CN107505538A - The asynchronous Fault Locating Method of half-wave power transmission circuit based on line mode voltage traveling wave amplitude attenuation characteristic - Google Patents
The asynchronous Fault Locating Method of half-wave power transmission circuit based on line mode voltage traveling wave amplitude attenuation characteristic Download PDFInfo
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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
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Abstract
The invention discloses a kind of asynchronous Fault Locating Method of half-wave power transmission circuit based on line mode voltage traveling wave amplitude attenuation characteristic, the amplitude attenuation rule of sowing time high fdrequency component is uploaded in half-wave power transmission circuit based on line mode voltage traveling wave, it is proposed by Single Terminal Traveling Wave Fault Location be with the asynchronous fault location scheme of the half-wave power transmission circuit that traveling wave attenuation characteristic is combined, its core concept：After failure occurs, rough estimate abort situation first then according to line mode voltage traveling wave amplitude attenuation degree, selects corresponding fault distance-finding method to be positioned.The attenuation characteristic range measurement principle of amplitude and single end distance measurement principle when being propagated based on line mode voltage traveling wave are combined and carry out half-wave power transmission line fault positioning by the present invention, have given full play to the advantage of two kinds of distance-finding methods.The present invention has higher practical engineering value without each measurement point precise synchronization.
Description
Technical Field
The invention relates to a method for positioning a fault of a half-wavelength power transmission line by utilizing the amplitude characteristic of the high-frequency component of a head wave head of a line mode voltage traveling wave.
Background
Half-wavelength power transmission and half-wavelength alternating current power transmission are used as an ultra-long distance alternating current power transmission mode, and compared with conventional alternating current power transmission, the half-wavelength alternating current power transmission mode has the advantages of no need of installing reactive compensation equipment, strong transmission capacity, good economy and the like. Because the transmission distance of the half-wavelength transmission line is long, and the dispersion and attenuation of traveling waves are obvious after a fault occurs, the error is very large by utilizing the traditional traveling wave distance measurement method.
At present, the traveling wave distance measurement of the power transmission line mainly comprises a single-end method and a double-end method, wherein the single-end method does not need synchronization, but needs to detect the arrival time of a plurality of wave heads. The double-ended method requires synchronization but only detection of the head-wave arrival time. In any distance measurement method, if the method is directly used on a half-wavelength transmission line for fault location, the error is large (the maximum can reach about 2%). Therefore, the research on the half-wavelength transmission line fault positioning method with good reliability and high positioning precision is necessary.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the problem of fault location of the existing half-wavelength power transmission line by a traveling wave method, the invention provides a half-wavelength power transmission line asynchronous fault location method based on the attenuation characteristic of a line mode voltage traveling wave amplitude.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:
a half-wavelength power transmission line asynchronous fault positioning method based on line mode voltage traveling wave amplitude attenuation characteristics comprises the following steps:
(1) Respectively representing measurement points of the head end, the tail end and the middle point of the half-wavelength power transmission line by A, B and points C, and representing a fault point by F; after the half-wavelength transmission line has a fault, respectively extracting the original voltage traveling wave signals of a head end point A, a tail end point B and a middle point C, then carrying out phase-mode conversion on the signals,obtain the original line mode voltage traveling wave signal, record it asWherein subscripts denote points a, B, and C, and superscript (1) denotes a line mode;
(2) Acquiring original line mode voltage traveling wave signals measured at the point A, the point B and the point CThe amplitudes of a plurality of signal components with different frequency components in head wave head signals with different data window lengths; at the same time, the following formula is used to find the arbitrary frequency f n Attenuation constant alpha of traveling wave amplitude of down-line mode voltage n ：
Wherein Z n ＝R n +jω n L and Y n ＝G n +jω n C is respectively the frequency f n Line mode impedance and admittance of the lower line; j is an imaginary unit; r n And G n Are respectively the frequency f n Line mode resistance and conductance of the lower line; l and C are respectively a power frequency line mode inductor and a capacitor of the circuit; omega n ＝2πf n Is the corresponding angular frequency; the subscript n representing all electrical quantities at frequency f n Obtaining the product;
(3) The frequency of the line mode voltage traveling wave signal measured by the point A and the point B in the head wave head signal with the signal data window length of 82 is omega i Signal amplitude of =22.727kHzAndthe amplitude ratio K is calculated by substituting the following formula AB ：
In which x represents the distance variable and i represents the quantity at frequency ω i The following was obtained.
(4) Judgment of K AB And size of 1, determine failed segment: if K AB &1, if the fault occurs on the first half section of the line, turning to the step (5); if K is AB &1, if the fault occurs on the second half-section line, turning to the step 10; if K AB =1, the fault occurred at a point in the line, and the fault distance was 1500km;
(5) Utilizing A point original line mode voltage traveling wave signalFinding out the Teager energy corresponding to the two traveling wave heads before reaching the point A by using a Teager energy operator method, and recording the value as E 1A And E 2A And the energy attenuation factor eta of the traveling wave Teager is calculated by the following two formulas 1A And η 2A ：
And η 2A ＝E 2A
In the formula, subscripts A, 1 and 2 respectively represent a point A, a first traveling wave head of the point A and a second traveling wave head of the point A;
(6) Eta obtained by calculation in the step (5) 1A And η 2A And (3) introducing the following criteria to determine a method for accurately positioning the subsequent fault:
(a) If eta 1A > 0.4 ‰ η 2A &1100, determining the fault position by single-ended distance measurement by utilizing the traveling wave information of the near-end point A, and turning to the step (7);
(b) If eta 1A Less than or equal to 0.4 per thousand or eta 2A If the fault position is less than or equal to 1100, determining the fault position by using traveling wave information of a near end point A and a middle point C and adopting a double-end amplitude ratio method, and turning to the step (8);
(7) Calibrating the original line mode voltage traveling wave signal of the point A by using a Teager energy operator methodThe arrival time of the first two wave heads is respectively T1 and T2, and the fault distance x from the head end A point is calculated by the following single-ended traveling wave distance measurement formula:
wherein v is the traveling wave velocity and takes the value of 2.95 multiplied by 10 8 m/s；
(8) Selecting the amplitudes corresponding to all signals of which the frequency components fall between 20kHz and 50kHz in the line mode voltage traveling wave head signals of the data windows with different lengths at the point A and the point C in the step (2), and solving the ratio of the amplitudes of the corresponding frequency components; for each amplitude ratio K AC And calculating a fault distance x from the head end A point by the following double-end amplitude ratio distance measurement formula:
wherein, L represents that the total length of the line is 3000km;is a frequency f i Attenuation constant of traveling wave amplitude of lower line mode voltage; the above table (1) shows the line mode, and the subscript i shows the frequency f i The following steps.
(9) Calculating the arithmetic mean value of all fault distances in the step (8), wherein the arithmetic mean value is the fault distance from the final A point to the head end, and the fault positioning is finished at this moment;
(10) Utilizing original line mode voltage traveling wave signal of B pointFinding out the Teager energy corresponding to the two traveling wave heads before reaching the point B by using a Teager energy operator method, and recording the value as E 1B And E 2B And the energy attenuation factor eta of the traveling wave Teager is calculated by the following two formulas 1B And η 2B ：
And η 2B ＝E 2B
In the formula, subscripts B, 1 and 2 respectively represent point B, a first traveling wave head at point B, and a second traveling wave head at point B.
(11) Eta obtained by the calculation of the step (10) 1B And η 2B And (3) introducing the following criteria to determine a method for accurately positioning the subsequent fault:
(a) If eta 1B >, 0.4% o and eta 2B &1100, determining the fault position by single-ended distance measurement by utilizing the traveling wave information of the near-end point B, and turning to the step (12);
(b) If eta 1B Less than or equal to 0.4 per thousand or eta 2B If the current value is less than or equal to 1100, determining the fault position by using traveling wave information of a near-end point B and a middle point C and adopting a double-end amplitude ratio method, and turning to the step (13);
(12) Calibrating the original line mode voltage traveling wave signal of the point B by using a Teager energy operator methodThe arrival time of the first two wave heads is respectively T1 and T2, and the distance x from the tail end B point fault is calculated by the following single-ended traveling wave distance measurement formula:
wherein v is the traveling wave velocity and takes the value of 2.95 multiplied by 10 8 m/s；
(13) Selecting the amplitudes corresponding to all signals of which the frequency components fall between 20kHz and 50kHz in the line mode voltage traveling wave head signals of the data windows with different lengths at the point B and the point C in the step (2), and solving the ratio of the amplitudes of the corresponding frequency components; for each amplitude ratio K BC And calculating a fault distance x from the tail end point B by substituting the following double-end amplitude ratio distance measurement formula:
wherein, L represents that the total length of the line is 3000km;is a frequency f i Attenuation constant of traveling wave amplitude of lower line mode voltage; the above table (1) shows the line mode, and the subscript i shows the frequency f i The following steps.
(14) Calculating the arithmetic mean value of all fault distances in the step (13), wherein the arithmetic mean value is the fault distance of the final distance line model tail end B point; and then, the fault positioning is finished.
In the step (2), each original line mode voltage traveling wave signal measured by the point A, the point B and the point C is obtained according to a calculation data window determining method, a line mode traveling wave high-frequency component amplitude extracting method and a data window frequency sweeping methodThe amplitudes of the signal components of a plurality of different frequency components in the head signal of different data window lengths.
Has the advantages that: the invention combines the attenuation characteristic distance measurement principle based on the amplitude during traveling wave propagation of line mode voltage with the single-end distance measurement principle to position the fault of the half-wavelength power transmission line, and fully exerts the advantages of the two distance measurement methods. The invention does not need the accurate synchronization of each measuring point, and has higher engineering practice significance.
Drawings
FIG. 1 is a schematic diagram of a half-wavelength power transmission line fault;
FIG. 2 is a flow chart of the present invention.
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
The half-wavelength power transmission line is shown in figure 1, wherein A, B and point C are dividedIdentifying the measuring points of the first end, the last end and the middle point of the transmission line, wherein F is a fault point and U is a fault point 1b And U 1f The reverse and forward line mode voltage initial traveling waves, respectively. The dashed arrows in the figure indicate the direction of the initial travelling wave propagation. The invention relates to a half-wavelength power transmission line asynchronous fault positioning method based on line mode voltage traveling wave amplitude attenuation characteristics, which comprises the following steps of:
(1) After the half-wavelength transmission line has a fault, respectively extracting original voltage traveling wave signals of a head end point A, a tail end point B and a middle point C, then carrying out phase-mode conversion on the original voltage traveling wave signals to obtain original line-mode voltage traveling wave signals which are respectively recorded asWherein subscripts denote points a, B, and C, and superscript (1) denotes a line mode;
(2) According to the determination method of the calculation data window, the extraction method of the high-frequency component amplitude of the line mode traveling wave and the sweep frequency method of the variable data window, the original line mode voltage traveling wave signals measured by the points A, B and C are obtainedThe amplitudes of a plurality of signal components with different frequency components in head wave head signals with different data window lengths; at the same time, the following formula is used to obtain an arbitrary frequency f n Attenuation constant alpha of down-line mode voltage traveling wave amplitude n ：
Wherein Z is n ＝R n +jω n L and Y n ＝G n +jω n C is respectively the frequency f n Line mode impedance and admittance of the lower line; j is an imaginary unit; r n And G n Are respectively the frequency f n Line mode resistance and conductance of the lower line; l and C are respectively a power frequency line mode inductor and a capacitor of the circuit; omega n ＝2πf n Is the corresponding angular frequency; the subscript n representing all electrical quantities at frequency f n The following was obtained.
(3) Using point AAnd the frequency of the line mode voltage traveling wave signal measured at the point B in the head wave head signal with the signal data window length of 82 is omega i Signal amplitude of =22.727kHzAndthe amplitude ratio K is calculated by substituting the following formula AB ：
Where x represents the distance variable and i represents the quantity at frequency ω i Obtaining the product;
(4) Judgment of K AB And size of 1, determine failed segment: if K AB &1, if the fault occurs on the first half section of the line, turning to the step (5); if K AB &1, if the fault occurs on the second half-section line, turning to the step 10; if K AB =1, the fault occurred at a point in the line, and the fault distance was 1500km;
(5) Utilizing A point original line mode voltage traveling wave signalFinding out the Teager energy corresponding to the wave heads of the two traveling waves before reaching the point A by a Teager energy operator method, and recording the value as E 1A And E 2A And the energy attenuation factor eta of the traveling wave Teager is calculated by the following two formulas 1A And η 2A ：
And η 2A ＝E 2A
Subscripts a, 1, and 2 denote a point a, a first traveling wave head at a point a, and a second traveling wave head at a point a, respectively. (6) Eta obtained by calculation in the step (5) 1A And η 2A And (3) introducing the following criteria to determine a method for accurately positioning the subsequent fault:
(a) If eta 1A >, 0.4% o and eta 2A &1100, determining the fault position by using the traveling wave information of the point A at the near end and adopting single-ended distance measurement, and turning to the step (7);
(b) If eta 1A Less than or equal to 0.4 per thousand or eta 2A If the fault position is less than or equal to 1100, determining the fault position by using traveling wave information of a near end point A and a middle point C and adopting a double-end amplitude ratio method, and turning to the step (8);
(7) Calibrating the original line mode voltage traveling wave signal of the point A by using a Teager energy operator methodThe arrival time of the first two wave heads is respectively T1 and T2, and the fault distance x from the head end A point is calculated by the following single-ended traveling wave distance measurement formula:
wherein v is the wave speed of the traveling wave, and is 2.95 × 10 8 m/s；
(8) Selecting the amplitudes corresponding to all signals of which the frequency components fall between 20kHz and 50kHz in the line mode voltage traveling wave head signals of the data windows with different lengths at the point A and the point C in the step (2), and solving the ratio of the amplitudes of the corresponding frequency components; for each amplitude ratio K AC And calculating a fault distance x from the head end A point by the following double-end amplitude ratio distance measurement formula:
wherein, L represents that the total length of the line is 3000km;is a frequency f i The amplitude attenuation constant of the lower line mode voltage traveling wave; the above table (1) shows the line mode, and the subscript i shows the frequency f i The following steps of (1);
(9) Calculating an arithmetic average value of all fault distances in the step (8), wherein the arithmetic average value is the fault distance from the final distance A to the head end A, and the fault positioning is finished at this moment;
(10) Utilizing original line mode voltage traveling wave signal of B pointFinding out the Teager energy corresponding to the two traveling wave heads before reaching the point B by using a Teager energy operator method, and recording the value as E 1B And E 2B And the energy attenuation factor eta of the traveling wave Teager is calculated by the following two formulas 1B And η 2B ：
And η 2B ＝E 2B
Subscripts B, 1 and 2 respectively represent a point B, a first traveling wave head of the point B and a second traveling wave head of the point B;
(11) Eta obtained by the calculation of the step (10) 1B And η 2B And (3) introducing the following criteria to determine a method for accurately positioning the subsequent fault:
(a) If eta 1B >, 0.4% o and eta 2B &1100, determining the fault position by single-ended distance measurement by utilizing the traveling wave information of the near-end point B, and turning to the step (12);
(b) If eta 1B Less than or equal to 0.4 per thousand or eta 2B If the current value is less than or equal to 1100, determining the fault position by using traveling wave information of a near-end point B and a middle point C and adopting a double-end amplitude ratio method, and turning to the step (13);
(12) Calibrating the original line mode voltage traveling wave signal of the point B by using a Teager energy operator methodThe arrival time of the first two wave heads is respectively T1 and T2, and the distance x from the tail end B point fault is calculated by the following single-ended traveling wave distance measurement formula:
wherein v is the traveling wave velocity and takes the value of 2.95 multiplied by 10 8 m/s；
(13) Selecting the amplitudes corresponding to all signals of which the frequency components fall between 20kHz and 50kHz in the line mode voltage traveling wave head signals of the data windows with different lengths at the point B and the point C in the step (2), and solving the ratio of the amplitudes of the corresponding frequency components; for each amplitude ratio K BC And calculating a fault distance x from the tail end point B by the following double-end amplitude ratio distance measurement formula:
wherein, L represents that the total length of the line is 3000km;is a frequency f i The amplitude attenuation constant of the lower line mode voltage traveling wave; the above table (1) shows the line mode, and the subscript i shows the frequency f i The following steps.
(14) Calculating the arithmetic mean value of all fault distances in the step (13), wherein the arithmetic mean value is the fault distance of the final distance line model tail end B point; and then, the fault location is finished.
The various methods used in the present invention are as follows:
1. method for determining calculation data window
After the half-wavelength transmission line breaks down, voltage traveling waves generated by the fault point can be transmitted to measuring points at two ends along the line. Since the calculation process of the method takes the line mode voltage head signal as an object, a data window for calculating the line mode voltage traveling wave head signal needs to be determined, which has an important influence on the subsequent fault positioning step. The step of determining the signal data window is divided into two steps: firstly, roughly determining a sudden change point of a head wave of a traveling wave; secondly, the length of the signal data window is determined.
Because the db6 wavelet energy is most concentrated and has good effect on singular point detection, the invention adopts db6 wavelet for wavelet transformationAs the mother wavelet. The half-wavelength transmission line is long, and under the condition of extreme faults, high-frequency components of line mode voltage traveling waves are obviously attenuated, so that the reconstruction coefficient of a detail coefficient at a d1 layer of wavelet decomposition of the line mode voltage traveling waves at the far end of the faults is too small, the edge effect is obvious, and singular point detection results are interfered. In order to solve the problem, the following method is adopted to solve the problem: keeping higher sampling frequency (about 1 MHz), utilizing db6 wavelet to carry out 4-layer decomposition on original line mode voltage traveling wave signal, selecting a first-order edge smoothing mode, and reconstructing d 3 And (4) layer detail coefficients, and determining a mutation point by calculating a corresponding modulus maximum. The method is characterized in that the catastrophe point of the lower frequency component (about 62.5 kHz-125 kHz) of the head wave of the traveling wave is roughly identified, and the catastrophe point can be ensured to be free from the interference of the overlarge attenuation of the amplitude of the high frequency component of the traveling wave of the line mode voltage to a certain extent due to the slow attenuation of the lower frequency component.
After the abrupt change point of the line mode traveling wave signal is determined, the data of m points in front of the point and n points behind the point are selected as the data window of the initial wave head signal of the whole line mode voltage traveling wave for calculation by taking the abrupt change point as a reference. By PSCAD simulation and MATLAB calculation, the method can adapt to various conditions when m is 5. Since the variable data window frequency sweep method is adopted, n can take a plurality of values, and the specific values are shown in the variable data window frequency sweep method.
2. Method for extracting high-frequency component amplitude of line mode traveling wave
The invention adopts a module maximum value method to determine the element, and the core idea is as follows: (1) According to the extracted frequency (S transform decomposition scale), determining a corresponding row vector U in a complex matrix obtained by S transform ST . (2) Solving a complex vector U ST The maximum module value represents the amplitude of the corresponding frequency component of the original signal.
According to the above analysis, before extracting the amplitude of the high-frequency component of the original signal by using the S transform, it is necessary to determine the frequency of the extracted high-frequency component (alternatively referred to as the decomposition scale S) level ). The frequency should be selected to be steeper in the middle of the traveling wave attenuation coefficient versus frequency characteristic. According to the PSCAD simulation and MATLAB calculation results, the following results can be obtained: line mode voltage traveling wave first wave head signal intermediate frequencyThe signal component calculation result with the rate between 20kHz and 50kHz is more accurate, and the specific S transformation decomposition scale S level The values are found in the data window sweep method.
3. Variable data window frequency sweep method
The specific principle of the data sweep frequency method provided by the invention is as follows:
(1) Determination of the data window length: sequentially taking the values of n in section 1, 70,71,72, … and 160;
(2) S, transforming decomposition scale: 2 middle S transform decomposition scale S level Sequentially taking 1,2,3, … and 9;
(3) The data processing method comprises the following steps: firstly, after acquiring the original line mode voltage traveling wave signals of corresponding measurement points, determining line mode voltage traveling wave head signals with different data window lengths by using a method with 1 section according to the principle (1). Then, for the head wave signal of each specific data window length, respectively extracting the amplitude of the frequency component under the scale 1-11 and the frequency corresponding to each scale by using S transformation according to the principle (2), screening out the amplitude of the frequency component falling between 20 kHz-50 kHz, solving the amplitude ratio of the corresponding frequency components of two measuring points and the real part of the line mode traveling wave propagation constant of the line under the frequency, and substituting the real part into a formula to calculate the fault position. And finally, solving and calculating the arithmetic mean value of the fault positions, wherein the arithmetic mean value is the final fault distance.
Teager energy operator method
The Teager energy operator method provided by the invention specifically comprises the following steps:
(1) Acquiring an original line mode voltage traveling wave signal of a corresponding measuring point;
(2) Adopting db6 wavelet to make 4-layer wavelet decomposition of obtained signal and extracting d 3 Layer detail coefficients;
(3) Using the same mother wavelet pair d 3 And performing wavelet reconstruction on the layer detail coefficients to obtain corresponding reconstruction detail coefficients, and recording the reconstruction detail coefficients as: d r2 ＝[d r1 ,d r2 ,…,d rm ]＝d r [m]Wherein m is the length of the original line mode voltage traveling wave signal;
(4) The Teager energy vector for the reconstruction coefficient is calculated by substituting the following equation:
Ψ e [d r [m]]＝d r [m] 2 -d r [m-1]·d r [m+1]
in the vector Ψ e, the time corresponding to the maximum value element is the head arrival time T 1 The time corresponding to the second local maximum element is the second wave head arrival time T 2 。
Simulation verification
In order to verify the effectiveness and reliability of the invention, a half-wavelength power transmission line model is built on PSCAD/EMTDC, as shown in FIG. 1. A line model which accords with the frequency-dependent characteristic of an actual line model is adopted, wherein a triangular tower model is adopted for a half-wavelength power transmission line tower, and 8-split steel-cored aluminum stranded wires are adopted for the wires. The head end, the middle point and the tail end of the line are provided with voltage traveling wave measuring devices, and fault simulation is carried out under the influence of different fault types, fault distances, fault resistances and fault initial phase angle factors. According to the method herein, MATLAB is used to calculate relevant parameters and fault distances. The fault ranging error e is defined by:
in the above formula, X c For calculating the resulting distance to failure, X r For actual fault distance, L t And =3000km is the total length of the line. The results of the fault location calculation are shown in table 1 below. For reasons of space, table 1 only lists the results for the first half of the line at fault, and therefore the fault distances are all distances from the a point at the head end of the line. The actual simulation results of the fault location calculation of the second half section of the line and the results of the first half section of the line are almost symmetrically distributed. In the following table, RFL is the actual fault distance, FT is the fault type (Ag, ABg, ABCg, AB, ABC respectively represent A phase grounding, AB two phase grounding, ABC three phase grounding, AB two phase short circuit, ABC three phase short circuit fault), R f To fault resistance, θ f Is the initial phase angle of the fault.
TABLE 1 Fault location calculation results under different fault conditions
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (2)
1. A half-wavelength power transmission line asynchronous fault positioning method based on line mode voltage traveling wave amplitude attenuation characteristics is characterized in that: the method comprises the following steps:
(1) Respectively representing measurement points of the head end, the tail end and the middle point of the half-wavelength power transmission line by A, B and points C, and representing a fault point by F; after the half-wavelength transmission line has a fault, respectively extracting original voltage traveling wave signals of a head end point A, a tail end point B and a middle point C, then carrying out phase-mode conversion on the original voltage traveling wave signals to obtain original line-mode voltage traveling wave signals which are respectively recorded asWherein subscripts denote points a, B, and C, and superscript (1) denotes a line mode;
(2) Acquiring original line mode voltage traveling wave signals measured at the point A, the point B and the point CThe amplitudes of a plurality of signal components with different frequency components in head wave head signals with different data window lengths; at the same time, the following formula is used to obtain an arbitrary frequency f n Attenuation constant alpha of down-line mode voltage traveling wave amplitude n ：
Wherein Z is n ＝R n +jω n L and Y n ＝G n +jω n C is frequency f n Line mode impedance and admittance of the lower line; j is an imaginary unit; r n And G n Are respectively the frequency f n Line mode resistance and conductance of the lower line; l and C are respectively a power frequency line mode inductor and a capacitor of the circuit; omega n ＝2πf n Is the corresponding angular frequency; the subscript n representing all electrical quantities at frequency f n The following was obtained.
(3) The frequency of the line mode voltage traveling wave signal measured by the point A and the point B in the head wave head signal with the signal data window length of 82 is omega i Signal amplitude of =22.727kHzAndthe amplitude ratio K is calculated by substituting the following formula AB ：
Where x represents the distance variable and i represents the quantity at frequency ω i The following was obtained.
(4) Judgment of K AB And size of 1, determine failed segment: if K is AB &1, if the fault occurs on the first half section of the line, turning to the step (5); if K AB &1, if the fault occurs on the second half-section line, turning to the step 10; if K AB =1, fault occurrence at line midpoint;
(5) Travelling wave signal by using A point original line mode voltageFinding out the Teager energy corresponding to the two traveling wave heads before reaching the point A by using a Teager energy operator method, and recording the value as E 1A And E 2A And the energy attenuation factor eta of the traveling wave Teager is calculated by the following two formulas 1A And η 2A ：
And η 2A ＝E 2A
Subscripts A, 1 and 2 respectively represent a point A, a first traveling wave head of the point A and a second traveling wave head of the point A;
(6) Eta obtained by calculation in the step (5) 1A And η 2A And (3) introducing the following criteria to determine a method for accurately positioning the subsequent fault:
(a) If eta 1A >, 0.4% o and eta 2A &1100, determining the fault position by single-ended distance measurement by utilizing the traveling wave information of the near-end point A, and turning to the step (7);
(b) If eta 1A Less than or equal to 0.4 per thousand or eta 2A If the fault position is less than or equal to 1100, determining the fault position by using traveling wave information of a near-end point A and a middle point C and adopting a double-end amplitude ratio method, and turning to the step (8);
(7) Calibrating the original line mode voltage traveling wave signal of the point A by using a Teager energy operator methodThe arrival time of the first two wave heads is respectively T1 and T2, and the fault distance x from the head end A point is calculated by the following single-ended traveling wave distance measurement formula:
wherein v is the traveling wave velocity and takes the value of 2.95 multiplied by 10 8 m/s；
(8) Selecting the amplitudes corresponding to all signals of which the frequency components fall between 20kHz and 50kHz in the line mode voltage traveling wave head signals of the data windows with different lengths at the point A and the point C in the step (2), and solving the ratio of the amplitudes of the corresponding frequency components; for each amplitude ratio K AC The double-end amplitude ratio distance measurement formula is substituted to calculate oneIndividual fault distance x from head end a:
in the above formula, L represents the total line length;is a frequency f i The amplitude attenuation constant of the lower line mode voltage traveling wave; the above table (1) shows the line mode, and the subscript i shows the frequency f i The following steps of (1);
(9) Calculating the arithmetic mean value of all fault distances in the step (8), wherein the arithmetic mean value is the fault distance from the final A point to the head end, and the fault positioning is finished at this moment;
(10) Utilizing original line mode voltage traveling wave signal of B pointFinding out the Teager energy corresponding to the two traveling wave heads before reaching the point B by using a Teager energy operator method, and recording the value as E 1B And E 2B And the energy attenuation factor eta of the traveling wave Teager is calculated by the following two formulas 1B And η 2B ：
And η 2B ＝E 2B
In the formula, subscripts B, 1 and 2 respectively represent a point B, a first traveling wave head of the point B and a second traveling wave head of the point B;
(11) Eta obtained by the calculation of the step (10) 1B And η 2B And (3) introducing the following criteria to determine a method for accurately positioning the subsequent fault:
(a) If eta 1B >, 0.4% o and eta 2B &1100, determining the fault position by using the traveling wave information of the near-end point B and adopting single-end distance measurement, and turning to the step (12);
(b) If eta 1B Less than or equal to 0.4 per thousand or eta 2B 1100 or less, the proximal B point is usedAnd the traveling wave information of the midpoint C point, determining the fault position by adopting a double-end amplitude ratio method, and turning to the step (13);
(12) Calibrating the original line mode voltage traveling wave signal of the point B by using a Teager energy operator methodThe arrival time of the first two wave heads is respectively T1 and T2, and the distance x from the tail end B point fault is calculated by the following single-ended traveling wave distance measurement formula:
wherein v is the traveling wave velocity and takes the value of 2.95 multiplied by 10 8 m/s；
(13) Selecting the amplitudes corresponding to all signals of which the frequency components fall between 20kHz and 50kHz in the line mode voltage traveling wave head signals of the data windows with different lengths at the point B and the point C in the step (2), and solving the ratio of the amplitudes of the corresponding frequency components; for each amplitude ratio K BC And calculating a fault distance x from the tail end point B by the following double-end amplitude ratio distance measurement formula:
wherein, L represents the total line length;is a frequency f i The amplitude attenuation constant of the lower line mode voltage traveling wave; the above table (1) shows the line mode, and the subscript i shows the frequency f i The following steps.
(14) Calculating the arithmetic mean value of all fault distances in the step (13), wherein the arithmetic mean value is the fault distance of the final distance line model tail end B point; and then, the fault location is finished.
2. The half-wavelength transmission line based on line-mode voltage traveling wave amplitude attenuation characteristics of claim 1The road asynchronous fault positioning method is characterized by comprising the following steps: in the step (2), each original linear mode voltage traveling wave signal measured at the point A, the point B and the point C is obtained according to a calculation data window determination method, a linear mode traveling wave high-frequency component amplitude extraction method and a variable data window frequency sweep methodThe amplitudes of the signal components of a plurality of different frequency components in the head signal of different data window lengths.
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