A method and system for restoring operation of a power distribution network after a fault

Abstract

The application provides a method and system for recovering operation of a power distribution network after a fault, comprising: starting from an outlet switch of a transformer substation upstream of a fault area, sequentially searching for a tie switch connected with the line according to line topology, if the tie switch is closed, recording the switch, otherwise, continuing to search; starting from the outlet switch of the transformer substation, sequentially searching for a first non-tie switch in a split position and marking, after marking, not continuing to search; sequentially opening the recorded tie switches according to the recording order and locking the closing, until all the tie switches are opened; releasing the closing lock state of the non-tie switch and closing the switch; after all the switches of the line are powered and closed, releasing the closing lock state of the tie switches.

Description

Technical Field

[0001] This invention belongs to the field of power distribution network feeder automation technology, and in particular relates to a method and system for restoring operation after a power distribution network fault. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Feeder automation refers to automated measures that enable autonomous fault location, isolation, and power restoration after a fault occurs on a feeder (medium-voltage transmission line). It includes three implementation methods: centralized control, local control, and distributed control.

[0004] Traditional local feeder automation functions describe the process of sectionalizing switches and substation outlet switches working together to isolate faults and supply power to non-faulty lines after a line fault occurs, but do not explain how the entire line should be restored to normal operation after the fault is cleared.

[0005] Currently, on-site restoration primarily relies on remote control from the main station or manual local operation of switches. When the line topology is complex, traditional restoration methods may lead to erroneous operations. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a method for restoring operation after a power distribution network fault, which can effectively reduce the number of power outages for users and improve power supply reliability.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0008] Firstly, a method for restoring operation after a distribution network fault is disclosed, including:

[0009] Starting from the substation outlet switch upstream of the fault area, search for the tie switches connected to this line in sequence according to the line topology. If the tie switch is closed, record the switch; otherwise, continue searching.

[0010] Starting from the substation outlet switch, find the first non-tie switch in the terminating position according to the line topology and mark it. After marking, stop searching.

[0011] Disconnect each of the recorded interconnecting switches in the recorded order and lock the circuit breaker until all interconnecting switches are disconnected.

[0012] Release the open block status of the non-connecting switch and close the switch;

[0013] After all switches on this line are energized and closed, release the closing lockout status of each interconnecting switch.

[0014] Secondly, a system for restoring operation after a distribution network fault is disclosed, including:

[0015] The tie switch closure lookup module is configured to: start from the substation outlet switch upstream of the fault area, sequentially search for the tie switches connected to this line according to the line topology; if the tie switch is closed, record the switch; otherwise, continue searching.

[0016] The non-tie switch lookup module is configured to: start from the substation outlet switch, sequentially search for the first non-tie switch in the terminating position according to the line topology and mark it; after marking, stop searching.

[0017] The tie switch processing module is configured to: sequentially disconnect each recorded tie switch and lock the closing according to the recorded order, until all tie switches are disconnected;

[0018] The non-tethering switch processing module is configured to: release the open blockage state of the non-tethering switch and close the switch;

[0019] The recovery module is configured to: wait for all switches on this line to be energized and closed, then release the closing lockout state of each tie switch, and the entire line will resume operation.

[0020] The above one or more technical solutions have the following beneficial effects:

[0021] After troubleshooting, the technical solution of this invention first operates the tie switches that supply power to this line, sequentially opening and then locking them back to their original positions. Next, the locking status of the original faulty upstream switch is released, and power supply to the entire line is restored via the upstream substation. Finally, the locking status of the tie switches that previously supplied power to this line is released. This technical solution, which involves disconnecting the tie switches before restoring power, is suitable for situations where loop-locked operation of the line is not permitted.

[0022] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a flowchart of the power restoration process in this invention;

[0025] Figure 2This is the line topology in this embodiment of the invention. The fault point has been isolated, and the non-faulty section has been transferred to another power source. CB is the substation outlet circuit breaker, FS1-FS6 are line section and branch switches, LSW1-LSW3 are tie switches, and k is the fault point.

[0026] Figure 3 This is a schematic diagram of the power supply to the communication switch after it is disconnected in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the sectionalizing switch releasing the closing interlock and closing in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram showing the line fully returning to normal operation in an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the loop closing in a preferred embodiment of the present invention. Detailed Implementation

[0030] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0032] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0033] Example 1

[0034] See appendix Figure 1 As shown in the figure, this embodiment discloses a method for restoring operation after a distribution network fault, which includes the following steps:

[0035] (1) Starting from the substation outlet switch upstream of the fault area, search for the tie switch connected to this line in sequence according to the line topology. If the tie switch is closed, record the switch; otherwise, continue searching.

[0036] Specifically, when sequentially locating the tie switches connected to this line, the status of the tie switches and the voltage on both sides are collected based on the dynamic topology of the line before the fault for judgment. If the switch status is closed and there is voltage on both sides, the tie switch is closed. If the tie switch status is open and there is voltage on one side and no voltage on the other side, the tie switch is open and the search ends.

[0037] (2) Starting from the substation outlet switch, find the first non-tie switch in the terminating position according to the line topology and mark it. After marking, do not continue searching.

[0038] Specifically, when sequentially searching for the first non-tethered switch in the open position, based on the fault recovery strategy, remote or local remote control is applied. If the switch state changes from closed to open, then it is a non-tethered switch in the open position.

[0039] The aforementioned non-interconnecting switches include sectionalizing switches and substation outlet switches.

[0040] (3) Disconnect each of the connecting switches in step (1) in the order of the records and lock the closing circuit until all connecting switches are disconnected;

[0041] In this step, the closing interlock is to prevent misoperation, because misoperation of closing may re-close the faulty line, causing the entire line to lose power or causing injury to personnel who are repairing the fault.

[0042] (4) Release the tripping lockout state of the non-connecting switch in step (2) and close the switch;

[0043] In this step, the above operation is to prevent accidental operation, which could cause a power outage for the user.

[0044] (5) After all the switches that isolate the fault on this line are energized and closed, release the closed and locked state of each connecting switch in step (3). The advantage of the main station in this step is that the dispatcher can participate to ensure the safety of the entire system.

[0045] In step (1) above, the process of finding the contact switch is generally carried out at the main station. In special cases, it can also be carried out on-site. The process of finding the switch in step (2) is similar.

[0046] It should be noted that the closing interlock applied to the connecting switch in step (3) is unrelated to the "double-sided pressurized interlock closing" function in the connecting switch, and the same applies when the interlock is released in step (5).

[0047] Step (4) is divided into the following two cases according to the type of interlocking switch:

[0048] (4.1) If it is a sectional switch, its closing interlock should generally be “Y time limit interlock”. After the interlock is released, the switch should be able to automatically close after the continuous energization time on the substation side is greater than X time limit.

[0049] The aforementioned Y-time limit interlocking refers to the interlocking of the switch closing due to power failure within the Y-time limit during fault handling.

[0050] (4.2) If it is a substation outlet switch, its closing interlock should generally be "reclosing interlock". After the interlock is released, the switch may need to be manually closed.

[0051] The aforementioned reclosing lockout refers to the lockout of the switch when the number of reclosing attempts is reached during fault handling.

[0052] In step (4), if a fault is detected after the non-tethering switch is reclosed, the fault handling logic preset for that line will be followed. Step (5) is similar. This process can terminate the fault and resume operation, then proceed to fault handling.

[0053] As can be seen from the above scheme, after the fault is eliminated, the first step is to operate the tie switch that supplies power to this line to open and close it in sequence. Then, the closing and blocking status of the original faulty upstream switch is released, and the power supply to the entire line is restored through the upstream substation. Finally, the closing and blocking status of the tie switch that supplies power to this line is released. This dispatching method is easy to implement. In addition, the method of disconnecting the tie and then restoring power supply in this scheme is suitable for sites where the line cannot be operated in a loop.

[0054] In dynamic topologies where the voltage and frequency characteristics differ, another feasible solution is to first close the output switches sequentially downwards, and then disconnect the previously closed tie switches. This method can effectively reduce the number of power outages for users and improve power supply reliability. However, given the impact of the loop closing moment and the damage caused by the circulating current to the line, such sites generally require one of the following conditions:

[0055] (1) The topology is a single-connection "hand-in-hand" line, and the lines on both sides of the connection are different outgoing lines of the same busbar of the same substation;

[0056] (2) The topology is a single-connection "hand-in-hand" line, and the lines on both sides of the connection are different outgoing lines of different busbars of the same substation. The two busbars are allowed to operate in parallel.

[0057] (3) The topology is a single-connection "hand-in-hand" line, and the lines on both sides of the connection are different outgoing lines of different busbars of the same substation, but each section switch has the function of synchronizing.

[0058] Figure 2 The following is a line topology after fault isolation has been completed, and its line status is as follows:

[0059] (1) Section switch FS1 is locked in Y time limit, and section switches FS2 and FS4 are locked in X time limit;

[0060] (2) When the outlet switch CB is closed, the tie switches LSW1 and LSW3 are closed, and the sectional switches FS3, FS5 and FS6 are closed, power supply is restored to all lines outside the fault section.

[0061] Now, assuming that fault k has been eliminated and the line is required to return to normal operation, the steps are as follows:

[0062] (1) Starting from the outlet switch CB, search downstream of the line to see if the next switch is a closed tie switch or a closed non-tie switch. Finally, find that tie switches LSW1 and LSW3 are closed and the section switch FS1 is the first non-tie switch in the open position. Record the above information.

[0063] (2) Disconnect interconnecting switches LSW1 and LSW3 sequentially and lock them closed. FS3, FS5, and FS6 are de-energized and tripped. Figure 3 As shown;

[0064] (3) Release the closing interlock of sectionalizing switch FS1, wait for FS1 to be energized and close, and then wait for sectionalizing switches FS2-FS6 to be energized and close. Figure 4 , 5 As shown;

[0065] (4) Release the closing interlock of LSW1 and LSW3.

[0066] If the preferred solution is adopted, proceed as follows:

[0067] (1) Starting from the outlet switch CB, search downstream of the line to see if the next switch is a closed tie switch or a closed non-tie switch. Finally, find that tie switches LSW1 and LSW3 are closed and the section switch FS1 is the first non-tie switch in the open position. Record the above information.

[0068] (2) Close sectionalizing switch FS1 and release its closing interlock, then wait for sectionalizing switches FS2 and FS4 to be energized and closed. Figure 6 As shown;

[0069] (3) Disconnect the connecting switches LSW1 and LSW3 in sequence, and release their double-sided pressure interlocking, such as Figure 5 As shown.

[0070] Example 2

[0071] The purpose of this embodiment is to provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method.

[0072] Example 3

[0073] The purpose of this embodiment is to provide a computer-readable storage medium.

[0074] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the above method.

[0075] Example 4

[0076] The purpose of this embodiment is to provide a system for restoring operation after a distribution network fault, including:

[0077] The tie switch closure lookup module is configured to: start from the substation outlet switch upstream of the fault area, sequentially search for the tie switches connected to this line according to the line topology; if the tie switch is closed, record the switch; otherwise, continue searching.

[0078] The non-tie switch lookup module is configured to: start from the substation outlet switch, sequentially search for the first non-tie switch in the terminating position according to the line topology and mark it; after marking, stop searching.

[0079] The tie switch processing module is configured to: sequentially disconnect each recorded tie switch and lock the closing according to the recorded order, until all tie switches are disconnected;

[0080] The non-tethering switch processing module is configured to: release the closing lockout state of the non-tethering switch and close the switch;

[0081] The recovery module is configured to: wait for all switches on this line to be energized and closed, then release the closing lockout state of each tie switch, and the entire line will resume operation.

[0082] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0083] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0084] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for restoring operation after a distribution network fault, characterized in that, include: Starting from the substation outlet switch upstream of the fault area, search for the tie switches connected to this line in sequence according to the line topology. If the tie switch is closed, record the switch; otherwise, continue searching. Starting from the substation outlet switch, find the first non-tie switch in the terminating position according to the line topology and mark it. After marking, stop searching. Disconnect each of the recorded interconnecting switches in the recorded order and lock the circuit breaker until all interconnecting switches are disconnected. Release the open block status of the non-connecting switch and close the switch; After all switches on this line are energized and closed, release the closing lockout status of each interconnecting switch.

2. The method for restoring operation after a distribution network fault as described in claim 1, characterized in that, When sequentially locating the tie switches connected to this line, the status of the tie switches and the voltage on both sides are collected based on the dynamic topology of the line before the fault for judgment. If the switch status is closed and there is voltage on both sides, the tie switch is closed. If the tie switch status is open and there is voltage on one side and no voltage on the other side, the tie switch is open and the search ends.

3. The method for restoring operation after a distribution network fault as described in claim 1, characterized in that, When sequentially searching for the first non-tethered switch in the open position, based on the fault recovery strategy, remote or local remote control is applied. If the switch state changes from closed to open, then it is a non-tethered switch in the open position.

4. The method for restoring operation after a distribution network fault as described in claim 1, characterized in that, Non-interlocking switches include sectionalizing switches and substation outlet switches.

5. The method for restoring operation of a distribution network after a fault as described in claim 1, characterized in that, Release the open blocking state of the non-connecting switch and close the switch. If it is a sectionalizing switch, its closing blocking should be "Y time limit blocking". After the blocking is released, the switch should be able to automatically close after the continuous energization time on the substation side is greater than X time limit. The aforementioned Y-time limit interlocking refers to the interlocking of the switch closing due to power failure within the Y-time limit during fault handling.

6. The method for restoring operation of a distribution network after a fault as described in claim 1, characterized in that, If it is a substation outlet switch, its closing interlock should be "reclosing interlock". After the interlock is released, the switch may need to be manually closed. The aforementioned reclosing lockout refers to the lockout of the switch when the number of reclosing attempts is reached during fault handling.

7. A method for restoring operation of a distribution network after a fault, as described in any one of claims 1-6, characterized in that, The method is applicable to sites where loop operation is not permitted.

8. A system for restoring operation after a distribution network fault, characterized in that, include: The tie switch closure lookup module is configured to: start from the substation outlet switch upstream of the fault area, sequentially search for the tie switches connected to this line according to the line topology; if the tie switch is closed, record the switch; otherwise, continue searching. The non-tie switch lookup module is configured to: start from the substation outlet switch, sequentially search for the first non-tie switch in the terminating position according to the line topology and mark it; after marking, stop searching. The tie switch processing module is configured to: sequentially disconnect each recorded tie switch and lock the closing according to the recorded order, until all tie switches are disconnected; The non-tethering switch processing module is configured to: release the open blockage state of the non-tethering switch and close the switch; The recovery module is configured to: wait for all switches on this line to be energized and closed, then release the closing lockout state of each tie switch, and the entire line will resume operation.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it performs the steps of the method described in any of claims 1-7 above.

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