Method for carrying out power transmission line fault location by using traveling wave distance measurement
By comparing the travel waveforms of the faulty phase and the non-faulty phase, identifying and calculating the location of the fault points, the problem of low single-ended ranging accuracy is solved, and higher ranging accuracy and reliability are achieved.
Patent Information
- Application Number
- CN202411409550.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-02-18
AI Technical Summary
The single-ended ranging device has low accuracy when the distance measurement is faulty and is greatly disturbed by harmonics, resulting in insufficient measurement accuracy.
By selecting the travel waveforms of the fault phase and the non-fault phase, a waveform comparison chart is formed, and the initial travel wave, the fault point reflected wave and the reflected wave of the opposite bus, and the distance between the fault point and the local bus or the opposite bus is calculated. , realize fault ranging.
It improves the accuracy of single-ended ranging, reduces harmonic interference, simplifies the wave head recognition process, and improves the accuracy and reliability of fault ranging.
Smart Images
Figure CN119471179A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of transmission line fault location, and in particular to a method for locating transmission line faults by using travelling wave ranging. Background Art
[0002] For transmission lines, when a line fault occurs, how to locate the fault position in a timely and accurate manner, thereby shortening the processing time and the workload of manual inspections, and minimizing the power outage losses and risks, is of great significance. At present, the common fault distance measurement methods are fault analysis method, impedance method, and traveling wave method. The fault analysis method estimates the fault distance based on the voltage and current recording diagrams at the time of the fault, and the impedance method obtains the fault distance by measuring the line impedance. The first two methods have low requirements for equipment performance, but the measurement accuracy is not high. The traveling wave ranging method calculates the fault distance by measuring the time it takes for the voltage and current traveling waves to propagate on the line. This method has high accuracy, but it has high requirements for system sampling, synchronization, and response speed. In recent years, the reliability of power system communication equipment has gradually improved, and the traveling wave ranging method has significant advantages in locating line faults.
[0003] The traveling wave ranging method mainly includes three methods: the first is to measure the time of the fault traveling wave pulse reflecting back and forth between the bus and the fault point, which is called the single-ended electrical quantity method, also called the A-type ranging method, which has the advantages of low investment and no need for communication between the two sides, but due to the influence of factors such as reflections at the ends of other lines on the bus, the ranging results are unstable; the second is to measure the time difference of the fault traveling wave pulse transmitted to the two ends of the bus, which is called the two-end electrical quantity method, also called the D-type method, which has the advantages of simple principle and reliable ranging results, but requires the installation of devices on both sides of the line and communication; the third is to record the transient current traveling wave waveform generated by the fault reclosing switch for ranging, which is also called the E-type method and is suitable for measuring permanent short circuits and disconnection faults. In practical applications, the three methods are used in combination to ensure the reliability and accuracy of ranging, thereby building a traveling wave ranging system.
[0004] Single-ended distance measurement devices are widely used in practice due to their cost advantages, but due to the large harmonic interference during measurement, the measurement accuracy is insufficient. Therefore, it is necessary to study and improve the single-ended distance measurement method to improve the distance measurement accuracy while reducing the distance measurement complexity.
[0005] The patent with publication number CN104793102A discloses a single-ended traveling wave fault ranging method, which uses electrical components that can change the waveform characteristics of the traveling wave installed at the opposite bus to change the waveform characteristics of the reflected wave of the opposite bus, making it significantly different from other traveling wave waveforms. Based on this, the reflected wave of the opposite bus can be directly found from multiple waveforms; the time data corresponding to the first wave and the reflected wave of the opposite bus is brought into the corresponding ranging formula to complete the ranging. This method improves the single-ended ranging method and does not require complex calculations and transformations, but this method requires the installation of electrical components at the opposite bus, which increases the complexity and equipment cost of traveling wave ranging. Therefore, it is particularly important to improve the accuracy of single-ended ranging without increasing the ranging cost and operational complexity. Summary of the invention
[0006] In order to solve the technical problem of low accuracy when a single-ended distance measuring device is used for fault distance measurement, the present invention provides a method for locating transmission line faults using traveling wave distance measurement.
[0007] The technical solution adopted by the present invention is as follows:
[0008] A method for locating transmission line faults using traveling wave ranging is characterized by comprising the following steps: S1, selecting the traveling wave waveform of the fault phase, adjusting the filter parameters, and removing clutter; S2, at the same time, due to induced electricity, other phases or lines with similar distances will produce traveling wave faults, and the traveling wave distribution is consistent with the fault phase, and the traveling wave waveform of a non-fault phase or non-fault line with small harmonic interference, pure waveform and complete information is selected as a comparison item; S3, overlapping the two traveling wave waveforms selected in S1 and S2 to form a waveform comparison diagram; S4, respectively identifying the initial traveling wave of the fault, the reflected wave of the fault point and the reflected wave of the opposite bus, positioning the wave head, and obtaining the time when the initial traveling wave of the fault, the reflected wave of the fault point and the reflected wave of the opposite bus reach the local bus; S5, calculating the distance from the fault point to the local bus / the opposite bus, realizing fault ranging, and finding the fault point.
[0009] Preferably, in S1, the filter parameters include width, gain, and ratio.
[0010] Preferably, in S4, when the opposite bus is connected to more than one line, the current wave generates a positive reflection at the opposite bus, and the reflected wave of the opposite bus is transmitted to the local bus through the fault point. Since the current wave moving toward the opposite bus has an opposite polarity to the current wave moving toward the local bus, the current wave generated by the reflected wave of the opposite bus at the local bus has an opposite polarity to the initial wave of the fault, which is used to distinguish the reflected wave of the fault point and the reflected wave of the opposite bus in the waveform comparison diagram.
[0011] Preferably, in S4, when the opposite-end bus is connected to more than one line, the fault point is within the midpoint of the fault line and there is transmission, the first traveling wave pulse in the waveform comparison diagram is the initial traveling wave of the fault, the second traveling wave pulse is the reflected wave of the fault point, and the third traveling wave pulse is the reflected wave of the opposite-end bus. Specifically, the fault point is within the midpoint of the fault line means that the distance from the fault point to the local bus is shorter than the distance from the fault point to the opposite-end bus.
[0012] Preferably, in S4, when the opposite-end bus is connected to more than one line, the fault point is outside the midpoint of the fault line and there is transmission, the first traveling wave pulse in the waveform is the fault initial traveling wave, the second traveling wave pulse is the opposite-end bus reflected wave, and the third traveling wave pulse is the fault point reflected wave. Specifically, the fault point is outside the midpoint of the fault line means that the distance from the fault point to the local bus is longer than the distance from the fault point to the opposite-end bus.
[0013] Preferably, the distance from the fault point to the local bus in S5 is calculated according to formula (a), and the formula (a) is:
[0014]
[0015] Where: X S1 is the distance from the fault point to the local busbar; T S1 T is the time it takes for the initial fault wave to reach the local bus; S2 is the time it takes for the reflected wave from the fault point to reach the local bus; Δt1 is T S2 and T S1 is the time difference; ν is the wave speed.
[0016] Preferably, the distance from the fault point to the opposite end bus in S5 is calculated according to formula (b), and the formula (b) is:
[0017]
[0018] Where: X S2 T is the distance from the fault point to the opposite busbar; S1 T is the time it takes for the initial fault wave to reach the local bus; S3 is the time it takes for the reflected wave from the other end bus to reach the local end bus; Δt2 is T S3 and T S1 is the time difference; ν is the wave speed.
[0019] Preferably, step S6 is also included after step S5, namely: verifying the accuracy of the traveling wave ranging result, and the verification method includes: if the sum of the distance from the fault point to the local bus and the distance from the fault point to the opposite bus is equal to the actual distance L from the local bus to the opposite bus, it means that the measurement result is accurate; if the sum of the distance from the fault point to the local bus and the distance from the fault point to the opposite bus is not equal to the actual distance L from the local bus to the opposite bus, it means that the measurement result is inaccurate.
[0020] Preferably, the method is applied to a traveling wave ranging device.
[0021] Preferably, the traveling wave ranging device is a traveling wave ranging device that uses the single-ended ranging principle to perform fault ranging; more preferably, the traveling wave ranging device is an XCF-2000 traveling wave ranging device.
[0022] In summary of the above technical solutions, the beneficial effects of the present invention are as follows: the present invention discloses a method for locating transmission line faults using traveling wave ranging, which is applied to a traveling wave ranging device that uses the single-ended ranging principle to perform fault ranging. When applied to lines above 500kV, at the moment of the fault, the interference caused by harmonics is large, and it is difficult to identify the wave heads of the initial traveling wave, reflected traveling wave, and transmitted traveling wave of the fault. However, for lines that are different or close to the non-fault phases, the induced voltage is usually large. After the fault occurs, the induced voltage will also generate a corresponding traveling wave waveform on the non-fault line. By comparing the current traveling wave waveform of the fault phase with the current traveling wave waveform of the non-fault phase or the non-fault line with a similar distance, the wave head of the fault line traveling wave can be simply, quickly, and accurately recognized, thereby improving the accuracy of fault ranging. In addition, the present application also verifies the accuracy of the ranging result by calculating the distance from the fault point to the opposite end bus, further improving the accuracy of fault ranging. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a flow chart of a method for locating a transmission line fault using traveling wave ranging in the present application;
[0024] Figure 2 It is a traveling wave schematic diagram of the initial traveling wave of the fault on the fault line and the reflected wave at the fault point in this application;
[0025] Figure 3 It is a schematic diagram of the current traveling wave of the fault line when more than one line is connected to the opposite end busbar and the fault point is within the midpoint of the line in this application;
[0026] Figure 4 It is a schematic diagram of the current traveling wave of the fault line when more than one line is connected to the opposite end busbar and the fault point is outside the midpoint of the line in this application;
[0027] Figure 5is a current traveling wave waveform diagram of the fault phase in the application embodiment 1 of the present application;
[0028] Figure 6 It is a comparison diagram of the current traveling wave waveforms of the fault phase and the non-fault phase in Application Example 1 of the present application. DETAILED DESCRIPTION
[0029] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.
[0030] Reference Figure 1 In the present application, a method for locating transmission line faults using traveling wave ranging mainly includes the following steps: selecting a traveling wave waveform of a fault phase and adjusting it with a filter; selecting a traveling wave waveform of a non-fault phase or non-fault line with small harmonic interference, pure waveform and complete information as a comparison item; overlapping two traveling wave waveforms to form a waveform comparison diagram; respectively identifying the initial traveling wave of the fault, the reflected wave at the fault point and the reflected wave at the opposite bus, positioning the wave heads, and obtaining the time when various waves arrive at the local bus; calculating the distance from the fault point to the local bus / the opposite bus; and verifying the accuracy of the fault ranging.
[0031] In the application of single-ended distance measurement, wave identification is the key. To improve the accuracy of fault distance measurement, it is necessary to accurately identify the initial fault traveling wave, the reflected wave at the fault point, and the reflected wave of the opposite busbar, and accurately locate the wave head. Figure 2-4 The specific identification method of the initial fault traveling wave, the reflected wave at the fault point and the reflected wave of the opposite bus is as follows:
[0032] like Figure 2 As shown in the figure, the formation principle of the initial fault traveling wave and the reflected wave at the fault point is as follows: when there is more than one line connected to the local bus, the initial fault traveling wave generated by the fault will reach the local bus first. At the same time, since the current traveling wave on the line will produce positive reflection at the local bus, the initial fault traveling wave generated by the fault will be reflected back and forth between the fault point and the local bus, and form the first fault point reflected wave, the second fault point reflected wave, the third fault point reflected wave, and so on. The waveforms of these fault point reflected waves gradually decay but the polarity remains unchanged. The distance to the fault can be calculated by applying the distance measurement principle based on the time difference between the first fault point reflected wave and the initial fault traveling wave.
[0033] When the opposite bus is connected to more than one line, the current wave generates positive reflection at the opposite bus, and the reflected wave of the opposite bus is transmitted to the local bus through the fault point. Since the current wave moving toward the opposite bus has the opposite polarity to the current wave moving toward the local bus, the current wave generated by the reflected wave of the opposite bus at the local bus is opposite in polarity to the current wave at the initial fault. This is used to distinguish the reflected wave at the fault point and the reflected wave of the opposite bus in the waveform comparison diagram. For details, see Figure 3 and Figure 4 .
[0034] like Figure 3 As shown in the figure, when the opposite bus is connected to more than one line, the fault point is within the midpoint of the fault line and there is transmission, the first traveling wave pulse is the initial traveling wave of the fault. Since the traveling wave path of the reflected wave at the fault point is shorter than that of the reflected wave at the opposite bus, it reaches the local bus first. Therefore, the second traveling wave pulse is the reflected wave at the fault point, and the third traveling wave pulse is the reflected wave at the opposite bus.
[0035] like Figure 4 As shown in the figure, when the opposite bus is connected to more than one line, the fault point is outside the midpoint of the fault line and there is transmission, the first traveling wave pulse in the waveform is the initial traveling wave of the fault. Since the traveling wave path of the reflected wave from the opposite bus is shorter than the traveling wave path of the reflected wave from the fault point, it reaches the local bus first. Therefore, the second traveling wave pulse is the reflected wave from the opposite bus, and the third traveling wave pulse is the reflected wave from the fault point.
[0036] Application Example 1
[0037] A single-phase grounding fault occurs on a line at a station. According to a method for locating a transmission line fault using traveling wave ranging in this application, the fault point is located. Figure 1 , the method comprising:
[0038] S1. Click on the manual analysis interface of the single-ended traveling wave ranging analysis system of the XCF-2000 traveling wave ranging device, select the fault phase, and select the B phase of the fault line. At this time, the traveling wave waveform of phase B is displayed; according to the actual fault situation, adjust the filter width, set the gain to 0.25, and set the ratio to 1 to make the waveform display more friendly and pure. According to the waveform distribution, it can be seen that the reflected wave of the opposite bus is after the reflected wave of the fault point, so the fault point is close to the local substation. However, after adjusting the parameters, due to harmonics, the wave head interference is still large, and the wave head cannot be accurately positioned, such as Figure 5 As shown;
[0039] S2. At the same time, due to induced electricity, other phases or lines with close distances will also produce traveling wave faults, and the traveling wave distribution is consistent with the fault phase B. The traveling wave waveform of the non-fault phase or non-fault line with small harmonic interference, pure waveform and complete information is selected as the comparison item. This time, the non-fault phase A of the fault line is selected as the comparison item;
[0040] S3, overlap the two waveforms of the fault phase B and the non-fault phase A to form a waveform comparison diagram, such as Figure 6 As shown;
[0041] S4. Identify the initial fault traveling wave on the traveling wave comparison diagram, and position the wave head. The calculation starts from the time when the initial fault traveling wave reaches the local bus, that is, T S1 =0; identify the reflected wave of the fault point on the traveling wave comparison diagram, perform wave head positioning, and obtain the time T when the reflected wave of the fault point reaches the local bus S2 0.200ms; identify the reflected wave of the opposite bus on the traveling wave comparison diagram, perform wave head positioning, and obtain the time T when the reflected wave of the opposite bus reaches the local bus S3 is 0.412ms; the wave velocity ν is calibrated by the XCF-2000 type traveling wave ranging device during operation, and the value of ν is 291kM / ms;
[0042] S5. T S1 =0; T S2 =0.200ms; ν = 291kM / ms Substitute into formula (a) to calculate the distance X from the fault point to the local busbar S1 =29.1kM, realize fault distance measurement and find the fault point;
[0043] The formula (a) is:
[0044]
[0045] T S1 =0; T S3 =0.412ms; ν = 291kM / ms Substitute into formula (b) to calculate the distance X from the fault point to the opposite busbar S2 =59.946km, realize fault distance measurement and find the fault point;
[0046] The formula (b) is:
[0047]
[0048] S6. Verify the accuracy of the fault distance measurement result, the verification method is:
[0049] If the distance from the fault point to the local bus is X S1 And the distance from the fault point to the opposite busbar X S2 The added sum is equal to the actual distance L from the local bus to the opposite bus, indicating that the measurement result is accurate.
[0050] If the distance from the fault point to the local bus is X S1 And the distance from the fault point to the opposite busbar X S2The added sum is not equal to the actual distance L from the local bus to the opposite bus, indicating that the measurement result is inaccurate.
[0051] It should be noted that, in the solution of the embodiment of the present application, if the sum of XS1 and XS2 is not equal to the actual distance L from the local bus to the opposite bus, but the difference between the two is less than the preset error threshold, the measurement result is also considered to be accurate. Optionally, the above error threshold can be 0.1 kM. Of course, the error threshold can also be set according to actual conditions, and the embodiment of the present application does not make specific limitations.
[0052] For example, X S1 and X S2 The sum is 89.046 km, which is roughly equal to the actual distance from the local bus to the opposite bus, 89.1 km. The difference between the two, 0.054 km, does not exceed the set error threshold of 0.1 km, indicating that the measurement result is accurate.
[0053] In addition, after the fault occurred, the fault recorder showed that the distance from the fault point to the local bus was 31.5kM, the line protection showed that the distance from the fault point to the local bus was 32.1kM, and the traveling wave ranging system automatically gave the distance from the fault point to the local bus as 30.1kM. The distance from the fault point to the local bus obtained by using the method of overlapping the two-phase traveling wave curves in this application to locate the wave head was 29.1kM, and the actual distance from the fault point to the local bus was 28.9kM. Compared with other methods, the single-ended traveling wave ranging method of this application is more accurate in identifying fault points.
[0054] Application Example 2
[0055] A single-phase grounding fault occurs in a line at a certain station. According to a method for locating a transmission line fault using traveling wave ranging in the present application, the fault point is located. The single-ended traveling wave ranging analysis system of the XCF-2000 traveling wave ranging device is used. The fault phase is phase C of the faulty line. Phase A of the faulty line is selected as the comparison item. Based on the waveform comparison of the two, according to formulas (a) and (b), it is calculated that the distance from the fault point to the local bus is 75.369 km, and the distance from the fault point to the opposite bus is 13.8225 km; the sum of the two is 89.1915 km, which is approximately equal to the actual distance from the local bus to the opposite bus of 89.1 km. The difference of 0.0915 km does not exceed the set error threshold of 0.1 km, indicating that the measurement result is accurate.
[0056] In addition, after the fault occurred, the traveling wave ranging system automatically gave a distance of 80.1 km from the fault point to the local busbar. The distance from the fault point to the local busbar obtained by using the method of overlapping the two-phase traveling wave curves in this application to locate the wave head was 75.369 km. The actual distance of the fault point was 75.1 km. Compared with the single-ended ranging method of the traveling wave ranging system, the improved single-ended traveling wave ranging method of this application can identify the fault point more accurately.
[0057] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A method for locating a transmission line fault using traveling wave ranging, characterized in that: The following steps are involved: S1. Select the traveling wave waveform of the fault phase, adjust the filter parameters, and remove the clutter; S2. At the same time, due to induced electricity, other lines with different phases or close distances will produce traveling wave faults, and the distribution of the traveling wave coincides with the fault phase. The traveling wave waveform of the non-fault phase or non-fault line with small harmonic interference, pure waveform and complete information is selected as the comparison item; S3. Overlap the two traveling wave waveforms selected in S1 and S2 to form a waveform comparison chart; S4. Respectively identify the initial traveling wave of the fault, the reflected wave at the fault point and the reflected wave of the opposite bus, and position the wave head to obtain the time when the initial traveling wave of the fault, the reflected wave at the fault point and the reflected wave of the opposite bus reach the local bus; S5. Calculate the distance from the fault point to the local bus / opposite bus, realize fault distance measurement, and find the fault point.
2. A method for locating a transmission line fault using traveling wave ranging as claimed in claim 1, characterized in that: In S1, the filter parameters include width, gain and ratio.
3. The method for locating a power transmission line fault using traveling wave ranging as claimed in claim 1, characterized in that: In S4, when the opposite bus is connected to more than one line, the current traveling wave generates a positive reflection at the opposite bus, and the reflected wave of the opposite bus is transmitted to the local bus through the fault point. Since the current traveling wave moving toward the opposite bus has the opposite polarity to the current traveling wave moving toward the local bus, the current traveling wave generated by the reflected wave of the opposite bus at the local bus has the opposite polarity to the initial traveling wave of the fault, which is used to distinguish the reflected wave at the fault point and the reflected wave of the opposite bus in the waveform comparison diagram.
4. A method for locating a transmission line fault using traveling wave ranging as claimed in claim 3, characterized in that: In S4, when the fault point is within the midpoint of the fault line and there is transmission, the first traveling wave pulse in the waveform comparison diagram is the initial traveling wave of the fault, the second traveling wave pulse is the reflected wave of the fault point, and the third traveling wave pulse is the reflected wave of the opposite bus.
5. The method for locating a power transmission line fault using traveling wave ranging as claimed in claim 3, characterized in that: In S4, when the fault point is outside the midpoint of the fault line and there is transmission, the first traveling wave pulse in the waveform is the initial traveling wave of the fault, the second traveling wave pulse is the reflected wave of the opposite bus, and the third traveling wave pulse is the reflected wave of the fault point.
6. The method for locating a power transmission line fault using traveling wave ranging as claimed in claim 1, characterized in that: The distance from the fault point in S5 to the local busbar is calculated according to formula (a), which is: Where: X S1 is the distance from the fault point to the local busbar; T S1 T is the time it takes for the initial fault wave to reach the local bus; S2 is the time it takes for the reflected wave from the fault point to reach the local bus; Δt1 is T S2 and T S1 is the time difference; ν is the wave speed.
7. The method for locating a power transmission line fault using traveling wave ranging as claimed in claim 1, characterized in that: The distance from the fault point in S5 to the opposite busbar is calculated according to formula (b), which is: Where: X S2 T is the distance from the fault point to the opposite busbar; S1 T is the time it takes for the initial fault wave to reach the local bus; S3 is the time it takes for the reflected wave from the other end bus to reach the local end bus; Δt2 is T S3 and T S1 is the time difference; ν is the wave speed.
8. The method for locating a transmission line fault using traveling wave ranging as claimed in claim 1, characterized in that: After step S5, step S6 is also included, namely: verifying the accuracy of the traveling wave ranging result, and the verification method includes: if the sum of the distance from the fault point to the local bus and the distance from the fault point to the opposite bus is equal to the actual distance L from the local bus to the opposite bus, it means that the measurement result is accurate; if the sum of the distance from the fault point to the local bus and the distance from the fault point to the opposite bus is not equal to the actual distance L from the local bus to the opposite bus, it means that the measurement result is inaccurate.
9. The method for locating a power transmission line fault using traveling wave ranging as claimed in claim 1, characterized in that: The method is applied to a traveling wave ranging device.
10. The method for locating a power transmission line fault using traveling wave ranging as claimed in claim 9, characterized in that: The traveling wave distance measuring device is a traveling wave distance measuring device which performs fault distance measurement by using the single-ended distance measuring principle.
Citation Information
Patent Citations
Single-ended traveling-wave fault distance measurement method
CN104793102A