Overhead transmission line fault positioning method based on double-end induction traveling waves

Abstract

The invention provides an overhead transmission line fault positioning method based on double-end induction traveling waves. The method comprises the following steps: extracting non-fault phase induction traveling waves of a transmission line; judging the wave head of the non-fault phase induction traveling wave and determining the starting moment of the wave head; calculating traveling wave head time difference on two sides of the fault point based on the wave head starting time; the traveling wave propagation speed is calculated based on the line distance between the two adjacent traveling wave acquisition devices and the traveling wave head time difference acquired by the two adjacent traveling wave acquisition devices, and the position of the fault point is determined based on the traveling wave propagation speed, the traveling wave head time difference on the two sides of the fault point and the distance between the traveling wave acquisition devices on the two sides of the fault point. Compared with a traditional method, the method can accurately calculate the fault position of the power transmission line under the conditions that a fault phase traveling wave acquisition device is damaged and fault traveling waves are missed in acquisition, reduces the troubleshooting time, and improves the operation and maintenance level of the line and the power supply reliability.

Description

Technical Field

[0001] The invention relates to the field of power transmission line fault detection, and in particular to an overhead power transmission line fault location method based on double-terminal induction traveling waves. Background Art

[0002] Overhead transmission lines often suffer from grounding faults due to lightning strikes and other reasons. Timely determination of the fault location is of great significance for emergency repair and reliable power supply. Traveling waves have the advantages of large fault mutation amplitude and high sensitivity, which are easy to measure. Currently, there are two types of fault traveling wave positioning methods: two-end and single-end. They mainly focus on the traveling wave positioning technology of branch lines, the traveling wave characteristics of overhead-cable hybrid lines, and the traveling wave waveform acquisition and processing algorithms. The two-end fault traveling wave method has become the preferred method for locating fault points. This method mainly calculates the fault position based on the waveforms recorded by the fault phase traveling wave acquisition devices on both sides of the fault point. However, these are all based on the fact that the traveling wave acquisition device can well record the traveling wave waveform of the fault phase at the moment of the fault. In actual operation, the transmission line traveling wave acquisition device is often unable to collect the traveling wave waveform of the fault phase when a fault occurs due to offline, failure, etc. At this time, the traveling wave waveform of the fault phase cannot be collected, resulting in the inability to locate the fault point, and the fault troubleshooting takes a long time. Summary of the invention

[0003] The present invention proposes a method for fault location based on the induced traveling wave collected from the non-fault phase of the same tower, which solves the problem that the fault location cannot be performed because the traveling wave of the fault phase is not collected.

[0004] A method for locating faults in overhead power transmission lines based on double-terminal induction traveling waves comprises the following steps:

[0005] Extract the induced traveling waves of the non-fault phase of the transmission line;

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

[0007] Calculate the time difference of the traveling wave fronts on both sides of the fault point based on the wave front starting time;

[0008] The traveling wave propagation velocity is calculated based on the line distance between two adjacent traveling wave collection devices and the time difference of the traveling wave heads collected by the two adjacent traveling wave collection devices, and the fault point location is determined based on the traveling wave propagation velocity, the time difference of the traveling wave heads on both sides of the fault point and the distance between the traveling wave collection devices on both sides of the fault point.

[0009] Furthermore, the extraction of the induced traveling wave of the non-fault phase of the transmission line includes:

[0010] The traveling wave waveforms of the fault phase and the non-fault phase at the time of the fault are synchronized.

[0011] The traveling wave waveform recorded by the traveling wave acquisition device is divided into two categories: fault phase traveling wave and non-fault phase induced traveling wave.

[0012] Furthermore, the method of distinguishing the wave head of the traveling wave induced by the non-fault phase and determining the starting time of the wave head includes: using wavelet transform and threshold judgment method to identify the wave head of the traveling wave induced by the non-fault phase, when the wave head traveling wave value is greater than 10 times the noise level, it is considered that the traveling wave has a mutation, and the mutation time is used as the starting time of the traveling wave head.

[0013] Furthermore, the calculation formula of the noise level is as follows:

[0014]

[0015] Where n is the number of sampling points recorded by the traveling wave acquisition device before the fault occurs, and n=500 or 1000. n is the traveling wave sampling value;

[0016] The wave head criterion is as follows:

[0017] i 0 >10*N L

[0018] where i 0 t 0 The sampling value of the traveling wave at time t is considered to be 0 is the starting time of the traveling wave head.

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

[0020] Furthermore, the method of calculating the traveling wave propagation speed based on the line distance between two adjacent traveling wave collection devices and the time difference of the traveling wave heads collected by the two adjacent traveling wave collection devices includes:

[0021] The time difference between the traveling wave heads collected by two adjacent traveling wave collection devices is Δt 1 ~Δt 4 , the line distance between two adjacent traveling wave collection devices is ΔL 1 ~ΔL 4 , the traveling wave propagation velocity is calculated as follows:

[0022]

[0023] where vi is the traveling wave velocity calculated based on the traveling wave propagation distance and time on the i-th line, and the calculated traveling wave velocity v i The average value is taken as the traveling wave propagation velocity v. Further, the determination of the fault point location based on the traveling wave propagation velocity, the time difference of the traveling wave head 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 according to the characteristics of the induced traveling wave waveform, and calculating the distance between the fault point location and the nearest traveling wave collection devices on both sides in combination with 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 velocity. The calculation formula is as follows:

[0024]

[0025]

[0026] 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 They are the wave front moments recorded by the traveling wave acquisition devices numbered M and N respectively.

[0027] Compared with traditional methods, the present invention can accurately calculate the fault location of the transmission line when the fault phase traveling wave collection device is damaged and the fault traveling wave is missed, thereby reducing the fault investigation time and improving the line operation and maintenance level and power supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overhead power transmission line fault location method based on double-terminal induction traveling waves of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 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.

[0030] See also Figure 1 The embodiment of the present invention provides a method for locating faults in overhead power transmission lines based on double-terminal inductive traveling waves, comprising the following steps:

[0031] Step 1: Extract the induced traveling wave of the non-fault phase of the transmission line

[0032] The traveling wave waveforms of the three phases (fault phase and non-fault phase) at the time of the fault are synchronized in time, and then 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 by combining the fault time, power frequency current, traveling wave waveform, etc. Figure 1 As shown in the upper right sub-figure in the middle, the amplitude of the traveling wave in the fault phase is significantly higher than the amplitude of the induced traveling wave in the non-fault phase.

[0033] Step 2: Identify the wave head of the non-fault phase induced traveling wave and determine the wave head starting time

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

[0035]

[0036] Where n is the number of sampling points recorded by the traveling wave acquisition device before the fault occurs, usually n=500 or 1000, i n is the traveling wave sampling value.

[0037] The wave head criterion is as follows:

[0038] i 0 >10*N L

[0039] where i 0 t 0 The sampling value of the traveling wave at time t is considered to be 0 is the starting time of the traveling wave head.

[0040] Step 3: Calculate the time difference of the traveling wave head on both sides of the fault point based on the wave head starting time

[0041] According to step 2, the starting time of the wave head of the non-fault phase induced traveling wave can be determined, such as Figure 1 As shown, taking phase C as an example, the starting time of the C-phase induced traveling wave head on both sides of the fault point is t C1 and t C2 The time difference between the two is the time difference of the traveling wave head on both sides of the fault point Δt C .

[0042] Step 4: Calculate the traveling wave propagation velocity based on the line distance between two adjacent traveling wave collection devices and the time difference of the traveling wave heads collected by the two adjacent traveling wave collection devices, and determine the fault point location based on the traveling wave propagation velocity, the time difference of the traveling wave heads on both sides of the fault point and the distance between the traveling wave collection devices on both sides of the fault point.

[0043] The traveling wave velocity is calculated based on the recorded waveform of the non-fault phase induced traveling wave propagating along the transmission line, as follows: Figure 1 As shown in the lower right sub-figure, the time difference of the wave head recorded by two adjacent traveling wave acquisition devices is Δt 1 ~Δt 4 ; Line distance ΔL between two adjacent traveling wave collection devices 1 ~ΔL 4 It can be seen that the propagation velocity of the traveling wave is calculated as follows:

[0044]

[0045] where v i is the traveling wave velocity calculated based on the traveling wave propagation distance and time on the i-th line, and then the calculated traveling wave velocity v i The average value is taken as the traveling wave propagation velocity v for subsequent calculations. The traveling wave propagation velocity is generally between 290m / μs and 300m / μs.

[0046] Finally, the fault interval is determined according to the characteristics of the induced traveling wave waveform. Combined with the distance between the traveling wave acquisition devices on both sides of the fault point, the wave head moment recorded by the traveling wave acquisition devices, and the traveling wave propagation speed, the distance between the fault point and the nearest traveling wave acquisition devices on both sides is calculated. The calculation formula is as follows:

[0047]

[0048]

[0049] 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 They are the wave front moments recorded by the traveling wave acquisition devices numbered M and N respectively.

[0050] The method proposed by the present invention is adopted below, according to Figure 1 The fault location is calculated by using the induced traveling wave waveform of the non-fault phase (phase C) in the fault point. First, the time difference Δt appears at the C phase induced traveling wave head on both sides of the fault point. C =82.4μs, and the distance L between the traveling wave acquisition devices on both sides of the fault point is 42434m. Then the traveling wave propagation speed is calculated according to the induced traveling wave propagation process, where Δt 1 ~Δt 4 They are 140.5μs, 99.4μs, 90.7μs, and 86.1μs respectively; ΔL 1 ~ΔL 4They are 41645m, 29505m, 27095m and 25568m respectively. The calculated traveling wave propagation velocity is 296.41m / μs, 296.83m / μs, 298.73m / μs and 296.96m / μs; the average value is 297.23m / μs.

[0051] The calculated distances from the fault point to the nearest traveling wave acquisition devices on the small and large sides are 33462.88m and 8971.12m respectively.

[0052]

[0053]

[0054] Compared with the traditional method, the present invention has the advantages of high precision and high reliability. The traveling wave acquisition device is generally installed on the three-phase conductors of the pole tower at the same time. When the fault traveling wave propagates to the pole tower position, the induced traveling wave in the non-fault phase will be recorded; when fault location is performed based on the induced traveling wave, the traveling wave data of the non-fault phase is equivalent to a backup redundant relationship with each other; in this way, the loss of original data during fault location can be avoided to the greatest extent, and the reliability of fault location can be ensured; at the same time, the fault location calculation based on the induced traveling waves of the non-fault phase can verify the calculation accuracy with each other, greatly improving the accuracy of fault location.

[0055] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for locating faults in overhead power transmission lines based on double-terminal inductive traveling waves, characterized in that: The steps include: Extract the induced traveling waves of the non-fault phase of the transmission line; Identify the wave head of the induced traveling wave in the non-fault phase and determine the wave head starting time; Calculate the time difference of the traveling wave fronts on both sides of the fault point based on the wave front starting time; The traveling wave propagation velocity is calculated based on the line distance between two adjacent traveling wave collection devices and the time difference of the traveling wave heads collected by the two adjacent traveling wave collection devices, and the fault point location is determined based on the traveling wave propagation velocity, the time difference of the traveling wave heads on both sides of the fault point and the distance between the traveling wave collection devices on both sides of the fault point.

2. The method for locating faults of overhead power transmission lines based on double-terminal induction traveling waves according to claim 1, characterized in that: The method of extracting the induced traveling wave of the non-fault phase of the transmission line comprises: The traveling wave waveforms of the fault phase and the 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-terminal induction traveling waves according to claim 1, characterized in that: The method of distinguishing the wave head of the non-fault phase induced traveling wave and determining the wave head starting time includes: using wavelet transform and threshold judgment method to identify the wave head of the non-fault phase induced traveling wave, 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.

4. The method for locating faults in overhead power transmission lines based on double-terminal induction traveling waves according to claim 3, characterized in that: 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. n is the traveling wave sampling value; The wave head criterion is as follows: i0>10*N L 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.

5. The method for locating faults in overhead power transmission lines based on double-terminal induction traveling waves according to claim 1, characterized in that: The method of calculating the time difference of the traveling wave head on both sides of the fault point based on the wave head starting time includes: the starting time of the traveling wave head induced by the non-fault phase 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.

6. The method for locating faults in overhead power transmission lines based on double-terminal inductive traveling waves according to claim 1, characterized in that: The method of calculating the traveling wave propagation speed based on the line distance between two adjacent traveling wave collection devices and the time difference of the traveling wave heads collected by the two adjacent traveling wave collection devices includes: The time difference of the traveling wave head collected by two adjacent traveling wave collection devices is Δt1~Δt4, the line distance between two adjacent traveling wave collection devices is ΔL1~ΔL4, and the traveling wave propagation speed is calculated as follows: where v i is the traveling wave velocity calculated based on the traveling wave propagation distance and time on the i-th line. The calculated traveling wave velocity v i Take the average value as the traveling wave propagation velocity v.

7. The method for locating faults in overhead power transmission lines based on double-terminal inductive traveling waves according to claim 6, characterized in that: The method of determining the position of the fault point based on the traveling wave propagation speed, the time difference of the traveling wave head 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 according to the waveform characteristics of the induced traveling wave, and calculating the distance between the fault point position and the nearest traveling wave collection devices on both sides in combination with 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 devices and the traveling wave propagation speed. 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 They are the wave front moments recorded by the traveling wave acquisition devices numbered M and N respectively.

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