A load-balanced coordinated elastic power restoration method for main and distribution systems

Abstract

The present invention discloses a main-distribution coordinated elastic power restoration method that takes load balancing into consideration, including: generating a number of power-off islands due to equipment failure, topologically searching all the spare original power supply paths of each power-off island to obtain a simplified power supply path set of each power-off island; synthesizing the initial transformer margin and initial feeder margin of the power supply paths corresponding to both ends of each power-off island to obtain the initial power supply path margin; sorting all power supply paths according to the current power supply path margin, distributing power to the corresponding power-off islands through each power supply path, determining the preliminary position of the split switches of each power-off island, and obtaining a preliminary power supply distribution plan; adjusting the split switch positions of each power-off island according to the current main grid transformer margin and feeder margin of the power supply paths corresponding to both ends of each power-off island to obtain a final power supply distribution plan with balanced transformer load. The present invention achieves the goal of restoring power to the power-off island to the greatest extent while improving the load balancing degree of the transformers involved in the power restoration.

Description

Technical Field

[0001] The present invention relates to the field of electric power automation technology, and in particular to a main-distribution coordinated elastic power restoration method taking load balancing into consideration. Background Art

[0002] When a partial line failure occurs in the distribution network, the main distribution network must coordinate to reverse power supply to the distribution line load. Because the coordinated load transfer problem in the main distribution network involves multiple power islands, multiple power sources, and the possibility that different power islands share the same power source, any single-step operation in the power transfer process between different power islands will affect each other. Currently, load transfer is mainly achieved through the branch boundary method. This method inputs all the conditional parameters after a specific power transfer into a predefined solution model to obtain a transfer solution. This method has a complex model, a large amount of calculation, and cannot fully guarantee the load balance of the transformer during reverse power supply. Summary of the Invention

[0003] The present invention proposes a main-distribution coordinated elastic power restoration method that takes load balancing into consideration, the purpose of which is to maximize power restoration of the power outage island while improving the load balancing of the transformers involved in the power restoration.

[0004] The technical solutions of the present invention are as follows:

[0005] A method for elastic power restoration with coordinated power supply between the main and distribution nodes taking into account load balancing includes the following steps:

[0006] S1: A device failure generates several power-off islands. A topological search is performed on all the backup original power supply paths for each power-off island to obtain a set of simplified power supply paths for each power-off island.

[0007] S2: The initial transformer margin P of the power supply path corresponding to each power loss island at both ends Li and initial feeder margin P Sj Get the initial power supply path margin P Tj ;

[0008] S3: All power supply paths are adjusted according to the current power supply path margin P Tj ' Sort by, distribute power to the corresponding power-off islands through each power supply path, determine the preliminary position of the split switches of each power-off island, and obtain a preliminary power supply distribution plan;

[0009] S4: Based on the current main grid transformer margin P of the power supply path corresponding to each power loss island Li ′ and the current feeder margin P Sj ′, adjust the position of the split switches of each power-off island to obtain the final power supply distribution plan with balanced transformer load.

[0010] Furthermore, the step S3 specifically includes:

[0011] S31: Select the current power supply path margin P Tj The largest power supply path distributes power to the corresponding power-off island, closes the tie switch, and determines the operating switch that needs to be disconnected on this power supply path;

[0012] S32: Recalculate the current power supply path margin P of all power supply paths Tj ';

[0013] S33: Determine whether there is a power supply path that has not yet been allocated to the power-lost island. If yes, remove the power supply path that has been allocated to the power-lost island and re-allocate the other power supply paths according to the current power supply path margin P. Tj ' Sort from large to small and return to step S31, otherwise use the operating switch that needs to be disconnected on each current power supply path as the initial position of the branch switch of the corresponding power-off island and go to step S4.

[0014] Furthermore, the step S31 of determining the operating switch that needs to be disconnected on the power supply path specifically includes:

[0015] a. If the current power supply path margin P of this power supply path Tj ′ is less than the current power supply load value D of the corresponding power-off island m , then start from the main grid transformer side of this power supply path and move forward along the simplified power supply path to determine the maximum load D that can be distributed by this power supply path. r Front-end power-off load D r+1 Is it an equivalent superimposed load for simplifying the power supply path? Otherwise, disconnect D r+1 The operation switch at the rear end is disconnected. r+1 The front operation switch and the r+1 The operating switch at the rear end starts to move forward along the original power supply path, disconnecting the maximum original power supply path load D that can be distributed by this power supply path. r ′The front-end operation switch realizes the maximum power supply of the power supply path to the corresponding power-off island, and recalculates D m ;

[0016] b. If the current power supply path margin P of this power supply path Tj ′ is greater than or equal to the current power supply load value D of the corresponding power-off island m , then determine whether there are other power supply paths to distribute power to the corresponding power loss island. If there are no other power supply paths to distribute power to the corresponding power loss island, then start from the main grid transformer side of this power supply path and move forward along the simplified power supply path to disconnect the power loss load D at the front end of the corresponding power loss island. f The operating switch at the rear end reserves the power-off load D at the front end. f Power distribution is performed by the opposite power supply path, and D is recalculated. m;

[0017] If there are other power supply paths to distribute power to the corresponding power-lost island, this power supply path will distribute power to all the current loads that need to be powered on the corresponding power-lost island without turning off the operating switch on this power supply path. m Set to zero.

[0018] Furthermore, the step S4 specifically includes:

[0019] S41: Calculate the current margin load rate α of all transformers involved in power distribution i and the overall load balance β;

[0020] S42: Current margin load rate α of the transformer corresponding to the power supply path at both ends of the power failure island i The difference α d Sort all power-off islands and select the difference α d The largest power-off island, go to the next step;

[0021] S43: Determine whether the position of the split switch of the currently selected power-off island is movable, if yes, jump to step S45, otherwise jump to step S44;

[0022] S44: Continue to determine whether the position of the next power-off island can be moved. If so, go to step S45. Otherwise, repeat this step until the last power-off island is determined, then go to step S46.

[0023] S45: Recalculate the position of the split switch by D l Move one side to D l The current margin load rate of each transformer after the other side α i and the total load balancing degree β, where D l The power-off load is the power-off load adjacent to the current split switch position on the power supply path with the smaller transformer margin in the power supply path corresponding to the two ends of the power-off island;

[0024] If the calculated value of the total load balance degree β after the movement is less than the calculated value before the movement, the position after the movement is used as the new position of the split switch, and then the process returns to step S42. If the calculated value of the total load balance degree β after the movement is not less than the calculated value before the movement, the split switch position of the power-off island is not moved, and the process returns to step S44.

[0025] S46: Record the positions of the current split switches of all power-off islands and determine the final power distribution plan.

[0026] Furthermore, the method for determining whether the position of the position switch is movable in step S43 and step S44 is:

[0027] If there is more than one split switch on the simplified power supply path corresponding to the two ends of the power-off island, it is determined that the split switch position cannot be moved;

[0028] If there is only one splitter switch on the simplified power supply path corresponding to the two ends of the power-off island, the judgment is made as follows:

[0029] If P Ld ≥D l , then it is determined that the position of the split switch can be moved;

[0030] If P Ld <D l , then judge D l Whether it is an equivalent superimposed load of the simplified power supply path, if so, the position of the split switch is determined to be movable, otherwise, the position of the split switch is determined to be immovable;

[0031] Among them, P Ld It is the difference between the current transformer margins of the corresponding power supply paths at both ends of the power failure island.

[0032] Furthermore, when determining whether the position of the split switch is movable in step S43 and step S44, the current feeder margin P of the power supply path corresponding to the two ends of the power-off island after the split switch position is moved must be satisfied. Sj ′≥0 constraint.

[0033] Furthermore, when all power-off islands are sorted in step S42, if there are two or more power-off islands, d The calculated value of α is the same as d The power-loss islands with the same calculated value are sorted from large to small according to the current feeder margin difference of the corresponding power supply paths at both ends.

[0034] Furthermore, in step S44, if all the position switches in the current order are immovable, the final power supply distribution plan is directly obtained.

[0035] Furthermore, the current margin load rate α of each transformer is i The calculation method of the overall load balancing degree β is:

[0036]

[0037]

[0038] Where n is the number of transformers involved in power distribution, For all α i The mean of .

[0039] Furthermore, the initial power supply path margin P in step S2 Tj The calculation method is:

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) This method first uses a greedy algorithm to reverse power to as many power-off loads as possible while ensuring that the transformer and feeder are not overloaded, and determines the initial position of the split switches of each power-off island. Then, the position of the split switches is moved under the constraint of load balancing, thereby restoring power to the power-off equipment to the greatest extent possible while ensuring the load balance of the transformer.

[0042] (2) When a certain power supply path cannot fully supply power to the equivalent superimposed load of the simplified power supply path, the operating switch at the front end of the equivalent superimposed load is disconnected to determine the preliminary position of the first-level split switch, and the preliminary position of the next-level split switch is further determined through the original power supply path, thereby achieving the maximum restoration of power supply to the corresponding power-lost island by this power supply path;

[0043] (3) This method does not need to traverse the opening and closing states of all switches, and has high computational efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flow chart of the present invention;

[0045] Figure 2 This is a schematic diagram of the original power supply path of the second embodiment of the present invention;

[0046] Figure 3 This is a simplified power supply path diagram of the second embodiment of the present invention. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is described in detail below with reference to the accompanying drawings:

[0048] Example 1:

[0049] like Figure 1 A method for elastic power restoration with coordinated power distribution and load balancing, comprising the following steps:

[0050] S1: A device failure generates several power-off islands. A topological search is performed on all the backup original power supply paths for each power-off island to obtain a set of simplified power supply paths for each power-off island.

[0051] S2: The initial transformer margin P of the main grid corresponding to the power supply path at both ends of each power loss island Li and initial feeder margin P Sj Get the initial power supply path margin P Tj , P Tj =min{P Li ,P Sj}.

[0052] S3: All power supply paths are adjusted according to the current power supply path margin P Tj ' sorting, and distribute power to the corresponding power-lost islands through each power supply path, determine the preliminary position of the split switches of each power-lost island, and obtain the preliminary power supply distribution plan. Tj The initial value of ′ is P Tj Each time the power supply path is allocated to the corresponding power-off island, the P of all power supply paths needs to be recalculated. Tj ′’s value.

[0053] The specific steps include:

[0054] S31: Select the current power supply path margin P Tj The largest power supply path distributes power to the corresponding power-off island, closes the tie switch, and determines the operating switch that needs to be disconnected on this power supply path.

[0055] The following are the solutions for different situations:

[0056] a. If the current power supply path margin P of this power supply path Tj ′ is less than the current power supply load value D of the corresponding power-off island m , then start from the main grid transformer side of this power supply path and move forward along the simplified power supply path to determine the maximum load D that can be distributed by this power supply path. r Front-end power-off load D r+1 Is it an equivalent superimposed load for simplifying the power supply path? Otherwise, disconnect D r+1 The operation switch at the rear end is disconnected. r+1 The front operation switch and the r+1 The operating switch at the rear end starts to move forward along the original power supply path, disconnecting the maximum original power supply path load D that can be distributed by this power supply path. r ′The front-end operation switch realizes the maximum power supply of the power supply path to the corresponding power-off island, and recalculates D m ;

[0057] b. If the current power supply path margin P of this power supply path Tj ′ is greater than or equal to the current power supply load value D of the corresponding power-off island m , then determine whether there are other power supply paths to distribute power to the corresponding power loss island. If there are no other power supply paths to distribute power to the corresponding power loss island, then start from the main grid transformer side of this power supply path and move forward along the simplified power supply path to disconnect the power loss load D at the front end of the corresponding power loss island. f The operating switch at the rear end reserves the power-off load D at the front end. f Power distribution is performed by the opposite power supply path, and D is recalculated. m ;

[0058] If there are other power supply paths to distribute power to the corresponding power-lost island, this power supply path will distribute power to all the current loads that need to be powered on the corresponding power-lost island without turning off the operating switch on this power supply path. m Set to zero.

[0059] S32: Recalculate the current power supply path margin P of all power supply paths Tj ′.

[0060] S33: Determine whether there is a power supply path that has not yet been allocated to the power-lost island. If yes, remove the power supply path that has been allocated to the power-lost island and re-allocate the other power supply paths according to the current power supply path margin P. Tj ' Sort from large to small and return to step S31, otherwise use the operating switch that needs to be disconnected on each current power supply path as the initial position of the branch switch of the corresponding power-off island and go to step S4.

[0061] S4: Based on the current main grid transformer margin P of the power supply path corresponding to each power loss island Li ′ and the current feeder margin P Sj ′, adjust the position of the split switches of each power-off island to obtain the final power supply distribution plan with balanced transformer load.

[0062] The specific steps include:

[0063] S41: Calculate the current margin load rate α of all transformers involved in power distribution i And the overall load balancing degree β, calculated as:

[0064]

[0065]

[0066] Where n is the number of transformers involved in power distribution, For all α i The mean of .

[0067] S42: Current margin load rate α of the transformer corresponding to the power supply path at both ends of the power failure island i The difference α d Sort all power-off islands and select the difference α d The largest power loss island, go to the next step.

[0068] Preferably, when sorting all power-off islands, if there are two or more power-off islands, d The calculated value of α is the same as d The power-loss islands with the same calculated value are sorted from large to small according to the current feeder margin difference of the corresponding power supply paths at both ends.

[0069] S43: Determine whether the position of the split switch of the currently selected power-off island is movable. The determination method is as follows:

[0070] If there is more than one split switch on the simplified power supply path corresponding to the two ends of the power-off island, it is determined that the split switch position cannot be moved;

[0071] If there is only one splitter switch on the simplified power supply path corresponding to the two ends of the power-off island, the judgment is made as follows:

[0072] If P Ld ≥D l , then it is determined that the position of the split switch can be moved;

[0073] If P Ld <D l , then judge D l Is it an equivalent superimposed load of the simplified power supply path? If so, it is determined that the position of the split switch is movable; otherwise, it is determined that the position of the split switch is immovable.

[0074] Among them, P Ld D is the difference in the current transformer margin of the power supply path at both ends of the power failure island. l It is the power-off load adjacent to the current split switch position on the power supply path with the smaller transformer margin in the power supply path corresponding to the two ends of the power-off island.

[0075] Furthermore, when adjusting the position of the split switches of each power-off island, the current feeder margin P of the power supply path corresponding to the two ends of the power-off island after the split switch position is moved must be met. Sj ′≥0 constraint.

[0076] If the position of the split switch is movable, the process goes to step S45 ; if the position of the split switch is immovable, the process goes to step S44 .

[0077] S44: Continue to determine whether the position of the next power-off island in the next order is movable. If so, proceed to step S45. Otherwise, repeat this step until the last power-off island in the order is determined, then proceed to step S46. If all the position of the power-off islands in the current order are not movable, the final power distribution plan is directly obtained.

[0078] S45: Recalculate the position of the split switch by D l Move one side to D l The current margin load rate of each transformer after the other side α iand the total load balance degree β. If the calculated value of the total load balance degree β after moving is less than the calculated value before moving, the position after moving is used as the new position of the split switch, and then returns to step S42; if the calculated value of the total load balance degree β after moving is not less than the calculated value before moving, the split switch position of the power-off island is not moved, and returns to step S44.

[0079] S46: Record the positions of the current split switches of all power-off islands and determine the final power distribution plan.

[0080] Example 2:

[0081] This embodiment is used to illustrate that when busbar L1 fails, the power failure island can fully restore power supply through all backup power supply paths. Figure 2 In the figure, L represents the bus, S represents the switch (dark represents closed, white represents open), and D represents the load (the load value of D12 is 40A, and the other load values ​​are 20A).

[0082] Assume that the feeder margin and transformer margin of each power supply path are as shown in Table 1.

[0083] Table 1 Feeder margin and transformer margin of each power supply path

[0084] equipment Margin S15 represents the feeder and S20 represents the feeder 60 S17 represents the feeder and S19 represents the feeder 80 S16 represents the feeder 100 The transformer where L2 is located and the transformer where L4 is located 120 S18 represents the feeder 120 L3 where the transformer 220

[0085] When busbar L1 fails, power is returned to the three power-lost islands B1, B2, and B3 through busbars L2, L3, and L4.

[0086] S1: Simplify the original power supply path, such as Figure 3 , where D231 represents the sum of the four loads D1, D4, D21, and D7, and D341 represents the sum of the three loads D2, D5, and D8.

[0087] S2: The initial power supply path margin is obtained by integrating the initial main grid transformer margin and initial feeder margin of the power supply path corresponding to both ends of each power loss island, as shown in Table 2.

[0088] Table 2 Initial power supply path margin of each power supply path

[0089] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:100 L2:120 T2 S17:80 L3:220 T3 S19:80 L4:120 T4 S18:120 L3:220 T5 S15:80 L4:120 T6 S20:60 L3:220

[0090] S3: Sort all power supply paths by their current power supply path margins, distribute power to the corresponding power-off islands through each power supply path, determine the preliminary position of the split switches of each power-off island, and obtain a preliminary power supply distribution plan, as follows:

[0091] Repeat step 1:

[0092] The current power supply path with the largest margin is path T4, and path T4 cannot fully power the power-off island B2. S21 needs to be disconnected, so the first step is to close S18 and disconnect S21.

[0093] Recalculate the current power supply path margin of each power supply path, as shown in Table 3.

[0094] Table 3 Current power supply path margin of each power supply path

[0095] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:100 L2:120 T2 S17:80 L3:100 T3 S19:80 L4:120 T4 S18:0 L3:100 T5 S15:60 L4:120 T6 S20:60 L3:100

[0096] Repeat operation 2:

[0097] The current power supply path with the largest margin is path T1. Path T1 cannot fully power the power-off island B1, so switch S12 needs to be opened. Therefore, the second step is to close S16 and open S12.

[0098] Recalculate the current power supply path margin of each power supply path, as shown in Table 4.

[0099] Table 4 Current power supply path margin of each power supply path

[0100] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:0 L2:20 T2 S17:80 L3:100 T3 S19:80 L4:120 T4 S18:0 L3:100 T5 S15:60 L4:120 T6 S20:60 L3:100

[0101] Repeat step 3:

[0102] The current power supply path with the largest margin is path T3, which only needs to provide 20A and does not need to disconnect the switch.

[0103] The next current power supply path with the largest margin is path T2, which only needs to provide 20A and does not need to disconnect the switch.

[0104] Recalculate the current power supply path margin of each power supply path, as shown in Table 5.

[0105] Table 5 Current power supply path margin of each power supply path

[0106] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:0 L2:20 T2 S17:60 L3:80 T3 S19:60 L4:100 T4 S18:0 L3:80 T5 S15:60 L4:100 T6 S20:60 L3:80

[0107] Repeat step 4:

[0108] The current power supply path with the largest margin is path T5, where 60A cannot supply power to the current load of 80A required by the B3 power-off island, and S22 needs to be disconnected.

[0109] Recalculate the current power supply path margin of each power supply path, as shown in Table 6.

[0110] Table 6 Current power supply path margin of each power supply path

[0111] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:0 L2:20 T2 S17:60 L3:80 T3 S19:60 L4:40 T4 S18:0 L3:80 T5 S15:0 L4:40 T6 S20:60 L3:80

[0112] Repeat step 5:

[0113] Power is distributed to the path T6 and S20 is closed.

[0114] Recalculate the current power supply path margin of each power supply path, as shown in Table 7.

[0115] Table 7 Current power supply path margin of each power supply path

[0116] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:0 L2:20 T2 S17:60 L3:60 T3 S19:60 L4:40 T4 S18:0 L3:60 T5 S15:0 L4:40 T6 S20:40 L3:60

[0117] At this point, all power supply paths have been allocated, the closed switches are {S15, S16, S17, S18, S19, S20}, and the open switches are {S12, S21, S22}.

[0118] S4: According to the current transformer margin and feeder margin of the main grid corresponding to the power supply path at both ends of each power loss island, the position of the splitter switch of each power loss island is adjusted to obtain the final power supply distribution plan with balanced transformer load, as follows:

[0119] Calculate the current margin load rate α of all transformers involved in power distribution i :

[0120] The transformer where L2 is located is 100:120=5:6

[0121] The transformer where L3 is located is 60:120=1:2

[0122] The transformer where L4 is located is 180:220=9:11

[0123] The overall load balancing degree β is calculated to be approximately 0.0236.

[0124] The transformer margin load ratios of the power supply paths at both ends of S12 are 5:6 and 9:11 respectively

[0125] The transformer margin load ratios of the power supply paths at both ends of S21 are 1:2 and 9:11 respectively

[0126] The transformer margin load ratios of the power supply paths at both ends of S22 are 1:2 and 9:11 respectively

[0127] The transformer margin load rate difference between the power supply paths at both ends of S21 and S22 is the largest, so the current on the right side needs to be transferred to the left side. Further comparison of the difference in feeder margin between the two: 60-0 and 20-20 shows that the feeder margin difference between the power supply paths at both ends of S21 is greater. The original disconnection of S21 is changed to disconnection of S14.

[0128] At this time, the current margin load rate of all transformers participating in power distribution is α i for:

[0129] The transformer where L2 is located is 100:120=5:6

[0130] The transformer where L3 is located is 80:120=2:3

[0131] The transformer where L4 is located is 160:220=8:11

[0132] The overall load balancing degree β is calculated to be approximately 0.00474.

[0133] The calculated value of the overall load balance degree β after the movement is smaller than the calculated value before the movement, and the value of β cannot be further reduced by adjusting the position of the split switches. The current operating state is the final allocation scheme. The final operation is that the closed switches are {S15, S16, S17, S18, S19, S20}, and the open switches are {S12, S14, S22}.

[0134] The feeder margin and transformer margin of each power supply path are shown in Table 8.

[0135] Table 8 Final feeder margin and transformer margin for each power supply path

[0136] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:0 L2:20 T2 S17:60 L3:60 T3 S19:40 L4:40 T4 S18:20 L3:60 T5 S15:20 L4:60 T6 S20:20 L3:60

[0137] Example 3:

[0138] This embodiment is used to illustrate the situation where when busbar L1 fails, the power failure island cannot fully restore power through all backup power supply paths. Figure 2 As shown in the figure, L represents bus, S represents switch (dark represents closed, white represents open), and D represents load (the load value of D1, D4, and D21 is 20A, and the load value of the remaining loads is 30A).

[0139] Assume that the feeder margin and transformer margin of each power supply path are as shown in Table 9.

[0140] Table 9 Feeder margin and transformer margin of each power supply path

[0141] equipment Margin S20 represents the feeder 60 S15 represents the feeder and S19 represents the feeder 80 S16 represents the feeder and S17 represents the feeder 100 L2 where the transformer 110 L4 where the transformer 150 S18 represents the feeder 150 L3 where the transformer 270

[0142] When busbar L1 fails, power is returned to the three power-lost islands B1, B2, and B3 through busbars L2, L3, and L4.

[0143] S1: Simplify the original power supply path, such as Figure 3 , where D231 represents the sum of the four loads D1, D4, D21, and D7, and D341 represents the sum of the three loads D2, D5, and D8.

[0144] S2: The initial power supply path margin is obtained by integrating the initial main grid transformer margin and feeder margin of the power supply path corresponding to both ends of each power loss island, as shown in Table 10.

[0145] Table 10 Initial power supply path margin for each power supply path

[0146] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:100 L2:110 T2 S17:100 L3:270 T3 S19:80 L4:150 T4 S18:150 L3:270 T5 S15:90 L4:150 T6 S20:60 L3:270

[0147] S3: Sort all power supply paths by their current power supply path margins, distribute power to the corresponding power-off islands through each power supply path, determine the preliminary position of the split switches of each power-off island, and obtain a preliminary power supply distribution plan, as follows:

[0148] Repeat step 1:

[0149] The current power supply path with the largest margin is path T4, and path T4 cannot fully power the power-off island B2. S21 needs to be disconnected, so the first step is to close S18 and disconnect S21.

[0150] Recalculate the current power supply path margin of each power supply path, as shown in Table 11.

[0151] Table 11 Current power supply path margin of each power supply path

[0152] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:100 L2:110 T2 S17:100 L3:120 T3 S19:80 L4:150 T4 S18:0 L3:120 T5 S15:90 L4:150 T6 S20:60 L3:120

[0153] Repeat operation 2:

[0154] The current power supply path with the largest margin is path T2. Path T2 cannot fully restore power to the power-off island B1, and cannot fully reverse power to the equivalent superimposed load D231 during power distribution. Therefore, the second step is to close S17, open S11, and open S5.

[0155] Recalculate the current power supply path margin of each power supply path, as shown in Table 12.

[0156] Table 12 Current power supply path margin of each power supply path

[0157] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:100 L2:110 T2 S17:0 L3:20 T3 S19:80 L4:150 T4 S18:0 L3:20 T5 S15:90 L4:150 T6 S20:60 L3:20

[0158] Repeat step 3:

[0159] The six power supply paths are:

[0160] The current power supply path with the largest margin is path T1, which only needs to provide 30A and does not need to disconnect the switch.

[0161] The next current power supply path with the largest margin is path T3, which only needs to provide 30A and does not need to disconnect the switch.

[0162] The next current power supply path with the largest margin is path T5, which can only provide 90A and requires disconnecting switch S22.

[0163] Recalculate the current power supply path margin of each power supply path, as shown in Table 13.

[0164] Table 13 Current power supply path margin of each power supply path

[0165] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:70 L2:80 T2 S17:0 L3:20 T3 S19:50 L4:30 T4 S18:0 L3:20 T5 S15:0 L4:30 T6 S20:60 L3:20

[0166] Repeat step 4:

[0167] Path T6 has not yet been allocated power, and its current power supply path margin is 20A, which is unable to supply power to the power-off island B3.

[0168] At this point, all power supply paths have been allocated, the closed switches are {S15, S16, S17, S18, S19}, and the open switches are {S11, S5, S21, S22}.

[0169] S4: According to the current transformer margin and feeder margin of the main grid corresponding to the power supply path at both ends of each power loss island, the position of the splitter switch of each power loss island is adjusted to obtain the final power supply distribution plan with balanced transformer load, as follows:

[0170] Calculate the current margin load rate α of all transformers involved in power distribution i :

[0171] The transformer where L2 is located is 30:110=3:11

[0172] The transformer where L3 is located is 250:270=25:27

[0173] The transformer where L4 is located is 120:150=4:5

[0174] Calculate the overall load balancing degree β, which is approximately 0.08.

[0175] The transformer margin load ratios of the power supply paths at both ends of S12 are 3:11 and 25:27 respectively

[0176] The transformer margin load ratios of the power supply paths at both ends of S21 are 4:5 and 25:27 respectively

[0177] The transformer margin load ratios of the power supply paths at both ends of S22 are 4:5 and 25:27 respectively

[0178] The transformer margin load rates of the power supply paths at both ends of S12 have the largest difference, so it is necessary to transfer the current on the right to the left for power supply, and modify the disconnection of S11 to disconnection of S12.

[0179] At this time, the current margin load rate of all transformers participating in power distribution is αi for:

[0180] The transformer where L2 is located is 100:120=5:6

[0181] The transformer where L3 is located is 180:270=2:3

[0182] The transformer where L4 is located is 120:150=4:5

[0183] The overall load balance degree β is calculated to be approximately 0.00518.

[0184] The calculated value of the overall load balance degree β after the movement is smaller than the calculated value before the movement, and the value of β cannot be further reduced by adjusting the position of the split switches. The current state is the final allocation plan. The final operation is that the closed switches are {S15, S16, S17, S18, S19, S20}, and the open switches are {S12, S4, S21, S22}.

[0185] The feeder margin and transformer margin of each power supply path are shown in Table 14.

[0186] Table 14 Final feeder margin and transformer margin for each power supply path

[0187] path Feeder margin Transformer margin path Feeder margin Transformer margin T1 S16:0 L2:10 T2 S17:70 L3:90 T3 S19:50 L4:30 T4 S18:0 L3:90 T5 S15:0 L4:30 T6 S20:60 L3:90

Claims

1. A method for elastic power restoration with coordinated power distribution and load balancing, characterized in that: The steps include: S1: A device failure generates several power-off islands. A topological search is performed on all the backup original power supply paths for each power-off island to obtain a set of simplified power supply paths for each power-off island. S2: The initial transformer margin P of the power supply path corresponding to each power loss island at both ends Li and initial feeder margin P Sj Get the initial power supply path margin P Tj ; S3: All power supply paths are adjusted according to the current power supply path margin P Tj ' Sort by, distribute power to the corresponding power-off islands through each power supply path, determine the preliminary position of the split switches of each power-off island, and obtain a preliminary power supply distribution plan; S4: Based on the current main grid transformer margin P of the power supply path corresponding to each power loss island Li ′ and the current feeder margin P Sj ', adjust the position of the split switches of each power-off island to obtain the final power distribution plan with balanced transformer load; The step S4 specifically includes: S41: Calculate the current margin load rate α of all transformers involved in power distribution i and the overall load balance β; S42: Current margin load rate α of the transformer corresponding to the power supply path at both ends of the power failure island i The difference α d Sort all power-off islands and select the difference α d The largest power-off island, go to the next step; S43: Determine whether the position of the split switch of the currently selected power-off island is movable, if yes, jump to step S45, otherwise jump to step S44; S44: Continue to determine whether the position of the next power-off island can be moved. If so, go to step S45. Otherwise, repeat this step until the last power-off island is determined, then go to step S46. S45: Recalculate the position of the split switch by D l Move one side to D l The current margin load rate of each transformer after the other side α i and the total load balancing degree β, where D l The power-off load is the power-off load adjacent to the current split switch position on the power supply path with the smaller transformer margin in the power supply path corresponding to the two ends of the power-off island; If the calculated value of the total load balance degree β after the movement is less than the calculated value before the movement, the position after the movement is used as the new position of the split switch, and then the process returns to step S42. If the calculated value of the total load balance degree β after the movement is not less than the calculated value before the movement, the split switch position of the power-off island is not moved, and the process returns to step S44. S46: Record the positions of the current split switches of all power-off islands and determine the final power distribution plan.

2. The load-balanced coordinated elastic power restoration method for main and distribution nodes according to claim 1 is characterized in that: The step S3 specifically includes: S31: Select the current power supply path margin P Tj The largest power supply path distributes power to the corresponding power-off island, closes the tie switch, and determines the operating switch that needs to be disconnected on this power supply path; S32: Recalculate the current power supply path margin P of all power supply paths Tj '; S33: Determine whether there is a power supply path that has not yet been allocated to the power-lost island. If yes, remove the power supply path that has been allocated to the power-lost island and re-allocate the other power supply paths according to the current power supply path margin P. Tj ' Sort from large to small and return to step S31, otherwise use the operating switch that needs to be disconnected on each current power supply path as the initial position of the branch switch of the corresponding power-off island and go to step S4.

3. The load-balanced coordinated elastic power restoration method for main and distribution nodes according to claim 2 is characterized by: Determining the operating switch that needs to be disconnected on the power supply path in step S31 specifically includes: a. If the current power supply path margin P of this power supply path Tj ′ is less than the current power supply load value D of the corresponding power-off island m , then start from the main grid transformer side of this power supply path and move forward along the simplified power supply path to determine the maximum load D that can be distributed by this power supply path. r Front-end power-off load D r+1 Is it an equivalent superimposed load for simplifying the power supply path? Otherwise, disconnect D r+1 The operation switch at the rear end is disconnected. r+1 The front operation switch and the r+1 The operating switch at the rear end starts to move forward along the original power supply path, disconnecting the maximum original power supply path load D that can be distributed by this power supply path. r ′The front-end operation switch realizes the maximum power supply of the power supply path to the corresponding power-off island, and recalculates D m ; b. If the current power supply path margin P of this power supply path Tj ′ is greater than or equal to the current power supply load value D of the corresponding power-off island m , then determine whether there are other power supply paths to distribute power to the corresponding power loss island. If there are no other power supply paths to distribute power to the corresponding power loss island, then start from the main grid transformer side of this power supply path and move forward along the simplified power supply path to disconnect the power loss load D at the front end of the corresponding power loss island. f The operating switch at the rear end reserves the power-off load D at the front end. f The power supply is distributed by the opposite power supply path, and D is recalculated. m ; If there are other power supply paths to distribute power to the corresponding power-lost island, this power supply path will distribute power to all the current loads that need to be powered on the corresponding power-lost island without turning off the operating switch on this power supply path. m Set to zero.

4. The load-balanced coordinated elastic power restoration method for main and distribution nodes according to claim 1 is characterized in that: The method for determining whether the position of the position switch is movable in step S43 and step S44 is as follows: If there is more than one split switch on the simplified power supply path corresponding to the two ends of the power-off island, it is determined that the split switch position cannot be moved; If there is only one split switch on the simplified power supply path corresponding to the two ends of the power-off island, the judgment is made as follows: Ld ≥D l , then it is determined that the position of the split switch can be moved; If P Ld <D l , then judge D l Whether it is an equivalent superimposed load of the simplified power supply path, if so, the position of the split switch is determined to be movable, otherwise, the position of the split switch is determined to be immovable; Among them, P Ld It is the difference between the current transformer margins of the corresponding power supply paths at both ends of the power failure island.

5. The load-balanced coordinated elastic power restoration method for main and distribution nodes according to claim 4 is characterized in that: When determining whether the position of the split switch is movable in step S43 and step S44, it is also necessary to meet the current feeder margin P of the power supply path corresponding to the two ends of the power-off island after the split switch position is moved. Sj ′≥0 constraint.

6. The load-balanced coordinated elastic power restoration method of main and distribution equipment according to claim 1, characterized in that: When all power-off islands are sorted in step S42, if there are two or more power-off islands, d If the calculated value of is the same, then α d The power-loss islands with the same calculated value are sorted from large to small according to the current feeder margin difference of the corresponding power supply paths at both ends.

7. The load-balanced coordinated elastic power restoration method of main and distribution equipment according to claim 1 is characterized in that: In step S44, if all the position switches in the current order are immovable, the final power supply distribution plan is directly obtained.

8. The load-balanced coordinated elastic power restoration method of main and distribution equipment according to claim 1 is characterized in that: The current margin load rate α of each transformer i The calculation method of the overall load balancing degree β is: Where n is the number of transformers involved in power distribution, For all α i The mean of .

9. The method for elastic power restoration with coordinated power distribution and load balancing according to any one of claims 1 to 8, characterized in that: The initial power supply path margin P in step S2 Tj The calculation method is: P Tj =min{P Li ,P Sj }.

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