Method and system for locating traction power supply fault of electrified railway

Abstract

The application provides a traction power supply fault positioning method and system for an electrified railway. A fault voltage transient signal is collected. A local measurement point and an opposite measurement point where an initial fault traveling wave first arrives are identified according to the fault voltage transient signal. Joint time-frequency analysis is performed on voltage waveforms of the local measurement point and the opposite measurement point to obtain a dominant oscillation frequency sequence. An equivalent propagation time difference of the fault traveling wave arriving at the local measurement point and the opposite measurement point is identified according to a distribution characteristic of the dominant oscillation frequency sequence. A first estimated distance and a second estimated distance of a fault point are determined based on a known wave speed of a traction network line and the equivalent propagation time difference. A fault positioning mode is determined according to a sum of the first and second estimated distances and an actual total length of a line. A fault position point of the traction power supply of the electrified railway is identified based on the fault positioning mode. The technical solution provided by the application can achieve accurate positioning of the fault position point of the traction power supply of the electrified railway under the influence of complex transient waveforms.

Description

Technical Field

[0001] This application relates to the field of power supply fault location technology, and more specifically, to a method and system for locating traction power supply faults in electrified railways. Background Technology

[0002] With the development of smart grids, distribution automation systems and smart terminals are gradually being deployed. Power supply fault location can automatically collect information such as fault current and voltage, and achieve preliminary fault location through algorithm analysis. However, the distribution network has a complex structure, many branches, and difficulties such as intermittent faults and high impedance faults. The accuracy of a single method is limited. Therefore, current technologies are integrating multi-source data, traveling wave positioning, artificial intelligence and Internet of Things technologies to develop towards high-precision, fast self-healing intelligent fault location.

[0003] In existing power supply fault location methods, when a fault occurs, the intelligent terminal on the line monitors the fault current and generates an overcurrent signal. These signals are uploaded to the master station via the communication network. The master station system performs fault analysis based on the timing and logic information reported by the terminal to locate the fault location or fault range. However, in the location of traction power supply faults in electrified railways, due to the large number of impedance discontinuities in the electrified railway traction network, complex multiple reflections and superposition phenomena occur during the propagation of the fault traveling wave. Traditional traveling wave location methods rely on capturing the reflected wave of the first fault point. However, in the actual traction network, the reflected wave of the fault point is easily mixed with the inherent reflected wave of the line, forming a complex transient waveform. This makes it difficult to directly identify the arrival time of the reflected wave of the fault point through the time domain waveform, thus increasing the fault ranging error. Therefore, how to accurately locate the fault point of traction power supply in electrified railways under the influence of complex transient waveforms has become a difficult problem for the industry. Summary of the Invention

[0004] This application provides a method and system for locating traction power supply faults in electrified railways, which can accurately locate the fault points of traction power supply in electrified railways under the influence of complex transient waveforms.

[0005] In a first aspect, this application provides a method for locating traction power supply faults in electrified railways, comprising the following steps: The transient fault voltage signal between the contact wire and the rail is collected at the measurement point of the traction power supply network of the electrified railway. Based on the fault voltage transient signal, the measurement point on this side and the measurement point on the opposite side that are first reached by the initial traveling wave of the fault are identified. Joint time-frequency analysis is performed on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave at the fault point and the reflected traveling wave at the measurement point. Based on the distribution characteristics of the dominant oscillation frequency sequence, the equivalent propagation time difference between the fault traveling wave and the measurement point on the local side and the measurement point on the opposite side is identified. Then, based on the known wave velocity of the traction network line and the equivalent propagation time difference, the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point are calculated. The fault location mode of the traction power supply fault is determined based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points, and the fault location point of the electrified railway traction power supply network is identified based on the fault location mode.

[0006] In some embodiments, identifying the local and opposite measurement points where the initial traveling wave of the fault first arrives based on the fault voltage transient signal specifically includes: The fault voltage transient signal is preprocessed to obtain a preprocessed fault voltage transient signal; Based on the preprocessed fault voltage transient signal, the traveling wave sudden change feature is detected, and then the arrival time of the initial traveling wave of the fault corresponding to each measurement point is identified. The arrival times of the initial traveling wave of the fault at each measurement point are compared in time sequence to determine the measurement point that first detects the initial traveling wave of the fault as the measurement point on this side. Using the measurement point on this side as a reference, the first measurement point among the remaining measurement points that has a time difference between the arrival time of the initial traveling wave of the fault and the measurement point on this side is taken as the measurement point on the opposite side.

[0007] In some embodiments, joint time-frequency analysis is performed on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault to extract the dominant oscillation frequency sequence formed by the superposition of the traveling wave reflected from the fault point and the traveling wave reflected from the measurement point. Specifically, this includes: Based on the arrival time difference of the initial traveling wave of the fault between the measurement point on this side and the measurement point on the opposite side, the voltage waveforms on both sides within the preset time window are aligned on the time axis to obtain the aligned voltage waveforms on both sides. A wavelet time-frequency analysis was performed on the aligned two-sided voltage waveforms using the cross-correlation coefficient of the two-point signal to determine the joint time-frequency matrix of the two sides. The amplitude of the dual-sided joint time-frequency matrix is ​​normalized, and time-frequency units with amplitudes greater than a preset normalization threshold are extracted. Then, a set of candidate frequencies related to the superposition of the traveling wave reflected from the fault point and the traveling wave reflected from the measurement point are selected. The candidate frequency set is subjected to a two-sided frequency consistency check, and frequency components that co-occur on both sides and have coordinated amplitude change trends are retained and arranged in ascending order of frequency to obtain the dominant oscillation frequency sequence.

[0008] In some embodiments, identifying the equivalent propagation time difference between the fault traveling wave arriving at the local measurement point and the opposite measurement point based on the distribution characteristics of the dominant oscillation frequency sequence specifically includes: The frequency difference sequence is obtained by extracting the difference between adjacent frequency components from the dominant oscillation frequency sequence. Calculate the corresponding time interval sequence based on the frequency difference sequence; The equivalent propagation time difference between the fault traveling wave and the measurement point on the opposite side is calculated based on the time interval sequence.

[0009] In some embodiments, calculating the first estimated distance and the second estimated distance from the local measurement point and the opposite measurement point to the fault point based on the known wave velocity of the traction network line and the equivalent propagation time difference specifically includes: Obtain the known wave velocity of the traction network line and the actual total length of the line between the measurement point on this side and the measurement point on the opposite side; Calculate the estimated distance difference between the local measurement point, the opposite measurement point, and the fault point based on the known wave velocity and the equivalent propagation time difference. Based on the difference between the actual total length of the line and the estimated distance, a system of two linear equations in two variables is established for the first estimated distance and the second estimated distance; Solve the system of two linear equations to obtain the first and second estimated distances from the measurement point on the local side and the measurement point on the opposite side to the fault point.

[0010] In some embodiments, determining the fault location mode of the traction power supply fault based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points specifically includes: Calculate the sum of the first estimated distance and the second estimated distance to obtain the total estimated distance; The difference between the estimated total distance and the actual total length of the line between the two measurement points is calculated to obtain the length deviation value; The length deviation value is compared with a preset error threshold to determine whether the length deviation value is within the preset error threshold range. If the length deviation value is within the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the normal traveling wave location mode. If the length deviation value exceeds the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the traveling wave reflection abnormal location mode.

[0011] In some embodiments, a voltage sensor is used to collect transient fault voltage signals between the contact wire and the rail at measurement points in the traction power supply network of an electrified railway.

[0012] Secondly, this application provides a traction power supply fault location system for electrified railways, comprising: The acquisition module is used to acquire transient fault voltage signals between the contact wire and the rail at measurement points in the traction power supply network of electrified railways. The processing module is used to identify the local measurement point and the opposite measurement point where the initial traveling wave of the fault first arrives, based on the fault voltage transient signal. The processing module is also used to perform joint time-frequency analysis on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault, so as to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave at the fault point and the reflected traveling wave at the measurement point. The processing module is also used to identify the equivalent propagation time difference between the fault traveling wave and the measurement point on the local side and the measurement point on the opposite side based on the distribution characteristics of the dominant oscillation frequency sequence, and then calculate the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point based on the known wave velocity of the traction network line and the equivalent propagation time difference. The execution module is used to determine the fault location mode of the traction power supply fault based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points, and to identify the fault location point of the electrified railway traction power supply network based on the fault location mode.

[0013] Thirdly, this application provides a computer device, the computer device including a memory and a processor, the memory storing code, and the processor being configured to acquire the code and execute the above-described method for locating traction power supply faults in electrified railways.

[0014] Fourthly, this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for locating traction power supply faults in electrified railways.

[0015] The technical solutions provided by the embodiments disclosed in this application have the following beneficial effects: The traction power supply fault location method and system for electrified railways provided in this application firstly collects transient fault voltage signals between the contact wire and the rail at measurement points in the traction power supply network of the electrified railway; secondly, based on the transient fault voltage signals, the measurement points on the local side and the opposite side where the initial traveling wave of the fault first arrives are identified; furthermore, joint time-frequency analysis is performed on the voltage waveforms of the local side and the opposite side measurement points within a preset time window after the fault to extract the dominant oscillation frequency sequence formed by the superposition of the traveling wave reflected from the fault point and the traveling wave reflected from the measurement point; then, based on... The distribution characteristics of the dominant oscillation frequency sequence identify the equivalent propagation time difference between the fault traveling wave and the measurement point on the local side and the measurement point on the opposite side. Then, based on the known wave velocity of the traction network line and the equivalent propagation time difference, the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point are calculated. Finally, the fault location mode of the traction power supply fault is determined based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points, and the fault location point of the electrified railway traction power supply network is identified based on the fault location mode.

[0016] Therefore, this application can accurately locate fault points in the traction power supply of electrified railways under the influence of complex transient waveforms. Firstly, by collecting transient fault voltage signals between the contact wire and rail at measurement points in the traction power supply network, the transient characteristics of traveling waves caused by the fault can be identified, providing the original signal basis for subsequent fault characteristic analysis. Secondly, based on the transient fault voltage signals, the measurement points on the local and opposite sides where the initial traveling wave first arrives are identified, establishing a signal analysis framework for dual-point collaborative monitoring. This framework locates the reference point and paired monitoring point for traveling wave capture, avoiding the shortcomings of single-point measurement which is susceptible to electromagnetic interference and signal attenuation. Furthermore, joint time-frequency analysis is performed on the voltage waveforms within a preset time window after the fault at the local and opposite measurement points, and the dominant oscillation frequency sequence is extracted. Through the collaborative analysis of the dual-point signals, invalid frequency components such as power frequency, electromagnetic interference, and transient stray reflections can be effectively eliminated. This allows for the determination of the core time-frequency characteristics formed by the superposition of traveling waves reflected from the fault point and the measurement point, providing a feature basis strongly correlated with fault location for subsequent extraction of the traveling wave propagation time difference, thus avoiding fault location issues. Point reflection waves are easily mixed with inherent line reflection waves, forming complex transient waveforms that increase fault location errors. Then, based on the distribution characteristics of the dominant oscillation frequency sequence, the equivalent propagation time difference is identified. Combined with the known wave velocity of the traction network line, the first and second estimated distances from the two measurement points to the fault point are calculated. The travel wave propagation time difference is indirectly characterized by frequency characteristics, avoiding the time difference calculation errors caused by signal attenuation and reflection distortion that are common in traditional methods that directly extract the arrival time of the travel wave. Simultaneously, the distance from the two measurement points to the fault point is quantified, establishing preliminary distance constraints for the fault point. Finally, the fault location mode is determined based on the sum of the first and second estimated distances and the actual total line length between the two measurement points. The fault location point is identified based on this mode. The comparison of the length deviation value with a preset error threshold accurately distinguishes between normal travel wave and abnormal travel wave reflection modes, enabling fault location for different travel wave propagation scenarios. In summary, the technical solution provided in this application can accurately locate traction power supply fault points in electrified railways under the influence of complex transient waveforms. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an application scenario architecture for a traction power supply fault location method for electrified railways, as shown in some embodiments of this application. Figure 2 This is an exemplary flowchart of a traction power supply fault location method for electrified railways according to some embodiments of this application; Figure 3 This is an exemplary flowchart illustrating the determination of a local measurement point and a remote measurement point according to some embodiments of this application; Figure 4 This is a schematic diagram of the structure of a traction power supply fault location system for electrified railways according to some embodiments of this application; Figure 5 This is a schematic diagram of the structure of a computer device for implementing a traction power supply fault location method for electrified railways, according to some embodiments of this application. Detailed Implementation

[0018] To better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] refer to Figure 1 This figure is a schematic diagram of an application scenario architecture for a traction power supply fault location method for electrified railways according to some embodiments of this application. The application scenario architecture includes a data acquisition terminal, a communication network, and a server. The data acquisition terminal and the server are directly or indirectly connected through the communication network. The data acquisition terminal acquires transient fault voltage signals between the contact wire and the rail at measurement points in the traction power supply network of the electrified railway and uploads them to the server. The server identifies the local and opposite measurement points where the initial traveling wave of the fault first arrives based on the transient fault voltage signals. Joint time-frequency analysis is performed on the voltage waveforms of the local and opposite measurement points within a preset time window after the fault. The process involves extracting the dominant oscillation frequency sequence formed by the superposition of the traveling wave reflected from the fault point and the traveling wave reflected from the measurement point; identifying the equivalent propagation time difference between the fault traveling wave reaching the measurement point on the local side and the measurement point on the opposite side based on the distribution characteristics of the dominant oscillation frequency sequence; calculating the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point based on the known wave velocity of the traction network line and the equivalent propagation time difference; determining the fault location mode of the traction power supply fault based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points; and identifying the fault location point of the electrified railway traction power supply network based on the fault location mode.

[0020] refer to Figure 2 The figure is an exemplary flowchart of a traction power supply fault location method for electrified railways according to some embodiments of this application. The traction power supply fault location method for electrified railways mainly includes the following steps: In step 101, transient fault voltage signals between the contact wire and the rail are collected at the measurement points of the traction power supply network of the electrified railway.

[0021] It should be noted that the traction power supply network in this application refers to a dedicated power supply system that provides electrical energy to electric traction trains. Its core function is to introduce high-voltage electrical energy from the national grid, step it down at the traction substation and convert it into single-phase AC power suitable for locomotive use, and then transmit it to the train through the contact network (current-carrying conductors that slide along the pantograph) erected along the railway line. After the current passes through the train's traction equipment, it returns to the traction substation through the rails and / or a return path composed of dedicated return lines and negative feeders, thus forming a complete electrical circuit.

[0022] In specific implementation, a voltage sensor is used to collect transient fault voltage signals between the contact wire and the rail at measurement points in the traction power supply network of the electrified railway. Alternatively, in other embodiments, other acquisition devices can be used to collect these transient fault voltage signals at measurement points in the traction power supply network of the electrified railway; this is not a limitation. It should be noted that, in this application, the fault voltage transient signal refers to the decaying oscillating waveform of the voltage that changes drastically and instantaneously between the contact wire and the rail at the moment a short-circuit fault occurs in the traction power supply network; the fault voltage transient signal is essentially an electromagnetic traveling wave generated in the power grid by the impedance suddenly applied at the fault point. This traveling wave propagates along the line to both ends at a speed close to the speed of light, and due to the discontinuity of the line impedance, it undergoes complex reflections, thus forming a voltage waveform containing rich high-frequency components.

[0023] In step 102, the measurement points on the local side and the opposite side that are first reached by the initial traveling wave of the fault are identified based on the fault voltage transient signal.

[0024] In some embodiments, reference Figure 3 As shown in the figure, this is an exemplary flowchart illustrating the determination of the local measurement point and the opposite measurement point according to some embodiments of this application. In this embodiment, the identification of the local measurement point and the opposite measurement point that the initial traveling wave of the fault first arrives at based on the fault voltage transient signal can be achieved by the following steps: In step 1021, the fault voltage transient signal is preprocessed to obtain a preprocessed fault voltage transient signal; In step 1022, traveling wave abrupt change feature detection is performed based on the preprocessed fault voltage transient signal to identify the arrival time of the initial traveling wave of the fault at each measurement point. In step 1023, the arrival times of the initial traveling wave of the fault at each measurement point are compared in time sequence to determine the measurement point that first detects the initial traveling wave of the fault as the measurement point on this side. In step 1024, taking the measurement point on this side as the reference, the first measurement point among the remaining measurement points that has a time difference between the arrival time of the initial traveling wave of the fault and the measurement point on this side is taken as the measurement point on the opposite side.

[0025] In specific implementation, firstly, wavelet threshold denoising is used to preprocess the fault voltage transient signal to obtain a preprocessed fault voltage transient signal. In other embodiments, other signal denoising methods can also be used to preprocess the fault voltage transient signal; this is not limited here. The preprocessed fault voltage transient signal refers to the fault voltage transient electrical signal after denoising. Secondly, a first-order differential operation in the discrete-time domain is performed on the preprocessed fault voltage transient signal to obtain a differential signal. The absolute value of the differential signal is calculated to obtain an absolute value differential signal. Based on the statistical results of voltage signal fluctuation amplitude under normal operating conditions of the traction network, a traveling wave abrupt change judgment threshold is set. The absolute value differential signal is compared with the traveling wave abrupt change judgment threshold point by point. When the absolute value differential signal has three or more consecutive sampling points exceeding the traveling wave abrupt change judgment threshold, the timestamp corresponding to the first sampling point exceeding the threshold is determined as the fault of the corresponding measurement point. To determine the arrival time of the initial traveling wave of a fault, after traversing all measurement points in the traction power supply network, the arrival time of the initial traveling wave of the fault at each measurement point is output. The arrival time of the initial traveling wave of the fault refers to the first timestamp at which the voltage signal changes due to the initial traveling wave of the fault is detected at each measurement point. Then, the arrival times of the initial traveling wave of the fault at all measurement points are sorted in ascending order. The measurement point with the smallest value in the sorting result is extracted as the measurement point on this side that first detected the initial traveling wave of the fault. The measurement point on this side refers to the first measurement point in the traction power supply network to detect the initial traveling wave signal of the fault. Finally, using the arrival times of the initial traveling wave of the fault at this side measurement point and the arrival times of the initial traveling wave of the fault at the other measurement points as input, the arrival time difference of the initial traveling wave of the fault between the other measurement points and the measurement point on this side is calculated. All the obtained arrival time differences of the initial traveling wave of the fault are sorted in ascending order. The measurement point with the first arrival time difference of the initial traveling wave in the sorting result is extracted as the measurement point on the opposite side.

[0026] It should be noted that, in this application, the opposite measurement point refers to the measurement point with the smallest arrival time difference of the initial traveling wave of the fault with the measurement point on the local side. As the point that first captures the initial traveling wave of the fault, the local measurement point can provide the time starting point and reference signal of the fault traveling wave propagation, and establish a time anchor point for the analysis of the traveling wave propagation characteristics. The opposite measurement point, as the paired point with the local measurement point with the smallest arrival time difference of the traveling wave, can form a two-way monitoring coverage of a specific section of the traction network with the local measurement point. Through the fault voltage transient signal collected synchronously by the two points, the spatiotemporal correlation of the traveling wave propagation is constructed, providing dual-source data support for subsequent spectral feature analysis, extraction of the dominant oscillation frequency sequence, and calculation of the equivalent propagation time difference.

[0027] In step 103, joint time-frequency analysis is performed on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault, so as to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave at the fault point and the reflected traveling wave at the measurement point.

[0028] In some embodiments, joint time-frequency analysis is performed on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave from the fault point and the reflected traveling wave from the measurement point. This is achieved through the following steps: Based on the arrival time difference of the initial traveling wave of the fault between the measurement point on this side and the measurement point on the opposite side, the voltage waveforms on both sides within the preset time window are aligned on the time axis to obtain the aligned voltage waveforms on both sides. A wavelet time-frequency analysis was performed on the aligned two-sided voltage waveforms using the cross-correlation coefficient of the two-point signal to determine the joint time-frequency matrix of the two sides. The amplitude of the dual-sided joint time-frequency matrix is ​​normalized, and time-frequency units with amplitudes greater than a preset normalization threshold are extracted. Then, a set of candidate frequencies related to the superposition of the traveling wave reflected from the fault point and the traveling wave reflected from the measurement point are selected. The candidate frequency set is subjected to a two-sided frequency consistency check, and frequency components that co-occur on both sides and have coordinated amplitude change trends are retained and arranged in ascending order of frequency to obtain the dominant oscillation frequency sequence.

[0029] In specific implementation, firstly, based on the arrival time difference of the initial traveling wave of the fault between the measurement point on this side and the measurement point on the opposite side, the leading and lagging sides of the traveling wave in both measurement points are determined by the time difference value. Using the time axis of the voltage waveform of the leading side as a reference, the time axis interpolation step size of the voltage waveform of the lagging side is calculated according to the time difference. The sampling points of the voltage waveform of the lagging side are completed by linear interpolation, so that the number of sampling points of the time axis of the voltage waveforms on both sides is consistent and the triggering time of the initial traveling wave of the fault completely coincides on the time axis, thus completing the time axis alignment process. The aligned voltage waveforms of both sides are then output. The aligned voltage waveforms of both sides refer to the time... The time-domain waveforms of the voltage at the measurement points on both sides after axis correction are obtained. Next, using the aligned voltage waveforms as input, a db series wavelet basis adapted to the characteristics of the traction network fault traveling wave signal is selected as the basic wavelet. Based on actual needs, the sliding window length and window step size are set to match the duration of the traction network fault traveling wave characteristics, with the window length being half the window length. A sliding window cross-correlation algorithm is used to calculate the cross-correlation coefficient of the voltage waveforms on both sides window by window. This cross-correlation coefficient is used as the basis for adjusting the wavelet basis scale. When the cross-correlation coefficient is higher than the preset correlation coefficient, a db4 wavelet basis with a scale less than 2 is selected to improve the frequency resolution of the time-frequency analysis. When the cross-correlation coefficient is lower than the preset correlation coefficient, a db4 wavelet basis with a scale less than 2 is selected. To ensure the time-domain stability of the time-frequency analysis, a db4 wavelet basis with a scale greater than 7 is selected. Then, based on the adjusted wavelet basis, multi-scale wavelet time-frequency decomposition is performed synchronously on both sides of the voltage waveform to obtain the time-frequency matrices of each side. The independent time-frequency matrices of both sides are then concatenated along the same dimension according to the time sampling point dimension to construct a joint time-frequency matrix. This joint time-frequency matrix refers to a two-dimensional data matrix characterizing the time-domain distribution features and frequency components of the voltage waveforms on both sides. Finally, the joint time-frequency matrix is ​​processed using the maximum-minimum normalization method, where each time-frequency unit (i.e., the smallest constituent unit of the joint time-frequency matrix, consisting of a unique time sampling point and frequency) is processed. The amplitude of the voltage waveform after double-sided alignment at the corresponding time-frequency position is mapped to the [0,1] interval to obtain a normalized double-sided joint time-frequency matrix. Based on the amplitude statistical characteristics of the superimposed traveling wave signal of the traction network fault, a preset normalization threshold is set according to actual needs. The normalized amplitude is compared with the normalization threshold for each time-frequency unit. Time-frequency units with normalized amplitudes greater than the normalization threshold are extracted. Then, the frequencies corresponding to all extracted time-frequency units are combined into a candidate frequency set related to the superposition of the traveling wave reflected from the fault point and the traveling wave reflected from the measurement point. The candidate frequency set refers to the set of frequency components formed by the superposition of the traveling waves reflected from the fault and the measurement point.Finally, using the candidate frequency set as input, each frequency component is traversed, and each is checked to see if it coexists in the bilateral joint time-frequency matrix. Simultaneously, by calculating the slope of the amplitude change of the corresponding frequency components on both sides, it is determined whether the amplitude change trends are consistent. Frequency components that coexist on both sides and have consistent amplitude change trends are retained. These frequency components are then arranged in ascending order using a bubble sort method to obtain the dominant oscillation frequency sequence.

[0030] It should be noted that the dominant oscillation frequency sequence in this application refers to the set of frequency components arranged in an ordered manner, formed by the superposition of the traveling waves reflected from the fault point and the traveling waves reflected from the measurement point. After a fault occurs in the electrified railway traction network, the oscillation frequency characteristics formed by the superposition of the traveling waves reflected from the fault point and the traveling waves reflected from the measurement point are inherently related to the propagation characteristics of the traveling waves in the traction network line and the distance from the fault point to the measurement point. However, the fault voltage waveform may contain invalid frequency components such as power frequency, electromagnetic interference, and transient stray reflections. It is necessary to extract the truly stable dominant oscillation frequency sequence formed by the superposition of traveling waves through multiple rounds of screening and verification. This is to eliminate interference and lock in the core time-frequency characteristics that are strongly related to fault location. Therefore, by determining the dominant oscillation frequency sequence, accurate and effective frequency dimension data support can be provided for subsequent calculation of the equivalent propagation time difference of the fault traveling wave based on frequency characteristic analysis, avoiding calculation errors introduced by invalid frequency components.

[0031] In step 104, the equivalent propagation time difference between the fault traveling wave and the measurement point on the local side and the measurement point on the opposite side is identified based on the distribution characteristics of the dominant oscillation frequency sequence. Then, based on the known wave velocity of the traction network line and the equivalent propagation time difference, the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point are calculated.

[0032] In some embodiments, identifying the equivalent propagation time difference between the fault traveling wave arriving at the local measurement point and the opposite measurement point based on the distribution characteristics of the dominant oscillation frequency sequence is achieved through the following steps: The frequency difference sequence is obtained by extracting the difference between adjacent frequency components from the dominant oscillation frequency sequence. Calculate the corresponding time interval sequence based on the frequency difference sequence; The equivalent propagation time difference between the fault traveling wave and the measurement point on the opposite side is calculated based on the time interval sequence.

[0033] In specific implementation, firstly, using the dominant oscillation frequency sequence arranged in ascending order of frequency as input, all elements of the dominant oscillation frequency sequence are traversed in ascending index order. The difference between adjacent frequency components is calculated sequentially by subtracting the preceding element from the subsequent element. All difference results are then combined one by one according to the original frequency component order to obtain a frequency difference sequence. This frequency difference sequence is a one-dimensional numerical sequence composed of the differences between adjacent frequency components in the dominant oscillation frequency sequence arranged in corresponding index order. Next, based on the physical constitutive relationship between the oscillation frequency difference and oscillation period formed by the superposition of traction network fault traveling waves, each difference element in the frequency difference sequence is subjected to an element-wise reciprocal operation. All reciprocal calculation results are then combined one by one according to the original difference element order to obtain a time interval sequence. This time interval sequence is a one-dimensional numerical sequence characterizing the superposition oscillation period of the fault traveling wave. Finally, the mean of all time intervals in the time interval sequence is calculated, and the mean calculation result is used as the equivalent propagation time difference between the fault traveling wave reaching the local measurement point and the opposite measurement point.

[0034] It should be noted that the equivalent propagation time difference in this application refers to the time difference characterizing the propagation of the fault traveling wave to the measurement point on this side and the measurement point on the opposite side. Determining the equivalent propagation time difference can quantify the time difference characteristics of the fault traveling wave propagating to the measurement point on this side and the measurement point on the opposite side, avoiding the time difference calculation error caused by signal attenuation and reflection superposition interference when directly extracting the arrival time of the traveling wave in traditional traveling wave positioning.

[0035] In some embodiments, the calculation of the first and second estimated distances from the local measurement point and the opposite measurement point to the fault point based on the known wave velocity of the traction network line and the equivalent propagation time difference is achieved by the following steps: Obtain the known wave velocity of the traction network line and the actual total length of the line between the measurement point on this side and the measurement point on the opposite side; Calculate the estimated distance difference between the local measurement point, the opposite measurement point, and the fault point based on the known wave velocity and the equivalent propagation time difference. Based on the difference between the actual total length of the line and the estimated distance, a system of two linear equations in two variables is established for the first estimated distance and the second estimated distance; Solve the system of two linear equations to obtain the first and second estimated distances from the measurement point on the local side and the measurement point on the opposite side to the fault point.

[0036] In specific implementation, firstly, the known wave velocity of the traction network line is obtained from the inherent parameter database of the traction network line, and simultaneously, the actual total line length between the local and opposite measurement points, as determined by field measurements and line topology modeling, is obtained from the traction network GIS topology database. Secondly, the known wave velocity is numerically multiplied by the equivalent propagation time difference to obtain the estimated distance difference between the local and opposite measurement points to the fault point. The estimated distance difference refers to the difference between the distances from the local and opposite measurement points to the fault point. Then, the fault distance from the local measurement point to the fault point is set as the first estimated distance, and the fault distance from the opposite measurement point to the fault point is set as the second estimated distance. Finally, based on the known traveling wave propagation distance within the traction network monitoring section formed by the local and opposite measurement points where the fault point is located, the calculation is performed. The system of linear equations in two variables is constructed, with the actual total line length as the sum of the first and second estimated distances and the difference between the estimated distances as the difference between the first and second estimated distances. This system contains two independent linear equations with the first and second estimated distances as the two unknowns. The system of linear equations in two variables refers to a system of linear equations with a unique solution established using the first and second estimated distances as unknowns. Finally, using the system of linear equations in two variables as input, the system of equations is solved using the elimination method known in the art, thereby obtaining the first and second estimated distances from the corresponding measurement points on the local and opposite sides to the fault point.

[0037] It should be noted that the first estimated distance and the second estimated distance in this application refer to the preliminary estimated values ​​of the fault distance from the measurement point on this side and the measurement point on the opposite side to the fault point. Determining the first estimated distance and the second estimated distance can provide an initial distance benchmark for subsequent fault distance correction under positioning mode adaptation, line topology verification and accurate mapping of the final fault location point.

[0038] In step 105, the fault location mode of the traction power supply fault is determined based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points, and the fault location point of the electrified railway traction power supply network is identified based on the fault location mode.

[0039] In some embodiments, determining the fault location mode of the traction power supply fault based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points is achieved through the following steps: Calculate the sum of the first estimated distance and the second estimated distance to obtain the total estimated distance; The difference between the estimated total distance and the actual total length of the line between the two measurement points is calculated to obtain the length deviation value; The length deviation value is compared with a preset error threshold to determine whether the length deviation value is within the preset error threshold range. If the length deviation value is within the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the normal traveling wave location mode. If the length deviation value exceeds the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the traveling wave reflection abnormal location mode.

[0040] In specific implementation, firstly, the first estimated distance and the second estimated distance are added together to obtain the sum of estimated distances, which represents the total estimated distance from the two measurement points to the fault point. Secondly, the sum of estimated distances is calculated using the absolute value difference method, and the actual total line length between the two measurement points is calculated to obtain the length deviation value, which represents the degree of deviation between the estimated distance and the actual line length. Finally, the length deviation value is compared with a preset error threshold to determine whether the length deviation value is within the preset error threshold range. If the length deviation value is within the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the normal traveling wave location mode. If the length deviation value exceeds the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the traveling wave reflection abnormal location mode. The error threshold can be set according to actual needs and is not limited here.

[0041] It should be noted that the normal traveling wave positioning mode in this application refers to the fault positioning mode where the fault point is located within the traction network monitoring section formed by the measurement point on this side and the measurement point on the opposite side, while the abnormal traveling wave reflection positioning mode refers to the fault positioning mode where the fault point is located outside the traction network monitoring section of the measurement point.

[0042] In some embodiments, identifying the fault location point of the electrified railway traction power supply network based on the fault location pattern is achieved through the following steps: The fault location mode is obtained, which includes a normal traveling wave location mode and a traveling wave reflection abnormal location mode. If it is a normal traveling wave positioning mode, the fault location of the electrified railway traction power supply network is determined by taking the measurement point on this side as a reference and combining it with the first estimated distance. If it is a traveling wave reflection anomaly location mode, the first estimated distance and the second estimated distance are corrected based on the traction network topology to obtain the corrected first estimated distance and the second estimated distance and determine the initial fault location point; By combining the traction network line parameters and traveling wave propagation characteristics, the rationality of the initial fault location is verified, and the verified initial fault location is output as the fault location of the electrified railway traction power supply network.

[0043] In specific implementation, firstly, the fault location mode is obtained, which includes a normal traveling wave location mode and a traveling wave reflection anomaly location mode; secondly, if it is determined to be a normal traveling wave location mode, then using the local measurement point as a spatial reference point, the line alignment topology data of the section where the local measurement point is located is retrieved from the traction network GIS topology database. Using the line topology spatial mapping method, the fault point is spatially located along the actual line extension direction of the traction network according to the first estimated distance, thus obtaining the fault location point of the electrified railway traction power supply network. The fault location point refers to the fault location point of the electrified railway traction power supply network. The spatial location of the fault point is determined; then, if it is determined to be a traveling wave reflection anomaly location mode, the complete traction network topology structure containing line branches, nodes, terminals and laying direction is retrieved from the traction network GIS topology database. Based on the traction network topology constraint relationship of the traveling wave reflection anomaly, the topology constraint correction method is used to numerically correct the first estimated distance and the second estimated distance according to the actual topology of the line and the spatial location of the traveling wave reflection point (that is, the topology constraint correction method first relies on the complete topology structure of the traction network to identify the spatial location of the branch node that caused the traveling wave reflection anomaly, and combines the actual laying direction of the traction network line and the spatial location of the fault point). The actual propagation path of the wave through the reflection point is used to calculate the effective propagation distance of the traveling wave from the measurement point to the fault point. This is used to subtract the redundant propagation distance components caused by the superposition of traveling wave reflections in the original first and second estimated distances, thus completing the numerical correction of the original estimated distances. The corrected first and second estimated distances are obtained. Then, using the measurement point on this side as the spatial reference point, spatial point calibration is performed along the extension direction of the topology-corrected traction network line according to the corrected first estimated distance to obtain the initial fault location point. Finally, a multi-dimensional rationality verification method is used to verify the initial fault location point, first verifying the point... The system checks whether the fault location is within the spatial range of the actual traction network topology, and then verifies whether the traveling wave propagation distance corresponding to the location matches the estimated distance or the corrected estimated distance. Invalid locations outside the topology spatial range and abnormal locations that do not match the traveling wave propagation characteristics are eliminated. Only the initial fault location points that meet the dual verification requirements are retained. Finally, the verified initial fault location points are output as the fault location points of the electrified railway traction power supply. The traction network topology refers to the set of geographical information and engineering parameters that characterize the traction network line laying direction, branch nodes, line terminals, and spatial distribution relationships.

[0044] It should be noted that the fault location point in this application represents the spatial location where the actual fault occurs in the traction power supply system of the electrified railway.

[0045] In another aspect, in some embodiments, this application provides a traction power supply fault location system for electrified railways, referring to... Figure 4The figure is a schematic diagram of the structure of a traction power supply fault location system for electrified railways according to some embodiments of this application. The traction power supply fault location system for electrified railways includes: a data acquisition module 201, a processing module 202, and an execution module 203, which are described below: The acquisition module 201 in this application is mainly used to acquire transient fault voltage signals between the contact wire and the rail at the measurement point of the traction power supply network of the electrified railway. Processing module 202, in this application, is mainly used to identify the local measurement point and the opposite measurement point where the initial traveling wave of the fault first arrives based on the fault voltage transient signal; The processing module 202 is also used to perform joint time-frequency analysis on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault, so as to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave at the fault point and the reflected traveling wave at the measurement point. In addition, the processing module 202 is also used to identify the equivalent propagation time difference between the fault traveling wave and the measurement point on the local side and the measurement point on the opposite side based on the distribution characteristics of the dominant oscillation frequency sequence, and then calculate the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point based on the known wave velocity of the traction network line and the equivalent propagation time difference. The execution module 203 in this application is mainly used to determine the fault location mode of the traction power supply fault based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points, and to identify the fault location point of the electrified railway traction power supply network based on the fault location mode.

[0046] In addition, this application also provides a computer device, which includes a memory and a processor. The memory stores code, and the processor is configured to acquire the code and execute the above-described method for locating traction power supply faults in electrified railways.

[0047] In some embodiments, reference Figure 5 The figure is a schematic diagram of the structure of a computer device for implementing a traction power supply fault location method for electrified railways according to some embodiments of this application. The traction power supply fault location method for electrified railways in the above embodiments can be implemented through... Figure 5 The computer device shown is used to implement this, and the computer device includes at least one processor 301, a communication bus 302, a memory 303, and at least one communication interface 304.

[0048] The processor 301 may be a general-purpose central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more devices used to control the execution of the traction power supply fault location method for electrified railways in this application.

[0049] The communication bus 302 can be used to transmit information between the aforementioned components.

[0050] The memory 303 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CDROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disks or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory 303 may exist independently and be connected to the processor 301 via the communication bus 302. The memory 303 may also be integrated with the processor 301.

[0051] The memory 303 stores program code for executing the scheme of this application, and its execution is controlled by the processor 301. The processor 301 executes the program code stored in the memory 303. The program code may include one or more software modules. In the above embodiments, the determination of the traction power supply fault location method for electrified railways can be implemented by the processor 301 and one or more software modules in the program code in the memory 303.

[0052] Communication interface 304 uses any transceiver-like device for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.

[0053] In a specific implementation, as one example, a computer device may include multiple processors, each of which may be a single-core (single CPU) processor or a multi-core (multi CPU) processor. Here, a processor may refer to one or more devices, circuits, and / or processing cores used to process data (e.g., computer program instructions).

[0054] The aforementioned computer device can be a general-purpose computer device or a special-purpose computer device. In specific implementations, the computer device can be a desktop computer, a portable computer, a network server, a handheld digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a communication device, or an embedded device. This application does not limit the type of computer device.

[0055] In addition, this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for locating traction power supply faults in electrified railways.

[0056] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0057] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for locating traction power supply faults in electrified railways, characterized in that, Includes the following steps: The transient fault voltage signal between the contact wire and the rail is collected at the measurement point of the traction power supply network of the electrified railway. Based on the fault voltage transient signal, the measurement point on this side and the measurement point on the opposite side that are first reached by the initial traveling wave of the fault are identified. Joint time-frequency analysis is performed on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave at the fault point and the reflected traveling wave at the measurement point. Based on the distribution characteristics of the dominant oscillation frequency sequence, the equivalent propagation time difference between the fault traveling wave and the measurement point on the local side and the measurement point on the opposite side is identified. Then, based on the known wave velocity of the traction network line and the equivalent propagation time difference, the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point are calculated. The fault location mode of the traction power supply fault is determined based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points, and the fault location point of the electrified railway traction power supply network is identified based on the fault location mode.

2. The method as described in claim 1, characterized in that, The specific measurement points on the local and opposite sides that are first reached by the initial traveling wave of the fault, identified based on the fault voltage transient signal, include: The fault voltage transient signal is preprocessed to obtain a preprocessed fault voltage transient signal; Based on the preprocessed fault voltage transient signal, the traveling wave sudden change feature is detected, and then the arrival time of the initial traveling wave of the fault corresponding to each measurement point is identified. The arrival times of the initial traveling wave of the fault at each measurement point are compared in time sequence to determine the measurement point that first detects the initial traveling wave of the fault as the measurement point on this side. Using the measurement point on this side as a reference, the first measurement point among the remaining measurement points that has a time difference between the arrival time of the initial traveling wave of the fault and the measurement point on this side is taken as the measurement point on the opposite side.

3. The method as described in claim 1, characterized in that, Joint time-frequency analysis is performed on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave from the fault point and the reflected traveling wave from the measurement point. Specifically, this includes: Based on the arrival time difference of the initial traveling wave of the fault between the measurement point on this side and the measurement point on the opposite side, the voltage waveforms on both sides within the preset time window are aligned on the time axis to obtain the aligned voltage waveforms on both sides. A wavelet time-frequency analysis was performed on the aligned two-sided voltage waveforms using the cross-correlation coefficient of the two-point signal to determine the joint time-frequency matrix of the two sides. The amplitude of the dual-sided joint time-frequency matrix is ​​normalized, and time-frequency units with amplitudes greater than a preset normalization threshold are extracted. Then, a set of candidate frequencies related to the superposition of the traveling wave reflected from the fault point and the traveling wave reflected from the measurement point are selected. The candidate frequency set is subjected to a two-sided frequency consistency check, and frequency components that co-occur on both sides and have coordinated amplitude change trends are retained and arranged in ascending order of frequency to obtain the dominant oscillation frequency sequence.

4. The method as described in claim 1, characterized in that, The equivalent propagation time difference between the fault traveling wave arriving at the local measurement point and the opposite measurement point, identified based on the distribution characteristics of the dominant oscillation frequency sequence, specifically includes: The frequency difference sequence is obtained by extracting the difference between adjacent frequency components from the dominant oscillation frequency sequence. Calculate the corresponding time interval sequence based on the frequency difference sequence; The equivalent propagation time difference between the fault traveling wave and the measurement point on the opposite side is calculated based on the time interval sequence.

5. The method as described in claim 1, characterized in that, The calculation of the first and second estimated distances from the local measurement point and the opposite measurement point to the fault point based on the known wave velocity of the traction network line and the equivalent propagation time difference specifically includes: Obtain the known wave velocity of the traction network line and the actual total length of the line between the measurement point on this side and the measurement point on the opposite side; Calculate the estimated distance difference between the local measurement point, the opposite measurement point, and the fault point based on the known wave velocity and the equivalent propagation time difference. Based on the difference between the actual total length of the line and the estimated distance, a system of two linear equations in two variables is established for the first estimated distance and the second estimated distance; Solve the system of two linear equations to obtain the first and second estimated distances from the measurement point on the local side and the measurement point on the opposite side to the fault point.

6. The method as described in claim 1, characterized in that, The fault location mode for traction power supply faults, determined based on the sum of the first and second estimated distances and the actual total line length between the two measurement points, specifically includes: Calculate the sum of the first estimated distance and the second estimated distance to obtain the total estimated distance; The difference between the estimated total distance and the actual total length of the line between the two measurement points is calculated to obtain the length deviation value; The length deviation value is compared with a preset error threshold to determine whether the length deviation value is within the preset error threshold range. If the length deviation value is within the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the normal traveling wave location mode. If the length deviation value exceeds the preset error threshold range, the fault location mode of the traction power supply fault is determined to be the traveling wave reflection abnormal location mode.

7. The method as described in claim 1, characterized in that, The transient fault voltage signal between the contact wire and the rail is collected at the measurement point of the traction power supply network of the electrified railway using a voltage sensor.

8. A traction power supply fault location system for electrified railways, characterized in that, The system includes: The acquisition module is used to acquire transient fault voltage signals between the contact wire and the rail at measurement points in the traction power supply network of electrified railways. The processing module is used to identify the local measurement point and the opposite measurement point where the initial traveling wave of the fault first arrives, based on the fault voltage transient signal. The processing module is also used to perform joint time-frequency analysis on the voltage waveforms of the local measurement point and the opposite measurement point within a preset time window after the fault, so as to extract the dominant oscillation frequency sequence formed by the superposition of the reflected traveling wave at the fault point and the reflected traveling wave at the measurement point. The processing module is also used to identify the equivalent propagation time difference between the fault traveling wave and the measurement point on the local side and the measurement point on the opposite side based on the distribution characteristics of the dominant oscillation frequency sequence, and then calculate the first estimated distance and the second estimated distance from the measurement point on the local side and the measurement point on the opposite side to the fault point based on the known wave velocity of the traction network line and the equivalent propagation time difference. The execution module is used to determine the fault location mode of the traction power supply fault based on the sum of the first estimated distance and the second estimated distance and the actual total line length between the two measurement points, and to identify the fault location point of the electrified railway traction power supply network based on the fault location mode.

9. A computer device, characterized in that, The computer device includes a memory and a processor, the memory storing code, and the processor being configured to retrieve the code and execute the traction power supply fault location method for electrified railways as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the traction power supply fault location method for electrified railways as described in any one of claims 1 to 7.

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