A Method and System for Fault Location in Low-Voltage Distribution Networks Based on Topology Identification

Abstract

This invention relates to the field of fault detection and location technology, and discloses a method and system for fault location in low-voltage distribution networks based on topology identification. The method includes: Step 1, collecting terminal heartbeat signals, user power supply status identifiers, and switch position sequence signals within a fault process time window to determine the complete user set, the set of out-of-power users, and the set of closed circuits; Step 2, performing topology self-identification on the initial static topology based on the set of out-of-power users and the set of closed circuits to obtain a dynamic directed tree topology; Step 3, generating an influence domain indication table based on the dynamic directed tree topology; Step 4, generating a cost judgment combination based on the set of out-of-power users and the influence domain indication table, and determining the final single fault segment; Step 5, determining the minimum set of fault segments when the interpretation of a single fault segment is insufficient; Step 6, outputting the fault location result and generating corresponding topology location relationship information. This invention achieves deterministic location of faulty line segments and interpretable output of results.

Description

Technical Field

[0001] This invention belongs to the field of fault detection and location technology, specifically relating to a method and system for locating faults in low-voltage distribution networks based on topology identification. Background Technology

[0002] Low-voltage distribution networks have complex structures, numerous branches, and variable operating environments. When a line fault occurs, quickly and accurately measuring and locating the faulty section is crucial for improving power supply reliability. Existing fault location technologies suffer from limitations in the following measurement and judgment methods: One type of method relies on real-time measurement of electrical quantities such as voltage and current, inferring fault location through waveform or transient feature analysis. However, low-voltage distribution networks often have insufficient measurement points, and factors such as load fluctuations and signal interference can severely affect the quality and stability of measurement signals, leading to poor consistency and low reliability in location judgments based on such measurement results. Another type of method relies on static topology information and manually reported power outage information for logical judgment. The core flaw of this type of method is that the topological connections upon which its judgment depends are static and pre-set, failing to effectively correlate and verify with dynamic measurement datasets such as switch states and user power supply states actually collected at the time of the fault. Because the distribution network operation mode may change, the static topology cannot reflect the true connectivity state at the moment of the fault, resulting in inherent biases in the fault section deduction and measurement results based on it. Especially in cases with multiple branches and multiple potential fault points, it is difficult to accurately extract a single or minimized set of fault segments from the measurement data. Summary of the Invention

[0003] This invention provides a method and system for locating faults in low-voltage distribution networks based on topology identification. It solves the technical problems in related technologies where, when a fault occurs in a low-voltage distribution network, the actual operating topology of the distribution network is difficult to obtain accurately, and there is a lack of effective means to quantify the relationship between the user's power outage status and the impact of the line section, resulting in inconsistent fault location results and insufficient verifiability.

[0004] This invention provides a method for fault location in low-voltage distribution networks based on topology identification, comprising the following steps:

[0005] Step 1: Collect terminal heartbeat signals, user power supply status indicators, and switch position sequence signals within the fault process time window, and determine the complete user set, the power outage user set, and the closed circuit set.

[0006] Step 2: Perform topology self-identification on the initial static topology corresponding to the asset ledger based on the set of power outage users and the set of closed circuits to obtain a dynamic directed tree topology;

[0007] Step 3: Determine the set of downstream affected users based on the dynamic directed tree topology and generate an influence domain indicator table;

[0008] Step 4: Calculate the number of missed detections and the number of false positives based on the power outage user set and the impact domain indicator table, and generate a cost judgment combination; determine the final single fault section again according to the priority of the number of missed detections, the second priority of the number of false positives, and the number of downstream users.

[0009] Step 5: When the number of missed detections or the number of false detections in the cost judgment combination corresponding to the final single fault section are not zero, establish an equation matching relationship based on the power outage user set and the impact domain indication table, set fault identifiers for the line section, and determine the minimum fault section set.

[0010] Step 6: Based on the final set of single fault sections or minimum fault sections, output the corresponding fault location results, and generate fault location information based on the topological positional relationship elements of the line sections in the dynamic directed tree topology.

[0011] This invention provides a low-voltage distribution network fault location system based on topology identification, comprising:

[0012] The operation status acquisition module is used to acquire terminal heartbeat signals, user power supply status indicators and switch position sequence signals within the fault process time window, and to determine the set of power outage users and the set of closed circuits.

[0013] Run the topology identification module to perform topology self-identification on the initial static topology corresponding to the asset ledger based on the set of power outage users and the set of closed lines, and obtain a dynamic directed tree topology;

[0014] The topology impact modeling module is used to determine the set of downstream impacting users and generate an impact domain indicator table based on the dynamic directed tree topology.

[0015] The fault determination module is used to calculate the number of missed detections and the number of false positives based on the set of power outage users and the impact domain indicator table, and generate a cost judgment combination; the final single fault section is determined according to the priority of the number of missed detections, the second priority of the number of false positives, and the number of downstream users.

[0016] The multi-segment matching module is used to establish an equation matching relationship based on the set of outage users and the impact domain indicator table when the number of missed detections or the number of misjudgments in the cost judgment combination corresponding to the final single fault segment is not zero, and to set fault identifiers for line segments and determine the minimum set of fault segments.

[0017] The fault location result output module is used to output the corresponding fault location result based on the final single fault section or minimum fault section set, and to generate fault location information based on the topological positional relationship elements of the line section in the dynamic directed tree topology.

[0018] The beneficial effects of this invention are as follows: Based on the user power supply status identifier, terminal heartbeat signal and switch position sequence signal collected by the low-voltage distribution network during the fault process time window, combined with asset ledger information, this invention can self-identify the actual operating topology of the distribution network and construct a dynamic directed tree topology, so that the fault location process is based on the real operating state rather than the static configuration topology, thereby improving the reliability and consistency of the fault section location results.

[0019] By determining the set of downstream affected users of a line segment based on a dynamic directed tree topology and generating an influence domain indicator table, the relationship between user power outage observation results and the topological influence of the line segment is expressed in a structured manner, transforming fault location from experience-based judgment into a quantifiable measurement and analysis process. Furthermore, by statistically combining the number of missed detections, the number of false positives, and the number of downstream users, a cost judgment combination is formed, enabling quantitative identification of faulty line segments and avoiding location bias caused by a single criterion.

[0020] When a single fault segment cannot explain the entire power outage, this invention determines the minimum set of fault segments through equation matching, ensuring that the fault location results in multi-segment fault scenarios still have clear judgment criteria. Finally, based on a dynamic directed tree topology, the fault location results and corresponding topological positional relationship information are output, giving the location conclusions good interpretability and verifiability. Attached Figure Description

[0021] Figure 1 This is a flowchart of the low-voltage distribution network fault location method based on topology identification of the present invention. Detailed Implementation

[0022] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0023] like Figure 1 As shown, the low-voltage distribution network fault location method based on topology identification includes the following steps:

[0024] Step 1: Collect terminal heartbeat signals, user power supply status indicators, and switch position sequence signals within the fault process time window, and determine the complete user set, the power outage user set, and the closed circuit set.

[0025] Step 2: Perform topology self-identification on the initial static topology corresponding to the asset ledger based on the set of power outage users and the set of closed circuits to obtain a dynamic directed tree topology;

[0026] Step 3: Determine the set of downstream affected users based on the dynamic directed tree topology and generate an influence domain indicator table;

[0027] Step 4: Calculate the number of missed detections and the number of false positives based on the power outage user set and the impact domain indicator table, and generate a cost judgment combination; determine the final single fault section again according to the priority of the number of missed detections, the second priority of the number of false positives, and the number of downstream users.

[0028] Step 5: When the number of missed detections or the number of false detections in the cost judgment combination corresponding to the final single fault section are not zero, establish an equation matching relationship based on the power outage user set and the impact domain indication table, set fault identifiers for the line section, and determine the minimum fault section set.

[0029] Step 6: Based on the final set of single fault sections or minimum fault sections, output the corresponding fault location results, and generate fault location information based on the topological positional relationship elements of the line sections in the dynamic directed tree topology.

[0030] In one embodiment of the present invention, terminal heartbeat signals, user power supply status indicators, and switch sequence signals are collected within a fault process time window, and the complete set of users, the set of users experiencing power outages, and the set of closed circuits are determined, including:

[0031] Step 11: Determine the fault process time window. The fault process time window refers to the time interval from the start of an abnormal power supply status change in the low-voltage distribution network to the point before the power supply status stabilizes or enters the review stage. This time window is used to limit the data range involved in this fault analysis. The fault process time window can be determined by a power outage event. Specifically, when the topology terminal detects that the user's power supply status identifier changes from an active state to a de-energized state, or detects that the terminal heartbeat signal enters a state of continuous absence, it generates a power outage signal and sends it to the master station. The master station uses the time corresponding to the power outage signal as a reference time and extends it forward and backward by a preset duration centered on the reference time to form the fault process time window. The preset duration can be 30 seconds to obtain the observation data range covering the status change before and after the fault. The power outage signal is an event identifier generated by the topology terminal based on the user's power supply status identifier and the terminal heartbeat signal, and is only used to determine the reference time of the fault process time window. Further, the topology terminal caches the terminal heartbeat signal, user power supply status identifier, and switch position sequence signal near the reference time and uploads the cached data together after the fault process time window ends.

[0032] Based on the user information recorded in the asset ledger, all users corresponding to the asset ledger are identified, forming the complete user set. The asset ledger serves as the basic information recording carrier for the low-voltage distribution network, used to record the correspondence between users, line sections, and switching equipment. During the fault process time window, terminal heartbeat signals and user power supply status identifiers are collected for each user in the complete user set, while switch position sequence signals are collected for each switching device corresponding to the asset ledger. The terminal heartbeat signal characterizes the communication status between the user-side metering device and the master station; the user power supply status identifier characterizes whether the user is currently in a power-on or power-off state; and the switch position sequence signal characterizes the opening and closing status of each switching device in the low-voltage distribution network.

[0033] The initial static topology corresponding to the asset ledger can be generated manually or by a topology terminal using the characteristic current method during normal operation of the low-voltage distribution network. The topology terminal is a measurement and communication device deployed at user access nodes or line branches, used to acquire observations related to topology connectivity and transmit them to the master station. The characteristic current method refers to a method that, without changing the operation mode of the low-voltage distribution network, determines the connectivity between line segments and nodes by forming distinguishable characteristic current identifiers at different measurement points and detecting the reachability of these identifiers in the network. Based on the connectivity determination results uploaded by the topology terminal, the master station performs consistency verification on the correspondence between users, line segments, and nodes in the asset ledger, thereby forming or updating the initial static topology corresponding to the asset ledger.

[0034] Step 12: Within the fault process time window, perform time alignment processing on the terminal heartbeat signal and the user power supply status identifier based on the timestamp. Time alignment refers to corresponding signals from different sources according to a unified time axis to ensure the consistency of various observation information at the same point in time. During the time alignment process, users who are missing both the terminal heartbeat signal and the user power supply status identifier within the fault process time window are marked as missing. The missing label indicates that the user does not have valid observation data within the time window. Further, users not marked as missing in the entire user set are determined as the valid observation dataset, and the valid observation dataset serves as the valid user range for subsequent power outage determination and topology identification.

[0035] Step 13: After obtaining the valid observation dataset, the power outage status of users is determined. Specifically, in the valid observation dataset, if a user's terminal heartbeat signal is continuously missing within the fault process time window, and the corresponding user power supply status identifier indicates a power outage, the user is included in the power outage user set; otherwise, the user is not included in the power outage user set. This joint determination method combines communication anomalies with power supply status information, effectively reducing the risk of misjudgment caused by relying solely on a single signal. Simultaneously, the line status is determined based on the collected switch position sequence signals. When the switch position sequence signal indicates that all switches corresponding to a certain line segment are in the closed state, the line segment is considered to maintain electrical connection within the fault process time window, and the line segment is included in the closed line set; otherwise, the line segment is not included in the closed line set.

[0036] Through the above steps, the complete user set, the set of users experiencing power outages, and the set of closed circuits were determined within the fault process time window. This process provides clear and constrained data input boundaries for subsequent low-voltage distribution network fault location based on topology identification. By introducing the distinction between the complete user set and the effective observation dataset, the subsequent fault location process is based solely on user data with effective observation capabilities, improving the reliability of measurement data in fault location. By simultaneously acquiring the set of users experiencing power outages and the set of closed circuits, the actual operating state of the low-voltage distribution network can be accurately reflected at the topology level, providing the necessary conditions for subsequent construction of dynamic directed tree topology, analysis of fault impact range, and location of faulty line sections.

[0037] In one embodiment of the present invention, a dynamic directed tree topology is obtained by performing topology self-identification on the initial static topology corresponding to the asset ledger based on the set of power outage users and the set of closed circuits, including:

[0038] Step 21: Construct a closed-loop constraint topology based on the initial static topology corresponding to the asset ledger. The initial static topology refers to the topology structure composed of line segments, nodes, and their connection relationships recorded in the asset ledger, used to describe the theoretical connection relationships of the low-voltage distribution network under normal configuration. Based on the set of closed lines obtained in Step 13, delete line segments that do not belong to the set of closed lines from the initial static topology, and simultaneously delete nodes connected only by the deleted line segments, thereby obtaining a closed-loop constraint topology containing only actual closed lines. Further, based on the correspondence between users and user access nodes recorded in the asset ledger, map each user in the power outage user set to the corresponding user access node in the closed-loop constraint topology, so that power outage information can be clearly located in the topology structure.

[0039] To enhance the interpretability of fault diagnosis output, after mapping the set of outage users to user access nodes, a set of outage access nodes can be further formed, and an outage identifier can be set on the set of outage access nodes in a closed-constraint topology or a dynamic directed tree topology. The outage identifier indicates that a power outage signal uploaded by the topology terminal exists at the corresponding node. Since the set of outage access nodes is obtained by mapping the set of outage users, it is a proper subset of all user access node sets in the dynamic directed tree topology. The system can overlay this proper subset on the topology graph as a layer to achieve a structured presentation of the outage distribution range.

[0040] Step 22: Within the fault process time window, identify switch state change segments based on the collected switch position sequence signals. These state change segments refer to the time interval during which the switch position sequence signal changes from a closed state to an open state, characterizing the moment when topology switching occurs in the low-voltage distribution network. For each switch state change segment, compare the user's power supply status before and after the change. If a user was in a powered state before the change and transitioned to a power outage state after the change, it is determined that the user has a response relationship to the switch. This user response relationship to the switch describes the correspondence between the user's power outage state change and a specific switch action, serving as a crucial basis for subsequent topology hierarchy determination.

[0041] Step 23: After obtaining the user response relationships to the switches, inclusion and segmentation decisions are performed based on these relationships. Specifically, when a user's response relationship to all switches collectively covers another user's response relationship to all switches, the former is determined to be at a downstream level of the latter, thus determining the upstream and downstream hierarchical relationship between users. When at least one switch causes the response relationships of two users to differ, i.e., one user responds to the switch while the other does not, the two users are determined to be on different branches on either side of that switch. Through inclusion and segmentation decisions, the distribution relationship of power outage users in the closed-loop constraint topology is transformed into a clear branch division and hierarchical relationship.

[0042] Step 24: After obtaining the branch division and hierarchical relationship, the line segments in the closed-loop constraint topology are oriented. Taking the power supply side node as the upstream node, and according to the determined hierarchical relationship, each line segment is oriented from upstream to downstream, thus forming a directed topology. During the orientation process, possible loops are detected; when a loop is detected, the loop disconnect edge is selected according to the fixed order of the line segments in the asset ledger, and the line segment is taken as the disconnection object to eliminate the loop structure. Through the above processing, a loop-free directed structure is obtained, and the loop-free directed structure is determined as a dynamic directed tree topology. The dynamic directed tree topology is used to describe the actual operating topology state of the low-voltage distribution network within the fault process time window.

[0043] Through the above steps, this embodiment achieves topology self-identification processing based on the set of power outage users and the set of closed circuits, transforming the initial static topology described in the asset ledger into a dynamic directed tree topology that reflects the actual operating status during a fault. This dynamic directed tree topology not only preserves the actual connectivity of the low-voltage distribution network but also accurately displays the upstream and downstream relationships and branch distribution of power outage users in the topology structure by introducing user response relationships to switches and a hierarchical determination mechanism. This ensures that subsequent fault impact range analysis and fault section determination are all based on a unified, realistic, and loop-free topology structure, avoiding the uncertainties caused by relying on voltage waveforms, transient signals, or empirical rules in traditional methods.

[0044] In one embodiment of the present invention, determining the downstream influencing user set and generating an influence domain indicator table based on a dynamic directed tree topology includes:

[0045] Step 31: Based on the correspondence between users and user access nodes recorded in the asset ledger, map each user in the user set to the corresponding user access node in the dynamic directed tree topology. The user access node refers to the node in the low-voltage distribution network topology used to represent the user's access location and reflect the connection relationship between the user and the line segment. For multiple users mapped to the same user access node, an aggregation record is created. This aggregation record represents the entire set of users corresponding to that user access node, thereby reducing the number of times duplicate nodes are processed during subsequent traversal.

[0046] Step 32: For each line segment in the dynamic directed tree topology, identify its downstream nodes according to the directed direction of the line segment in the dynamic directed tree topology. The dynamic directed tree topology is a loop-free directed structure, with its directed direction pointing from the power source side to the load side, reflecting the direction of power transmission in the low-voltage distribution network. After identifying the downstream nodes, traverse along the directed edges in the dynamic directed tree topology to obtain the complete set of descendant nodes of the downstream node, and determine this set of descendant nodes as the downstream reachable node range of the corresponding line segment. The downstream reachable node range is used to characterize the set of nodes that may be affected by the line segment in the topology structure.

[0047] Step 33: For each line segment, based on the aggregated records obtained in Step 31, summarize the users corresponding to each node within the downstream reachable node range. Specifically, merge the user sets corresponding to each user access node within the downstream reachable node range to obtain a user union, and determine the user union as the downstream affected user set for that line segment. The downstream affected user set describes the range of all users that may be affected by power supply issues in the topology when a fault occurs in that line segment.

[0048] Step 34: After obtaining the downstream affected user set for each line segment, an influence domain indicator table is generated. This influence domain indicator table uses the entire user set as rows and the line segments in the dynamic directed tree topology as columns, representing the influence relationship between users and line segments. When a user belongs to the downstream affected user set corresponding to a line segment, the entry for that user in the influence domain indicator table corresponding to that line segment is set to one; when the user does not belong to the downstream affected user set, the corresponding entry is set to zero. In this way, the influence relationships in the topology are transformed into a structured indicator table form.

[0049] Through the above steps, this embodiment realizes the process of determining the downstream affected user set and generating the influence domain indicator table based on a dynamic directed tree topology. This process organically combines the topology information of the low-voltage distribution network with the user access relationship, enabling the influence relationship between line segments and users to be expressed in a clear and computable form. By determining the range of downstream reachable nodes along the directed direction in the dynamic directed tree topology, the propagation path of fault impact in the low-voltage distribution network is accurately reflected. By constructing an influence domain indicator table indexed by the entire user set and line segments, a unified data foundation is provided for subsequent calculation of missed detections and false positives, generation of cost judgment combinations, and fault segment location, avoiding reliance on complex signal processing methods such as voltage amplitude, transient waveforms, or spectral characteristics.

[0050] In one embodiment of the present invention, the number of missed detections and the number of false positives are calculated based on the power outage user set and the impact domain indication table to generate a cost judgment combination; the final single fault section is determined again according to the priority of the number of missed detections, the second priority of the number of false positives, and the number of downstream users, including:

[0051] Step 41: Determine the candidate line segment set based on the influence domain indicator table. The line segments corresponding to each column in the influence domain indicator table are identified as the candidate line segment set. For each line segment in the candidate line segment set, the influence identifier of the corresponding column in the influence domain indicator table is read. The influence identifier is used to indicate whether the user is located within the downstream influence range of that line segment.

[0052] Step 42: For each line segment in the candidate line segment set, traverse the entire user set and statistically analyze the matching relationship between user power outage status and impact identifiers. When a user belongs to the power outage user set and the corresponding impact identifier is zero, it indicates that the user is not covered by the impact range of the line segment but actually experiences a power outage. This situation is counted as a missed detection, and the number of missed detections is accumulated. When a user does not belong to the power outage user set and the corresponding impact identifier is one, it indicates that the user is covered by the impact range of the line segment but does not actually experience a power outage. This situation is counted as a misjudgment, and the number of misjudgments is accumulated. The number of missed detections and the number of misjudgments are used to measure the explanatory power of the line segment to the actual power outage impact.

[0053] Step 43: After completing the statistics of missed detections and false positives, for each line segment in the candidate line segment set, further count the number of users whose corresponding column value is one in the influence domain indicator table, and determine the number of users as the downstream users of that line segment. The number of downstream users is used to characterize the scale of users that the line segment may affect in the topology. Subsequently, the number of missed detections, the number of false positives, and the number of downstream users for the corresponding line segment are combined in a predetermined order to form the cost judgment combination corresponding to that line segment.

[0054] Step 44: After obtaining the cost judgment combinations corresponding to each candidate line segment, compare the cost judgment combinations in the candidate line segment set. During the comparison, the minimum number of missed detections is prioritized, followed by the minimum number of false positives, and then the minimum number of downstream users, filtering cost judgment combinations level by level. When there are still cases where cost judgment combinations are tied, the final single-fault segment is determined according to the fixed order of line segments in the asset ledger. Through the above comparison process, the line segment that best matches the actual power outage situation is determined from the candidate line segment set as the final single-fault segment.

[0055] Through the above steps, based on the influence domain indicator table generated by the dynamic directed tree topology, the user power outage observation results are quantitatively compared with the topological influence relationship of the line segment. This forms a cost judgment combination centered on the number of missed detections, the number of false positives, and the number of downstream users, enabling refined location of single faulty line segments in low-voltage distribution networks. This process transforms the traditional fault judgment method, which relies on experience or single signal characteristics, into a quantitative judgment mechanism based on the consistency between topology structure and measurement status, giving the determination of faulty segments clear comparison rules and repeatability.

[0056] In one embodiment of the present invention, before generating the cost judgment combination, the statistical data source used to determine the faulty line segment is constrained. Specifically, for each line segment in the candidate line segment set, discrete observation data for statistics is obtained only based on the values ​​of the entries in the corresponding row of the user's entire set and the corresponding column of the line segment in the influence domain indicator table. The discrete observation data refers to the set of entries in the influence domain indicator table consisting of zero or one value, used to characterize whether there is a topological influence relationship between the user and the line segment.

[0057] After acquiring the discrete observation data, statistical processing is performed on each line segment based on the discrete observation data to obtain the corresponding number of missed detections, number of false positives, and number of downstream users. The number of missed detections, number of false positives, and number of downstream users are all directly determined by the combination relationships between the values ​​of the entries in the influence domain indicator table, without introducing other weight parameters, empirical rules, or external judgment conditions. After completing the statistical processing, the number of missed detections, number of false positives, and number of downstream users corresponding to each line segment are combined in a predetermined order to form a cost judgment combination, which is used as the input basis for the final single-fault segment determination process in step 4. By limiting the statistical source of the cost judgment combination, the fault segment determination process is entirely based on the measurement results and topological influence relationships reflected in the influence domain indicator table.

[0058] Through this implementation method, the generation process of the cost judgment combination is constrained to a statistical interpretation of discrete measurement results, avoiding the introduction of judgment parameters or control strategies that are unrelated to the measurement. This ensures that the fault location results have a clear data source and a consistent judgment basis, thereby improving the repeatability and verifiability of the fault location results under different operating scenarios.

[0059] In one embodiment of the present invention, when the number of missed detections or the number of false detections in the cost judgment combination corresponding to the final single fault section are not zero, an equation matching relationship is established based on the power outage user set and the impact domain indication table, a fault identifier is set for the line section, and the minimum fault section set is determined, including:

[0060] Step 51: When the number of missed detections or the number of false detections in the cost judgment combination corresponding to the final single fault segment are not zero, the line segments corresponding to each column in the influence domain indicator table are determined as a set of candidate line segments, and a fault identifier is set for each line segment in the set of candidate line segments. The fault identifier is used to characterize whether the line segment is selected as a possible fault segment, so as to serve as the calculation object for the subsequent establishment of the equation matching relationship.

[0061] Step 52: For each user in the user set, determine the user's power outage status according to the power outage user set, and determine the impact identifier of each candidate line segment on the user according to the impact domain indicator table; take the candidate line segments as the traversal object, when there is a line segment with a fault identifier value of one and a corresponding impact identifier of one, the coverage result is determined to be one, otherwise the coverage result is determined to be zero, and establish an equation matching relationship between the coverage result and the user's power outage status, that is, a one-to-one correspondence relationship, wherein the coverage result is used to characterize whether the current user is covered by at least one line segment identified as fault in the topology;

[0062] Step 53: Under the condition of satisfying the equality matching relationship, determine the minimum set of faulty sections with the goal of minimizing the number of line sections with fault identifier values ​​of one. When there are ties, determine the total number of downstream users of the corresponding line section set according to the influence domain indicator table, and determine the final minimum set of faulty sections by prioritizing the minimum total number of downstream users and the fixed order of line sections in the asset ledger.

[0063] Through the above steps, using the influence domain indicator table generated by the dynamic directed tree topology, an equality matching constraint is established between the observation results of power outage users and the topological influence relationship of candidate line segments. When the determination of a single fault segment cannot fully explain the actual power outage situation, the minimum set of line segments that can simultaneously explain all power outage users is further determined. This process transforms the multi-segment fault situation that may exist in the low-voltage distribution network into a deterministic matching problem based on topological coverage relationships, so that the determination of fault segments has clear judgment rules and consistent data basis.

[0064] In one embodiment of the present invention, the process of determining the minimum fault segment set in step 5 further includes a pre-screening process for the candidate line segment set. Specifically, after determining the line segments corresponding to the columns of the influence domain indication table as the candidate line segment set, for each line segment in the candidate line segment set, the table entry corresponding to that line segment in the influence domain indication table in the row corresponding to the power outage user set is read. The table entry is used to characterize whether the power outage user is located within the downstream influence range of that line segment.

[0065] When at least one user in the power outage user set has a value of 1 in the corresponding column, it indicates that the line segment can affect at least one user who actually experienced a power outage in terms of topology, and the line segment is retained as a possible fault segment. When all users in the power outage user set have a value of zero in the corresponding column, it indicates that the line segment cannot explain the power outage phenomenon of any user in terms of topology, and the line segment is removed from the candidate line segment set. Through the above pre-screening process, a candidate line segment set is obtained after removing irrelevant line segments.

[0066] Fault identifiers are set for each line segment in the candidate line segment set after elimination, and the process proceeds to step 52 to establish an equation matching relationship. By introducing the above screening process before establishing the equation matching relationship, the line segments participating in the equation matching calculation are limited to those that are topologically related to the actual power outage users, thereby making the subsequent determination of the minimum fault segment set based on a more convergent and consistent data range.

[0067] This implementation method, while maintaining the original equation matching relationship and the logic for determining the minimum fault section set in step 5, further reduces the interference of irrelevant line sections on the calculation process, enabling the low-voltage distribution network fault location based on topology identification to more accurately reflect the actual correlation between the outage user and the faulty line section.

[0068] In one embodiment of the present invention, based on the final single-fault section or minimum fault section set, the corresponding fault location result is output, and fault location information is generated based on the topological positional relationship elements of the line section in the dynamic directed tree topology, including:

[0069] Step 61: Determine the set of faulty line segments for output based on the final single-fault segment and the minimum fault segment set. If the minimum fault segment set has been determined in Step 5, then the minimum fault segment set is determined as the set of faulty line segments; if the minimum fault segment set has not been determined, then the final single-fault segment is determined as the set of faulty line segments. Through this method, a unified expression of single-segment fault location results and multi-segment fault location results is achieved in the output stage.

[0070] Step 62: After determining the set of faulty line segments, for each line segment in the set, determine the corresponding line segment identifier according to the fixed order of line segments pre-set in the asset ledger, and associate the line segment identifier with the corresponding faulty line segment to generate a fault location result. The line segment identifier is used to consistently identify the same line segment under different data sources, different time windows, and different system environments, avoiding ambiguity caused by naming differences.

[0071] Step 63: For each line segment in the set of faulty line segments, extract the topological location relationship elements related to that line segment from the dynamic directed tree topology. These topological location relationship elements include at least the upstream and downstream nodes corresponding to the line segment, as well as the directed path information from the power supply side node to the line segment. The directed path consists of line segments and nodes sequentially connected along directed edges in the dynamic directed tree topology. Based on these topological location relationship elements, generate fault location information corresponding to the fault location result, enabling the fault location result to be clearly and interpretably described in the dynamic directed tree topology.

[0072] The topological location relationship elements may also include the results of directed layer-level calculations based on the set of power outage access nodes, to further define the priority investigation interval. The priority investigation interval is used to provide topological layer-level interpretation information for the output fault location results, without changing the rules for determining the final single fault segment or the minimum fault segment set. Specifically, assuming the power supply-side node of the dynamic directed tree topology is the root node, for each power outage access node in the set of power outage access nodes, the directed path length from the root node to that power outage access node is calculated; the power outage access node with the shortest path length is determined as the highest-level power outage point, which represents the location of the power outage impact closest to the power supply side at the topological level. Subsequently, backtracking step by step along the upstream direction of the highest-level power outage point, the nearest upstream node outside the set of power outage access nodes and located on the same root-to-leaf path as the highest-level power outage point is determined as the energized point; when no upstream node meeting the conditions is found during the backtracking process, the root node is determined as the energized point. The set of line segments covered by the directed path from the energized point to the highest level of power outage point is determined as the priority investigation interval, and this priority investigation interval is associated with the fault location result generated in step 62 as a supplementary field for fault location information.

[0073] Through the above implementation method, the determination result of the fault section is associated with the actual operating topology of the low-voltage distribution network during the fault process, so that the fault location output not only includes the identification information of the fault line section, but also the description of its positional relationship in the topology, which can improve the understandability and consistency of the fault location results.

[0074] This invention also provides a low-voltage distribution network fault location system based on topology identification, comprising:

[0075] The distribution network acquisition module is used to acquire terminal heartbeat signals, user power supply status indicators, and switch position sequence signals within the fault process time window, and to determine the set of power outage users and the set of closed circuits.

[0076] The topology identification module is used to perform topology self-identification on the initial static topology corresponding to the asset ledger based on the set of power outage users and the set of closed lines, and obtain a dynamic directed tree topology.

[0077] The influence domain construction module is used to determine the set of downstream influencing users based on the dynamic directed tree topology and generate an influence domain indicator table;

[0078] The fault determination module is used to calculate the number of missed detections and the number of false positives based on the set of power outage users and the impact domain indicator table, and generate a cost judgment combination; the final single fault section is determined according to the priority of the number of missed detections, the second priority of the number of false positives, and the number of downstream users.

[0079] The equation matching module is used to establish an equation matching relationship based on the set of outage users and the impact domain indication table when the number of missed detections or the number of misjudgments in the cost judgment combination corresponding to the final single fault section is not zero, and to set fault identifiers for line sections and determine the minimum set of fault sections.

[0080] The fault location result output module is used to output the corresponding fault location result based on the final single fault section or minimum fault section set, and to generate fault location information based on the topological positional relationship elements of the line section in the dynamic directed tree topology.

[0081] It should be noted that the interval and threshold sizes are set for ease of comparison. The size of the threshold depends on the amount of sample data and the base number set by those skilled in the art for each set of sample data, as long as it does not affect the proportional relationship between the parameter and the quantized value. Furthermore, the above formulas are all dimensionless calculations, and the formulas are derived from software simulations using a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0082] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of the present embodiments, all of which are within the protection scope of the present embodiments.

Claims

1. A method for fault location in low-voltage distribution networks based on topology identification, characterized in that, Includes the following steps: Step 1: Collect terminal heartbeat signals, user power supply status indicators, and switch position sequence signals within the fault process time window, and determine the complete user set, the power outage user set, and the closed circuit set. Step 2: Perform topology self-identification on the initial static topology corresponding to the asset ledger based on the set of power outage users and the set of closed circuits to obtain a dynamic directed tree topology; Step 3: Determine the set of downstream affected users based on the dynamic directed tree topology and generate an influence domain indicator table; Step 4: Calculate the number of missed detections and the number of false positives based on the power outage user set and the impact domain indicator table, and generate a cost judgment combination; determine the final single fault section again according to the priority of the number of missed detections, the second priority of the number of false positives, and the number of downstream users. Step 5: When the number of missed detections or the number of false detections in the cost judgment combination corresponding to the final single fault section are not zero, establish an equation matching relationship based on the power outage user set and the impact domain indication table, set fault identifiers for the line section, and determine the minimum fault section set. Step 6: Based on the final set of single fault sections or minimum fault sections, output the corresponding fault location results, and generate fault location information based on the topological positional relationship elements of the line sections in the dynamic directed tree topology.

2. The low-voltage distribution network fault location method based on topology identification according to claim 1, characterized in that, Determine the complete user set, the set of users experiencing power outages, and the set of closed circuits, including: Step 11: Determine the fault process time window. Based on the users corresponding to the asset ledger, determine the complete set of users. Within the fault process time window, collect terminal heartbeat signals and user power supply status identifiers for the users corresponding to the asset ledger, and collect switch position sequence signals for the switches corresponding to the asset ledger. Step 12: Within the fault process time window, the terminal heartbeat signal and the user power supply status identifier are time-aligned based on the timestamp. Users who lack terminal heartbeat signals and user power supply status identifiers are marked as missing, and users in the entire user set who are not marked as missing are identified as valid observation datasets. Step 13: In the effective observation dataset, when a user's terminal heartbeat signal is continuously missing and the user's power supply status is marked as out of power, the user is included in the out-of-power user set; otherwise, the user is not included in the out-of-power user set. When the switch position sequence signal indicates that all switches corresponding to the line segment are closed, the line segment is included in the closed line set; otherwise, the closed line set is not included.

3. The low-voltage distribution network fault location method based on topology identification according to claim 1, characterized in that, Perform topology self-identification on the initial static topology corresponding to the asset ledger to obtain a dynamic directed tree topology, including: Step 21: Based on the initial static topology corresponding to the asset ledger, delete line segments that do not belong to the closed line set and simultaneously delete nodes connected only by line segments to obtain a closed constraint topology; according to the correspondence between users and user access nodes in the asset ledger, map the set of power outage users to the user access nodes in the closed constraint topology. Step 22: Within the fault process time window, the change of the switch position sequence signal from closed to open is taken as the state change segment; compare the power supply status of each user before and after the change, and determine the user's response relationship to the switch when the user was powered before the change and was powered off after the change. Step 23: Perform inclusion and segmentation determination based on the user's response relationship to the switches; when one user's response relationship to all switches covers another user's response relationship to all switches, determine the downstream hierarchical relationship; when there are switches that make the response relationships of the two users different, determine different branches. Step 24: Based on the branch division and hierarchical relationship, the line segment is oriented from upstream to downstream with the power supply side node as the upstream. Loops are detected and loop disconnect edges are selected according to the fixed order of the line segments in the asset ledger to obtain a loop-free directed structure. The loop-free directed structure is then determined as a dynamic directed tree topology.

4. The low-voltage distribution network fault location method based on topology identification according to claim 1, characterized in that, The downstream influencing user set is determined based on the dynamic directed tree topology, and an influence domain indicator table is generated, including: Step 31: Based on the correspondence between users and user access nodes in the asset ledger, map each user in the user set to a user access node in the dynamic directed tree topology, and aggregate and record users mapped to the same user access node. Step 32: For each line segment in the dynamic directed tree topology, identify the downstream node according to the directed direction of the line segment in the dynamic directed tree topology, and traverse along the directed edge of the dynamic directed tree topology to obtain the set of descendant nodes of the downstream node, which is used as the downstream reachable node range of the line segment. Step 33: For each line segment, based on the aggregation record, summarize the users corresponding to each node within the downstream reachable node range, and determine the union of the summarized users as the downstream affected user set of the line segment. Step 34: Generate an influence domain indicator table with the entire user set as rows and the line segments in the dynamic directed tree topology as columns. When a user belongs to the downstream influence user set of the line segment, set the corresponding table entry to one; otherwise, set it to zero.

5. The low-voltage distribution network fault location method based on topology identification according to claim 1, characterized in that, Based on the power outage user set and the impact domain indicator table, the number of missed detections and false positives are calculated, and a cost judgment combination is generated. The final single-fault section is then determined according to the priority of missed detections, followed by false positives, and then the number of downstream users, including: Step 41: Determine the line segments corresponding to the columns of the influence domain indicator table as the candidate line segment set, and read the influence identifier of the corresponding column of each line segment in the candidate line segment set from the influence domain indicator table. Step 42: For each line segment in the candidate line segment set, traverse the entire user set. When a user belongs to the power outage user set and the impact flag is zero, accumulate the number of missed detections. When a user does not belong to the power outage user set and the impact flag is one, accumulate the number of false positives. Step 43: For each line segment in the candidate line segment set, count the number of users whose corresponding column value is one in the influence domain indicator table as the number of downstream users, and combine the number of missed detections, the number of misjudged cases and the number of downstream users in order as the cost judgment combination. Step 44: In the candidate line segment set, compare the cost judgment combinations in the order of minimum number of missed detections, minimum number of misjudgments, and minimum number of downstream users to determine the final single fault segment; when there are still ties, determine the final single fault segment according to the fixed order of line segments in the asset ledger.

6. The low-voltage distribution network fault location method based on topology identification according to claim 1, characterized in that, Step 4 further includes: before generating the cost judgment combination, for each line segment in the candidate line segment set, discrete observation data for statistics is obtained based solely on the values ​​of the table entries in the corresponding rows of the user set and the corresponding columns of the line segment in the influence domain indicator table; based on the discrete observation data, the number of missed detections, the number of false positives, and the number of downstream users corresponding to each line segment are statistically obtained, wherein the number of missed detections, the number of false positives, and the number of downstream users are all determined by the combination relationship of the table entry values ​​in the influence domain indicator table; the number of missed detections, the number of false positives, and the number of downstream users are combined in a predetermined order to form the cost judgment combination.

7. The low-voltage distribution network fault location method based on topology identification according to claim 1, characterized in that, Based on the equation matching relationship established between the power outage user set and the impact domain indication table, fault identifiers are set for line sections to determine the minimum set of fault sections, including: Step 51: When the number of missed detections or the number of false detections in the cost judgment combination corresponding to the final single fault section is not zero, the line sections corresponding to the columns of the influence domain indicator table are determined as the candidate line section set, and a fault identifier is set for each line section in the candidate line section set. Step 52: For each user in the user set, determine the user's power outage status according to the power outage user set, and determine the impact identifier of each candidate line segment on the user according to the impact domain indicator table; take the candidate line segments as the traversal object, when there is a line segment with a fault identifier value of one and an impact identifier of one, determine the coverage result as one, otherwise determine the coverage result as zero, and establish an equation matching relationship between the coverage result and the user's power outage status; Step 53: Under the condition of satisfying the equality matching relationship, determine the minimum set of fault sections with the goal of minimizing the number of line sections with fault identifier values ​​of one; when there are ties, determine the total number of downstream users according to the influence domain indicator table, and determine the minimum set of fault sections by prioritizing the minimum total number of downstream users and then the fixed order of line sections in the asset ledger.

8. The low-voltage distribution network fault location method based on topology identification according to claim 7, characterized in that, Step 5 further includes: after determining the line segments corresponding to the columns of the influence domain indication table as a set of candidate line segments, reading the table entry of the corresponding column of the influence domain indication table in the corresponding row of the power outage user set for each line segment in the candidate line segment set; retaining the line segment when at least one user in the power outage user set has a value of one in the table entry of the corresponding column, otherwise removing the line segment from the set of candidate line segments; setting a fault identifier for each line segment in the removed set of candidate line segments, and proceeding to step 52 to establish an equation matching relationship.

9. The low-voltage distribution network fault location method based on topology identification according to claim 1, characterized in that, Based on the final set of single-fault sections or minimum fault sections, the corresponding fault location results are output, and fault location information is generated based on the topological positional relationship elements of the line sections in the dynamic directed tree topology, including: Step 61: Determine the set of faulty line segments based on the final single-fault segment and the minimum fault segment set. When a minimum fault segment set exists, determine the minimum fault segment set as the set of faulty line segments; when a minimum fault segment set does not exist, determine the final single-fault segment as the set of faulty line segments. Step 62: For each line segment in the set of faulty line segments, determine the line segment identifier according to the fixed order of the line segments in the asset ledger, and associate the line segment identifier with the corresponding faulty line segment to generate a fault location result. Step 63: For each line segment in the set of faulty line segments, extract the topological location relationship elements in the dynamic directed tree topology, which include the upstream node, downstream node and directed path from the power supply side node to the line segment corresponding to the line segment, and generate fault location information corresponding to the fault location result based on the topological location relationship elements.

10. A low-voltage distribution network fault location system based on topology identification, characterized in that, The low-voltage distribution network fault location method based on topology identification as described in any one of claims 1-9 includes: The operation status acquisition module is used to acquire terminal heartbeat signals, user power supply status indicators and switch position sequence signals within the fault process time window, and to determine the set of power outage users and the set of closed circuits. Run the topology identification module to perform topology self-identification on the initial static topology corresponding to the asset ledger based on the set of power outage users and the set of closed lines, and obtain a dynamic directed tree topology; The topology impact modeling module is used to determine the set of downstream impacting users and generate an impact domain indicator table based on the dynamic directed tree topology. The fault determination module is used to calculate the number of missed detections and the number of false positives based on the set of power outage users and the impact domain indicator table, and generate a cost judgment combination; the final single fault section is determined according to the priority of the number of missed detections, the second priority of the number of false positives, and the number of downstream users. The multi-segment matching module is used to establish an equation matching relationship based on the set of outage users and the impact domain indicator table when the number of missed detections or the number of misjudgments in the cost judgment combination corresponding to the final single fault segment is not zero, and to set fault identifiers for line segments and determine the minimum set of fault segments. The fault location result output module is used to output the corresponding fault location result based on the final single fault section or minimum fault section set, and to generate fault location information based on the topological positional relationship elements of the line section in the dynamic directed tree topology.

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