CN112444705A - Regression correction method for wavelet transformation fault location - Google Patents

Regression correction method for wavelet transformation fault location Download PDF

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Publication number
CN112444705A
CN112444705A CN201910829658.6A CN201910829658A CN112444705A CN 112444705 A CN112444705 A CN 112444705A CN 201910829658 A CN201910829658 A CN 201910829658A CN 112444705 A CN112444705 A CN 112444705A
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fault
distance
traveling wave
distance measurement
theoretical
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CN112444705B (en
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李岩
李双明
邹康
易文俊
曹树新
曹权
刘辉
韩子鹏
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Nanjing University of Science and Technology
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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
    • G01R31/11—Locating faults in cables, transmission lines, or networks using pulse reflection methods
    • 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
    • G01R31/088—Aspects of digital computing
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
    • G06F17/148—Wavelet transforms
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

Abstract

The invention discloses a regression correction method for wavelet transformation fault location. By establishing an actual point of failure d1Theoretically measured fault point d0And a regression model of the line length L, found in (d)0‑d1)/d1And d1the/L presents a nonlinear relation which can be fitted by a polynomial, the nonlinear relation is summarized by a equation, and the theoretical distance d can be solved by substituting the theoretical distance solved by wavelet transformation and fixed wave velocity value and the line length L into the equation0The corrected fault distance is obtained by the method, a complex link of solving the wave speed is omitted, db4 distance measurement is simpler and more convenient, a regression model is used for correcting a db4 distance measurement result, and the accuracy of db4 fault distance measurement is improved.

Description

Regression correction method for wavelet transformation fault location
Technical Field
The invention belongs to the field of line fault positioning by a double-end traveling wave method, and particularly relates to a regression correction method for wavelet transformation fault positioning.
Background
The accurate positioning of the transmission line fault can reduce the fault routing inspection time and help to recover the electricity consumption of industry and residents, and among a plurality of fault positioning methods, the traveling wave distance measurement method becomes a hot point for studying by scholars at home and abroad due to the advantages of strong adaptability, small influence of fault type ground resistance and the like.
The transmission line fault positioning technology is mainly based on a double-end traveling wave distance measurement method, and the fault positioning accuracy of the distance measurement method is mainly influenced by two aspects, one is the extraction accuracy of the arrival time point of the fault traveling wave head; the second is the determination of the traveling wave velocity, and in the existing technology for extracting the traveling wave head, a Hilbert-Huang algorithm or a wavelet transformation method is mainly used, and both algorithms extract the time point of the fault traveling wave head by identifying the signal frequency mutation point, but because the transmission fault traveling wave is transmitted on the line, the energy or the frequency of the transmission fault traveling wave is inevitably attenuated and affects the frequency identification of the two algorithms, and finally the extraction error of the time point is caused. The uncertainty of the traveling wave velocity can cause the distance measurement error of the traveling wave method, the prior art measures the time of the traveling wave reaching the terminal by the refraction and reflection on the line for many times, uses the simultaneous equation of the time and the known line length, and finally obtains the traveling wave velocity by solving the equation.
Disclosure of Invention
The invention aims to provide a regression correction method for wavelet transformation fault location.
The technical solution for realizing the purpose of the invention is as follows: a regression correction method for wavelet transformation fault location comprises the following steps:
(1) setting the total line length of the high-voltage three-phase power transmission line as L, and marking two end points of the power transmission line as M, N respectively; when a single-phase earth fault occurs, the distance between an actual fault point and the M end is set as d1Setting the distance between the fault and the M end as d0The error component of the theoretical fault distance from the actual fault point distance is denoted as Δ d (Δ d = d)1-d0) The corrected theoretical distance is set as d0’；
(2) The high-voltage transmission line M, N is simulated to simulate single-phase earth fault, and when fault traveling wave current signals I are obtained at two ends of M, NM、INThen, for two-terminal signal IM、INPerforming Clark transformation to obtain line-mode components, performing db4 wavelet transformation on alpha component signals in the line-mode components at two ends, and identifying time T of arrival M, N of traveling wave headM、TNThe traveling wave velocity v is selected from the speed of light and T is determinedM、TNSubstituting the parameters into a double-end traveling wave distance measurement formula to obtain a theoretical distance measurement distance d0；
(3) For the L parameter in the simulation model to be unchanged, d is changed1The parameters are then measured by the method in step (2) and d1Corresponding d0Data in d0、d1And establishing a nonlinear regression model based on the multiple groups of data samples of L to finally obtain delta d and d0A nonlinear mathematical relationship of L;
(4) after the simulation is finished and the mathematical relation is obtained, step (2) is carried out on the fault traveling wave waveform of the actual power transmission line to obtain the theoretical distance d0And d is obtained by utilizing the nonlinear mathematical relation in the step (3)0Substituting L into the equation to obtain an error component delta d, and using the error component to obtain a db4 wavelet theory distance measurement result d0Correction, i.e. d0’=Δd+d0Finally, d can be obtained0’。
Compared with the prior art, the invention has the following remarkable advantages: (1) the extraction error of the traveling wave head reaching the time point caused by different traveling wave attenuation due to the difference of the fault distance can be effectively reduced; (2) the wave speed is determined without measuring the refraction and reflection signals of the fault traveling wave for multiple times, but the distance measurement is carried out by using the wave speed with a fixed empirical value, and finally the correction is carried out by using a regression correction formula, so that the method is simpler and more convenient; (3) and the theoretical distance measurement amount is corrected through the fitted polynomial equation, so that the distance measurement error amount is smaller and the precision is higher.
Drawings
Fig. 1 is an overall schematic view of the present invention.
FIG. 2 is a schematic diagram of a circuit simulation according to the present invention.
FIG. 3 is a schematic diagram of the decomposition of fault traveling waves by the db4 wavelet transform of the present invention.
FIG. 4 is a diagram illustrating a nonlinear relationship between a theoretical fault distance measurement and an actual fault distance measurement according to the present invention.
Detailed Description
The invention obtains the mathematical relationship of the line fault distance and the theoretical distance measurement error amount of db4 wavelet transformation by researching the nonlinear relationship of the line fault distance and the theoretical distance measurement error amount, and corrects the theoretical distance measurement distance to be subjected to fault location by the mathematical relationship.
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 1, fig. 1 is an overall schematic of the present invention.
The actual fault point d is obtained by establishing simulation and simulation1Theoretically measured fault point d0And a regression model of the line length L, found in (d)0-d1)/d1And d1the/L presents a nonlinear relation which can be fitted by a polynomial, the nonlinear relation is summarized by a equation, and the theoretical distance d can be solved by substituting the theoretical distance solved by wavelet transformation and fixed wave velocity value and the line length L into the equation0The corrected fault distance is obtained, thereby improving the precision of fault distance measurement,
referring to fig. 2, a simulation model (as shown in fig. 2) is first established for an actual line, where the total length of the line is L, and the actual fault point is d1The theoretical distance measurement of db4 wavelet transform by the double-ended traveling wave method is d0And db4 measures the error component of the fault distance from the actual fault point distance as Δ d (Δ d = d)0-d1);
Referring to fig. 3, a power transmission line M, N is simulated, and a fault traveling wave current signal I is obtained at both ends M, NM、INThen, for two-terminal signal IM、INPerforming Clark transformation to obtain line-mode components, performing db4 wavelet transformation on alpha component signals in the line-mode components at two ends to identify time T of arrival M, N of traveling wave headM、TNThe traveling wave velocity v is directly the speed of light and T is measuredM、TNSubstituting the parameters into a double-end traveling wave distance measurement formula to obtain the db4 wavelet theory distance measurement d0；
For L parameter in simulation model, the method is not changed, and d is changed1Parameters (only the length of Line1-1 and Line1-2 in the attached figure 2 are changed correspondingly), and then the parameters are sequentially measured and d is measured by using the db4 wavelet ranging method1Corresponding d0Data in d0、d1Establishing a nonlinear regression model on the basis of the plurality of groups of data samples of the L;
referring to fig. 4, taking total lengths of the lines L =100km and L =150km as an example, fig. 4 shows a nonlinear relationship between the two.
And (3) performing curve fitting on the correlation between the independent variable factor and the dependent variable factor by adopting 8-order to 10-order polynomial regression to obtain a nonlinear mathematical relation between the independent variable factor and the dependent variable factor: (Δ d/d)1)=ΣPi(d1/L)iWherein i is the order of the polynomial and Pi is the coefficient of the polynomial;
when the fault point of actual line is positioned, the db4 wavelet transform is used to measure the theoretical fault distance d0Then d is converted to d in the relation0-d1Then the theoretical distance d is measured0Substituting the total length L of the line, solving a nonlinear mathematical relation, and finally obtaining d1. And completing the db4 wavelet ranging correction.
The invention establishes an actual fault point d1Theoretically measured fault point d0And regression model of line length LType (d) found in0-d1)/d1And d1the/L presents a nonlinear relation which can be fitted by a polynomial, the nonlinear relation is summarized by a equation, and the theoretical distance d can be solved by substituting the theoretical distance solved by wavelet transformation and fixed wave velocity value and the line length L into the equation0The corrected fault distance improves the precision of fault distance measurement, avoids errors caused by the attenuation difference of traveling waves transmitted by a line due to different distances of fault points of the line, solves the problem by using a fixed wave velocity value, abandons a complex wave velocity solving formula, and is simpler and more convenient in the distance measurement process.

Claims (2)

1. A regression correction method for wavelet transformation fault location is characterized by comprising the following steps:
(1) setting the total line length of the high-voltage three-phase power transmission line as L, and marking two end points of the power transmission line as M, N respectively; when a single-phase earth fault occurs, the distance between an actual fault point and the M end is set as d1Setting the distance between the fault and the M end as d0The error component of the theoretical fault distance from the actual fault point distance is denoted as Δ d (Δ d = d)1-d0) The corrected theoretical distance is set as d0’；
(2) The high-voltage transmission line M, N is simulated to simulate single-phase earth fault, and when fault traveling wave current signals I are obtained at two ends of M, NM、INThen, for two-terminal signal IM、INPerforming Clark transformation to obtain line-mode components, performing db4 wavelet transformation on alpha component signals in the line-mode components at two ends, and identifying time T of arrival M, N of traveling wave headM、TNThe traveling wave velocity v is selected from the speed of light and T is determinedM、TNSubstituting the parameters into a double-end traveling wave distance measurement formula to obtain a theoretical distance measurement distance d0；
(3) For the L parameter in the simulation model to be unchanged, d is changed1The parameters are then measured by the method in step (2) and d1Corresponding d0Data in d0、d1Based on multiple groups of data samples of LEstablishing a nonlinear regression model to finally obtain delta d and d0A nonlinear mathematical relationship of L;
(4) after the simulation is finished and the mathematical relation is obtained, step (2) is carried out on the fault traveling wave waveform of the actual power transmission line to obtain the theoretical distance d0And d is obtained by utilizing the nonlinear mathematical relation in the step (3)0Substituting L into the equation to obtain an error component delta d, and using the error component to obtain a db4 wavelet theory distance measurement result d0Correction, i.e. d0’=Δd+d0Finally, d can be obtained0’。
2. The regression correction method according to claim 1, characterized in that:
establishing a nonlinear regression model in the step (3) by using the ratio delta d/d of the error component to the actual fault point distance1The ratio d of the actual fault point distance to the total line length is an automatic variable factor1the/L is a dependent factor;
by changing the position d of the fault point of the transmission line in the simulation0Obtaining a large amount of data of the auto-variable factor and the dependent factor, and performing curve fitting on the correlation of the auto-variable factor and the dependent factor by adopting 8-10 order polynomial regression to obtain a nonlinear mathematical relation (delta d/d) of the auto-variable factor and the dependent factor1)=ΣPi(d1/L)iWherein i is the order of the polynomial, PiIs a polynomial coefficient.
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