CN105372489B - The method and system of any initial phase cosine function sequence is obtained from electric power signal - Google Patents
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Abstract
The present invention relates to a kind of method and system that any initial phase cosine function sequence is obtained from electric power signal, after obtaining zero initial phase benchmark cosine function modulation sequence and zero initial phase reference sinusoidal FUNCTION MODULATION sequence, initial phase is set, the cosine function of the initial phase is multiplied with the zero initial phase benchmark cosine function modulation sequence and obtains the first multiplication sequence, the SIN function of the initial phase is multiplied with the zero initial phase reference sinusoidal FUNCTION MODULATION sequence obtains the second multiplication sequence；First multiplication sequence is subtracted into second multiplication sequence, obtains the cosine function sequence of the initial phase.The initial phase that the present invention can set cosine function sequence according to being actually needed, influence of the list entries arbitrarily with uncertain initial phase problem is avoided, have positive effect to improving sine parameter accuracy in computation.
Description
Technical Field
The invention relates to the technical field of power systems, in particular to a method and a system for acquiring an arbitrary initial phase cosine function sequence from a power signal.
Background
The frequency measurement, the phase measurement, the amplitude measurement and the like of the power system are all the measurement of sine parameters in nature. Fast Fourier Transform (FFT) and Discrete Fourier Transform (DFT) algorithms are basic mathematical methods for sinusoidal parameter calculation, and have wide application in power systems. However, with the development of sinusoidal parameter measurement technology, the problems of the fast fourier transform algorithm and the discrete fourier transform algorithm are more prominent, and it is difficult to further meet the requirement of the power system on high accuracy calculation of sinusoidal parameters.
In the aspect of measuring sinusoidal parameters of the power system, improved parameter measuring methods such as a zero-crossing method, a filtering-based measuring method, a wavelet transformation-based measuring method, a neural network-based measuring method, a DFT transformation-based measuring method and the like exist. The rated power frequency of the power grid is near 50Hz (hertz), and the frequency is low sinusoidal. Due to the limitations of the actual signal processing technology and the complexity of signal composition, such as the influence of data quantization background noise generated by signal discrete sampling, the problem of spectrum leakage caused by signal sequence truncation is objectively difficult to avoid, the influence of the problem of arbitrary and uncertain initial phases of signals, the influence of the problems of direct current, subharmonic and subharmonic in the signals and the like, the measurement precision of the algorithms is low, and the harmonic and noise interference resistance is poor.
Disclosure of Invention
In view of the above, it is necessary to provide a method and system for acquiring an arbitrary initial phase cosine function sequence from a power signal, which can ensure high accuracy of sine parameter calculation.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for obtaining an arbitrary initial phase cosine function sequence from a power signal comprises the following steps:
obtaining a preliminary sequence length according to the lower limit of the power signal frequency range, a preset sampling frequency and a preset integer signal period number;
sampling the power signal according to the length of the preliminary sequence to obtain a preliminary sequence of the power signal;
carrying out frequency initial measurement on the initial sequence to obtain an initial frequency of the power signal, and obtaining a reference frequency according to the initial frequency;
obtaining the unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;
obtaining a preset sequence length according to the preset integer signal cycle number and the unit cycle sequence length, wherein the preset sequence length is an odd number;
obtaining a first forward sequence from the preliminary sequence according to the preset sequence length and a preset starting point, and obtaining a first reverse pleat sequence according to the first forward sequence;
obtaining a first positive phase from the first forward sequence and a first anti-phase from the first anti-aliasing sequence;
obtaining a first average initial phase according to the first positive phase and the first negative phase;
obtaining a phase comparison value according to the first average initial phase and a preset phase value, and obtaining a new initial point according to the phase comparison value, the preset initial point and the unit cycle sequence length;
according to the preset sequence length and the new starting point, obtaining a second forward sequence from the preliminary sequence, and obtaining a second reverse pleat sequence according to the second forward sequence;
obtaining a second positive phase from the second forward sequence and a second anti-phase from the second anti-aliased sequence;
obtaining a second average initial phase according to the second positive phase and the second negative phase;
adding the second forward sequence and the second inverse pleat sequence to obtain a sum sequence, and obtaining a cosine function modulation sequence according to the sum sequence and a cosine function value of the second average initial phase;
subtracting the second reverse-folding sequence from the second forward sequence to obtain a difference sequence, and obtaining a sine function modulation sequence according to the difference sequence and the sine function value of the second average initial phase;
outputting from the center point of the cosine function modulation sequence to obtain a zero initial phase reference cosine function modulation sequence, and outputting from the center point of the sine function modulation sequence to obtain a zero initial phase reference sine function modulation sequence;
setting an initial phase, multiplying the cosine function of the initial phase by the zero initial phase reference cosine function modulation sequence to obtain a first multiplication sequence, and multiplying the sine function of the initial phase by the zero initial phase reference sine function modulation sequence to obtain a second multiplication sequence;
and subtracting the second multiplication sequence from the first multiplication sequence to obtain a cosine function sequence of the initial phase.
A system for obtaining an arbitrary initial phase cosine function sequence from an electrical power signal, comprising:
the preliminary sequence length determining module is used for obtaining a preliminary sequence length according to the lower limit of the power signal frequency range, a preset sampling frequency and a preset integer signal period number;
the preliminary sequence acquisition module is used for sampling the electric power signal according to the length of the preliminary sequence to obtain a preliminary sequence of the electric power signal;
a reference frequency determining module, configured to perform frequency initial measurement on the preliminary sequence to obtain a preliminary frequency of the power signal, and obtain a reference frequency according to the preliminary frequency;
a unit cycle sequence length determining module, configured to obtain a unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;
a preset sequence length determining module, configured to obtain a preset sequence length according to the preset integer signal cycle number and the unit cycle sequence length, where the preset sequence length is an odd number;
a first sequence obtaining module, configured to obtain a first forward sequence from the preliminary sequence according to the preset sequence length and a preset starting point, and obtain a first anti-aliasing sequence according to the first forward sequence;
a first positive and negative phase determination module for obtaining a first positive phase from the first forward sequence and a first negative phase from the first deconvolution sequence;
a first average initial phase determining module, configured to obtain a first average initial phase according to the first positive phase and the first negative phase;
a new starting point determining module, configured to obtain a phase comparison value according to the first average initial phase and a preset phase value, and obtain a new starting point according to the phase comparison value, the preset starting point, and the unit cycle sequence length;
a second sequence obtaining module, configured to obtain a second forward sequence from the preliminary sequence according to the preset sequence length and the new starting point, and obtain a second inverse-folding sequence according to the second forward sequence;
a second forward-reverse phase determination module, configured to obtain a second positive phase according to the second forward sequence and obtain a second reverse phase according to the second deconvolution sequence;
a second average initial phase determining module, configured to obtain a second average initial phase according to the second positive phase and the second negative phase;
a cosine function modulation sequence determining module, configured to add the second forward sequence and the second inverse-pleated sequence to obtain a sum sequence, and obtain a cosine function modulation sequence according to the sum sequence and a cosine function value of the second average initial phase;
a sinusoidal function modulation sequence determining module, configured to subtract the second forward sequence from the second inverse-folding sequence to obtain a difference sequence, and obtain a sinusoidal function modulation sequence according to the difference sequence and a sinusoidal function value of the second average initial phase;
the zero initial phase modulation sequence acquisition module is used for outputting from the center point of the cosine function modulation sequence to acquire a zero initial phase reference cosine function modulation sequence and outputting from the center point of the sine function modulation sequence to acquire a zero initial phase reference sine function modulation sequence;
a multiplication sequence obtaining module, configured to set an initial phase, multiply the cosine function of the initial phase by the zero initial phase reference cosine function modulation sequence to obtain a first multiplication sequence, and multiply the sine function of the initial phase by the zero initial phase reference sine function modulation sequence to obtain a second multiplication sequence;
and the initial phase cosine function sequence determining module is used for subtracting the second multiplication sequence from the first multiplication sequence to obtain the initial phase cosine function sequence.
The method and the system for acquiring the cosine function sequence of any initial phase from the power signal can set the initial phase of the cosine function sequence according to actual needs, avoid the influence of the problem that the input sequence is arbitrary and uncertain, and have positive significance for improving the accuracy of sine parameter calculation.
Drawings
FIG. 1 is a schematic flow chart illustrating an embodiment of a method for obtaining an arbitrary initial phase cosine function sequence from an electrical signal according to the present invention;
FIG. 2 is a schematic representation of a preliminary sequence, a first forward sequence, and a first reverse pleat sequence of the present invention;
FIG. 3 is a schematic diagram of a zero initial phase reference point according to the present invention;
fig. 4 is a schematic structural diagram of a system for obtaining an arbitrary initial phase cosine function sequence from an electrical signal according to an embodiment of the present invention.
Detailed Description
In order to further explain the technical means and effects of the present invention, the following description of the present invention with reference to the accompanying drawings and preferred embodiments will be made for clarity and completeness.
As shown in fig. 1, a method for obtaining an arbitrary initial phase cosine function sequence from an electrical signal includes the steps of:
s101, obtaining a preliminary sequence length according to the lower limit of the power signal frequency range, a preset sampling frequency and a preset integer signal period number;
s102, sampling the electric power signal according to the length of the preliminary sequence to obtain the preliminary sequence of the electric power signal;
s103, carrying out frequency initial measurement on the initial sequence to obtain an initial frequency of the power signal, and obtaining a reference frequency according to the initial frequency;
s104, obtaining the unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;
s105, obtaining a preset sequence length according to the preset integer signal cycle number and the unit cycle sequence length, wherein the preset sequence length is an odd number;
s106, obtaining a first forward sequence from the preliminary sequence according to the preset sequence length and a preset starting point, and obtaining a first reverse pleat sequence according to the first forward sequence;
s107, obtaining a first positive phase according to the first forward sequence, and obtaining a first reverse phase according to the first reverse pleat sequence;
s108, obtaining a first average initial phase according to the first positive phase and the first negative phase;
s109, obtaining a phase comparison value according to the first average initial phase and a preset phase value, and obtaining a new initial point according to the phase comparison value, the preset initial point and the unit cycle sequence length;
s110, obtaining a second forward sequence from the preliminary sequence according to the preset sequence length and the new starting point, and obtaining a second reverse-pleat sequence according to the second forward sequence;
s111, obtaining a second positive phase according to the second positive sequence, and obtaining a second reverse phase according to the second reverse-folding sequence;
s112, obtaining a second average initial phase according to the second positive phase and the second negative phase;
s113, adding the second forward sequence and the second inverse pleat sequence to obtain a sum sequence, and obtaining a cosine function modulation sequence according to the sum sequence and a cosine function value of the second average initial phase;
s114, subtracting the second forward sequence from the second inverse pleat sequence to obtain a difference sequence, and obtaining a sine function modulation sequence according to the difference sequence and the sine function value of the second average initial phase;
s115, outputting from the center point of the cosine function modulation sequence to obtain a zero initial phase reference cosine function modulation sequence, and outputting from the center point of the sine function modulation sequence to obtain a zero initial phase reference sine function modulation sequence;
s116, setting an initial phase, multiplying the cosine function of the initial phase by the zero initial phase reference cosine function modulation sequence to obtain a first multiplication sequence, and multiplying the sine function of the initial phase by the zero initial phase reference sine function modulation sequence to obtain a second multiplication sequence;
and S117, subtracting the second multiplication sequence from the first multiplication sequence to obtain a cosine function sequence of the initial phase.
The actual power signal is a sinusoidal signal mainly composed of fundamental wave components, and if not specifically stated, the power signal refers to the fundamental wave signal, and the power signal frequency refers to the fundamental wave frequency. For step S101, the power system frequency range is generally 45Hz (Hertz) -55Hz, so the lower limit f of the power signal frequency rangeminMay be taken to be 45 Hz. Presetting integer signal period number C2πCan be set according to actual needs, for example, C2πTaken as 13. The preliminary sequence length may be calculated according to equation (1):
wherein N isstartIs the preliminary sequence length; (int) represents rounding; c2πIs a preset integer signal period number; f. ofminThe lower limit of the frequency range of the power signal, in Hz; f is the preset sampling frequency in Hz.
For step S102, the power signal can be expressed by a cosine function signal of a single fundamental frequency, and then the initial sequence is formula (2):
n＝0,1,2,3,.....,Nstart-1
wherein, Xstart(n) is a preliminary sequenceColumns; a is the signal amplitude in v; omegaiIs the signal frequency, T is the sampling interval time, f is the preset sampling frequency, the unit Hz, n is the sequence discrete number,for the initial phase of the preliminary sequence, NstartIs the preliminary sequence length.
For step S103, a frequency preliminary measurement may be performed on the preliminary sequence by a zero-crossing method, a filtering-based algorithm, a wavelet transform algorithm, a neural network-based algorithm, a DFT transform-based frequency algorithm, or a phase difference-based frequency algorithm to obtain a preliminary frequency ωo. In one embodiment, the reference frequency ωs＝ωo。
For step S104, in one embodiment, the length of the unit cycle sequence of the power signal is calculated as formula (3):
wherein N is2πIs the length of the unit period sequence; (int) is an integer; f is a preset sampling frequency in Hz; omegasIs the reference frequency. The unit period sequence length integer has an error within 1 sampling interval.
For step S105, the preset sequence length is odd, and in one embodiment, the preset sequence length is calculated by equation (4):
wherein, N is the length of the preset sequence, (int) is an integer, N2πIs the length of the unit period sequence, C2πIs a predetermined integer number of signal cycles.
For step S106, in an embodiment, the preset starting point may be 0.5 times the length of the unit cycle sequence, and the first forward sequence is represented by equation (5):
Pstart＝(int)(0.5N2π)
(5)
n＝0,1,2,3,.....,N-1
wherein, Xstart(n) is a preliminary sequence, X+start(n) is a first forward sequence, PstartTo a predetermined starting point, N2πIs the unit period sequence length, (int) is an integer, A is the signal amplitude, and the unit v, omegaiIs the signal frequency, T is the sampling interval time, n is the sequence discrete number,the sequence length is preset for the first forward sequence initial phase, N.
The first deconvolution sequence is of formula (6):
X-start(-n)＝X+start(N-n)＝Acos(-ωiTn+β1)
(6)
n＝0,1,2,3,.....,N-1
wherein, X-start(-n) is the first deconvolution sequence, X+start(n) is the first forward sequence, A is the signal amplitude in v, ωifor signal frequency, T is the sampling interval time, N is the sequence discrete number, β 1 is the first unwrapped sequence initial phase, and N is the predetermined sequence length, as shown in fig. 2, it is a schematic diagram of the initial sequence, the first forward sequence, and the first unwrapped sequence.
For step S107, in one embodiment, a first positive phase is obtained from the result of the quadrature mixing and integration calculation on the first forward sequence; a first anti-phase is obtained from the results of quadrature mixing and integration calculations performed on the first anti-aliasing sequence. When the mixing interference frequency of the quadrature mixing is not considered, the quadrature mixing is expressed as equation (7), and the integral calculation is expressed as equation (8):
(7)
Ω＝ωi-ωs
n＝0,1,2,.....,N-1
wherein R is+start(n) is a first positive real-frequency mixing sequence, I+start(n) is a first positive virtual audio mixing sequence, R-start(-n) is the first inverse real mixing sequence, I-start(-n) is the first inverse virtual mixing sequence, cos ([ omega ])sTn) or cos (-omega)sTn) is a discrete cosine function of the reference frequency sin (ω)sTn) or sin (-omega)sTn) is a discrete sine function of the reference frequency and omega is the signal frequency omegaiWith reference frequency omegasT is the sampling interval time, n is the sequence discrete number,is the first forward sequence initial phase, β 1 is the first forward sequence initial phase, and N is the predetermined sequence length.
(8)
n＝0,1,2,.....,N-1
Wherein R is+startFirst positive real-frequency integral value, unit dimensionless, I+startIs the first positive imaginary frequency integral value, with dimensionless units, R-startIs the first inverse real-frequency integral value, unit dimensionless, I-startIs the first inverse virtual mixing integral value, the unit is dimensionless, omega is the signal frequency omegaiWith reference frequency omegasT is the sampling interval time, N is the sequence discrete number, N is the preset sequence length,is the first forward sequence initial phase, β 1 is the first deconvolution sequence initial phase, and N is the predetermined sequence length.
In one embodiment, the calculation of the first positive phase and the first negative phase is expressed by equation (9):
wherein the pH is+startIs the first positive phase, PH-startIs a first antiphase, R+startIs the first positive real-frequency integral value, unit dimensionless, I+startIs the first positive imaginary frequency integral value, with dimensionless units, R-startIs the first inverse real-frequency integral value, unit dimensionless, I-startIs the first inverse virtual mixing integral value, the unit is dimensionless, omega is the signal frequency omegaiWith reference frequency omegasT is the sampling interval time, N is the preset sequence length,is the first forward sequence initial phase, and β 1 is the first unwrapped sequence initial phase.
For step S108, in one embodiment, the first average initial phase calculation method is expressed by equation (10):
wherein the pH isstart-avgIs the first average initial phase, PH+startIs the first positive phase, PH-startIn order to be in a first opposite phase,is the first forward sequence initial phase, and β 1 is the first unwrapped sequence initial phase.
For step S109, in one embodiment, the preset phase value may be ± pi/4; the step of obtaining a phase comparison value according to the first average initial phase and the preset phase value may include:
if the first average initial phase is greater than or equal to 0 and less than or equal to pi/2, subtracting the first average initial phase according to pi/4 to obtain a phase comparison value;
and if the first average initial phase is greater than or equal to-pi/2 and less than or equal to 0, subtracting the first average initial phase according to-pi/4 to obtain a phase comparison value.
Specifically formula (11):
wherein, △ PHcomIs the phase comparison value, in units of rad, PHstart-avgIs the first average initial phase.
In one embodiment, the new starting point is calculated as equation (12):
wherein, PnewAs a new starting point, in dimensionless units, Pstartto preset a starting point, delta PHcomFor phase comparison, in units rad, N2πIs the length of the unit period sequence, and (int) is an integer.
For step S110, the second forward sequence and the second reverse-pleated sequence are equation (13):
X-end(-n)＝X+end(N-n)＝Acos(-ωiTn+β2) (13)
n＝0,1,2,3,.....,N-1
wherein, X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PnewIs a new starting point and has no unit dimension,is the second forward sequence initial phase, β 2 is the second inverse convolution sequence initial phase, omegaiFor signal frequency, T is sampling intervalAnd N is a sequence discrete number, and N is a preset sequence length.
For step S111, in one embodiment, a second positive phase is obtained from the results of the quadrature mixing and digital filtering of the second forward sequence; a second anti-phase is obtained based on the results of the quadrature mixing and digital filtering of the second anti-aliasing sequence. I.e., the second positive phase and the second negative phase, are based on the results of the quadrature mixing and digital filtering calculations. In one embodiment, the orthogonally mixed second forward sequence and second inverse-pleated sequence may be digitally filtered by a 6-stage rectangular window arithmetic mean filter of 2 filter parameters.
When the mixing interference frequency of the quadrature mixing is not considered, the quadrature mixing is expressed as equation (14), and the filtering calculation of the 6-level rectangular window arithmetic mean filter of the 2 filtering parameters is expressed as equation (15):
(14)
Ω＝ωi-ωs
n＝0,1,2,.....,N-1
wherein R is+end(n) is a second positive real-frequency mixing sequence, I+end(n) is a second positive virtual audio mixing sequence, R-end(-n) is a second inverse real mixing sequence,I-end(-n) is the second inverse virtual mixing sequence, cos ([ omega ])sTn) or cos (-omega)sTn) is a discrete cosine function of the reference frequency sin (ω)sTn) or sin (-omega)sTn) is a discrete sine function of the reference frequency and omega is the signal frequency omegaiWith reference frequency omegasT is the sampling interval time, n is the sequence discrete number,is the first forward sequence initial phase, β 1 is the first deconvolution sequence initial phase, and N is the predetermined sequence length.
(15)
ND＝3ND1+3ND2
ND≤N
n＝0,1,2,3,....,ND-1
Wherein R is+endThe second positive real frequency digital filtering final value is a unit dimensionless; i is+endFor the second positive virtual frequency digital filter end value, unit dimensionless；R-endThe second inverse digital filtering final value is a unit dimensionless; i is-endThe second inverse virtual frequency digital filtering final value is a unit dimensionless; omega is the signal frequency omegaiWith reference frequency omegasThe frequency difference of (2); k (omega) is the amplitude gain of the digital filtering at the frequency difference omega, and the unit is dimensionless; t is sampling interval time;is the initial phase of the second forward sequence, beta 2 is the initial phase of the second inverse pleat sequence, ND1For filtering parameter 1, i.e. for ND1Adding the continuous discrete values, and then taking the arithmetic mean value of the continuous discrete values as the current filtering value to be output; n is a radical ofD2For filter parameter 2, i.e. for ND2Adding the continuous discrete values, and then taking the arithmetic mean value of the continuous discrete values as the current filtering value to be output; n is a radical ofDThe sequence length is used for digital filtering, the number of the sequence length is the sum of filtering parameters of a 6-stage rectangular window arithmetic mean filter, and the sequence length is less than or equal to a preset sequence length N.
In one embodiment, the filter parameter ND1The value is 1.5 times of the length of the unit period sequence of the reference frequency, so that the frequency mixing interference frequency generated by 1/3 subharmonic is deeply inhibited; filter parameter ND2The value is 2 times of the length of the unit period sequence of the reference frequency, so that the frequency mixing interference frequency generated by direct current, 1/2 order, subharmonic and the like is deeply inhibited. The 6-stage rectangular window arithmetic mean filter filtering calculation of 2 filtering parameters needs to use 10.5 times of the length of the signal period sequence.
Filter parameter ND1And a filter parameter ND2Calculated as formula (16):
ND1＝(int)(1.5N2π)
(16)
ND2＝2N2π
wherein N isD1Is a digital filtering parameter 1, the unit is dimensionless, (int) is an integer, ND2For the digital filter parameter 2, the units are dimensionless，N2πIs the unit period sequence length.
In one embodiment, the calculation method of the second positive phase and the second negative phase is expressed by formula (17):
(17)
wherein the pH is+endIs the second positive phase, PH-endIs a second opposite phase, R+endIs the second positive real-frequency integral value, unit dimensionless, I+endIs the second positive imaginary frequency integral value, with dimensionless units, R-endIs the second inverse real-frequency integral value, unit dimensionless, I-endIs the second inverse virtual mixing integral value, the unit is dimensionless, omega is the signal frequency omegaiWith reference frequency omegasFrequency difference of (1), T is sampling interval time, NDThe sequence length is used for the digital filtering,is the second forward sequence initial phase, and β 2 is the second unwrapped sequence initial phase.
For step S112, the second average initial phase calculation method, expressed as equation (18):
wherein the pH isend-avgIs the second average initial phase, PH+endIs the second positive phase, PH-endIn order to be in the second opposite phase,is the second forward sequencephase β 2 is the second forward sequence initial phase.
For step S113, the cosine function modulation sequence is expressed as equation (19):
n＝0,1,2,3,.....,N-1
wherein, Xcos(n) is a cosine function modulation sequence; x+end(n) is a second forward sequence; x-end(-n) is a second deconvolution sequence; PH valueend-avgA second average initial phase; a is the cosine function modulation sequence amplitude, unit v;modulating the initial phase, omega, of the sequence for the cosine functioniIs the signal frequency, T is the sampling interval time, N is the sequence discrete number, N is the preset sequence length,is the second forward sequence initial phase, and β 2 is the second unwrapped sequence initial phase.
For step S114, the sine function modulation sequence is expressed as equation (20):
n＝0,1,2,3,.....,N-1
wherein, Xsin(n) is a sine function modulation sequence, X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PHend-avgIs the second average initial phase, a is the sine function modulation sequence amplitude, unit v,the initial phase of the sequence is modulated for the cosine function,ωisignal frequency, T is sampling interval time, N is sequence discrete number, N is preset sequence length,is the second forward sequence initial phase, and β 2 is the second unwrapped sequence initial phase.
For step S115, in one embodiment, the zero initial phase reference cosine function modulation sequence is expressed by equation (21):
wherein, X0sin(n) is zero initial phase reference cosine function modulation sequence, A is cosine function modulation sequence amplitude, unit v, omegaiSignal frequency, T is sampling interval time, N is a sequence discrete number, and N is a preset sequence length.
In one embodiment, the zero initial phase reference sine function modulation sequence is expressed as equation (22):
wherein, X0sin(n) is a zero initial phase reference sine function modulation sequence, A is the amplitude of the sine function modulation sequence and the unit v, omegaiSignal frequency, T is sampling interval time, N is a sequence discrete number, and N is a preset sequence length. The zero initial phase reference point pattern is shown in fig. 3.
For step S116, the initial phaseIn the range of 0 to. + -. π/2. In one embodiment, the resulting expression for the first and second multiplication sequences is (23):
wherein X1(n) is a first multiplication sequence, X2(n) is a second multiplication sequence,as a result of the initial phase being the first phase,as a sine function of the initial phase, X0cos(n) is the zero initial phase reference cosine function modulation sequence,as a cosine function of the initial phase, X0sinAnd (N) is the zero initial phase reference sine function modulation sequence, N is a sequence discrete number, and N is a preset sequence length.
For step S117, the cosine function sequence of the initial phase is expressed by equation (24):
wherein,and the cosine function sequence of the initial phase.
Based on the same inventive concept, the invention also provides a system for acquiring any initial phase cosine function sequence from the power signal, and the following describes the specific implementation of the system in detail with reference to the attached drawings.
As shown in fig. 4, a system for obtaining an arbitrary initial phase cosine function sequence from an electric power signal includes:
a preliminary sequence length determining module 101, configured to obtain a preliminary sequence length according to a lower limit of a power signal frequency range, a preset sampling frequency, and a preset integer signal cycle number;
a preliminary sequence obtaining module 102, configured to sample an electric power signal according to the length of the preliminary sequence, so as to obtain a preliminary sequence of the electric power signal;
a reference frequency determining module 103, configured to perform frequency initial measurement on the preliminary sequence to obtain a preliminary frequency of the power signal, and obtain a reference frequency according to the preliminary frequency;
a unit cycle sequence length determining module 104, configured to obtain a unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;
a preset sequence length determining module 105, configured to obtain a preset sequence length according to the preset integer signal cycle number and the unit cycle sequence length, where the preset sequence length is an odd number;
a first sequence obtaining module 106, configured to obtain a first forward sequence from the preliminary sequence according to the preset sequence length and a preset starting point, and obtain a first anti-aliasing sequence according to the first forward sequence;
a first positive and negative phase determining module 107, configured to obtain a first positive phase according to the first forward sequence and obtain a first negative phase according to the first anti-aliasing sequence;
a first average initial phase determining module 108, configured to obtain a first average initial phase according to the first positive phase and the first negative phase;
a new starting point determining module 109, configured to obtain a phase comparison value according to the first average initial phase and a preset phase value, and obtain a new starting point according to the phase comparison value, the preset starting point, and the unit cycle sequence length;
a second sequence obtaining module 110, configured to obtain a second forward sequence from the preliminary sequence according to the preset sequence length and the new starting point, and obtain a second inverse-convolution sequence according to the second forward sequence;
a second positive and negative phase determining module 111, configured to obtain a second positive phase according to the second forward sequence and obtain a second inverse phase according to the second inverse-folding sequence;
a second average initial phase determining module 112, configured to obtain a second average initial phase according to the second positive phase and the second negative phase;
a cosine function modulation sequence determining module 113, configured to add the second forward sequence and the second inverse-pleated sequence to obtain a sum sequence, and obtain a cosine function modulation sequence according to the sum sequence and a cosine function value of the second average initial phase;
a sinusoidal function modulation sequence determining module 114, configured to subtract the second forward sequence from the second inverse-folding sequence to obtain a difference sequence, and obtain a sinusoidal function modulation sequence according to the difference sequence and the sinusoidal function value of the second average initial phase;
a zero initial phase modulation sequence obtaining module 115, configured to output from the cosine function modulation sequence center point to obtain a zero initial phase reference cosine function modulation sequence, and output from the sine function modulation sequence center point to obtain a zero initial phase reference sine function modulation sequence;
a multiplication sequence obtaining module 116, configured to set an initial phase, multiply the cosine function of the initial phase by the zero initial phase reference cosine function modulation sequence to obtain a first multiplication sequence, and multiply the sine function of the initial phase by the zero initial phase reference sine function modulation sequence to obtain a second multiplication sequence;
and an initial phase cosine function sequence determining module 117, configured to subtract the second multiplication sequence from the first multiplication sequence to obtain a cosine function sequence of the initial phase.
In one embodiment, the cosine function modulation sequence determination module 113 may determine the modulation sequence according to an expressionObtaining a cosine function modulation sequence Xcos(n) wherein X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PHend-avgThe second average initial phase.
In one embodiment, the sine function modulation sequence determination module 114 may be based on an expressionObtaining a sine function modulation sequence Xsin(n) wherein X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PHend-avgThe second average initial phase.
In one embodiment, the zero initial phase modulation sequence obtaining module 115 may obtain the zero initial phase modulation sequence according to an expressionObtaining the zero initial phase reference cosine function modulation sequence X0cos(n), wherein n is 0,1,2, 3. -,n is a discrete number of sequences, N is a predetermined sequence length, XcosAnd (n) is a cosine function modulation sequence.
In one embodiment, the zero initial phase modulation sequence obtaining module 115 may obtain the zero initial phase modulation sequence according to an expressionObtaining the zero initial phase reference sine function modulation sequence X0sin(n), wherein n is 0,1,2, 3. -,n is a discrete number of sequences, N is a predetermined sequence length, XsinAnd (n) is a sine function modulation sequence.
The multiplication sequence acquisition module 116 may be according to an expressionObtaining a first multiplication sequence X1(n), according to the expressionObtaining a second multiplication sequence X2 (n);
wherein,as a result of the initial phase being the first phase,as a sine function of the initial phase, X0cos(n) is the zero initial phase reference cosine function modulation sequence,as a cosine function of the initial phase, X0sin(n) is the zero initial phase reference sine function modulation sequence, n is 0,1,2, 3.N is a discrete number of sequences, and N is a preset sequence length.
Other technical features of the system of the present invention are the same as those of the method of the present invention, and are not described herein again.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. A method for obtaining an arbitrary initial phase cosine function sequence from an electric power signal is characterized by comprising the following steps:
obtaining a preliminary sequence length according to the lower limit of the power signal frequency range, a preset sampling frequency and a preset integer signal period number;
sampling the power signal according to the length of the preliminary sequence to obtain a preliminary sequence of the power signal;
carrying out frequency initial measurement on the initial sequence to obtain an initial frequency of the power signal, and obtaining a reference frequency according to the initial frequency;
obtaining the unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;
obtaining a preset sequence length according to the preset integer signal cycle number and the unit cycle sequence length, wherein the preset sequence length is an odd number;
obtaining a first forward sequence from the preliminary sequence according to the preset sequence length and a preset starting point, and obtaining a first reverse pleat sequence according to the first forward sequence;
obtaining a first positive phase from the first forward sequence and a first anti-phase from the first anti-aliasing sequence;
obtaining a first average initial phase according to the first positive phase and the first negative phase;
obtaining a phase comparison value according to the first average initial phase and a preset phase value, and obtaining a new initial point according to the phase comparison value, the preset initial point and the unit cycle sequence length;
according to the preset sequence length and the new starting point, obtaining a second forward sequence from the preliminary sequence, and obtaining a second reverse pleat sequence according to the second forward sequence;
obtaining a second positive phase from the second forward sequence and a second anti-phase from the second anti-aliased sequence;
obtaining a second average initial phase according to the second positive phase and the second negative phase;
adding the second forward sequence and the second inverse pleat sequence to obtain a sum sequence, and obtaining a cosine function modulation sequence according to the sum sequence and a cosine function value of the second average initial phase; wherein, according to the expressionObtaining a cosine function modulation sequence Xcos(n) wherein X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PHend-avgA second average initial phase;
subtracting the second reverse-folding sequence from the second forward sequence to obtain a difference sequence, and obtaining a sine function modulation sequence according to the difference sequence and the sine function value of the second average initial phase; wherein, according to the expressionObtaining a sine function modulation sequence Xsin(n) wherein X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PHend-avgA second average initial phase;
outputting from the center point of the cosine function modulation sequence to obtain a zero initial phase reference cosine function modulation sequence, and outputting from the center point of the sine function modulation sequence to obtain a zero initial phase reference sine function modulation sequence;
setting an initial phase, multiplying the cosine function of the initial phase by the zero initial phase reference cosine function modulation sequence to obtain a first multiplication sequence, and multiplying the sine function of the initial phase by the zero initial phase reference sine function modulation sequence to obtain a second multiplication sequence;
and subtracting the second multiplication sequence from the first multiplication sequence to obtain a cosine function sequence of the initial phase.
2. The method of claim 1, wherein the sequence of arbitrary initial phase cosine functions is derived from an electrical power signal according to the expressionObtaining a first multiplication sequence X1(n), according to the expressionObtaining a second multiplication sequence X2 (n);
wherein,as a result of the initial phase being the first phase,as a sine function of the initial phase, X0cos(n) is the zero initial phase reference cosine function modulation sequence,as a cosine function of the initial phase, X0sin(n) is the zero initial phase reference sine function modulation sequence,n is a discrete number of sequences, and N is a preset sequence length.
3. The method of claim 2, wherein the sequence of arbitrary initial phase cosine functions is derived from the power signal according to the expressionObtaining the zero initial phase reference cosine function modulation sequence X0cos(n) wherein,n is a discrete number of sequences, N is a predetermined sequence length, XcosAnd (n) is a cosine function modulation sequence.
4. The method of claim 2, wherein the sequence of arbitrary initial phase cosine functions is derived from the power signal according to the expressionObtaining the zero initial phase reference sine function modulation sequence X0sin(n) wherein,n is a discrete number of sequences, N is a predetermined sequence length, Xsin(n)The sequence is modulated for a sine function.
5. A system for obtaining an arbitrary initial phase cosine function sequence from an electrical power signal, comprising:
the preliminary sequence length determining module is used for obtaining a preliminary sequence length according to the lower limit of the power signal frequency range, a preset sampling frequency and a preset integer signal period number;
the preliminary sequence acquisition module is used for sampling the electric power signal according to the length of the preliminary sequence to obtain a preliminary sequence of the electric power signal;
a reference frequency determining module, configured to perform frequency initial measurement on the preliminary sequence to obtain a preliminary frequency of the power signal, and obtain a reference frequency according to the preliminary frequency;
a unit cycle sequence length determining module, configured to obtain a unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;
a preset sequence length determining module, configured to obtain a preset sequence length according to the preset integer signal cycle number and the unit cycle sequence length, where the preset sequence length is an odd number;
a first sequence obtaining module, configured to obtain a first forward sequence from the preliminary sequence according to the preset sequence length and a preset starting point, and obtain a first anti-aliasing sequence according to the first forward sequence;
a first positive and negative phase determination module for obtaining a first positive phase from the first forward sequence and a first negative phase from the first deconvolution sequence;
a first average initial phase determining module, configured to obtain a first average initial phase according to the first positive phase and the first negative phase;
a new starting point determining module, configured to obtain a phase comparison value according to the first average initial phase and a preset phase value, and obtain a new starting point according to the phase comparison value, the preset starting point, and the unit cycle sequence length;
a second sequence obtaining module, configured to obtain a second forward sequence from the preliminary sequence according to the preset sequence length and the new starting point, and obtain a second inverse-folding sequence according to the second forward sequence;
a second forward-reverse phase determination module, configured to obtain a second positive phase according to the second forward sequence and obtain a second reverse phase according to the second deconvolution sequence;
a second average initial phase determining module, configured to obtain a second average initial phase according to the second positive phase and the second negative phase;
a cosine function modulation sequence determining module, configured to add the second forward sequence and the second inverse-pleated sequence to obtain a sum sequence, and obtain a cosine function modulation sequence according to the sum sequence and a cosine function value of the second average initial phase; wherein, according to the expressionObtaining a cosine function modulation sequence Xcos(n) wherein X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PHend-avgA second average initial phase;
a sinusoidal function modulation sequence determining module, configured to subtract the second forward sequence from the second inverse-folding sequence to obtain a difference sequence, and obtain a sinusoidal function modulation sequence according to the difference sequence and a sinusoidal function value of the second average initial phase; wherein, according to the expressionObtaining a sine function modulation sequence Xsin(n) wherein X+end(n) is a second forward sequence, X-end(-n) is the second deconvolution sequence, PHend-avgA second average initial phase;
the zero initial phase modulation sequence acquisition module is used for outputting from the center point of the cosine function modulation sequence to acquire a zero initial phase reference cosine function modulation sequence and outputting from the center point of the sine function modulation sequence to acquire a zero initial phase reference sine function modulation sequence;
a multiplication sequence obtaining module, configured to set an initial phase, multiply the cosine function of the initial phase by the zero initial phase reference cosine function modulation sequence to obtain a first multiplication sequence, and multiply the sine function of the initial phase by the zero initial phase reference sine function modulation sequence to obtain a second multiplication sequence;
and the initial phase cosine function sequence determining module is used for subtracting the second multiplication sequence from the first multiplication sequence to obtain the initial phase cosine function sequence.
6. The system according to claim 5, wherein said multiplication sequence obtaining module obtains any initial phase cosine function sequence from the power signal according to the expressionObtaining a first multiplication sequence X1(n), according to the expressionObtaining a second multiplication sequence X2 (n);
wherein,as a result of the initial phase being the first phase,as a sine function of the initial phase, X0cos(n) is the zero initial phase reference cosine function modulation sequence,as a cosine function of the initial phase, X0sin(n) is the zero initial phase reference sine function modulation sequence,n is a discrete number of sequences, and N is a preset sequence length.
7. The system according to claim 6, wherein the zero initial phase modulation sequence obtaining module obtains the arbitrary initial phase cosine function sequence from the power signal according to the expressionObtaining the zero initial phase reference cosine function modulation sequence X0cos(n) wherein,n is a discrete number of sequences, N is a predetermined sequence length, XcosAnd (n) is a cosine function modulation sequence.
8. The system according to claim 6, wherein the zero initial phase modulation sequence obtaining module obtains the arbitrary initial phase cosine function sequence from the power signal according to the expressionObtaining the zero initial phase reference sine function modulation sequence X0sin(n) wherein,n is a discrete number of sequences, N is a predetermined sequence length, XsinAnd (n) is a sine function modulation sequence.
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