CN112363017A - Line fault positioning method based on wavelet transformation - Google Patents
Line fault positioning method based on wavelet transformation Download PDFInfo
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- G—PHYSICS
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- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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Abstract
The invention discloses a line fault positioning method based on wavelet transformation, and relates to a line fault positioning method based on wavelet transformation. The method comprises the following steps: data acquisition, wavelet analysis processing, arrival time detection and transmission line fault analysis positioning, wherein the data acquisition adopts a synchronous sampling technology of a satellite synchronous clock; after wavelet transformation is adopted to process data, arrival time detection of fault initial traveling waves is carried out; the traveling wave velocity is an uncertain factor in fault location by a double-end traveling wave method, and a fault location algorithm for eliminating the wave velocity is provided to ensure and improve the precision of fault location by the double-end traveling wave method. And the method is not influenced by fault types and partial node recording error time, and is suitable for detecting and positioning faults of the multi-end power transmission line.
Description
Technical Field
The invention belongs to the technical field of fault location of high-voltage transmission lines, and particularly belongs to a line fault location method based on wavelet transformation.
Background
The traditional power line fault positioning method based on the power frequency electric quantity is influenced by a plurality of factors such as transformer transformation errors, line distribution capacitance, fault signal non-periodic components and the like, has large positioning errors, and is not suitable for high-altitude overhead line-cable mixed lines. The transient traveling wave method calculates the distance from a fault point to one end of a line by measuring the propagation time of the transient traveling wave on the fault line, and has high positioning accuracy for common overhead lines and cables, wherein the positioning error of the overhead lines can reach within 300 meters, and the positioning error of the cables can reach within l meters. The travelling wave distance measurement method has the advantages of simple principle and no influence by the type of fault and the asymmetric reason of the line, and is a commonly applied method for measuring the distance of the fault of the line. However, for fault location of a high-voltage overhead line-cable hybrid line, not only the influence of the conductivity and insulation condition of the actual line conductor to be measured and the external environment of the fault line to be measured on the wave velocity of the traveling wave need to be considered, but also the waveform distortion of the traveling wave caused by the complex frequency contained in the traveling wave needs to be considered, so that an accurate measurement time reference point is difficult to obtain, and the reflection process of the traveling wave is more complicated due to the existence of the connection point of the overhead line and the cable, and in addition, the wave velocities of the traveling wave signals before and after the connection point of the overhead line and the cable are also different. These reasons have led to the fact that the various single-ended or double-ended traveling wave fault location principles and algorithms that have been proposed cannot be directly applied to fault location of hybrid overhead line-cable lines.
A high-voltage overhead line-cable hybrid line fault positioning technology based on distributed detection utilizes a distributed traveling wave detection ball platform to collect a transient current signal of a key node position of a hybrid line, combines the length relation of the overhead line and the cable of the hybrid line, designs a targeted fault positioning algorithm, can accurately judge whether a fault occurs on the overhead line or the cable, and accurately positions the fault on the basis, so that maintenance personnel can quickly and accurately find the fault position and repair the time for winning the fault, the economic loss caused by power failure is reduced, the bad social influence can be weakened, and the high-voltage overhead line-cable hybrid line fault positioning technology has a very important significance in ensuring the safety, stability and economic operation of the whole power system.
Disclosure of Invention
The invention aims to provide a line fault positioning method based on wavelet transformation aiming at the problems of the existing online power transmission line fault monitoring system.
The method for positioning the line fault based on the wavelet transform is characterized by comprising the following steps of: the method comprises the following steps of data acquisition, wavelet analysis and processing, arrival time detection and transmission line fault analysis and positioning, and specifically comprises the following steps:
1. the data acquisition and data synchronous sampling technology adopts a GPS satellite synchronous clock, and because the transient traveling wave signal generated when the power transmission line is in fault has the characteristics of short duration and corresponding frequency bandwidth, a high-speed data acquisition system is adopted in order to complete the faithful recording of the transient traveling wave signal to ensure higher positioning accuracy. When the transmission line is relatively long or the transmission line has a high-resistance ground fault, the fault traveling wave signal is relatively weak and is easily interfered by a noise signal, so that the fault traveling wave signal cannot be detected. Weak signal detection techniques are studied to accurately and timely detect faulty traveling wave signals. In addition, after high-sensitivity data acquisition is carried out on the fault traveling wave signal, a fault signal is extracted and analyzed;
2. the method comprises the following steps that wavelet analysis processing is carried out, wherein detection terminals arranged at two ends of a line need to detect the first arriving fault traveling wave surge, the first wave head of a fault traveling wave is captured without considering the refraction and reflection of the traveling wave, and the fault traveling wave head is accurately identified;
3. the method comprises the steps that the arrival time detection is carried out, a traveling wave data acquisition system carries out time marking on acquired fault signal data, time synchronization of all detection terminals is carried out, time synchronization errors directly influence measurement results of absolute time differences of detection terminals on two sides of an initial traveling wave arrival line, the precision of fault positioning is influenced, wavelet transformation just has signal singularity detection properties and zooming properties and is very sensitive to singularity and mutation parts of signals, and therefore wavelet analysis is used for analyzing and detecting positions of signal mutation points and time of the mutation points;
4. the transmission line fault analysis and location method is characterized in that detection terminals arranged at two ends of a line need to detect the first fault traveling wave surge, the refraction and reflection of the traveling wave are not considered, and the fault traveling wave head must be accurately identified as long as the first wave head of the fault traveling wave is captured. The method comprises the steps that a sensor is required to collect fault traveling wave signals, fault traveling wave heads are extracted through a reliable and simplified algorithm, meanwhile, the module is located on a detection terminal, the algorithm required to be adopted is small in calculation amount and good in self-adaption performance, and the time difference of the fault initial traveling waves reaching buses at two ends of a line is obtained by utilizing a double-end principle, so that the fault interval is judged. Wavelet transformation is used for signal processing, the traditional travelling wave ranging process is analyzed on the basis, and ranging research is respectively carried out on the conditions without interference and the conditions with interference.
5. The method for positioning the fault of the double-end transmission line can realize fault positioning only by detecting the time when the wave head of the current traveling wave reaches each measuring point, and has no relation with the wave speed of the current traveling wave, and the fault positioning flow of the double-end transmission line is as follows:
(1) collecting fault current traveling wave signals;
(2) performing phase-mode conversion;
(3) detecting an initial wave head arrival time based on wavelet analysis;
(4) judging and diagnosing a fault area;
(5) carrying out fault diagnosis;
(6) and outputting the measurement result.
M, N are the detection points of the two side power supply terminals respectively, and MN distance is L. P is a detection point between two ends of M, N, and distances from the two ends of M, N are L respectively1、L2. The time when the fault current traveling wave head reaches M, N, P ends for the first time is tM、tN、tPThe distance between the fault point and the measurement point P is set to x. Then the P, N area detection formula is:
then the M, N area detection formula is:
drawings
FIG. 1 is a schematic diagram of a line fault location process based on wavelet transformation;
FIG. 2 is a schematic diagram of an access network scheme of an online transmission line detection system;
fig. 3 is a flow chart of fault location of a double-ended power transmission line.
Detailed Description
As shown in fig. 1, the specific process is as follows:
(1) the data acquisition and data synchronous sampling technology adopts a GPS satellite synchronous clock, and because the transient traveling wave signal generated when the power transmission line fails has the characteristics of short duration and corresponding frequency bandwidth, a high-speed data acquisition system is adopted in order to complete the faithful recording of the transient traveling wave signal so as to ensure higher positioning accuracy. When the transmission line is relatively long or the transmission line has a high-resistance ground fault, the fault traveling wave signal is relatively weak and is easily interfered by a noise signal, so that the fault traveling wave signal cannot be detected. Weak signal detection technology is studied to accurately detect fault traveling wave signals in time. In addition, after high-sensitivity data acquisition is carried out on the fault traveling wave signal, the fault signal is extracted and analyzed.
(2) And (5) wavelet analysis processing. The invention adds the same white noise into the same given signal, respectively uses a wavelet modulus maximum value method, a wavelet decomposition and reconstruction method and a wavelet threshold value method to carry out denoising treatment, and analyzes the corresponding treatment effect.
(3) The method comprises the steps of arrival time detection, time marking of collected fault signal data by a traveling wave data collection system, time synchronization of all detection terminals, direct influence of time synchronization errors on measurement results of absolute time difference of the initial traveling wave arriving at the detection terminals on two sides of a line, influence on accuracy of fault positioning, good signal singularity detection property and zooming property of wavelet transformation, and very sensitivity to singularity and mutation parts of signals.
(4) The transmission line fault analysis and location, the detection terminals installed at two ends of the line need to detect the first fault traveling wave surge, the refraction and reflection of the traveling wave are not considered, and the fault traveling wave head must be accurately identified as long as the first wave head of the fault traveling wave is captured. The method comprises the steps that a sensor is required to collect fault traveling wave signals, fault traveling wave heads are extracted through a reliable and simplified algorithm, meanwhile, the module is located on a detection terminal, the algorithm required to be adopted is small in calculation amount and good in self-adaption performance, and the time difference of the fault initial traveling waves reaching buses at two ends of a line is obtained by utilizing a double-end principle, so that the fault interval is judged. The wavelet transformation is used for signal processing, the traditional travelling wave ranging process is analyzed on the basis, and ranging research is respectively carried out on the conditions without interference and the conditions with interference.
As shown in fig. 2, the specific process is as follows:
(1) when the measurement is performed, the measurement is inaccurate due to the influence of the reflected wave. Therefore, in order to eliminate this effect, a wavelet transform method is used for transformation, and a characteristic traveling wave is reconstructed to eliminate the effect.
(2) After the influence of the reflected wave is removed, the interference signal is processed. The method is to perform wavelet transform under different standards, i.e. different wavelet bases, and observe the transformation situation of the modulus maximum in each situation. And selecting the most appropriate group of fundamental waves by analyzing the filtering effect of wavelet transformation under different scales on the interference signals.
(3) Reflected waves at some non-fault points also affect the fault ranging results. Therefore, these effects are also dealt with. The method is to set up a threshold value artificially, and send a reference value corresponding to the threshold value, and the threshold value is set up by setting one thousandth of the maximum value of wavelet variation to the value under a certain precision.
(4) And determining a detection scale. The detection scale is determined based on the scale at which the mode maximum of the initial current is measured.
(5) After the detection scale is determined, the fault distance is derived by wavelet transform maximum analysis under this condition. The method of determining the fault distance is determined by the corresponding time of the two modes. The two modes are respectively the maximum values of opposite ends of the fault line.
As shown in fig. 3, the fault location method for the even-number lines can realize fault location only by detecting the time when the current traveling wave head reaches each measurement point, and is independent of the current traveling wave speed. The fault locating process of the double-end transmission line comprises the following steps:
(1) collecting fault current traveling wave signals;
(2) performing phase-mode conversion;
(3) detecting an initial wave head arrival time based on wavelet analysis;
(4) judging and diagnosing a fault area;
(5) carrying out fault diagnosis;
(6) and outputting the measurement result.
Claims (6)
1. A line fault positioning method based on wavelet transformation is characterized by comprising the following steps:
(1) collecting data;
(2) wavelet analysis processing;
(3) detecting the arrival time;
(4) and analyzing and positioning the transmission line faults.
2. The line fault location method based on wavelet transformation as claimed in claim 1, wherein: the data acquisition adopts a GPS satellite synchronous clock, and because the transient traveling wave signal generated when the power transmission line has a fault has the characteristics of short duration and wide corresponding frequency band, a high-speed data acquisition system is adopted in order to complete the faithful recording of the transient traveling wave signal so as to ensure higher positioning accuracy. When the transmission line is long or the transmission line has a high-resistance grounding fault, the fault traveling wave signal is weak and is easily interfered by a noise signal, so that the fault traveling wave signal cannot be detected, a weak signal detection technology is researched to accurately and timely detect the fault traveling wave signal, and in addition, the fault signal is extracted and analyzed after high-sensitivity data acquisition is carried out on the fault traveling wave signal.
3. The line fault location method based on wavelet transformation as claimed in claim 1, wherein: the wavelet analysis processing is to detect the first arriving traveling wave surge of the fault traveling wave by the detection terminals installed at two ends of the line, capture the first wave head of the fault traveling wave, accurately identify the wave head of the fault traveling wave, add the same white noise into the same given signal, perform denoising processing by respectively using a wavelet modulus maximum value method, a wavelet decomposition and reconstruction method and a wavelet threshold value method, and analyze the corresponding processing effect.
4. The line fault location method based on wavelet transformation as claimed in claim 1, wherein: the method comprises the steps that the arrival time detection is carried out, a traveling wave data acquisition system carries out time marking on acquired fault signal data, time synchronization of all detection terminals is carried out, time synchronization errors directly influence measurement results of absolute time differences of detection terminals on two sides of an initial traveling wave arrival line, the precision of fault positioning is influenced, wavelet transformation just has signal singularity detection properties and zooming properties and is very sensitive to singularity and mutation parts of signals, and therefore wavelet analysis is used for analyzing and detecting positions of signal mutation points and time of the mutation points.
5. The line fault location method based on wavelet transformation as claimed in claim 1, wherein: the transmission line fault analysis and positioning method is characterized in that a fault traveling wave signal is collected by a sensor, a fault traveling wave head is extracted by a reliable and simplified algorithm, meanwhile, the module is positioned on a detection terminal, so that the algorithm required to be adopted is small in calculation amount and good in self-adaptability, and the time difference of the fault initial traveling wave reaching buses at two ends of a line is obtained by utilizing a double-end principle, so that the fault section is judged; wavelet transformation is used for signal processing, the traditional travelling wave ranging process is analyzed on the basis, and ranging research is respectively carried out on the conditions without interference and the conditions with interference.
6. The line fault location method based on wavelet transformation as claimed in claim 1, wherein the fault location procedure is as follows:
(1) collecting fault current traveling wave signals;
(2) performing phase-mode conversion;
(3) detecting an initial wave head arrival time based on wavelet analysis;
(4) judging and diagnosing a fault area;
(5) carrying out fault diagnosis;
(6) and outputting the measurement result.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111736035A (en) * | 2020-06-10 | 2020-10-02 | 国网浙江诸暨市供电有限公司 | Troubleshooting method for single-core cable fault positioning |
| CN114034979A (en) * | 2021-11-12 | 2022-02-11 | 昆明理工大学 | Alternating current transmission line distance measuring method and system |
| CN116243108A (en) * | 2023-03-16 | 2023-06-09 | 国网江苏省电力有限公司南通市通州区供电分公司 | Distribution network fault point positioning method, system, equipment and medium |
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Cited By (3)
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| CN114034979A (en) * | 2021-11-12 | 2022-02-11 | 昆明理工大学 | Alternating current transmission line distance measuring method and system |
| CN116243108A (en) * | 2023-03-16 | 2023-06-09 | 国网江苏省电力有限公司南通市通州区供电分公司 | Distribution network fault point positioning method, system, equipment and medium |
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