CN114152837A - Wave head identification method and device under multi-scale wavelet transform - Google Patents

Wave head identification method and device under multi-scale wavelet transform Download PDF

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CN114152837A
CN114152837A CN202010943842.6A CN202010943842A CN114152837A CN 114152837 A CN114152837 A CN 114152837A CN 202010943842 A CN202010943842 A CN 202010943842A CN 114152837 A CN114152837 A CN 114152837A
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scale
wavelet transform
reference point
wave head
point
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CN114152837B (en
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黄涛
徐晓春
谢华
赵青春
陈玉林
谈浩
戴光武
陆金凤
王玉龙
李奔
张洪喜
徐海洋
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NR Electric Co Ltd
NR Engineering Co Ltd
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NR Engineering Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • 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
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F18/00—Pattern recognition
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F18/00—Pattern recognition
    • G06F18/20—Analysing
    • G06F18/21—Design or setup of recognition systems or techniques; Extraction of features in feature space; Blind source separation
    • G06F18/213—Feature extraction, e.g. by transforming the feature space; Summarisation; Mappings, e.g. subspace methods
    • G06F18/2131—Feature extraction, e.g. by transforming the feature space; Summarisation; Mappings, e.g. subspace methods based on a transform domain processing, e.g. wavelet transform
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2218/00—Aspects of pattern recognition specially adapted for signal processing
    • G06F2218/02—Preprocessing
    • G06F2218/04—Denoising
    • G06F2218/06—Denoising by applying a scale-space analysis, e.g. using wavelet analysis

Abstract

The invention discloses a wave head identification method under multi-scale wavelet transform, which comprises the following steps: acquiring fault traveling wave current data, performing multi-scale wavelet transformation on the traveling wave current data, and solving a modulus maximum value set under each scale; searching in a small scale longitudinally layer by taking the first mode maximum value of the maximum scale as a reference point, and sequentially obtaining the reference point of each scale in a wave head credible interval; each scale calculates a transverse credibility index from each datum point; and finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and locally correcting the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time. The invention also discloses a corresponding recognition device. The invention can obviously improve the wave head time extraction precision when the wave head change of the traveling wave is smooth.

Description

Wave head identification method and device under multi-scale wavelet transform
Technical Field
The invention relates to the field of relay protection of power systems, in particular to a wave head identification method and device under multi-scale wavelet transformation.
Background
The fault location and traveling wave protection technology can be realized by using transient traveling waves generated on the line when the transmission line fails. The identification of the traveling wave head is a key link for extracting the characteristics of the transient traveling wave, the wavelet transformation has good time-frequency localization capability, singular signals can be quickly and accurately detected, meanwhile, the multi-scale singularity detection of the signals can be realized through the change of scale factors, and the method is the most effective mathematical tool for analyzing the traveling wave.
In actual engineering, due to the influence of factors such as transition resistance, fault distance and the like, a traveling wave may be seriously attenuated, a traveling wave head detected by a measuring point is relatively gentle, singularity characteristics are not obvious, and the precision of traveling wave head identification is seriously influenced by considering the interference of noise. The multi-scale wavelet transform has obvious filtering characteristic difference under different scales, small scales are sensitive to high-frequency signals, traveling wave detection with obvious singularity characteristics is very accurate, but the influence of noise is large, the sensitive frequency of the wavelet transform is continuously reduced along with the increase of the scales, the influence of noise is also obviously reduced, the detection of the traveling wave signals with gentle wave heads is facilitated, and the identification precision of the large-scale downlink wave head at the moment is deficient.
Disclosure of Invention
The present application aims to provide a method and an apparatus for identifying a wave head under multi-scale wavelet transform, which comprehensively utilize multi-scale wavelet transform information to identify a traveling wave head, and implement adaptive identification of traveling wave heads with different change characteristics, thereby improving the accuracy of extracting a traveling wave arrival time, especially the accuracy of identifying a traveling wave head when the traveling wave head is relatively flat.
In order to achieve the above purpose, the solution of the present application is:
on one hand, the application provides a wave head identification method under multi-scale wavelet transform, which comprises the following steps:
step 1: acquiring fault traveling wave current data, performing multi-scale wavelet transformation on the traveling wave current data, and solving a modulus maximum value set under each scale;
step 2: searching in a small scale longitudinally layer by taking the first mode maximum value of the maximum scale as a reference point, and sequentially obtaining the reference point of each scale in a wave head credible interval;
and step 3: each scale calculates a transverse credibility index from each datum point;
and 4, step 4: and finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and locally correcting the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time.
Preferably, in the step 1, the multi-scale wavelet transform method is n (n ≧ 3) scale dyadic wavelet transform.
Preferably, in step 1, the modulus maximum value set at each scale is obtained by the following formula:
Figure BDA0002671507730000021
wherein k is the scale of wavelet transform, and k is 1, 2, …, n; n is the maximum scale of wavelet transform; i represents a wavelet transformThe number of results; m isk,i-1、mk,i、mk,i+1Absolute values of wavelet transformation results of ith-1, ith and i +1 points of the kth scale respectively;
Figure BDA0002671507730000022
is the maximum value of the absolute value of the k-th scale wavelet transform result,
Figure BDA0002671507730000023
n is the total number of the traveling wave current data; l is coefficient and has a value range of [0.2, 0.5 ]]。
Preferably, in step 2, the wave head confidence interval in each scale is:
Figure BDA0002671507730000024
in the formula, n is the maximum scale of wavelet transformation; i isnA set of modulus maxima at the nth scale; k is the scale of wavelet transformation;
Figure BDA0002671507730000025
is a reference point at the k +1 th scale; ckAnd the wave head confidence interval at the k-th scale.
Preferably, in step 2, the method for calculating the reference points of each scale is as follows:
Figure BDA0002671507730000026
in the formula, k is the scale of wavelet transformation; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head; n is the maximum scale of wavelet transform; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1); ckIs a wave head credible interval under the k-th scale;
Figure BDA0002671507730000027
is a reference point at the k-th scale; min (J)k) Is a set JkMinimum of all elements in (c).
Preferably, in step 3, the lateral reliability index in each scale is the number of elements in the modulus maximum value set in the scale that are smaller than the reference point in the scale, and the calculation formula is as follows:
Figure BDA0002671507730000028
in the formula, k is the scale of wavelet transformation; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1);
Figure BDA0002671507730000031
is a reference point at the k-th scale; n iskAnd the k-th scale is a transverse reliability index.
Preferably, in the step 4, the confidence point is integrated with the smallest scale kminThe judging method comprises the following steps:
Figure BDA0002671507730000032
in the formula, k is the scale of wavelet transformation; n iskThe k-th scale is a transverse reliability index; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head;
Figure BDA0002671507730000033
indicating an empty set.
Preferably, in the step 4, the step of locally correcting the reference point includes: at the k-thminScale wavelet transform results
Figure BDA0002671507730000034
From the second place to
Figure BDA0002671507730000035
The point starts searching forward until finding less than
Figure BDA0002671507730000036
The first point of (2), the latter point of the point is taken as the reference point after the local correction; wherein k isminIs the minimum scale of the reference point for comprehensive credibility, N is the total number of the traveling wave current data,
Figure BDA0002671507730000037
is the k-thminThe ith point of the scale wavelet transform result,
Figure BDA0002671507730000038
is the k-thminA reference point on a scale.
On the other hand, the application provides a wave head identification device under multi-scale wavelet transform, which comprises a modulus maximum value set calculation unit, a datum point calculation unit, a transverse reliability index calculation unit and a correction identification unit which are sequentially connected; wherein:
the modulus maximum value set calculation unit: the system is used for acquiring fault traveling wave current data, performing multi-scale wavelet transformation on the traveling wave current data and solving a modulus maximum value set under each scale;
the reference point calculating unit: the device is used for searching in layers longitudinally in a small scale by taking the first mode maximum value of the maximum scale as a reference point, and sequentially solving the reference point of each scale in a wave head credible interval;
the lateral reliability index calculation unit: the device is used for solving the transverse credibility index of each reference point according to each scale;
the correction recognition unit: and the method is used for finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and performing local correction on the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time.
Preferably, in the above apparatus, in the module maximum value set calculating unit, the multi-scale wavelet transform method is n (n ≧ 3) scale dyadic wavelet transform.
Preferably, in the apparatus, in the modulus maximum value set calculation unit, a modulus maximum value set at each scale is obtained by the following formula:
Figure BDA0002671507730000041
wherein k is the scale of wavelet transform, and k is 1, 2, …, n; n is the maximum scale of wavelet transform; i represents the serial number of the wavelet transformation result; m isk,i-1、mk,i、mk,i+1Absolute values of wavelet transformation results of ith-1, ith and i +1 points of the kth scale respectively;
Figure BDA0002671507730000042
is the maximum value of the absolute value of the k-th scale wavelet transform result,
Figure BDA0002671507730000049
n is the total number of the traveling wave current data; l is coefficient and has a value range of [0.2, 0.5 ]]。
Preferably, in the above apparatus, in the reference point calculation unit, the wave head confidence interval at each scale is:
Figure BDA0002671507730000043
in the formula, n is the maximum scale of wavelet transformation; i isnA set of modulus maxima at the nth scale; k is the scale of wavelet transformation;
Figure BDA0002671507730000044
is a reference point at the k +1 th scale; ckAnd the wave head confidence interval at the k-th scale.
Preferably, in the above apparatus, the reference point calculating means calculates the reference point for each scale by:
Figure BDA0002671507730000045
in the formula, k is the scale of wavelet transformation; j. the design is a squarekIs the modulus maximum value in the credible interval of the kth scale wave headGathering; n is the maximum scale of wavelet transform; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1); ckIs a wave head credible interval under the k-th scale;
Figure BDA0002671507730000046
is a reference point at the k-th scale; min (J)k) Is a set JkMinimum of all elements in (c).
Preferably, in the above apparatus, in the horizontal reliability index calculation unit, the horizontal reliability index at each scale is the number of elements smaller than the reference point at the scale in the modulo maximum value set at the scale, and the calculation formula is as follows:
Figure BDA0002671507730000047
in the formula, k is the scale of wavelet transformation; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1);
Figure BDA0002671507730000048
is a reference point at the k-th scale; n iskAnd the k-th scale is a transverse reliability index.
Preferably, in the above apparatus, the correction recognition means may recognize a minimum scale k in which the reference points are integrated with confidenceminThe judging method comprises the following steps:
Figure BDA0002671507730000051
in the formula, k is the scale of wavelet transformation; n iskThe k-th scale is a transverse reliability index; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head;
Figure BDA0002671507730000052
indicating an empty set.
Preferably, in the above apparatus, the correction is performedThe step of locally correcting the reference point in the recognition unit is as follows: at the k-thminScale wavelet transform results
Figure BDA0002671507730000053
From the second place to
Figure BDA0002671507730000054
The point starts searching forward until finding less than
Figure BDA0002671507730000055
The first point of (2), the latter point of the point is taken as the reference point after the local correction; wherein k isminIs the minimum scale of the reference point for comprehensive credibility, N is the total number of the traveling wave current data,
Figure BDA0002671507730000056
is the k-thminThe ith point of the scale wavelet transform result,
Figure BDA0002671507730000057
is the k-thminA reference point on a scale.
The beneficial effect of this application is:
after the scheme is adopted, on the basis of acquiring traveling wave sampling data, the method and the device position the reference point of the traveling wave head to the minimum comprehensive credible scale by performing longitudinal credible interval search and transverse credibility judgment on a multi-scale wavelet transform result, ensure the optimization of the wave head identification precision from the small wave transform scale, and then solve the problem that the identification of the wave head time possibly lags when the minimum comprehensive credible scale is still larger by performing local correction on the wave head reference point, thereby effectively improving the traveling wave head identification precision when the wave head changes smoothly.
Drawings
Fig. 1 is a flowchart of an embodiment of a method for identifying a wave head under multi-scale wavelet transform according to the present application.
Fig. 2 is a first specific embodiment of a method for identifying a wave head under multi-scale wavelet transform according to the present application.
Fig. 3 is a second specific embodiment of a method for identifying a wave head under multi-scale wavelet transform according to the present application.
Fig. 4 is an embodiment of a wave head recognition device under multi-scale wavelet transform according to the present application.
Detailed Description
The following detailed description of the present application will be provided in conjunction with the accompanying drawings and specific examples to enable those skilled in the art to better understand the present application and to practice the present application, but the examples are not intended to limit the present application.
As shown in fig. 1, an embodiment of a method for identifying a wave head under multi-scale wavelet transform includes the following steps:
step 1: acquiring fault traveling wave current data, performing multi-scale wavelet transformation on the traveling wave current data, and solving a modulus maximum value set under each scale;
step 2: searching in a small scale longitudinally layer by taking the first mode maximum value of the maximum scale as a reference point, and sequentially obtaining the reference point of each scale in a wave head credible interval;
and step 3: each scale calculates a transverse credibility index from each datum point;
and 4, step 4: and finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and locally correcting the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time.
In a preferred embodiment, in step 1, the multi-scale wavelet transform method is an n (n ≧ 3) scale dyadic wavelet transform.
In a preferred embodiment, in step 1, the modulus maximum value set at each scale is obtained by the following formula:
Figure BDA0002671507730000061
wherein k is the scale of wavelet transform, and k is 1, 2, …, n; n is the maximum scale of wavelet transform; i represents the serial number of the wavelet transformation result; m isk,i-1、mk,i、mk,i+1Absolute values of wavelet transformation results of ith-1, ith and i +1 points of the kth scale respectively;
Figure BDA0002671507730000062
is the maximum value of the absolute value of the k-th scale wavelet transform result,
Figure BDA0002671507730000063
n is the total number of the traveling wave current data; l is coefficient and has a value range of [0.2, 0.5 ]]。
In a preferred embodiment, in step 2, the wave head confidence interval in each scale is:
Figure BDA0002671507730000064
in the formula, n is the maximum scale of wavelet transformation; i isnA set of modulus maxima at the nth scale; k is the scale of wavelet transformation;
Figure BDA0002671507730000065
is a reference point at the k +1 th scale; ckAnd the wave head confidence interval at the k-th scale.
In a preferred embodiment, in step 2, the calculation method of the reference points of each scale is as follows:
Figure BDA0002671507730000066
in the formula, k is the scale of wavelet transformation; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head; n is the maximum scale of wavelet transform; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1); ckIs a wave head credible interval under the k-th scale;
Figure BDA0002671507730000067
is a reference point at the k-th scale; min (J)k) Is a set JkMinimum of all elements in。
In a preferred embodiment, in step 3, the lateral reliability index in each scale is the number of elements in the modulus maximum value set in the scale that are smaller than the reference point in the scale, and the calculation formula is as follows:
Figure BDA0002671507730000071
in the formula, k is the scale of wavelet transformation; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1);
Figure BDA0002671507730000072
is a reference point at the k-th scale; n iskAnd the k-th scale is a transverse reliability index.
In a preferred embodiment, in the step 4, the confidence points are integrated into the smallest k scaleminThe judging method comprises the following steps:
Figure BDA0002671507730000073
in the formula, k is the scale of wavelet transformation; n iskThe k-th scale is a transverse reliability index; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head;
Figure BDA0002671507730000074
indicating an empty set.
In a preferred embodiment, in the step 4, the step of locally correcting the reference point includes: at the k-thminScale wavelet transform results
Figure BDA0002671507730000075
From the second place to
Figure BDA0002671507730000076
The point starts searching forward until finding less than
Figure BDA0002671507730000077
The first point of (2), the latter point of the point is taken as the reference point after the local correction; wherein k isminIs the minimum scale of the reference point for comprehensive credibility, N is the total number of the traveling wave current data,
Figure BDA0002671507730000078
is the k-thminThe ith point of the scale wavelet transform result,
Figure BDA0002671507730000079
is the k-thminA reference point on a scale.
The method of the present application is described below by way of example of a four-scale dyadic wavelet transform.
Step 1: and acquiring fault traveling wave current data, performing four-scale wavelet transformation on the traveling wave current data, and solving a modulus maximum value set under each scale.
The modulus maximum value set solving formula under each scale is as follows:
Figure BDA00026715077300000710
in the formula, k is the scale of wavelet transformation, and k is more than or equal to 1 and less than or equal to 4; m isk,i-1、mk,i、mk,i+1Absolute values of wavelet transformation results of ith-1, ith and i +1 points of the kth scale respectively;
Figure BDA00026715077300000711
is the maximum value of the absolute value of the k-th scale wavelet transform result,
Figure BDA00026715077300000712
and N is the total number of the traveling wave current data.
In the step 2, the wave head confidence interval under each scale is as follows:
Figure BDA0002671507730000081
in the formula I4A set of modulus maxima at scale 4; k is the scale of wavelet transformation;
Figure BDA0002671507730000082
is a reference point at the k +1 th scale; ckAnd the wave head confidence interval at the k-th scale.
Step 2: and taking the first mode maximum value of the maximum scale as a reference point, searching the small scale longitudinally layer by layer, and sequentially obtaining the reference point of each scale in the wave head credible interval.
The calculation method of the reference points of each scale is as follows:
Figure BDA0002671507730000083
in the formula Ik,jIs IkThe jth element of (1); ckIs a wave head credible interval under the k-th scale;
Figure BDA0002671507730000084
is a reference point at the k-th scale; min (J)k) Is a set JkMinimum of all elements in (c).
And step 3: the lateral reliability index is obtained from the respective reference points by each scale.
The transverse confidence index under each scale is the scale modulus maximum value set IkMiddle ratio
Figure BDA0002671507730000085
The small number of elements, the calculation formula is as follows:
Figure BDA0002671507730000086
in the formula, k is the scale of wavelet transformation; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1);
Figure BDA0002671507730000087
is a reference point at the k-th scale; n iskAnd the k-th scale is a transverse reliability index.
And 4, step 4: and finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and locally correcting the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time.
The minimum scale judgment method for comprehensively credible reference points comprises the following steps:
Figure BDA0002671507730000088
in the formula, k is the scale of wavelet transformation; n iskThe k-th scale is a transverse reliability index; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head;
Figure BDA0002671507730000089
indicating an empty set.
The step of locally correcting the reference point is as follows: at the k-thminScale wavelet transform results
Figure BDA0002671507730000091
From the second place to
Figure BDA0002671507730000092
The point starts searching forward until finding less than
Figure BDA0002671507730000093
The first point of (2) is a reference point after the point is locally corrected.
FIG. 2 shows a traveling wave current data, wavelet analysis results and modulus maxima at various scales, where the singularity of traveling wave head is very obvious when the traveling wave current data is viewed, and according to the method of the present application, the first modulus maximum point under the 4 th scale wavelet transform is
Figure BDA0002671507730000094
Longitudinally searching layer by taking the point as a reference point, and respectively finding the reference point under the 3 rd scale, the 2 nd scale and the 1 st scale according to the wave head credible interval
Figure BDA0002671507730000095
And the transverse reliability index n under each scalekAll are 0, so the smallest scale of the finally found reference points which can be comprehensively found is the 1 st scale, and then the reference points are locally corrected under the scale, namely the reference points are found from the 273 rd point until less than 0.5m is found1,273The first point 128.6, which is the 271 th point in the figure, is taken as the reference point after the local correction, that is, the 272 th point, and the real traveling wave arrival is at the 271 th point, so that the wave head arrival time can be identified more accurately by using the method of the present application.
FIG. 3 is another embodiment of the present application, in which traveling wave current data, wavelet analysis results and modulus maxima at various scales are shown, and traveling wave headers of the embodiment are very gentle as seen from the traveling wave current data, and according to the method of the present application, the first modulus maximum point at the 4 th scale wavelet transform is
Figure BDA0002671507730000096
Longitudinally searching layer by taking the point as a reference point, and respectively finding the reference point under the 3 rd scale, the 2 nd scale and the 1 st scale according to the wave head credible interval
Figure BDA0002671507730000097
Figure BDA0002671507730000098
Wherein the transverse reliability index of the 3 rd scale is 0, the transverse reliability index of the 2 nd scale is 2, the transverse reliability index of the 1 st scale is obviously larger than 5, so the finally found minimum comprehensive credibility scale of the reference point is the 2 nd scale, and then the reference point is locally corrected under the scale, namely the reference point is found from the 183 th point to the front until the reference point is found to be less than 0.5m2,183The first point, point 181 in the figure, of 14.97, and thenThe point 182, which is the latter point of the point, is used as the reference point after local correction, the reference point is converted into the point 364 in the traveling wave current data, and the real traveling wave arrival is at the point 365, so that the arrival time of the wave head can be accurately identified even if the wave head changes more smoothly by adopting the method.
Fig. 4 shows an embodiment of a wave head recognition device under multi-scale wavelet transform according to the present application, which includes a modulus maximum value set calculation unit, a reference point calculation unit, a lateral reliability index calculation unit, and a correction recognition unit, which are connected in sequence. Wherein:
the modulus maximum value set calculation unit: the method is used for acquiring fault traveling wave current data, performing multi-scale wavelet transformation on the traveling wave current data and solving a modulus maximum value set under each scale.
The reference point calculating unit: and the method is used for searching layer by layer in the longitudinal direction of the small scale by taking the first mode maximum value of the maximum scale as a reference point, and sequentially obtaining the reference point of each scale in the wave head credible interval.
The lateral reliability index calculation unit: and the device is used for solving the transverse credibility index of each reference point according to each scale.
The correction recognition unit: and the method is used for finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and performing local correction on the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time.
In a preferred embodiment of the apparatus, in the module maximum value set calculation unit, the multi-scale wavelet transform method is n (n ≧ 3) scale dyadic wavelet transform.
In an embodiment of the preferred apparatus, in the module maximum set calculating unit, a module maximum set calculation formula at each scale is as follows:
Figure BDA0002671507730000101
wherein k is the scale of wavelet transform, and k is 1, 2, …, n; n is the maximum scale of wavelet transform; i represents a waveletThe serial number of the transform result; m isk,i-1、mk,i、mk,i+1Absolute values of wavelet transformation results of ith-1, ith and i +1 points of the kth scale respectively;
Figure BDA0002671507730000102
is the maximum value of the absolute value of the k-th scale wavelet transform result,
Figure BDA0002671507730000103
n is the total number of the traveling wave current data; l is coefficient and has a value range of [0.2, 0.5 ]]。
In an embodiment of the preferred apparatus, in the reference point calculating unit, the wave head confidence interval at each scale is:
Figure BDA0002671507730000104
in the formula, n is the maximum scale of wavelet transformation; i isnA set of modulus maxima at the nth scale; k is the scale of wavelet transformation;
Figure BDA0002671507730000105
is a reference point at the k +1 th scale; ckAnd the wave head confidence interval at the k-th scale.
In a preferred embodiment of the apparatus, in the reference point calculating unit, a method of calculating reference points of each scale is as follows:
Figure BDA0002671507730000106
in the formula, k is the scale of wavelet transformation; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head; n is the maximum scale of wavelet transform; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1); ckIs a wave head credible interval under the k-th scale;
Figure BDA0002671507730000111
is a reference point at the k-th scale; min (J)k) Is a set JkMinimum of all elements in (c).
In a preferred embodiment of the apparatus, in the horizontal reliability index calculation unit, the horizontal reliability index in each scale is the number of elements in the modulus maximum value set in the scale that are smaller than the reference point in the scale, and the calculation formula is as follows:
Figure BDA0002671507730000112
in the formula, k is the scale of wavelet transformation; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1);
Figure BDA0002671507730000113
is a reference point at the k-th scale; n iskAnd the k-th scale is a transverse reliability index.
In a preferred embodiment of the device, the smallest scale k for which the reference points are integrated in the correction recognition unit is reliableminThe judging method comprises the following steps:
Figure BDA0002671507730000114
in the formula, k is the scale of wavelet transformation; n iskThe k-th scale is a transverse reliability index; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head;
Figure BDA0002671507730000115
indicating an empty set.
In a preferred embodiment of the apparatus, the step of locally correcting the reference point in the correction recognition unit is as follows: at the k-thminScale wavelet transform results
Figure BDA0002671507730000116
From the second place to
Figure BDA0002671507730000117
The point starts searching forward until finding less than
Figure BDA0002671507730000118
The first point of (2), the latter point of the point is taken as the reference point after the local correction; wherein k isminIs the minimum scale of the reference point for comprehensive credibility, N is the total number of the traveling wave current data,
Figure BDA0002671507730000119
is the k-thminThe ith point of the scale wavelet transform result,
Figure BDA00026715077300001110
is the k-thminA reference point on a scale.
The method adopts multiple comprehensive technologies such as longitudinal credibility interval searching, transverse feasibility judgment, datum point local correction and the like under multi-scale wavelet transformation, wherein the longitudinal credibility interval searching ensures the optimal scale capable of representing the arrival of the traveling wave head, the transverse credibility judgment can eliminate the scale with larger noise and serious interference, the datum point local correction realizes fine adjustment of the datum point, and the wave head identification result is closer to the actual wave head arrival time. The method has obvious effect of improving the traveling wave identification precision with gentle wave head change.
The present application is not limited to the above embodiments, and the above embodiments are only used for facilitating the understanding of the core idea of the present application, and any modification made to the present application or equivalent substitution made according to the idea of the present application and the modification made within the scope of the present application shall fall within the protection scope of the present application.

Claims (16)

1. A wave head identification method under multi-scale wavelet transform is characterized by comprising the following steps:
step 1: acquiring fault traveling wave current data, performing multi-scale wavelet transformation on the traveling wave current data, and solving a modulus maximum value set under each scale;
step 2: searching in a small scale longitudinally layer by taking the first mode maximum value of the maximum scale as a reference point, and sequentially obtaining the reference point of each scale in a wave head credible interval;
and step 3: each scale calculates a transverse credibility index from each datum point;
and 4, step 4: and finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and locally correcting the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time.
2. The method for identifying the wave head under the multi-scale wavelet transform as claimed in claim 1, wherein: in the step 1, the multi-scale wavelet transform method is n (n is more than or equal to 3) scale binary wavelet transform.
3. The method for identifying the wave head under the multi-scale wavelet transform as claimed in claim 1, wherein: in step 1, the modulus maximum value set at each scale is calculated as follows:
Figure FDA0002671507720000011
wherein k is the scale of wavelet transform, and k is 1, 2, …, n; n is the maximum scale of wavelet transform; i represents the serial number of the wavelet transformation result; m isk,i-1、mk,i、mk,i+1Absolute values of wavelet transformation results of ith-1, ith and i +1 points of the kth scale respectively;
Figure FDA0002671507720000012
is the maximum value of the absolute value of the k-th scale wavelet transform result,
Figure FDA0002671507720000013
n is the total number of the traveling wave current data; l is coefficient and has a value range of [0.2, 0.5 ]]。
4. The method for identifying the wave head under the multi-scale wavelet transform as claimed in claim 1, wherein: in the step 2, the wave head confidence interval under each scale is as follows:
Figure FDA0002671507720000014
in the formula, n is the maximum scale of wavelet transformation; i isnA set of modulus maxima at the nth scale; k is the scale of wavelet transformation;
Figure FDA0002671507720000015
is a reference point at the k +1 th scale; ckAnd the wave head confidence interval at the k-th scale.
5. The method for identifying the wave head under the multi-scale wavelet transform as claimed in claim 1, wherein: in the step 2, the calculation method of the reference points of each scale is as follows:
Figure FDA0002671507720000021
in the formula, k is the scale of wavelet transformation; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head; n is the maximum scale of wavelet transform; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1); ckIs a wave head credible interval under the k-th scale;
Figure FDA0002671507720000022
is a reference point at the k-th scale; min (J)k) Is a set JkMinimum of all elements in (c).
6. The method for identifying the wave head under the multi-scale wavelet transform as claimed in claim 1, wherein: in step 3, the transverse reliability index in each scale is the number of elements in the modulus maximum value set in the scale, which is smaller than the reference point in the scale, and the calculation formula is as follows:
Figure FDA0002671507720000023
in the formula, k is the scale of wavelet transformation; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1);
Figure FDA0002671507720000024
is a reference point at the k-th scale; n iskAnd the k-th scale is a transverse reliability index.
7. The method for identifying the wave head under the multi-scale wavelet transform as claimed in claim 1, wherein: in the step 4, the smallest scale k for the reference points to be comprehensively credibleminThe judging method comprises the following steps:
Figure FDA0002671507720000025
in the formula, k is the scale of wavelet transformation; n iskThe k-th scale is a transverse reliability index; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head;
Figure FDA0002671507720000026
indicating an empty set.
8. The method for identifying the wave head under the multi-scale wavelet transform as claimed in claim 1, wherein: in the step 4, the step of locally correcting the reference point is as follows: at the k-thminScale wavelet transform results
Figure FDA0002671507720000027
From the second place to
Figure FDA0002671507720000028
The point starts searching forward until finding less than
Figure FDA0002671507720000029
The first point of (2), the latter point of the point is taken as the reference point after the local correction; wherein k isminIs the minimum scale of the reference point for comprehensive credibility, N is the total number of the traveling wave current data,
Figure FDA0002671507720000031
is the k-thminThe ith point of the scale wavelet transform result,
Figure FDA0002671507720000032
is the k-thminA reference point on a scale.
9. A wave head recognition device under multi-scale wavelet transform is characterized by comprising a modulus maximum value set calculation unit, a datum point calculation unit, a transverse reliability index calculation unit and a correction recognition unit which are sequentially connected; wherein:
the modulus maximum value set calculation unit: the system is used for acquiring fault traveling wave current data, performing multi-scale wavelet transformation on the traveling wave current data and solving a modulus maximum value set under each scale;
the reference point calculating unit: the device is used for searching in layers longitudinally in a small scale by taking the first mode maximum value of the maximum scale as a reference point, and sequentially solving the reference point of each scale in a wave head credible interval;
the lateral reliability index calculation unit: the device is used for solving the transverse credibility index of each reference point according to each scale;
the correction recognition unit: and the method is used for finding the minimum scale of the comprehensive credibility of the reference points according to the reference points of all scales and the transverse credibility index, and performing local correction on the reference points, wherein the time corresponding to the locally corrected reference points is taken as the wave head time.
10. The apparatus for wave-front recognition under multi-scale wavelet transform according to claim 9, wherein: in the module maximum value set calculation unit, the multi-scale wavelet transformation method is n (n is more than or equal to 3) scale binary wavelet transformation.
11. The apparatus for wave-front recognition under multi-scale wavelet transform according to claim 9, wherein: in the module maximum value set calculation unit, the module maximum value set under each scale is calculated according to the following formula:
Figure FDA0002671507720000033
wherein k is the scale of wavelet transform, and k is 1, 2, …, n; n is the maximum scale of wavelet transform; i represents the serial number of the wavelet transformation result; m isk,i-1、mk,i、mk,i+1Absolute values of wavelet transformation results of ith-1, ith and i +1 points of the kth scale respectively;
Figure FDA0002671507720000034
is the maximum value of the absolute value of the k-th scale wavelet transform result,
Figure FDA0002671507720000035
n is the total number of the traveling wave current data; l is coefficient and has a value range of [0.2, 0.5 ]]。
12. The apparatus for wave-front recognition under multi-scale wavelet transform according to claim 9, wherein: in the reference point calculation unit, the wave head confidence interval under each scale is as follows:
Figure FDA0002671507720000041
in the formula, n is the maximum scale of wavelet transformation; i isnA set of modulus maxima at the nth scale; k is the scale of wavelet transformation;
Figure FDA0002671507720000042
is a reference point at the k +1 th scale; ckAnd the wave head confidence interval at the k-th scale.
13. The apparatus for wave-front recognition under multi-scale wavelet transform according to claim 9, wherein: in the reference point calculation unit, the calculation method of the reference points of each scale is as follows:
Figure FDA0002671507720000043
in the formula, k is the scale of wavelet transformation; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head; n is the maximum scale of wavelet transform; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1); ckIs a wave head credible interval under the k-th scale;
Figure FDA0002671507720000044
is a reference point at the k-th scale; min (J)k) Is a set JkMinimum of all elements in (c).
14. The apparatus for wave-front recognition under multi-scale wavelet transform according to claim 9, wherein: in the transverse reliability index calculation unit, the transverse reliability index under each scale is the number of elements in the modulus maximum value set under the scale, which are smaller than the reference point under the scale, and the calculation formula is as follows:
Figure FDA0002671507720000045
in the formula, k is the scale of wavelet transformation; i iskA set of modulus maxima at the k-th scale; i isk,jIs IkThe jth element of (1);
Figure FDA0002671507720000046
is a reference point at the k-th scale; n iskAnd the k-th scale is a transverse reliability index.
15. The apparatus for wave-front recognition under multi-scale wavelet transform according to claim 9, wherein: in the correction recognition unit, the smallest scale k with credible integrated reference pointsminThe judging method comprises the following steps:
Figure FDA0002671507720000047
in the formula, k is the scale of wavelet transformation; n iskThe k-th scale is a transverse reliability index; j. the design is a squarekA modulus maximum value set in a credible interval of a kth scale wave head;
Figure FDA0002671507720000051
indicating an empty set.
16. The apparatus for wave-front recognition under multi-scale wavelet transform according to claim 9, wherein: in the correction recognition unit, the step of locally correcting the reference point is as follows: at the k-thminScale wavelet transform results
Figure FDA0002671507720000052
From the second place to
Figure FDA0002671507720000053
The point starts searching forward until finding less than
Figure FDA0002671507720000054
The first point of (2), the latter point of the point is taken as the reference point after the local correction; wherein k isminIs the minimum scale of the reference point for comprehensive credibility, N is the total number of the traveling wave current data,
Figure FDA0002671507720000055
is the k-thminThe ith point of the scale wavelet transform result,
Figure FDA0002671507720000056
is the k-thminA reference point on a scale.
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