Traveling wave fault positioning method and system for full parallel AT power supply traction network

Abstract

The invention discloses a traveling wave fault positioning method and system for a full parallel AT power supply traction network, and belongs to the field of railway traction power supply system relay protection. The method specifically comprises the following steps: after the full parallel AT power supply traction network has a fault, firstly, analyzing the characteristics of an AT station fault initial current traveling wave, and determining a fault line by using the amplitude of the AT station fault initial current traveling wave; then, the polarity of the fault initial current traveling wave and the fault initial voltage traveling wave of the AT station fault line is used for judging the fault direction; and finally, calculating the fault distance by selecting a positive direction or negative direction distance measurement formula according to the moment when the fault initial voltage traveling wave arrives at the outlet of the traction substation, the AT station and the subarea station and the fault direction information. According to the method, only fault initial traveling wave information is utilized, wave head identification is not needed, wave velocity parameters are not needed, and simulation results show that the positioning method not only can provide fault distance, but also can provide fault line information, is convenient for maintainers to quickly find fault points, and has extremely high robustness and accuracy.

Description

Technical Field

[0001] The invention relates to a traveling wave fault locating method and system for a full-parallel AT power supply traction network, and belongs to the field of relay protection of railway traction power supply systems. Background Art

[0002] The full parallel AT traction power supply mode has the characteristics of 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 exposed to the natural environment for a long time. Strong winds, ice and snow, dirt, foreign objects intrusion, etc. can cause short-circuit faults and affect the normal operation of trains. Therefore, fast and accurate fault location is of great significance for railway operation. At present, the fault location methods of the full parallel AT power supply traction network mainly include impedance method and current ratio method, and the positioning accuracy is low.

[0003] The traveling wave fault distance measurement method has been widely studied and applied in power systems. The traveling wave method has high accuracy and reliability in fault distance measurement, and its application in traction power supply system fault distance measurement is a new attempt. However, the wiring form of the full parallel AT power supply traction network is complex, the propagation characteristics of the traveling wave are complex, and the wave head identification is difficult. The application prospect of the single-ended traveling wave method is relatively small. At the same time, due to the asymmetric structure of the traction network, the double-ended traveling wave method cannot accurately determine the traveling wave velocity, and the ranging accuracy is poor.

[0004] In summary, although the traveling wave method for fault location has good application prospects and high ranging accuracy, there are still some problems when it is applied to the full 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 the full parallel AT traction network. Summary of the invention

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

[0006] In order to achieve the above-mentioned purpose, 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 station fault are analyzed, and the fault line is determined by using its amplitude; then, the fault direction is determined by using the polarity of the initial current traveling wave of the AT station fault line and the initial voltage traveling wave of the fault; finally, the time when the initial voltage traveling wave of the fault arrives at the traction substation exit, AT station and substation is used, and the positive direction or reverse direction ranging formula is selected in combination with the fault direction information to calculate the fault distance, forming a complete traveling wave fault location method and system for a fully parallel AT power supply traction network.

[0007] On the one hand, the present invention provides a traveling wave fault location method for a fully parallel AT power supply traction network, which specifically includes: Step 1: After a fault occurs in the fully parallel AT power supply traction network, the current traveling wave data of the AT's upstream T line, upstream F line, downstream T line, and downstream F line are retrieved and wavelet transform is performed to extract the maximum value of the initial current traveling wave modulus of each line;

[0008] 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;

[0009] Step 3: retrieve the fault line voltage traveling wave data collected by AT, perform wavelet transform, and extract the initial voltage traveling wave polarity of the fault line;

[0010] Step 4: Determine the fault direction according to the polarity of the initial fault voltage wave and the initial fault current wave of the fault line of the AT;

[0011] Step 5: retrieve the voltage traveling wave data of the fault line at the traction substation, AT station and substation, and perform wavelet transform to extract the arrival time of the initial traveling wave of the voltage fault;

[0012] Step 6: According to the fault direction determined in Step 4, select the forward direction or reverse direction ranging formula to calculate the fault distance.

[0013] Furthermore, in Step 1, Step 3 and Step 5, the wavelet transform uses the derivative function of the cubic B-spline function as the wavelet function to obtain the maximum value of the wavelet transform modulus in the high-frequency band and extract the arrival time, polarity and amplitude of the fault traveling wave.

[0014] Furthermore, in Step 4, the method for determining the fault direction is:

[0015]

[0016] In the formula, is the maximum value of the initial current traveling wave mode of the AT fault, is the maximum value of the initial voltage traveling wave mode of AT fault, and sign represents its polarity.

[0017] Furthermore, in Step 6, the distance measurement formula for the reverse direction fault is: , where x is the distance between the fault point and the AT station when the fault occurs in the reverse direction. is the moment when the initial fault voltage wave reaches the S end (traction substation), is the moment when the initial fault voltage wave reaches the M terminal (AT), It is the moment when the initial voltage wave of the fault reaches the Z end (district office); the distance measurement formula for the positive direction fault is: ; In the formula, In case of positive fault, the distance between the fault point and the AT station; is the moment when the initial fault voltage wave reaches the S end (traction substation), is the moment when the initial fault voltage wave reaches the M terminal (AT), It is the moment when the initial fault voltage wave reaches the Z end (partition).

[0018] Another aspect of the present invention provides a traveling wave fault location system for a fully parallel AT power supply traction network, specifically comprising: Data acquisition module: used to collect current and voltage traveling waves of AT stations, voltage traveling waves of traction substations, and voltage traveling waves of substations; Data processing module: Analyze the amplitude of the initial current wave of each line of the AT station to select the fault line, identify the fault direction according to the polarity of the initial current wave of the AT station and the initial voltage wave of the fault, and calibrate the arrival time of the initial voltage wave of the fault line at the traction substation, AT station and substation; Numerical calculation module: used to calculate the distance between the fault point and the AT station.

[0019] Furthermore, the data acquisition module specifically includes: Data acquisition unit: used to collect the current and voltage traveling waves of AT stations, traction substation voltage traveling waves and substation voltage traveling wave data in real time from sensors and other measuring devices; Analog-to-digital conversion unit: used to convert the collected analog signals into digital signals.

[0020] Furthermore, the data processing module specifically includes: Fault line selection unit: Determine the fault line by using the maximum amplitude of the initial current traveling wave mode of the AT; Fault direction determination unit: Determine the fault direction by using the polarity of the initial fault voltage wave and the initial fault current wave of the fault line of the AT station; Wave arrival time calibration unit: used to calibrate the wave arrival time of voltage traveling waves at the traction substation outlet, AT station and substation.

[0021] Furthermore, the numerical calculation module is used to calculate the fault distance according to the result given by the fault direction determination unit and the wave arrival time proposed by the wave arrival time calibration unit.

[0022] The beneficial effects of the present invention are: 1. The present invention uses the AT of the full-parallel AT traction power supply system as the third measuring point, and proposes a traveling wave fault location method for the full-parallel AT power supply traction network. Compared with the single-end traveling wave method, the method does not need to identify the wave head, avoiding the problem of difficult wave head identification caused by the complex wiring of the full-parallel AT traction network; compared with the double-end traveling wave method, the distance measurement formula provided by the method does not require the wave speed parameter, can be immune to the influence of the wave speed, and avoids the problem that the wave speed cannot be accurately calculated due to the asymmetry of the traction network parameters; 2. The present invention combines the structural characteristics of the full parallel AT traction network and uses the traveling wave method to perform fault distance measurement. Compared with the traditional impedance method and current ratio method, the present invention has extremely high robustness and accuracy. At the same time, the present invention not only provides the fault distance, but also provides the fault line information, which is convenient for maintenance personnel to quickly find the fault point; 3. The present invention performs data processing locally in the traction substation, AT station and substation. The traction substation and substation only need to send the wave arrival time to the AT station, thus avoiding the transmission of large amounts of data and ranging errors caused by packet loss during the transmission process.

[0023] To sum up, the present invention combines the characteristics of a fully parallel AT power supply traction network to provide a traveling wave fault location method and system for a fully parallel AT power supply traction network. This method has great advantages over the single-ended traveling wave method, the double-ended traveling wave method, the traditional impedance method and the current ratio method, and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to better understand the above technical solution, the exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art. The accompanying drawings of the present invention are as follows: Figure 1 This is a full parallel AT power supply system diagram of the present invention; Figure 2 This is a structural diagram of the full parallel AT power supply traction network of the present invention; Figure 3 It is a flow chart of the traveling wave fault location method of the full parallel AT power supply traction network of the present invention; Figure 4 It is a module block diagram of the traveling wave fault location system of the full parallel AT power supply traction network of the present invention; Figure 5 This is a traveling wave diagram of the current of each line of AT in the full parallel AT power supply system in Example 1 of the present invention; Figure 6 The maximum value distribution diagram of the traveling wave modulus of the fault current of each line of the AT in Example 1 of the present invention; Figure 7 The traveling wave of the fault line voltage of AT in Embodiment 1 of the present invention and the distribution diagram of the modulus maximum value after the corresponding wavelet transformation; Figure 8 The fault voltage traveling wave and its modulus maximum distribution diagram at each measuring point in Example 1 of the present invention; Fig. 9 The traveling wave diagram of the current of each line of AT in Example 2 of the present invention; Fig.10 The maximum value distribution diagram of the traveling wave modulus of the fault current of each line of the AT in the second embodiment of the present invention; Fig.11 The traveling wave of the fault line voltage of AT in Embodiment 2 of the present invention and the distribution diagram of the modulus maximum value after the corresponding wavelet transformation; Fig.12 1 is a distribution diagram of the fault voltage traveling waves and their modulus maximum values ​​at each measuring point in Example 2 of the present invention. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The purpose of the present 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 problem of inaccurate and unreliable fault location in the existing fully parallel AT power supply traction network. The present invention is further described below in conjunction with specific implementation methods.

[0027] Example 1: Using PSCAD / EMTDC electromagnetic transient simulation software, refer to Figure 1 and Figure 2 , build a full parallel AT power supply system with a sampling rate of 5MHz. Among them, the power supply length from the traction substation to the AT station and from the AT station to the substation is 15km. In addition, considering the impact of noise on traveling waves, a 30dB signal-to-noise ratio noise is considered to verify the practicality of this method. In the simulation model, it is set that the uplink T line from the AT station to the substation section fails 5km away from the AT station, and the transition resistance is 10Ω.

[0028] according to Figure 3 and Figure 4 The traveling wave fault location method and system for the full parallel AT power supply traction network shown in the figure perform fault location, and the specific steps include:

[0029] Step 1: After a fault occurs in the fully parallel AT power supply traction network, the current traveling waves of the AT's upstream T line, upstream F line, downstream T line, and downstream F line are retrieved, such as Figure 5 As shown; perform wavelet transform to extract the maximum value of the initial current traveling wave modulus of each line fault, as shown Figure 6 shown.

[0030] 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; Figure 6 It can be seen that the maximum value of the traveling wave mode of the initial current of the upward T line fault is the largest, so the upward T line is determined to be the fault line.

[0031] Step 3: retrieve the upstream T-line voltage traveling wave data collected by AT, perform wavelet transform, and extract the maximum polarity of the upstream T-line fault initial voltage traveling wave modulus, such as Figure 7 shown.

[0032] Step 4: Determine the fault direction according to the polarity of the initial fault voltage wave and the initial fault current wave of the fault line of AT; Figure 7 It can be seen that the polarity of the maximum value of the traveling wave mode of the initial voltage of the upstream T-line fault is positive, which is Figure 6 It can be seen that the polarity of the maximum value of the initial current traveling wave modulus of the upstream T-line fault is negative, and the product of the two is less than 0, which is judged to be a fault in the positive direction of AT.

[0033] Step 5: retrieve the voltage traveling wave data of the fault line at the traction substation exit, AT station and 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 time when the fault voltage traveling wave reaches the traction substation outlet (S end) is 0.0668ms, the time when it reaches the AT station (M end) is 0.0168ms, and the time when it reaches the substation (Z end) is 0.0336ms.

[0034] Step 6: From Step 4, we know that the fault direction is the positive direction of the AT. Select the positive direction distance measurement formula to calculate the fault distance: .

[0035] According to the calculation results, the uplink T-line of the fully parallel AT power supply traction network fails in the positive direction of the AT station, 4.98 km away from the AT station, which is only 20 m away from the actual fault location. Therefore, the present invention can realize fault locating of the fully parallel AT power supply traction network.

[0036] Example 2: Using PSCAD / EMTDC electromagnetic transient simulation software, refer to Figure 1 and Figure 2, build a full parallel AT power supply system with a sampling rate of 5MHz. Among them, the power supply length from the traction substation to the AT station and from the AT station to the substation is 15km. In addition, considering the impact of noise on traveling waves, a 30dB signal-to-noise ratio noise is considered to verify the practicality of this method. In the simulation model, a fault occurs on the downlink T line from the traction substation to the AT station at 9km away from the AT station, and the transition resistance is 10Ω.

[0037] according to Figure 3 and Figure 4 The traveling wave fault location method and system for the full parallel AT power supply traction network shown in the figure perform fault location, and the specific steps include:

[0038] Step 1: After a fault occurs in the fully parallel AT power supply traction network, the current traveling waves of the AT's upstream T line, upstream F line, downstream T line, and downstream F line are retrieved, such as Fig. 9 As shown; perform wavelet transform to extract the maximum value of the initial current traveling wave modulus of each line fault, as shown Fig.10 shown.

[0039] 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; Fig.10 It can be seen that the maximum value of the traveling wave mode of the initial current of the downstream T line fault is the largest, so the downstream T line is determined to be the fault line.

[0040] Step 3: retrieve the downstream T-line voltage traveling wave data collected by AT, perform wavelet transform, and extract the maximum polarity of the downstream T-line fault initial voltage traveling wave modulus, such as Fig.11 shown.

[0041] Step 4: Determine the fault direction according to the polarity of the initial fault voltage wave and the initial fault current wave of the fault line of AT; Fig.11 It can be seen that the polarity of the maximum value of the traveling wave mode of the initial voltage of the downlink T line fault is positive, which is Fig.10 It can be seen that the polarity of the maximum value of the traveling wave modulus of the initial current of the downstream T line fault is positive, and the product of the two is greater than 0, which is judged to be a fault in the opposite direction of AT.

[0042] Step 5: retrieve the voltage traveling wave data at the fault line traction substation exit, AT station and substation, and perform wavelet transform to extract the arrival time of the initial traveling wave of the voltage fault, such as Fig.12 As shown in the figure, the time when the fault voltage wave reaches the traction substation outlet (S end) is 0.0201ms, the time when it reaches the AT station (M end) is 0.0302ms, and the time when it reaches the substation (Z end) is 0.0804ms.

[0043] Step 6: According to Step 4, the fault direction is opposite to the AT direction. Select the reverse direction distance measurement formula to calculate the fault distance: .

[0044] According to the calculation results, the downlink T-line of the fully parallel AT power supply traction network fails in the opposite direction of the AT station, 9.01 km away from the AT station, which is only 10 meters away from the actual fault location. Therefore, the present invention can realize fault positioning of the fully parallel AT power supply traction network.

[0045] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A traveling wave fault location method for a fully parallel AT power supply traction network, characterized by: Step 1: After a fault occurs in the fully parallel AT power supply traction network, the current traveling wave data of the AT's upstream T line, upstream F line, downstream T line, and downstream F line are retrieved and wavelet transform is performed to extract the maximum value of the initial current traveling wave modulus of each line; 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 fault line voltage traveling wave data collected by AT, perform wavelet transform, and extract the initial voltage traveling wave polarity of the fault line; Step 4: Determine the fault direction according to the polarity of the initial fault voltage wave and the initial fault current wave of the fault line of the AT; Step 5: retrieve the voltage traveling wave data of the fault line at the traction substation, AT station and substation, and perform wavelet transform to extract the arrival time of the initial voltage traveling wave of the fault; Step 6: According to the fault direction determined in Step 4, select the forward direction or reverse direction ranging formula to calculate the fault distance.

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

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

4. The traveling wave fault location method for a fully parallel AT power supply traction network according to claim 1 is characterized in that: In Step 6, the distance measurement formula for the reverse direction fault is: , where x is the distance between the fault point and the AT station when the fault occurs in the reverse direction. is the moment when the initial fault voltage wave reaches the S end (traction substation), is the moment when the initial fault voltage wave reaches the M terminal (AT), It is the moment when the initial voltage wave of the fault reaches the Z end (district office); the distance measurement formula for the positive direction fault is: ; In the formula, In case of positive fault, the distance between the fault point and the AT station; is the moment when the initial fault voltage wave reaches the S end (traction substation), is the moment when the initial fault voltage wave reaches the M terminal (AT), It is the moment when the initial fault voltage wave reaches the Z end (partition).

5. A traveling wave fault location system for a fully parallel AT powered traction network, the characteristics of which include: Data acquisition module: used to collect current and voltage traveling waves of AT stations, voltage traveling waves of traction substations, and voltage traveling waves of substations; Data processing module: Analyze the amplitude of the initial current traveling wave of each line of the AT station to select the fault line, identify the fault direction according to the polarity of the initial current traveling wave and the initial voltage traveling wave of the AT station, and calibrate the arrival time of the initial voltage traveling wave of the fault line of the traction substation, AT station and substation; Numerical calculation module: used to calculate the distance between the fault point and the AT station.

6. The 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 collect the current and voltage traveling waves of AT stations, traction substation voltage traveling waves and substation voltage traveling wave data in real time from sensors and other measuring devices; Analog-to-digital conversion unit: used to convert the collected analog signals into digital signals.

7. The 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: Determine the fault line by using the maximum amplitude of the initial current traveling wave mode of the AT; Fault direction determination unit: Determine the fault direction by using the polarity of the initial fault voltage wave and the initial fault current wave of the fault line of the AT station; Wave arrival time calibration unit: used to calibrate the wave arrival time of voltage traveling waves at the traction substation outlet, AT station and substation.

8. A traveling wave fault location system for a fully parallel AT powered traction network, characterized in that: The numerical calculation module is used to calculate the fault distance according to the result given by the fault direction determination unit and the wave arrival time provided by the wave arrival time calibration unit.

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