A power distribution network fault locating method based on photovoltaic inverter active perturbation topology fingerprint

Abstract

This invention discloses a method for fault location in distribution networks based on active perturbation topology fingerprinting of photovoltaic inverters, belonging to the field of power system automation technology. High-proportion distributed photovoltaic (PV) grid integration weakens fault currents in distribution networks and makes fault location difficult in complex feeder branches. This invention acquires transient measurement data from multiple measurement points, line topology parameters, and inverter operating status to construct a time-varying state diagram; extracts passive transient fault fingerprints and matches them to obtain passive diagnostic confidence; if insufficient, it selects inverter-generated perturbation signals and extracts active perturbation response fingerprints; it fuses passive and active fingerprints, inverter operating status, and the time-varying state diagram into a joint fault fingerprint, and matches it with a topology transient fingerprint template to obtain a comprehensive matching score; it generates a counterfactual transient response and compares it with the joint fault fingerprint to obtain a physical consistency residual; the final fault branch and distance are determined by the comprehensive matching score and the physical consistency residual. This invention improves fault observability and location reliability in scenarios with weak fault currents.

Description

Technical Field

[0001] This invention belongs to the field of power system automation technology, and in particular relates to a method for fault location in distribution networks based on active perturbation topology fingerprinting of photovoltaic inverters. Background Technology

[0002] With the advancement of new power system construction, the integration rate of distributed photovoltaic power in medium and low voltage distribution networks continues to increase. The fault characteristics of distribution networks have gradually shifted from the strong fault current characteristics under traditional unidirectional power supply to weak transient characteristics affected by inverter current limiting, low voltage ride-through, irradiance fluctuations, and load changes. In scenarios such as low irradiance, high-resistance grounding, single-phase grounding, and implicit grounding, traditional overcurrent, impedance, and zero-sequence current criteria are prone to problems such as insufficient sensitivity, unstable branch location, and decreased reliability of fault location. This makes it difficult for protection criteria that rely on fault current amplitude to operate reliably under weak fault characteristic conditions, and the identification stability of fault branches in multi-branch feeders is poor.

[0003] Existing fault diagnosis methods for distribution networks mainly include overcurrent protection, impedance methods, traveling wave methods, signal processing methods, and data-driven methods. Overcurrent protection and impedance methods are highly dependent on the magnitude of the fault current, and their sensitivity is severely insufficient in weak fault current scenarios. The traveling wave method is easily affected by the complexity of wavefront reflection and refraction, and has high requirements for strict time synchronization between multiple measurement points, making it difficult to implement in engineering. Signal processing methods and data-driven methods lack means to actively enhance fault observability and lack physical consistency verification mechanisms, resulting in insufficient interpretability and reliability of diagnostic results under complex operating conditions. In addition, existing photovoltaic fault diagnosis technologies are mostly geared towards faults in photovoltaic modules, arrays, DC cables, or inverters themselves, and cannot directly solve the problems of regional identification, branch location, and distance estimation of distribution network line faults after distributed photovoltaic access. Therefore, how to overcome the problems of insufficient observability caused by weak fault current characteristics, difficulty in locating complex feeder branches, and limited time synchronization accuracy of multiple measurement points under high-proportion distributed photovoltaic access conditions, and achieve reliable location of faulty branches and fault distances in distribution networks, is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method for fault location in distribution networks based on active perturbation topology fingerprinting of photovoltaic inverters, thereby resolving the issues present in the prior art.

[0005] Firstly, to achieve the above objectives, the present invention provides a method for fault location in distribution networks based on active perturbation topology fingerprinting of photovoltaic inverters, comprising the following steps: Acquire transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status to construct a time-varying state diagram of a high-proportion photovoltaic distribution network. The nodes of the time-varying state diagram include bus nodes, load nodes, photovoltaic access nodes, and measurement nodes. The edges of the time-varying state diagram include lines, switches, and equivalent impedance branches. The edge weights of the time-varying state diagram are determined by branch impedance, active power flow, branch length, and switch connectivity. The passive transient fault fingerprint is extracted based on the transient response at the time of the fault. The passive transient fault fingerprint is matched with the topological transient fingerprint database to obtain the passive diagnosis confidence. When the passive diagnosis confidence is lower than the preset threshold, the photovoltaic inverter perturbation detection is initiated. At least one photovoltaic inverter is selected from the candidate photovoltaic inverters as the active diagnostic excitation source. The selected inverter generates a perturbation signal, and the voltage and current responses at multiple measurement points are collected during the perturbation period to extract the active perturbation response fingerprint. When photovoltaic inverter perturbation detection is initiated, the passive transient fault fingerprint, active perturbation response fingerprint, photovoltaic inverter operating status and time-varying state diagram are fused into a joint fault fingerprint. When the photovoltaic inverter perturbation detection is not activated, the passive transient fault fingerprint, the photovoltaic inverter operating status and the time-varying state diagram are merged into a joint fault fingerprint. The joint fault fingerprint is matched with the topological transient fingerprint template of each candidate branch to obtain the comprehensive matching score of each candidate branch. A counterfactual transient response is generated based on each candidate branch and candidate fault distance. The joint fault fingerprint is compared with the counterfactual transient response to obtain the physical consistency residual. The final fault branch and final fault distance are determined based on the comprehensive matching score and the physical consistency residual, and the fault diagnosis result is output.

[0006] Secondly, the present invention also provides a distribution network fault location system based on photovoltaic inverter active perturbation topology fingerprinting, for implementing a distribution network fault location method based on photovoltaic inverter active perturbation topology fingerprinting, the system comprising: The state diagram construction module is used to acquire transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status to construct a time-varying state diagram of a high-proportion photovoltaic distribution network. The nodes of the time-varying state diagram include bus nodes, load nodes, photovoltaic access nodes, and measurement nodes. The edges of the time-varying state diagram include lines, switches, and equivalent impedance branches. The edge weights of the time-varying state diagram are determined by branch impedance, active power flow, branch length, and switch connectivity. The passive diagnosis and triggering module is used to extract passive transient fault fingerprints based on the transient response when a fault occurs, match the passive transient fault fingerprints with the topological transient fingerprint database to obtain the passive diagnosis confidence level, and start the photovoltaic inverter perturbation detection when the passive diagnosis confidence level is lower than a preset threshold. The perturbation excitation and active fingerprint extraction module is used to select at least one photovoltaic inverter from candidate photovoltaic inverters as an active diagnostic excitation source. The selected inverter generates a perturbation signal, and the voltage and current responses of multiple measurement points are collected during the perturbation period to extract the active perturbation response fingerprint. The joint fingerprint matching module is used to integrate passive transient fault fingerprints, active perturbation response fingerprints, photovoltaic inverter operating status and time-varying state diagrams into a joint fault fingerprint, and match the joint fault fingerprint with the topological transient fingerprint template of each candidate branch to obtain the comprehensive matching score of each candidate branch. The counterfact verification and location output module is used to generate counterfact transient responses based on each candidate branch and candidate fault distance, compare the joint fault fingerprint with the counterfact transient response to obtain the physical consistency residual, determine the final fault branch and the final fault distance based on the comprehensive matching score and the physical consistency residual, and output the fault diagnosis result.

[0007] Thirdly, the present invention also provides a computer terminal device, comprising: One or more processors; A memory, coupled to the processor, for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the steps of the distribution network fault location method based on photovoltaic inverter active perturbation topology fingerprint in the first aspect above.

[0008] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, it implements the steps of the distribution network fault location method based on photovoltaic inverter active perturbation topology fingerprint in the first aspect described above.

[0009] Fifthly, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the distribution network fault location method based on active perturbation topology fingerprinting of photovoltaic inverters in the first aspect described above.

[0010] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a method for fault location in distribution networks based on active perturbation topology fingerprinting using photovoltaic inverters. This method leverages the synergistic effects of photovoltaic inverter-coordinated perturbation, active-passive fault fingerprint fusion, topology fingerprint embedding, and counterfactual physical consistency verification to improve fault location accuracy in high-proportion photovoltaic distribution networks while effectively enhancing fault observability in scenarios with weak fault currents. This invention utilizes existing distributed photovoltaic inverters in the distribution network as controllable diagnostic excitation sources, eliminating the need for additional dedicated reflected signal injection equipment. It can acquire equivalent impedance changes, voltage response characteristics, and multi-measurement point propagation information after a fault under complex operating conditions such as low irradiance, high-resistance grounding, and implicit grounding. By embedding line topology, branch length, line impedance, measurement point location, switch status, and photovoltaic connection location into a topology transient fingerprint database, the stability and interpretability of fault branch identification in complex multi-branch feeders are improved. By employing a self-correction mechanism for measurement point time deviation and a counterfactual physical verification mechanism, the dependence of multi-measurement point transient positioning on strictly synchronized measurement equipment is reduced. Furthermore, candidate results that do not conform to the topology propagation law and branch boundary constraints can be eliminated, thereby improving the accuracy and engineering reliability of distribution network fault location under high-proportion photovoltaic access conditions. Attached Figure Description

[0011] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a general flowchart of an embodiment of the present invention. Detailed Implementation

[0012] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0013] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0014] This invention is applicable to medium and low voltage distribution networks with a high proportion of distributed photovoltaic access, and is particularly suitable for weak fault characteristic scenarios where the fault current amplitude is significantly reduced due to inverter current limiting control, low voltage ride-through strategy, irradiance fluctuations and load changes. It is also suitable for distribution network structures where fault branches are difficult to distinguish under complex multi-branch feeder structures, and for engineering application scenarios where it is difficult to achieve strict time synchronization between multiple measurement points. Specifically, it can be applied to single-phase grounding fault location, high-resistance grounding fault location and implicit grounding fault location under low irradiance conditions. It can also be applied to line fault area identification, fault branch location and fault distance estimation when the fault characteristics of the distribution network change after the photovoltaic inverter participates in current limiting.

[0015] Example 1 Figure 1 This is the overall flowchart of the present invention. After the process begins, the construction of the high-proportion photovoltaic distribution network state diagram and data acquisition are performed first; then, passive transient fault fingerprint extraction and confidence determination are performed to determine whether the confidence of passive diagnosis is insufficient; if the determination result is negative, the construction of distributed photovoltaic inverter collaborative perturbation and active response fingerprints is skipped, and the passive transient fault fingerprint, photovoltaic inverter operating state and time-varying state diagram are fused into a joint fault fingerprint; if the determination result is positive, the construction of distributed photovoltaic inverter collaborative perturbation and active response fingerprints is performed, and the passive transient fault fingerprint, active perturbation response fingerprint, photovoltaic inverter operating state and time-varying state diagram are fused into a joint fault fingerprint; then, the active and passive fault fingerprints are fused, and active-passive fault fingerprint fusion and topology fingerprint embedding matching are performed; finally, counterfactual physical consistency verification and location result output are performed, and the process ends.

[0016] Combined with flowchart Figure 1 This embodiment provides a method for fault location in distribution networks based on active perturbation topology fingerprinting of photovoltaic inverters, including: Acquire transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status to construct a time-varying state diagram of a high-proportion photovoltaic distribution network. The nodes of the time-varying state diagram include bus nodes, load nodes, photovoltaic access nodes, and measurement nodes. The edges of the time-varying state diagram include lines, switches, and equivalent impedance branches. The edge weights of the time-varying state diagram are determined by branch impedance, active power flow, branch length, and switch connectivity. The passive transient fault fingerprint is extracted based on the transient response at the time of the fault. The passive transient fault fingerprint is matched with the topological transient fingerprint database to obtain the passive diagnosis confidence. When the passive diagnosis confidence is lower than the preset threshold, the photovoltaic inverter perturbation detection is initiated. At least one photovoltaic inverter is selected from the candidate photovoltaic inverters as the active diagnostic excitation source. The selected inverter generates a perturbation signal, and the voltage and current responses at multiple measurement points are collected during the perturbation period to extract the active perturbation response fingerprint. When photovoltaic inverter perturbation detection is initiated, the passive transient fault fingerprint, active perturbation response fingerprint, photovoltaic inverter operating status and time-varying state diagram are fused into a joint fault fingerprint. When the photovoltaic inverter perturbation detection is not activated, the passive transient fault fingerprint, the photovoltaic inverter operating status and the time-varying state diagram are merged into a joint fault fingerprint. The joint fault fingerprint is matched with the topological transient fingerprint template of each candidate branch to obtain the comprehensive matching score of each candidate branch. A counterfactual transient response is generated based on each candidate branch and candidate fault distance. The joint fault fingerprint is compared with the counterfactual transient response to obtain the physical consistency residual. The final fault branch and final fault distance are determined based on the comprehensive matching score and the physical consistency residual, and the fault diagnosis result is output.

[0017] The specific details of the above-mentioned end-to-end solution include: First, acquire transient measurement data from multiple measurement points, line topology parameters, and photovoltaic inverter operating status to construct a high-proportion photovoltaic distribution network status diagram. Secondly, passive transient fault fingerprints are extracted based on the natural transient response of the fault, and the confidence level of passive diagnosis is calculated. Then, when the confidence level of passive diagnosis is insufficient, the distributed photovoltaic inverter is scheduled to generate a low-amplitude perturbation signal that meets the grid connection security constraints, and an active perturbation response fingerprint is constructed. Furthermore, the active perturbation response fingerprint, passive transient fault fingerprint, inverter operating status and topology constraint information are fused and matched with the topology transient fingerprint database; Finally, through self-correction of measurement point time deviation and counterfactual physical consistency verification, the candidate fault branches and fault distances are corrected, and the fault type, fault area, fault branch, fault distance, inverter current limiting contribution, and fault handling suggestions are output.

[0018] The complete process described above is estimated to include a total of 5 steps: Step 1: Construction and data acquisition of a high-proportion photovoltaic distribution network status diagram; Step 2: Passive transient fault fingerprint extraction and perturbation trigger determination; Step 3: Construction of collaborative perturbation and active response fingerprints for distributed photovoltaic inverters; Step 4: Active-passive joint fault fingerprint fusion and matching with the topological transient fingerprint database; Step 5: Counterfactual physical verification and hierarchical diagnostic output.

[0019] As one implementation method in this embodiment, the process of acquiring transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status, and constructing a time-varying state diagram of a high-proportion photovoltaic distribution network includes: The voltage and current measurement information of each node is obtained to form a node measurement feature matrix; The photovoltaic inverter operating status matrix is ​​composed of the active power output, reactive power output, current limiting status, low voltage ride-through status, and control mode of each access node. Busbar nodes, load nodes, photovoltaic access nodes, and measurement nodes are used as nodes in the time-varying state diagram, and lines, switches, and equivalent impedance branches are used as edges in the time-varying state diagram. The edge weights between nodes are determined based on the switch connection state, branch impedance, active power flow, and branch length. The edge weights are positively correlated with the switch connection state, the reciprocal of the branch impedance, the active power flow amplitude, and the reciprocal of the branch length.

[0020] Step 1: The process of constructing and acquiring data for the state diagram of a high-proportion photovoltaic distribution network specifically includes: Operational data is acquired using synchronous phasor measurement units, fault recording devices, feeder terminals, distribution automation terminals, photovoltaic inverter controllers, switch status acquisition devices, and distribution master station systems. ,in, For a moment The acquired set of power distribution network operation data. The node measurement information and inverter operating status are characterized. For nodes... Construct node measurement feature vectors ,in, For nodes The measurement feature vectors of all nodes; the node measurement feature matrix is ​​composed of the measurement feature vectors of all nodes. Then, the active power output, reactive power output, current limiting state, low voltage ride-through state, and control mode of photovoltaic inverters are used as operating characteristics. ,in, For access nodes The photovoltaic inverter operating state vector is composed of each Composition of distributed photovoltaic inverter operating state matrix To describe the distribution network topology, measurement status, and photovoltaic inverter operating status, bus nodes, load nodes, photovoltaic access nodes, and measurement nodes are used as graph nodes, and lines, switches, and equivalent impedance branches are used as graph edges, thus constructing a time-varying state diagram of a high-proportion photovoltaic distribution network: in, For a set of nodes, Let be a time-varying edge set. Let be the edge weight matrix. For the node measurement feature matrix, This is the operating status matrix for distributed photovoltaic inverters.

[0021] To characterize the impact of line physical parameters, power flow direction, branch length, and switch status on fault propagation paths, nodes are defined. With nodes The edge weights between them are: in, For nodes With nodes The branch impedance between , and These are the reference values ​​for impedance, power, and length, respectively. For the length of the branch road, The switch is in the connected state. These are the weighting coefficients. It is a very small positive number.

[0022] As one implementation method in this embodiment, the process of extracting a passive transient fault fingerprint based on the transient response at the time of the fault, matching the passive transient fault fingerprint with a topological transient fingerprint database to obtain a passive diagnostic confidence level, and initiating photovoltaic inverter perturbation detection when the passive diagnostic confidence level is lower than a preset threshold includes: When voltage sag, zero-sequence component abnormality, negative-sequence component abnormality, transient change abnormality, inverter current limiting action or protection alarm are detected, the transient waveforms of multiple measurement points within the time window before and after the fault are captured. The transient waveform is subjected to high-frequency filtering, envelope extraction, abrupt change detection and multi-measurement wavefront identification. The high-frequency transient energy, wavefront arrival time, multi-measurement arrival time difference, zero-sequence component, negative-sequence component, transient attenuation rate and wavefront arrival sequence code are extracted to form a passive transient fault fingerprint. The passive diagnostic confidence is obtained by initially matching the passive transient fault fingerprint with the topological transient fingerprint database. When the confidence level of passive diagnosis is lower than the preset threshold, the perturbation trigger flag is set to the enabled state.

[0023] Step 2: The process of passive transient fault fingerprint extraction and perturbation trigger determination specifically includes: When voltage sags, zero-sequence component anomalies, negative-sequence component anomalies, transient surge anomalies, inverter current limiting actions, or protection alarms are detected, transient waveforms at multiple measurement points within the time window before and after the fault are captured. Through high-frequency filtering, envelope extraction, abrupt change detection, and multi-measurement point wavefront identification, high-frequency transient energy, wavefront arrival time, multi-measurement point arrival time difference, zero-sequence component, negative-sequence component, transient attenuation rate, and wavefront arrival sequence encoding are extracted to form a passive transient fault fingerprint. in, It is high-frequency transient energy. Let the wavefront arrival time vectors be the vectors for each measuring point. For the time difference of arrival matrix of multiple measurement points, It is the zero-sequence current component. It is a negative sequence current component. The transient decay rate, Encode the arrival order of wavefronts.

[0024] Based on passive transient fault fingerprint A preliminary match was performed with the topological transient fingerprint database to obtain the passive diagnostic confidence level. When the confidence level is insufficient, it indicates that relying solely on the natural transient response of the fault is insufficient to reliably distinguish candidate fault branches. Therefore, it is necessary to initiate distributed photovoltaic inverter-coordinated perturbation detection. The perturbation trigger function is: in, To preset the reliability threshold, =1 indicates that distributed photovoltaic inverter collaborative perturbation detection is initiated. =0 indicates that the passive transient fault fingerprint has met the requirements for subsequent topology matching and physical verification.

[0025] As one implementation method in this embodiment, the process of selecting at least one inverter from candidate photovoltaic inverters as an active diagnostic excitation source, the selected inverter generating a perturbation signal, acquiring the voltage and current responses at multiple measurement points during the perturbation, and extracting the active perturbation response fingerprint includes: Inverters are selected from the candidate photovoltaic inverter set based on candidate branch response discrimination, measurement observability gain, voltage over-limit risk, and inverter control cost. The selected inverter generates low-amplitude, short-duration, multi-frequency perturbation signals; The voltage and current responses at multiple measurement points were acquired during the perturbation. The active perturbation response fingerprint is formed by extracting the equivalent impedance change matrix, equivalent admittance change matrix, voltage response amplitude matrix, current response amplitude matrix, multi-point response correlation coefficient, and inverter-to-measurement point response sensitivity matrix before and after the perturbation.

[0026] Step 3: The process of constructing the collaborative perturbation and active response fingerprint for distributed photovoltaic inverters specifically includes: When the perturbation trigger flag When =1, at least one photovoltaic inverter is selected from the candidate photovoltaic inverter set as the active diagnostic excitation source. The inverter selection process comprehensively considers the candidate branch response distinguishability, measurement observability gain, node voltage safety risk, and control cost to ensure that the perturbation signal can enhance fault observability without affecting the safe operation of the distribution network. The inverter selection objective is: in, For the selected set of photovoltaic inverters, A collection of candidate photovoltaic inverters. To differentiate the responses of candidate faulty branches, To measure the observability gain, To mitigate the risk of voltage or current exceeding limits due to perturbations. The cost of inverter control, These are the corresponding weighting coefficients.

[0027] The selected photovoltaic inverter generates low-amplitude, short-duration, multi-frequency perturbation signals that meet grid connection safety constraints. During the perturbation period, voltage and current responses at multiple measurement points are collected, and the equivalent impedance change, equivalent admittance change, voltage response amplitude, current response amplitude, response correlation coefficient, and inverter-measurement point sensitivity are extracted to form an active perturbation response fingerprint. in, This is the equivalent impedance change matrix before and after the perturbation. The equivalent admittance change matrix, The voltage response amplitude matrix, This is the current response amplitude matrix. The correlation coefficient is the response correlation coefficient at multiple measurement points. This is the response sensitivity matrix from the photovoltaic inverter to the measurement point.

[0028] As one implementation method in this embodiment, the process of fusing the passive transient fault fingerprint, the active perturbation response fingerprint, the photovoltaic inverter operating state, and the time-varying state diagram into a joint fault fingerprint, and matching the joint fault fingerprint with the topological transient fingerprint template of each candidate branch to obtain the comprehensive matching score of each candidate branch includes: When the perturbation trigger flag is in the enabled state, the passive transient fault fingerprint and the active perturbation response fingerprint are fused together. When the perturbation trigger flag is in the inactive state, the passive transient fault fingerprint, photovoltaic inverter operating status and time-varying state diagram are fused together. For each candidate branch, a topological transient fingerprint template is constructed based on the line topology, branch length, line impedance, switch status, measurement point location, traveling wave propagation characteristics, and photovoltaic inverter access location. The joint fault fingerprint is matched with the topological transient fingerprint templates of each candidate branch. The comprehensive matching score is calculated based on the wavefront arrival time-series matching degree, impedance response matching degree, inverter perturbation response matching degree, topological connectivity consistency matching degree, and time-series consistency matching degree after measurement point time deviation correction. When the perturbation trigger flag is in the inactive state, the photovoltaic inverter perturbation response matching degree is not calculated, or the weight of the photovoltaic inverter perturbation response matching item is set to zero.

[0029] Step 4: The process of active-passive joint fault fingerprint fusion and topological transient fingerprint database matching specifically includes: Passive transient fault fingerprint Active perturbation response fingerprint Operating status of distributed photovoltaic inverters Time-varying state diagram of high-proportion photovoltaic distribution network By fusing the fingerprints, an active-passive joint fault fingerprint is obtained: in, For active-passive joint fault fingerprinting, For feature fusion function, This is the perturbation trigger flag. When At that time, active perturbation response fingerprints participate in fusion; when At that time, matching is mainly based on passive transient fault fingerprints and topological constraint information.

[0030] For candidate branches Based on the line topology, branch length, line impedance, switch status, measurement point location, traveling wave propagation characteristics, and photovoltaic inverter connection location, a topological transient fingerprint template is constructed: in, Candidate branch Topological transient fingerprint template, Theoretical wavefront arrival time characteristics, Branch impedance characteristics, For reflection and propagation path characteristics, It exhibits transient decay characteristics. This is a perturbation response template for photovoltaic inverters.

[0031] Combined fault fingerprints The candidate branches are matched with their topological transient fingerprint templates to calculate the comprehensive matching score. in, Candidate branch The overall matching score, For wavefront arrival timing matching degree, For impedance response matching degree, For inverter perturbation response matching degree, For topological connectivity consistency matching degree, The timing consistency matching degree after correction for measurement point time deviation. These are the corresponding weighting coefficients.

[0032] As one implementation method in this embodiment, the process of generating a counterfactual transient response based on each candidate branch and candidate fault distance, comparing the joint fault fingerprint with the counterfactual transient response to obtain a physical consistency residual, determining the final fault branch and final fault distance based on the comprehensive matching score and the physical consistency residual, and outputting the fault diagnosis result includes: For each candidate branch and candidate fault distance, counterfactual transient responses under each candidate assumption are generated based on line impedance parameters, branch length parameters, transient propagation speed, photovoltaic inverter operating status, and time-varying state diagram. The joint fault fingerprint is compared with the counterfactual transient response, and the physical consistency residual is calculated based on the difference between the joint fault fingerprint and the counterfactual transient response, the branch boundary constraint error, and the line length constraint error. The final fault branch and final fault distance are determined based on the physical consistency residual and the comprehensive matching score. When the physical consistency residuals of all candidate results fail to meet the physical consistency requirements, they are judged as double faults, compound faults, or measurement anomalies and the verification mechanism is triggered. The output includes fault diagnosis results such as fault type, fault area, final fault branch, final fault distance, fault resistance, fault current, set of photovoltaic inverters involved in current limiting, and the current limiting contribution of each inverter.

[0033] Step 5: The process of verifying counterfactual physical consistency and outputting the location results specifically includes: Let there be a set of candidate fault hypotheses. Candidate branches in and fault distance By combining line impedance, branch length, transient propagation speed, photovoltaic inverter operating status, and time-varying state diagram, the counterfactual transient response under the corresponding fault assumption is generated: in, Candidate branch At fault distance The counterfactual transient response when a fault occurs at a certain point. The physical response function is constructed based on topology propagation laws and line parameters. These are the line impedance parameters. For branch length parameters, This refers to the transient propagation speed.

[0034] The measured active-passive combined fault fingerprint Counterfactual transient response Compare and calculate the physical consistency residuals of the candidate failure assumptions: in, For counterfactual physical consistency residuals, For branch boundary constraint error, For line length constraint error, This represents the corresponding penalty coefficient.

[0035] Overall candidate branch matching score and counterfactual physical consistency residuals Determine the final faulty branch and the fault distance: in, For the final faulty branch, The final fault distance, To match the score weighting coefficients. If none of the candidate results meet the physical consistency requirements, it is determined that there may be a hidden double fault, a compound fault, or a measurement anomaly, and the review mechanism is triggered.

[0036] Final output of fault diagnosis results Y : exist middle, Fault type The fault area The fault resistor, For fault current, For the collection of photovoltaic inverters participating in current limiting, Contribution to inverter current limiting To determine the overall diagnostic confidence level. Based on... The system generates fault handling recommendations, including priority disconnect switches, backup disconnect switches, affected photovoltaic access nodes, inverter derating strategies, reactive power support strategies, and reclosing lockout recommendations.

[0037] Based on this, this invention provides a distribution network fault location method based on active perturbation topological fingerprinting of photovoltaic inverters. This invention, through the synergistic effects of photovoltaic inverter-coordinated perturbation, active-passive fault fingerprint fusion, topological fingerprint embedding, and counterfactual physical consistency verification, improves the fault location accuracy of high-proportion photovoltaic distribution network lines while effectively enhancing fault observability in weak fault current scenarios. Compared to traditional fault diagnosis methods that rely on fault current amplitude, steady-state impedance, or a single transient wavefront, this invention utilizes existing distributed photovoltaic inverters in the distribution network as a controllable diagnostic excitation source. Without the need for additional dedicated reflected signal injection equipment, it can obtain equivalent impedance changes, voltage response characteristics, and multi-point propagation information after a fault under complex operating conditions such as low irradiance, high-resistance grounding, and implicit grounding. By embedding line topology, branch length, line impedance, measurement point location, switch status, and photovoltaic (PV) access location into a topology transient fingerprint database, this invention improves the stability and interpretability of fault branch identification in complex multi-branch feeders. Through a measurement point time deviation self-correction and counterfactual physics verification mechanism, it reduces the dependence of multi-measurement point transient localization on strictly synchronized measurement equipment and eliminates candidate results that do not conform to topology propagation laws and branch boundary constraints. Therefore, this invention not only improves the accuracy and engineering reliability of distribution network fault location under high-proportion PV access conditions but also outputs fault type, fault area, fault branch, fault distance, inverter current limiting contribution, and fault handling suggestions, providing reliable technical support for distribution network fault isolation, operation and maintenance, and safety control in scenarios involving renewable energy consumption.

[0038] Example 2 In this embodiment, a computer terminal device is provided, including: One or more processors; A memory, coupled to the processor, for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the steps of the above-described method for fault location in distribution networks based on active perturbation topology fingerprinting of photovoltaic inverters.

[0039] In this embodiment, a computer-readable storage medium is also provided, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the above-described method for fault location in a distribution network based on the active perturbation topology fingerprint of a photovoltaic inverter.

[0040] In this embodiment, an electronic device is also provided, including a memory and a processor. The memory stores a computer program, and the processor is configured to run the computer program to perform the steps of the above-described method for fault location in a distribution network based on the active perturbation topology fingerprint of a photovoltaic inverter.

[0041] In this embodiment, a computer program product is also provided, including a computer program that, when executed by a processor, implements the steps of the above-described method for fault location in a distribution network based on the active perturbation topology fingerprint of a photovoltaic inverter.

[0042] The aforementioned program can run on a processor or be stored in memory (or a computer-readable medium). Computer-readable media includes both permanent and non-permanent, removable and non-removable media, and information storage can be achieved by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random-access memory (SRAM), dynamic random-access memory (DRAM), other types of random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transfer medium that can be used to store information accessible by a computing device.

[0043] These computer programs may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes can be implemented by different modules for different steps.

[0044] This embodiment provides such a device or system. The system, referred to as a distribution network fault location system based on photovoltaic inverter active perturbation topology fingerprinting, includes: The state diagram construction module is used to acquire transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status to construct a time-varying state diagram of a high-proportion photovoltaic distribution network. The nodes of the time-varying state diagram include bus nodes, load nodes, photovoltaic access nodes, and measurement nodes. The edges of the time-varying state diagram include lines, switches, and equivalent impedance branches. The edge weights of the time-varying state diagram are determined by branch impedance, active power flow, branch length, and switch connectivity. The passive diagnosis and triggering module is used to extract passive transient fault fingerprints based on the transient response when a fault occurs, match the passive transient fault fingerprints with the topological transient fingerprint database to obtain the passive diagnosis confidence level, and start the photovoltaic inverter perturbation detection when the passive diagnosis confidence level is lower than a preset threshold. The perturbation excitation and active fingerprint extraction module is used to select at least one inverter from the candidate photovoltaic inverters as the active diagnostic excitation source. The selected inverter generates a perturbation signal, and the voltage and current responses of multiple measurement points are collected during the perturbation period to extract the active perturbation response fingerprint. The joint fingerprint matching module is used to integrate passive transient fault fingerprints, active perturbation response fingerprints, photovoltaic inverter operating status and time-varying state diagrams into a joint fault fingerprint, and match the joint fault fingerprint with the topological transient fingerprint template of each candidate branch to obtain the comprehensive matching score of each candidate branch. The counterfact verification and location output module is used to generate counterfact transient responses based on each candidate branch and candidate fault distance, compare the joint fault fingerprint with the counterfact transient response to obtain the physical consistency residual, determine the final fault branch and the final fault distance based on the comprehensive matching score and the physical consistency residual, and output the fault diagnosis result.

[0045] As one implementation method in this embodiment, the state diagram construction module includes: The data acquisition unit is used to acquire voltage and current measurement information of each node, as well as the active power output, reactive power output, current limiting status, low voltage ride-through status and control mode of the photovoltaic inverter of each access node. The feature matrix construction unit is used to form a node measurement feature matrix from the measurement information of each node and to form a photovoltaic inverter operating status matrix from the photovoltaic inverter operating status information of each access node. The graph structure building unit is used to use bus nodes, load nodes, photovoltaic access nodes and measurement nodes as nodes of the time-varying state diagram, and lines, switches and equivalent impedance branches as edges of the time-varying state diagram. The edge weight calculation unit is used to determine the edge weight elements between nodes based on the switch connection state, branch impedance, active power flow, and branch length. The edge weight elements are positively correlated with the switch connection state, the reciprocal of the branch impedance, the active power flow amplitude, and the reciprocal of the branch length.

[0046] As one implementation method in this embodiment, the passive diagnosis and triggering module includes: The monitoring trigger unit is used to monitor voltage sag, zero-sequence component abnormality, negative-sequence component abnormality, transient change abnormality, inverter current limiting action and protection alarm. When any event is detected, it captures the transient waveforms of multiple measurement points within the time window before and after the fault. The waveform processing unit is used to perform high-frequency filtering, envelope extraction, abrupt change detection, and multi-point wavefront identification on transient waveforms. The fingerprint extraction unit is used to extract high-frequency transient energy, wavefront arrival time, multi-point arrival time difference, zero-sequence component, negative-sequence component, transient attenuation rate and wavefront arrival sequence code from the processed waveform to form a passive transient fault fingerprint. The confidence level determination unit is used to perform a preliminary match between the passive transient fault fingerprint and the topological transient fingerprint database to obtain the passive diagnosis confidence level. When the passive diagnosis confidence level is lower than a preset threshold, the perturbation trigger flag is set to the start state.

[0047] As one implementation method in this embodiment, the perturbation excitation and active fingerprint extraction module includes: The inverter selection unit is used to select an inverter from a set of candidate photovoltaic inverters based on candidate branch response discrimination, measurement observability gain, voltage over-limit risk, and inverter control cost. The perturbation signal generation unit is used to control the selected inverter to generate low-amplitude, short-time, multi-frequency perturbation signals; The response acquisition unit is used to acquire voltage and current responses at multiple measurement points during perturbation. The active fingerprint construction unit is used to extract the equivalent impedance change matrix, equivalent admittance change matrix, voltage response amplitude matrix, current response amplitude matrix, multi-measurement point response correlation coefficient, and inverter-to-measurement point response sensitivity matrix before and after the perturbation, forming an active perturbation response fingerprint.

[0048] As one implementation method in this embodiment, the joint fingerprint matching module includes: The fusion processing unit is used to fuse the passive transient fault fingerprint and the active perturbation response fingerprint when the perturbation trigger flag is in the start state, and to fuse the passive transient fault fingerprint, the photovoltaic inverter operating state and the time-varying state diagram when the perturbation trigger flag is in the non-start state. The fingerprint template construction unit is used to construct a topological transient fingerprint template for each candidate branch based on the line topology, branch length, line impedance, switch status, measurement point location, traveling wave propagation characteristics, and photovoltaic inverter access location. The matching score calculation unit is used to match the joint fault fingerprint with the topological transient fingerprint template of each candidate branch, and calculate the comprehensive matching score based on the wavefront arrival timing matching degree, impedance response matching degree, inverter perturbation response matching degree, topological connectivity consistency matching degree, and timing consistency matching degree after measurement point time deviation correction.

[0049] As one implementation method in this embodiment, the counterfactual verification and location output module includes: The counterfactual response generation unit is used to generate counterfactual transient responses under each candidate assumption for each candidate branch and candidate fault distance, based on line impedance parameters, branch length parameters, transient propagation speed, photovoltaic inverter operating status and time-varying state diagram. The residual calculation unit is used to compare the joint fault fingerprint with the counterfactual transient response and calculate the physical consistency residual based on the difference between the joint fault fingerprint and the counterfactual transient response, the branch boundary constraint error and the line length constraint error. The fault determination unit is used to determine the final fault branch and the final fault distance based on the physical consistency residual and the comprehensive matching score. The anomaly determination unit is used to determine a double fault, a compound fault, or a measurement anomaly and trigger a verification mechanism when the physical consistency residuals of all candidate results do not meet the physical consistency requirements. The result output unit is used to output fault diagnosis results including fault type, fault area, final fault branch, final fault distance, fault resistance, fault current, set of photovoltaic inverters participating in current limiting, and inverter current limiting contribution.

[0050] The system or apparatus is used to implement the functions of the methods in the above embodiments. Each module in the system or apparatus corresponds to each step in the method, as has been described in the method and will not be repeated here.

[0051] The above implementation method solves the problem of distribution network fault location based on photovoltaic inverter active perturbation topology fingerprint in related technologies, thereby ensuring that the problems existing in the prior art are resolved.

[0052] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fault location in distribution networks based on active perturbation topology fingerprinting of photovoltaic inverters, characterized in that, Includes the following steps: Acquire transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status to construct a time-varying state diagram of a high-proportion photovoltaic distribution network. The nodes of the time-varying state diagram include bus nodes, load nodes, photovoltaic access nodes, and measurement nodes. The edges of the time-varying state diagram include lines, switches, and equivalent impedance branches. The edge weights of the time-varying state diagram are determined by branch impedance, active power flow, branch length, and switch connectivity. The passive transient fault fingerprint is extracted based on the transient response at the time of the fault. The passive transient fault fingerprint is matched with the topological transient fingerprint database to obtain the passive diagnosis confidence. When the passive diagnosis confidence is lower than the preset threshold, the photovoltaic inverter perturbation detection is initiated. At least one inverter is selected from the candidate photovoltaic inverters as the active diagnostic excitation source. The selected inverter generates a perturbation signal, and the voltage and current responses at multiple measurement points are collected during the perturbation period to extract the active perturbation response fingerprint. When photovoltaic inverter perturbation detection is initiated, the passive transient fault fingerprint, active perturbation response fingerprint, photovoltaic inverter operating status and time-varying state diagram are fused into a joint fault fingerprint. When the photovoltaic inverter perturbation detection is not activated, the passive transient fault fingerprint, the photovoltaic inverter operating status and the time-varying state diagram are merged into a joint fault fingerprint. The joint fault fingerprint is matched with the topological transient fingerprint template of each candidate branch to obtain the comprehensive matching score of each candidate branch. A counterfactual transient response is generated based on each candidate branch and candidate fault distance. The joint fault fingerprint is compared with the counterfactual transient response to obtain the physical consistency residual. The final fault branch and final fault distance are determined based on the comprehensive matching score and the physical consistency residual, and the fault diagnosis result is output.

2. The method according to claim 1, characterized in that, The process of acquiring transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status, and constructing a time-varying state diagram of a high-proportion photovoltaic distribution network includes: The voltage and current measurement information of each node is obtained to form a node measurement feature matrix; The photovoltaic inverter operating status matrix is ​​composed of the active power output, reactive power output, current limiting status, low voltage ride-through status, and control mode of each access node. Busbar nodes, load nodes, photovoltaic access nodes, and measurement nodes are used as nodes in the time-varying state diagram, and lines, switches, and equivalent impedance branches are used as edges in the time-varying state diagram. The edge weights between nodes are determined based on the switch connection state, branch impedance, active power flow, and branch length. The edge weights are positively correlated with the switch connection state, the reciprocal of the branch impedance, the active power flow amplitude, and the reciprocal of the branch length.

3. The method according to claim 1, characterized in that, The process of extracting a passive transient fault fingerprint based on the transient response at the time of the fault, matching the passive transient fault fingerprint with a topological transient fingerprint database to obtain a passive diagnostic confidence level, and initiating photovoltaic inverter perturbation detection when the passive diagnostic confidence level is lower than a preset threshold includes: When voltage sag, zero-sequence component abnormality, negative-sequence component abnormality, transient change abnormality, inverter current limiting action or protection alarm are detected, the transient waveforms of multiple measurement points within the time window before and after the fault are captured. The transient waveform is subjected to high-frequency filtering, envelope extraction, abrupt change detection and multi-measurement wavefront identification. The high-frequency transient energy, wavefront arrival time, multi-measurement arrival time difference, zero-sequence component, negative-sequence component, transient attenuation rate and wavefront arrival sequence code are extracted to form a passive transient fault fingerprint. The passive diagnostic confidence is obtained by initially matching the passive transient fault fingerprint with the topological transient fingerprint database. When the confidence level of passive diagnosis is lower than the preset threshold, the perturbation trigger flag is set to the enabled state.

4. The method according to claim 1, characterized in that, The process of selecting at least one photovoltaic inverter from candidate photovoltaic inverters as the active diagnostic excitation source, the selected inverter generating a perturbation signal, acquiring the voltage and current responses at multiple measurement points during the perturbation period, and extracting the active perturbation response fingerprint includes: Inverters are selected from the candidate photovoltaic inverter set based on candidate branch response discrimination, measurement observability gain, voltage over-limit risk, and inverter control cost. The selected inverter generates low-amplitude, short-duration, multi-frequency perturbation signals; The voltage and current responses at multiple measurement points were acquired during the perturbation. The active perturbation response fingerprint is formed by extracting the equivalent impedance change matrix, equivalent admittance change matrix, voltage response amplitude matrix, current response amplitude matrix, multi-point response correlation coefficient, and inverter-to-measurement point response sensitivity matrix before and after the perturbation.

5. The method according to claim 1, characterized in that, The process of fusing passive transient fault fingerprints, active perturbation response fingerprints, photovoltaic inverter operating status, and time-varying state diagrams into a joint fault fingerprint, and matching the joint fault fingerprint with the topological transient fingerprint templates of each candidate branch to obtain the comprehensive matching score of each candidate branch includes: When the perturbation trigger flag is in the enabled state, the passive transient fault fingerprint and the active perturbation response fingerprint are fused together. When the perturbation trigger flag is in the inactive state, the passive transient fault fingerprint, photovoltaic inverter operating status and time-varying state diagram are fused together. For each candidate branch, a topological transient fingerprint template is constructed based on the line topology, branch length, line impedance, switch status, measurement point location, traveling wave propagation characteristics, and photovoltaic inverter access location. The joint fault fingerprint is matched with the topological transient fingerprint template of each candidate branch, and the comprehensive matching score is calculated based on the wavefront arrival timing matching degree, impedance response matching degree, inverter perturbation response matching degree, topological connectivity consistency matching degree, and timing consistency matching degree after measurement point time deviation correction.

6. The method according to claim 1, characterized in that, The process of generating a counterfactual transient response based on each candidate branch and candidate fault distance, comparing the joint fault fingerprint with the counterfactual transient response to obtain a physical consistency residual, determining the final fault branch and final fault distance based on the comprehensive matching score and the physical consistency residual, and outputting the fault diagnosis result includes: For each candidate branch and candidate fault distance, counterfactual transient responses under each candidate assumption are generated based on line impedance parameters, branch length parameters, transient propagation speed, photovoltaic inverter operating status, and time-varying state diagram. The joint fault fingerprint is compared with the counterfactual transient response, and the physical consistency residual is calculated based on the difference between the joint fault fingerprint and the counterfactual transient response, the branch boundary constraint error, and the line length constraint error. The final fault branch and final fault distance are determined based on the physical consistency residual and the comprehensive matching score. When the physical consistency residuals of all candidate results fail to meet the physical consistency requirements, they are judged as double faults, compound faults, or measurement anomalies and the verification mechanism is triggered. The output includes fault diagnosis results such as fault type, fault area, final fault branch, final fault distance, fault resistance, fault current, set of photovoltaic inverters involved in current limiting, and the current limiting contribution of each inverter.

7. A distribution network fault location system based on active perturbation topology fingerprinting of photovoltaic inverters, characterized in that, The system for implementing the method of any one of claims 1-6 comprises: The state diagram construction module is used to acquire transient measurement data from multiple measurement points in the distribution network, line topology parameters, and photovoltaic inverter operating status to construct a time-varying state diagram of a high-proportion photovoltaic distribution network. The nodes of the time-varying state diagram include bus nodes, load nodes, photovoltaic access nodes, and measurement nodes. The edges of the time-varying state diagram include lines, switches, and equivalent impedance branches. The edge weights of the time-varying state diagram are determined by branch impedance, active power flow, branch length, and switch connectivity. The passive diagnosis and triggering module is used to extract passive transient fault fingerprints based on the transient response when a fault occurs, match the passive transient fault fingerprints with the topological transient fingerprint database to obtain the passive diagnosis confidence level, and start the photovoltaic inverter perturbation detection when the passive diagnosis confidence level is lower than a preset threshold. The perturbation excitation and active fingerprint extraction module is used to select at least one photovoltaic inverter from candidate photovoltaic inverters as an active diagnostic excitation source. The selected inverter generates a perturbation signal, and the voltage and current responses of multiple measurement points are collected during the perturbation period to extract the active perturbation response fingerprint. The joint fingerprint matching module is used to integrate passive transient fault fingerprints, active perturbation response fingerprints, photovoltaic inverter operating status and time-varying state diagrams into a joint fault fingerprint, and match the joint fault fingerprint with the topological transient fingerprint template of each candidate branch to obtain the comprehensive matching score of each candidate branch. The counterfact verification and location output module is used to generate counterfact transient responses based on each candidate branch and candidate fault distance, compare the joint fault fingerprint with the counterfact transient response to obtain the physical consistency residual, determine the final fault branch and the final fault distance based on the comprehensive matching score and the physical consistency residual, and output the fault diagnosis result.

8. A computer terminal device, characterized in that, include: One or more processors; A memory, coupled to the processor, for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors perform the steps of the method as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-6.

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