CN104535855A - Electric energy quality disturbing signal detecting algorithm based on discrete orthogonal S transformation - Google Patents

Electric energy quality disturbing signal detecting algorithm based on discrete orthogonal S transformation Download PDF

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Publication number
CN104535855A
CN104535855A CN201410785364.5A CN201410785364A CN104535855A CN 104535855 A CN104535855 A CN 104535855A CN 201410785364 A CN201410785364 A CN 201410785364A CN 104535855 A CN104535855 A CN 104535855A
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China
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transformation
orthogonal
discrete orthogonal
beta
frequency
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CN201410785364.5A
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Inventor
张学东
赵庆生
包同岗
赵志
李鹏
孙凯
王振起
王宇
韩肖清
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State Grid Corp of China SGCC
Jinzhong Power Supply Co of State Grid Shanxi Electric Power Co Ltd
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State Grid Corp of China SGCC
Jinzhong Power Supply Co of State Grid Shanxi Electric Power Co Ltd
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Abstract

The invention relates to a detecting method of power grid disturbing signals in an electric power system, in particular to an electric energy quality disturbing signal detecting algorithm based on discrete orthogonal S transformation. The algorithm comprises the steps that after a frequency variable (representing the center of a frequency band) and the width and time variable (representing a time point) of the frequency band are introduced based on traditional S transformation, discretization orthogonalization processing is carried out on time-domain signals, discrete orthogonal S transformation is obtained, then discrete orthogonal S transformation is applied to carrying out time-frequency analysis on several common electric energy quality disturbing signals, an obtained discrete orthogonal S transformation coefficient matrix is used for locating start and stop disturbing moments, and finally the disturbing signals are detected. According to the algorithm, the start and stop moments of the disturbing signals can be detected accurately and effectively, a new thought is provided for electric energy quality disturbing signal detecting, and development of a disturbing signal analysis method is facilitated.

Description

A kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation
Technical field
The present invention relates to the detection method of grid disturbance signal in electric system, be specially a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation.
Background technology
Power quality problem is all a problem received much concern all the time, and in the middle of many power quality problems, complicated Power Quality Disturbance stands in the breach.A large amount of power electronic devices and the use of nonlinear element can produce disturbing signal, detect the start/stop time of these disturbing signals quickly and accurately, for guarantee with improve the quality of power supply most important.
At present, short time discrete Fourier transform (STFT), wavelet transformation, neural network, S-transformation are the methods of common detection Power Quality Disturbance, for non-static signals, short time discrete Fourier transform be limited to window function fixed width and can not the high and low frequency composition of detection signal dynamically; Wavelet transformation is by variable window function, although more effectively can detect the frequency content of non-static signals, not good for time domain disturbing signal (such as voltage swell, fall temporarily) Detection results; Although neural network effectively can carry out time frequency analysis, first need to train, and need a large amount of prior imformations, therefore calculated amount is comparatively large, and algorithm is complicated, poor real; S-transformation alternatively effectively can analyze the method for time-frequency domain signal, be similar to continuous wavelet transform, but the regulatory factors such as the position of its Gauss function and width are fixed, and cause its adaptive ability poor, time-frequency complex matrixs a large amount of in algorithmic procedure too increases algorithm complex.
More than analyze known, in order to overcome the various problems that traditional time frequency analysis algorithm exists, find a kind of algorithm relatively simple, frequency resolution is high, and the algorithm that accuracy is good is crucial.
Summary of the invention
The present invention effectively can not detect the problem of the start/stop time of disturbing signal in order to the method solving traditional detection Power Quality Disturbance, provide a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, this algorithm is applicable to duration power quality disturbances, frequency resolution is high, algorithm is easy, and accuracy is good.
The present invention adopts following technical scheme to realize: a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, comprises the following steps:
S1: to Power Quality Disturbance emulation, obtain disturbing signal h (t), and disturbing signal h (t) is sampled;
S2: carry out Discrete Orthogonal S-transformation to the disturbing signal h (t) sampled, obtains Discrete Orthogonal S-transformation matrix of coefficients, draws disturbing signal waveform according to matrix of coefficients;
S3: according to the disturbing signal waveform of matrix of coefficients and drafting, the initial time of amplitude change in final Location perturbation signal and end time.
Above-mentioned a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, the Discrete Orthogonal S-transformation in described S2 comprises the following steps:
Step one: by the disturbing signal h (t) that sampled through fast fourier transform, obtain frequency-region signal H (f);
Step 2: the width beta of setpoint frequency variable ν, frequency band and time variable τ tri-variablees, then composes initial value to these three variablees, and constructs N number of orthogonal S-transformation basis function vector;
Step 3: create Ramp matrix, in Ramp matrix, element is positive and negative one alternately to occur, namely [-1,1 ,-1,1 ... ];
Step 4: by frequency-region signal H (f) in step one after inverse Fourier transform, is multiplied with the orthogonal S-transformation basis function vector that step 2 obtains, then with the Ramp matrix multiple in step 3; Obtain Discrete Orthogonal S-transformation matrix of coefficients;
Step 5: the Discrete Orthogonal S-transformation matrix of coefficients that step 4 obtains draw in MATLAB carry out visual.
Above-mentioned a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, composes initial value to the width beta of frequency variable ν, frequency band and time variable τ tri-variablees in described step 2 and follows following provisions: τ=0,1 ... β-1; Choosing of ν and β must ensure that the use of each Frequency point once and only uses once, and specify and facilitate three variable assignments more than meeting, introduce variable p, assignment condition is as follows: p=2 ..., log 2(N)-1, ν=2 (p-1)+ 2 (p-2), β=2 (p-1), τ=0,1 ..., 2 (p-1)-1.
Above-mentioned a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, after composing initial value to the width beta of frequency variable ν, frequency band and time variable τ tri-variablees in step 2, according to the N number of orthogonal S-transformation basis function vector of following formula construction: S [ k ] [ v , β , τ ] = 1 β Σ f = v - β 2 v + β 2 - 1 exp ( i - 2 π k N f ) exp ( i 2 π τ β f ) exp ( - iπτ ) , S [k] in formula [ν, β, τ]represent a kth orthogonal S-transformation basis function vector.
Compared with prior art, the present invention introduces ν, β and τ tri-variablees, makes discretize orthogonalization process to S-transformation, by greatly improving frequency resolution to whole traversals of time parameter; By sliding-model control signal, reduce operand; Discrete Orthogonal S-transformation is used to carry out analyzing and processing to several Power Quality Disturbance, extract the actual parameter of disturbing signal, draw Discrete Orthogonal S-transformation matrix of coefficients figure, accurately detect the disturbance moment, provide a kind of new thinking for Power Quality Disturbance detects, be beneficial to the development of disturbing signal analytical approach.
Accompanying drawing explanation
Fig. 1 is algorithm flow chart of the present invention;
Fig. 2-Fig. 6 is Discrete Orthogonal S-transformation disturbing signal analysis result figure, and wherein Fig. 2 is that voltage swell falls analysis result temporarily; Fig. 3 is voltage oscillation analysis result; Fig. 4 is pulse signal analysis result; Fig. 5 is voltage interruption analysis result; Fig. 6 is that the voltage swell containing harmonic wave falls analysis result temporarily.
Embodiment
Based on a Power Quality Disturbance detection algorithm for Discrete Orthogonal S-transformation, comprise the following steps:
S1: utilize MATLAB software to emulate Power Quality Disturbance, obtain disturbing signal h (t), and disturbing signal h (t) is sampled;
S2: carry out Discrete Orthogonal S-transformation to the disturbing signal h (t) sampled, obtains Discrete Orthogonal S-transformation matrix of coefficients, draws disturbing signal waveform according to matrix of coefficients;
S3: according to the waveform of matrix of coefficients and drafting, the initial sum end time of amplitude change in final Location perturbation signal.
Above-mentioned a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, the Discrete Orthogonal S-transformation in described S2 comprises the following steps:
Step one: by the disturbing signal h (t) that sampled through fast fourier transform, obtain frequency-region signal H (f);
Step 2: the width beta of setpoint frequency variable ν, frequency band and time variable τ tri-variablees, then composes initial value to these three variablees, and constructs N number of orthogonal S-transformation basis function vector;
Step 3: create Ramp matrix, in Ramp matrix, element is positive and negative one alternately to occur, namely [-1,1 ,-1,1 ... ];
Step 4: by frequency-region signal H (f) in step one after inverse Fourier transform, is multiplied with the orthogonal S-transformation basis function vector that step 2 obtains, then with the Ramp matrix multiple in step 3; Obtain Discrete Orthogonal S-transformation matrix of coefficients;
Step 5: the Discrete Orthogonal S-transformation matrix of coefficients that step 4 obtains draw in MATLAB carry out visual.
Above-mentioned a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, composes initial value to the width beta of frequency variable ν, frequency band and time variable τ tri-variablees in described step 2 and follows following provisions: τ=0,1 ... β-1; Choosing of ν and β must ensure that the use of each Frequency point once and only uses once, and specify and facilitate three variable assignments more than meeting, introduce variable p, assignment condition is as follows: p=2 ..., log 2(N)-1, ν=2 (p-1)+ 2 (p-2), β=2 (p-1), τ=0,1 ..., 2 (p-1)-1.
Above-mentioned a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation, after composing initial value to the width beta of frequency variable ν, frequency band and time variable τ tri-variablees in step 2, according to the N number of orthogonal S-transformation basis function vector of following formula construction: S [ k ] [ v , β , τ ] = 1 β Σ f = v - β 2 v + β 2 - 1 exp ( i - 2 π k N f ) exp ( i 2 π τ β f ) exp ( - iπτ ) , S [k] in formula [ν, β, τ]represent a kth orthogonal S-transformation basis function vector.
During concrete enforcement, the conversion process of Discrete Orthogonal S-transformation is: the S-transformation of disturbing signal h (t) is defined as follows: S { h ( t ) } = ∫ - ∞ ∞ h ( t ) | f | 2 π e ( τ - t ) 2 f 2 2 e - i 2 πft dt , In formula, | f | 2 π e ( τ - t ) 2 f 2 / 2 For Gauss function, be also frequency sensitive window function simultaneously, for high band, Gaussian window width relative narrower; For low-frequency range, Gaussian window width is relatively wide; Above-mentioned expression formula is transformed into Fourier: S { τ , f } = ∫ - ∞ ∞ H ( α + f ) e - 2 π 2 α 2 f 2 e i 2 παt dα , Wherein: H ( α + f ) = ∫ - ∞ ∞ h ( t ) e - i 2 π ( α + f ) t dt , Sliding-model control is carried out to above formula, obtains N point S-transformation formula: t=0 ..., N-1, introduces ν, β and τ tri-variablees, structure Discrete Orthogonal S-transformation basis function vector: S [ k ] [ v , β , τ ] = 1 β Σ f = v - β 2 v + β 2 - 1 exp ( i - 2 π k N f ) exp ( i 2 π τ β f ) exp ( - iπτ ) , Finally obtain the expression formula of the Discrete Orthogonal S-transformation of disturbing signal h (t): discrete Orthogonal S-transformation matrix of coefficients is calculated according to above formula.
Below voltage swell fallen temporarily, transient oscillation, pulse signal, voltage interruption, fall these five kinds of common Power Quality Disturbances temporarily containing the voltage swell of harmonic wave and carry out the analysis of Discrete Orthogonal S-transformation.Above-mentioned five kinds of disturbing signal fundamental frequencies are 50Hz, and the signal sampling time is 0.2 second, and sampling rate is 2560Hz, and sampling number is 512 points.Discrete Orthogonal S-transformation analysis result is shown in Fig. 2-Fig. 6.
1. voltage swell falls signal analysis temporarily: can find out in Fig. 2, between 148-153 sampled point, occurs obvious spike between 348-351 sampled point.The catastrophe point of amplitude is described, namely disturbance start/stop time is the 148th point and the 348th point respectively.
2. transient oscillation analysis: can find out in Fig. 3, there is spike in the 152nd point, in the middle part of the image of the 354th point, colour band interrupts.The start/stop time (the 152nd point and the 354th point) of oscillator signal disturbance can be found out clearly by figure.
3. pulse signal analysis: can find out in Fig. 4, there is spike in 262-265 sampled point.The catastrophe point of amplitude is described, namely disturbance start/stop time is the 262nd point and the 265th point respectively.
4., between 201-204 sampled point, between 304-307 sampled point, there is obvious spike in voltage interruption analysis: can find out in Fig. 5.The catastrophe point of amplitude is described, namely disturbance start/stop time is the 201st point and the 304th point respectively.
5. the voltage swell containing harmonic wave falls analysis temporarily: can find out in Fig. 6, between 193-196 sampled point, occur obvious spike between 358-360 sampled point.The catastrophe point of amplitude is described, namely disturbance start/stop time is the 193rd point and the 358th point respectively.

Claims (4)

1., based on a Power Quality Disturbance detection algorithm for Discrete Orthogonal S-transformation, it is characterized in that comprising the following steps:
S1: to Power Quality Disturbance emulation, obtain disturbing signal h (t), and disturbing signal h (t) is sampled;
S2: carry out Discrete Orthogonal S-transformation to the disturbing signal h (t) sampled, obtains Discrete Orthogonal S-transformation matrix of coefficients, draws disturbing signal waveform according to matrix of coefficients;
S3: according to the disturbing signal waveform of matrix of coefficients and drafting, the initial time of amplitude change in final Location perturbation signal and end time.
2. a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation according to claim 1, is characterized in that the Discrete Orthogonal S-transformation in described S2 comprises the following steps:
Step one: by the disturbing signal h (t) that sampled through fast fourier transform, obtain frequency-region signal H (f);
Step 2: the width beta of setpoint frequency variable ν, frequency band and time variable τ tri-variablees, then composes initial value to these three variablees, and constructs N number of orthogonal S-transformation basis function vector;
Step 3: create Ramp matrix, in Ramp matrix, element is positive and negative one and alternately occurs, namely [-1,1 ,-1,1 ... ];
Step 4: by frequency-region signal H (f) in step one after inverse Fourier transform, is multiplied with the orthogonal S-transformation basis function vector that step 2 obtains, then with the Ramp matrix multiple in step 3; Obtain Discrete Orthogonal S-transformation matrix of coefficients;
Step 5: the Discrete Orthogonal S-transformation matrix of coefficients that step 4 obtains draw in MATLAB carry out visual.
3. a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation according to claim 2, it is characterized in that composing initial value to the width beta of frequency variable ν, frequency band and time variable τ tri-variablees in described step 2 follows following provisions: τ=0,1 ... β-1; Choosing of ν and β must ensure that the use of each Frequency point once and only uses once.
4. a kind of Power Quality Disturbance detection algorithm based on Discrete Orthogonal S-transformation according to claim 2, after it is characterized in that composing initial value to the width beta of frequency variable ν, frequency band and time variable τ tri-variablees in step 2, according to the N number of orthogonal S-transformation basis function vector of following formula construction: S [ k ] [ v , β , τ ] = 1 β Σ f = v - β 2 v + β 2 - 1 exp ( - i 2 π k N f ) exp ( i 2 π τ β f ) exp ( - iπτ ) S [k] in formula [ν, β, τ]represent a kth orthogonal S-transformation basis function vector.
CN201410785364.5A 2014-12-17 2014-12-17 Electric energy quality disturbing signal detecting algorithm based on discrete orthogonal S transformation Pending CN104535855A (en)

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Application publication date: 20150422