A method and system for locating traveling wave faults in a fully parallel AT-powered traction network

Abstract

This invention discloses a traveling wave fault location method and system for a fully parallel AT-powered traction network, belonging to the field of relay protection for railway traction power supply systems. Specifically, after a fault occurs in the fully parallel AT-powered traction network, firstly, the characteristics of the initial current traveling wave of the AT substation are analyzed, and the fault line is determined using its amplitude; then, the polarity of the initial current traveling wave and the initial voltage traveling wave of the fault line in the AT substation are used to determine the fault direction; finally, the fault distance is calculated by using the arrival times of the initial voltage traveling wave at the traction substation outlet, AT substation, and sectioning substation, combined with the fault direction information, and selecting a forward or reverse direction ranging formula. This method only utilizes the initial traveling wave information, without needing to identify the wavefront or wave velocity parameters. Simulation results show that this location method not only provides the fault distance but also the fault line information, facilitating maintenance personnel to quickly locate the fault point, and exhibits extremely high robustness and accuracy.

Description

Technical Field

[0001] This invention relates to a method and system for locating traveling wave faults in a fully parallel AT power supply traction network, belonging to the field of relay protection for railway traction power supply systems. Background Technology

[0002] The fully parallel AT traction power supply system is characterized by stable power supply voltage and strong power supply capacity, and is widely used in my country's high-speed electrified railways. However, the traction network is constantly exposed to the natural environment, and strong winds, ice and snow, pollution, and foreign objects intruding into the grid can cause short-circuit faults, affecting the normal operation of trains. Therefore, rapid and accurate fault location is of great significance for railway operation. Currently, the main fault location methods for fully parallel AT traction networks are the impedance method and the current ratio method, which have relatively low location accuracy.

[0003] Traveling wave fault location methods have been widely researched and applied in power systems. The traveling wave method boasts high accuracy and reliability in fault location, and its application in traction power supply systems represents a novel approach. However, the complex wiring configuration of fully parallel AT power supply traction networks, coupled with the complex propagation characteristics of traveling waves and difficulties in wavefront identification, limits the application prospects of single-ended traveling wave methods. Furthermore, the double-ended traveling wave method, due to the asymmetrical structure of the traction network, cannot accurately determine the traveling wave velocity, resulting in suboptimal location accuracy.

[0004] In summary, although the traveling wave method has good application prospects and high ranging accuracy for fault location, there are still some problems when applied to a fully parallel AT power supply traction network. Therefore, it is necessary to further study the method of using the traveling wave method for fault location in a fully parallel AT traction network. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of fault location in a fully parallel AT traction network. The existence of the AT in a fully parallel AT traction network creates a third measuring point. This invention provides a traveling wave fault location method and system for a fully parallel AT power supply traction network to achieve accurate fault location in the fully parallel AT power supply traction network.

[0006] To achieve the above objectives, the present invention adopts the following scheme: a traveling wave fault location method and system for a fully parallel AT power supply traction network. First, the characteristics of the initial current traveling wave of the AT substation fault are analyzed, and the fault line is determined using its amplitude. Then, the polarity of the initial current traveling wave and the initial voltage traveling wave of the AT substation fault line is used to determine the fault direction. Finally, the fault distance is calculated by using the time when the initial voltage traveling wave of the fault reaches the traction substation outlet, AT substation, and section substation, combined with the fault direction information, to select the forward or reverse direction ranging formula, thus forming a complete traveling wave fault location method and system for a fully parallel AT power supply traction network.

[0007] This invention provides a method for locating traveling wave faults in a fully parallel AT power supply traction network, specifically including:

[0008] Step 1: After a fault occurs in the fully parallel AT power supply traction network, retrieve the current traveling wave data of the AT's upstream T line, upstream F line, downstream T line, and downstream F line, and perform wavelet transform to extract the maximum value of the initial current traveling wave modulus of each line during the fault.

[0009] Step 2: Find the maximum value of the initial current traveling wave mode with the largest amplitude, and determine the corresponding line as the fault line;

[0010] Step 3: Retrieve the traveling wave data of the fault line voltage collected by AT, and perform wavelet transform to extract the polarity of the initial voltage traveling wave of the fault line.

[0011] Step 4: Determine the direction of the fault based on the polarity of the initial voltage traveling wave and the initial current traveling wave of the faulty line in the AT.

[0012] Step 5: Retrieve voltage traveling wave data at the three locations of the fault line: traction substation, AT substation, and section substation, and perform wavelet transform to extract the arrival time of the initial traveling wave of the voltage fault.

[0013] Step 6: Based on the fault direction determined in Step 4, select the forward or reverse direction distance measurement formula to calculate the fault distance.

[0014] Furthermore, in Step 1, Step 3, and Step 5, the wavelet transform uses the derivative of the cubic B-spline function as the wavelet function to obtain the modulus maxima of the wavelet transform in the high-frequency band, and extracts the arrival time, polarity, and amplitude of the fault traveling wave.

[0015] Furthermore, in Step 4, the method for determining the direction of the fault is as follows:

[0016]

[0017] In the formula, The maximum value of the traveling wave mode of the initial fault current of the AT is given. The maximum value of the traveling wave mode of the initial voltage of the AT fault is given by sign, which indicates its polarity.

[0018] Furthermore, in Step 6, the ranging formula for a fault in the opposite direction is: In the formula, x is the distance between the fault point and the AT station when the fault occurs in the opposite direction. The moment when the initial voltage traveling wave of the fault reaches terminal S (traction substation). The moment when the initial fault voltage traveling wave reaches terminal M (AT station). The moment when the initial voltage traveling wave of the fault reaches the Z-end (section); the ranging formula for a fault in the positive direction is: In the formula, When the fault is in the positive direction, the distance between the fault point and the AT station; The moment when the initial voltage traveling wave of the fault reaches terminal S (traction substation). The moment when the initial fault voltage traveling wave reaches terminal M (AT station). The moment when the initial voltage traveling wave of the fault reaches the Z-terminus (section).

[0019] Another aspect of the present invention provides a traveling wave fault location system for a fully parallel AT power supply traction network, specifically comprising:

[0020] Data acquisition module: used to acquire current traveling wave and voltage traveling wave data of AT substation, voltage traveling wave data of traction substation, and voltage traveling wave data of section substation;

[0021] Data processing module: Analyzes the amplitude of the initial current traveling wave of each line in the AT substation to select the fault line, determines the fault direction based on the polarity of the initial current traveling wave and the initial voltage traveling wave of the fault in the AT substation, and calibrates the arrival time of the initial voltage traveling wave of the fault line in the traction substation, AT substation, and section substation.

[0022] Numerical calculation module: used to calculate the distance between the fault point and the AT station.

[0023] Furthermore, the data acquisition module specifically includes:

[0024] Data acquisition unit: used to acquire real-time current traveling wave and voltage traveling wave data of AT substation, voltage traveling wave data of traction substation and voltage traveling wave data of section substation from sensors and other measuring devices;

[0025] Analog-to-digital converter: Used to convert the acquired analog signals into digital signals.

[0026] Furthermore, the data processing module specifically includes:

[0027] Fault line selection unit: Determines the fault line by using the magnitude of the maximum value of the initial current traveling wave mode of the AT.

[0028] Fault direction determination unit: The direction of the fault is determined by the polarity of the traveling wave of the initial voltage and the traveling wave of the initial current of the faulty line.

[0029] Wave arrival time calibration unit: used to calibrate the arrival time of voltage traveling waves at three locations: the traction substation outlet, the AT station, and the sectioning station.

[0030] Furthermore, the numerical calculation module is used to calculate the fault distance based on the results given by the fault direction discrimination unit and the wave arrival time proposed by the wave arrival time calibration unit.

[0031] The beneficial effects of this invention are:

[0032] 1. This invention utilizes the AT station of the fully parallel AT traction power supply system as the third measuring point, and proposes a traveling wave fault location method for the fully parallel AT power supply traction network. Compared with the single-end traveling wave method, this method does not require wavehead identification, thus avoiding the problem of difficult wavehead identification caused by the complex wiring of the fully parallel AT traction network. Compared with the double-end traveling wave method, the distance measurement formula provided by this method does not require wave velocity parameters, and can be immune to the influence of wave velocity, thus avoiding the problem of inaccurate wave velocity calculation caused by the asymmetry of traction network parameters.

[0033] 2. This invention combines the structural characteristics of a fully parallel AT traction network and uses the traveling wave method for fault location. Compared with the traditional impedance method and current ratio method, it has extremely high robustness and accuracy. At the same time, this invention not only provides fault distance but also fault line information, making it easier for maintenance personnel to quickly locate the fault point.

[0034] 3. This invention performs data processing locally at the traction substation, AT station, and sectioning station. Only the traction substation and sectioning station need to send the arrival time of the wave to the AT station, thus avoiding the transmission of a large amount of data and the ranging error caused by packet loss during transmission.

[0035] In summary, this invention, taking into account the characteristics of a fully parallel AT power supply traction network, provides a traveling wave fault location method and system for a fully parallel AT power supply traction network. This method has significant advantages over the single-end traveling wave method, the double-end traveling wave method, and the traditional impedance method and current ratio method, and is easy to implement. Attached Figure Description

[0036] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art. The accompanying drawings are shown below:

[0037] Figure 1 This is a diagram of the fully parallel AT power supply system of the present invention;

[0038] Figure 2 This is a structural diagram of the fully parallel AT power supply traction network of the present invention;

[0039] Figure 3 This is a flowchart of the traveling wave fault location method for a fully parallel AT power supply traction network according to the present invention.

[0040] Figure 4This is a block diagram of the traveling wave fault location system for the fully parallel AT power supply traction network of the present invention.

[0041] Figure 5 This is a traveling wave diagram of the current in each line of the AT power supply system in the fully parallel AT power supply system of Embodiment 1 of the present invention;

[0042] Figure 6 This is a distribution diagram of the maximum value of the traveling wave mode of the fault current in each line of the AT unit in Embodiment 1 of the present invention;

[0043] Figure 7 This is a diagram showing the traveling wave of the fault line voltage at AT in Embodiment 1 of the present invention and the distribution of its corresponding modulus maxima after wavelet transform;

[0044] Figure 8 This is a diagram showing the distribution of the fault voltage traveling wave and its modulus maxima at each measuring point in Embodiment 1 of the present invention;

[0045] Figure 9 This is a traveling wave diagram of the current in each line of AT in Embodiment 2 of the present invention;

[0046] Figure 10 This is a distribution diagram of the maximum value of the traveling wave mode of the fault current in each line of the AT unit in Embodiment 2 of the present invention;

[0047] Figure 11 This is a diagram showing the traveling wave of the fault line voltage at AT in Embodiment 2 of the present invention and the distribution of its corresponding modulus maxima after wavelet transform;

[0048] Figure 12 This is a diagram showing the distribution of the fault voltage traveling wave and its modulus maxima at each measuring point in Embodiment 2 of the present invention. Detailed Implementation

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the technical solutions in 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.

[0050] The purpose of this invention is to provide a traveling wave fault location method and system for a fully parallel AT power supply traction network, aiming to solve the problems of inaccurate and unreliable fault location in existing fully parallel AT power supply traction networks. The invention will be further described below with reference to specific embodiments.

[0051] Example 1: Using PSCAD / EMTDC electromagnetic transient simulation software, referring to... Figure 1 and Figure 2A fully parallel AT power supply system was constructed with a sampling rate of 5MHz. The power supply length from the traction substation to the AT station and from the AT station to the section substation is 15km each. Furthermore, considering the impact of noise on traveling waves, a signal-to-noise ratio of 30dB was used to verify the practicality of this method. In the simulation model, a fault occurred on the uplink T-line of the section from the AT station to the section substation, 5km from the AT station, with a transition resistance of 10Ω.

[0052] according to Figure 3 and Figure 4 The method and system for locating traveling wave faults in a fully parallel AT power supply traction network, as shown, include the following specific steps:

[0053] Step 1: After a fault occurs in the fully parallel AT power supply traction network, retrieve the current traveling waves of the upstream T line, upstream F line, downstream T line, and downstream F line of the AT power supply. Figure 5 As shown; perform wavelet transform to extract the maximum value of the traveling wave mode of the initial fault current of each line, such as... Figure 6 As shown.

[0054] Step 2: Locate the maximum amplitude of the initial current traveling wave mode; the corresponding line is identified as the fault line. Figure 6 It can be seen that the initial current traveling wave mode of the fault on the upward T-line has the largest maximum value. Therefore, the upward T-line is determined to be the fault line.

[0055] Step 3: Retrieve the traveling wave data of the uplink T-line voltage collected by the AT, perform wavelet transform, and extract the polarity of the maximum modulus of the initial voltage traveling wave of the uplink T-line fault, such as... Figure 7 As shown.

[0056] Step 4: Determine the fault direction based on the polarity of the initial voltage and current traveling waves of the faulty line as indicated by the AT; Figure 7 It can be seen that the polarity of the maximum value of the traveling wave mode of the initial voltage during an upward T-line fault is positive. Figure 6 It can be seen that the polarity of the maximum value of the traveling wave mode of the initial current of the upward T-line fault is negative, and the product of the two is less than 0, so it is judged to be a fault in the positive direction of AT.

[0057] Step 5: Retrieve voltage traveling wave data from the faulty line at the traction substation outlet, AT substation, and section substation, and perform wavelet transform to extract the arrival time of the initial traveling wave of the voltage fault, such as... Figure 8 As shown, the fault voltage traveling wave arrives at the traction substation outlet (S end) at 0.0668ms, at the AT substation (M end) at 0.0168ms, and at the section substation (Z end) at 0.0336ms.

[0058] Step 6: As shown in Step 4, the fault direction is the positive direction of the AT. Calculate the fault distance using the positive direction distance measurement formula: .

[0059] According to the calculation results, the fault occurred on the T-line of the fully parallel AT power supply traction network at a distance of 4.98km from the AT station in the positive direction, which is only 20m away from the actual fault location. Therefore, the present invention can realize the fault location of the fully parallel AT power supply traction network.

[0060] Example 2: Using PSCAD / EMTDC electromagnetic transient simulation software, referring to... Figure 1 and Figure 2 A fully parallel AT power supply system was constructed with a sampling rate of 5MHz. The power supply lengths from the traction substation to the AT station and from the AT station to the section substation were both 15km. Furthermore, considering the impact of noise on traveling waves, a signal-to-noise ratio of 30dB was used to verify the practicality of this method. In the simulation model, a fault occurred on the downlink T-line of the section from the traction substation to the AT station, 9km from the AT station, with a transition resistance of 10Ω.

[0061] according to Figure 3 and Figure 4 The method and system for locating traveling wave faults in a fully parallel AT power supply traction network, as shown, include the following specific steps:

[0062] Step 1: After a fault occurs in the fully parallel AT power supply traction network, retrieve the current traveling waves of the upstream T line, upstream F line, downstream T line, and downstream F line of the AT power supply. Figure 9 As shown; perform wavelet transform to extract the maximum value of the traveling wave mode of the initial fault current of each line, such as... Figure 10 As shown.

[0063] Step 2: Locate the maximum amplitude of the initial current traveling wave mode; the corresponding line is identified as the fault line. Figure 10 It can be seen that the initial current traveling wave mode of the fault on the downlink T-line is the largest, therefore, the downlink T-line is determined to be the fault line.

[0064] Step 3: Retrieve the downstream T-line voltage traveling wave data collected by the AT system, perform wavelet transform, and extract the polarity of the initial voltage modulus maximum of the downstream T-line fault. Figure 11 As shown.

[0065] Step 4: Determine the fault direction based on the polarity of the initial voltage and current traveling waves of the faulty line as indicated by the AT; Figure 11 It can be seen that the polarity of the maximum value of the traveling wave mode of the initial voltage during a fault on the downlink T-line is positive. Figure 10 It can be seen that the polarity of the maximum value of the traveling wave mode of the initial current of the downlink T-line fault is positive, and the product of the two is greater than 0, indicating that the fault is in the opposite direction of the AT line.

[0066] Step 5: Retrieve voltage traveling wave data from the traction substation outlet, AT substation, and section substation of the faulty line, and perform wavelet transform to extract the arrival time of the initial traveling wave of the voltage fault, such as... Figure 12 As shown, the fault voltage traveling wave arrives at the traction substation outlet (S end) at 0.0201ms, at the AT substation (M end) at 0.0302ms, and at the section substation (Z end) at 0.0804ms.

[0067] Step 6: As we know from Step 4, the fault direction is opposite to the AT direction. Calculate the fault distance using the opposite direction distance measurement formula: .

[0068] According to the calculation results, the fault occurred on the downlink T-line of the fully parallel AT power supply traction network in the opposite direction of the AT station, at a distance of 9.01km from the AT station, which is only 10m away from the actual fault location. Therefore, the present invention can realize the fault location of the fully parallel AT power supply traction network.

[0069] 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 locating traveling wave faults in a fully parallel AT-powered traction network, characterized in that: Step 1: After a fault occurs in the fully parallel AT power supply traction network, retrieve the current traveling wave data of the AT's upstream T line, upstream F line, downstream T line, and downstream F line, and perform wavelet transform to extract the maximum value of the initial current traveling wave modulus of each line during the fault. Step 2: Find the maximum value of the initial current traveling wave mode with the largest amplitude, and determine the corresponding line as the fault line; Step 3: Retrieve the traveling wave data of the fault line voltage collected by AT, and perform wavelet transform to extract the polarity of the initial voltage traveling wave of the fault line. Step 4: Determine the direction of the fault based on the polarity of the initial voltage traveling wave and the initial current traveling wave of the faulty line in the AT. Step 5: Retrieve voltage traveling wave data of the fault line at the traction substation, AT station and sectioning station, and perform wavelet transform to extract the arrival time of the initial voltage traveling wave of the fault. Step 6: Based on the fault direction determined in Step 4, select the forward or reverse direction distance measurement formula to calculate the fault distance.

2. The method for locating traveling wave faults in a fully parallel AT power supply traction network according to claim 1, characterized in that: In Steps 1, 3, and 5, the wavelet transform uses the derivative of a cubic B-spline function as the wavelet function to obtain the modulus maxima of the wavelet transform in the high-frequency band and extract the arrival time, polarity, and amplitude of the fault traveling wave.

3. The method for locating traveling wave faults in a fully parallel AT power supply traction network according to claim 1, characterized in that: In Step 4, the method for determining the direction of the fault is as follows: ； In the formula, The maximum value of the traveling wave mode of the initial fault current of the AT is given. The maximum value of the traveling wave mode of the initial voltage of the AT fault is given by sign, which indicates its polarity.

4. The method for locating traveling wave faults in a fully parallel AT power supply traction network according to claim 1, characterized in that: In Step 6, the ranging formula for a fault in the opposite direction is: In the formula, x is the distance between the fault point and the AT station when the fault is in the opposite direction; The moment when the initial voltage traveling wave of a fault in the opposite direction reaches terminal S, where terminal S is the traction substation; The moment when the initial voltage traveling wave of the fault reaches terminal M during a reverse fault, where terminal M is AT; The time when the initial voltage traveling wave of a fault reaches the Z-terminus during a reverse fault is the moment when the Z-terminus is the section; the ranging formula for a forward fault is... In the formula, When the fault is in the positive direction, the distance between the fault point and the AT station; This is the moment when the initial fault voltage traveling wave reaches terminal S during a positive-direction fault. This is the moment when the initial fault voltage traveling wave reaches terminal M during a positive-direction fault. The moment when the initial voltage traveling wave of a fault reaches the Z-terminus during a positive-direction fault.

5. A traveling wave fault location system for a fully parallel AT-powered traction network, characterized in that... The method for locating traveling wave faults in a fully parallel AT power supply traction network as described in any one of claims 1-4 specifically includes: Data acquisition module: used to acquire current traveling wave and voltage traveling wave data of AT substation, voltage traveling wave data of traction substation, and voltage traveling wave data of section substation; Data processing module: Analyzes the amplitude of the initial current traveling wave of each line of the AT substation to select the fault line, determines the fault direction based on the polarity of the initial current traveling wave and the initial voltage traveling wave of the fault in the AT substation, and calibrates the arrival time of the initial voltage traveling wave of the fault line in the traction substation, AT substation, and section substation. Numerical calculation module: used to calculate the distance between the fault point and the AT station.

6. A traveling wave fault location system for a fully parallel AT power supply traction network according to claim 5, characterized in that: The data acquisition module specifically includes: Data acquisition unit: used to acquire real-time current traveling wave and voltage traveling wave data of AT substation, voltage traveling wave data of traction substation and voltage traveling wave data of section substation from sensors and other measuring devices; Analog-to-digital converter: Used to convert the acquired analog signals into digital signals.

7. A traveling wave fault location system for a fully parallel AT power supply traction network according to claim 5, characterized in that: The data processing module specifically includes: Fault line selection unit: Determines the fault line by using the magnitude of the maximum value of the initial current traveling wave mode of the AT. Fault direction determination unit: The direction of the fault is determined by the polarity of the traveling wave of the initial voltage and the traveling wave of the initial current of the faulty line. Wave arrival time calibration unit: used to calibrate the arrival time of voltage traveling waves at three locations: the traction substation outlet, the AT station, and the sectioning station.

8. A traveling wave fault location system for a fully parallel AT power supply traction network according to claim 5, characterized in that: The numerical calculation module is used to calculate the fault distance based on the results given by the fault direction discrimination unit and the wave arrival time provided by the wave arrival time calibration unit.

Images