CN111308234A - Method for extracting S-transform power quality disturbance characteristics of Blackman window and window width ratio - Google Patents
Method for extracting S-transform power quality disturbance characteristics of Blackman window and window width ratio Download PDFInfo
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- CN111308234A CN111308234A CN201911250742.9A CN201911250742A CN111308234A CN 111308234 A CN111308234 A CN 111308234A CN 201911250742 A CN201911250742 A CN 201911250742A CN 111308234 A CN111308234 A CN 111308234A
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Abstract
The invention discloses an S-transform power quality disturbance feature extraction method of a Blackman window and window width ratio, which comprises the following steps: s1, collecting power quality disturbance signals; s2, transforming the disturbance signal by using S based on the Blackman window and the window width ratio; s3, extracting a characteristic curve of a complex disturbance signal, the method is scientific and reasonable in structure and safe and convenient to use, compared with the conventional electric energy quality disturbance characteristic extraction method, the method adopts the steps of respectively extracting characteristics, namely a frequency amplitude curve, a high-frequency part of the frequency amplitude curve and a third harmonic amplitude curve from three aspects, and extracting the characteristics of a peak and a trapped wave from the third harmonic, so that the interference of other disturbances on the characteristics of the peak and the trapped wave is reduced, the characteristic separation is realized, the mutual interference among the characteristics of the complex disturbance is reduced, the interference among the mutual characteristics is reduced due to the realization of the characteristic separation of different component disturbances in the complex disturbance, a solid foundation is laid for the disturbance identification and classification, and the accuracy of the disturbance identification and classification is greatly improved.
Description
Technical Field
The invention relates to the technical field of electric energy quality disturbance feature extraction, in particular to an S-transform electric energy quality disturbance feature extraction method of a Blackman window and window width ratio.
Background
At present, new energy is vigorously developed, the ratio of photovoltaic power generation and wind power generation to the energy is larger, the output of the new energy is not stable enough, and the problems of voltage spike, voltage wave trap, higher harmonic and the like exist in a power system due to the fact that a large number of power electronic equipment are used through electric energy storage and conversion, and multiple kinds of simultaneously-generated electric energy quality disturbance exist in the power system due to the fact that a complex load is connected, and the complex electric energy quality disturbance feature extraction is very important as the basis of electric energy quality evaluation and management;
the method comprises the following steps of signal processing, characteristic separation and extraction, wherein the two steps are signal processing, characteristic separation and extraction, the commonly used power quality disturbance signal processing mainly comprises Fourier transform, wavelet transform, S transform, Hilbert-Huang transform and the like.
Disclosure of Invention
The invention provides an S-transform power quality disturbance feature extraction method of a Blackman window and window width ratio, which can effectively solve the problems that the accuracy of disturbance identification and classification cannot be improved and the interference between mutual features cannot be reduced in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: the extraction method of the S-transform power quality disturbance characteristics of the Blackman window and window width ratio comprises the following steps:
s1, collecting power quality disturbance signals;
s2, transforming the disturbance signal by using S based on the Blackman window and the window width ratio;
and S3, extracting a complex disturbance signal characteristic curve.
According to the technical scheme, in the step S1, the voltage, the current transformer and the secondary device in the transformer substation are used for collecting and recording the relevant disturbance signals.
According to the above technical solution, when n ≠ 0 in step S2:
when n is 0:
wherein j, m, N is 0,1, …, N-1.
Indicating rounding up. GB(m,n,fs) Is omegaBThe discretized expression of (1):
the frequency range of the low-frequency part is more than or equal to f and is 1HzLN of S-transform discrete expression based on Blackman window and window width ratio not more than 100HzLThe value range of (1) is NT less than or equal to nLThe parameter of less than or equal to 100NT is gammaBL＝1.46875；
The frequency range of the high-frequency part is more than or equal to f and is 101HzHN is less than or equal to 6400Hz and is based on the S transformation discrete expression of the Blackman window and the window width ratioHHas a value range of 101NT ≤ nHThe parameter of < 6400NT is gammaBH＝3。
According to the above technical solution, in the step S2, the result of the S transformation based on the blackman window-to-window ratio is a complex matrix, and a modulus is taken for each element of the matrix to obtain a modulus matrix based on the S transformation of the blackman window-to-window ratio. The modulo matrix column represents the sampling time and the row represents the frequency.
According to the above technical solution, the characteristic curve of the disturbance signal in step S3 is selected from three aspects:
a. a fundamental frequency amplitude curve, namely a row vector of which the S transformation mode matrix frequency is 50Hz based on a Blackman window and a window width ratio is taken;
b. a frequency amplitude high-frequency part curve, namely a frequency amplitude curve is a maximum value of each row of an S-conversion model based on a Blackman window and a window width ratio, and a range larger than 100Hz is selected on the basis of the frequency amplitude curve;
c. and adding third harmonic to the original signal according to a third harmonic amplitude curve, performing S transformation based on the Blackman window and window width ratio to obtain a mode matrix, and taking a row vector of which the S transformation mode matrix frequency is 150Hz based on the Blackman window and window width ratio.
Compared with the prior art, the invention has the beneficial effects that: the method has the advantages of scientific and reasonable structure, safe and convenient use, and compared with the traditional method for extracting the disturbance characteristics of the power quality, the method has the advantages that the characteristics, namely the frequency amplitude curve, the high-frequency part of the frequency amplitude curve and the third harmonic amplitude curve, are respectively extracted from three aspects, namely when the characteristics of the peak and the trapped wave are extracted, the third harmonic is added to the signal, the characteristics of the peak and the trapped wave are extracted from the third harmonic, the interference of other disturbances on the characteristics of the peak and the trapped wave is reduced, the characteristic separation is realized, the mutual interference among complex disturbance characteristics is reduced, the characteristic separation of different component disturbances in the complex disturbance is realized, the interference among the mutual characteristics is reduced, a solid foundation is laid for the disturbance identification and classification, and the accuracy of the disturbance identification and classification is greatly improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
In the drawings:
FIG. 1 is a schematic flow chart of the present invention;
FIG. 2 is a schematic diagram of the amplitude curve of the fundamental frequency of voltage interruption and the amplitude curve of the fundamental frequency of voltage sag of the present invention;
FIG. 3 is a schematic structural diagram of a transient fundamental frequency amplitude curve and a flicker fundamental frequency amplitude curve of the present invention;
FIG. 4 is a schematic diagram of the harmonic fundamental frequency amplitude curve and the transient oscillation fundamental frequency amplitude curve of the present invention;
FIG. 5 is a schematic of the peak third harmonic amplitude curve and the notch third harmonic amplitude curve of the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
Example (b): as shown in fig. 1, the invention provides a technical solution, and a method for extracting S-transform power quality disturbance characteristics of a blackman window and window width ratio, comprising the following steps:
s1, collecting power quality disturbance signals;
s2, transforming the disturbance signal by using S based on the Blackman window and the window width ratio;
and S3, extracting a complex disturbance signal characteristic curve.
According to the technical scheme, in the step S1, the voltage, the current transformer and the secondary equipment in the transformer substation are used for collecting and recording the related disturbance signals.
According to the above technical solution, when n ≠ 0 in step S2:
when n is 0:
wherein j, m, N is 0,1, …, N-1.
Indicating rounding up. GB(m,n,fs) Is omegaBFromThe scattering expression:
the frequency range of the low-frequency part is more than or equal to f and is 1HzLN of S-transform discrete expression based on Blackman window and window width ratio not more than 100HzLThe value range of (1) is NT less than or equal to nLThe parameter of less than or equal to 100NT is gammaBL＝1.46875；
The frequency range of the high-frequency part is more than or equal to f and is 101HzHN is less than or equal to 6400Hz and is based on the S transformation discrete expression of the Blackman window and the window width ratioHHas a value range of 101NT ≤ nHThe parameter of < 6400NT is gammaBH＝3。
According to the above technical solution, in step S2, the result of S transformation based on the blackman window-to-window ratio is a complex matrix, and a modulus is taken for each element of the matrix to obtain a modulus matrix based on S transformation of the blackman window-to-window ratio. The modulo matrix column represents the sampling time and the row represents the frequency.
According to the technical scheme, the characteristic curve of the disturbance signal in the step S3 is selected from three aspects:
a. a fundamental frequency amplitude curve, namely a row vector of which the S transformation mode matrix frequency is 50Hz based on a Blackman window and a window width ratio is taken;
b. a frequency amplitude high-frequency part curve, namely a frequency amplitude curve is a maximum value of each row of an S-conversion model based on a Blackman window and a window width ratio, and a range larger than 100Hz is selected on the basis of the frequency amplitude curve;
c. and adding third harmonic to the original signal according to a third harmonic amplitude curve, performing S transformation based on the Blackman window and window width ratio to obtain a mode matrix, and taking a row vector of which the S transformation mode matrix frequency is 150Hz based on the Blackman window and window width ratio.
As shown in fig. 2 to 5, the method for extracting the disturbance characteristics of the complex power quality by using the S transform based on the blackman window and the window width ratio in the specific embodiment includes:
a. generation of power quality disturbance raw data
Because the actual power quality signals can not completely reflect the diversity of the disturbance signals, the invention adopts the method of generating different types of power quality signals according to the simulation of a mathematical model, respectively and randomly generating 150 groups of disturbance signals, wherein the signal sampling frequency is 12.8kHz, and Gaussian white noise with the signal-to-noise ratio of 50dB is added into all the signals
b. S transformation based on Blackman window and window width ratio is carried out on original data
c. The characteristic curves required for extraction and classification are shown in fig. 2-5.
Compared with the prior art, the invention has the beneficial effects that: the method has the advantages of scientific and reasonable structure, safe and convenient use, and compared with the traditional method for extracting the disturbance characteristics of the power quality, the method has the advantages that the characteristics, namely the frequency amplitude curve, the high-frequency part of the frequency amplitude curve and the third harmonic amplitude curve, are respectively extracted from three aspects, namely when the characteristics of the peak and the trapped wave are extracted, the third harmonic is added to the signal, the characteristics of the peak and the trapped wave are extracted from the third harmonic, the interference of other disturbances on the characteristics of the peak and the trapped wave is reduced, the characteristic separation is realized, the mutual interference among complex disturbance characteristics is reduced, the characteristic separation of different component disturbances in the complex disturbance is realized, the interference among the mutual characteristics is reduced, a solid foundation is laid for the disturbance identification and classification, and the accuracy of the disturbance identification and classification is greatly improved.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The extraction method of the S-transform power quality disturbance characteristics of the Blackman window and window width ratio is characterized by comprising the following steps of: the method comprises the following steps:
s1, collecting power quality disturbance signals;
s2, transforming the disturbance signal by using S based on the Blackman window and the window width ratio;
and S3, extracting a complex disturbance signal characteristic curve.
2. The extraction method of the disturbance characteristics of the quality of the S-transform power with the Blackman window-to-window width ratio according to claim 1, wherein in the step S1, relevant disturbance signals are collected and recorded by using voltage transformers, current transformers and secondary equipment in a transformer substation.
3. The method for extracting a quality disturbance feature of an S-transform power with a blackman window-to-window ratio according to claim 1, wherein when n ≠ 0 in step S2:
when n is 0:
wherein j, m, N is 0,1, …, N-1.
Indicating rounding up. GB(m,n,fs) Is omegaBThe discretized expression of (1):
the frequency range of the low-frequency part is more than or equal to f and is 1HzLN of S-transform discrete expression based on Blackman window and window width ratio not more than 100HzLThe value range of (1) is NT less than or equal to nLThe parameter of less than or equal to 100NT is gammaBL＝1.46875；
The frequency range of the high-frequency part is more than or equal to f and is 101HzHN is less than or equal to 6400Hz and is based on the S transformation discrete expression of the Blackman window and the window width ratioHHas a value range of 101NT ≤ nHThe parameter of < 6400NT is gammaBH＝3。
4. The method for extracting the disturbance characteristics of the S-transform power quality of the Blackman window-to-window ratio according to claim 1, wherein the result of the S-transform based on the Blackman window-to-window ratio in the step S2 is a complex matrix, and a mode matrix of the S-transform based on the Blackman window-to-window ratio is obtained by performing a mode operation on each element of the matrix. The modulo matrix column represents the sampling time and the row represents the frequency.
5. The method for extracting disturbance characteristics of the quality of the S-transform power with Blackman window-to-window aspect ratio according to claim 1, wherein the characteristic curve of the disturbance signal in the step S3 is selected from three aspects:
a. a fundamental frequency amplitude curve, namely a row vector of which the S transformation mode matrix frequency is 50Hz based on a Blackman window and a window width ratio is taken;
b. a frequency amplitude high-frequency part curve, namely a frequency amplitude curve is a maximum value of each row of an S-conversion model based on a Blackman window and a window width ratio, and a range larger than 100Hz is selected on the basis of the frequency amplitude curve;
c. and adding third harmonic to the original signal according to a third harmonic amplitude curve, performing S transformation based on the Blackman window and window width ratio to obtain a mode matrix, and taking a row vector of which the S transformation mode matrix frequency is 150Hz based on the Blackman window and window width ratio.
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