A method and system for double-end fault location of overhead self-closing through-line without synchronization

Abstract

This invention discloses a method and system for fault location at both ends of an overhead self-closing through-line without synchronization, belonging to the field of railway power relay protection. Specifically, it includes: when a fault occurs in an overhead self-closing through-line, fault recording devices at both ends of the substation record three-phase voltage traveling wave data within a short time window. A phase-mode transformation matrix is ​​used to convert the coupled three-phase voltage traveling wave data into independent line-mode and zero-mode components, and wavelet transform is performed. The arrival times of the initial voltage traveling waves of the line-mode and zero-mode components are determined based on the wavelet transform coefficients, and their time difference is calculated. The substation at the first end can locate the fault in the overhead self-closing through-line line based on the time difference obtained from the substations at both ends. Principle analysis and simulation results show that this method does not rely on double-end clock synchronization and is unaffected by wave velocity, providing accurate and reliable fault location results.

Description

Technical Field

[0001] This invention relates to a method and system for determining fault location at both ends of an overhead self-closing through line without synchronization, belonging to the field of railway power relay protection. Background Technology

[0002] As railways play an increasingly prominent role in my country's comprehensive transportation system, the safety requirements for railway operations are also becoming increasingly stringent. Automatic block signaling (ABS) lines provide power to the railway lines and station loads, playing a crucial role in railway safety. Power outages can lead to chaotic ABS signals, disrupting normal railway operations and, in severe cases, causing significant loss of life and property. These ABS lines are constructed along railway lines, traversing mountains, forests, and deserts, and are susceptible to damage from storms, rain, snow, and lightning, making them highly prone to failure and extremely difficult to troubleshoot. With increasing demands for railway power supply reliability and automation, fault location and detection in ABS lines have become increasingly important. Therefore, developing a method or monitoring system for rapidly locating faults in ABS lines is of significant practical importance for ensuring railway operational safety.

[0003] Fault location methods can be categorized into three types based on their working principles: impedance method, fault analysis method, and traveling wave method. Currently, the main method used in self-closing railway lines is impedance-based distance measurement, which calculates the line impedance by measuring the voltage and current at one end of the line, and then calculates the fault distance. This method is simple in principle, easy to implement, and not limited by communication technology, but it also suffers from significant distance measurement errors. The traveling wave method has received widespread attention from scholars because it is unaffected by system parameters, neutral grounding methods, and line asymmetry. Traveling wave distance measurement mainly includes single-end and double-end methods. The single-end method uses the time difference between the first incident traveling wave front and the first reflected traveling wave front at the fault point for fault location. Its advantages include fewer required devices and no need for precise synchronization clocks. However, its disadvantages include difficulty in identifying the reflected wave from the fault point, which affects the accuracy of the distance measurement, and its dependence on wave velocity, resulting in low accuracy. Double-ended traveling wave ranging utilizes the time difference between the arrival of the first incident traveling wave wavefront at the detection points at both ends of the track for fault location. Its advantages include a simple principle and easy wavefront detection, requiring only the detection of the initial wavefront from the fault point to the detection devices at both ends of the track. Disadvantages include the need for precise synchronization clocks, dependence on parameters such as track length and wave velocity, and the need to install ranging devices at the ends of the track, increasing costs. Therefore, both single-ended and double-ended traveling wave ranging methods have some shortcomings. Furthermore, railway self-closing through-tracks differ from power system lines; although they are dual-powered, they operate under single-power supply during normal operation, with a power supply arm length typically 40-60 km, reaching 80 km or even hundreds of km in special cases.

[0004] In summary, although the traveling wave method has good application prospects and high ranging accuracy, some problems still exist. Therefore, it is necessary to further study the method of fault location for railway overhead self-closing through lines using the traveling wave method. Summary of the Invention

[0005] The purpose of this invention is to address the inherent defects of the traveling wave method, such as the wave velocity selection problem in the single-end method and the strict clock synchronization problem in the double-end method. At the same time, this invention studies the characteristics of railway overhead self-closing through lines and provides a method and system for double-end fault location of railway overhead self-closing through lines that does not require synchronization, so as to achieve accurate fault location of railway overhead self-closing through lines.

[0006] To achieve the above objectives, the present invention adopts the following scheme: a method and system for fault location at both ends of an overhead self-closing through-line without synchronization. When a fault occurs in the overhead self-closing through-line of a railway, the fault recording devices at the substations at both ends of the line record the three-phase voltage traveling wave data within a short time window. The coupled three-phase voltage traveling wave data are converted into mutually independent line-mode components and zero-mode components using a phase-mode transformation matrix. Wavelet transform is used to calibrate the arrival times of the initial voltage traveling waves of the line-mode component and the initial voltage traveling waves of the zero-mode component fault, respectively, and the time difference between the two is calculated. The end substation transmits its time difference information to the beginning substation. The beginning substation can locate the fault in the overhead self-closing through-line of the railway based on the time difference obtained from the two end substations.

[0007] This invention provides a method for locating faults at both ends of an overhead self-closing through-line without synchronization, specifically including:

[0008] Step 1: A fault occurs on the overhead automatic closed-circuit railway line. The substations at both ends record the three-phase voltage traveling wave data 0.5ms before the fault and 1ms after the fault. , , ;

[0009] Step 2: Using the phase transformation matrix The coupled three-phase voltage traveling wave data is converted into independent line mode components. or and zero modulus components And perform wavelet transform;

[0010] Step 3: Based on the wavelet transform coefficients, determine the arrival times of the initial voltage traveling waves of the linear mode component fault and the initial voltage traveling waves of the zero mode component fault, and calculate the time difference between them. and ;

[0011] Step 4: The first-end substation locates the fault in the overhead automatic closed-loop railway line based on the time difference obtained from the two-end substations.

[0012] Furthermore, in Step 2:

[0013] Step 2.1: The methods for obtaining the linear model components and zero model components are as follows:

[0014] u m = S − 1 u = [ 3 3 3 3 − 1 − 2 3 − 2 − 1 ] × [ u a u b u c ]

[0015] in, To obtain the three-phase voltage traveling wave for the two-end substations, u = [ u a u b u c ] , To obtain the voltage traveling wave modulus for the two distribution substations, u m = [ u 0 u α u β ] ;

[0016] Step 2.2: Select or As a linear model component As a zero-modulus component;

[0017] Furthermore, in Step 3:

[0018] Step 3.1: Calculate the time difference between the arrival times of the initial voltage traveling waves of zero-mode faults and the initial voltage traveling waves of line-mode faults at the substation at the beginning (M end) of the overhead self-closing through-line railway line:

[0019]

[0020] in, This indicates the time when the initial voltage traveling wave of a line-mode fault arrives at the first-end (M-end) substation. This indicates the moment when the initial voltage traveling wave of a zero-mode fault arrives at the first (M) end of the substation;

[0021] Step 3.2: Calculate the time difference between the arrival times of the initial voltage traveling waves of zero-mode faults and the initial voltage traveling waves of line-mode faults at the end (N-end) of the railway overhead self-closing through-line substation:

[0022]

[0023] in, This indicates the time when the initial voltage traveling wave of a line-mode fault reaches the end (N-terminal) substation. This indicates the time when the initial voltage traveling wave of a zero-mode fault reaches the end (N-terminal) substation;

[0024] Furthermore, in Step 4:

[0025] Step 4.1: Construct the single-end method traveling wave ranging formula based on the zero-mode and linear-mode wave velocities and time differences:

[0026]

[0027]

[0028] Where d represents the fault distance; Indicates the length of the line; These represent zero-mode wave velocity and linear-mode wave velocity, respectively.

[0029] Step 4.2: Based on the two single-end traveling wave ranging formulas in Step 4.1, construct a double-end traveling wave fault ranging formula for railway overhead self-closing through-line that does not rely on double-end synchronization and is unaffected by wave velocity:

[0030]

[0031] Another aspect of the present invention provides a fault location system for an overhead self-closing through-line without synchronization, specifically comprising:

[0032] Data acquisition module: used to acquire three-phase voltage traveling wave data on both sides of the railway overhead automatic / through track;

[0033] Data processing module: used to decouple the three-phase voltage traveling wave into independent line mode components and zero mode components, and to calibrate the arrival time of the initial traveling wave of the line mode fault and the initial traveling wave of the zero mode fault.

[0034] Numerical calculation module: used to calculate fault distance;

[0035] Furthermore, the data acquisition module specifically includes:

[0036] Data acquisition unit: used to acquire three-phase voltage signals from the unit under test in real time from sensors and other measuring devices;

[0037] Analog-to-digital converter: Used to convert the acquired analog signals into digital signals.

[0038] Furthermore, the data processing module specifically includes:

[0039] Phase-mode conversion unit: used to convert three-phase voltage signals into line-mode and zero-mode components;

[0040] Wavelet transform unit: used to perform wavelet decomposition and reconstruction of linear mode components and zero mode components;

[0041] Timing calibration unit: used to calibrate the arrival time of the initial traveling wave of the linear mode fault and the initial traveling wave of the zero mode fault.

[0042] Furthermore, the numerical calculation module specifically includes:

[0043] Line length input unit: Used to input the length of the railway overhead self-closing through line;

[0044] Fault Distance Calculation Unit: Used to calculate fault distance;

[0045] The beneficial effects of this invention are:

[0046] 1. This invention utilizes the initial voltage traveling waves of the line mode and zero mode of the substations on both sides of the railway overhead self-closing through line, eliminating the need to identify subsequent wavefronts and improving the accuracy of fault location.

[0047] 2. This invention can perform distance measurement without using wave speed, overcoming the dependence of traditional single-end distance measurement methods on wave speed and improving the accuracy of fault location.

[0048] 3. Although this invention is a dual-end method, it does not require clock synchronization between the two substations. This reduces the cost of the ranging device and eliminates the positioning error caused by clock asynchrony.

[0049] In summary, this invention, taking into account the characteristics of overhead self-closing through-line railways, proposes a method and system for double-end fault location of overhead self-closing through-line railways that does not require synchronization. This method overcomes the inherent defects of single-end and double-end methods. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings of the present invention are as follows:

[0051] Figure 1 This is a typical wiring diagram of the overhead self-closing through-line railway of the present invention;

[0052] Figure 2 This is a diagram showing the arrangement of towers and conductors for the overhead self-closing through-line railway of the present invention.

[0053] Figure 3 This is a flowchart of the double-end fault location method for an overhead self-closing through railway line according to the present invention.

[0054] Figure 4 A block diagram of a double-end fault location system for an overhead self-closing through-line railway.

[0055] Figure 5 This is the traveling wave diagram of the three-phase voltage at the first end (M end) in Embodiment 1 of the present invention;

[0056] Figure 6 The first-end (M-end) linear mode component and its first-scale wavelet coefficients in Embodiment 1 of the present invention;

[0057] Figure 7 The zero-mode component at the first end (M end) and its first-scale wavelet coefficients in Embodiment 1 of the present invention;

[0058] Figure 8 This is the traveling wave diagram of the three-phase voltage at the end (N terminal) in Embodiment 1 of the present invention;

[0059] Figure 9 The terminal (N-end) linear mode component and its first-scale wavelet coefficients in Embodiment 1 of the present invention;

[0060] Figure 10 The zero-mode component at the end (N end) and its first-scale wavelet coefficients in Embodiment 1 of the present invention;

[0061] Figure 11 This is the traveling wave diagram of the three-phase voltage at the first end (M end) in Embodiment 2 of the present invention;

[0062] Figure 12 The first-end (M-end) linear mode component and its first-scale wavelet coefficients in Embodiment 2 of the present invention;

[0063] Figure 13 The zero-mode component at the first end (M end) and its first-scale wavelet coefficients in Embodiment 2 of the present invention;

[0064] Figure 14 This is the traveling wave diagram of the three-phase voltage at the end (N terminal) in Embodiment 2 of the present invention;

[0065] Figure 15 The terminal (N-end) linear mode component and its first-scale wavelet coefficients in Embodiment 2 of the present invention;

[0066] Figure 16 The zero-mode component at the end (N end) and its first-scale wavelet coefficients are shown in Embodiment 2 of the present invention. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0068] The purpose of this invention is to provide a method and system for fault location at both ends of an overhead self-closing through-line without synchronization, aiming to solve the problems of inaccurate and unreliable fault location in existing railway overhead self-closing through-line systems. The invention will be further described below with reference to specific embodiments.

[0069] Example 1: This example follows... Figure 1The structural diagram shown illustrates the simulation model of an overhead self-closing through-line railway built in PSCAD electromagnetic transient simulation software. The length of the self-closing / through-line between substations M and N is 60km, all of which are overhead lines. The arrangement of the overhead line towers and conductors is as follows. Figure 2 As shown, the fault is located 25km from substation M, and the fault type is a single-phase ground fault of phase A.

[0070] According to such Figure 3 and Figure 4 The method for fault location using a double-ended traveling wave fault detection system on an overhead self-closing through-line railway, as shown in the figure, includes the following specific steps:

[0071] Step 1: According to Figure 1 After a fault occurs on the overhead automatic gated / through railway line shown, the M-end substation records the three-phase voltage traveling wave data 0.5ms before the fault and 1ms after the fault. , , ,like Figure 5 As shown; the three-phase voltage traveling wave data recorded by the N-terminal substation 0.5ms before the fault and 1ms after the fault. , , ,like Figure 8 As shown;

[0072] Step 2: Using the phase transformation matrix The three-phase voltage traveling wave data recorded at the M-terminal substation are converted into independent line mode components. and zero modulus components Then, wavelet decomposition is performed to obtain the first-scale wavelet coefficients. and ,like Figure 6 and Figure 7 As shown; using the phase mode transformation matrix The three-phase voltage traveling wave data recorded at the N-terminal substation are converted into independent line mode components. and zero modulus components Then, wavelet decomposition is performed to obtain the first-scale wavelet coefficients. and ,like Figure 9 and Figure 10 As shown;

[0073] Step 3: Based on the wavelet transform coefficients, determine the arrival times of the initial voltage traveling wave of the line-mode component fault and the initial voltage traveling wave of the zero-mode component fault at the M-end substation. , According to the formula Calculations show that ; calibrate the arrival times of the initial voltage traveling wave of the line-mode component fault and the initial voltage traveling wave of the zero-mode component fault in the N-terminal substation, where, , According to the formula Calculations show that ;

[0074] Step 4: The first-end substation locates faults in the overhead automatic / through railway line based on the time difference obtained from the two-end substations.

[0075]

[0076] According to the calculation results, the fault occurred 25.05km away from the M substation on the overhead self-closing through-line of the railway, which is only 50m away from the actual fault location. Therefore, the present invention can realize fault distance measurement of the overhead self-closing through-line of the railway.

[0077] Example 2: This example follows... Figure 1 The structural diagram shown illustrates the simulation model of an overhead self-closing through-line railway built in PSCAD electromagnetic transient simulation software. The length of the self-closing and through-line between substations M and N is 60km, all of which are overhead lines. The arrangement of the overhead line towers and conductors is as follows. Figure 2 As shown, the fault occurred 35km from substation M, and the fault type was BCG two-phase ground fault.

[0078] According to such Figure 2 and Figure 3 The method for fault location using double-end traveling wave fault ranging on an overhead self-closing through-line railway, as shown, includes the following specific steps:

[0079] Step 1: According to Figure 1 After a fault occurs on the overhead automatic closed-circuit railway line shown, the M-end substation records the three-phase voltage traveling wave data 0.5ms before the fault and 1ms after the fault. , , ,like Figure 11 As shown; the three-phase voltage traveling wave data recorded by the N-terminal substation 0.5ms before the fault and 1ms after the fault. , , ,like Figure 14 As shown;

[0080] Step 2: Using the phase transformation matrix The three-phase voltage traveling wave data recorded at the M-terminal substation are converted into independent line mode components. and zero modulus components Then, wavelet decomposition is performed to obtain the first-scale wavelet coefficients. and ,like Figure 12 and Figure 13 As shown; using the phase mode transformation matrix The three-phase voltage traveling wave data recorded at the N-terminal substation are converted into independent line mode components. and zero modulus components Then, wavelet decomposition is performed to obtain the first-scale wavelet coefficients. and ,like Figure 15 and Figure 16 As shown;

[0081] Step 3: Based on the wavelet transform coefficients, determine the arrival times of the initial voltage traveling wave of the line-mode component fault and the initial voltage traveling wave of the zero-mode component fault at the M-end substation. , According to the formula Calculations show that ; calibrate the arrival times of the initial voltage traveling wave of the line-mode component fault and the initial voltage traveling wave of the zero-mode component fault in the N-terminal substation, where, , According to the formula Calculations show that ;

[0082] Step 4: The first-end substation locates the fault in the overhead automatic closed-loop railway line based on the time difference obtained from the two end substations.

[0083]

[0084] According to the calculation results, the fault occurred 35.26km away from the M substation on the overhead self-closing through-line of the railway, which is only 260m away from the actual fault location. Therefore, the present invention can realize fault distance measurement of the overhead self-closing through-line of the railway.

[0085] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A method for double-end fault location of an overhead self-closing through-line without synchronization, characterized in that: Step 1: When a fault occurs in the railway overhead automatic closed through line, the substations at both ends record the three-phase voltage traveling wave data 0.5ms before the fault and 1ms after the fault. Step 2: Using a phase-mode transformation matrix, the coupled three-phase voltage traveling wave data is converted into independent line-mode and zero-mode components, and then wavelet transform and reconstruction are performed. The phase-mode transformation matrix is: Step 3: Based on the wavelet transform coefficients, determine the arrival times of the initial voltage traveling waves of the linear mode component fault and the initial voltage traveling waves of the zero mode component fault, and calculate the time difference Δt between them. M and Δt N The Δt M and Δt N The calculation method is as follows: t M =t 0M -t αM , Δt N =t 0N -t αN , where t αM t represents the time when the initial voltage traveling wave of a line-mode fault arrives at the first-end (M-end) substation. 0M t represents the time when the initial voltage traveling wave of a zero-mode fault arrives at the first-end (M-end) substation. αN t represents the time when the initial voltage traveling wave of a line-mode fault reaches the end (N-terminal) substation. 0N This indicates the time when the initial voltage traveling wave of a zero-mode fault reaches the end (N-terminal) substation; Step 4: The first-end substation performs fault location measurement on the overhead automatic closed-circuit railway line based on the time difference obtained from the two end substations. The fault distance is calculated as follows: Where d represents the distance between the fault point and the first (M) end substation, and l represents the length of the railway overhead automatic closed-loop line.

2. A fault location system for an overhead self-closing through-line without synchronization, characterized in that... The method for determining fault location at both ends of an overhead self-closing through-line without synchronization as described in claim 1 specifically includes: Data acquisition module: includes a three-phase voltage acquisition unit and an analog-to-digital conversion unit. The three-phase voltage acquisition unit is used to acquire three-phase voltage signals in real time; the analog-to-digital conversion unit is used to convert the acquired analog signals into digital signals. The data processing module includes a phase-mode transformation unit, a wavelet transform unit, and a time calibration unit. The phase-mode transformation unit converts the three-phase voltage signal into line-mode and zero-mode components. The wavelet transform unit performs wavelet decomposition and reconstruction on the line-mode and zero-mode components. The time calibration unit calibrates the arrival times of the initial traveling wave of the line-mode fault and the initial traveling wave of the zero-mode fault. The numerical calculation module includes a line length input unit and a fault distance calculation unit. The line length input unit is used to input the length of the railway overhead self-closing through line; the fault distance calculation unit is used to calculate the fault distance.

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