CN120103064B - Power distribution network fault line selection method and system based on modal decomposition and self-adaptive noise - Google Patents
Power distribution network fault line selection method and system based on modal decomposition and self-adaptive noiseInfo
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- CN120103064B CN120103064B CN202510586523.7A CN202510586523A CN120103064B CN 120103064 B CN120103064 B CN 120103064B CN 202510586523 A CN202510586523 A CN 202510586523A CN 120103064 B CN120103064 B CN 120103064B
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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
- G01R31/088—Aspects of digital computing
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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
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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
- G01R31/50—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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- 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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Abstract
一种基于模态分解与自适应噪声的配电网故障选线方法及系统，包括：根据零序电压判断电力系统是否故障；若故障则获去馈线上含有噪声的暂态零序电流信号；根据固有模态分量的能量、频谱和时域相关性，从固有模态分量中选取出主频率模态分量；计算每个馈线主频率模态分量的能量与其他馈线主频率模态分量之和的能量的差值，以及每个馈线与其他馈线的相关性系数之和；若存在馈线既满足能量的差值最小，又满足相关性系数之和小于零，则该馈线为故障馈线。本发明通过能量与相关性系数筛选故障馈线，提高了配电网故障选线判别的准确性。
A distribution network fault line selection method and system based on modal decomposition and adaptive noise, including: judging whether the power system is faulty according to zero-sequence voltage; if faulty, obtaining the transient zero-sequence current signal containing noise on the feeder; selecting the main frequency modal component from the inherent modal component according to the energy, spectrum and time domain correlation of the inherent modal component; calculating the difference between the energy of the main frequency modal component of each feeder and the energy of the sum of the main frequency modal components of other feeders, and the sum of the correlation coefficients of each feeder and other feeders; if there is a feeder that satisfies both the minimum energy difference and the sum of the correlation coefficients being less than zero, the feeder is a faulty feeder. The present invention screens faulty feeders by energy and correlation coefficients, thereby improving the accuracy of fault line selection in the distribution network.
Description
Technical Field
The invention belongs to the technical field of power distribution network fault line selection, and particularly relates to a power distribution network fault line selection method and system based on complete integrated empirical mode decomposition and self-adaptive noise.
Background
With more and more distributed energy sources accessing into a power grid, how to ensure the power supply reliability of the power distribution network is the focus of study of domestic and foreign students. The probability of single-phase earth faults in the power system accounts for more than 80% of all fault conditions. When a single-phase fault occurs, the line voltage of the three-phase system still keeps in an equilibrium state, so that power can be continuously supplied for 1-2 hours. If left untreated for a long time, insulation breakdown will develop into phase-to-phase faults, so that the fault sections need to be located and cut off in time. However, due to the compensation effect of the arc suppression coil, the fault current is small, so that the existing research method cannot accurately identify.
With the development of deep learning, the current fault section locating method can be roughly divided into a traditional method based on fault characteristics and a modern method based on an artificial intelligence algorithm. The conventional methods can be classified into steady state information based, matrix method based and transient state characteristic based according to the fault characteristic. The method for positioning the fault section based on the steady state information is easily influenced by topology change, arc suppression coils and the like, and the matrix method faces the influence of data loss and distortion. The method for positioning the fault section based on the transient characteristic quantity can be further refined into a traveling wave method and a signal decomposition method. The traveling wave method utilizes the refraction and reflection characteristics of traveling wave signals when faults occur, and combines the wave speed and the transmission time to measure the distance of the faults. The traveling wave method is classified into a single-ended traveling wave method and a double-ended traveling wave method according to the difference in the utilization electric power. However, the traveling wave method requires a special device, has high cost, has a certain difficulty in wave head identification, and needs to further perfect waveform data and improve a waveform fault feature matching technology. Measurement data is often decomposed into different frequency band components using some modern signal processing methods.
CN110632462A provides a small-current grounding fault positioning method, a system, computer equipment and a medium thereof, and the method comprises the following steps of receiving zero-mode current wave recording data of monitoring nodes of a circuit in real time when the circuit breaks down, dividing each circuit into a plurality of sections, setting a plurality of monitoring nodes in each section, extracting transient components of the zero-mode current wave recording data, determining transient amplitude and transient resonance frequency of the zero-mode current wave recording data according to the transient components, generating transient characteristic quantities of the monitoring nodes according to the transient amplitude and the transient resonance frequency, and determining sections where the fault points are located according to the transient characteristic quantities of the monitoring nodes. The fault locating method does not carry out signal decomposition on the zero-mode current recorded broadcast data obtained by the monitoring node, cannot remove the influence of noise, does not establish a global transient characteristic quantity index, only considers amplitude and resonance frequency, and does not consider that the transient zero-mode current waveform of the fault line is opposite to the polarity of the non-fault line.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a power distribution network fault line selection method and system based on complete integrated empirical mode decomposition and self-adaptive noise.
The invention adopts the following technical scheme.
The first aspect of the invention provides a power distribution network fault line selection method based on modal decomposition and adaptive noise, which is characterized by comprising the following steps:
if the fault is detected, recording and collecting transient zero-sequence current in a set multiple period after the fault, and obtaining a transient zero-sequence current signal containing noise on a feeder line;
Decomposing a transient zero sequence current signal containing noise through a modal decomposition and self-adaptive noise algorithm to obtain a plurality of natural modal components, and selecting a main frequency modal component from the natural modal components according to the energy, frequency spectrum and time domain correlation of the natural modal components;
And if the feeder line exists, not only meeting the minimum difference of the energy, but also meeting the condition that the sum of the correlation coefficients is smaller than zero, the feeder line is a fault feeder line, otherwise, the zero sequence voltage of the power system is monitored, and whether the power system fails or not is judged according to the zero sequence voltage.
Preferably, the judging whether the power system fails according to the zero sequence voltage specifically includes:
And judging whether the zero sequence voltage exceeds the set multiple of the rated voltage of the bus, if so, the power system fails, otherwise, the power system does not fail, and the value range of the set multiple is between 0.05 and 0.15.
Preferably, the transient zero sequence current of the multiple period is set after the fault, and the transient zero sequence current is 1/4 period.
The transient zero sequence current signal containing noise is decomposed through a modal decomposition and self-adaptive noise algorithm to obtain a plurality of inherent modal components, and the method specifically comprises the following steps:
sequentially adding a plurality of pairs of white noise with the number being opposite to each other on the original signal by taking the transient zero sequence current signal containing noise as the original signal, carrying out modal decomposition on the original signal after each addition to obtain a first inherent modal component of the original signal;
subtracting the first inherent modal component of the transient zero-sequence current signal containing noise from the original signal to obtain a residual error;
Adding multiple pairs of self-adaptive noise to the residual error, carrying out modal decomposition on the residual error after each addition to obtain a second inherent modal component of the residual error;
Subtracting the second inherent modal component of the transient zero-sequence current signal containing noise from the residual error to obtain an updated residual error, and repeating the process until the updated residual error cannot continue modal decomposition.
Preferably, the adding multiple pairs of adaptive noise is specifically:
If the obtained k-th natural modal component is the transient zero sequence current signal containing noise, respectively carrying out modal decomposition on a plurality of pairs of white noise which are mutually opposite numbers and are added on the original signal to obtain the k-1-th natural modal component of each pair of white noise, multiplying the k-1-th natural modal component of each pair of white noise by the adaptive amplitude which is the amplitude of the plurality of pairs of white noise which are mutually opposite numbers and are added on the original signal by the energy of the residual error at the moment, wherein the adaptive amplitude corresponds to each pair of adaptive noise.
Preferably, the main frequency modal component is selected from the natural modal components according to the energy, the frequency spectrum and the time domain correlation of the natural modal components, specifically:
firstly, calculating the duty ratio of the energy of each natural mode component and the energy of all the natural mode components, and if the duty ratio of the natural mode components exceeds a set energy duty ratio threshold, selecting the natural mode component with the largest energy as a main frequency mode component;
otherwise, obtaining the frequency spectrum of each natural modal component through Fourier transformation, and calculating a comprehensive index, wherein the natural modal component with the maximum comprehensive index is used as a main frequency modal component;
Comprehensive index The calculation formula is as follows:
Wherein, the 、、For the set weight to be applied,The energy of the kth natural mode component, K is the total number of natural mode components,Is the maximum value in the energy of the natural modal component,Standard deviation of energy of natural modal component; The spectral peak frequency of the kth natural mode component; 、 Setting dB frequencies for the reduction of the left side and the right side of the frequency spectrum of the kth natural mode component; Is the kth natural modal component; n is a sampling point for the corresponding original signal; is a time domain correlation; representing an inner product operation; 。
Preferably, the calculating the difference between the energy of each feeder line main frequency modal component and the energy of the sum of other feeder line main frequency modal components, and the sum of correlation coefficients of each feeder line and other feeder lines is specifically:
Differences in energy of each feeder line main frequency modal component and sum of energy of other feeder line main frequency modal components The calculation formula is as follows:
wherein N is the sampling point number of the original signal, i, j represents the ith feeder line, j feeder lines, 、The value of the nth sampling point of the main frequency modal component of the ith feeder line and the J feeder lines is the total number of the feeder lines;
the sum of the correlation coefficients of each feeder line and other feeder lines The calculation formula is as follows:
Wherein, the 、The value of the nth sampling point of the original signal of the ith feeder line and the jth feeder line,、Is the average value of all sampling points of the original signals of the ith and j feeder lines.
The second aspect of the invention provides a power distribution network fault line selection system based on modal decomposition and self-adaptive noise by using the method of the first aspect of the invention, which comprises a monitoring module, a main frequency modal component acquisition module and a power distribution network fault line selection module, and is characterized in that:
the monitoring module monitors the zero sequence voltage of the power system in real time, judges whether the power system fails according to the zero sequence voltage, and records the transient zero sequence current with a set multiple period after the failure if the power system fails, so as to obtain a transient zero sequence current signal containing noise on a feeder line;
The main frequency modal component acquisition module is used for decomposing a transient zero sequence current signal containing noise through modal decomposition and a self-adaptive noise algorithm to obtain a plurality of natural modal components, and selecting main frequency modal components from the natural modal components according to the energy, frequency spectrum and time domain correlation of the natural modal components;
The power distribution network fault line selection module calculates the difference value of the energy of the main frequency modal component of each feeder line and the sum of the main frequency modal components of other feeder lines and the sum of the correlation coefficients of each feeder line and other feeder lines, if the feeder line is the smallest in energy difference value and the sum of the correlation coefficients is smaller than zero, the feeder line is the fault feeder line, otherwise, the zero sequence voltage of the power system is monitored, and whether the power system fails or not is judged according to the zero sequence voltage.
A third aspect of the invention proposes an apparatus comprising a memory, a processor and a computer program stored in the memory and executable on the processor, which when executed by the processor uses the steps of a power distribution network fault line selection method based on modal decomposition and adaptive noise according to the first aspect of the invention.
A fourth aspect of the present invention proposes a computer readable storage medium storing a computer program which, when executed by a processor, uses the steps of a power distribution network fault line selection method based on modal decomposition and adaptive noise according to the first aspect of the present invention.
Compared with the prior art, the method and the system for selecting the power distribution network fault line based on the completely integrated empirical mode decomposition and self-adaptive noise have the advantages that the simplified single-phase grounding fault transient analysis equivalent circuit is subjected to theoretical analysis, the zero sequence current signals of all the feeder lines are detected to obtain the feeder lines containing the transient zero sequence current signals of the noise, the transient zero sequence current signals containing the noise are decomposed through the mode decomposition and the self-adaptive noise algorithm to obtain a plurality of inherent mode components, the main frequency mode components are selected from the inherent mode components according to the energy, the frequency spectrum and the time domain correlation of the inherent mode components, the energy and the correlation coefficient of the main frequency mode components of all the feeder lines are determined based on the correlation and the energy difference theory, and therefore the feeder line with the maximum energy and the correlation coefficient smaller than zero is the fault feeder line, and the accuracy of the power distribution network fault line selection discrimination is improved.
Drawings
FIG. 1 is a flow chart of the present invention;
fig. 2 is an equivalent circuit diagram of the present invention with simplified circuitry.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. The described embodiments of the application are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art without inventive faculty, are within the scope of the application, based on the spirit of the application.
As shown in fig. 1, embodiment 1 of the present invention discloses a power distribution network fault line selection method based on modal decomposition and adaptive noise, which includes the following steps:
As shown in fig. 2, the circuit is simplified according to the actual situation, theoretical analysis is performed on the simplified single-phase earth fault transient analysis equivalent circuit, and the relationship between the polarity and the amplitude of the fault circuit and the healthy circuit is analyzed to obtain the conclusion that the polarity of the fault circuit is different from the polarity of the healthy circuit, and the amplitude of the fault circuit is obviously larger than that of the healthy circuit;
Specifically, at power frequency The inductance of the arc suppression coil is approximately equal to the capacitive reactance of the system to ground, namely:
In the formula (I), the total number of the components, 3 Times of arc suppression coil inductance; a distributed capacitance per unit length of line to ground; Summing the lengths of all outgoing lines of the system; Distributing the sum of the capacitances to ground for all outgoing lines;
Because the system has the capacitance resistance to the ground which is reduced along with the increase of the frequency, and the inductance resistance of the arc suppression coil is increased along with the increase of the frequency, the transient main resonance frequency is obtained The relation between the system capacitive reactance to the ground and the arc suppression coil inductive reactance is as follows:
in the formula, As can be seen from the above, when the frequency of the transient main resonance is proportional to the power frequencyWhen the inductance of the arc suppression coil is approximately considered to be 9 times greater than the capacitance of the capacitance to the ground, the action of the arc suppression coil can be ignored in the model simplification process, and then a simplified single-phase grounding fault transient analysis equivalent circuit is obtained, and theoretical analysis is carried out on the equivalent circuit as shown in fig. 2 to obtain the following formula:
in the formula, R is the voltage at two ends of the circuit, R is the equivalent resistance,For the magnitude of the bus voltage,In order to be able to take the moment of time,For the phase angle of the primary phase,For the zero sequence current of the h healthy line,Is the capacitance to ground of the h healthy line,Zero sequence current of fault line, H is total number of healthy lines
Is provided withCarrying out solution on the equation, and obtaining the following steps:
in the formula, 、Two solutions for r; is an imaginary number; is a characteristic root;
Because of When the difference value is larger than 1, the difference value between the energy of the main frequency modal component of the transient state zero-sequence current of the fault line and the energy of the sum of the main frequency modal components of other feeder lines is smallest, and the transient state zero-sequence current waveform of the fault line and the transient state zero-sequence current waveform of other feeder lines are in an up-down overturning state.
If the fault is detected, recording and collecting transient zero-sequence current in a set multiple period after the fault, and obtaining a transient zero-sequence current signal containing noise on a feeder line;
Decomposing a transient zero sequence current signal containing noise through a modal decomposition and self-adaptive noise algorithm to obtain a plurality of natural modal components, and selecting a main frequency modal component from the natural modal components according to the energy, frequency spectrum and time domain correlation of the natural modal components;
And if the feeder line exists, not only meeting the minimum difference of the energy, but also meeting the condition that the sum of the correlation coefficients is smaller than zero, the feeder line is a fault feeder line, otherwise, the zero sequence voltage of the power system is monitored, and whether the power system fails or not is judged according to the zero sequence voltage.
Judging whether the power system fails according to the zero sequence voltage, specifically:
And judging whether the zero sequence voltage exceeds the set multiple of the rated voltage of the bus, if so, the power system fails, otherwise, the power system does not fail, and the value range of the set multiple is between 0.05 and 0.15.
The transient zero sequence current signal containing noise is decomposed through a modal decomposition and self-adaptive noise algorithm to obtain a plurality of inherent modal components, and the method specifically comprises the following steps:
sequentially adding a plurality of pairs of white noise with the number being opposite to each other on the original signal by taking the transient zero sequence current signal containing noise as the original signal, carrying out modal decomposition on the original signal after each addition to obtain a first inherent modal component of the original signal;
subtracting the first inherent modal component of the transient zero-sequence current signal containing noise from the original signal to obtain a residual error;
Adding multiple pairs of self-adaptive noise to the residual error, carrying out modal decomposition on the residual error after each addition to obtain a second inherent modal component of the residual error;
Subtracting the second inherent modal component of the transient zero-sequence current signal containing noise from the residual error to obtain an updated residual error, and repeating the process until the updated residual error cannot continue modal decomposition.
The adding of the plurality of pairs of self-adaptive noise is specifically as follows:
If the obtained k-th natural modal component is the transient zero sequence current signal containing noise, respectively carrying out modal decomposition on a plurality of pairs of white noise which are mutually opposite numbers and are added on the original signal to obtain the k-1-th natural modal component of each pair of white noise, multiplying the k-1-th natural modal component of each pair of white noise by the adaptive amplitude which is the amplitude of the plurality of pairs of white noise which are mutually opposite numbers and are added on the original signal by the energy of the residual error at the moment, wherein the adaptive amplitude corresponds to each pair of adaptive noise.
According to the energy, frequency spectrum and time domain correlation of the natural modal components, the main frequency modal components are selected from the natural modal components, specifically:
firstly, calculating the duty ratio of the energy of each natural mode component and the energy of all the natural mode components, and if the duty ratio of the natural mode components exceeds a set energy duty ratio threshold, selecting the natural mode component with the largest energy as a main frequency mode component;
otherwise, obtaining the frequency spectrum of each natural modal component through Fourier transformation, and calculating a comprehensive index, wherein the natural modal component with the maximum comprehensive index is used as a main frequency modal component;
Comprehensive index The calculation formula is as follows:
Wherein, the 、、For the set weight to be applied,The energy of the kth natural mode component, K is the total number of natural mode components,Is the maximum value in the energy of the natural modal component,Standard deviation of energy of natural modal component; The spectral peak frequency of the kth natural mode component; 、 Setting dB frequencies for the reduction of the left side and the right side of the frequency spectrum of the kth natural mode component; Is the kth natural modal component; n is a sampling point for the corresponding original signal; is a time domain correlation; representing an inner product operation; 。
the calculating of the difference between the energy of the main frequency modal component of each feeder and the energy of the sum of the main frequency modal components of other feeders and the sum of the correlation coefficients of each feeder and the other feeders is specifically as follows:
Differences in energy of each feeder line main frequency modal component and sum of energy of other feeder line main frequency modal components The calculation formula is as follows:
wherein N is the sampling point number of the original signal, i, j represents the ith feeder line, j feeder lines, 、The value of the nth sampling point of the main frequency modal component of the ith feeder line and the J feeder lines is the total number of the feeder lines;
the sum of the correlation coefficients of each feeder line and other feeder lines The calculation formula is as follows:
Wherein, the 、The value of the nth sampling point of the original signal of the ith feeder line and the jth feeder line,、Is the average value of all sampling points of the original signals of the ith and j feeder lines.
The embodiment 2 of the invention provides a power distribution network fault line selection system based on modal decomposition and self-adaptive noise by using the method of the embodiment 1 of the invention, which comprises a monitoring module, a main frequency modal component acquisition module and a power distribution network fault line selection module, and is characterized in that:
the monitoring module monitors the zero sequence voltage of the power system in real time, judges whether the power system fails according to the zero sequence voltage, and records the transient zero sequence current with a set multiple period after the failure if the power system fails, so as to obtain a transient zero sequence current signal containing noise on a feeder line;
The main frequency modal component acquisition module is used for decomposing a transient zero sequence current signal containing noise through modal decomposition and a self-adaptive noise algorithm to obtain a plurality of natural modal components, and selecting main frequency modal components from the natural modal components according to the energy, frequency spectrum and time domain correlation of the natural modal components;
The power distribution network fault line selection module calculates the difference value of the energy of the main frequency modal component of each feeder line and the sum of the main frequency modal components of other feeder lines and the sum of the correlation coefficients of each feeder line and other feeder lines, if the feeder line is the smallest in energy difference value and the sum of the correlation coefficients is smaller than zero, the feeder line is the fault feeder line, otherwise, the zero sequence voltage of the power system is monitored, and whether the power system fails or not is judged according to the zero sequence voltage.
Embodiment 3 of the present invention proposes an apparatus comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the computer program when executed by the processor using the steps of a power distribution network fault line selection method based on modal decomposition and adaptive noise according to embodiment 1 of the present invention.
Embodiment 4 of the present invention proposes a computer readable storage medium storing a computer program which, when executed by a processor, uses the steps of the power distribution network fault line selection method based on modal decomposition and adaptive noise described in embodiment 1 of the present invention.
The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made to the specific embodiments of the present invention without departing from the spirit and scope of the present invention, and any modifications and equivalents are intended to be included in the scope of the claims of the present invention.
Claims (10)
1. The power distribution network fault line selection method based on modal decomposition and self-adaptive noise is characterized by comprising the following steps of:
if the fault is detected, recording and collecting transient zero-sequence current in a set multiple period after the fault, and obtaining a transient zero-sequence current signal containing noise on a feeder line;
Decomposing a transient zero sequence current signal containing noise through a modal decomposition and self-adaptive noise algorithm to obtain a plurality of natural modal components, and selecting a main frequency modal component from the natural modal components according to the energy, frequency spectrum and time domain correlation of the natural modal components;
And if the feeder line exists, not only meeting the minimum difference of the energy, but also meeting the condition that the sum of the correlation coefficients is smaller than zero, the feeder line is a fault feeder line, otherwise, the zero sequence voltage of the power system is monitored, and whether the power system fails or not is judged according to the zero sequence voltage.
2. The power distribution network fault line selection method based on modal decomposition and adaptive noise according to claim 1, wherein the method comprises the following steps:
Judging whether the power system fails according to the zero sequence voltage, specifically:
And judging whether the zero sequence voltage exceeds the set multiple of the rated voltage of the bus, if so, the power system fails, otherwise, the power system does not fail, and the value range of the set multiple is between 0.05 and 0.15.
3. The power distribution network fault line selection method based on modal decomposition and adaptive noise according to claim 1, wherein the method comprises the following steps:
and setting the transient zero-sequence current of the multiple period after the fault as the transient zero-sequence current of 1/4 period.
4. The power distribution network fault line selection method based on modal decomposition and adaptive noise according to claim 1, wherein the method comprises the following steps:
The transient zero sequence current signal containing noise is decomposed through a modal decomposition and self-adaptive noise algorithm to obtain a plurality of inherent modal components, and the method specifically comprises the following steps:
sequentially adding a plurality of pairs of white noise with the number being opposite to each other on the original signal by taking the transient zero sequence current signal containing noise as the original signal, carrying out modal decomposition on the original signal after each addition to obtain a first inherent modal component of the original signal;
subtracting the first inherent modal component of the transient zero-sequence current signal containing noise from the original signal to obtain a residual error;
Adding multiple pairs of self-adaptive noise to the residual error, carrying out modal decomposition on the residual error after each addition to obtain a second inherent modal component of the residual error;
Subtracting the second inherent modal component of the transient zero-sequence current signal containing noise from the residual error to obtain an updated residual error, and repeating the process until the updated residual error cannot continue modal decomposition.
5. The power distribution network fault line selection method based on modal decomposition and adaptive noise according to claim 4, wherein the method comprises the following steps:
The adding of the plurality of pairs of self-adaptive noise is specifically as follows:
If the obtained k-th natural modal component is the transient zero sequence current signal containing noise, respectively carrying out modal decomposition on a plurality of pairs of white noise which are mutually opposite numbers and are added on the original signal to obtain the k-1-th natural modal component of each pair of white noise, multiplying the k-1-th natural modal component of each pair of white noise by the adaptive amplitude which is the amplitude of the plurality of pairs of white noise which are mutually opposite numbers and are added on the original signal by the energy of the residual error at the moment, wherein the adaptive amplitude corresponds to each pair of adaptive noise.
6. The power distribution network fault line selection method based on modal decomposition and adaptive noise according to claim 5, wherein the method comprises the following steps:
according to the energy, frequency spectrum and time domain correlation of the natural modal components, the main frequency modal components are selected from the natural modal components, specifically:
firstly, calculating the duty ratio of the energy of each natural mode component and the energy of all the natural mode components, and if the duty ratio of the natural mode components exceeds a set energy duty ratio threshold, selecting the natural mode component with the largest energy as a main frequency mode component;
otherwise, obtaining the frequency spectrum of each natural modal component through Fourier transformation, and calculating a comprehensive index, wherein the natural modal component with the maximum comprehensive index is used as a main frequency modal component;
Comprehensive index The calculation formula is as follows:
Wherein, the 、、For the set weight to be applied,The energy of the kth natural mode component, K is the total number of natural mode components,Is the maximum value in the energy of the natural modal component,Standard deviation of energy of natural modal component; The spectral peak frequency of the kth natural mode component; 、 Setting dB frequencies for the reduction of the left side and the right side of the frequency spectrum of the kth natural mode component; Is the kth natural modal component; n is a sampling point for the corresponding original signal; is a time domain correlation; representing an inner product operation; 。
7. the power distribution network fault line selection method based on modal decomposition and adaptive noise according to claim 6, wherein the method comprises the following steps:
the calculating of the difference between the energy of the main frequency modal component of each feeder and the energy of the sum of the main frequency modal components of other feeders and the sum of the correlation coefficients of each feeder and the other feeders is specifically as follows:
Differences in energy of each feeder line main frequency modal component and sum of energy of other feeder line main frequency modal components The calculation formula is as follows:
Wherein N is the sampling point number of the original signal, i, j represents the ith feeder line, j feeder lines, 、The value of the nth sampling point of the main frequency modal component of the ith feeder line and the J feeder lines is the total number of the feeder lines;
the sum of the correlation coefficients of each feeder line and other feeder lines The calculation formula is as follows:
Wherein, the 、The value of the nth sampling point of the original signal of the ith feeder line and the jth feeder line,、Is the average value of all sampling points of the original signals of the ith and j feeder lines.
8. A power distribution network fault line selection system based on modal decomposition and adaptive noise using the method of any one of claims 1-7, comprising a monitoring module, a main frequency modal component acquisition module, and a power distribution network fault line selection module, wherein:
the monitoring module monitors the zero sequence voltage of the power system in real time, judges whether the power system fails according to the zero sequence voltage, and records the transient zero sequence current with a set multiple period after the failure if the power system fails, so as to obtain a transient zero sequence current signal containing noise on a feeder line;
The main frequency modal component acquisition module is used for decomposing a transient zero sequence current signal containing noise through modal decomposition and a self-adaptive noise algorithm to obtain a plurality of natural modal components, and selecting main frequency modal components from the natural modal components according to the energy, frequency spectrum and time domain correlation of the natural modal components;
The power distribution network fault line selection module calculates the difference value of the energy of the main frequency modal component of each feeder line and the sum of the main frequency modal components of other feeder lines and the sum of the correlation coefficients of each feeder line and other feeder lines, if the feeder line is the smallest in energy difference value and the sum of the correlation coefficients is smaller than zero, the feeder line is the fault feeder line, otherwise, the zero sequence voltage of the power system is monitored, and whether the power system fails or not is judged according to the zero sequence voltage.
9. An apparatus comprising a memory, a processor and a computer program stored in the memory and executable on the processor, which when executed by the processor uses the steps of a power distribution network fault line selection method based on modal decomposition and adaptive noise as claimed in any one of claims 1 to 7.
10. A computer readable storage medium storing a computer program which when executed by a processor uses the steps of a power distribution network fault line selection method based on modal decomposition and adaptive noise as claimed in any one of claims 1 to 7.
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