Abnormal state self-healing control method and device for distributed energy access power distribution network

Abstract

The invention discloses a distributed energy access power distribution network abnormal state self-healing control method and device. The method comprises the following steps: monitoring the change state of current data on a target line in a power distribution network; when it is monitored that the change state of the current data meets a preset starting condition, abnormal state self-healing control is started; after abnormal state self-healing control is started, an abnormal area is positioned and an abnormal type is identified according to current data monitored at present, if the abnormal type is identified as a fault type, fault isolation is controlled, and if the abnormal type is identified as an overload abnormal type, a protection threshold value of the terminal is adaptively adjusted according to a current value monitored at present. According to the method, self-adaptive control over the abnormal state of the power distribution network can be achieved by combining fault and overload identification, the fault can be isolated in time in the fault state, distribution network protection misoperation can be prevented, and the operation reliability of the power distribution network is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution network protection control, and in particular to a method and device for self-healing control of abnormal state of distributed energy access to a power distribution network. Background Art

[0002] The access of distributed renewable energy to the distribution network can improve energy efficiency, utilization and power supply reliability, but it will also make the distribution network structure more complex and flexible. In the prior art, the protection of active distribution networks usually adopts a relay protection setting method based on the design of unidirectional current flow, that is, the protection setting value is determined according to the unidirectional current flow, and then the protection setting value is set for the relay protection device to be set. However, this method is not only complex in calculation, but also has poor adaptability, especially when applied to the scenario of distributed renewable energy access to the distribution network, the adaptability will be significantly reduced.

[0003] Based on the relay protection strategy, the self-healing strategy combined with distribution automation can automatically control the disconnection of the fault to isolate the fault when a fault occurs. However, the action process design of the self-healing strategy in the existing technology is often cumbersome, and because a fixed protection setting value is used, when fluctuating new energy or variable loads are connected to the distribution network, the distribution network will become active and the flow will cross in both directions. The overload of the power grid will also cause the current amplitude to increase significantly. The traditional self-healing strategy will easily cause the protection to refuse to operate or malfunction during the dynamic changes of such loads.

[0004] In order to improve the robustness of distribution network protection, some practitioners have proposed the strategy of adopting adaptive protection. However, in the existing technology, the fault type is usually determined by detecting the positive and negative sequence content in the fault current to adjust the setting value of the current protection in real time. This is not only complicated in calculation and low in control efficiency, but also fails to fully consider the protection refusal or malfunction caused by dynamic changes in load. When abnormal conditions such as a sudden increase in load causing a significant increase in current amplitude occur, the overlap between the current and the threshold will cause protection malfunction, and frequent protection malfunctions will affect the normal operation of the distribution network. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in response to the technical problems existing in the prior art, the present invention provides a self-healing control method and device for abnormal state of distributed energy access to distribution network, which is simple in implementation, low in cost, high in control efficiency and precision, and safe and reliable. The method and device can combine the identification of faults and overloads to realize adaptive control of abnormal state of distribution network, which can not only isolate faults in time in fault state, but also prevent malfunction of distribution network protection, thereby effectively improving the operation reliability of distribution network.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is: A method for self-healing control of abnormal state of distributed energy access to a distribution network, comprising: Monitor the changing status of current data on the target line in the distribution network; When the change state of the monitored current data meets the preset start condition, the abnormal state self-healing control is started; After starting the abnormal state self-healing control, the abnormal area is located and the abnormal type is identified according to the currently monitored current data. If it is identified as a fault type, the fault isolation is controlled. If it is identified as an overload abnormal type, the protection threshold of the terminal is adaptively adjusted according to the currently monitored current value.

[0007] Furthermore, the preset start condition includes: the current change exceeds a preset threshold and the duration exceeds a specified time.

[0008] Furthermore, locating the abnormal area according to the currently monitored current data includes: Determine whether there is overcurrent at each node on the target line; According to whether the target node, the upstream and downstream nodes of the target node, and the adjacent T nodes have an overcurrent state, it is judged whether the target node is located in the abnormal section, wherein the adjacent T nodes are adjacent nodes having the same upstream node as the target node; The abnormal section is located according to the abnormal status of each node.

[0009] Furthermore, the nodes are defined to include three states: forward overcurrent, reverse overcurrent and no overcurrent. Whether the target node is located in the abnormal section is determined according to the following rules: if node i is in forward overcurrent and the downstream node D adjacent to node i is in forward overcurrent, then the area where node i is located is determined to be non-abnormal, otherwise it is determined to be abnormal; if node i is in reverse overcurrent and the upstream node U adjacent to node i is reverse overcurrent start or the adjacent node T to node i is forward overcurrent start, then the area where node i is located is determined to be non-abnormal, otherwise it is determined to be abnormal; The method of locating the abnormal section according to the abnormal state of each node includes: judging the abnormal state of node i, the abnormal state of the upstream and downstream nodes of node i, and the adjacent T nodes; if node i, the upstream and downstream nodes of node i, and the adjacent T nodes are all abnormal, it is determined to be an abnormal area.

[0010] Determine whether node i is located in the abnormal section according to the following formula: , , , in, represents the load current at node i, represents the load current at the downstream node of node i, represents the load current at the upstream node of node i, represents the load current at the adjacent T node with the same upstream node as node i; The abnormal area ij is located according to the following formula: , , , in, Indicates the outliers in the area where node i, its upstream nodes, and adjacent T nodes are located. Indicates the outlier value in the area where node i and its downstream nodes are located. represents the outlier value of the region where the node ij is located, , as well as They represent the abnormal judgment values ​​corresponding to node i, the upstream node u of node i, and the adjacent T nodes of node i respectively.

[0011] Furthermore, the abnormality type identified according to the currently monitored current data includes: According to the current data currently monitored, the ,in, Indicates the voltage value of the target line, Indicates the phase difference between voltage and current; if If the value is less than the preset threshold, it is judged as a fault type; otherwise, it is judged as an overload abnormal type.

[0012] Further, the adaptively adjusting the protection threshold of the terminal according to the currently monitored current value includes: The protection threshold of the terminal is as follows: To make adaptive adjustments:

[0013] in, is the reliability coefficient, , Indicates the current and voltage values ​​of the target line. Indicates the phase difference between voltage and current.

[0014] A self-healing control device for abnormal state of distributed energy access to a distribution network, comprising: A monitoring module, used to monitor the changing status of current data on a target line in a distribution network; A start-up control module, used to start abnormal state self-healing control when the change state of the monitored current data meets the preset start-up conditions; The self-healing control module is used to locate the abnormal area and identify the abnormal type according to the currently monitored current data after starting the abnormal state self-healing control. If it is identified as a fault type, the fault isolation is controlled. If it is identified as an overload abnormal type, the protection threshold of the terminal is adaptively adjusted according to the currently monitored current value.

[0015] A computer device comprises a processor and a memory, wherein the memory is used to store a computer program, and the processor is used to execute the computer program to perform the above method.

[0016] A computer-readable storage medium storing a computer program, wherein the computer program implements the above method when executed by a processor.

[0017] Compared with the prior art, the advantages of the present invention are: the present invention monitors the changing state of current data on the target line of the distribution network in real time, and starts abnormal state self-healing control when the changing state reaches the preset starting condition. During the abnormal state self-healing control process, the abnormal area is first located and the abnormal type is identified, so as to perform different actions in combination with different abnormal types. When a fault occurs, the control is used to isolate the fault. In the case of overload, the control is used to adaptively adjust the protection threshold. The protection threshold can be adjusted in real time according to the dynamic change of the load, which can not only effectively perform fault protection, but also prevent erroneous protection actions caused by changes in current amplitude caused by load fluctuations. The control process is simple to implement, and no complex data processing is required. The complexity of control can also be reduced and the efficiency of control can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the implementation flow of the abnormal state self-healing control method for distributed energy access to the distribution network in this embodiment.

[0019] Figure 2 It is a comparative schematic diagram of protection thresholds used in a control process using the present invention and a traditional protection strategy in a specific application embodiment. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0021] like Figure 1 As shown, the steps of the abnormal state self-healing control method for distributed energy access to the distribution network in this embodiment include: Step S01: Monitor the change status of current data on a target line in a distribution network.

[0022] In this embodiment, the current data on the target line in the distribution network is monitored in real time, and the current data at the current moment is compared with the current data at the previous moment to determine the change state of the current data, and the change state of the current data can reflect the change trend of the current data. The change state can be specifically a change amount or a change rate.

[0023] It is understandable that, in addition to monitoring current data, other types of data, such as voltage data, etc., can also be monitored according to actual needs.

[0024] Step S02: When the change state of the monitored current data meets the preset start condition, the abnormal state self-healing control is started.

[0025] As an optional implementation, the preset start condition may include the current change exceeding the preset threshold and the duration exceeding the specified time, that is, the current change exceeding the preset threshold and the duration exceeding the specified time are used as the start criterion, and when the start criterion is detected to be met, the abnormal state self-healing control is started. If the start criterion is not met, the current / voltage data is continuously monitored in real time.

[0026] It is understandable that the thresholds of the current change amount and duration can be configured according to actual needs. For example, the threshold of the current change amount can be configured as , the duration threshold is half a power frequency cycle, then the following formula can be used as the start criterion to determine the feeder k Whether a sudden change in current occurs: (1) In the formula, The node before the change j Load current; The node after the change j Load current, t is the duration after the current stops changing, T is the power frequency cycle.

[0027] According to formula (1), when the current change is greater than 5% and the duration is greater than half of the power frequency cycle, it is determined that the start criterion is met, indicating that there is an abnormality at present and it is necessary to start the abnormal state self-healing control to further locate and identify the abnormality and perform corresponding actions.

[0028] Step S03. After starting the abnormal state self-healing control, locate the abnormal area and identify the abnormal type according to the currently monitored current data. If it is identified as a fault type, control the fault isolation. If it is identified as an overload abnormal type, the terminal protection threshold is adaptively adjusted according to the currently monitored current value.

[0029] In this embodiment, the positive direction is set in the distribution network to divide the active distribution network into regions, and the adjacent nodes of each node are divided into upstream nodes along the positive direction. A U , downstream nodes A D and T-node A T , T nodes are adjacent nodes with the same upstream node.

[0030] As an optional implementation, the following steps may be used to locate the abnormal area according to the currently monitored current data: Step S301. Determine whether there is overcurrent at each node on the target line; Step S302. Determine whether the target node is located in an abnormal section according to whether the target node, the upstream and downstream nodes of the target node, and the adjacent T nodes are in an overcurrent state, wherein the adjacent T nodes are adjacent nodes having the same upstream node as the target node; Step S303: locate the abnormal section according to the abnormal status of each node.

[0031] In this embodiment, the nodes are defined to include three states: forward overcurrent, reverse overcurrent, and no overcurrent. The abnormal area is located according to the following rules: If node i is in forward overcurrent and the downstream node D adjacent to node i is in forward overcurrent, the area where node i is located is determined to be non-abnormal, otherwise it is determined to be abnormal. That is, if the forward overcurrent of node i is in action and the downstream node D adjacent to node i is in forward overcurrent startup, the area where node i is located is determined to be non-abnormal, otherwise it is abnormal. If node i is in reverse overcurrent and the upstream node U adjacent to node i is in reverse overcurrent startup or the adjacent T node of node i is in forward overcurrent startup, the area where node i is located is determined to be non-abnormal, otherwise it is determined to be abnormal. That is, if node i is in reverse overcurrent action, the upstream node U adjacent to it is in reverse overcurrent startup or the adjacent T node of node i is in forward overcurrent startup, the area where node i is located is determined to be non-abnormal, otherwise it is abnormal.

[0032] For example, whether node i is located in an abnormal section can be determined according to the following formula: (2) (3) (4) in, represents the load current at node i, represents the load current at the downstream node of node i, represents the load current at the upstream node of node i, Represents the load current at the adjacent T-node that has the same upstream node as node i.

[0033] As shown in equations (2) to (4) above, if there is a forward or reverse overcurrent at node i, then The value is ±1. If there is no overcurrent, The value is 0, and the abnormal judgment value is calculated based on the overcurrent status of each node. , if there is an overcurrent at node i ( ), there is no overcurrent at the downstream node D of node i ( ), or if there is no overcurrent between node i and the adjacent T node of node i ( , ), there is an overcurrent at the upstream node U of node i ( ), calculate If the value of If it is 1, it indicates that there is an abnormality, otherwise it indicates that there is no abnormality. This can be used to determine whether node i is located in the abnormal section.

[0034] Further, the abnormal area is located according to the abnormal state of node i and its upstream and downstream nodes and adjacent T nodes. Specifically, the abnormal state of node i, the abnormal state of the upstream and downstream nodes of node i and the adjacent T nodes are judged. If node i, the upstream and downstream nodes of node i and the adjacent T nodes are all abnormal, it is determined to be an abnormal area. For example, the abnormal area ij can be located according to the following formula: (5) (6) (7) in, Indicates the outliers in the area where node i, its upstream nodes, and adjacent T nodes are located. Indicates the outlier value in the area where node i and its downstream nodes are located. represents the outlier value of the region where the node ij is located, , as well as They represent the abnormal judgment values ​​corresponding to node i, the upstream node u of node i, and the adjacent T nodes of node i respectively.

[0035] The abnormal section ij can be located in the above manner, and the upstream node i can be determined according to the positive direction.

[0036] This embodiment defines the direction of node current as normal overcurrent and reverse overcurrent, and then determines the abnormal state in combination with the overcurrent devices of the target node, the upstream and downstream nodes of the target node, and the adjacent T node (for example, calculates the abnormal value according to formula (2)), so as to realize abnormal location. It can skillfully integrate the bidirectional flow of power flow into the positioning method, so that the abnormal location is not affected by the bidirectional power flow. When the fluctuating new energy and variable load are connected to the distribution network, causing the distribution network to become active and the power flow to cross in both directions, the abnormal area can still be accurately located.

[0037] As an optional implementation, the following steps may be used to identify the abnormal type based on the currently monitored current data: According to the current data currently monitored, the ,in, U Indicates the voltage value of the target line, Indicates the phase difference between voltage and current; if If the value is less than the preset threshold, it is judged as a fault type; otherwise, it is judged as an overload abnormal type.

[0038] Specifically, Ucosφ is calculated to determine whether the abnormality is a fault or an overload. If the abnormality is a fault, the faulty section is removed according to the standard to complete the fault isolation. If the abnormality is an overload, the terminal protection threshold is further adaptively adjusted to prevent false operation caused by a substantial increase in current due to overload.

[0039] As an optional implementation, in the process of adaptively adjusting the protection threshold of the terminal according to the current current value, the protection threshold of the terminal can be adjusted by the following formula: To make adaptive adjustments: (8) in, is the reliability coefficient, for example, it can be 1.2 ~ 1.5, , Indicates the current and voltage values ​​of the target line.

[0040] The present invention monitors the changing state of the current data on the target line of the distribution network in real time, and starts the abnormal state self-healing control when the changing state reaches the preset starting condition. During the abnormal state self-healing control process, the abnormal area is first located and the abnormal type is identified to determine whether a fault occurs or an overload condition exists. Different actions are performed for the fault and overload conditions. If a fault occurs, the control is to perform fault isolation. If it is an overload condition, the control is to adaptively adjust the protection threshold, so that the parameters of the DFA protection can be adjusted in real time according to the dynamic change of the load. It can not only effectively ensure the safety of system operation, and timely perform protection actions when a fault occurs, but also prevent erroneous protection actions caused by changes in current amplitude caused by load fluctuations, and ensure the safety and stability of the distribution network operation. In addition, the entire control process of the present invention is simple to implement, without the need for complex data processing, and can also greatly improve the efficiency of control.

[0041] In a specific application example, the results obtained by using the above method of the present invention are as follows Figure 2 As shown, I represents the monitored current, I h represents the protection threshold used in the control process of the present invention, I h_old Indicates the protection threshold used in traditional protection strategies. Figure 2 It can be seen that the protection threshold I used in the traditional protection strategy h_old There will be an overlap point at a position where the current I has a larger value, so there will actually be a false operation in this area. The present invention can significantly increase the threshold at this position, thereby resisting the current amplitude change caused by load fluctuations, preventing protection false operation, and ensuring the reliability of DFAs.

[0042] The abnormal state self-healing control device for accessing the distributed energy distribution network in this embodiment includes: A monitoring module, used to monitor the changing status of current data on a target line in a distribution network; A start-up control module, used to start abnormal state self-healing control when the change state of the monitored current data meets the preset start-up conditions; The self-healing control module is used to locate the abnormal area and identify the abnormal type according to the currently monitored current data after starting the abnormal state self-healing control. If it is identified as a fault type, the fault isolation is controlled. If it is identified as an overload abnormal type, the protection threshold of the terminal is adaptively adjusted according to the currently monitored current value.

[0043] The distributed energy access distribution network abnormal state self-healing control device of this embodiment corresponds to the above-mentioned distributed energy access distribution network abnormal state self-healing control method, and will not be described one by one here.

[0044] This embodiment further provides a computer device, including a processor and a memory, wherein the memory is used to store a computer program, and the processor is used to execute the computer program to perform the above method.

[0045] It is understandable that the above method of this embodiment can be executed by a single device, such as a computer or server, etc., and can also be applied to a distributed scenario and completed by multiple devices in cooperation with each other. In the case of a distributed scenario, one of the multiple devices can only execute one or more steps in the above method of this embodiment, and multiple devices interact to complete the above method. The processor can be implemented in the form of a general-purpose CPU, a microprocessor, an application-specific integrated circuit, or one or more integrated circuits, etc., for executing related programs to implement the above method of this embodiment. The memory can be implemented in the form of a read-only memory ROM, a random access memory RAM, a static storage device, and a dynamic storage device. The memory can store an operating system and other applications. When the above method of this embodiment is implemented by software or firmware, the relevant program code is stored in the memory and called and executed by the processor.

[0046] This embodiment further provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the above method is implemented.

[0047] Those skilled in the art should understand that the above-mentioned embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the process Figure 1 A process or multiple processes and / or boxes Figure 1These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0048] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for controlling abnormal state self-healing of distributed energy access to a distribution network, characterized in that the steps include: Monitor the changing status of current data on the target line in the distribution network; When the change state of the monitored current data meets the preset start condition, the abnormal state self-healing control is started; After starting the abnormal state self-healing control, the abnormal area is located and the abnormal type is identified according to the currently monitored current data. If it is identified as a fault type, the fault isolation is controlled. If it is identified as an overload abnormal type, the protection threshold of the terminal is adaptively adjusted according to the currently monitored current value.

2. The method for controlling the abnormal state of distributed energy access to the distribution network according to claim 1 is characterized in that: The preset start condition includes: the current change exceeds a preset threshold and the duration exceeds a specified time.

3. The method for controlling the abnormal state of distributed energy access to the distribution network according to claim 1 is characterized in that: The method of locating the abnormal area according to the currently monitored current data includes: Determine whether there is overcurrent at each node on the target line; According to whether the target node, the upstream and downstream nodes of the target node, and the adjacent T nodes have an overcurrent state, it is judged whether the target node is located in the abnormal section, wherein the adjacent T nodes are adjacent nodes having the same upstream node as the target node; The abnormal area is located according to the abnormal status of each node.

4. The method for controlling the abnormal state of distributed energy access to the distribution network according to claim 3 is characterized in that: The nodes are defined to contain three states: forward overcurrent, reverse overcurrent, and no overcurrent. The following rules are used to determine whether the target node is located in the abnormal section: if node i is in a forward overcurrent state and the downstream node D adjacent to node i is in a forward overcurrent state, the area where node i is located is determined to be non-abnormal, otherwise it is determined to be abnormal; If node i is in reverse overcurrent and the upstream node U adjacent to node i is in reverse overcurrent start or the adjacent node T to node i is in forward overcurrent start, then the area where node i is located is judged to be non-abnormal, otherwise it is judged to be abnormal; The method of locating the abnormal section according to the abnormal state of each node includes: judging the abnormal state of node i, the abnormal state of the upstream and downstream nodes of node i, and the adjacent T nodes; if node i, the upstream and downstream nodes of node i, and the adjacent T nodes are all abnormal, it is determined to be an abnormal area.

5. The method for controlling the abnormal state of distributed energy access to the distribution network according to claim 3 is characterized in that: Determine whether node i is located in the abnormal section according to the following formula: ， ， ， in, represents the load current at node i, represents the load current at the downstream node of node i, represents the load current at the upstream node of node i, represents the load current at the adjacent T node with the same upstream node as node i; The abnormal area ij is located according to the following formula: ， ， ， in, Indicates the outliers in the area where node i, its upstream nodes, and adjacent T nodes are located. Indicates the outlier value in the area where node i and its downstream nodes are located. represents the outlier value of the region where the node ij is located, , as well as They represent the abnormal judgment values ​​corresponding to node i, the upstream node u of node i, and the adjacent T nodes of node i respectively.

6. The method for controlling abnormal state self-healing of distributed energy access to a distribution network according to any one of claims 1 to 5, characterized in that: The abnormal types identified according to the currently monitored current data include: According to the current data currently monitored, the ,in, U Indicates the voltage value of the target line, Indicates the phase difference between voltage and current; if If the value is less than the preset threshold, it is judged as a fault type; otherwise, it is judged as an overload abnormal type.

7. The method for controlling abnormal state self-healing of distributed energy access to a distribution network according to any one of claims 1 to 5, characterized in that: The adaptively adjusting the protection threshold of the terminal according to the currently monitored current value includes: The protection threshold of the terminal is as follows: To make adaptive adjustments: ， in, is the reliability coefficient, , Indicates the current and voltage values ​​of the target line. Indicates the phase difference between voltage and current.

8. A self-healing control device for abnormal state of distributed energy access distribution network, characterized in that: include: A monitoring module, used to monitor the changing status of current data on a target line in a distribution network; A start-up control module, used to start abnormal state self-healing control when the change state of the monitored current data meets the preset start-up conditions; The self-healing control module is used to locate the abnormal area and identify the abnormal type according to the currently monitored current data after starting the abnormal state self-healing control. If it is identified as a fault type, the fault isolation is controlled. If it is identified as an overload abnormal type, the protection threshold of the terminal is adaptively adjusted according to the currently monitored current value.

9. A computer device comprising a processor and a memory, wherein the memory is used to store a computer program, wherein: The processor is configured to execute the computer program to perform the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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