CN111521910A - Multi-end line fault positioning method and system based on wavelet transformation - Google Patents

Multi-end line fault positioning method and system based on wavelet transformation Download PDF

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CN111521910A
CN111521910A CN202010372741.8A CN202010372741A CN111521910A CN 111521910 A CN111521910 A CN 111521910A CN 202010372741 A CN202010372741 A CN 202010372741A CN 111521910 A CN111521910 A CN 111521910A
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fault
branch
transmission line
point
power transmission
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崔超奇
刘斌
董苏
安玲
程亚航
郭运泽
朱杰
胡慧敏
王蕊
刁哲伟
张剑东
卢家奎
杨海龙
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State Grid Corp of China SGCC
Fuyang Power Supply Co of State Grid Anhui Electric Power Co Ltd
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State Grid Corp of China SGCC
Fuyang Power Supply Co of State Grid Anhui Electric Power Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing
    • 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

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  • Engineering & Computer Science (AREA)
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Abstract

The invention discloses a multi-terminal line fault positioning method and a system based on wavelet transformation, wherein the method comprises the steps of monitoring a detected power transmission line, uploading monitored signal information to a data acquisition card, carrying out A/D conversion on the acquired signal information by the data acquisition card, and then synchronously transmitting the signal information to a main control computer, and storing sampling information by the main control computer; carrying out phase-mode conversion processing on the signal information; determining the time when the fault initial wave reaches a measuring point; and constructing a multi-end power transmission line fault branch judgment matrix, and finding out a fault branch through the multi-end power transmission line fault branch judgment matrix. The invention effectively solves the practical problems that the existing fault location method can not identify the branch where the fault is located, the location precision is low and the method is easily influenced by various factors.

Description

Multi-end line fault positioning method and system based on wavelet transformation
Technical Field
The invention relates to the technical field of power transmission line fault diagnosis, in particular to a multi-end line fault positioning method and system based on wavelet transformation.
Background
Accurate and quick power transmission line fault location has important significance for timely power transmission recovery of a line after a fault. The existing fault location methods are mainly directed to two-terminal lines, and some transmission systems (especially in secondary transmission networks) have more three-terminal or multi-terminal lines. Therefore, the method for accurately and quickly positioning the faults of the multi-end power transmission line has practical significance.
The fault location of the multi-end transmission line is difficult to be large relative to a double-end line, and for the fault location of the multi-end transmission line, a fault branch can be found out only after a fault branch is found, and an accurate method is not provided. At present, a method for positioning faults of a multi-end power transmission line is mainly an impedance method. The impedance method is characterized in that a fault location equation is written by using known system parameters and a steady-state power frequency quantity sequence after fault, the position of a fault point is obtained by solving the equation, and the system impedance and the line parameters are changed due to the change of the operation mode and the frequency.
Disclosure of Invention
The invention provides a multi-end line fault positioning method and system based on wavelet transformation, and aims to provide a fault branch judgment matrix of a new index for judging a multi-end line fault branch.
In one aspect, the present invention provides a multi-end line fault location method based on wavelet transform, which includes:
monitoring a detected power transmission line, uploading signal information obtained by monitoring to a data acquisition card, carrying out A/D conversion on the acquired signal information by the data acquisition card, and then synchronously transmitting the signal information to a main control computer, wherein the main control computer stores sampling information of the acquired signal information;
carrying out phase-mode conversion processing on the signal information;
determining the time when the initial fault wave reaches the measuring point by using wavelet transformation;
constructing a multi-end power transmission line fault branch judgment matrix, and finding out a fault branch through the multi-end power transmission line fault branch judgment matrix;
calculating the position of a fault point by utilizing a double-end traveling wave distance measurement principle;
and the main control computer synchronously outputs the judgment result of the fault branch and the position calculation result of the fault point.
In another aspect, the present invention provides a multi-terminal line fault location system based on wavelet transform, which includes:
the signal monitoring module is used for monitoring the detected power transmission line and uploading monitored signal information to the data acquisition card;
the signal acquisition module is used for controlling the data acquisition card to perform A/D conversion on the acquired signal information and then synchronously transmitting the signal information to the main control computer, and the main control computer stores the sampling information of the acquired signal information;
the signal preprocessing module is used for carrying out phase-mode conversion processing on the signal information;
the wavelet transformation module is used for determining the time when the fault initial wave reaches the measuring point by utilizing wavelet transformation;
the fault branch determining module is used for constructing a multi-terminal power transmission line fault branch judging matrix and finding out a fault branch through the multi-terminal power transmission line fault branch judging matrix;
the fault point position determining module is used for calculating the position of a fault point by utilizing a double-end traveling wave distance measuring method principle;
and the synchronous display module is used for controlling the main control computer to synchronously output the judgment result of the fault branch and the position calculation result of the fault point.
According to the embodiment of the invention, a new multi-terminal fault branch judgment matrix is established, and the fault branch can be accurately and effectively judged by utilizing the element characteristics of the matrix, so that the fault point can be accurately positioned. The invention effectively solves the practical problems that the existing fault location method can not identify the branch where the fault is located, the location precision is low and the method is easily influenced by various factors.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic flowchart of a multi-port line fault location method based on wavelet transform according to an embodiment of the present invention;
fig. 2 is a general block diagram of a multi-port line fault location method based on wavelet transformation according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a three-terminal power transmission line of a wavelet transform-based multi-terminal line fault location method according to an embodiment of the present invention;
fig. 4 is an N-terminal transmission line of a multi-terminal line fault location method based on wavelet transform according to an embodiment of the present invention;
fig. 5 is a 5-terminal power transmission line system diagram of a multi-terminal line fault location method based on wavelet transformation according to an embodiment of the present invention;
fig. 6 is a schematic block diagram of a multi-port line fault location system based on wavelet transformation according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
Referring to fig. 1, a flowchart of a multi-terminal line fault location method based on wavelet transformation according to an embodiment of the present invention is shown, where the multi-terminal line fault location method based on wavelet transformation includes the following steps S101 to S106.
Step S101: monitoring the detected power transmission line, uploading monitored signal information to a data acquisition card, carrying out A/D conversion on the acquired signal information by the data acquisition card, and then synchronously transmitting the signal information to a main control computer, wherein the main control computer stores sampling information for acquiring the signal information.
Specifically, the signals are monitored in real time and uploaded synchronously. The ABC three-phase current of the detected power transmission line is monitored in real time through the current transformer, and the three-phase current i detected in real timeA、iB、iCObtaining corresponding three-phase voltage signals u through I/V conversionA、uB、uCWhile simultaneously applying three-phase voltage signals uA、uB、uCAnd synchronously uploading to a data acquisition card. Data acquisition card for three-phase voltage signal uA、uB、uCAfter acquisition and corresponding A/D conversion, the data are synchronously transmitted to a main control computer. Main control computer to three-phase voltage signal uA、uB、uCThe number of the sampling points, all the sampling points and the sampling time corresponding to each sampling point are stored.
Step S102: and carrying out phase-mode conversion processing on the signal information.
Specifically, the signal preprocessing is phase-mode conversion. The main control computer is based on the formula
Figure BDA0002478914860000041
For three-phase voltage signal uA、uB、uCThe phase-mode conversion is carried out, and the 0-mode component, α -mode component and β -mode component of the detected line are obtained correspondingly,
Figure BDA0002478914860000042
u0、uα、uβrespectively 0 mode component, α mode component, β mode componentA、uB、uCRespectively are A phase,Phase B and phase C voltages.
Step S103: and determining the time when the fault initial wave reaches the measuring point by using wavelet transformation.
Specifically, the time when the fault initial traveling wave reaches the detection point is determined by using wavelet transformation. When the detected transmission line has a fault, the data acquisition card transmits a three-phase voltage signal u to the main control computerA、uB、uCFor the fault signal, the fault signal is converted into u through signal preprocessing0、uα、uβMain control computer pair α modulus voltage component uαWavelet transform is carried out, and α modulus voltage components u are recordedαIs denoted as t.
Step S104: and constructing a multi-end power transmission line fault branch judgment matrix, and finding out a fault branch through the multi-end power transmission line fault branch judgment matrix.
Referring to fig. 2 to 4, specifically, a fault branch judgment matrix is constructed to judge a fault branch. When the detected transmission line has a fault, the three-phase voltage signal u transmitted to the main control computer by the data acquisition cardA、uB、uCFor the fault signal, the main control computer carries out analysis processing on the three-phase fault voltage signal and correspondingly obtains which section the fault branch of the detected power transmission line is, and the analysis processing process is as follows:
(1) according to the principle of double-end traveling wave distance measurement, the main control computer is based on a formula
Figure BDA0002478914860000043
And calculating the distance X from the fault position of the power transmission line to the installation position of the power supply side current sensor, wherein L is the total length of the detected power transmission line, v is the propagation speed of the transient traveling wave on the detected power transmission line, and t1 and t2 are the time for the fault initial traveling wave to reach the installation positions of the power supply side current sensors at the two ends of the line respectively.
(2) And constructing a fault branch judgment matrix, and judging the fault branch by using the element characteristics of the matrix. The element of the fault branch judgment matrix is the ratio of the calculated fault distance to the length of the line from the starting end of the double-ended branch to the T node.
(a) The general formula of the fault branch judgment matrix of the three-terminal power transmission line is as follows:
Figure BDA0002478914860000051
wherein "×" indicates that the element is not considered, /)M1dM2、lM1dN1The fault distance of the double-end branch M1-M2 and M1-N1 which take the end M1 as the starting end; lM2dM1、lM2dN1The fault distance of the double-end branch M2-M1 and M2-N1 which take the end M2 as the starting end; lN1dM1、lN1dM2The fault distance of the double-end branch N1-M1 and N1-M2 which start from the end N1; lM1T1The line length of branch M1T 1; lN1T1The line length of branch N1T 1; lM2T1The line length for branch M2T 1;
(b) the general formula of the fault branch judgment matrix of the N-end transmission line (N >3) line is as follows:
Figure BDA0002478914860000052
wherein "×" indicates that the element is not considered, and the corresponding element value of the N-terminal transmission line fault branch judgment matrix is the ratio of the fault distance to the length of the line between the start of the branch at both ends and the T node closest to the end of the branch on the branch (for example, in fig. 4, for the double-terminal branch M1-N3, the element value corresponding to M1 row and N3 column in the fault branch judgment matrix should be the fault distance lM1dN3And the length l of the line M1-T3M1T3Ratio of).
(3) The comparison formula between each element value of the "faulty branch judgment matrix" and "1" is referred to as a "faulty branch judgment formula".
(4) And (4) correcting a fault branch judgment formula. Due to the existence of positioning errors caused by various influencing factors, certain margin needs to be reserved when each element in the calculated fault branch judgment matrix is compared with '1'. Therefore, the generated fault branch judgment matrix is corrected. Assuming that the value of a certain element in the determination formula is r, the set error margin is. When the fault branch determination formula is actually calculated, the element correction tables in the fault branch determination formula are as follows:
actual value Correction value
1-ε≤r≤1+ε r＝1
r<1-ε r<1
r>1+ε r>1
(5): principle of fault branch determination
Judging fault branch of three-terminal power transmission line
a) When all the row element values corresponding to a certain measuring point in the fault branch judgment formula are less than 1 and all the column element values corresponding to the measuring point are greater than 1, the fault can be judged to occur in the branch where the measuring point is located.
b) And when all elements of the fault branch judgment formula are equal to 1, judging that the fault occurs at the position of the T node.
And (2) judging fault branches of the N-end transmission line (N > 3).
a) And when the values of the row elements corresponding to a certain end measuring point in the fault branch judgment formula are all smaller than 1 and the values of the column elements corresponding to the measuring point are all larger than 1, judging that the branch line where the measuring point is located has a fault.
b) And when the values of the row elements corresponding to a certain end measuring point in the fault branch judging formula are all smaller than 1 and the column elements corresponding to the end measuring point are all equal to 1, judging that the fault occurs on the T node of the branch where the end measuring point is located. And when the elements of two adjacent columns are equal to 1, judging that the fault occurs at the T node of the branch where any one column of end measuring points is located.
c) When k is 2 in Nk, the failure a) and the failure b) are eliminated, and it is determined that a failure has occurred between the T nodes.
When k in Nk is greater than 2, (1) when values of row elements corresponding to only one end measuring point in the judgment formula are all smaller than 1 (namely, the values of elements of only one row are all smaller than 1), if only the first element value in the upper row is equal to 1, judging that a fault occurs between the T node of the branch where the end measuring point is located and the T node of the branch where the corresponding measuring point in the upper row is located, and if only the last element value in the lower row is equal to 1, judging that the fault occurs between the T node of the branch where the end measuring point is located and the T node of the branch where the corresponding measuring point in the lower row is located; (2) and when the values of two adjacent lines of elements are less than 1, judging that the fault occurs between the T nodes of the branch circuits where the end measuring points corresponding to the two adjacent lines of elements are located.
Step S105: and calculating the position of the fault point by utilizing a double-end traveling wave distance measurement method principle.
Specifically, a double-ended traveling wave method is used to locate a fault point. When the detected transmission line has a fault, the three-phase voltage signal u transmitted to the main control computer by the data acquisition cardA、uB、uCFor the fault signal, the main control computer analyzes and processes the three-phase fault voltage signal and correspondingly obtains the fault position of the detected power transmission line, and the analyzing and processing process is as follows:
(1): after the fault branch is judged, the bus which can form the double-end branch through the fault point most is selected as the initial end (when the bus which can be selected as the initial end has a plurality of buses, one of the buses can be selected as the initial end), and the fault distance from the initial end to the double-end branch of each other node through the fault point is calculated.
(2): the average of these several failure distances is taken as the final failure distance.
Figure BDA0002478914860000071
Wherein l is the final fault distance; liThe fault distance from the initial end to the double-end branch of each other node through the fault point.
Step S106: and the main control computer synchronously outputs the judgment result of the fault branch and the position calculation result of the fault point.
Specifically, in the step S104 and the step S105, during the power transmission line fault location, the main control computer synchronously displays the fault branch judgment result and the distance measurement result in the step S104 and the step S105 through the display connected to the main control computer.
Specifically, by establishing a new multi-terminal fault branch judgment matrix, the fault branch can be accurately and effectively judged by utilizing the element characteristics of the matrix, and further, a fault point can be accurately positioned. The invention effectively solves the practical problems that the existing fault location method can not identify the branch where the fault is located, the location precision is low and the method is easily influenced by various factors.
Referring to fig. 6, a schematic block diagram of a multi-terminal line fault location system based on wavelet transformation provided in the embodiment of the present invention includes a signal monitoring module 110, a signal acquisition module 120, a signal preprocessing module 130, a wavelet transformation module 140, a fault branch determination module 150, a fault point location determination module 160, and a synchronous display module 170, where the signal monitoring module 110 is configured to monitor a detected power transmission line and upload signal information obtained through monitoring to a data acquisition card; the signal acquisition module 120 is configured to control the data acquisition card to perform a/D conversion on the acquired signal information, and then synchronously transmit the signal information to a main control computer, where the main control computer stores sampling information of the acquired signal information; the signal preprocessing module 130 is configured to perform phase-to-analog conversion processing on the signal information; the wavelet transformation module 140 is configured to determine a time when the fault initial wave reaches the measurement point by using wavelet transformation; the fault branch determining module 150 is configured to construct a multi-terminal power transmission line fault branch judgment matrix, and find out a fault branch through the multi-terminal power transmission line fault branch judgment matrix; the fault point position determining module 160 is configured to calculate a position of a fault point by using a double-end traveling wave ranging method principle; the synchronous display module 170 is configured to control the main control computer to synchronously output the judgment result of the faulty branch and the position calculation result of the faulty point.
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below by combining the specific drawings.
As shown in fig. 5, the system is a 220kV 5-terminal transmission network. In order to accurately reflect transient and harmonic responses, a line model employs a frequency-dependent model. Tables 1 and 2 show the line parameters, respectively.
Table 1 transmission line parameters
Type of parameter r/(Ω/km) x/(Ω/km) g/(S/km) b/(S/km)
Positive sequence parameter 0.03468 0.4234 1×10-7 2.726×10-6
Zero sequence parameter 0.3 1.1426 1×10-7 1.936×10-6
TABLE 2 System impedance
Power supply Z1/Ω Z0/Ω
EM1 1.052+j23.175 0.600+j19.120
EN1 1.051+j20.500 0.530+j20.107
EN2 1.046+j18.765 0.390+j14.681
EN3 1.030+j16.500 0.500+j15.750
EM2 1.060+j20.125 0.300+j17.436
As shown in fig. 5, the fault points d are respectively arranged on the branch linesDifferent positions of lines on a path N2-T2, a node T2 and between a node T1 and a node T2, wherein the sampling frequency is set to be 2MHZ, the transition resistance is set to be 100 omega, measuring points are respectively arranged on buses of branch lines (the measuring points comprise M1, N1, N2, N3 and M2), the wave speed v is approximately equal to 2.9776674937965 × 108m/s。
In practice, the single-phase ground fault has the highest occurrence rate, and the invention is described as a phase-a ground short circuit. Wherein the error margin is taken to be 0.005. A single-phase earth fault happens at 0.2s moment, and a current transformer detects a three-phase fault current signal iA、iB、iCObtaining corresponding three-phase fault voltage signal u through I/V conversionA、uB、uCSimultaneously converting three-phase fault voltage signal uA、uB、uCAnd synchronously uploading to a data acquisition card.
Data acquisition card for three-phase fault voltage signal uA、uB、uCAfter acquisition and corresponding A/D conversion, the data are synchronously transmitted to a main control computer. Main control computer for three-phase fault voltage signal uA、uB、uCThe number of the sampling points, all the sampling points and the sampling time corresponding to each sampling point are stored.
The main control computer takes 1/4 periods of three-phase fault voltage signal at each measuring point after fault and according to formula
Figure BDA0002478914860000081
For three-phase fault voltage signal uA、uB、uCThe decoupling is carried out, in which formula,
Figure BDA0002478914860000082
and correspondingly obtaining α mode voltage components u of 1/4 cycles of each measuring point after the faultα。
Main control computer pair uαAnd performing wavelet transformation, and determining the arrival time of the initial fault traveling wave by using the maximum point of the wave mode of the initial fault traveling wave. The sampling time is represented by the sampling point. Since the sampling period is known and the starting time of the sampled voltage data is the same, the time difference between two sampling pointsWhich can be obtained by multiplying the sampling period between the sampling points.
1) Branch line fault
An A-phase grounding fault occurs on the branch line N2-T2 40km away from the end N2. And table 3 shows the positions of the sampling points where the detected initial fault traveling wave reaches each measuring point.
TABLE 3 sampling points for the initial traveling wave to reach each measurement point during the branch line fault
Point names M1 M2 N1 N2 N3
Sampling point 1138 1472 1271 266 1405
According to the principle of double-end traveling wave, the fault distance l of a two-end line M1-N1 with the end M1 as the starting endM1dN1Comprises the following steps:
Figure BDA0002478914860000091
the distance of failure lM1dN1And lM1T1Ratio of (A to (B)The values are:
Figure BDA0002478914860000092
similarly, other corresponding elements of the fault branch judgment matrix can be calculated to form the fault branch judgment matrix. The fault branch judgment matrix is as follows:
Figure BDA0002478914860000093
according to the correction rule of the fault branch judgment matrix, the fault branch judgment formula is as follows:
Figure BDA0002478914860000094
as can be seen from the faulty branch decision equation, all row element values corresponding to N2 are less than 1, and all column element values corresponding thereto are greater than 1. Therefore, the fault can be judged to occur on the branch line N2-T2 through the fault branch judgment principle of the N-terminal transmission line.
At this time, the bus bar N2 that can form the double-ended branch through the fault point as the most is selected as the initial end, and the average fault distance l from the fault point to the end N2 can be calculatedN2d。
Figure BDA0002478914860000095
2) T node failure
Node T2 has an a-phase ground fault. And table 4 shows the positions of the sampling points where the detected initial fault traveling wave reaches each measuring point.
TABLE 4 sampling points for initial traveling wave to reach each measurement point when T node fails
Point names M1 M2 N1 N2 N3
Sampling point 737 1071 870 670 1004
Similarly, the fault branch determination matrix is:
Figure BDA0002478914860000101
according to the correction rule, the corrected fault branch decision formula is as follows:
Figure BDA0002478914860000102
as can be seen from the faulty branch decision equation, the values of all row elements corresponding to N2 are less than 1, and the values of all column elements corresponding thereto are equal to 1. Therefore, it can be determined that the fault occurs on the T node T2 of the branch in which N2 is located according to the determination principle.
Similarly, the N2 end should be selected as the initial end, and the calculated average fault distance l between the fault point and the N2 endN2dIs composed of
Figure BDA0002478914860000103
3) Line fault between T nodes
An a-phase grounding fault occurs between the nodes T1 and T2 at a distance of 30km from the T1 point. And table 5 shows the positions of the sampling points where the detected initial fault traveling wave reaches each measuring point.
TABLE 5 sampling points for initial traveling waves to each measurement point during inter-node line fault
Point names M1 M2 N1 N2 N3
Sampling point 603 1205 736 803 1138
Similarly, the fault branch determination matrix is:
Figure BDA0002478914860000111
according to the correction rule, the corrected fault branch decision formula is as follows:
Figure BDA0002478914860000112
as can be seen from the failed branch decision equation, only all row elements in row N2 have values less than 1, and only the first element in the row above it has a value equal to 1. Therefore, it can be determined that a fault occurs between the nodes T2 and T1 according to the determination principle.
Because the double-ended branches formed by passing through the fault point when N1 and M1 are used as initial ends are the most and equal (three double-ended branches can be formed), N1 is randomly selected as the initial end at the moment, and the average distance l between the fault point and the N1 end is the same as the average distance lN1dComprises the following steps:
Figure BDA0002478914860000113
while the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (9)

1. A multi-end line fault positioning method based on wavelet transformation is characterized by comprising the following steps:
monitoring a detected power transmission line, uploading signal information obtained by monitoring to a data acquisition card, carrying out A/D conversion on the acquired signal information by the data acquisition card, and then synchronously transmitting the signal information to a main control computer, wherein the main control computer stores sampling information of the acquired signal information;
carrying out phase-mode conversion processing on the signal information;
determining the time when the initial fault wave reaches the measuring point by using wavelet transformation;
constructing a multi-end power transmission line fault branch judgment matrix, and finding out a fault branch through the multi-end power transmission line fault branch judgment matrix;
calculating the position of a fault point by utilizing a double-end traveling wave distance measurement principle;
and the main control computer synchronously outputs the judgment result of the fault branch and the position calculation result of the fault point.
2. The multi-terminal line fault location method based on wavelet transformation as recited in claim 1, wherein said monitoring the detected transmission line and uploading the monitored signal information to a data acquisition card comprises:
the three-phase current of the detected power transmission line is monitored in real time through a current transformer, current signals obtained through monitoring are converted into corresponding three-phase voltage signals through I/V, and the three-phase voltage signals are uploaded to the data acquisition card.
3. The wavelet transform-based multi-terminal line fault location method according to claim 2, wherein the sampling information includes the number of sampling points, position information of each sampling point, and a sampling time corresponding to the sampling point.
4. The wavelet transform-based multi-terminal line fault location method according to claim 2, wherein said performing phase-mode transform processing on said signal information comprises:
converting the voltage signal into corresponding module component information according to a preset conversion formula;
the preset conversion formula is as follows:
Figure RE-RE-FDA0002546640520000011
wherein the content of the first and second substances,
Figure RE-RE-FDA0002546640520000012
u0、uα、uβrespectively 0 mode component, α mode component, β mode componentA、uB、uCAnd the phase voltages of the A phase, the B phase and the C phase corresponding to the three-phase voltage signals are respectively.
5. The wavelet transform-based multi-terminal line fault location method according to claim 4, wherein said determining the time when the fault initiation wave reaches the measurement point by using wavelet transform comprises:
and the main control computer performs wavelet transformation on the alpha mode voltage component and records the time when the wave mode maximum value of the fault initial row of the alpha mode voltage component appears as the time when the fault initial wave reaches the measuring point.
6. The multi-terminal line fault location method based on wavelet transformation according to claim 5, wherein said constructing a multi-terminal transmission line fault branch judgment matrix, and finding out a fault branch through said multi-terminal transmission line fault branch judgment matrix comprises:
the main control computer calculates the distance from the fault position of the power transmission line to the installation position of the power supply side current sensor through a first calculation formula;
the first calculation formula is:
Figure RE-RE-FDA0002546640520000021
wherein L is the total length of the detected power transmission line, v is the speed of the transient traveling wave propagating on the detected power transmission line, and t1、t2Respectively determining the time of the initial fault traveling wave reaching the installation positions of the power supply side current sensors at the two ends of the line;
forming a fault branch judgment matrix by taking the ratio of the distance from the fault position of the power transmission line to the installation position of the power supply side current sensor and the length of the line from the starting end of the double-end branch to the T node as an element;
the fault branch judgment matrix is as follows:
the general formula of the fault branch judgment matrix of a plurality of multi-end transmission line lines is as follows:
Figure RE-RE-FDA0002546640520000031
wherein, the '×' indicates that the element is not considered, the corresponding element value of the judgment matrix of the fault branch of the N-end transmission line is the ratio of the fault distance to the length of the line between the starting end of the branches at two ends and the T node closest to the tail end of the branch, and the double-end branch M1-NkM in the faulty branch judgment matrix1Line NkThe value of the element corresponding to the column should be the fault distance lM1dNkAnd line M1-TkLength l ofM1TkThe ratio of (A) to (B);
comparing each element value in the fault branch judgment matrix with 1 to generate a fault branch judgment formula;
the fault branch judgment principle of the multi-end power transmission line comprises the following steps:
when the values of the row elements corresponding to a certain end measuring point in the fault branch judgment formula are all smaller than 1 and the values of the column elements corresponding to the measuring point are all larger than 1, judging that the branch line where the measuring point is located has a fault;
when the values of the row elements corresponding to a certain end measuring point in the fault branch judging formula are all smaller than 1 and the column elements corresponding to the end measuring point are all equal to 1, judging that a fault occurs on the T node of the branch where the end measuring point is located, and when two adjacent columns of elements are all equal to 1, judging that the fault occurs on the T node of the branch where any one column of end measuring point is located;
when k is 2, eliminating the branch line fault where the measuring point is determined to be located and determining that the fault occurs in the T node of the branch where any column of end measuring points is located, and then determining that the fault occurs between the T nodes;
when k is greater than 2, if the values of the row elements corresponding to only one end measuring point in the fault branch judgment formula are all smaller than 1 and only the first element value in the previous row is equal to 1, judging that a fault occurs between the T node of the branch where the end measuring point is located and the T node of the branch where the corresponding measuring point in the previous row is located, and if only the last element value in the next row is equal to 1, judging that the fault occurs between the T node of the branch where the end measuring point is located and the T node of the branch where the corresponding measuring point in the next row is located; and when the values of two adjacent lines of elements are less than 1, judging that the fault occurs between the T nodes of the branch circuits where the end measuring points corresponding to the two adjacent lines of elements are located.
7. The wavelet transform-based multi-port line fault location method according to claim 6, wherein after performing the generation of a faulty branch decision formula, the method further comprises modifying the faulty branch decision formula;
and the step of correcting the fault branch judgment formula comprises the step of reserving a certain margin when each element in the calculated fault branch judgment matrix is compared with 1.
8. The wavelet transform-based multi-terminal line fault location method of claim 6, wherein said calculating the location of the fault point using double-terminal traveling wave ranging principle comprises:
selecting a bus which can pass through a fault point to form the most double-end branches as an initial end, and calculating the fault distance from the initial end to the double-end branches of other nodes through the fault point;
taking the average value of the several fault distances as a final fault distance;
the expression of the final fault distance is:
Figure RE-RE-FDA0002546640520000041
wherein l is the final fault distance; liThe fault distance from the initial end to the double-end branch of each other node through the fault point.
9. A multi-end line fault positioning system based on wavelet transformation is characterized by comprising:
the signal monitoring module is used for monitoring the detected power transmission line and uploading monitored signal information to the data acquisition card;
the signal acquisition module is used for controlling the data acquisition card to perform A/D conversion on the acquired signal information and then synchronously transmitting the signal information to the main control computer, and the main control computer stores the sampling information of the acquired signal information;
the signal preprocessing module is used for carrying out phase-mode conversion processing on the signal information;
the wavelet transformation module is used for determining the time when the fault initial wave reaches the measuring point by utilizing wavelet transformation;
the fault branch determining module is used for constructing a multi-terminal power transmission line fault branch judging matrix and finding out a fault branch through the multi-terminal power transmission line fault branch judging matrix;
the fault point position determining module is used for calculating the position of a fault point by utilizing a double-end traveling wave distance measuring method principle;
and the synchronous display module is used for controlling the main control computer to synchronously output the judgment result of the fault branch and the position calculation result of the fault point.
CN202010372741.8A 2020-05-06 2020-05-06 Multi-end line fault positioning method and system based on wavelet transformation Pending CN111521910A (en)

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CN112698150A (en) * 2020-12-11 2021-04-23 河北工业大学 Distribution transformer monitoring terminal-based power distribution network traveling wave fault positioning method
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