CN112255497A - Fault line selection method based on fundamental frequency correlation and maximum correlation distance - Google Patents

Fault line selection method based on fundamental frequency correlation and maximum correlation distance Download PDF

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CN112255497A
CN112255497A CN202010948048.0A CN202010948048A CN112255497A CN 112255497 A CN112255497 A CN 112255497A CN 202010948048 A CN202010948048 A CN 202010948048A CN 112255497 A CN112255497 A CN 112255497A
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fundamental frequency
feeder
fault
line
correlation
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王晓卫
魏向向
高杰
梁振锋
党建
贾嵘
张惠智
王开艳
王艳婷
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Xian University of 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
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • 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
    • 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
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults

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Abstract

The invention relates to a fault line selection method based on fundamental frequency correlation and maximum correlation distance, which is implemented according to the following steps: step 1, acquiring and calculating zero sequence current of each feeder line, calculating a fundamental frequency component phase in the zero sequence current by utilizing a Fourier algorithm and calculating a phase difference; and 2, judging the single-phase earth fault feeder of the power distribution network according to the phase difference to obtain a fault line. When the single-phase earth fault feeder of the power distribution network is judged, when the single-phase earth fault occurs, the phase difference of fundamental frequency components of zero-sequence current is judged firstly, and if the difference value is smaller, a fault line selection criterion based on the correlation of the fundamental frequency components is provided; if the difference value is large, the first half-wave polarity of the free oscillation component is combined, the free oscillation component is rearranged, and a fault line selection criterion based on the improved association distance is provided.

Description

Fault line selection method based on fundamental frequency correlation and maximum correlation distance
Technical Field
The invention belongs to the technical field of power distribution network relay protection of a power system, and particularly relates to a fault line selection method based on fundamental frequency correlation and maximum correlation distance.
Background
Among the power system ground faults, single-phase ground faults account for more than 80% of all fault types, so power system fault detection is an important means for maintaining safe, reliable and stable operation of a power grid. The operation mode that the neutral point is grounded through the arc suppression coil is widely applied to medium and low voltage distribution systems (10kV, 35kV, 66kV and the like). For the power grid with the operation mode, when a single-phase earth fault occurs, the fault current amplitude is small, and the fault characteristic is weak due to the compensation effect of the arc suppression coil. In recent years, many techniques and articles about faulty line selection are published successively, but due to the severe field environment, there are many difficulties and limitations in the applicability of the existing line selection method.
The existing line selection method can be mainly divided into a steady state method, an artificial injection method and a transient state method, wherein the steady state method mainly comprises the following steps: amplitude-to-amplitude phase comparison method, harmonic wave method, etc., and the steady state method mainly utilizes the amplitude or phase difference of fault voltage or current to realize line selection. The power distribution network fault line selection method based on manual injection realizes line selection by detecting specific current signals manually injected. The line selection method based on the steady state method and the manual injection method is convenient to realize and simple in principle.
In order to fully utilize the abundant transient information in the transient zero-sequence current of the fault instant and improve the timeliness and accuracy of line selection, a line selection method based on the transient information becomes the mainstream of research, such as an energy method, a correlation analysis method, a wavelet analysis method, an S transformation method, a Hilbert-Huang transformation method, a clustering method and the like.
The steady-state method and the manual injection method are easily affected by factors such as a system operation mode, the capacity of a current transformer, external interference and the like, and under the condition of a high-resistance grounding fault, the accuracy rate of a line selection result is low, and the reliability is low. Although the accuracy of the line selection principle of the existing transient line selection method is improved, the line selection process is complex and takes long time, the method is accompanied with a modern signal processing algorithm or an intelligent algorithm, the obtained result is often high in randomness, and the method is limited in the practical application process. For the clustering method, enough fault line samples need to be collected, the time consumption is long, the fault randomness is high, sufficient sample data cannot be collected, and the actual application effect is not ideal.
The line selection accuracy is high when the low-resistance earth fault occurs, but when the high-resistance earth fault occurs, the line selection method only depending on the transient quantity is limited in applicability due to weak fault characteristics and quick disappearance. Therefore, when a single-phase earth fault occurs, if steady-state and transient-state information under the fault condition is reasonably utilized, the accuracy of the line selection method is certainly improved, and the applicability of the line selection method is increased.
According to the above discussion, the existing fault line selection method is not high in accuracy, or complex in calculation process, and long in line selection time.
Disclosure of Invention
The invention aims to provide a fault line selection method based on fundamental frequency correlation and maximum correlation distance, which can improve the accuracy of fault line selection by fully utilizing the steady-state and transient-state information of fault zero-sequence current.
The technical scheme adopted by the invention is that a fault line selection method based on fundamental frequency correlation and maximum correlation distance is implemented according to the following steps:
step 1, acquiring and calculating zero sequence current of each feeder line, calculating a fundamental frequency component phase in the zero sequence current by utilizing a Fourier algorithm and calculating a phase difference;
and 2, judging the single-phase earth fault feeder of the power distribution network according to the phase difference to obtain a fault line.
The invention is also characterized in that:
the specific process of the step 1 is as follows: collecting the zero sequence current of each feeder line, calculating the zero sequence current of each feeder line in the 2 nd power frequency period after the single-phase earth fault occurs by adopting a Fourier algorithm, and obtaining the fundamental frequency component i of the zero sequence current of each feeder lineq(N), q is a feeder number, q is 1, 2, …, p, j, …, m, N is the number of sampling points, N is 1, 2, …, N, wherein the fundamental frequency component i isqThe phase of (n) is thetaq(ii) a Calculating the absolute value of the phase difference | theta of the zero sequence current fundamental frequency components of any two feeder linespj|，|θpj|＝|θp-θjL, wherein θpIs the phase of the fundamental component of the feed line p, thetajIs the phase of the fundamental frequency component of feed j.
The specific process of the step 2 is as follows: and judging the magnitude relation between the absolute value of the phase difference and pi/4:
if thetapjIf | > pi/4, adopting a fault line selection criterion based on the similarity of fundamental frequency components to judge a fault line;
if thetapjIf the | is less than pi/4, judging the fault line by adopting a fault line selection criterion based on the improved correlation distance.
The specific process of judging the fault line by the fault line selection criterion based on the similarity of the fundamental frequency components is as follows:
calculating the cross-correlation coefficient rho of the fundamental frequency component of each feeder linepjThe specific calculation formula is as follows:
Figure BDA0002675975890000031
by cross-correlation coefficient ρpjForming a matrix of correlation coefficients ρpjThe following are:
Figure BDA0002675975890000032
wherein m represents the total number of feeders;
reject matrix ρpjMaximum and minimum of the j-th row elementValue and calculating the comprehensive correlation coefficient rho of each feeder linejThe calculation formula is as follows:
Figure BDA0002675975890000041
where ρ isj＝[ρ1 ρ2 … ρm]；
Will rhojMinimum mean value ρj minAnd the corresponding feeder line is judged as a fault feeder line, and other feeder lines are judged as sound feeder lines.
The specific process of judging the fault line based on the fault line selection criterion of the improved correlation distance is as follows:
taking any feeder j as an example, calculating the free oscillation component Z of the feeder jj(n)；
According to free-running component Zj(n) first half-wave extreme positive and negative, and Zj(n) rearranging to obtain an arranged component Sj(n)；
Similarly, a second feeder p is selected, S is obtained after the feeders p are rearrangedp(n) Process and Sj(n) the same method;
calculating the correlation distance D of any two feeder linespjThe calculation formula is as follows:
Figure BDA0002675975890000042
removing DpjThe maximum value and the minimum value in the feed line j are calculated, and the improved correlation distance of the feed line j is calculated
Figure BDA0002675975890000043
The calculation formula is as follows:
Figure BDA0002675975890000044
will be provided with
Figure BDA0002675975890000045
Maximum value of
Figure BDA0002675975890000046
And the corresponding feeder line is judged as a fault feeder line, and other feeder lines are judged as sound feeder lines.
Calculating the free-running component Z of the feed line iiThe (n) specific method comprises the following steps: subtracting the fundamental frequency component of the zero sequence current of the feeder line i from the zero sequence current of the feeder line i to obtain the free oscillation component Z of the feeder line ii(n)。
Will Zi(n) the rearrangement rule is: if first half wave extreme value mujIf Z is greater than or equal to 0, thenjThe numerical values of (n) are arranged from large to small in sequence; if first half wave extreme value mujIf < 0, then Z isjThe numerical values of (n) are arranged from small to large in sequence as follows:
when mu isjWhen the value is more than or equal to 0, the arrangement result is as follows:
Sj(n)＝Zj(1)≥Zj(2)≥Zj(3)，…，Zj(n)
when mu isjWhen < 0, the alignment results are as follows:
Sj(n)＝Zj(1)≤Zj(2)≤Zj(3)，…，Zj(n)。
the invention has the beneficial effects that:
the invention relates to a fault line selection method based on fundamental frequency correlation and maximum correlation distance, when a single-phase earth fault occurs, firstly, judging the phase difference of fundamental frequency components of zero-sequence current, and if the difference value is smaller, providing a fault line selection criterion based on the fundamental frequency component correlation; if the difference value is large, the first half-wave polarity of the free oscillation component is combined, the free oscillation component is rearranged, and a fault line selection criterion based on the improved association distance is provided.
Drawings
Fig. 1 is a zero sequence current distribution diagram of 4 feeders of a certain distribution network adopted by the invention;
FIG. 2 is a schematic diagram of the present invention after extracting fundamental frequency component signals by Fourier analysis of the current shown in FIG. 1;
FIG. 3 is a schematic diagram of free oscillation components of the current feeds of FIG. 1 in accordance with the present invention;
fig. 4 is a simulation model of a 10kV power distribution network according to an embodiment of the present invention;
fig. 5 shows the fundamental frequency component signals of the feeders according to the embodiment of the present invention;
FIG. 6 shows free oscillation components of the feeders according to the embodiment of the present invention;
fig. 7 shows the free oscillation components of the feeders after rearrangement according to the embodiment of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention relates to a fault line selection method based on fundamental frequency correlation and maximum correlation distance, which is implemented according to the following steps:
step 1, collecting zero sequence current of each feeder line, calculating a fundamental frequency component phase in the zero sequence current by utilizing a Fourier algorithm and calculating a phase difference; the specific process is as follows: collecting three-phase current in a line, obtaining zero-sequence current according to the three-phase current, calculating the zero-sequence current of each feeder line in the 2 nd power frequency period after single-phase earth fault occurs by adopting a Fourier algorithm, and obtaining a fundamental frequency component i of the zero-sequence current of each feeder lineq(N), q is a feeder number, q is 1, 2, …, p, j, …, m, N is the number of sampling points, N is 1, 2, …, N, wherein the fundamental frequency component i isqThe phase of (n) is thetaq(ii) a Calculating the absolute value of the phase difference | theta of the zero sequence current fundamental frequency components of any two feeder linespj|，|θpj|＝|θp-θjL, wherein θpIs the phase of the fundamental component of the feed line p, thetajIs the phase of the fundamental frequency component of feed j.
Step 2, judging a single-phase earth fault feeder of the power distribution network according to the phase difference to obtain a fault line; the specific process is as follows: and judging the magnitude relation between the absolute value of the phase difference and pi/4:
if thetapjIf | ≧ pi/4, the method based on the similarity of fundamental frequency components is adoptedFault line is judged according to fault line selection criteria; the specific process is as follows:
calculating the cross-correlation coefficient rho of the fundamental frequency component of each feeder linepjThe specific calculation formula is as follows:
Figure BDA0002675975890000061
by cross-correlation coefficient ρpjForming a matrix of correlation coefficients ρpjThe following are:
Figure BDA0002675975890000071
wherein m represents the total number of feeders;
reject matrix ρpjThe maximum value and the minimum value of the jth row of elements in the middle are calculated, and the comprehensive correlation coefficient rho of each feeder line is calculatedjThe calculation formula is as follows:
Figure BDA0002675975890000072
where ρ isj＝[ρ1 ρ2 … ρm]；
Will rhojMinimum mean value ρj minAnd the corresponding feeder line is judged as a fault feeder line, and other feeder lines are judged as sound feeder lines.
If thetapjIf the | is less than pi/4, judging a fault line by adopting a fault line selection criterion based on the improved correlation distance, and realizing the amplification of the difference between a fault feeder line and a healthy feeder line by rearranging free oscillation components in zero-sequence currents of all feeder lines according to a criterion strategy; the specific process is as follows:
taking any feeder j as an example, calculating the free oscillation component Z of the feeder jj(n), the specific method comprises the following steps: subtracting the fundamental frequency component of the zero sequence current of the feeder line i from the zero sequence current of the feeder line i to obtain the free oscillation component Z of the feeder line ii(n)；
According to free-running component ZjPositive and negative conditions of first half-wave extreme value of (n)In the condition that Z isj(n) rearranging to obtain an arranged component Sj(n) the arrangement rule is: if first half wave extreme value mujIf Z is greater than or equal to 0, thenjThe numerical values of (n) are arranged from large to small in sequence; if first half wave extreme value mujIf < 0, then Z isjThe numerical values of (n) are arranged from small to large in sequence as follows:
when mu isjWhen the value is more than or equal to 0, the arrangement result is as follows:
Sj(n)＝Zj(1)≥Zj(2)≥Zj(3)，…，Zj(n)
when mu isjWhen < 0, the alignment results are as follows:
Sj(n)＝Zj(1)≤Zj(2)≤Zj(3)，…，Zj(n)；
similarly, a second feeder p is selected, S is obtained after the feeders p are rearrangedp(n) Process and Sj(n) the same method;
calculating the correlation distance D of any two feeder linespjThe calculation formula is as follows:
Figure BDA0002675975890000081
removing DpjThe maximum value and the minimum value in the feed line j are calculated, and the improved correlation distance of the feed line j is calculated
Figure BDA0002675975890000086
The calculation formula is as follows:
Figure BDA0002675975890000082
will be provided with
Figure BDA0002675975890000083
Maximum value of
Figure BDA0002675975890000084
The corresponding feeder line is judged as a fault feeder line, and other feeder lines are judgedThe line is a sound feeder line.
The invention relates to a fault line selection method based on fundamental frequency correlation and maximum correlation distance, which has the working principle that:
1. fourier analysis
Extracting by adopting a Fourier algorithm, specifically: and extracting the power frequency signal of the 2 nd period after the single-phase earth fault, and inverting the power frequency signal in the 1 st period at the fault occurrence moment.
Assuming that the zero sequence current i (t) satisfies the dirichlet condition, i.e.:
Figure BDA0002675975890000085
it is well known that the fourier transform exists and is defined as:
Figure BDA0002675975890000091
the inverse transformation is as follows:
Figure BDA0002675975890000092
2. effectiveness analysis for extracting fundamental frequency component of zero-sequence current by Fourier analysis
In order to verify the effectiveness of the fourier algorithm in extracting the fundamental frequency component from the zero-sequence current, taking the zero-sequence current of a certain power distribution network as an example, as shown in fig. 1, (the power distribution network contains 4 feeder lines), and extracting the fundamental frequency component by using the fourier algorithm.
Intercepting the current data of 0.02 s-0.04 s, and utilizing Fourier analysis fitting to obtain a power frequency result as shown in the following formula:
Figure BDA0002675975890000093
the formula is extended to the first 1 period (0-0.02 s), and the final result is shown in fig. 2:
as can be seen from fig. 2, the fundamental frequency component signal obtained by fourier analysis can be well fitted to the power frequency component in the actual zero sequence current; further, in order to obtain the high-frequency free oscillation component in the zero-sequence current of each feeder line, the fundamental frequency component may be subtracted from the original zero-sequence current, and the obtained free oscillation components of the zero-sequence currents of 4 feeder lines are shown in fig. 3:
as can be seen from fig. 3, by removing the fundamental frequency component information in the zero-sequence current of each feeder line, the free oscillation component in the zero-sequence current of each feeder line can be accurately obtained, and further, the acquisition of the free oscillation component lays a foundation for the construction of the next fault line selection criterion.
3. Fault line selection method based on fundamental frequency correlation and maximum correlation distance
The fundamental frequency phase of the sound lines is only related to the earth capacitance of the lines, and the fundamental frequency phase between the sound lines is not greatly different. The fundamental frequency phase of the fault line is related to the sum of the earth capacitance of all lines, the inductance of the arc suppression coil, the grounding resistance and other factors, and the initial phase difference between the healthy line and the fault line is larger.
A great deal of simulation and actual measurement data of the existing literature shows that the phase difference of the fundamental frequency components among the feeders
Figure BDA0002675975890000101
The threshold value of 45 degrees can meet the requirement of fault line selection accuracy, namely when the phase difference of the fundamental frequency components of the two signals
Figure BDA0002675975890000102
When the phase difference is large, the similarity between two signals on the surface is poor, and when the phase difference is large, the similarity between the two signals on the surface is poor
Figure BDA0002675975890000103
When the two signals are close to each other, the phase difference between the two signals is considered to be close.
In summary, by calculating the phase difference between the zero sequence current fundamental frequency components of each feeder line, if the phase difference is large, the fault feeder line can be determined by solving the correlation coefficient between the fundamental frequency components of each feeder line, and thus, a fault line selection criterion using the similarity of the fundamental frequency components is provided.
Examples
Establishing a 10kV power distribution network simulation model shown in the figure 4 by utilizing ATP-EMTP, wherein an arc suppression coil: the operation is carried out by adopting an overcompensation mode, the overcompensation degree is 10 percent, and the inductance of the arc suppression coil is LNThe resistance value was calculated to be 40.2517 Ω, taking 10% of the reactance value, 1.2819H. Loading: uniformly using delta connection, ZL400+ j20 Ω. Sampling frequency fs＝105Hz, the single-phase earth fault occurs in 0.02s, and the simulation time length is 0.04 s.
The fault line selection criterion test based on the correlation of the fundamental frequency signals: taking the case of a fault occurring in the line 1, the initial fault phase angle β is 90 °, the fault location is 10km away from the bus, and the ground resistance is 100 Ω. Because the transient zero-sequence current at the moment is attenuated quickly, i can be selected0jThe signal in 0.02 s-0.04 s time is similar to the fundamental frequency component signal, and the result is shown in fig. 5.
As can be seen from fig. 5, the fundamental frequency waveform of each robust line has a high similarity with the original fundamental frequency waveform. The reconstructed fundamental frequency signal is analyzed by Fourier to obtain the frequency, amplitude and phase of the fundamental frequency signal i of each lineqThe expression of (a) is as follows:
Figure BDA0002675975890000111
the phases of the fitted fundamental frequency component signals of the healthy line are-31.29 degrees, -31.4 degrees, -31.51 degrees respectively, the periods are close, and the phase angle of the fundamental frequency signal of the fault line is 29.44 degrees. The maximum value of the absolute value of the phase angle difference between fundamental frequency signals of a sound line and a fault line is-31.29-29.44 degrees, 60.73 degrees is larger than 45 degrees, so that the cross-correlation coefficient of the fundamental frequency signals of each line can be calculated by utilizing a fault line selection criterion based on the similarity of fundamental frequency components, and the result is shown in table 1.
TABLE 1 values of cross-correlation coefficient between feeds
Figure BDA0002675975890000112
As can be seen from table 1, the overall correlation coefficient ρ of each line can be obtainedj＝[0.4881 1 1 1]. Comprehensive correlation coefficient rho of fault line selection criterion based on similarity of fundamental frequency components10.4881, the feeder line is the smallest, therefore, the feeder line 1 is judged to be the fault feeder line according to the fault line selection criterion based on the similarity of the fundamental frequency components, and the judgment result is accurate.
When the phase difference of the fundamental frequency of each line is small, the fault line can be accurately judged by using the fault line selection criterion based on the similarity of the fundamental frequency components. However, when the phase difference between the fault line and the healthy line is large, the fault line selection criterion condition based on the similarity of the fundamental frequency components cannot be met, and the fault line selection criterion flow based on the improved correlation distance is automatically entered.
And (3) fault line selection criterion test based on improved correlation distance: taking the single-phase earth fault of the feeder line 3 as an example, the initial fault phase angle β is 0 °, the fault position is 5km away from the bus, and the ground resistance is 100 Ω, and the fundamental frequency signal expression of each line is obtained by fourier analysis as follows:
Figure BDA0002675975890000121
analysis shows that the fundamental frequency phases of the healthy lines 1, 2 and 4 are-119.82 degrees, -119.84 degrees and-120 degrees respectively, and the fundamental frequency phase of the fault line 3 is-103.79 degrees. And calculating the absolute value of the phase angle difference between the healthy line and the fault line, and obtaining the maximum value of the absolute value of | -120 ° +103.79 ° | < 45 °, wherein the fault line selection criterion based on the similarity of the fundamental frequency components is not satisfied.
And obtaining a fundamental frequency component signal of 0.02 s-0.04 s by adopting a Fourier algorithm, and then reversely prolonging to ensure that the time of the power frequency signal is 0.04 s. Calculating free oscillation component Z of each linej(n), the results are shown in FIG. 6.
As can be seen from fig. 6, the free oscillation component Z of each line in a short timej(n) decays rapidly to 0, and Zj(n) almost no periodic sinusoidal signal. The transient zero sequence currents of the healthy line and the fault line flow in opposite directions, and this feature is shown in fig. 6 as the polarities of the first half waves of the free oscillation components of the fault line and the healthy line are opposite. Based on this, willFree oscillation component Z of each linej(n) rearrangement according to the fault route selection criterion based on the improved correlation distance, the result is as shown in fig. 7.
As can be seen from FIG. 7, S after rearrangementj(n) the difference between the fault line and the healthy line is increased, namely the S of the fault line and the healthy linej(n) the correlation distance between (n) is generally greater than the healthy line Sj(n) and finally, obtaining the improved correlation distance result of each line, as shown in table 2.
TABLE 2 improved correlation distance calculation for each feeder
Figure BDA0002675975890000122
As can be seen from Table 2, for the column vector D3j(j ≠ 3) where the value of each element is greater than the values of the other elements in the row in which the element is located, indicating that the improved correlation distance between the faulted line and the healthy line is generally greater than the improved correlation distance between the healthy lines. Thus, the improved association distance of each line can be obtained
Figure BDA0002675975890000131
Figure BDA0002675975890000132
Due to the existence of
Figure BDA0002675975890000133
Finally, the line 3 is judged as a fault line, and the judgment result is accurate.
According to the mode, the fault line selection method based on the fundamental frequency correlation and the maximum correlation distance is characterized in that when a single-phase earth fault occurs, the phase difference of the fundamental frequency components of zero-sequence current is judged firstly, and if the difference value is smaller, a fault line selection criterion based on the fundamental frequency component correlation is provided; if the difference value is large, the first half-wave polarity of the free oscillation component is combined, the free oscillation component is rearranged, and a fault line selection criterion based on the improved association distance is provided.

Claims (7)

1. A fault line selection method based on fundamental frequency correlation and maximum correlation distance is characterized by being implemented according to the following steps:
step 1, collecting zero sequence current of each feeder line, calculating a fundamental frequency component phase in the zero sequence current by utilizing a Fourier algorithm and calculating a phase difference;
and 2, judging the single-phase earth fault feeder of the power distribution network according to the phase difference to obtain a fault line.
2. The fault line selection method based on the fundamental frequency correlation and the maximum correlation distance as claimed in claim 1, wherein the specific process of step 1 is as follows: collecting the zero sequence current of each feeder line, calculating the zero sequence current of each feeder line in the 2 nd power frequency period after the single-phase earth fault occurs by adopting a Fourier algorithm, and obtaining the fundamental frequency component i of the zero sequence current of each feeder lineq(N), q is a feeder number, q is 1, 2, …, p, j, …, m, N is the number of sampling points, N is 1, 2, …, N, wherein the fundamental frequency component i isqThe phase of (n) is thetaq(ii) a Calculating the absolute value of the phase difference | theta of the zero sequence current fundamental frequency components of any two feeder linespj|，|θpj|＝|θp-θjL, wherein θpIs the phase of the fundamental component of the feed line p, thetajIs the phase of the fundamental frequency component of feed j.
3. The fault line selection method based on the fundamental frequency correlation and the maximum correlation distance as claimed in claim 1, wherein the step 2 comprises the following specific processes: and judging the magnitude relation between the absolute value of the phase difference and pi/4:
if thetapjIf | > pi/4, adopting a fault line selection criterion based on the similarity of fundamental frequency components to judge a fault line;
if thetapjIf the | is less than pi/4, judging the fault line by adopting a fault line selection criterion based on the improved correlation distance.
4. The fault line selection method based on fundamental frequency correlation and maximum correlation distance as claimed in claim 3, wherein the fault line selection criterion based on fundamental frequency component similarity is to determine a fault line by:
calculating the cross-correlation coefficient rho of the fundamental frequency component of each feeder linepjThe specific calculation formula is as follows:
Figure FDA0002675975880000021
by cross-correlation coefficient ρpjForming a matrix of correlation coefficients ρpjThe following are:
Figure FDA0002675975880000022
wherein m represents the total number of feeders;
reject matrix ρpjThe maximum value and the minimum value of the jth row of elements in the middle are calculated, and the comprehensive correlation coefficient rho of each feeder line is calculatedjThe calculation formula is as follows:
Figure FDA0002675975880000023
where ρ isj＝[ρ1 ρ2 … ρm]；
Will rhojMinimum mean value ρjminAnd the corresponding feeder line is judged as a fault feeder line, and other feeder lines are judged as sound feeder lines.
5. The fault line selection method based on the fundamental frequency correlation and the maximum correlation distance as claimed in claim 3, wherein the fault line selection criterion based on the improved correlation distance is to determine the fault line by:
taking any feeder j as an example, calculating the free oscillation component Z of the feeder jj(n)；
According to freeOscillation component Zj(n) first half-wave extreme positive and negative, and Zj(n) rearranging to obtain an arranged component Sj(n)；
Similarly, a second feeder p is selected, S is obtained after the feeders p are rearrangedp(n) Process and Sj(n) the same method;
calculating the correlation distance D of any two feeder linespjThe calculation formula is as follows:
Figure FDA0002675975880000031
removing DpjThe maximum value and the minimum value in the feed line j are calculated, and the improved correlation distance of the feed line j is calculated
Figure FDA0002675975880000035
The calculation formula is as follows:
Figure FDA0002675975880000032
will be provided with
Figure FDA0002675975880000033
Maximum value of
Figure FDA0002675975880000034
And the corresponding feeder line is judged as a fault feeder line, and other feeder lines are judged as sound feeder lines.
6. The fault line selection method based on fundamental frequency correlation and maximum correlation distance as claimed in claim 5, characterized in that the free oscillation component Z of the feeder line i is calculatediThe (n) specific method comprises the following steps: subtracting the fundamental frequency component of the zero sequence current of the feeder line i from the zero sequence current of the feeder line i to obtain the free oscillation component Z of the feeder line ii(n)。
7. A method according to claim 5 based on correlation of fundamental frequenciesAnd a maximum correlation distance fault line selection method, characterized in that Z is selectedi(n) the rearrangement rule is: if first half wave extreme value mujIf Z is greater than or equal to 0, thenjThe numerical values of (n) are arranged from large to small in sequence; if first half wave extreme value mujIf < 0, then Z isjThe numerical values of (n) are arranged from small to large in sequence as follows:
when mu isjWhen the value is more than or equal to 0, the arrangement result is as follows:
Sj(n)＝Zj(1)≥Zj(2)≥Zj(3)，…，Zj(n)
when mu isjWhen < 0, the alignment results are as follows:
Sj(n)＝Zj(1)≤Zj(2)≤Zj(3)，…，Zj(n)。
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113092934A (en) * 2021-03-23 2021-07-09 武汉大学 Single-phase earth fault judgment method and system based on clustering and LSTM
CN114779016A (en) * 2022-05-07 2022-07-22 四川大学 Repetitive transient fault identification method based on improved DTW

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103675605A (en) * 2013-12-11 2014-03-26 湖南大学 Small-current earth fault line selection method based on fault signal transient state correlation analysis
CN108663599A (en) * 2018-05-07 2018-10-16 太原理工大学 Fault line selection method for single-phase-to-ground fault based on transient high-frequency component correlation analysis
CN110542821A (en) * 2019-08-30 2019-12-06 江苏莱尔曼电气科技有限公司 Small current line selection method using correlation analysis

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103675605A (en) * 2013-12-11 2014-03-26 湖南大学 Small-current earth fault line selection method based on fault signal transient state correlation analysis
CN108663599A (en) * 2018-05-07 2018-10-16 太原理工大学 Fault line selection method for single-phase-to-ground fault based on transient high-frequency component correlation analysis
CN110542821A (en) * 2019-08-30 2019-12-06 江苏莱尔曼电气科技有限公司 Small current line selection method using correlation analysis

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WANGXIAOWEI 等: "Fault feeder detection method utilized steady state and transient components based on FFT backstepping in distribution networks", 《INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113092934A (en) * 2021-03-23 2021-07-09 武汉大学 Single-phase earth fault judgment method and system based on clustering and LSTM
CN113092934B (en) * 2021-03-23 2022-05-13 武汉大学 Single-phase earth fault judgment method and system based on clustering and LSTM
CN114779016A (en) * 2022-05-07 2022-07-22 四川大学 Repetitive transient fault identification method based on improved DTW

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