Power distribution line fault location method based on primary and secondary fused set pole circuit breaker

Abstract

This invention specifically relates to a fault location method for distribution lines based on a primary and secondary integrated pole-mounted circuit breaker, falling within the field of distribution line fault detection and location technology. The method includes: after the primary and secondary integrated circuit breaker detects a line fault and trips, it classifies the fault type using edge computing, blocks conventional reclosing, and completes hardware reset and line parameter preloading before distance measurement. In this invention, the phase-selective closing function of the primary and secondary integrated circuit breaker actively injects a standardized high-frequency transient excitation signal, avoiding the randomness problem of the traditional traveling wave method relying on natural fault traveling waves, thus improving the signal-to-noise ratio and feature saliency of the transient signal. Simultaneously, the core of the distance measurement relies on the transient oscillation frequency, which is dominated by the line inductance and capacitance and minimally affected by high-resistance grounding resistance, naturally adapting to high-resistance fault scenarios. Furthermore, the Prony algorithm's accurate extraction of transient parameters and iterative correction strategy for transition resistance solve the problem of large errors in high-resistance scenarios using traditional impedance methods.

Description

Technical Field

[0001] This invention relates to the field of power distribution line fault detection and location technology, and in particular to a power distribution line fault location method based on a primary and secondary integrated pole-mounted circuit breaker. Background Technology

[0002] As an important component of the power system, the accuracy and timeliness of fault location in power distribution lines directly affect the reliability of power supply.

[0003] Current methods for fault location in power distribution lines mainly include traditional techniques such as impedance method and traveling wave method, but they have many limitations: the traditional traveling wave method relies on the natural traveling wave at the moment of fault occurrence for passive analysis. The phase of the fault occurrence is random, resulting in unclear transient signal characteristics, low signal-to-noise ratio, difficulty in parameter extraction, and weak anti-interference ability; the impedance method calculates the fault impedance based on steady-state power frequency voltage and current, which is significantly affected by the voltage division of high-resistance grounding resistance, resulting in large location error and difficulty in meeting the location requirements of high-resistance faults.

[0004] Therefore, there is an urgent need for a fault location method based on this type of equipment, which can improve the accuracy and reliability of location under high-resistance faults by constructing standardized transient signals through active excitation. Summary of the Invention

[0005] The purpose of this invention is to propose a method for fault location in power distribution lines based on a primary and secondary integrated pole-mounted circuit breaker in order to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for fault location in distribution lines based on a primary and secondary integrated pole-mounted circuit breaker includes: After the primary and secondary integrated circuit breaker detects a line fault and trips, it accurately classifies the fault type through edge computing, blocks conventional reclosing, and completes hardware reset and line parameter preloading before ranging. The controller detects the phase of the voltage on the power supply side in real time, and controls the circuit breaker to select and close the circuit at the peak of the voltage amplitude, injecting a high-frequency transient excitation signal into the line. Simultaneously with the closing command, transient current and voltage data within 2 to 10 ms are collected at a sampling rate of 100 kHz to 1 MHz, and the data quality is determined. The upstream line of the fault point is simplified into a second-order equivalent circuit, the transient current equation is derived, and the mathematical relationship between the transient oscillation frequency and the line parameters and the fault distance is established. After preprocessing the transient signal, the oscillation frequency and attenuation coefficient are extracted, and the fault distance and transition resistance are calculated iteratively. The results are then output after consistency verification.

[0007] Preferably, after the primary and secondary integrated circuit breakers detect a line fault and trip, they classify the fault type through edge computing, block conventional reclosing, and complete the hardware reset and line parameter preloading before ranging, specifically including: The three-phase current and voltage signals of the line are monitored in real time through current transformers, electronic voltage transformers and fault detection modules. The fault detection module uses overcurrent detection, grounding fault detection, and high-resistance fault screening to initially determine line faults. When the fault determination conditions are met, the circuit breaker controller sends a trip command to the actuator; Acquire power frequency current and voltage data, including three-phase current, within a preset time period before tripping. / / Three-phase voltage / / Zero-sequence current Zero-sequence voltage .

[0008] Preferably, the method further includes: like > And the fault current is greater than The fault is determined to be a metallic grounding / low-resistance short circuit; routine reclosing is then performed. like > , <and fault current < Meanwhile, the voltage drop was 10%. The fault is identified as a high-resistance grounding fault and marked as a distance measurement mode. If the fault current fluctuates intermittently and the voltage does not drop continuously: it is determined to be an intermittent arc fault and marked as a distance measurement mode; After marking the distance measurement mode, the controller issues a blocking command to prohibit blind reclosing within a preset time. Read the basic parameters of the current line.

[0009] Preferably, the controller detects the voltage phase on the power supply side in real time, controls the circuit breaker to select and close phases at the peak of the voltage amplitude, and injects a high-frequency transient excitation signal into the line, specifically including: Target of testing: Three-phase voltage on the power supply side / / ; Extract the fundamental voltage component and calculate the real-time phase. ; The controller continuously calculates the instantaneous amplitude of the three-phase voltage. When the voltage amplitude of a certain phase is detected to be at [ , ], and phase When the circuit stabilizes within the preset range, it is determined to be the optimal closing time. Single-phase high-resistance ground fault: Select the phase that is connected to the faulty phase; If there is a three-phase fault or the faulty phase cannot be determined: perform simultaneous closing of all three phases.

[0010] Preferably, when the closing command is triggered, transient current and voltage data within 2-10ms are simultaneously acquired at a sampling rate of 100kHz-1MHz, and the data quality is determined, specifically including: Synchronous acquisition of transient current Transient voltage ; Data acquisition is triggered by instruction hard triggering, and the closing instruction and the acquisition start instruction are output synchronously through the same FPGA pin; The acquisition module has a built-in circular buffer to pre-store voltage and current data before triggering. Data quality assessment criteria: Signal amplitude: peak transient current ≥ ; Signal-to-noise ratio: The ratio of the effective signal amplitude to the noise amplitude is ≥15dB; Number of oscillations: Transient oscillations ≥ 3 cycles within the acquisition time.

[0011] Preferably, the step of simplifying the upstream line of the fault point into a second-order equivalent circuit, deriving the transient current equation, and establishing the mathematical relationship between the transient oscillation frequency and the line parameters and fault distance specifically includes: The power distribution line is a distributed parameter circuit, and the length of the line upstream of the fault point is... The unit length parameter is , , The fault point is high resistance. Grounding; Transient oscillation frequency Above the power frequency, the line's resistance effect... Compared to inductors and capacitor It can be ignored, therefore it is simplified to Second-order series equivalent circuit For the transition resistance at the fault point, , ; The voltage balance equation of the equivalent circuit after closing is: ; The step voltage injected for closing the circuit breaker; Regarding time Taking the derivative, we get ; because For step voltage, Given the impulse function, the solution to the equation is divided into steady-state components. With transient components : The general expression for transient current is: ; For transient component amplitude, The initial phase angle of the transient component. The attenuation coefficient is... The natural oscillation frequency, Let be the amplitude of the power frequency steady-state component in the transient current. It is the power frequency angular frequency. The initial phase angle is the steady-state phase angle of the power frequency component.

[0012] Preferably, the method further includes the derivation of the correlation between physical parameters and fault distance: Inductance per unit length of power distribution lines ,capacitance Since it is a fixed value, the total inductance of the line upstream of the fault point is... Total capacitance ; Substitute , We can obtain: ; Obtain the fault distance The expression: .

[0013] Preferably, after preprocessing the transient signal, the oscillation frequency and attenuation coefficient are extracted, and the fault distance and transition resistance are calculated iteratively. After consistency verification, the results are output, specifically including: The acquired signals are preprocessed, including DC component removal, power frequency component filtering, and signal smoothing. Select the 2-5ms data segment with the largest amplitude in the filtered signal, data length =Sampling rate × Truncation duration; Constructing the Hankel matrix Perform SVD decomposition and determine the signal order based on the singular value attenuation characteristics. ; Solve The characteristic equation is used to obtain the eigenvalues. ; Calculate the attenuation coefficient from the eigenvalues angular frequency oscillation frequency ; The result was obtained by fitting using the least squares method. and ; The amplitude of the corresponding transient oscillation component; The initial phase angle corresponding to the transient oscillation component.

[0014] Preferably, the method further includes: Based on attenuation coefficient resistance , combined We can obtain: ; The optimization process is as follows: Depend on Preliminary calculations ; Substitution Formula calculation ; consider right Correction, recalculation ; Depend on calculate Iterate 2-3 times until The final fault distance is obtained when the change is less than a preset threshold. and transition resistance .

[0015] Preferably, the process further includes fault distance inversion and result output: The final extracted oscillation frequency Substitute into the fault distance formula: ;in, and For preloaded line unit length parameters; If transient voltage was collected simultaneously Then extract oscillation frequency ,calculate When | | When the preset requirements are met, output the effective distance. Otherwise, mark the ranging as suspicious and take the average of the two values; Output final fault distance Transition resistance Distance measurement confidence level.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention actively injects standardized high-frequency transient excitation signals through the phase selection and closing function of the primary and secondary integrated circuit breakers, avoiding the randomness problem of the traditional traveling wave method relying on natural fault traveling waves, and improving the signal-to-noise ratio and feature saliency of the transient signal. At the same time, the ranging core relies on the transient oscillation frequency, which is dominated by the line inductance and capacitance and is minimally affected by the high-resistance grounding resistance, making it naturally suitable for high-resistance fault scenarios. In addition, the Prony algorithm's accurate extraction of transient parameters and iterative correction strategy for transition resistance solve the pain point of large errors in high-resistance scenarios of the traditional impedance method.

[0017] 2. This invention constructs a multi-fault-tolerant mechanism: it filters effective data by using indicators such as signal amplitude and signal-to-noise ratio, verifies the reliability of parameters by relying on fitting error, and outputs confidence by combining the consistency judgment of current-voltage dual-channel ranging results, providing maintenance personnel with a reliable basis for decision-making and further ensuring the stability and reliability of fault location. Attached Figure Description

[0018] Further details, features, and advantages of this application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0019] Several embodiments of this application will now be described in more detail with reference to the accompanying drawings to enable those skilled in the art to implement this application. This application may be embodied in many different forms and for various purposes and should not be limited to the embodiments set forth herein. These embodiments are provided to make this application thorough and complete, and to fully convey the scope of this application to those skilled in the art. The embodiments described do not limit this application.

[0020] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0021] Example 1

[0022] Its specific implementation method is combined with the appendix Figure 1 Please provide a detailed explanation.

[0023] Appendix Figure 1The flowchart of the distribution line fault location method based on a primary and secondary integrated pole-mounted circuit breaker provided in the embodiments of the present invention shows the complete steps from classifying fault types through edge computing to extracting oscillation frequency and attenuation coefficient after preprocessing transient signals, and then back-calculating fault distance and transition resistance through iterative calculation.

[0024] In this embodiment, it includes: After the primary and secondary integrated circuit breaker detects a line fault and trips, it accurately classifies the fault type through edge computing, blocks conventional reclosing, and completes hardware reset and line parameter preloading before ranging. Specifically, it includes: By integrating high-precision electronic current transformers (ECT, ratio error ≤0.2%), electronic voltage transformers (EVT, phase error ≤±0.5°), and fault detection modules into the primary and secondary integrated circuit breakers, the three-phase current and voltage signals of the line can be monitored in real time (sampling rate 5kHz~10kHz, meeting the requirements for power frequency quantity detection). The fault detection module determines line faults based on the following indicators: Overcurrent detection: The peak value of any phase current in the three phases exceeds 1.2 to 1.5 times the rated current (configurable according to line parameters), and the duration is ≥20ms; Ground fault detection: zero-sequence current , The rated current of the line. It is zero-sequence current or zero-sequence voltage. , This is the line's rated voltage. It is zero-sequence voltage; Preliminary screening for high-resistance faults: The above fault conditions are met, but the fault current does not reach the instantaneous tripping threshold (e.g., <3). And the voltage drop is less than 30%. (When grounded with high resistance, the fault current is small, and the impact on system voltage is relatively small.) When the above fault determination conditions are met, the circuit breaker controller sends a trip command to the actuator (permanent magnet mechanism / spring-operated mechanism), and the actuator completes the contact opening within ≤20ms to achieve electrical isolation between the faulty line and the system; Acquire power frequency current and voltage data within a preset time (100ms) before tripping (continuously collected by ECT / EVT and stored in local cache), including three-phase current. / / Three-phase voltage / / Zero-sequence current Zero-sequence voltage .

[0025] The following logic is executed based on the edge computing unit (MCU+FPGA architecture): like > And the fault current is greater than The fault is determined to be a metallic grounding / low-resistance short circuit. Perform a conventional reclosing (no distance measurement required). like > , <and fault current < Meanwhile, the voltage drop was 10%. : If the fault is determined to be a high-resistance grounding fault (such as grounding through a 1kΩ~10kΩ resistor), mark it as the distance measurement mode; If the fault current fluctuates intermittently (peak difference > 50%) and the voltage does not drop continuously: it is determined to be an intermittent arc fault and marked as a distance measurement mode; After marking the distance measurement mode, the controller issues a lockout command to prohibit blind reclosing within a preset time (100ms) (to avoid multiple reclosings from amplifying the fault). The actuator is reset to the ready-to-close state, the ECT / EVT starts high-frequency sampling preheating (to ensure the accuracy of subsequent data acquisition), and the high-frequency waveform recording module is initialized (clearing the ring buffer and configuring parameters such as sampling rate and acquisition duration). Read the basic parameters of the current line from the local storage unit, including the inductance per unit length. Capacitance per unit length Line rated voltage Rated current .

[0026] The controller detects the voltage phase on the power supply side in real time, and controls the circuit breaker to select and close the circuit at the peak of the voltage amplitude (90° or 270°), injecting a high-frequency transient excitation signal into the line; Specifically, it includes: Real-time voltage phase detection: Target of testing: Three-phase voltage on the power supply side / / (Acquired by EVT, with an EVT bandwidth ≥ 1MHz, ensuring no distortion in high-frequency components); The fundamental voltage component is extracted using Discrete Fourier Transform (DFT), and the real-time phase is calculated using zero-crossing detection or phase-locked loop (PLL). The specific formula is as follows: ; For the first Voltage values ​​at each sampling point The number of sampling points per power frequency cycle. It is the power frequency angular frequency. The sampling period; Using the sampling clock of ECT / EVT as a reference, ensure that the time synchronization error between voltage phase detection and subsequent closing command meets the preset delay requirements; Determining the optimal closing time: Select the moment when the voltage amplitude is at its maximum (θ=90° or 270°) to close the circuit. At this time, the step voltage excitation is the strongest and the transient oscillation component amplitude is the largest.

[0027] The controller continuously calculates the instantaneous amplitude of the three-phase voltage. , , For voltage peak value, when the voltage amplitude of a certain phase is detected to be at [ , ], and phase When the temperature stabilizes within the preset range, i.e., 90°±1° or 270°±1°, it is determined to be the optimal closing time. Phase selection strategy: For single-phase high-resistance grounding faults: prioritize selecting the faulty phase (determined by zero-sequence current and voltage characteristics) to ensure that the excitation signal directly acts on the circuit where the fault point is located; Three-phase fault or inability to determine the faulty phase: Perform simultaneous closing of all three phases to ensure that at least one phase can generate effective excitation; Special scenario: If the residual voltage of the line is detected to be out of phase with the power supply voltage, the circuit breaker can be closed at θ=0° (voltage zero crossing point) to avoid excessive closing inrush current. However, the sampling rate (≥500kHz) needs to be increased simultaneously to compensate for the insufficient amplitude of transient components.

[0028] The primary and secondary integrated circuit breaker adopts a fast permanent magnet mechanism with a mechanical action time of ≤10ms (from receiving the command to the contact closing) and an action time dispersion of ≤±0.5ms; Because the mechanical action has a fixed delay (obtained by actual measurement and stored in the controller), the controller adopts predictive closing logic: when it detects that the voltage phase is about to reach the target value (such as 90°), it sends the closing command in advance with a fixed delay time to ensure that the contact is exactly at the target phase at the moment of closing.

[0029] The average value and dispersion of the fixed delay of mechanical action time are updated quarterly through on-site tests. Combined with the microsecond-level timing function of FPGA, the closing phase error is ≤±1°.

[0030] The closing command is sent through a high-speed bus (such as CANopen, with a transmission delay of ≤10μs) between the controller and the actuator to avoid the transmission delay affecting the phase accuracy.

[0031] Simultaneously with the closing command, transient current and voltage data within 2 to 10 ms are collected at a sampling rate of 100 kHz to 1 MHz, stored after anti-interference processing, and the data quality is determined. Specifically, it includes: Transient oscillation frequency Typically, for frequencies between 10kHz and 100kHz (when the power distribution line length is 1 to 10km), according to the Nyquist sampling theorem, the sampling rate needs to be ≥2. (200kHz), considering the requirements of signal filtering and feature extraction, the actual sampling rate is configured as 100kHz~1MHz (1MHz is selected when the line length is short, and 100kHz is selected when the line length is long).

[0032] Transient oscillations are a decay process, and the amplitude usually decays to less than 10% of the initial value within 2 to 10 ms (the decay is slower during high-resistance faults, so we take 10 ms; the decay is faster during low-resistance faults, so we take 2 ms). If the acquisition time is too short, key oscillation information will be lost, and if it is too long, redundant data will be introduced (increasing the amount of computation). Acquisition channel configuration: Synchronous acquisition of transient current (ECT acquisition, range 0~100A), transient voltage (EVT data acquisition, range 0~1.2) Dual-channel data is used for joint fitting to improve parameter identification accuracy; Data acquisition is triggered by instruction hard triggering, and the closing instruction and the acquisition start instruction are output synchronously through the same FPGA pin; The acquisition module has a built-in circular buffer that pre-stores voltage and current data within 1ms before triggering (1000 sampling points at a sampling rate of 1MHz) to ensure the capture of the residual voltage and residual current status of the line before closing, providing a reference for signal preprocessing. If no contact closure signal is detected within 5ms after the closing command is issued (via feedback from auxiliary contacts), the data acquisition will automatically stop and be marked as excitation failure. Hardware anti-interference measures: The signal cables of ECT / EVT use shielded twisted pair cables (shielding layer grounding resistance ≤1Ω), and the acquisition module has a built-in common mode rejection circuit to avoid power frequency interference and electromagnetic radiation interference; Data preprocessing: The acquired raw data is converted by a 12-bit ADC and then digitally filtered (FIR low-pass filter, cutoff frequency = sampling rate / 5, such as 200kHz cutoff frequency when sampling at 1MHz) to filter out high-frequency noise (>200kHz) and retain effective transient components. Data storage method: The collected data is stored in high-speed flash memory and uses binary format (to reduce storage space occupation). Each data frame contains a timestamp, channel identifier, and sampled value, which facilitates subsequent data traceability and analysis. Data quality assessment criteria: Signal amplitude: peak transient current ≥ Ensure sufficient signal strength to avoid being drowned out by noise; Signal-to-noise ratio: The ratio of effective signal amplitude to noise amplitude is ≥15dB (noise amplitude is defined as the residual value in the acquired data after removing the oscillation component); Number of oscillations: Transient oscillations ≥ 3 cycles within the acquisition time (to ensure that a stable oscillation frequency can be extracted).

[0033] The upstream line of the fault point is simplified into a second-order equivalent circuit of Rf-LC, the transient current equation is derived, and the mathematical relationship between the transient oscillation frequency and the line parameters and the fault distance is established. Specifically, it includes: Original circuit model: The power distribution line is a distributed parameter circuit, and the length of the line upstream of the fault point is... (Fault distance), unit length parameter is , , (Resistance per unit length), the fault point is high resistance. Grounding; Simplified logic under high-frequency transients: transient oscillation frequency (10kHz~100kHz) is much higher than the power frequency (50Hz), at which point the line resistance effect... Compared to inductors and capacitor Negligible (impedance) , , ),when =50kHz, / ≈100, / ≈0.01, The impact is negligible, therefore it is simplified to Second-order series equivalent circuit For the transition resistance at the fault point, , ; According to Kirchhoff's voltage law, the voltage balance equation of the equivalent circuit after closing is: ; The step voltage injected for closing the circuit breaker. , For the closing phase, at 90° ; Regarding time Taking the derivative, we obtain the second-order linear nonhomogeneous differential equation: ; because For step voltage, Given the impulse function, the solution to the equation is divided into steady-state components. With transient components : steady-state components Generated by power frequency voltage excitation, the expression is: ,in , ; Transient components Determined by the inherent characteristics of the circuit, it is a damped oscillation component, expressed as follows: ,in, Attenuation coefficient ,Depend on and Decide, The bigger, The smaller the value, the faster the decay. Natural oscillation frequency ,when When smaller, ≤1 can be simplified to ; For transient component amplitude, The initial phase angle of the transient component (determined by the initial state of the circuit at the moment of closing); Therefore, the general expression for transient current is: ; For transient component amplitude, The initial phase angle of the transient component. The attenuation coefficient is... The natural oscillation frequency, Let be the amplitude of the power frequency steady-state component in the transient current. It is the power frequency angular frequency. The initial phase angle is the steady-state phase angle of the power frequency component.

[0034] It also includes the derivation of the correlation between physical parameters and fault distance: Relationship between line parameters and fault distance: Inductance per unit length of distribution line ,capacitance It is a fixed value (determined by the conductor type and circuit structure, therefore the total inductance of the line upstream of the fault point). Total capacitance ( (Fault distance, in km). The relationship between oscillation frequency and line parameters: (from...) Substitute , We can obtain: ; Fault distance calculation formula: Simplify the above formula to obtain the fault distance. The expression: ;in, This is the transient oscillation frequency.

[0035] Explanation of key model parameters: Power frequency angular frequency At 50Hz =314 rad / s, at 60 Hz =377rad / s, configured according to the actual power grid frequency; Attenuation coefficient The value range is usually 100~1000 rad / s (for high-resistance faults). big, Large, rapid oscillation decay; low resistance fault. Small, long oscillation duration); Transient oscillation frequency When the line length is 1~10km, Typically 10kHz~100kHz.

[0036] After preprocessing the transient signal, the Prony algorithm is used to extract the oscillation frequency and attenuation coefficient. The fault distance and transition resistance are calculated iteratively, and the results are output after consistency verification. Specifically, it includes: The acquired signals are preprocessed, including DC component removal, power frequency component filtering, and signal smoothing. DC component removal: Acquired transient current It may contain DC offset (caused by hysteresis effect during closing or zero drift of the sensor), which is removed using the averaging method; Power frequency component filtering: FIR band-stop filters are used to filter out power frequency fundamental and harmonic components; Signal smoothing: Moving average filtering (window length = 5 sampling points) is used to remove residual noise after filtering, ensuring smooth signal waveform and facilitating subsequent fitting; The above signal preprocessing process is a direct reference to existing technology and will not be elaborated here.

[0037] Feature parameter extraction: The Prony algorithm works by fitting a discrete-time signal using a set of complex exponential functions. It can simultaneously extract the signal's amplitude, frequency, attenuation coefficient, and initial phase angle, making it suitable for parameter identification of damped oscillating signals. Its discrete form is as follows: ,in, The order of the oscillation component of the signal (in this scheme) =1, because the transient signal mainly contains a main oscillation component. The sampling period is For fitting error, , , , The first The amplitude, attenuation coefficient, angular frequency, and initial phase angle of each component.

[0038] Algorithm implementation steps: Select the 2-5ms data segment with the largest amplitude from the filtered signal (including the complete oscillation period to avoid boundary effects), data length = Sampling rate × Truncation time (e.g., when sampling at 1MHz, 2ms is 2000 sampling points); Constructing the Hankel matrix : ; in, The number of columns in the matrix is ​​usually taken as... / 2 (to ensure the matrix is ​​full rank); Hankel matrix Perform SVD decomposition and determine the signal order based on the singular value attenuation characteristics. (In this scheme, p=1); Solve using the least squares method The characteristic equation is used to obtain the eigenvalues. , ; It is the attenuation coefficient of the transient oscillation component (corresponding to the parameter in the transient current expression that controls the decay rate of the oscillation amplitude). The imaginary unit satisfies ; It is the angular frequency of the transient oscillation component (corresponding to the angular frequency of the oscillation part in the transient current expression); Calculate the attenuation coefficient from the eigenvalues angular frequency oscillation frequency ; ; ; ; The result was obtained by fitting using the least squares method. and ; The amplitude of the corresponding transient oscillation component reflects the initial amplitude of the transient signal; The initial phase angle of the corresponding transient oscillation component reflects the phase state of the transient signal at the initial moment.

[0039] (Transient component amplitude) and The initial phase angle is the core parameter of the complete waveform of the transient signal. The fitted transient oscillation waveform can be reconstructed through these two parameters and compared with the actual acquired signal to determine whether the fitting error of the Prony algorithm is within a reasonable range (if the fitted waveform deviates too much from the actual signal, it means that the frequency and attenuation coefficient extracted later may be unreliable).

[0040] Based on attenuation coefficient With transition resistance correlation formula , combined ( (Based on the preliminary calculated fault distance), we can obtain: ; because computational dependency ,and right The impact is relatively small, therefore the optimization process using the iterative method is as follows: Depend on Preliminary calculations ; ; Substitution Formula calculation ; ,Will and Substituting into the formula, we obtain the preliminary transition resistance. ; consider right Correction, recalculation ; Calculate the corrected Then, it is converted into an oscillation frequency: ; Depend on calculate Iterate 2-3 times until If the change is less than the preset threshold (≤0.1km), the final fault distance is obtained. and transition resistance ; Among them, the obtained Substitute into the fault distance formula Calculate the distance to the second fault. .

[0041] It also includes fault distance inversion and result output: The final extracted oscillation frequency Substitute into the distance formula: ;in, and The preloaded line unit length parameters (calibrated by on-site measurement); If transient voltage was collected simultaneously Then the same method is used to extract. oscillation frequency ,calculate When | | When the preset requirement is met (≤0.2km), the effective distance is output. Otherwise, mark the ranging as suspicious and take the average of the two values; Output final fault distance (Accuracy ≤ ±0.5km), Transition Resistance (Accuracy ≤ ±10%), ranging confidence level (based on fitting error and consistency verification results, divided into three levels: high / medium / low).

[0042] Obtaining ranging confidence: Fitting error determination: Based on the fitting error of the Prony algorithm for transient signals (current / voltage): If the root mean square (RMS) of the fitting error is ≤0.05A (current signal) or ≤0.5%. (Voltage signal) is judged to have excellent fitting quality; If the fitting error is between 0.05A and 0.1A (or 0.5%) ~1% The fit quality is considered average. If the fitting error is >0.1A (or >1%) () was judged as poor fitting quality.

[0043] Consistency verification judgment: Compare the difference between the fault distance calculated by transient current and the fault distance calculated by transient voltage: If the distance difference is ≤0.2km, the results are considered to have high consistency. If the distance difference is between 0.2km and 0.5km, the result is considered to be consistent. If the distance difference is greater than 0.5km, the results are considered to have low consistency.

[0044] The grades are determined by combining the results of the two factors mentioned above: High confidence level: Excellent fit quality and high consistency of results; Medium confidence level: Medium fit quality or medium consistency of results (either one is satisfied); Low confidence: poor fit quality or low consistency of results (either one of the following is met).

[0045] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0046] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

[0047] It should be noted that, in this document, the use of relational terms such as "first" and "second" is merely for distinguishing one entity or operation from another, and does not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "include," "contain," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the statement "includes a…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0048] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0049] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0050] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0051] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0052] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0053] The above description is merely a specific embodiment of this application, but the scope of protection of this application 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 this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0054] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for fault location in power distribution lines based on a primary and secondary integrated pole-mounted circuit breaker, characterized in that, include: After the primary and secondary integrated circuit breakers detect line faults and trip, the fault type is classified by edge computing, conventional reclosing is blocked, and hardware reset and line parameter preloading are completed before ranging. The controller detects the phase of the voltage on the power supply side in real time, and controls the circuit breaker to select and close the circuit at the peak of the voltage amplitude, injecting a high-frequency transient excitation signal into the line. Simultaneously with the closing command, transient current and voltage data within 2 to 10 ms are collected at a sampling rate of 100 kHz to 1 MHz, and the data quality is determined. The upstream line of the fault point is simplified into a second-order equivalent circuit, the transient current equation is derived, and the mathematical relationship between the transient oscillation frequency and the line parameters and the fault distance is established. After preprocessing the transient signal, the oscillation frequency and attenuation coefficient are extracted, and the fault distance and transition resistance are calculated iteratively. The results are then output after consistency verification.

2. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 1, characterized in that, After the primary and secondary integrated circuit breakers detect a line fault and trip, the fault type is classified through edge computing. Conventional reclosing is then blocked, and hardware reset and line parameter preloading are completed before ranging. Specifically, this includes: The three-phase current and voltage signals of the line are monitored in real time through current transformers, electronic voltage transformers and fault detection modules. The fault detection module uses overcurrent detection, grounding fault detection, and high-resistance fault screening to initially determine line faults. When the fault determination conditions are met, the circuit breaker controller sends a trip command to the actuator; Acquire power frequency current and voltage data, including three-phase current, within a preset time period before tripping. / / Three-phase voltage / / Zero-sequence current Zero-sequence voltage .

3. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 2, characterized in that, Also includes: like > And the fault current is greater than The fault is determined to be a metallic grounding / low-resistance short circuit; routine reclosing is then performed. like > , <and fault current < Meanwhile, the voltage drop was 10%. The fault is identified as a high-resistance grounding fault and marked as a distance measurement mode. If the fault current fluctuates intermittently and the voltage does not drop continuously: it is determined to be an intermittent arc fault and marked as a distance measurement mode; After marking the distance measurement mode, the controller issues a blocking command to prohibit blind reclosing within a preset time. Read the basic parameters of the current line.

4. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 1, characterized in that, The controller monitors the voltage phase on the power supply side in real time, and controls the circuit breaker to select and close phases at the peak of the voltage amplitude, injecting high-frequency transient excitation signals into the line, specifically including: Target of testing: Three-phase voltage on the power supply side / / ; Extract the fundamental voltage component and calculate the real-time phase. ; The controller continuously calculates the instantaneous amplitude of the three-phase voltage. When the voltage amplitude of a certain phase is detected to be at [ , ], and phase When the circuit stabilizes within the preset range, it is determined to be the optimal closing time. Single-phase high-resistance ground fault: Select the phase that is connected to the faulty phase; If there is a three-phase fault or the faulty phase cannot be determined: perform simultaneous closing of all three phases.

5. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 1, characterized in that, Simultaneously with the closing command, transient current and voltage data within 2-10ms are acquired at a sampling rate of 100kHz~1MHz, and the data quality is determined, specifically including: Synchronous acquisition of transient current Transient voltage ; Data acquisition is triggered by instruction hard triggering, and the closing instruction and the acquisition start instruction are output synchronously through the same FPGA pin; The acquisition module has a built-in circular buffer to pre-store voltage and current data before triggering. Data quality assessment criteria: Signal amplitude: peak transient current ≥ ; Signal-to-noise ratio: The ratio of the effective signal amplitude to the noise amplitude is ≥15dB; Number of oscillations: Transient oscillations ≥ 3 cycles within the acquisition time.

6. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 1, characterized in that, The upstream line of the fault point is simplified into a second-order equivalent circuit. The transient current equation is derived, and the mathematical relationship between the transient oscillation frequency and line parameters and fault distance is established, specifically including: The power distribution line is a distributed parameter circuit, and the length of the line upstream of the fault point is... The unit length parameter is , , The fault point is high resistance. Grounding; Transient oscillation frequency Above the power frequency, the line's resistance effect... Compared to inductors and capacitor It can be ignored, therefore it is simplified to Second-order series equivalent circuit For the transition resistance at the fault point, , ; The voltage balance equation of the equivalent circuit after closing is: ; The step voltage injected for closing the circuit breaker; Regarding time Taking the derivative, we get ; because For step voltage, Given the impulse function, the solution to the equation is divided into steady-state components. With transient components : The general expression for transient current is: ; For transient component amplitude, The initial phase angle of the transient component. The attenuation coefficient is... The natural oscillation frequency, Let be the amplitude of the power frequency steady-state component in the transient current. It is the power frequency angular frequency. The initial phase angle is the steady-state phase angle of the power frequency component.

7. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 6, characterized in that, It also includes the derivation of the correlation between physical parameters and fault distance: Inductance per unit length of power distribution lines ,capacitance Since it is a fixed value, the total inductance of the line upstream of the fault point is... Total capacitance ; Substitute , We can obtain: ； Obtain the fault distance The expression: .

8. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 1, characterized in that, After preprocessing the transient signal, the oscillation frequency and attenuation coefficient are extracted. The fault distance and transition resistance are then calculated iteratively. After consistency verification, the results are output, including: The acquired signals are preprocessed, including DC component removal, power frequency component filtering, and signal smoothing. Select the 2-5ms data segment with the largest amplitude in the filtered signal, data length =Sampling rate × Truncation duration; Constructing the Hankel matrix Perform SVD decomposition and determine the signal order based on the singular value attenuation characteristics. ; Solve The characteristic equation is used to obtain the eigenvalues. ; Calculate the attenuation coefficient from the eigenvalues angular frequency oscillation frequency ; The result was obtained by fitting using the least squares method. and ; The amplitude of the corresponding transient oscillation component; The initial phase angle corresponding to the transient oscillation component.

9. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 8, characterized in that, Also includes: Based on attenuation coefficient resistance , combined We can obtain: ; The optimization process is as follows: Depend on Preliminary calculations ; Substitution Formula calculation ; consider right Correction, recalculation ; Depend on calculate Iterate 2-3 times until The final fault distance is obtained when the change is less than a preset threshold. and transition resistance .

10. The method for fault location of distribution lines based on a primary and secondary integrated pole-mounted circuit breaker according to claim 1, characterized in that, It also includes fault distance inversion and result output: The final extracted oscillation frequency Substitute into the fault distance formula: ;in, and For preloaded line unit length parameters; If transient voltage was collected simultaneously Then extract oscillation frequency ,calculate When | | When the preset requirements are met, output the effective distance. Otherwise, mark the ranging as suspicious and take the average of the two values; Output final fault distance Transition resistance Distance measurement confidence level.

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