A fault location method for overhead transmission line based on double-ended traveling wave induction

Abstract

The application provides a kind of overhead transmission line fault location method based on double-ended induction traveling wave, comprising: extracting transmission line non-fault phase induction traveling wave;Distinguish the wave head of non-fault phase induction traveling wave and determine the starting time of wave head;Based on wave head starting time, calculate the time difference of wave head of two sides of fault point;Based on the line distance between adjacent two traveling wave collection devices and the time difference of traveling wave head collected by adjacent two traveling wave collection devices, calculate the traveling wave propagation speed, determine the fault point position based on the traveling wave propagation speed, the time difference of traveling wave head of two sides of fault point and the distance between the traveling wave collection devices of two sides of fault point.The application can accurately calculate the fault position of transmission line in the case of damage of fault phase traveling wave collection device and missing of fault traveling wave compared with traditional method, reduce fault troubleshooting time, improve line operation level and power supply reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power transmission line fault locating, in particular to an overhead power transmission line fault locating method based on double-ended induced traveling wave. BACKGROUND

[0002] Overhead power transmission lines often have grounding faults due to lightning strikes and the like, and timely determination of the fault location is of great significance for accident repair and power supply reliability. Traveling wave has the advantages of large fault mutation amplitude and high sensitivity, and is easy to measure. Current fault traveling wave locating methods include double-ended and single-ended methods, which mainly focus on traveling wave locating technology for branch lines, traveling wave characteristics for overhead-cable hybrid lines, and traveling wave waveform collection and processing algorithms. Double-ended fault traveling wave method is the preferred method for fault point positioning, which is mainly based on the waveforms recorded by the fault phase traveling wave collection devices on both sides of the fault point to calculate the fault location. However, these are based on the premise that the traveling wave collection device can record the traveling wave waveform of the fault phase at the fault time. In actual operation, the traveling wave collection device of the power transmission line often cannot collect the traveling wave waveform of the fault phase at the fault time due to offline, fault, and other reasons. At this time, the traveling wave waveform of the fault phase cannot be collected, which leads to the failure to locate the fault point and the long time-consuming fault locating SUMMARY

[0003] The present application proposes a method for fault locating based on the induced traveling wave collected by the non-fault phase on the same tower, which solves the problem of failure to locate the fault due to the failure to collect the traveling wave of the fault phase.

[0004] An overhead power transmission line fault locating method based on double-ended induced traveling wave, comprising the following steps:

[0005] Extracting the induced traveling wave of the non-fault phase of the power transmission line;

[0006] Determining the wave head of the induced traveling wave of the non-fault phase and the starting time of the wave head;

[0007] Calculating the time difference of the wave head of the fault point on both sides based on the starting time of the wave head;

[0008] Calculating the traveling wave propagation speed based on the line distance between the adjacent two traveling wave collection devices and the time difference of the traveling wave wave head collected by the adjacent two traveling wave collection devices, and determining the fault point position based on the traveling wave propagation speed, the time difference of the traveling wave wave head of the fault point on both sides, and the distance between the traveling wave collection devices on both sides of the fault point.

[0009] Further, the extracting the induced traveling wave of the non-fault phase of the power transmission line comprises:

[0010] Time synchronizing the traveling wave waveforms of the fault phase and the non-fault phase at the fault time, and comprehensively considering the fault phase and the non-fault phase

[0011] The fault phase traveling wave and the non-fault phase induced traveling wave are divided into two categories according to the fault time, the power frequency current and the traveling wave waveform recorded by the traveling wave acquisition device.

[0012] Further, the wave head of the non-fault phase induced traveling wave is identified and the wave head starting time is determined by using the wavelet transform and threshold judgment method, and when the wave head traveling wave value is greater than 10 times the noise level, it is considered that the traveling wave has a sudden change, and the sudden change time is taken as the wave head starting time.

[0013] Further, the noise level is calculated according to the following formula:

[0014]

[0015] Wherein, n is the n sampling points recorded by the traveling wave acquisition device before the fault time, n = 500 or 1000, i n is the traveling wave sampling value;

[0016] The wave head criterion is as follows:

[0017] i0>10*N L

[0018] Where i0 is the traveling wave sampling value at t0, and if the criterion condition is met, t0 is considered as the wave head starting time.

[0019] Further, the time difference of the wave heads on both sides of the fault point is calculated based on the wave head starting time, including: the wave head starting time of the non-fault phase induced traveling wave on both sides of the fault point is t C1 and t C2 , and the time difference between t C1 and t C2 is the time difference of the wave heads on both sides of the fault point.

[0020] Further, the traveling wave propagation speed is calculated based on the line distance between the adjacent two traveling wave acquisition devices and the traveling wave head time difference collected by the adjacent two traveling wave acquisition devices, including:

[0021] The traveling wave head time difference collected by the adjacent two traveling wave acquisition devices is Δt1-Δt4, and the line distance between the adjacent two traveling wave acquisition devices is ΔL1-ΔL4, and the traveling wave propagation speed is calculated as follows:

[0022]

[0023] Where v i is the traveling wave speed calculated according to the traveling wave propagation distance and time on the i-th section of line, and the calculated traveling wave speed v iTake the average as the traveling wave propagation speed v. Further, the determination of the fault point position based on the traveling wave propagation speed, the time difference of the traveling wave wave fronts on both sides of the fault point and the distance between the traveling wave collection devices on both sides of the fault point comprises: determining the fault interval according to the induced traveling wave waveform characteristics, combining the distance between the traveling wave collection devices on both sides of the fault point, the wave head time recorded by the traveling wave collection device and the traveling wave propagation speed, calculating the distance of the fault point position from the traveling wave collection device on the nearest side, and the calculation formula is as follows:

[0024]

[0025]

[0026] Wherein, M and N are the fault point two traveling wave collection device numbers, L M and L N are the distances of the fault point position from M and N, L is the distance between the traveling wave collection devices numbered M and N, v is the traveling wave propagation speed, t M and t N are the wave head time recorded by the traveling wave collection devices numbered M and N respectively.

[0027] Compared with the traditional method, the power transmission line fault position can be accurately calculated in the case of damage of the fault phase traveling wave collection device and missing of the fault traveling wave, the fault troubleshooting time is reduced, and the line operation and maintenance level and power supply reliability are improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic diagram of the overhead power transmission line fault positioning method based on double-ended induced traveling wave of the application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0030] Please refer to Figure 1 , the application provides a kind of based on double-ended induced traveling wave of overhead power transmission line fault positioning method, comprising the following steps:

[0031] Step one, extract the induced traveling wave of non-fault phase of power transmission line

[0032] The waveforms of the three phases (the fault phase and the non-fault phase) at the fault moment are time-synchronized, and then the waveforms recorded by the traveling wave acquisition device are divided into the fault phase traveling wave and the non-fault phase induced traveling wave based on the fault moment, the power frequency current and the traveling wave waveform. Figure 1 As shown in the upper right subgraph, the amplitude of the fault phase traveling wave is obviously higher than that of the non-fault phase induced traveling wave.

[0033] Step two, identifying the wave head of the non-fault phase induced traveling wave and determining the starting moment of the wave head

[0034] The wave head of the non-fault phase induced traveling wave is identified by using the wavelet transform and threshold judgment method. When the value of the wave head is greater than 10 times the noise level, it is considered that the traveling wave has a sudden change, and at this time, the starting moment of the wave head is determined. The calculation formula of the noise level is as follows:

[0035]

[0036] Wherein, n is the n sampling points recorded by the traveling wave acquisition device before the fault moment, generally n = 500 or 1000, i n is the sampling value of the traveling wave.

[0037] The wave head criterion is as follows:

[0038] i0>10*N L

[0039] Where i0 is the sampling value of the traveling wave at t0, and if the criterion condition is met, t0 is considered as the starting moment of the wave head.

[0040] Step three, calculating the time difference of the wave heads on both sides of the fault point based on the starting moment of the wave head

[0041] According to step two, the starting moment of the wave head of the non-fault phase induced traveling wave can be determined, as shown in Figure 1 Taking phase C as an example, the starting moments of the C phase induced traveling wave heads on both sides of the fault point are t C1 and t C2 , and the time difference between the two is the time difference of the wave heads on both sides of the fault point Δt C .

[0042] Step four, calculating the traveling wave propagation speed based on the line distance between the adjacent two traveling wave acquisition devices and the time difference of the wave heads recorded by the adjacent two traveling wave acquisition devices, and determining the position of the fault point based on the traveling wave propagation speed, the time difference of the wave heads on both sides of the fault point and the distance between the traveling wave acquisition devices on both sides of the fault point.

[0043] The traveling wave speed is calculated according to the recorded traveling wave waveform of the non-fault phase induced traveling wave along the transmission line, as shown in Figure 1As shown in the lower right subgraph, the time difference of wave head recorded by two adjacent traveling wave acquisition devices is Δt1-Δt4; the line distance between two adjacent traveling wave acquisition devices is ΔL1-ΔL4, and the traveling wave propagation speed is calculated as follows:

[0044]

[0045] where v i is the traveling wave propagation speed calculated according to the traveling wave propagation distance and time on the ith line, and then the calculated traveling wave propagation speed v i is taken as the average value of the traveling wave propagation speed v for subsequent calculation. The traveling wave propagation speed is generally 290 m / μs-300 m / μs.

[0046] Finally, the fault interval is determined according to the induced traveling wave waveform characteristics, the distance between the fault point and two adjacent traveling wave acquisition devices, the wave head time recorded by the traveling wave acquisition device, and the traveling wave propagation speed, the distance of the fault point from the traveling wave acquisition device on the nearest side is calculated, and the calculation formula is as follows:

[0047]

[0048]

[0049] where M and N are the numbers of the traveling wave acquisition devices on both sides of the fault point, L M and L N are the distances of the fault point from M and N, L is the distance between the traveling wave acquisition devices numbered M and N, v is the traveling wave propagation speed, t M and t N are the wave head times recorded by the traveling wave acquisition devices numbered M and N, respectively.

[0050] Next, the method proposed in the present application is used to calculate the fault point position according to the induced traveling wave waveform of the non-fault phase (C phase) in Figure 1 . First, the time difference Δt C of the C phase induced traveling wave wave head on both sides of the fault point is equal to 82.4 μs, and the distance L between the traveling wave acquisition devices on both sides of the fault point is 42434 m. Then, the traveling wave propagation speed is calculated according to the traveling wave propagation process, where Δt1-Δt4 are 140.5 μs, 99.4 μs, 90.7 μs, and 86.1 μs, respectively; ΔL1-ΔL4 are 41645 m, 29505 m, 27095 m, and 25568 m, respectively; the calculated traveling wave propagation speed is 296.41 m / μs, 296.83 m / μs, 298.73 m / μs, and 296.96 m / μs, respectively; and the average value is 297.23 m / μs.

[0051] The distance between the fault point and the small-size side and the large-size side traveling wave acquisition device is respectively 33462.88 m and 8971.12 m.

[0052]

[0053]

[0054] Compared with the traditional method, the application has the advantages of high precision and high reliability, the traveling wave acquisition device is generally installed on the three-phase conductor of the tower, and the induced traveling wave of the non-fault phase is recorded when the fault traveling wave propagates to the tower position; when the fault location is based on the induced traveling wave, the traveling wave data of the non-fault phase is equivalent to the mutual standby redundancy relationship; in this way, the loss of original data during fault location can be avoided to the greatest extent, and the reliability of fault location is ensured; at the same time, the calculation accuracy can be verified by respectively calculating the fault position based on the induced traveling wave of the non-fault phase, and the precision of fault location is greatly improved.

[0055] The above is only a specific embodiment of the application, but the protection scope of the application is not limited to this, any change or replacement within the technical range disclosed by the application can be easily thought by any person skilled in the art, and should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A method for locating faults in overhead transmission lines based on double-ended inductive traveling waves, characterized in that: The steps include: Extracting the induced traveling waves of the non-fault phase of the transmission line; Identify the wave head of the traveling wave induced by the non-fault phase and determine the starting time of the wave head; Calculate the time difference of the traveling wave fronts on both sides of the fault point based on the starting time of the wave front; Calculate the traveling wave propagation velocity based on the line distance between two adjacent traveling wave acquisition devices and the time difference of the traveling wave fronts collected by the two adjacent traveling wave acquisition devices, and determine the fault point location based on the traveling wave propagation velocity, the time difference of the traveling wave fronts on both sides of the fault point, and the distance between the traveling wave acquisition devices on both sides of the fault point; The method of discriminating the wave head of the non-fault phase induced traveling wave and determining the wave head starting time includes: using a wavelet transform and a threshold judgment method to identify the wave head of the non-fault phase induced traveling wave, and when the wave head traveling wave value is greater than 10 times the noise level, it is considered that the traveling wave has a sudden change, and the sudden change time is used as the starting time of the traveling wave head; The noise level is calculated as follows: ； Where n is the number of sampling points recorded by the traveling wave acquisition device before the fault occurs, and n=500 or 1000, i n is the traveling wave sampling value; The wave head criterion is as follows: ； Where i0 is the sampling value of the traveling wave at time t0. If the judgment condition is met, t0 is considered to be the starting time of the traveling wave head; The method of calculating the time difference of the traveling wave fronts on both sides of the fault point based on the wave front starting time includes: the starting time of the traveling wave fronts induced by the non-fault phases on both sides of the fault point is t C1 and t C2 , t C1 and t C2 The time difference between them is the time difference of the traveling wave heads on both sides of the fault point.

2. The method for locating faults in overhead power transmission lines based on double-ended inductive traveling waves according to claim 1, wherein: The extracting of the induced traveling wave of the non-fault phase of the transmission line comprises: The traveling wave waveforms of the fault phase and non-fault phase at the fault moment are time-synchronized, and the traveling wave waveforms recorded by the traveling wave acquisition device are divided into two categories: fault phase traveling wave and non-fault phase induced traveling wave based on the fault moment, power frequency current and traveling wave waveform.

3. The method for locating faults in overhead power transmission lines based on double-ended inductive traveling waves according to claim 1, wherein: The method of calculating the traveling wave propagation velocity based on the line distance between two adjacent traveling wave collection devices and the time difference between the traveling waves collected by the two adjacent traveling wave collection devices includes: The time difference between the traveling wave heads collected by two adjacent traveling wave collection devices is , the line distance between two adjacent traveling wave acquisition devices is , the traveling wave propagation velocity is calculated as follows: ； where v i The calculated traveling wave velocity v is calculated based on the traveling wave propagation distance and time on the i-th line. i Take the average value as the traveling wave propagation velocity v.

4. The method for locating faults in overhead power transmission lines based on double-ended inductive traveling waves according to claim 3, wherein: The method of determining the fault point location based on the traveling wave propagation velocity, the time difference of the traveling wave crests on both sides of the fault point, and the distance between the traveling wave collection devices on both sides of the fault point includes: determining the fault interval based on the waveform characteristics of the induced traveling wave, and calculating the distance between the fault point location and the nearest traveling wave collection devices on both sides based on the distance between the traveling wave collection devices on both sides of the fault point, the crest time recorded by the traveling wave collection devices, and the traveling wave propagation velocity. The calculation formula is as follows: ； ； Among them, M and N are the numbers of the traveling wave acquisition devices on both sides of the fault point, L M and L N is the distance between the fault point and M and N, L is the distance between the traveling wave acquisition devices numbered M and N, v is the traveling wave propagation speed, t M and t N These are the wave front moments recorded by the traveling wave acquisition devices numbered M and N respectively.

Images