CN116914697A - Half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment - Google Patents

Half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment Download PDF

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CN116914697A
CN116914697A CN202310572614.6A CN202310572614A CN116914697A CN 116914697 A CN116914697 A CN 116914697A CN 202310572614 A CN202310572614 A CN 202310572614A CN 116914697 A CN116914697 A CN 116914697A
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fault
line
traveling wave
dimensional plane
cluster
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Inventor
范作云
吉星宇恒
张小东
邓凯
姚美定
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Three Gorges Jinsha River Yunchuan Hydropower Development Co ltd
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Three Gorges Jinsha River Yunchuan Hydropower Development Co ltd
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Priority to CN202310572614.6A priority Critical patent/CN116914697A/en
Publication of CN116914697A publication Critical patent/CN116914697A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Locating Faults (AREA)

Abstract

The application discloses a half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment, which comprises the following steps: the method comprises the steps of obtaining line mode current initial traveling wave clusters of forward faults and reverse faults by utilizing electromagnetic transient simulation of a large number of half-wavelength lines, establishing a two-dimensional plane sample space of the forward faults and the reverse faults, estimating fault positions according to starting time of protection elements on two sides when the lines are in faults, calculating fault initial phase angles, multiplying measured end line mode current initial traveling waves by fault initial phase angle characteristic values, judging fault directions by utilizing projection values q values of product curves on the two-dimensional plane sample space, wherein q is the forward faults if q is more than 0, and is the reverse faults if q is less than 0. The method provided by the application adopts the fault current initial traveling wave with a lower frequency band, can accurately ensure the directivity of the fault traveling wave, accurately distinguishes the forward fault and the reverse fault of the line by using two-dimensional plane judgment, and has certain robustness.

Description

Half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment
Technical Field
The application belongs to the technical field of relay protection of power systems, and particularly relates to a half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment.
Background
The half-wavelength alternating current transmission technology refers to an ultra-long distance alternating current transmission technology with transmission electric distance close to a power frequency half-wave, and the technology is first proposed in the 40 th century of 20. With the reduction of energy reserves in middle regions of China and the increasing of electricity consumption scale in regions with developed economy such as eastern regions, the ultra-high voltage half-wavelength alternating current transmission technology can be used as one of the future transmission modes of China.
The zero mode and line mode fault traveling wave on the half-wavelength line has serious attenuation along with the increase of the transmission distance, the zero modulus is unusable, a learner identifies the inside and outside of the half-wavelength alternating current line fault area based on the polarity of the wavelet mode maximum value of the traveling wave head, the protection only uses the positive and negative of the wavelet conversion mode maximum value of the directional traveling wave to correspond to the polarity of the traveling wave head, the magnitude corresponds to the strength of the abrupt change of the wave head, and the reliability is lower when the transient traveling wave is weak.
Disclosure of Invention
This section is intended to outline some aspects of embodiments of the application and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section as well as in the description of the application and in the title of the application, which may not be used to limit the scope of the application.
The present application has been made in view of the above-mentioned and/or existing problems associated with the half-wavelength line direction protection method based on two-dimensional plane judgment of linear-mode traveling wave clusters.
Therefore, the problem to be solved by the application is how to improve the reliability of the traveling wave direction protection.
In order to solve the technical problems, the application provides the following technical scheme: a half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment comprises the steps of performing simulation traversal of different fault types and positions on a half-wavelength line through electromagnetic transient simulation, and collecting fault current data; extracting line mode current initial traveling waves after fault current data are decoupled through phase mode transformation, and constructing line mode current traveling wave curve clusters; preprocessing the sample data of the calculated initial traveling wave curve clusters of the plurality of line mode currents, and carrying out two-dimensional plane analysis on the line mode current traveling wave curve clusters; collecting voltage and current information of a measuring terminal when a fault occurs as a sample to be measured, estimating a fault position and a fault initial phase angle, and determining a fault initial phase angle characteristic value; multiplying the initial travelling wave of the line mode current in the sample to be detected by the characteristic value of the fault initial phase angle, and judging the fault direction by utilizing the projection value of the curve on the two-dimensional plane sample space.
As a preferred scheme of the half-wavelength line direction protection method based on the linear mode traveling wave cluster two-dimensional plane judgment, the method comprises the following steps of: data of fault traveling waves reaching the M side and the N side of the measuring end in each sample data are selected for normalization processing; and processing the line mode current initial traveling wave curve clusters of the fault initial phase angles in the curve clusters to obtain the line mode current traveling wave curve clusters when the line fails in the forward direction and when the line fails in the reverse direction.
As a preferable scheme of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear mode traveling wave cluster, the application comprises the following steps: the specific method for carrying out two-dimensional plane analysis on the linear mode current traveling wave curve cluster comprises the following steps: PCA principal component analysis is carried out on the linear mode current traveling wave curve cluster, a first principal component PC1 and a second principal component PC2 can be obtained, and a two-dimensional plane sample space of the line forward fault and the line reverse fault is constructed on a two-dimensional plane.
As a preferable scheme of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear mode traveling wave cluster, the application comprises the following steps: the specific formula of the fault initial phase angle is as follows:
wherein ω is the system frequency, the unit is rad/s, v is the electromagnetic wave propagation speed, L fM As the distance of the fault point from the line M side,the voltage and the current acquired by the measuring end are respectively Z c For the wave impedance, the propagation coefficient γ=α+jβ, where the real part α is called the attenuation coefficient and the imaginary part β is called the phase coefficient.
As a preferable scheme of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear mode traveling wave cluster, the application comprises the following steps: the fault initial phase angle characteristic value includes:
when the failure initial phase angle theta 0 ∈(0°,90°]When the fault initial phase angle characteristic value k=1;
when the failure initial phase angle theta 0 E [ -90 DEG, 0 DEG), the fault initial phase angle characteristic value k= -1.
As a preferable scheme of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear mode traveling wave cluster, the application comprises the following steps: the fault position is calculated according to the starting time of the protection elements at the two sides, and the specific formula is as follows:
wherein L is fM For the distance of the fault point from the line M side, L is the half-wavelength line length 3000kmv and is the electromagnetic wave propagation speed, estimated from the start time of the protection elements on both sides.
As a preferable scheme of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear mode traveling wave cluster, the application comprises the following steps: the method comprises the steps of judging the fault direction by utilizing the projection q value of a product curve obtained by multiplying the line mode current initial traveling wave and the fault initial phase angle characteristic value in a sample to be detected on the PC1 axis of a two-dimensional plane sample space, wherein the specific judgment is as follows:
when q > q set The line is a forward fault;
if q is less than q set The line is reverse faulty.
As a preferable scheme of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear mode traveling wave cluster, the application comprises the following steps: the specific formula of the line mode current initial traveling wave curve cluster is as follows:
”'
i α ＝i αm (1)-i αm (-1)
wherein i is α ' is a curve cluster of initial traveling wave of line mode current, i αm ' 1 is the data of the first power frequency period after the fault of the line mode current, i αm ' (-1) is the data of the power frequency period before the fault of the line mode current.
In a second aspect, embodiments of the present application provide a computer device comprising a memory and a processor, the memory storing a computer program, wherein: and the processor executes the computer program to realize any step of the half-wavelength line direction protection method based on the line mode traveling wave cluster two-dimensional plane judgment.
In a third aspect, embodiments of the present application provide a computer-readable storage medium having stored thereon a computer program, wherein: and the computer program is executed by a processor to realize any step of the half-wavelength line direction protection method based on the line mode traveling wave cluster two-dimensional plane judgment.
The application has the beneficial effects that: the method provided by the application utilizes the characteristic of the half-wavelength transmission line as a customized long line, and the fault initial angle is estimated more accurately through the time difference that the protection elements at two sides of the line feel the fault after the fault occurs, so that the reliability and the selectivity of the protection are improved; the application adopts the fault current initial traveling wave cluster with lower frequency band to ensure the directivity same as that of the fault traveling wave with higher frequency band, shorten the fault removal time of the system and ensure the transient stability of the system; the application can accurately distinguish the forward fault and the reverse fault of the circuit by using the two-dimensional plane judgment, and if a large number of historical samples are added, the performance of the application can be further improved, and the application has certain robustness.
Drawings
For a clearer description of the technical solutions of embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the description below are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art, wherein:
fig. 1 is a simulation diagram of a half-wavelength transmission line system of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear-mode traveling wave cluster in embodiment 1.
Fig. 2 is a graph of an initial traveling wave curve cluster of current when a half-wavelength line of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear-mode traveling wave cluster in embodiment 2 has a forward fault.
Fig. 3 is a graph of an initial traveling wave curve cluster of current when a half-wavelength line of the half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear-mode traveling wave cluster in embodiment 2 has a reverse fault.
Fig. 4 is a plot of the projected point clusters formed on the coordinate axes of PC1 and PC2 by the current initial traveling wave curves when the half-wavelength line is in the forward fault and the reverse fault in example 2.
FIG. 5 is a schematic diagram of the circuit F in example 2 1 、F 2 And when the position is in fault, judging a result diagram of the M-end fault section.
FIG. 6 is a schematic diagram of the circuit F in example 2 3 、F 4 And when the position is in fault, judging a result diagram of the M-end fault section.
Detailed Description
In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present application is not limited to the specific embodiments disclosed below.
Furthermore, references herein to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic that may be included in at least one implementation of the application, and that "in one embodiment" appearing in various places throughout the specification are not all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Example 1
Referring to fig. 1, a first embodiment of the present application provides a half-wavelength line direction protection method based on two-dimensional plane judgment of a line mode traveling wave cluster, including:
s1: and performing simulation traversal of different fault types and positions on the half-wavelength line through electromagnetic transient simulation, and collecting fault current data.
S2: and extracting the initial traveling wave of the line mode current after the fault current data are decoupled through phase mode transformation, and constructing a line mode current traveling wave curve cluster as a history sample.
Further, decoupling the obtained plurality of pieces of simulation fault data according to a photographic mode transformation matrix to extract corresponding line mode current, wherein the specific formula is as follows:
wherein i is α 、i β 、i 0 Currents respectively representing alpha mode, beta mode and zero mode, i a 、i b 、i c The A, B and C three-phase currents measured by the line measurement terminals are shown respectively.
Further, subtracting the data of the first power frequency period after the fault from the data of the first power frequency period before the fault to obtain the initial traveling wave curve cluster of the line mode current, wherein the specific formula is as follows:
i α '＝i αm '(1)-i αm '(-1)
wherein i is α ' is a curve cluster of initial traveling wave of line mode current, i αm ' 1 is the data of the first power frequency period after the fault of the line mode current, i αm ' (-1) is the line mode currentIs the data of the power frequency period before the fault of the power frequency.
S3: preprocessing the calculated sample data of the initial traveling wave curve clusters of the plurality of line mode currents, and carrying out two-dimensional plane analysis on the traveling wave curve clusters of the line mode currents.
Further, data 1ms before the fault traveling wave reaches the measuring end M side and N side and data 3ms after the fault traveling wave reaches the measuring end M side and N side in each sample data are selected to be normalized by using a mapmin max function.
Further, after multiplying the line mode current initial traveling wave curve cluster with the failure initial phase angle in the curve cluster by-1, the failure initial phase angle theta can be obtained 0 E < -90 > and 0 DEG) fault current traveling wave and fault initial phase angle theta 0 ∈(0,90°]The fault current traveling wave calculation is unified, and a line mode current traveling wave curve cluster when the line fails positively and a line mode current traveling wave curve cluster when the line fails reversely are obtained.
Further, PCA is utilized to perform two-dimensional plane analysis on the line mode current traveling wave curve cluster during the forward fault and the reverse fault of the line, and the line mode current traveling wave curve cluster is mapped into a two-dimensional plane space formed by PC1 and PC 2. Under the condition that the characteristics of most data are reserved, the PCA operation can be utilized to project the data of the curve cluster into a two-dimensional plane space, so that the point cluster of the line forward fault and the line reverse fault is obtained.
Furthermore, the application analyzes curve cluster data by utilizing PCA, and the curve cluster is obtained by analyzing the curve cluster, namely, the point cluster of forward and reverse faults on a two-dimensional plane is obtained by analyzing the curve cluster of forward and reverse faults through PCA.
S4: and collecting voltage and current information of the measuring terminal when a fault occurs as a sample to be measured, and starting time of the protection elements at two sides to estimate the fault position and the fault initial phase angle and determine the characteristic value of the fault initial phase angle.
Further, after the fault occurs, one end of the protection element is started to record the starting time T M Will start time T M Transmitting to the opposite end, and delaying T set Receiving opposite end protection starting time T N If receiving the opposite terminal T N Then immediately execute the next step in which the fault location is estimatedThe specific formula is as follows:
wherein L is fM L is the distance from the fault point to the line M side, L is the length 3000km of the half-wavelength line, and v is the propagation speed of electromagnetic waves;
when L fM ＞3000km，L fM ＝3000km；
When L fM ＜0km，L fM ＝0km。
It should be noted that since the propagation time of the electromagnetic wave over the whole half wavelength line is about 10ms, T set Set to 20ms.
Further, the voltage of the fault point of the sample to be detected is calculated according to the collected current and voltage information and the estimated fault position.
It should be noted that when the transmission line is long, there is a significant fluctuation in the transmission of the electric quantity along the line, a distribution parameter model must be used to calculate the voltage current along the line, and when a fault occurs, the voltage current collected by the measurement terminal isUsing estimated fault location L fM The voltage at the fault point can be calculated as follows:
wherein the propagation constantZ c For wave impedance +.>For measuring the voltage and current collected by the terminal, L fM Is the fault location.
Further, a fault initial phase angle is calculated, and a specific formula is as follows:
wherein ω is the system frequency, the unit is rad/s, v is the electromagnetic wave propagation speed, L fM As the distance of the fault point from the line M side,the voltage and the current acquired by the measuring end are respectively Z c For the wave impedance, the propagation coefficient γ=α+jβ, where the real part α is called the attenuation coefficient and the imaginary part β is called the phase coefficient.
Further, a criterion is constructed according to the angle of the fault initial phase angle, and the criterion is specifically as follows:
when the failure initial phase angle theta 0 ∈(0°,90°]When the fault initial phase angle characteristic value k=1;
when the failure initial phase angle theta 0 E [ -90 DEG, 0 DEG), the fault initial phase angle characteristic value k= -1.
S5: multiplying the initial travelling wave of the line mode current in the sample to be detected by the characteristic value of the fault initial phase angle, and judging the fault direction by utilizing the projection value of the curve on the two-dimensional plane sample space.
Further, when the failure initial phase angle theta 0 ∈(0°,90°]The line has a forward fault, and the projection q value of the fault current initial traveling wave curve on the PC1 axis of the two-dimensional plane sample space is positive; the line fails in reverse and the projected q value on the axis of the two-dimensional planar sample space PC1 is negative.
Further, the failure initial phase angle theta 0 E [ -90 degrees, 0 degrees), when the line fails in the forward direction, the projected q value is negative; when the line fails reversely, the projection q value is positive.
Further, principal component analysis is performed on the sample to be detected by PCA, the sample to be detected can be projected into a two-dimensional plane sample space, and forward and reverse faults are judged by using the value of the sample to be detected on the PC1 axis
When q > q set The line is a forward fault;
if q is less than q set The line is reverse faulty.
Note that, in the present embodimentExample, q set ＝0。
The embodiment also provides a computer device, which is suitable for the case of the half-wavelength line direction protection method, and includes:
a memory and a processor; the memory is used for storing computer executable instructions, and the processor is used for executing the computer executable instructions to realize the half-wavelength line direction protection method based on the line mode traveling wave cluster two-dimensional plane judgment, which is proposed by the embodiment.
The computer device may be a terminal comprising a processor, a memory, a communication interface, a display screen and input means connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The communication interface of the computer device is used for carrying out wired or wireless communication with an external terminal, and the wireless mode can be realized through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, can also be keys, a track ball or a touch pad arranged on the shell of the computer equipment, and can also be an external keyboard, a touch pad or a mouse and the like.
The present embodiment also provides a storage medium having stored thereon a computer program which, when executed by a processor, performs the following steps as set forth in the above embodiments:
performing simulation traversal of different fault types and positions on the half-wavelength line through electromagnetic transient simulation, and collecting fault current data;
extracting line mode current initial traveling waves after fault current data are decoupled through phase mode transformation, and constructing line mode current traveling wave curve clusters as history samples;
preprocessing the sample data of the calculated initial traveling wave curve clusters of the plurality of line mode currents, and carrying out two-dimensional plane analysis on the line mode current traveling wave curve clusters;
collecting voltage and current information of a measuring end when a fault occurs as a sample to be measured, and starting time of protection elements at two sides to estimate a fault position and a fault initial phase angle, and determining a characteristic value of the fault initial phase angle;
multiplying the initial travelling wave of the line mode current in the sample to be detected by the characteristic value of the fault initial phase angle, and judging the fault direction by utilizing the projection value of the curve on the two-dimensional plane sample space.
In summary, the method provided by the application utilizes the half-wavelength transmission line as the characteristic of the customized long line, and the fault initial angle is estimated more accurately through the time difference that the protection elements at two sides of the line feel the fault after the fault occurs, so that the reliability and the selectivity of the protection are improved; the fault current initial traveling wave cluster with a lower frequency band is adopted, so that the directivity same as that of the fault traveling wave with a higher frequency band can be ensured, the fault removal time of the system is shortened, and the transient stability of the system is ensured; the two-dimensional plane judgment can accurately distinguish the forward fault and the reverse fault of the circuit, and if a large number of historical samples are added, the performance of the application can be further improved, and the application has certain robustness.
Example 2
Referring to fig. 2 to 6, for the second embodiment of the present application, a comparative description with the conventional scheme is provided for verifying the advantageous effects thereof on the basis of the first embodiment.
Firstly, performing simulation traversal of different fault types and positions on a half-wavelength line simulation system, and collecting fault current data.
Specifically, the simulation system parameters are: at 50Hz power frequency, positive sequence inductance L 1 ＝8.404×10 -7 H/m, positive sequence resistance R 1 ＝1.032×10 -5 Omega/m, positive sequence capacitor C 1 ＝1.375×10 -11 F/m zero sequence inductance L 0 ＝2.692×10 -6 H/m, zero sequence resistance R 0 ＝2.513×10 -4 Omega/m zero sequence capacitor C 0 ＝8.804×10 -12 F/m，E m ＝1.05∠0°，E n ＝1.00∠150°。
It should be noted that, the triangle-arranged line parameters and line model of the 1000kV ultra-high voltage test demonstration project which is put into operation are adopted to build the half-wavelength alternating current transmission line model (the diversification of the line corridor environment is ignored), the transmission line is uniformly transposed, the whole length of the line is 3000km, and the sampling frequency of the system is 20kHz.
Further, AG faults with a fault initial angle of 90 degrees are arranged on a half-wavelength simulation system model every 100km along the whole length of a line MN, AG faults with a fault initial angle of-90 degrees are arranged every 100km along the whole length of the line MN, AG faults with fault initial angles of 90 degrees, 70 degrees and 50 degrees respectively are arranged on an M-end bus and behind an M-end, AG faults with fault initial angles of-90 degrees, 70 degrees and 50 degrees respectively are arranged on an M-end bus and behind an M-end, and N ends are the same.
Further, extracting line mode current initial traveling wave after decoupling fault current data through phase mode transformation, constructing a line mode current traveling wave curve cluster, as a history sample, decoupling and extracting corresponding line mode current from a plurality of pieces of obtained simulation fault data according to a photographic mode transformation matrix, subtracting the data of the first power frequency period after the fault of each line mode current from the data of the first power frequency period before the fault, and obtaining the line mode current initial traveling wave curve cluster, wherein the specific formula is as follows:
i α '＝i αm '(1)-i αm '(-1)
wherein i is α ' is a curve cluster of initial traveling wave of line mode current, i αm ' 1 is the data of the first power frequency period after the fault of the line mode current, i αm ' (-1) is the data of the power frequency period before the fault of the line mode current.
Further, the sample data of the plurality of line mode current initial traveling wave curve clusters obtained through calculation are preprocessed, the result is shown in fig. 2 and 3, and the principal component analysis is carried out on the line mode current traveling wave curve clusters, and the result is shown in fig. 4.
Further, taking M-terminal protection as an example, experiments are carried out on the protection method and the criterion.
Preferably, a half-wavelength line simulation model such asAs shown in FIG. 1, the sampling frequency of the system is 20kHz, and the sampling frequencies are respectively F 1 、F 2 A single-phase grounding fault with a fault initial phase angle of 80 degrees and a fault grounding resistance of 0 omega is arranged at two positions, namely, behind an M-end bus and on a line of 750km, and the fault moment t 1 ＝0.2135s，t 2 ＝0.216s。
Further, the obtained simulation fault data of the sample to be tested are decoupled according to a photographic mode transformation matrix to extract corresponding line mode currents, and the data of the first power frequency period after the fault of each line mode current is subtracted from the data of the last power frequency period before the fault, so that the line mode current initial traveling wave curve cluster can be obtained.
Further, after protection is started, current and voltage information is collected, and according to the starting time T of the protection elements at two sides of the circuit M1 、T N1 、T M2 、T N2 Estimating the fault location L f1 、L f2 Then according to the acquisition of the M end Respectively find out fault point voltage->Then the calculated failure initial phase angle theta is utilized 01 、θ 02 And obtain the characteristic values of the failure initial phase angles as k respectively 1 、k 2 。
Further, intercepting fault current data in the line mode current initial traveling wave 4ms time window under the 2 different fault conditions respectively, multiplying the fault initial phase angle characteristic value k of each fault initial phase angle, then carrying out principal component analysis of PCA (principal component analysis), and projecting the principal component analysis onto a two-dimensional plane to obtain a projection value of a sample to be tested on a PC1 coordinate axisFinally, the fault direction of the line is judged by the aid of the direction element.
As shown in fig. 5, when the line F 1 、F 2 When the position is faulty, judging the result diagram of the M-end fault section according to the judgment of S5 in the specificationIn accordance with the determination that it is not possible,namely F 1 To reverse fault, F 2 Is a forward fault.
Further, F 1 F for a reverse fault with a fault initiation angle of 80 DEG 2 The application can correctly judge the forward fault and the reverse fault for the forward fault with the initial phase angle of 80 degrees.
Preferably, as shown in FIG. 1, the simulation model of the half-wavelength line has a system sampling frequency of 20kHz, and is respectively shown in F 3 、F 4 Two positions, namely, a line 2550km and an N-end bus are provided with a single-phase grounding fault with a fault initial phase angle of-90 DEG and a fault grounding resistance of 100 omega, and the fault time t is the time of the fault 3 ＝0.3516s，t 4 ＝0.2443s。
Further, after protection is started, current and voltage information is collected, and according to the starting time T of the protection elements at two sides of the circuit M3 、T N3 、T M4 、T N4 Estimating the fault location L f3 、L f4 Then according to the acquisition of the M end Respectively find out fault point voltage->Then the calculated failure initial phase angle theta is utilized 03 、θ 04 And obtain the characteristic values of the failure initial phase angles as k respectively 3 、k 4 。
Further, the fault current data in the line mode current initial traveling wave 4ms time window under the 2 different fault conditions are respectively taken, the principal component analysis of PCA is carried out after the fault initial phase angle characteristic values are multiplied, and the principal component analysis is projected onto a two-dimensional plane, namely the projection value of the test sample on the PC1 coordinate axis is obtainedFinally, the direction element is used for judgingThe fault direction of the line.
Further, as shown in FIG. 6, line F in example 2 3 、F 4 When the position is faulty, the judgment result diagram of the M-end fault section is judged according to the criterion of the step S5 in the specification, namely F 3 F is a forward fault 4 Is a forward fault.
Further, F 3 F for a forward failure of 100. Omega. Of the ground resistance 4 The application can correctly identify the forward fault and has a certain transitional resistance for the forward out-of-zone fault of the grounding resistor 100 omega.
It should be noted that the above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present application may be modified or substituted without departing from the spirit and scope of the technical solution of the present application, which is intended to be covered in the scope of the claims of the present application.

Claims (10)

1. The half-wavelength line direction protection method based on the two-dimensional plane judgment of the linear mode traveling wave cluster is characterized by comprising the following steps of: comprising the following steps:
performing simulation traversal of different fault types and positions on the half-wavelength line through electromagnetic transient simulation, and collecting fault current data;
extracting line mode current initial traveling waves after fault current data are decoupled through phase mode transformation, and constructing line mode current traveling wave curve clusters;
preprocessing the sample data of the calculated initial traveling wave curve clusters of the plurality of line mode currents, and carrying out two-dimensional plane analysis on the line mode current traveling wave curve clusters;
collecting voltage and current information of a measuring terminal when a fault occurs as a sample to be measured, estimating a fault position and a fault initial phase angle, and determining a fault initial phase angle characteristic value;
and multiplying the initial travelling wave of the line mode current in the sample to be detected by the characteristic value of the fault initial phase angle, and judging the fault direction by utilizing the projection value of the curve on the two-dimensional plane sample space.
2. The half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment according to claim 1, wherein the method comprises the following steps: the pretreatment of the calculated sample data of the initial traveling wave curve clusters of the plurality of line mode currents comprises the following steps:
data of fault traveling waves reaching the M side and the N side of the measuring end in each sample data are selected for normalization processing;
for failure initial phase angle theta in curve cluster 0 And E < -90 > and 0 DEG) to obtain the line mode current traveling wave curve clusters when the line fails forward and when the line fails backward.
3. The half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment according to claim 1, wherein the method comprises the following steps: the specific method for carrying out two-dimensional plane analysis on the linear mode current traveling wave curve cluster comprises the following steps: PCA principal component analysis is carried out on the linear mode current traveling wave curve cluster, a first principal component PC1 and a second principal component PC2 can be obtained, and a two-dimensional plane sample space of the line forward fault and the line reverse fault is constructed on a two-dimensional plane.
4. The half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment according to claim 1, wherein the method comprises the following steps: the specific formula of the fault initial phase angle is as follows:
wherein ω is the system frequency, the unit is rad/s, v is the electromagnetic wave propagation speed, L fM As the distance of the fault point from the line M side,the voltage and the current acquired by the measuring end are respectively Z c For the wave impedance, the propagation coefficient γ=α+jβ, where the real part α is called the attenuation coefficient and the imaginary part β is called the phase coefficient.
5. The half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment according to claim 1, wherein the method comprises the following steps: the fault initial phase angle characteristic value comprises:
when the failure initial phase angle theta 0 ∈(0°,90°]When the fault initial phase angle characteristic value k=1;
when the failure initial phase angle theta 0 E [ -90 DEG, 0 DEG), the fault initial phase angle characteristic value k= -1.
6. The half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment according to claim 1, wherein the method comprises the following steps: the specific formula of the estimated fault position is as follows:
wherein L is fM For the distance of the fault point from the line M side, L is the half-wavelength line length 3000kmv and is the electromagnetic wave propagation speed, estimated from the start time of the protection elements on both sides.
7. The half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment according to claim 1, wherein the method comprises the following steps: the projection value of the curve on the two-dimensional plane sample space is utilized to judge the fault direction, and the specific judgment is as follows:
when q > q set The line is a forward fault;
if q is less than q set The line is reverse faulty.
8. The half-wavelength line direction protection method based on the linear mode traveling wave cluster two-dimensional plane judgment according to claim 2, wherein the method is characterized by comprising the following steps of: the specific formula of the line mode current initial traveling wave curve cluster is as follows:
i α ′＝i αm ′(1)-i αm ′(-1)
wherein i is α ' is a curve cluster of initial traveling wave of line mode current, i αm ' 1 is the data of the first power frequency period after the fault of the line mode current, i αm ' (-1) is the data of the power frequency period before the fault of the line mode current.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that: the method for protecting the half-wavelength line direction based on the line mode traveling wave cluster two-dimensional plane judgment comprises the steps of implementing the method for protecting the half-wavelength line direction based on the line mode traveling wave cluster two-dimensional plane judgment according to any one of claims 1 to 8 when the processor executes the computer program.
10. A computer-readable storage medium having stored thereon a computer program, characterized by: the method for protecting the half-wavelength line direction based on the two-dimensional plane judgment of the linear mode traveling wave cluster according to any one of claims 1 to 8 is realized when the computer program is executed by a processor.
CN202310572614.6A 2023-05-19 2023-05-19 Half-wavelength line direction protection method based on line mode traveling wave cluster two-dimensional plane judgment Pending CN116914697A (en)

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