of the power distribution network is improved to a large extent, and the requirements for randomness and flexibility of a load area of the modern power distribution network are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network, and in particular relates to a distribution network grid division method and system taking static and dynamic indicators into consideration. Background Art

[0002] Over the past few decades, distribution planning has become increasingly important with the increasing integration of distributed energy, electric vehicles, and urbanization. With the rapid development of cities in my country, building and operating distribution networks in new urban areas is a top priority for distribution system operators. The main goal of distribution network planning is to optimize feeder selection using geographic information systems (GIS) to ensure safe operation of the distribution network under various conditions.

[0003] At present, there are many studies on distribution network planning at home and abroad, which can be roughly divided into mathematical optimization methods, heuristic optimization methods and modern intelligent optimization algorithms according to the solution methods. Although the existing mathematical planning methods and intelligent heuristic methods are relatively systematic, the optimization schemes are difficult to implement due to the complexity of modeling, immature algorithms and difficulty in manual intervention, and there are few practical applications. In order to solve the above problems, the gridding idea is introduced in the distribution network planning, and the large-scale distribution network is divided into multiple power supply areas that are relatively independent geographically and electrically (there is only electrical connection in the power supply substation), and then the distribution network planning is carried out for each small-scale power supply area, so as to alleviate the contradiction between the large scale of the distribution network and the refined planning, and reduce the complexity of large-scale distribution network planning. However, the traditional grid division method cannot meet the requirements of randomness and flexibility of the load area of ​​the modern distribution network. Summary of the invention

[0004] The purpose of the present invention is to provide a distribution network grid division method and system taking static and dynamic indicators into consideration in view of the above-mentioned problems existing in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention proposes a distribution network grid division method considering static and dynamic indicators, comprising:

[0007] S1. Establish a distribution network grid division model that takes geographic information into consideration and aims to minimize investment and operating costs;

[0008] S2, solving the distribution network grid division model and obtaining multiple preliminary grid division schemes;

[0009] S3. Evaluate each preliminary grid division scheme based on the comprehensive evaluation index considering static and dynamic indicators, and take the preliminary grid division scheme with the largest comprehensive evaluation index value as the final grid division scheme, where:

[0010] The comprehensive evaluation index f is calculated according to the following formula:

[0011] f=β∑F l,i(k),j +η∑F g,i(k),j -ε∑F c

[0012] In the above formula, F l,i(k),j 、F g,i(k),j are the line cost reduction and annual revenue increase caused by adjusting the corresponding area of ​​load k in unit grid i to unit grid j, respectively. c To consider the dynamic index of load peak-valley coupling characteristics, β, η, and ε are F l,i(k),j 、F g,i(k),j 、F c The corresponding weight.

[0013] The F l,i(k),j Calculated according to the following formula:

[0014]

[0015] ΔF l,(i(k),j) =ε′d l (ΔD i(k) -ΔD i(k),j )

[0016]

[0017] ε′=k z +k y +k h

[0018] In the above formula, ε′ is the intermediate coefficient, d l is the investment cost per unit length of line, D i(k) is the load k in unit grid i and the grid area i w The distance between virtual trunk lines, i w is the grid area in unit grid i excluding the area corresponding to load k, is the distance between load k in unit grid i and the virtual trunk line of unit grid j, ΔF l,i(k),j When the area corresponding to load k in unit grid i is adjusted to grid j, the change in the benefit of occupying the equivalent line in the corresponding grid area, ΔD i(k) is the increase in the line length of the feeder capacity equivalent to the corresponding grid area occupied by the load area k in the unit grid i, ΔD i(k),j is the increase in the length of the feeder capacity equivalent line occupied in the corresponding grid area when the load k in the unit grid i is adjusted to the unit grid j, P i , P j are the maximum loads of the load curves of unit grids i and j, is the grid area i w Maximum load of the load curve, P l is the maximum load allowed for a single line, L X,i , L X,j are the average lengths of a single line in the main power substation of grid i and grid j, respectively, and k z , k y , k h They are depreciation factor, operation and maintenance cost factor and investment recovery factor respectively;

[0019] The F g,i(k),j Calculated according to the following formula:

[0020]

[0021] ΔF g,i(k),j =ΔF g,i(k) -ΔF g,j,k

[0022] In the above formula, ΔF g,i(k),j is the annual revenue change value of the distributed generation due to the over-limit of distributed generation penetration when the corresponding area of ​​load k in unit grid i is adjusted to unit grid j, ΔF g,i(k) When the area corresponding to load k is in unit grid i, the annual revenue reduction value of unit grid i caused by less generation of distributed generation due to the over-limit of distributed generation penetration rate, ΔF g,j,k It is the annual revenue reduction value of unit grid j due to the less power generation of distributed generation caused by the distributed generation penetration rate exceeding the limit when the corresponding area of ​​load k in unit grid i is adjusted to grid j.

[0023] The F c Calculated according to the following formula:

[0024] F c = x l +χ2+χ3

[0025]

[0026] In the above formula, χ l , χ2, χ3 are the average load difference, the load rate structure of each block, and the average peak-to-valley difference rate, respectively. N is the number of unit grids, P max is the value of the maximum load in the unit grid, P imax is the maximum load of unit grid i, f i is the load rate of unit grid i, f av is the average load rate of all unit grids, f ip is the peak-to-valley difference rate of unit grid i.

[0027] In S1, the objective function of the distribution network grid partitioning model includes:

[0028] min(F1+F2+F3)

[0029]

[0030] In the above formula, F1 is the substation cost, F2 is the feeder cost, F3 is the additional wiring cost when laying the line, and d f is the fixed investment cost of the substation, d v is the investment cost per unit capacity of the substation, S m is the capacity of substation m, r0 is the annual interest rate, p and q are the depreciation periods of the substation and the line respectively, d o is the unit capacity operation cost of the substation, K is the total number of substations, J m is the set of loads supplied by substation m, d l is the investment cost per unit length of line, α is the line network loss conversion coefficient, P n is the active load of load n, l mn is the length of the line between substation m and load n, c mn The additional wiring cost required to lay the line between substation m and load n;

[0031] The S2 includes:

[0032] S21. Determine the appropriate number of substations K based on the number, capacity and location of loads in the planning area:

[0033]

[0034] In the above formula, N' is the total number of loads, R min , R max They are the minimum and maximum load ratios allowed by the current voltage level;

[0035] S22. The improved K-Means algorithm is used to solve the distribution network grid partitioning model, wherein the distance, evaluation function and cluster center in the improved K-Means algorithm are as follows:

[0036]

[0037] B=r0(1+r0) q / [(1+r0) q -1]

[0038]

[0039] In the above formula, A n , B is the intermediate variable, e(S m ) is the load rate of substation m, is the load simultaneity rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the load active power of the substation, is the set of loads supplied by substation m at the cth iteration, f c is the evaluation function, F4 is the known value of the substation cost, k mn is the penalty coefficient for important areas. If load n and substation m are in different administrative areas, k mn >1, otherwise k mn =1.

[0040] The constraints of the distribution network grid partitioning model include:

[0041]

[0042] l mn ≤L m=1,2,...,K;n∈J m

[0043] In the above formula, L is the maximum power supply capacity radius of the substation.

[0044] In a second aspect, the present invention proposes a distribution network grid partitioning system that considers static and dynamic indicators, including a grid partitioning model construction module, a grid partitioning model solving module, and a scheme optimization module;

[0045] The grid division model building module is used to establish a distribution network grid division model that takes geographic information into consideration and aims to minimize investment and operating costs;

[0046] The grid division model solving module is used to solve the distribution network grid division model to obtain multiple preliminary grid division schemes;

[0047] The scheme optimization module is used to evaluate each preliminary grid division scheme based on the comprehensive evaluation index considering static and dynamic indicators, and take the preliminary grid division scheme with the largest comprehensive evaluation index value as the final grid division scheme, wherein:

[0048] The comprehensive evaluation index f is calculated according to the following formula:

[0049] f=β∑F l,i(k),j +η∑F g,i(k),j -ε∑F c

[0050] In the above formula, F l,i(k),j 、F g,i(k),j are the line cost reduction and annual revenue increase caused by adjusting the corresponding area of ​​load k in unit grid i to unit grid j, respectively. cTo consider the dynamic index of load peak-valley coupling characteristics, β, η, and ε are F l,i(k),j 、F g,i(k),j 、F c The corresponding weight.

[0051] The F l,i(k),j Calculated according to the following formula:

[0052]

[0053] ΔF l,(i(k),j) =ε′d l (ΔD i(k) -ΔD i(k),j )

[0054]

[0055] ε′=k z +k y +k h

[0056] In the above formula, ε′ is the intermediate coefficient, d l is the investment cost per unit length of line, D i(k) is the load k in unit grid i and the grid area i w The distance between virtual trunk lines, i w is the grid area in unit grid i excluding the area corresponding to load k, is the distance between load k in unit grid i and the virtual trunk line of unit grid j, ΔF l,i(k),j When the area corresponding to load k in unit grid i is adjusted to grid j, the change in the benefit of occupying the equivalent line in the corresponding grid area, ΔD i(k) is the increase in the line length of the feeder capacity equivalent to the corresponding grid area occupied by the load area k in the unit grid i, ΔD i(k),j is the increase in the length of the feeder capacity equivalent line occupied in the corresponding grid area when the load k in the unit grid i is adjusted to the unit grid j, P i , P j are the maximum loads of the load curves of unit grids i and j, is the grid area i w Maximum load of the load curve, P l is the maximum load allowed for a single line, L X,i , L X,j are the average lengths of a single line in the main power substation of grid i and grid j, respectively, and k z , k y , k h They are depreciation factor, operation and maintenance cost factor and investment recovery factor respectively;

[0057] The Fg,i(k),j Calculated according to the following formula:

[0058]

[0059] ΔF g,i(k),j =ΔF g,i(k) -ΔF g,j,k

[0060] In the above formula, ΔF g,i(k),j is the annual revenue change value of the distributed generation due to the over-limit of distributed generation penetration when the corresponding area of ​​load k in unit grid i is adjusted to unit grid j, ΔF g,i(k) When the area corresponding to load k is in unit grid i, the annual revenue reduction value of unit grid i caused by less generation of distributed generation due to the over-limit of distributed generation penetration rate, ΔF g,j,k It is the annual revenue reduction value of unit grid j due to the less power generation of distributed generation caused by the distributed generation penetration rate exceeding the limit when the corresponding area of ​​load k in unit grid i is adjusted to grid j.

[0061] The F c Calculated according to the following formula:

[0062] F c = x l +χ2+χ3

[0063]

[0064] In the above formula, χ l , χ2, χ3 are the average load difference, the load rate structure of each block, and the average peak-to-valley difference rate, respectively. N is the number of unit grids, P max is the value of the maximum load in the unit grid, P imax is the maximum load of unit grid i, f i is the load rate of unit grid i, f av is the average load rate of all unit grids, f ip is the peak-to-valley difference rate of unit grid i.

[0065] The objective function of the distribution network grid partitioning model includes:

[0066] min(F1+F2+F3)

[0067]

[0068] In the above formula, F1 is the substation cost, F2 is the feeder cost, F3 is the additional wiring cost when laying the line, and d f is the fixed investment cost of the substation, d v is the investment cost per unit capacity of the substation, S mis the capacity of substation m, r0 is the annual interest rate, p and q are the depreciation periods of the substation and the line respectively, d o is the unit capacity operation cost of the substation, K is the total number of substations, J m is the set of loads supplied by substation m, d l is the investment cost per unit length of line, α is the line network loss conversion coefficient, P n is the active load of load n, l mn is the length of the line between substation m and load n, c mn The additional wiring cost required to lay the line between substation m and load n;

[0069] The grid division model solving module includes a substation quantity determination unit and a model solving unit;

[0070] The substation quantity determination unit is used to determine the appropriate number of substations K according to the number, capacity and location of loads in the planning area:

[0071]

[0072] In the above formula, N' is the total number of loads, R min , R max They are the minimum and maximum load ratios allowed by the current voltage level;

[0073] The model solving unit is used to solve the distribution network grid partitioning model using the improved K-Means algorithm, wherein the distance, evaluation function and cluster center in the improved K-Means algorithm are as follows:

[0074]

[0075] B=r0(1+r0) q / [(1+r0) q -1]

[0076]

[0077] In the above formula, A n , B is the intermediate variable, e(S m ) is the load rate of substation m, is the load simultaneity rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the load active power of the substation, is the set of loads supplied by substation m at the cth iteration, f c is the evaluation function, F4 is the known value of the substation cost, k mnis the penalty coefficient for important areas. If load n and substation m are in different administrative areas, k mn >1, otherwise k mn =1.

[0078] The constraints of the distribution network grid partitioning model include:

[0079]

[0080] l mn ≤L m=1,2,...,K;n∈J m

[0081] In the above formula, L is the maximum power supply capacity radius of the substation.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] 1. A distribution network grid division method considering static and dynamic indicators of the present invention first establishes a distribution network grid division model that considers geographic information and aims at minimizing investment and operating costs, then solves the distribution network grid division model, obtains multiple preliminary grid division schemes, and finally evaluates each preliminary grid division scheme based on the comprehensive evaluation index considering static and dynamic indicators, and takes the preliminary grid division scheme with the largest comprehensive evaluation index value as the final grid division scheme. The method proposes to optimize the grid division scheme by considering the comprehensive evaluation index of static and dynamic indicators, so that the final grid division scheme can improve the load reliability, interactivity, and carrying capacity of the distribution network, improve the equipment utilization and economy, and greatly improve the overall efficiency of the distribution network, meeting the randomness and flexibility requirements of the load area of ​​the modern distribution network.

[0084] 2. The invention proposes a distribution network grid division method considering static and dynamic indicators, and proposes an improved K-Means algorithm, which takes into account the weight of load nodes, the influence of adverse terrain and capacity limitations, and improves the definition of the distance, evaluation function and cluster center of the K-Means algorithm, so that the solution results are more in line with actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 This is a flowchart of the method described in Example 1.

[0086] Figure 2 The structure diagram of the system of the present invention is shown in FIG. DETAILED DESCRIPTION

[0087] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0088] Embodiment 1:

[0089] This embodiment takes the 110kV substation power supply area in a certain planning area (all 10kV trunk lines in the area are LGJ-240, the maximum transmission capacity of a single circuit line is 7MW, the power factor is 0.9, and the load simultaneous rate is 0.85) as the research object, and implements a distribution network grid division method considering static and dynamic indicators described in the present invention, such as Figure 1 As shown, the specific steps are as follows:

[0090] 1. Initialization: input the operation data, load information, and geographic information of the distribution network planning area.

[0091] 2. Establish a distribution network grid division model that takes geographic information into account and aims to minimize investment and operating costs.

[0092] The objective function of the distribution network grid partitioning model is:

[0093] min(F1+F2+F3)

[0094]

[0095] In the above formula, F1 is the substation cost, F2 is the feeder cost, F3 is the additional wiring cost when laying the line, and d f is the fixed investment cost of the substation, d v is the investment cost per unit capacity of the substation, S m is the capacity of substation m, r0 is the annual interest rate, p and q are the depreciation periods of the substation and the line respectively, d o is the unit capacity operation cost of the substation, K is the total number of substations, J m is the set of loads supplied by substation m, d l is the investment cost per unit length of line, α is the line network loss conversion coefficient, P n is the active load of load n, l mn is the length of the line between substation m and load n, c mn The additional wiring cost required to lay a line between substation m and load n. The more obstacles there are, the greater the value.

[0096] The constraints are based on the substation, considering the substation power supply capacity and power supply radius, including:

[0097]

[0098] l mn ≤L m=1,2,...,K;n∈J m

[0099] In the above formula, L is the maximum power supply capacity radius of the substation.

[0100] 3. Determine the appropriate number of substations K based on the number, capacity and location of loads in the planning area:

[0101]

[0102] In the above formula, N' is the total number of loads, R min , R max are the minimum and maximum load ratios allowed by the current voltage level. At this point, F1 in the objective function becomes a known value, and the objective function can be converted to:

[0103]

[0104] In the above formula, F4 is the known value of the substation cost, and the distribution network grid division problem is transformed into a problem that only depends on the line length l mn and additional wiring costs c mn Constraint programming problems.

[0105] 4. In view of the above constrained programming problem, the improved K-Means algorithm is used to solve the distribution network grid partition model, and multiple preliminary grid partition schemes are obtained. Among them, the distance, evaluation function and cluster center in the improved K-Means algorithm are as follows:

[0106]

[0107] B=r0(1+r0) q / [(1+r0) q -1]

[0108]

[0109] In the above formula, A n , B is the intermediate variable, e(S m ) is the load rate of substation m, is the load simultaneity rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the load active power of the substation, is the set of loads supplied by substation m at the cth iteration, f c is the evaluation function, k mn is the penalty coefficient for important areas. This parameter ensures that the loads in important areas are supplied by the substations in the area. If the load n and the substation m are in different administrative areas, k mn >1, otherwise k mn =1.

[0110] 5. Introduce static indicators of land use properties and dynamic indicators of load peak-valley coupling capacity, and establish mathematical models of static and dynamic indicators respectively.

[0111] (1) Static indicator mathematical model

[0112] Considering the impact of load characteristics of different land uses on the feeder power supply capacity, it is reflected by the equivalent line investment or length (when the unit length investment is the same) of the load occupying the feeder capacity.

[0113] If the area corresponding to load k in unit grid i is adjusted to unit grid j, the reduction in line cost caused by this can be expressed as:

[0114]

[0115] ΔF l,(i(k),j) =ε′d l (ΔD i(k) -ΔD i(k),j )

[0116]

[0117] ε′=k z +k y +k h

[0118]

[0119] In the above formula, F l,i(k),j is the line cost reduction caused by adjusting the corresponding area of ​​load k in unit grid i to unit grid j, ε′ is the intermediate coefficient, d l is the investment cost per unit length of line, D i(k) is the load k in unit grid i and the grid area i w The distance between virtual trunk lines, i w is the grid area in unit grid i excluding the area corresponding to load k, is the distance between load k in unit grid i and the virtual trunk line of unit grid j, ΔF l,i(k),j When the area corresponding to load k in unit grid i is adjusted to grid j, the change in the benefit of occupying the equivalent line in the corresponding grid area, ΔD i(k) is the increase in the line length of the feeder capacity equivalent to the corresponding grid area occupied by the load area k in the unit grid i, ΔD i(k),j is the increase in the length of the feeder capacity equivalent line occupied in the corresponding grid area when the load k in the unit grid i is adjusted to the unit grid j, P i , P j are the maximum loads of the load curves of unit grids i and j, is the grid area i w Maximum load of the load curve, P l is the maximum load allowed for a single line, L X,i , LX,j are the average lengths of a single line in the main power substation of grid i and grid j, respectively, and k z , k y , k h are depreciation coefficient, operation and maintenance cost coefficient and investment recovery coefficient respectively, i , H j are the power supply areas of the main power substations of unit grids i and j respectively, and K′ Z is the correction coefficient of the feeder length. In this embodiment, the correction coefficient of the feeder length is 2.0.

[0120] Considering the limitation of the maximum distributed generation penetration rate in the power supply partition, if the area corresponding to load k in unit grid i is adjusted to unit grid j, the annual revenue increase caused by this can be expressed as:

[0121]

[0122] ΔF g,i(k),j =ΔF g,i(k) -ΔF g,j,k

[0123] In the above formula, F g,i(k),j is the annual revenue increase caused by adjusting the area corresponding to load k in unit grid i to unit grid j, ΔF g,i(k),j is the annual revenue change value of the distributed generation due to the over-limit of distributed generation penetration when the corresponding area of ​​load k in unit grid i is adjusted to unit grid j, ΔF g,i(k) When the area corresponding to load k is in unit grid i, the annual revenue reduction value of unit grid i caused by less generation of distributed generation due to the over-limit of distributed generation penetration rate, ΔF g,j,k It is the annual revenue reduction value of unit grid j due to the less power generation of distributed generation caused by the distributed generation penetration rate exceeding the limit when the corresponding area of ​​load k in unit grid i is adjusted to grid j.

[0124] (2) Dynamic indicator mathematical model

[0125] In order to achieve the best effect of distribution network grid division and improve the power supply capacity within each grid division of the distribution network, it is necessary to optimize the overall load characteristics of each block as much as possible. With this goal in mind, the peak-valley coupling capacity between loads is maximized to adjust the overall load characteristics of the grid, and the following dynamic indicators of load peak-valley coupling capacity are proposed:

[0126] F c = x l +χ2+χ3

[0127]

[0128]

[0129] In the above formula, F c is a dynamic index that takes into account the peak-valley coupling characteristics of the load. l , χ2, χ3 are the average load difference, the load rate structure of each block, and the average peak-to-valley difference rate, respectively. l The smaller the value, the more uniform the load distribution of each unit grid. The smaller χ2 is, the greater the load rate of each unit grid and the more concentrated the distribution value interval is, the higher the equipment utilization rate is. The smaller χ3 is, the smaller the peak-to-valley difference rate of the divided area is, and the better the ability to alleviate peak load is. N is the number of unit grids, P is max is the value of the maximum load in the unit grid, P imax is the maximum load of unit grid i, f i is the load rate of unit grid i, f av is the average load rate of all unit grids, f ip is the peak-to-valley difference rate of unit grid i.

[0130] 6. Determine the dynamic index mathematical model based on the static and dynamic index mathematical models, and use the comprehensive evaluation index to evaluate each preliminary grid division scheme, and take the preliminary grid division scheme with the largest comprehensive evaluation index value as the final grid division scheme, where:

[0131] The comprehensive evaluation index is calculated according to the following formula:

[0132] f=β∑F l,i(k),j +η∑F g,i(k),j -ε∑F c

[0133] In the above formula, f is a comprehensive evaluation index. The larger the f is, the more reasonable the grid division is, and the better the effect of distribution network planning is. β, η, and ε are F l,i(k),j 、F g,i(k),j 、F c The corresponding weight.

[0134] The final grid division scheme (after optimization) obtained in this embodiment and the performance evaluation indicators before the implementation of this embodiment (before optimization) are shown in Table 1:

[0135] Table 1 Values ​​of performance evaluation indicators before and after optimization

[0136] Performance Indicators Before optimization After optimization Average load difference 0.47 0.31 Average load factor 0.58 0.49 Average peak-to-valley rate 0.42 0.34

[0137] It can be seen from Table 1 that the various performance indicators after optimization are improved compared with those before optimization. It can be seen that the grid division method proposed in the present invention improves the load reliability, interactivity and carrying capacity of the distribution network to varying degrees, reduces the redundancy of the distribution network, improves the equipment utilization rate and economy, and greatly improves the overall efficiency of the distribution network.

[0138] Embodiment 2:

[0139] A distribution network grid division system considering static and dynamic indicators, such as Figure 2 As shown, it includes a grid partition model construction module, a grid partition model solution module, and a solution optimization module.

[0140] The grid partitioning model building module is used to establish a distribution network grid partitioning model that takes geographic information into consideration and aims to minimize investment and operating costs. The objective function of the model is:

[0141] min(F1+F2+F3)

[0142]

[0143] In the above formula, F1 is the substation cost, F2 is the feeder cost, F3 is the additional wiring cost when laying the line, and d f is the fixed investment cost of the substation, d v is the investment cost per unit capacity of the substation, S m is the capacity of substation m, r0 is the annual interest rate, p and q are the depreciation periods of the substation and the line respectively, d o is the unit capacity operation cost of the substation, K is the total number of substations, J m is the set of loads supplied by substation m, d l is the investment cost per unit length of line, α is the line network loss conversion coefficient, P n is the active load of load n, l mn is the length of the line between substation m and load n, c mn The additional wiring cost required to lay the line between substation m and load n;

[0144] The constraints include:

[0145]

[0146] l mn ≤L m=1,2,...,K;n∈J m

[0147] In the above formula, L is the maximum power supply capacity radius of the substation.

[0148] The grid division model solving module is used to solve the distribution network grid division model to obtain multiple preliminary grid division schemes, including a substation quantity determination unit and a model solving unit;

[0149] The substation quantity determination unit is used to determine the appropriate number of substations K according to the number, capacity and location of loads in the planning area:

[0150]

[0151] In the above formula, N' is the total number of loads, R min , R max They are the minimum and maximum load ratios allowed by the current voltage level;

[0152] The model solving unit is used to solve the distribution network grid partitioning model using the improved K-Means algorithm, wherein the distance, evaluation function and cluster center in the improved K-Means algorithm are as follows:

[0153]

[0154] B=r0(1+r0) q / [(1+r0) q -1]

[0155]

[0156] In the above formula, A n , B is the intermediate variable, e(S m ) is the load rate of substation m, is the load simultaneity rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the load active power of the substation, is the set of loads supplied by substation m at the cth iteration, f c is the evaluation function, F4 is the known value of the substation cost, k mn is the penalty coefficient for important areas. If load n and substation m are in different administrative areas, k mn >1, otherwise k mn =1.

[0157] The scheme optimization module is used to evaluate each preliminary grid division scheme based on the comprehensive evaluation index considering static and dynamic indicators, and take the preliminary grid division scheme with the largest comprehensive evaluation index value as the final grid division scheme, wherein:

[0158] The comprehensive evaluation index f is calculated according to the following formula:

[0159] f=β∑F l,i(k),j +η∑F g,i(k),j -ε∑F c

[0160]

[0161] ΔF l,(i(k),j) =ε′d l (ΔD i(k) -ΔDi(k),j )

[0162]

[0163]

[0164] ε′=k z +k y +k h

[0165]

[0166] ΔF g,i(k),j =ΔF g,i(k) -ΔF g,j,k

[0167] F c = x l +χ2+χ3

[0168]

[0169] In the above formula, F l,i(k),j 、F g,i(k),j are the line cost reduction and annual revenue increase caused by adjusting the corresponding area of ​​load k in unit grid i to unit grid j, respectively. c To consider the dynamic index of load peak-valley coupling characteristics, β, η, and ε are F l,i(k),j 、F g,i(k),j 、F c The corresponding weight, ε′ is the intermediate coefficient, d l is the investment cost per unit length of line, D i(k) is the load k in unit grid i and the grid area i w The distance between virtual trunk lines, i w is the grid area in unit grid i excluding the area corresponding to load k, is the distance between load k in unit grid i and the virtual trunk line of unit grid j, ΔF l,i(k),j When the area corresponding to load k in unit grid i is adjusted to grid j, the change in the benefit of occupying the equivalent line in the corresponding grid area, ΔD i(k) is the increase in the line length of the feeder capacity equivalent to the corresponding grid area occupied by the load area k in the unit grid i, ΔD i(k),j is the increase in the length of the feeder capacity equivalent line occupied in the corresponding grid area when the load k in the unit grid i is adjusted to the unit grid j, P i , P j are the maximum loads of the load curves of unit grids i and j, respectively, P iw is the grid area i w Maximum load of the load curve, Pl is the maximum load allowed for a single line, L X,i , L X,j are the average lengths of a single line in the main power substation of grid i and grid j, respectively, and k z , k y , k h are depreciation coefficient, operation and maintenance cost coefficient and investment recovery coefficient respectively, i , H j are the power supply areas of the main power substations of unit grids i and j respectively, and K′ Z is the correction factor of the feeder length. In this embodiment, the correction factor of the feeder length is ΔF g,i(k),j is the annual revenue change value of the distributed generation due to the over-limit of distributed generation penetration when the corresponding area of ​​load k in unit grid i is adjusted to unit grid j, ΔF g,i(k) When the area corresponding to load k is in unit grid i, the annual revenue reduction value of unit grid i caused by less generation of distributed generation due to the over-limit of distributed generation penetration rate, ΔF g,j,k is the annual revenue reduction value of distributed generation in unit grid j due to the over-limit of distributed generation penetration rate when the corresponding area of ​​load k in unit grid i is adjusted to grid j, l , χ2, χ3 are the average load difference, the load rate structure of each block, and the average peak-to-valley difference rate, respectively. N is the number of unit grids, P max is the value of the maximum load in the unit grid, P imax is the maximum load of unit grid i, f i is the load rate of unit grid i, f av is the average load rate of all unit grids, f ip is the peak-to-valley difference rate of unit grid i.

Claims

1. A distribution network grid division method considering static and dynamic indicators, characterized in that: The method comprises: S1. Establish a distribution network grid division model that takes geographic information into consideration and aims to minimize investment and operating costs; S2, solving the distribution network grid division model and obtaining multiple preliminary grid division schemes; S3. Evaluate each preliminary grid division scheme based on the comprehensive evaluation index considering static and dynamic indicators, and take the preliminary grid division scheme with the largest comprehensive evaluation index value as the final grid division scheme, where: The comprehensive evaluation index f is calculated according to the following formula: f=β∑F l,i(k),j +η∑F g,i(k),j -ε∑F c In the above formula, F l,i(k),j 、F g,i(k),j are the line cost reduction and annual revenue increase caused by adjusting the corresponding area of ​​load k in unit grid i to unit grid j, respectively. c To consider the dynamic index of load peak-valley coupling characteristics, β, η, and ε are F l,i(k),j 、F g,i(k),j 、F c The corresponding weight.

2. A distribution network grid division method considering static and dynamic indicators according to claim 1, characterized in that: The F l,i(k),j Calculated according to the following formula: ΔF l,(i(k),j) =ε′d l (ΔD i(k) -ΔD i(k),j ) e′=k z +k y +k h In the above formula, ε′ is the intermediate coefficient, d l is the investment cost per unit length of line, D i(k) is the load k in unit grid i and the grid area i w The distance between virtual trunk lines, i w is the grid area in unit grid i excluding the area corresponding to load k, is the distance between load k in unit grid i and the virtual trunk line of unit grid j, ΔF l,i(k),j When the area corresponding to load k in unit grid i is adjusted to grid j, the change in the benefit of occupying the equivalent line in the corresponding grid area, ΔD i(k) is the increase in the line length of the feeder capacity equivalent to the corresponding grid area occupied by the load area k in the unit grid i, ΔD i(k),j is the increase in the length of the feeder capacity equivalent line occupied in the corresponding grid area when the load k in the unit grid i is adjusted to the unit grid j, P i , P j are the maximum loads of the load curves of unit grids i and j, is the grid area i w Maximum load of the load curve, P l is the maximum load allowed for a single line, L X,i , L X,j are the average lengths of a single line in the main power substation of grid i and grid j, respectively, and k z , k y , k h They are depreciation factor, operation and maintenance cost factor and investment recovery factor respectively; The F g,i(k),j Calculated according to the following formula: ΔF g,i(k),j =ΔF g,i(k) -ΔF g,j,k In the above formula, ΔF g,i(k),j is the annual revenue change value of the distributed generation due to the over-limit of distributed generation penetration when the corresponding area of ​​load k in unit grid i is adjusted to unit grid j, ΔF g,i(k) When the area corresponding to load k is in unit grid i, the annual revenue reduction value of unit grid i caused by less generation of distributed generation due to the over-limit of distributed generation penetration rate, ΔF g,j,k It is the annual revenue reduction value of unit grid j due to the less power generation of distributed generation caused by the distributed generation penetration rate exceeding the limit when the corresponding area of ​​load k in unit grid i is adjusted to grid j.

3. A distribution network grid division method considering static and dynamic indicators according to claim 1 or 2, characterized in that: The F c Calculated according to the following formula: F c =χ1+χ2+χ3 In the above formula, χ l , χ2, χ3 are the average load difference, the load rate structure of each block, and the average peak-to-valley difference rate, respectively. N is the number of unit grids, P max is the value of the maximum load in the unit grid, P imax is the maximum load of unit grid i, f i is the load rate of unit grid i, f av is the average load rate of all unit grids, f ip is the peak-to-valley difference rate of unit grid i.

4. A distribution network grid division method considering static and dynamic indicators according to claim 1 or 2, characterized in that: In S1, the objective function of the distribution network grid partitioning model includes: min(F1+F2+F3) In the above formula, F1 is the substation cost, F2 is the feeder cost, F3 is the additional wiring cost when laying the line, and d f is the fixed investment cost of the substation, d v is the investment cost per unit capacity of the substation, S m is the capacity of substation m, r0 is the annual interest rate, p and q are the depreciation periods of the substation and the line respectively, d o is the unit capacity operation cost of the substation, K is the total number of substations, J m is the set of loads supplied by substation m, d l is the investment cost per unit length of line, α is the line network loss conversion coefficient, P n is the active load of load n, l mn is the length of the line between substation m and load n, c mn The additional wiring cost required to lay the line between substation m and load n; The S2 includes: S21. Determine the appropriate number of substations K based on the number, capacity and location of loads in the planning area: In the above formula, N' is the total number of loads, R min , R max They are the minimum and maximum load ratios allowed by the current voltage level; S22. The improved K-Means algorithm is used to solve the distribution network grid partitioning model, wherein the distance, evaluation function and cluster center in the improved K-Means algorithm are as follows: B＝r0(1+r0) q / [(1+r0) q -1] In the above formula, A n , B is the intermediate variable, e(S m ) is the load rate of substation m, is the load simultaneity rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the load active power of the substation, is the set of loads supplied by substation m at the cth iteration, f c is the evaluation function, F4 is the known value of the substation cost, k mn is the penalty coefficient for important areas. If load n and substation m are in different administrative areas, k mn >1, otherwise k mn =1.

5. A distribution network grid division method considering static and dynamic indicators according to claim 1 or 2, characterized in that: The constraints of the distribution network grid partitioning model include: l mn ≤L m=1,2,…,K;n∈J m In the above formula, L is the maximum power supply capacity radius of the substation.

6. A distribution network grid division system considering static and dynamic indicators, characterized in that: The system includes a grid partition model construction module, a grid partition model solution module, and a scheme optimization module; The grid division model building module is used to establish a distribution network grid division model that takes geographic information into consideration and aims to minimize investment and operating costs; The grid division model solving module is used to solve the distribution network grid division model to obtain multiple preliminary grid division schemes; The scheme optimization module is used to evaluate each preliminary grid division scheme based on the comprehensive evaluation index considering static and dynamic indicators, and take the preliminary grid division scheme with the largest comprehensive evaluation index value as the final grid division scheme, wherein: The comprehensive evaluation index f is calculated according to the following formula: f=β∑F l,i(k),j +η∑F g,i(k),j -ε∑F c In the above formula, F l,i(k),j 、F g,i(k),j are the line cost reduction and annual revenue increase caused by adjusting the corresponding area of ​​load k in unit grid i to unit grid j, respectively. c To consider the dynamic index of load peak-valley coupling characteristics, β, η, and ε are F l,i(k),j 、F g,i(k),j 、F c The corresponding weight.

7. A distribution network grid division system considering static and dynamic indicators according to claim 6, characterized in that: The F l,i(k),j Calculated according to the following formula: ΔF l,(i(k),j) =ε′d l (ΔD i(k) -ΔD i(k),j ) e′=k z +k y +k h In the above formula, ε′ is the intermediate coefficient, d l is the investment cost per unit length of line, D i(k) is the load k in unit grid i and the grid area i w The distance between virtual trunk lines, i w is the grid area in unit grid i excluding the area corresponding to load k, is the distance between load k in unit grid i and the virtual trunk line of unit grid j, ΔF l,i(k),j When the area corresponding to load k in unit grid i is adjusted to grid j, the change in the benefit of occupying the equivalent line in the corresponding grid area, ΔD i(k) is the increase in the line length of the feeder capacity equivalent to the corresponding grid area occupied by the load area k in the unit grid i, ΔD i(k),j is the increase in the length of the feeder capacity equivalent line occupied in the corresponding grid area when the load k in the unit grid i is adjusted to the unit grid j, P i , P j are the maximum loads of the load curves of unit grids i and j, is the grid area i w Maximum load of the load curve, P l is the maximum load allowed for a single line, L X,i , L X,j are the average lengths of a single line in the main power substation of grid i and grid j, respectively, and k z , k y , k h They are depreciation factor, operation and maintenance cost factor and investment recovery factor respectively; The F g,i(k),j Calculated according to the following formula: ΔF g,i(k),j =ΔF g,i(k) -ΔF g,j,k In the above formula, ΔF g,i(k),j is the annual revenue change value of the distributed generation due to the over-limit of distributed generation penetration when the corresponding area of ​​load k in unit grid i is adjusted to unit grid j, ΔF g,i(k) When the area corresponding to load k is in unit grid i, the annual revenue reduction value of unit grid i caused by less generation of distributed generation due to the over-limit of distributed generation penetration rate, ΔF g,j,k It is the annual revenue reduction value of unit grid j due to the less power generation of distributed generation caused by the distributed generation penetration rate exceeding the limit when the corresponding area of ​​load k in unit grid i is adjusted to grid j.

8. A distribution network grid division system considering static and dynamic indicators according to claim 6, characterized in that: The F c Calculated according to the following formula: F c =x l +x2+x3 In the above formula, χ l , χ2, χ3 are the average load difference, the load rate structure of each block, and the average peak-to-valley difference rate, respectively. N is the number of unit grids, P max is the value of the maximum load in the unit grid, P imax is the maximum load of unit grid i, f i is the load rate of unit grid i, f av is the average load rate of all unit grids, f ip is the peak-to-valley difference rate of unit grid i.

9. A distribution network grid division system considering static and dynamic indicators according to claim 6 or 7, characterized in that: The objective function of the distribution network grid partitioning model includes: min(F1+F2+F3) In the above formula, F1 is the substation cost, F2 is the feeder cost, F3 is the additional wiring cost when laying the line, and d f is the fixed investment cost of the substation, d v is the investment cost per unit capacity of the substation, S m is the capacity of substation m, r0 is the annual interest rate, p and q are the depreciation periods of the substation and the line respectively, d o is the unit capacity operation cost of the substation, K is the total number of substations, J m is the set of loads supplied by substation m, d l is the investment cost per unit length of line, α is the line network loss conversion coefficient, P n is the active load of load n, l mn is the length of the line between substation m and load n, c mn The additional wiring cost required to lay the line between substation m and load n; The grid division model solving module includes a substation quantity determination unit and a model solving unit; The substation quantity determination unit is used to determine the appropriate number of substations K according to the number, capacity and location of loads in the planning area: In the above formula, N' is the total number of loads, R min , R max They are the minimum and maximum load ratios allowed by the current voltage level; The model solving unit is used to solve the distribution network grid partitioning model using the improved K-Means algorithm, wherein the distance, evaluation function and cluster center in the improved K-Means algorithm are as follows: B＝r0(1+r0) q / [(1+r0) q -1] In the above formula, A n , B is the intermediate variable, e(S m ) is the load rate of substation m, is the load simultaneity rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the load active power of the substation, is the set of loads supplied by substation m at the cth iteration, f c is the evaluation function, F4 is the known value of the substation cost, k mn is the penalty coefficient for important areas. If load n and substation m are in different administrative areas, k mn >1, otherwise k mn =1.

10. A distribution network grid division system considering static and dynamic indicators according to claim 6 or 7, characterized in that: The constraints of the distribution network grid partitioning model include: l mn ≤L m=1,2,…,K;n∈J m In the above formula, L is the maximum power supply capacity radius of the substation.

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