CN109946512B  A kind of dynamic power analysis method for improving frequency domain interpolation  Google Patents
A kind of dynamic power analysis method for improving frequency domain interpolation Download PDFInfo
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 CN109946512B CN109946512B CN201910310434.4A CN201910310434A CN109946512B CN 109946512 B CN109946512 B CN 109946512B CN 201910310434 A CN201910310434 A CN 201910310434A CN 109946512 B CN109946512 B CN 109946512B
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Abstract
The invention discloses a kind of dynamic power analysis methods for improving frequency domain interpolation, it includes: a, obtains sinusoidal signal sequence X (n) to be analyzed to actual voltage signal and current signal progress discrete sampling；B, Fast Fourier Transform (FFT) is done to sinusoidal signal sequence X (n) to be analyzed, calculates frequency spectrum interpolation coefficient δ^{+}And δ；C, the frequency spectrum interpolation coefficient according to two neighbouring spectral line amplitudes of peak value spectral line, after calculating weightingD calculates the frequency, amplitude and phase of sinusoidal signal sequence X (n) to be analyzed: step e, and the amplitude and phase angle for obtaining contact potential series are denoted as A respectively_{u}And θ_{u}, amplitude, phase angle and the dynamic power of current sequence；When solving the prior art using Interpolating Window FFT Algorithm calculating frequency, error caused by the presence of the noninteger truncation because of nonsynchronous sampling or data, even if using interpolation algorithm, there is also ignoring negative frequency some effects, the problem for causing interpolation result precision not high.
Description
Technical field
The invention belongs to dynamic power analysis more particularly to a kind of dynamic power analysis methods for improving frequency domain interpolation.
Background technique
The continuous development of China's economy causes domestic electrical in great demand, the construction of remote, extensive power transmission network with
And a large amount of uses of various nonlinear loads, power quality problem are got worse.Electric system standard frequency in China's is 50Hz, electricity
Pressure, electric current are the standard sine wave of 50Hz, but since by various interference effects, in practical power systems, voltage is electric
It flows waveform and always generates distortion to varying degrees.Effective detection fundamental energy is asked as what expert and scholar increasingly paid close attention to
Topic.
Currently, power system signal frequency analysis application algorithm the most universal is Fast Fourier Transform (FFT) (FFT), however
When transformation, which occurs, for detected signal frequency leads to nonsynchronous sampling, there are fence effects and leakage phenomenon by FFT, so that calculate
Electric power signal parameter  frequency, amplitude and phase etc. are inaccurate, and especially phase error is very big, are unable to satisfy accurate measurement and want
It asks.In order to eliminate influence of the mains frequency variation to measurement, synchronized sampling can be realized using hardware phase lock high precision loop circuit；It can also be with
Fft algorithm is improved, the method for generalling use windowed function for spectral leakage solves, and fence effect is generallyd use
Interpolation algorithm improves.Common window function has rectangular window, quarter window, Hanning window, Blackman window, Blackman
Harris window, rectangle convolution window and maximum side lobe attenuation rate window etc..Common interpolation algorithm has singlet difference, using most general
Time double spectral line differences and three popular in recent years spectral line differences.
But when traditional Interpolating Window FFT Algorithm calculates frequency, there is the noninteger because of nonsynchronous sampling or data
Error caused by being truncated, even if, there is also negative frequency some effects are ignored, causing interpolation result precision not high using interpolation algorithm
The problem of.
Summary of the invention
The technical problem to be solved by the present invention is a kind of dynamic power analysis method for improving frequency domain interpolation is provided, with solution
When certainly the prior art calculates frequency using Interpolating Window FFT Algorithm, exist because nonsynchronous sampling or the noninteger of data are cut
Error caused by disconnected, even if, there is also negative frequency some effects are ignored, causing interpolation result precision not high using interpolation algorithm
Problem.
The technical scheme is that
A kind of dynamic power analysis method for improving frequency domain interpolation, it includes:
Step a carries out discrete sampling, sample frequency f to actual voltage signal u (t) and current signal i (t)_{s}, sampling
Points are N, obtain discrete voltage U_{0}(n) and current sequence I_{0}(n), n=0,1,2 ..., N1, using sinusoidal signal to be analyzed
Sequence X (n) indicates sampled discrete voltage or stray currents sequence；
Step b does Fast Fourier Transform (FFT), transformed discrete spectrum sequence to sinusoidal signal sequence X (n) to be analyzed
X (k) remembers that the serial number k of the peak value spectral line of X (k) is k_{0}, remember X (k_{0})=a+jb, X (k_{0}+ 1)=c+jd, X (k_{0} 1)=e+jf, meter
Calculate frequency spectrum interpolation coefficient δ^{+}And δ；
Step c, the frequency spectrum interpolation coefficient according to two neighbouring spectral line amplitudes of peak value spectral line, after calculating weighting
Step d calculates the frequency, amplitude and phase of sinusoidal signal sequence X (n) to be analyzed:
Step e, by discrete voltage, stray currents sequence U_{0}(n)、I_{0}(n) it substitutes into respectively in the formula of step b to step d,
The amplitude and phase angle for obtaining contact potential series are denoted as A respectively_{u}And θ_{u}, the amplitude and phase angle of current sequence be denoted as A respectively_{i}And θ_{i}, dynamic
Power is P=A_{i}A_{u}cos(θ_{u} θ_{i})。
Frequency spectrum interpolation coefficient δ described in step b^{+}And δCalculation formula are as follows:
Frequency spectrum interpolation coefficient after calculating weighting described in step c according to two neighbouring spectral line amplitudes of peak value spectral line's
Expression formula are as follows:
The frequency of sinusoidal signal sequence X (n) to be analyzed is calculated described in step dThe expression formula of amplitude A and phase theta point
Not are as follows:
The invention has the advantages that:
The present invention acquires sine voltage signal, current signal, calculates both direction with a kind of improved frequency domain interpolation method
Frequency spectrum interpolation coefficient, handle to obtain final frequency spectrum interpolation coefficient using weighting, final frequency interpolation coefficient brought into
The frequency that sinusoidal signal is calculated in Frequency Estimation formula, then calculates the amplitude and phase of voltage, electric current, finally calculates dynamic function
Rate, to realize measurement realtime to dynamic power, accurate.
FFT frequency domain interpolation frequency estimation algorithm is improved used by power measurement method of the present invention than traditional interpolation algorithm number
Learn that model is simple, and calculation amount is small, strong antijamming capability, especially when two neighbouring peak value spectral lines of peak value spectral line receive it is serious dry
Disturb, when generating dislocation, method disclosed by the invention due to using weighted interpolation method, remain to access accurate frequency,
Amplitude and phase calculation are as a result, so that it is guaranteed that the accuracy that dynamic power calculates.
When calculating frequency, there is the noninteger because of nonsynchronous sampling or data in traditional Interpolating Window FFT Algorithm
Error caused by being truncated, even if there is also ignore negative frequency portion using the bispectrum line being widely used at present, three spectral line interpolation algorithms
Dividing influences, the problem for causing interpolation result precision not high；Method disclosed by the invention in stepb, dexterously uses three phases
Adjacent amplitude maximum spectral line X (k_{0} 1), X (k_{0}) and X (k_{0}+ 1) real and imaginary parts construct the interpolation polynomial δ of both direction^{+}
And δ, by introducing the parameter of negative frequency part, it is obviously improved the accuracy of frequency domain interpolation result.
Metering electric energy method mathematical model proposed by the present invention is simple, and meter can be completed with simple MATLAB sentence
It calculates, convenient for being realized in engineer application.The metering electric energy method data processing journey that this patent is proposed can also be programmed with C language
Sequence downloads to program in mobile device, the metering of dynamic electrical power in life easy to produce.
When solving the prior art and calculating frequency using Interpolating Window FFT Algorithm, exist because of nonsynchronous sampling or data
Error caused by noninteger is truncated, even if, there is also negative frequency some effects are ignored, leading to interpolation knot using interpolation algorithm
The not high problem of fruit precision.
Detailed description of the invention
Fig. 1 is the method for the present invention program flow diagram；
Fig. 2 is specific embodiment voltage sample figure；
Fig. 3 is specific embodiment current sample figure；
Fig. 4 is specific embodiment contact potential series spectrogram；
Fig. 5 is specific embodiment current sequence spectrogram.
Specific embodiment
A kind of dynamic power analysis method for improving frequency domain interpolation, acquires sine voltage signal, current signal, is changed with one kind
Into frequency domain interpolation method calculate both direction frequency spectrum interpolation coefficient, handle to obtain final frequency spectrum interpolation system using weighting
Final frequency interpolation coefficient is brought in Frequency Estimation formula into the frequency for calculating sinusoidal signal, then calculates voltage, electric current by number
Amplitude and phase, finally calculate dynamic power, to realize measurement realtime to dynamic power, accurate, specifically include following step
It is rapid:
Step a carries out discrete sampling, sample frequency f to actual voltage signal u (t) and current signal i (t)_{s}, sampling
Points are N, obtain discrete voltage, current sequence U_{0}(n)、I_{0}(n), wherein n=0,1,2 ..., N1, for convenient for narration, subsequent step
Suddenly sampled discrete voltage or stray currents sequence are indicated with sinusoidal signal sequence x (n) to be analyzed；
Step b does Fast Fourier Transform (FFT), transformed discrete spectrum sequence to sinusoidal signal sequence x (n) to be analyzed
X (k) remembers that the serial number k of the peak value spectral line of X (k) is k_{0}, remember X (k_{0})=a+jb, X (k_{0}+ 1)=c+jd, X (k_{0} 1)=e+jf, meter
Calculate frequency spectrum interpolation coefficient δ^{+}And δ；
The method, it is characterised in that in step b, dexterously use three adjacent amplitude maximum spectral lines: X (k_{0} 1),
X(k_{0}) and X (k_{0}+ 1) real and imaginary parts construct the interpolation coefficient δ of both direction^{+}And δ, and frequency spectrum interpolation coefficient δ^{+}And δ's
Mathematical model is simple, calculation amount small needs 8 plus/minus methods, 8 multiplication and 2 divisions.Their expression formula are as follows:
Step c, the frequency spectrum interpolation coefficient according to two neighbouring spectral line amplitudes of peak value spectral line, after calculating weighting
The method, it is characterised in that the frequency in step c, after being weighted according to two neighbouring spectral line amplitudes of peak value spectral line
Compose interpolation coefficientExpression formula are as follows:
Step d calculates the frequency, amplitude and phase of sinusoidal signal sequence x (n) to be analyzed:
The method, it is characterised in that in step d, using the frequency spectrum interpolation coefficient after weightingTo calculate accordingly wait divide
The frequency of the sinusoidal signal sequence x (n) of analysisAmplitude A and phase theta, their expression formula are respectively as follows:
When calculating frequency, there is the noninteger because of nonsynchronous sampling or data in traditional Interpolating Window FFT Algorithm
Error caused by being truncated, even if there is also ignore negative frequency portion using the bispectrum line being widely used at present, three spectral line interpolation algorithms
Dividing influences, the problem for causing interpolation result precision not high.
Step e, by discrete voltage, stray currents sequence U_{0}(n)、I_{0}(n) step b is substituted into respectively to step d, obtains voltage
The amplitude and phase angle of sequence are denoted as A respectively_{u}And θ_{u}, the amplitude and phase angle of current sequence be denoted as A respectively_{i}And θ_{i}, dynamic power P
=A_{i}A_{u}cos(θ_{u} θ_{i})。
Specific embodiment:
The present embodiment introduces the ordinarily resident's household electricity interfered by 5 subharmonic using voltage, current transformer, here
Voltage, current transformer be exactly by voltage and current used in resident according to a certain percentage, be converted into corresponding amplitude analog letter
Number, to be suitable for the voltage value of A/D conversion.Release 16 of model MAX1166 of MAXIM company used in this patent by
Secondary approach type A/D converter has many advantages, such as that small in size, low in energy consumption, conversion speed is fast, precision is high.The characteristics of serial line interface, makes
It is connected directly with CPU, enormously simplifies the design in defeated people channel.After A/D is converted into digital signal, send to computer
In analyzed.
Specific reality process steps are as follows:
The first step, with f_{s}=3200 be voltage of the sample frequency to the practical resident living power utility interfered by quintuple harmonics
Signal u (t) and current signal i (t) carry out discrete sampling, sampling number N=128 in a power frequency period, obtain discrete voltage,
Current sequence U_{0}(n)、I_{0}(n) (n=0,2 ..., 127) as shown in Figure 2 and Figure 3, voltage U_{0}(n) and electric current I_{0}(n) value such as table 1
It is shown；
1 discrete voltage of table, the value of current sequence
Second step, to sinusoidal signal sequence U to be analyzed_{0}(n)、I_{0}(n) Fast Fourier Transform (FFT) is done, it is transformed discrete
Spectrum sequence U_{0}(k)、I_{0}(k) (k=0,1,2 ..., 127), obtained frequency spectrum is as shown in Figure 4, Figure 5.Remember U_{0}(k) peak value spectral line
Serial number k be k_{u0}, the k in the voltage spectrum sequence_{u0}=3,
Then U_{0}(k_{u0})=a+jb=U_{0}(3)=1239.252819769.0300i
U_{0}(k_{u0}+ 1)=c+jd=U_{0}(4)= 36.2848+471.7011i
U_{0}(k_{u0} 1)=e+jf=U_{0}(2)=15.9699261.8091i
By a=1239.2528, b=19769.0300, c=36.2848, d=471.7011, e=15.9699, f=
261.8091 bring formula (1), (2) middle frequency spectrum interpolation coefficient δ for calculating contact potential series into_{u} ^{+}And δ_{u}:
Remember I_{0}(k) the serial number k of peak value spectral line is k_{i0}, the k in the current spectrum sequence_{i0}=3,
Then I_{0}(k_{i0})=a+jb=I_{0}(3)=28.3751449.8248i
I_{0}(k_{i0}+ 1)=c+jd=I_{0}(4)= 0.5687+9.8857i
I_{0}(k_{i0} 1)=e+jf=I_{0}(2)=0.54806.2068i
By a=28.3751, b=449.8248, c=0.5687, d=9.8857, e=0.5480, f=6.2068
Bring formula (3), (4) middle frequency spectrum interpolation coefficient δ for calculating current sequence into_{i} ^{+}And δ_{i}:
Third step, the frequency spectrum interpolation system according to two neighbouring spectral line amplitudes of peak value spectral line, after contact potential series weights respectively
NumberWith the frequency spectrum interpolation coefficient after current sequence weighting
4th step calculates the frequency of contact potential seriesAmplitude A_{u}And phase theta_{u}, their expression formula is respectively as follows:
5th step, the frequency of calculating current sequenceAmplitude A_{i}And phase theta_{i}, their expression formula is respectively as follows:
6th step, the discrete voltage sequence U that will be acquired_{0}(n) voltage magnitude and voltage phase angle, stray currents sequence I_{0}(n)
Current amplitude and current phase angle bring into formula (13), calculate dynamic power P:
This area is to the fundamental voltage amplitude for the normal voltage that resident suppliesThe fundamental voltage amplitude of electric current isThe frequency of practical fundamental wave when being disturbed is 50.5Hz.Voltage letter is calculated using method disclosed in this patent
Number amplitude be 310.2965V, with institute's supply standard voltage magnitudeError be only 0.2669%, calculate gained
The frequency of voltage signal is 50.4948Hz, and the error with actual frequency 50.5Hz is only 0.0103%；Using disclosed in this patent
Method be calculated current signal amplitude be 7.0585A, with institute's supply standard current amplitudeError be only
0.1770%；The frequency for calculating gained current signal is 50.4652Hz, and the error with actual frequency 50.5Hz is only
0.0690%.
The method accuracy disclosed by the invention for improving frequency domain interpolation calculating dynamic power is higher, is calculated using this method
The frequency of sinusoidal signal, error only has ten thousand/and it is several.Calculating the amplitude of sinusoidal signal using this method, error only has thousand/
It is several.
When calculating frequency, there is the noninteger because of nonsynchronous sampling or data in traditional Interpolating Window FFT Algorithm
Error caused by being truncated, even if there is also ignore negative frequency portion using the bispectrum line being widely used at present, three spectral line interpolation algorithms
Dividing influences, the problem for causing interpolation result precision not high.
Method disclosed in this patent in stepb, dexterously uses three adjacent amplitude maximum spectral line X (k_{0} 1),
X(k_{0}) and X (k_{0}+ 1) real and imaginary parts construct the interpolation polynomial δ of both direction^{+}And δ, by introducing negative frequency part
Parameter is obviously improved the accuracy of frequency domain interpolation result.
Employed in metering electric energy method proposed by the invention, FFT interpolation frequency estimation algorithm is improved than tradition
Interpolation algorithm mathematical model is simple, and calculation amount is small, strong antijamming capability, especially when two neighbouring peak value spectral lines of peak value spectral line are received
To severe jamming, when generating dislocation, the method as disclosed in this patent is in step c with using weighted interpolation method, root
Frequency spectrum interpolation coefficient after being weighted according to two neighbouring spectral line amplitudes of peak value spectral lineIt remains to access accurate frequency
Rate, amplitude and phase calculation are as a result, so that it is guaranteed that the accuracy that dynamic power calculates.
Metering electric energy method mathematical model proposed by the invention is simple, and meter can be completed with simple MATLAB sentence
It calculates, convenient for being realized in engineer application.The metering electric energy method data processing journey that this patent is proposed can also be programmed with C language
Sequence downloads to program in mobile device, the metering of dynamic electrical power in life easy to produce.
Claims (1)
1. a kind of dynamic power analysis method for improving frequency domain interpolation, it includes:
Step a carries out discrete sampling, sample frequency f to actual voltage signal u (t) and current signal i (t)_{s}, sampling number is
N obtains discrete voltage U_{0}(n) and current sequence I_{0}(n), n=0,1,2 ..., N1, using sinusoidal signal sequence X to be analyzed
(n) sampled discrete voltage or stray currents sequence are indicated；
Step b does Fast Fourier Transform (FFT), transformed discrete spectrum sequence X to sinusoidal signal sequence X (n) to be analyzed
(k), remember that the serial number k of the peak value spectral line of X (k) is k_{0}, remember X (k_{0})=a+jb, X (k_{0}+ 1)=c+jd, X (k_{0} 1)=e+jf, meter
Calculate frequency spectrum interpolation coefficient δ^{+}And δ；k_{0} 1 and k_{0}+ 1 respectively represents adjacent spectral line before and after peak value spectral line；
Frequency spectrum interpolation coefficient δ described in step b^{+}And δCalculation formula are as follows:
Step c, the frequency spectrum interpolation coefficient according to two neighbouring spectral line amplitudes of peak value spectral line, after calculating weightingDescribed in step c
Frequency spectrum interpolation coefficient after calculating weighting according to two neighbouring spectral line amplitudes of peak value spectral lineExpression formula are as follows:
Step d calculates the frequency, amplitude and phase of sinusoidal signal sequence X (n) to be analyzed:
The frequency of sinusoidal signal sequence X (n) to be analyzed is calculated described in step dThe expression formula of amplitude A and phase theta is respectively as follows:
Step e, by discrete voltage, stray currents sequence U_{0}(n)、I_{0}(n) it substitutes into the formula of step b to step d, obtains respectively
The amplitude and phase angle of contact potential series are denoted as A respectively_{u}And θ_{u}, the amplitude and phase angle of current sequence be denoted as A respectively_{i}And θ_{i}, dynamic power
For P=A_{i}A_{u}cos(θ_{u} θ_{i})。
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JP2001042033A (en) *  19990730  20010216  Fujitsu Ten Ltd  Peak frequency computing method in fft signal processing 
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