A method for improving power supply recovery capability of distribution network

Abstract

The present invention discloses a method for improving the power supply recovery capability of a distribution network, comprising the following steps: step (1): grouping the branch lines of the distribution network according to the topological structure and the direction of the power flow of the distribution network; step (2): proposing a branch fault recovery optimization strategy under a line fault scenario based on the branch grouping result; step (3): performing a safety check on the reconnected line, and grouping the branches again after the check passes, and providing new group data to the recovery program. The present invention improves the fault scenario calculation speed by grouping the branches of the distribution network topology structure and reducing the number of fault scenarios to be simulated in the distribution network fault recovery framework, thereby ultimately improving the power supply recovery capability of the distribution network, thereby providing a guarantee for the safe and stable operation of the distribution network.

Description

Technical field

[0001] The present invention belongs to the technical field of power system distribution, and in particular relates to a method for improving the power supply recovery capability of a distribution network. [Background Technology]

[0002] Currently, radial distribution designs are one of the most commonly used power grid types. A single branch failure in the network can potentially disconnect downstream sections of the system. Power restoration in distribution networks can be achieved by remotely controlling interconnected switches within the grid or segmented switches on branches, thereby changing the network topology and redistributing the power mix. Power restoration in distribution networks is fundamental to their safe and stable operation and a crucial foundation for other applications, such as network reliability, assessment, maintenance planning, and network planning. Therefore, when a fault occurs, the distribution network requires an efficient and rapid power restoration solution. [Summary of the invention]

[0003] In view of the deficiencies in the existing technology, the technical problem to be solved by the present invention is to provide a method for dividing the system topology structure using a branch grouping algorithm and reorganizing the grid structure according to the division results to improve the power supply recovery capability, so as to provide guarantee for the safe and stable operation of the distribution network.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for improving the power supply recovery capability of a distribution network comprises the following steps:

[0006] Step (1): According to the topology of the distribution network and the direction of the power flow, the distribution network branch lines are divided into groups;

[0007] Step (2): Based on the branch grouping results, propose a branch fault recovery optimization strategy under the line fault scenario;

[0008] Step (3): Perform a safety check on the reconnected line, and after passing the check, perform branch grouping again and provide new group data to the recovery program.

[0009] Preferably, the method of grouping the branches of the line in step (1) is: grouping the branch lines directly connected to the bus according to the bus type, the branch lines connected to the substation bus are grouped in the first feeder group, and the bus connected to the distributed power supply is grouped in the second feeder group; grouping the remaining branches, and using the second branch by default; performing grouping, if: 1) the "to bus" of the second branch has two or more branches connected, the grouping is terminated and there will be only one branch; 2) there is only one branch connected to the "to bus" of the branch under consideration, and then continuing the grouping.

[0010] Preferably, step (2) considers the recovery plan for each individual branch failure scenario after grouping, by finding a recovery plan whereby the "branch group members" are likely to take the same steps when recovery occurs.

[0011] Preferably, the safety verification method of step (3) is: the topology of the line system after the reconnection is changed, and after the system topology is changed, the line current I i ≤I max , line capacity S i ≤S max , bus voltage limit V i ≥V min , and line N-1 verification to maintain the radial structure of the system.

[0012] The technical solution adopted by the present invention takes the system topology and calculated network power flow as input, analyzes the system grid structure and the properties of each busbar node, and divides the distribution network grid into branch groups based on the structure and node characteristics of each branch according to the branch grouping algorithm. All branches within the same group have similar power supply restoration solutions. Based on this grouping result, a branch fault recovery optimization strategy is proposed for each group under the line fault scenario. Finally, the grouped grid topology is reorganized and safety verification is performed. Therefore, it has the following beneficial effects:

[0013] The present invention improves the fault scenario calculation speed by grouping the distribution network topology branches and reducing the number of fault scenarios to be simulated in the distribution network fault recovery framework, ultimately enhancing the power supply recovery capability of the distribution network to provide protection for the safe and stable operation of the distribution network.

[0014] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

Brief Description of the Drawings

[0015] The invention will be further described below with reference to the accompanying drawings:

[0016] Figure 1 This is a flow chart of a method for improving the power supply restoration capability of a distribution network based on a network topology branch grouping algorithm according to the present invention;

[0017] Figure 2 This is the topology diagram of the 33-node distribution network structure. [Specific implementation method]

[0018] The following is an explanation and description of the technical solutions of the embodiments of the present invention in conjunction with the drawings of the embodiments of the present invention. However, the following embodiments are only preferred embodiments of the present invention and are not exhaustive. Based on the embodiments in the implementation manner, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0019] When a fault occurs, the distribution network requires an efficient and rapid power restoration plan. To achieve the above objectives, the present invention provides a method for improving the power restoration capability of the distribution network. The method divides the distribution network topology based on a branch grouping algorithm and, based on the division results, formulates a power restoration plan for each group to improve the power restoration capability. The method comprises the following steps:

[0020] Step 1: According to the distribution network topology and power flow direction, the lines are divided into branches and groups;

[0021] Step (1): According to the topology of the distribution network and the direction of the power flow, the distribution network branch lines are divided into groups;

[0022] Step (2): Based on the branch grouping results, propose a branch fault recovery optimization strategy under the line fault scenario;

[0023] Step (3): Perform a safety check on the reconnected line, and after passing the check, perform branch grouping again and provide new group data to the recovery program.

[0024] Combine Figure 1 and Figure 2 As shown, step (1) mainly includes the following steps:

[0025] (1.1) Input bus and branch information, and extract bus, branch and tie line data from case files (configurable).

[0026] (1.2) According to the input bus type, the branches directly connected to the bus are grouped by feeder units. The branches connected to the main feeder unit (substation) bus are grouped in the first feeder group, and the bus connected to the DG is grouped in the second feeder group.

[0027] (1.3) Group the remaining branches. By default, the second branch is used because the first branch is most likely to be connected to the busbar with the feeder unit. Grouping is performed. If: (1) the "To Busbar" of the second branch has two or more branches connected, the grouping is terminated and there will be only one branch; (2) there is only one branch connected to the "To Busbar" of the branch under consideration, then the grouping continues. The final branch results are shown in Table 1:

[0028] Table 1

[0029] Group number Branch number 1 1 2 2 3 3，4，5 4 6，7 5 8 6 9，10，11 7 12，13，14 8 15，16，17 9 18，19，20 10 21 11 22，23，24 12 25，26，27，28 13 29，30，31，32

[0030] Based on the above steps, after completing the system network structure grouping, after executing the grouping, you can consider the recovery plan for each individual branch failure scenario. By finding a recovery plan, when recovery occurs, the "branch group members" may take the same steps. Step (2) specifically includes the following steps:

[0031] (2.1) Branch 1 Fault: If no DG is present, the only branch that cannot operate with the fault is branch 1. If there is only one feeder on bus 1 and branch 1 is isolated for protection, there is no solution. In other cases, there are solutions in almost all cases, with some groups facing difficulties in full or partial restoration.

[0032] (2.2) Branch 2-5 failure: If branch 25 fails, another method of detecting switching is required because it is impossible to restore the network downstream with a single switching operation.

[0033] (2.3) Branch 8 Fault: A single branch fault occurred on branch 8. When a single load transfer restored the load, 23 buses were within the voltage constraints. No power flowed on the other buses, so they are not included to better visualize the remaining buses.

[0034] (2.4) Fault on branch 22-23: In the case of these two branch faults, the minimum voltage is not within the constraints in some cases.

[0035] (2.5) Faults on branches 29-32: Tie lines should be avoided for this last group, as restoring bus voltages using line 36 would reduce the bus voltages of other groups, while including line 37 would create loops in the system. Without tie lines, for faults on branches 29, 30, 31, and 32, only buses 29, 30, 31, and 32 would be within the voltage constraints. In a standard system without distributed generation (DG), a fault on branch 1 cannot be restored because it carries all the power required by the system. Faults on branches 2-5 cannot be restored using a single tie line and should involve at least two or more switching operations. Faults on branches 8, 22, and 23 restore only 23 buses, while the remaining 10 are disconnected from the supply unit. At least two tie lines should be involved to restore more or all buses affected by the branch fault. Fault scenarios for branches 18, 29, 30, and 31 do not include partial bus restoration, as only one tie line is involved; the involvement of two tie lines should restore all buses to the outage.

[0036] (2.6) Fault of branch 30 with DG: When a 1MW DG is added to bus 34, there is a 38th branch connected to bus 32. With the participation of DG, group 13 in the table is divided, and the new groups are: Group 13: branches 29 and 31; Group 14: branch 32; Group 15: branch 38, connected bus 32 and bus 34.

[0037] After developing a group power restoration strategy, perform a system security check. Step 3 mainly includes the following steps:

[0038] (3.1) After the system topology is changed by performing switching operations, the line current I i ≤I max , line capacity S i ≤Sm ax , bus voltage limit V i ≥V min , and line N-1 verification to maintain the radial structure of the system;

[0039] (3.2) After verification, run the branch grouping algorithm again and provide new group data to the recovery program.

[0040] The above description is merely a specific embodiment of the invention, but the scope of protection of the invention is not limited thereto. Those skilled in the art will understand that the invention includes, but is not limited to, the drawings and the contents described in the above specific embodiments. Any modifications that do not deviate from the functional and structural principles of the invention are intended to be included within the scope of the claims.

Claims

1. A method for improving the power supply recovery capability of a distribution network, characterized in that: The steps include: Step (1): According to the topology of the distribution network and the direction of the power flow, the distribution network branch lines are divided into groups; Step (2): Based on the branch grouping results, propose a branch fault recovery optimization strategy under the line fault scenario; Step (3): Perform safety check on the reconnected line, and perform branch grouping again after the check passes, and provide new group data to the recovery program. The method of performing branch grouping on the line in step (1) is as follows: group the branch lines directly connected to the bus according to the bus type, the branch lines connected to the substation bus are grouped in the first feeder group, and the bus connected to the distributed power supply is grouped in the second feeder group; group the remaining branches, and use the second branch by default; perform grouping, and if: 1) the "to bus" of the second branch has two or more branches connected, then terminate the grouping and there will be only one branch; 2) Only one branch is connected to the "to bus" of the branch under consideration, and then continue to group. Step (2) considers the recovery plan of each individual branch failure scenario after grouping. By finding a recovery plan, when recovery occurs, the "branch group members" will take the same steps. Step (3) The safety verification method is: the line system topology after the reconnection changes. After changing the system topology, the line current I i ≤I max , line capacity S i ≤ S max , bus voltage limit V i ≥ V min , and line N-1 verification to maintain the radial structure of the system.

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