A method and device for fault location of a traveling wave at an intermediate point on a three-phase line

Abstract

The application discloses a three-line intermediate measuring point traveling wave fault location method and device, and belongs to the technical field of power transmission line fault location. The method adopts intermediate measuring point fault phase current traveling wave data, calibrates initial traveling wave time and extracts subsequent wave head time sequence; takes the initial time as a reference to identify healthy interval reflected wave and arrival time in the full-length propagation time difference interval; determines the fault interval according to the relative polarity of the initial traveling wave; defines the time domain healthy interval with the initial and the reflected wave time, and counts the number of homopolar wave heads; if the number is greater than or equal to 1, it is a weak mode, and the most significant homopolar wave head in the interval is taken as the first transmitted wave to calculate the fault distance; otherwise, it is a strong mode, and the most significant homopolar wave head in the lag interval is taken as the fault point reflected wave to calculate the fault distance; and the fault interval and distance are output. The application solves the problems of reflected wave identification and fault interval determination, and realizes accurate and rapid fault location.

Description

Technical Field

[0001] This invention relates to the field of transmission line fault location technology, and in particular to a method and device for locating traveling wave faults at intermediate measuring points on a Sany transmission line. Background Technology

[0002] Reliable and accurate fault location on transmission lines is crucial for improving the targeting of inspections, reducing outage duration, ensuring power transmission capacity, and mitigating congestion and power outage losses. The traveling wave fault location principle is unaffected by operating conditions and transition resistance, and theoretically boasts high accuracy. With the construction of new power systems, higher demands are being placed on the reliability and accuracy of line fault location. Fault traveling wave technology is receiving increasing attention, making it imperative to expand its application scope and enhance its effectiveness.

[0003] Traditional station-end traveling wave ranging relies on traveling waves collected from multiple outgoing lines by instrument transformers within the substation, and is divided into single-end and double-end methods. The double-end method only requires detecting the time difference between the arrival times of the initial traveling wave at both ends of the line to calculate the fault location. It is simple in principle and widely applicable, but it is costly and requires clock synchronization at both ends of the acquisition device. The single-end method does not require clock synchronization or communication at both ends, making it economical. It uses the time difference between two arrival times at the measurement point to measure the distance; however, it is difficult to reliably identify the reflected wave from the fault point, limiting its positioning accuracy. Compared to station-end traveling waves, traveling waves observed at distributed measurement points along the line are less affected by the transmission links such as instrument transformers and secondary cables, have higher waveform quality, and provide shorter fault location sections. The double-end and multi-end positioning principles are applicable to the vast majority of faults.

[0004] However, for distributed traveling wave measurement points that only perform dual-end and multi-end ranging based on the initial traveling wave of a fault, their wave recording capability and waveform value have not been fully explored, and the subsequent reflected wave information contained in the traveling wave has not been effectively utilized, which limits the further improvement of distributed traveling wave ranging methods. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems in the related art.

[0006] To address this issue, this invention proposes a method for determining fault location at intermediate measuring points on a Sany railway line using traveling wave data. The method involves collecting traveling wave data of the fault phase current at the intermediate measuring point, calibrating the initial traveling wave time, and extracting subsequent wavefront sequences. Using the initial traveling wave as a reference, the reflected wave and its relative polarity within the healthy interval are identified, uniquely determining the fault interval. The healthy interval in the time domain is defined using the initial traveling wave and the reflected wave, and the number of wavefronts of the same polarity is counted: if the number is ≥1, it is determined to be a weak mode, and the most significant wavefront of the same polarity within the interval is taken as the first transmitted wave to calculate the fault distance; otherwise, it is a strong mode, and the reflected wave of the healthy interval is used as a reference to select a reflected wave of the same polarity to calculate the fault distance. This invention utilizes adaptive discrimination between the reflected wave of the healthy interval and the fault mode, solving the problem of reflected wave identification and achieving accurate and rapid fault location.

[0007] Another objective of this invention is to provide a traveling wave fault location device for intermediate measuring points of a Sany railway line.

[0008] To achieve the above objectives, this invention proposes a method for locating traveling wave faults at intermediate measuring points on a Sany railway line, comprising:

[0009] Collect fault phase current traveling wave data at intermediate measuring points along the transmission line, calibrate the arrival time of the initial traveling wave at the measuring point, and extract the arrival time series of the subsequent traveling wave wavefronts. Based on the arrival time of the initial traveling wave of the fault, within the time interval of the propagation time difference of the corresponding line, search for whether there is a wavefront in the subsequent wavefront arrival time sequence whose time difference with the initial traveling wave of the fault is equal to the propagation time difference of the line. If so, the corresponding wavefront is identified as a healthy interval reflected wave and the arrival time of the corresponding wavefront is marked. Calculate the relative polarity of the reflected wave in the healthy section and the initial traveling wave of the fault. Based on whether the polarities of the two are the same or opposite, uniquely determine whether the fault is located in the second half or the first half of the line section, thereby determining the fault section. A healthy time-domain interval is defined by the arrival time of the initial traveling wave of the fault and the arrival time of the reflected wave of the healthy interval. The number of wavefronts with the same polarity as the initial traveling wave of the fault within the corresponding interval is counted. Determine the line fault mode based on the number of wavefronts: If the number of wavefronts is greater than or equal to one, it is determined to be a weak mode, and the wavefront with the most significant amplitude of the same polarity is selected from the healthy time domain interval as the first transmitted wave of the fault interval. The fault distance is calculated based on the time difference between the corresponding transmitted wave and the initial traveling wave of the fault. If the number of wavefronts is less than one, it is determined to be a strong mode. Based on the arrival time of the reflected wave in the healthy interval, the wavefront with the most significant amplitude and the same polarity is selected as the reflected wave of the fault point within the lag time interval. The fault distance is calculated based on the time difference between the corresponding reflected wave and the initial traveling wave of the fault. The output shows the determined fault range and the calculated fault distance.

[0010] The method for locating traveling wave faults at intermediate measuring points on a Sany railway line according to an embodiment of the present invention may also have the following additional technical features: In one embodiment of the present invention, before acquiring the traveling wave data of the fault phase current, the method further includes: The total length parameters and empirical wave velocity parameters of the transmission line are obtained to determine the time interval of the propagation time difference of the corresponding total line length; wherein, the time interval is determined by the calculation relationship between the total line length and the empirical wave velocity.

[0011] In one embodiment of the present invention, searching for a wavefront whose initial traveling wave time difference from the fault is equal to the propagation time difference over the entire line length includes: Using the arrival time of the initial traveling wave of the fault as a reference, calculate the time difference between the arrival time of each subsequent wavefront and this reference time; Each time difference value is compared with the total propagation time difference value of the line. If a certain time difference value is equal to the total propagation time difference value of the line within the preset matching tolerance range, the corresponding wavefront is determined to be a healthy interval reflected wave, and the arrival time of the corresponding wavefront is recorded.

[0012] In one embodiment of the present invention, calculating the relative polarity of the reflected wave in the healthy region and the initial traveling wave of the fault includes: Obtain the current polarity sign of the reflected wave in the healthy section and the current polarity sign of the initial traveling wave of the fault, respectively; compare whether the two are consistent; if the polarities are opposite, it is determined that the fault is located in the first half of the line section; if the polarities are the same, it is determined that the fault is located in the second half of the line section.

[0013] In one embodiment of the present invention, defining the time-domain healthy interval and counting the number of wavefronts of the same polarity includes: The arrival time of the initial traveling wave of the fault is taken as the starting point of the interval, and the arrival time of the reflected wave of the healthy interval is taken as the ending point of the interval, and a healthy interval in the time domain is constructed. Retrieve all wavefronts within the healthy time-domain interval except for the start and end points, select wavefronts with the same polarity as the initial traveling wave of the fault, and count the number of selected wavefronts.

[0014] In one embodiment of the present invention, selecting the first transmitted wave of the fault region when the fault mode is determined to be weak includes: Obtain all wavefronts with the same polarity as the initial traveling wave of the fault within the healthy time-domain interval, and their corresponding modulus maxima amplitudes. Compare the magnitude maxima of each wavefront, determine the wavefront with the largest magnitude as the first transmitted wave in the fault zone, and record the arrival time of the corresponding wavefront.

[0015] In one embodiment of the present invention, selecting the reflected wave from the fault point when the mode is determined to be strong includes: Arrival time of reflected wave in the healthy interval Based on this, construct a lag time interval. ;in, For the total length of the line, For empirical wave speed; Search for all wavefronts with the same polarity as the initial traveling wave of the fault within the lag time interval, and compare the magnitude maxima of each wavefront; The wavefront with the largest amplitude is identified as the reflected wave from the fault point, and the arrival time of the corresponding wavefront is recorded. .

[0016] In one embodiment of the present invention, calculating the fault distance based on the first transmitted wave of the fault section includes: Calculate the arrival time of the first transmitted wave in the fault section. Arrival time of the initial traveling wave of the fault Time difference between them; Using formula Calculate the fault distance; where, For empirical wave speed, Taking -1, we obtain the distance from the fault point to the busbar at the beginning of the line. .

[0017] In one embodiment of the present invention, calculating the fault distance based on the reflected wave from the fault point includes: Calculate the arrival time of the reflected wave at the fault point Arrival time of the initial traveling wave of the fault Time difference between them; Using formula Calculate the fault distance; where, For empirical wave speed, Taking 1, we obtain the distance from the fault point to the busbar at the beginning of the line. .

[0018] To achieve the above objectives, another aspect of the present invention provides a traveling wave fault location device for intermediate measuring points of a Sany railway line, comprising: The data calibration module is used to collect fault phase current traveling wave data at intermediate measuring points along the transmission line, calibrate the time when the initial traveling wave of the fault arrives at the measuring point, and extract the arrival time sequence of the subsequent traveling wave wavefronts. The reflection recognition module is used to search within the time interval of the propagation time difference of the entire line length, based on the arrival time of the initial traveling wave of the fault, to see if there is a wavefront in the subsequent wavefront arrival time sequence where the time difference between the wavefront and the initial traveling wave of the fault is equal to the propagation time difference of the entire line length. If such a wavefront exists, the corresponding wavefront is identified as a healthy interval reflected wave and the arrival time of the corresponding wavefront is marked. The section determination module is used to calculate the relative polarity of the reflected wave in the healthy section and the initial traveling wave of the fault. Based on whether the polarities of the two are the same or opposite, it uniquely determines whether the fault is located in the second half or the first half of the line section, thereby determining the fault section. The wavefront statistics module is used to define a healthy time-domain interval by the arrival time of the initial traveling wave of the fault and the arrival time of the reflected wave of the healthy interval, and to count the number of wavefronts with the same polarity as the initial traveling wave of the fault within the corresponding interval. The modal ranging module is used to determine the line fault mode based on the number of wavefronts: if the number of wavefronts is greater than or equal to one, it is determined to be a weak mode, and the wavefront with the most significant amplitude of the same polarity within the healthy time domain is selected as the first transmitted wave of the fault section, and the fault distance is calculated based on the time difference between the corresponding transmitted wave and the initial traveling wave of the fault; if the number of wavefronts is less than one, it is determined to be a strong mode, and the wavefront with the most significant amplitude of the same polarity within the lag time interval is selected as the reflected wave of the fault point based on the arrival time of the reflected wave in the healthy region, and the fault distance is calculated based on the time difference between the corresponding reflected wave and the initial traveling wave of the fault; the module outputs the determined fault section and the calculated fault distance.

[0019] This invention discloses a method and apparatus for determining fault location at intermediate measuring points on a Sany railway line using traveling wave data of the fault phase current at the intermediate measuring point. It identifies the reflected wave in the healthy section and determines the fault section based on the initial traveling wave. Then, it adaptively distinguishes between weak and strong modes based on the number of wavefronts of the same polarity within the healthy section in the time domain, and calculates the fault distance by selecting either the first transmitted wave or the reflected wave from the fault point. This method effectively solves the problems of unreliable identification of reflected waves from the fault point and complex fault section determination in existing single-end traveling wave ranging methods. It achieves an integrated solution for the entire process from traveling wave data acquisition, wavefront identification, mode discrimination to fault distance calculation, significantly improving the reliability and accuracy of line fault location and enhancing the adaptability and engineering practical value of the method under different fault modes.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of a method for locating traveling wave faults at intermediate measuring points on a Sany railway line according to an embodiment of the present invention. Figure 2 This is a fault traveling wave mesh diagram according to an embodiment of the present invention; Figure 3 This is an algorithm flowchart according to an embodiment of the present invention; Figure 4 This is a traveling wave diagram of the fault phase current according to an embodiment of the present invention; Figure 5 This is a wavelet transform modulus maxima diagram according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a traveling wave fault location device for intermediate measuring points of a Sany railway line according to an embodiment of the present invention. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] The following describes, with reference to the accompanying drawings, a method and apparatus for determining traveling wave faults at intermediate measuring points on a Sany railway line, according to an embodiment of the present invention.

[0025] The core idea of ​​this invention is to address the problems of unreliable identification of fault point reflected waves and complex fault interval determination in traditional single-end traveling wave ranging by constructing an intermediate measuring point traveling wave fault ranging method that covers the entire process of "data acquisition - wavefront identification - interval determination - mode adaptive ranging". First, traveling wave data of the fault phase current at the intermediate measuring point is collected, the initial traveling wave time is calibrated, and the subsequent wavefront sequence is extracted. Based on this, the healthy interval reflected wave is identified according to the propagation time difference along the entire line length, and the fault interval is uniquely determined based on its relative polarity with the initial traveling wave. Then, the healthy interval in the time domain is defined using the initial traveling wave and the healthy reflected wave, and the number of wavefronts of the same polarity is counted: if the number is ≥1, it is a weak mode, and the most significant wavefront of the same polarity within the interval is taken as the first transmitted wave to calculate the fault distance; otherwise, it is a strong mode, and the most significant wavefront of the same polarity within the lag interval is taken as the reference to calculate the fault distance. Through the above-mentioned technical path of "identification-judgment-modal differentiation-separate ranging", this invention transforms the traditional ranging method that relies on empirical judgment of a single reflected wave into an intelligent ranging system that can adapt to the strong and weak modes of faults, fully explore the characteristics of traveling wave sequences, and realize the integrated output of fault interval and distance, which significantly improves the reliability, accuracy and engineering applicability of single-end traveling wave ranging.

[0026] The following describes, with reference to the accompanying drawings, a method and apparatus for determining traveling wave faults at intermediate measuring points on a Sany railway line, according to an embodiment of the present invention.

[0027] like Figure 1 As shown, the method for locating traveling wave faults at intermediate measuring points on a Sany railway line according to the present invention includes the following steps: S1: Collect fault phase current traveling wave data at intermediate measuring points along the transmission line, calibrate the time when the initial traveling wave of the fault arrives at the measuring point, and extract the arrival time sequence of the subsequent traveling wave wavehead. S2, based on the arrival time of the initial traveling wave of the fault, within the time interval of the propagation time difference of the corresponding line, search whether there is a wavefront in the subsequent wavefront arrival time sequence where the time difference between the wavefront and the initial traveling wave of the fault is equal to the propagation time difference of the line. If it exists, the corresponding wavefront is identified as a healthy interval reflected wave and the arrival time of the corresponding wavefront is marked. S3, calculate the relative polarity of the reflected wave in the healthy section and the initial traveling wave of the fault. Based on whether the polarities of the two are the same or opposite, uniquely determine whether the fault is located in the second half or the first half of the line section, thereby determining the fault section. S4. Define a healthy time-domain interval by the arrival time of the initial traveling wave of the fault and the arrival time of the reflected wave of the healthy interval, and count the number of wavefronts with the same polarity as the initial traveling wave of the fault in the corresponding interval. S5, determine the line fault mode based on the number of wavefronts: If the number of wavefronts is greater than or equal to one, it is determined to be a weak mode, and the wavefront with the most significant amplitude of the same polarity is selected from the healthy time domain interval as the first transmitted wave of the fault interval. The fault distance is calculated based on the time difference between the corresponding transmitted wave and the initial traveling wave of the fault. If the number of wavefronts is less than one, it is determined to be a strong mode. Based on the arrival time of the reflected wave in the healthy interval, the wavefront with the most significant amplitude and the same polarity is selected as the reflected wave of the fault point within the lag time interval. The fault distance is calculated based on the time difference between the corresponding reflected wave and the initial traveling wave of the fault. The output shows the determined fault range and the calculated fault distance.

[0028] In general, a considerable number of power plant-to-station transmission lines and single-circuit terminal substations exist in the power grid. From a traveling wave perspective, these can be equivalent to "three-in-one" lines, with current transformers (CTs) arranged along the lines to divide them into... L A , L B Two intervals, such as Figure 2 As shown.

[0029] 1. Traveling wave characteristics.

[0030] by Figure 1 As shown L B interval f Taking a three-phase symmetrical fault as an example, when a fault occurs, there is one and only one faulty section in the line. L k A sound interval L s Continue to use L k , L sLet M represent the length of the two sections. The initial traveling wave of the fault first propagates along the faulty line towards both ends. Assuming the busbars M to N are the reference positive direction for the current traveling wave, the initial traveling wave ① observed at the continuous impedance measurement point TA can be expressed as: (1) In the formula, x This indicates the distance from the fault point to the busbar on the fault section side; v For empirical wave speed; Z C Wave impedance; k This is the fault interval characterization coefficient, where the fault is located in the section preceding the measuring points along the line. L A , k =-1; The fault is located in the rear section of the measuring points along the line. L B , k =1.

[0031] The initial traveling wave propagating into the healthy section of the line reaches the measuring point TA along the line, is fully transmitted into the healthy section without reflection, and is reflected back to the measuring point TA via the end busbar M. This traveling wave ② is defined as the healthy section reflected wave, and can be expressed as: (2) In the formula, β s To improve the voltage reflection coefficient at the busbar on the section side.

[0032] The reflected wave ③ at the fault point in the fault section of the healthy interval is represented as: (3) The initial traveling wave propagating into the fault section is reflected by its end bus N and transmitted back to the measurement point TA. This traveling wave ④ is defined as the transmitted wave of the fault section, and is expressed as: (4) In the formula, β k The voltage reflection coefficient at the busbar on the fault section side; n This represents the number of times the traveling wave is reflected by the busbar on the faulty section side.

[0033] Ignoring amplitude attenuation and time delay of the traveling wave propagating along the line, and considering the relative polarities of the reflected wave in the healthy section and the initial traveling wave of the fault, and the transmitted wave in the fault section and the reflected wave at the fault point, we have: (5a) (5b) It is evident that the relative polarity of the traveling wave depends on the location of the fault section of the line. When a fault occurs on a "Sanyi" line where the reflection wave coefficients of the two busbars at both ends are mutually exclusive, the fault section can be identified by the relative polarity of the reflected wave of the healthy section and the initial traveling wave of the fault. However, the reflected wave of the fault point and the transmitted wave of the fault section cannot be distinguished by polarity characteristics.

[0034] 2. Temporal boundary characteristics of intermediate measuring points along the line.

[0035] The first transmitted wave in the fault section can be represented as: (6) Based on the analysis of traveling wave propagation path and propagation time delay, the arrival times of the measuring points for the initial traveling wave, the reflected wave in the healthy section, the reflected wave at the fault point, and the first transmitted wave in the fault section are recorded as follows: t 0、 t 1. t 2. t t Then we have: (7) It is evident that the time delay between the reflected wave from the healthy section and the initial traveling wave of the fault is determined by the length of the healthy section and is a fixed value. The time delay between the reflected wave from the fault point and the initial traveling wave reflects the sum of the relative fault distances between the healthy section and the fault from the measuring point, while the time difference between the first transmitted wave from the fault section and the initial traveling wave reflects the distance of the fault from the busbar on the fault section side. Taking the reflected wave from the healthy section as a reference, and considering its propagation time delay with the first transmitted wave from the fault section, we have: (8) It can be seen that when the fault distance x > L s When the fault distance is [not specified], the subsequent wavefront of the reflected wave in the healthy interval contains the transmitted wave, making it impossible to eliminate the interference of the transmitted wave on the identification of the reflected wave at the fault point; when ... x < L s When the faulty section's transmitted wave arrives at the measuring point ahead of the healthy section's reflected wave, the faulty section's reflected wave lags behind the healthy section's reflected wave; that is, the two ranging wavefronts are bounded by the healthy section's reflected wave. x = L s At that time, there were: (9) If the measuring points along the line are arranged of equal length at the midpoint of the line, then... L k = L s Then the line must have no blind spots in ranging and x ∈(0, L kTherefore, any fault location on the line must satisfy the following condition. x < L s The intermediate measuring points along the line have time-series boundary characteristics, which can reliably identify the reflected waves of fault points and the reflected waves of healthy sections with the same polarity.

[0036] The measurement points along the line, arranged at the midpoint of the line, result in a time-series boundary characteristic for the ranging wavefront, with the reflected wavefront of the intact section as the boundary, thus enabling reliable identification of the ranging wavefront in terms of time sequence.

[0037] 3. Identification of line fault sections based on the inherent time difference and polarity of traveling waves at intermediate measuring points along the line.

[0038] Arrival time of the initial traveling wave of the fault t Using 0 as a baseline, search for the wavefront of the entire route corresponding to the subsequent arrival time difference, i.e., in ( t 0, t 0+2 L / v Within the range, determine the arrival time of the traveling wave at the intermediate measuring point along the line that satisfies equation (10). t i To improve the arrival time of reflected waves in the section t 1, then the healthy interval reflected wave is identified.

[0039] (10) In the formula, ε To match the tolerance, 1km can be used; t i for( t 0, t 0+2 L / v The arrival time of subsequent wavefronts within the range of ).

[0040] As can be seen from the above, the section of the line at the intermediate measuring point along the route... L A When a fault occurs, the initial traveling wave of the fault has the opposite polarity to the reflected wave of the healthy section; if the faulty section is a section downstream of the line... L B If the polarity of the initial traveling wave of the fault is consistent with that of the reflected wave of the healthy section, then the fault section can be identified by utilizing the polarity characteristics according to equation (11).

[0041] (11) In the formula, sgn( V 0, V 1) represents the relative polarity of the reflected wave in the healthy region and the initial traveling wave in the fault region, sgn( V 0, V 1) <0 indicates opposite polarity, sgn( V0, V 1) >0 indicates the same polarity.

[0042] Therefore, the polarity of the reflected wave in the healthy region, identified based on the inherent time difference of the traveling wave, relative to the initial traveling wave of the fault, can uniquely determine the fault region.

[0043] 4. Fault location based on traveling waves at intermediate measuring points along the line.

[0044] Based on the temporal boundary characteristics of the intermediate measuring points along the line, it can be seen that the first transmitted wave in the fault section must be within the healthy time domain, and no other traveling wave besides the transmitted wave in the fault section can reach this time domain. Whether the reflected waves traveling back and forth within the fault section can reach the intermediate measuring points along the line depends on the reflection and refraction intensity of the fault point, that is, whether there is a traveling wavefront in the healthy time domain depends on the line fault mode. Therefore, the line fault mode can be determined based on the wavefront quantity characteristics in the healthy time domain. The formula for calculating the wavefront quantity is as follows: (12) like Q s If ≥1, the line fault is a weak mode, and the ranging wavefront is the first transmitted wave in the fault section that leads the reflected wave in the healthy section; if Q s If the value is less than 1, the line fault is a strong mode, and the ranging wavefront is selected to reflect the fault point wave that lags behind the reflected wave of the healthy section.

[0045] The arrival time of the measuring point of the initial traveling wave of the fault t Using 0 as the baseline, calculate the healthy interval in the time domain ( t 0, t 1) The number of wavefronts with significantly higher amplitudes than the detection threshold. If wavefronts exist, the wavefront with the most significant amplitude characteristics is recorded as the first transmitted wave in the fault zone, with an arrival time of [time missing]. t t The absolute fault distance from the main busbar side of the line was calculated as follows: (13) Otherwise, the arrival time of the reflected wave in the healthy interval is used. t Using 1 as a baseline, search within its subsequent limited range ( t 1, t 1+ L / v The arrival time of the measured point of the reflected wave from the fault location is determined by the first wavefront of the same polarity to arrive with the largest amplitude. t 2. The distance of the fault from the main busbar side of the line is as follows: (14) This invention comprehensively utilizes the length of the transmission line section, the unique polarity of the "Sanyi" transmission line's structure with multiple outgoing lines at one end and a single outgoing line at the other, and the temporal boundary characteristics of measurements along the line's middle section. It can uniquely and reliably identify the reflected wave of the healthy section, the reflected wave of the fault point, the first transmitted wave of the fault section, and the fault section itself. Based on the number of wavefronts within the healthy section in the time domain, the fault mode of the line is determined, and then the corresponding ranging formula is selected to calculate the fault location. Based on this, a fault section identification and single-end ranging method based on the traveling wave of a single measuring point along the middle section of the "Sanyi" transmission line is formed.

[0046] The method of this invention effectively solves the problems of unreliable identification of fault point reflected waves and complex fault interval determination in existing single-end traveling wave ranging. It realizes the integrated solution of the entire process from traveling wave data acquisition, wavehead identification, interval determination, mode adaptation to fault distance calculation, which significantly improves the reliability and accuracy of line fault ranging and enhances the adaptability and engineering practical value of the method under different fault modes.

[0047] Furthermore, the algorithm flow of this embodiment of the invention is as follows: the fault section identification and single-end ranging algorithm flow of the traveling wave at the intermediate measuring point along the "Sanyi" transmission line is as follows: Figure 3 As shown, the specific steps are as follows: Step 1: Collect traveling wave data from measuring points along the line in phases and read the data for the entire line length. L .

[0048] Step 2: Select the fault line and phase based on the traveling wave data along the line, and obtain the arrival time series of the initial traveling wave of the fault phase and its subsequent wavefronts. t m .

[0049] Step 3: Take ɛ =1km matching tolerance, judgment time interval ( t 0, t 0+2 L / v Does there exist a wavehead moment within )? t i If equation (10) is satisfied, then the labeling is performed. t i To improve the arrival time of reflected waves in the interval t 1. Identify the healthy interval reflected wave. If the condition is not met, the healthy interval matching fails, and the algorithm process ends.

[0050] Step 4: After determining the healthy interval reflected wave, calculate the relative polarity of the healthy interval reflected wave and the initial traveling wave according to equation (11). If sgn( V 0, V 1) <0 indicates that the two are opposite in polarity, and the fault interval characterization coefficient k =-1, the fault is located in the first half of the line section.L A If sgn ( V 0, V 1) >0 indicates that the two have the same polarity, and the interval characterization coefficient k =1, the fault is located in the latter half of the line section. L B .

[0051] Step 5: Using the healthy interval reflected wave as a reference, calculate the time-domain healthy interval ( ) according to equation (12). t 0, t 1) The number of wavefronts of the same polarity within.

[0052] Step 6: According to step 5 Q s The calculation results determine the line fault mode. If the following conditions are met: (15) If the line fault is weak mode, the first transmitted wave ranging of the fault section should be selected, and the next step should be performed. If equation (15) is not satisfied, the line fault is strong mode, and the reflected wave ranging of the fault point should be selected, and step 8 should be executed.

[0053] Step 7: Using the reflection time of the healthy interval t Based on 1, a time-domain healthy interval is selected ( t 0, t 1) The moment of the same polarity wavefront where the internal amplitude characteristics are most significant t t And use equation (13) to calculate the distance from the fault point to the main busbar side of the line. x a .

[0054] Step 8: Using the reflection time of the healthy interval t Based on 1, select a time interval ( t 1, t 1+2 L / v The moment of the same polarity wavefront with the most significant amplitude characteristics within the wavefront. t 2. And use equation (14) to calculate the distance from the fault point to the main busbar side of the line. x a .

[0055] Step 9: Output the fault range based on the calculation results. L k and location of the fault x .

[0056] The algorithm of the method in this embodiment of the invention effectively solves the problems of difficult identification of reflected waves and complex fault interval determination in existing single-end traveling wave ranging. It realizes the integrated solution of unique fault interval identification and modal adaptive ranging, which significantly improves the reliability and accuracy of ranging.

[0057] The algorithm flow of this invention is applied to real-world scenarios. An example implementation is in PSCAD / EMTDC using... Figure 2 The simulation model of the 220kV transmission line topology shown is illustrated. The line has multiple outgoing busbars at its beginning and a single outgoing busbar at its end, with a total length of 100km. Measurement points are installed at 50km along the line. When a single-phase ground fault occurs at 36km, the transition resistance is 150Ω and the fault angle is 30°. Fault current data is collected phase-by-phase using a traveling wave recorder with a sampling rate of 1MHz. (Refer to...) Figure 3 The process shown, specifically the implementation steps are as follows: Step 1: Read the fault current traveling wave data at the measuring points along the line and the total length of the line. L =100km.

[0058] Step 2: Based on the fault phase selection results, obtain the initial traveling wave of the fault phase, and extract the fault phase current data at 900 points (150 before the fault wave and 750 after the fault wave). The waveform is as follows: Figure 4 As shown, wavelet transform is applied to extract the modulus maxima, and the arrival time series of the initial traveling wave and its subsequent wavefronts are obtained. t m The transformation result is as follows Figure 5 As shown.

[0059] Step 3: Extracting the time series data from Step 2 t m In the middle, the initial traveling wave time is determined. t 0 = 0.150ms, within the interval (0.150ms, 0.821ms), take the matching tolerance. ɛ =1km, empirical wave speed v =298km / ms, according to equation (10) for sound interval reflection wave matching, there exists a wavefront moment. t i =0.486ms satisfies the following formula: (16) Step 4: Matching the time t i The corresponding wavefront is a healthy interval reflected wave, arrival time t 1 = 0.486ms.

[0060] Step 5: Determine the relative polarities of the reflected wave and the initial traveling wave in the healthy interval according to equation (11). The two satisfy the following: (17) The two polarities are opposite, and the fault is located in the section upstream of the line. L A Interval characterization coefficient k =-1.

[0061] Step 6: Using the reflected wave in the healthy interval as a reference, calculate the number of wavefronts of the same polarity in the healthy interval (0.150ms, 0.486ms) in the time domain according to formula (12) and determine the fault mode: Q s =1, satisfying equation (15), the line fault is a weak mode, and the ranging wavefront should be selected as the first transmitted wave of the fault section that leads the reflected wave of the healthy section.

[0062] Step 7: Determine the arrival time of the reflected wave in the healthy interval. t Based on 1 = 0.486 ms, the wavefront with the most significant amplitude of the same polarity within the healthy time domain is selected and calibrated as the first transmitted wave in the fault zone, with the arrival time... t t =0.391ms.

[0063] Step 8: Calculate the distance from the fault point to the main busbar side according to formula (13): (18) Step 9: Output the fault range L A and fault distance x a =35.909km.

[0064] This invention utilizes PSCAD / EMTDC to build a simulation model of a 220kV transmission line with a total length of 100km and measuring points installed at 50km along the line. A single-phase ground fault is simulated at 36km, and traveling wave data of the fault phase current is collected at a sampling rate of 1MHz. Following the proposed algorithm: the initial traveling wave time is calibrated, the reflected wave in the healthy interval is matched and identified, and the fault is determined to be located in the preceding interval LA based on the relative polarity; the number of wavefronts of the same polarity in the healthy interval in the time domain is calculated (Qs=1), indicating a weak mode; the first transmitted wave in the fault interval is selected, and the fault distance is calculated to be 35.909km, with an error of only 91m compared to the actual fault location of 36km. This embodiment verifies that the proposed method can reliably identify the reflected wave type and adaptively determine the fault mode under different transition resistance and fault angle conditions, effectively solving the problem of difficult reflected wave identification in traditional single-end ranging, achieving accurate output of the fault interval and distance, and significantly improving the accuracy and engineering applicability of ranging.

[0065] To achieve the above invention, such as Figure 6As shown, this embodiment also provides a traveling wave fault location device 10 for intermediate measuring points of Sany lines. The device 10 includes: The data calibration module 100 is used to collect fault phase current traveling wave data at intermediate measuring points along the transmission line, calibrate the time when the initial traveling wave of the fault arrives at the measuring point, and extract the arrival time sequence of the subsequent traveling wave waveheads.

[0066] The reflection recognition module 200 is used to search, within the time interval of the propagation time difference of the corresponding line's full length, whether there is a wavefront in the subsequent wavefront arrival time sequence that has a time difference between the wavefront and the initial traveling wave of the fault equal to the propagation time difference of the line's full length, based on the arrival time of the initial traveling wave of the fault. If such a wavefront exists, the corresponding wavefront is identified as a healthy interval reflected wave and the arrival time of the corresponding wavefront is marked.

[0067] The section determination module 300 is used to calculate the relative polarity of the reflected wave in the healthy section and the initial traveling wave of the fault. Based on whether the polarities of the two are the same or opposite, it uniquely determines whether the fault is located in the second half or the first half of the line section, thereby determining the fault section.

[0068] The wavefront statistics module 400 is used to define a healthy time-domain interval by the arrival time of the initial traveling wave of the fault and the arrival time of the reflected wave of the healthy interval, and to count the number of wavefronts with the same polarity as the initial traveling wave of the fault within the corresponding interval.

[0069] The modal ranging module 500 is used to determine the line fault mode based on the number of wavefronts: if the number of wavefronts is greater than or equal to one, it is determined to be a weak mode, and the wavefront with the most significant amplitude of the same polarity within the healthy time domain is selected as the first transmitted wave of the fault section, and the fault distance is calculated based on the time difference between the corresponding transmitted wave and the initial traveling wave of the fault; if the number of wavefronts is less than one, it is determined to be a strong mode, and the wavefront with the most significant amplitude of the same polarity within the lag time interval is selected as the reflected wave of the fault point based on the arrival time of the reflected wave in the healthy region, and the fault distance is calculated based on the time difference between the corresponding reflected wave and the initial traveling wave of the fault; the determined fault section and the calculated fault distance are output.

[0070] The device of this invention effectively solves the problems of unreliable identification of fault point reflected waves and complex fault interval determination in existing single-ended traveling wave ranging devices. It can automatically adapt to weak-mode and strong-mode line faults, and select the first transmitted wave or the fault point reflected wave to calculate the fault distance, which significantly improves the reliability and accuracy of transmission line fault ranging and enhances the engineering applicability of the device under different fault modes and line structures.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A method for locating traveling wave faults at intermediate measuring points on a Sany railway line, characterized in that, include: Collect fault phase current traveling wave data at intermediate measuring points along the transmission line, calibrate the arrival time of the initial traveling wave at the measuring point, and extract the arrival time series of the subsequent traveling wave wavefronts. Based on the arrival time of the initial traveling wave of the fault, within the time interval of the propagation time difference of the corresponding line, search for whether there is a wavefront in the subsequent wavefront arrival time sequence whose time difference with the initial traveling wave of the fault is equal to the propagation time difference of the line. If so, the corresponding wavefront is identified as a healthy interval reflected wave and the arrival time of the corresponding wavefront is marked. Calculate the relative polarity of the reflected wave in the healthy section and the initial traveling wave of the fault. Based on whether the polarities of the two are the same or opposite, uniquely determine whether the fault is located in the second half or the first half of the line section, thereby determining the fault section. A healthy time-domain interval is defined by the arrival time of the initial traveling wave of the fault and the arrival time of the reflected wave of the healthy interval. The number of wavefronts with the same polarity as the initial traveling wave of the fault in the corresponding interval is counted. Determine the line fault mode based on the number of wavefronts: If the number of wavefronts is greater than or equal to one, it is determined to be a weak mode, and the wavefront with the most significant amplitude of the same polarity is selected from the healthy time domain interval as the first transmitted wave of the fault interval. The fault distance is calculated based on the time difference between the corresponding transmitted wave and the initial traveling wave of the fault. If the number of wavefronts is less than one, it is determined to be a strong mode. Based on the arrival time of the reflected wave in the healthy interval, the wavefront with the most significant amplitude and the same polarity is selected as the reflected wave of the fault point within the lag time interval. The fault distance is calculated based on the time difference between the corresponding reflected wave and the initial traveling wave of the fault. The output shows the determined fault range and the calculated fault distance.

2. The method according to claim 1, characterized in that, Before collecting the traveling wave data of the fault phase current, the following steps are also included: The total length parameters and empirical wave velocity parameters of the transmission line are obtained to determine the time interval of the propagation time difference of the corresponding total line length; wherein, the time interval is determined by the calculation relationship between the total line length and the empirical wave velocity.

3. The method according to claim 1, characterized in that, The wavefront whose initial traveling wave time difference between the search and fault is equal to the propagation time difference over the entire line length includes: Using the arrival time of the initial traveling wave of the fault as a reference, calculate the time difference between the arrival time of each subsequent wavefront and this reference time; Each time difference value is compared with the total propagation time difference value of the line. If a certain time difference value is equal to the total propagation time difference value of the line within the preset matching tolerance range, the corresponding wavefront is determined to be a healthy interval reflected wave, and the arrival time of the corresponding wavefront is recorded.

4. The method according to claim 1, characterized in that, Calculate the relative polarity of the reflected wave in the healthy region and the initial traveling wave of the fault, including: Obtain the current polarity sign of the reflected wave in the healthy section and the current polarity sign of the initial traveling wave of the fault, respectively; compare whether the two are consistent; if the polarities are opposite, it is determined that the fault is located in the first half of the line section; if the polarities are the same, it is determined that the fault is located in the second half of the line section.

5. The method according to claim 1, characterized in that, Define the healthy time-domain intervals and count the number of wavefronts of the same polarity, including: The arrival time of the initial traveling wave of the fault is taken as the starting point of the interval, and the arrival time of the reflected wave of the healthy interval is taken as the ending point of the interval, and a healthy interval in the time domain is constructed. Retrieve all wavefronts within the healthy time-domain interval except for the start and end points, select wavefronts with the same polarity as the initial traveling wave of the fault, and count the number of selected wavefronts.

6. The method according to claim 1, characterized in that, When the fault is determined to be a weak mode, the first transmitted wave in the fault region is selected, including: Obtain all wavefronts with the same polarity as the initial traveling wave of the fault within the healthy time-domain interval, and their corresponding modulus maxima amplitudes. Compare the magnitude maxima of each wavefront, identify the wavefront with the largest magnitude as the first transmitted wave in the fault zone, and record the arrival time of the corresponding wavefront.

7. The method according to claim 1, characterized in that, When the fault is determined to be a strong mode, the reflected wave from the fault point is selected, including: Arrival time of reflected wave in the healthy interval Based on this, construct a lag time interval. ;in, For the total length of the line, For empirical wave speed; Search for all wavefronts with the same polarity as the initial traveling wave of the fault within the lag time interval, and compare the magnitude maxima of each wavefront; The wavefront with the largest amplitude is identified as the reflected wave from the fault point, and the arrival time of the corresponding wavefront is recorded. .

8. The method according to claim 1, characterized in that, The fault distance is calculated based on the first transmitted wave in the fault section, including: Calculate the arrival time of the first transmitted wave in the fault section. Arrival time of the initial traveling wave of the fault Time difference between them; Using formula Calculate the fault distance; where, For empirical wave speed, Taking -1, we obtain the distance from the fault point to the busbar at the beginning of the line. .

9. The method according to claim 1, characterized in that, The fault distance is calculated based on the reflected wave from the fault point, including: Calculate the arrival time of the reflected wave at the fault point Arrival time of the initial traveling wave of the fault Time difference between them; Using formula Calculate the fault distance; where, For empirical wave speed, Taking 1, we obtain the distance from the fault point to the busbar at the beginning of the line. .

10. A traveling wave fault location device for intermediate measuring points on a Sany railway line, characterized in that, include: The data calibration module is used to collect fault phase current traveling wave data at intermediate measuring points along the transmission line, calibrate the time when the initial traveling wave of the fault arrives at the measuring point, and extract the arrival time sequence of the subsequent traveling wave wavefronts. The reflection recognition module is used to search within the time interval of the propagation time difference of the entire line length, based on the arrival time of the initial traveling wave of the fault, to see if there is a wavefront in the subsequent wavefront arrival time sequence where the time difference between the wavefront and the initial traveling wave of the fault is equal to the propagation time difference of the entire line length. If such a wavefront exists, the corresponding wavefront is identified as a healthy interval reflected wave and the arrival time of the corresponding wavefront is marked. The section determination module is used to calculate the relative polarity of the reflected wave in the healthy section and the initial traveling wave of the fault. Based on whether the polarities of the two are the same or opposite, it uniquely determines whether the fault is located in the second half or the first half of the line section, thereby determining the fault section. The wavefront statistics module is used to define a healthy time-domain interval by the arrival time of the initial traveling wave of the fault and the arrival time of the reflected wave of the healthy interval, and to count the number of wavefronts with the same polarity as the initial traveling wave of the fault within the corresponding interval. The modal ranging module is used to determine the line fault mode based on the number of wavefronts: if the number of wavefronts is greater than or equal to one, it is determined to be a weak mode, and the wavefront with the most significant amplitude of the same polarity within the healthy time domain is selected as the first transmitted wave of the fault section, and the fault distance is calculated based on the time difference between the corresponding transmitted wave and the initial traveling wave of the fault; if the number of wavefronts is less than one, it is determined to be a strong mode, and the wavefront with the most significant amplitude of the same polarity within the lag time interval is selected as the reflected wave of the fault point based on the arrival time of the reflected wave in the healthy region, and the fault distance is calculated based on the time difference between the corresponding reflected wave and the initial traveling wave of the fault; the module outputs the determined fault section and the calculated fault distance.

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