Topological structure identification method for low-voltage acquisition terminal, master station and computer readable storage medium

Abstract

The invention belongs to the technical field of low-voltage power distribution networks, and particularly relates to a topological structure identification method for a low-voltage acquisition terminal, a master station and a computer readable storage medium. The method comprises the following steps: 1) when the topological structure of the low-voltage power distribution network changes, a master station sends a characteristic current to a next-stage device directly connected with the master station, the characteristic current is used for enabling a device receiving the characteristic current to send a continuous sending characteristic current to the next-stage device connected with the master station, and returning data to an upper-stage device, the upper-level equipment receives the returned data and then sends the returned data to the master station step by step; the returned data comprises a receiver and a sender; and 2) the master station constructs a return data set based on the return data of each device, determines a real connection relationship in the low-voltage power distribution network based on the return data set, and connects a sender and a receiver in the real connection relationship so as to update the topological structure of the low-voltage power distribution network.

Description

Technical Field

[0001] This invention belongs to the field of low-voltage power distribution network technology, specifically relating to a topology identification method for low-voltage acquisition terminals, a master station, and a computer-readable storage medium. Background Technology

[0002] During the construction of new power systems, low-voltage distribution networks are characterized by high equipment density, numerous branch lines, and large load fluctuations. The large-scale integration of new equipment such as distributed photovoltaics and user-side energy storage, coupled with the intertwining of residential and commercial electricity loads, has made the physical connections of the distribution network increasingly complex, placing higher demands on the precision and intelligence of operation and maintenance. As the core equipment for sensing the "nerve endings" of the distribution network, the edge-end integrated branch load monitoring and control unit currently has functions largely limited to data acquisition and fault alarms, which is insufficient to meet the distribution network's need for dynamic understanding of equipment connection relationships. Therefore, it is urgent to expand its sensing capabilities to improve the level of lean power grid management. Compared to traditional edge-end integrated branch load monitoring and control units, the physical topology management of traditional edge-end integrated branch load monitoring and control units relies on manual on-site surveys and manual drawing, which has significant drawbacks: a single unit area may have dozens to hundreds of branch boxes, monitoring unit boxes and other equipment, and a complete survey requires multiple maintenance personnel to carry equipment to check point by point, taking more than 4 hours, which is extremely inefficient; after line modification and equipment addition or removal, the topology ledger is updated in a lag of several weeks or even months, resulting in a serious disconnect between the ledger and the actual connection; fault location requires reliance on experience to "test by cutting off the power segment", which prolongs the power outage time and is prone to misjudgment due to inaccurate topology information, which seriously restricts the fault response speed and the level of intelligent operation and maintenance. Summary of the Invention

[0003] The purpose of this invention is to provide a topology identification method, a master station, and a computer-readable storage medium for low-voltage data acquisition terminals, in order to solve the technical problems of time-consuming, labor-intensive, and inefficient construction of low-voltage distribution network topology in the prior art.

[0004] To address the aforementioned technical problems, this invention provides a topology identification method for low-voltage data acquisition terminals, comprising: 1) When the topology of the low-voltage distribution network changes, the master station sends characteristic currents to the low-voltage distribution network equipment directly connected to it; The characteristic current is used to enable the device receiving the characteristic current to send the characteristic current to the next level device connected to it, and to send data back to its previous level device. After receiving the returned data, the previous level device sends it to the master station level by level. The returned data includes the receiver and the sender. 2) The main station constructs a backhaul dataset based on the backhaul data from each device, determines the actual connection relationship in the low-voltage distribution network based on the backhaul dataset, and connects the sender and receiver in the actual connection relationship, thereby updating the topology of the low-voltage acquisition terminal in the low-voltage distribution network.

[0005] Furthermore, the returned data also includes the receiving time and the sending time, as well as the difference between the two, the transmit / receive time difference. Correspondingly, the method for updating the low-voltage distribution network topology includes: 2.1) The master station sets a basic weight based on the type of sending device in the returned data and a dynamic weight based on the transmit / receive time difference. If the sum of the basic weight and the dynamic weight is greater than or equal to the set real connection weight, the receiver and sender in the returned data are determined to be in a real connection relationship. The higher the level of the sending device type, the higher the basic weight, and the shorter the transmit / receive time difference, the higher the dynamic weight.

[0006] Furthermore, methods for updating the low-voltage distribution network topology also include: 2.2) After performing bidirectional communication verification to eliminate unidirectional connections and performing correct connection verification to eliminate cross-level connections, the verified low-voltage distribution network topology is obtained.

[0007] Furthermore, the method for verifying bidirectional communication is as follows: for a certain return data, check whether there is return data after the receiver and sender have swapped data. If it exists and the time difference between the transmission and reception of the return data is within the set time difference range, then the connection is determined to be a bidirectional connection; otherwise, it is determined to be a unidirectional connection and is eliminated.

[0008] Furthermore, the method for verifying the correct connection is as follows: for a certain return data, if its receiver and sender types belong to the set of receiver and sender types for correct connection in the low-voltage distribution network, then the sender and receiver are determined to be correctly connected; otherwise, the sender and receiver are determined to be cross-level connection, and the connection is eliminated.

[0009] Furthermore, the returned dataset is a preprocessed returned dataset, and the preprocessing includes at least one of the following: removing invalid returned data, removing duplicate returned data, and completing isolated devices. The method for eliminating invalid return data is to subtract the sending time from the receiving time of the return data to obtain the transmit / receive time difference, and to determine the data whose transmit / receive time difference is outside the set transmit / receive time difference range as invalid return data. The method for eliminating duplicate data is to group data with the same sender ID, the same receiver ID and a transmit / receive time difference less than a set value into a group. For a group of data, only the data with the smallest transmit / receive time difference is retained, and the rest of the data is judged as duplicate data and eliminated. The method for completing isolated devices is as follows: for isolated devices that have not sent any information, query the data returned by the device as the receiver, and complete the connection relationship of the isolated device based on the returned data.

[0010] Furthermore, when the change in the low-voltage distribution network topology is a local change, the master station sends characteristic currents to the devices whose topology has changed locally and their connected devices to locally update the devices whose topology has changed. When a new device comes online, an old device goes offline, or an old device does not send a signal back in the status of each device in the low-voltage distribution network, it is determined that the low-voltage distribution network topology has changed locally.

[0011] Furthermore, before the master station sends the characteristic current, at least one of the following steps is also included: The master station sends a time synchronization command to synchronize the time of each device in the low-voltage distribution network; The main station sends a link verification command to ensure that the link is working properly; The master station sends a historical data clearing command to clear the historical data of each device in the low-voltage distribution network.

[0012] The beneficial effects of this invention are as follows: By transmitting characteristic current step by step and transmitting back data step by step, this invention can determine the devices directly connected to the upper and lower levels of each device in the low-voltage distribution network, thereby determining the connection relationship between the devices. From this, the back data with the true connection relationship is selected, and the sender and receiver are connected to establish a connection, thereby updating the topology of the low-voltage distribution network and realizing the automatic construction of the low-voltage distribution network topology. There is no need for manual construction of the low-voltage distribution network topology, which not only saves time and manpower costs, but also has high efficiency and accuracy.

[0013] To address the aforementioned problems, this invention also provides a master station, including a processor. When executing a computer program, the processor implements a topology identification method for low-voltage data acquisition terminals, comprising: 1) When the topology of the low-voltage distribution network changes, the master station sends characteristic currents to the low-voltage distribution network equipment directly connected to it; The characteristic current is used to enable the device receiving the characteristic current to send the characteristic current to the next level device connected to it, and to send data back to its previous level device. After receiving the returned data, the previous level device sends it to the master station level by level. The returned data includes the receiver and the sender. 2) The main station constructs a backhaul dataset based on the backhaul data from each device, determines the actual connection relationship in the low-voltage distribution network based on the backhaul dataset, and connects the sender and receiver in the actual connection relationship, thereby updating the topology of the low-voltage acquisition terminal in the low-voltage distribution network.

[0014] Furthermore, the returned data also includes the receiving time and the sending time, as well as the difference between the two, the transmit / receive time difference. Correspondingly, the method for updating the low-voltage distribution network topology includes: 2.1) The master station sets a basic weight based on the type of sending device in the returned data and a dynamic weight based on the transmit / receive time difference. If the sum of the basic weight and the dynamic weight is greater than or equal to the set real connection weight, the receiver and sender in the returned data are determined to be in a real connection relationship. The higher the level of the sending device type, the higher the basic weight, and the shorter the transmit / receive time difference, the higher the dynamic weight.

[0015] Furthermore, methods for updating the low-voltage distribution network topology also include: 2.2) After performing bidirectional communication verification to eliminate unidirectional connections and performing correct connection verification to eliminate cross-level connections, the verified low-voltage distribution network topology is obtained.

[0016] Furthermore, the method for verifying bidirectional communication is as follows: for a certain return data, check whether there is return data after the receiver and sender have swapped data. If it exists and the time difference between the transmission and reception of the return data is within the set time difference range, then the connection is determined to be a bidirectional connection; otherwise, it is determined to be a unidirectional connection and is eliminated.

[0017] Furthermore, the method for verifying the correct connection is as follows: for a certain return data, if its receiver and sender types belong to the set of receiver and sender types for correct connection in the low-voltage distribution network, then the sender and receiver are determined to be correctly connected; otherwise, the sender and receiver are determined to be cross-level connection, and the connection is eliminated.

[0018] Furthermore, the returned dataset is a preprocessed returned dataset, and the preprocessing includes at least one of the following: removing invalid returned data, removing duplicate returned data, and completing isolated devices. The method for eliminating invalid return data is to subtract the sending time from the receiving time of the return data to obtain the transmit / receive time difference, and to determine the data whose transmit / receive time difference is outside the set transmit / receive time difference range as invalid return data. The method for eliminating duplicate data is to group data with the same sender ID, the same receiver ID and a transmit / receive time difference less than a set value into a group. For a group of data, only the data with the smallest transmit / receive time difference is retained, and the rest of the data is judged as duplicate data and eliminated. The method for completing isolated devices is as follows: for isolated devices that have not sent any information, query the data returned by the device as the receiver, and complete the connection relationship of the isolated device based on the returned data.

[0019] Furthermore, when the change in the low-voltage distribution network topology is a local change, the master station sends characteristic currents to the devices whose topology has changed locally and their connected devices to locally update the devices whose topology has changed. When a new device comes online, an old device goes offline, or an old device does not send a signal back in the status of each device in the low-voltage distribution network, it is determined that the low-voltage distribution network topology has changed locally.

[0020] Furthermore, before the master station sends the characteristic current, at least one of the following steps is also included: The master station sends a time synchronization command to synchronize the time of each device in the low-voltage distribution network; The main station sends a link verification command to ensure that the link is working properly; The master station sends a historical data clearing command to clear the historical data of each device in the low-voltage distribution network.

[0021] The beneficial effects of this invention are as follows: By transmitting characteristic current step by step and transmitting back data step by step, this invention can determine the devices directly connected to the upper and lower levels of each device in the low-voltage distribution network, thereby determining the connection relationship between the devices. From this, the back data with the true connection relationship is selected, and the sender and receiver are connected to establish a connection, thereby updating the topology of the low-voltage distribution network and realizing the automatic construction of the low-voltage distribution network topology. There is no need for manual construction of the low-voltage distribution network topology, which not only saves time and manpower costs, but also has high efficiency and accuracy.

[0022] To address the aforementioned problems, the present invention also provides a computer-readable storage medium storing a computer program that, when executed, implements a topology identification method for a low-voltage acquisition terminal, comprising: 1) When the topology of the low-voltage distribution network changes, the master station sends characteristic currents to the low-voltage distribution network equipment directly connected to it; The characteristic current is used to enable the device receiving the characteristic current to send the characteristic current to the next level device connected to it, and to send data back to its previous level device. After receiving the returned data, the previous level device sends it to the master station level by level. The returned data includes the receiver and the sender. 2) The main station constructs a backhaul dataset based on the backhaul data from each device, determines the actual connection relationship in the low-voltage distribution network based on the backhaul dataset, and connects the sender and receiver in the actual connection relationship, thereby updating the topology of the low-voltage acquisition terminal in the low-voltage distribution network.

[0023] Furthermore, the returned data also includes the receiving time and the sending time, as well as the difference between the two, the transmit / receive time difference. Correspondingly, the method for updating the low-voltage distribution network topology includes: 2.1) The master station sets a basic weight based on the type of sending device in the returned data and a dynamic weight based on the transmit / receive time difference. If the sum of the basic weight and the dynamic weight is greater than or equal to the set real connection weight, the receiver and sender in the returned data are determined to be in a real connection relationship. The higher the level of the sending device type, the higher the basic weight, and the shorter the transmit / receive time difference, the higher the dynamic weight.

[0024] Furthermore, methods for updating the low-voltage distribution network topology also include: 2.2) After performing bidirectional communication verification to eliminate unidirectional connections and performing correct connection verification to eliminate cross-level connections, the verified low-voltage distribution network topology is obtained.

[0025] Furthermore, the method for verifying bidirectional communication is as follows: for a certain return data, check whether there is return data after the receiver and sender have swapped data. If it exists and the time difference between the transmission and reception of the return data is within the set time difference range, then the connection is determined to be a bidirectional connection; otherwise, it is determined to be a unidirectional connection and is eliminated.

[0026] Furthermore, the method for verifying the correct connection is as follows: for a certain return data, if its receiver and sender types belong to the set of receiver and sender types for correct connection in the low-voltage distribution network, then the sender and receiver are determined to be correctly connected; otherwise, the sender and receiver are determined to be cross-level connection, and the connection is eliminated.

[0027] Furthermore, the returned dataset is a preprocessed returned dataset, and the preprocessing includes at least one of the following: removing invalid returned data, removing duplicate returned data, and completing isolated devices. The method for eliminating invalid return data is to subtract the sending time from the receiving time of the return data to obtain the transmit / receive time difference, and to determine the data whose transmit / receive time difference is outside the set transmit / receive time difference range as invalid return data. The method for eliminating duplicate data is to group data with the same sender ID, the same receiver ID and a transmit / receive time difference less than a set value into a group. For a group of data, only the data with the smallest transmit / receive time difference is retained, and the rest of the data is judged as duplicate data and eliminated. The method for completing isolated devices is as follows: for isolated devices that have not sent any information, query the data returned by the device as the receiver, and complete the connection relationship of the isolated device based on the returned data.

[0028] Furthermore, when the change in the low-voltage distribution network topology is a local change, the master station sends characteristic currents to the devices whose topology has changed locally and their connected devices to locally update the devices whose topology has changed. When a new device comes online, an old device goes offline, or an old device does not send a signal back in the status of each device in the low-voltage distribution network, it is determined that the low-voltage distribution network topology has changed locally.

[0029] Furthermore, before the master station sends the characteristic current, at least one of the following steps is also included: The master station sends a time synchronization command to synchronize the time of each device in the low-voltage distribution network; The main station sends a link verification command to ensure that the link is working properly; The master station sends a historical data clearing command to clear the historical data of each device in the low-voltage distribution network.

[0030] The beneficial effects of this invention are as follows: By transmitting characteristic current step by step and transmitting back data step by step, this invention can determine the devices directly connected to the upper and lower levels of each device in the low-voltage distribution network, thereby determining the connection relationship between the devices. From this, the back data with the true connection relationship is selected, and the sender and receiver are connected to establish a connection, thereby updating the topology of the low-voltage distribution network and realizing the automatic construction of the low-voltage distribution network topology. There is no need for manual construction of the low-voltage distribution network topology, which not only saves time and manpower costs, but also has high efficiency and accuracy. Attached Figure Description

[0031] Figure 1 This is a flowchart of the topology identification method for low-voltage acquisition terminals according to the present invention; Figure 2 This is a flowchart of the master station updating the low-voltage distribution network topology according to the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] Main site implementation method: This invention provides a master station for constructing a topology for low-voltage data acquisition terminals, located at the very end of a low-voltage distribution network. In this embodiment, the low-voltage data acquisition terminal is a monitoring unit box. The low-voltage distribution network includes transformers, distribution boxes, branch boxes, and monitoring unit boxes (also called monitoring units). The low-voltage distribution network exhibits a tree-like topology, with each level of equipment connected to the level above. In this embodiment, the hierarchy of other equipment in the low-voltage distribution network, from highest to lowest, is: transformer > distribution box > branch box > monitoring unit box.

[0034] When the master station of a low-voltage distribution network communicates with equipment in the network via a communication unit, it first sends commands to the communication unit within the network, which then forwards them to other equipment. Each piece of equipment in the low-voltage distribution network includes a communication unit.

[0035] This embodiment uses a low-voltage power distribution network with one transformer, five distribution boxes, 20 branch boxes, and 100 monitoring unit boxes as an example. The communication unit integrates carrier wave and low-power wireless dual channels.

[0036] The master station is used to send equipment list search frames and characteristic currents to the low-voltage distribution network through the communication unit, and to construct the topology of the low-voltage distribution network based on the data returned by each device in the low-voltage distribution network after receiving the equipment list search frames.

[0037] Because low-voltage distribution networks have a tree-like topology, device list search frames need to be sent down level by level. Upon receiving a device list search frame, the next-level device sends back its own data and then forwards the device list search frame to the next-level device connected to it. In this embodiment, the transformer, upon receiving a device list search frame, sends back its own data and then forwards the device list search frame to the distribution box connected to it, and so on.

[0038] The master station of the low-voltage distribution network includes a processor that, when executing a computer program, implements the topology identification method for low-voltage data acquisition terminals as described in this invention. The processor can be a microprocessor (MCU), a programmable logic device (FPGA), or other processing device. The method is as follows: Figure 1 As shown, it includes the following steps: Step 1: When a change in the low-voltage distribution network topology is detected, the master station initiates topology identification, performs file synchronization and link confirmation.

[0039] The master station sends a device list search frame, which is then transmitted transparently to all monitoring units via the communication unit. The device list search frame has a standard 68H frame header (68H + address field + function code + data field + checksum (16H)).

[0040] During this process, since the equipment list search frame is distributed level by level through the tree topology, when all monitoring units receive the equipment list search frame, other higher-level devices in the low-voltage distribution network will also receive the equipment list search frame.

[0041] In a low-voltage distribution network, all devices transmit their own status information, including "device ID-address-online status" data, after receiving the device list search frame.

[0042] To address the technical problem in existing technologies where the entire low-voltage distribution network topology needs to be reconstructed when the topology changes, this invention determines whether the change in the low-voltage distribution network structure is a local topology change based on the status information returned by all devices in the low-voltage grid. If it is a local topology change, the topology update can be performed only on the devices whose topology has changed and their connected devices, without having to rebuild the entire low-voltage distribution network topology, thus saving time and increasing efficiency.

[0043] For scenarios such as adding / deleting equipment and reconnecting lines, the specific criteria for determining changes in the low-voltage distribution network topology detected in this application include: when a new device comes online, an old device goes offline, or an old device has no signal feedback in the status of each device in the low-voltage distribution network, it is determined that a local change has occurred in the low-voltage distribution network topology.

[0044] The master station updates the archives synchronously based on the data returned by each device and verifies the links to ensure smooth operation and prevent subsequent commands from being sent to offline or mismatched devices. In this embodiment, the link verification method is to send an empty command to the master station to perform link verification. Specifically, the master station broadcasts a link test request frame to all online devices in the archive through the communication unit; after receiving the request frame, each device replies with a link test confirmation frame to the master station within a specified time limit via a carrier or wireless channel; the master station counts the confirmation frames received within the set time window. If the matching degree between the confirmed device ID and the online device ID in the archive reaches a preset threshold (e.g., 95%), the link is determined to be smooth, and subsequent time synchronization and topology identification processes can proceed; otherwise, the link is determined to be abnormal, the unresponsive device is recorded and an alarm is triggered, or a retry is initiated.

[0045] Step 2: Perform global time synchronization on all equipment in the low-voltage distribution network.

[0046] When the master station uses broadcast correction for global coarse calibration of the low-voltage distribution network, specifically: time calibration is performed on each device whose time deviation exceeds a set deviation, ultimately controlling the device's time deviation within the set time deviation range. In this embodiment, time calibration is performed on devices with a time deviation exceeding 50ns, and after calibration, the device's time deviation is controlled within 30ns. This provides accurate time for subsequent data transmission and topology establishment.

[0047] Step 3: Clear historical data.

[0048] The main station issues a historical data clearing frame to clear the historical residual data stored in various devices in the low-voltage distribution network, so as to avoid the impact of historical residual data on the current topology identification.

[0049] Step 4: The master station sends characteristic current generation frames at intervals.

[0050] The communication unit transmits the characteristic current generation frame sent by the master station to the corresponding monitoring unit. Upon receiving the frame, the monitoring unit generates a characteristic current injection line representing the monitoring unit's device ID and timestamp, and sends it back for confirmation, ensuring no signal overlap or conflict. The master station then summarizes and processes the received feedback results to generate a topology diagram of the low-voltage distribution network.

[0051] During the transparent transmission process, the characteristic current utilizes the tree topology of the low-voltage distribution network, transmitting it level by level. The master station sends the characteristic current to the next-level device directly connected to it. This characteristic current is used to instruct the receiving device to continue sending the characteristic current to its connected next-level device and to send data back to its previous-level device. The previous-level device receives the returned data and sends it back to the master station level by level. Specifically, in this embodiment, the master station sends the characteristic current to the transformer, the transformer sends information back to the master station, and sends the characteristic current to the distribution box; after receiving the characteristic current, the distribution box sends a message back to the transformer and sends the characteristic current to its next-level branch box; after receiving the characteristic current, the branch box sends a message back to its previous-level distribution box and sends the characteristic current to its next-level monitoring unit; after receiving the characteristic current, the monitoring unit sends data back to its previous-level branch box.

[0052] Taking the monitoring unit as an example: After receiving the characteristic current generation frame, the monitoring unit sends its own ID, transmission time Ts, and receiver ID to the upstream receiver (branch box in this embodiment). The branch box records the reception time Tr and calculates the transmission and reception time difference Δt to form a return data. The return data is then sent to the distribution box connected to it, the distribution box sends it to the transformer, and the transformer sends it to the main station.

[0053] Therefore, a single data transmission should include: sender ID, transmission time Ts, receiver ID (the ID of the upstream device directly connected to the sender), receiver reception time Tr, and transmit / receive time difference Δt. Transmit / receive time difference Δt = Tr - Ts.

[0054] The specific method used by the main site to construct the return dataset based on the returned data is as follows: In this embodiment, the returned dataset is in tabular form, namely the returned data table. The original returned data is organized into a table containing "sender ID, sending time Ts, receiver ID, receiving time Tr, and transmit / receive time difference △t", where the transmit / receive time difference △t = Tr - Ts.

[0055] In this embodiment, the returned dataset is the preprocessed returned dataset. Preprocessing includes at least one of the following: removing invalid returned data, removing duplicate returned data, and completing isolated device data. For ease of explanation, this embodiment uses three preprocessing methods as an example, such as... Figure 2 As shown, the steps to generate a low-voltage distribution network topology diagram are as follows: 4.1 Perform data preprocessing on the returned dataset and construct the returned dataset.

[0056] In this embodiment, data preprocessing includes removing invalid data, removing duplicate data, and completing invalid nodes.

[0057] The method for removing invalid data is as follows: invalid data is removed from the returned data aggregated by the main station according to the transmit / receive time difference between the receiving and sending times. Specifically, in this embodiment, the aggregated received data is filtered according to the transmit / receive time difference Δt, and data with transmit / receive time differences within the set transmit / receive time difference range is selected to remove invalid data outside the set transmit / receive time difference range.

[0058] When the time difference between receiving and sending times is greater than 300ms, the data returned by the device may not be a response to the characteristic current sent by the master station, and is therefore deemed invalid data. To avoid affecting subsequent topology construction, this data is discarded. For data with a time difference Δt less than 0, the device returns the data before receiving the characteristic current sent by the master station. Obviously, the returned data is not a response to the received information from the master station, and is therefore deemed invalid data and removed. Based on this, in this embodiment, the time difference range is set to (0, 300ms).

[0059] The method for removing duplicate data is triple deduplication, specifically: deduplication is performed according to the sender ID, sending time, and receiver ID to avoid duplicate edges caused by the same signal being collected multiple times. For example, if a monitoring unit repeatedly receives the same set of characteristic currents, it is considered as multiple connections.

[0060] In this embodiment, triple deduplication is based on the combination of three pieces of information: "sender ID + transmission time Ts + receiver ID" to form a valid record. Specifically, return data with the same sender ID, the same receiver ID, and a transmission time difference less than a set difference (1 ns in this embodiment) are grouped together. After deduplication, only one record is retained from each group. In this embodiment, the record with the smallest transmit / receive time difference Δt is retained from the same group, and all other duplicate data are deleted. The record with the smallest Δt is closest to the actual transmission delay; therefore, retaining the record with the smallest transmit / receive time difference Δt can eliminate duplicate records with excessively large delays caused by interference.

[0061] An isolated node refers to a device that exists in the distribution network archive but has no signal interaction records in the original topology identification data. For example, branch box A is in the archive, but no feedback data sent by A is detected, nor is any other device receiving signals from device A detected. The method for completing isolated node data is as follows: based on the hierarchical correlation of the distribution network, the missing upstream isolated nodes are traced back through the signal records of downstream devices to achieve completion. For isolated devices that have not sent any information, their feedback data as receivers is queried, and the connection relationship of the isolated device is completed based on this feedback data. If a device has no direct feedback data (this device is the sender), but its downstream devices have feedback data as receivers, the potential connection relationship between these two devices is traced back.

[0062] Because the distribution network has a tree structure, the signal of each lower-level device must come from the upper-level device. For example, the signal of the monitoring unit only comes from the branch box, the signal of the branch box only comes from the distribution box, and the signal of the upper-level device must be received by the lower-level device directly connected to it. Therefore, the tree topology of the distribution network can be used to complete the isolation of nodes.

[0063] The specific method for completing isolated nodes is as follows: a) Identify isolated devices: Compare the list of device IDs recorded in the area archive with the list of all sender IDs that have appeared in the returned dataset. Any device that exists in the archive but has never appeared as a sender ID is marked as a "suspected isolated device".

[0064] b) Reverse association query: For each suspected isolated device (denoted as device X), search the back-transmitted dataset for all records where the receiver ID field is equal to the ID of device X.

[0065] c) Validation and completion: If one or more such records are found, it is considered that the device represented by the sender ID in these records (denoted as device Y1, Y2...) is very likely to be a direct subordinate of device X (because according to the protocol, they record events of receiving signals from device X).

[0066] Once the conditions are met, establish connection edges from device X to devices Y1, Y2... in the topology.

[0067] d) Final determination: If a suspected isolated device is not found to have any valid data transmissions after querying, it will be marked as a completely offline or unrecognizable device and will not be presented in this topology.

[0068] 4.2. For the preprocessed data, set a basic weight Wb according to the type of the sending device and a dynamic weight Wd according to the time difference between transmission and reception Δt. Based on the basic weight and the dynamic weight, filter out real edges and eliminate false edges to update the topology of the voltage distribution network.

[0069] Basic weights are set according to equipment type, with higher-level equipment in the distribution network having higher basic weights. In this embodiment, basic weights are assigned according to the order "Transformer 10 > Distribution Box 8 > Branch Box 5 > Meter Box 3". Dynamic weights are assigned based on the transmit / receive time difference Δt. The smaller the transmit / receive time difference, the larger the dynamic weight. In this embodiment, when Δt ≤ 100ms, the dynamic weight is 3. For every 100ms increase in Δt, the dynamic weight decreases by 1. When Δt > 300ms, the dynamic weight is 0.

[0070] For example, spurious edges in cross-branch coupling are caused by excessively long Δt (e.g., Δt=280ms, Wd=1) or hierarchical mismatch (e.g., transformer → branch box, skipping the distribution box, Wb=5<8).

[0071] The total weight is calculated by summing the base weight and the dynamic weight. The total weight is then compared with the set real connection weight. If the total weight is greater than or equal to the set real weight, the connection between the sending device and the master station is determined to be real; otherwise, the connection between the sending device and the master station is determined to be fake.

[0072] Based on the sender ID and receiver ID of the actual connection relationship, the connection relationship between the sender and receiver is established, thereby updating the low-voltage distribution network to generate a tree-like topology structure of "transformer → distribution box → branch box → monitoring unit box".

[0073] 4.3 Verify the updated low-voltage distribution network topology.

[0074] In this embodiment, the method for verifying the topology of the low-voltage distribution network includes: performing bidirectional communication verification to eliminate unidirectional connections on the updated low-voltage distribution network topology, and performing correct connection verification to eliminate cross-level connections, thereby obtaining the verified low-voltage distribution network topology.

[0075] In this embodiment, the low-voltage distribution network presents a tree topology, and the various devices are strictly connected according to their levels. Cross-level connections are not allowed. Therefore, in this embodiment, when removing residual false edges, the set of device connection relationships in the low-voltage distribution network topology is traversed, and the upper-level type and lower-level device type are extracted. These are compared with the standard level connection relationship (main station → transformer → distribution box → branch box → monitoring unit box). If the upper-level device and the lower-level device in a certain connection relationship are not within the standard level connection relationship, it is determined to be a residual false connection edge and is removed.

[0076] Meanwhile, genuine connection edges possess bidirectional communication capabilities. Therefore, this embodiment also performs bidirectional communication verification on the low-voltage distribution network topology to eliminate unidirectional false connection edges. The specific bidirectional communication verification method is as follows: For a given return data, query whether there is return data after the receiver and sender have swapped data. If it exists and the transmit / receive time difference of the return data is within the set transmit / receive time difference range, then the connection is determined to be bidirectional; otherwise, it is determined to be unidirectional and eliminated. Specifically: For a given connection relationship (A→B), reverse query the signal record for "B→A". If a signal record for "B→A" exists and the transmit / receive time difference Δt in that record is within the set transmit / receive time difference range (0, 300ms], then the bidirectional connection between A and B is determined to be valid, and the connection between them is a genuine connection edge. If there is no signal record for "B→A" or a signal record for "B→A" exists but the transmit / receive time difference Δt in that record is not within the set transmit / receive time difference range (0, 300ms], then the connection relationship between A and B is determined to be a unidirectional interference false connection edge.

[0077] When the topology of a low-voltage distribution network changes locally, the topology is updated only for the devices that have changed and their connected devices. The update method is the one described above, which locks the direct superiors and subordinates of the devices whose topology has changed in the low-voltage distribution network and determines their position in the entire topology, thereby updating the topology of the low-voltage distribution network.

[0078] In this implementation, the commands issued by the master station for device list search, precise time synchronization (broadcast time synchronization frames with nanosecond-level timestamps, and individual time synchronization frames with deviation correction values), and historical record clearing all adopt a structured format of "standard frame header (68H + address field + function code + data field + checksum (16H)"". This format covers device list search, precise time synchronization (broadcast time synchronization frames with nanosecond-level timestamps, and individual time synchronization frames with deviation correction values), and historical record clearing, and is compatible with traditional master station protocols. Furthermore, in this implementation, the transparent transmission mechanism between devices integrates carrier and low-power wireless dual channels, automatically switching to the faulty channel within 500ms.

[0079] Method implementation: The topology identification method for low-voltage acquisition terminals of the present invention includes the following steps: Step 1: When a change in the low-voltage distribution network topology is detected, the master station initiates topology identification, performs file synchronization and link confirmation.

[0080] The master station sends a device list search frame, which is then transmitted transparently to all monitoring units via the communication unit. The device list search frame has a standard 68H frame header (68H + address field + function code + data field + checksum (16H)).

[0081] During this process, since the equipment list search frame is distributed level by level through the tree topology, when all monitoring units receive the equipment list search frame, other higher-level devices in the low-voltage distribution network will also receive the equipment list search frame.

[0082] In a low-voltage distribution network, all devices transmit their own status information, including "device ID-address-online status" data, after receiving the device list search frame.

[0083] To address the technical problem in existing technologies where the entire low-voltage distribution network topology needs to be reconstructed when the topology changes, this invention determines whether the change in the low-voltage distribution network structure is a local topology change based on the status information returned by all devices in the low-voltage grid. If it is a local topology change, the topology update can be performed only on the devices whose topology has changed and their connected devices, without having to rebuild the entire low-voltage distribution network topology, thus saving time and increasing efficiency.

[0084] For scenarios such as adding / deleting equipment and reconnecting lines, the specific criteria for determining changes in the low-voltage distribution network topology detected in this application include: when a new device comes online, an old device goes offline, or an old device has no signal feedback in the status of each device in the low-voltage distribution network, it is determined that a local change has occurred in the low-voltage distribution network topology.

[0085] The master station updates the archives synchronously based on the data returned by each device and verifies the links to ensure smooth operation and prevent subsequent commands from being sent to offline or mismatched devices. In this embodiment, the link verification method is to send an empty command to the master station to perform link verification. Specifically, the master station broadcasts a link test request frame to all online devices in the archive through the communication unit; after receiving the request frame, each device replies with a link test confirmation frame to the master station within a specified time limit via a carrier or wireless channel; the master station counts the confirmation frames received within the set time window. If the matching degree between the confirmed device ID and the online device ID in the archive reaches a preset threshold (e.g., 95%), the link is determined to be smooth, and subsequent time synchronization and topology identification processes can proceed; otherwise, the link is determined to be abnormal, the unresponsive device is recorded and an alarm is triggered, or a retry is initiated.

[0086] Step 2: Perform global time synchronization on all equipment in the low-voltage distribution network.

[0087] When the master station uses broadcast correction for global coarse calibration of the low-voltage distribution network, specifically: time calibration is performed on each device whose time deviation exceeds a set deviation, ultimately controlling the device's time deviation within the set time deviation range. In this embodiment, time calibration is performed on devices with a time deviation exceeding 50ns, and after calibration, the device's time deviation is controlled within 30ns. This provides accurate time for subsequent data transmission and topology establishment.

[0088] Step 3: Clear historical data.

[0089] The main station issues a historical data clearing frame to clear the historical residual data stored in various devices in the low-voltage distribution network, so as to avoid the impact of historical residual data on the current topology identification.

[0090] Step 4: The master station sends characteristic current generation frames at intervals.

[0091] The communication unit transmits the characteristic current generation frame sent by the master station to the corresponding monitoring unit. Upon receiving the frame, the monitoring unit generates a characteristic current injection line representing the monitoring unit's device ID and timestamp, and sends it back for confirmation, ensuring no signal overlap or conflict. The master station then summarizes and processes the received feedback results to generate a topology diagram of the low-voltage distribution network.

[0092] During the transparent transmission process, the characteristic current utilizes the tree topology of the low-voltage distribution network, transmitting it level by level. The master station sends the characteristic current to the next-level device directly connected to it. This characteristic current is used to instruct the receiving device to continue sending the characteristic current to its connected next-level device and to send data back to its previous-level device. The previous-level device receives the returned data and sends it back to the master station level by level. Specifically, in this embodiment, the master station sends the characteristic current to the transformer, the transformer sends information back to the master station, and sends the characteristic current to the distribution box; after receiving the characteristic current, the distribution box sends a message back to the transformer and sends the characteristic current to its next-level branch box; after receiving the characteristic current, the branch box sends a message back to its previous-level distribution box and sends the characteristic current to its next-level monitoring unit; after receiving the characteristic current, the monitoring unit sends data back to its previous-level branch box.

[0093] Taking the monitoring unit as an example: After receiving the characteristic current generation frame, the monitoring unit sends its own ID, transmission time Ts, and receiver ID to the upstream receiver (branch box in this embodiment). The branch box records the reception time Tr and calculates the transmission and reception time difference Δt to form a return data. The return data is then sent to the distribution box connected to it, the distribution box sends it to the transformer, and the transformer sends it to the main station.

[0094] Therefore, a single data transmission should include: sender ID, transmission time Ts, receiver ID (the ID of the upstream device directly connected to the sender), receiver reception time Tr, and transmit / receive time difference Δt. Transmit / receive time difference Δt = Tr - Ts.

[0095] The specific method used by the main site to construct the return dataset based on the returned data is as follows: In this embodiment, the returned dataset is in tabular form, namely the returned data table. The original returned data is organized into a table containing "sender ID, sending time Ts, receiver ID, receiving time Tr, and transmit / receive time difference △t", where the transmit / receive time difference △t = Tr - Ts.

[0096] In this embodiment, the returned dataset is the preprocessed returned dataset. Preprocessing includes at least one of the following: removing invalid returned data, removing duplicate returned data, and completing isolated device data. For ease of explanation, this embodiment uses three preprocessing steps as an example: The steps for generating the low-voltage distribution network topology diagram are as follows: 4.1 Perform data preprocessing on the returned dataset and construct the returned dataset.

[0097] In this embodiment, data preprocessing includes removing invalid data, removing duplicate data, and completing invalid nodes.

[0098] The method for removing invalid data is as follows: invalid data is removed from the returned data aggregated by the main station according to the transmit / receive time difference between the receiving and sending times. Specifically, in this embodiment, the aggregated received data is filtered according to the transmit / receive time difference Δt, and data with transmit / receive time differences within the set transmit / receive time difference range is selected to remove invalid data outside the set transmit / receive time difference range.

[0099] When the time difference between receiving and sending times is greater than 300ms, the data returned by the device may not be a response to the characteristic current sent by the master station, and is therefore deemed invalid data. To avoid affecting subsequent topology construction, this data is discarded. For data with a time difference Δt less than 0, the device returns the data before receiving the characteristic current sent by the master station. Obviously, the returned data is not a response to the received information from the master station, and is therefore deemed invalid data and removed. Based on this, in this embodiment, the time difference range is set to (0, 300ms).

[0100] The method for removing duplicate data is triple deduplication, specifically: deduplication is performed according to the sender ID, sending time, and receiver ID to avoid duplicate edges caused by the same signal being collected multiple times. For example, if a monitoring unit repeatedly receives the same set of characteristic currents, it is considered as multiple connections.

[0101] In this embodiment, triple deduplication is based on the combination of three pieces of information: "sender ID + transmission time Ts + receiver ID" to form a valid record. Specifically, return data with the same sender ID, the same receiver ID, and a transmission time difference less than a set difference (1 ns in this embodiment) are grouped together. After deduplication, only one record is retained from each group. In this embodiment, the record with the smallest transmit / receive time difference Δt is retained from the same group, and all other duplicate data are deleted. The record with the smallest Δt is closest to the actual transmission delay; therefore, retaining the record with the smallest transmit / receive time difference Δt can eliminate duplicate records with excessively large delays caused by interference.

[0102] An isolated node refers to a device that exists in the distribution network archive but has no signal interaction records in the original topology identification data. For example, branch box A is in the archive, but no data transmission from A is detected, nor is any other device receiving signals from A. The method for completing isolated node data is as follows: based on the hierarchical relationship of the distribution network, the missing upstream isolated nodes are traced back through the signal records of downstream devices to achieve completion. For isolated devices that do not send any information, their data transmission as receivers is queried, and the connection relationship of the isolated device is completed based on this data. If a device has no direct data transmission, but its downstream devices have signal reception records for that device, the potential connection relationship between the two devices is traced back.

[0103] Because the distribution network has a tree structure, the signal of each lower-level device must come from the upper-level device. For example, the signal of the monitoring unit only comes from the branch box, the signal of the branch box only comes from the distribution box, and the signal of the upper-level device must be received by the lower-level device directly connected to it. Therefore, the tree topology of the distribution network can be used to complete the isolation of nodes.

[0104] 4.2. For the preprocessed data, set a basic weight Wb according to the type of the sending device and a dynamic weight Wd according to the time difference between transmission and reception Δt. Based on the basic weight and the dynamic weight, filter out real edges and eliminate false edges to update the topology of the voltage distribution network.

[0105] Basic weights are set according to equipment type, with higher-level equipment in the distribution network having higher basic weights. In this embodiment, basic weights are assigned according to the order "Transformer 10 > Distribution Box 8 > Branch Box 5 > Meter Box 3". Dynamic weights are assigned based on the transmit / receive time difference Δt. The smaller the transmit / receive time difference, the larger the dynamic weight. In this embodiment, when Δt ≤ 100ms, the dynamic weight is 3. For every 100ms increase in Δt, the dynamic weight decreases by 1. When Δt > 300ms, the dynamic weight is 0.

[0106] For example, spurious edges in cross-branch coupling are caused by excessively long Δt (e.g., Δt=280ms, Wd=1) or hierarchical mismatch (e.g., transformer → branch box, skipping the distribution box, Wb=5<8).

[0107] The total weight is calculated by summing the base weight and the dynamic weight. The total weight is then compared with the set real connection weight. If the total weight is greater than or equal to the set real weight, the connection between the sending device and the master station is determined to be real; otherwise, the connection between the sending device and the master station is determined to be fake.

[0108] Based on the sender ID and receiver ID of the actual connection relationship, the connection relationship between the sender and receiver is established, thereby updating the low-voltage distribution network to generate a tree-like topology structure of "transformer → distribution box → branch box → monitoring unit box".

[0109] 4.3 Verify the updated low-voltage distribution network topology.

[0110] In this embodiment, the method for verifying the topology of the low-voltage distribution network includes: performing bidirectional communication verification to eliminate unidirectional connections on the updated low-voltage distribution network topology, and performing correct connection verification to eliminate cross-level connections, thereby obtaining the verified low-voltage distribution network topology.

[0111] In this embodiment, the low-voltage distribution network presents a tree topology, and the various devices are strictly connected according to their levels. Cross-level connections are not allowed. Therefore, in this embodiment, when removing residual false edges, the set of device connection relationships in the low-voltage distribution network topology is traversed, and the upper-level type and lower-level device type are extracted. These are compared with the standard level connection relationship (main station → transformer → distribution box → branch box → monitoring unit box). If the upper-level device and the lower-level device in a certain connection relationship are not within the standard level connection relationship, it is determined to be a residual false connection edge and is removed.

[0112] Meanwhile, genuine connection edges possess bidirectional communication capabilities. Therefore, this embodiment also performs bidirectional communication verification on the low-voltage distribution network topology to eliminate unidirectional false connection edges. The specific bidirectional communication verification method is as follows: For a given return data, query whether there is return data after the receiver and sender have swapped data. If it exists and the transmit / receive time difference of the return data is within the set transmit / receive time difference range, then the connection is determined to be bidirectional; otherwise, it is determined to be unidirectional and eliminated. Specifically: For a given connection relationship (A→B), reverse query the signal record for "B→A". If a signal record for "B→A" exists and the transmit / receive time difference Δt in that record is within the set transmit / receive time difference range (0, 300ms], then the bidirectional connection between A and B is determined to be valid, and the connection between them is a genuine connection edge. If there is no signal record for "B→A" or a signal record for "B→A" exists but the transmit / receive time difference Δt in that record is not within the set transmit / receive time difference range (0, 300ms], then the connection relationship between A and B is determined to be a unidirectional interference false connection edge.

[0113] When the topology of a low-voltage distribution network changes locally, the topology is updated only for the devices that have changed and their connected devices. The update method is the one described above, which locks the direct superiors and subordinates of the devices whose topology has changed in the low-voltage distribution network and determines their position in the entire topology, thereby updating the topology of the low-voltage distribution network.

[0114] Storage medium implementation methods: The computer-readable storage medium of the present invention, in one embodiment, is located within the main station of a low-voltage acquisition terminal, and internally stores a computer program that, when executed, implements a topology identification method for a low-voltage acquisition terminal as described below: Step 1: When a change in the low-voltage distribution network topology is detected, the master station initiates topology identification, performs file synchronization and link confirmation.

[0115] The master station sends a device list search frame, which is then transmitted transparently to all monitoring units via the communication unit. The device list search frame has a standard 68H frame header (68H + address field + function code + data field + checksum (16H)).

[0116] During this process, since the equipment list search frame is distributed level by level through the tree topology, when all monitoring units receive the equipment list search frame, other higher-level devices in the low-voltage distribution network will also receive the equipment list search frame.

[0117] In a low-voltage distribution network, all devices transmit their own status information, including "device ID-address-online status" data, after receiving the device list search frame.

[0118] To address the technical problem in existing technologies where the entire low-voltage distribution network topology needs to be reconstructed when the topology changes, this invention determines whether the change in the low-voltage distribution network structure is a local topology change based on the status information returned by all devices in the low-voltage grid. If it is a local topology change, the topology update can be performed only on the devices whose topology has changed and their connected devices, without having to rebuild the entire low-voltage distribution network topology, thus saving time and increasing efficiency.

[0119] For scenarios such as adding / deleting equipment and reconnecting lines, the specific criteria for determining changes in the low-voltage distribution network topology detected in this application include: when a new device comes online, an old device goes offline, or an old device has no signal feedback in the status of each device in the low-voltage distribution network, it is determined that a local change has occurred in the low-voltage distribution network topology.

[0120] The master station updates the archives synchronously based on the data returned by each device and verifies the links to ensure smooth operation and prevent subsequent commands from being sent to offline or mismatched devices. In this embodiment, the link verification method is to send an empty command to the master station to perform link verification. Specifically, the master station broadcasts a link test request frame to all online devices in the archive through the communication unit; after receiving the request frame, each device replies with a link test confirmation frame to the master station within a specified time limit via a carrier or wireless channel; the master station counts the confirmation frames received within the set time window. If the matching degree between the confirmed device ID and the online device ID in the archive reaches a preset threshold (e.g., 95%), the link is determined to be smooth, and subsequent time synchronization and topology identification processes can proceed; otherwise, the link is determined to be abnormal, the unresponsive device is recorded and an alarm is triggered, or a retry is initiated.

[0121] Step 2: Perform global time synchronization on all equipment in the low-voltage distribution network.

[0122] When the master station uses broadcast correction for global coarse calibration of the low-voltage distribution network, specifically: time calibration is performed on each device whose time deviation exceeds a set deviation, ultimately controlling the device's time deviation within the set time deviation range. In this embodiment, time calibration is performed on devices with a time deviation exceeding 50ns, and after calibration, the device's time deviation is controlled within 30ns. This provides accurate time for subsequent data transmission and topology establishment.

[0123] Step 3: Clear historical data.

[0124] The main station issues a historical data clearing frame to clear the historical residual data stored in various devices in the low-voltage distribution network, so as to avoid the impact of historical residual data on the current topology identification.

[0125] Step 4: The master station sends characteristic current generation frames at intervals.

[0126] The communication unit transmits the characteristic current generation frame sent by the master station to the corresponding monitoring unit. Upon receiving the frame, the monitoring unit generates a characteristic current injection line representing the monitoring unit's device ID and timestamp, and sends it back for confirmation, ensuring no signal overlap or conflict. The master station then summarizes and processes the received feedback results to generate a topology diagram of the low-voltage distribution network.

[0127] During the transparent transmission process, the characteristic current utilizes the tree topology of the low-voltage distribution network, transmitting it level by level. The master station sends the characteristic current to the next-level device directly connected to it. This characteristic current is used to instruct the receiving device to continue sending the characteristic current to its connected next-level device and to send data back to its previous-level device. The previous-level device receives the returned data and sends it back to the master station level by level. Specifically, in this embodiment, the master station sends the characteristic current to the transformer, the transformer sends information back to the master station, and sends the characteristic current to the distribution box; after receiving the characteristic current, the distribution box sends a message back to the transformer and sends the characteristic current to its next-level branch box; after receiving the characteristic current, the branch box sends a message back to its previous-level distribution box and sends the characteristic current to its next-level monitoring unit; after receiving the characteristic current, the monitoring unit sends data back to its previous-level branch box.

[0128] Taking the monitoring unit as an example: After receiving the characteristic current generation frame, the monitoring unit sends its own ID, transmission time Ts, and receiver ID to the upstream receiver (branch box in this embodiment). The branch box records the reception time Tr and calculates the transmission and reception time difference Δt to form a return data. The return data is then sent to the distribution box connected to it, the distribution box sends it to the transformer, and the transformer sends it to the main station.

[0129] Therefore, a single data transmission should include: sender ID, transmission time Ts, receiver ID (the ID of the upstream device directly connected to the sender), receiver reception time Tr, and transmit / receive time difference Δt. Transmit / receive time difference Δt = Tr - Ts.

[0130] The specific method used by the main site to construct the return dataset based on the returned data is as follows: In this embodiment, the returned dataset is in tabular form, namely the returned data table. The original returned data is organized into a table containing "sender ID, sending time Ts, receiver ID, receiving time Tr, and transmit / receive time difference △t", where the transmit / receive time difference △t = Tr - Ts.

[0131] In this embodiment, the returned dataset is the preprocessed returned dataset. Preprocessing includes at least one of the following: removing invalid returned data, removing duplicate returned data, and completing isolated device data. For ease of explanation, this embodiment uses three preprocessing steps as an example: The steps for generating the low-voltage distribution network topology diagram are as follows: 4.1 Perform data preprocessing on the returned dataset and construct the returned dataset.

[0132] In this embodiment, data preprocessing includes removing invalid data, removing duplicate data, and completing invalid nodes.

[0133] The method for removing invalid data is as follows: invalid data is removed from the returned data aggregated by the main station according to the transmit / receive time difference between the receiving and sending times. Specifically, in this embodiment, the aggregated received data is filtered according to the transmit / receive time difference Δt, and data with transmit / receive time differences within the set transmit / receive time difference range is selected to remove invalid data outside the set transmit / receive time difference range.

[0134] When the time difference between receiving and sending times is greater than 300ms, the data returned by the device may not be a response to the characteristic current sent by the master station, and is therefore deemed invalid data. To avoid affecting subsequent topology construction, this data is discarded. For data with a time difference Δt less than 0, the device returns the data before receiving the characteristic current sent by the master station. Obviously, the returned data is not a response to the received information from the master station, and is therefore deemed invalid data and removed. Based on this, in this embodiment, the time difference range is set to (0, 300ms).

[0135] The method for removing duplicate data is triple deduplication, specifically: deduplication is performed according to the sender ID, sending time, and receiver ID to avoid duplicate edges caused by the same signal being collected multiple times. For example, if a monitoring unit repeatedly receives the same set of characteristic currents, it is considered as multiple connections.

[0136] In this embodiment, triple deduplication is based on the combination of three pieces of information: "sender ID + transmission time Ts + receiver ID" to form a valid record. Specifically, return data with the same sender ID, the same receiver ID, and a transmission time difference less than a set difference (1 ns in this embodiment) are grouped together. After deduplication, only one record is retained from each group. In this embodiment, the record with the smallest transmit / receive time difference Δt is retained from the same group, and all other duplicate data are deleted. The record with the smallest Δt is closest to the actual transmission delay; therefore, retaining the record with the smallest transmit / receive time difference Δt can eliminate duplicate records with excessively large delays caused by interference.

[0137] An isolated node refers to a device that exists in the distribution network archive but has no signal interaction records in the original topology identification data. For example, branch box A is in the archive, but no data transmission from A is detected, nor is any other device receiving signals from A. The method for completing isolated node data is as follows: based on the hierarchical relationship of the distribution network, the missing upstream isolated nodes are traced back through the signal records of downstream devices to achieve completion. For isolated devices that do not send any information, their data transmission as receivers is queried, and the connection relationship of the isolated device is completed based on this data. If a device has no direct data transmission, but its downstream devices have signal reception records for that device, the potential connection relationship between the two devices is traced back.

[0138] Because the distribution network has a tree structure, the signal of each lower-level device must come from the upper-level device. For example, the signal of the monitoring unit only comes from the branch box, the signal of the branch box only comes from the distribution box, and the signal of the upper-level device must be received by the lower-level device directly connected to it. Therefore, the tree topology of the distribution network can be used to complete the isolation of nodes.

[0139] 4.2. For the preprocessed data, set a basic weight Wb according to the type of the sending device and a dynamic weight Wd according to the time difference between transmission and reception Δt. Based on the basic weight and the dynamic weight, filter out real edges and eliminate false edges to update the topology of the voltage distribution network.

[0140] Basic weights are set according to equipment type, with higher-level equipment in the distribution network having higher basic weights. In this embodiment, basic weights are assigned according to the order "Transformer 10 > Distribution Box 8 > Branch Box 5 > Meter Box 3". Dynamic weights are assigned based on the transmit / receive time difference Δt. The smaller the transmit / receive time difference, the larger the dynamic weight. In this embodiment, when Δt ≤ 100ms, the dynamic weight is 3. For every 100ms increase in Δt, the dynamic weight decreases by 1. When Δt > 300ms, the dynamic weight is 0.

[0141] For example, spurious edges in cross-branch coupling are caused by excessively long Δt (e.g., Δt=280ms, Wd=1) or hierarchical mismatch (e.g., transformer → branch box, skipping the distribution box, Wb=5<8).

[0142] The total weight is calculated by summing the base weight and the dynamic weight. The total weight is then compared with the set real connection weight. If the total weight is greater than or equal to the set real weight, the connection between the sending device and the master station is determined to be real; otherwise, the connection between the sending device and the master station is determined to be fake.

[0143] Based on the sender ID and receiver ID of the actual connection relationship, the connection relationship between the sender and receiver is established, thereby updating the low-voltage distribution network to generate a tree-like topology structure of "transformer → distribution box → branch box → monitoring unit box".

[0144] 4.3 Verify the updated low-voltage distribution network topology.

[0145] In this embodiment, the method for verifying the topology of the low-voltage distribution network includes: performing bidirectional communication verification to eliminate unidirectional connections on the updated low-voltage distribution network topology, and performing correct connection verification to eliminate cross-level connections, thereby obtaining the verified low-voltage distribution network topology.

[0146] In this embodiment, the low-voltage distribution network presents a tree topology, and the various devices are strictly connected according to their levels. Cross-level connections are not allowed. Therefore, in this embodiment, when removing residual false edges, the set of device connection relationships in the low-voltage distribution network topology is traversed, and the upper-level type and lower-level device type are extracted. These are compared with the standard level connection relationship (main station → transformer → distribution box → branch box → monitoring unit box). If the upper-level device and the lower-level device in a certain connection relationship are not within the standard level connection relationship, it is determined to be a residual false connection edge and is removed.

[0147] Meanwhile, genuine connection edges possess bidirectional communication capabilities. Therefore, this embodiment also performs bidirectional communication verification on the low-voltage distribution network topology to eliminate unidirectional false connection edges. The specific bidirectional communication verification method is as follows: For a given return data, query whether there is return data after the receiver and sender have swapped data. If it exists and the transmit / receive time difference of the return data is within the set transmit / receive time difference range, then the connection is determined to be bidirectional; otherwise, it is determined to be unidirectional and eliminated. Specifically: For a given connection relationship (A→B), reverse query the signal record for "B→A". If a signal record for "B→A" exists and the transmit / receive time difference Δt in that record is within the set transmit / receive time difference range (0, 300ms], then the bidirectional connection between A and B is determined to be valid, and the connection between them is a genuine connection edge. If there is no signal record for "B→A" or a signal record for "B→A" exists but the transmit / receive time difference Δt in that record is not within the set transmit / receive time difference range (0, 300ms], then the connection relationship between A and B is determined to be a unidirectional interference false connection edge.

[0148] When the topology of a low-voltage distribution network changes locally, the topology is updated only for the devices that have changed and their connected devices. The update method is the one described above, which locks the direct superiors and subordinates of the devices whose topology has changed in the low-voltage distribution network and determines their position in the entire topology, thereby updating the topology of the low-voltage distribution network.

Claims

1. A topology identification method for a low-voltage collection terminal, characterized in that, The method comprises the following steps: 1) When the topology of the low-voltage power distribution network changes, the master station sends a characteristic current to the low-voltage power distribution network equipment directly connected thereto; The characteristic current is used to make the equipment receiving the characteristic current send the characteristic current to the next level of equipment connected thereto and return data to the previous level of equipment, and the previous level of equipment receiving the returned data is sent to the master station level by level; the returned data comprises the receiver and the sender; 2) The master station constructs a returned data set based on the returned data of each equipment, determines the real connection relationship in the low-voltage power distribution network based on the returned data set, and connects the sender and the receiver in the real connection relationship, thereby updating the topology of the low-voltage power distribution network.

2. The topology identification method for a low-voltage collection terminal according to claim 1, characterized in that, The returned data further comprises the receiving time and the sending time, and the difference between the two, the transmission-reception time difference, and correspondingly, the method for updating the topology of the low-voltage power distribution network comprises the following steps: 2.1) The master station sets a basic weight according to the type of the sending equipment in the returned data, and sets a dynamic weight according to the transmission-reception time difference, and if the sum of the basic weight and the dynamic weight is greater than or equal to a set real connection weight, it is determined that the receiver and the sender in the returned data are in a real connection relationship; the higher the level of the sending equipment type, the higher the basic weight, and the shorter the transmission-reception time difference, the higher the dynamic weight.

3. The topology identification method for a low-voltage collection terminal according to claim 2, characterized in that, The method for updating the topology of the low-voltage power distribution network further comprises the following steps: 2.2) After bidirectional communication verification eliminates unidirectional connection and correct connection verification eliminates cross-level connection, a verified low-voltage power distribution network topology is obtained.

4. The topology identification method for a low-voltage collection terminal according to claim 3, characterized in that, The method for bidirectional communication verification is that for a returned data, it is queried whether there is returned data after the receiver and the sender are interchanged, and if there is and the transmission-reception time difference of the returned data is within a set transmission-reception time difference range, it is determined that the connection is bidirectional, otherwise it is determined to be unidirectional and is eliminated.

5. The topology identification method for a low-voltage collection terminal according to claim 3, characterized in that, The method for correct connection verification is that for a returned data, if the types of the receiver and the sender belong to the set of types of receivers and senders in correct connection of the low-voltage power distribution network, it is determined that the sender and the receiver are in correct connection, otherwise it is determined that the sender and the receiver are in cross-level connection, and the connection is eliminated.

6. The method for topology identification of low-voltage collection terminals according to any one of claims 1-5, characterized in that, The returned data set is a preprocessed returned data set, and the preprocessing comprises at least one of the following: eliminating invalid returned data, eliminating duplicate returned data, and isolated equipment completion; The method for eliminating invalid returned data is that the transmission-reception time difference is obtained by subtracting the sending time from the receiving time, and the data whose transmission-reception time difference is outside the set transmission-reception time difference range is determined to be invalid returned data; The method for eliminating duplicate returned data is that data with the same sender ID, the same receiver ID and a transmission-reception time difference less than a set difference value are divided into a group of data, and for a group of data, only the data with the smallest transmission-reception time difference is retained, and the rest of the data is determined to be duplicate data and is eliminated; The method for isolated equipment completion is that for an isolated equipment that has not sent any information, the returned data of the isolated equipment as a receiver is queried, and the connection relationship of the isolated equipment is completed according to the returned data.

7. The method for topology identification of low-voltage collection terminals according to any one of claims 1-5, characterized in that, When the change of the low-voltage power distribution network topology is a local change, the master station sends a characteristic current to the device with local topology change and the device connected to the device with local topology change to perform local update on the device with local topology change, and determines that the low-voltage power distribution network topology has a local change when a new device is online, an old device is offline or the old device has no signal return.

8. The method for topology identification of low-voltage collection terminals according to any one of claims 1-5, characterized in that, Before the master station sends the characteristic current, at least one of the following steps is further included: The master station sends a time correction instruction to correct the time of each device in the low-voltage power distribution network. The master station sends a link verification instruction to ensure that the link is unblocked. The master station sends a history data clearing instruction to clear the history data of each device in the low-voltage power distribution network.

9. A primary station comprising a processor, characterized in that The processor implements the topology identification method for the low-voltage acquisition terminal according to any one of claims 1-8 when executing the computer program.

10. A computer-readable storage medium, characterized in that, The computer program is stored in the computer program product and implements the topology identification method for the low-voltage acquisition terminal according to any one of claims 1-8 when being executed.

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