CN118347393B - Power transmission line sag detection method based on inherent noise of power line - Google Patents
Power transmission line sag detection method based on inherent noise of power line Download PDFInfo
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Abstract
The invention discloses a power transmission line sag detection method based on inherent noise of a power line, which comprises the following steps of: and obtaining the time-frequency two-dimensional characteristics of the inherent noise between the line starting end and the line terminating end through the current sensing device at the line starting end and the line terminating end, exerting the advantage that the correlation operation is suitable for detecting weak signals, and calculating the length change and sag of the power transmission line through the time domain cross correlation operation of the inherent noise of the line starting end and the frequency domain phase difference operation of the inherent noise of the line starting end and the line terminating end. The method avoids the inconvenience of installing the detection device in the middle section of the line, has robustness in the line sag detection result, provides engineering feasibility for the detection of the power transmission line, and remarkably improves the efficiency of the sag detection of the power transmission line in various complex scenes.
Description
Technical Field
The invention relates to the technical field, in particular to a power transmission line sag detection method based on inherent noise of a power line.
Background
Sag of a power transmission line refers to a slight bending in the power transmission line due to the dead weight of the line, which looks like a catenary. The sag is too large, the height to the ground is reduced, and the safety distance which does not meet the design requirement is greatly influenced on the safety of objects under the line. The existing method mainly adopts a detection device hung in the center of a line, adopts methods such as light, radio, image and the like to detect the distance between the device and the ground, and is inconvenient to install, use and maintain. The existing method also adopts Beidou positioning to detect the sag of the circuit. The Beidou positioning has higher precision on the detection of the horizontal plane position, and has poor detection capability on the vertical direction, so that the engineering requirements cannot be well met. Thus, there is an urgent need to study more convenient and efficient detection methods in the field.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a power transmission line sag detection method based on inherent noise of a power line, which aims to estimate sag of the power line according to time-frequency signal correlation of the inherent noise of the power line.
In order to achieve the above purpose, the present invention provides the following technical solutions: a power transmission line sag detection method based on inherent noise of a power line comprises the following steps:
Step S1: collecting a current signal of a line starting end through a current transformer, wherein the current signal comprises A-phase current Current of B phaseAnd C phase currentSimilarly, the current signal of the line termination end is collected by a current transformer, which comprises A-phase currentCurrent of B phaseAnd C phase current; The collected current signal comprises a power frequency power signal and inherent noise;
step S2: removing a power frequency component in the current signal through a power frequency harmonic trap, and reserving a high-frequency component representing inherent noise; amplifying the high-frequency signal with the power frequency component removed by a preamplifier, and converting the amplified high-frequency signal into a digital signal by adopting an analog-digital converter;
Step S3: performing discrete Fourier transform on the digital signal to obtain spectrum information of the digital signal; the digital high-frequency band-pass filter is adopted to further remove low-frequency signals in the digital signals according to the obtained frequency spectrum information of the digital signals, a frequency domain signal at the starting end of a circuit is output, the amplitude of the digital signals with the low-frequency signals removed is subjected to smoothing processing according to the frequency spectrum characteristics of inherent noise, and the digital signals after smoothing processing are subjected to inverse discrete Fourier transform to obtain high-frequency time domain signals representing the inherent noise;
Step S4: based on the steps S1-S3, obtaining high-frequency time domain signals representing inherent noise of a line starting end and a line ending end, and carrying out correlation operation on the high-frequency time domain signals representing inherent noise of the starting end and the line ending end through a time domain correlation operator of the inherent noise to obtain time delay data of the line under different lengths; the phase difference operation is carried out on the frequency domain signals of the line starting end and the line ending end through the frequency domain phase difference arithmetic unit with inherent noise, so that time delay data of the line under different lengths are obtained;
The analog-digital converter, the discrete Fourier transform, the digital high-frequency band pass filter, the discrete Fourier inverse transform, the inherent noise time domain correlation arithmetic unit and the inherent noise frequency domain phase difference arithmetic unit are uniformly controlled by adopting clock synchronous signals;
Step S5: and analyzing the time delay data obtained by the correlation operation and the time delay data obtained by the phase difference operation by adopting a convolutional neural network to obtain the time delay data of the signal transmission of the line starting end and the sag estimation data of the transmission line, and outputting the line time delay estimation and the sag estimation data.
Further, in the inherent noise time domain correlation operator, the high-frequency time domain signals representing inherent noise at the line starting end and the line ending end complete correlation operation through the multiplication integrator; specific:
Let the A-phase current at the beginning of the line represent the high-frequency time-domain signal of the inherent noise as The A-phase current at the line termination represents the high-frequency time domain signal of the inherent noise as；
By means of an inherently noisy time-domain correlation operatorAndThe multiplication and integration operations with length i are performed, expressed as:
（1）；
In the method, in the process of the invention, A value representing a cross-correlation operation; Representing the relevant distance; Representation of Values at the relevant distance points.
Further, the cross-correlation operation includes multiplication and integration, and the cross-correlation operation includesTraversing; when reaching the termination end through line transmission Having the same waveform whenThe time delay via line a isWhen (1):
（2）；
In the method, in the process of the invention, Representation ofA delayed value;
In the output result of the cross-correlation operation, Presenting an impulse waveform with spikes, the waveform amplitude being proportional to the sequence length:
（3）；
In the method, in the process of the invention, A value representing a cross-correlation operation; The result of the related operation, which shows that the delay time is the same as the related distance, is the square sum of the values of each point, and the maximum output is obtained;
similarly, the time delay of the high frequency time domain signal representing the inherent noise via line B is Output resultWill present an impulse waveform with spikes, the time delay of the high frequency time domain signal representing the inherent noise via line C beingOutput resultAn impulse waveform with spikes will be presented; the result of the correlation of the high-frequency time-domain signals of the ABC three-phase line representing the inherent noise is obtained:
（4）；
（5）；
（6）；
In the method, in the process of the invention, Representing a length ofA phase line related operation result; representing a length of B-phase line related operation results; representing a length of C-phase line related operation result;
Performing correlation operation on the obtained high-frequency time domain signals representing the inherent noise to obtain time delay data of the line starting end under different lengths;
comprehensively carrying out statistical analysis on the time delay data, queuing according to the output amplitude, carrying out statistical analysis, and respectively solving by impulse response positions:
（7）；
（8）；
（9）；
In the method, in the process of the invention, Representing the average value of the delay data of the A-phase line; representing the average value of delay data of the B-phase line; representing the average value of time delay data of the C-phase line; representing the ith time delay of the A-phase line; Representing the ith time delay of the B-phase line; representing the ith time delay of the C-phase line; indicating the number of common delays.
Further, the smoothed digital signal is subjected to discrete fourier transform, expressed as:
（10）；
In the method, in the process of the invention, Spectral information representing m-order frequency points of noise; n represents a serial number;
obtaining the spectrum information of m times of frequency points of ABC noise of each phase after discrete Fourier transformation 、And。
Further, the removal of the power frequency component in the current signal by the power frequency harmonic trap is expressed as:
（11）；
In the method, in the process of the invention, AndRespectively representing poles and zeros of a transfer function, and designing according to frequency points, notch bandwidths and notch depths; Representing transmission characteristics; A variable representing a discrete digital transformation; the high-frequency signal is obtained after the processing of the power frequency harmonic wave trap, and is expressed as 、And。
Further, the transfer function is adopted asThe digital high-frequency band-pass filter further removes low-frequency signals in the digital signals according to the obtained frequency spectrum information of the digital signals, and smoothes the amplitude of the digital signals from which the low-frequency signals are removed according to the frequency spectrum characteristics of inherent noise, and outputs a frequency domain signal at the starting end of a line, which is expressed as:
（12）；
In the method, in the process of the invention, Representing the passing of the transfer functionA digital signal at the starting end of the line processed by the digital high-frequency band-pass filter; Representing the passing of the transfer function A line start digital signal before processing by a digital high-frequency band-pass filter;
similarly, the A-phase current at the line termination end Current of B phaseAnd C-phase currentRepeating the above processes to obtain a frequency domain signal of the line termination end, which is expressed as:
（13）；
In the method, in the process of the invention, Representing the passing of the transfer functionA digital signal of the line termination end processed by the digital high-frequency band-pass filter; representing the passing of the transfer function The line termination side digital signal before processing by the digital high-frequency band-pass filter.
Further, the specific process of performing phase difference operation on the frequency domain signals of the line starting end and the line ending end by using the frequency domain phase difference arithmetic unit with inherent noise is as follows:
firstly, calculating the phase of each frequency point of a starting end of a line:
（14）；
In the method, in the process of the invention, Representation ofIs a phase of (2);
calculating the phase of each frequency point at the line termination end:
（15）；
In the method, in the process of the invention, Representation ofIs a phase of (2);
Calculating phase difference between line start end and line end ：
（16）；
Under a certain time delay, the phase difference is proportional to the frequency, and the normalized phase difference is used for deriving the time delay:
（17）；
In the method, in the process of the invention, Representing the normalized phase difference;
Taking the accumulated value of the normalized phase difference to obtain time delay data under different lengths of a line starting end and a line terminating end, wherein the time delay data is expressed as:
（18）；
In the method, in the process of the invention, Representing the noise transmission time between the line start and line end.
Furthermore, the convolutional neural network adopted in the step S5 is based on a feedback mechanism and consists of a three-layer coupling structure of a training layer, a detection layer and a feedback regulation layer, so that information interaction is realized.
Further, the convolution nerve based on the feedback mechanism utilizes the high-frequency time domain signal representing the inherent noise and the time delay data of different lengths of the line starting end and the line ending end to calculate the line length; the original sag of the line is obtained through the length of the line, the distances between the two ends of the line and the hanging height of the line, and after the temperature characteristic of the line is added, the change of the length of the line is estimated, and the sag change of the line is deduced.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention can estimate the sag of the power transmission line by utilizing the time-frequency signal correlation of the phase line inherent noise without installing any device at the sag part of the middle section of the line and only installing a current detection device at the starting end and the ending end of the line.
(2) Aiming at the randomness of inherent noise, the invention plays the advantage that the correlation operation is suitable for the detection of weak signals, accumulated impulse appears at the alignment point of the sequence at the starting end and the ending end of the line, and the average value of noise at other points is close to 0, so that the time delay test has high feasibility.
(3) The method calculates the transmission delay of the line starting end and the line ending end for a long time, uses methods such as frequency spectrum analysis of random noise, time domain correlation operation of random noise, notch of power frequency signals, convolutional neural network and the like, reproduces the process of manually judging sag by adopting an intelligent method, has robustness in detection results, and provides engineering feasibility for power transmission line detection.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
Fig. 2 is a flowchart of a method for implementing a frequency domain phase difference operator according to the present invention.
Detailed Description
As shown in fig. 1, the present invention provides the following technical solutions: a power transmission line sag detection method based on inherent noise of a power line comprises the following steps:
Step S1: collecting a current signal of a line starting end through a current transformer, wherein the current signal comprises A-phase current Current of B phaseAnd C phase currentSimilarly, the current signal of the line termination end is collected by a current transformer, which comprises A-phase currentCurrent of B phaseAnd C phase current; The collected current signal not only contains a power frequency power signal with a large amplitude, but also contains very weak inherent noise buried in the power frequency power signal; wherein the spectrum of the inherent noise is very broad;
Step S2: removing a power frequency component in the current signal through a power frequency harmonic trap, and reserving a high-frequency component representing inherent noise; the frequency spectrum characteristic of the power frequency harmonic trap requires a larger recess on a 50Hz frequency point, and has a certain bandwidth; amplifying the high-frequency signal with the power frequency component removed by a preamplifier, and converting the amplified high-frequency signal into a digital signal by an analog-digital converter;
Step S3: performing discrete Fourier transform on the digital signal to obtain spectrum information of the digital signal; the digital high-frequency band-pass filter is adopted to further remove low-frequency signals in the digital signals according to the obtained frequency spectrum information of the digital signals, a frequency domain signal at the starting end of a circuit is output, the amplitude of the digital signals with the low-frequency signals removed is subjected to smoothing processing according to the frequency spectrum characteristics of inherent noise, and the digital signals after smoothing processing are subjected to inverse discrete Fourier transform to obtain high-frequency time domain signals representing the inherent noise; the length of the inverse discrete Fourier transform is different, and the inverse discrete Fourier transform comprises 1 level and 2 level … n levels;
step S4: based on the steps S1-S3, obtaining high-frequency time domain signals representing inherent noise of a line starting end and a line ending end, and carrying out correlation operation on the high-frequency time domain signals representing inherent noise of the line starting end and the line ending end through a time domain correlation operator of the inherent noise to obtain time delay data of the line starting end and the line ending end under different lengths; the phase difference operation is carried out on the frequency domain signals of the line starting end and the line ending end through the frequency domain phase difference arithmetic unit with inherent noise, and time delay data of the line starting end and the line ending end under different lengths are obtained; the two kinds of time delay data can respectively contain a certain error, and the accuracy of time delay detection needs to be further improved through convolutional neural network calculation;
The analog-digital converter, the discrete Fourier transform, the digital high-frequency band pass filter, the discrete Fourier inverse transform, the inherent noise time domain correlation arithmetic unit and the inherent noise frequency domain phase difference arithmetic unit are uniformly controlled by adopting clock synchronous signals;
Step S5: and analyzing the time delay data obtained by the correlation operation and the time delay data obtained by the phase difference operation by adopting a convolutional neural network to obtain the time delay data of signal transmission of a line starting end and a line terminating end and sag estimation data of a transmission line, and finally outputting the data such as line time delay estimation, sag estimation and the like through an output interface.
The digital sequence of the high-frequency time domain signals representing the inherent noise with different lengths is generated by the high-frequency band signals representing the inherent noise of the A phase current, the B phase current and the C phase current through inverse discrete Fourier transform, and the digital sequence comprises 1 level and 2 level … N levels; in the time domain correlation arithmetic unit of the inherent noise, the high-frequency time domain signals representing the inherent noise of the line starting end and the line ending end finish the correlation operation through the multiplication integrator; specific:
Let the A-phase current at the beginning of the line represent the high-frequency time-domain signal of the inherent noise as The A-phase current at the line termination represents the high-frequency time domain signal of the inherent noise as；
By means of an inherently noisy time-domain correlation operatorAndPerforming multiplication and integration operation with length of i:
（1）；
In the method, in the process of the invention, A value representing a cross-correlation operation; Representing the relevant distance; Representation of Values at the relevant distance points;
wherein the cross-correlation operation includes multiplication and integration, and the cross-correlation operation includes Traversing; when reaching the termination end through line transmission Having the same waveform ifThe time delay via line a isWhen (1):
（2）；
In the method, in the process of the invention, Representation ofA delayed value;
In the output result of the cross-correlation operation, An impulse waveform with spikes will be presented, the waveform amplitude being proportional to the sequence length:
（3）；
In the method, in the process of the invention, A value representing a cross-correlation operation; The result of the correlation operation, which indicates that the delay time is the same as the correlation distance, is the sum of squares of the values of each point, and the maximum output is obtained.
Also, because the inherent noise is0 average noise with randomness, at the point that other time delays are not equal to the related distanceThe upper will take on a small value, close to 0, so that the delay test has a very high output amplitude.
Similarly, the time delay of the high frequency time domain signal representing the inherent noise via line B isOutput resultWill exhibit an impulse waveform with spikes, if the time delay of the high frequency time domain signal representing the inherent noise via line C isOutput resultAn impulse waveform with spikes will be presented; the result of this is that the ABC three-phase line represents the result of the correlation of the high frequency time domain signal of the intrinsic noise:
（4）；
（5）；
（6）；
In the method, in the process of the invention, Representing a length ofA phase line related operation result; representing a length of B-phase line related operation results; representing a length of C-phase line related operation result;
performing correlation operation on the obtained high-frequency time domain signals representing the inherent noise to obtain time delay data of the line starting end and the line terminating end under different lengths;
Comprehensively carrying out statistical analysis on 3N time delay data, queuing according to the output amplitude, and carrying out statistical analysis including mean value, variance, random distribution type and the like, wherein the statistical analysis is respectively obtained by impulse response positions:
（7）；
（8）；
（9）；
In the method, in the process of the invention, Representing the average value of the delay data of the A-phase line; representing the average value of delay data of the B-phase line; representing the average value of time delay data of the C-phase line; representing the ith time delay of the A-phase line; Representing the ith time delay of the B-phase line; representing the ith time delay of the C-phase line; Representing the number of common time delays;
similarly, statistical analysis of variance, random distribution type, etc. can be performed.
As shown in fig. 2, the smoothed digital signal is subjected to discrete fourier transform, expressed as:
（10）；
In the method, in the process of the invention, Spectral information representing m-order frequency points of noise; n represents a serial number;
obtaining the spectrum information of m times of frequency points of ABC noise of each phase after discrete Fourier transformation 、And。
The removal of the power frequency component in the current signal by the power frequency harmonic trap can be expressed as:
（11）；
In the method, in the process of the invention, AndRespectively representing poles and zeros of a transfer function, and designing according to frequency points, notch bandwidths and notch depths; Representing transmission characteristics; A variable representing a discrete digital transformation; the high-frequency signal is obtained after the processing of the power frequency harmonic wave trap, and is expressed as 、And。
Wherein, in order to obtain finer time delay calculation, a transfer function is adopted asThe digital high-frequency band-pass filter further removes low-frequency signals in the digital signals according to the obtained frequency spectrum information of the digital signals, and smoothes the amplitude of the digital signals from which the low-frequency signals are removed according to the frequency spectrum characteristics of inherent noise, and outputs a frequency domain signal at the starting end of a line, which can be expressed as:
（12）；
In the method, in the process of the invention, Representing the passing of the transfer functionA digital signal at the starting end of the line processed by the digital high-frequency band-pass filter; Representing the passing of the transfer function The digital high-frequency band-pass filter processes the line-start digital signal before processing.
Similarly, the A-phase current at the line termination endCurrent of B phaseAnd C-phase currentThe above processing is repeated to obtain a frequency domain signal of the line termination end, which can be expressed as:
（13）；
In the method, in the process of the invention, Representing the passing of the transfer functionA digital signal of the line termination end processed by the digital high-frequency band-pass filter; representing the passing of the transfer function The line termination side digital signal before processing by the digital high-frequency band-pass filter.
The specific process of carrying out phase difference operation on the frequency domain signals of the line starting end and the line ending end through the frequency domain phase difference arithmetic unit with inherent noise is as follows:
firstly, calculating the phase of each frequency point of a starting end of a line:
（14）；
In the method, in the process of the invention, Representation ofIs a phase of (2);
calculating the phase of each frequency point at the line termination end:
（15）；
In the method, in the process of the invention, Representation ofIs a phase of (2);
Calculating phase difference between line start end and line end ：
（16）；
At a certain time delay, the phase difference is proportional to the frequency, so the deriving time delay requires normalizing the phase difference:
（17）；
In the method, in the process of the invention, Representing the normalized phase difference;
Taking the accumulated value of the normalized phase difference to obtain time delay data of different lengths of the line starting end and the line terminating end, wherein the time delay data can be expressed as:
（18）；
In the method, in the process of the invention, Representing the noise transmission time between the line start and line end.
In order to adapt to complex working conditions, the invention adopts a convolutional neural network based on a feedback mechanism for predicting line sag; the convolutional neural network based on the feedback mechanism consists of a three-layer coupling structure of a training layer, a detection layer and a feedback regulation layer, so that information interaction is realized;
The logic mechanism of the convolution nerve based on the feedback mechanism is to calculate the length of the line by using the high-frequency time domain signal representing the inherent noise and the time delay data of different lengths of the starting end and the ending end of the line. Obtaining the original sag of the line through the length of the line, the distances between the two ends of the line and the hanging height of the line, estimating the change of the length of the line after the temperature characteristic of the line is added, and deducing the sag change of the line;
the input matrix of the convolutional nerve based on the feedback mechanism includes the following data: high-frequency time domain signal cross-correlation operation result of inherent noise represented by line starting end and ending end ; Time delay data of different lengths of line starting end and line terminating end; Cable length; Termination distance; Temperature (temperature); Environmental factors。
The output parameters of the convolution nerve based on the feedback mechanism are as follows: line length variation; Sag estimation。
The training layer consists of three modules, namely data normalization preprocessing, convolutional neural networks (Convolutional Neural Networks, CNN) and random configuration network classifiers (Stochastic Configuration Networks, SCNs). The data normalization preprocessing is used for realizing the normalization of the amplitude by a robust method according to the difference of the output amplitude of the arithmetic unit. And adopting least square method based straight line fitting to normalize and correct the data with different amplitudes. The training samples are input into a convolutional neural network CNN after normalization pretreatment, sample feature vectors are extracted, and a random configuration network classifier SCNs is used for classifying the feature vectors to obtain a state detection result of the training samples. The training layer carries out larger weight on the related data with longer time length, plays the advantage that the related operation is suitable for the detection of weak signals, ensures that the detection result has robustness and is suitable for the time delay detection under the weak noise of the transmission line;
The detection layer synchronously realizes extraction and state detection of feature vectors based on the feature space provided by the training layer, calculates semantic error information entropy of the test samples according to the feature vectors, and evaluates detection results of the test samples in real time; outputting a detection result if the semantic error information entropy measure index is met; otherwise, retraining and learning are carried out;
the feedback adjustment layer adjusts the detection space in a self-adaptive mode when different detection objects are detected according to the deviation of the entropy measure index of the semantic error information, the size and the number of convolution kernels are adjusted in a self-adaptive mode when the feature space is different for the different detection objects, the feedback adjustment layer returns to the network model input layer, model training is conducted again, and therefore comparison detection results are optimized repeatedly, and the identifiable rate and the correct rate of the improved convolution neural network model are improved;
The convolutional neural network which is converged after repeated training can estimate sag accurately enough according to the delay data of the inherent noise of the line starting end and the line ending end.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. The power transmission line sag detection method based on the inherent noise of the power line is characterized by comprising the following steps of:
Step S1: collecting a current signal of a line starting end through a current transformer, wherein the current signal comprises A-phase current Current of B phaseAnd C phase currentSimilarly, the current signal of the line termination end is collected by a current transformer, which comprises A-phase currentCurrent of B phaseAnd C phase current; The collected current signal comprises a power frequency power signal and inherent noise;
step S2: removing a power frequency component in the current signal through a power frequency harmonic trap, and reserving a high-frequency component representing inherent noise; amplifying the high-frequency signal with the power frequency component removed by a preamplifier, and converting the amplified high-frequency signal into a digital signal by adopting an analog-digital converter;
Step S3: performing discrete Fourier transform on the digital signal to obtain spectrum information of the digital signal; the digital high-frequency band-pass filter is adopted to further remove low-frequency signals in the digital signals according to the obtained frequency spectrum information of the digital signals, a frequency domain signal at the starting end of a circuit is output, the amplitude of the digital signals with the low-frequency signals removed is subjected to smoothing processing according to the frequency spectrum characteristics of inherent noise, and the digital signals after smoothing processing are subjected to inverse discrete Fourier transform to obtain high-frequency time domain signals representing the inherent noise;
Step S4: based on the steps S1-S3, obtaining high-frequency time domain signals representing inherent noise of a line starting end and a line ending end, and carrying out correlation operation on the high-frequency time domain signals representing inherent noise of the starting end and the line ending end through a time domain correlation operator of the inherent noise to obtain time delay data of the line under different lengths; the phase difference operation is carried out on the frequency domain signals of the line starting end and the line ending end through the frequency domain phase difference arithmetic unit with inherent noise, so that time delay data of the line under different lengths are obtained;
The analog-digital converter, the discrete Fourier transform, the digital high-frequency band pass filter, the discrete Fourier inverse transform, the inherent noise time domain correlation arithmetic unit and the inherent noise frequency domain phase difference arithmetic unit are uniformly controlled by adopting clock synchronous signals;
in the time domain correlation arithmetic unit of the inherent noise, the high-frequency time domain signals representing the inherent noise of the line starting end and the line ending end finish the correlation operation through the multiplication integrator; specific:
Let the A-phase current at the beginning of the line represent the high-frequency time-domain signal of the inherent noise as The A-phase current at the line termination represents the high-frequency time domain signal of the inherent noise as；
By means of an inherently noisy time-domain correlation operatorAndThe multiplication and integration operations with length i are performed, expressed as:
（1）；
In the method, in the process of the invention, A value representing a cross-correlation operation; Representing the relevant distance; Representation of Values at the relevant distance points;
Step S5: analyzing the time delay data obtained by the correlation operation and the time delay data obtained by the phase difference operation by adopting a convolutional neural network to obtain the time delay data of the signal transmission of the line starting end and the sag estimation data of the transmission line, and outputting the line time delay estimation and the sag estimation data;
Calculating the length of a line based on a convolutional neural network by using high-frequency time domain signals representing inherent noise and time delay data of different lengths of a line starting end and a line ending end; the original sag of the line is obtained through the length of the line, the distances between the two ends of the line and the hanging height of the line, and after the temperature characteristic of the line is added, the change of the length of the line is estimated, and the sag change of the line is deduced.
2. The power line sag detection method based on the inherent noise of the power line according to claim 1, wherein: the cross-correlation operation includes multiplication and integration, and the pairA traversal is made through which the user can choose,When reaching the termination end through line transmissionHaving the same waveform whenThe time delay via line a isWhen (1):
（2）；
In the method, in the process of the invention, Representation ofA delayed value;
In the output result of the cross-correlation operation, Presenting an impulse waveform with spikes, the waveform amplitude being proportional to the sequence length:
（3）；
In the method, in the process of the invention, A value representing a cross-correlation operation; The result of the related operation, which shows that the delay time is the same as the related distance, is the square sum of the values of each point, and the maximum output is obtained;
similarly, the time delay of the high frequency time domain signal representing the inherent noise via line B is Output resultWill present an impulse waveform with spikes, the time delay of the high frequency time domain signal representing the inherent noise via line C beingOutput resultAn impulse waveform with spikes will be presented; the result of the correlation of the high-frequency time-domain signals of the ABC three-phase line representing the inherent noise is obtained:
（4）；
（5）；
（6）；
In the method, in the process of the invention, Representing a length ofA phase line related operation result; representing a length of B-phase line related operation results; representing a length of C-phase line related operation result;
Performing correlation operation on the obtained high-frequency time domain signals representing the inherent noise to obtain time delay data of the line starting end under different lengths;
comprehensively carrying out statistical analysis on the time delay data, queuing according to the output amplitude, carrying out statistical analysis, and respectively solving by impulse response positions:
（7）；
（8）；
（9）；
In the method, in the process of the invention, Representing the average value of the delay data of the A-phase line; representing the average value of delay data of the B-phase line; representing the average value of time delay data of the C-phase line; representing the ith time delay of the A-phase line; Representing the ith time delay of the B-phase line; representing the ith time delay of the C-phase line; indicating the number of common delays.
3. A method for detecting sag of a power transmission line based on noise inherent to the power transmission line according to claim 2, wherein: performing discrete fourier transform on the smoothed digital signal, expressed as:
（10）；
In the method, in the process of the invention, Spectral information representing m-order frequency points of noise; n represents a serial number;
obtaining the spectrum information of m times of frequency points of ABC noise of each phase after discrete Fourier transformation 、And。
4. A method for sag detection of a power line based on noise inherent to the power line according to claim 3, wherein: the removal of the power frequency component in the current signal by the power frequency harmonic trap is expressed as:
（11）；
In the method, in the process of the invention, AndRespectively representing poles and zeros of a transfer function, and designing according to frequency points, notch bandwidths and notch depths; Representing transmission characteristics; A variable representing a discrete digital transformation; the high-frequency signal is obtained after the processing of the power frequency harmonic wave trap, and is expressed as 、And。
5. The method for detecting sag of a power transmission line based on noise inherent to the power transmission line according to claim 4, wherein: using transfer functions asThe digital high-frequency band-pass filter further removes low-frequency signals in the digital signals according to the obtained frequency spectrum information of the digital signals, and smoothes the amplitude of the digital signals from which the low-frequency signals are removed according to the frequency spectrum characteristics of inherent noise, and outputs a frequency domain signal at the starting end of a line, which is expressed as:
（12）；
In the method, in the process of the invention, Representing the passing of the transfer functionA digital signal at the starting end of the line processed by the digital high-frequency band-pass filter; Representing the passing of the transfer function A line start digital signal before processing by a digital high-frequency band-pass filter;
similarly, the A-phase current at the line termination end Current of B phaseAnd C-phase currentRepeating the above processes to obtain a frequency domain signal of the line termination end, which is expressed as:
（13）；
In the method, in the process of the invention, Representing the passing of the transfer functionA digital signal of the line termination end processed by the digital high-frequency band-pass filter; representing the passing of the transfer function The line termination side digital signal before processing by the digital high-frequency band-pass filter.
6. The method for detecting sag of a power transmission line based on inherent noise of a power line according to claim 5, wherein: the specific process of carrying out phase difference operation on the frequency domain signals of the line starting end and the line ending end through the frequency domain phase difference arithmetic unit with inherent noise is as follows:
firstly, calculating the phase of each frequency point of a starting end of a line:
（14）；
In the method, in the process of the invention, Representation ofIs a phase of (2);
calculating the phase of each frequency point at the line termination end:
（15）；
In the method, in the process of the invention, Representation ofIs a phase of (2);
Calculating phase difference between line start end and line end ：
（16）；
Under a certain time delay, the phase difference is proportional to the frequency, and the normalized phase difference is used for deriving the time delay:
（17）；
In the method, in the process of the invention, Representing the normalized phase difference;
Taking the accumulated value of the normalized phase difference to obtain time delay data under different lengths of a line starting end and a line terminating end, wherein the time delay data is expressed as:
（18）；
In the method, in the process of the invention, Representing the noise transmission time between the line start and line end.
7. The method for detecting sag of a power transmission line based on noise inherent to the power transmission line according to claim 6, wherein: the convolutional neural network adopted in the step S5 is based on a feedback mechanism and consists of a three-layer coupling structure of a training layer, a detection layer and a feedback adjusting layer, so that information interaction is realized.
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| RU2494511C1 (en) * | 2012-04-27 | 2013-09-27 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Казанский государственный энергетический университет" (ФГБОУ ВПО "КГЭУ") | Method to monitor sagging of power transmission line wire |
| CN105974423A (en) * | 2016-04-27 | 2016-09-28 | 中国科学技术大学先进技术研究院 | Power transmission line sag measurement method based on ultrasonic distance measuring and system thereof |
| CN108344923B (en) * | 2018-01-19 | 2024-01-16 | 国家电网公司 | High-adaptability power transmission line fault location method and system |
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| CN103344170A (en) * | 2013-06-26 | 2013-10-09 | 西安工程大学 | High voltage transmission conductor sag measuring device and method |
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