CN109039379B - Power line communication signal filtering method - Google Patents
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- H—ELECTRICITY
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- H—ELECTRICITY
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Abstract
The invention provides a filtering method for a power line communication signal, which can effectively filter out pulse noise in the power line communication signal. The method comprises the following steps: acquiring a power line communication signal sequence, and converting the power line communication signal sequence into a two-dimensional signal; decomposing the two-dimensional signal, and obtaining a power line communication signal decomposition coefficient; determining a power line communication signal decomposition coefficient threshold according to the solved power line communication signal decomposition coefficient; judging whether the amplitude of the solved power line communication signal decomposition coefficient is larger than or equal to a power line communication signal decomposition coefficient threshold value or not, if so, taking the decomposition coefficient for filtering noise as the solved power line communication signal decomposition coefficient, and otherwise, taking the decomposition coefficient for filtering noise as a preset value; and generating a noiseless power line communication signal sequence by using the obtained decomposition coefficient for filtering the noise. The invention relates to the field of electric power.
Description
Technical Field
The invention relates to the field of electric power, in particular to a power line communication signal filtering method.
Background
Compared with various wired communication technologies, Power Line Communications (PLC) has the advantages of no need of rewiring, easy networking and the like, and has a wide application prospect. The power line communication technology is classified into Narrowband over power line (NPL) and Broadband over power line (BPL). The narrow-band power line communication refers to a power line carrier communication technology with the bandwidth limited to 3 k-500 kHz. Including the regulated bandwidth of CENELEC in Europe (3-148.5 kHz), the regulated bandwidth of the Federal Communications Commission (FCC) in the United states (9-490 kHz), the regulated bandwidth of the Association of Radio Industries and Businesses (ARIB) in Japan (9-450 kHz), and the regulated bandwidth of China (3-500 kHz). The narrow-band power line communication technology mostly adopts a single carrier modulation technology, such as a PSK technology, a DSSS technology, a Chirp technology and the like, and the communication speed is less than 1 Mbits/s. The broadband power line communication technology refers to a power line carrier communication technology with the bandwidth limited between 1.6-30 MHz and the communication rate generally above 1Mbps, and adopts various spread spectrum communication technologies with Orthogonal Frequency Division Multiplexing (OFDM) as a core.
Although power line communication systems are widely used and the technology is relatively mature, the large number of branches and electrical equipment in the power line communication system generate a large amount of noise in the power line channel. The random impulse noise has high randomness and high noise intensity, and causes serious damage to a power line communication system.
With the application and popularization of nonlinear electrical appliances (such as a juicer, a coffee maker, a soybean milk maker and the like using a motor), more and more pulse noises appear in PLC signals, the instantaneous power of the noises is very high, and the noises have obvious non-stationarity and non-Gaussian characteristics, so that a low-pass filter used in the prior art has poor performance in the aspect of filtering the pulse noises, and the performance of a PLC system is seriously influenced.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a power line communication signal filtering method to solve the problem that a low-pass filter in the prior art cannot effectively filter out pulse noise in a power line communication signal.
In order to solve the above technical problem, an embodiment of the present invention provides a power line communication signal filtering method, including:
acquiring a power line communication signal sequence, and converting the power line communication signal sequence into a two-dimensional signal;
decomposing the two-dimensional signal, and obtaining a power line communication signal decomposition coefficient;
determining a power line communication signal decomposition coefficient threshold according to the solved power line communication signal decomposition coefficient;
judging whether the amplitude of the solved power line communication signal decomposition coefficient is larger than or equal to a power line communication signal decomposition coefficient threshold value or not, if so, taking the decomposition coefficient for filtering noise as the solved power line communication signal decomposition coefficient, and otherwise, taking the decomposition coefficient for filtering noise as a preset value;
and generating a noiseless power line communication signal sequence by using the obtained decomposition coefficient for filtering the noise.
Further, the acquiring the power line communication signal sequence and converting the power line communication signal sequence into a two-dimensional signal includes:
acquiring power line communication signal sequences P (1), P (2), …, P (N), and converting the power line communication signal sequences into a matrix form to obtain a signal matrix, wherein N is the length of the power line communication signal sequences;
the signal matrix is converted into a two-dimensional signal.
Further, the acquiring power line communication signal sequences P (1), P (2), …, P (n), and converting them into a matrix form to obtain a signal matrix includes:
according to the sequence of the power line communication signal sequences P (1), P (2), …, P (N), the power is transmittedThe line communication signal sequence P (1), P (2), …, P (N) is divided into NRSegments, each segment containing NCThe number of the data is one,wherein, the symbolRepresenting upper rounding;
if N is present<NR×NCZero-filling the deficient part of the last section;
rearranging the segmented data into a matrix form, wherein one segment of data is one row to obtain a signal matrix
Further, the two-dimensional signal obtained after conversion is:
nr=1,2,…,NR
nc=1,2,…,NC
wherein,a two-dimensional signal is represented by,representing a signal matrixN of (2)rLine, n-thcColumn elements.
Further, the decomposing the two-dimensional signal and obtaining the power line communication signal decomposition coefficient includes:
by the formulaDecomposing the two-dimensional signal to obtain a power line communication signal decomposition coefficient
Wherein,represents a power line communication signal transformation operator,operator for representing power line communication signal transformationThe conjugate of (a) to (b),representing a parameter.
Further, power line communication signal transformation operatorThe calculation formula of (2) is as follows:
wherein,is composed ofWeight function in the domain, argument being Is composed ofWeight function in the domain, argument beingSuperscript i denotes imaginary units.
Further, the determining a power line communication signal decomposition coefficient threshold value according to the solved power line communication signal decomposition coefficient comprises:
calculating the mean value c of the power line communication signal decomposition coefficient amplitudemean;
Solving the mean square error sigma of the power line communication signal decomposition coefficient amplitude;
determining a power line communication signal decomposition coefficient threshold value tau: τ ═ cmean+0.712*σ。
Further, the decomposition coefficient for filtering noise is expressed as:
wherein,is a decomposition coefficient for filtering noise, and represents a decomposition coefficient of the power line communication signal after the noise has been filtered; | indicates the amplitude of the extracted |.
Further, the generating a noise-free power line communication signal sequence by using the obtained noise-filtered decomposition coefficient includes:
according to the obtained decomposition coefficient of the filtered noiseBy the formulaObtaining a noise-free power line communication signal
According to the obtained noiseless electricityForce line communication signalConstructing new signal matrix
The obtained signal matrixThe first row of data is used as a first section, the second row of data is used as a second section, and so on, the last row of data is used as a last section, the sections are connected in sequence, the N data in the front are intercepted to form a data sequence, and the data sequence is a noiseless power line communication signal sequence.
the technical scheme of the invention has the following beneficial effects:
in the scheme, a power line communication signal sequence is collected and converted into a two-dimensional signal; decomposing the two-dimensional signal, and obtaining a power line communication signal decomposition coefficient; determining a power line communication signal decomposition coefficient threshold according to the solved power line communication signal decomposition coefficient; judging whether the amplitude of the solved power line communication signal decomposition coefficient is larger than or equal to a power line communication signal decomposition coefficient threshold value or not, if so, taking the decomposition coefficient for filtering noise as the solved power line communication signal decomposition coefficient, and otherwise, taking the decomposition coefficient for filtering noise as a preset value; the obtained decomposition coefficient for filtering the noise is utilized to generate a noiseless power line communication signal sequence, so that the pulse noise in the power line communication signal is effectively and quickly filtered, but the high-fidelity function is realized on the useful signal, the distortion of the useful signal is not caused, and the performance of a power line communication system is improved.
Drawings
Fig. 1 is a schematic flowchart of a power line communication signal filtering method according to an embodiment of the present invention;
fig. 2 is a detailed flowchart of a power line communication signal filtering method according to an embodiment of the present invention;
fig. 3 is a schematic diagram of data segmentation and matrix arrangement provided in the embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention provides a filtering method for a power line communication signal, aiming at the problem that the existing low-pass filter cannot effectively filter out pulse noise in the power line communication signal.
As shown in fig. 1, a method for filtering a power line communication signal according to an embodiment of the present invention
S101, acquiring a power line communication signal sequence, and converting the power line communication signal sequence into a two-dimensional signal;
s102, decomposing the two-dimensional signal, and obtaining a power line communication signal decomposition coefficient;
s103, determining a power line communication signal decomposition coefficient threshold value according to the solved power line communication signal decomposition coefficient;
s104, judging whether the amplitude of the solved power line communication signal decomposition coefficient is larger than or equal to a power line communication signal decomposition coefficient threshold value, if so, taking the decomposition coefficient for filtering noise as the solved power line communication signal decomposition coefficient, and otherwise, taking the decomposition coefficient for filtering noise as a preset value;
and S105, generating a noiseless power line communication signal sequence by using the obtained decomposition coefficient of the filtered noise.
The filtering method of the power line communication signal, provided by the embodiment of the invention, is used for collecting a power line communication signal sequence and converting the power line communication signal sequence into a two-dimensional signal; decomposing the two-dimensional signal, and obtaining a power line communication signal decomposition coefficient; determining a power line communication signal decomposition coefficient threshold according to the solved power line communication signal decomposition coefficient; judging whether the amplitude of the solved power line communication signal decomposition coefficient is larger than or equal to a power line communication signal decomposition coefficient threshold value or not, if so, taking the decomposition coefficient for filtering noise as the solved power line communication signal decomposition coefficient, and otherwise, taking the decomposition coefficient for filtering noise as a preset value; the obtained decomposition coefficient for filtering the noise is utilized to generate a noiseless power line communication signal sequence, so that the pulse noise in the power line communication signal is effectively and quickly filtered, but the high-fidelity function is realized on the useful signal, the distortion of the useful signal is not caused, and the performance of a power line communication system is improved.
In order to better understand the power line communication signal filtering method according to the embodiment of the present invention, the power line communication signal filtering method is described in detail, as shown in fig. 2, the power line communication signal filtering method may specifically include the following steps:
a1, collecting power line communication signal sequence
The method comprises the steps of acquiring power line communication signal sequences P (1), P (2), …, P (N), wherein N is the length of the power line communication signal sequence, and the power line communication signal sequence can also be called as a power line communication data sequence.
A2, segmenting the power line communication signal sequences P (1), P (2), …, P (n) and rearranging the segmented data into a signal matrix P, the data segmentation and matrix arrangement being as shown in fig. 3.
A21, dividing the power line communication signal sequence P (1), P (2), …, P (N) into N according to the sequence of the power line communication signal sequence P (1), P (2), …, P (N)RSegments, each segment containing NCThe number of the data is one,wherein, the symbolMeaning that the upper rounding, for example,the purpose of this is that all data is involved in the operation and not discarded.
In general, N isR256 or 512 or 1024, in practical applications, NRThe value of (a) is determined by the actual application scenario.
A22 if N<NR×NCThe insufficient part of the last segment is zero-filled.
A23, rearranging the segmented data into matrix form, one segment of data is one row, so that the signal matrix P has N in totalRLine, NCThe column, signal matrix can be expressed as
nr=1,2,…,NR
nc=1,2,…,NC
Wherein,represents a power line communication signal transformation operator,operator for representing power line communication signal transformationThe conjugate of (a) to (b),representing a parameter.
In this embodiment, the power line communication signal transformation operatorThe calculation formula of (2) is as follows:
wherein,is composed ofWeight function in the domain, argument beingA gaussian function may be selected in general;is composed ofWeight function in the domain, argument beingThe superscript i denotes the imaginary unit whose square is equal to-1.
A5, determining a power line communication signal decomposition coefficient threshold, wherein the specific steps may include:
a51, obtaining a mean value c of the decomposition coefficient amplitude of the power line communication signalmean;
A52, solving the mean square error sigma of the amplitude of the power line communication signal decomposition coefficient;
a53, determining a power line communication signal decomposition coefficient threshold value tau: τ ═ cmean+0.712*σ。
A6, determining the decomposition coefficient for filtering noise
Wherein,is a decomposition coefficient for filtering noise, and represents a decomposition coefficient of the power line communication signal after the noise has been filtered; | indicates the amplitude of the extracted |.
A7, obtaining new power line communication signal
A71, the obtained decomposition coefficient for filtering noiseThe power line communication signal corresponding to the decomposition coefficient sequence is the required noiseless power line communication signal. Specifically, the method comprises the following steps:
according to the obtained decomposition coefficient of the filtered noiseBy the formulaObtaining a noise-free power line communication signal
a8, rearranging data to obtain a noiseless power line communication signal sequence
The obtained signal matrixThe first row of data is used as a first section, the second row of data is used as a second section, and so on, the last row of data is used as a last section, the sections are connected in sequence, the N data in the front are intercepted to form a data sequence, and the data sequence is a noiseless power line communication signal sequence.
The filtering method for the power line communication signals can effectively filter out pulse noise in the power line communication signals. After the noise is filtered, the signal-to-noise ratio of the PLC signal can be improved by about 3 dB.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (1)
1. A method for filtering a power line communication signal, comprising:
acquiring a power line communication signal sequence, and converting the power line communication signal sequence into a two-dimensional signal;
decomposing the two-dimensional signal, and obtaining a power line communication signal decomposition coefficient;
determining a power line communication signal decomposition coefficient threshold according to the solved power line communication signal decomposition coefficient;
judging whether the amplitude of the solved power line communication signal decomposition coefficient is larger than or equal to a power line communication signal decomposition coefficient threshold value or not, if so, taking the decomposition coefficient for filtering noise as the solved power line communication signal decomposition coefficient, and otherwise, taking the decomposition coefficient for filtering noise as a preset value;
generating a noiseless power line communication signal sequence by using the obtained decomposition coefficient for filtering the noise;
wherein, the acquiring the power line communication signal sequence and converting the power line communication signal sequence into a two-dimensional signal comprises:
acquiring power line communication signal sequences P (1), P (2), …, P (N), and converting the power line communication signal sequences into a matrix form to obtain a signal matrix, wherein N is the length of the power line communication signal sequences;
converting the signal matrix into a two-dimensional signal;
wherein, the acquiring power line communication signal sequences P (1), P (2), …, P (n), converting them into a matrix form, and obtaining a signal matrix includes:
according toThe sequence of the plc signal sequences P (1), P (2), …, P (N) is to divide the plc signal sequences P (1), P (2), …, P (N) into NRSegments, each segment containing NCThe number of the data is one,wherein, the symbolRepresenting upper rounding;
if N is present<NR×NCZero-filling the deficient part of the last section;
rearranging the segmented data into a matrix form, wherein one segment of data is one row to obtain a signal matrix
Wherein, the two-dimensional signal obtained after conversion is:
nr=1,2,…,NR
nc=1,2,…,NC
wherein,a two-dimensional signal is represented by,representing a signal matrixN of (2)rLine, n-thcA column element;
wherein, decomposing the two-dimensional signal, and obtaining the power line communication signal decomposition coefficient comprises:
by the formulaDecomposing the two-dimensional signal to obtain a power line communication signal decomposition coefficient
Wherein,represents a power line communication signal transformation operator,operator for representing power line communication signal transformationThe conjugate of (a) to (b),representing a parameter;
wherein the power line communication signal transformation operatorThe calculation formula of (2) is as follows:
wherein,is composed ofWeight function in the domain, argument being Is composed ofWeight function in the domain, argument beingSuperscript i represents the imaginary unit;
wherein, the determining the power line communication signal decomposition coefficient threshold value according to the solved power line communication signal decomposition coefficient comprises:
calculating the mean value c of the power line communication signal decomposition coefficient amplitudemean;
Solving the mean square error sigma of the power line communication signal decomposition coefficient amplitude;
determining a power line communication signal decomposition coefficient threshold value tau: τ ═ cmean+0.712*σ;
Wherein the decomposition coefficient for filtering noise is expressed as:
wherein,is a decomposition coefficient for filtering noise, and represents a decomposition coefficient of the power line communication signal after the noise has been filtered; | indicates the amplitude of the extracted |;
wherein, the generating a power line communication signal sequence without noise by using the obtained decomposition coefficient of the filtered noise comprises:
according to the obtained decomposition coefficient of the filtered noiseBy the formulaObtaining a noise-free power line communication signal
The obtained signal matrixTaking the first row of data as a first section, taking the second row of data as a second section, and so on, taking the last row of data as a last section, connecting the sections in sequence, and intercepting the front N data to form a data sequence, wherein the data sequence is a noiseless power line communication signal sequence;
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CN103020907A (en) * | 2012-12-04 | 2013-04-03 | 上海交通大学 | DSPI (digital speckle pattern interferometry) fringe filtering system based on BEEMD (bidimensional ensemble empirical mode decomposition) |
CN103398295A (en) * | 2013-07-04 | 2013-11-20 | 东北大学 | Device and method for compressing pipeline magnet leakage signal data |
CN105245240A (en) * | 2015-10-23 | 2016-01-13 | 国家电网公司 | Power microwave communication system wavelet noise reduction method |
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CN103020907A (en) * | 2012-12-04 | 2013-04-03 | 上海交通大学 | DSPI (digital speckle pattern interferometry) fringe filtering system based on BEEMD (bidimensional ensemble empirical mode decomposition) |
CN103398295A (en) * | 2013-07-04 | 2013-11-20 | 东北大学 | Device and method for compressing pipeline magnet leakage signal data |
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