Substation planning method and device considering hierarchical allocation

Abstract

The present invention discloses a substation planning method and device considering hierarchical distribution, belonging to the technical field of distribution network planning, the method includes determining the capacity combination of a newly built substation and the initial site of the newly built substation; calculating the optimal power supply radius of each substation based on the total load density and the power supply capacity of each substation; according to the conventional Voronoi diagram, in the distribution area corresponding to the load in each power supply area, the load is distributed to the corresponding substation according to the principle of nearest distribution; according to the weighted Voronoi diagram algorithm, the load distribution between each substation is adjusted; according to the conventional Voronoi diagram, the undistributed load is distributed to the nearest substation to complete the power supply range division; with the minimum total cost as the goal, the optimal new substation capacity, new substation location and corresponding power supply range division plan are obtained. The three levels of distribution have clear division principles and boundaries, and duplicate distribution and invalid distribution are avoided under the premise of ensuring that all loads are distributed, thereby improving the speed and accuracy of power supply range division.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network planning, and in particular to a substation planning method and device considering hierarchical distribution. Background Art

[0002] The site selection, capacity determination and power supply range division of substations are important links in distribution network planning, and their results directly affect the network structure, power supply reliability, construction and economic efficiency of operation and maintenance of the future distribution network. Reasonable planning results of substation location and power supply range division can greatly promote the economy and safety of the distribution network, and can obtain great economic and social benefits; on the contrary, unreasonable planning errors will cause irreparable losses to the safety, economy and subsequent upgrade and operation and maintenance of the distribution network.

[0003] At present, many studies have been conducted both at home and abroad on the planning of distribution network substations, and the theoretical research on distribution network substation planning has become relatively mature. However, in the power supply range division stage, since the load rate of each substation must meet the "N-1" planning principle, and the capacity combination schemes of optional new stations given based on economic considerations have compressed the total capacity to a very small extent, the flexibility of power supply range division has been reduced, and high requirements have been placed on the allocation method and weight setting of each iteration.

[0004] At present, the research on the power supply range division stage mainly focuses on the optimization level of weights. For example, in the invention patent application with application number 201710256654.4, a planning method for active distribution network substation based on improved weighted Voronoi diagram is proposed, including: hierarchical improvement of weighted Voronoi diagram and directional improvement of weighted Voronoi diagram, each iteration of weighted Voronoi diagram algorithm is completed in 3 steps, that is, the power supply range of substation is expanded in three steps, wherein the weight of weighted Voronoi diagram changes in each step of expansion, and the weight depends on the load carried by the substation after the previous step of expansion and the capacity of the substation itself. By correcting the weight setting of the next time by the power supply range division result of the previous iteration, this method often has extreme changes in weights, resulting in repeated changes in the division results and failure to converge; there is also a method in which the weight gradually reduces the adjustment range with the increase of iteration times, which reduces the possibility of repeated changes but easily leads to a small influence of weights in the later stage and failure to converge. Another part of the research proposed a hierarchical improvement of weights, dividing the power supply range into three steps to improve the convergence speed. However, this type of research calculates the weights and power supply radius in each step, which makes the algorithm more complicated. In addition, the boundaries of the three-step allocation are all calculated values, with no obvious distinction and easy overlap, resulting in poor convergence for complex examples. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to increase the algorithm speed and convergence reliability of distribution network substation planning.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] On the one hand, the present invention proposes a substation planning method considering hierarchical allocation, the method comprising the following steps:

[0008] Determine the capacity combination of the new substation and the initial site of the new substation;

[0009] Calculating the optimal power supply radius of each of the substations based on the total load density and the power supply capacity of each of the substations;

[0010] According to the conventional Voronoi diagram, in the distribution area corresponding to the load in each power supply area, the load is distributed to the corresponding substation according to the principle of proximity distribution, and the power supply radius limit of the substation is a times the optimal power supply radius of the substation;

[0011] The load distribution between the substations is adjusted according to the weighted Voronoi diagram algorithm, and the power supply radius limit of each substation is the maximum power supply radius of the substation set in the specification;

[0012] According to the conventional Voronoi diagram, the unallocated load is distributed to the nearest substation to complete the division of power supply range;

[0013] With the goal of minimizing the total cost, the optimal new substation capacity, new substation location and corresponding power supply range division plan are obtained.

[0014] In the process of substation planning, the present invention divides the power supply range division process into three steps based on the hierarchical allocation process, gradually expanding the power supply radius limit. In the first step, the allocation is based on the principle of nearby allocation of substations and loads, so the weight is fixed to 1; in the second step, the weight calculation idea of ​​the system is set by considering factors such as substation capacity and the effect of the last iterative allocation. The weight allocated in the third step is based on the principle of all load allocation, and the load that was not allocated in the first two steps is allocated to the nearest substation, so the weight is also fixed to 1. The three levels of allocation have clear division principles, and the loads allocated three times have clear boundaries. On the premise of ensuring that all loads are allocated, the possibility of repeated allocation and invalid allocation is avoided, and the speed and accuracy of power supply range division are improved.

[0015] Furthermore, the determining of the capacity combination of the newly built substation and the initial site of the newly built substation includes:

[0016] Calculate the range of the number of new substations required in the target year based on the total load in the target year, the capacity and number of existing substations in the current year, and the candidate capacity types of substations;

[0017] Based on the number of new substations required in the target year and the candidate capacity types of the substations, a model is established with the goal of minimizing the annual investment cost of new substations and the substation capacity-load ratio requirement as a constraint condition to determine the capacity combination of new substations;

[0018] For each new substation capacity combination, the initial site of the new substation is determined by coordinate geometry method.

[0019] Furthermore, the calculation formula of the optimal power supply radius of the substation is as follows:

[0020]

[0021] Among them, R i is the optimal power supply radius of the ith substation, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, π is the circumference of a circle, P ∑ It is the grid supply load of the power supply area in the target year.

[0022] Furthermore, the weight calculation formula in the weighted Voronoi diagram algorithm is as follows:

[0023] When j=1, the initial weight is 1;

[0024] When j=2, the weight calculation adopts the initial weight calculation formula:

[0025] When j≥3, the weight calculation formula is:

[0026]

[0027]

[0028] Among them, j is the number of iterations, rlbl i (j) is the capacity ratio of the i-th substation after the j-th iteration, P i (j,3) is the active power sum of the load carried by the ith substation after the third allocation in the jth iteration, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, △w i (j) is the weight change of the ith substation in the jth iteration, wi (j) is the weight of the ith substation in the jth iteration.

[0029] Furthermore, when the weighted Voronoi diagram algorithm is used to calculate the weight, the method further includes:

[0030] Determine whether the calculated weight of the i-th substation in the j-th iteration is within the set interval;

[0031] If so, determine the weight as the weight of the i-th substation in the j-th iteration;

[0032] If not, the weight is corrected to the boundary of the set interval as the weight of the i-th substation in the j-th iteration.

[0033] Furthermore, when the weighted Voronoi diagram algorithm is used to calculate the weight, the method further includes:

[0034] The initial weight calculation formula is periodically used to disturb the weight change.

[0035] Furthermore, after allocating the unallocated load to the nearest substation according to the conventional Voronoi diagram and completing the division of the power supply range, the method further includes:

[0036] In the power supply range division results, a single-median location selection algorithm is used for each power supply area, with the minimum load distance as the goal, and the fminsearch function is used to solve the optimal median point as the location of the substation;

[0037] When the load rate of the substation satisfies the N-1 principle and the change distance between the position of the substation in this iteration and the position of the previous iteration is 0, it is determined that the results of the substation address correction and power supply range division are converged.

[0038] On the other hand, the present invention also proposes a substation planning device considering hierarchical allocation, the device comprising:

[0039] A determination module is used to determine the capacity combination of the new substation and the initial site of the new substation;

[0040] A power supply radius calculation module, used to calculate the optimal power supply radius of each substation based on the total load density and the power supply capacity of each substation;

[0041] A first allocation module is used to allocate to the corresponding substation in the allocation area corresponding to the load in each power supply area according to the principle of proximity allocation according to the conventional Voronoi diagram, and the power supply radius limit of the substation is a times the optimal power supply radius of the substation;

[0042] A second allocation module is used to adjust the load distribution between the substations according to the weighted Voronoi diagram algorithm, and the power supply radius limit of each substation is the maximum power supply radius of the substation set in the specification;

[0043] A third allocation module is used to allocate the unallocated load to the nearest substation according to the conventional Voronoi diagram to complete the division of power supply range;

[0044] The planning scheme determination module is used to obtain the optimal new substation capacity, new substation location and corresponding power supply range division scheme with the goal of minimizing total cost.

[0045] Furthermore, the weight calculation formula in the weighted Voronoi diagram algorithm is as follows:

[0046] When j=1, the initial weight is 1;

[0047] When j=2, the weight calculation adopts the initial weight calculation formula:

[0048] When j≥3, the weight calculation formula is:

[0049]

[0050]

[0051] Among them, j is the number of iterations, rlbl i (j) is the capacity ratio of the i-th substation after the j-th iteration, P i (j,3) is the active power sum of the load carried by the ith substation after the third allocation in the jth iteration, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, △w i (j) is the weight change of the ith substation in the jth iteration, w i (j) is the weight of the ith substation in the jth iteration.

[0052] Furthermore, the device also includes:

[0053] A weight adjustment module, used for correcting the weight to the boundary of the set interval as the weight of the i-th substation in the j-th iteration when the calculated weight of the i-th substation in the j-th iteration is not within the set interval;

[0054] The disturbance module is used to periodically disturb the weight change using the initial weight calculation formula.

[0055] The advantages of the present invention are:

[0056] (1) In the process of substation planning, the present invention divides the power supply range division process into three steps based on the hierarchical allocation process, gradually expanding the power supply radius limit. In the first step, the allocation is based on the principle of nearby allocation of substations and loads, so the weight is fixed to 1; in the second step, the weight calculation idea of ​​the system is set by considering factors such as substation capacity and the effect of the previous iterative allocation. The weight of the third step is based on the principle of all load allocation, and the load that was not allocated in the first two steps is allocated to the nearest substation, so the weight is also fixed to 1. The three levels of allocation have clear division principles, and the loads allocated three times have clear boundaries. On the premise of ensuring that all loads are allocated, the possibility of repeated allocation and invalid allocation is avoided, and the speed and accuracy of power supply range division are improved.

[0057] (2) In the second allocation process, upper and lower limit constraints are added to address extreme changes in weights, thus avoiding repeated changes in the partitioning results.

[0058] (3) In the second allocation process, the periodic perturbation weight algorithm is used to solve the problem that the influence of the weight gradually decreases as the number of iterations increases, thereby increasing the convergence of the algorithm.

[0059] (4) The location of the new substation is corrected by using a multi-dimensional unconstrained linear optimization method, and the location of the new substation and the power supply range division results are gradually improved, so that the best location of the new substation and the optimal power supply range division scheme can be obtained.

[0060] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flow chart of a substation planning method considering hierarchical allocation in a first embodiment of the present invention;

[0062] Figure 2 is an overall flow chart of a substation planning method considering hierarchical allocation in a first embodiment of the present invention;

[0063] Figure 3 It is a schematic diagram of load distribution in the planning area in the present invention;

[0064] Figure 4 It is the load attribution diagram obtained by using the traditional algorithm to conduct case tests;

[0065] Figure 5 It is a load attribution diagram obtained by carrying out example tests using the method of the present invention;

[0066] Figure 6It is a structural diagram of a substation planning device considering hierarchical allocation in the second embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] like Figure 1 As shown, an embodiment of the present invention proposes a substation planning method considering hierarchical allocation, and the method includes the following steps:

[0069] S10, determining the capacity combination of the new substation and the initial site of the new substation;

[0070] S20, calculating the optimal power supply radius of each substation based on the total load density and the power supply capacity of each substation;

[0071] S30, according to the conventional Voronoi diagram, in the distribution area corresponding to the load in each power supply area, the load is distributed to the corresponding substation according to the principle of proximity distribution, and the power supply radius limit of the substation is a times the optimal power supply radius of the substation;

[0072] It should be noted that, after a large number of calculation examples and tests, when a is 0.7, the load rate of the corresponding power station can generally reach more than 80% of its upper limit, so a=0.7 is generally set.

[0073] It should be understood that in the first allocation, the load is allocated to the substation based on the principle of the closest actual distance, so the weight is fixed at 1.

[0074] S40, adjusting the load distribution among the substations according to the weighted Voronoi diagram algorithm, wherein the power supply radius limit of each substation is the maximum power supply radius of the substation set in the specification;

[0075] It should be noted that the power supply radius is limited to the maximum power supply radius of the substation set by the regulations, which is generally 5km in rural areas and 2km in urban areas.

[0076] S50, according to the conventional Voronoi diagram, allocating the unallocated load to the nearest substation to complete the division of power supply range;

[0077] It should be noted that in most examples, after the allocation in step S30 and step S40, all loads can be allocated to the corresponding substations. However, considering the extreme cases such as large capacity differences between substations and extremely uneven load distribution, there are still loads that cannot be allocated to substations after the second allocation. Therefore, the principle of the third allocation is to allocate all loads without considering the limitation of the power supply radius, and use the conventional Voronoi diagram algorithm for load allocation, that is, all values ​​are 1.

[0078] S60. With the goal of minimizing the total cost, the optimal new substation capacity, new substation location and corresponding power supply range division plan are obtained.

[0079] Based on the hierarchical allocation process, this embodiment divides each complete power supply range division process into three steps, gradually expands the power supply radius limit, and gives priority to the principle of nearby distribution of substations and loads in the first step of allocation; in the second step of allocation, the power supply capacity of the substation after the first two iterations and the advantages and disadvantages of the weight setting of the previous iteration are fully considered; in the third step of allocation, the principle of all loads being allocated is considered. This ensures that the three levels of allocation have clear division principles, and the loads allocated three times have clear boundaries. On the premise of ensuring that all loads are allocated, the possibility of repeated allocation and invalid allocation is avoided, and the speed and accuracy of power supply range division are improved.

[0080] In one embodiment, the step S10 includes the following steps:

[0081] S11. Calculate the range of the number of new substations required in the target year based on the total load in the target year, the capacity and number of existing substations in the current year, and the candidate capacity types of substations;

[0082] It should be noted that the maximum number of new substations required in the target year is n max And the minimum number n min The calculation formula is:

[0083]

[0084]

[0085] Among them, P ∑ is the grid load of the power supply area in the target year, P y is the total active capacity of existing substations in the current year (mainly the maximum active power that existing stations can provide), S max and S min are the maximum and minimum capacity of the candidate substation types, respectively, max and z min They are the upper and lower limits of the load ratio allowed by the specification, is the power factor.

[0086] S12, based on the number of new substations required in the target year and the candidate capacity types of the substations, with the goal of minimizing the annual investment cost of new substations and the substation capacity-load ratio requirement as a constraint condition, a model is established to determine the capacity combination of new substations;

[0087] It should be noted that, under the premise that the number of new stations n has been determined, n min ≤n≤n max According to the candidate capacity types of new substations, a mathematical model can be established with the goal of minimizing the annual investment cost of new substations and the constraint of satisfying the requirements of the substation capacity-load ratio, and finally m groups of optimal new substation capacity combinations can be determined. The mathematical model is as follows:

[0088]

[0089]

[0090]

[0091] Where p is the number of candidate substation types, CZ k is the investment cost of the kth candidate type substation, CU k is the annual operating cost of the kth candidate type substation, x k is the number of substations of the kth candidate type to be built, S k is the capacity of the kth candidate substation after considering the load rate, S exist is the total capacity that can be provided by the existing substation after considering the load rate, r 0 is the discount rate, and ms is the depreciation period of the substation.

[0092] It should be noted that the above mathematical model can be solved by integer programming method, and finally each n can obtain a maximum of m capacity combination schemes corresponding to it, which can be used for comparison of the total cost after the subsequent power supply range division.

[0093] S13. For each new substation capacity combination, determine the initial site of the new substation by using coordinate geometry method.

[0094] Furthermore, for each combination of the number of stations n, the initial site of the new station is determined by the coordinate geometry method, and the process is as follows:

[0095] (1) Find the center of the regional load, use it as the center of a circle, and draw a circle with a radius of half the distance from the center to the regional border;

[0096] (2) Divide the circle into n equal parts and use the equally divided points on the arc as the initial sites of n newly built substations.

[0097] It should be noted that if a substation can be built in the city center, the regional center can be first determined as the site of one of the new stations, and then the arc n-1 can be divided into equal parts as the initial sites of other new stations.

[0098] In one embodiment, in step S20, the calculation formula of the optimal power supply radius of the substation is as follows:

[0099]

[0100] Among them, R i is the optimal power supply radius of the ith substation, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, π is the circumference of a circle, P ∑ It is the grid supply load of the power supply area in the target year.

[0101] In one embodiment, in step S0, the weight calculation formula in the weighted Voronoi diagram algorithm is as follows:

[0102] When j=1, the initial weight is 1;

[0103] When j=2, the weight calculation adopts the initial weight calculation formula:

[0104] When j≥3, the weight calculation formula is:

[0105]

[0106]

[0107] Among them, j is the number of iterations, rlbl i (j) is the capacity ratio of the i-th substation after the j-th iteration, P i (j,3) is the active power sum of the load carried by the ith substation after the third allocation in the jth iteration, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, △w i (j) is the weight change of the ith substation in the jth iteration, w i (j) is the weight of the ith substation in the jth iteration.

[0108] It should be noted that this embodiment simplifies the weight calculation method for three times. The first weight is allocated based on the principle of the closest actual distance, so the weight is fixed at 1; the third weight is allocated based on the principle of all allocation to allocate the unallocated loads of the first two times to the nearest substation, so the weight is also fixed at 1; the second allocation sets the system's weight calculation ideas to consider factors such as substation capacity and the effect of the previous iterative allocation. Compared with the weight calculation for all three allocations (the first and third times are not fixed), this weight calculation method first simplifies the weight calculation steps for each iteration and saves time for each iteration; secondly, it retains the correlation between the weight of each iteration and the weight of the previous iteration, which is conducive to the improvement of the weight in a more favorable direction for convergence as the number of iterations increases.

[0109] In one embodiment, when the weighted Voronoi diagram algorithm is used to calculate the weights, the following steps are also included:

[0110] Determine whether the calculated weight of the i-th substation in the j-th iteration is within the set interval;

[0111] If so, determine the weight as the weight of the i-th substation in the j-th iteration;

[0112] If not, the weight is corrected to the boundary of the set interval as the weight of the i-th substation in the j-th iteration.

[0113] It should be noted that the general weight is a value near 1. When it deviates too much from 1, it is easy to cause repeated alternation, but when it deviates too little from 1, it is similar to the slow convergence of the conventional V graph. Therefore, the upper and lower limits of this interval are parameters that can be set in the program. In order to avoid repeated division results of the power supply range when the weight is extremely large or extremely small, the upper and lower limits of the weight can be set to 1.4 and 0.6 respectively. When the weight exceeds this interval, the weight is corrected to the boundary of 1.4 or 0.6.

[0114] In one embodiment, when the weighted Voronoi diagram algorithm is used to calculate the weights, the following steps are also included:

[0115] The initial weight calculation formula is periodically used to disturb the weight change.

[0116] It should be noted that in order to prevent the weight from becoming less influential and unable to converge as the number of iterations increases, based on the analysis of weight changes, it is found that this type of weight calculation method generally tends to stabilize after about 30 iterations and no longer has an obvious correction effect. Therefore, the initial weight formula is used every 30 times for perturbation to increase the correction effect of the weight.

[0117] It should be noted that, in the second-level weight process, this embodiment adds upper and lower limit constraints for extreme weight changes, thereby avoiding repeated alternation of division results; thirdly, it uses a periodic perturbation weight algorithm to solve the problem of the gradual reduction of the influence of the weight as the number of iterations increases, thereby increasing the convergence of the algorithm.

[0118] In one embodiment, if Figure 2 As shown, after step S50, the following steps are also included:

[0119] In the power supply range division results, a single-median location selection algorithm is used for each power supply area, with the minimum load distance as the goal, and the fminsearch function is used to solve the optimal median point as the location of the substation;

[0120] When the load rate of the substation satisfies the N-1 principle and the change distance between the position of the substation in this iteration and the position of the previous iteration is 0, it is determined that the results of the substation address correction and power supply range division are converged.

[0121] It should be noted that, in this embodiment, according to the power supply range division result completed in the above allocation steps, each power supply area uses a planar single median location selection algorithm, takes the minimum load distance as the goal, and uses the fminsearch function to solve the optimal median point as the latest location of the substation.

[0122] The load rate of the calculation station is calculated to see whether it can meet the constraint condition of the "N-1" principle. At the same time, the change distance between the location of the substation in this iteration and the location of the substation in the previous iteration is calculated to determine whether the convergence condition of the change distance being 0 is met. If both conditions are met, the results of the site correction and power supply range division of the new substation have converged, and the line cost and network loss cost of the corresponding solution can be calculated based on the load distance; if the above two conditions are not met, return to step S30 for the next iteration.

[0123] It should be noted that this embodiment introduces the concept of hierarchical allocation in the process of substation power supply range division and new substation location correction. First, based on the hierarchical allocation process, each complete power supply range division is divided into three steps to complete, and the power supply radius limit is gradually expanded. In the first step of allocation, the principle of nearby allocation of substations and loads is given priority; in the second step of allocation, the power supply capacity of the substation after the first two iterations and the advantages and disadvantages of the weight setting of the previous iteration are fully considered; in the third step of allocation, the principle of all loads are allocated. Thirdly, the upper and lower limits of the weights are constrained, and the perturbation weight algorithm is used regularly to optimize the weight changes. Finally, the multi-dimensional unconstrained linear optimization method is used to correct the location of the new substation, and the location of the new substation and the power supply range division results are gradually improved. The best location of the new substation and the optimal power supply range division scheme are finally obtained through the above alternating positioning allocation algorithm.

[0124] In one embodiment, in step S60, the feasible solutions for power supply range division obtained in the previous step are compared and selected, and the solution with the lowest total cost is selected as the best, and the optimal number, capacity, location and corresponding power supply range division solution of new stations are obtained. Among them, the objective function is to minimize the sum of costs including substation construction and maintenance costs, line construction and maintenance costs, network loss, etc., and its mathematical model is as follows:

[0125]

[0126]

[0127]

[0128]

[0129] Among them, C Station is the annual cost of substation construction and maintenance, C Feeder is the annual cost of line investment on the low voltage side of the substation, C CQ is the annual cost of line loss on the low-voltage side of the substation, N is the total number of existing and newly built substations, P j is the load value of the jth load point, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, J i is the set of loads supplied by the ith substation, J is the set of all load points, n is the number of newly built substations, r 0 is the discount rate, ms is the depreciation period of the substation, CZ i is the investment cost of the ith substation, CU i is the annual operating cost of the ith substation, β is the unit length construction cost coefficient of the substation outgoing line, d ij is the distance from the ith substation to the jth load, and α is the conversion coefficient of line network loss.

[0130] This example is a newly built area in a county town, which covers an area of ​​63.08 square kilometers. The area was divided into 351 communities during planning. The predicted grid load in the target year is 1257.36MW, with a power factor of 0.9. The load distribution in the planning area is as follows: Figure 3 shown.

[0131] According to the "N-1" principle, the load rate of the substation with two main transformers is limited to 65%, and the load rate of the substation with three main transformers is limited to 86.7%, and the substation planning is carried out on this basis. The two methods of traditional distribution network substation planning and the distribution network substation planning with hierarchical allocation adopted by the present invention are compared and tested by examples. The load attribution results are as follows: Figure 4 , Figure 5 shown.

[0132] The comparison of the optimal substation location, capacity and load rate of the two algorithms is shown in Table 1. The comparison of the maximum running time, number of feasible solutions and calculation cost of the two algorithms is shown in Table 2:

[0133] Table 1 Comparison of optimal substation location, capacity and load rate of the two algorithms

[0134]

[0135] Table 2 Comparison of the maximum running time, number of feasible solutions and computational cost of the two algorithms

[0136]

[0137] From the above test dismissal we can see that:

[0138] (1) Total cost: The optimal solution is Scheme 1. The line cost of the algorithm of the present invention is better, which is 92,850 yuan less than that of the traditional algorithm. Comparing the 12 solutions that can be solved, the algorithm of the present invention has a lower cost in 9 solutions, and the traditional algorithm has a lower cost in 3 solutions.

[0139] It should be noted that each calculation example will result in n types of station numbers, and each type of station number corresponds to m groups of capacity combination schemes, so there are a total of m*n groups of capacity combination schemes. Each of these schemes will be divided into power supply ranges to obtain a convergent solution, and finally the optimal solution will be obtained through comparison.

[0140] The scheme 1 mentioned here is the first capacity combination scheme in the first station number type. Since the present invention is mainly aimed at improving the power supply range division module, the purpose of listing it here is to compare the results obtained by the same scheme. The results of the present invention are better, that is, the power supply range division of the present invention under the same scheme is more reasonable.

[0141] (2) Feasible solutions: The number of solutions solved by the algorithm of the present invention is 8 more than that of the traditional algorithm. The algorithm of the present invention can solve all the solutions that can be solved by the traditional algorithm.

[0142] (3) Number of iterations: For comparison of 12 solutions that can be solved, the algorithm of the present invention has fewer iterations for 8 solutions, and the traditional algorithm has fewer iterations for 4 solutions. The total number of iterations of the patent algorithm is 665 times, and the traditional algorithm is 923 times. The algorithm of the present invention has 258 fewer iterations than the traditional algorithm.

[0143] (4) Running time: The overall algorithm of the present invention is 42.9 seconds shorter than the traditional algorithm, and the time is shortened by 9.7%. All 12 solutions were solved for comparison. The algorithm of the present invention took shorter time for 7 solutions, and the traditional algorithm took shorter time for 5 solutions. The combined statistics of 12 times showed that the algorithm of the present invention took 19.33 seconds, and the traditional algorithm took 23.67 seconds. The algorithm of the present invention was 4.34 seconds shorter than the traditional algorithm, and the time was shortened by 18.33%.

[0144] The overall comparison is visible. In terms of algorithm accuracy, the algorithm cost of the present invention is better for the same scheme, and the results of substation site selection and power supply range division are more reasonable; from the perspective of computational efficiency, the time of each iteration of the algorithm of the present invention is slightly increased, but the number of iterations is significantly reduced, which is conducive to shortening the overall running time; from the perspective of algorithm convergence reliability, each of the three allocations has a clear allocation purpose, and then through the site correction and weight correction of each iteration, it is improved, which is higher than the iteration efficiency of the traditional algorithm, which is conducive to increasing the number of solutions that can obtain converged solutions.

[0145] In addition, if Figure 6 As shown, the embodiment of the present invention also proposes a substation planning device considering hierarchical allocation, the device comprising:

[0146] A determination module 10 is used to determine the capacity combination of the new substation and the initial site of the new substation;

[0147] A power supply radius calculation module 20, used to calculate the optimal power supply radius of each substation based on the total load density and the power supply capacity of each substation;

[0148] The first allocation module 30 is used to allocate to the corresponding substation in the allocation area corresponding to the load in each power supply area according to the principle of proximity allocation according to the conventional Voronoi diagram, and the power supply radius limit of the substation is a times the optimal power supply radius of the substation;

[0149] A second allocation module 40 is used to adjust the load distribution between the substations according to the weighted Voronoi diagram algorithm, and the power supply radius limit of each substation is the maximum power supply radius of the substation set in the specification;

[0150] A third allocation module 50 is used to allocate the unallocated load to the nearest substation according to the conventional Voronoi diagram to complete the division of power supply range;

[0151] The planning scheme determination module 60 is used to obtain the optimal new substation capacity, new substation location and corresponding power supply range division scheme with the goal of minimizing the total cost.

[0152] It should be noted that this embodiment is based on the hierarchical allocation process, and each complete power supply range division process is divided into three steps to complete, gradually expanding the power supply radius limit. In the first step of allocation, the principle of nearby allocation of substations and loads is given priority; in the second step of allocation, the power supply capacity of the substation after the first two iterations and the advantages and disadvantages of the weight setting of the previous iteration are fully considered; in the third step of allocation, the principle of all loads being allocated is considered. This ensures that the three levels of allocation have clear division principles, and the loads allocated three times have clear boundaries. On the premise of ensuring that all loads are allocated, the possibility of repeated allocation and invalid allocation is avoided, and the speed and accuracy of power supply range division are improved.

[0153] In one embodiment, the weight calculation formula in the weighted Voronoi diagram algorithm is as follows:

[0154] When j=1, the initial weight is 1;

[0155] When j=2, the weight calculation adopts the initial weight calculation formula:

[0156] When j≥3, the weight calculation formula is:

[0157]

[0158]

[0159] Among them, j is the number of iterations, rlbl i (j) is the capacity ratio of the i-th substation after the j-th iteration, P i (j,3) is the active power sum of the load carried by the ith substation after the third allocation in the jth iteration, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, △w i (j) is the weight change of the ith substation in the jth iteration, w i (j) is the weight of the ith substation in the jth iteration.

[0160] It should be noted that the second allocation sets up a systematic weight calculation idea to consider factors such as substation capacity and the effect of the previous iteration allocation. Compared with the weight calculation for all three allocations (the first and third are not fixed), this weight calculation method first simplifies the weight calculation steps for each iteration and saves the time for each iteration; secondly, it retains the correlation between the weight of each iteration and the weight of the previous iteration, which is conducive to the improvement of the weight in a more favorable direction for convergence as the number of iterations increases.

[0161] In one embodiment, the device further comprises:

[0162] A weight adjustment module, used for correcting the weight to the boundary of the set interval as the weight of the i-th substation in the j-th iteration when the calculated weight of the i-th substation in the j-th iteration is not within the set interval;

[0163] The disturbance module is used to periodically disturb the weight change using the initial weight calculation formula.

[0164] It should be noted that, in the second-level weight process, this embodiment adds upper and lower limit constraints for extreme weight changes, thereby avoiding repeated alternation of division results; thirdly, it uses a periodic perturbation weight algorithm to solve the problem of the gradual reduction of the influence of the weight as the number of iterations increases, thereby increasing the convergence of the algorithm.

[0165] It should be noted that other embodiments of the substation planning device considering hierarchical allocation described in the present invention or implementation methods can refer to the above-mentioned method embodiments, which will not be repeated here.

[0166] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0167] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0168] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0169] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0170] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A substation planning method considering hierarchical allocation, characterized in that: The method comprises: Determine the capacity combination of the new substation and the initial site of the new substation; Calculating the optimal power supply radius of each of the substations based on the total load density and the power supply capacity of each of the substations; According to the conventional Voronoi diagram, in the distribution area corresponding to the load in each power supply area, the load is distributed to the corresponding substation according to the principle of proximity distribution, and the power supply radius limit of the substation is a times the optimal power supply radius of the substation; The load distribution between the substations is adjusted according to the weighted Voronoi diagram algorithm, and the power supply radius limit of each substation is the maximum power supply radius of the substation set in the specification; According to the conventional Voronoi diagram, the unallocated load is distributed to the nearest substation to complete the division of power supply range; With the goal of minimizing the total cost, the optimal new substation capacity, new substation location and corresponding power supply range division plan are obtained; The weight calculation formula in the weighted Voronoi diagram algorithm is as follows: When j=1, the initial weight is 1; When j=2, the weight calculation adopts the initial weight calculation formula: When j≥3, the weight calculation formula is: Among them, j is the number of iterations, rlbl i (j) is the capacity ratio of the i-th substation after the j-th iteration, P i (j,3) is the active power sum of the load carried by the ith substation after the third allocation in the jth iteration, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, △w i (j) is the weight change of the ith substation in the jth iteration, w i (j) is the weight of the ith substation in the jth iteration; When the weighted Voronoi diagram algorithm is used to calculate the weight, the method further includes: Determine whether the calculated weight of the i-th substation in the j-th iteration is within the set interval; If so, determine the weight as the weight of the i-th substation in the j-th iteration; If not, the weight is corrected to the boundary of the set interval as the weight of the i-th substation in the j-th iteration; When the weighted Voronoi diagram algorithm is used to calculate the weight, the method further includes: The initial weight calculation formula is periodically used to disturb the weight change.

2. The substation planning method considering hierarchical allocation as claimed in claim 1, characterized in that: The determining of the capacity combination of the new substation and the initial site of the new substation includes: Calculate the range of the number of new substations required in the target year based on the total load in the target year, the capacity and number of existing substations in the current year, and the candidate capacity types of substations; Based on the number of new substations required in the target year and the candidate capacity types of the substations, a model is established with the goal of minimizing the annual investment cost of new substations and the substation capacity-load ratio requirement as a constraint condition to determine the capacity combination of new substations; For each new substation capacity combination, the initial site of the new substation is determined by coordinate geometry method.

3. The substation planning method considering hierarchical allocation as claimed in claim 1, characterized in that: The calculation formula for the optimal power supply radius of the substation is as follows: Among them, R i is the optimal power supply radius of the ith substation, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, π is the circumference of a circle, P ∑ It is the grid supply load of the power supply area in the target year.

4. The substation planning method considering hierarchical allocation according to any one of claims 1 to 3, characterized in that: After allocating the unallocated load to the nearest substation according to the conventional Voronoi diagram and completing the division of the power supply range, the method further includes: In the power supply range division results, a single-median location selection algorithm is used for each power supply area, with the minimum load distance as the goal, and the fminsearch function is used to solve the optimal median point as the location of the substation; When the load rate of the substation satisfies the N-1 principle and the change distance between the position of the substation in this iteration and the position of the previous iteration is 0, it is determined that the results of the substation address correction and power supply range division are converged.

5. A substation planning device considering hierarchical allocation, characterized in that: The device comprises: A determination module is used to determine the capacity combination of the new substation and the initial site of the new substation; A power supply radius calculation module, used to calculate the optimal power supply radius of each substation based on the total load density and the power supply capacity of each substation; A first allocation module is used to allocate to the corresponding substation in the allocation area corresponding to the load in each power supply area according to the principle of proximity allocation according to the conventional Voronoi diagram, and the power supply radius limit of the substation is a times the optimal power supply radius of the substation; A second allocation module is used to adjust the load distribution between the substations according to the weighted Voronoi diagram algorithm, and the power supply radius limit of each substation is the maximum power supply radius of the substation set in the specification; A third allocation module is used to allocate the unallocated load to the nearest substation according to the conventional Voronoi diagram to complete the division of power supply range; The planning scheme determination module is used to obtain the optimal new substation capacity, new substation location and corresponding power supply range division scheme with the goal of minimizing the total cost; The weight calculation formula in the weighted Voronoi diagram algorithm is as follows: When j=1, the initial weight is 1; When j=2, the weight calculation adopts the initial weight calculation formula: When j≥3, the weight calculation formula is: Among them, j is the number of iterations, rlbl i (j) is the capacity ratio of the i-th substation after the j-th iteration, P i (j,3) is the active power sum of the load carried by the ith substation after the third allocation in the jth iteration, S i is the capacity of the ith substation, is the power factor, e i is the maximum allowable load rate of the ith substation, △w i (j) is the weight change of the ith substation in the jth iteration, w i (j) is the weight of the ith substation in the jth iteration; The device also includes: A weight adjustment module, used for correcting the weight to the boundary of the set interval as the weight of the i-th substation in the j-th iteration when the calculated weight of the i-th substation in the j-th iteration is not within the set interval; The disturbance module is used to periodically disturb the weight change using the initial weight calculation formula.

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