A power distribution box abnormal working condition adaptive protection method and system

Abstract

This invention discloses an adaptive protection method and system for abnormal operating conditions of distribution boxes, relating to the field of abnormal protection technology for distribution boxes. The method includes: acquiring fault synchronization signals, modulating and filtering the analog voltage signal to reconstruct the effective value of the residual current; constructing positive-sequence and negative-sequence synchronous coordinate systems to determine voltage sags and three-phase imbalances; locating the faulty branch based on the branch voltage pulse signal, the effective value of the residual current, the instantaneous voltage amplitude, and the voltage transient flag; and generating differentiated protection commands for the faulty branch to execute adaptive protection management under abnormal operating conditions. This invention solves the technical problems of incomplete fault type identification, low fault branch location accuracy, and uniform and coarse protection strategies in existing distribution boxes, making it difficult to achieve hierarchical and differentiated handling. It achieves the technical effect of accurate location and differentiated adaptive protection for multiple types of faults in distribution boxes, improving the efficiency of power distribution safety management.

Description

Technical Field

[0001] This invention relates to the field of abnormal protection technology for distribution boxes, and specifically to an adaptive protection method and system for abnormal operating conditions of distribution boxes. Background Technology

[0002] Currently, most existing distribution box protection technologies adopt a unified overcurrent and leakage protection mode, with limited fault identification methods. This makes it difficult to accurately distinguish between different abnormal operating conditions such as three-phase imbalance, short circuit, and insulation leakage, and it is impossible to accurately locate faulty branches. The protection strategies are general and crude, lacking targeted hierarchical handling methods. At the same time, fault data is not effectively used for risk prediction and optimization, resulting in delayed fault handling and low safety management efficiency in the power distribution system, which is difficult to meet the needs of modern power distribution networks for refined and adaptive safety protection.

[0003] Existing technologies for distribution boxes suffer from incomplete fault type identification, low fault branch location accuracy, and uniform and crude protection strategies, making it difficult to achieve differentiated and tiered handling. Summary of the Invention

[0004] This application provides an adaptive protection method and system for abnormal operating conditions of distribution boxes, which addresses the technical problems of incomplete fault type identification, low fault branch location accuracy, uniform and crude protection strategies, and difficulty in achieving hierarchical and differentiated handling in existing distribution boxes.

[0005] In view of the above problems, this application provides an adaptive protection method and system for abnormal operating conditions of distribution boxes.

[0006] A first aspect of this application provides an adaptive protection method for abnormal operating conditions of a distribution box, the method comprising: By acquiring fault synchronization signals, branch voltage pulse signals and analog voltage signals are obtained. The analog voltage signals are modulated and filtered for reconstruction, and the effective value of the residual current is calculated. Single-phase voltage signals are acquired from the bus through voltage transformers, and two-way orthogonal integration is performed through a second-order generalized integrator to construct positive-sequence and negative-sequence synchronous coordinate systems. The positive-sequence and negative-sequence components are extracted by low-pass filtering, and voltage sag and three-phase imbalance are judged to obtain the instantaneous voltage amplitude and voltage transient status. Based on the branch voltage pulse signals, the effective value of the residual current, the instantaneous voltage amplitude, and the voltage transient status, the faulty branch is located. Each faulty branch is identified by a fault type, including three-phase imbalance source branches, short-circuit fault branches, and insulation leakage branches. For the faulty branches, differentiated protection commands are generated, and adaptive protection management for abnormal operating conditions is executed.

[0007] A second aspect of this application provides an adaptive protection system for abnormal operating conditions of a distribution box, the system comprising: The residual current RMS value calculation module is used to acquire branch voltage pulse signals and analog voltage signals through fault synchronization signal acquisition, and to calculate the residual current RMS value by modulating and filtering the analog voltage signal; the voltage instantaneous amplitude acquisition module is used to acquire single-phase voltage signals from the bus through voltage transformers, perform two-way orthogonal integration through a second-order generalized integrator to construct positive-sequence and negative-sequence synchronous coordinate systems, extract positive-sequence and negative-sequence components through low-pass filtering, and perform voltage sag and three-phase imbalance judgment to obtain voltage instantaneous amplitude and voltage transient flag; the fault branch location module is used to locate the fault branch based on the branch voltage pulse signal, residual current RMS value, voltage instantaneous amplitude and voltage transient flag, wherein each fault branch is identified by fault type, including three-phase imbalance source branch, short-circuit fault branch and insulation leakage branch; the protection management module is used to generate differentiated protection commands for the fault branch and execute adaptive protection management for abnormal operating conditions.

[0008] One or more technical solutions provided in this application have at least the following technical effects or advantages: By acquiring fault synchronization signals, branch voltage pulse signals and analog voltage signals are obtained. The analog voltage signal is modulated and filtered for reconstruction, and the effective value of the residual current is calculated. Positive and negative sequence synchronization coordinate systems are constructed to obtain the instantaneous voltage amplitude and voltage transient flag. Based on the branch voltage pulse signal, the effective value of the residual current, the instantaneous voltage amplitude, and the voltage transient flag, the faulty branch is located. For the faulty branch, differentiated protection commands are generated, and adaptive protection management for abnormal operating conditions is executed. This achieves the technical effect of accurately locating multiple types of faults in the distribution box and implementing differentiated adaptive protection, thereby improving the efficiency of power distribution safety management. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A schematic flowchart of an adaptive protection method for abnormal operating conditions of a distribution box is provided in an embodiment of this application. Figure 2 This is a schematic diagram of an adaptive protection system for abnormal operating conditions of a distribution box, provided as an embodiment of this application.

[0011] Explanation of reference numerals in the attached diagram: 10 for residual current effective value calculation module, 20 for instantaneous voltage amplitude acquisition module, 30 for fault branch location module, and 40 for protection management module. Detailed Implementation

[0012] This application provides an adaptive protection method and system for abnormal operating conditions of distribution boxes, which addresses the technical problems of incomplete fault type identification, low fault branch location accuracy, uniform and crude protection strategies, and difficulty in achieving hierarchical and differentiated handling in existing distribution boxes.

[0013] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0014] Example 1, as Figure 1 As shown, this application provides an adaptive protection method for abnormal operating conditions of a distribution box, the method comprising: Step S100: Obtain the branch voltage pulse signal and analog voltage signal through fault synchronization signal acquisition, and reconstruct the analog voltage signal by signal modulation and filtering to calculate the effective value of the residual current.

[0015] Specifically, Hall effect sensors are installed at the main inlet switch of the distribution box and the outlet terminals of each branch to collect branch voltage pulse signals that are proportional to the rate of change of branch current. At the same time, current transformers are installed in the residual current loop to collect analog voltage signals that are proportional to the measured residual current. The analog voltage signal is input into a second-order Σ-Δ modulator to obtain a high sampling rate bit stream. After being downsampled by a comb filter and low-pass filtered by a half-band filter, the digital waveform of the residual current is reconstructed. The root mean square value of the digital waveform is calculated cycle by cycle to finally obtain the effective value of the residual current.

[0016] Step S200: Collect single-phase voltage signals from the bus through voltage transformers, perform two-way orthogonal integration through a second-order generalized integrator, construct positive-sequence and negative-sequence synchronous coordinate systems, extract positive-sequence and negative-sequence components through low-pass filtering, perform voltage sag and three-phase imbalance judgment, and obtain instantaneous voltage amplitude and voltage transient flag.

[0017] Specifically, a single-phase voltage signal is acquired from the busbar of the distribution box through a voltage transformer. After signal amplification, it is input into a second-order generalized integrator to generate an α-axis signal in phase with the input voltage and a β-axis signal lagging the α-axis signal by 90°. Based on the two orthogonal signals, a positive-sequence and negative-sequence synchronous coordinate system is constructed. The DC components of the positive-sequence and negative-sequence components are extracted by a low-pass filter. The instantaneous voltage amplitude is calculated based on the positive-sequence component. Voltage sag and three-phase imbalance are judged based on the ratio of the negative-sequence amplitude to the positive-sequence amplitude and the ratio of the positive-sequence amplitude to the rated value. Finally, the instantaneous voltage amplitude and voltage transient status are obtained.

[0018] Step S300: Locate the faulty branch based on the branch voltage pulse signal, the effective value of the residual current, the instantaneous voltage amplitude, and the voltage transient flag. Each faulty branch is identified by its fault type, including three-phase unbalanced source branches, short-circuit fault branches, and insulation leakage branches.

[0019] Specifically, the fault branch is located based on the branch voltage pulse signal, the effective value of the residual current, the instantaneous voltage amplitude, and the voltage transient flag. When it is determined to be a three-phase imbalance, the three-phase imbalance source branch is directly locked. After the three-phase imbalance is eliminated, the total current increment at the moment of the fault is compared with the current increment of each branch based on the branch voltage pulse signal to lock the short-circuit fault branch. Then, the voltage transient flag is used to achieve fault synchronization. When the voltage transient flag is a voltage sag and the effective value of the residual current exceeds the leakage threshold, and the short-circuit fault is eliminated, the insulation leakage branch is determined and located, and finally the fault branch with the fault type identifier is output.

[0020] Step S400: For the faulty branch, generate differentiated protection instructions and execute adaptive protection management for abnormal operating conditions.

[0021] Specifically, based on the identified fault branch type and branch number, corresponding differentiated protection instructions are generated. For short-circuit fault branches, a first trip instruction is generated to drive the corresponding branch solid-state circuit breaker to perform a tripping action. For three-phase unbalanced source branches, a second delay-lock instruction is triggered to achieve delayed early warning and branch locking. For insulation leakage branches, a third reporting instruction is triggered to perform front-end alarm and report the branch number and leakage current amplitude, thereby completing the adaptive protection management of abnormal operating conditions of the distribution box. At the same time, the fault event type, branch number, instantaneous voltage amplitude at the time of the fault, residual current effective value, and branch voltage pulse signal are packaged into a structured log and uploaded to the operation and maintenance platform through the communication interface to update the prior probabilities of the Bayesian network of each branch.

[0022] In one possible implementation, step S100 further includes: Step S110: Install Hall sensors at the main incoming switch and the outgoing terminals of each branch to collect branch voltage pulse signals, wherein the branch voltage pulse signals are proportional to the branch current change rate.

[0023] Step S120: Install a current transformer in the residual current loop and collect an analog voltage signal, wherein the analog voltage signal is proportional to the measured residual current.

[0024] Step S130: Modulate and filter the analog voltage signal to obtain the effective value of the residual current.

[0025] Specifically, Hall sensors are installed at the main incoming switch of the distribution box and at the outgoing terminals of each branch. The Hall sensors collect the branch voltage pulse signals in real time. These signals are directly proportional to the rate of change of the current in the corresponding branch, providing synchronous data collection for subsequent fault location.

[0026] A current transformer is installed in the residual current loop of the distribution box. The current transformer is used to collect an analog voltage signal that is proportional to the residual current being measured, providing raw input data for the subsequent calculation of the effective value of the residual current.

[0027] The acquired analog voltage signal is input into a second-order Σ-Δ modulator to obtain a high sampling rate bit stream. The bit stream is then downsampled by a comb filter and then low-pass filtered by a half-band filter to reconstruct an accurate digital waveform of the residual current. Finally, the root mean square value of the residual current digital waveform is calculated cycle by cycle to obtain the effective value of the residual current.

[0028] In one possible implementation, step S130 further includes: Step S131: Input the analog voltage signal into a second-order Σ-Δ modulator to obtain a high sampling rate bit stream.

[0029] Step S132: The high sampling rate bitstream is downsampled by a comb filter, then low-pass filtered by a half-band filter to reconstruct the digital waveform of the residual current.

[0030] Step S133: Calculate the root mean square value of the residual current digital waveform cycle by cycle to obtain the effective value of the residual current.

[0031] Specifically, the analog voltage signal output from the residual current transformer is input to a second-order Σ-Δ modulator. The weak analog signal is preprocessed with high precision using oversampling technology and noise shaping mechanism to generate a high-sampling-rate bit stream. Since the original residual current signal has the characteristics of small amplitude and is susceptible to power frequency interference and environmental electromagnetic noise, if a low sampling rate is used for analog-to-digital conversion, the high-frequency characteristic components corresponding to electric shock faults will be lost. Therefore, the quantization noise is shifted to the high-frequency band by the second-order Σ-Δ modulator. Combined with the subsequent digital decimation and filtering circuit, the signal-to-noise ratio and conversion resolution can be significantly improved within the 100kHz target bandwidth required for electric shock detection, providing a high-quality digital signal for accurate calculation of residual current.

[0032] The high-sampling-rate bitstream output from the second-order Σ-Δ modulator is first input to a comb filter. The comb filter performs downsampling processing, which reduces the data sampling rate while suppressing high-frequency quantization noise. The downsampled signal is then sequentially fed into a half-band filter, which performs low-pass filtering to further filter out residual high-frequency interference components in the signal, retaining the effective residual current signal that meets the bandwidth requirements of electric shock detection. Finally, a smooth, complete digital waveform of the residual current that can be used for RMS value calculation is reconstructed.

[0033] The residual current digital waveform obtained after filtering and reconstruction is sampled and calculated cycle by cycle based on the power frequency voltage cycle. According to the root mean square algorithm, all discrete digital sampling points in each complete cycle are first squared, then summed and averaged, and finally the square root is taken to obtain the root mean square value. This root mean square value is the effective value of residual current used for leakage current determination and fault analysis.

[0034] In one possible implementation, step S200 further includes: Step S210: Collect single-phase voltage signals from the distribution box bus based on the voltage transformer.

[0035] Step S220: Perform signal amplification on the single-phase voltage signal, input it into a second-order generalized integrator, and generate two orthogonal signals, wherein the two orthogonal signals include an α-axis signal that is in phase with the input voltage and a β-axis signal that lags the α-axis signal by 90°.

[0036] Step S230: Construct a positive-sequence synchronization coordinate system and a negative-sequence synchronization coordinate system based on the two orthogonal signals to obtain the instantaneous voltage amplitude and voltage transient flag.

[0037] Specifically, a voltage transformer is used to collect single-phase voltage signals from the busbar of the distribution box. The voltage transformer is a sensing element used to proportionally convert the high-voltage side voltage of the busbar into a detectable low-voltage side voltage. The busbar is the main conductor in the distribution box that collects and distributes electrical energy. The collected single-phase voltage signal is the basic electrical signal that reflects the real-time status of the power supply voltage of the distribution box and is used for subsequent voltage feature extraction and fault identification.

[0038] The single-phase voltage signal acquired by the voltage transformer is amplified to improve the amplitude and driving capability of the weak voltage signal, meeting the input requirements of subsequent processing units. The amplified single-phase voltage signal is then input into a second-order generalized integrator, which performs orthogonalization processing on the input AC voltage and outputs two orthogonal signals that are perpendicular to each other in phase. One signal is an α-axis signal that is in phase with the input voltage, and the other signal is a β-axis signal that lags the α-axis signal by 90° electrical angle. The two orthogonal signals are used to construct a synchronous coordinate system and to accurately extract the positive and negative sequence components of the voltage.

[0039] Based on the aforementioned two orthogonal signals, the α-axis and β-axis signals, a positive-sequence synchronization coordinate system and a negative-sequence synchronization coordinate system are constructed respectively. The voltage vector in the α-β plane is rotated towards the fundamental positive-sequence phase direction, so that the fundamental positive-sequence component is in the d... + -q + Converting to DC components in a coordinate system, similarly rotating the vector towards the fundamental negative-sequence phase direction to construct a negative-sequence coordinate system, and extracting the positive-sequence d-coordinate system using a low-pass filter. + Values ​​and ascending order q + The positive-order components of the value and the negative-order components d - Value and Negative Order q - The negative sequence component of the value is used to calculate the instantaneous voltage amplitude, which represents the real-time magnitude of the voltage, based on the positive sequence component. Voltage sag and three-phase imbalance are judged based on the ratio of the negative sequence amplitude to the positive sequence amplitude and the ratio of the positive sequence amplitude to the rated voltage. Finally, a voltage transient flag is output to identify abnormal voltage conditions.

[0040] In one possible implementation, step S230 further includes: Step S231: Extract the DC component from the positive-sequence synchronization coordinate system and the negative-sequence synchronization coordinate system using a low-pass filter to obtain the positive-sequence component and the negative-sequence component, wherein the positive-sequence component includes the positive-sequence d + Values ​​and ascending order q + Value, negative order component contains negative order d - Value and Negative Order q - value.

[0041] Step S232: Calculate the positive sequence amplitude based on the positive sequence component, wherein the positive sequence amplitude is used as the instantaneous voltage amplitude.

[0042] Step S233: Calculate the negative sequence magnitude based on the negative sequence component.

[0043] Step S234: Based on the negative sequence amplitude and the positive sequence amplitude, determine the voltage sag and three-phase imbalance.

[0044] Specifically, the constructed positive-sequence synchronization coordinate system and negative-sequence synchronization coordinate system signals are respectively fed into low-pass filters. The low-pass filters remove AC harmonic components and high-frequency interference from the coordinate systems, accurately extracting the corresponding DC components, thereby obtaining the positive-sequence voltage component and the negative-sequence voltage component. The positive-sequence component includes the positive-sequence direct-axis component and the positive-sequence d-axis component. + Values ​​and positive sequence cross-axis components positive sequence q + Value, negative order component includes negative order direct axis component negative order d - Value and negative order cross axis component negative order q - The value provides a stable characteristic parameter for subsequent voltage amplitude calculation and fault identification.

[0045] The positive sequence magnitude is calculated based on the positive sequence component extracted by low-pass filtering, where the positive sequence component contains the positive sequence d representing the direct axis information. + The positive order q of the value and the representation of the intersection axis information + Value; the specific calculation method is to take the ascending order d + Values ​​and ascending order q + The values ​​are squared, the squared values ​​are summed, and the arithmetic square root of the sum is taken to obtain the positive sequence amplitude. This positive sequence amplitude can represent the actual magnitude of the current power supply voltage in real time and can be directly used as the instantaneous voltage amplitude for fault identification.

[0046] The negative sequence magnitude is calculated based on the negative sequence component extracted by low-pass filtering, where the negative sequence component contains the negative sequence d representing the direct axis information. - The negative order q of the value and the representation of the cross axis information - Value; the specific calculation method is to take the negative order d - Value and Negative Order q - The values ​​are squared separately, the squared values ​​are summed, and the arithmetic square root of the sum is taken. The resulting value is the negative sequence amplitude. This negative sequence amplitude is used to characterize the degree of three-phase voltage asymmetry in the system and provides a core basis for subsequent three-phase imbalance fault identification.

[0047] The calculated negative-sequence amplitude is compared with the positive-sequence amplitude. The ratio of the negative-sequence amplitude to the positive-sequence amplitude is used to determine a three-phase imbalance fault. When the ratio is greater than the preset imbalance threshold, it is determined that there is a three-phase imbalance problem in the current power supply system. At the same time, the voltage sag is judged by comparing the positive-sequence amplitude with the rated voltage amplitude. When the positive-sequence amplitude is lower than the preset voltage drop threshold, it is determined that a voltage sag abnormality has occurred. Finally, a voltage transient flag that can be used for fault location is generated, providing a basis for voltage-side anomalies for subsequent fault branch identification.

[0048] In one possible implementation, step S234 further includes: Step S2341: If the ratio of negative sequence amplitude to positive sequence amplitude is greater than the first preset threshold and the positive sequence amplitude is lower than the preset ratio, it is determined that the three phases are unbalanced.

[0049] Step S2342: If the positive sequence amplitude is less than the second preset threshold and the negative sequence amplitude is normal, it is determined to be a voltage sag.

[0050] Specifically, the calculated negative-sequence amplitude is compared with the positive-sequence amplitude to obtain the imbalance ratio. This ratio is then compared with a pre-set first threshold value. Simultaneously, the positive-sequence amplitude is compared with a preset ratio of the amplitude corresponding to the rated voltage. When the ratio of the negative-sequence amplitude to the positive-sequence amplitude is greater than the first preset threshold value and the positive-sequence amplitude is lower than the preset ratio, a three-phase imbalance fault is determined to have occurred in the power supply system of the distribution box, providing a basis for the generation of voltage anomaly types for subsequent differentiated protection commands.

[0051] The calculated positive sequence amplitude is compared with a second preset threshold for judging voltage drop, and the negative sequence amplitude is checked to see if it is within the normal range, that is, the negative sequence amplitude does not exceed the normal fluctuation range. When the positive sequence amplitude is less than the second preset threshold and the negative sequence amplitude remains normal, it is determined that a voltage drop fault has occurred in the power supply of the distribution box bus, thereby marking the abnormal voltage state and providing a basis for voltage abnormality characteristics for subsequent fault identification and branch location.

[0052] In one possible implementation, step S300 further includes: Step S310: If it is determined that there is a three-phase imbalance, lock the source branch of the three-phase imbalance.

[0053] Step S320: Based on the branch voltage pulse signal, by comparing the total current increment at the moment of the fault with the current increment of each branch, the short-circuit fault branch is locked after eliminating the three-phase imbalance.

[0054] Step S330: Synchronize the fault time according to the voltage transient flag. If the voltage transient flag is a voltage sag and the effective value of the residual current exceeds the leakage threshold, it is determined to be an insulation leakage branch after the short circuit fault is eliminated.

[0055] Specifically, when a three-phase imbalance fault is determined in the power supply system of the distribution box by the negative sequence amplitude and the positive sequence amplitude, the current and voltage sampling data collected in real time for each branch are compared with the degree of three-phase current deviation and load asymmetry characteristics of each branch to identify the power supply branch that causes the three-phase voltage imbalance of the system and complete the accurate locking of the three-phase imbalance source branch.

[0056] Based on the branch voltage pulse signals collected from each branch of the distribution box, the instantaneous moment of the fault occurrence is accurately captured. The total current increment at the incoming end of the distribution box and the corresponding branch current increment of each power-consuming branch are extracted at the moment of the fault. By comparing the numerical change relationship between the two, the current disturbance interference caused by the three-phase imbalance fault is first eliminated. At the same time, the pulse characteristics are combined for discrimination. The voltage pulse amplitude corresponding to the faulty branch is significantly greater than that of the non-faulty branch, and the pulse polarity points to the bus, indicating that the current flows into the fault point from the bus. Based on the above characteristics, the target branch where the short circuit fault occurs can be accurately located.

[0057] Based on the voltage transient flag that characterizes the type of voltage anomaly, the fault time of each acquired signal in the system is synchronized, and the fault judgment timing benchmark is unified. When the voltage transient flag determines that the power supply state is a voltage sag, and the effective value of the calculated residual current is greater than the preset leakage threshold, and the interference of short circuit fault has been eliminated through the aforementioned steps, it is determined that there is insulation damage and leakage to ground in the applied power branch, which is the insulation leakage branch, thus completing the accurate branch location of leakage faults.

[0058] In one possible implementation, step S300 further includes: Step S340: Generate differentiated protection instructions based on the branch number of the faulty branch.

[0059] If the fault is a short-circuit fault branch, a first trip command is generated, wherein the first trip command drives the corresponding branch solid-state circuit breaker to perform a tripping action.

[0060] Step S350: If it is a three-phase unbalanced source branch, trigger the second delay lock command, wherein the second delay lock command triggers delay warning and branch lock.

[0061] Step S360: If it is an insulation leakage branch, trigger the third reporting command, wherein the third reporting command triggers the front-end alarm and reports the branch number and leakage current amplitude.

[0062] Specifically, based on the branch number corresponding to the faulty branch obtained from the aforementioned steps, this branch number serves as a unique identifier for each power branch within the distribution box, used to distinguish different power supply circuits. For different fault types such as three-phase imbalance, short-circuit faults, and insulation leakage, and in conjunction with the severity level of the corresponding fault and electrical safety requirements, differentiated protection instructions matching the fault type and branch attributes are generated. These protection instructions include different execution strategies such as tripping control, alarm signal output, and fault information uploading for the corresponding branch, achieving precise, hierarchical, and differentiated protection control for different faulty branches.

[0063] If the located faulty branch is a short-circuit faulty branch, and the branch is at risk of a large current surge due to the short circuit, a first trip command for emergency power outage protection is generated. The first trip command is a digital control command containing the branch control address and trip trigger signal, which can be directly sent to the solid-state circuit breaker configured in the corresponding branch. The solid-state circuit breaker is a switching device that uses power electronic devices to achieve fast switching. It has the characteristics of no mechanical contacts and fast action speed. The first trip command drives the solid-state circuit breaker to immediately perform the trip action, quickly cut off the power supply circuit of the faulty branch, and prevent the short circuit fault from expanding and causing a safety accident.

[0064] If the fault diagnosis determines that the current faulty branch is a three-phase unbalanced source branch, the branch causes three-phase voltage and current imbalance in the power supply system due to load asymmetry, and does not pose an emergency risk of instantaneous power outage. Therefore, a second delay lockout command is generated and triggered. The second delay lockout command is a timing control command with a preset duration, used to perform delay warning and branch lockout operations. The delay warning refers to outputting an audible and visual or remote alarm signal to indicate the existence of the fault within the preset delay period. The branch lockout refers to marking and controlling the power supply authority of the faulty branch, restricting its disorderly start and stop, and achieving controllable handling of three-phase unbalanced faults while ensuring the continuity of overall power supply.

[0065] If the fault diagnosis determines that the current faulty branch is an insulation leakage branch, and this branch has a ground leakage phenomenon due to damage or aging of the insulation layer, posing a leakage safety hazard, but it is not necessary to immediately cut off the overall power supply, a third reporting command is generated and triggered. The third reporting command is a fault information transmission and alarm triggering control command. Its core function is to simultaneously trigger the front-end alarm and fault information reporting. The front-end alarm refers to driving the local sound and light alarm device of the distribution box to start, emitting intuitive sound and light prompt signals, so that on-site personnel can quickly detect the leakage fault. At the same time, the third reporting command will use the branch number corresponding to the insulation leakage branch to accurately locate the faulty circuit and the real-time detected leakage current amplitude to characterize the severity of the leakage fault, and simultaneously upload it to the system monitoring terminal. This provides accurate fault parameters and location basis for subsequent fault investigation and insulation repair by the staff, realizing the traceability and handling of leakage faults.

[0066] In one possible implementation, step S400 further includes: Step S410: As the differentiated protection command is executed, the fault event type, branch number, instantaneous voltage amplitude at the time of the fault, effective value of residual current and branch voltage pulse signal are packaged into a structured log.

[0067] Step S420: Upload the structured log to the operation and maintenance platform via the communication interface.

[0068] Step S430: The operation and maintenance platform updates the Bayesian network prior probabilities of each branch based on the structured logs.

[0069] Specifically, during the synchronous execution of the aforementioned generated differentiated protection instructions, the fault event type corresponding to this fault, the branch number used to uniquely identify the fault circuit, the instantaneous voltage amplitude calculated at the time of the fault occurrence, the effective value of the residual current obtained in real time, and the branch voltage pulse signal used to characterize the fault mutation features are collected. The above multi-dimensional fault feature data are organized and integrated according to the preset data format, packaged and generated into a structured log with a unified format, standardized fields, and parsable characteristics. This achieves standardized retention of key information throughout the fault process, which is convenient for subsequent fault source tracing analysis, maintenance record archiving, and system status review.

[0070] With the help of the device's reserved communication interface, which serves as the hardware and protocol transmission port for data interaction between the local device and the remote platform, stable transmission of fault data is supported. The structured logs containing multi-dimensional fault information generated above are transmitted and uploaded to the cloud or locally deployed operation and maintenance platform according to the preset communication protocol and data format, realizing remote archiving and real-time push of fault logs, which makes it convenient for operation and maintenance management personnel to view fault details in real time, carry out fault tracing and equipment operation and maintenance management.

[0071] The remote operation and maintenance platform receives and parses the uploaded structured logs, which contain fault characteristic data such as fault event type, branch number, instantaneous voltage amplitude, and residual current effective value. A Bayesian network for fault reasoning in distribution branches is pre-built within the platform. This network uses the operating status, abnormal electrical parameters, and fault type of each branch as core nodes. Causal relationships between nodes are established based on fault mechanisms such as short circuits, three-phase imbalance, and insulation leakage. Network construction is completed by determining node types, building the topology, and initializing conditional probabilities. The prior probabilities are the initial probabilities of different faults occurring in each branch. Based on real fault samples in the structured logs, the operation and maintenance platform updates the prior probabilities of various faults in each branch in the Bayesian network accordingly, continuously optimizing the fault reasoning model and improving the accuracy of subsequent fault prediction and risk assessment.

[0072] Example 2, based on the same inventive concept as the adaptive protection method for abnormal operating conditions of a distribution box in the foregoing examples, such as... Figure 2 As shown, this application provides an adaptive protection system for abnormal operating conditions of a distribution box. The system and method embodiments in this application are based on the same inventive concept. The system includes: The residual current effective value calculation module 10 is used to obtain the branch voltage pulse signal and the analog voltage signal through fault synchronization signal acquisition, and to calculate the residual current effective value by modulating and filtering the analog voltage signal.

[0073] The instantaneous voltage amplitude acquisition module 20 is used to acquire single-phase voltage signals from the bus through a voltage transformer, perform two-way orthogonal integration through a second-order generalized integrator, construct a positive-sequence and negative-sequence synchronous coordinate system, extract the positive-sequence and negative-sequence components through low-pass filtering, and perform voltage sag and three-phase imbalance judgment to obtain the instantaneous voltage amplitude and voltage transient flag.

[0074] The fault branch location module 30 is used to locate the fault branch based on the branch voltage pulse signal, the effective value of the residual current, the instantaneous voltage amplitude and the voltage transient flag. Each fault branch is identified by a fault type, including three-phase unbalanced source branches, short-circuit fault branches and insulation leakage branches.

[0075] The protection management module 40 is used to generate differentiated protection instructions for the faulty branch and execute adaptive protection management under abnormal operating conditions.

[0076] Furthermore, the system is also used to implement the following functions: Hall effect sensors are installed at the main incoming switch and the outgoing terminals of each branch to collect branch voltage pulse signals, wherein the branch voltage pulse signals are proportional to the branch current change rate; current transformers are installed in the residual current loop to collect analog voltage signals, wherein the analog voltage signals are proportional to the measured residual current; the analog voltage signals are modulated and filtered to obtain the effective value of the residual current.

[0077] Furthermore, the system is also used to implement the following functions: The analog voltage signal is input into a second-order Σ-Δ modulator to obtain a high sampling rate bit stream; the high sampling rate bit stream is downsampled by a comb filter, then low-pass filtered by a half-band filter to reconstruct the digital waveform of the residual current; the root mean square value of the digital waveform of the residual current is calculated cycle by cycle to obtain the effective value of the residual current.

[0078] Furthermore, the system is also used to implement the following functions: Based on the voltage transformer, a single-phase voltage signal is acquired from the busbar of the distribution box; the single-phase voltage signal is amplified and input into a second-order generalized integrator to generate two orthogonal signals, wherein the two orthogonal signals include an α-axis signal that is in phase with the input voltage and a β-axis signal that lags the α-axis signal by 90°; based on the two orthogonal signals, a positive-sequence synchronous coordinate system and a negative-sequence synchronous coordinate system are constructed to obtain the instantaneous voltage amplitude and voltage transient flag.

[0079] Furthermore, the system is also used to implement the following functions: The positive-sequence synchronization coordinate system and the negative-sequence synchronization coordinate system are processed by a low-pass filter to extract the DC component, resulting in a positive-sequence component and a negative-sequence component. The positive-sequence component includes a positive-sequence d-axis. + Values ​​and ascending order q+ Value, negative order component contains negative order d - Value and Negative Order q - Value; calculate the positive sequence amplitude based on the positive sequence component, wherein the positive sequence amplitude is used as the instantaneous voltage amplitude; calculate the negative sequence amplitude based on the negative sequence component; and determine voltage sag and three-phase imbalance based on the negative sequence amplitude and the positive sequence amplitude.

[0080] Furthermore, the system is also used to implement the following functions: If the ratio of negative sequence amplitude to positive sequence amplitude is greater than the first preset threshold and the positive sequence amplitude is lower than the rated value of the preset ratio, it is judged as three-phase imbalance; if the positive sequence amplitude is less than the second preset threshold and the negative sequence amplitude is normal, it is judged as voltage sag.

[0081] Furthermore, the system is also used to implement the following functions: If it is determined to be a three-phase imbalance, the three-phase imbalance source branch is locked; based on the branch voltage pulse signal, by comparing the total current increment at the moment of the fault with the current increment of each branch, the short-circuit fault branch is locked after eliminating the three-phase imbalance; the fault is triggered synchronously according to the voltage transient flag. If the voltage transient flag is a voltage sag and the effective value of the remaining current exceeds the leakage threshold, the branch is determined to be an insulation leakage branch after eliminating the short-circuit fault.

[0082] Furthermore, the system is also used to implement the following functions: Based on the branch number of the faulty branch, a differentiated protection command is generated. If it is a short-circuit faulty branch, a first trip command is generated, which drives the corresponding branch solid-state circuit breaker to perform a tripping action. If it is a three-phase unbalanced source branch, a second delayed lockout command is triggered, which triggers a delayed warning and branch lockout. If it is an insulation leakage branch, a third reporting command is triggered, which triggers a front-end alarm and reports the branch number and leakage current amplitude.

[0083] Furthermore, the system is also used to implement the following functions: As the differentiated protection command is executed, the fault event type, branch number, instantaneous voltage amplitude at the time of the fault, effective value of residual current, and branch voltage pulse signal are packaged into a structured log; the structured log is uploaded to the operation and maintenance platform through the communication interface; the operation and maintenance platform updates the Bayesian network prior probability of each branch based on the structured log.

[0084] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Specific embodiments of this specification have been described above. Furthermore, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0085] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0086] This specification and accompanying drawings are merely illustrative examples of this application and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Therefore, if such modifications and variations fall within the scope of this application and its equivalents, this application intends to include such modifications and variations.

Claims

1. An adaptive protection method for abnormal operating conditions of a distribution box, characterized in that, The method includes: By acquiring fault synchronization signals, branch voltage pulse signals and analog voltage signals are obtained. The analog voltage signals are then modulated and filtered to reconstruct the signal, and the effective value of the residual current is calculated. Single-phase voltage signals are acquired from the bus by voltage transformers, and then two-way orthogonal integration is performed by a second-order generalized integrator to construct a positive-sequence and negative-sequence synchronous coordinate system. The positive-sequence and negative-sequence components are extracted by low-pass filtering, and voltage sag and three-phase imbalance are judged to obtain the instantaneous voltage amplitude and voltage transient status. Based on the branch voltage pulse signal, residual current effective value, voltage instantaneous amplitude and voltage transient flag, the faulty branch is located. Each faulty branch is identified by its fault type, including three-phase unbalanced source branch, short-circuit fault branch and insulation leakage branch. For the faulty branch, a differentiated protection command is generated, and adaptive protection management for abnormal operating conditions is executed.

2. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 1, characterized in that, Hall sensors are installed at the main incoming switch and the outgoing terminals of each branch to collect branch voltage pulse signals, wherein the branch voltage pulse signals are proportional to the branch current change rate. A current transformer is installed in the residual current loop to collect an analog voltage signal, wherein the analog voltage signal is proportional to the measured residual current. The analog voltage signal is modulated and filtered to obtain the effective value of the residual current.

3. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 2, characterized in that, The analog voltage signal is modulated and filtered to obtain the effective value of the residual current, including: The analog voltage signal is input into a second-order Σ-Δ modulator to obtain a high sampling rate bit stream; The high sampling rate bitstream is downsampled by a comb filter, then low-pass filtered by a half-band filter to reconstruct the digital waveform of the residual current. The root mean square value of the residual current is calculated cycle by cycle for the digital waveform of the residual current to obtain the effective value of the residual current.

4. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 1, characterized in that, Obtain the instantaneous voltage amplitude and voltage transient flags, including: Single-phase voltage signals are collected from the distribution box bus based on the voltage transformer. The single-phase voltage signal is amplified and input into a second-order generalized integrator to generate two orthogonal signals, wherein the two orthogonal signals include an α-axis signal that is in phase with the input voltage and a β-axis signal that lags the α-axis signal by 90°. Based on the two orthogonal signals, construct a positive-sequence synchronization coordinate system and a negative-sequence synchronization coordinate system to obtain the instantaneous voltage amplitude and voltage transient flag.

5. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 4, characterized in that, Based on the two orthogonal signals, a positive-sequence synchronization coordinate system and a negative-sequence synchronization coordinate system are constructed to obtain the instantaneous voltage amplitude and voltage transient flags, including: The positive-sequence synchronization coordinate system and the negative-sequence synchronization coordinate system are processed by a low-pass filter to extract the DC component, resulting in a positive-sequence component and a negative-sequence component. The positive-sequence component includes a positive-sequence d-axis. + Values ​​and ascending order q + Value, negative order component contains negative order d - Value and Negative Order q - value; Based on the positive sequence component, the positive sequence amplitude is calculated, wherein the positive sequence amplitude is used as the instantaneous voltage amplitude; Calculate the negative order magnitude based on the negative order component; Voltage sag and three-phase imbalance are determined based on negative sequence amplitude and positive sequence amplitude.

6. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 5, characterized in that, If the ratio of negative sequence amplitude to positive sequence amplitude is greater than the first preset threshold and the positive sequence amplitude is lower than the preset ratio, it is judged as three-phase imbalance. If the positive sequence amplitude is less than the second preset threshold and the negative sequence amplitude is normal, it is judged as a voltage sag.

7. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 6, characterized in that, Locating the faulty branch includes: If it is determined to be a three-phase imbalance, the source branch of the three-phase imbalance is identified; Based on the branch voltage pulse signal, by comparing the total current increment at the moment of the fault with the current increment of each branch, the short-circuit fault branch is locked after eliminating the three-phase imbalance. The fault is triggered synchronously according to the voltage transient flag. If the voltage transient flag is a voltage sag and the effective value of the residual current exceeds the leakage threshold, it is determined to be an insulation leakage branch after the short circuit fault is eliminated.

8. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 1, characterized in that, Generate differentiated protection instructions based on the branch number of the faulty branch; If it is a short-circuit fault branch, a first trip command is generated, wherein the first trip command drives the corresponding branch solid-state circuit breaker to perform a tripping action. If it is a three-phase unbalanced source branch, a second delay lockout command is triggered, wherein the second delay lockout command triggers a delay warning and branch lockout; If it is an insulated leakage branch, a third reporting command is triggered. The third reporting command triggers a front-end alarm and provides you with the branch number and leakage current amplitude.

9. The adaptive protection method for abnormal operating conditions of a distribution box as described in claim 1, characterized in that, After implementing adaptive protection management for abnormal operating conditions, the following is included: As the differentiated protection command is executed, the fault event type, branch number, instantaneous voltage amplitude at the time of the fault, effective value of residual current and branch voltage pulse signal are packaged into a structured log. The structured logs are uploaded to the operation and maintenance platform via the communication interface; The operation and maintenance platform updates the Bayesian network prior probabilities of each branch based on the structured logs.

10. An adaptive protection system for abnormal operating conditions of a distribution box, characterized in that, The system is used to implement the adaptive protection method for abnormal operating conditions of a distribution box according to any one of claims 1-9, the system comprising: The residual current effective value calculation module is used to obtain the branch voltage pulse signal and the analog voltage signal through fault synchronization signal acquisition, and to calculate the residual current effective value by modulating and filtering the analog voltage signal. The instantaneous voltage amplitude acquisition module is used to acquire single-phase voltage signals from the bus through a voltage transformer, perform two-way orthogonal integration through a second-order generalized integrator, construct a positive-sequence and negative-sequence synchronous coordinate system, extract the positive-sequence and negative-sequence components through low-pass filtering, and perform voltage sag and three-phase imbalance judgment to obtain the instantaneous voltage amplitude and voltage transient flag. The fault branch location module is used to locate the fault branch based on the branch voltage pulse signal, the effective value of the residual current, the instantaneous voltage amplitude and the voltage transient flag. Each fault branch is identified by a fault type, including three-phase unbalanced source branches, short-circuit fault branches and insulation leakage branches. The protection management module is used to generate differentiated protection instructions for the faulty branch and execute adaptive protection management under abnormal operating conditions.

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