A power distribution network grid division method and system considering static and dynamic indexes

Abstract

The application provides a power distribution network grid division method and system considering static and dynamic indexes, which comprises the following steps: firstly, a power distribution network grid division model considering geographic information and aiming at minimizing investment and operation cost is established; then, the power distribution network grid division model is solved to obtain multiple preliminary grid division schemes; finally, each preliminary grid division scheme is evaluated based on a comprehensive evaluation index considering static and dynamic indexes, and the preliminary grid division scheme with the maximum comprehensive evaluation index value is taken as the final grid division scheme. The application can improve the load reliability, interactivity and carrying capacity of the power distribution network, improve the equipment utilization and economy, greatly improve the overall efficiency of the power distribution network, and meet the randomness and flexibility requirements of the modern power distribution network load area.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power distribution network, and particularly relates to a power distribution network grid division method and system considering static and dynamic indexes. BACKGROUND

[0002] In the past few decades, with the increasing integration of distributed energy, electric vehicles and urbanization, power distribution planning has become increasingly important. With the rapid development of cities in China, constructing and operating power distribution networks in new urban areas is the primary task of power distribution system operators. The main goal of power distribution network planning is to optimize feeder routing using geographic information systems (GIS) to ensure the safe operation of power distribution networks under various conditions.

[0003] At present, there are many studies on power distribution network planning at home and abroad, which can be broadly divided into mathematical optimization methods, heuristic optimization methods and modern intelligent optimization algorithms. However, existing mathematical planning methods and intelligent heuristic methods, although relatively systematic, are difficult to implement due to complex modeling, immature algorithms and difficulty in manual intervention, and have few practical applications. In order to solve the above problems, the idea of grid division is introduced in power distribution network planning, and the large-scale power distribution network is divided into multiple power supply areas that are relatively independent in geography and electricity (only electrically connected at power supply substations), and then power distribution network planning is carried out for each small-scale power supply area, thereby alleviating the contradiction between the large scale of the power distribution network and the fine planning, and reducing the complexity of large-scale power distribution network planning. However, the traditional grid division method cannot meet the randomness and flexibility requirements of modern power distribution network load areas. SUMMARY

[0004] The purpose of the present application is to provide a power distribution network grid division method and system considering static and dynamic indexes to solve the above problems in the prior art.

[0005] To achieve the above purpose, the technical solutions of the present application are as follows:

[0006] In a first aspect, the present application provides a power distribution network grid division method considering static and dynamic indexes, comprising:

[0007] S1, establishing a power distribution network grid division model considering geographic information and aiming to minimize investment and operating costs;

[0008] S2, solving the power distribution network grid division model to obtain multiple preliminary grid division schemes;

[0009] S3, evaluating each preliminary grid division scheme based on a comprehensive evaluation index considering static and dynamic indexes, and taking the preliminary grid division scheme with the maximum comprehensive evaluation index value as the final grid division scheme, wherein,

[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 load area corresponding to load k in unit grid i to unit grid j, respectively. c In order 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 length of the feeder capacity equivalent line occupied by the load area k in the unit grid i, ΔD i(k),j P 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. i 、P j are the maximum loads of the load curves of unit grids i and j, For grid area i w Maximum load of load curve, P l Maximum load allowed for single line, L X,i , L X,j Average length of single line of grid i, j main power substation respectively, k z , k y , k h Depreciation coefficient, operation and maintenance cost coefficient and investment recovery coefficient respectively;

[0019] The F g,i(k),j Is 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 The annual income change value of the less power generation of distributed power caused by the penetration rate of distributed power exceeding the limit when the load k corresponding area in the unit grid i is adjusted to the unit grid j, ΔF g,i(k) The annual income reduction value of the less power generation of distributed power caused by the penetration rate of distributed power exceeding the limit in the unit grid i when the load k corresponding area in the unit grid i, ΔF g,j,k The annual income reduction value of the less power generation of distributed power caused by the penetration rate of distributed power exceeding the limit in the unit grid j when the load k corresponding area in the unit grid i is adjusted to the grid j.

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

[0024] F c = χ l + χ2+ χ3

[0025]

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

[0027] The objective function of the power distribution network grid division model in the S1 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, 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 the 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 operation cost per unit capacity of the substation, K is the total number of substations, J m is the load set supplied by the substation m, d l is the investment cost per unit length of the line, a is the line loss conversion coefficient, P n is the active load of the load n, l mn is the length of the line laid between the substation m and the load n, c mn is the additional wiring cost required when laying the line between the substation m and the load n;

[0031] The S2 includes:

[0032] S21, according to the number, capacity and location of the loads in the planning area, determine the appropriate number of substations K:

[0033]

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

[0035] S22, solve the power distribution network grid division model by using the improved K-Means algorithm, 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 and B are intermediate variables, e(S m ) is the load rate of the substation m, is the load synchronism rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the active power of the substation load, 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 solution module, and a scheme optimization module;

[0045] The grid division model construction 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 partitioning model solving module is used to solve the distribution network grid partitioning model and obtain multiple preliminary grid partitioning schemes;

[0047] The scheme optimization module is used to evaluate each preliminary grid division scheme based on a 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 load area corresponding to load k in unit grid i to unit grid j, respectively. cFor the dynamic index considering the load peak-valley coupling characteristics, β, η, ε are F l,i(k),j , F g,i(k),j , F c corresponding weights.

[0051] The F l,i(k),j is 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 an intermediate coefficient, d l is the investment cost per unit length of line, D i(k) is the distance between the virtual backbone line in the unit grid i w , i w is the grid area in the unit grid i , ΔF l,i(k),j is the change in revenue of the equivalent line occupied by the corresponding grid area in the unit grid i i(k) , ΔD i(k),j is the increase in the length of the equivalent line occupied by the corresponding grid area in the unit grid i i , P j are the maximum loads of the unit grids i and j, respectively, is the maximum load of the grid area i w , P l is the maximum load allowed by a single line, L X,i , L X,j are the average lengths of a single line of the main supply substation of the grids i and j, respectively, k z , k y , k h are the depreciation coefficient, the operation and maintenance cost coefficient, and the investment recovery coefficient, respectively.

[0057] The Fg,i(k),j 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 less power generation of the distributed power caused by the penetration rate of the distributed power exceeding the limit when the load k corresponding area in the unit grid i is adjusted to the unit grid j, ΔF g,i(k) is the annual revenue reduction value of the less power generation of the distributed power caused by the penetration rate of the distributed power exceeding the limit in the unit grid i when the load k corresponding area is in the unit grid i, ΔF g,j,k is the annual revenue reduction value of the less power generation of the distributed power caused by the penetration rate of the distributed power exceeding the limit in the unit grid j when the load k corresponding area in the unit grid i is adjusted to the grid j.

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

[0062] F c = χ l + χ2+ χ3

[0063]

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

[0065] The objective function of the power distribution grid division model comprises:

[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, 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 years of substation and line respectively, d o is the operation cost per unit capacity of substation, K is the total number of substations, J m is the load set powered by substation m, d l is the investment cost per unit length of line, a is the line loss conversion coefficient, P n is the active load of load n, l mn is the length of line laid between substation m and load n, c mn is the additional wiring cost required when laying line between substation m and load n;

[0069] The grid partitioning model solving module comprises a substation quantity determination unit and a model solving unit.

[0070] The substation quantity determination unit is configured to determine a suitable 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 , and R max are the minimum and maximum load capacity ratios allowed at the current voltage level respectively.

[0073] The model solving unit is configured to solve the distribution network grid partitioning model by using an 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 and B are intermediate variables, e(S m ) is the load rate of substation m, is the simultaneous load rate, cosθ is the power factor, is the mth cluster center in the cth iteration, i.e., substation m, P e is the active load power of the substation, is the load set powered by substation m in the cth iteration, f c is the evaluation function, F4 is a known value of substation cost, k mnPenalty coefficient for important area, if load n and substation m are in different administrative regions, k mn = 1, otherwise k mn = 1.

[0078] The constraint condition of the power distribution network grid division model comprises:

[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 power distribution network grid division method has the following beneficial effects:

[0083] 1. The power distribution network grid division method considering static and dynamic indexes first establishes a power distribution network grid division model considering geographic information and aiming to minimize investment and operation cost, then solves the power distribution network grid division model to obtain multiple grid division preliminary schemes, and finally evaluates each grid division preliminary scheme based on a comprehensive evaluation index considering static and dynamic indexes, so that the grid division preliminary scheme with the maximum comprehensive evaluation index value is taken as the final grid division scheme. The method proposes the comprehensive evaluation index considering static and dynamic indexes to optimize the grid division scheme, so that the final grid division scheme can improve the load reliability, interactivity and carrying capacity of the power distribution network, improve the equipment utilization rate and economy, greatly improve the overall efficiency of the power distribution network, and meet the randomness and flexibility requirements of the modern power distribution network load area.

[0084] 2. The power distribution network grid division method considering static and dynamic indexes proposes an improved K-Means algorithm, which considers the weight of the load node, the influence of adverse terrain and the capacity limit, and improves the distance, evaluation function and definition of the clustering center of the K-Means algorithm, so that the solving result is more in line with the actual demand. BRIEF DESCRIPTION OF DRAWINGS

[0085] Figure 1 A flowchart of the method described in Embodiment 1.

[0086] Figure 2 A structure diagram of the system described in the application. DETAILED DESCRIPTION

[0087] The application will be further described in detail in combination with the description of the drawings and specific embodiments.

[0088] Embodiment 1:

[0089] The embodiment takes a 110kV substation power supply area of a certain planning area (all 10kV main trunk line models of the area are LGJ-240, the maximum transmission capacity of single loop line is 7MW, the power factor is 0.9, and the simultaneous load rate is 0.85) as a research object, and a power distribution network grid division method considering static and dynamic indexes is implemented, as shown in Figure 1 The specific steps are as follows:

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

[0091] 2. Establish a power distribution network grid division model considering geographic information and taking the minimum investment and operation cost as the target.

[0092] The objective function of the power distribution network grid division 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, 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 the substation m, r0 is the annual interest rate, p and q are the depreciation period of the substation and the line respectively, d o is the operation cost per unit capacity of the substation, K is the total number of substations, J m is the load set supplied by the substation m, d l is the investment cost per unit length of the line, α is the line loss conversion coefficient, P n is the active load of load n, l mn is the line length laid between the substation m and the load n, c mn is the additional wiring cost needed when laying the line between the substation m and the load n, the more obstacles, the larger the value;

[0096] The constraint conditions start from the substation, considering the power supply capacity and power supply radius of the substation, 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. According to the number, capacity and location of the load of the planning area, the number of suitable substations K is determined:

[0101]

[0102] In the above formula, N' is the total number of loads, R min and R max are the minimum and maximum load capacity ratios allowed by the current voltage level, respectively. At this time, 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 converted into a constraint programming problem only related to the line length l mn and the additional wiring cost c mn .

[0105] 4. For the above constraint programming problem, an improved K-Means algorithm is used to solve the distribution network grid division model to obtain multiple grid division preliminary schemes. In the improved K-Means algorithm, the distance, evaluation function and cluster center are as follows:

[0106]

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

[0108]

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

[0110] 5. Static indicators of land use and dynamic indicators of load peak-valley coupling capacity are introduced, and static and dynamic mathematical models are established, respectively.

[0111] (1) Static index mathematical model

[0112] Considering the influence of different land property load characteristics on feeder power supply capacity, the load occupies the equivalent line investment or length (when the unit length investment is the same) of the feeder capacity to reflect.

[0113] If the load k in the unit grid i is adjusted to the unit grid j, the reduction value of the line cost caused thereby 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 reduction value of the line cost caused by adjusting the load k corresponding area in the unit grid i to the unit grid j, ε' is the intermediate coefficient, d l is the investment cost of the unit length line, D i(k) is the distance between the load k in the unit grid i and the virtual main line in the grid area i w , i w is the grid area in the unit grid i except the load k corresponding area, is the distance between the load k in the unit grid i and the virtual main line in the unit grid j, ΔF l,i(k),j is the change value of the income of the equivalent line occupied by the load k corresponding area in the unit grid i when adjusting to the grid j, ΔD i(k) is the increase value of the equivalent line length of the feeder capacity occupied by the load k corresponding area in the unit grid i, ΔD i(k),j is the increase value of the equivalent line length of the feeder capacity occupied by the load k in the unit grid i when adjusting to the unit grid j, P i , P j are the maximum loads of the load curves of the unit grids i and j, is the maximum load of the grid area i w load curve, P l is the maximum load allowed by a single line, L X,i , LX,j respectively, the average length of single line of grid i, j main supply substation, k z , k y , k h respectively, the depreciation coefficient, operation and maintenance cost coefficient and investment recovery coefficient, H i , H j respectively, the power supply area of unit grid i, j main supply substation, K' Z is the correction coefficient of feeder length, the correction coefficient of feeder length in the embodiment, taking 2.0.

[0120] Considering the limit of the maximum distributed power penetration of power supply subarea, if the area corresponding to load k in unit grid i is adjusted to unit grid j, the annual income increase value caused thereby 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 income increase value 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 income change value of less power generation of distributed power caused by the penetration rate of distributed power exceeding the limit when the area corresponding to load k in unit grid i is adjusted to unit grid j, ΔF g,i(k) is the annual income decrease value of less power generation of distributed power caused by the penetration rate of distributed power exceeding the limit in unit grid i when the area corresponding to load k is in unit grid i, ΔF g,j,k is the annual income decrease value of less power generation of distributed power caused by the penetration rate of distributed power exceeding the limit in unit grid j when the area corresponding to load k in unit grid i is adjusted to unit grid j.

[0124] (2) Dynamic index mathematical model

[0125] In order to achieve the best effect of grid division of distribution network and improve the power supply capacity in each grid division of distribution network, the overall load characteristics of each block should be optimized as much as possible. In order to achieve this goal, the peak-valley coupling ability between loads is maximized to adjust the overall load characteristics of the grid, and the following dynamic index of load peak-valley coupling ability is proposed:

[0126] F c = χ l + χ2+ χ3

[0127]

[0128]

[0129] In the above formula, F c is a dynamic index considering the load peak-valley coupling characteristics, χ l , χ2, χ3 are respectively the average load difference, the load rate structure of each block, and the average peak-valley difference rate, χ l is smaller, the load distribution of each unit grid is more uniform, χ2 is smaller, indicating that the load rate of each unit grid is larger and the numerical interval of the distribution is more concentrated, the equipment utilization is higher, χ3 is smaller, indicating that the overall peak-valley difference rate of the divided region is smaller, and the ability to relieve peak load is better, 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 the unit grid i, f i is the load rate of the unit grid i, f av is the average load rate of all unit grids, f ip is the peak-valley difference rate of the unit grid i.

[0130] 6. Determine the dynamic index mathematical model based on the static and dynamic index mathematical models, and evaluate each grid division preliminary scheme respectively by using a comprehensive evaluation index, so that the grid division preliminary scheme with the maximum comprehensive evaluation index value is taken as the final grid division scheme, wherein,

[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 the comprehensive evaluation index, the larger f is, the more reasonable the grid division is, and the better the effect of the power distribution network planning is, β, η, and ε are respectively the corresponding weights of F l,i(k),j , F g,i(k),j , and F c .

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

[0135] Table 1: Values of each performance evaluation index before and after optimization

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

[0137] As can be seen from Table 1, each performance index after optimization is improved compared with before optimization, and it can be seen that the grid division method proposed in the present application improves the load reliability, interactivity, and carrying capacity of the power distribution network to different degrees, reduces the redundancy of the power distribution network, improves the equipment utilization and economy, and greatly improves the overall performance of the power distribution network.

[0138] Embodiment 2:

[0139] A power distribution network grid division system considering static and dynamic indexes, as shown in the figure, comprises a grid division model construction module, a grid division model solving module and a scheme optimization module. Figure 2 The grid division model construction module is used for establishing a power distribution network grid division model considering geographic information and aiming at minimizing investment and operation costs.

[0140] 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 lines, 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 the 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 operation cost per unit capacity of the substation, K is the total number of substations, J m is the load set supplied by the substation m, d l is the investment cost per unit length of the line, α is the line loss conversion coefficient, P n is the active load of the load n, l mn is the length of the line laid between the substation m and the load n, c mn is the additional wiring cost needed when laying the line between the substation m and the load n.

[0144] The constraint conditions include:

[0145]

[0146] l mn ≤L m=1,2,...,K;n∈J m

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

[0148] The grid division model solving module is used for solving the power distribution network grid division model to obtain multiple preliminary grid division schemes, comprising a substation number determination unit and a model solving unit.

[0149] The substation number determination unit is used for determining the suitable number K of substations according to the number, capacity and location of the loads in the planning area.

[0150]

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

[0152] The model solving unit is configured to solve the power distribution network grid division model by using an improved K-Means algorithm, wherein the distance, evaluation function and clustering 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 are intermediate variables, e(S m ) is the load rate of the substation m, is the simultaneous rate of the load, cosθ is the power factor, is the mth clustering center in the cth iteration, i.e., the substation m, P e is the active power of the load of the substation, is the load set supplied by the substation m in the cth iteration, f c is the evaluation function, F4 is the known value of the substation cost, k mn is the important area penalty coefficient, if the load n and the substation m are in different administrative regions, k mn > 1, otherwise k mn = 1.

[0157] The scheme optimization module is configured to evaluate each grid division preliminary scheme based on a comprehensive evaluation index considering static and dynamic indexes, and take the grid division preliminary scheme with the maximum 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 =χ l +χ2+χ3

[0168]

[0169] In the above formula, F l,i(k),j , F g,i(k),j are the line cost reduction value and annual income increase value caused by adjusting the load k corresponding area in unit grid i to unit grid j, F c is a dynamic index considering the load peak-valley coupling characteristics, β, η, ε are the corresponding weights of F l,i(k),j , F g,i(k),j , F c , ε' is an intermediate coefficient, d l is the investment cost of the line per unit length, D i(k) is the distance between the load k in unit grid i and the grid area i w virtual main line, i w is the grid area in unit grid i except the load k corresponding area, is the distance between the load k in unit grid i and the virtual main line in unit grid j, ΔF l,i(k),j is the income change value of the equivalent line occupied by the corresponding grid area when the load k corresponding area in unit grid i is adjusted to grid j, ΔD i(k) is the increase value of the equivalent line length of the feeder capacity occupied by the load k corresponding area in unit grid i, ΔD i(k),j is the increase value of the equivalent line length of the feeder capacity occupied by the corresponding grid area when the load k in unit grid i is adjusted to unit grid j, P i , P j are the maximum load of the load curve of unit grid i, j, P iw is the maximum load of the load curve of the grid area i w , Pl Maximum load allowed for a single line, L X,i , L X,j Average length of a single line of the grid i, j main supply substation, k z , k y , k h Depreciation coefficient, operation and maintenance cost coefficient and investment recovery coefficient, H i , H j Power supply area of the unit grid i, j main supply substation, K' Z Correction coefficient of feeder length, correction coefficient of feeder length in the present embodiment, ΔF g,i(k),j Annual revenue change value of the distributed power less generated due to the distributed power penetration rate exceeding the limit when the load k corresponding area in the unit grid i is adjusted to the unit grid j, ΔF g,i(k) Annual revenue reduction value of the distributed power less generated due to the distributed power penetration rate exceeding the limit in the unit grid i when the load k corresponding area in the unit grid i, ΔF g,j,k Annual revenue reduction value of the distributed power less generated due to the distributed power penetration rate exceeding the limit in the unit grid j when the load k corresponding area in the unit grid i is adjusted to the unit grid j, χ l , χ2, χ3 are average load difference, load rate configuration of each block, average peak-valley difference rate, N is the number of unit grids, P max Maximum load value in the unit grid, P imax Maximum load of the unit grid i, f i Load rate of the unit grid i, f av Average load rate of all unit grids, f ip Peak-valley difference rate of the 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. Solve the distribution network grid division model and obtain 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=βΣF 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 load k corresponding area 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; 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.

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 length of the feeder capacity equivalent line occupied by the load area k in the unit grid i, ΔD i(k),j P 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, 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, P l is the maximum load allowed for a single line, L X,i 、L X,j are the average lengths of single lines of main power substations in grids i and 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 When the area corresponding to load k in unit grid i is adjusted to unit grid j, the annual income change value of distributed generation due to the over-limit of distributed generation penetration causing less power generation, ΔF g,i(k) When the load k corresponds to the area in the unit grid i, the annual revenue reduction value of the unit grid i caused by the distributed generation of less power due to the distributed generation penetration rate exceeding the limit, ΔF g,j,k When the area corresponding to load k in unit grid i is adjusted to grid j, the annual revenue reduction of unit grid j due to the less power generation of distributed generation caused by the distributed generation penetration rate exceeding the limit.

3. 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 years of substation and line respectively, d o is the unit capacity operating 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 respectively; S22. Use the improved K-Means algorithm to solve the distribution network grid partitioning model. 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 synchronism rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the active power of the substation load, 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.

4. A distribution network grid division method considering static and dynamic indicators according to claim 3, characterized in that: The constraints of the distribution network grid partitioning model include: In the above formula, L is the maximum power supply capacity radius of the substation.

5. A distribution network grid division system considering static and dynamic indicators, characterized in that: The system includes a grid partitioning model building module, a grid partitioning model solving module, and a scheme optimization module; The grid division model construction 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 partitioning model solving module is used to solve the distribution network grid partitioning model and obtain multiple preliminary grid partitioning schemes; The scheme optimization module is used to evaluate each preliminary grid division scheme based on a 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 load k corresponding area 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; 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.

6. A distribution network grid division system considering static and dynamic indicators according to claim 5, 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 length of the feeder capacity equivalent line occupied by the load area k in the unit grid i, ΔD i(k),j P 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, 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 single lines of main power substations in grids i and 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 When the area corresponding to load k in unit grid i is adjusted to unit grid j, the annual income change value of distributed generation due to the over-limit of distributed generation penetration causing less power generation, ΔF g,i(k) When the load k corresponds to the area in the unit grid i, the annual revenue reduction value of the unit grid i caused by the distributed generation of less power due to the distributed generation penetration rate exceeding the limit, ΔF g,j,k When the area corresponding to load k in unit grid i is adjusted to grid j, the annual revenue reduction of unit grid j due to the less power generation of distributed generation caused by the distributed generation penetration rate exceeding the limit.

7. A distribution network grid division system considering static and dynamic indicators according to claim 5 or 6, 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 years of substation and line respectively, d o is the unit capacity operating 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 number determination unit is used to determine the appropriate number K of substations 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 respectively; 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 synchronism rate, cosθ is the power factor, is the mth cluster center of the cth iteration, i.e., substation m, P e is the active power of the substation load, 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.

8. A distribution network grid division system considering static and dynamic indicators according to claim 7, characterized in that: The constraints of the distribution network grid partitioning model include: In the above formula, L is the maximum power supply capacity radius of the substation.

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